Most gold projects fall into the free milling category, whereby the ore is milled to liberate the gold prior to leaching and recovery processes. Free milling process work includes the evaluation and optimisation of all relevant process parameters that influence the CAPEX and OPEX for a gold project. ALS Metallurgy, in Perth Western Australia, has conducted thousands of free milling gold projects and no other laboratory group can offer this sort of experience to meet your needs.
Overwhelmingly, most gold projects centre around extraction via cyanidation and gold recovery via either carbon in pulp (CIP) or carbon in leach (CIL). The journey of process development usually starts small with a few tests on a blended composite to ascertain general amenability of the ore to these processes. Typically, thereafter, scopes of work expand to much larger programs to encompass wide ranging testing on various ore types and mine domains and leading to comprehensive variability testing once key processing parameters have been established.
After sample preparation, the general order of free milling gold evaluation is as follows:
It doesn’t stop there when your ores are not directly suited to standard processes. This might be due to gold that is finely disseminated in pyrite and requires prior flotation and ultra-fine grinding prior to cyanidation. Ores containing soluble copper can have very high cyanide consumption. Ammoniacal cyanidation can dramatically reduce the overall level of cyanide consumption and we can carry out leach tests to optimise reagent conditions. Ores rich in silver may be better suited to gold recovery from solution via the Merrill-Crowe zinc cementation method. Whatever the requirement, our expertise covers all aspects of processing non-standard ores, from flotation to selective leaching, CIP, elution and fully integrated electrowinning circuits.
This will depend on the number of tests required and the outcome of those tests, but at typically 1 kg per test, a parcel of 100 kg should be sufficient for a standard program. Keep in mind, though, requirements for preliminary comminution testing, and if significant gravity and/or flotation testing is required, that perhaps 200-300 kg for ore type may be more appropriate.
Bottle rolls are a cheaper method for leaching and CIP/CIL testing that can be done very efficiently in large batches. In many instances bottle rolls can suffice for most of the program. The main shortcoming of the bottle roll is that whilst on the rolls, the test is a closed system. The main advantage an open topped agitated vessel test is that the slurry is always accessible, and thus enables constant air or oxygen sparging through the duration of the test.
Yes, of course. Large or small, we cater for all customer requirements.
Yes, no problem.
Yes, ALS can filter your plant slurry samples as required or treat them as received.
Yes, this is a very common service and extends to all plant 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.
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.
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.
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.
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.
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.
Gold ores and the associated free milling metallurgical testwork results very often don’t fit into nice categories and packages and will often require other testwork, such as:
Click on the above links or contact us for further information. We can integrate a full program for you if required.