Method for removing complex calcium in salting-out mother liquor generated in lithium extraction process of lepidolite ore

Abstract

The invention relates to the technical field of metallurgical impurity removal, in particular to a method for removing complex calcium in salt precipitation mother liquor generated in the lithium extraction process of lepidolite ore. The invention provides a method for removing complex calcium in a salt precipitation mother liquor generated in a lithium extraction process of lepidolite ore, which is characterized in that brine is obtained after the lepidolite is roasted and leached, the salt precipitation mother liquor containing the complex calcium is obtained after the brine is subjected to impurity removal, concentration, lithium precipitation and pressure filtrate decarburization concentration, and the complex calcium can be enriched in a system, so that the product quality can be influenced; therefore, the invention designs the method for removing the complex calcium in the salting-out mother liquor generated in the lithium extraction process of the lepidolite ore, which comprises the following steps: firstly, adjusting the salting-out mother liquor to be acidic, adding hydrogen peroxide for reaction and filtering, then adjusting the filtrate to be alkaline, adding sodium carbonate for reaction and filtering, and finally obtaining the complex calcium in the salting-out mother liquor. And finally preparing the salt precipitation mother liquor without the complex calcium.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical impurity removal, and in particular to a method for removing complex calcium in a salt precipitation mother liquor generated in a lithium extraction process of lepidolite ore. Background Art

[0002] Lithium is widely used in emerging fields such as battery industry, ceramic industry, glass industry, aluminum industry, lubricant, refrigerant, nuclear industry and optoelectronic industry. Among them, lithium hydroxide monohydrate and lithium carbonate are the two most important lithium compounds, and other industrial lithium products are basically downstream products of these two compounds.

[0003] The reserves of lithium mica ore in Yichun City, Jiangxi Province, are the largest in Asia, accounting for more than 30% of the country's lithium reserves. At present, except for a small amount of lithium extraction, most of the lithium mica ore is sold very cheaply to glass factories and ceramic factories as raw materials, and the lithium mica resources have not been fully utilized with high added value.

[0004] There are two main methods for smelting lithium metal in industry: one is to extract lithium from brine, enrich the lithium in the brine, and finally transform it into lithium salt products such as lithium hydroxide monohydrate, lithium carbonate, and lithium sulfate; the other method is to extract lithium from ore, which is mainly to treat the lithium-containing ore-spodumene and lithium mica by pyrometallurgy or hydrometallurgy to destroy its original gangue structure, so that the Li2O therein is dissolved in the form of soluble lithium salt, and lithium salts such as lithium hydroxide monohydrate, lithium carbonate, and lithium sulfate can be obtained. However, since most of the domestic salt lake brines have the characteristics of low magnesium-lithium ratio, the development is difficult, and the extraction of lithium from spodumene and lithium mica has the advantages of small material flow, high production efficiency, low energy consumption, and high lithium recovery rate. Therefore, the extraction of lithium from spodumene and lithium mica is currently a widely used method.

[0005] After calcination, lithium mica is leached to obtain brine, which is then removed from the salt mother liquor after impurities, concentrated, lithium precipitated (with the addition of EDTA) and decarbonized and concentrated by filtrate press. A certain amount of complexed calcium remains in the salt mother liquor, which will be enriched in the system, affecting product quality and affecting the salt separation of the centrifuge in the salt crystallization system. However, there is currently no method for removing the complexed calcium from the salt mother liquor. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for removing complex calcium from a salt precipitation mother liquor generated in a lithium extraction process of lepidolite ore in view of the deficiencies of the above-mentioned prior art. Since lepidolite is roasted and leached to obtain brine, a salt precipitation mother liquor containing complex calcium is obtained after impurity removal, concentration, lithium precipitation and filtrate decarbonization and concentration. The complex calcium will be enriched in the system, which will affect the product quality and affect the salt separation of a centrifuge in a salt precipitation crystallization system. Therefore, a method for removing complex calcium from a salt precipitation mother liquor generated in a lithium extraction process of lepidolite ore is designed. The salt precipitation mother liquor is first adjusted to be acidic, hydrogen peroxide is added for reaction and filtration, and then the filtrate is adjusted to be alkaline, and sodium carbonate is added for reaction and filtration, so as to finally prepare a salt precipitation mother liquor after the complex calcium is removed.

[0007] The present invention provides a method for removing complexed calcium in a salt precipitation mother liquor generated in a lithium extraction process of lepidolite ore, comprising the following steps:

[0008] S1, taking the salt mother solution, adding sulfuric acid thereto while stirring to adjust the pH value, to obtain a mixed solution 1;

[0009] S2, adding hydrogen peroxide to the mixed solution 1 prepared in S1, stirring sufficiently for reaction, and filtering to obtain a mixed solution 2;

[0010] S3, taking the mixed solution 2 prepared in S2, adding liquid alkali thereto while stirring, adjusting the pH value thereof, and filtering to obtain a mixed solution 3 after sufficient reaction;

[0011] S4, adding sodium carbonate to the mixed solution 3 prepared in S3 and stirring continuously, reacting fully at high temperature, and then filtering to obtain the salt precipitation mother liquor after removing the complexed calcium.

[0012] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the lithium extraction process of lepidolite ore provided by the present invention, the volume mass ratio of the salt precipitation mother liquor and sulfuric acid in S1 is 2L:17.5g, and the mass fraction of the sulfuric acid is 98%.

[0013] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the process of extracting lithium from lepidolite ore provided by the present invention, the initial pH value of the salt precipitation mother liquor in S1 is 8-9, and the pH value of the mixed solution 1 is 2.5-3.5.

[0014] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the lithium extraction process of lepidolite ore provided by the present invention, the volume mass ratio of the mixed solution 1 and the hydrogen peroxide in S2 is 1L:5g, the mass fraction of the hydrogen peroxide is 30%, and the time for fully stirring the reaction is 0.5h.

[0015] According to the method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore provided by the present invention, the volume mass ratio of the mixed solution 2 and the liquid alkali in S3 is 0.5L:12.5-13g, and the mass fraction of the liquid alkali is 30%.

[0016] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the process of extracting lithium from lepidolite ore provided by the present invention, the pH value in S3 is 11.5 to 13, and the sufficient reaction time is 15 to 30 minutes.

[0017] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the process of extracting lithium from lepidolite provided by the present invention, the mass ratio of the mixed solution 3 and sodium carbonate in S4 is 0.5kg:2g.

[0018] According to the method for removing complexed calcium in the salt precipitation mother liquor generated in the lithium extraction process of lepidolite ore provided by the present invention, the temperature of the high temperature sufficient reaction in S4 is 50-75° C., and the time of the high temperature sufficient reaction is 30-45 minutes.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The present invention provides a method for removing complex calcium in the salt mother liquor produced by the lithium extraction process of lepidolite ore, lepidolite is roasted, brine is obtained after leaching, and the salt mother liquor containing complex calcium is obtained after impurity removal, concentration, lithium precipitation (adding EDTA) and press filtrate decarbonization concentration, and the complex calcium is enriched in the system, which will affect the product quality and have an impact on the salt separation of the centrifuge of the salt crystallization system, so the salt mother liquor containing complex calcium is first adjusted to be acidic in the present invention, hydrogen peroxide is added to react and filter, and then the filtrate is adjusted to be alkaline, sodium carbonate is added to react and filter, and finally the salt mother liquor after removing the complex calcium is prepared. The efficiency of removing complex calcium in the salt mother liquor using the method provided by the present invention can reach up to 92.5%, and the content of calcium in the salt mother liquor after removing the complex calcium can be reduced to 0.03g / L at the lowest, which greatly reduces the content of impurity calcium in the salt brine. DETAILED DESCRIPTION

[0021] Example 1

[0022] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0023] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8-9, adding 17.5g of 98% sulfuric acid to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.5-3.5;

[0024] After calcination, lepidolite is leached to obtain brine, which is then removed from the mixture, concentrated, lithium precipitated (with EDTA added), and the filtrate is decarbonized and concentrated to obtain a salt precipitation mother liquor, wherein the calcium content of the salt precipitation mother liquor is 0.9 g / L.

[0025] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution A;

[0026] S3, take the mixed solution A prepared in 0.5LS2, add 12.5-13g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 11.5-13, react for 15-30 minutes, and filter to obtain a mixed solution 2;

[0027] S4, add 2g of sodium carbonate to the mixed solution 2 prepared in 0.5kg of S3 and stir continuously, heat to 50-75°C and react for 30-45min, and filter to obtain the salt precipitation mother solution 1 after removing the complexed calcium.

[0028] Comparative Example 1

[0029] This comparative example provides a method with a different reaction time of S2 hydrogen peroxide from that in Example 1, and the specific steps are as follows:

[0030] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8-9, adding 17.5g of 98% sulfuric acid to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.5-3.5;

[0031] After calcination, lepidolite is leached to obtain brine, which is then removed from the mixture, concentrated, lithium precipitated (with EDTA added), and the filtrate is decarbonized and concentrated to obtain a salt precipitation mother liquor, wherein the calcium content of the salt precipitation mother liquor is 0.9 g / L.

[0032] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 1 h, and filtering to obtain a mixed solution B;

[0033] S3, take 0.5LS2 prepared mixed solution B, add 12.5-13g of 30% liquid caustic soda while stirring, adjust the pH value to 11.5-13, react for 15-30 minutes, and filter to obtain mixed solution 2;

[0034] S4, add 2g of sodium carbonate to the mixed solution 2 prepared in 0.5kg of S3 and stir continuously, heat to 50-75°C and react for 30-45min, and filter to obtain the salt precipitation mother solution 2 after removing the complexed calcium.

[0035] Comparative Example 2

[0036] This comparative example provides a method with a different reaction time of S2 hydrogen peroxide from that in Example 1, and the specific steps are as follows:

[0037] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8-9, adding 17.5g of 98% sulfuric acid to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.5-3.5;

[0038] After calcination, lepidolite is leached to obtain brine, which is then removed from the mixture, concentrated, lithium precipitated (with EDTA added), and the filtrate is decarbonized and concentrated to obtain a salt precipitation mother liquor, wherein the calcium content of the salt precipitation mother liquor is 0.9 g / L.

[0039] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 1.5 h, and filtering to obtain a mixed solution C;

[0040] S3, take the mixed solution C prepared in 0.5LS2, add 12.5-13g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 11.5-13, react for 15-30 minutes, and filter to obtain a mixed solution 2;

[0041] S4, add 2g of sodium carbonate to the mixed solution 2 prepared in 0.5kg of S3 and stir continuously, heat to 50-75°C and react for 30-45min, and filter to obtain the salt precipitation mother solution 3 from which calcium has been removed.

[0042] Based on Example 1, Comparative Example 1 and Comparative Example 2, the calcium content in the final salt precipitation mother solutions 1, 2 and 3 after removing the complexed calcium was detected, and the results are shown in Table 1 below:

[0043] Table 1 Calcium content in salt mother liquor 1, 2 and 3

[0044] sample Initial Ca content Ca content after complexation Calcium removal efficiency Salt mother liquor 1 0.9g / L 0.17g / L 81.1％ Salt mother liquor 2 0.9g / L 0.32g / L 54.4％ Salt mother liquor 3 0.9g / L 0.29g / L 67.8％

[0045] It can be seen from the above table that when the reaction time of adding hydrogen peroxide to the mixed solution 1 is 0.5h, it is the best method for complexing calcium in the salt mother liquor.

[0046] Example 2

[0047] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0048] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8.5, adding 17.5g of 98% sulfuric acid with a mass fraction to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.35;

[0049] The calcium content in the raw material salt precipitation mother liquor in this embodiment is 0.58g / L;

[0050] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution 2;

[0051] S3, take the mixed solution 2 prepared in 0.5LS2, add 12.5 g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 12.05, react for 30 minutes, and filter to obtain a mixed solution 3;

[0052] S4, add 2 g of sodium carbonate to the mixed solution 3 prepared in 0.5 kg of S3 and stir continuously, heat to 50-75° C. and react for 45 min, and filter to obtain the salt precipitation mother solution 4 after removing the complexed calcium.

[0053] Example 3

[0054] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0055] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8.35, adding 17.5g of 98% sulfuric acid with a mass fraction to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.72;

[0056] The calcium content in the raw material salt precipitation mother liquor in this embodiment is 0.63g / L;

[0057] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution 2;

[0058] S3, take the mixed solution 2 prepared in 0.5LS2, add 12.5 g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 11.85, react for 30 minutes, and filter to obtain a mixed solution 3;

[0059] S4, add 2 g of sodium carbonate to the mixed solution 3 prepared in 0.5 kg of S3 and stir continuously, heat to 50-75° C. and react for 45 min, and filter to obtain the salt precipitation mother solution 5 after removing the complexed calcium.

[0060] Example 4

[0061] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0062] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8.3, adding 17.5g of 98% sulfuric acid with a mass fraction to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.38;

[0063] The calcium content in the raw material salt precipitation mother liquor in this embodiment is 0.58g / L;

[0064] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution 2;

[0065] S3, take the mixed solution 2 prepared in 0.5LS2, add 12.8 g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 12.51, react for 30 minutes, and filter to obtain a mixed solution 3;

[0066] S4, add 2 g of sodium carbonate to the mixed solution 3 prepared in 0.5 kg of S3 and stir continuously, heat to 50-75° C. and react for 45 min, and filter to obtain the salt precipitation mother solution 6 after removing the complexed calcium.

[0067] Example 5

[0068] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0069] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8.43, adding 17.5g of 98% sulfuric acid with a mass fraction to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.28;

[0070] In this embodiment, the calcium content in the raw material salt precipitation mother liquor is 0.4g / L;

[0071] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution 2;

[0072] S3, take the mixed solution 2 prepared in 0.5LS2, add 12.8 g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 12.15, react for 30 minutes, and filter to obtain a mixed solution 3;

[0073] S4, add 2 g of sodium carbonate to the mixed solution 3 prepared in 0.5 kg of S3 and stir continuously, heat to 50-75° C. and react for 45 min, and filter to obtain the salt precipitation mother solution 7 after removing the complexed calcium.

[0074] Example 6

[0075] This embodiment provides a method for removing complexed calcium from the salt precipitation mother liquor produced during the lithium extraction process of lepidolite ore:

[0076] S1, taking 2L of the salt precipitation mother liquor, and detecting the pH value of the salt precipitation mother liquor to be 8.5, adding 17.5g of 98% sulfuric acid with a mass fraction to the mother liquor while stirring to adjust the pH value, to obtain a mixed solution 1, and the pH value of the mixed solution 1 after adjustment is 2.08;

[0077] In this embodiment, the calcium content in the raw material salt precipitation mother liquor is 0.4g / L;

[0078] S2, adding 5 g of 30% hydrogen peroxide to the mixed solution 1 prepared in 1 L of S1, stirring and reacting for 0.5 h, and filtering to obtain a mixed solution 2;

[0079] S3, take the mixed solution 2 prepared in 0.5LS2, add 12.8 g of liquid caustic soda with a mass fraction of 30% while stirring, adjust the pH value to 12.59, react for 30 minutes, and filter to obtain a mixed solution 3;

[0080] S4, add 2 g of sodium carbonate to the mixed solution 3 prepared in 0.5 kg of S3 and stir continuously, heat to 50-75° C. and react for 45 min, and filter to obtain the salt precipitation mother solution 8 after removing the complexed calcium.

[0081] Based on the above examples 1 to 6, the calcium content in the salt precipitation mother solutions 1, 4, 5, 6, 7 and 8 after removing the complexed calcium was detected, and the results are shown in the following Table 2:

[0082] Table 2 Calcium content in salt precipitation mother liquor 1, 4, 5, 6, 7 and 8 after removing complex calcium

[0083] sample Initial Ca content Ca content after decalcification Calcium removal efficiency Salt mother liquor 1 0.9g / L 0.17g / L 81.1％ Salt mother liquor 4 0.58g / L 0.13g / L 77.6％ Salt mother liquor 5 0.63g / L 0.24g / L 61.9％ Salt mother liquor 6 0.58g / L 0.19g / L 67.2％ Salt mother liquor 7 0.4g / L 0.03g / L 92.5％ Salt mother liquor 8 0.4g / L 0.09g / L 77.5％

[0084] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for removing complexed calcium from salt precipitation mother liquor produced during lithium extraction from lepidolite ore, characterized in that: The following steps are involved: S1, taking the salt mother solution, adding sulfuric acid thereto while stirring to adjust the pH value, to obtain a mixed solution 1; S2, adding hydrogen peroxide to the mixed solution 1 prepared in S1, stirring sufficiently for reaction, and filtering to obtain a mixed solution 2; S3, taking the mixed solution 2 prepared in S2, adding liquid alkali thereto while stirring, adjusting the pH value thereof, and filtering to obtain a mixed solution 3 after sufficient reaction; S4, adding sodium carbonate to the mixed solution 3 prepared in S3 and stirring continuously, after sufficient reaction at high temperature, filtering to obtain the salt precipitation mother liquor after removing the complexed calcium.

2. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The volume mass ratio of the salt precipitation mother solution and sulfuric acid in S1 is 2L:17.5g, and the mass fraction of the sulfuric acid is 98%.

3. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The initial pH value of the salt precipitation mother solution in S1 is 8-9, and the pH value of the mixed solution 1 is 2.5-3.

5.

4. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The volume mass ratio of the mixed solution 1 and the hydrogen peroxide in S2 is 1L:5g, the mass fraction of the hydrogen peroxide is 30%, and the time for the sufficient stirring reaction is 0.5h.

5. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The volume mass ratio of the mixed solution 2 and the liquid caustic soda in S3 is 0.5L:12.5-13g, and the mass fraction of the liquid caustic soda is 30%.

6. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The pH value in S3 is 11.5 to 13, and the sufficient reaction time is 15 to 30 minutes.

7. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The mass ratio of the mixed solution 3 and sodium carbonate in S4 is 0.5kg:2g.

8. The method for removing complexed calcium in the salt precipitation mother liquor produced in the lithium extraction process of lepidolite ore according to claim 1, characterized in that: The temperature of the high temperature sufficient reaction in S4 is 50-75° C., and the time of the high temperature sufficient reaction is 30-45 minutes.