Method for separating and enriching lithium, aluminum and silicon from fly ash

Abstract

The invention discloses a method for separating and enriching lithium, aluminum and silicon from fly ash. The method comprises the following steps: (1) pretreating fly ash; (2) carrying out low-temperature alkali dip reaction on the treated fly ash, aids and a sodium hydroxide solution, and filtering; (3) washing the filter residue, removing the impurities, filtering, and drying to obtain calcium silicate; (4) regulating the pH value of the filtrate to alkalinity, separating the lithium / aluminum-containing filtrate to obtain a sodium metaaluminate concentrated solution and a lithium-rich solution, carrying out reverse osmosis on the lithium-rich solution to obtain a lithium concentrated solution, and mixing the sodium metaaluminate concentrated solution with the lithium / aluminum-containing filtrate to obtain a refined solution; (5) precipitating the sodium metaaluminate refined solution, filtering to obtain aluminum hydroxide, and calcining to obtain the aluminum oxide finished product; (6) treating the lithium-rich solution to obtain a lithium-rich concentrated solution and fresh water; and (7) carrying out carbonating precipitation on the lithium-rich concentrated solution, filtering, and drying to obtain the lithium carbonate finished product. The method is a short-stage extraction process, reduces the lithium loss, and implements separation, enrichment and extraction of calcium silicate, aluminum oxide and lithium carbonate.

Description

technical field [0001] The invention belongs to the field of resource utilization of solid waste, relates to a separation and enrichment extraction method for lithium, aluminum and silicon in fly ash, relates to a short-flow extraction process, reduces lithium loss, separates and enriches to extract calcium silicate, oxidizes Aluminum, lithium carbonate method. Background technique [0002] my country is a large coal-producing and coal-burning country. Coal is the main energy source of my country's industry. A considerable part of coal resources is used for thermal power generation, resulting in a large amount of fly ash, which has become the largest single pollution source of China's industrial bulk solid waste. Fly ash The effects of stacking, leaching, and dust escaping have brought great potential harm to the ecological environment. At the same time, fly ash is also a waste with strong resource utilization. Its main constituent elements are Si, Al, etc., and the oxides o...

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Problems solved by technology

[0004] Chinese patents in the prior art, patent number CN 101125656 "a method for extracting silicon from fly ash first and then aluminum" and patent number CN 101284668 "a method for extracting silicon dioxide from high-alumina fly ash , alumina and gallium oxide” two invention patents are involved in the extraction of silicon and aluminum from fly ash, these two technologies adopt complex processes and long process, large material consumption, not conducive to the extraction of lithium, the NaOH solution used is only used for Pre-desilication, the product is white carbon black, and other resources in fly ash are not fully utilized

Patent No. CN 102923743's "Acid Method for Comprehensive Extraction of Aluminum and Lithium from Fly Ash" uses acid method to effectively extract alumina, but the acid method has obvious disadvantages, which will introduce a large number of impurity ions to the filtrate, and subsequent separation is difficult. , the acid method has high requirements on equipment and materials, large acid consumption and serious pollution

Patent No. CN 102923742's "A Method for Comprehensively Extracting Aluminum and Lithium from Fly Ash" adopts multiple alkali leaching methods, which has a long process flow, does not separate aluminum and lithium for the aluminum precipitation process, and causes a lot of loss of lithium, and does not consider Recycling of silicon etc.

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