Laurie Woollacott

The combined influence of oxygen and cyanide on adsorption isotherms in carbon-based gold extraction systems

Abstract In carbon-based gold extraction plants the operating conditions are frequently such that the concentrations of cyanide and oxygen in the gold-bearing solution vary both with time and through the adsorption circuit. To estimate the effect of such variation on the performance of the circuit reference is made to various studies where the individual influence of oxygen or of cyanide has been investigated. Todate no work has been reported in which the combined influence of these two variables has been studied. Such a study — involving the determination of adsorption isotherms in synthetic systems — is reported in this paper.

Use of synthetic ore particles to test a transformation function in liberation analysis

One of the problems in attempting to validate the stereological procedures that are needed to establish the liberation characteristics of a particulate mineral system is the difficulty of obtaining suitable standard samples. In this paper, the development of a useful synthetic standard is described. The standard is then used to test the important transformation procedure developed by Baba, Miller and Herbst.

Assessing the Quality of Student Thinking Directly: An Exploratory Study of Two Cohorts Entering Engineering Education in South Africa.

This paper presents the findings of an exploratory investigation involving the direct assessment of the quality of abstract thinking of two cohorts of South African university entrants who had very good school leaving qualifications. The investigation was prompted by the observation of difficulties these students seemed to have had in a first year engineering course with regard to conceptualization and problem solving that called for abstract thinking. The investigation was based on neo-Piagetian principles and the benchmarked findings indicated an alarming level of concrete thinking in tasks that called for abstract thinking. The paper argues that this is a manifestation of a problematic secondary education system and that quality of thinking has received inadequate research attention as a potentially significant factor influencing student retention and academic performance in the country. It argues further that such research should include a re-evaluation of current first year educational strategies with regard to the development of the quality of student thinking and that, to support this, additional research is needed to develop appropriate instruments for providing objective measures of the quality of student thinking. Based on the experience gained in the study, recommendations are made about directions such research could take.