CN-121974380-A - Technological method for cooperatively extracting lithium, potassium and boron in salt lake

CN121974380ACN 121974380 ACN121974380 ACN 121974380ACN-121974380-A

Abstract

The invention provides a process method for synergistically extracting lithium, potassium and boron in a salt lake. The method comprises the steps of pretreating raw brine of a salt lake, mixing the raw brine with a first-stage extraction organic phase, carrying out multistage countercurrent extraction, obtaining a raffinate water phase after extraction, adding a potassium precipitant into the raffinate water phase, enabling potassium ions to form a precipitate, carrying out solid-liquid separation to generate boron-poor potassium-poor lithium-rich brine, enabling the boron-poor potassium-poor lithium-rich brine to contact with a lithium ion sieve adsorbent, adsorbing lithium ions on the lithium ion sieve adsorbent, and eluting the lithium ions by using an eluent to obtain a lithium-rich solution. The invention provides a novel integrated extraction process of lithium, potassium and boron with high cooperativity, which can simplify the flow, reduce the cost and protect the environment, and has great technical value and economic significance.

Inventors

LV LONG
SUN QUANXI
ZHU XIAOFENG
CHEN CHUNSHENG
LI TIANYU
YIN LINA
XIE PENG
GUO SHASHA
XU ZHIBO
PENG YANPING

Assignees

北京华特源科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260106

Claims (8)

1. A process method for cooperatively extracting lithium, potassium and boron in a salt lake is characterized by comprising the following steps: after pretreatment of the salt lake raw brine, mixing the salt lake raw brine with a primary extraction organic phase, and carrying out multistage countercurrent extraction to obtain a raffinate water phase after extraction is completed; Adding a potassium precipitant into the raffinate water phase to form potassium ions into a precipitate, and performing solid-liquid separation to generate boron-lean potassium-rich lithium-rich brine; And (3) enabling the boron-poor potassium-poor lithium-rich brine to contact with a lithium ion sieve adsorbent, adsorbing lithium ions on the lithium ion sieve adsorbent, eluting the lithium ions by using an eluent to obtain a lithium-rich solution.
2. The method of claim 1, wherein the pretreatment of the salt lake raw brine, the mixing with the first-stage extraction organic phase, and the multistage countercurrent extraction are carried out to obtain a raffinate water phase, and the method comprises the following steps: Filtering the salt lake raw brine to remove suspended impurities to obtain clarified brine, regulating the pH value of the clarified brine to be in an acid range of 1.0-3.0, mixing the brine with a primary extraction organic phase, and carrying out multistage countercurrent extraction to obtain an extract and a raffinate phase after extraction is completed; The primary extraction organic phase consists of an extractant, a synergistic extractant and a diluent, wherein the extractant is an alcohol or diol compound containing ortho-position dihydroxyl, the synergistic extractant B is a neutral phosphorus oxy compound, after extraction is finished, a boron-loaded organic phase and a raffinate water phase containing lithium and potassium are obtained, and the boron-loaded organic phase is subjected to back extraction by using a NaOH solution to obtain an enriched sodium borate solution.
3. The method according to claim 2, wherein the extractant is a higher aliphatic alcohol or polyol having a carbon chain length of C8-C12, the volume percentage of the extractant in the primary extracted organic phase is 10% -30%, the synergistic extractant is tributyl phosphate, the volume percentage of the synergistic extractant in the primary extracted organic phase is 5% -30%, and the diluent is sulfonated kerosene.
4. A method according to claim 2 or 3, wherein adding potassium precipitant to the aqueous raffinate phase to precipitate potassium ions, and performing solid-liquid separation to produce a boron-depleted potassium-depleted lithium-enriched brine, comprising: Indirectly heating a raffinate water phase by using a plate heat exchanger or a tubular heat exchanger through hot water or steam, regulating the temperature of the raffinate water phase to 15-35 ℃, adding an organic phosphate potassium precipitant into the temperature-regulated raffinate water phase, selectively reacting the organic phosphate potassium precipitant with potassium ions in the raffinate water phase to form chelate precipitate, separating potassium precipitate to generate boron-depleted potassium-depleted lithium-enriched brine and potassium salt precipitate, wherein the organic phosphate potassium precipitant is dipropylene glycol phenyl ether phosphate DPPP or tetraphenyl borate, and the adding amount of the organic phosphate potassium precipitant is 1.05-1.2 times of the theoretical calculated molar amount of potassium ions.
5. The method of claim 4, further comprising treating the potassium salt precipitate with dilute sulfuric acid, decomposing to obtain a potassium sulfate solution and a regenerated DPPP precipitant, evaporating, concentrating, crystallizing and drying the potassium sulfate solution to obtain a potassium sulfate product, and returning the regenerated DPPP precipitant to the precipitation process for recycling after treatment.
6. The method of claim 4, wherein contacting the boron-depleted potassium-depleted lithium-enriched brine with a lithium ion sieve adsorbent, adsorbing lithium ions onto the lithium ion sieve adsorbent, eluting the lithium ions with an eluent to obtain a lithium-enriched solution, comprising: After regulating the pH value of the boron-lean potassium-lean lithium-rich brine to 7.0-11.0, enabling the boron-lean potassium-lean lithium-rich brine to pass through an adsorption tower filled with a lithium ion sieve adsorbent, wherein the lithium ion sieve adsorbent is a manganese-titanium composite lithium ion sieve with a core-shell structure, the manganese-titanium composite lithium ion sieve with the core-shell structure takes a manganese-titanium lithium ion sieve as a core, a high polymer organic matter as a shell, and a core layer consists of a manganese-titanium composite oxide and has a three-dimensional pore structure, lithium ion intercalation sites are provided, and selective adsorption of lithium is realized; After entering an adsorption tower, the lithium ions in the brine pass through a hydrophilic polymer shell layer, the shell layer serves as a molecular sieve barrier, the lithium ions are selectively allowed to pass through, the lithium ions are further diffused into a manganese-titanium composite oxide core layer, the lithium ions are specifically adsorbed in lattice pore channels of the core layer through an ion exchange or intercalation mechanism, the unadsorbed sodium, magnesium and calcium ions flow out of the adsorption tower along with the brine, after adsorption saturation, 0.01-0.5 mol/L of hydrochloric acid, sulfuric acid or citric acid solution is used as eluent, the lithium ions enriched on the manganese-titanium composite lithium ions of the core-shell structure are eluted, so that a lithium-enriched solution is obtained, and the eluted manganese-titanium composite lithium ion sieve of the core-shell structure is used for the next round of adsorption of lithium ions after water washing to neutrality.
7. The method of claim 1, wherein the lithium ion sieve adsorbent is a manganese ion sieve, a titanium ion sieve, or a manganese titanium composite ion sieve.
8. The method of claim 6, wherein the functionalized shell layer of the manganese-titanium composite lithium ion sieve with the core-shell structure is a hydrophilic organic substrate, and the hydrophilic organic substrate comprises one or more of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, cellulose acetate butyrate and sodium carboxymethyl cellulose.

Description

Technological method for cooperatively extracting lithium, potassium and boron in salt lake Technical Field The invention relates to the technical field of salt lake chemical industry and inorganic salt separation, in particular to a process method for cooperatively extracting lithium, potassium and boron in a salt lake. Background Salt lakes are a strategic mineral resource pool of global importance and are rich in various elements such as lithium, potassium, boron, magnesium, and the like. With the rapid development of new energy automobiles, energy storage industry and fine chemical industry, the market demands of lithium, potassium and boron are continuously rising, and the efficient and green extraction of the resources from salt lakes has become a focus of global research and technical competition. Currently, the industry mostly adopts a "fractionation" or "tandem" process for the development of salt lake resources. For example, the production of potash fertilizer mainly depends on a large-scale salt pan tedding and flotation crystallization method, and the process has high energy consumption, large occupied area and strong weather dependence. The lithium extraction method is various and includes precipitation method, adsorption method, solvent extraction method, membrane separation method, etc. Among them, the adsorption method is considered as an effective means for treating salt lake brine with high magnesium-lithium ratio due to its high selectivity, and particularly, the synergistic solvent extraction system (SYNERGISTIC SOLVENT EXTRACTION SYSTEMS, SSX) is also attracting attention due to its high efficiency and low energy consumption. Boron is usually extracted by extraction or precipitation. At present, the extraction method of lithium, potassium and boron in the salt lake in the prior art has the following defects: 1. The technology method in the prior art is designed for a single element, such as 'potassium before lithium' or 'lithium before boron'. In this serial processing mode, the operation of each unit is independent and even mutually interfered. For example, boron and magnesium plasmas are impurities that need to be removed in advance during lithium extraction, which increases the complexity and cost of the process, while the old brine component after potassium extraction is more complex, which presents a greater challenge for subsequent lithium extraction. 2. The process flow is long, the energy consumption and the material consumption are high, the process route for sequentially extracting the multiple elements is long, the steps of evaporation concentration, precipitation, filtration and the like are involved, and huge energy consumption and material loss are caused. For example, conventional evaporative precipitation processes are not only inefficient, but also produce large amounts of tailings and waste streams. 3. The environmental load is large, the ecological topography is changed by the large-scale tedding of the salt field, and a large amount of chemical reagents are used by some precipitation methods and extraction methods, so that secondary pollution is easily caused if the chemical reagents are improperly treated. Disclosure of Invention The embodiment of the invention provides a process method for cooperatively extracting lithium, potassium and boron in a salt lake, so as to realize the synergistic efficient comprehensive recovery of the lithium, potassium and boron in the salt lake. In order to achieve the above purpose, the present invention adopts the following technical scheme. A process method for cooperatively extracting lithium, potassium and boron in a salt lake comprises the following steps: after pretreatment of the salt lake raw brine, mixing the salt lake raw brine with a primary extraction organic phase, and carrying out multistage countercurrent extraction to obtain a raffinate water phase after extraction is completed; Adding a potassium precipitant into the raffinate water phase to form potassium ions into a precipitate, and performing solid-liquid separation to generate boron-lean potassium-rich lithium-rich brine; And (3) enabling the boron-poor potassium-poor lithium-rich brine to contact with a lithium ion sieve adsorbent, adsorbing lithium ions on the lithium ion sieve adsorbent, eluting the lithium ions by using an eluent to obtain a lithium-rich solution. Preferably, after the pretreatment of the salt lake raw brine, the salt lake raw brine is mixed with a primary extraction organic phase to carry out multistage countercurrent extraction, and the extraction is completed to obtain a raffinate water phase, which comprises the following steps: Filtering the salt lake raw brine to remove suspended impurities to obtain clarified brine, regulating the pH value of the clarified brine to be in an acid range of 1.0-3.0, mixing the brine with a primary extraction organic phase, and carrying out multistage countercurrent extraction to obtain an extract and a ra