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Take advantage of this increasing rare service to determine gravity response. Check out our FAQ's below or by all means contact us for further details.


Heavy liquid separation (HLS)

Characterising response to gravity

Heavy Liquid Separation (HLS) tests provide key data for exploration programs and process design. Most commonly, data derived from HLS tests are used for: Characterising the density parameters of ore samples, predicting the performance of ores through gravity circuits, and/or pre-concentrating low-grade high-density minerals prior to further physical or analytical testing. At ALS, our dedicated HLS testing team work closely with clients to design tailored testwork program to meet any HLS requirement.

Rare capability

ALS uses Clerici's Solution (also known as Thallium Malonate Formate, TMF), which can separate samples into a wide range of specific gravity (SG) intervals from 1.00 all the way through to 4.35 (4.50 with modified samples and solution). Many jurisdictions have discontinued the production and use of Clerici's Solution and now use substitute liquids that cannot achieve the same density range. ALS staff are highly trained in the use of these hazardous, heavy liquids via rigorous HSE and QC procedures in order to educate, monitor, and protect our employees. Clients can still be confident that their ESG targets are being met while reaping the benefits of a superior testing regime.

Choose from a Wide Range of Heavy Liquid Densities

HLS testing can separate samples at a single density, resulting in a pair of sink-float products or into a range of density intervals with a minimum density increment as small as 0.1. Static separations are performed on coarser-grained fractions (greater than 0.5 mm) and for size fractions less than 0.5 mm, separations are usually performed in a centrifuge. This method is effective down to particle sizes as fine as 45μm and, with modifications, reasonable separation can be achieved on fractions as fine as 10μm.

The resulting size fractions are then weighed and assayed. Calculated weight and element distribution data can then be used to indicate optimum density cut points or product weight splits to achieve the desired results in terms of grade and/or recovery. Once produced, the density fractions can be submitted for analysis at our in-house analytical and mineralogical laboratories.

ALS are able to provide testwork data on samples across a range of commodities including:

  • Iron Ores
  • Mineral Sands
  • Base Metals
  • Precious metals including Gold and PGMs
  • Uranium
  • Industrial Minerals

List of heavy liquids available for use together with SGs are tabulated below.


Name Density in kg·dm−3
Lithium Polytungstate (LST) 2.920
1,1,2,2-Tetrabromoethane (Muthmanns solution, TBE) 2.967
Sodium polytungstate 3.100
Diiodomethane (Methylene Iodide, MI) 3.325
Thallium formate + Thallium malonate (Clerici's solution) 4.35-4.50

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