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DESIGN OF SODA ASH PRODUCTION PLANT
Comprehensive Design Project
Department of Chemical and Process Engineering
University of Moratuwa
Supervised by
Dr.Padma Amarasinghe
Group members
Danushka D.G. 050069L
Gunasekara D.T. 050137U
Jayakody J.R.U.C. 050166GMadurika B.N. 050254B
Weerasinghe D.T. 050472P
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i
PREFACE
This report gives a narrative of our final year comprehensive design project, which is the
production of Soda ash from the sea water and lime stone mines exist in number of places in the
country. The project is the part of curriculum of the final year B.Sc. Engineering Degree program of
the University of Moratuwa and in essence it consists of basic description of such attempt made by
five undergraduate students of Chemical and process Engineering Department, University of
Moratuwa. The content of this report are outlined here.
Chapter 1 gives a brief introduction to the report and the finding from literature survey is given
in chapter 2. This was conducted to study about the soda ash production. It gives general information
about soda ash, how it began, history of the production, the types of production, uses in industrial
sectors, etc.
Designing of compatible, large scale industry in a developing country like Sri Lanka is a big
task. Especially with matching technology and feasibility to the project in such situation is a heavy
work. Chapter 3 consists of the evaluation of the complete feasibility study under technical
economical, market….sectors.
Under chapter 4, we discussed the how we select most appropriate process for the Sri Lanka
through the various operate processes in the world considering the pros and cons of several models.
Chapter 5 is focused on the process description. It begins with the feed selection; and mainly this
chapter contents based on each and every unit operation of the selected process. Equipment layout is
enlightened at the end of this chapter.
The site selection and the plant layout are given in chapter 6. Chapter 7 contains the particulars
of the environmental impact assessment. This contains the major environmental impact from the
sodium bicarbonate process plant and the how to carry out processes of the effluent management.
Full details of the safety measures intended for the plant is given on chapter 8. After that the
safety aspects considering equipment is expressed in detail.
Material balance and energy/ heat balance done on behalf of each unit operation selected isdiscussed in next two episodes chapter 9, 10. The overall material and energy flow sheets arranged for
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the plant is summarized within too. The detailed calculations as well as the assumptions made have
been appended.
The final chapter is presenting the conclusion of this report a summing up of the whole project
with the benefits of the selected process and technologies are imparted in this chapter, as well how it
helped us improve our skill and knowledge. A list of abbreviations and the list of references are
appended at the end of the report.
28/10/2008
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ACKNOWLEDGEMENT
When doing our Final year Comprehensive Design Project, we had to face many hardships and
challenges. It was with the help of many people that we were able to complete this project. We would
like to express our heartiest gratitude to all those people.
First of all we would like to grant our heartiest gratitude to our project coordinator, Dr. Padma
Amarasinghe, (lecturer- Chemical & Process Engineering department, University of Moratuwa) for all
the valuable advice, guidance, support and encouragement given through out the time. Dear Madam,
Thank you very much for spending your precious time to share your priceless knowledge with us, we
owe you a lot.
Then we express our gratitude to the department of Chemical and Process Engineering , all the
staff members of Chemical & Process Engineering department, including Dr. Jagath Premachandra
(head of the department), for all the assistance and big hearted support given toward while doing many
activities of this project and for including a design project in the final year syllabus. Thereby providing
us with a valuable opportunity to improve our knowledge and experience on doing a project, this will
come very useful when we go out to the industry as Chemical and Process Engineers.
We appreciate the support given by all the non academic staff of the Department of Chemical
and Process Engineering, especially the people who were in charge of the department of CAPD center,
for keeping it open at all hours so we could continue our work without interruption.
Then we would like to thank the staff of the Ceylon Glass Limited and the Holcim Lanka
limited for giving us permission to visit the glass plant and provide us necessary experience and
relevant data regarding this project.
Finally we thank all our colleagues of the department of Chemical and Process Engineering for
their help stimulating suggestions and encouragement.
Thanking You.
Group Members
Danushka D.G. : 050069L
Gunasekara D.T : 050137U
Jayakody J.R.U.C : 050166G
Madurika B.N. : 050254B
Weerasinghe.D.T. : 050472P
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CONTENTS
PREFACE
i
ACKNOWLEDGEMENT iii
CONTENTS iv
CHAPTER 1: INTRODUCTION 1
CHAPTER 2: LITERATURE SURVEY 42.1. General Information 5
2.1.1. Other Names for Sodium Carbonate 5
2.1.2. Physical Properties of Sodium Carbonate 5
2.1.3. Hydrates of Sodium Carbonate 5
2.1.4. Chemical Properties of Sodium Carbonate 6
2.1.5. Grades and Specification of the Soda Ash 6
2.2. Uses of Na CO in Industrial Sectors2 3 7
2.2.1. Glass Industry 7
2.2.2. Detergent Industry 8
2.2.3. Metals and Mining 8
2.2.4. Steel Industry 8
2.2.5. Paper and Pulp 9
2.2.6. Textiles 9
2.2.7. Non-ferrous metallurgy industry 9
2.2.8. Chemical industry 9
2.2.9. Other Applications 9
2.3. Uses of NaHCO3 in Industrial Sectors 10
2.4. History of the Production 10
2.5. Overview about Type of Production 12
2.5.1. Le Blanc process 12
2.5.2. Solvay Process 14
2.5.3. Hou's Process 15
2.5.4. Dual process 15
2.6. Sodium Carbonate Minerals 15
2.6.1. Trona Based Process 16
2.6.1.1. Trona Products 17
2.6.1.2. Monohydrate Process 18
2.6.1.3. Sesquicarbonate Process 19
2.6.1.4. Alkali Extraction Process 20
2.6.2. Nahcolite based process 22
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2.7. International Scenario 22
2.8. Structure and Status of Indian Industry 23
CHAPTER 3: FEASIBILITY STUDY 243.1. Preliminary Study 25
3.2. Economical Feasibility 27
3.3. Market Feasibility 30
3.4. Technical Feasibility 31
3.5. Social Feasibility 33
CHAPTER 4: PROCESS SELECTION 354.1. Introduction 364.2. Comparison of Solvay process with Others Methods of Production 374.3. Process Selection Conclusions 40
CHAPTER 5: PROCESS DESCRIPTION 41
5.1. Main Chemical Reactions in Solvay process 42
5.2. Process Steps 44
5.2.1. Brine purification 44
5.2.2. Calcinations of limestone in kilns and the production of CO2 and milk of lime 45
5.2.3. Absorption of ammonia into purified brine 46
5.2.4. Carbonation of the ammoniated brine with CO2 to produce sodium bicarbonate 46
5.2.5. Separation of Sodium Bicarbonate from Mother Liquid 47
5.2.6. Recovery of the Ammonia using Milk of Lime 48
5.2.7. Calcinations of Sodium Bicarbonate to form Sodium Carbonate (light ash) 49
5.2.8. Densification of Sodium Carbonate to form Dense ash 49
5.3. Product (Soda Ash) Storage and Handling 50
5.4. Raw Materials 50
5.4.1. Brine 50
5.4.2. Limestone 51
5.4.3. Carbon for the Lime Kiln 51
5.4.4. Ammonia 52
5.4.5. Various additives 52
5.5. Utilities 53
5.5.1. Steam 53
5.5.2. Process water 53
5.5.3. Cooling waters 535.5.4. Electricity 54
5.6. Energy saving in the process 54
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5.6.1. Heat recovery 55
5.6.2. Energy Minimization 55
5.7. Process Flow Diagram 57
5.8. P & I Diagram 58
CHAPTER 6: SITE SELECTION & PLANT LAYOUT 596.1. Introduction 60
6.2. Site Selection Considerations 60
6.3. Plant layout 65
CHAPTER 7: ENVIRONMENTAL IMPACT ASSESSMENT 667.1. Gaseous Effluents 67
7.1.1. Particulate Dust 67
7.1.2. Carbon dioxide and monoxide 67
7.1.3. Nitrogen oxides 68
7.1.4. Sulfur oxides 68
7.1.5. Ammonia 68
7.1.6. Hydrogen sulfide 69
7.2. Gaseous Effluents Management 69
7.2.1. Calcinations of Limestone 69
7.2.2. Precipitation of Crude Sodium Bicarbonate 70
7.2.3. Filtration of the Bicarbonate 70
7.2.4. Conveying and Storage of Soda Ash 70
7.3. Liquid Effluents 71
7.3.1. Wastewater from Distillation 71
7.3.2. Wastewater from Brine Purification 72
7.4. Liquid Effluent Management 73
7.4.1. Liquid Effluent Treatments 73
7.4.1.1. Total Dispersion 74
7.4.1.2. Separation of the Suspended Solids and Liquid Dispersion 74
7.4.2. Liquid Effluent Discharge Management 75
7.5. Solid Effluents 76
7.6. Solid Materials Management 76
7.6.1. Limestone Fines 76
7.6.2. Grits from slaker 76
7.7. By-Products Recovery and Reuse 77
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7.7.1. Calcium Chloride 77
CHAPTER 8: SAFETY MEASURES 78
8.1. Plant Safety 79
8.2. General Plant Safety 79
8.3. Personal Safety 80
8.4. Safety Aspects of Equipments 81
8.4.1. Lime Kiln 81
8.4.2. NH3 Absorbing Unit 82
8.4.3. Carbonator Unit 82
8.4.4. NH3 Recovery Unit 82
8.4.5. Drier 83
8.4.6. Storage Vessels 84
8.4.6.1. Ammonia 84
8.4.6.2. Soda ash 84
8.4.6.3. Baking soda 84
8.4.6.4. Calcium Carbonate and Calcium Oxide 84
8.4.7. Pipelines 85
8.5. Safety Aspects of Chemical 85
8.5.1. Carbon Dioxide (CO )2 85
8.5.2. Ammonia (NH )3 86
8.5.3. Sodium Carbonate (Na CO )2 3 88
CHAPTER 9: MATERIAL BALANCE 91
9.1. Product specification 92
9.2. Components in Purified brine 92
9.3. Calculations for NH Absorption Unit3 93
9.4. Air Mixture 95
9.5. Gas Washing Tower with Purified Brine 96
9.6. Carbonator Unit 97
9.7. Filter 99
9.7.1. Calculation for residue solid 100
9.7.2. Calculation for permeate 100
9.8. Lime Kiln 101
9.9. Slaker of lime 103
9.10. Ammonia Recovery Unit 104
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9.11. Gas Cooler 107
9.12. Air Mixture (Before the Gas Cooler) 108
9.13. Dryer 109
9.14. Material Flow Sheet 111
CHAPTER 10: ENERGY BALANCE 112
10.1. Kiln Energy Balance 113
10.2. Energy Balance for Air Preheated 115
10.3. Calcinations of Crude Bicarbonate 116
10.4. CaCO3 Preheated 119
10.5. Air Mixer Energy Balance 120
10.6. Heat Balance for Gas Cooler 122
10.7. Slaking of Lime 123
10.8. Recovery of Ammonia Column Energy Balance 126
10.8.1. Find Outlet Temperature of the Cool Gas 127
10.8.2. Fine Quantity of Steam Consumption 128
10.9. Carbonation of Ammoniated Brine Column 130
CHAPTER 11: CONCLUSION 133
REFERENCE 135
CD CONTENTS
Excel Spreadsheets
Soft Copy Of Report
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Table & Figure
Table2.1: Market specifications of dense soda ash 7
Table2.2 : Worldwide capacity of soda ash manufacture 11
Table 2.3: Natural soda minerals occurred worldwide 16
Table 2.4: products of Trona 17
Table 4.1 a comparison of the Solvey and dual processes 40
Table5.1: Raw and purified brines (typical composition ranges) 51
Table 5.2: Typical compositions for coke to the lime kiln 52
Table 5.3: Soda ash process major Input/output levels 56
Table 7.1: Rough concentrations of the waste water from the distillation column 71
Table 7.2: Typical concentration wastewater from brine purification 72
Table 9.1- Soda ash specification 92
Table 9.2- Purified brine specification 92
Table 9.3- Residue solid composition 99
Table 10.1- a,b,c constant 113
Table 10.2- kiln inlet enthalpy 114
Table 10.3- kiln outlet enthalpy 114
Table 10.4- Air enthalpy change 115
Table 10.5- CaO enthalpy change 116
Table 10.6- flue gas enthalpy change 119
Table 10.7- Soda ash specification 123
Table 10.8- a, b, c constant for CaO 124
Figure 2.1: Distribution of soda ash by end use 7
Figure 2.2: Flow diagram of monohydrate process 18
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Figure2.3: Flow diagram of sesquicarbonate process 19
Figure 2.4: Flow diagram of alkali extraction process 21
Figure 3.1: Soda ash imports (2006) 25
Figure 3.2: Variation in soda ash imports 26
Figure5.1: Block diagram of the soda ash production plant 42
Figure5.2: Vertical shaft kiln for lime stone 46
Figure5.3: Process flow diagram 57
Figure5.4: P&I diagram
Figure 6.1- Mineral Map of Sri Lanka 63
Figure 6.2- Geographical map of proposed land 64
Figure 6.3- Plant layout 65
Figure 9.1- NH3 Absorption Unit 93
Figure 9.2- Air mixture before NH3 Absorption Unit 95
Figure 9.3- Gas washing tower with purified brine 96
Figure 9.4- Carbonator Unit 97
Figure 9.5- Filter 99
Figure 9.6- Lime Kiln 101
Figure 9.7- Slaker of lime 103
Figure 9.8- Ammonia Recovery Unit 104
Figure 9.9- Gas Cooler 107
Figure 9.10- Air mixture before gas cooler 108
Figure 9.11- Dryer 109
Figure 10.1- kiln 113
Figure 10.2- Air preheated 115
Figure 10.3- Dryer 117
Figure 10.4- Cyclone 119
Figure 10.5- Air mixture before gas cooler 120
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Figure 10.6- Gas cooler 122
Figure 10.7- Slaker 124
Figure 10.8- NH3 Recovery column 126
Figure 10.9- Carbonation column 130
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Chapter 1 INTRODUCTION
CHAPTER 01
1
INTRODUCTION
Sodium carbonate or soda ash is used in many
process industries such as in glass
manufacturing, Detergents & soaps, Metals and
mining, Paper and pulp and Textiles industries.
Raw materials for the manufacturing of sodium
carbonate are readily available and inexpensive.
Raw materials for the Sodium carbonate can be
obtained from sea water and lime stone mines
exist in number of places in the country……
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Chapter 1 INTRODUCTION
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In developed areas of the world mainly in the western European countries and in North
America the annual dollar value of industrial mineral production has surpassed that for metals and
continues to grow rapidly. This is due to the fact of high income levels per capita consumption of
industrial mineral products in developed Countries exceeds that in developing countries. While in
developed countries industrial minerals and rocks provide inputs in many industrial processes, in some
developing countries with little industrial infrastructure significant portions of their foreign exchange
derive from exports of industrial minerals like Sri Lanka. Thus, industrial minerals are of great
economic value to developed and developing economies alike.
When we consider the Sri Lankan perspective as one of the developing countries the scenario
mentioned above applies without much deviation. Sri Lanka is a country which is rich in minerals and
natural resources, but these have not been utilized to an extent where they will contribute to the
country production and hence to its development. Sri Lanka as a county can capitalize on its exports if
it were to manufacture value added products from the existing resources instead of an economy based
on export of raw materials to industries in other countries.
Soda ash, the common name for sodium carbonate (Na2CO3), has significant economic
importance because of its applications in manufacturing glass, chemicals, detergents metals and
mining, paper and pulp, textiles industries and many other products. There are many evidences to show
that people have been using soda ash extracted from earth in crude form, in glass manufacturing
industries since ancient times. But the production of soda ash as an industry itself, emerged only
during the late 18th century.
Raw materials for the manufacturing of sodium carbonate are readily available and
inexpensive. Main raw materials can be obtained from sea water and lime stone mines exist in number
of places in Sri Lanka. So the purpose of our final year comprehensive design project is production of
sodium carbonate from brine and lime stone. The comprehensive design project is done as per the
requirement for the award of the B.Sc. (Honors) Engineering degree.
The literature survey that was conducted as part of the project included a thorough study on
several soda ash consuming and lime stone consuming industries in Sri Lanka. Since the Holcim
Cement plant in Palavi will have a considerable amount of relation to the proposed plant, as explained
in later chapters a brief study on its operations was also carried out.
The results of the design project for the commercial production of soda ash are presented. The
project has been performed in two stages. The first part concerns the feasibility of the project, literaturesurvey and the second part presents the detailed material and energy balances.
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Chapter 1 INTRODUCTION
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From the investigation into project feasibility, it is proposed to construct a plant using the
Solvay process for the production of soda ash and will deliver 50 tons per day of 99.5(wt) Na 2CO3. It
is envisaged that this soda ash production facility will be located in Karadipuval near Puttalam. The
process has been tailor-made and designed to utilize limestone available locally at the North-Western
area of the country. Saturated brine from the adjacent lagoon is the other raw material utilized for the
proposed soda ash plant. Coke for the combustion of limestone in order to produce CO2 for the process
will have to be imported. It is hoped that this project makes a contribution to further the cause of
national development by provision of a viable, cost-effective, and environmental friendly solution.
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Chapter 2 LITRETURE SURVEY
CHAPTER 02
4
LITRETURE SURVEY
Soda ash has a number of diversified uses that touch
our lives every day. Glass manufacturing is the
largest application for soda ash whether it is in the
production of containers, fiberglass insulation, or flat
glass for the housing, commercial building etc.
As environmental concerns grow, demand increasesfor soda ash used in the removal of sulfur dioxide and
hydrochloric acid from stack gases. Chemical
producers use soda ash as an intermediate to
manufacture products that sweeten soft drinks,
relieve physical discomfort and improve foods and
toiletries, Household detergents and paper products
are a few other common examples of readily
identifiable products using soda ash………
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Chapter 2 LITRETURE SURVEY
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2.1 General Information
2.1.1 Other Names for Sodium Carbonate
Soda ash
Carbonate acid.
Disodium salt
Dry alkali
Molecular formula:
Na2CO3
2.1.2 Physical Properties of Sodium Carbonate
Specific Gravity : 2.53
Solubility in water(22°C) : 22g/100ml
Melting Point : 851.0°C
Boiling Point : Decomposes before melting
pH (1% aq. solution.) : 11.5
Sodium carbonate is an odorless, opaque white, crystalline or granular solid. It is soluble in
water and insoluble in alcohol, acetone, and ether. Sodium carbonate reacts exothermically with strong
acids evolving carbon dioxide. It corrodes aluminium, lead and iron.
2.1.3 Hydrates of Sodium Carbonate
The three known hydrates exist in addition to anhydrous sodium carbonate.
Sodium carbonate monohydrate ( Na2CO3.H2O )
This contains 85.48 % Na2CO3 and 14.52 % water of crystallization. It separates as small
crystals from saturated aqueous solutions above 35.4 °C, or it may be formed simply by wetting soda
ash with the calculated quantity of water at or above this temperature. It loses water on heating, and its
solubility decreases slightly with increasing temperature. In contact with its saturated solution it is
converted to Na2CO3 at 109 °C.
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Sodium carbonate heptahydrate ( Na2CO3.7H2O ),
This contains 45.7 % Na2CO3 and 54.3 % water of crystallization. It is of no commercial
interest because of its narrow range of stability, which extends from 32 °C to 35.4 °C.
Sodium carbonate decahydrate ( Na2CO3.10H2O ),
Commonly called sal soda or washing soda which usually forms large transparent crystals
containing 37.06 % Na2CO3 and 62.94 % water. It may be crystallized from saturated aqueous
solutions below 32.0 °C and above -2.1°C or by wetting soda ash with the calculated quantity of water
in this temperature range. The crystals readily effloresce in dry air, forming a residue of lower
hydrates, principally the monohydrate.
2.1.4 Chemical Properties of Sodium Carbonate
Sodium carbonate is hygroscopic. In air at 96 % R.H. (relative humidity) its weight can
increase by 1.5 % within 30 minutes. If sodium carbonate is stored under moist conditions, its
alkalinity decreases due to absorption of moisture and carbon dioxide from the atmosphere. Water
vapor reacts with sodium carbonate above 400 °C to form sodium hydroxide and carbon dioxide.
Sodium carbonate is readily soluble in water and the resulting solutions are alkaline, as expected a salt
formed from a strong base and weak acid. At 25 °C the pH of 1, 5 and 10 wt % solutions are 11.37,
11.58 and 11.70 respectively. Sodium carbonate reacts exothermically with chlorine above 150 °C to
form NaCl, CO2, O2 and NaClO4.
2.1.5 Grades and Specification of the Soda Ash
Soda ash is produced in two principal grades, known as light soda ash and dense soda ash.
These grades differ only in physical characteristics such as bulk density and size and shape of
particles, which influence flow characteristics and angle of repose. Dense soda ash has a bulk density
of 950 to 1100 kg/m3, may command a slightly higher price than the light variety, and is preferred for
glass manufacture because the lighter variety leads to frothing in the glass melt. Light soda ash having
a bulk density at 520 to 600 kg/m3, is the normal production item direct from the calcining furnace and
is preferred by the chemical and detergent industries. Other physical properties, as well as chemical
properties and properties of solutions, are common to both grades of soda ash.
All commercial grades are chemically similar. As density differences are the main distinguishing
feature, Table 2.1 shows the typical market specifications of dense soda ash.
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Chemical composition
Sodium Carbonate (Na2CO3) ≥ 99.8 %
Sodium Oxide (Na2O) ≥ 58.4 %
Sodium Sulfate (Na2SO4) ≤ 0.10 %
Sodium Chlorite (NaCl) ≤ 0.03 %
Iron (Fe) ≤ 0.0005% ( 5 ppm)
Bulk density (0.96-1.04 g/cm3)
Particle size 75 micron - 850 micron
Table2.1: Market specifications of dense soda ash
2.2 Uses of Na2CO3 in Industrial Sectors
Figure 2.1: Distribution of soda ash by end use
The distribution of soda ash by end use in 2007 was glass, 49%; chemicals, 27%; soap and
detergents, 10%; distributors, 5%; miscellaneous uses, 4%; flue gas desulfurization and pulp and
paper, 2% each; and water treatment, 1%.
2.2.1 Glass Industry
Soda ash is used in the manufacturing of flat and container glass. When mixed in proportion
with sand and calcium carbonate, heated to the right temperature and then cooled quickly, the end
result will be a glass that has an excellent level of durability and clarity. Na2CO3 as a network
modifier or fluxing agent, it allows lowering the melting temperature of sand and therefore reduces the
energy consumption.
7
http://www.wisegeek.com/what-is-calcium.htmhttp://www.wisegeek.com/what-is-calcium.htm
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Chapter 2 LITRETURE SURVEY
Soda ash reduces the viscosity and acts as a fluxing agent in glass melting [soda-lime glass (flat
and container glass), fiber-glass, specialty glass (e.g. borosilicate glass)].
2.2.2 Detergent Industry
Soda ash is used in a large number of prepared domestic products: soaps, scouring powders,
soaking and washing powders containing varying proportions of sodium carbonate, where the soda ash
acts primarily as a builder or water softener. The addition of the soda ash prevents hard water from
bonding with the detergent, allowing for a more even distribution of the cleaning agent during the
washing cycle. In addition, soda ash has demonstrated an ability to help remove alcohol and grease
stains from clothing.
Sodium carbonate is a major raw material in the manufacture of sodium phosphates and sodium
silicates which are important components of domestic and industrial cleaners. Sodium carbonate is also
added to these detergents to produce formulations for heavy duty laundering and other specialized
detergents manufacture. Sodium carbonate may also be used for neutralizing fatty acids in the
production of soap.
2.2.3 Metals and Mining
Sodium carbonate is used for the production of metals in both the refining and smelting stages.
It is often used for producing a metal carbonate which can later be converted to the oxide prior to
smelting.
2.2.4 Steel Industry
Soda ash is used as a flux, a desulfurizer, dephosphorizer and denitrider. Aqueous soda ash
solutions are used to remove sulfur dioxide from combustion gases in steel desulfurization, flue gas
desulfurization (FGD) systems, forming sodium sulfite and sodium bicarbonate.
Na2CO3 + SO2 Na2SO3 + CO2
CO2 + Na2CO3 + H2O 2NaHCO3
2Na2CO3 + SO2 + H2O Na2SO3 + 2NaHCO3
8
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2.2.5 Paper and Pulp
Sodium carbonate solution is used for the production of sodium sulphite or bisulphite for the
manufacture of paper pulp by various sulphite processes.
2.2.6 Textiles
Sodium carbonate is widely used in the preparation of fibers and textiles. In wool processing it
is used during scouring and carbonizing to remove grease and dirt from wool. It is also used as a
neutralizer after treatment with acids.
2.2.7 Non-ferrous metallurgy industry
Treatment of uranium ores.
Oxidizing calcination of chrome ore.
Lead recycling from discarded batteries.
Recycling of zinc, aluminium.
2.2.8 Chemical industry
Soda ash is used in a large number of chemical reactions to produce organic or inorganic
compounds used in very different applications. It is used to manufacture many sodium-base inorganic
chemicals, including sodium bicarbonate, sodium chromates, sodium phosphates, and sodium silicates.
2.2.9 Other Applications
Production of various chemical fertilizers
Production of artificial sodium bentonites or activated bentonites
Manufacture of synthetic detergents
Organic and inorganic coloring industry
enameling industry
Petroleum industry
Fats, glue and gelatine industry, etc.
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2.3 Uses of NaHCO3 in Industrial Sectors
Sodium bicarbonate can also be manufactured by Solvay process.
Animal feeds to balance their diets to compensate for seasonal variations and meet specific
biological and rearing needs
Paper industry for paper sizing
Plastic foaming
Water treatment
Leather treatment
Flue gas treatment, especially in incinerators
Detergent and cleaning products such as washing powders and liquids, dishwashing products,
etc…
Drilling mud to improve fluidity
Fire extinguisher powder
Human food products and domestic uses: baking soda, effervescent drinks, toothpaste, fruit
cleaning, personal hygiene, etc.
Pharmaceutical applications: effervescent tablets, etc.
2.4 History of the Production
Before the advent of industrial processes, sodium carbonate, often-called soda ash, came
from natural sources, either vegetable or mineral. Soda made from ashes of certain plants or seaweed
has been known since antiquity.
At the end of the 18th century, available production was far below the growing demand due to
the soap and glass market. The French Academy of Science offered an award for the invention of a
practical process to manufacture soda ash. Nicolas Leblanc proposed a process starting from
common salt and obtained a patent in 1791.
The so-called Leblanc or black ash process was developed in the period 1825 till 1890. The
major drawback of this process was its environmental impact with the emission of large quantities of
HCl gas and the production of calcium sulfide solid waste which not only lost valuable sulfur but also produced poisonous gases. In 1861, Ernest Solvay rediscovered and perfected the process based
on common salt, limestone and ammonia.
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Competition between both processes lasted many years, but relative simplicity, reduced
operating costs and, above all, reduced environmental impact of the Solvay process ensured its
success. From 1885 on, Leblanc production took a downward curve as did soda ash price and by the
First World War, Leblanc soda ash production practically disappeared. Since then, the only production
process used in Western Europe as well as in main part of the world is the Solvay process.
In the meantime and mainly since the twenties, several deposits of minerals containing
sodium carbonate or bicarbonate have been discovered. Nevertheless the ore purity and the location of
these deposits, as well as the mining conditions of these minerals, have limited the effective number of
plants put into operation.
Worldwide capacity of soda ash manufacture
Table2.2 Worldwide capacity of soda ash manufacture
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2.5 Overview about Type of Production
Geographical location and site characteristics such as environmental matters, specific energy
resources, distribution methods, and trade barriers are key elements in a selection of processing
method. Soda ash is readily produced from either natural deposits or trona or by synthetic pathways.
Soda ash production methods are given below in historical sequence.
Le Blanc Process (synthetic soda ash)
Solvey Process (synthetic soda ash)
Dual and NA Processes (synthetic soda ash)
Monohydrate Process
Sesquicarbonate Process
Carbonation Process
Alkali Extraction Process
2.5.1 Le Blanc process
This process was invented by Nicolas Le Blanc, a French man, who in 1775, among several
others submitted an outline of a process for making soda ash from common salt, in response to an offer
of reward by the French academy in Paris. Le Blanc proposal was accepted and workable on a
commercial scale.
Reactions
2NaCl + H2SO Na2SO4 + 2HCL
4C + NaSO4 NaS + 4CO
Na2S + CaCO3 Na2CO3 + CaS
A mixture of equivalent quantities of salt and concentrated sulphuric acid is heated in cast iron
salt cake furnance. Hydrochloric acid gas is given off and sodium hydrogen sulphate is formed. The
gas is dissolved in water and the mixture is raked and transferred to the muffle bed reverbratory
furnance where it is subjected to stronger heat. Here sodium sulphate called salt cake is formed.
The cake is broken, mixed with coke and limestone and charged into black ash furnace. The
mass is heated and a porous grey mass know as black ash is withdrawn.
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The black ash is cursed and leached with water in the absence of air in a series of tanks. The
extract containing sodium carbonate, sodium hydroxide and many other impurities, is sprayed from the
top of a tower counter current to the flow of hot gases from the black-ash furnace.
This converts sodium hydroxide, aluminate, silicate, cyanate to sodium carbonate. The liquor is
concentrated in open pans until the solution is concentrated in open pans until the solution is
concentrated enough to precipitate sodium carbonate on cooling.
The product is calcined to get crude soda ash which is purified by recrystallisation. The liquor
remaining after removal of first crop of soda crystals is purified to remove iron and causticised with
lime to produce caustic soda. The mud remaining in the leaching tanks containing calcium sulphide is
suspended in water and lime kiln gas is passed through it. The following reaction occurs.
CaS + H2O + CO2 CaCO3 + H2S
The lean gas containing hydrogen sulphide is passed through another tank containing
suspension of calcium sulphide.
CaS + H2S Ca(SH)2
This solution is again treated with lime kiln gas liberating a gas rich in hydrogen sulphide.
Ca(SH)2 + CO2 + H2O CaCO3 + 2H2S
The hydrogen sulphide is burnt in limited supply of air in a special furnace in presence of
hydrated iron oxide as a catalyst to obtain sulphur.
H2S + 1/2O2 H2O + S
This sulphur is sublimed and collected.The hydrochloric acid produced by the Leblanc process
was a major source of air pollution, and the calcium sulfide byproduct also presented waste disposal
issues. However, it remained the major production method for sodium carbonate until the late 1880s.
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2.5.2 Solvay Process
In 1861, the Belgian industrial chemist Ernest Solvay developed a method to convert sodium
chloride to sodium carbonate using ammonia. The Solvay process centered on a large hollow tower. At
the bottom, calcium carbonate (limestone) was heated to release carbon dioxide:
CaCO3 → CaO + CO2
At the top, a concentrated solution of sodium chloride and ammonia entered the tower. As the
carbon dioxide bubbled up through it, sodium bicarbonate precipitated:
NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl
The sodium bicarbonate was then converted to sodium carbonate by heating it, releasing water
and carbon dioxide:
2 NaHCO3 → Na2CO3 + H2O + CO2
Meanwhile, the ammonia was regenerated from the ammonium chloride byproduct by treating
it with the lime (calcium hydroxide) left over from carbon dioxide generation:
CaO + H2O → Ca(OH)2
Ca(OH)2 + 2 NH4Cl → CaCl2 + 2 NH3 + 2 H2O
Because the Solvay process recycled its ammonia, it consumed only brine and limestone, and
had calcium chloride as its only waste product. This made it substantially more economical than the
Leblanc process, and it soon came to dominate world sodium carbonate production.
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2.5.3 Hou's Process
This process is developed by a Chinese chemist Hou Debang in 1930s. It is the same as the
Solvay process in the first few steps. But, instead of treating the remaining solution with lime, carbon
dioxide and ammonia is pumped into the solution, and sodium chloride is added until it is saturated at
40 °C. Then the solution is cooled down to 10 °C. Ammonium chloride precipitates and is removed by
filtration, the solution is recycled to produce more sodium bicarbonate. Hou's Process eliminates the
production of calcium chloride and the byproduct ammonium chloride can be used as a fertilizer.
2.5.4 Dual process
In this process ammonium chloride is produced as a co product in equivalent quantities anddiffers from conventional, Solvay process and it does not recycle ammonia.
The mother liquor from the carbonating system, containing ammonium chloride, unreacted salt
and traces of carbonate is ammoniated in ammonia absorber. The ammoniated mother liquor is passed
through a bed of salt in a salt dissolver. Exit liquor from the dissolver, saturated with salt, is gradually
cooled from 400 C to 10
0 C by evaporation under vacuum to separate ammonium chloride. The slurry
containing ammonium chloride is centrifuged and dried. The product is 98% pure and is marked as
ammonium chloride fertilizer with nitrogen content of 25%.The mother liquor obtained after the separation of ammonium chloride crystals is recycled to
the carbonation vessels placed in series. Carbon dioxide obtained from ammonia plant and the calciner
section of soda ash plant is injected in the carbonation vessels. There is provision of cooling coils in
the lower carbonation vessels. Sodium bicarbonate is formed. The growth of crystals, of sodium
bicarbonate is controlled by the supply of cooling water to cooling water to cooling coils in
carbonation vessels. Sodium bicarbonate is thickened in a thickener and centrifuged. The sodium bi
carbonate is calcined to soda ash.
2.6 Sodium Carbonate Minerals
Whereas the production of sodium carbonate from the ashes of plants in salty soil near the sea
is only of historical interest, extraction from soda-containing minerals, especially trona, is of
increasing importance. The natural soda minerals occurred in the world is given in the following table.
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Types of Natural soda minerals occurred worldwide
Mineral Chemical Name Chemical Composition % Na2CO3
content
Trona Natural sodium
sesquicarbonate
Na2CO3.NaHCO3.2H2O 70.3
Nahcolite Natural sodium bicarbonate NaHCO3 63.1
Bredeyit Natural sodium bicarbonate 47.1
Gaylusitte Natural sodium bicarbonate Na2CO3.CaCO3.5H2O 35.8
Pirrsonite Natural sodium bicarbonate Na2CO3.CaCO3.2H2O 43.8
Thermonatrite Sodium carbonate
monohydrate
Na2CO3.H2O 85.5
Natron Sodium carbonate
decahydrate
Na2CO3.10H2O 37.1
Burkeit - Na2CO3.2Na2SO4 27.2
Dawsonit - NaAl(CO3)(OH)2
35.8
Hankcite - Na2CO3.9Na2SO4.KCl 13.5
Sortite - Na2CO3.2CaCO3 34.6
Table 2.3: Natural soda minerals occurred worldwide
Only Trona and Nahcolite are the minerals those commercial interest. These Na2CO3
containing minerals were formed from the original rock by the erosive action of, air, water, heat, and
pressure, followed by chemical changes caused by the action of atmospheric carbon dioxide. The
carbonate containing salts formed were leached by water and then concentrated and crystallized by
evaporation.
2.6.1 Trona Based Process
The production of sodium carbonate from the ashes of plants in salty soil near the sea is only of
historical interest, extraction from soda-containing minerals, is of increasing importance. Trona,
hydrated sodium bicarbonate carbonate (Na2CO3.NaHCO3.2H2O), is mined in several areas of the
world.
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This underground dry Trona processing consists in several steps:
First Trona has to be mined by the room and pillar or long wall method mechanically.
As Trona is an impure sodium sesquicarbonate mineral (Na2CO
3·NaHCO
3·2H
2O), it has to be
calcined to produce a soda ash still containing all the impurities from the ore.
Next, calcined Trona is dissolved, the solution is settled and filtered to remove impurities
(insoluble and organics), and the purified liquor is sent to evaporators where sodium monohydrate
crystals precipitate.
The monohydrate slurry is concentrated in centrifuges before drying and transformation into dense
soda ash.
Deposits from Trona lakes and solution mined Trona are processed as follows:
Dissolving Trona in wells
Carbonation of the solution in order to precipitate sodium bicarbonate filtration of the slurry and
Calcination of the bicarbonate to get light soda ash , recycling of the carbon dioxide to the
carbonation
Light soda ash transformation into dense by the monohydrate method
Carbon dioxide make-up produced by burner off-gas enrichment
2.6.1.1 Trona Products
Various Forms of Sodium
Carbonate
Formula
Anhydrous sodium carbonate Na2CO3
Sodium carbonate monohydrate Na2CO3. H2O
Sodium carbonate heptahydrate Na2CO3 .7H2O
Sodium carbonate decahydrate Na2CO3 .10H2O
Caustic Soda ( NaOH )
Sodium Bicarbonate ( NaHCO3)
Sodium Derivatives
Table 2.4: products of Trona
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2.6.1.2 Monohydrate Process
Soda ash is generally produced from trona by monohydrate process that produces only dense
soda ash. The first FMC Wyoming Corporation plant using this process went into operation in late
1972. In this process, the trona ore is first converted to crude soda ash by calcination and all
subsequent operations are performed on the resulting carbonate solution, as given in following figure.
Figure 2.2: Flow diagram of monohydrate process
Crushed Trona is calcined in a rotary kiln to dissociate the ore and drive off the carbon dioxide
and water by the following reaction:
2 (Na2CO
3. NaHCO
3.2H
2O)
(s). 3 Na
2CO
3 (s)
+ 5 H2O + CO
2
The calcined material is combined with water to dissolve the soda ash and to allow separating
and discarding of the insoluble material such as shale or shortite by settling and /or filtration. The
resulting clear liquid is concentrated as necessary by triple-effect evaporators, and the dissolved soda
ash precipitates as crystals of sodium carbonate monohydrate, Na 2CO3.H2O. Other dissolved
impurities, such as sodium chloride or sodium sulfate, remain in solution.
The crystals and liquor are separated by centrifugation. The sodium carbonate monohydrate
crystals are calcined a second time to remove water of crystallization. The resultant finished product is
cooled, screened.
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2.6.1.3 Sesquicarbonate Process
An alternate method of soda ash production from trona is the sesquicarbonate process. This is
the original process, developed by FMC Wyoming Corporation and put in operation in 1953, for
producing pure soda ash from Wyoming trona.
Trona ore is leached in recycled mother liquor at as high a temperature as possible to maximize
the amount dissolved. The solution is then clarified, filtered and sent to a series of evaporative cooling
crystallizers where sodium sesquicarbonate (Na2CO3.NaHCO3.2H2O) is crystallized. Carbon is added
to the filters to control any crystal modifying organics. The purified sesquicarbonate crystals may be
calcined to produce a light soda ash product. Simplified flow diagram of sesquicarbonate process is
shown in following figure.
The mother liquor is recycled to the dissolvers. In a variation of the process, trona ore is
dissolved in hot water and the centrate is returned to the evaporator crystallizer (Haynes, 1997). This produced soda is the light soda ash. Densities similar to the monohydrate soda ash may be achieved by
subsequently heating the material to about 350 °C. Alternatively, soda ash can be converted to the
monohydrate and then calcined.
Figure2.3: Flow diagram of sesquicarbonate process
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2.6.1.4 Alkali Extraction Process
Alkali extraction process is mainly to dissolve crude trona in an aqueous sodium hydroxide
solution. In this process, trona is dissolved in an aqueous sodium hydroxide to obtain pregnant sodium
carbonate solution. This method is generally used for bicarbonate content that dissolves to be an
incongruent consisted in trona. The diluted solution has a composition of 2-7 % caustic soda.
Dissolution reaction is given as follows:
Na2CO3.NaHCO3.2H2O + NaOH 2 Na2CO3 + 3 H2O
The solution at 30 °C was filtered and the pregnant carbonate solution is heated, sufficient
water is evaporated to form slurry of sodium carbonate monohydrate crystals and aqueous sodium
carbonate. The slurry was filtered and the mother liquor was recycled to dissolve raw mineral. Theregeneration was done by adding sodium hydroxide to the mother liquor.
The monohydrate crystals were dried and calcined. The most important parameters in alkaline
extraction process are; the dissolution temperature, concentration of sodium hydroxide and evaporative
crystallization temperature. The appropriate temperatures for the dissolution and evaporative
crystallization are 30 °C and 100 °C respectively. The flow diagram of alkali extraction process is
shown in following figure.
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Figure 2.4: Flow diagram of alkali extraction process
In a trona bed, the effect of water on the solubility of sodium carbonate will decrease due to the
precipitated bicarbonate. In the conventional mining technique, bicarbonate can be converted to
carbonate with a pre-calcination stage. The problem associated with the presence of sodium
bicarbonate in trona deposits can be solved by applying of sodium hydroxide solution. The required
amount of sodium hydroxide is the stochiometric amount that is necessary to convert all of the
bicarbonate to carbonate. The aqueous sodium hydroxide solvent preferably contains 1-15 wt% NaOH.
Using an excess of sodium hydroxide causes unreacted NaOH to remain in the solution and this effect
decreases the solubility of sodium carbonate.
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2.6.2 Nahcolite based process
A Nahcolite deposit has been found in several places in the world.
Nahcolite is processed as follows:
By solution mining (wells, with injection of hot mother liquor returned from the surface facilities),
Nahcolite is separated.
As nahcolite is an impure sodium bicarbonate mineral (NaHCO3), it must be treated.
The hot solution is decarbonated by heating. Then the solution is sent to settling and filtration.
Next, the purified liquor is sent to evaporators where sodium monohydrate precipitates.
The slurry is concentrated by centrifugation and the monohydrate crystals transformed to soda ash
by drying. The mother liquor is sent back to the solution mining
2.7 International Scenario
The present global capacity of soda ash is 37.0 million tones per annum and the long term
growth rate is 1.5-2%.
The major technology suppliers for the soda ash plant are:
Solvay and Cie SA, Belgium
AKZO-ZOUT Chemie BV, Netherlands
Asahi Chemical Industry, Japan
Polimex Cheepok, Poland
Technology Exports Divn, DSTA, China
The basic process for the manufacturer of soda ash has not undergone much change since last
130 years. Developments however are taking place in the following areas:
Process technology
Operation technology
Improvement of quality
New product from waste
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2.8 Structure and Status of Indian Industry
The manufacture of soda ash in India started in 1932 at in Gujarat with an installed capacity of
50 tons per day.
This was followed by the entry of another Chemicals manufacturing plant at Mithapur in
Gujarat in 1894 with an installed capacity of 100 tons per day. In a span of 50 years it has grown to be
the biggest soda ash unit in the country with daily capacity of 2000 tones.
In the same region in Gujarat, two more soda ash plants came up after-wards. First one was
commissioned in 1959 with a capacity of 200 tons per day which has been expanded to 800 tons per
day. Second one was commissioned in 1988 with a capacity of 1200 tons per day. All these four units
in Saurashtra in Gujarat are based on Solvay process.
Three units are operating on the modified Solvay process (Dual Process) in which ammonium
chloride is the co-product. The first plant based on this technology was set up in 1959 at Varansai, with
an installed capacity of 120 tons per day. The two other units operating on Dual process are at a
capacity of 200 tons per day. The present installed capacity of six soda ash manufacturing units is
17.09 lakh tones.
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CHAPTER 03
24
FEASIBILITY STUDY
The feasibility analysis is a preliminary study
undertaken to determine a project's viability or
the discipline of planning, organizing, and
managing resources to bring about the
successful completion of specific project goals
and objectives. The results of this study are used
to make a decision whether or not to proceed
with the project. In the case of the soda ash plant
an analysis of possible alternative solutions and
scenarios that has an impact on the proposed
was done and recommendations have been made
on the best alternative.
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3.1 Preliminary Study
As a preliminary study of the prospective soda ash plant a simple feasibility analysis has been
summarized in this chapter. The main objective of this feasibility is to explore the economical aspects
of the process and other concerns like environmental, technical, social issues that may arise as a result.
It can be said that the necessity of the plant is primarily based on final out come of the plant
and the market availability for its products. The bulk of the soda ash imported into the country is
primarily for the consumption of the glass industry. The main player in the present glass industry in Sri
Lanka is ‘Ceylon Glass’ with a daily consumption of almost 20 Metric Tones per day. A considerable
growth in the consumption of Soda ash can be seen within this single entity itself.
SODA ASH IMPORTS (2006)
Country QuantityKg
Value Rs.
Bulgaria 619000 17120020
China 975407 28721920
India - 9342
India 4089598 101802615
Iran 83284 2643973
Japan 1 4282
Kenya 792000 15948728
Malaysia 1 9510
Pakistan 100000 3496878Romania 440000 13901583
Singapore 725350 19914608
Taiwan 78 26244
Turkey 36000 960489
U.K. 469 824657
Ukraine 175000 3573407
Total 8,036,188 208958256
Avg price of 1kg of imported Na2CO3
(Rs) 26.00
Average consumption per day 22016.95342 kg
22.01695342 MT
Figure 3.1: Soda ash imports (2006)
When we consider the total soda consumption based on the amount imported to the country it can be
clearly seen from the above graph (figure 3.1)that an average of almost 40 MT (2008)is consumed
daily. Also a considerable increase in the amount demanded per year is depicted in the figure 3.2.
Therefore a daily production capacity of 50 MT on a continuous basis is justifiable.
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Variation of Soda ash imports
0
5
10
15
20
25
30
35
40
45
2004 2005 2006 2007 2008
year
M T / d a y
Figure 3.2: Variation in soda ash imports
The present average imported price per kg of soda ash is `23`1. The cost incurred for the
production of a single kg based on the raw material costs, maintenance and operation costs and other
overheads will be far less than the importing price because of the availability of CaCO3 deposits in Sri
Lanka at a considerable degree of purity, availability of skilled workers at considerably lower wage
rates and mainly due to the avoidance of cost for freight services. But the lower price in itself doesn’t
justify the high capital cost that has to be incurred for the implementation and construction of soda ash
plant based on the Solvay process. A further in-depth analysis with considerations of strength of export
market, pay back period, etc has to be taken into account.
26
When we consider the importing scenario there are considerable fluctuations in the demand for
soda ash and related products. It was noted that most of the soda ash imported to the country is in the
form of high dense soda ash. This is because high dense soda ash is one of the main raw materials of
the glass industry and most of the soda ash imported to the country is consumed by the same industry.
A main factor for the increased price of the imported soda ash in to the country is because of the fact
that different local companies import soda separately in small amounts and because of the cost
incurred for the freight services. Also as mentioned above the unstructured importing from various
suppliers and the unavailability of an agent to handle the soda import has led to higher prices. Another
factor that would lead to higher prices when importing is because of levies and taxes that has been
imposed on imported products and charges at the customs. Since soda is being imported to the country
at a higher price the related industries face restrictions in implementation and expansion because they
have a huge problem of
the market share because of the high final cost.
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The main raw materials for the production of soda ash from the Solvay process are Brine and
Calcium Carbonate. When we consider the availability of these raw materials in Sri Lanka, brine is
present in the form of sea water all around the country and Calcium Carbonate can be obtained from
sand stone or Dolomite reserves present throughout the country. Pure Miocene sand stone can be found
in the land strip stretching from Puttalam to the Jaffna peninsula. Dolomite reserves are present to the
middle of the country. Areas well known in this aspect is present in the Matale district. Also Calcium
Carbonate can be found in the form of coral reefs in various parts of the costal belt in Sri Lanka though
this is not an environmental friendly and feasible option. Also sea shells that is present in the costal
areas is a good form of Calcium Carbonate but this is not a viable and secure raw material source for a
soda ash production facility of the proposed scale. Therefore it can be concluded with confidence that
a local soda ash production plant will be able to get the essential raw materials easily. Therefore based
on this preliminary feasibility analysis it can be said that building a soda ash plant in Sri Lanka would be profitable.
In addition to the facts highlighted and discussed above, the feasibility has been further divided
and analyzed as economical, legal and administrative; market feasibility as part of the initial
evaluations and technical, social and environmental feasibilities have been analyzed as a measure of
viability when work is in progress.
3.2 Economical Feasibility
• Impact on local industry- Soda ash is one of the most important raw materials for the
manufacturing as well as process industry. It can be used as a raw material for the production
of glass, polymers, etc. Also it is extensively used in the process industry as a raw material in
the production of various chemicals, fertilizers, etc. When soda ash is available locally at a
lower price and most importantly in form of a continuous, secure supply there would be a
considerable boom in the above mentioned industries. Also since the there would be
developments in industries that are in parallel with this industry. For example saturated brine is
required as a raw material in the Solvay process. Hence a salt production facility in the area can
be utilized to provide saturated brine.
• Impact on economy of area- As studied and evaluated under chapter 5 the location of the soda
ash plant is designated as Karadipuval site in Puttalam. The Holcim Lanka cement plant and itsquarry is located in the puttalam district. The Aruwakkaru Limestone Quarry site of Holcim
Lanka Ltd is used to extract limestone to produce cement in Palavi plant of Holcim Lanka (pvt)
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ltd. This is the only quarry in operation to extract limestone which is 150 km away from
capital city Colombo of Sri Lanka. Other than few industries the area presently can be
considered as remote or rural. With the establishment of the soda ash plant and the completion
of Norochcholai coal power plant the area will comprise of 3 main industries and would be
similar to an industrial zone. The Norochcholai coal power plant already has many
infrastructure developments which include the development of a port. The development of such
industries will lead to considerable development of the facilities, economy and availability of
jobs in the area.
• Reduction of Imports- When we consider in a macro scale there will be considerable amount
of savings when the production of Sri Lanka is increased. This in tern will benefit the country
as a whole because of increase in GDP, reduction of unemployment, drop of inflation, increase
of local currency.
• Opportunity for export- There are several industries that consumes soda ash as a raw
material. Also there is a high demand for soda ash in neighboring India and other south Asian
countries. Though India is one of the major producers of soda ash in the world it utilizes the
Dual purpose method to cater the fertilizer demand in the country and most of the plants aresited north of the country. Also the dual purpose method leads to higher cost for the soda ash
because NH3 used in the process is of high cost. Therefore there would be considerable market
for soda ash produced in Sri Lanka in the south Indian region. Also there would be
considerable demand for end products like glass that is made from soda ash throughout the
south Asian region.
• Increase of production- The availability of locally produced soda ash will lead to a boom in
the soda related industries. This would lead to the possibility of expanding local industries and
emerging of new ones. Such an increase of production, production capacity and availability of
raw materials would make Sri Lanka attractive to investors.
• Production costs- As mentioned earlier the availability of raw materials locally for the
production of soda ash in Sri Lanka itself will lead to reduction production cost. Also the
availability of skilled workers and manpower at a relatively lower wage rates comparative to
that of other soda ash producing European counterparts will lead to reduced cost. But it needs
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to be noted that the other overhead costs in Sri Lanka would be somewhat higher because of
high electricity tariffs and condition of infrastructure.
• Incentives and levies imposed on the industry- Presently there are various levies and taxes
imposed on imported goods. But Ceylon glass which is involved with importing most of the
soda ash into the country for its production activities has a considerable concession as part of
the agreement with the government when it was taken over by an Indian company. Even
though this is the case if soda ash is produced locally the government would impose taxes on
imported soda ash to promote the local producer.
• Government support- Since a soda ash production plant is a huge production facility and it
would be involved with providing jobs for considerable amount of people the government is
likely to act in favor of the local soda ash producer. Government support at a considerable
degree would be required because purchasing of land in the proposed area under Chapter 6,
establishment of infrastructure support, environmental impact mitigations, obtaining quarrying
rights for limestone, provision of security from terrorist threats etc would require government
intervention and support.
• Security- As discussed later in Chapter 5 the most suitable location for the proposed soda ash
plant is at Karadipuval in Puttalam. Though more pure Miocene Limestone deposits are
available in the Jaffna Peninsula, it will not be a likely option because of the terrorist activities
present in the area and the on-going war effort. When we consider the site at Puttalam a secure
security situation has been prevailing for several years. Also a tight security parameter
presently has been set in the area which would be further strengthened once the Norochcholai
coal power plant has been commissioned. Therefore it can be said that the security threat or
risk is minimum.
• Inflation and its impact- The present inflation rate of the country is very high. Therefore this
would negatively impact on the project at the construction and maintenance phases because
most of the equipment would have to be imported. But once the plant is running the soda
produced and sold locally would not be severely affected. But the competitive edge of soda ash
that is to be exported would be lost.
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• Regional impact- A major administrative and management issue that would affect the
functioning of the plant is the environmental concerns and waste management. When the plant
has necessary control measure in-place, which is used successfully in other parts of the world,
this threat can be avoided.
• Impact from other main industries in the area (Holcim) - An administrative issue that the
company involved will have to face is when obtaining quarrying rights to the limestone quarry.
At present Holcim Lanka is involved with quarrying activities at Aruwakkaru. Since this site
has already been reserved by the cement company obtaining quarrying rights and reserving of
limestone deposits would be necessary.
When we consider the economical evaluation as a whole after considering lagal and
administrative issues the implications are positive. But since this is a preliminary feasibility
analysis of the project in-depth cost and benefit analysis are not possible. But when viewing the
above facts and considering the economical parameters, it can be said with certainty that the
expected outcome would be positive.
3.3 Market Feasibility
• Market trends – Presently there is considerable market trend towards the development of soda
and salt related industries in Sri Lanka. This will result in a huge demand for soda ash which is
being used as raw material. Also there is tremendous potential for the development of the glass
industry. For instance Ceylon Glass moved from their conventional plant at Ratmalana and
built a new one at Horana to cater the increasing demand. Therefore it can be said with
confidence that there would be considerable demand for locally produced soda ash with the
expected boost in industry.
• Allowance for expansion- As mentioned in the economic feasibility and later on in the site
layout selection there is considerable potential for expansion. The present demand for soda ash
is about 40 MT/day. The proposed plant has a capacity of 50MT/day with an allowance of 10
MT/day. In the event of a huge increase in the market a new plant or an expansion of the plant
itself would be required. The land selected under the latter chapter of site selection has
allowance for such an expansion.
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• Sales generation- As highlighted above the current market price for soda ash is around Rs 25.
According to the present economic evaluation it can be said that a kg of soda ash can be
produced from a cost of around Rs 8 which means that the gross profit is considerably high.
• Pay back - As mentioned above the gross profit per kg of soda ash sold is high. Therefore it can
be said that the payback would be less event though a thorough evaluation with a detailed
financial statements would be required for in order to estimate the payback accurately.
• Sales and marketing concerns- At present there won’t be any marketing concerns because
there are no other players in this industry. The only competitor would be soda ash importers.
But there are no big importers that have specialized in this business, currently in Sri Lanka.
Also since the government is biased towards the development of the local industry there would
be restrictions on imports once the plant has commenced production. Also since the no of
consumers if Soda ash is less a highly costly marketing campaign would be meaningless.
• Distribution network – As mentioned above since the consumers of soda ash is less the ideal
distribution network would be a one-to-one system. For example when soda ash for the glass
company can be sold to the Ceylon glass (pvt) ltd directly without the involvement of
intermediates and complex sales networks. This would benefit the producer as well as the
consumer because of simplicity and high profitability.
3.4 Technical Feasibility
• Infrastructure requirement- The proposed plant with a capacity of 50 MT/day would require
considerable amount of infrastructure and utility processes. Normally Solvay process plants are
considered to be some of the biggest plants in the world. The plant would require a road
network, railroad or durable road to transport limestone from the quarry, uninterrupted
electricity, basic water supply and process water, etc. The producers would have to build the
internal road network as required. In the event of building a rail network for the transportation
of limestone from the quarry the company would require the assistance of the governments.
The case would-be the same if the plan to transport limestone from the quarry to the plant in
Lorries and vehicles because a road with reinforced layer would be required. The plant could
fulfill its power requirement by means of electricity from the National grid and power
generated from steam/cogeneration at the plant. The plant can fulfill its domestic water
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requirement from the National water supply lines. But the process would require extensive
amounts of process water. Since the use of treated and purified salt water for this purpose
would not be feasible the need will have to be met by water from dug wells or stream/river.
• Geological aspects- A process plant of this scale would require a strong foundation. Therefore
the stability of the bedrock on which the plant is sited, is of importance. The land of Puttalam
area consists of hard, moisture free soil. It has already been proved that the bedrock in the
Puttalam area is one of the best to locate process plants by the survey done for the
Norochcholai coal power plant. This is a positive aspect. But the soil in the area, especially in
places near the lagoon and the salt production plants the soil consist of salts which might be
harmful to the plant. By adopting necessary coatings on surfaces and having corrosion
allowances this problem can be solved.
• Availability of skilled workers and professionals for maintenance of plant- At present the
district of Puttalm doesn’t comprise of a considerable skilled and professional workforce.
Hence the human force requirement will have to be met by resident workers from other areas of
the country. But it is possible to obtain unskilled laborers from the area for the plant
construction activities and maintenance when the plant has been commissioned.
• Availability of construction companies- At present Sri Lankan Process development
companies doesn’t have the experience and capacity for the construction of a Solvay plant with
a daily capacity of 50MT. Hence the assistance of process plant construction companies abroad
with experience in similar construction activities will be required.
• Availability of expert consultancy firms- At present there are companies that have extensive
amounts of technical expertise regarding the Solvay process. Some of them are given below.
Solvay and Cie SA, Belgium
AKZO-ZOUT Chemie BV, Netherlands
Asahi Chemical Industry, Japan
Polimex Cheepok, Poland
The technical assistance of such a consultancy provider will be required to oversee the
construction activities and provide process consultancy when the plant has been commissioned.
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• Fabrication concerns- Presently Sri Lanka has the capacity for fabricating most of the process
vessels required for the plant. Other equipment that cannot be produced locally will have to be
imported or fabricated and shipped to Sri Lanka.
• Imported equipment transportation- The port that has been built at Norochcholai is to be
used as a transportation channel for the imported equipment of the Norochcholai Coal Power
Plant. The same port can be used when bringing Heavy process equipment or vessels for the
proposed soda ash plant.
3.5 Social Feasibility
• Social condition of people- The living standard of an average resident in the area is low. Most
of the population is farmers. The proposed plant will not have a huge impact on the residents of
the area since not much farming is done or vegetation is present in the chosen area. It cannot be
said that the plant will be involved to a great extent in uplifting the living standards of these
people, but there are certain direct and indirect means related to the activities of the plant
through which the local population can thrive and earn an extra income.
• Resettlement and rehabilitation- This will not be a problem because the land chosen is a
piece of bare land. Therefore no concern of this matter would be required. But in the event of
placing rail lines from the existing one from the Holcim factory to the quarry, acquiring of
certain land plots from the residents will be required. But even in this case resettlement or
rehabilitation will not be a concern because this project will not need land from a process of
nationalization.
• Social resistance- The construction of the plant will definitely have to face public pressure and
cultural resistance, as quite evident from other projects of this sort. The pressure would mainly
be based on environmental issues, pollution and waste disposal. These resistances can be
subdued to a certain degree by implementation of the best available pollution control
techniques and waste management principles and increasing public awareness regarding them.
This scenario as whole will not affect the decision of implementation of the plant.
• Health and safety concerns- As mentioned above with the implementation of the best
available practices and by designing process vessels according to standards the risk of a
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disaster occurring due to failure can be avoided. By having a good training programme in-place
and by recruiting skilled and experienced workers there would not be a risk of health and
safety. Then it would not be a concern in the feasibility concern.
• Employment- One of the positive implications of the plant on the surrounding community is
the increase in job opportunities. These jobs can be in the form direct or indirect means. For
instance with the start of construction activities of the plant many laborers (both skilled and
unskilled), will be recruited from the area. Once the plant is complete and has been
commissioned people across a diverse range will get job opportunities. In recruiting of
recruiting such people the priority will be given to the locals in the area because the company
will then not have to bear accommodation and transport costs. Also with the establishment of a
new plant various businesses would come into being, whose activities are not directly related to
the operation of the plant. For example many new shops and stores would be established by
external people to cater the needs of the employees, suppliers, etc. This would result in the
provision of employment as well as flow of money into the area. But on the plant’s perspective
relying on employees from the adjacent areas alone, will not be sufficient because the lack of
skilled workers and professionals in the area will affect the operations of the plant. Therefore
the company will have to provide transport and accommodation to a certain degree to attract
employees with the necessary traits from other parts of the country.
• Local industry- At present in the Puttalam district, there are industries and commercial entities
that will directly benefit from the proposed soda ash plant at Karadipuval. For instance the
heavily spread saltern industries in the area discharge the Mother Liquor from the tanks after
salt has crystallized. But since this mother liquor with saturated Sodium Chloride is a raw
material for the soda ash industry the salterns can earn an income from their effluent. Also the
Holcim cement factory can benefit immensely by leasing out their assets like the quarry, rail
carriages, kiln for hazardous waste disposal, etc. Also the jetty/port that is being built in the
area can benefit from the activities of the plant. Other than these industries small commercial
entities like suppliers, caterers, transporters, etc also will get a new market onto which they can
expand their business.
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CHAPTER 04
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PROCESS SELECTION
The selection of an appropriate process is an
important decision, all the subsequent work
depends upon this choice. Although the selection
can be changed or modified at a latter stage, at
least before the plant is built, such a decision
results in a serious waste of time and
money……….
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4.1 Introduction
The stepping stone for the chemical revolution begun in Europe with the introduction of the
Leblanc process for the production of Soda by Leblanc in 1790. This industry used as raw materials,
salt, sulfur, limestone, saltpeter, coal, air, and water; its products were the alkalis, sodium carbonate
and sodium hydroxide. Cheap alkalis brought to the ordinary citizen those luxuries which had formerly
been enjoyed only by the rich and powerful: glass for bringing light into dark places, paper for
bringing the printed word into proletarian homes, and soap for bringing sanitation into cities oppressed
by filth and disease.
A highlight of the developments in the soda ash industry was witnessed when the Belgian
industrial chemist Ernest Solvay (in 1861), developed a method to convert sodium chloride to sodium
carbonate using ammonia. Other than the Leblanc and Solvay process there have been various
developments in the soda ash industry during the last 100 years. The processes that are present used for
the production of soda ash are given below.
Leblanc Process
Solvay Process
Dual Process
Akzo Dry Lime Process
New Ashai ( NA) Process
Akzo Zoul Chemie Method
Nepheline syenite process
Carbonation of caustic soda
Also Trona and nahcolite based process are used in different countries but this is not an option
in the Sri Lankan context because the island does not have soda ash reserves which can be mined and
processed under these methods to yield soda ash for consumption. In other words Trona and Nahcolite
processes are used for processing soda ash reserves to remove impurities within them. Also there are
some plants operating under the ‘Nepheline syenite process’ and ‘Carbonation of caustic soda’
method. But it is not possible to obtain soda ash of good quality from the Nepheline syenite process
and this would lead to additional cost for purification processes as demanded by soda ash consuming
industries. Also carbonization of caustic soda is not feasible for Sri Lanka at present because it is
dependent on imports to fulfill caustic soda requirements.
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4.2 Comparison of Solvay process with Others Methods of Production
As mentioned above in the introduction, Leblanc process was the industrial process for the
production of soda ash used throughout the 19th century. It involved two stages: Production of sodium
sulfate from sodium chloride, followed by reaction of the sodium sulfate with coal and calcium
carbonate to produce sodium carbonate. The Leblanc process was a batch process in which sodium
chloride was subjected to a series of treatments, eventually producing sodium carbonate.It is also
noteworthy that in addition to valuable alkalis, the Leblanc process produced two waste products,
hydrogen chloride and calcium sulfide. Acidic hydrogen chloride gas was sent up the chimney, after
which it decimated vegetation in the vicinity of an alkali works. Insoluble calcium sulfide was
conveniently disposed of in heaps where the vegetation used to be. Unfortunately, when calcium
sulfide reacts with rain water it farts out noxious hydrogen sulfide.
Hence alkali manufacturers based on Leblanc process became popular targets for lawsuits and
government regulations. The British Alkali Act of 1863, for example, required the absorption of 95%
of the hydrogen chloride produced by the salt cake furnace. This was easily accomplished, hydrogen
chloride being quite soluble in water; the waste gas was sent up through a stone tower filled with coke;
water dribbling down through the tower absorbed the hydrogen chloride, producing aqueous
hydrochloric acid.
In addition to hydrogen chloride which can be presently considered as valuable product own its
own account and after Henry Deacon in1868 introduced a process for turning waste hydrogen chloride
into bleaching powder, which could be utilized in paper and textiles industry, calcium sulfide produced
is a problem for soda manufacturers using the Leblanc process. This (calcium sulfide produced)
became a persistent problem owing to the twin problems of stinking heaps of tank waste, and the loss
of valuable sulfur. It is noteworthy at this point that pure source of Sulfur is not present in Sri Lanka.
An alternative to sulfur is sulfur dioxide which was obtained during the latter stages of the soda
industry from roasted from pyrites, which alternatively would have to be imported to Sri Lanka. Also
whatever the source may be, it will eventually end up as calcium sulfide waste. The only positive
solution for the disposal of calcium sulfide lies in the fact that it could be converted into sodium
thiosulfate, used by photographers to fix photographs but this cannot be considered as a feasible
option. Also at present there is a method of recovering sulfur from tank waste owing to the discoveries
of Alexander Chance in 1887. But these slight improvements would adversely affect the effi