Bauxite grinding aids-development of test method and evaluation of various chemicals

摘要

Bauxite grinding is one of the power-intensive unit operations in a Bayer alumina refinery.With deterioration of bauxite quality with respect to decreasing tri-hydrate content and simultaneous increase in mono-hydrate content, which results in increasing bond work index of the ore, the grinding section is becoming a major bottleneck area for the refineries to achieve the rated production capacity.Various chemicals are claimed to have been developed as grinding aids to overcome these issues.Before these chemicals are tried out in the refinery on a full scale, it is always advisable to evaluate the same under standardized laboratory conditions.It is therefore essential that a standard method is developed for grinding so that the performance of the chemicals can be evaluated with confidence.This paper presents an attempt to develop such a standard test method and also the preliminary results of various chemicals as grinding aids.Based on the results, plant scale trials have been recommended with the short-listed chemicals in one of the alumina refineries of Hindalco.