Decalcification method of calcium chloride type lithium-containing brine

Abstract

A method for removing calcium from calcium chloride type lithium-containing brine: calcium removal from brine, calcium chloride type lithium-containing brine is mixed with potassium sulfate to react, and is discharged into a solar pond for evaporation and natural sedimentation of calcium sulfate solid or direct solid-liquid separation, and the calcium-removed brine is used for subsequent impurity removal and lithium recovery; calcium sulfate recovery, the naturally sedimentated calcium sulfate is recovered by salt mining, the calcium sulfate is separated from halite or sylvite, the calcium sulfate slurry is solid-liquid separated, the calcium sulfate is reused to prepare potassium sulfate, and the filtrate is reused to prepare pulp; if the calcium sulfate is not mixed with halite or sylvite, the calcium sulfate is dehydrated and reused to prepare potassium sulfate; potassium sulfate preparation, ammonia water and a lower aliphatic alcohol are used as solvents, potassium chloride salt or sylvite and the like containing potassium chloride are reacted with calcium sulfate to generate potassium sulfate solid and calcium chloride ammonia water solution, the potassium sulfate is separated from the calcium chloride ammonia water solution, the potassium sulfate is recycled and reused for calcium removal, and the calcium chloride ammonia water solution is recovered for ammonia and lower aliphatic alcohol; recycling of ammonia and alcohol, the calcium chloride ammonia water solution is recovered for ammonia and lower aliphatic alcohol, and the method has the advantages of efficient calcium removal, simplified process and easy engineering implementation.

Description

TECHNICAL FIELD

[0001] The application relates to the fields of bio-metallurgy and environmental protection, and particularly relates to a method for removing calcium from calcium chloride type lithium-containing brine. BACKGROUND

[0002] The CaCl2 type brine has a high Ca content, and almost contains no CO3 2- and HCO3 - , and has a very small SO4 2- content, is a high-mineralization (100-300 g / L) brine resource rich in various valuable elements (K, B, Li, Sr, Br, I) or heavy metal elements (Fe, Mn, Cu, Pb, Zn, Ba), and is mainly distributed in various sedimentary basins, mid-ocean ridge hydrothermal fluids and continental tectonic activity zones. The CaCl2 type brine is of great significance for the formation of large-scale potash deposits, and makes the salt deposition sequence simple (gypsum-salt-sylvite- carnallite), and the enrichment of K elements in the brine with the appearance of typical minerals (larnite, antarcticite, borate, etc.

[0003] Lithium is called "white oil" because of its unique physical and chemical properties. The position of lithium ion batteries in energy storage and power batteries is becoming more and more prominent.

[0004] According to the traditional concept, because of the particularity of the positions of lithium and magnesium in the periodic table, the chemical properties of lithium and magnesium are very similar, which leads to the fact that it is very difficult to extract lithium from high-magnesium lithium brine. Calcium and magnesium are both group II A elements and are located in the upper and lower adjacent positions, but the properties of the two are obviously different, and it is more difficult to extract lithium from high-calcium brine than from high-magnesium brine.

[0005] In order to solve the above difficulties or problems, Pan Lei et al. published a combined process of freezing crystallization / mirabilite decalcification to remove a large amount of Ca 2+CN201310463888.8 disclosed a method for extracting lithium from oilfield brine, which proposed to evaporate the oilfield brine to a specific gravity of 1.40-1.54, and then freeze crystallize at 0-30℃ for 3-15 days to obtain lithium-rich brine. However, this method has the problem of long freeze crystallization period, which is difficult to be applied in engineering; Yang Lixin's research group developed a method for extracting and stripping lithium from calcium-containing brine above 0℃ using secondary amide type composite solvent (CN201911088271.6), and further optimized the composition of the extractant to realize the extraction of lithium from calcium-containing brine below 0℃; In terms of industrial application, the Maricunga project in Chile used continuous evaporation and crystallization process for decalcification, but it was still in the pilot stage and had not been applied in engineering; Recently, the 3Q project in Argentina used a combined process of natural evaporation and freeze crystallization for decalcification, and developed a calcium chloride crystal washing process to solve the problem of large amount of brine entrained by calcium chloride crystals, which could improve the overall recovery rate of lithium. However, due to the special properties of calcium chloride solution and crystals, this process has the disadvantage of strict control of process conditions in engineering application.

[0006] Therefore, it is of great significance to develop a method for decalcification of calcium chloride type lithium-containing brine. SUMMARY

[0007] The task of the present application is to overcome the shortcomings of the prior art, and to provide a method for decalcification of calcium chloride type lithium-containing brine, which can efficiently decalcify calcium chloride type lithium-containing brine and simplify the process conditions, and is easy to realize engineering recovery.

[0008] The task of the present application is accomplished by the following technical scheme:

[0009] A method for decalcification of calcium chloride type lithium-containing brine, which is aimed at the problem of calcium removal from lithium-containing brine, and the specific process steps and conditions are as follows:

[0010] (1) Decalcification of brine, mix and stir calcium chloride type lithium-containing brine with potassium sulfate at 0.9-1.1 chemical equivalent for 10-60 min, discharge to a solar pond for evaporation and natural sedimentation of calcium sulfate solid or directly perform solid-liquid separation, and use the decalcified brine for subsequent impurity removal and lithium recovery;

[0011] (2) Calcium sulfate recovery, the calcium sulfate naturally precipitated is recovered by salt mining, if the calcium sulfate is mixed with halite or sylvite, etc., first crushing, then pulping, then using a shaker or hydrocyclone, etc. to separate the calcium sulfate from the halite or sylvite, and the calcium sulfate slurry is subjected to solid-liquid separation, and the calcium sulfate is recycled for the preparation of potassium sulfate, and the filtrate is recycled for pulping; if the calcium sulfate is not mixed with halite or sylvite, etc., the calcium sulfate is dehydrated and recycled for the preparation of potassium sulfate;

[0012] (3) Potassium sulfate preparation, using the solubility difference of salt in different solutions, taking ammonia water and lower aliphatic alcohol as the solvent, and taking potassium chloride salt or sylvite and other impurities containing potassium chloride to react with calcium sulfate to generate potassium sulfate solid and calcium chloride ammonia solution, then through solid-liquid separation, the potassium sulfate is separated from the calcium chloride ammonia solution, the potassium sulfate is recycled for calcium removal of calcium chloride type brine, and the calcium chloride ammonia solution is recycled for ammonia and lower aliphatic alcohol recovery;

[0013] (4) Ammonia and alcohol recovery and recycling, the calcium chloride ammonia solution is recycled for ammonia and lower aliphatic alcohol recovery.

[0014] The working principle of the present application is as follows:

[0015] The present application utilizes the characteristics of potassium chloride decomposing calcium sulfate to generate potassium sulfate crystals and calcium chloride solution in a specific solvent, and realizes efficient calcium removal through sulfate regeneration and recycling. The main chemical reaction equation and the simplified process flow diagram of sulfate recycling and calcium removal are as follows:

[0016] KCl + CaSO4·2H2O → K2SO4(crystal)↓ + CaCl2

[0017] K2SO4 + CaCl2 → KCl + CaSO4·2H2O↓

[0018] Compared with the prior art, the present application has the following advantages or effects:

[0019] (1) Because the ammonia water and lower aliphatic alcohol are recycled and utilized through sulfate recycling, the dependence on the outside world is low, and efficient calcium removal can be achieved.

[0020] (2) At the same time, the calcium chloride type brine is transformed, avoiding the potential problems of high calcium brine concentration, impurity removal and lithium extraction, so that the engineering recovery is easier to realize.

[0021] The application file involves % by mass. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a calcium chloride type lithium-containing brine decalcification method process flow diagram according to the present application.

[0023] Figure 2 is Figure 1The process flow diagram of the method for removing calcium from calcium chloride type lithium-containing brine by sulfate radical.

[0024] Figure 3 is Figure 1 The process flow diagram of the method for removing calcium from calcium chloride type lithium-containing brine by sulfate radical.

[0025] Figure 4 is Figure 1 The process flow diagram of the method for removing calcium from calcium chloride type lithium-containing brine by sulfate radical.

[0026] Figure 5 is Figure 1 The process flow diagram of the method for removing calcium from calcium chloride type lithium-containing brine by sulfate radical.

[0027] The application will be further described in detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] As Figure 1 shown, a method for removing calcium from calcium chloride type lithium-containing brine, aiming at the problem of calcium removal from lithium-containing brine, the specific process steps and conditions are as follows:

[0029] (1) Brine decalcification, calcium chloride type lithium-containing brine is mixed with potassium sulfate at 0.9-1.1 chemical equivalent, stirred and reacted for 10-60 min, discharged into a solar pond for evaporation and natural sedimentation of calcium sulfate solid or directly for solid-liquid separation, and the decalcified brine is used for subsequent continuous impurity removal and lithium recovery;

[0030] (2) Calcium sulfate recovery, the naturally settled calcium sulfate is recovered by salt mining. If the calcium sulfate is mixed with stone salt or potassium stone salt, etc., it is first crushed, then pulped, and then separated from the stone salt or potassium stone salt by using a shaking table or a hydrocyclone, etc. The calcium sulfate slurry is subjected to solid-liquid separation, and the calcium sulfate is recycled for the preparation of potassium sulfate, and the filtrate is recycled for pulping. If the calcium sulfate is not mixed with stone salt or potassium stone salt, etc., the calcium sulfate is dehydrated and recycled for the preparation of potassium sulfate;

[0031] (3) Preparation of potassium sulfate, taking advantage of the difference in solubility of salt in different solutions, using ammonia water and lower aliphatic alcohol as solvent, and using potassium chloride salt or potassium stone salt and other chlorides containing potassium chloride to react with calcium sulfate to generate potassium sulfate solid and calcium chloride ammonia solution, then separating the potassium sulfate from the calcium chloride ammonia solution by solid-liquid separation, the potassium sulfate is recycled for calcium removal from calcium chloride type brine, and the calcium chloride ammonia solution is recycled for ammonia and lower aliphatic alcohol recovery;

[0032] (4) Recovery and recycling of ammonia and alcohol, ammonia and lower aliphatic alcohol are recovered from the calcium chloride ammonia solution.

[0033] The process of the application can be further

[0034] The step (1) calcium chloride type includes lithium-containing brine of calcium chloride type, pre-concentrated brine after sodium removal of lithium-containing brine of calcium chloride type, and pre-concentrated brine after sodium and potassium removal of lithium-containing brine of calcium chloride type.

[0035] The step (3) ammonia concentration is 20-40%.

[0036] The step (3) calcium sulfate is a combination of one or more of anhydrous calcium sulfate, gypsum, phosphogypsum, monohydrate gypsum, and hemihydrate gypsum, and recycled gypsum.

[0037] The step (3) potassium chloride salt is a combination of one or more of potassium chloride, potassium salt, and other miscellaneous salts containing potassium chloride.

[0038] The step (3) potassium chloride or potassium salt and other miscellaneous salts containing potassium chloride is used in an amount of 1.0-1.5 times the chemical equivalent.

[0039] The step (3) lower aliphatic alcohol is a combination of one or more of ethanol, propanol, butanol, and pentanol, and the concentration of lower aliphatic alcohol is 2-15%.

[0040] The step (3) reaction temperature is 5-35°C, reaction pressure is normal pressure-0.2 MPa, and the reaction time is 20-50 min.

[0041] The step (4) uses conventional techniques such as distillation and stripping to recover ammonia and lower aliphatic alcohol.

[0042] Example 1

[0043] The calcium chloride type lithium-containing brine contains Ca 2+ 3.26%, Na + 6.21%, K + 0.66%, Li + 0.07%, Cl - 16.74%, SO4 2- 0.02%, H3BO3 0.56%, the following steps and conditions are implemented:

[0044] Step 1: add a chemical equivalent of potassium sulfate and stir for 60 min.

[0045] Step 2: directly perform solid-liquid separation on the brine after reaction, pump the decalcified brine to an evaporation pool for further sodium and potassium removal, and finally obtain concentrated brine, which is further purified in a processing plant to obtain purified high-lithium brine for producing battery-grade lithium carbonate, lithium hydroxide, and other products.

[0046] Step 3: The gypsum and potassium chloride salt obtained from the solid-liquid separation in the previous step were added into 40% ammonia water solution in a chemical equivalent of 1:1, with an isopropanol concentration of 3%, and reacted at normal pressure and 5°C for 50 min, followed by solid-liquid separation, to obtain potassium sulfate crystals and calcium chloride ammonia water solution. The potassium sulfate crystals were washed and reused in Step 1.

[0047] Step 4: The calcium chloride + sodium chloride ammonia water solution obtained above was recovered by distillation to recover ammonia and isopropanol, and the remaining calcium chloride + sodium chloride solution was discharged after treatment and detection. Ammonia and isopropanol were reused in Step 3. The specific process flow is shown in Figure 1

[0048] Example 2

[0049] Calcium chloride type lithium-containing brine Ca 2+ 3.26%, Na + 6.21%, K + 0.66%, Li + 0.07%, Cl - 16.74%, SO4 2- 0.02%, H3BO3 0.56%, the following steps and conditions are implemented:

[0050] Step 1: A chemical equivalent of potassium sulfate was added and stirred for 20 min, and then transferred to an evaporation tank for evaporation to remove sodium and potassium. Finally, concentrated brine was obtained, which was further purified in a processing plant to obtain purified high-lithium brine for the production of battery-grade lithium carbonate, lithium hydroxide, and other products.

[0051] Step 2: The salt in the sodium removal evaporation tank was collected at regular intervals, crushed, slurried, and separated by a shaker to separate gypsum and salt. Then, the gypsum and salt were recovered by solid-liquid separation. The salt was stacked in a salt yard, and the gypsum was used to prepare potassium sulfate in the next step. The filtrate was reused in the slurry preparation step.

[0052] Step 3: The gypsum and potassium salt obtained from the solid-liquid separation in the previous step were added into 40% ammonia water solution in a chemical equivalent of 1:1, with an isopropanol concentration of 3%, and reacted at normal pressure and 5°C for 50 min, followed by solid-liquid separation, to obtain potassium sulfate crystals and calcium chloride ammonia water solution. The potassium sulfate crystals were washed and reused in Step 1.

[0053] Step 4: The calcium chloride + sodium chloride ammonia water solution obtained above was recovered by distillation to recover ammonia and isopropanol, and the remaining calcium chloride + sodium chloride solution was discharged after treatment and detection. Ammonia and isopropanol were reused in Step 3. The specific process flow is shown in Figure 2

[0054] Example 3

[0055] Calcium chloride type lithium-containing brine hanCa 2+ ​​3.26%, Mg 0.13%, Na + 6.21%, K + 0.66%, Li + 0.07%, Cl - 16.74%, SO4 2- 0.02%, H3BO30.56%, the following steps and conditions are implemented:

[0056] Step 1: first sodium removal in the evaporation pond, to get saturated pre-concentration of potassium chloride brine (Ca 2+ 10.05%, Mg 0.41%, Na + 0.75%, K + 1.75%, Li + 0.23%, Cl - 22.99%, SO4 2- 0.00%, H3BO31.74%), add a stoichiometric amount of potassium sulfate and stir for 20 minutes, then transport to the evaporation pond for evaporation and potassium removal, finally get concentrated brine, after further impurity removal in the processing plant, get purified high lithium brine for producing battery-grade lithium carbonate, lithium hydroxide and other products.

[0057] Step 2: collect the salt in the potassium removal evaporation pond at regular intervals, crush, pulp, separate gypsum and halite with hydrocyclone, then recover gypsum and halite by solid-liquid separation, potassium halite is stacked in the potassium halite yard for step 3 or potassium chloride recovery, gypsum is used for the next step to prepare potassium sulfate, and the filtrate is returned to the above pulping step.

[0058] Step 3: add the gypsum and potassium halite obtained by solid-liquid separation in the above step to 20% ammonia solution in a stoichiometric amount of 1:1.3, where the butanol concentration is 7%, react at 0.2 MPa and 35°C for 40 minutes, then solid-liquid separation to get potassium sulfate crystals and calcium chloride + sodium chloride ammonia solution. The potassium sulfate crystals are washed and returned to step 1.

[0059] Step 4: recover ammonia and butanol from the above calcium chloride + sodium chloride ammonia solution by distillation, the remaining calcium chloride + sodium chloride solution is discharged after treatment and detection, ammonia and butanol are reused in step 3, the specific process flow is shown in Figure 3 .

[0060] Example 4

[0061] Calcium chloride type lithium-containing brine contains Ca 2+ 3.26%, Mg 0.13%, Na + 6.21%, K + 0.66%, Li + 0.07%, Cl - 16.74%, SO42- 0.02%, H3BO30.56%, the following steps and conditions are implemented:

[0062] Step 1: first, sodium and potassium are removed in an evaporation pond to obtain saturated pre-concentrated brine (Ca 2+ 12.50%, Mg0.51%, Na + 0.30%, K + 1.54%, Li + 0.29%, Cl - 26.99%, SO4 2- 0.00%, H3BO32.14%), a stoichiometric amount of potassium sulfate is added and stirred for 20 minutes, then transported to an evaporation pond for potassium removal by evaporation, and finally concentrated brine is obtained, which is further purified in a processing plant to obtain purified high-lithium brine for producing battery-grade lithium carbonate, lithium hydroxide and other products.

[0063] Step 2: collect the salt in the potassium removal evaporation pond at regular intervals, crush it, make a slurry, separate the gypsum and halite with a hydrocyclone, then perform solid-liquid separation to recover the gypsum and halite, the potassium halite is stacked in a potassium halite yard for use in Step 3 or to recover potassium chloride, the gypsum is used to prepare potassium sulfate in the next step, and the filtrate is returned to the slurry-making step.

[0064] Step 3: the gypsum and potassium halite obtained by solid-liquid separation in the previous step are added to a 40% ammonia solution in a stoichiometric ratio of 1:1.4, the concentration of amyl alcohol in the solution is 2%, the reaction is carried out at 0.2 MPa and 35°C for 20 minutes, then solid-liquid separation is performed to obtain potassium sulfate crystals and calcium chloride + sodium chloride ammonia solution. The potassium sulfate crystals are washed and returned to Step 1.

[0065] Step 4: the calcium chloride + sodium chloride ammonia solution obtained in the above step is distilled to recover ammonia and amyl alcohol, the remaining calcium chloride + sodium chloride solution is treated and detected to meet the discharge standard, and the ammonia and amyl alcohol are returned to Step 3. The specific process flow is shown in Figure 4 .

[0066] As described above, the present application can be well implemented. The above examples are only the best embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and other changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are all equivalent replacement methods, which are all included in the protection scope of the present application.

Claims

1. A method for decalcification of a calcium chloride type lithium-containing brine, characterized in that The specific process steps and conditions are as follows: (1) Decalcification with brine, mixing and stirring calcium chloride type lithium-containing brine with potassium sulfate for 10-60 min, discharging into a solar pond for evaporation, and naturally settling or directly performing solid-liquid separation of calcium sulfate solid, and using the decalcified brine for subsequent continuous impurity removal and lithium recovery; the amount of calcium chloride type lithium-containing brine is 0.9-1.1 times the chemical equivalent of potassium sulfate; (2) Calcium sulfate recovery, recovering the naturally settled calcium sulfate by salt mining, if the calcium sulfate is mixed with halite or sylvite, first crushing, then pulping, and then separating the calcium sulfate from the halite or sylvite using a shaker or hydrocyclone, and performing solid-liquid separation on the calcium sulfate slurry, and using the recovered calcium sulfate for the preparation of potassium sulfate, and the filtrate is reused for pulping; if the calcium sulfate is not mixed with halite or sylvite, the calcium sulfate is recovered after removing free water for the preparation of potassium sulfate; (3) Preparation of potassium sulfate, using the solubility difference of salt in different solutions, using ammonia water and lower aliphatic alcohol as solvent, and using potassium chloride or sylvite to react with calcium sulfate to generate potassium sulfate solid and calcium chloride ammonia solution, the amount of potassium chloride or sylvite is 1.0-1.5 times the chemical equivalent of calcium sulfate, the reaction temperature is 5-35℃, the reaction pressure is normal pressure-0.2 MPa, and the reaction time is 20-50 min, then the potassium sulfate is separated from the calcium chloride ammonia solution by solid-liquid separation, the potassium sulfate is recycled for calcium removal from calcium chloride type brine, and the calcium chloride ammonia solution is recycled for ammonia and lower aliphatic alcohol recovery; (4) Recovery and recycling of ammonia and alcohol, recovering ammonia and lower aliphatic alcohol from the calcium chloride ammonia solution.

2. The method of decalcification according to claim 1, wherein said Step (1) The calcium chloride type lithium-containing brine is calcium chloride type lithium-containing brine or pre-concentrated brine after sodium removal from calcium chloride type lithium-containing brine.

3. The method of claim 1 wherein The ammonia water concentration in step (3) is 20-40%.

4. The method of decalcification according to claim 1 or 3, characterized in that The lower aliphatic alcohol in step (3) is a combination of one or more of ethanol, propanol, butanol, and pentanol, and the concentration of the lower aliphatic alcohol is 2-15%.

5. The method of claim 1 wherein The step (4) uses distillation and stripping technology to recover ammonia and lower aliphatic alcohol.

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