Sustainable Mining and Metallurgy

The pretreatment of the high carbon bauxite was performed by Using sodium hydroxide solution，the carbonate in the high carbon bauxite was leached into the solution phase and the purpose of decarbonization was achieved. The effects of sodium hydroxide concentration, reaction temperature, reaction time and mineral slurry fixation content on the decarbonization effect of the high carbon bauxite were studied respectively. According to the test results, the carbon in high-carbon bauxite is mainly inorganic siderite carbonate，and its optimal reaction conditions for decarbonization are as follows: sodium hydroxide concentration 10%, reaction temperature 60℃, reaction time 80min, and slurry solid content control 800g/L. Under the optimal treatment conditions, the total carbon content of high-carbon ore can be reduced from 1.34% to below 0.35%, and the inorganic carbon removal rate can reach more than 90%. After pretreatment, the sodium carbonate solution was recovered by caustic reaction of lime milk, and the base solution was returned to circulation. The sodium carbonate solution obtained by this method does not contain sodium aluminate, which will not cause alumina loss in the caustic reaction process of lime milk, and effectively solves the problem of traditional sodium aluminate solution system cannot avoid alumina loss. After pretreatment, the carbon content of the ore can reach less than 0.35%, which meets the carbon control requirements of the Bayer alumina production system. The Bayer alumina production process no longer needs salt discharge, saves the consumption of salt discharge steam, and eliminates the impact of sodium carbonate on the Bayer alumina production process.