Method for deeply removing fluorine in zinc sulfate solution and application thereof

Abstract

The application discloses a method for deeply removing fluorine in zinc sulfate solution, which comprises the following specific steps: (1) adding aluminum sulfate into the pre-neutralized zinc sulfate solution to perform pre-defluorination, and then performing liquid-solid separation to obtain defluorinated solution; (2) sequentially adding calcine and slaked lime into the defluorinated solution, and then performing liquid-solid separation. The method does not change the main process route, only adds aluminum sulfate particles into the pre-neutralized solution, and outputs defluorination slag by pressure filtration to open a channel, and the fluorine in the solution is removed by the aid of 10% iron ions in the process, the process adjustment does not need additional investment, and the original matching equipment and facilities can completely realize the removal of fluorine in the solution, the economic cost of the method is less than that of defluorination by a defluorination agent, the defluorination rate is high, the pre-removal of aluminum sulfate reaches 60%, the deep removal of fluorine by colloidal iron is realized, and the total fluorine removal rate reaches more than 90%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, in particular to a method for deeply removing fluorine in zinc sulfate solution and application thereof. BACKGROUND

[0002] Currently, the full wet smelting technology is usually used in the prior art for zinc smelting. After the zinc concentrate is leached by the high-acid spent electrolyte, the solution contains 3-5 g / L of acid. The calcine is neutralized. The zinc concentrate contains 0.02-0.05% of fluorine, and the calcine contains 0.01%-0.07% of fluorine. After leaching, all the fluorine enters the solution. The fluorine in the solution is continuously enriched. When the fluorine in the solution reaches 150 g / L or more, it is difficult to strip the cathode zinc sheet after zinc electrolysis due to the high fluorine concentration in the solution, and the current efficiency is reduced. Therefore, effective measures must be taken to remove the fluorine in the zinc sulfate solution.

[0003] Therefore, it is a technical problem to be solved in the field to provide a method for deeply removing fluorine in zinc sulfate solution with low cost and high fluorine removal rate. SUMMARY

[0004] The present application aims to provide a method for deeply removing fluorine in zinc sulfate solution and application thereof. The method does not affect the main process of zinc smelting production. Aluminum sulfate is added to the production process to remove fluorine by the iron precipitation process.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] A method for deeply removing fluorine in zinc sulfate solution, comprising the following specific steps:

[0007] (1) adding aluminum sulfate to the pre-neutralized zinc sulfate solution for pre-fluorine removal, and separating the liquid and solid to obtain the defluorinated solution;

[0008] (2) adding the defluorinated solution to the calcine and slaked lime in sequence, and then separating the liquid and solid.

[0009] The technical process of the present application is to add zinc sulfide concentrate to the spent electrolyte to produce zinc sulfate solution by two-stage pressurized leaching. The zinc sulfate solution contains 3-5 g / L of acid. After neutralization of the zinc oxide dust to pH 4.0-4.5, 20 g / L of solid aluminum sulfate particles are added for pre-fluorine removal. The removal rate of pre-fluorine removal reaches more than 60%. After the addition of aluminum sulfate to the solution, aluminum sulfate is hydrolyzed to produce [Al(H2O)6] 3+ , [Al(OH)·(H2O)5] 2+ , [Al2(OH)2·(H2O)8] 4+ , [Al3(OH)5·(H2O)9] 4+ , [Al3(OH)4] 5+ , [Al7(OH)17 ] 4+ 、[Al 13 O4(OH) 17 ] 7+ Multiple high-valence cations, such as F, adsorb F in zinc sulfate solution through electrostatic interactions. - The hydrolysis product of aluminum sulfate, Al(OH)3, is a colloid with a large surface area, which can adsorb F. - And thus coexistence occurs, in addition to F in the solution - With the addition of Al 3+ A chemical reaction occurs to form a compound composed of elements F and Al, which contains positively charged aluminum ions. These ions have a strong charge neutralization and adsorption effect on fluoride ions, which have small ionic radii and strong negative charge. After the fluoride in the solution is neutralized, they collide with each other under Brownian motion and, due to their superior adsorption properties compared to aluminum hydroxide, they condense together to form a precipitate.

[0010] Adding aluminum sulfate to the defluorination solution lowers the pH to 3-3.5. Adding calcined sand and introducing oxygen adjusts the pH to 4.5-5.0. 90% of the iron is added to the first neutralization slag, producing a neutralized underflow that is returned to oxygen pressure leaching. Then, limestone is added to adjust the pH to 5.0-5.2, and 10% of the iron is added to the slag in colloidal form. At the same time, the fluorine in the solution is added to the iron slag, achieving deep removal of fluorine from the solution. This part of the fluorine-containing iron slag is piled up in the slag yard. Through aluminum sulfate pre-removal + iron slag defluorination, the fluorine in the solution is reduced from 145 mg / L to 12 mg / L. The method of this invention does not change the main process route. It simply adds aluminum sulfate particles after the original pre-neutralization liquid, and uses pressure filtration to produce defluorination residue. At the same time, it uses 10% iron ions in the process to produce colloidal particles for secondary removal of fluoride from the solution. The process adjustment does not require additional investment. The existing supporting equipment and facilities can fully achieve the removal of fluoride from the solution. The economic cost of the method of this invention is less than that of defluorination with defluorinating agents, and the defluorination rate is high. The pre-removal of fluoride by aluminum sulfate reaches 60%, and the colloidal iron removes fluoride deeply, with a total fluoride removal rate of over 90%.

[0011] Preferably, the pH value of the zinc sulfate solution in step (1) is 4.0-4.5.

[0012] Preferably, the pre-neutralization uses zinc oxide dust.

[0013] Since zinc sulfate solution contains 3-10 g / L of acid, the acid should be neutralized to a pH of 4.0-4.5 before aluminum sulfate is added for defluorination. The main component of zinc oxide dust is zinc oxide, so adding acid to neutralize the zinc oxide dust can not only effectively leach zinc from the zinc oxide dust but also prevent other metal impurities from entering the zinc sulfate solution.

[0014] Preferably, the mass-to-volume ratio of aluminum sulfate and zinc sulfate in step (1) is 20 g / L.

[0015] The pH value of the neutralized zinc oxide fume zinc sulfate solution is controlled in the range of 4.0-4.5, solid aluminum sulfate (mass / volume ratio of 20 g / L) is added, F ion is a common ligand, F- can form complex with Al 3+ The complex is mixed in the hydrolysis product Al(OH)3 of aluminum sulfate, and is separated to produce defluorinated solution and fluorine-containing residue, and the fluorine ion removal rate in the zinc sulfate solution is more than 60%.

[0016] Preferably, the adding amount of the calcine in step (2) is to pH 4.5-5.0.

[0017] The pH value of the aluminum sulfate defluorinated solution is reduced to 3.0-3.5, the iron content is 2-5 g / L, the pH value is neutralized to 4.5-5.0 by calcine, oxygen 99.5% is introduced to realize the iron in the form of goethite to be precipitated in the residue, a neutralized bottom stream and a neutralized solution are formed, the iron content in the neutralized solution is controlled to be 30 mg / L-50 mg / L (the iron ion is further removed in the form of colloidal iron), and the neutralized bottom stream is returned to the oxygen pressure leaching for further recovery of zinc in the neutralized bottom stream.

[0018] Preferably, the adding amount of the slaked lime in step (2) is to pH 5.0-5.2.

[0019] The iron content in the neutralized solution is 30 mg / L-50 mg / L, the pH value is 4.5-5.0, the pH value is adjusted to 5.0-5.2 by slaked lime, the iron content in the solution is reduced to below 20 mg / L, the iron ion is precipitated in the form of colloidal iron, the adsorption of the colloidal iron makes the F and Ca ions in the solution coagulate to form a precipitate to realize secondary removal of fluorine in the solution, and the fluorine ion removal rate in the zinc sulfate solution is more than 90%.

[0020] The method for deeply removing fluorine in the zinc sulfate solution is applied to hydrometallurgy.

[0021] Compared with the prior art, the method has the following beneficial effects:

[0022] 1. The fluorine removal rate of the method is high, which can reach more than 90%, and the fluorine content in the solution is reduced to below 15 mg / L, so that the problem of difficult stripping of zinc sheet due to high fluorine in the electrolysis process is eliminated.

[0023] 2. The method produces less defluorinated residue, and the fluorine residue is 1.9 kg / m 3 , and the loss of zinc metal is small.

[0024] 3. The reaction time of the method is relatively short, and the effective removal of fluorine can be realized in 30-45 min.

[0025] 4. The method of the present application does not change the main process flow, and the reagent is added to the main process flow to experimentally remove fluorine effectively. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced, and the drawings in the description are only embodiments of the present application.

[0027] Figure 1 A process flow chart of the method for deeply removing fluorine from zinc sulfate solution according to the present application;

[0028] Figure 2 A state diagram of the filtered solution obtained after different reaction times of the pre-neutralized supernatant according to the present application;

[0029] Figure 3 A state diagram of the pre-neutralized supernatant according to the present application;

[0030] Figure 4 A state diagram of the pre-neutralized supernatant after adding 20 g of aluminum sulfate according to the present application. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described below, and the examples of the embodiments are shown in the drawings. The embodiments described with reference to the drawings are exemplary and are intended to explain the present application, and are not understood as limiting the present application.

[0032] Example 1

[0033] As Figure 1 A method for deeply removing fluorine from zinc sulfate solution, specifically comprising the following steps:

[0034] Take 3 L of zinc sulfate solution after two-stage oxygen pressure leaching of zinc sulfate concentrate, the zinc sulfate solution contains 4 g / l of acid and 146.8 mg / l of fluorine, add 38 g of zinc oxide dust, control the end point pH value at 4.5, and take the pre-neutralized supernatant after liquid-solid separation, the pre-neutralized supernatant contains 145.5 mg / l of fluorine, add 20 g / L of aluminum sulfate in the pre-neutralized supernatant, and separate the liquid and solid after 30 min of reaction, the solution contains 54.65 mg / l of fluorine, and the defluorination residue is 1.86 kg / m 3 After the calcine is neutralized to pH 4.8, liquid-solid separation is performed, lime is added to the neutralized liquid to adjust the pH to 5.1 for secondary neutralization, the lime is added at a dosage of 2 g / l, and the neutralized liquid and iron residue are produced after liquid-solid separation, the fluorine in the solution is reduced to 10.85 mg / l, and the total removal rate reaches 91.8%.

[0035] Example 2

[0036] As Figure 1A method for deeply removing fluorine from a zinc sulfate solution, specifically comprising the following steps:

[0037] Take 4L of zinc sulfate solution after two-stage oxygen pressure leaching of zinc sulfate concentrate, the zinc sulfate solution contains 7g / l of acid and 139.2mg / l of fluorine, add 50g of zinc oxide dust, control the end point pH value at 4.2, carry out liquid-solid separation, take the supernatant of pre-neutralization, the supernatant of pre-neutralization contains 137.35mg / l of fluorine, add 20g / L of aluminum sulfate according to the supernatant of pre-neutralization, carry out liquid-solid separation after 30min of reaction, the solution contains 52.25mg / l of fluorine, and the defluorination residue is 1.88kg / m 3 After the pre-neutralization, add slaked lime to adjust the pH value to 5.0 to carry out secondary neutralization, add 2g / l of slaked lime, carry out liquid-solid separation to obtain the neutralized solution and iron residue, the fluorine in the solution is reduced to 12.6mg / l, and the total removal rate reaches 90.83%.

[0038] Example 3

[0039] As Figure 1 A method for deeply removing fluorine from a zinc sulfate solution, specifically comprising the following steps:

[0040] Take 4L of zinc sulfate solution after two-stage oxygen pressure leaching of zinc sulfate concentrate, the zinc sulfate solution contains 7g / l of acid and 139.2mg / l of fluorine, add 50g of zinc oxide dust, control the end point pH value at 4.2, carry out liquid-solid separation, take the supernatant of pre-neutralization, the supernatant of pre-neutralization contains 137.35mg / l of fluorine, add 20g / L of aluminum sulfate according to the supernatant of pre-neutralization, carry out liquid-solid separation after 30min of reaction, the solution contains 52.25mg / l of fluorine, and the defluorination residue is 1.88kg / m 3 After the pre-neutralization, add slaked lime to adjust the pH value to 5.0 to carry out secondary neutralization, add 2g / l of slaked lime, carry out liquid-solid separation to obtain the neutralized solution and iron residue, the fluorine in the solution is reduced to 12.6mg / l, and the total removal rate reaches 90.83%.

[0041] Explore the aluminum sulfate defluorination time and dosage

[0042] 1. Aluminum sulfate defluorination time condition test

[0043] Take 6 cups of pre-neutralization supernatant in the production process, each cup is 1L, add 20g of aluminum sulfate solid particles, respectively, stir for 30min, 45min, 60min, 75min, 90min and 105min, then filter the solution, take samples for analysis, and the experimental results are shown in Table 1 and Figure 2 :

[0044] Table 1 Aluminum sulfate defluorination time condition test data table

[0045]

[0046]

[0047] Figure 2 The filtrate solutions obtained after the reaction of the pre-neutralized supernatant at different times are shown from left to right as follows: filtrate obtained after 0 min, 30 min, 45 min, 60 min, 75 min, 90 min, and 105 min of reaction, respectively. Figure 2 As can be seen from Table 1 and Table 2, after the addition of 20 g of aluminum sulfate solid particles to the pre-neutralized supernatant, there is a very small increase with the extension of time, and the fluorine removal rate reaches 57.86% at 45 min of reaction, and 60.02% at 60 min of reaction. Thereafter, the fluorine removal rate decreases with the extension of time, and thus the operation time of 45 min is more appropriate for the production process.

[0048] 2. Test of the amount of aluminum sulfate used after pre-neutralization

[0049] The pre-neutralized supernatant was obtained by adding 72 g of zinc oxide fume to 4 L of zinc sulfate solution obtained after two-stage oxygen pressure leaching, and controlling the pH value at the acid neutralization end point to 4.5. The pre-neutralized supernatant was poured into 5 2L cups, each containing 1 L of the pre-neutralized supernatant, and tests of different amounts of aluminum sulfate were performed. The reaction time was controlled at 45 min, and after the end of the experiment, liquid-solid separation was performed, and the samples were analyzed. The test results are shown in Table 2 and Table 3. Figures 3-4

[0050] Table 2: Test data of the effect of the amount of aluminum sulfate added on fluorine removal

[0051] Sample name F (mg / 1) Liquid F removal rate (%) Pre-neutralized supernatant 140.75 0 3 g aluminum sulfate 112.75 22.51 20 g aluminum sulfate 54.65 62.44 25 g aluminum sulfate 67.55 52.96 30 g aluminum sulfate 55.7 61.21 35 g aluminum sulfate 54 62.40

[0052] Figure 3 The state diagram of the pre-neutralized supernatant is shown in Figure 1. Figure 4 The state diagram of the pre-neutralized supernatant after the addition of 20 g of aluminum sulfate is shown in Figure 2, and the state diagram of the pre-neutralized supernatant after the addition of 20 g of aluminum sulfate and 45 min of reaction is shown in Figure 3. Figures 3-4 As can be seen from Table 2 and Table 3, the pre-neutralized slurry after the addition of zinc oxide fume is very difficult to filter. After the addition of aluminum sulfate, the color of the pre-neutralized supernatant changes from yellow to light green, and there is almost no obvious residue in the solution. The pH value of the solution continuously decreases with the extension of reaction time, and finally decreases to pH = 3. The fluorine removal rate in the solution continuously increases with the addition of aluminum sulfate, and the fluorine removal rate in the solution reaches more than 60% when the amount of aluminum sulfate added is 20 g / L. There is no increasing trend in fluorine removal with the further increase of the amount of aluminum sulfate, and thus the addition of 20 g / L of aluminum sulfate is more appropriate.

[0053] 3. Comparison between fluorine removal by the addition of aluminum sulfate and fluorine removal by the addition of lime to the second neutralized solution ​

[0054] Take the zinc sulfate concentrate by two-stage oxygen pressure leaching of zinc sulfate solution 3L, containing acid 7g / l, containing fluorine 135.25, add zinc oxide dust 50g, the end point pH value control at 4.3, after liquid-solid separation, take the pre-neutralization supernatant, inject the pre-neutralization supernatant into 2L cup 4, add aluminum sulfate 20g / L respectively, react for 45min, after the experiment, liquid-solid separation, the liquid is neutralized to pH 4.5-5.0 with calcine, while oxygen is passed in, after the reaction, liquid-solid separation, take the solution, add lime to pH 5.0-5.2, carry out liquid-solid separation, weigh the amount of slag, take the liquid sample for analysis, the test results are as follows in Table 3:

[0055] Table 3 Comparison of aluminum sulfate defluorination and aluminum sulfate + colloidal iron defluorination

[0056]

[0057] As can be seen from Table 3, the removal rate of fluorine is about 60% when using aluminum sulfate alone for defluorination, and the removal rate of fluorine can be more than 90% when using aluminum sulfate + colloidal iron for defluorination, and the fluorine in the solution can be reduced from 135mg / l to less than 13.5mg / l.

[0058] As can be seen from the above, the fluorine removal rate of the method of the present application can be more than 90%, the fluorine in the solution can be reduced to less than 15mg / l, the reaction time is relatively short, and the effective removal of fluorine can be achieved within 30-45min reaction time.

[0059] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for deep removal of fluorine from a zinc sulfate solution, characterized in that, Comprise the following specific steps: (1) adding aluminum sulfate into the pre-neutralized zinc sulfate solution to pre-defluorinate, and obtaining a defluorinated solution after liquid-solid separation; the pre-neutralization uses zinc oxide fume, and the mass-volume ratio of the aluminum sulfate to the zinc sulfate solution is 20 g / L; wherein the zinc sulfate solution is produced by adding zinc sulfide concentrate into waste electrolyte through two-stage pressurized leaching; (2) neutralizing the defluorinated solution to pH 4.5-5.0 with calcine, and simultaneously passing in oxygen to form a neutralization underflow and a post-neutralization solution, controlling the iron content of the post-neutralization solution to be 30 mg / l-50 mg / l, then adding slaked lime into the post-neutralization solution to adjust the solution pH to 5.0-5.2, and producing a post-neutralization solution and iron residue after liquid-solid separation.

2. The method for deep removal of fluorine from zinc sulfate solution according to claim 1, characterized in that, The pH of the pre-neutralized zinc sulfate solution in step (1) is 4.0-4.

5.

3. Use of the method for deeply removing fluorine from a zinc sulfate solution according to any one of claims 1-2 in hydrometallurgy.

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