Froth flotation: preparation of a laboratory standard

In evaluating the separation of coal from slurries of fine solids by froth flotation, it is necessary to work to a standard method to ensure that the procedure, on the same sample, can be repeated by others and the same results obtained. In a number of countries the standard procedure is produced and distributed by the International Standards Organisation (ISO) working through its member countries. In the preparation of a froth flotation standard, two different techniques from two countries (Australia and Great Britain) have been proposed. These procedures, known as the 'tree' and 'release' analyses respectively, differ in the laboratory technique and presentation of results. In order to assist in the debate of which of the procedures should be adopted as the basis for the International Standard, a short programme of comparative work was undertaken to evaluate the different methods. Samples of coal slurries from Australia, Great Britain and South Africa were evaluated using the Australian and British procedures. The work undertaken is described detailing the preparation of the samples, test procedures and differences between the two techniques. The results showed that the two techniques produced similar results with the 'Release Analysis' giving more detail at the cleaner (low ash) end of the curve and the 'Tree Analysis' more data for the middle (medium ash-higher yield) part of the curve. The results indicated that the technique chosen would be dependent upon the information required from the flotation analysis, i.e, the British 'Release Analysis' for the cleaner coal data and the Australian 'Tree Analysis' for higher ash fractions. (C) 1999 Elsevier Science Ltd. All rights reserved.