Study On A New Technology Of Fine Processing And Comprehensive Utilization Of Qinghai Serpentine

The separation of magnesium and silicon from Qinghai serpentine was achieved by sulfuric acid leaching. Refined magnesium sulfate solution was obtained by purification of filtrate; while water glass was prepared from residue after extracting magnesium from serpentine ore. Magnesium silicate, magnesium hydroxide and white carbon was respectively prepared from refined magnesium sulfate solution and water glass. The economic benefit analysis and environmental analysis were also taken. The main results of experiments were as follows:(1) The optimum conditions of acid leaching serpentine were determined by experiment, it is possible to extract 94% of magnesia from the mineral. While in the optimum conditions of alkaline leaching, it is possible to extract 96% of silicon dioxide. The experimental results show that the structure of Qinghai serpentine is more stable than the south of Anhui province and it leads to the acid leaching conditions more rigorous.(2) The optimum conditions of preparing magnesium trisilicate from Qinghai serpentine were determined by experiment. The quality of magnesium trisilicate obtained in the optimum conditions is up to the standards of the pharmacopoeia of the People's Republic of China(2005). The content of magnesia dioxide reaches 24.8%, while silicon dioxide reaches 53.2%. The weight ratio of SiO₂ to MgO is 2.15. The recovery rate of magnesium oxide reaches 84.1%.In the optimum conditions, the quality of magnesium hexasilicate meets the quality standards of magnesium hexasilicate. The content of magnesia dioxide reaches 13.8%, while silicon dioxide reaches 61.5%. The recovery rate of magnesium oxide reaches 85.2%.(3) In the optimum conditions, the quality of magnesium hydroxide is up to the standards of the chemical industry, HG/T3067-2000. The content of magnesia dioxide reaches 66.8%, the recovery rate of magnesium reaches 75.9%. The magnesium hydroxide product was characterized by SEM. It shows that the shape of product is nearly spherical.(4) In the optimum conditions, the quality of white carbon is up to the standards of the chemical industry, HG/T3061-1999. The content of silicon dioxide reaches 91%; the total recovery rate of silicon dioxide in serpentine reaches 88.4%. The product of white carbon is characterized by XRD and SEM, it shows that the structure of white carbon is amorphous, its shape is nearly spherical. It is the superfine power, the average pore size is 1.28μm.(5) Economic benefit analysis shows that it has good economic benefit to prepare magnesium silicate, magnesium hydroxide and white carbon from Qinghai serpentine. The environmental analysis shows that it nearly has no waste pollution production in the productive process. It is a cleaner production process.