A method for leaching germanium from zinc oxide dust

Abstract

The invention relates to a method for leaching germanium from secondary zinc oxide smoke, and belongs to the technical field of secondary zinc oxide smoke leaching. The invention uses three steps of leaching, wherein the first step of leaching is completed under low acid conditions, mainly completing the leaching of zinc oxide and germanium oxide, the second step of leaching increases the acidity, and simultaneously adds a dispersant to complete the leaching of lead oxide, germanium zinc oxide and germanium lead oxide, and the third step of leaching, while further increasing the acidity, adds an oxidant to complete the leaching of sulfide. The invention uses three steps of leaching under different conditions to increase the germanium leaching rate.

Description

Technical Field

[0001] The invention belongs to the technical field of leaching secondary zinc oxide dust, and in particular relates to a method for leaching germanium from secondary zinc oxide dust. Background Art

[0002] Germanium associated with zinc concentrate is concentrated in the acid leaching residue after the zinc concentrate is desulfurized by boiling roasting and leached by conventional zinc roasting method. After the acid leaching residue is reduced and volatilized by pyrometallurgical furnace, germanium is concentrated in the secondary zinc oxide dust. The main components of secondary zinc oxide dust are zinc and lead oxides and zinc sulfide. The germanium enriched in the secondary zinc oxide dust is GeO, GeO 2 、ZnO.GeO 2 、PbO.GeO 2 , GeS, GeS 2 Exist in other forms.

[0003] In the prior art, germanium is recovered from germanium-rich zinc oxide dust by using sulfuric acid as the leaching medium, subjecting the zinc oxide dust to a first-stage low-acid, second-stage medium-acid or high-acid leaching to allow zinc and germanium to enter the solution, and then recovering zinc and germanium from the solution.

[0004] When the prior art uses dilute sulfuric acid to leach zinc oxide dust, the lead oxide in the zinc oxide dust generates insoluble lead sulfate, which covers the lead oxide and PbO.GeO 2 The surface will form a coating, which will affect the leaching of germanium; and the sulfide of germanium will not react during acid leaching, thus affecting the leaching rate of germanium. Summary of the invention

[0005] In order to overcome the problems existing in the background technology, the present invention provides a method for leaching germanium from secondary zinc oxide smoke. The secondary zinc oxide smoke is leached in three steps, and the leaching conditions of each leaching step are controlled to avoid the influence of lead wrapping on the germanium leaching rate, and the leaching of sulfide is realized. The leaching of zinc oxide and germanium oxide is completed in the first leaching, the reaction of lead oxide to lead sulfate is completed in the second leaching, and the leaching of sulfide is completed in the third leaching. Through the control of the three leaching steps, the germanium leaching rate is effectively improved.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The method for leaching germanium from zinc oxide dust comprises the following steps:

[0008] (1) The first leaching process is to mix the secondary zinc oxide dust with acid solution for leaching.

[0009] (2) Second leaching: the bottom sulfur from the first leaching is subjected to the second leaching, and the leaching liquid is returned to the first leaching.

[0010] (3) The third leaching: the bottom flow of the second leaching is subjected to the third leaching, and the leachate is returned to the second leaching.

[0011] in,

[0012] During the second leaching, a dispersant is added to prevent the precipitate from encapsulating the germanium substance.

[0013] During the third leaching, an oxidant is added to leach out the sulfide.

[0014] Furthermore, the first leaching mainly completes the leaching of zinc oxide and germanium oxide; the second leaching completes the precipitation of lead sulfate; and the third leaching completes the leaching of germanium and zinc sulfide.

[0015] Furthermore, the acidity of the supernatant of the first leaching is H 2 SO 4 0.5-5g / L.

[0016] Furthermore, the acidity of the supernatant from the second leaching is H 2 SO 4 20-50g / L.

[0017] Furthermore, the acidity of the supernatant from the third leaching is H 2 SO 4 50-100g / L.

[0018] Furthermore, the dispersant is lignin sulfonate.

[0019] Furthermore, the lignin sulfonate is sodium lignin sulfonate or calcium lignin sulfonate.

[0020] Furthermore, the oxidant is one of hydrogen peroxide, manganese powder, and acid leaching residue.

[0021] Furthermore, the acid solution is one or both of dilute sulfuric acid and zinc electrolysis waste liquid.

[0022] Beneficial effects of the present invention: The present invention leaches secondary zinc oxide dust in three steps, and through the control of the leaching process, realizes the leaching of zinc oxide and germanium oxide, the generation of lead precipitation and the leaching of germanium and zinc sulfide in steps, effectively solves the problem of encapsulation and difficulty in leaching sulfides in the current secondary zinc oxide dust leaching process, and realizes a high leaching rate of germanium. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0025] The method for leaching germanium from zinc oxide dust comprises the following steps:

[0026] (1) First leaching

[0027] Add the secondary zinc oxide dust, acid solution and the supernatant of the second leaching into the reaction tank for leaching. The end point acidity is controlled to contain H 2 SO 4 0.5-5g / L. After leaching, the slurry is allowed to stand and clarified, and the supernatant is used to recover germanium and zinc, and the bottom flow enters the second leaching.

[0028] The acid solution used is one or two of dilute sulfuric acid and zinc electrolysis waste liquid.

[0029] Due to the low end point acidity, the following reactions mainly occur:

[0030] ZnO+H 2 SO 4 =ZnSO 4 +H 2 O (1)

[0031] GeO+H 2 SO 4 =GeSO 4 + H 2 O (2)

[0032] GeO 2 +2H 2 SO 4 =Ge(SO 4 ) 2 + H 2 O (3)

[0033] In the first leaching, the leaching of zinc oxide and germanium oxide is completed, and the germanium oxide and zinc oxide are leached first, while lead is not leached. The obtained supernatant mainly contains zinc and germanium and can be directly recovered.

[0034] (2) Second leaching

[0035] The first leaching underflow, the third leaching filtrate and the acid solution are added to the reaction tank for leaching, and lignin sulfonate is added as a dispersant. The lignin sulfonate is sodium lignin sulfonate or calcium lignin sulfonate, and the addition amount is 0.1-0.4% of the weight of the zinc oxide dust. The end point acidity is controlled to contain H 2 SO4 20-50g / L. After leaching, the slurry is allowed to stand for clarification, the supernatant is returned to the first leaching, and the bottom flow enters the third leaching.

[0036] During the second leaching, due to the increase in acidity, lead oxide begins to react with acid in large quantities, mainly the following reactions occur:

[0037] PbO+H 2 SO 4 = PbSO 4 ↓+H 2 O (4)

[0038] ZnO.GeO 2 +3H 2 SO 4 = Ge(SO 4 ) 2 + ZnSO 4 +3H 2 O (5)

[0039] PbO.GeO 2 +3H 2 SO 4 = Ge(SO 4 ) 2 + PbSO 4 ↓+3H 2 O (6)

[0040] The lead sulfate generated by reaction (4) will cover the lead oxide and PbO.GeO 2 The surface forms a coating, which hinders the leaching of acid-soluble germanium in reactions (5) and (6), especially hindering the progress of reaction (6). After adding a dispersant, the coating effect of lead sulfate can be eliminated, promoting the smooth progress of reactions (5) and (6).

[0041] In the second leaching, the reaction of lead oxide to lead sulfate precipitation and the leaching of germanium zinc and germanium lead oxides are completed. By adding a dispersant, the lead sulfate precipitation is prevented from wrapping the oxide, thereby improving the leaching of germanium zinc and germanium lead oxides. It is found through experiments that by controlling the acidity in steps and leaching the lead sulfate precipitation first, the leaching rate of sulfides in the subsequent third leaching can be improved.

[0042] (3) Third leaching

[0043] The underflow and acid solution from the second leaching are added to the reaction tank for leaching, and an oxidant is added. The amount of the oxidant added is 15-40% of the weight of the secondary zinc oxide dust. The end point acidity is controlled to contain H 2 SO 4 50-100g / L, filter after leaching, the filtrate returns to the second leaching, and the filter residue is lead residue.

[0044] The oxidant is industrial hydrogen peroxide, manganese powder, or one of the acid leaching residues.

[0045] Add oxidant and use H in industrial hydrogen peroxide to 2 O 2 , or MnO in manganese powder 2 , or ZnO.Fe in acid leaching residue 2 O 3 The oxidizing property of zinc oxide can leach out the sulfides of zinc and germanium in the secondary zinc oxide dust under acidic conditions.

[0046] The following reactions mainly occur (using hydrogen peroxide as an oxidant as an example):

[0047] ZnS+H 2 SO 4 +H 2 O 2 =ZnSO 4 +2H 2 O+S↓(7)

[0048] GeS+H 2 SO 4 +H 2 O 2 =GeSO 4 +2H 2 O+S↓ (8)

[0049] G JZ 2 +2H 2 SO 4 +2H 2 O 2 =Ge(SO 4 ) 2 +4H 2 O+2S↓ (9)

[0050] By means of three-step leaching, adding lignin sulfonate in the second leaching step and adding an oxidant in the third leaching step, germanate and germanium in the form of sulfide in the secondary zinc oxide dust can be leached more thoroughly.

[0051] In order to more clearly illustrate the present invention, it is described in detail through the following examples.

[0052] Example 1

[0053] The secondary zinc oxide smoke used in this embodiment has the following components: Ge 0.223%wt, Pb 15.32%wt, Zn 56.79%wt, S 4.52%wt.

[0054] (1) First leaching: Take dilute sulfuric acid, electrolytic waste liquid, and the second leaching supernatant, add them into a beaker and mix them evenly. After stirring, add zinc oxide dust. After the reaction is completed, let the slurry stand for 30 minutes and filter out the supernatant. The supernatant contains H 2 SO 4 4.8g / L, the bottom flow enters the second leaching.

[0055] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 50g / L of electrolytic waste liquid and the third leaching solution were added, and sodium lignin sulfonate was added at a rate of 0.4% of the weight of zinc oxide smoke. Stirring was started. After the reaction was completed, the slurry was allowed to stand for 30 minutes, the supernatant was filtered out, and the bottom flow entered the third leaching.

[0056] (3) The third leaching: according to the H content at the reaction end point 2 SO 4 Add 100g / L of dilute sulfuric acid and add industrial hydrogen peroxide at 15% of the weight of zinc oxide dust, start stirring, and after the reaction is completed, separate the slurry into liquid and solid, and the filter residue is lead slag, which is baked at a constant temperature to constant weight. The slag rate is determined to be 32.63%, the slag contains 0.0634% Ge, and the germanium leaching rate is 90.72%.

[0057] Comparative Example 1 (Two-step leaching)

[0058] The secondary zinc oxide fume used in this comparative example is the same as that in Example 1.

[0059] (1) First leaching: Take dilute sulfuric acid, electrolytic waste liquid, and the second leaching supernatant, add them into a beaker and mix them evenly. After stirring, add zinc oxide dust. After the reaction is completed, let the slurry stand for 30 minutes and filter out the supernatant. The supernatant contains H 2 SO 4 40g / L, the bottom flow enters the second leaching.

[0060] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 100g / L of electrolytic waste liquid and the third leaching solution were added, and sodium lignin sulfonate was added at a rate of 0.4% of the weight of zinc oxide smoke. Stirring was started. After the reaction was completed, it was filtered and the filter residue was baked at a constant temperature to constant weight. The slag rate was determined to be 42.03%, the slag contained 0.7481% Ge, and the germanium leaching rate was 61.27%.

[0061] Comparative Example 2 (oxidation during one-step leaching)

[0062] The secondary zinc oxide fume used in this comparative example is the same as that in Example 1.

[0063] (1) First leaching: Take dilute sulfuric acid, electrolytic waste liquid, second leaching supernatant, and 5% of the weight of zinc oxide dust, add industrial hydrogen peroxide, add to a beaker and mix evenly, start stirring and add secondary zinc oxide dust. After the reaction is completed, let the slurry stand for 30 minutes, filter out the supernatant, and the supernatant contains H 2 SO 4 4.8g / L, the bottom flow enters the second leaching.

[0064] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 50g / L of electrolytic waste liquid and the third leaching solution were added, and sodium lignin sulfonate was added at a rate of 0.4% of the weight of zinc oxide smoke. Stirring was started. After the reaction was completed, the slurry was allowed to stand for 30 minutes, the supernatant was filtered out, and the bottom flow entered the third leaching.

[0065] (3) The third leaching: according to the H content at the reaction end point 2 SO 4 100g / L dilute sulfuric acid was added, and industrial hydrogen peroxide was added according to 10% of the weight of zinc oxide dust. Stirring was started. After the reaction was completed, the slurry was separated into liquid and solid. The obtained filter residue was baked at a constant temperature to constant weight. The slag rate was determined to be 35.63%, the slag contained 0.0504% Ge, and the germanium leaching rate was 87.98%.

[0066] Comparative Example 3 (Leaching in two steps, and adding oxidant in the second leaching)

[0067] The secondary zinc oxide fume used in this comparative example is the same as that in Example 1.

[0068] (1) First leaching: Take dilute sulfuric acid, electrolytic waste liquid, and the second leaching supernatant, add them into a beaker and mix them evenly. After stirring, add zinc oxide dust. After the reaction is completed, let the slurry stand for 30 minutes and filter out the supernatant. The supernatant contains H 2 SO 4 4.8g / L, the bottom flow enters the second leaching.

[0069] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 100g / L of electrolytic waste liquid and dilute sulfuric acid were added, and sodium lignin sulfonate was added at 0.4% of the weight of zinc oxide dust, and industrial hydrogen peroxide was added at 15% of the weight of zinc oxide dust. Stirring was started. After the reaction was completed, the slurry was solid filtered to obtain filter residue, which was baked at a constant temperature to constant weight. The slag rate was determined to be 38.63%, the Ge content in the slag was 0.1046%, and the germanium leaching rate was 83.84%.

[0070] If the oxidation leaching of sulfides is completed simultaneously with the precipitation of lead sulfate, the leaching rate of germanium is significantly reduced.

[0071] Example 2

[0072] The secondary zinc oxide smoke used in this embodiment has the following components: Ge 0.0652%wt, Pb 13.96%wt, Zn 58.14%wt, S 3.44%wt.

[0073] (1) First leaching: Take 1500 mL of dilute sulfuric acid and 500 mL of the second leaching supernatant, add them into a beaker and mix them evenly. After stirring, take 240 g of secondary zinc oxide dust and add them. After the reaction is completed, let the slurry stand for 30 minutes and filter out the supernatant. The supernatant contains H 2 SO 4 0.7g / L, the bottom flow enters the second leaching.

[0074] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 20g / L of electrolytic waste liquid and the third leaching solution were added, and calcium lignin sulfonate was added at a rate of 0.1% of the weight of zinc oxide smoke. Stirring was started. After the reaction was completed, the slurry was allowed to stand for 30 minutes, the supernatant was filtered out, and the bottom flow entered the third leaching.

[0075] (3) The third leaching: according to the H content at the reaction end point 2 SO 4 Add 50g / L of dilute sulfuric acid, and add acid leaching residue according to 40% of the weight of zinc oxide smoke, start stirring, and after the reaction is completed, separate the slurry into liquid and solid, and the filter residue is lead slag, which is baked at a constant temperature to constant weight. The slag rate is determined to be 34.37%, the slag contains 0.0194% Ge, and the germanium leaching rate is 89.77%.

[0076] Comparative Example 4 (no dispersant added during the second leaching)

[0077] This comparative example is the same as Example 2, except that no dispersant is added during the second leaching.

[0078] After three-step leaching and baking at a constant temperature to constant weight, the slag rate was determined to be 35.84%, the slag contained 0.0264% Ge, and the germanium leaching rate was 86.32%.

[0079] Example 3

[0080] The secondary zinc oxide smoke used in this embodiment has the following components: Ge 0.132%wt, Pb 13.49%wt, Zn 56.33%wt, S 4.01%wt.

[0081] (1) First leaching: Take 1500 mL of dilute sulfuric acid and 500 mL of the second leaching supernatant, add them into a beaker and mix them evenly. After stirring, take 260 g of secondary zinc oxide dust and add them. After the reaction is completed, let the slurry stand for 30 minutes and filter out the supernatant. The supernatant contains H 2 SO 4 2.6g / L, the bottom flow enters the second leaching.

[0082] (2) Second leaching: according to the H content at the reaction end point 2 SO 4 25g / L of electrolytic waste liquid and the third leaching solution were added, and sodium lignin sulfonate was added at 0.2% of the weight of zinc oxide smoke. Stirring was started. After the reaction was completed, the slurry was allowed to stand for 30 minutes, the supernatant was filtered out, and the bottom flow entered the third leaching.

[0083] (3) The third leaching: according to the H content at the reaction end point 2 SO 4 70g / L dilute sulfuric acid is added, and manganese powder is added according to 30% of the weight of zinc oxide smoke, and stirring is started. After the reaction is completed, the slurry is separated into liquid and solid, and the filter residue is lead slag, which is baked at a constant temperature to constant weight. The slag rate is determined to be 33.63%, the slag contains Ge0.0428%, and the germanium leaching rate is 89.10%.

[0084] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for leaching germanium from zinc oxide dust, characterized in that: The following steps are involved: (1) First leaching, mixing the secondary zinc oxide dust with acid solution for leaching; the acidity of the supernatant of the first leaching is H2SO40.5-5g / L; the first leaching mainly completes the leaching of zinc oxide and germanium oxide; (2) Second leaching: the bottom flow of the first leaching is subjected to the second leaching, and the leachate is returned to the first leaching; the acidity of the supernatant of the second leaching is H2SO420-50g / L; the second leaching completes the precipitation of lead sulfate; (3) The third leaching, the bottom flow of the second leaching is subjected to the third leaching, and the leaching liquid is returned to the second leaching; the acidity of the supernatant of the third leaching is H2SO450-100g / L; the third leaching completes the leaching of germanium and zinc sulfide; in, During the second leaching, a dispersant is added to prevent the precipitate from encapsulating the germanium substance; During the third leaching, an oxidant is added to leach out the sulfide.

2. The method according to claim 1, characterized in that The dispersant is lignin sulfonate.

3. The method according to claim 2, characterized in that The lignin sulfonate is sodium lignin sulfonate or calcium lignin sulfonate.

4. The method according to claim 1, characterized in that: The oxidant is one of hydrogen peroxide, manganese powder and acid leaching residue.

5. The method according to claim 1, characterized in that The acid solution is one or more of dilute sulfuric acid, zinc electrolysis waste liquid, and leaching liquid.

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