A process for recovery of aluminum, potassium and gallium through rapid reduction and desulfurization of alunite at high temperature

Abstract

The invention discloses a process for recycling aluminum, potassium and gallium by quickly reducing and desulfurizing alunite at high temperature. The process comprises the following steps: roasting and dehydrating alunite ore powder at a certain temperature and within a certain time period to obtain alunite clinker; uniformly mixing with solid reductant coal according to a certain ratio, and carrying out fast high-temperature reduction roasting on alunite clinker the at a certain high temperature to realize desulfuration; extracting potassium from desulfurized calcine through water leaching, removing residual sulphur from the calcine; carrying out evaporative crystallization on water leaching solution to obtain a national standard product potassium sulfate; dissolving out aluminum and a small amount of potassium and metal gallium from water leaching residuals by a low-temperature low-alkali Bayer method; performing seed precipitation on leachate for recycling aluminum oxide, returning a seed precipitation mother solution to the dissolution process; regularly performing carbon decomposition on a part of the leachate for recycling the aluminum, potassium and gallium to obtain aluminum oxide, carbonate potassium and sodium carbonate and gallium-enriched precipitates, wherein the leaching residuals obtained through the low-temperature low-alkali Bayer method can be used as silicon raw materials for building products.

Description

technical field [0001] The invention belongs to the technical field of nonferrous metal metallurgy, and relates to a new process for comprehensively recovering aluminum, potassium and gallium from alunite ore. Background technique [0002] With the continuous development of the alumina industry, natural bauxite resources are decreasing day by day, so it is particularly important to study the use of non-bauxite aluminum resources such as alunite to produce alumina. The former Soviet Union, Mexico, etc. paid more attention to the research and promotion of the technology of extracting alumina by using alunite non-bauxite resources, and a large number of research results have been obtained and promoted in practice. my country's alum stone reserves rank third in the world, and it has been found that the alum stone reserves are more than 300 million tons. Among them, Zhejiang's mineral reserves rank first in the country, with a total of 234 million tons of proven reserves and 223...

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Problems solved by technology

[0014] CN103011206A discloses "a method for producing potassium sulfate and its by-products using alunite in flotation tailings", which mainly obtains alunite concentrate by flotation, then mixes the alunite concentrate with a reducing agent and makes pellets, Roasting at a temperature of 570-650°C for 15-30min, the amount of reducing agent is calculated by the grade of alunite, and the calcining is carried out under the conditions of adding 1-3 times of the theoretical requirement, the flue gas is used to make acid, and the obtained roasted material is quenched with potassium sulfate, and the reaction After the end, solid-liquid separation is carried out, and the filtrate is sent to a multi-effect evaporation system, and the potassium sulfate product is obtained by cooling and crystallization. After solid-liquid separation, it is alumina and aluminosilicate by-products, which are sold to cement plants as raw materials for cement production. This method is mainly from alum Potassium sulfate is produced in stone without considering the recovery of alumina and gallium, so there is no special requirement for the decomposition and desulfurization rate of aluminum sulfate during the roasting process and the leaching activity of alumina after roasting

In order to improve the extraction rate of potassium and reduce the impact on the subsequent production of alkaline alumina, the decomposition rate of aluminum sulfate as high as possible is required. The conventional measures to improve the decomposition rate of aluminum sulfate are to increase the roasting temperature and prolong the roasting time, but to increase the roasting temperature and Prolonging the calcination time will promote the pyrolysis product Al 2 o 3 The crystalline form transition, that is, the transition from the amorphous form with better activity to the crystalline form loses the leaching activity. Therefore, the pyrolysis desulfurization of alunite disclosed at present is carried out at a temperature lower than 650 ° C, and 650 ° C is regarded as Insurmountable temperature, even if the requirements of this temperature range are met, it will take a long time to completely remove the sulfur in aluminum sulfate, and a longer roasting time will lead to Al 2 o 3 The alkaline leaching activity of the alkaline leaching is reduced, which affects the subsequent extraction of aluminum

In addition, reduction desulfurization at lower temperature, due to slow reaction speed, low equipment operation efficiency, and difficult to control the roasting process

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