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China is a big country with asbestos mineral resources, reserves, ranking third in the world. The western region is a major asbestos producing areas of the country. The asbestos mining rate is not high, along with produce large amounts of asbestos tailings, except for a few backfill an area of ??stacked, the serious pollution of the surrounding environment, the threat to human health. Tailings contain a large number of components of value from the point of view of environmental protection and rational use of resources is necessary for recycling. At present, the domestic use of asbestos tailings preparation of light magnesium oxide can be divided into hydrochloric and sulfuric acid method, but there is the high cost, low conversion rate of raw materials and improper waste disposal, waste of resources and the quality of magnesium products, not high. In this paper, the characteristics of the Sichuan Province of asbestos tailings High magnesium content, on the basis of the research, the design of a closed cycle of clean production process route proposed cleaner production concepts and requirements for full control of the production process, and research and development of new addition to iron reagent, in order to guarantee the purity of the product of light magnesia. Not only from the point of view of production costs, energy consumption and efficiency considerations, more integration of the ecological factors in process design, to be eliminated from the production source pollution, waste minimization, recycling and harmless, or the eradication of the production process, price component of efficient, clean, comprehensive utilization of asbestos tailings. This paper studies the content and conclusions are as follows: (1) to determine the optimum leaching conditions magnesium ore samples. The leaching of magnesium in the ore sample is the most critical step in the process, their rigorous screening process conditions. Less material consumption in accordance with the Clean Production principles, the test conditions of ore sample particle size, acid type and amount of liquid to solid ratio, leaching time and cosolvent add volume to do a comparative study. Determine the optimum to the magnesium leaching rate indicators, as follows: 80 mesh ore sample liquid to solid ratio of 4:1 for the premise, the leaching rate of magnesium in 120% sulfuric acid and 1% cosolvent environment immersed mine 1h up to 98.76 percent year-on-year previous studies, this condition is feasible. (2) research and development of multi-effect separation agent separation of impurities. Crude magnesium sulfate solution containing impurities leaching of iron, if not removed can cause iron red phenomenon. Ammonia, sodium hydroxide as a precipitating agent, iron removal rate is not ideal, and pollution in the operating environment and corrosion production equipment. To solve this problem, the trial proceed from the perspective of clean production, R \u0026 D the new impurity reagents and more efficient separation agent, iron removal rate as a reference, and do comparison with the previous two reagents, the results show that the multi-effect separation agent in addition to the rate of 99.94% iron The above phenomenon does not exist to achieve separation test clean production. Thus determined that the multi-effect separation agent is the preferred precipitating agent, and the pH value at the impurity effect is preferably between 5.5 to 6.5. (3) the selection of conditions for the preparation of light magnesia. The tests were performed for the study of sodium carbonate powder, a slurry, a clear solution to find the best precipitate, while selecting the best aging time. After the formation of precipitation, drying, calcination temperature and time optimal choice. Solution was added to ultimately determine NaCO3 clear solution was reacted completely immediately after the filtration, without aging, and calcined at a high temperature of 850 ° C for 2.5h the highest purity of the product. Which washing is the key to ensuring the quality of magnesia program, better washing with hot water. The basic liquid waste after recycling byproducts no interference factors as industrial water to return to the mother liquor, and embodies the characteristics of the closed loop and clean production process eliminate the secondary pollution, reduce end processing load. (4) analysis of product quality inspection to ensure the purity of the desired target. The product of XRD learned MgO diffraction peaks are quite sharp, high purity; The SEM characterization learned that the particles were spherical morphology distribution products; chemical analysis and atomic absorption method for quantitative analysis. The data show that the MgO content of more than 95% to achieve the desired effect. Impurities of CaO content of 0.17%, only 0.0055% iron, 3.14% LOI, According HB/T2573-94 division of industrial grade magnesium oxide, the product of industrial grade magnesium oxide superior product level. High purity magnesium oxide as a refractory raw materials, there is a great use of space. (5) to do the entire process simple cost estimates and benefit analysis, preparation of magnesia clean production is environmentally friendly, economically beneficial process. The process is simple, environmentally friendly, high purity, low impurity content, the byproduct of a wide range of uses, means of resource for the asbestos tailings preparation lightweight magnesium oxide, well coordinated the development of production and environmental issues, the state advocates take the clean production , waste of resources and sustainable development of recycling economy road.
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