Method for separation and collection of purified alkali metal salt

Abstract

The present invention relates to a method for separating and recovering a purified alkali metal salt from an aqueous alkali metal salt solution, the method including a treatment step of removing a purification-inhibiting substance from an aqueous alkali metal salt solution with a separation membrane having a glucose removal ratio and an isopropyl alcohol removal ratio simultaneously satisfying the following expressions (I) and (II) when each of a 1000 ppm aqueous glucose solution having a temperature of 25° C. and pH of 6.5 and a 1000 ppm aqueous isopropyl alcohol solution having a temperature of 25° C. and pH of 6.5 is permeated through the separation membrane at an operating pressure of 0.75 MPa: Glucose removal ratio>=90% . . . (I), Glucose removal ratio-Isopropyl alcohol removal ratio>=30% . . . (II).

Description

technical field [0001] The present invention relates to a method for separating and recovering refined alkali metal salts such as refined lithium salts or refined potassium salts from lake water, groundwater, industrial waste water, etc., and to removing refined alkali metal salts by using a separation membrane exhibiting high selective permeability for specific compounds A method for effectively recovering and purifying alkali metal salts by removing hindering substances. Background technique [0002] In recent years, with the development of global industry and economy, the demand for mineral resources has expanded significantly. Among the indispensable mineral resources in various industries (including the semiconductor industry), some resources are technically difficult to obtain as elemental substances despite their large reserves in the earth's crust, and due to the high cost of mining and refining, they are not economically viable. It is not cost-effective, and in man...

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Problems solved by technology

Therefore, it is difficult to efficiently recover these salts as refined salts such as lithium carbonate

[0005] As a solution to the problem, various methods using an adsorbent (Patent Documents 1 to 3), etc. have been proposed, but the problem is that the cost is high, and there is no established technology for stably recovering refined lithium salt at low cost

As a conventional low-cost method, a method of removing impurities by sun-drying brine and concentrating it can be mentioned, but the method has a problem in that it is difficult to apply this method when the concentration of lithium is low or when the concentration of alkaline earth metal is high

Currently, while there is no serious resource concern for potassium, the resource crunch that accompanies the steady supply of fertilizer ingredients indispensable for food production, and the explosive population and economic growth of developing countries is a concern

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