MINERAL PROCESSING

Our laboratory conducts beneficiation studies of ores, industrial raw materials, and coal using various methods including gravity (e.g., jigging, shaking tables), flotation, magnetic separation, and hydrometallurgy. In addition to these beneficiation processes, we also work on evaluating mine waste, addressing issues in currently operating mining and beneficiation facilities, and carrying out performance improvement studies and revisions.

In these studies, comprehensive reports are generated based on the following aspects:

• Liberation particle size
• Method and machine selection
• Optimum grade and recovery distributions
• Determination and optimization of process reagents
• Reagent consumption per ton (in flotation and hydrometallurgy studies)
• Settling tests for thickener design

Comprehensive reports are prepared, leading to the final plant flow diagram, based on tests aimed at determining the equipment specifications.

The final report, along with interim presentations, aims to address and resolve potential issues encountered during implementation.

ARGETEST Mineral Processing and Research & Development Unit provides the services mentioned below:

• Lab scale mineral processing test studies
• Mineral process characterization and process mineralogy
• Pilot scale mineral processing test studies
• Mineral processing flowsheet design for plants
• Plant optimization and revisions
• Determining the plant problems with the site application and works on overcoming these problems
• On-site applied trainings

SIZE REDUCTION TESTS

2. SIEVE ANALYSIS (Dry/Wet)

Sieve analysis is performed to determine the particle size distribution of a sample composed of particles with different sizes and to establish a relationship between particle size and the amount of each fraction (i.e., to find the amount of particles in each size fraction). Parameters such as the type and structure of the sample, the narrowness/breadth of the desired fraction ranges, the type of processing to be carried out afterward, etc., determine the sieve sizes used during the sieve analysis and whether the process will be dry or wet. Accordingly, sieves of the desired sizes are arranged in sequence, and the sample is subjected to sieve analysis. The percentage weight distributions of the obtained particle sizes are determined both cumulatively and fractionally. The sieve sizes used during the test consist of standard sieve sizes used in the industry and conform to ASTM standards.

 

2.2. Crushing Tests

Crushing tests are conducted as the initial stage of the ore beneficiation to release valuable minerals (ore) from the gangue minerals in the largest possible particle size and to increase the surface area of the sample. Parameters such as the type and structure of the sample, the desired liberation size and size reduction ratio, and the type of processing to be carried out afterward determine the type of crusher used during the crushing test. To verify the particle size of the product obtained from the crusher, sieves with the same mesh size as the crusher aperture are used. The undersized sample is stored, while the oversized sample is fed back into the crusher, thus achieving a continuous crushing process.

 

2.2.1. Jaw Crusher

A jaw crusher is a type of crusher consisting of two plates (jaws) that form a narrow angle (25°-30°). While one jaw remains fixed, the other jaw moves via an eccentric shaft, and the sample stuck between them is crushed and exits as fragmented material. The jaw opening can be adjusted according to the desired particle size. Jaw crushers are ideal for primary and secondary crushing and are preferred for breaking hard and ore bodies with high toughness.

 

2.2.2. Roller Crusher
Size reduction occurs as the sample is nipped and crushed between two rollers rotating in opposite directions. The distance between the rollers can be adjusted based on the desired reduction ratio and the crusher output product length. It is preferred for crushing slag samples containing metal fragments and alloys, heat-treated samples, and ores with lower hardness compared to run-of-mine ore.

2.2.3. Hammer Crusher
In a hammer crusher, the gaps between the hammers and the grate bars are narrow, and the ore is crushed as it gets trapped in between. The size reduction occurs through a combination of attrition, shear, and impact forces. It is practical for crushing less abrasive materials like low-silica limestone or coal.

2.2.4. Cone Crusher
In a cone crusher, the cone is mounted at the top and supported by a curved bearing. The cone rotates 360°, crushing the ore as it gets trapped between the cone and the crusher walls. The crushed particles are then collected from the crusher's output. It is used in secondary and tertiary crushing circuits.

2.3. Grinding Tests
Grinding is carried out in drums that use the rotation of the drum to lift the grinding media, which then grinds the ore using a combination of impact, friction, and attrition forces to achieve the desired product size. The grinding media may be the ore itself (autogenous grinding) or manufactured metallic media (steel rods, steel or iron balls). Parameters such as the type and structure of the sample, the desired liberation size, the reduction ratio, and the type of subsequent beneficiation determine the mill type and grinding duration during the test.

2.3.1. Ball Mill
A ball mill is a drum-based wet grinding mill that uses metallic balls as the grinding medium. It is preferred for finer grinding. Due to the finer grinding, the sample stays in the mill for a longer retention time, which leads to increased slurry (slime) formation.

 

2.3.2. Rod Mill
In a rod mill, coarse-grained ore tends to spread between the rods, forming a conical series. This formation enables selective grinding and yields a product with a narrow particle size distribution. Additionally, the rod mill reduces the formation of unwanted slimes and minimizes the amount of coarse particles that remain unground. Steel alloy rods are used as the grinding medium.

2.3.3. Semi-Autogenous Mill
A semi-autogenous (SAG) mill is an autogenous mill where large rock fragments, as well as large steel balls making up 3-6% of the mill volume, are added. The grinding medium consists of large rocks, which break smaller pebbles through impact force and gradually wear down (abrasion) until they shrink to a size that can also be broken by impact, along with large steel balls. When choosing this method, attention should be paid to whether the ore size distribution is suitable for semi-autogenous grinding, and if so, parameters such as the size of the grinding medium should be considered.

 

2.4. Bond Work Index Tests (Ball Mill/Rod Mill)
The Bond Work Index provides the initial indication of the specific energy consumption (kWh/t) required to grind a particular ore. Since the Bond Work Index test requires only a small sample, it can quickly and accurately determine the specific energy consumption for different ore types using core samples or run-of-mine ore in the early stages of a project. Depending on the hardness, structure, and grindability of the ore, either a ball mill or a rod mill can be used for the test. The grinding is conducted continuously. After each test, a standard sieve analysis is performed on the sample before proceeding to the next test. Once all tests are completed, engineering calculations are made, and the Bond Work Index for the ore is determined.

 

3. 3. PROCESSING TESTS

3.1. Gravimetric Separation Tests
In cases where the density difference between ore and gangue minerals is significant, after achieving the required liberation, gravimetric separation methods are used to obtain concentrate and waste products.

 

3.1.1. Jig
The jig enrichment process involves separating mineral particles of different specific gravities in layers within a vertically moving fluid medium. This process uses gravity and hydrodynamic forces to create separation. Pulsation movements (upward pushing and downward suction) are applied to the fluid medium, resulting in layered formations based on density differences. Heavy minerals settle in the lower layers, while lighter minerals remain in the upper layers.

 

3.1.2. Shaking Table
The shaking table is one of the fundamental gravimetric separation devices for fine particle sizes. Due to differences in density and size between ore and gangue minerals, they are separated according to the flow regime and table movement. The table is equipped with riffles (grid lines) at certain intervals, and at the end where the concentrate is collected, the riffle height is zero.

 

3.1.2.1. Gemini Shaking Table
The Gemini-type shaking table is known for producing bullion-grade gold products with high recovery rates from low-grade concentrates. This table design allows for the production of a gold concentrate that can be directly converted into bullion. Under the influence of a vibratory wave, sample particles move vertically and horizontally based on different proportions and granularities and are discharged from the concentrate and waste outlets.

3.1.3. Heavy Media Separation
This method uses the density difference between ore and gangue minerals by employing a heavy media liquid. In our laboratory, we use Sodium Polytungstate (SPT) with four different densities (2.82 g/cm³, 3.0 g/cm³, 3.2 g/cm³, and 3.5 g/cm³) as the heavy media liquid. Prior to separation, the feed material is thoroughly washed and dried, then subjected to a series of sink-float tests at various densities. The result is different density concentrates and waste samples.

3.2. Separation Tests Using Centrifugal Force
As particle size decreases (≈-0.05 mm), the efficiency of traditional gravimetric separation methods diminishes. One of the developed methods for finer particles is centrifugal force-based separation.

3.2.1. Falcon Separator
The Falcon separator works by applying high G-forces, effectively capturing fine particles that might otherwise be lost in low-G force methods. It is commonly used in the recovery of gold, silver, and platinum group metals. In this process, the pulp sample is fed into a rotating bowl, where the heavier particles are more affected by centrifugal forces compared to the lighter ones. As a result, heavier particles move towards the bowl's surface, while lighter particles exit the device with the upper layer of the pulp.

3.2.2. Hydrocyclone Separator
The hydrocyclone is the primary classifier type used for wet processing of fine and ultra-fine particles. The feed is introduced tangentially and under pressure, initiating a rotational motion within the cyclone. As the pulp moves within the cone-shaped sections of the hydrocyclone, it gains momentum, leading to a low-pressure vortex at the center where finer and lighter particles continue to move upward. These lighter particles exit through the vortex finder at the top, while heavier particles are carried downwards through the apex region with a downward rotating flow. The main forces at work in the hydrocyclone are centrifugal and drag forces. The target solid content for the feed material is typically between 15-20% by weight.

3.2.3. Spiral Separator
The spiral separator consists of a half-circle cross-section channel that forms multiple turns and spirals around a central support column. The feed is introduced at a controlled flow rate to ensure a smooth and steady pulp flow over the spiral surface. Along the lower section of the spiral, there are several discharge outlets positioned at intervals, allowing the separation of concentrate and waste materials. The feed material for the test should have a particle size of no more than 2 mm.

3.3. Magnetic Separation Tests
Magnetic separation is conducted based on the magnetic susceptibility of the sample, with varying magnetic field strengths used to separate ore and gangue minerals through dry or wet processing. Working with a sample that has a narrow particle size range is important for optimal test efficiency. Low-intensity magnetic equipment is used to concentrate ferromagnetic minerals (those with high magnetic susceptibility), while high-intensity equipment is utilized for paramagnetic minerals (those with low magnetic susceptibility). Diamagnetic minerals, which are not affected by the magnetic field, are collected as waste material.

3.3.1. Belt-Type Magnetic Separator (Low/Medium/High Field Intensity)

The belt-type magnetic separator features a cylindrical drum magnet with various magnetic field intensities (0.15 T – 1.5 T) and a rubber belt. Sample material is fed onto the belt from a feeding hopper. Magnetic minerals are attracted to the magnetic field and collected as magnetic concentrate, while non-magnetic minerals are separated as non-magnetic waste by an adjustable separation blade at the end of the belt. The separation accuracy between magnetic and non-magnetic minerals can be controlled by adjusting the blade gap. The process is conducted dry, requiring the feed material to be dry as well. The magnet strength can be adjusted according to the material's magnetic susceptibility. The separator can handle samples with a wide particle size range, including coarse (≈10 mm) and fine (≈0.25 mm) particles.

3.3.2. Drum Magnetic Separator (Low/Medium Field Intensity)
It is used to separate minerals with different magnetic susceptibilities through dry or wet processes, utilizing drums with magnetic coils that generate various magnetic field intensities (0.1 T – 0.35 T). As the drum rotates, the feed is introduced, and magnetic minerals, which are influenced by the drum’s magnetic field, are collected as concentrate samples using a scraper blade. Non-magnetic minerals, unaffected by the magnetic field, are collected as non-magnetic waste samples from the stream under the drum. In wet processes, it is recommended that the feed be prepared in pulp form with the help of a mixer and consist of fine particles in a narrow size range (-1 mm).

3.3.3. Filter-Type Magnetic Separator (Medium/High Field Intensity)

The filter-type magnetic separator features a matrix within which the magnetic field intensity can be adjusted up to a maximum of 2 Tesla. This equipment uses filtration to separate magnetic and non-magnetic minerals. After generating the magnetic field, the sample is fed with water. Magnetic minerals adhere to the matrix inside the equipment, while non-magnetic minerals move with the water flow and are collected through the discharge pipe. Once the non-magnetic waste is collected, the magnetic field is turned off, and the magnetic concentrate adhering to the matrix is washed out through the discharge pipe. This separator operates in a wet process, requiring the feed to be in the form of a pulp, with a maximum particle size of less than 1 mm.

3.3.4. Eddy Current Magnetic Separator

An eddy current is an electric current that forms in closed-loop circuits within conductors, induced perpendicularly to a changing magnetic field according to Faraday's and Lenz's laws. In the eddy current magnetic separator used in our laboratory, an electromagnetic field is generated by an eddy current created in the coil. A rubber belt runs over this coil. The dry sample is fed onto the belt from the feed hopper. Minerals affected by the electromagnetic field are collected as magnetic concentrates, while those unaffected are separated as non-magnetic waste with the help of a scraper blade. It is recommended to use samples with a narrow particle size range for optimal results.

3.3.5. Davis Tube

The Davis tube is a laboratory device designed to separate finely ground ores with strong magnetic properties from accompanying non-magnetic gang minerals. It features an electromagnet positioned between its poles at a 45° (adjustable) angle. The electromagnet generates a magnetic field intensity of up to 0.25 Tesla. The tube moves back and forth to mix the pulp sample within it. Minerals affected by the electromagnetic field are retained in the area created by the electromagnet, while non-magnetic minerals are discharged with the water from the outlet. It is essential to use a sample with a narrow particle size range, ideally consisting of fine particles (-0.5 mm).

3.3.6. Satmagan Magnetite Detector
Satmagan is a fast, accurate, and reliable device used to measure magnetite content in samples. It performs measurements with an approximate duration of one minute and a margin of error of 0.4% or less. The principle behind Satmagan is based on measuring the force acting on the sample within a magnetic field that has a spatial gradient. The magnetic field is strong enough to saturate the magnetic component within a sample.

3.3.7. Electrostatic Separator
The electrostatic separator takes advantage of the electrical conductivity differences between various minerals in the ore feed. Its primary application is separating certain minerals found in heavy sands. Through the lifting effect, certain charged particles are attracted to an opposite-charged electrode, effectively lifting them from the separator surface to the electrode. The pinning effect, on the other hand, causes non-conductive mineral particles to retain a surface charge after receiving it from the electrode, holding them in place due to opposite-charge attraction to the separator surface. The sample feed must be completely dry and have a narrow particle size range, preferably between 0.150 mm and 0.212 mm.

3.4. Flotation Tests

Flotation tests are based on the differences in physicochemical surface properties of various mineral particles. Specific chemicals (flotation reagents: collectors, depressants, frothers, modifiers, etc.) are applied to these minerals to make their surfaces either hydrophobic or hydrophilic. Hydrophobic minerals attach to the air bubbles introduced into the flotation cell and float to the surface, where they are collected as a concentrate sample. Hydrophilic minerals, on the other hand, remain in the water and settle at the bottom of the cell, thus not floating. These minerals are collected from the pulp as waste samples. For flotation tests, the sample should be composed of fine particles (≈ d80 0.1 mm). Flotation tests can be conducted on a lab or pilot scale.

3.4.1. Mechanical Flotation Machines

Our laboratory utilizes Wemco and Denver type mechanical flotation machines. Flotation cells range in size from 0.5 L to 8 L. We also have a pilot-scale mechanical flotation machine with a compatible flotation cell of 100 L capacity.

Sulphide and/or Oxide Ore Flotation:

Ores in which sulfur (S) is bonded to minerals (such as CuFeS₂, PbS, ZnS, etc.) are referred to as sulfide ore flotation, while ores where oxygen (O) is bonded to minerals (such as Cu₂O, PbCO₃, ZnO, etc.) are known as oxide ore flotation. In our laboratory, flotation tests can be performed for both types of ore formations. The flotation of ores that contain both sulfide and oxide minerals, which is known as complex flotation, can also be carried out similarly. Flotation tests are conducted using chemicals appropriate to the structure and bonds of the minerals present in the ore.

Industrial Raw Material Flotation:

Industrial raw materials (such as feldspar, silica, bentonite, barite, bauxite, quartz, etc.) are non-metallic and non-fuel mineral resources. Flotation tests for raw materials containing impurities, which can be enriched through flotation due to surface chemistry differences, are conducted in our laboratory. Prior to the tests, necessary preparations and pre-enrichment processes are carried out to ensure that the feed has an appropriate particle size. The tests are performed using suitable chemicals and flotation cells (glass or silicon). As a result, impurities are removed as waste samples, while the desired concentrate sample is collected from the froth.carried out to ensure the feed has the proper particle size. Impurities are removed as waste while the desired concentrate is collected from the froth.

 

Coarse-Slurry-Cleaning Sequential Flotation Tests:

When designing flotation flow sheets, parameters such as the number of stages, the adequacy of reagents, and the desired tenor in the ore are considered. To achieve optimal conditions, stages for coarse, scavenging, and cleaning may be added or removed based on the data obtained from these parameters.

Single-Stage (Batch) and Continuous Flotation Tests:

Depending on the flotation flow sheet, tests can be conducted in a single-stage (batch) or continuous manner.

Closed-Circuit (Locked Cycle) Flotation Tests:

Closed-circuit tests simulate a continuous circuit using repeated single-stage (batch) tests. The basic procedure starts with a complete single-stage (batch) test. The intermediate products from this batch test are then added to the next cycle to repeat the process. Batch tests or cycles are typically continued until a steady state is reached, usually through five or more cycles. Closed-circuit tests are essential for determining the reliability of overall recovery rates and whether regrinding is necessary.

Collector Type and Quantity Determination:

Tests are conducted to determine the most suitable collector type and the optimal amount required for flotation circuits for the sample being studied.

Depressant Type and Quantity Determination:

Tests are carried out to identify the best depressant type and the appropriate amount needed for flotation circuits for the sample under investigation.

Frother Type and Quantity Determination:

Tests are performed to establish the most effective frother type and the optimal quantity for flotation circuits based on the sample being studied.

Kinetic Flotation Tests:

Tests are conducted to determine the optimal flotation times for each stage (coarse, scavenging, cleaning) and to implement flotation circuits with these optimal flotation times.

Pulp Density Determination:

Tests are performed to identify the optimal pulp density for the sample and to apply flotation circuits at this optimal pulp density.

pH Value Determination:

Tests are conducted to determine the ideal pH value for the sample and to perform flotation circuits at this optimal pH value.

3.4.2. Pneumatic Flotation Machine

MMSA (Maelgwyn Mineral Services Africa) Imhoflot Pneumatic Flotation System:

The most significant advantage of the Imhoflot system is its improved grade-recovery curve and the expanded range of mineral particle sizes (for both very fine and coarse particles). This is achieved through higher energy dissipation for bubble-particle attachment and superior froth discharge, which reduces gangue entrainment. The flotation cell design is optimized for different applications, and our laboratory is equipped with two types of flotation cells: vertical feed (V-Cell) and tangential feed (G-Cell). Additionally, the system includes a conditioning tank with a stirrer for sample conditioning. The Imhoflot flotation system operates on a pilot scale

 

3.5. Hydrometallurgy Tests

Hydrometallurgy focuses on the production of metals and compounds from minerals or other materials using chemical processes. The most popular and accepted definition of leaching is the dissolution of soluble components in a solid material using a solvent. In its most common form, leaching involves dissolving valuable minerals from an ore or concentrate using an aqueous solution (media). This process can be carried out under atmospheric or varying pressure conditions. The samples used for leaching tests need to be fine-grained (≈ d80 -0.05 mm).

3.5.1. Acid Leaching

The process of leaching using an acidic solution as the separating medium is referred to as acid leaching. Depending on the mineral bonding structure of the sample being tested, an appropriate acid solution (H2SO4, HCl, HNO3, etc.) is selected to facilitate chemical bond degradation. After the test, a suitable filtration method is applied to achieve solid/liquid separation, and the precipitated solid sample is separated from the leach solution.

3.5.2. Alkali Leaching

Alkaline leaching is recommended for ores associated with acid-consuming components, such as calcareous materials. Based on the mineral bonding structure of the sample being tested, a basic solution (Na2CO3, NH3, NaOH, etc.) that facilitates chemical bond degradation is selected for the test. After the test, a suitable filtration method is applied to achieve solid/liquid separation, and the precipitated solid sample is separated from the leach solution.3.5.3. Column Leaching

3.5.3. Cyanide Leaching
Samples taken from drill cores, run-of-mine ore, or crushed/ground ore can be used for this test. It is recommended for high-grade ores (typically ≥2-3 g/ton Au) and ores suitable for agitated tank leaching, as well as for refractory ores. The leaching duration is generally 24 hours, though it may be extended to 48 or 72 hours if needed. Throughout the leaching process, samples are collected at specific intervals (e.g., 1, 2, 4, 6, 8, and 24 hours) and analyzed for free cyanide, gold, and other metals. Based on the data obtained from these analyses, the test completion time is determined.

 

3.5.4. Bottle Roll Test

The bottle roll test is a standard initial step in the industry to evaluate the feasibility of gold recovery through cyanide leaching. The ore, which is known in tenor, crushed, and ground (≈ d80 -0.15 mm), is mixed with water in a bottle to create a pulp. The test is conducted with free cyanide, with pH adjustment, over a period of 48-96 hours in a specialized setup that provides mixing and oxygen/air supply.

3.5.5. CIL/CIP Tests
Samples can be taken from drill cores, run-of-mine ore, or crushed/ground ore. This test is recommended for ores with high grades (typically ≥2-3 g/ton Au) and ores suitable for agitated tank leaching. In the CIL test, cyanide leaching is performed using active carbon, which has been subjected to abrasion and fines removal. The CIP test is applied after the bottle-roll leaching process, where no active carbon is added. After the bottle-roll process is completed, granular activated carbon is added to the bottle, and adsorption typically lasts for 24 hours.

3.5.6. Atmospheric Leaching
Samples can be taken from drill cores, run-of-mine ore, crushed/ground ore, or flotation concentrates. This method can be applied in leaching tests conducted under atmospheric conditions (<100°C). Leaching tests are performed using appropriate acids (H2SO4, HCl, HNO3), bases (Na2CO3, NH3, NaOH), or salt solutions for acidic or alkaline leaching.

3.5.7. Pressure Leaching (HPAL)
Samples can be taken from drill cores, run-of-mine ore, crushed/ground ore, or flotation concentrates. This method can be applied to lateritic nickel, copper, zinc, cobalt, and uranium ores. Depending on the type and mineralogical properties of the ore, the acid concentration (10-50 g/L H2SO4), temperature (110-260°C), and pressure conditions (total pressure <40-50 atm) are determined, and leaching tests are conducted under optimal conditions using an autoclave.

3.5.8. Pressure Oxidation Test (POX)
Samples can be taken from drill cores, run-of-mine ore, crushed/ground ore, or flotation concentrates. Ores with high carbonate content are subjected to pre-acid leaching under atmospheric conditions, aiming to reduce the carbonate (CO32-) content of the ore to <2%. After the pre-acid treatment is completed, the pulp is transferred to the autoclave in the required volume, and the test is conducted. Pressure oxidation is typically applied at temperatures of 180-230°C and partial O2 pressures of 350-700 kPa (50-100 psi or 3.5-7 bar).

3.5.9. Diagnostic Leaching
Samples can be taken from drill cores, run-of-mine ore, or crushed/ground ore. Diagnostic leaching tests are carried out on samples ground to d80 0.038 mm with a standard cyanide leach followed by acid leaching and subsequent cyanide leaching. In diagnostic leaching tests, the mineral phases to which gold or silver are bound are selectively decomposed using different acids, allowing the liberation of gold and silver, followed by their recovery through cyanide leaching.

3.5.10. Physical Diagnostic Leaching
Samples can be taken from drill cores, run-of-mine ore, or crushed/ground ore. This test is recommended for high-grade ores (typically ≥2-3 g/ton Au) and ores suitable for agitated tank leaching, as well as refractory ores. In physical diagnostic leaching, the material is ground to different sizes in the range of 5-100 µm (typically d80 0.100, 0.075, 0.044, 0.025, and 0.005 mm), and cyanide leaching is applied.

3.5.11. Bioleaching – Biooxidation
This method is applied for the recovery of metals (bioleaching) from low-grade sulfide ores or concentrates and for the oxidation of pyritic/arsenopyritic refractory gold ores and concentrates prior to cyanide leaching (biooxidation). Samples can be taken from drill cores, run-of-mine ore, crushed/ground ore, or flotation concentrates. Bioleaching tests are conducted under column leaching conditions for low-grade ores, while temperature-controlled stirred reactors are used for high-grade materials/concentrates. Temperature-controlled stirred reactors are also used in the biooxidation of pyritic and arsenopyritic ores and concentrates.

3.5.12. Column Leaching

Leaching is performed using a column that allows water, acid, or other leach solutions to pass through the sample to dissolve impurities within it. Column leaching tests are generally among the initial tests to determine the suitability of the ore for heap leaching. The test duration can vary from 9 to 90 days, depending on the mineral structure and content.

 

3.5.13. Agglomeration Test
The fine clay minerals present in the ore and the fine materials generated during size reduction processes hinder the percolation of the solution through the heap, thereby reducing the leaching rate. The uneven percolation of the cyanide solution within the heap negatively impacts the efficiency of gold dissolution. To minimize the issues caused by fine particles and improve the leaching rate and efficiency, the agglomeration method can be applied. The purpose of agglomeration is to bind the ore using water, lime, or binders such as Portland cement, creating aggregates and producing material with a narrow size distribution. If the proportion of fine particles in the ore (d80 75 µm) is ≥10-15%, agglomeration is carried out using binders like cement and lime.

3.5.14. Weak Acid Dissociable (WAD) Cyanide Analysis
WAD cyanide analysis provides an estimate of toxicity by recovering both free cyanide and weak metal cyanide complexes. WAD cyanide includes all forms of free cyanide, as well as cyanide complexes of nickel, copper, mercury, and silver, excluding organic cyanide compounds. During the analysis, potentiometric titration is performed using a ligand exchange reagent (LER) solution as the binding reagent.

 

3.5.15. MMSA (Maelgwyn Mineral Services Africa) Aachen Reactor

Aachen technology provides high levels of oxygen mass transfer efficiently and has proven particularly successful in gold mining. The pulp is pumped from the process tank through a specially designed aeration system where oxygen is introduced at high shear and speed. The purpose of applying Aachen technology is to help realize hidden potentials for reagent savings, gold recovery, or yield improvements. The Aachen reactor is suitable for any application requiring thorough gas-liquid mixing and has been found particularly effective for gold leaching applications where increased dissolved oxygen levels are needed. It can enhance gold and silver cyanide leaching kinetics, leading to significantly higher gold recovery.

3.6. Abrasion Tests

Abrasion refers to the reduction in particle size of ores through friction between two hard surfaces (typically the mineral particles within the ore itself). It is commonly used for soft and sticky ores (phosphate, mica, kimberlite, etc.).

3.6.1. Drum Scrubbing

Involves the abrasion of a sample with a certain solid-to-water ratio in a rotating drum without any grinding media. Key parameters include test duration, pulp density, and drum rotation speed. Conducted on a lab scale.

3.6.2. Attrition Scrubbing

A sample with a specific solid-to-water ratio is placed in specialized hexagonal cells and subjected to abrasion of mineral surfaces by a special impeller during the test. Key parameters include test duration, pulp density, and impeller rotation speed. This test can be performed on both pilot and lab scales.

4. DEWATERING TESTS

Dewatering tests involve separating solids from liquids using a porous separator (filter paper) to obtain a solid sample with approximately 15-20% moisture content as filter cake. The separated liquid is collected in a separate container. For effective dewatering, the pulp sample should not have very fine particles (≈ -0.1 mm) or high clay content, as these can clog the filter paper pores.

4.1. Pressure Filtration

The filter chamber is fitted with filter paper and checked for leakage before feeding the pulp sample. After sealing the chamber lid, air is introduced through pipes, and solid-liquid separation is achieved under applied air pressure. The test result is obtained by opening the chamber lid carefully, and the filter cake is then dried in an oven.

4.2. Vacuum Filtration

A vacuum pump is connected to a flask via a tube. A porous Buchner funnel is placed on top of the flask, and a filter paper with an appropriate pore size is inserted into the funnel. The pulp sample is then added, and a solid sample with approximately 20% moisture content is obtained on the filter paper, while the liquid sample is collected in the flask. The resulting solid sample is dried in an oven.

5. PRECIPITATION TESTS

The efficiency of solid-liquid separation can be greatly improved, especially in coal preparation where sedimentation, filtration, and centrifugation are intensively used, by applying synthetic polymeric flocculants. This improvement is achieved by increasing the effective particle size of the solid phase, which aggregates dispersed particles. This destabilizes the suspension, allowing the liquid phase to be released and facilitating the precipitation of the solid phase.

5.1. Flocculant Type and Amount Determination

Tests are conducted to determine the most suitable flocculant type and the optimal amount required for the flocculant in the testing circuits, based on the sample being studied.

6. DENSITY TESTS

The density of a test sample is calculated by determining the ratio of its mass (m) to its volume (V) at a specific temperature, expressed in units such as kg/m³, kg/dm³, g/cm³, kg/L, or g/mL. This test method involves the immersion method applied to mineral ores and geological samples (core and rock) to determine the sample's density. The samples are cut to fit appropriately in the immersion container and are cleaned in liquid paraffin if necessary to ensure no residue is left behind. This method is developed for laboratory use.

6.1. Paraffin Density Tests

The weight of the test sample without paraffin is recorded using a precision scale. Paraffin is melted on a heating stove, and the entire test sample is immersed in it until all surfaces are coated. The paraffin-coated sample is then weighed on a precision scale. The sample is placed in the measurement device's precision scale cage, immersed in displacement water, and the volume measurement is taken. The weight change on the scale is noted until it stabilizes, and the density of the sample is calculated based on its mass and volume.

6.2. Paraffin-Free Density Tests

The weight of the test sample is recorded on a precision scale. The sample is placed in the measurement device's precision scale cage, immersed in displacement water, and the volume measurement is taken. The volume on the scale is noted until it stabilizes, and the density of the sample is calculated based on its mass and volume.

7. CLAY ANALYSES

Various types of analyses are available in our laboratory for clay samples containing hydrous aluminum silicate minerals. These analyses provide data on the clay content (type and amount), methylene blue index, swelling characteristics, viscosity, pH, and density values of the sample.

7.1. Methylene Blue Index Tests

The first step in this test is to prepare a methylene blue solution according to the appropriate procedure. The test sample is mixed with water at a specific solid ratio and methylene blue solution is added in controlled and incremental amounts. After each addition, a drop of the mixture is placed on filter paper for color observation. The methylene blue index is calculated based on the obtained data. The sample must meet the d100 -2 mm condition for this test. Key parameters include test duration, pulp density, and mixer speed.

7.2. Swelling Tests

Smectite group clays can expand by 30% due to drying and wetting. These clays are referred to as swelling clays. Tests are conducted in our laboratory to determine the swelling ratios of these clay samples. The test involves placing a specific amount of sample into a glass measuring cylinder, ensuring there are no air gaps by tightly packing the sample. The height of the sample in the cylinder is recorded. Another cylinder of the same size is filled with distilled water, and the sample is added very slowly. After sealing the cylinder to prevent air exchange, it is left to stand for 24 hours, and the height of the sample is measured again. The difference between the two measurements is calculated to evaluate the sample's swelling properties.

7.3. Viscosity Tests

This test aims to determine the viscosity coefficients of a sample-water mixture and calculate the viscosity energy of the test sample. The sample is placed in a special container of the viscosity measurement device. Two measurements are taken: first at low rpm (300 rpm) and then at high rpm (600 rpm). The dynamic viscosity of the test sample is calculated from the obtained data.

7.4. pH Tests

This test aims to determine the pH value of a sample-water mixture at a specific solid ratio. pH readings are taken using known pH buffer solutions. pH 2, pH 7, and pH 10 buffer solutions are used in our laboratory. The deviation in the pH value of the test sample is corrected based on the buffer solution readings.

7.5. Density Tests

This test determines the density of a sample-water mixture at a specific solid ratio. Density measurement instruments with different density values ranging from 1.50 g/cm³ to 2.00 g/cm³ and a precision of 0.06 g/cm³ are used to find the density of the pulp.

8. LASER PARTICLE SIZE ANALYSIS

   Particle size distribution analysis is performed by measuring the angular change in light intensity scattered when a laser beam passes through a particle. Ultrasonication is used to ensure that the sample is homogeneously dispersed in a liquid medium during the analysis. The concept of equivalent particle diameter is used to define the size of non-spherical particles. The equivalent particle diameter is measured by capturing the particle's projection with cameras and processing it to provide relative shape parameters such as projection contour and area. Thus, both image analysis and laser analysis can be performed for the sample being analyzed for particle size.