Study On Preparation Of Ultrafinealumina With Gangue And The Joint Process Of Sodium Silicate

When the coal is washed or mined, coal gangue which is a solid waste could be produced in this process, it accounts for about 15% of coal production. If it is discharged directly, it not only pollutes environmental but also waste resources seriously. Coal gangue contains large amounts of alumina﹑silicon dioxide Iron﹑magnesium and other minerals. We research on the separation of these substances and produce high value-added chemical products. According to our researched, Not only the shortage of alumina and silica resources, but also the problem of land covered, polluted environment, happening geological disasters and others may be solved by it. Consequently, researching the utilization of coal gangue is an important way to build resource-saving society. It has a very bright future and far-reaching significance.The coal gangue used in experimental contains about 45% silicon dioxide and 47% alumina. These two components are combined crystalline form and stable crystalline if coal gangue is not spontaneous combustion, consequently, it almost does not have chemical reactivity, and is hard to extract using. In this study, we use high-temperature method to turn the crystals into the higher activity of semi-crystalline or amorphous nature, so certain active coal gangue is made. Then, use acid leaching method to separate alumina and silicon dioxide in roast coal gangue. The effect of activation temperature, activation time, solid to liquid ratio, acid concentration, leaching time and leaching temperature on the extraction rate of alumina from coal gangue was studied, on the basic of it, the best leaching conditions was selected by orthogonal test. High value-added chemical products which are ultrafine alumina powder and industrial sodium silicate were prepared with filtrate and cake. In the course of prepared alumina, the impurities of aluminum chloride are removed by adjusting pH, and hard agglomerates of alumina particles were controlled by adding dispersants. When preparing industrial sodium silicate, we also research effects on the modulus at different sodium hydroxide concentration.The best conditions of coal gangue extraction was confirmed: liquid-solid ratio is 1:6, reaction temperature is 95℃, hydrochloric acid concentration is 20%, reaction time is 2.5h, roasting time is 1h and calcination temperature is 750℃. The leaching rate of alumina is 84.0% in these best conditions. When prepared alumina powder, triethanolamine was added in:aluminum chloride(1:20) is the best of alumina powder dispersed, Particle distribution, little reunion. When prepared industry liquid sodium silicate, the modulus of liquid sodium silicate is from 2.6 down to 1.0 following sodium hydroxide concentration increased. Liquid-3 was mainly used in building materials industry which can be prepared with liquid-3 at sodium hydroxide concentration 1.0 mol/dm~3.