Potassium extraction system and method based on biomass combustion fly ash

Abstract

The invention discloses a potassium extraction system and method based on biomass combustion fly ash. The system comprises raw material mixing equipment which is used for introducing mixed water and fly ash, and carrying out stirring and mixing to obtain a mixed solution; a stirring device used for introducing the mixed solution output by the raw material mixing equipment and uniformly stirring toobtain a uniformly stirred mixed solution; a standing sedimentation tank used for introducing uniformly stirred mixed liquid and standing to obtain supernatant and treated fly ash, wherein the staticsedimentation tank is provided with a heat exchange buried pipe used for carrying out heat exchange on the mixed liquid in the static sedimentation tank; and an evaporative crystallization device used for introducing the supernatant, realizing supersaturation of the potassium solution through evaporation, and crystallizing to separate out potassium salt. The system and method provided by the invention can realize retreatment of biomass combustion fly ash and high-efficiency extraction of the potassium salt.

Description

technical field [0001] The invention belongs to the technical field of solid waste resource utilization, and in particular relates to a potassium extraction system and method based on biomass combustion fly ash. Background technique [0002] Fossil energy will eventually be exhausted, and the development of renewable energy is conducive to alleviating energy demand and achieving sustainable development. Biomass is a high-quality renewable energy that can achieve CO 2 zero emission. [0003] The residual products after biomass combustion are slag and fly ash, and the content of fly ash accounts for more than 30% of the total. It contains high alkali metals, chlorides and heavy metals (Co, Pb, Cr, etc.), and is a valuable solid waste; among them, the content of K can reach more than 8%. Therefore, fly ash has a higher potassium extraction value. [0004] At present, the disposal of fly ash is often based on landfill, which not only occupies a large area of ​​land, but also...

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Problems solved by technology

[0005] Regarding the extraction of potassium salts, especially for the high-chloride and high-potassium fly ash of biomass boilers, general extraction methods cannot efficiently extract potassium salts. One of the reasons is that the solubility of potassium chloride varies greatly with temperature, as shown in the table 1 shown

In the conventional extraction method: on the one hand, the extraction speed is low at normal temperature; on the other hand, the amount of potassium salt that can be extracted by water at normal temperature is low

If the water temperature for extracting potassium is increased by 30°C or even 40°C from normal temperature, the solubility of potassium chloride will be greatly improved, but directly heating the water will greatly increase the cost of extracting potassium, which is not suitable for industrial production

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