The main solid waste generated during the production of alumina is red mud. As the world's largest alumina producer, China generally produces more than 30 million tons of red mud every year. However, due to the low level of the current utilization technology of red mud, most of the red mud can not be effectively utilized, resulting in the phenomenon of red mud accumulation is very serious. On the one hand, a large amount of red mud occupies a large amount of cultivated land, resulting in the waste of cultivated land, and on the other hand, it may also cause alkali to seep into the ground, pollute groundwater, and accelerate the deterioration of the ecological environment.
As a rare metal, gallium, due to its unique properties and characteristics, has greatly expanded its functions and uses, gradually improved its status, and increased demand, which has formed a great contrast with the current extraction process. Therefore, it is necessary to constantly seek new extraction methods and continuously improve the extraction rate to meet the current shortage of supply. The red mud used as waste contains gallium, which provides a new raw material for the extraction of gallium. The extraction of gallium from red mud not only makes use of red mud, but also alleviates the situation that gallium is in short supply.
Main reagents and instruments: The sample was taken from a Bayer alumina plant in Shanxi, placed for 30 days, dried and ground finely, and the sample was processed into debris no larger than 1mm. The main chemical components contained in the raw materials are ( ) Al20325,4, Si0218 54, CaO20 10, Fe2034 39, Na208 28, Ga2030 017, Ti024 45.
Experimental instrument: 722 spectrophotometer;FA2004 Analytical Balance;Electric Heating Jacket;Type 800 centrifugal precipitator;Brinell funnel;shz-d
Water ring vacuum pump.
Experimental reagent: hydrogen peroxide (p=1 10g ml). Titanium trichloride (TiC1) solution: 15 by mass. Sulfuric acid (H:S0) is diluted accordingly.
Sodium hydroxide (NaOH);
Hydrochloric acid (HC1) solution: 6mol L should be diluted accordingly.
Butylrhodamine B solution: 0 40 mass fraction.
Gallium standard solution A: This solution 1 ml contains 0 10 mg of gallium.
Gallium standard solution B: Pipette 10 00ml of gallium standard solution A into a 1000ml volumetric flask, dilute it to the scale with 6mol l of hydrochloric acid solution, and mix well. This solution contains 1 0txg gallium in 1 ml (ready when used).
Toluene. All the above reagents are analytically pure unless otherwise specified, and the water is distilled.
Conclusion: 1) The results of sulfuric acid leaching experiments are analyzed in the order of sulfuric acid concentration, liquid-solid ratio, reaction temperature and reaction time. The optimal experimental conditions for acid leaching were as follows: temperature of 160oC, concentration of 12mol l, time of 4h, and liquid-solid ratio of 7.
2) Due to the strong oxidation of sulfuric acid, the formation rate of the product layer on the surface of red mud is faster and the H activity is higher, and the leaching rate of gallium leached with sulfuric acid is higher than that of gallium leached with hydrochloric acid alone. (3) For this process to improve the leaching rate of gallium, the concentration and dosage of sulfuric acid should be well controlled, and the concentration of sulfuric acid is too large, and the consumption of acid and alkali is relatively large, which will increase the production cost. (4) The leaching slag of sulfuric acid leaching is larger than that of the leaching slag directly leached with hydrochloric acid, and the filtration speed is relatively slow. (5) Because the content of gallium in red mud is relatively small, the amount of red mud required to form precipitation is more, and the amount of precipitation generated is less. Therefore, this method has high requirements for instruments and equipment.