Appropriate Process Technologies (APT) says it has developed a simple circuit that utilizes batch and continuous Knelson concentrators to capture both elemental liberated gold as well as sulphide carriers. Although the emphasis is upon economics rather than ultimate percentage recovery, the company states that recovery of the simple APT Low Energy Process (LEP) system can, in some cases, exceed existing conventional recovery. According to APT, ore is crushed via an impact mill rather than a ball mill, and although the general particle size is much coarser, the initial degree of gold and sulphide liberation is surprisingly high, probably due to fracture on grain boundaries. This early liberation can account for the vast majority of the contained value on some ores, but a small secondary mill is included to further reduce the coarse and dense portion in the primary tailings. The elemental gold is recovered gravimetrically directly to the gold bar. Sulphides, being coarser, are amenable to simple vat leaching. The LEP system operates with as little as 8 kW/mt as opposed to around 50 kW/mt for a comparable conventional ball mill/CIP process.

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