Use: in the production of aluminum hydroxide. Essence: the seed aluminum hydroxide is crushed, mix it with aluminate solution. The resulting suspension is incubated with stirring and treated with carbon dioxide. Separating the aluminum hydroxide from the mother liquor. Aluminum hydroxide is washed.
The invention relates to the production of aluminum hydroxide.
A method of obtaining fine aluminum hydroxide [1] in which the process is conducted in two stages. In the first stage aluminate solution is neutralized with hydrochloric acid, and the resulting finely dispersed aluminum hydroxide is used as the seed decomposition of supersaturated aluminate solution in the second stage.
The disadvantage of this method are the high costs caused by the neutralization of the caustic alkali by the acid, the accumulation of impurities in the solutions, etc.
Closest to the present invention is a method [2] in which for the production of fine aluminum hydroxide as seed use powdered aluminum hydroxide.
The disadvantage of this method are the high wintopo solution.
The aim of the invention is the reduction in the unit cost of energy by increasing the output of the fine aluminum hydroxide.
Processing aluminate solutions with carbon dioxide, the carbonization process is widely used in alumina plants operating by way of sintering. The use of carbonization can provide a high output hydroxide.
The grain size of aluminum hydroxide obtained in the carbonization process largely depends on the temperature of carbonization and composition of aluminate solutions (concentration of alkali and alumina).
The known method (Light metals. 1937, No. 10, S. 8-15) the production of fine aluminum hydroxide by the method of carbonization, including the processing of carbon dioxide ultracracker aluminate solutions (concentration 200 g/l) at low temperatures (30aboutC).
Although this method gives a high output fine aluminum hydroxide, its use is practically impossible due to technical difficulties arising in the final stages of the process: the Department of precipitation and washing.
However, when using nizkokontsentrirovannye method of carbonization fails.
The grain size of aluminum hydroxide obtained under these conditions, characterized by non-uniform composition and high content of coarse particles.
The invention consists in that in the method of production of fine aluminum hydroxide, comprising grinding the seed aluminum hydroxide, mixing it with the aluminate solution, aging the resulting suspension with stirring, separating the aluminum hydroxide from the mother liquor and washing, before separating the aluminum hydroxide from the mother liquor slurry is treated with carbon dioxide.
Studies have shown that when processing carbon dioxide aluminate solutions containing significant amounts of solids, the particle size is almost the same.
When making the crushed seed in supersaturated aluminate solution, and aging the resulting suspension with stirring produce large amounts of highly dispersed aluminum hydroxide. However, the yield of fine aluminum hydroxide without additional processing of the suspension is low and depends on the concentration of caustic alkali in the solution: the higher the concentration of alkali, the lower the output.
When processing carbon dioxide the initial suspension is provided by the output of aluminum hydroxide is the same as in the processing of the suspension after the preliminary exposure, however, dramatically increases the particle size of aluminum hydroxide.
The method can be implemented using existing hardware.
The method preferably alumina plants based on spechitelnoj technology.
Comparing data from multiple experiments suggests that the processing of the hydrate slurry obtained after exposure of the mixture of aluminate solution and shredded seed, carbon dioxide allows to obtain fine aluminum hydroxide and ensure high product yield.
P R I m e R 1. 0.02 kg of aluminum hydroxide with an average size of 2.8 μm was mixed with 1 liter of aluminate solution containing, g/l: Na2CMOS 100,8; Al2O3107,4.
The resulting suspension was passed at 60aboutWith over 10 hours Out fine aluminum hydroxide was 40,4, the Average particle size in the sediment of 3.6 μm. The composition of the liquid phase of the suspension, Noi mixture, containing about 12. CO2. The processing time of 6 hours to a Residual content of sodium oxide in solution after treatment of 5.6 g/L.
The average particle size in the sediment after treatment of 4.8 μm. The output of aluminum hydroxide 102,5.
P R I m m e R 2. 0.02 kg of aluminum hydroxide with an average size of 2.8 μm was mixed with 1 liter of aluminate solution and immediately (without exposure) was treated with carbon dioxide. The duration of treatment and concentration of CO2in a gas mixture similar to example 1.
The output of aluminum hydroxide was 103,1, the Average particle size in the sediment of 30.4 μm.
Therefore, the implementation of the above sequence of operations: mixture of aluminate solution with crushed seed extract, the resulting suspension, carbonation slurry before separation of aluminum hydroxide can provide a high output fine aluminum hydroxide.
METHOD of production of FINE ALUMINUM HYDROXIDE, comprising grinding the seed aluminum hydroxide, mixing it with the aluminate solution, aging the resulting suspension with stirring, separating the aluminum hydroxide from the mother liquor and washing,
Post time: Jul-09-2020