Whether the driving force is increasing power charges, or unreliable power supply, it make more and more sense to reduce mine process power requirement. APT engineers have applied a number of processing advantages to come up with a simplistic circuit that utilises 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 recovery of the simple APT LOW ENERGY PROCESS (LEP) system can in some cases exceed existing conventional recovery.

The ore is crushed via a highly efficient 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. The sulphides, being coarser, are amenable to simple vat leaching.

The LOW ENERGY PROCESSING (LEP) system operates with as little as 8kwh/t as opposed to around 50kwh/t for the comparable conventional ball mill/CIP process. This means that the mine can generate its own process power economically. Being small and compact, the APT LOW ENERGY PROCESS (LEP) can be operated down the mine, with the tailings being pumped out rather than the ore being hoisted – again with huge power savings.

Where some ores are not fully amenable to the LOW ENERGY PROCESSING (LEP) system, it can nevertheless be applied to supplement the existing conventional processing by greatly reducing the grinding energy, and also recovering a portion of the gold up front.

Ores can be tested in APT’s associate Peacocke & Simpson laboratory - www.peacockesimpson.com .

Appropriate Process Technologies – taking processing to new heights

Download the APT Low Energy Process - Flow sheet - (122KB)