ALUMINA MARKET:

Stand-Alone Gibbsite Precipitation Model Built to Meet Industry Interest
Gibbsite (alumina trihydrate) precipitation is of enormous importance in the production of alumina by the Bayer process. Stand-alone software for modelling gibbsite precipitation was developed to enable the alumina industry to simulate continuous well-mixed gibbsite precipitators. This model incorporates advanced gibbsite precipitation kinetic (rate) models generated through the Parker Centre's precipitation research. The gibbsite simulation software has already been delivered to an industrial client, and should further facilitate improved optimisation and control of gibbsite precipitation.

Latest Successful AMIRA P266 “Improving Thickener Technology” Project Concludes, With Strong Industry Support for a P266F Project
The three-year AMIRA P266E “Improving Thickener Technology” project, which had 20 industry sponsors and funding of A$3.38 million, was completed in May 2008. P266E was the sixth in the P266 series of large, long-running collaborative projects which has researched gravity thickeners, used for solid-liquid separation in the minerals industry. P266E delivered numerous valuable outcomes to its sponsors through its core research as well as the one-to-one projects undertaken to address company-specific thickener issues. A recent example from the core program is a novel thickener feedwell design, predicted by computer modelling to offer superior performance to that of standard designs. This prediction has been validated at pilot-scale thus far.

New Research Capability Helping to Bring Full Thickener Modelling for Industry in Sight
The AMIRA P266E project concluded with the mathematical framework for the world's first computer simulation of an entire thickener in place, linking the sub-models developed for the various thickening stages. While the feedwell and raking sub-models have been formulated, further work is required on the sedimentation model to include the impact of shear on aggregate structures. A new instrument has been developed for characterising permeability within a laboratory column as a flocculated slurry settles to form a sediment bed. This instrument is contributing essential data needed for the development of an advanced sedimentation model, which will be the first to be fully predictive (ie provide predictions on the basis of initial flocculation conditions).

Benefits Should Flow to Industry From Raking Research
A slowly rotating rake at the base of a thickener performs several crucial tasks, including moving settled solids (aggregates) towards the tank's central discharge (underflow) point. Recent research promises to help improve thickener performance related to raking. The research has included computational fluid dynamics (CFD) modelling of thickener rakes in action, which has produced the first estimates of shear rate distributions generated within the sediment bed due to rake action. Parallel studies in collaboration with the University of Melbourne are investigating whether such shear causes aggregates to break or become denser. Such information is needed for sedimentation model development.

Scientific Successes Land Two Prestigious New Projects to Develop Promising Technologies for Industry Application
The Asia-Pacific Partnership (APP) on Clean Development and Climate (between Australia, China, India, Korea, Japan and the US ) aims to develop and deploy cleaner, more efficient technologies. The Australian Government's initial investment is A$60 million across 44 projects involving industry, Australian researchers and researchers from other AP6 countries. On the back of the research outputs of two of its Alumina Market projects, the Parker Centre successfully bid for the two largest of the six projects in the “Aluminium” target sector:

• a A$0.6 million project focused on developing technically and economically sound technologies and practices for the management of bauxite residue (red mud), a by-product of alumina production from bauxite ores
• a A$1 million project aimed at industry implementation of new environmentally friendly and economically viable technologies for processing low-grade (high silica) bauxites.

BASE METALS MARKET:

Two Solvent Extraction (SX) Projects Join Forces to Deliver New “Ready-to-Go” SX Systems to Industry
Synergistic solvent extraction (SSX) systems use a combination of two commercially available extractants to improve metal selectivity and thus metal separation and recovery in solvent extraction (liquid to liquid extraction). The SX Technology project and the SX Chemistry project have worked together to ensure that the potential of novel SSX systems for commercial applications is being realised. The former has developed and tailored SSX systems to meet specific industry needs – for Baja Mining's El Boleo deposit and for another client's nickel laterite leach solutions – and the latter's work on reagent stability in these systems under client conditions has been critical in gaining client acceptance of the new technology.

Laterite Research Assists Industry by Investigating the Link Between Mineralogy and Leaching Performance With a Range of Different Technologies
The Base Metals Market increased its focus on evaluating, optimising and developing a variey of leaching technologies for hydrometallurgical processing of nickel laterite ores. Processing of the world's huge reserves of nickel laterites is becoming increasingly important as the global reserves of nickel sulfides decline: about 60% of the land-based nickel resources are in laterites and 40% are in sulfide deposits. The research has attracted greater industry interest (driven by increasing demand and high prices for nickel), especially from Minara Resources, Vale and Zinifex, with repeat business an indicator of the value of this research to industry. The research aims to increase nickel recovery rates for existing laterite deposits and enable economically viable processing of deposits currently considered too marginal to exploit.

Microbiology Meets Metallurgy in Work to Improve Bioleaching
The combined efforts of the Parker Centre's biohydrometallurgy research groups at CSIRO Minerals, Curtin University and Murdoch University saw valuable progress made towards the goal of more efficient bioleaching of sulfide ores. Their advances included:

• a salt-tolerant microbial culture (comprising a mixture of species) that effectively catalyses biooxidation of a nickel sulfide (with >90% of the nickel liberated) in hypersaline conditions. This culture has considerable potential value for operations where the process water is highly saline. The culture is now being tested on a pilot-scale bioleach heap.
• investigation of the microbial population, and the population dynamics, within bioleaching columns using a combination of modern molecular (DNA) methods for monitoring microbial species in leach solutions and leached residues. These microbial tracking methods could one day assist with managing the right mix of microbes in a bioleach heap.

GOLD MARKET:

Novel Elution Technology Coupled With Adsorption and Electrowinning for Efficient Gold Recovery From Thiosulfate Leach Solutions
Further development of a novel elution process for recovering gold thiosulfate from resins has demonstrated that when combined with a continuous adsorption circuit (with recycling of both resin and eluent) and gold recovery from the eluent by electrowinning, the process can be optimised. This is significant step taken by the Parker Centre to make the thiosulfate process for gold recovery viable for niche applications. A full patent has been granted for the new elution process.

Simulation of In Situ Leaching Advancing Process Development
Development of a process for in situ gold leaching (ISL) would enable currently uneconomic underground gold resources to be recovered without having to mine the gold. A thiosulfate leaching system is considered the best candidate for an in situ process, in which a thiosulfate solution would be pumped underground to leach paleochannel gold deposits (surrounded by impermeable rock so that the solution does not escape), and then returned to the surface to recover the gold. The first large-scale physical laboratory simulation of in situ leaching, involving anaerobic thiosulfate leaching studies on a column containing a paleochannel gold ore, is providing an essential first step in developing a thiosulfate in situ leaching process.

New Procedure Opens a Door to Future On-Site Preg-Robbing Assessment
A procedure that improves the prediction of the preg-robbing potential of gold ores has been developed. Preg-robbing is the loss of gold during the leaching of carbonaceous gold ores via the re-adsorption of dissolved gold cyanide onto carbonaceous ore components. This robbing of gold from the gold cyanide solution (that would otherwise be recovered by adsorption onto activated carbon) can be a significant cause of low gold recovery. The new predictive tool could potentially be adapted for use on site at gold mines to monitor the preg-robbing characteristics of gold ores as they are mined. Processing could then be appropriately modified, for example by blending different ores or choosing the best treatment option to maximise gold recovery for a particular ore mineralogy.

Shine Still on AMIRA P420 Gold Project Series as P420C Ends But P420D in Development
The AMIRA P420 “Gold Processing Technology” series of projects recently completed 14 years of successful collaborative research for the gold industry with the conclusion of the fourth project in the series, the P420C project. Highlights of the last year of P420C, a three-year, A$1.91 million project sponsored by 13 companies, included:

• the release of an improved version of the total cyanide balance model to sponsors. The model simulates cyanide additions and losses within, and from, a gold processing circuit to assist mine sites meet their cyanide reporting obligations. The model can also be used in environmental management of cyanide and process optimisation.
• the addition of a new high silver gold ore option (developed through P420C and a CRC-funded project) to the SIMCIL leaching/adsorption computer model. This option is being used to model leaching/adsorption for high silver-containing gold ores for industry.