Usage of a statistical method of designing factorial experiments in the mechanical activation of a complex CuPbZn sulphide concentrate

• Main Authors: Balá Peter, Godoèíková Erika, Leko Michal
• Format: Article
• Language: English
• Published: Technical University of Kosice 2003-09-01
• Series: Acta Montanistica Slovaca
• Subjects: mechanical activation; CuPbZn sulphide concentrate; surface area; factorial experiment
• Online Access: http://actamont.tuke.sk/pdf/2003/n2-3/15godocikova.pdf

Mechanical activation belongs to innovative procedures which intensify technological processes by creating new surfaces and making a defective structure of solid phase. Mechanical impact on the solid phase is a suitable procedure to ensure the mobility of its structure elements and to accumulate the mechanical energy that is later used in the processes of leaching.The aim of this study was to realize the mechanical activation of a complex CuPbZn sulphide concentrate (Slovak deposit) in an attritor by using of statistical methods for the design of factorial experiments and to determine the conditions for preparing the optimum mechanically activated sample of studied concentrate.The following parameters of the attritor were studied as variables:the weight of sample/steel balls (degree of mill filling), the number of revolutions of the milling shaft and the time of mechanical activation. Interpretation of the chosen variables inducing the mechanical activation of the complex CuPbZn concentrate was also carried out by using statistical methods of factorial design experiments. The presented linear model (23 factorial experiment) does not support directly the optimum search, therefore this model was extended to the nonlinear model by the utilization of second order ortogonal polynom. This nonlinear model does not describe adequately the process of new surface formation by the mechanical activation of the studied concentrate. It would be necessary to extend the presented nonlinear model to the nonlinear model of the third order or choose another model. In regard to the economy with the aspect of minimal energy input consumption, the sample with the value of 524 kWht-1 and with the maximum value of specific surface area 8.59 m2g-1 (as a response of the factorial experiment) was chosen as the optimum mechanically activated sample of the studied concentrate. The optimum mechanically activated sample of the complex CuPbZn sulphide concentrate was prepared under the following conditions: the weight of sample/steel balls (degree of mill filling) 125 g/2000 g; the number of revolutions of the milling shaft - 900 min-1 and the time of mechanical activation - 64 min.Indeed, it is necessary to emphasize that the application of mechanical activation has exceeded the framework of the laboratory research. The Institute of Geotechnics of SAS has achieved significant theoretical and technological results in the study of mechanical activation of sulphides and their reactivity in the different solid state reactions. Nowadays the mechanical activation is frequently applied in Australia, New Zealand and South Africa for the pretreatment of sulphide concentrates with a gold content.