Method for recovering and separating potassium salt and sodium salt from waste incineration fly ash

Abstract

The invention relates to a method for recovering and separating a potassium salt and a sodium salt from waste incineration fly ash, which comprises the following steps of: extracting the potassium salt, the sodium salt and a calcium salt from the waste incineration fly ash by quartz sand and water to obtain high-concentration salt-containing water, separating the quartz sand from the fly ash, returning the quartz sand for continue use; adjusting the pH value of the high-concentration salt-containing water to 5-7 with an acid, and conducting evaporating and concentrating to obtain potassium andsodium mixed salts and a residual calcium chloride saturated solution; conducting flotation separation on the potassium and sodium mixed salts in saturated potassium chloride and sodium chloride solutions, and conducting filtration, so as to obtain a foam product, namely potassium chloride, and tailings slurry, namely sodium chloride; respectively conducting stirring washing on the potassium chloride and sodium chloride obtained by flotation through corresponding saturated salt water, and conducting filtering to obtain industrial grade potassium chloride and sodium chloride products, whereina washing solution is a saturated potassium chloride and sodium chloride mixed solution and is returned to the flotation procedure as a supplement solution of a flotation medium. The method effectively separates soluble salts in the fly ash: potassium chloride, sodium chloride and calcium chloride without decalcification to obtain high purity or industrial grade potassium chloride and sodium chloride products; and the efficiency-cost ratio of the treatment process is greatly improved.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to a method for recovering and separating potassium salt and sodium salt in waste incineration fly ash. Background technique [0002] my country is a country with relatively poor potassium resources. The domestic production of potassium salt is mainly extracted from salt lakes and seawater, and most of the others need to be imported from abroad. Research results have shown that the content of potassium and sodium salts in incineration fly ash is as high as more than 20%. If it is not utilized, a huge "salt mine" will be wasted. Potassium and sodium salts in fly ash mainly exist in the form of chloride, and the content of chloride ion is as high as about 20%. According to the composition characteristics of waste fly ash, sintering cement as raw material is an effective method to dispose of waste fly ash. However, the content of chloride ion in waste fly ash is high,...

AI Technical Summary

Problems solved by technology

Since fly ash comes from waste incineration, a certain proportion of aggregated particles that are difficult to disperse will be formed during the production of fly ash. The direct mixing of fly ash with water is not uniform, and the soluble salts in fly ash particles are difficult to dissolve. At the same time, the fly ash particles are easy to agglomerate and agglomerate, which also makes it difficult to dissolve soluble salts. Therefore, the fly ash particles after wet grinding are finer and easier to agglomerate and agglomerate, which increases the difficulty of subsequent filtration.

After the fly ash is washed with water, high-concentration salt water is obtained, mainly potassium chloride, sodium chloride and calcium chloride. Sodium carbonate or sodium sulfate, the dosage of the agent is large, the disposal cost is high, and a large amount of calcium mud is produced at the same time

The separation of potassium and sodium salts through evaporation and crystallization requires multi-step crystallization and separation, and for washing water with similar potassium and sodium content, it cannot be effectively separated, and its applicability is narrow.

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