ALUMINA MARKET:

Additional Web-based Resources for AMIRA P266E Project Sponsors
The resources available to sponsors of the AMIRA P266E “Improving Thickener Technology” project through the project’s website grew during the past year, with the addition of a population balance (PB) model for pipe flocculation and an enhanced CCD (counter-current decantation) circuit model. The PB model tracks the number and size of aggregates as they form or rupture during pipe flocculation, and allows comparison of different flocculation conditions.

Modelling How Bauxite Residue Turns to Dust
A good phenomenological model for the formation of dust from bauxite residue, a waste material generated by the Bayer process, was developed by the “Bayer Environmental Issues” project team. The model explains the stages observed in dust creation as bauxite residue dries. This model could provide insights that lead to decreased dust formation in bauxite residue storage areas.

Simulating a Bauxite Residue Disposal Area in a Greenhouse
A greenhouse has been used to mimic residue drying and dust creation in actual bauxite residue disposal areas (BRDA), with the simulation producing an excellent replication of observed BRDA behaviour. This simulation provides a reliable method for testing possible strategies to mitigate dust formation before committing resources to large-scale and costly BRDA trials. Several dust mitigation treatments were tested using the greenhouse system, with two treatments shown to be able to reduce the yields of airborne dust from residue.

BASE METALS MARKET:

Successful Pilot Test of Direct Solvent Extraction System by Mining Company
Direct solvent extraction (DSX) involves the application of solvent extraction to separate the target metal ions directly from a leach solution. A DSX system developed by the Parker Centre’s Solvent Extraction Technology team for selective recovery of cobalt and zinc was used in a phase 2 pilot plant campaign by Canadian company the Baja Mining Corporation to achieve over 99% recovery of both zinc and cobalt from the feed solution.

Understanding of Chalcopyrite Heap Bioleaching Advanced
Understanding of the conditions required to process chalcopyrite (copper iron sulfide) via heap bioleaching was enhanced by Parker Centre research which informed a comprehensive heap leach model developed by University of British Columbia researchers and provided insights into the “operating window” for chalcopyrite bioleaching. This understanding may assist the copper industry to improve copper recovery from chalcopyrite heap bioleaching.

Methods Being Developed to Quantify Minerals in Laterite Ores
The development of quantitative X-ray diffraction methods to determine the concentrations of minerals in laterite ores, including difficult clay minerals in particular, was significantly advanced. Methods enabling quantitative mineralogical characterisation of laterite ores will be useful in generating knowledge that could assist industry with improving process efficiency and nickel/cobalt extraction in pressure acid leaching of laterites. This knowledge includes an understanding of nickel and cobalt losses during laterite leaching in terms of leach feed mineralogy.

GOLD MARKET:

Model Predicts Reduced Costs & Environmental Benefits will Flow from Water Changes
A predictive water chemistry/water balance model of a gold processing circuit was constructed to emulate the complex chemistry occurring in gold circuits. The model has also been used to assess the economic and environmental impacts of different water management strategies. This meant various scenarios could be assessed without having to change anything in the plant. The modelling demonstrated that in some situations it is possible to re-configure the water circuit to reduce environmental discharges (weak acid dissociable (WAD) cyanide) and save money in reagents at the same time.

New Stripping Method to Get Gold-thiosulfate Off Resins
A new additive has been identified that significantly improves the efficacy of anion elution of gold thiosulfate from resins. The additive is so effective that even chloride can now be used to elute gold from resin. This is another step taken by the Parker Centre to make the thiosulfate process for the recovery of gold viable. Past work has shown that thiosulfate is likely to be a better option than cyanide for leaching gold in some cases. This new work makes the recovery of the gold onto and from a resin much simpler and avoids the problems of eluent build-up in the circuit.

Better Carbon Management for Reduced Solution Gold Losses
Gold losses from processing circuits into the tailings can result from fouling of the activated carbon used to adsorb the leached gold from solution. Contamination of the carbon by foulants such as copper (an inorganic foulant) reduces the carbon’s ability to recover gold, affecting the economic bottom line. The rate of adsorption of copper onto carbon, and the impact of this copper loading on gold adsorption to the carbon, was determined and incorporated into the water chemistry/water balance model of a gold processing circuit. This expanded model assisted in the design of a new leaching circuit for a copper-gold ore.

Using Multi-option Flowsheets to Optimise Circuit Design for New Gold Ores
The Parker Centre is building a capability in developing multi-option process models that include variables such as metal recovery, capital & processing costs and environmental impact in modelling the optimum configuration for a processing circuit for a particular ore. A complex flowsheet incorporating multiple gold processing options (including flotation, ultrafine grinding, leaching and roasting), and which also has an optimisation framework wrapped around the flowsheet, has been constructed. Different processing scenarios can now be analysed to determine the circuit design that will give the best economic and environmental outcomes when processing a new ore.

Modelling Total Cyanide In and Total Cyanide Out in Gold Processing Assists Industry
A new total cyanide balance model has been constructed, enabling the deportment of cyanide in gold mines to be mapped. The model simulates cyanide additions and losses within, and from, a gold processing circuit to assist mine sites meet their cyanide reporting obligations. Some gold operations are using the model in environmental management of cyanide and process optimisation.