Acid Metalliferous Drainage

ABA tests are the basic, initial static tests used to determine the potential for acid generation from mine waste rock. Measurements include Acid Neutralisation Capacity (ANC), total sulphur, and sulphate sulfur.

ABA is based on calculation of acid production from sulphur content, preferably the non-sulphate sulphur (= sulphide sulphur), and the Acid Neutralisation Capacity (ANC) of the rock. A confirmation of the calculation is achieved by the Net Acid Generation (NAG) test, which is additional to ABA.

ABA testing alone often is not sufficient to provide the certainty required for mine site closure planning and waste management, therefore ABA tests are recommended as a preliminary measure of acid generating potential. Our scientists will work with you to discuss your results and provide advice for further analyses by other tools such as Sequential Leaching and/or long-term kinetic tests.

ASLP tests are used to assess the leaching potential of wastes, sediments and contaminated soils, including processed mine waste (e.g. tailings) and hence help to inform mine site closure planning and waste storage and management.

The ASLP is derived from the USEPA Method 1311-Toxicity Characteristic Leachate Procedure (TLCP). The main difference is that the ASLP method calls for the particle size of the test material to be less than 2.4 mm and it allows the use of a deionized water extraction, whereas the TLCP method allows the particle size of the test material to be up to 9.5 mm.

The ASLP method uses a 1:20 (solid : liquid) extraction of solid wastes by tumbling  for the analysis of metals and non-volatile compounds.

Reports include analysis of leachate, the pH of the fluid used and the final pH of the leachate.

Kinetic tests complement static tests by demonstrating over time the long-term leaching potential of mining waste rock material.

Basic kinetic test methods include leaching columns and humidity cells. We can offer you a tailored program of kinetic methods that mimic field scenarios and cover analysis of leachate and sample characteristics.

An alternative to Kinetic testing, ChemCentre’s sequential leaching tests have been developed to identify in just weeks rather than years, the chemical risks to the environment from potential contaminants due to the migration of metals and elements at mines into ground and surface water sources.

The new sequential leaching method predicts the order and extent of major ions, metals and metalloids that would be leached from waste rock material in non-acid environments (a process known as neutral metalliferous drainage).

Aided by a decision support tool, tests can be optimised as a screening tool for early identification of risks, saving industry and government time and money, enabling better resource allocation and waste management, and will support efficient mine closure planning.