Resource separation and recycling method of aluminum ash

Abstract

The invention relates to a resource separation and recycling method of aluminum ash. The method comprises the following steps: (1) preparing washed aluminum ash; preparing a sodium hydroxide solution;(2) putting the sodium hydroxide solution into a reactor, stirring, gradually adding the washed aluminum ash, and discharging generated hydrogen and ammonia gas; (3) adding water to dilute and stirring when hydrogen and ammonia gas are stopped being discharged, and filtering to obtain a primary filtrate; (4) under a stirring condition, adding hydrofluoric acid into the primary filtrate until thepH value is 3-5 to obtain a solid-liquid mixture; (5) filtering to obtain secondary filtrate and secondary filter residues; drying the secondary filter residues to obtain cryolite; and concentrating the secondary filtrate to prepare a Na2SiF6 product. According to the method disclosed by the invention, the aluminum ash is separated, recycled and utilized in a resource manner.

Description

technical field [0001] The invention relates to the technical field of recovery and treatment of hazardous waste solid materials produced in aluminum smelting, in particular to a method for resource separation, recovery and utilization of aluminum ash. Background technique [0002] Aluminum is the most abundant resource on earth, and its production is the second largest metal after steel. Because of its light weight and good oxidation and corrosion resistance, aluminum can be combined with many metal elements to form aluminum alloys with many different uses, and it is recyclable. Aluminum is produced by electrolytic alumina with cryolite flux molten salt; at present, the design production capacity of electrolytic cells in my country has reached more than 40 million tons / year, and the actual aluminum output is about 37 million tons / year. Recycling of scrap aluminum, the output of aluminum from secondary smelting, the actual output of aluminum should exceed 40 million tons per...

AI Technical Summary

Problems solved by technology

As can be seen from the above, there are many patented methods for producing alumina with aluminum ash; but up to now, there is no any kind of method applied in industry, and its existing problems are as follows: (1) the composition of aluminum ash is complex, although Different alloys produce different aluminum ash, but a common feature is that each aluminum ash contains not only impurity iron (Fe 2 o 3 ), but also contains a very high content of silicon impurities, magnesium, calcium oxide and fluoride impurities

For silicon impurities, it exists in aluminum ash in the form of silicon dioxide, and this silicon impurity will inevitably exist in the products of the above-mentioned various patent methods without removal and treatment; (2) the product is single, and Failure to recycle other products other than aluminum hydroxide

[0014] Patent CN101823741B discloses another aluminum ash treatment method. In this method, the aluminum ash after water immersion is first roasted at a high temperature at a temperature of 750-900° C. Carry out filtration after soaking, obtain solid product after filtrate is concentrated and evaporated, produce aluminum fluoride with the cryolite production method on the current industry, and evaporated liquid reacts with sodium hydroxide, produces water glass by the technology of current production water glass, and The filter residue is high-fluorine alumina containing magnesium fluoride; the problem of this method is that the process is complicated, and the oxides of calcium and iron with high impurity content in the aluminum ash cannot be effectively removed, so that the prepared The purity of the product fluorine-containing alumina is not high, so it is difficult to be applied in practice

However, these methods have not explained the purification treatment of silicon oxide, calcium fluoride, calcium oxide, magnesium fluoride and impurity iron with high content of other components in aluminum ash.

In fact, it may be a more complicated method to treat recycled aluminum ash with acid to obtain alumina with higher purity, and a large amount of acid-containing waste residue will be produced in the process.

In addition to treating aluminum ash with acid to produce water purifying agent, acid treatment of aluminum ash to produce alumina has not been applied in industry

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