Gravity gold recovery

Here are some frequently asked questions

• How much sample mass do I need for gravity testing?

  Gravity is one unit process that usually requires very little mass to achieve a result, as follows:

  Pre-gravity stage	1 kg plus and in batches there after
  Wilfley table	1 kg plus and in batches there after
  Half GRG test	20-30 kg
  Full GRG test	50-100 kg

• Why are benchscale gravity results often higher than industry practice?

  Centrifugal concentrators are a batch process whereby the spinning bowl will capture the high SG material in the sample feed and progressively displace according to the highest SG particles. The bowl of a Knelson KC-MD3 will typically capture 60-100 g of mass. If the feed mass is only 1 or 2 kg, this represents 3-6% of feed mass. Whereas in industrial plants, the bowl of an industrial grade centrifugal concentrate will capture 1—20 kg from hundreds or thousands of tonnes processed, which only represents a mass yield of fractions of 1%. Another important factor is that full-scale gravity circuits on a mine site are capturing liberated gold grains from a continuous closed-circuit system that is not replicable in a batch testing arrangement. However, most engineering companies will have proven plant design scaling factors for batch test results.

• Can I send plant slurry samples?

  Yes, ALS can filter your plant slurry samples as required or treat them as received.

• Does ALS do bulk gravity pilot testwork?

  Yes, but it is rarely required. ALS does not carry larger concentrator sizes in its inventory and therefore will have to hire units as required.

• Will ALS toll treat gravity gold bearing ore parcels?

  Typically, no. Our core business is testing, not production and the security and insurance requirements for this type of work are very onerous.

• Will ALS treat hazardous samples?

  Generally, yes. ALS has facilities and procedures to treat fibrous and radioactive samples. Surcharges do apply, however, to cover safety equipment, monitoring and decontamination.

• Our samples are from overseas, what do I do?

  ALS is a quarantine approved premises and treats many samples of oversea origin. Strict regulatory requirements are in needed around packaging and paperwork, however. ALS can advise you on these requirements.

• Can I do my own testwork in ALS’s laboratory?

  Generally, no. Insurance and safety protocols typically prevent renting laboratory space and this is not part of ALS’s business model. Clients are able to visit and witness testwork but this is to observe only. Typically, clients may attend on 24/7 piloting campaigns and interact with senior staff members for technical and operational issues.

• Can my associates and I view the testwork at ALS’s laboratory?

  Yes, clients are always welcome to visit our facilities and observe samples or tests in progress. Inductions are required and other rules may apply to visitors.

• Will ALS dispatch my samples to third parties?

  Yes, if a testwork program is in progress, ALS will happily dispatch testwork products and feed samples to vendors, third party laboratories, and customers as required. Fees apply.

• Does ALS do design engineering and consulting?

  No, as it is not our core business and would put us in direct competition with many of our clients. We can, however, put you in contact with a range of reputable engineering providers and consultants.