Extraction system, extraction method and application of separating calcium and extracting lithium from calcium-containing brine with secondary amide/alkyl ketone composite solvent

Abstract

The invention discloses an extraction system, an extraction method and an application thereof for separating calcium and extracting lithium from calcium-containing brine by using a secondary amide / alkyl ketone composite solvent. The extraction system contains secondary amides and alkyl ketones which are composed of a single compound or a mixture of two or more, the total number of carbon atoms in the molecule is 12-18 and 8-12 respectively, and the freezing point of the extraction system is less than 0°C. The volume ratio of the organic phase to the brine phase is 1-10:1, and the brine density is 1.30-1.56g / cm 3 , brine with a pH value of 1 to 7 and a temperature of 0 to 50°C for single-stage or multi-stage countercurrent extraction, back extraction to obtain a low-calcium-lithium ratio water phase, after concentration, impurity removal and preparation, lithium chloride, lithium carbonate and lithium hydroxide. Excellent effect of the present invention: secondary amide extractant molecular structure is simple, is easy to produce, and alkyl ketone improves properties such as the viscosity of composite solvent; Li + The multi-stage extraction rate is high, the lithium-calcium separation coefficient is large, and the acid-base consumption of water back extraction is small; the extraction and separation process is short, and the extraction system has little dissolution loss, which is suitable for the development of oilfield brine.

Description

technical field [0001] The invention relates to a method for extracting lithium from calcium-containing brine, in particular to an extraction system for separating calcium from calcium-containing brine to extract lithium with a composite solvent, an extraction method and its application. 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 calcium, Low m...

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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 softness and hardness of ions are also compatible with 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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