Fundamental Study On Acid Leaching Of Coal Gangue By Microwave Method

China is a developing country using coal as its main energy, coal accounts for about70percent in primary energy consumption. In the next period, China’s energy structure will not be changed radically, and coal will still be used as primary energy. Coal gangue is a solid waste generated during the process of coal production and processing, the annual emissions of which is equivalent to about15%of coal production in the current years. It is one of the largest industrial solid wastes in our country. Large accumulation of coal gangue not only take up lands, pollute the surrounding environment, but also be get resources waste. Thus, the integrative utilization of coal gangue is directly related to the sustainable development of China’s coal industry and environmental protection.In recent years, coal gangue is widely applied to power generation, production of building materials farmland reclamation and in the other aspects, but there exists some common problems such as low added value, bad economic benefits, low technological utilization. Coal Gangue in the "quality" is rich in aluminum, silicon, iron and other valuable elements, abundant in "quantity". So coal gangue’s duality in the " quality" and " quantity" decide the development direction of the scale and high value-added utilization.In this paper, Coal gangue is acquired from Liu Pan-shui as the main raw material, through mechanical activation to stimulate its activity, reacted with a certain quality of concentrated sulfuric in the case of microwave heating, dissolution rate of the valuable elements in coal gangue is commanded to be the main indexes, the effects of the experimental factors on the dissolution rate of metal and the impact of different operating modes on the experimental results was discussed. The chemical reactions mechanism of microwave heating in comparison with the conventional heating pickling way has been explored. Through experimental study, the conclusions as follows:(1) After mechanical activation, its fineness is obviously enhanced, increased the surface area of particles, destroyed the ordered structure of coal gangue minerals, loose inside porous, activity promotion, providing favorable conditions with the gangue acid dip extraction of valuable elements from coal gangue. (2) The experiments investigated that whether the coal gangue needs thermal activation treatment, pointing to the characteristics of the coal gangue’s low calorific value, consequently, confirming the experimental conditions of gangue’s acid hydrolysis directly but without the thermal activation treatment, and its metal dissolution rate is also relatively high.(3) The effect microwave firepower, acid gangue ratio and microwave heating time on the metal dissolution rate was investigated by single factor and orthogonal experiments, optimal conditions are concluded:acid gangue ratio is1.6, the type of heating is low fire, time is settled as60min.(4) Dissolution temperature, dissolution time and diluted multiples was studied, the optimal parameters of the dissolution reaction:dissolved temperature is90℃, the dissolution time is30min and diluted multiples is5times.(5) By examining the different experiments during reflow methods on the experimental results, and ultimately adopted the mode of operation without reflux, and in the experiment described in (3) and (4) optimize the parameters suggest, the gangue dissolution rate of Fe2O3is98.85%, Al2O3dissolution rate is96.64%, TiO2dissolution rate is92.01%.(6) Contrasted with general heating acid leaching methods, there are some advantages of microwave acid leaching with heating, for instance, short acid leaching time, high dissolution rate of valuable elements, less acid consumption and energy saving, eco-friendly; and discussed the thermal effect of microwave heating and mechanism of non-thermal effects of chemical reactions in two acceleration.