Development of Prediction Methods for ARD Assessment of Coal Process Wastes

摘要

Standard test methods for predicting acid rock drainage (ARD) potential of coal rejects andtailings are unreliable due to interferences associated with organic matter and mineralogycommon in these types of materials. A research project was carried out supported by theAustralian Coal Association Research Program (ACARP) to develop a set of tests for morereliably predicting the ARD potential of coal washery wastes. The project involved three maincomponents: ·Sulphur speciation test evaluation and development; ·Modified net acid generation (NAG) test development; and ·Geochemical characterisation and kinetic testing of coal and coal washery samples from avariety of coal operations and projects. Modified NAG and sulphur speciation test development work involved specialised tests andinvestigations on standard compounds and materials to develop test methodology, followed byvalidation and refinement using case study coal and washery waste samples. Geochemical characterisation was carried out on a case study set of 125 samples to better definethe geochemical variability of coal washery wastes, and provide a sample set to validate testdevelopment work. The case study set was made up of coal, rejects and tailings from a range oflocations, with varying geochemical properties and coal rank. The research outcomes improve the application, methodology and reliability of assessing theARD potential of coal washery waste materials. An overall test methodology is recommendedfor carbonaceous materials, comprising standard ARD characterisation testing (pH and electricalconductivity of water extracts, acid base analysis and single additional NAG) with the additionof the sulphur speciation, extended boil NAG and calculated NAG test methods developed.