Grinding & Classification Circuits

Grinding & Classification Circuits

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Recovering Gold From Worn Out Mill Liners (2 replies)

8 months ago
Ceverett 8 months ago

In our grinding circuit, we have a SAG mill that uses rubber liners. Once the liners are worn out and replaced we sell the old liners to a company for a credit where I am guessing they either burn them or leach them in a tank to recover the gold embedded in the liners. They are shipped to South Africa to be processed so guessing there must be a pretty good amount of gold inside. We are not sure how much gold is in the liners and have always just sold them for a credit. Wondering if anyone has tried recovering the gold from their old mill liners on site and what the most effective way to do it would be and if it was economical to do so. Thanks

8 months ago
Jorge 8 months ago

In you want to determine the gold content trapped in the liners, the metallurgy department should oversee the work because some free gold or gold bearing minerals can be trapped in the space between liners. No matter if your maintenance department or a service is responsible to replace the liners, the metallurgy department should be there.

The space between liners is like a hydraulic trap and work similarly like a sluice. For example, it has been found that fine free gold (e.g. 500 um) is good for sluices. Coarser particles can be collected without any problem. Since free gold is a metal. It is ductile and malleable, grains of grains become flattened, instead of breaking in the grinding circuit. This situation is related to the grain size. In the grinding circuit is common to find flaky gold particles, some of these particles can be settled and others are extremely fine. The latter ones are usually reported in the SAG mill discharge. A similar situation can be found in a ball mill or droll mill.

It is necessary to review the liners to remove the particles. After collecting the ore, can be taken a sample to determine the gold grade. Initially can be considered a gravity equipment. The metallurgy balance will indicate the necessity of including and additional step to recover more gold. Cyanidation is an option. The mineralogy information can provide good information to select the recovery process.

Pump boxes is other place where can be found free gold and/or heavy particles. It is important to review them during maintenance.

6 months ago
AAFilipe 6 months ago

Honestly, this is not a thing that you should be worried about.

The gold content on liners won't make that difference to you, while to recover it you would have to invest in an equipment that is not part of your core business, and you would use it one, maybe two times per year.

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