Search

The dissolution kinetics of a lateritic nickel ore in the sulphuric acid solution were investigated. The shrinking core model wasapplied to the results of experiments. The effects of stirring speed (100–600 rpm), H2SO4 concentration (0.1–2 mol l-1), leachingtemperature (40-96 °C) and the particle size of the ore were studied on the nickel dissolution rate. The correlation coefficients for eachdifferent parameters were calculated. The results indicated that the dissolution rate of Ni is controlled by diffusion. The activationenergy (Ea) for the dissolution reaction was determined to be 68.66 kJ mol-1. The Arrhenius constant was calculated to be 8.2578 s−1.The order of reaction for the H2SO4 concentration and the particle size were also obtained. It was found that the stirring speed hadno effect on the rate of nickel dissolution.

Optimum enriching possibilities of chromite ores from the abandoned Topraktepe mine were investigated. To obtain the best enriching method(s), shaking table, multi gravity separator, humprey spiral and jigging tests were tested. The best grades for Cr2O3 are 55.65% by shaking table, 57.52% by multigravity separator, 54.58 % by humprey spiral test and 50.68 % by jigging. To provide these results, the particle sizes of the ore are -0.3 to 0.212 mm for shaking table, -0.106 to 0.075 mm for multi gravity separator, -0.3 to 0.212 mm for humprey spiral and -2 to 1 mm for jigging. Regarding the best grades obtained, the recoveries for shaking table, multi gravity separator, humprey spiral and jigging methods are 85.38 %, 79.83 %, 94.89 % and 87.58 % respectively. The results of these tests show that a further recovery of remaining 500 000 tons of ore could be possible from the abandoned Topraktepe chromite deposit.