Batch Flotation

Batch laboratory scale tests can be carried out to determine preliminary design parameters such as grind size, reagent requirements, flowsheet design and flotation retention time for the economic recovery of the valuable mineral(s).

AMML has extensive experience in the flotation of simple and complex base metal sulphide ores, gold and silver bearing ores, platinum group metals and industrial minerals.

The staff has an excellent track record for developing flotation chemical conditions and circuit designs for problematic and complex ores (eg. for sequential Cu-Pb-Zn flotation and reverse flotation).

AMML uses several techniques such as controlled potential sulphidisation (CPS) and specific collectors tailored for flotation of base metal oxide and transition ores, including precious metals.

Locked Cycle Flotation Testing

Locked cycle flotation tests can be undertaken to provide results and data of the metallurgical performance on a continuous circuit. These tests include recirculation of circuit water and intermediate mineral streams, until a steady state is achieved.

• Tests in stirred reactors and bottle rolls (up to 100 L bottles)
• Batch carbon-adsorption tests such as carbon-in-leach (CIL) and carbon-in-pulp (CIP)
• Acid leaching (eg. copper and cobalt ores)
• Uranium leaching in either acidic or alkaline conditions
• Neutralisation and precipitation tests

Column (Heap) Leaching and Agglomeration

Simulated heap leach application, typically for gold, silver, copper, nickel and cobalt ores using perspex columns in open or closed circuit.

Agglomeration tests can be carried out on ores containing a significant proportion of fine particles prior to leaching. AMML has a dedicated plastic agglomeration drum for batch agglomeration using acid, water or cyanide solutions. The requirements for agglomeration binding agents (eg. cement, lime, concentrated H₂SO₄ are determined in small agglomeration tests.

Leach column sizes range from 100-500 mm diameter and up to 5 m tall. A small scale test in a 100 mm × 2 m column nominally requires 20 kg or ore.

Tests usually include size by size assays on the feed ore and leach residues to allow calculation of metal recoveries over the different sizes of crushed rock.

Cyanide Destruction/Regeneration

Strict environmental regulations require removal of residual cyanide from tailings water. Typically this can be done using several methods. Alternatively, free cyanide can be regenerated from tailings water which can then be recycled for use in the processing plant.

Bond Closed Circuit Grindability Tests

Determining  the Bond work indexes of a sample involves tests using laboratory scale grinding circuits. A unit weight is determined by achieving maximum packing of the prepared ore sample; the unit weight is then fed into the circuit, with undersized product being replaced by fresh feed at the commencement of each cycle. The grind times for each cycle are determined by the percentage of undersize product with relation to an ideal period product (IPP). Upon obtaining a consistent IPP, the undersize product of the final cycle is sized to obtain a work index.

Bond Ball Work Index (BBWi)

The sample is staged crushed to 100% passing 3.35 mm. The crushed feed sample is subject to a grinding by a standard ball mill. The BBWi is calculated after achieving a consistent IPP of ~28%.

Bond Rod Work Index (BRWi)

The sample is staged crushed to 100% passing 12.5 mm. The crushed feed sample is subject to a grinding by a standard rod mill. The BRWi is calculated after achieving a consistent IPP of ~50%.

Our internal analytical laboratory is equipped with modern XRF instruments and fused glass bead sample preparation to eliminate matrix effects. The fused glass bead eliminates the effects of mineral particle sizes and rock/gangue matrix effects.

The process is ideal for analysing different ores, concentrates, tails, etc…, accurately, quickly and for a large range of elements. Elements that can be reliably measured include Cu, Fe, Pb, Zn, S, Sb, As, Ni, Co, Mo, Ag and Si.

With an internal XRF service, AMML can often complete the analysis of test products (eg. flotation test products) on the same day as the test was completed. Routinely, we achieve a 24 hour turnaround from undertaking the metallurgical test to providing the assays of the test products.

Appropriate standards are always run with the test products to provide Quality Assurance/Control.

AMML also uses the services of commercial analytical laboratories such as SGS, ALS and UltraTrace for specialised analysis (eg. Gold fire assay, Platinum Group Metals, LECO Sulphur, multi element scans).

Mineralogy

QEMScan, mineral liberation analysis (MLA) and optical mineral investigations on ores and test products can be performed by arrangement to confirm valuable mineral and major gangue components and to investigate liberation or locking issues.

• ISO 3310 (BS 410) certified wire mesh and perforated plated sieves
• Apertures ranging from 11μm to 75mm
• A complete range of 200 and 450mm sieves
• Wet and dry sieving

Cyclosizing

• Warman Cyclosizer
• Five hydrocyclones used to size 55 – 10μm material
• -10μm material can be retained for analysis

Laser Sizing

• Allows for a quick and accurate particle size analysis
• Instrument measurement range: 0.01 – 600μm
• Can size directly from wet slurries

Static thickening/clarification settling tests on concentrates and tailing samples to establish settling characteristics and thickener settling area requirements.

• Initially small scale tests are conducted to evaluate different flocculants and coagulants as well as other chemical conditions
• Settling tests are then undertaken in glass cylinders of 1000/2000 mL volumes
• Settling profiles are measured over the settling time and final underflow density is measured
• Data is used to determine thickener unit area

Vacuum Leaf Filtration Tests

Tests can be conducted to determine the optimal filter type and to estimate the filtration rate and cake moisture that can be expected on a plant vacuum filter.

Co-Operation with Equipment Suppliers

As many equipment suppliers have specialised testing equipment for their specialty thickeners and filters, AMML can provide assistance for their companies by providing our laboratory facilities for suppliers to use their equipment.

A 3 inch batch concentrator (model number: KC-MD3), typically useful for recovering fine liberated precious metals at a laboratory scale.

Wilfley Table

A 1:4 lab scale unit with decks for fine and coarse separations of heavy valuable minerals.

Gold Panning and Amalgamation

Gravity concentrates can be further upgraded by hand panning. Free gold within the gravity concentrates can also be recovered by amalgamation with mercury.

Amalgamation is used in the laboratory as a method of indication the free gold content of ores and gravity concentrates. Free gold is dissolved by mercury and the mercury is subsequently analysed for gold by fire assay.

• Using Lithium Sodium Tungstate (LST)
• For static laboratory scale separations up to a specific gravity of 2.90 at ambient temperature.
• Non toxic
• Water soluble

Batch Heavy Media Separation Unit

• 60 litre capacity
• Ferrosilicon dense media
  • Non-toxic
  • Water-ferrosilicon mix

The Davis Tube bench separator performs wet separations based on magnetic susceptibility and can be used to provide a quantitative measure of the content of ferromagnetic minerals in samples.

The magnetic field strength is adjustable allowing minerals of different magnetic susceptibilities to be recovered selectively. The Davis Tube is designed to allow very clean separations of minerals. This is achieved by holding the magnetic material in the magnetic field and continuously washing the non magnetics away.