Influence of surfactants on crushing of marble

Abstract

Modern techniques demand extensive use of dispersed materials in such fields as ore beneflclation, structural materials, and ceramics. The most effective procedure is crushing of the material in the closed space of a mill.One way of intensifying crushing is the use of surfactants (SUR), which simultaneously enable us to regulate the grain-size composition of the product in the required direction.The results of investigations [2][3][4] indicate that the use of SUR in crushing enhances the output of the machines by 20-30%.Among the surfactants used are the following: distilled water, inorganic salts and bases, alcohols, amines, ethanolamines, glycols, sulfides, sulfanates, aliphatic acids, etc. Published reports do not give an additive selection scheme nor do they reveal the mechanism by which SUR act on the material being crushed.This has led us to investigate the crushing of solid materials with added organic SUR, with SUR containing hydroxyl and amine groups, and with a combination of both types. Table 1 lists the characteristics of the SUR used.As the material for this investigation we selected white marble of calcite--dolomite structure with specific gravity 3.7 kg/cm s and Mohs hardness 4.Marble of particle size 3-5 mmwas crushed for 5 min in a laboratory vibrating mill (capacity 0.375 llters). The grinding balls (diameter 30 and 22 mm) used constituted 50% of the mill volume, the weight of material crushed was 150 g. Organic additives were fed in continuously at the beginning of crushing.To determine the optimum amounts of the SUR used in these investigations we varied the additive concentration from 0.02 to 0.2 wt.% of the weight of the material being crushed. After crushing the marble was sifted, the --i00 ~ fraction being separated followed by determination of the specific surfaces: a) the external surface was measured on a PSKh-2 surfacemeter; b) the total specific surface was determined by the adsorption method by the Klyachko--Gurvich procedure.