Removal of copper from magnetite concentrates by chlorination

Two magnetite concentrates from Palabora mine, South Africa, containing und esirable amounts of copper (from 0.056 to 0.068%) and differentiated by the ir titanium content, were chlorinated in air-chlorine mixtures in the ratio s 10 : 1, 15 : 1 and 20 : 1 at temperatures between 1200 and 1329 K. In a f ixed reactor the now rate of chlorine was 12 cm(3) min(-1) and that of air ranged between 120 and 240 cm(3) min(-1); a few tests were also conducted i n a fluidized-bed reactor. The resulting volatile chlorides were condensed and the solutions were analysed by atomic absorption spectroscopy for coppe r, iron and titanium. According to the results obtained from an orthogonal array of experimental runs, the most influential variable was the temperature, followed by the re action time and the ratio of chlorine to air. When the reaction temperature was low and the run time was short the recovery of copper was less than 25 %, but it increased to nearly 100% when the temperature was raised to 1329 K. The amount of iron carried over ranged between 0.05 and 4.70%. When the magnetite concentrates were oxidized prior to chlorination with HCl gas (ge nerated from combustion of scrap PVC) about 97% of the copper was removed a nd no iron was detected in the volatile products. For the same residence ti me and nearly similar reaction temperatures higher recoveries were obtained when the high-titanium magnetite concentrates were chlorinated in a fluidi zed-bed reactor in the presence of air than were obtained with the fixed re actor.