[China Aluminum Network] coal gangue is the waste in the coal production process, is the main coal-based solid waste, there are piles of coal gangue around the many mines, both environmental pollution, but also occupy large areas of land, the national gangue The total stockpile is about 4.5 billion t [1-2]. The environmental pollution is large and the waste of resources is serious. There are a lot of aluminum elements in coal gangue, and the content of alumina accounts for about 25%, which is an available resource [3-4]. After utilization, it not only solves the problem of land occupation and environmental pollution in coal gangue, but also Turn waste into treasure to create more economic benefits [2,6-8]. Coal gangue can be prepared by leaching with sulfuric acid. The latter is a commonly used flocculant and is mostly used for sewage treatment. This experiment has analyzed and studied coal gangue of a mine in Zhengzhou mining area. After several experiments, under the better conditions, the dissolution rate of aluminum can be stabilized to 89.6%, and the purity of prepared aluminum sulfate can reach 95%, which is gangue Development and utilization provide new ideas. First, the experimental part (a) material a certain mineral gangue in Zhengzhou, crushed to 40 mesh, its composition shown in Table l. (B) Instruments and Equipment Muffle, pH meter, electronic balance, grinder, mixer. (3) Reagent leaching reagents: 1:1 hydrochloric acid (diluted hydrochloric acid diluted in distilled water), 1:2 sulfuric acid (diluted sulfuric acid diluted twice in distilled water), and reversed aqua regia (concentrated nitric acid: concentrated hydrochloric acid = 3:1) Aluminum determination reagent: 10% sulfosalicylic acid, 0.02mol/L Accu04, 0.02mol/L ethylenediaminetetraacetic acid (EDTA), 1:1 hydrochloric acid, 1:1 ammonia, acetic acid-sodium acetate, pH 5.0 Buffer solution, PAN indicator. (D) Experimental method Weigh a suitable amount of gangue samples after drying, placed in a muffle furnace at a certain temperature and high temperature roasting, sinter at a certain temperature with a certain amount of sulfuric acid leaching, test roasting temperature, roasting Time, acidity, leaching temperature, leaching time and other factors on the leaching rate of aluminum, to develop a better leaching conditions for aluminum in coal gangue. Determination of aluminum: EDTA continuous measurement. II. EXPERIMENTAL RESULTS AND ANALYSIS (I) Effect of activation temperature Coal gangue directly leached coal gangue with concentrated sulfuric acid and reversed aqua regia without activation treatment for 2 hours, its dissolution rate is very low, only 3.6%. 50g of 40-mesh coal gangue was collected in a magnetic evaporating dish and fired at 400°C, 600°C, 800°C, 1000°C, and 1200°C in a high-temperature furnace for 5 hours. After cooling, 10g of 1:2 sulfuric acid was added for leaching for 5 hours. According to the data of Table 2, dissolution rate and temperature were plotted. When the calcination temperature exceeds 500°C, the A12O3?2SiO2?2H2O component in the coal gangue starts to remove some hydroxyl groups and changes from crystalline to amorphous state; the activity reaches 700°C. Higher. After 1000°C, a new phase γ-A12O3 and mullite phase were formed, and the amount of aluminum dissolved rapidly decreased. (2) Effect of leaching time Weigh 30g of coal gangue sample after calcination at 800°C, add 150mL of 1:1 hydrochloric acid, and control the temperature at 85°C. Pipette 1mL of leach solution several times for analysis. Experiments show that the leaching time is 5h, the dissolution rate is too slow for too long time, the time is too short, and the dissolution rate is low, which can not reach the production purpose. (III) Effect of Acid Type Acids used in acid leaching include HNO3, HCl and H2SO4. Based on the technically feasible and economically reasonable principles, the acid used should be selected from HCl and H2SO4. The leaching of 10 g of the ore sample at 800°C with 1:1 hydrochloric acid and 1:2 sulfuric acid was performed at a rate of 1.5 times, respectively, and 100 mL was prepared (the weight loss rate of the mineral sample was 11.3%). The results showed that the dissolution rate of hydrochloric acid was 68.78%; the dissolution rate of sulfuric acid was 89.6%. It can be seen that, with the same amount of acid and the same leaching time, the dissolution rate of sulfuric acid is much greater than that of hydrochloric acid, and the concentration of sulfuric acid for industrial use is quite large and the price is much cheaper than that of hydrochloric acid. Therefore, the use of sulfuric acid to leach gangue Have better economic benefits.