Method for removing iron and aluminum impurities in strong acid liquid

Abstract

The invention relates to a method for removing iron and aluminum impurities in strong acid liquid, and belongs to the field of hydrometallurgy and resource utilization. The method specifically comprises the following steps: adding manganese monoxide powder (MnO) into a strongly acidic aqueous solution containing iron and aluminum, and gradually adjusting the acidity of the system under a mild condition, so that iron and aluminum ions form insoluble precipitates; after solid-liquid separation and washing, the removal rate of iron and aluminum exceeds 90%, and the loss of target elements such as magnesium and lithium is small. According to the method, introduction of exogenous sodium salt is avoided, the ionic strength shielding effect caused by strong electrolyte such as NaCl is effectively avoided, a recessive chlorine salt buffer system is prevented from being formed, and it is ensured that pH adjustment is more flexible and controllable. The method is suitable for pretreatment processes of various acidic industrial liquids such as titanium slag water quenching liquid and lepidolite pickle liquor. The method has the advantages of low raw material cost, large precipitate particles, easiness in filtration, mild operation conditions and the like, and is suitable for industrial-scale application and popularization.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgy and industrial wastewater treatment technology, and particularly relates to a method for removing iron and aluminum impurities from strongly acidic liquids. Background Technology

[0002] The large amounts of acidic leachate generated during industrial extraction processes are typically rich in impurities such as iron and aluminum. These impurities not only affect the extraction efficiency of valuable metals like lithium and magnesium but also interfere with subsequent separation processes. Traditional neutralization and precipitation methods using lime, sodium hydroxide, or sodium carbonate suffer from poor selectivity, numerous byproducts, difficulty in filtration, and the introduction of sodium salts. Especially in strongly acidic systems, strong electrolytes like NaCl enhance the ionic strength of the solution, forming a buffer system that severely inhibits the sensitivity of pH adjustment. Therefore, it is essential to develop a highly efficient method for removing iron and aluminum that does not introduce sodium and allows for precise control of acidity and alkalinity without affecting the retention of lithium and magnesium. Summary of the Invention

[0003] The purpose of this invention is to provide a method for efficiently removing iron and aluminum impurities from a strongly acidic aqueous solution by adding manganese monoxide. This method involves the stepwise reaction of MnO to release OH-. - By adjusting the pH to 5.5-6.2 without introducing sodium, iron and aluminum ions are precipitated. Unexpectedly, this method has little effect on lithium and magnesium ions, and their retention rate in the solution is very high, which can completely remove iron and aluminum impurities from lithium and magnesium solutions.

[0004] In view of this, one objective of the present invention is to provide a method for removing iron and aluminum impurities from a strongly acidic liquid, wherein the strongly acidic liquid contains lithium and / or magnesium elements, and the pH of the strongly acidic liquid is 0-2. The method includes the following steps:

[0005] 1) Obtain a strongly acidic solution;

[0006] 2) Under normal temperature and stirring conditions, add MnO powder in batches to the strongly acidic solution, each batch being 0.1–1 g / 100 mL, with an interval of 10–30 minutes. The total amount of MnO added is 1–5 g / 100 mL, adjusting the pH to 5.5–6.2. The total amount of MnO added is negatively correlated with the pH of the wastewater (0–2).

[0007] 3) Allow the sediment to settle and perform solid-liquid separation. Wash the sediment and combine the filtrates, which have been free of iron and aluminum impurities.

[0008] Furthermore, the number of times the batches are added in step 2) is greater than or equal to 5.

[0009] Furthermore, the number of times the batches are added in step 2) is 5 to 8.

[0010] Furthermore, the interval is 10 or 20 minutes.

[0011] Furthermore, the strong acidic liquid is either the titanium tailings water quenching liquid from the titanium dioxide chlorination process or the lithium mica acid leaching liquid.

[0012] Furthermore, the elemental composition of the lithium mica acid leaching solution includes Al, Fe, Mn, Li, K, Na, Be, and Tl; the elemental composition of the titanium dioxide tailings water quenching solution includes Fe, Mg, Mn, Ca, Al, Na, and K.

[0013] The method of this invention achieves a Fe and Al removal rate of greater than 90% and a Li and / or Mg retention rate of greater than 80%, which can be used for subsequent high-value utilization.

[0014] The advantages of this invention are as follows:

[0015] This method avoids the introduction of traditional industrial alkalis, thus preventing ionic strength shielding caused by high-concentration sodium salts and ensuring pH sensitivity. It achieves high iron and aluminum removal rates (>90%) and high retention rates of high-value elements (Li, Mg). Furthermore, the large precipitate particles facilitate filtration and treatment, and the mild process conditions make it suitable for industrial-scale implementation. Attached Figure Description

[0016] Figure 1 This is a process phenomenon diagram of Embodiment 1 of the present invention;

[0017] Figure 2 The image shows the XRD pattern of the filter residue after iron and aluminum removal in Example 1 of this invention.

[0018] Figure 3 This diagram illustrates the source of titanium tailings generated during the titanium dioxide chlorination process of Panzhihua Iron and Steel Group in this invention.

[0019] Figure 4 This is a process phenomenon diagram of Comparative Example 3 of the present invention;

[0020] Figure 5 This is a graph showing the pH change during MnO2 impurity removal in Comparative Example 7 of this invention. Detailed Implementation

[0021] The present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of the present invention. The present invention is not limited to the following embodiments or examples. Any modifications and variations made without departing from the spirit of the present invention should be included within the scope of the present invention. Unless otherwise specified, the experimental materials or reagents used in the following embodiments are commercially available.

[0022] Example 1

[0023] A lepidolite acid leaching solution from a factory in Yichun, Jiangxi Province (obtained using an acid leaching process; due to its high impurity content, the solution requires impurity removal before lithium extraction) was taken. The pH was measured to be 1.6. The initial ion content of each ion in the acid leaching solution was determined by ICP-OES, as shown in Table 1. The total iron content was 534 ppm, the aluminum content was 6110 ppm, and the lithium content was 996 ppm. 100 mL of the acid leaching solution was placed in a beaker, and 1.6 g of solid MnO powder was added at room temperature at a rotation speed of 300 rpm. The addition method was to add 0.2 g in batches every 20 minutes, while monitoring the pH. The reaction was complete 20 minutes after the last addition of MnO, with a final pH of 5.84. After the reaction, the solution was vacuum filtered, washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The reaction process is as follows: Figure 1 As shown. The residual ion content in the filtrate was determined by ICP-OES, and the removal rates of iron and aluminum ions were calculated according to formula (1).

[0024]

[0025] In the formula, η is the ion removal rate; C0 is the concentration of each ion in the acid leaching solution before the reaction (mg / L); V0 is the volume of the acid leaching solution before the reaction (L); The concentration (mg / L) of each ion in the acid leaching solution after the reaction; The volume (L) of the filtrate after the reaction.

[0026] The lithium ion retention rate is calculated according to formula (2).

[0027]

[0028] In the formula, u is the ion retention rate; C0 is the concentration of each ion in the acid leaching solution before the reaction (mg / L); V0 is the volume of the acid leaching solution before the reaction (L); The concentration (mg / L) of each ion in the acid leaching solution after the reaction; The volume of the filtrate after the reaction (L).

[0029] The calculation results show that the Al removal rate is 99.92%, the Fe removal rate is 100%, and the Li retention rate is 86.66%. XRD results are as follows. Figure 2 As shown, the precipitate was amorphous according to XRD analysis, and XRF showed that it was rich in Fe, Al, Mn and S elements, suggesting that it was a mixed adsorbed state or a sulfate phase.

[0030] Table 1. Elemental composition of lithium mica acid leaching solution

[0031]

[0032] Example 2

[0033] Panzhihua Panzhihua Iron and Steel Group's titanium dioxide chlorination process, such as Figure 3 As shown, the first batch of water-quenched liquid from the titanium dioxide chlorination process (derived from a solid byproduct formed during chlorination in a chlorination furnace using titanium concentrate / titanium slag / rutile as titanium-containing raw materials and petroleum coke as a reducing agent, followed by water quenching) was taken. The pH was measured to be 0. The initial ion content of each ion in the wastewater was determined by ICP-OES, as shown in Table 2. The total iron content was 27400 ppm, the aluminum content was 200 ppm, and the magnesium content was 17260 ppm. 100 mL of the original wastewater sample was placed in a beaker, and the rotation speed was 300 rpm. MnO was added five times at room temperature at a rate of 1 g / 10 min (added in batches, 1 g MnO every 10 minutes, for a total of 5 g). After complete feeding, the system was reacted for another 20 min until complete. The final pH was measured to be 5.62. After the reaction, the mixture was vacuum filtered, washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The residual content of each ion in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation showed that the Al removal rate was 99.71%, the Fe removal rate was 95.56%, and the magnesium retention rate was 99.95%.

[0034] Table 2. Elemental composition of the first batch of water quenching solution

[0035]

[0036] Example 3

[0037] The second batch of water-quenched liquid from the titanium tailings of the titanium dioxide chlorination process at Panzhihua Iron and Steel Group (derived from a solid byproduct formed during the chlorination process in different sections of the titanium dioxide chlorination process, using titanium concentrate / titanium slag / rutile as titanium-containing raw materials and petroleum coke as a reducing agent, and then quenched in a chlorination furnace) was taken. The pH value was measured to be 1.22. The initial ion content of each ion in the wastewater was determined by ICP-OES, as shown in Table 3. The total iron content was 28954 ppm, the aluminum content was 106 ppm, and the magnesium content was 22677 ppm. 100 mL of the original wastewater sample was placed in a beaker and the reaction was carried out at 300 rpm. MnO was fed five times at 1 g / 10 min at room temperature. After complete feeding, the system was reacted for another 20 min until complete. The final pH was measured to be 5.65. After the reaction, the mixture was vacuum filtered, washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The residual content of each ion in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation showed that the Al removal rate was 99.7%, the Fe removal rate was 94.88%, and the magnesium retention rate was 99.99%.

[0038] Table 3. Elemental composition of the second batch of water quenching solution

[0039]

[0040] Comparative Example 1

[0041] The lepidolite acid leaching solution was the same as in Example 1. 100 mL of the acid leaching solution was placed in a beaker, and 1.6 g of MnO powder solid was added at room temperature at a rotation speed of 300 rpm. The reaction was allowed to proceed for 20 min. The final pH was measured to be 5.76. After the reaction, the solution was vacuum filtered (slowly), washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The residual ion content in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation results showed that the Al removal rate was 95.73%, the Fe removal rate was 93.70%, and the Li retention rate was 72.32%.

[0042] Comparative Example 2

[0043] The lepidolite acid leaching solution was the same as in Example 1. 100 mL of the acid leaching solution was placed in a beaker, and 30% NaOH solution was added dropwise at 300 rpm at room temperature. The pH was monitored during the reaction, and stabilized for 30 min, with a final pH of 5.92. After the reaction, vacuum filtration (slower process) and washing were performed. The filtrates were combined and their volume was measured using a graduated cylinder. The residual ion content in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation results showed that the Al removal rate was 99.91%, the Fe removal rate was 100%, and the Li retention rate was 67.23%.

[0044] Comparative Example 3

[0045] The titanium dioxide tailings quenching solution from the chlorinated titanium dioxide process was prepared similarly to that in Example 2. 100 mL of the original wastewater sample was placed in a beaker, and the reaction was carried out at 300 rpm. 5 g of MnO powder was added at room temperature in a single batch, and the reaction was allowed to proceed for 20 min. The final pH was measured to be 5.72. After the reaction, the mixture was vacuum filtered, washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The reaction process is as follows: Figure 4 As shown. The residual content of each ion in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation showed that the Al removal rate was 97.37%, the Fe removal rate was 60.2%, and the magnesium retention rate was 71.9%.

[0046] Comparative Example 4

[0047] The titanium tailings quenching solution from the titanium dioxide process was the same as in Example 2. 100 mL of the original wastewater sample was placed in a beaker and the rotation speed was 300 rpm. 5 mL of 30% NaOH was added dropwise at room temperature. The pH was monitored during the reaction and stabilized for 30 min, with a final pH of 5.90. After the reaction, vacuum filtration (extremely difficult) and washing were performed. The filtrates were combined and their volume was measured using a graduated cylinder. The residual content of each ion in the filtrate was determined using ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculations showed that the Al removal rate was 97.55%, the Fe removal rate was 93.14%, and the magnesium retention rate was 51.4%.

[0048] Comparative Example 5

[0049] The titanium tailings water quenching solution from different stages of the titanium dioxide chlorination process was the same as in Experiment 3. 100 ml of the original wastewater sample was placed in a beaker and the rotation speed was 300 rpm. 5 g of MnO powder solid was added at room temperature and the reaction was carried out for 20 min. The final pH was measured to be 5.72. After the reaction, the solution was vacuum filtered, washed, and the filtrates were combined and their volume was measured with a graduated cylinder. The residual content of each ion in the filtrate was determined by ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation showed that the Al removal rate was 97.54%, the Fe removal rate was 76.38%, and the magnesium retention rate was 82.62%.

[0050] Comparative Example 6

[0051] The titanium tailings quenched solution from different stages of the titanium dioxide chlorination process was the same as in Experiment 3. 100 ml of the original wastewater sample was placed in a beaker and rotated at 300 rpm. 30% NaOH solution was added dropwise at room temperature. The pH was monitored during the reaction and stabilized for 30 min, with the final pH being 5.9. After the reaction, the solution was vacuum filtered, washed, and the filtrates were combined and their volume was measured using a graduated cylinder. The residual content of each ion in the filtrate was determined using ICP-OES. The ion removal rate was calculated according to formula (1) in Example 1, and the ion retention rate was calculated according to formula (2). The calculation showed that the Al removal rate was 97.90%, the Fe removal rate was 94.61%, and the magnesium retention rate was 66.46%.

[0052] Comparative Example 7

[0053] The titanium tailings water quenching solution from different stages of the titanium dioxide chlorination process was the same as in Experiment 3, with a pH value of 1.22. The initial content of each ion in the wastewater was determined by ICP-OES, as detailed in Table 3. The total iron content was 28954 ppm, the aluminum content was 1106 ppm, and the magnesium content was 22677 ppm. 100 ml of the original wastewater sample was placed in a beaker, and the rotation speed was 300 rpm. MnO2 was fed four times at room temperature at a rate of 1 g / 10 min. The results are as follows... Figure 5As shown, the final pH was measured to be 1.19, and the pH of the system did not change significantly. Moreover, the precipitation conditions for iron and aluminum were not met at this pH. MnO2 was not effective in removing impurities from iron and aluminum and retaining high-value elements in a strong acid and high salt system.

[0054] The above embodiments demonstrate that the batch addition of manganese monoxide to a strongly acidic solution method provided in this invention can effectively remove iron and aluminum impurities, while maintaining high lithium and magnesium retention rates. Compared to traditional NaOH removal, it offers advantages such as easy filtration, low cost, and high selectivity, providing a good technical means for industrial wastewater treatment and high-value utilization.

[0055] The conventional techniques and solutions not described in detail in the above embodiments are all well known in the art, and therefore will not be elaborated upon here. The above embodiments and / or experimental examples describe the preferred embodiments of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for removing iron and aluminum impurities from a strongly acidic liquid, characterized in that, The strongly acidic solution contains lithium and / or magnesium, and the pH of the strongly acidic solution is 0-2. The method includes the following steps: 1) Obtain a strongly acidic solution; 2) Under normal temperature and stirring conditions, add MnO powder to the strongly acidic solution in batches, 0.1-1 g / 100 mL per batch, with an interval of 10-30 minutes. The total amount of MnO added is 1-5 g / 100 mL, so that the pH is adjusted to 5.5-6.

2. 3) Allow the sediment to settle and perform solid-liquid separation. Wash the sediment and combine the filtrates, which have been free of iron and aluminum impurities.

2. The method as described in claim 1, characterized in that, The number of times the batches are added in step 2) is greater than or equal to 5.

3. The method as described in claim 2, characterized in that, The number of times the product is added in batches as described in step 2) is 5 to 8.

4. The method as described in claim 1, characterized in that, The time interval mentioned in step 2) is 10 or 20 minutes.

5. The method as described in claim 1, characterized in that, The strong acidic liquid is any one of the following: lithium mica acid leaching solution and titanium dioxide tailings water quenching solution from the titanium dioxide chlorination process.

6. The method as described in claim 5, characterized in that, The elemental composition of the lithium mica acid leaching solution includes Al, Fe, Mn, Li, K, Na, Be, and Tl; the elemental composition of the titanium dioxide tailings water quenching solution in the titanium dioxide chlorination process includes Fe, Mg, Mn, Ca, Al, Na, and K.

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