Integrated process for purification of low grade talc ores

LUCIANA CASTILLO; SILVIA BARBOSA; PEDRO MAIZA; NUMA CAPIATI

PARTICULATE SCIENCE AND TECHNOLOGY

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2014 vol. 32 p. 1 - 7

0272-6351

A research focused mainly on the development of an integrated process for the separation and purification of low grade talc with associated minerals recovery, is presented. This procedure involves an acid leaching to solubilize the gangue minerals and to purify talc, followed by minerals recovery from their corresponding cations as hydroxides via selective precipitation. In order to achieve a high purity degree of talc, inorganic acid was selected (HCl). This paper describes the use of this process for low-grade talc, containing up to 40% of associated minerals like calcite, dolomite, magnesite and chlorite. Laboratory-scale tests were conducted to determine the operating conditions that eventually allow the design of a conceptual process flowsheet for talc purification and associated minerals recovery. The effects of acid concentration, talc/acid ratio, time and reaction temperature on talc purification were studied and the optimal conditions were determined. The main results at laboratory-scale tests revealed that resulting talc is free of gangue, having so small particles with nanometric thicknesses. The reactants are fully consumed during the process and byproducts like carbonic anhydride and ammonium chloride could be recirculated and reused in the same process. Cations resulting from associated minerals dissolution can be precipitated as hydroxides, being available for water treatment as a coagulation aid.