Iron removal method for aluminum salt solution

Abstract

The invention discloses an iron removal method for an aluminum salt solution. According to the method, the aluminum salt solution containing iron is mixed with aluminum wires (powder), so that a replacement reaction happens to generate zero-valent iron powder, and then the iron powder is separated from the aluminum salt solution in a magnetic separating mode. By the adoption of the method, the concentration of iron ions of the aluminum salt solution containing iron is not restricted; on the premise that no novel impurities are introduced, the purity of the aluminum salt solution is improved, and iron impurities in the aluminum salt solution are removed and converted into valuable zero-valent iron powder. Compared with other iron removal methods, the method has a series of advantages that the technological process is simple, consumed time is short, the iron removal efficiency (capable of reaching 90%) is high, cost is low, energy consumption is small and the raw materials can be obtained easily. The difficult problems that an existing iron removal method is complex in working procedure, low in iron removal efficiency and high in energy consumption, and the requirement for the concentration of the iron ions in the aluminum salt solution is demanding are solved.

Description

technical field [0001] The invention belongs to the field of chemical industry, and relates to a method for removing iron from an aluminum salt solution, in particular to a method for removing iron from an aluminum sulfate solution. Background technique [0002] The main technical quality index based on the quality classification of aluminum sulfate products is the iron content, the higher the iron content, the lower the quality of aluminum sulfate. At present, the production of iron-free aluminum sulfate in China is mainly made by neutralizing aluminum hydroxide with sulfuric acid, but on the one hand, aluminum hydroxide is expensive, and on the other hand, China's high-grade bauxite resources are scarce, and the iron content is relatively high. The iron content is more than 0.3%, which cannot meet the iron content standard required by aluminum sulfate. Therefore, it is necessary to find a cost-effective method to remove iron ions in aluminum sulfate. [0003] There are m...

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Problems solved by technology

Potassium permanganate oxidation precipitation method achieves the purpose of iron removal by forming ferric hydroxide precipitation, but the ferric hydroxide precipitation is flocculent, which is difficult to filter and inconvenient to operate; potassium ferrocyanide and potassium ferricyanide precipitation method The resulting precipitated particles are extremely fine and blue solid precipitates, which are difficult to filter and easy to contaminate the product; the organic extraction method is based on the inmiscibility of organic solvents and aluminum chloride solutions, using iron ions to form complexes in the organic phase material, so that iron ions are transferred from the aluminum sulfate solution to the organic phase, so as to achieve the purpose of iron removal, but the extractants used (phosphate esters, amines, fatty acids, etc.) are expensive, and there is a problem of iron and extractant separation The problem is that the process is complicated, the operation is cumbersome, and it is not easy to master; the neutralization hydrolysis method has high requirements for the control of the hydrolysis pH, and the reaction process is easy to bring out other valuable metals and produce a large amount of iron hydroxide, which is also difficult to settle, filter and slag washing, and even As a result, the production process cannot be carried out due to the difficulty of solid-liquid separation; iron removal by recrystallization is a process in which aluminum sulfate crystals are dissolved in a solvent at high temperature to reach saturation, and then recrystallized from the solution at low temperature. It is necessary to repeat the crystallization several times to achieve the effect of iron removal. The process is complicated, requires precise control, and consumes a lot of energy and causes a lot of loss of aluminum salt

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