Extraction system and method of using secondary amide/alkyl ester composite solvent to separate calcium and extract lithium from brine containing calcium and application thereof

Abstract

The invention discloses an extraction system and method of using a secondary amide / alkyl ester composite solvent to separate calcium and extract lithium from brine containing calcium and application of the extraction method. The extraction system contains secondary amid and alkyl ester, the secondary amid is formed by a single compound of the secondary amid or two or more mixtures, and the alkyl ester is formed by a single compound of the alkyl ester or two or more mixtures. The sum of carbon atoms in molecules of the secondary amid ranges from 12 to 18, and the sum of carbon atoms in molecules of the alkyl ester ranges from 8 to 20. The temperature of the freezing point of the extraction system is smaller than 0 DEG C. The single-stage or multi-stage counter-current extraction is conducted under the condition that the volume ratio of the organic phase to the brine phase is 1-10:1, the density of the brine ranges from 1.30g / cm<3> to 1.56g / cm<3>, the pH value of the brine ranges from 1to 7, and the temperature ranges from 0 DEG C to 50 DEG C; the aqueous phase with the low calcium lithium ratio is obtained through re-extraction; and lithium chloride, lithium carbonate and lithium hydroxide are obtained through concentration, impurity removal and preparation. The extraction system and method of using the secondary amide / alkyl ester composite solvent to separate calcium and extract lithium from the brine containing calcium and the application of the extraction method have the excellent effects that a secondary amide extracting agent is simple in molecular structure and easy to produce, and the properties such as the viscosity of the composite solvent are improved by the alkyl ester; the Li<+> multi-stage extraction rate is high, the lithium calcium separation coefficientis large, and the acid-base consumption of water re-extraction is low; the extraction separation technological process is short, the dissolution loss of the extraction system is few, and the extraction system and method are suitable for oil field brine exploitation.

Description

technical field [0001] The invention relates to a method for extracting lithium from calcium-containing brine, in particular to an extraction system, an extraction method and an application thereof for separating calcium and extracting lithium from calcium-containing brine with a composite solvent. Background technique [0002] There is abundant underground brine in oil fields in the Nanyishan area in the west of the Qaidam Basin in Qinghai, my country. Its resource reserves are comparable to those of the salt lake reserves in the Qaidam Basin. It is a rare multi-element coexistence super-large deposit in the world and has great industrial development value. . Among them, there are many useful components such as potassium, boron, lithium and iodine, and the content is high. The resource occurrence status is quite different from that of the developed salt lake resources. It belongs to the calcium chloride type brine in the Sulin classification, showing high salinity, high calc...

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Problems solved by technology

Li Bing and others evaporated the oilfield water to a specific gravity of 1.40-1.54, and frozen it at 0-30°C for 3-15 days to obtain lithium-rich brine (CN103508472A). This method takes a long time and the decrease in the mass ratio of calcium to lithium is limited.

[0004] In other methods for separating calcium in brine, Qin Xiaoming et al. use chelating cation exchange resin columns to remove metal cations above divalent in lithium-containing solutions at a pH value of 10 to 12 (CN108840354A), Guo Dingjiang, etc. use nanofilters to remove high-salt Calcium and magnesium impurities in lithium chloride mixed solution (CN106048218A) and Cao Naizhen etc. utilize extraction method to use P204 as extraction agent, sulfonated kerosene as sustained release agent to remove calcium and magnesium ions in lithium-rich solution (CN105712383A), these methods are only suitable for Advanced Purification Treatment of Low Concentration Calcium and Magnesium Containing Brine

At present, there are not many documents related to the study of high calcium-lithium ratio oilfield brine, especially the literature on the application of solvent extraction method to high calcium-lithium ratio brine for calcium-lithium separation has not been reported, which is attributed to Ca 2+ The valence layer has empty 3d orbitals, strong coordination ability, and the hardness and softness of ions are similar to those of Mg 2+ There are obvious differences. In fact, the separation of brine with high calcium-lithium ratio is more difficult than the separation of brine with high magnesium-lithium ratio. As a result, the development of lithium resources in oil field brines has not been realized so far.

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