CN118563131A - New use of tannin in germanium precipitation process - Google Patents

Abstract

The invention discloses a new use of tannin in a germanium precipitation process and belongs to the technical field of hydrometallurgy. The invention uses a pollution-free oxidant to decompose Tara tannin in a sodium hydroxide solution and modify and activate small-molecule sodium tannate, and simultaneously performs low-temperature freezing desalination on a hydrometallurgical zinc-smelting germanium-containing solution, and then uses small-molecule sodium tannate to precipitate germanium from the desalted hydrometallurgical zinc-smelting germanium-containing solution to obtain tannic germanium with high germanium content. The invention decomposes macromolecular Tara tannin into small-molecule tannic acid, and further modifies and activates the tannin into sodium tannate, thereby effectively reducing the amount of tannin used in the tannin germanium precipitation process, greatly reducing the germanium recovery cost, and reducing the influence of organic matter on the hydrometallurgical zinc-smelting process.

Description

New use of tannin in germanium precipitation process

Technical Field

The invention relates to a new use of tannin in a germanium precipitation process, belonging to the technical field of hydrometallurgy.

Background Art

The main methods for recovering germanium from germanium-containing zinc leaching slag are pyrometallurgical reduction volatilization and wet high-temperature high-acid leaching. In addition, it also includes direct oxygen pressure leaching of germanium-containing zinc concentrate. For example, conventional zinc smelting process and fuming furnace volatilization of germanium-containing zinc oxide process are used, and zinc and germanium are leached from the germanium-containing zinc oxide dust; liquid sulfur dioxide reduction acid leaching method is used to leach germanium from zinc leaching slag, and the smelting process of zinc leaching slag is effectively recovered through sulfur dioxide high-pressure reduction leaching of zinc leaching slag; direct high-temperature acid leaching process of zinc sulfide concentrate is used to leach slag while leaching zinc. In general, the recovery of germanium in the zinc smelting process uses acid leaching process to dissolve germanium into wet zinc smelting solution, and then separate and enrich the germanium in the solution. Among them, the direct high-temperature acid leaching process uses zinc powder neutralization precipitation to separate and enrich germanium, the sulfur dioxide reduction acid leaching process uses lime neutralization precipitation to separate and enrich germanium, and the acid leaching solution of zinc oxide dust uses tannin to precipitate germanium. The zinc powder neutralization method easily produces arsenic in the solution, which requires precise protection; the lime neutralization method produces a large amount of gypsum, and the secondary leaching of gypsum easily causes the loss of germanium; the tannin precipitation germanium consumption is large, and the amount of tannin added is 25 times the amount of germanium or even higher.

At present, the recovery of germanium from zinc concentrate mainly adopts the process of fumigation volatilization of zinc oxide dust-acid leaching-tannin precipitation of germanium. This method has a high germanium recovery efficiency, but is also prone to chlorination and volatilization of germanium. In addition, due to the large consumption of tannin, the tannin germanium slag needs to be burned and removed by calcination process to remove tannin and other organic matter, which cannot be effectively recovered and reused in sequence, resulting in high germanium recovery costs. At the same time, the addition of a large amount of tannin increases the organic matter content of the hydrometallurgical zinc smelting system, which has an adverse effect on subsequent electrolysis.

Summary of the invention

The invention aims to reduce the amount of tannin used in the tannin germanium precipitation process, reduce the cost and reduce the influence of organic matter on the hydrometallurgical zinc smelting process. Aiming at the problem of separation and enrichment of germanium in a germanium-containing solution in hydrometallurgical zinc smelting, the invention provides a new method for using tannin in the germanium precipitation process. Tara tannin is decomposed and modified and activated into small-molecule sodium tannate in a sodium hydroxide solution by using a pollution-free oxidant. Meanwhile, the hydrometallurgical zinc smelting germanium-containing solution is subjected to low-temperature freezing desalination. Then, the desalted hydrometallurgical zinc smelting germanium-containing solution is subjected to tannin germanium precipitation by using the small-molecule sodium tannate to obtain germanium tannate with high germanium content, thereby effectively reducing the amount of tannin used in the tannin germanium precipitation process, reducing the germanium recovery cost and reducing the influence of organic matter on the hydrometallurgical zinc smelting process.

The technical solution of the present invention is as follows:

A new use of tannin in the germanium precipitation process is to convert tannin into small molecule sodium tannate and apply sodium tannate to the germanium precipitation process.

The specific steps of converting tannin into small molecule sodium tannate are as follows:

Tara tannin is dissolved in water with a mass of 8 to 10 times that of tannin at 50 to 60°C to obtain a tannin solution, a sodium hydroxide solution with a mass concentration of 10 to 15% is added to the tannin solution to adjust the pH to 6 to 8, and then a pollution-free oxidant is added and stirred to decompose the Tara tannin and modify and activate small molecule sodium tannate to obtain a sodium tannate solution, and the tannate solution is applied to the germanium precipitation process.

The pollution-free oxidant is hydrogen peroxide, and the added amount is 5-15% of the mass of tannin; the hydrogen peroxide is commercially available industrial hydrogen peroxide, wherein the mass fraction of hydrogen peroxide is 30%.

The stirring time is 40 to 60 minutes.

The sodium tannate is applied to the germanium precipitation process by adding the sodium tannate solution into the low-temperature freezing desalination wet zinc smelting germanium-containing solution, and stirring at 50-60° C. for 20-30 minutes to precipitate the germanium through tannin.

The germanium concentration in the germanium-containing solution of the hydrometallurgical zinc smelting is 30-300 mg/L.

The low-temperature freezing desalination is to freeze the germanium-containing solution of hydrometallurgical zinc smelting to below 0°C, crystallize sulfate and reduce the salt concentration of the germanium-containing solution of hydrometallurgical zinc smelting.

The mass of the sodium tannate is 10 to 13 times the mass of germanium in the germanium-containing solution of hydrometallurgical zinc smelting.

The beneficial effects of the present invention are:

(1) The present invention utilizes a pollution-free oxidant to decompose Tara tannin in a sodium hydroxide solution and modify and activate it into a small-molecule sodium tannate. First, the oxidant is used to decompose the macromolecular tannin into a small-molecule tannic acid to increase the number of hydroxyl and carboxyl groups that can be complexed and coordinated. Then, sodium hydroxide is used to modify it into a more active small-molecule sodium tannate, making it easier to precipitate with germanium.

(2) Compared with the germanium precipitation by tannic acid, the germanium is replaced by sodium ions instead of hydrogen ions in the present invention, which can effectively maintain the pH value of the solution and will not cause the pH value of the solution to decrease due to the precipitation reaction, resulting in a poor effect of germanium precipitation in the later stage of the reaction.

(3) The present invention modifies and activates tannin into small molecule sodium tannate. Compared with the traditional tannin germanium precipitation process, the amount of tannin can be reduced from 22 to 25 times to 13 to 15 times, thereby effectively reducing the amount of tannin germanium precipitation slag, so that the germanium in the germanium precipitation slag is better enriched. The quality of germanium in the slag is increased from 3 to 4% to more than 6 to 7% compared with the traditional process. At the same time, due to the reduction in the amount of tannin, the cost of germanium recovery can be greatly reduced, and the organic matter introduced into the solution due to the use of tannin is reduced, which is beneficial to reducing the organic matter content of the hydrometallurgical zinc smelting solution.

(4) The present invention utilizes low-temperature freezing desalination to reduce the salt concentration of the germanium-containing solution in the hydrometallurgical zinc smelting process, thereby making the solution system more conducive to the precipitation of germanium.

DETAILED DESCRIPTION

The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the above contents. The hydrogen peroxide used in the embodiments of the present invention is commercially available industrial hydrogen peroxide, wherein the mass fraction of hydrogen peroxide is 30%.

Example 1

(1) dissolving Tara tannin at 60° C. in water having a mass of 8 times that of Tara tannin to obtain a tannin solution, adding a 10% sodium hydroxide solution to the tannin solution to adjust the pH to 6.21, then adding a 10% hydrogen peroxide solution based on the mass of the tannin, stirring for 60 minutes, decomposing the Tara tannin and modifying and activating small molecule sodium tannate, and obtaining a sodium tannate solution;

(2) Using germanium-rich zinc oxide smoke leaching solution (Zn 141g/L, Mg 22g/L, Fe ³⁺ 0.012g/L, Fe ²⁺ 8.72g/L, Ge 37mg/L, pH 1.93) from a certain factory as raw material, the leaching solution was cooled to -5°C, and the crystallization of the frozen desalted sulfate was precipitated to reduce the salt concentration of the germanium-containing solution in the hydrometallurgical zinc smelting process;

(3) adding the sodium tannate solution of step (1) into the frozen desalted leachate of step (2), wherein the mass of sodium tannate in the sodium tannate solution is 13 times the mass of germanium in the leachate, and stirring at 55° C. for 30 minutes to precipitate germanium from tannin.

The precipitated slag in this example contains 6.13% germanium, and the concentration of liquid germanium after precipitation is 1.97 mg/L.

Example 2

(1) dissolving Tara tannin at 50° C. in water having a mass of 10 times that of Tara tannin to obtain a tannin solution, adding a 15% sodium hydroxide solution to the tannin solution to adjust the pH to 7.96, then adding a 15% hydrogen peroxide solution having a mass of 15% of that of the tannin, stirring for 40 minutes, decomposing the Tara tannin and modifying and activating small molecule sodium tannate, and obtaining a sodium tannate solution;

(2) Using germanium-rich zinc oxide smoke leaching solution (Zn 143g/L, Mg 21g/L, Fe ³⁺ 0.011g/L, Fe ²⁺ 8.16g/L, Ge 291mg/L, pH 1.72) from a certain factory as raw material, the leaching solution was cooled to -12°C, and the crystallization of the frozen desalted solution was precipitated to precipitate sulfate, so as to reduce the salt concentration of the germanium-containing solution in the hydrometallurgical zinc smelting process;

(3) adding the sodium tannate solution of step (1) into the frozen desalted leachate of step (2), wherein the mass of sodium tannate in the sodium tannate solution is 12 times the mass of germanium in the leachate, stirring at 60° C. for 20 min to precipitate germanium from tannin.

The precipitated slag in this embodiment contains 6.98% germanium, and the concentration of liquid germanium after precipitation is 2.51 mg/L.

Example 3

(1) dissolving Tara tannin at 55° C. in water having a mass of 9 times that of Tara tannin to obtain a tannin solution, adding a 10% sodium hydroxide solution to the tannin solution to adjust the pH to 7.12, then adding 5% hydrogen peroxide to the mass of the tannin, stirring for 50 minutes, decomposing the Tara tannin and modifying and activating small molecule sodium tannate, and obtaining a sodium tannate solution;

(2) Using germanium-rich zinc oxide smoke leaching solution (Zn 145g/L, Mg 18g/L, Fe ³⁺ 0.008g/L, Fe ²⁺ 9.92g/L, Ge 171mg/L, pH 1.63) from a certain factory as raw material, the leaching solution was cooled to -8°C, and the crystallization of the frozen desalted sulfate was precipitated to reduce the salt concentration of the germanium-containing solution in the hydrometallurgical zinc smelting process;

(3) adding the sodium tannate solution of step (1) into the frozen desalted leachate of step (2), wherein the mass of sodium tannate in the sodium tannate solution is 10 times the mass of germanium in the leachate, stirring at 50° C. for 25 minutes to precipitate germanium from tannin.

The precipitated slag in this embodiment contains 6.27% germanium, and the concentration of liquid germanium after precipitation is 2.36 mg/L.

Comparative Example 1

(1) Using germanium-rich zinc oxide smoke leaching solution (Zn 141g/L, Mg 22g/L, Fe ³⁺ 0.012g/L, Fe ²⁺ 8.72g/L, Ge 37mg/L, pH 1.93) from a certain factory as raw material, the leaching solution was cooled to -5°C, and the crystallization of the frozen desalted sulfate was precipitated to reduce the salt concentration of the germanium-containing solution in the hydrometallurgical zinc smelting process;

(2) Tara tannin is added to the frozen desalted leachate of step (1), the mass of tannin being 13 times the mass of germanium in the leachate, and the mixture is stirred at 55° C. for 30 min to precipitate germanium from the tannin. The precipitated residue contains 3.81% germanium, and the germanium concentration in the liquid after precipitation is 9.76 mg/L.

Comparative Example 2

(1) dissolving Tara tannin at 60° C. in water with an amount of 8 times the mass of tannin to obtain a tannin solution, adding a 10% sodium hydroxide solution to the tannin solution to adjust the pH to 6.21, then adding a 10% hydrogen peroxide solution with an amount of 10% of the mass of tannin, stirring for 60 minutes, decomposing Tara tannin and modifying and activating small molecule sodium tannate, and obtaining a sodium tannate solution;

(2) The raw material is the germanium-rich zinc oxide smoke leaching solution (Zn 141g/L, Mg 22g/L, Fe ³⁺ 0.012g/L, Fe ²⁺ 8.72g/L, Ge 37mg/L, pH 1.93) from a certain factory;

(3) adding the sodium tannate solution of step (1) to the leachate of step (2), wherein the mass of sodium tannate is 13 times the mass of germanium in the leachate, stirring at 55° C. for 30 min, and precipitating germanium from tannin, wherein the precipitated residue contains 5.29% germanium, and the concentration of liquid germanium after precipitation is 2.86 mg/L.

The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes made without departing from the spirit of the present invention are also included within the knowledge scope of ordinary technicians in the field.

Claims (6)

1. A new use of tannin in the germanium precipitation process: converting tannin into small molecule sodium tannate and applying sodium tannate to the germanium precipitation process. 2. The new method according to claim 1 is characterized in that the specific steps of converting tannin into small molecule sodium tannate are as follows: adding water to dissolve Tara tannin at 50-60°C to obtain a tannin solution, adjusting the pH of the tannin solution to 6-8, adding a pollution-free oxidant, and stirring to obtain a sodium tannate solution. 3. The new method of use according to claim 2 is characterized in that the pollution-free oxidant is hydrogen peroxide, and the added amount is 5 to 15% of the mass of Tara tannin. 4. The new method according to claim 2 is characterized in that the stirring time is 40 to 60 minutes. 5. The new method according to claim 1 is characterized in that the sodium tannate is applied to the germanium precipitation process by adding the sodium tannate solution to the low-temperature frozen desalted wet zinc smelting germanium-containing solution, stirring at 50-60° C. for 20-30 minutes to precipitate the germanium from the tannin. 6. The new method of use according to claim 5 is characterized in that the mass of the sodium tannate is 10 to 13 times the mass of germanium in the germanium-containing solution of hydrometallurgical zinc smelting.