Control Philosophy_Rev 5

Control philosophy _ JSPL Pellet Plant-II

Page 1 of 106

SPECIFICATION

Department: Control Systems

Document No: I010S

Document Title: CONTROL PHILOSOPHY

PROJECT REFERENCE 3 Project No.: TS120100 Project Location: Barbil, Odisha, India. Project Title: Iron Ore Pelletizing Plant II Client: Jindal Steel and Power Ltd.

PM Authorisation: Date: 13th July, 2013 Client Authorisation: Date:

APPROVALS Rev Issue Date Revision Description Prepared Checked Disp.App Proj. App

0 16 Oct 2012 Issued for Design JR RC RC TC 1 20 Nov 2012 Issued for Design KT RC RC TC 2 28 Nov 2012 Issued for Design KT RC RC TC 3 6 Mar 2013 Issued for Design JR RC RC 4 25 June 2013 Revised in line with Vendor Control

Philosophy SSG SD JS CPn

5 13 July 2013 Revised in line with discussion with JSPL SSG SB JS CPn

Entire Document DOCUMENT ISSUED FOR: Issued this Revision In-house Review Purchase

Revised Pages Only Client Approval Construction Issued this Revision Enquiry Tender

Copyright 2010 by Jacobs Engineering Group Inc. All rights reserved. The contents of this document are proprietary and produced for the exclusive benefit of Jacobs Engineering Groups Inc. and its affiliated companies. No part of this document may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written approval of Jacobs Engineering Group Inc.

Project No. TS120100 Revision 5 Document Title. CONTROL PHILOSOPHY Page 2 of 106 Document No. I010S Date 13 July 2013


TABLE OF CONTENTS

1.0 INTENT OF THE DOCUMENT

2.0 CONVENTIONS

3.0 IRON ORE RECEIVING & WET GRINDING SECTION- AREA 1

4.0 ADDITIVE RECEIVING AND DRY GRINDING -AREA 2

5.0 MIXING AREA 3

6.0 BALLING AREA 4

7.0 INDURATING AREA 5

8.0 PRODUCT SCREENING AREA 6

9.0 POLLUTION CONTROL AREA 7

10.0 UTILITIES AREA 8

11.0 CONTROL SYSTEM OVERVIEW & PHILOSOPHY

12.0 ANNEXURE I PID LOOP LIST



1.0 INTENT OF THIS DOCUMENT

This document describes the control system for iron ore pelletizing facility, based on the Dravo Traveling Grate Process, located at the site of Jindal Steel and Power Limited (JSPL) in Barbil, Odisha, India. This plant is designated as JSPL Pellet Plant 2 and is located adjacent to the existing JSPL Pellet Plant 1.

Specific vendor document for equipment/package is used as a basis to provide detailed philosophy.

The pellet plant is conceived as a versatile operation capable of producing a variety of product types, as predicated by the ore supply and/or the consumer demand. Thus, from time to time, campaigns may be run to produce varieties ranging from acid pellets to fluxed pellets.

The pellet plant conveyors and hardware will be mechanically designed to handle 4,500,000 direct reduction grade (DR-grade) ore pellets per year in 330 days of operation (7,920 scheduled hours per year), taking into account all design safety factors. Actual indurating capacity is dependent upon the specific ore being utilized, the type of pellets being produced, and quality specifications of the consumer.

Total plant availability is dependent upon the specific operating and maintenance practice employed at the site. JSPLs target production is 4,000,000 tonnes per annum of fired pellets.

2.0 CONVENTIONS

The sections on control philosophy for each area include references to Loops with associated numbers. These loops are instrument loops identified by number on the Piping and Instrumentation Diagrams (P&IDs).

3.0 IRON ORE RECEIVING & WET GRINDING SECTION- AREA 1

3.1 Iron Ore Receiving (P&ID: R-01-1001)

Blended Iron ore is delivered by owners blended ore conveyor directly onto the Ore Concentrate Conveyor OF-11 (B43001D). OF-11 discharges blended ore on conveyor OF-12 (B43001C). OF-12 delivers ore to OF-13 (B43001B) and finally OF-13 delivers on shuttle conveyor OF-14 (B43001A), which in turn feeds to Ball mill feed bins (B43510-1&2). Conveyor OF-11, 12, 13 and OF-14 are equipped with standard conveyor control packages for this project. Each conveyor is equipped with adequate safety switches.

The receiving rates for wet iron ore to the ball mill feed bins at 8% H2O (by weight) are:

Operating : 590 TPH Design : 2000 TPH

Each Ball mill feed bin has a four (4) hour design storage capacity.

Individual start-up of blended ore conveyors OF-11, 12 &13 and shuttle conveyor OF-14 will depend on healthy signal from the safety switches placed on the conveyors.

Group start up will depend on the level signal from level transmitters placed over bins. Low (20%) signal from bin level transmitters will start shuttle conveyor OF-14 first followed by blended ore conveyors OF-13, OF-12 & OF-11 sequentially, provided there is healthy signal from safety switches of these conveyors.

The unidirectional Ore Concentrate shuttle conveyor OF-14 feeds the Ball Mill Feed Bin2 (B43510-2) when positioned under the discharge of blended ore conveyor (OF-13). The shuttle car is fitted



with a chute at the back end. When Bin-2 is full (High alarm), OF-14 moves ahead and the chute fitted with the shuttle car comes in line with the discharge chute of OF-13 and Bin-1 starts getting filled up.

The filling of each bin will be controlled by the level transmitter High & Low Set points. The position for the shuttle car filling BIN-01 directly will be determined by a limit switch installed corresponding to desired position which will stop the shuttle car motor. On receipt of H signal (70%) from Bin-01 the shuttle car starts traveling to fill Bin-02. After receipt of H signal from any of the bins if the shuttle car fails to move to the other bin due to any reason within 2 minutes the shuttle conveyor will stop and subsequently all upstream conveyors will stop sequentially.

H-H alarm (90%) from both bin level transmitters and/or unhealthy signal from any conveyor safety switch will stop up-stream conveyors in a sequential manner.

There are 2 weigh belt feeders WF-1 and WF-2 (B55201-1, 2) (Loop No: WIC-01B0107 & WIC-01B0117, P&ID: R-01-1001) located under Ball Mill Feed Bins-1 & 2 respectively. The weigh belt feeders feed blended ore to respective ball mill feed conveyors BMF-1 & BMF-2 (B43002-1&2).

Group start-up of weigh belt feeders and mill feed conveyors will depend on the following factors:

Healthy signal from the safety switches placed on the conveyors Ball mill (B46201 / B46202) is running Low-Low alarm not present at the respective bin.

The feed rate set point to the weigh feeders is from the Ball Mill Specific Energy Consumption (JIC-01B0206, JIC-01B0506, P&ID: R-01-1002 & R-01-1005). Ball mill feed set point is based on mill specific energy, kWh/T as formulated below:

Feed (TPH) = (Mill kWh per h) / (Mill kWh per T)

Mill Specific energy will be set by an operator at 12.5 (Constant) [Refer P&ID: R-01-1001, Note-5]

The action on a bin alarm of low-low (5%) is to stop the belt weigh feeder (B55201-1, 2) under the bin. This will prevent the bin emptying out with the consequential damage to the belt weigh feeders caused by material falling from the top of the bin directly on them.

Stopping of weigh belt feeders and mill feed conveyors will depend on the following factors:

Unhealthy signal from the safety switches placed on the conveyors Ball mill stops Low-Low alarm at the respective bin

HH, H, and LL, L set points are indicative only and will be finalized by the commissioning engineer.

3.2 Shutdown

Prior to a planned shutdown the decision must be made as to whether or not to empty off all or any of the conveyors. This decision will determine the sequence and timing of each conveyor shutdown. The units are designed so they can be safely be restarted if stopped under full load.

3.3 Wet Grinding System (R-01-1002, 1003, 1004, 1005, 1006 & 1007) (Inputs received from package vendor FLSmidth)

3.3.1 Process Description

Wet Grinding System is a dual motor driven Ball Mill with Hydrocyclone in a closed loop circuit.



Iron ore feed size of -12mm (F100) with moisture content 8% is fed into the ball mill in a controlled rate .Water added at the ball mill inlet to cater to grinding and to maintain the consistency in percentage solids at the trommel discharge. The discharge from ball mill is pumped to a classifying Hydrocyclone for separating -70 to -75 microns fractions (P80). The oversize will be recycled to Ball Mill for further grinding. The Product will be collected from the Hydrocyclone over flow.

Hydrocyclone underflow is taken as a recycle into ball mill feed, this forms the closed circuit. Required dilution water through flow control valves FV0021/FV1021 can be added to the slurry tank to maintain density of slurry to the Hydrocyclone (Loop No: FIC-B01-0020 / FIC-B01-1020, P&ID: R-01-1003 / R-01-1006)

A flow transmitter FIT0037 / FIT1037 and Density meter DIT0036 / DIT1036 (Loop No: DIC-B01-0036 / 1036, P&ID: R-01-1003 / R-01-1006) is provided in the discharge of the slurry pumps (331.PU210/B41101-1, 2 / 3, 4) to maintain the slurry density and flow rate to the Hydrocyclone. The readings of the same will be available at the Main Automation System. A Flow control valve FCV0044 / FCV1042 located in the ball mill feed water pipe to ensure proper control on the water addition to mill (Loop No: FIC-B01-0042 / 1040, P&ID: R-01-1002 / R-01-1005).

Protective trips/alarms for the mill motor, lubrication system etc would be actuated from the Main Automation System. A local control panel monitors girth gear pinion grease lubrication system. Main Automation System obtains only healthy and unhealthy signals from the Girth gear local control panel. However, the start/ stop command can be initiated from the Main Automation System.

3.3.2 Normal Start-up Sequence

This section describes the functional group startup sequence. If the group has an automatic start sequence, time delays between equipment will also be listed. Any group preconditions required prior to startup are also listed herein. However, interlocks required for individual or predefined groups of equipment are listed in the Interlocks section.

3.3.3 Normal Operation

This section describes the functional group normal operation, including operator functions. There are three modes of operation, as described below:

Automatic

Automatic mode is when functional groups are controlled automatically and in sequence by the equipment control system. A functional group is a set of items such as motors, valves, etc. which are started by a single operator action when in Automatic Mode. All Protective, Safety, Machine, Operational and Start Interlocks must be met in order to operate.

Manual

Manual mode is when items such as motors, valves, etc. are controlled individually by the operator using the equipment control system. Functional groups have no meaning in Manual Mode. All Protective, Safety, and Start Interlocks must be met in order to operate.

Local

Local mode is when items such as motors, valves, etc. are controlled individually in the field, usually by local pushbutton stations located near the equipment. Functional groups have no meaning in Local Mode. Since the operator interface in Local Mode is often physical devices rather than a display screen, extra care must be taken to ensure that interlocking continues to be enforced. All Protective, Safety, and Start Interlocks must be met in order to operate.



Main Automation System Control

Commands to operate the equipment control system are made by an operator using the Main Automation System HMI. The Main Automation System can only operate equipment in Automatic Mode.

3.3.4 Normal Shutdown Sequence

This section describes the group shutdown sequence. If the group has an automatic shutdown sequence, time delays to allow for equipment cleanout or deceleration will also be listed.

3.3.5 Abnormal and Emergency Shutdowns

This section describes abnormal shutdown conditions caused by isolated process or equipment abnormalities or activation of individual equipment safety devices. It also describes emergency shutdowns due to automatic activation of personnel safety systems or field emergency stop pushbuttons.

3.3.6 Interlocks

The Interlocks section describes all interlocks for the individual equipment or functional group of equipment within the associated software function group. Interlock is defined herein as an input/output signal or a Main Automation System/Main Automation System internal logic condition, which automatically prevents the operation of an individual or functional group of equipment from the Plant Main Automation System HMI. When the condition of an interlock(s) is such that operation of a related piece of equipment or an equipment group is permitted, the interlock(s) is defined as being satisfied.

Specific devices in the Interlock table may be preceded by NOT. This is the condition for the analog threshold (i.e. NOT Bearing Temperature High-High = Bearing Temperature is NOT ABOVE the High-High Set point). However, in the case of discrete switches the Interlock is stated from the ON perspective of the switch. For example the Oil Reservoir Low switch is ON when the oil level is NOT Low (fail-safe), so the required interlock in the switch being true.

Interlocks consist of five types and are described in detail below:

Safety interlocks:

Safety interlocks are those interlocks which prevent damage to that associated piece of equipment. As a result, safety interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

Safety interlock for a pump would be no high-high bearing temperature.

Safety interlocks for every motor will also include the MCC/motor ready signal and receipt of a run confirmation from the motor contactor after a run command is sent. These interlocks apply to all motors and are not listed in the interlock table for this reason.

Start interlocks:

Start interlocks are those interlocks necessary ONLY for starting the machine. As soon as the motor is running the start interlock has no influence. As a result, start interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

A start interlock for a fixed speed fan with automatic damper would be that the damper be closed (limit switch or position transmitter) prior to starting.



Protective Interlocks:

Protective interlocks are those interlocks for the protection of the motor itself. As a result, protective interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

A protective interlock for an equipment motor would be motor bearing temperature or motor winding temperature.

Machine Interlocks:

Machine interlocks are those interlocks for the protection of the machine that is operating in Automatic Mode. As a result, machine interlocks apply only when operating in Automatic Mode.

Example

A machine interlock for a belt conveyor would be a belt drift switch.

Operational Interlocks:

Operational interlocks are those interlocks that are related to the process, but not to the equipment, that is necessary for the normal operation of the item. As a result, operational interlocks apply only when operating in Automatic Mode.

Example:

An operational interlock would be downstream equipment running.

3.3.7 Overview

The mill plant incorporates the following features: Feed system (Described in section 3.1)

Ball mill

Hydrocyclone

Product Slurry system

3.3.7.1 Ball mill

Iron ore size reduction is carried out in the Ball mill. Water spray system is installed on the discharge chute for cleaning the trommel screen and process water addition is installed at the feed chute to maintain the percentage solids consistency. Temperature Scanner at the feed end and discharge end measures the inlet and outlet mill bearing temperature. Slurry from the trommel discharge is transported to Slurry Tank. The mill is equipped with internal liners and the balls are charged in different size.

The efficiency of wet grinding action depends mainly on the solids present in the feed slurry to the Ball mill. The Ball mill outlet is fed to hydro cyclone through slurry pumps for coarser and finer classification.

Trommel screen functions for the removal of grinding media scats and tramp oversize material from mill discharge slurry which fed into mill discharge tank. Mill scats are then discharged to the area below mill and are manually shoveled.

3.3.7.2 Hydrocyclone

Hydrocyclone are density separators that convert pressure energy into rotational momentum. The rotational momentum provides the centrifugal force to classify solids from slurry. Separation efficiency is determined by the Hydro cyclone geometrical parameters. The interaction between parameters dedicates the Hydro cyclone efficiency.



In operation, pressurized slurry is fed to the Hydro cyclone and the centrifugal force generated causes the heavier suspended solids to move toward the wall while the radial velocity forces the liquid and lighter gravity solids to move inward toward the central axis. Primary and secondary vortex develops. The primary vortex carries the solids to the apex. The apex orifice permits the heavier solids and a small amount of the liquor to be discharged. A secondary developing vortex carries the cleaned primary liquid (liquor) and light gravity solids out through the Vortex Finder Tube.

The performance of the hydro cyclone is based on the particle size distribution of the cyclone overflow. The underflow slurry from the hydro cyclone is fed in to the ball mill. The hydro cyclone overflow is fed to the Thickener Feed Well by gravity.

3.3.7.3 Product Slurry System

Each grinding mill will have a dedicated mill discharge slurry pump tank which collects the ground iron ore slurry from the mill. Each slurry pump tank with conical bottom, is of approximately 50 m3 capacity. The tank base will preferably be above grade level. Water addition to the Ball Mill Slurry Tank is to control the Density of the slurry being fed to the Hydro Cyclone which is monitored by density meter at the slurry pump discharge. This is controlled by a Control Valve in the Water Addition Line to the slurry tank. Slurry Pumps are equipped the Variable speed drive to maintain consistent pressure in the Hydro Cyclone for better classification and the slurry tank is equipped with Level transmitter to maintain level in tank.

3.3.8 Operation Philosophy and Plant Sequencing

Starting of the mill system is divided into a number of groups. Each drive/ equipment/ Valves in a particular group has a specified sequence of operation. Each group in itself has a specified sequence of operation during start and stop. This means that no equipment can be started before the subsequent equipment has been started. Inversely, stop of any equipment will cause the stop of the preceding equipment, unless until specified herein.

This section outlines the division of groups; the basic terminology used in numbering of the groups, sequential Interlocks between groups and between equipment/ drives/ Valves in every particular group.

This section basically outlines the various process Interlocks that are to be satisfied for successful operation of a sequence. The operator has to ensure that the power source, remote selection etc., are properly ensured. In case, the same has not been ensured, the HMI would initiate the respective alarms as described in the earlier section(s)/ sub section(s).

The philosophy goes into details on the various process related Interlocks and sequences only. Zero speed switch indication has not been included due to the commonality to all drives. Interlocks like pull chord switch, belt sway switch, instrument air pressure etc, and are not included in the write up.

General Notes:

a. Temperature, pressure, flow, level and any other process parameter set point will be adjusted and set during commissioning. Access to the set point is provided only for Engineers and not for the Operators.

b. For all the analog inputs, trends are configured in the Main Automation System.

c. Pressure switch is provided in the discharge line of all Slurry pumps for monitoring low pressure alarm in the Main Automation System.

d. Considering the safety of the equipment, the AUTO changeover of any drives is not permitted in the mill.

e. During the Re-start of the plant after the power failure, the operator has to ensure that the mill drive is ready for operation before starting the mill discharge tank group and Hydro cyclone group to avoid overflow of slurry at the mill feed end and discharge end. (After starting the



Hydro cyclone and Mill discharge tank group, the mill drive has to be started immediately).

f. After ensuring that the utilities are ready the operator initiates the starting of the plant.

3.3.9 Equipment Grouping

The various sections of the wet grinding circuit are assigned group numbers to assist the definition of discrete areas. Groups can be started up individually in preparation for overall plant start-up. These numbers will also be used for plant start-up and commissioning planning activities. Details of the groups are included in the relevant sections.

The total process is broken down into four discrete groups to allow for easy description of the facilities. These are as follows:

Group 1 Slurry Classification Group 2 Ball mill Lubrication Group 3 Ball Mill

Group 4 Ball mill Feed

3.3.10 Slurry Classification Group-1 (P&ID: R-01-1003, R-01-1004, R-01-1006, R-01-1007)

3.3.10.1 Group description:

The ground product from the ball mill discharges into the slurry tank (331. TK200/B35101-1).Slurry tank is provided with a level transmitter LT0023 to monitor and maintain the level with the slurry pump speed control.

Pair of slurry pumps (331.PU210/331.PU220/B41101-1, 2), (one operating and the other stand by) are located adjacent to the tank transport the slurry to the Hydro cyclones. Both slurry pumps are provided with Variable frequency Drive (VFD).

A low level in the tank (331.TK200/B35101-1), (LAL0023 set at 20%) inhibits the starting of the slurry pumps. A low low level in the tank (331.TK200 /B35101-1),(LALL0023 set at 30%) is used to trip the Hydro cyclone feed pumps. The normal operating level is expected to be 65%.Slurry pump speed shall be varied to maintain the targeted level.

Slurry is classified for fines and coarse in a cluster of hydro-cyclone (331.HN300/B45801-1,2,3,4).Slurry is distributed to individual cyclones from a common feed distribution manifold. Pressure transmitter PT0039 located on the hydro cyclone manifold monitors inlet pressure of feed slurry.

Consistent pressure is maintained for efficient classification in the hydro-cyclone. There are four cyclones in the cluster. Typically, at rated production one cyclone remain as a spare with all other cyclones on line. At lower capacity operation it might be necessary to reduce the number of cyclones in operation to maintain the desired pressure to achieve targeted classification. The field technician can add or reduce the number of cyclones in operation by opening or closing the cyclone feed valve.

Overflow and underflow from the hydro-cyclone cluster discharges into common overflow and underflow launders respectively. The overflow product slurry is sent through pipeline to the storage tank and flows by gravity.

Coarse underflow Slurry is discharged into the ball mill for further grinding to target fineness.

Transmitters FIT0037 and DIT0036 measure the flow and density of the slurry as fed to the hydro-cyclones respectively. The hydro cyclone feed slurry percent solid is maintained at 55% w/w by adding water to the slurry tank. Water addition is controlled via the automated flow control valve FCV0021.



3.3.10.2 Group-1 Equipment summary:

The operator can select only one slurry pump at any point of time. Selection of a pump would automatically de-select the other pump from operation. By default slurry pump (331.PU210/B41101-1) is selected for operation.

a. Suction and Discharge valves (XV0025)for(331 PU210/B41101-1)

b. Suction and Discharge valves (XV0024)for(331 PU220/B41101-2)

c. Hydro cyclone feed pumps (331.PU210/331.PU220/B41101-1,2)

3.3.10.3 Group-1 starting sequence:

The SCG group is a single drive group slurry pumps. By default (331. PU210 /B41101-1) pump is selected for operation. A start command to the SCG group starts the selected pump (331.PU210/331.PU220/B41101-1, 2).

a. Open discharge knife gate valve XV0034/0035 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

b. Open suction knife gate valve XV0025/0024 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

c. Start the slurry pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

It will be the responsibility of the Control room operator to confirm from the field technician that the gland seal water line valve of the selected pump is open and drain valves of the selected pump are closed and stand by pump is open before embarking a start command. A knife gate valves is provided at the discharge of the pumps to isolate the non-operating pump.

3.3.10.4 Group-1 Starting interlocks:

The following general interlocks are valid for starting SCG Group.

a. A level low alarm LAL0023 (set at 30%) on the tank (331.TK200/B35101-inhibits starting of the selected slurry pump.

b. Open Limit switch of the suction and discharge valves (ZSO 0024/0025) and (ZSO0034/0035) is healthy for the selected pump.

3.3.10.5 Group-1 Running interlocks:

a. A level low low alarm, LALL0023 (Set at 20%) on the tank (331.TK200/B35101-1) inhibits running of the selected slurry pump.

b. Open Limit switch of the suction and discharge valves (ZSO 0024/0025) and (ZSO0034/0035) is healthy for the selected pump.

3.3.10.6 Group-1 stopping sequence:

A stop command initiates a stop of the operating selected slurry pump.

a. Stop the selected slurry pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

b. Close limit (ZSC0034/0035) healthy for discharge knife gate valve XV0034/0035 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

c. Close limit (ZSC0024/0025) healthy for suction knife gate valve XV0025/0024 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2).

It will be the responsibility of the control room operator to confirm from the field technician that the gland seal water line valve of the selected pump is closed and drain valves of the selected pump are opened and flush the casing and discharge line of the selected pump.



3.3.11 Ball Mill Lubrication Group 2

This group is divided into following functional groups for easy operation and logical control.

1. Ball Mill Main Lubrication system Group 2A

2. Main Gearbox Lubrication system Group 2B

3.3.11.1 Ball Mill Main Lubrication system Group 2A (P&ID: R-01-1009, R-01-1010)

3.3.11.1.1 Group Description:

The mill lubrication system (331.LQ110) consists of 3 parts:

Reservoir assembly and oil conditioning circuit;

HP hydrostatic bearings lube circuit;

Pinion bearings LP lube circuit.

Reservoir Assembly & Oil Conditioning

Capacity of the Reservoir is 2310 litres. Tank utilises the drain lines from the bearing housings to return the "dirty hot oil" back to tank by gravity. This passes through a basket strainer which is accessible through a hinged inspection door, for on-line inspection and cleaning.

The sump tank is a 3 compartment design,

1. Return oil

2. Settling

3. Clean compartments.

The clean compartment is approx. 710 litres (3 minutes retention) and the balance 1600 litres in the dirty side (6 minutes retention). The correct oil temperature in the sump tank is maintained by 3 kW heater elements (3 Nos), monitored by Temperature transmitter (TT4033). Heaters operate between sump oil temperatures of 32 38C. The dirty compartment temperature transmitter is indicative and for heater control only. Two oil level transmitters (LT4032/38) are also interlocked for oil level monitoring.

Oil level sight glasses fitted to the tank gives visual indication of oil level & temperature (LG4034/36 & TG4035/37). Air breather / filter allow clean air to enter the tank. 3 (nos) BSP drain valves plugs are available to drain the tank, when required. Access to the tank internals is gained by removing the tank lid and removal of the man-hole cover, which are bolted down.

The LP conditioning circuit is fitted with 2 LP oil gear pumps LP (One Working & One Standby), driven by an 18.5 kW TEFC electric motor, fitted with integral pressure relief valves, set at 10 bars. Suction is isolated from the tank via a butterfly valve; discharge end isolated via both a non return valve and ball valve.

The LP oil flow rate is approx. 430 lpm, which is supplied to the oil conditioning circuit and the pinion bearings and returned to tank as a closed loop system via the over-flow and pinion brgs drain line.

A pressure gauge (PG4009) & pressure transmitter (PT4011), oil flow (FIT4010) and temperature transmitters (TT4008) in the line confirms that the conditioning circuit is functional, allowing the use of the pinion LP & hydrostatic HP pumps.

The dirty & hot oil" from the sump tank settling compartment is pumped to a high capacity LP duplex filter and thereafter to a Plate Heat Exchanger (PHE). The duplex filter unit is fitted with 2 filter clogged visual indicators and a common indicating differential pressure transmitter



(DPIT4023),which indicates to "change-over and clean filter unit on-line, thereafter, allowing the artisan to isolate the clogged filter housing ( close both butterfly valves ) and to replace the clogged filter element with a new unit, resetting the visual indicator, re-opening the isolating butterfly valves after completion, bleeding and equalising the filter housing pressure, which is now ready for use.

A Manual valve Controls the water flow rate through the cooler, maintaining a constant oil temperature exiting the cooler of 47C. Temperature gauges (TG4022) before and after(TG4006) the cooler give visual indication of the water and oil temperature across the cooler. The temperature transmitter (TT4008) fitted to the cooler oil exit line, interlocked to raise an alarm if the oil Temperature exceeds 520C.

The conditioned oil (clean & cool oil) exits the cooler and a bleed line return back to the sump tank clean compartment (414 lpm). Clean compartment oil level and temperatures (level LT4038> 90% and oil temp TT4039> 380C) shall meet to start the HP pumps. The conditioning pump should run continuously, even when the mill is stopped.

High Pressure Hydrostatic Oil Lube

The HP oil is pumped to the mill bearings via a 4 port flow divider, as follows: FE (Feed End) bearing at 118 lpm; 59 lpm per pocket

DE (Discharge End) bearing at 118 lpm; 59 lpm per pocket

HP Pressure gauges, HP pressure transmitters (PT 4050/ 53/ 56/ 59), HP flow transmitter (FIT4038) exist to monitor and inter-locked. The oil flow rates are balanced using rotary geared flow divider to achieve the correct flow rates to the various bearing pockets. The HP tandem gear pumps HP 01 /02 (One Working & One Standby) are isolated from the sump tank by ball valves, and protected against over-pressure by an individual pressure relief valve, set at 103 bar. Non return and ball valves isolate the pump feed lines, and a pressure gauge, oil flow transmitter are fitted for visual and MAIN AUTOMATION SYSTEM interlocking for HP system pressure. The 2750 kW TEFC mill main motors will be tripped if the pressure drops below 25 bar or oil flow drops



3.3.11.1.3 Group 2A Start sequence

Start command of the Group 2A initiate the following sequence

a. Start heater HE 01

b. Start heater HE 02

c. Start heater HE 03

Note: Start the above sequence if the oil temperature is 520C for running HP01 or HP02.

e. Flow low-low alarm(FI 4014/4016/4018/4020)(Set at (34lpm) alarm is generated, if any of the pinion lube line oil flow low low alarm FITS (3lpm) is not true then mill main motor trips.

f. Flow low-low alarm FI4048 (Set at



d. Stop mill main motor.

e. Stop the running HP pump, either HP01 or HP02

f. Stop the running LP pump, either LP01 or LP02

3.3.11.2 Main Gearbox Lubrication system Group 2B (R-01-1011, R-01-1012)

The ball mill main gear reducer is lubricated utilizing a forced lubrication system.

The reducer lube system 331.LQ145 contains an oil reservoir. Two oil-circulating pumps 331.GB 01/02 (one working + one standby) are utilized for oil circulation inside the reducer. An oil-water cooler is provided in the downstream to cool the oil before entering the main reservoir.

The pressure of oil to the gearbox lubrication system and the oil circulation pump discharge line will be monitored by the pressure switches PSL4081. TemperatureTG4080 and pressure gauges PG4083 are provided in the line for local display. The discharge piping of the pump is connected to a differential pressure switch DPSH4084 monitors the pressure drop across the filter unit. The switch provides an input to the control system to alarm on high-pressure drop across the filter alerting the operator to change the filter.

The pumps used for oil recirculation, in case failure of main pump auxiliary shall be manually started by the standby pump and will trip the working pump by the low pressure switch PSL is activated will trip the oil pump.

3.3.13 Ball Mill Group 3 (P&ID: R-01-1002, R-01-1005, R-01-1010, R-01-1012)

3.3.12.1 Group description:

Ground ore from the Ball mill (331.BM100/B46201) discharge to the tank (331.TK200/B35101-1) and pumped through slurry pumps (331.PU210/B41101-1) to the hydro cyclone cluster (331.HN300/B45801-1, 2, 3, 4) for classification.

Ball mill Inching Mode

It is to be noted that inching drive engage or disengage status has also to be monitored locally. A proximity Switch (ZSC0017) is provided in the jaw clutch coupling to ensure the disengage before the start-up of the mill main motor.

3.3.12.2 Group 3 equipment summary:

a. Ball mill Main Drive 331.MD 135/140

b. Ball mill grease spray system 331.GS137

3.3.12.3 Ball Mill Girth-gear grease spray system Group

Prior to mill start up, the Main Automation System should have a healthy signal from the grease drum low level switch.

As soon as the mill main motor runs, the Main Automation System will energises the 3/2 way air solenoid valve which operates the pneumatic grease pump, and a monitoring timer is activated. The grease is pumped through the grease strainer via the tubing to the Master distributor, splitting the flow equally to the 2 Slave distributors, which in turn discharges fixed quantities of grease into all 10 nozzles. Once this cycle is complete, the indicator pin on the slave distributors will activate the limit switches (ZS4064/71), which re-sets the monitoring timer and the Main Automation System will energise the 2/2 way air spray solenoids for a set time period (time required for the mill to do 1 full revolution, approx. 4 sec. plus time required complete the 7 distributor cycles)

The air pressure switches (PSL4062) in the air line will confirm to the Main Automation System that the solenoid valves are operational and that the plant air pressure is sufficient. The grease pump runs for the duration of the set pulses, pulsed by the distributor limit switches ZS. As soon as the



pulses are complete, i.e. 7 pulses, the Main Automation System will de-energise the pump solenoid valve and the system is put on PAUSE for a set time period (10 minutes).

The above cycle will be repeated as long as the mill runs. The indicator pin will not activate the limit switches if:

no grease flow to the nozzles occurs

the nozzles are blocked

the pipeline is broken / blocked

the distributor and/or limit switch is faulty

the grease strainer is blocked

The air pressure switch PSL4062 will fail to signal the Main Automation System if the 2/2 way solenoid valve is faulty, or if the plant air pressure is low or off line. The pressure gauge gives visual indication of the system air & grease pressure. The pump should trip if no pulses are generated from the distributors, or the air pressure switches are not activated. The mill should then also trip.

3.3.12.4 Group 3 starting Sequence:

Start command of the Group 3 initiate the following sequence

a. Start Lube System 331.LQ110

b. Start Ball mill main motors 331. MD 135 & 140.

c. Start the Grease spray system 331.GS137.

d. Start Reducer Lube system 331.LQ145

3.3.12.6 Group 3 starting interlocks:

The ball mill 331.BM100 can start if the following conditions are met:

Pinion bearing temperature TI0018 high alarm not true (Set at 800C)

Feed end trunnion bearing temperature TI0011 high alarm not true (Set at 60oC)

Discharge end trunnion bearing temperature TI0019 high alarm not true (Set at 600C)

Mill main bearing lubrication system 331 LQ110 operation is valid for a minimum period of 600 seconds prior to start of mill drive

Mill main motor gearbox lubrication system 331 LQ145 operation is valid for a minimum period of 600 seconds prior to start of mill drive

Motor bearing temperature T1 0014/0004 high alarm not true (Set at 650C) Motor winding temperature T1 0012/0006 high alarm not true (Set at 650C) Mill discharge slurry tank 331.TK200 level LAH0023 high alarm not true

Grease spray system false alarm is not present.

Inching Drive (ZSC0017) engaged limit is not true.

3.3.12.6 Group 3 running interlocks:

The ball mill (331.BM100/B46201) can remain in operation if the following conditions are met:

Mill bearing lube oil pumps is in valid operation.

'Low Low oil reservoir level LSL LT4032 alarm 15% is not true. 'Low Low oil reservoir level LSL LT4038 alarm 15% is not true. Lubrication Oil



pressure low low alarm



Mill operation with high solid percentage by weight than that recommended and a subsequent emergency shutdown.

The permanent remedy for case one would be to feed clean ore in to the mill.

In both cases jamming could possibly be cleared by pressurized fresh water into the trommel screen and carefully extracting with proper tools from the discharge of the mill.

If needed, stop the mill operation to clear the jam.

3.3.13.3 Integrated Start Sequence

In summary the system is started with the following sequence.

Start the Group 1 Start the Group 2

Start the Group 3

Start the Group 4

Put the liquor flow controllers in to cascade Control.

3.3.14 Integrated Stop Sequence

In summary the system is stopped with the following sequence.

Put the liquor flow controllers in to Auto mode to maintain their current set points Stop the Group 4 Wait for the mill to empty of solids Stop the Group 3 Stop mill main drives Set the liquor flow rates to low values Wait for the mill discharge tank to empty of solids Flushing the mill discharge slurry transfer pipe Close the water flow control valves Stop the Group 1 Drain the slurry from mill discharge tanks. Stop the Group 2

Allowance is also made for flushing the mill and tanks as much as possible after an equipment trip. This sequence is still initiated by the operator.

3.3.14 Emergency Operation

If any trip or failures occur in any of the drives in this group, all preceding equipment will also stop as a result of the interlock system.

This could result in increased difficulty while re-starting the group due to the improper shut down. If the quantity of the material is huge that remain in the system, it might be necessary for the operator to resort to the Individual mode of start during re-start of group.

3.3.14.1 Failure of feeding arrangement to Mill

In this instance, a number of simultaneous interlock actions need to occur. Those include immediately.

Mill main motor stops if the weigh feeder operation is not restored within 300 seconds from the fault occurred.

Mill water controls automatically with the ratio control.

Main bearing lubrication system stops after 600sec if run feedback of mill main motor fails.



Mill discharge pumps speed would come to a preset value (Say 50%) if the mill discharge tank level reaches Low-Low (30%).

3.3.14.2 Failure of main bearing lubrication system


Failure of mill main bearing lubrication system will stop the mill main motor.

Mill feed system (apron feeder & mill feed conveyor) trips immediately if mill main motor stops/trips.

Mill water addition controls automatically with the ratio control.

Speed of mill discharge pumps would come to a preset value if the mill discharge slurry tank level reaches Low-Low (30%).

3.3.14.3 Failure of Gearbox lubrication system

In this instance, the simultaneous interlock actions need to occur. Those include immediately.

Mill main motor stops if the gearbox lubrication system is not resorted within 300 seconds from the fault occurred.

3.3.14.4 Failure of Grease Spray system

In this instance, the simultaneous interlock actions need to occur. Those include immediately.

Mill main motor stops if the grease spray system is not resorted within 1200 seconds from the fault occurred.

3.3.14.5 Failure of mill discharge slurry pump


Mill discharge slurry pump feedback fails.

Mill main motor stops if the mill discharge slurry tank level remains High-High for 240 seconds.

Mill feed system (apron feeder & mill feed conveyor) trips if mill discharge slurry tank level reaches High-High.

Mill water controls automatically with the ratio control.

Main bearing lubrication system stops after 600sec if run feedback of mill main motor fails.

The drain valve should be opened manually to drain the slurry in the pump and the line.

3.3.14.6 Failure of mill

Mill Weigh feeder operation stops.

Mill Water controls automatically with the ratio control.

3.4 Thickener & Flocculent dosing system (Inputs received from package vendor Outotec)

The thickener treats the concentrate from the wet grinding section using a flocculent solution to produce thickened concentrate for transport to the next process and Clarified water for reuse in the plant.

Local control of the thickener is via the control panel mounted on the bridge. The drive can be



started and stopped and the rakes raised and lowered via pushbuttons on the front of the panel. The panel displays all of the alarms as well as the main process signals, viz: Torque.

3.4.1 Principle of Operation Feed slurry enters the thickener from the top via a feed pipe, and is discharged tangentially into the feed well. The slurry is diluted with filtrate (From Filtrate tank) and a chemical agent (a poly electrolyte) is added to bind solid particles to form suitably large and stable flocs that settle under gravitational forces. The flocculated slurry settles over a bed with a well-defined interface with clarified water above it. Clarified water flows to a peripheral collection launder at the top of the thickener and finally flow into the process water tank and again re-circulated as process water. Rake arms fastened to the drive shaft coupled with gear box, scrape the precipitated and deposited sludge towards to the centre of thickener bottom cone. Concentrated Sludge is withdrawn from central underflow nozzle located at base of the thickener and then pumped to the slurry holding tanks (B36101-1&2).

3.4.2 Control Logic for Thickener Local Control Panel

The main controls for the Thickener are as follows:

1. Manually Start or Stop the Hydraulic power pack Electric motor through local control panel.

2. Manually raise and lower the rake base.

3. Rake raising and lowering through Auto mode.

4. Manual trip Reset.

5. Selection of operation (Auto/Manual operation) through selector switch.

3.4.2.1 Manual operation

Manual mode shall be selected in the selector switch.

The electric motor shall be started manually. The motor shall start only if oil level is above the specified level in the power pack and the pressure switch has not exceeded the maximum set pressure (95% of set pressure).

The Hydraulic Cylinder is actuated manually up to the maximum stroke or the rake base raised up to maximum level. Once the cylinder reaches to max. Stroke, the Upper limit switch turn NC thereby restricting further raising of the rake.

The Hydraulic Cylinder is retracted manually or the rake base is lowered up to the minimum level. Once it reaches to the minimum set point, the Lower limit switch turn NC, thereby restricting further lowering.

When the oil level reaches low level in the hydraulic power pack or pressure switch experience maximum pressure (95%) or pre-set pressure governed by the pressure transmitter is more than 60% - The Hooter siren turns ON.

While lifting the rake mechanism, the rake arms shall continuously rotate and scrape the slurry. Hooter will turn OFF if trip reset is being activated.

The electric motor shall be stopped manually.



3.4.2.2 Auto operation

1. Auto Mode shall be selected by selector switch.

2. The Hydraulic Power pack electric motor shall be manually started. The motor shall start only if oil level is just above the specified level in the power pack and pressure switch has not exceeded maximum set pressure (95%).

3. If torque is less than 60% of the set pressure in the pressure transmitter, rake shall rotate at the lower most position and lower limit switch shall turn NC.

4. Accordingly indication shows as Rake is fully lowered.

5. Once torque reaches to 60 % or more of the preset pressure transmitter reading, rake shall raise automatically and will be held at the position so that pressure drops to 60 % of the set pressure. In any case if rake pressure reaches 95% of the set pressure, pressure switch shall be activated and the electric motor turns OFF.

6. If the rake lift carriage reaches the maximum level and still the pressure shows more than 95%, the electric motor shall turn OFF (Upper limit switch turn to NC).

7. Accordingly indication shows as Rake is fully raised.

8. After lifting, if pressure drops to less than 40% of set pressure, rake shall lower automatically by timer circuit relay. Rake shall lower every 180 sec. interval and spike of 2 sec ON, process shall be repeated till this reaches the lower most position.

9. When oil level reaches the low level in the hydraulic power pack or pressure switch experiences maximum pressure (95%) or more than 60% of pre set pressure governed by the pressure transmitter, the Hooter siren turns ON.

3.4.2.3 Local control panel Indication

a) Hydraulic power pack electric motor ON.

b) Hydraulic power pack electric motor TRIP.

c) Rake fully RAISED (max. stroke).

d) Rake fully LOWERED.

e) High torque TRIP.

f) Low hydraulic oil level TRIP.

g) High torque ALRAM (Hooter turned ON).

3.4.2.4 Local control panel PUSH BUTTON

a) Hydraulic power pack electric motor START.

b) Hydraulic power pack electric motor STOP.

c) Rake RAISED.



d) Rake fully LOWERED

e) Trip RE-SET.

f) Lamp TEST.

g) Emergency STOP.

h) Selector switch (Manual/Auto Mode)

i) Duel set controller (Micro process based).

j) Hooter

3.4.2.5 Feed back to Main Automation System (Potential free contacts)

a. Pressure transmitter/Torque transducer (4 to 20 mA)

b. Rake Fully lowered.

c. Rake fully raised.

d. Hydraulic oil level-Low trip.

e. High torque trip (Pressure switch).

f. Hydraulic Power pack Motor ON.

g. Hydraulic Power pack Motor TRIP.

Note:

1. In primary duel set controller, 100% (20 mA) set point corresponds to 120 bar/Maximum operating pressure/torque and 0% (4 mA) set point (Torque Duel set Controller) corresponds to 0 bar.

2. In secondary duel set controller, 100% (20 mA) set point corresponds to height from sensor face and free board and 0% (4 mA) set point corresponds to 2 mtr depth from the dual crystal sensor/source.

3.4.3 Control Logic For Flocculent Dosing System

The operation logic for complete flocculent dosing system is designed and defined to prepare and dose the required quantity of flocculent automatically from Main Automation System.

Provision for manual operation is also enabled through a selector switch.

The flocculent solution of 0.25% concentration gets pumped by the dosing pump. If required, further dilution will be done by addition of water. Proper mixing takes place inside the static mixture before the diluted flocculent solution enters the thickener.

Once the flocculent drops below certain level (1-FDS-LS-04) in dosing tank (1-FDS-DOT-02), the level switch gives the signal to Transfer Pump (1 - FDS - TP 01), which starts and pumps the prepared solution from preparation tank (1-FDS-PRT-01) to dosing tank (1-FDS-DOT-02).The Transfer Pump (1 - FDS - TP 01) Stops at LL level of the tank. This batch Displacement volume



is pre calculated. Dosing Tank Volume above Low level (1-FDS-LS-04) is slightly more than this Pre calculated Volume (Effective Volume). Hence there is no possibility of overflow.

When the preparation tank (1-FDS-PRT-01) gets emptied, this signal is transferred to panel by level switch (1-FDS-LS-03) and the Transfer Pump stops (1 - FDS - TP 01). Simultaneously, water inlet solenoid valve (1-FDS-SOV-01) actuates to open & allow water inside preparation tank (1-FDS-PRT-01). When the water just submerges agitator blades, level switch (1-FDS-LS-02) gives signal again to panel, which in turn starts Screw feeder (1-FDS-SF-01) and agitator (1-FDS-AG-01).

Screw feeder is allowed to operate only for few seconds thro timer (T2) to allow just enough quantity of flocculent powder required for preparing fresh batch of solution at 0.25% concentration. It will be automatically stopped through Timer. It will also invariably stop at high level (1-FDS-LS-01), overriding the timer as a safety interlock, depending on the status.

The water inlet to the preparation tank stops when the high level (1-FDS-LS-01) is reached. Agitator (1-FDS-AG-01) continues to mix water and powder to make homogeneous solution and stops when solution is transferred to dosing tank.

The whole cycle repeats when the dosing tank level hits low level again.

The safety interlock is provided, in case the level goes further low (very low) (1-FDS-LS-05) in dosing tank (approximately 50mm. lower than low level), very low level switch is actuated, trips the dosing pump (1-FDS-DP-01)

In such conditions, manual building up of level in dosing tank needs to be done, till very low level signal goes off.

The auto manual switch is provided on panel which enables following operations manually provided the very low dosing tank level alarm is not actuated.

1. Transfer valve operation 2. Agitator operation 3. Screw feeder operation 4. Water feed valve operation

3.5 Thickener Underflow Slurry Handling

The Thickener (B45701) receives slurry from many sources. The ball mill area sump pumps and filter area sump pumps go to the Sieve Bend (B45451) to reject trash and oversize material.

Density and flow meters (DT-01B0820), (DT-01B0830) and (FT-01B0821), (FT-01B0831) measure the Thickener Underflow Pumps (B41101-1, 2, 3) discharge. There are two underflow pumps running with one spare. Thickener underflow slurry density is maintained at a specific gravity of approximately 2.13. There are two density controllers that control the discharge either to the slurry distributer or to the thickener. Underflow travels to the Slurry Distributor (B48201) and is directed by two Dart Valves (B48201-1, 2) to the Slurry Holding Tanks (B36101-1, 2). An overflow at the Distributor returns slurry to the thickener.

The three Thickener Underflow Pumps have individual Hand Speed Controllers at the Main Automation System.

The thickener underflow rate will be controlled to maintain equilibrium between the solids going into the thickener from all sources and the solids pumped as underflow at the proper density to the slurry holding tanks. One indication that the thickener is not in equilibrium is that the level in the slurry tank will begin dropping. Another indication is the torque measured from the thickener rake will increase as a result of excessive solids building. The underflow pump rate may then be



adjusted by the operator to re-establish the solids balance. The variable speed control will only be used for small adjustments. The operator may also increase the solids flow to the upstream ball mills to balance the solids into and out of the thickener.

If there are large changes in the flow of solids to the thickener, then the thickener underflow will be recycled until the desired density has been re-established. One of the thickener underflow pumps may be shutdown if the one of the upstream ball mills is shutdown.

The flow and density instruments on the thickener underflow pumps allow operators to compute the mass flow from the thickener. Once equilibrium is reached in the thickener, the underflow pump speed may be adjusted to yield the same mass flow to the distributor as the new solids feeding the thickener. The primary source of new solids enters the thickener from the cyclone overflow.

3.6 Thickener Overflow Water handling

Overflow from the thickener goes to Process Water sump (B15701) fitted with pumps (B41105-1, 2, 3). Two pumps would be in operating condition and 1 pump will be standby.

The process water sump level controller (Loop No: LIC-01B-0804, P&ID: R-01-1023) will control makeup water addition through LV-01B0804A in case of low level of the sump or divert water to Blow down through LV-01B0804B in case of High High level of the sump. At Low Low level of the sump, process water pumps will stop.

3.7 Slurry Holding tanks

Two Dart Valves (B48201-1, 2) direct the thickener underflow slurry to Slurry holding tanks. The dart valves are operated manually from Main Automation System. Operator will allow the Dart valves to fill one Slurry Holding Tank at a time. The third dart valve is for future.

Agitators (B39102-1, 2) are fitted to keep the slurry in suspension in the Slurry Holding Tanks. Slurry level (LIT-01B1304 and LIT-01B1305) should be maintained to keep the agitator below slurry level.

3.8 Filter Press Feed Pumps

Manual valves allow the Filter Press Pumps (B41103-1, 2, 3) to be fed from either Slurry Holding Tank. If both Slurry Holding tanks are empty, then all three Filter Press Feed pumps (B41103-1, 2, 3) stop. The Filter Press Feed Pumps are designed for one pump for (2) Filter Presses. The logic will allow the pump to fill only one filter press at a time.

3.9 Pressure filter (Inputs received from package vendor METSO)

The pressure filter operates on a batch basis and comprises a series of filter plates supported in a fabricated frame with a hydraulic system to open and close the filter plate pack.

Slurry is fed into the chambers; the filtrate formed in the filter plates passes through the filter cloths while the solids are retained in the chambers. After filtration the membranes are activated to stabilize the cake and the filter cake is air dried by passing Compressed air through the cake. The filter is then opened to discharge the cake, the cloths are rinsed and the filter starts next cycle.

The operation of the VPA Pressure Filter (VPA 20 of METSO) is fully automatic requiring only periodical operator routine inspection and operational checks.

A complete filter cycle comprises of following individual steps



Low pressure closing High pressure closing Feed - filtration Membrane compression Air through blow Top blow High pressure drainage Cake chute doors opening Filter opening cake discharge Cloth vibration (only if required) Cake chute doors closing Cloth washing with vibrations Waiting for next cycle to commence

These individual steps are generally described as follows reference is also made to the valve sequence diagram.

3.9.1 Low pressure closing

The cycle begins with filter closing where the low-pressure high-capacity hydraulic pump is started and oil is directed by appropriate valves to retract the cylinder rods. This pump actually consists of multiple pumps mounted on a common shaft. Each pump operating one cylinder to ensure equal extension and retraction speed of all cylinders to maintain parallel movement of the pressure piece and filter plates. When the movable head reached the inner closed position indicated by proximity switches the filter Low Pressure is closed.

3.9.2 High pressure Closing

When the filter has reached the low pressure closed position, the step high pressure closing will commence. The hydraulic high pressure pump will create the required pressure to retract the cylinder rods a little bit further to accomplish compressive closing. High pressure closing pressure is indicated by a pressure transmitter.

3.9.3 Feed - filtration

The feed pump needs be controlled by a variable speed drive unit. The pump speed control is necessary to cater for the difference in the pump operating conditions at the start and end of the filtering step, where high flow/low pressure and low flow/high pressure conditions are required respectively.

With this system, the feed pump speed will be controlled to provide a filling rate of the correct flow m/hr, which should fill the filter under controlled forms. As the pressure increases, the pump speed will be increased to achieve and maintain the required 6-8 bar filtering pressure. Signals to start and stop the feed pump, as well as the pump speed reference signals could be provided from the filter control system.

Feed - Filtration starts as soon as the correct filter closing pressure is reached.

Feed valve V1 opens and the feed pump starts. An automatic feed control system will control the speed of the pump, the first part of the feed step under flow control to limit the flow rate, then a ramped speed increase until the 6-8 bar filtering pressure is achieved and maintained. The pump speed reference signals can be provided by the filter control system.

The cloth damage detection system is activated a short time after the filtration starts to avoid the normal initial turbid filtrate flow period.



Filtration continues for the timed period, or by using derivative calculation algorithm. The feed pump then stops and feed valve V1 closes.

3.9.4 Membrane Compression

The membrane air evacuation valve (V10) closes and the membrane compression air feed valve (V7) opens to inflate the membranes.

The primary membrane compression step continues for the timed period.

3.9.5 Air Through Blow

The filtrate valve V3 (V3, V12 and V13 on VPA 20 size filters) closes, air valve V5 opens and air is entering into the filter via two of the side channels and further into the surface of the membrane plates. The air has to pass through the filter cake forcing the water around the particles, out on the drainage surface on the filter plates, and out again of the filter through the two filtrate ports.

The membranes are kept inflated with a higher pressure than the air through blow pressure during the complete step to compensate for the reduction in the filter cake volume as the moisture is displaced.

To secure a higher pressure behind the membranes during the air through blow, the valve V11 opens for booster air to pressurize the membranes at the same time as valve V5 opens for air through-blow.

The booster air is delivered from a booster air compressor.

The procedure described above will prevent the filter cake from cracking and consequently minimize the air consumption.

The air through-blow step continues for the timed period and then valve V5 is closed.

3.9.6 Top Blow

The filtrate valve V3 (V3, V12 and V13 on the VPA 20 size machines) opens. The Slurry return valve V4 and valve V41 opens.

The air inlet valve V6 and water inlet valve V8 opens for a short time (V8 only if needed), to displace slurry from the feed channel in the filter plate pack.

The Top blow step continues for the timed period. The top blow step is completed when valve V4 and valve V41 are closed.

Then the membrane air valves V7 and V11 close and the membrane air evacuation valve V10 opens to release the membrane pressure.

3.9.7 High Pressure Drainage (Hydraulic)

The hydraulic closing pressure in the hydraulic cylinders is relieved allowing the filter to open slightly to drain any remaining filtrate from the filter.

The filter weighing system records the filter weight. High pressure drainage completion is indicated by a pressure transmitter.

3.9.8 Cake Chute Doors opening



The two chute doors open, operated by hydraulic cylinders. Proximity switches indicate when the both doors are in open position.

3.9.9 Filter Opening cake discharge

The relevant hydraulic system valves are activated and the low pressure high capacity pumps extend the cylinders, pushing the movable head open.

The filter plates are connected together to the movable head by a link system so as the movable head starts to move the plate pack is opened according to the concertina style allowing the cake to fall from the filter by gravity in the chambers one by one.

When the movable head reached the outer limit of its travel indicated by proximity switches the filter is open.

3.9.10 Cloth Vibration

When the machine is in open position the weight will be checked.

If the weight is above maximum allowed empty weight, the motor vibrators will start and run for short timed period to vibrate the filter cloths and to ensure that all cakes are removed from the filter cloths.

If the empty weight is too high after the automatically repeated vibrations, the machine will stop. An alarm will follow which is visible on the screen and the remaining weight needs to be removed manually by further vibrations or washing.

3.9.11 Cake Chute Doors Closing

The two chute doors operated by hydraulic cylinders close. Proximity switches indicate when the both doors are in closed position.

3.9.12 Cloth wash

When the cake chute doors are closed the wash water valve V9 opens and cloth flushing starts. During flushing the vibrators may be activated to ensure that all remaining cake residue is removed.

The cloth flushing step continues for the timed period and a after valve 9 closes.

3.9.13 Waiting time

A waiting time setting between the cycles can be used. Waiting continues for the timed period. The VPA Pressure Filter is then ready to start next cycle.

OPERATION DESCRIPTION



Automatic Cycle Steps Schematic

3.10 Control system VPA-press filter



The VPA-press filter control system consists mainly of the following items:

Main control cabinet, -K1 containing PLC, Industrial-PC and MCC functions, (designed to be installed on the filter platform). Pneumatic valve control, -PV1-2, (designed to be installed on the filter platform). Hydraulic control, -HV1 the hydraulic junction box, (preinstalled on the hydraulic unit). Weight system with 4 load cells and a weight central.

3.10.1 Description

The VPA-press filter is operated from the Industrial PC screen on the main control cabinet -K1 located on the filter platform. The industrial PC is connected to a PLC which handles the control logics. The VPA-press filter can be operated either in Automatic, Semi-automatic or Manually.

In AUTO the VPA-press filter operates automatically by the programmed sequence. In SEMI-AUTOMATIC the filter is operated step by step through the sequence and in MANUAL some of the filter functions can be manually operated from the monitor.

All process specific Data & Parameters can be set and adjusted in the Settings-menu.

Statistics, like Cycle time, Press weight etc. is presented on the Statistics-menu.

Alarm & Fault handling is implemented in the operators panel; each alarm will be displayed with text, status, date and time in the Alarm-menu.

The main power supply are connected to the Main control cabinet, all other supply and control voltages are created internally by use of transformers and distributed to all other different units. The cabinet are placed on rubber dampers to eliminate vibrations from the environment.

The process air supply will only be connected to one point at the Pneumatic control panel, -PV1, that together with PV2 controls all pneumatic process valves located around the press filter.

Inductive proximity switches supervise the process valve positions.

The Hydraulics will be controlled from the Main control cabinet via the junction box located on the hydraulic station. Inductive proximity switches supervise all hydraulic movements.

A number of sensors, pressure switches, inductive proximity switches etc. for control and supervision of the process are connected to the Main control cabinet via junction boxes.

A weighing system consisting of 4 load cells, (one in each corner of the VPA -press filter), connected to the weight-central via a junction box delivers the actual weight of the pressed material to the control system for process control and statistics.

3.10.2 Interfaces Between Metso And Customer

There are two types of interfaces between Metso VPA-press filter control system and JSPL. One is for the process control and the other is for starting & stopping the VPA Press filter from a Remote location. Both interfaces will preferably be Ethernet TCP/IP between the different units.

3.10.2.1 Process equipment interface

Following signals will be exchanged between the Metso VPA control system and JSPL process equipment:

From Metso JSPL From JSPL Metso



Control Room Emergency Stop

Slurry tank OK = Tank level OK and/or Density OK

Dry Air OK = Pressure OK or Flow OK Wash Water OK = Tank level, or Pressure or Flow OK Start order Slurry pump Slurry Pump is running, acknowledge signal

Slurry Pump Fault Start order Wash water pump Wash water pump is running, acknowledge signal

Wash water Fault Conveyor Increase speed order Conveyor is running, acknowledge signal

Conveyor Fault

3.10.2.2 Remote control interface

The VPA Press filter can be Started & Stopped from Main Automation System, (i.e. an overriding computer).

Following signals will be exchanged between the Metso VPA Press filter control system and customer overriding control:

From Metso JSPL From JSPL Metso Remote mode is selected Run/Stop order, (pulse, toggle Run and Stop) VPA in operation To Neutral, (pulse) VPA No Fault To Parking, (pulse) Completed press cycle, (pulse)

In Neutral

In Parking

3.11 Filter cake and Filtrate handling

Pressure filtration occurs in several steps to dewater the iron ore concentrate. The typical filtration cycle starts with the feeding step, followed by compression, followed by air drying, then cake discharge, and finally cloth washing. In the Feeding step, slurry is pumped to the operating filter via the Filter Press Feed Pumps. Pumping pressure provides the pressure for the initial dewatering of the slurry. When the pumping pressure is no longer high enough to dewater the slurry, the feeding step is complete. The Filter Press Feed Pump then begins pumping either to another filter press or back to the three-way slurry distributor. Filtrate from the pressure filter drains to the Filtrate and Wash Water Tank.

In the compression step, a pressurized bladder in the filter press compresses the filter cake to remove additional water from the filter cake.

In the drying step, compressed air from the Drying Air Compressors removes additional water from the filter cake.

Commands from each filter press will signal the Main Automation System to supply high pressure slurry. When not filling, the Filter Press Feed Pumps recycle slurry to the Slurry Distributor (B48201).

There are six (6) Filter Presses (B45101, 2, 3, 4, 5, and 6). These presses work on a cycle that is part of the METSO supplied PLC system with Profibus link to the Main Automation System. If Slurry is not needed at a filter press, the slurry is recycled back to the Slurry Distributor (B48201).



High Pressure water sprays are also used to clean the cloth when the filter frames are opened.

There are 4 air compressors feeding 6 Filter Presses. The Filter Cake drops on the Filter Cake Conveyor (FC-11A, B, C, D, E & F) (B43010-1, 2, 3, 4, 5, 6) and is transported to common conveyor FC-12 (B43015).

From here the filter cake will travel over conveyors FC- 13, 14, 15 & 16.

Individual start-up of Filter cake collecting conveyors (FC-11A to F) and Filter cake transport conveyors FC-12, 13, 14, 15 & 16 will depend on healthy signal from the safety switches placed on the conveyors.

Group start of FC-12, 13, 14, 15 & 16 will depend on the low level signal from level transmitters placed over filter cake storage bins (43502-1,2). Low signal from bin level transmitters will start FC-16 first then filter cake conveyors FC-15, 14, 13 & 12 in a sequential manner provided there is healthy signal from safety switches on these conveyors.

The Filter cake conveyor plow (B48005) is lowered to the conveyor in order to fill Iron ore filter cake storage bin-2 (B43502-2). Plow is equipped with two position switches, up and down. They signal the DCS which indicates to the control room operator the position of the plow. The plow is operated in manual mode; the operator raises and lowers the plow to suit. Full (High, High) bin will cause its plow to raise by the operator manually.

HH alarm from both bin level transmitters and unhealthy signal from any conveyor safety switch will stop up-stream conveyors in a sequential manner.

The Filtrate and Wash Water Tank (B35104) has two variable speed pumps (B41104-1, 2) to move the filtrate back to the Thickener. If the Filtrate level gets below the set point of LIT-01B1801A, then makeup water enters through LV-01AB1801. Level controller (Loop No: LIC-01B1801B, P&ID: R-01-1019) controls the speed of the Filtrate Pumps (B41104-1, 2).

The set point of Level Controller (Loop No: LIC-01B1801A, P&ID: R-01-1019) is set at about 25 % while level controller LIC-01B1801B is set to 60 %. When the level reduces to 25% the control valve will attain its full opening condition in order to fill the tank. When the rising level is at 60% the valve will attain its full close condition and the pumps will start in order to pump-out the filtrate from the tank.

4.0 ADDITIVE RECEIVING AND DRY GRINDING -AREA 2

4.1 Additive Receiving & Storage (P&ID: R-02-1001)

Additive Feed can travel to Line 1 or Line 2. When directed to line 2, the material travels from reversing shuttle conveyor AF-4 (B43120) to Additive Feed Conveyor AF-15 (B43110) to reversing shuttle AF-16 (B43115). The shuttle car (B43120A) of AF-4 can position at the existing limestone bin, the existing coal bin, or at the Additive Feed conveyor AF-15.

AF-15 will feed AF-16 (additive feed bin reversing shuttle conveyor, B43115). AF-16 will fill limestone bin (B16207) and coal bin (B16205).

Individual start-up of blended ore conveyors AF-15 and shuttle conveyor AF-16 will depend on healthy signal from the safety switches placed on the conveyors.



Group start up will depend on the level signal from level transmitters placed over bins. Low (20%) signal from bin level transmitters will start shuttle conveyor AF-16 first then additive feed conveyors AF-15 in a sequential manner provided there is healthy signal from safety switches of these conveyors.

The Additive feed bin reversing shuttle conveyor AF-16 feeds the Lime stone feed bin (B16207) and Coal feed bin (B16205) depending on the high level signal from level transmitters LIT 2212 & 2213 placed at the bins. The position limit switch (ZS 0132 & ZS 0134) placed suitably for lime stone bin and coal bin positions will allow the shuttle car to stop over the respective bins in order to achieve un-interrupted filling of the bins.

When the limestone bin (B16207) and coal bin (B16205) level reaches the High (70%) level (LAH-02B2212 and LAH-02B2213) a light will blink at the filling location to warn operators that the bin is nearly full. If the level in both the bins should continue to rise to High, High (95%) the feed belt and feed shuttle conveyor will stop.

Lime stone feed bin and Coal feed bin are equipped with individual weigh belt feeders (B43119 & B43068). Belt feeders discharge material to conveyors AMF-11 (B43079) at a controlled rate, set by the operator (Loop No: WIC - 2215 & 2216, P&ID: R-02-1001) for a capacity which is compatible with the Mill grinding capacity for that particular additive. Once the system is started, operator controls the respective belt feeder speed to obtain the desired set point as mentioned below:

Low-Low (5%) bin level will stop the Weigh Belt Feeders LSF-11, CF-11 and subsequently additive mill feed conveyor AMF-11.

The receiving rates for coal (10% H2O) and Lime stone (8% H2O) to the feed bins are:

Operating - TPH Design - TPH Coal: 100 100 Lime Stone: 100 100

Storage capacity of Coal and Lime stone storage bin is as follows:

Operating - Hours Design - Hours Coal feed bin: 9 4

Lime Stone: 16 9

The feed rate to the Additive mill feed conveyor is as follows:

Coal - TPH Lime stone - TPH Operating 21.2 22.7

Design: 43.5 43.5

The additive mill feed conveyor (AMF-11) feeds the additives to the Ball mill (B46203)

4.2 Dry Grinding System

4.2.1 Process Description (P&ID: R-02-1003, R-02-1005) (Inputs received from package vendor FL Smidth)

The proposed Limestone-Anthracite coal mixture Additive dry grinding system consists of an air swept Ball Mill with its accessories. The mill is sized for grinding Limestone-Anthracite coal mixture at a maximum moisture content of 9% with a feed size of Limestone as -7 mm (100%) & Anthracite coal as -7 mm (100%) to a product fineness of 80% < 53 microns, with a residual moisture content



of 1% at a combined Bond Work Index of 16 KWH/MT. Hot Air Generator Supplies hot air to the mill which will dry the limestone-Anthracite coal mixture during grinding.

Mill exhaust Gases are vented through a dynamic Classifier which recycles coarser particles back to the mill through a flap valve and an air slide. Ground product is collected in a cyclone and a bag filter placed after the dynamic Classifier. In this system, air flow is induced by two fans, mill ID fan and filter ID fan. The clean air from Bag filter shall be released to atmosphere through a stack. Product collected by the cyclone and bag filter is transferred to a product bin which is located inside mixer building.

4.2.2 Normal Start-up Sequence

This section describes the functional groups start-up sequence. If the group has an automatic start sequence, time delays between equipment will also be listed. Any group preconditions required prior to start-up are also listed herein. However, interlocks required for individual or predefined groups of equipment are listed in the Interlocks section.

4.2.4 Normal Operation

This section describes the functional groups normal operation, including operator functions. There are three modes of operation, as described below:

Automatic: Automatic mode is when functional groups are controlled automatically and in sequence by the control system. A functional group is a set of items such as motors, valves, etc. which are started by a single operator action when it is in Automatic Mode. All Protective, Safety, Machine, Operational and Start Interlocks must be met in order to operate.

Manual: Manual mode is when items such as motors, valves, etc. are con-trolled individually by the operator using the control system. Functional groups have no meaning in Manual Mode. All Protective, Safety, and Start Interlocks must be met in order to operate.

Local: Local mode is when items such as motors, valves, etc. are controlled individually in the field, usually by local pushbutton stations located at the item. Functional groups have no meaning in Local Mode. Since the operator interface in Local Mode is often physical devices rather than a display screen, extra care must be taken to ensure that interlocking continues to be enforced. All Protective, Safety, and Start Interlocks must be met in order to operate.

Main Automation System Control: Commands to operate the control system are made by an operator using the Main Automation System HMI. Main Automation System can only operate in Automatic Mode. Main Automation System sets the equipment control mode to Main Automation System control.

4.2.4 Normal Shutdown Sequence

This section describes the group shutdown sequence. If the group has an automatic shutdown sequence, time delays to allow for equipment cleanout or deceleration will also be listed.

4.2.5 Abnormal and Emergency Shutdowns

This section describes abnormal shutdown conditions caused by isolated process or equipment abnormalities or activation of individual equipment safety devices. It also describes emergency shutdowns due to automatic activation of personnel safety systems or field emergency stop pushbuttons.

4.2.6 Interlocks

The Interlocks section describes all interlocks for the individual equipment or functional groups of equipment within the associated software function group. Interlock is defined herein as an



input/output signal or a Main Automation System/Main Automation System internal logic condition, which automatically prevents the operation of an individual or functional group of equipment from the Plant MAIN AUTOMATION SYSTEM HMI. When the condition of an interlock(s) is such that operation of a related piece of equipment or an equipment group is permitted, the interlock(s) is defined as being satisfied.

Specific devices in the Interlock table may be preceded by NOT. This is the condition for the analog threshold (i.e. NOT Bearing Temperature High-High = Bearing Temperature is NOT ABOVE the High-High Set point). However, in the case of discrete switches the Interlock is stated from the ON perspective of the switch. For example the Oil Reservoir Low switch is ON when the oil level is NOT Low (fail-safe), so the required interlock is the switch being true

Interlocks consist of five types and are described in detail below:

Safety interlocks: Safety interlocks are those interlocks which prevent damage to that associated piece of equipment. As a result, safety interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

Safety interlock for a fan or pump would be no high-high bearing temperature. Safety interlocks for every motor will also include the MCC/motor ready signal and receipt of a

run confirmation from the motor contactor after a run command is sent. These interlocks apply to all motors and are not listed in the interlock table for this reason.

Start interlocks: Start interlocks are those interlocks necessary ONLY for starting the machine. As soon as the motor is running the start interlock has no influence. As a result, start interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

A start interlock for a fixed speed fan with automatic damper would be that the damper be closed (limit switch or position transmitter) prior to starting.

Protective Interlocks: Protective interlocks are those interlocks for the protection of the motor itself. As a result, protective interlocks apply when operating in Automatic Mode, Manual Mode and Local Mode.

Example

A protective interlock for a crusher motor would be motor bearing temperature or motor winding temperature.

Machine Interlocks: Machine interlocks are those interlocks for the protection of the machine that is operating in Automatic Mode. As a result, machine interlocks apply only when operating in Automatic Mode.

Example

A machine interlock for a belt conveyor would be a belt drift switch.

Operational Interlocks: Operational

Control Philosophy_Rev 5

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