Economic, water and energy evaluation of early rejection of gangue from copper ores using a dry sand fluidised bed separator

• A dry sand fluid bed for early rejection of gangue from copper ore reduces water and energy consumed.
• Copper loss makes the use of the DSFB uneconomical unless the reject from the DSFB is heap leached.
• Circuits including DSFB and heap leaching can increase the recovery of copper and profitability.
• The profit can be increased if the ore has copper content as a strong function of density.

The implications of adding a dry sand fluid bed (DSFB) separator for early rejection of gangue from copper ore on the economic outcomes as well as energy and water consumed have been analysed. The analysis included capital and operating costs and considered the consequence of loss of valuable copper to the tails. Two types of copper ores with different mass-density and copper-density distributions were analysed. Energy and water can be saved using the DSFB to reject gangue early but the loss of valuable copper makes the revised flow sheet uneconomical. If the low density ore rejected by the DSFB is sent to heap leaching, both reduced water and energy consumption as well as increased profit are possible for one of the ores. In order for the DSFB to be useful in increasing profit, the ore should have copper content a strong function of density (greater than linear). This type of ore is amenable to processing by DSFB and heap leaching, because a large fraction of the feed can be sent directly to heap leaching rather than being ground resulting in significant reduction in energy and water consumption with minimal loss (or even slightly improved) recovery of copper.

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