Studies on the kinetics of slurry chlorination of a sphalerite concentrateby chlorine gas

Studies on the chlorination of a sphalerite concentrate in aqueous slurry b y gaseous chlorine have been carried out. The effect of time, flow rate of Cl-2, partial pressure of Cl-2 in N-2 (p(Cl2)), particle size and pulp dens ity of the sulphide concentrate and the temperature of chlorination, on the fraction of the zinc dissolved, has been investigated. At the optimum flow rate of Cl-2 (350 ml min(-1)), the percent of Zn dissolved is found to be increasing with decrease in particle size and pulp density, proportional to p(Cl2) (0.2 to 1.0 atm) and increases with increase in temperature in the range of 10 to 28 degrees C, studied. The activation energy of the chlorina tion process has been calculated to be 49.6 kJ mol(-1). In all the cases, t he fraction of the Zn dissolved (a) in time (t) is found to follow a diffus ion reaction control model: 1 - 2/3a - (1 - a)(2/3) = kt, where k is the ra te constant. At 28 degrees C, with 12 wt.% concentrate in the slurry acid u sing pure Cl-2 gas with a flow rate of 350 ml min(-1), nearly 90% of Zn ext raction has been achieved in about 17 min. (C) 1999 Published by Elsevier S cience B.V. All rights reserved.