Extraction system and method for separating calcium and extracting lithium from calcium-containing brine through secondary amide/alkane compound solvent and application thereof

Abstract

The invention discloses an extraction system and method for separating calcium and extracting lithium from calcium-containing brine through a secondary amide / alkane compound solvent and application thereof. The extraction system contains secondary amide and alkane which are each composed of one compound or a mixture of two or more compounds, the total numbers of carbon atoms in molecules are 12-18and 9-18, and the solidifying point of the extraction system is lower than 0 DEG C. When the volume ratio of an organic phase or a brine phase is (1-10):1, the density of the brine is 1.30-1.56 g / cm<3>, the pH value of the brine is 1-7 and the temperature is 0-50 DEG C, single-stage or multi-stage counter-current extraction is performed, low-calcium-lithium-ratio water phase is obtained through back extraction, and lithium chloride, lithium carbonate and lithium hydroxide are obtained through concentration, impurity removal and preparation. The extraction system has the advantages that a secondary amide extraction agent is simple in molecular structure and easy to produce, alkane improves the viscosity and other properties of the compound solvent, the Li+ multi-stage extraction rate is high, the lithium and calcium separating coefficient is high, the acid and alkali consumption is greatly reduced when back extraction is performed with water, the extraction separation technological process is short, the extraction system is low in dissolving loss and suitable for oil field brine development.

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. used chelating cation exchange resin columns to remove metal cations above divalent in lithium-containing solutions at a pH of 10-12 (CN108840354A), and Guo Dingjiang et al. used nanofilters to remove high salts. 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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