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Atmospheric leaching

ALS offers a full range of atmospheric acid and alkaline leaching at the Hydrometallurgical Centre of Excellence (HCE). Services covering basic simple amenability leach tests, progressing to scoping studies on master composites, right through to bankable feasibility studies encompassing comprehensive leach optimisation, process validation and variability studies.

Hydrometallurgical testwork 4

Atmospheric leaching testwork services

Atmospheric leaching covers a range of apparatus set-ups and test conditions, and given the relative ease of this form of leaching, ALS can accommodate just about any scenario, as follows:

  • Leaching using acid and alkaline lixiviants
  • Cyanidation and complexing agents including halides and thiosulphate
  • Range of agitated leach vessels
  • Temperature, pH, Eh and ORP control as required
  • Automated reagent dosing
  • Steam injection and heating (direct or indirect)
  • Vapour extraction and scrubbing systems.

An atmospheric Leach Skid (cascade circuit with up to seven stages including ferric precipitation; volume ~74 – 134 L/stage; Hastelloy agitated steel tanks; 95 to 100ºC operation) is also available for continuous processing.


In addition to the above, all the generic pre and post laboratory tasks such as feed characterisation, particle size, rheology and representative sampling, monitoring, handling and dispatch, are available.

Don't see what you need or are unsure about some of the services and associated requirements?

We understand that metallurgical testwork is not a one size fits all or a pick off a menu proposition, and so we are happy to help walk you through the process. Or you might know exactly what you want and just need some clarifications.

No problem. Please contact us for further details.

Here are some frequently asked questions

  • How much sample mass do I need for a leach program?

    Well that depends on the type of sample material, ore or concentrate and the extent of the program, but some rough guidelines are as follows:

    • Head analysis   1-2 kg
    • Atmospheric Bottle Roll Test   0.5 – 1.0 kg (depending on % solids)
    • Leaching optimisation   1 kg per test so 10-50 kg usually suffices
    • Bulk Leaching piloting   10-50 kg per hour (typically 120h run time)
    • Heap (Column) Leaching   12 kg/m (100mm Ø) 70 kg/m (2400mm Ø)
  • 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 send plant slurry samples?

    Yes, ALS can filter your plant slurry samples as required.

  • 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 bulk atmospheric leaching pilot testwork?

    Absolutely. Generally, however, piloting testwork follows a successful bench testwork program where the proposed process flowsheet has been selected. Continuous testwork will prove the viability of the selected flowsheet and confirm recycle streams and overall circuit kinetics which is not possible from only batch or bench scale tests.

  • 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.

Associated testwork services

Leach testwork rarely happens in isolation and typically many other processes are required pre and post leaching testwork, as follows: Sample Characterization, Mineralogy, rheology, solid liquid separation including flocculation and settling, impurity removal, Iron control chemistry, tailings management, materials of construction selection testwork (corrosion coupons) preliminary piloting and fully integrated piloting.


Click on the above links or contact us for further information. We can integrate a full program for you if required.