Ž . Int. J. Miner. Process. 58 2000 267–304 www.elsevier.nlrlocaterijminpro Surface chemistry–rheology relationships in concentrated mineral suspensions Stephen B. Johnson, George V. Franks, Peter J. Scales ) , David V. Boger, Thomas W. Healy Departments of Chemistry and Chemical Engineering, The UniÕersity of Melbourne, ParkÕille, Victoria, 3052, Australia Received 6 July 1999; accepted 22 July 1999 Abstract The rheological behaviour of concentrated mineral suspensions can be controlled by under- standing and regulating the net particle-particle interaction force. This paper summarizes the experimental results from studies showing how the yield stress of concentrated aqueous suspen- sions of alumina, zirconia and kaolin can be controlled through regulation of pH and the addition Ž . of inorganic electrolytes, ionic surfactants and polyelectrolytes polymers . The various kinds of inter-particle forces acting in aqueous suspensions of fine particles are reviewed and used to interpret the experimental results. q 2000 Elsevier Science B.V. All rights reserved. Keywords: surface forces; rheology; shear yield stress; compressive yield stress 1. Introduction When minerals are comminuted or liberated from their ores via an aqueous process- Ž . ing route, suspensions of fine F 1 mm or colloidal particles generally result. Such particles are often small enough to be unaffected by gravity and as a result, their interactions with each other and other larger particles are controlled by a range of ) Corresponding author. Advanced Mineral Products Special Res. Centre, School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia. Tel.: q 61-3-9344-6480; Fax: q 61-3-9344-6233; E-mail: p.scales@chemeng.unimelb.edu.au 0301-7516r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0301-7516 99 00041-1