Article outlining the advantages of the Albion Process from Asia Miner January-March 2010.
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Simple refractory leaching technology
XSTRATA Technology provides a range of technologies that simplify the process of oxidation of refractory sulphide minerals.
They include the IsaMill ultrafine grinding system, a new oxygen gas sparging system, modular slurry leaching and storage tanks, and the AlbionProcess.
The Albion Process is a robust leaching process used to treat concentrates produced from refractory base and precious metal ores. The processutilizes a simple flowsheet based on hot-oxidative leaching of finely ground concentrates at atmospheric pressure, which eliminates the complexityinvolved with using autoclaves or bacterial cultures. Refractory ore as well as ‘dirty’ concentrates can be treated enabling high metal recovery at much lower costs.
The process uses Xstrata Technology’s IsaMill to grind refractory ore or concentrate to ultrafine sizes to increase the activity of the sulphide concentrates to a point where they can be oxidized readily in conventional open tanks. Oxidation is carried out without need for high pressure, expensive reagents or bacteria, resulting in a simple, robust process offering substantial operating and capital cost savings over bacterial or pressure leaching.
A big advantage is that all byproducts produced in the process can be disposed of as chemically inert residues, ensuring the mine site can berehabilitated at the end of operations without any risk of leaching of contaminants from tailings.
Two projects using Albion Process are Envirogold’s Las Lagunas tailings treatment project in the Dominican Republic and European Goldfields’Certej project in Romania.
The IsaMill technology provides a number of advantages. It produces a narrow particle discharge sizing, which reduces wasted energy used in over grinding particles, as well as reducing recovery loss to oversized particles. The high energy efficiency of the process, as well as the inert nature ofthe ceramic grinding media, ensures maximum metal recovery for lowest energy input.
lsaMilling the feed to the process introduces a high degree of strain into the mineral lattice, which imparts fractures in the grain boundary and latticedefects in the minerals. These lead to mineral ‘activation’, allowing leaching under less aggressive conditions.
Xstrata Technology has recently developed two new products, each a significant advance over existing technologies. The first is a gas sparger that utilizes a revolutionary design to increase oxygen transfer rates up to five times relative to existing sparging systems. The gas sparger also includes an intrinsically safe design that allows live removal of the spargers for inspection in a safe and reliable manner.
The second is a fully modular slurry tank. Slurry storage and leaching tanks can be provided in modular format with all parts transported to site in shipping containers. The tanks are erected using a revolutionary panel joining system that eliminates site welding. This reduces tank construction times by more than 60% and can reduce tank costs by 35-40%. Tanks sizes range from 20 to 2000 cubic metres.
