Metallurgical testing
Metallurgical testing
Our span of capabilities in metallurgical testing both at bench and pilot scales encompass but are not limited to:
- Froth flotation (of sulphides and non-sulphides),
- Gold recovery test work by Gravity concentration and cyanidation,
- Physical separation (HMS/DMS, Gravity concentration (Shaking tables and spirals), jigging, magnetic separation, Screening etc.),
- Comminution test work (Bond Ball Work index, Bond Abrasion index and
- Bond Crushing Work index,
- Beneficiation of industrial minerals,
- Process plant commissioning and
- Hydrometallurgy – Leaching of oxides and base metals,
Froth Flotation of sulphides
Suntech prides itself for having extensive knowledge in sulphide flotation of PGMs, Base metals as well as Gold & Silver from ores of varying mineralogy i.e., clean & fresh, tarnished as well as partially oxidised. The laboratory has earned the reputation as the preferred centre for flotation test work for reagent scouting, circuit flowsheet development and metallurgical projections.
Froth Flotation of non-sulphides
Over the years, Suntech Geomet has acquired extensive knowledge and experience in the flotation of non-sulphide minerals successfully developing conditions suitable for recovery of Graphite, Calcium fluoride (CaF2), Cassetirite (Sn), Chromite (Cr2O3), TREO (Total Rare Earths Oxide minerals) & Apatite among others. A significant milestone was achieved when the laboratory successfully developed suitable reagents suites and conditions for separating CaF2 from apatite and upgrading apatite from carbonatite ores. The laboratory has also successfully depressed As and Fe oxides during flotation of CaF2 producing a premium concentrate with a As levels below 4ppm and Fe levels below 0.4%. Thus, the laboratory has gained recognition as the centre for excellence in non-sulphide flotation testing.
Froth Flotation of tarnished minerals
The laboratory has a successful track record of successfully developing conditions for recovery of the following difficult categories of minerals:
- Tarnished sulphides and/or minerals,
- Slow floating minerals,
- Au/PGM tellurides and alloys and
- Carbon contaminated PGMs concentrate.
Gold recovery test work
The laboratory is set up to run various gold recovery tests meant to guide and equip gold miners with information necessary to make informed investment decisions and trouble shoot as well as improving metallurgical performance of existing metallurgical processes. The tests that the laboratory is capable of undertaking comprise:
- Diagnostic leach tests – These tests are done to infer the deportment of gold within the mineral constituencies making up the sample,
- Bottle roll cyanidation tests – Carried out to quantify amount of leachable/recoverable gold by direct and/or enhanced cyanidation /process.
- Preg-robbing tests – These tests are done to infer the presence mineral species or ore constituents capable of adsorbing gold and to quantify the amount of gold robbed per respective leaching process.
- GRG and EGRG tests – Carried out to quantify the amount of gold in a sample recoverable by gravity means. Suntech has capacity to carry out the tests on both batch and continuous setups.
- Recovery of non-free milling gold – These tests are carried out to develop processes for the recovery refractory gold / gold occluded in sulphides.
Hydrometallurgy
The laboratory harbours capabilities in hydrometallurgical testing with unparalleled expertise in the following:
- Electrolysis
- Cementation
- Leaching of oxides, base metals etc
Physical separation
Suntech has acquired vast experience in running test work for beneficiating minerals by physical means using appropriate equipment and/or techniques. The laboratory is properly set up to offer testing in the following:
- Spirals
- Jigging
- Shaking tables
- Magnetic separation
Cartox
Recently, the laboratory successfully developed a method for sulphide matrix destruction that enables gold recovery occluded within the pyretic and arsenopyretic sulphide complex. The method uses certain acids to destroy the sulphide matrix and regenerating ~95% of the leachant in the process. The sulphide matrix destruction process is done in less than 3 hours and guarantees gold exposures exceeding 97%.
Gravity Separation
Suntech has over the years developed methods and techniques to counteract the effect of Van Der Waals and electrostatic forces and hence developed sustainable methods to achieve clean separations. Gravity separation techniques are used to separate minerals of different relative densities; the dominant competing force in gravity separation is usually a fluid drag force while Van Der Waals and electrostatic forces have a tendency to stick particles together preventing separation. Equipped with this knowledge, Suntech has over the years developed methods and techniques to counteract the effect of these forces and hence developed sustainable methods to achieve clean separations. The beneficiation of chromite and iron ore using gravity and magnetic separation and vermiculite upgrading by dry separation techniques, have become important activities.
Shaking Tables
To date Suntech has carried out Gravity separation processes using Shaking tables on gold, chromite, tantalite, heavy minerals, ferrous and non-ferrous ores as well as PGM-bearing (to a lesser extent and only when it’s UG2 ores). The grade- recovery profile obtained on the shaking table is used as a benchmark for modelling performance of a spiral circuit. Other gravity separation techniques we implement are Falcon Centrifugal Concentrators and Spirals.
Comminution
The laboratory has expertise and resources to provide various types of the three basic comminution tests vis a viz:
- Bond Ball Work Index (BBWi):
- Bond Abrasion Work Index (BAWi) and
- Bond Crushability Work Index (BCWi)
Magnetic & Electrostatic Separation:
Low Intensity Magnetic Separators (LIMS)
We implement LIMS units (~700 to ~3000 Gauss) for laboratory scale operations to recover ferromagnetic minerals such as magnetite or pyrrhotite from paramagnetic and non-magnetic minerals.
Wet High Intensity Magnetic Separator (WHIMS)
At Suntech WHIMS is done using an Eriez magnetic separator ~11000G. The WHIMS is suited for particles less than -1mm and is capable of separating material with paramagnetic properties from non-magnetic material. The main application fields of WHIMS are recovery of ilmenite, hematite, rutile, and manganese products as well as removal of Fe contaminates from fluorspar and other industrial minerals.
Typical ores treated by HLS include chromite and base metal ores, kimberlites, PGM ores & hematite. Gold recovery test work (Cyanidation, Gravity concentration, Flotation etc.)
HLS or DMS utilises the differences in particle density to concentrate material into various density classes. Separation is facilitated by a heavy liquid medium with an unstable suspension of TetraBromoEthane (TBE) and atomised ferrosilicon used as the medium for densities greater than 2.96g/cm3; this method is time-dependant hence only particles coarser than 1mm can be treated. For densities less than 2.96g/cm3, a mixture of TBE and acetone is used. Density classes with intervals of 0.05g/cm3 can be fractionated with the data being used to construct washability grade-recovery curves. Typical ores treated by HLS include chromite and base metal ores, kimberlites, PGM ores & hematite.