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Dump or heap leaching

Heap or dump leaching

Dump and heap leaching (via irrigation and percolation of acid onto and through the material) is often the selected process option for many marginal low-grade orebodies typically for Cu, Uranium and Ni ores. This process typically presents much lower capital and operating costs, albeit at lower metal recoveries. In some cases, dumps of feed material are already pre- existing as tailings or mine waste material. In place of heaps and dumps, testing is ultimately conducted in columns of various sizes. ALS offers a full range of heap and dump leaching services covering basic scoping tests through to feasibility studies on larger scale continuous columns.

Column heap leaching

As part of the Hydrometallurgical Centre of Excellence (HCE), ALS has a dedicated fully equipped column leach facility at the Balcatta campus. Bench scale testwork initially consists of intermittent bottle roll tests and agglomeration/percolation testwork. This leads onto small scale 100 mm dia by. 1 m - 2 m high columns. If required, larger columns of 200 mm dia and 300 mm dia at both 4 or 6 m high can be assembled in a 30-column structure. This facility is complete with heating, continuous monitoring, and mass measurements to enable progressive balancing on each column during the course of the leaching time.


ALS has carried out numerous copper, nickel and uranium heap leaching programs, the findings of which have gone onto successful bankable studies. We have the expertise and developments at the cutting edge of metallurgical technology.


Note: The hydrometallurgical column leaching facility is separate to the gold cyanidation facility.

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 heap leach program?

    This depends on the sample bulk density selected (in-situ SG), typically each 1m column requires approximately 10 kg, however for larger 300mm dia columns a sample mass of 400- 500kg is required.

  • How important is agglomeration?

    This is very important to ensure well-formed strong agglomerates are maintained during the column leach. Typically, a binder with acid is used and the agglomerates allowed to cure. A Kappes percolation test is typically conducted to confirm the agglomeration process.

  • How is temperature maintained during column leaching?

    Columns can be wrapped in heating blankets, which are temperature controlled.

  • How long do columns operate for?

    This depends on the type of column leach, typically Nickel laterites and Uranium ores can operate from 12-24+ weeks, while Cu columns can be much quicker at 4-6 weeks.

  • Can columns be sampled during weekends and public holidays?

    Yes, ALS can offer a sampling regime to suit the analytical requirements for the testwork. Some additional fees cover these situations which are common during column leaching programs.

  • 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 interactions.

  • 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.

Associated testwork services

Column Leach testwork rarely happens in isolation and typically many other processes are required pre and post leaching testwork, as follows: Mineralogy, Sample Characterization, Feed blending and drying (typically air) to constant moisture, agglomeration, selection of binding reagents, reagent additions – reductants or oxidizers for ORP and pH control, Kappes percolation tests (modified constant head test), Column decommissioning and residue profile sampling.


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