Pemodelan & Evaluasi CadanganHendra Harisman, ST., M.Eng.Sc.

24 MARET 2015

Ore Reserve EstimationHendra Harisman, ST., M.Eng.Sc.

MINING SYSTEM

Introduction

• The relationship between exploration information, resources and reserves

Introduction

• Inferred• Indicated• Probable• Measured• Proved

Introduction

• Geologi:• increase in geological knowledge = ??

• Ekonomi:• economic information increases = ??

Definitions• Exploration information:

• Size• Composition• Shape• Grade

• Exploration methods:• Geological• Geochemical survey• geophysical surveys• drill holes, trial pits• surface underground openings.

Definitions• trial pits:

Definitions• Resource:

• a concentration or occurrence of material• Intrinsic economic interest• reasonable prospects for economic extraction

• Specific geological evidence and knowledge:• Location• Quantity• Grade• Geological• Characteristics and continuity

Definitions• Resources are sub-divided, in order of increasing

geological confidence:• Inferred• Indicated• Measured categories.

Note:• Portions of a deposit that do not have reasonable prospects for eventual

economic extraction must not be included in a Mineral Resource

DefinitionsInferred:

• can be estimated with a low level of confidence- Tonnage- Grade and - Mineral content

• from- geological evidence

• assumed but not verified- geological and/or grade continuity

DefinitionsIndicated:

• can be estimated with a reasonable level of confidence- Tonnage- densities- Shape- physical characteristics- grade and - mineral content

DefinitionsIndicated:

• Based on- Exploration- sampling and testing information

- appropriate techniques:- Outcrops- Trenches- Pits- Workings- Drill holes

DefinitionsMeasured:

• can be estimated with a high level of confidence- Tonnage- densities - Shape- physical characteristics- grade and - mineral content

DefinitionsMeasured :

• Based on- detailed and reliable exploration- sampling and testing information

- appropriate techniques:- Outcrops- Trenches- Pits- Workings- Drill holes

Definitions• Reserve:

• economically mineable part of a Measured or Indicated Mineral Resource

• Includes:- diluting materials and - allowances for losses that may occur when the material is mined.

• Appropriate assessments:• feasibility studies

• Mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors.

DefinitionsReserves relate to resources:• Probable reserve

• economically mineable part of an Indicated and, in some circumstances, Measured Mineral Resource.

• Includes:- diluting materials and - allowances for losses that may occur when the material is mined.

• Appropriate assessments:• feasibility studies

• Mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors.

DefinitionsReserves relate to resources:• Proved reserve

• economically mineable part of a Measured Mineral Resource.• Includes:

- diluting materials and - allowances for losses that may occur when the material is mined.

• Appropriate assessments:• feasibility studies

• Mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors.

DefinitionsWhen reporting a Mineral Reserve :• Tonnages• Grades and • Mineral or metal contents must be

reported

after taking into account mining loss and mining dilution

• also take into account processing recoveries• If not, the percentage expected to be recovered or lost

after processing must be reported.

Tonnage FactorTonnage factor:• conversion from volume of ore to weight of ore• normally expressed as cubic feet per ton of ore• dependent upon the specific gravity of the ore• specific gravity is a function of the mineral composition

of the ore

Tonnage Factor

Tonnage Factor

Tonnage Factor

Tonnage FactorMethods to determine specific gravity:• to calculate an average specific gravity using the specific

gravities of individual minerals• by weighing a core or specimen of the ore in air and then

weighing the same sample suspended in water.• carefully measure the volume of an excavation and weigh

the material extracted. The tonnage factor is simply the volume in cubic feet divided by the tons.

specific gravityThe most accurate method to determine specific gravity:• to calculate an average specific gravity using the specific

gravities of individual minerals• the relative percentages of ore minerals present are

accurately known

specific gravityby weighing a core or specimen of the ore in air and then weighing the same sample suspended in water:

• The specific gravity is calculated by the following formula:• Specific gravity = Wa /(Wa – Ww)

• If the ore volume has been computed in cubic meters, the volume multiplied by the specific gravity is the tonnage in metric tons directly.

specific gravityby weighing a core or specimen of the ore in air and then weighing the same sample suspended in water:

• The specific gravity is calculated by the following formula:• Specific gravity = Wa /(Wa – Ww)

specific gravityCalculating an average specific gravity using the specific gravities of individual minerals:• For example, if a massive sulfide ore is 10% galena, 35%

sphalerite, and 55% pyrite• Specific gravity = ??