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Solvent extraction (SX)

Solvent extraction (SX)

Solvent extraction is a well-established technology that is used for purification and concentration of base metals in aqueous solutions (e.g. nickel, cobalt copper, uranium and zinc) The technology is robust and dependent on reagent selection to the required duty making testwork imperative for any flowsheet development. The "state of the art" Hydrometallurgical Centre of Excellence (HCE) at the ALS Balcatta campus has a world class service capability with a fully equipped solvent extraction testwork facility.

Teste de agitação de SX

Solvent extraction

ALS offers a full range of solvent extraction testwork and piloting services covering basic shake out tests, through to comprehensive scales SX circuits for definitive feasibility studies. Batch equipment includes mixers and shakeout flasks of various sizes. Our bench testwork capabilities include:

  • Determination of phase disengagement and separation times
  • Chemical and physical organic scrubbing studies
  • Evaluation of physical properties (densities and viscosities)
  • pH profiles that determine effect of pH on metal distribution
  • Effect of reagent concentration, temperature and phase continuity
  • Evaluation of maximum loading and effective organic reagent concentration
  • Determination of kinetics (extraction and stripping)

Continuous pilot equipment is extensive and flexible with three separate SX pilot plants available with up to 60 mixer settlers (i.e. a range of mixer and settler volumes). If we do not have your specific mixer/settler configurations, we will fabricate vessels to suit.


SX circuits can be constructed using various configurations of mixer/settlers for liquor feed rates from 3 to 50 L/h. Ancillary equipment includes heating, pH control and internal recycle control.


ALS has conducted batch and continuous SX tests on both the so-called 'acid' circuit (Cyanex 272 followed by DE2HPA or Versatic Acid) and the ammoniacal circuit (LIX 84I), as well as cobalt-zinc separation in refining circuits (Cyanex 272).


Call our team to discuss your SX needs.

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

We understand that SX testwork is not a standard template and needs a customised approach specific to a project. Our team will tailor a program exactly to your needs.

Please contact us for further details.

Here are some frequently asked questions

  • How are SX reagents obtained?

    Typically, reagent supply companies will freely issue organic reagents for use on clients projects.

  • Are organic reagents considered dangerous?

    Organic reagents and specifically the diluents used are highly flammable. More recent diluents have increased flashpoints to 70°C, and for this reason fire precautions and adequate ventilation are imperative during all SX testwork.

  • What is CRUD?

    CRUD is an old acronym signifying “Colorado River Unidentified Deposit” and has taken on ubiquitous industry use for all SX processing. It relates to a stable emulsion phase generated at the interface of a mixer settler. Normally caused by solids or precipitates forming in the process.

  • 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 vendors attend the ALS lab to do associated testwork?

    Yes, Vendors and SX reagent suppliers often attend during specific bench and pilot scale testwork periods to conduct offline tests.

  • 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 pilot SX testwork?

    Yes, absolutely. Continuous SX testing is one of our fortes. However, piloting testwork usually follows a successful bench testwork program where the proposed process flowsheet has been define. 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.

Related testwork

SX rarely happens in isolation and typically many other processes are inter-related, including: acid leaching, CCD, filtration, recycles, electrowinning etc. Wider processes include: sample preparation, 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.