The Continuous Variable Discharge concentrator (CVD) has been successfully applied in the separation of gold sulphides. During the 1990s, Knelson batch centrifugal concentrators became a standard addition to the cyanide circuit in order to improve both costs and recoveries of free milling ores. In recent gravity separation developments, more difficult sulphide associated gold ores can be processed using the Knelson CVD concentrator. The CVD can capture both the fine free particles of gold and the gold associated sulphide particles as well.
Fig 1. The Knelson CVD can be placed within optional areas of the gold milling circuit (A, B, C, D). Specific sites may warrant a different placement as determined by mineralogy and site layout.
Benefits
Superior metallurgical performance over existing gravity plants.
Preferential removal of high value sulphide particles from the grinding circuit can reduce the overall grind requirement.
CVD will tend to remove preg-robbing components from valuable product.
Low tonnage/ high grade sulphide concentrate containing the majority of values can be treated intensively.
CVD has small footprint to facilitate retrofit into existing operations.
Low operating cost
Application
There are a number of placement options for installing a Knelson CVD within a gold milling circuit. Although the best results are often obtained with the Knelson CVD placed within the closed milling circuit, specific sites may warrant a different approach as determined by mineralogy and site layout. The four common placement options (A,B,C, and D) are shown in figure 1, along with the standard concentrate treatment circuit.
Gold bearing sulphides can be separated in a closed grinding circuit with a Knelson Continuous Variable Discharge concentrator. CVD concentrate can be fed to an intensive treatment circuit tailored to the high-grade concentrate. Intensive treatment will usually include a small milling circuit and an intensive leach (fig 1). Two examples of CVD recovery curves in gold sulphides cyclone underflow applications (position A, fig 1) are shown in figures two (2) and three (3).
Fig 2. Au recovery versus concentrate mass yield from gold sulphides cyclone underflow.
Fig 3. Au recovery, concentrate grade and feed grade versus concentrate mass yield from gold sulphides cyclone underflow.
Share Your Knelson Experience
"We used a Knelson in Caroni River, Estado Bolivar (1989-1982). The results were very important to eliminate the mercury in concentration operations to recover gold."
- Hector Marquez, Geografo - CVG Tecmin, C.A., Venezuela
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