Leaching method of zinc roasted ore

Abstract

The invention relates to a leaching method of zinc roasted ore, and belongs to the technical field of zinc hydrometallurgy. According to the technical scheme, the method comprises the steps that the zinc roasted ore is added into second leaching liquid and acid liquid to be subjected to first leaching, and first underflow and middle supernate are obtained; the first underflow is subjected to second leaching, second underflow and second leaching liquid are obtained, and the second leaching liquid is returned to the first leaching; and acid liquor is added to carry out third leaching on the second underflow, leaching residues and third leaching liquid are obtained, and the third leaching liquid is returned to the second leaching. By means of the method, the leaching rate of zinc in the zinc roasted ore can be larger than 96%, the adaptability to the zinc roasted ore is extremely good, and the method is especially suitable for treating the high-silicon zinc roasted ore.

Description

Technical Field

[0001] This invention belongs to the field of zinc hydrometallurgical technology, specifically, it relates to the leaching of zinc and the precipitation of iron in zinc roasted ore. Background Technology

[0002] When zinc roasted ore is leached using a process of neutral leaching → weak / low acid leaching → hot acid leaching, a large amount of iron is leached out. The hot acid leaching solution needs to be de-ironized to prevent iron from accumulating in the process.

[0003] The technical solution disclosed in Chinese patent CN117025972A is as follows: Zinc roasted ore is subjected to neutral leaching, weak acid leaching, hot acid leaching, and neutralization of the hot acid underflow, etc., to remove impurities such as Fe that have been dissolved in the hot acid underflow. 3+ The process involves precipitating the zinc ferrite and adding it to the slag to achieve iron balance during zinc roasting ore leaching. However, this method requires an additional neutralization step to balance the iron entering the solution, and the leaching intensity for zinc ferrite is insufficient, resulting in a zinc content in the leaching residue as high as 12-13%. This method suffers from drawbacks such as multiple steps and high zinc content in the residue. Summary of the Invention

[0004] This invention aims to at least partially address the problems or deficiencies existing in the prior art. To this end, this invention proposes a method for leaching zinc and precipitating iron from zinc roasted ore, characterized by high zinc leaching rate and the elimination of the need for separate iron removal in the hot acid leaching solution.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: The leaching method for the zinc roasted ore includes the following steps: The zinc roasted ore is added to the second leaching solution and acid solution for the first leaching to obtain the first underflow and the middle and supernatant; The first underflow is subjected to a second leaching to obtain a second underflow and a second leachate, and the second leachate is returned to the first leaching. Acid solution is added to the second underflow for a third leaching, resulting in leaching residue and a third leachate. The third leachate is then returned to the second leaching.

[0006] In some embodiments, the first leaching involves adding the zinc roasted ore at least twice. The leaching endpoint acidity of the first addition of zinc roasted ore is 5-10 g / L, and the leaching endpoint pH of the second addition of zinc roasted ore is 5.0-5.4.

[0007] In some embodiments, iron alum and ferrosilicon precipitates are generated during the first leaching.

[0008] In some embodiments, the ferrosilicon precipitate is in the form of ferrosilicon silicate.

[0009] In the example, iron alum is generated during the second leaching.

[0010] In some embodiments, the second leaching process parameters are: temperature 80-85°C, time 1.0-2.0 h, and endpoint acidity 8-15 g / L.

[0011] In some embodiments, the third leaching process parameters are: temperature 80–90°C, time 1.0–2.0 h, and endpoint acidity 60–80 g / L.

[0012] In some embodiments, the acid solution is zinc electrolysis waste liquid, and / or dilute sulfuric acid.

[0013] In some embodiments, the supernatant is sent for purification; the leaching residue is sent for pyrometallurgical treatment. Detailed Implementation

[0014] The embodiments of the present invention are described in detail below. These descriptions are intended to explain the present invention and should not be construed as limiting the present invention.

[0015] It should be understood that the weight mentioned in the embodiments of the present invention can be a mass unit known in the metallurgical / chemical industry, such as g, kg, t, and the volume unit can be mL, L, m. 3 The volume units are those known in the metallurgical / chemical fields. The operation methods involved in the embodiments of this invention can be intermittent or continuous. That is, the feeding, leaching and sedimentation can be intermittent, or the feeding, leaching and sedimentation can be continuous.

[0016] The example includes the following steps: S1: The zinc roasted ore is added to the second leaching solution and acid solution for the first leaching. After settling, the leached slurry yields the first underflow and the middle and upper supernatants. During the first leaching, the zinc roasted ore is added at least twice. The final acidity of the first addition of zinc roasted ore is 5-10 g / L, which allows zinc and silicates to leach out, and also leaches some Fe. 3+ Iron ferrous sulfate precipitate is formed; the final leaching pH of the second zinc roasting of the ore is 5.0–5.4, which allows the remaining Fe to precipitate. 3+ Silica precipitate.

[0017] As is common knowledge, the first leaching of zinc roasted ore requires the presence of Fe. 3+ Fe 3+ At the end of the leaching process, it precipitates as ferric hydroxide to adsorb arsenic, antimony, and other ions from the solution and precipitate them into the residue; in existing technologies, Fe... 3+ Before hydrolysis and precipitation, the Fe content in the first leaching pulp needs to be controlled. 3+ The amount is 10 to 15 times the amount of arsenic dissolved, 20 to 40 times the amount of antimony dissolved, and Fe 3+The amount of Fe should not be too little or too much. Too little will result in incomplete hydrolysis and precipitation of arsenic and antimony, causing the arsenic and antimony content in the supernatant to exceed the standard, increasing the difficulty of purification. Too much will make it difficult to clarify the first leaching underflow. Therefore, Fe is generally controlled. 3+ The dosage is 1-2 g / L; during the first addition of zinc roasted ore, the silica in the zinc roasted ore, which exists as silicates, will be dissolved by acid. The dissolved silica exists primarily in colloidal form in the leaching pulp. During the second addition of zinc roasted ore to adjust the pulp acidity to pH 5.0-5.4, Fe... 3+ The ore slurry is hydrolyzed and adsorbed in the form of Fe(OH)3 to precipitate arsenic, antimony and other impurities that have been dissolved in the ore slurry. Silica is hydrolyzed and precipitated in the form of SiO2.nH2O. However, when the SiO2 content in the ore slurry is high, a large amount of SiO2.nH2O is generated, which will deteriorate the clarification and sedimentation performance of the first leaching ore slurry.

[0018] It should be noted that the actual form of silica dissolved by acid in zinc roasted ore in the leaching slurry is H2SiO3. In this invention, its content in the leaching slurry is expressed as SiO2 or Si.

[0019] In the technical solution of this invention, the second leachate contains Fe. 3+ When the second leaching solution is returned to the first leaching solution, after the initial addition of zinc roasted ore, almost no zinc ferrite in the zinc roasted ore is leached out, but a large amount of silicate is leached out, resulting in a high Si content and Fe content in the first leaching pulp. 3+ The content is also high. If existing technology is used directly, that is, relying on adding zinc roasted ore at the end of the first leaching stage to make the pulp pH 5.0-5.4, Fe... 3+ Ferric hydroxide is formed, and Si forms SiO2·nH2O. When these two precipitate, they will worsen the clarification and settling properties of the leaching pulp.

[0020] Furthermore, the precipitates of iron and silicon at the end of the first leaching stage are almost entirely ferric hydroxide and SiO2·nH2O. If the leaching acidity (pH < 2) is present in subsequent leachings, the precipitated ferric hydroxide will redissolve, leading to Fe... 3+ Gradual enrichment requires an additional iron removal step.

[0021] To address the clarification and settling properties of the first leaching pulp, and to reduce the amount of precipitated Fe... 3+ Regarding the dissolution amount in subsequent leaching, the process parameters for the initial addition of zinc roasted ore during the first leaching of this invention are: temperature 85–90°C, time 1.0 h, and leaching endpoint H₂SO₄ 5–10 g / L. These process parameters allow some of the Fe in the first leaching slurry to be dissolved. 3+Iron ore is generated, and some impurities such as arsenic and antimony are adsorbed and precipitated. The process parameters for the second zinc roasting of the ore are: temperature 80-85℃, time 0.5h, and pH value at the leaching endpoint 5.0-5.4. These process parameters can reduce the Fe content in the first leaching pulp. 3+ Besides forming small amounts of ferric hydroxide and SiO2·nH2O precipitates, Si also produces a large amount of small, acid-insoluble ferrosilicon precipitates. Phase analysis confirmed that the acid-insoluble ferrosilicon precipitates are in the form of ferric silicate (Ⅲ){Fe2(SiO3)3}. Ferric silicate also adsorbs and precipitates impurities such as arsenic and antimony. Since iron alum and ferric silicate are difficult to dissolve in subsequent leaching, the adsorbed and precipitated impurities such as arsenic and antimony are also difficult to dissolve.

[0022] It should be noted that, in order to produce ferrous sulfate after the first zinc roasting of the ore in the first leaching, the Fe in the leaching pulp needs to be increased. 3+ Greater than 3 g / L; to produce ferric silicate (III) after the second zinc roasting of the ore following the first leaching, the Fe in the leaching pulp needs to be greater than 3 g / L. 3+ The mass ratio of silicon to silicon is 1.3 to 2.0:1.

[0023] Advantageously, using the above process parameters during the first leaching not only stabilizes the clarification and settling properties of the first leaching pulp, but also generates ferric alum and ferric silicate (III) that are insoluble in acid, creating conditions for subsequent leaching of zinc ferrite.

[0024] In some embodiments, the present invention employs returning a second leachate to a first leachate, the second leachate containing Fe. 3+ 7–10 g / L, containing 1–2 g / L of Si. After the second leaching solution is returned to the first leaching solution and mixed with the acid solution, and then the ore is first roasted with zinc, the slurry contains Fe. 3+ 3.5~4.5g / L, containing 2~3g / L of Si; after the second zinc addition and roasting of the ore, in addition to the formation of ferric hydroxide and SiO2.nH2O precipitates, ferric silicate (III), which is insoluble in acid, is also formed.

[0025] Advantageously, through the first leaching, Fe can be... 3+ The proportion of ferric alum precipitate reaches 20%, and the proportion of ferric silicate precipitate reaches 20%.

[0026] S2: The first underflow is subjected to a second leaching, and the process parameters are controlled to generate iron alum. After the leached slurry settles, a second underflow and a second leachate are obtained. The second leachate is returned to the first leaching.

[0027] The second leaching process parameters are: temperature 80-90℃, time 1.0-2.0h, and final acidity 8-15g / L.

[0028] Under these process parameters, the ferric hydroxide generated in the first leaching will be leached out, but the iron alum and ferric silicate (III) generated in the first leaching will not be leached out; in addition, when the third leaching solution is returned to the second leaching, the Fe in the third leaching solution will be leached out. 3+ It will react with sodium and potassium ions and lead sulfate in the slurry to form iron alum precipitate. Iron alum has a good adsorption and impurity removal effect and can adsorb impurities such as arsenic and antimony and co-precipitate.

[0029] Advantageously, the second leaching can allow Fe 3+ The proportion of iron alum precipitate reaches 60%.

[0030] Analysis revealed that in the second leaching pulp, Fe... 3+ Iron alum will only be formed if the concentration is greater than 4 g / L.

[0031] S3: Add acid to the second underflow for the third leaching. After liquid-solid separation, the slurry yields leaching residue and third leaching solution. The third leaching solution is returned to the second leaching.

[0032] The third leaching process parameters are: temperature 80-90℃, time 2.0-3.0h, and final acidity 60-80g / L.

[0033] Under these process parameters, zinc ferrite in the zinc roasted ore will be leached out, generating zinc sulfate and ferric sulfate which enter the third leaching solution, thereby increasing the zinc leaching rate. Ferric silicate (III) and iron alum already formed in the second underflow are difficult to leach, and impurities such as arsenic and antimony adsorbed for precipitation are also difficult to leach. This achieves the goal of both reducing the zinc content in the leaching residue and simultaneously precipitating iron.

[0034] The acid solution added in the first and third leaching processes is zinc electrolysis waste liquid and / or dilute sulfuric acid.

[0035] It should be noted that the three-step leaching technique used in this invention for zinc roasted ore is highly correlated; during the third leaching, the Fe from the previous third leaching step needs to be removed. 3+ The first and second leaching processes produce insoluble ferrous sulfate and ferric silicate (III); the second leaching process requires the removal of Fe from the ore pulp. 3+ Iron alum will only be formed when the concentration is greater than 4 g / L; the first leaching requires the removal of Fe from the ore pulp. 3+ Ferrous sulfate only forms when the concentration exceeds 3 g / L; moreover, the formation of ferric silicate (III) also requires the leaching of Fe from the slurry. 3+ The mass ratio of zinc ferrite to Si is 1.3 to 2.0:1. In other words, the third leaching is a prerequisite for the formation of ferric silicate (III) and iron alum in the first and second leaching, but the formation of ferric silicate (III) and iron alum in the first and second leaching is also a prerequisite for the leaching of only zinc ferrite in the third leaching. They are not only prerequisites for each other, but also highly correlated.

[0036] Purification of the supernatant and middle natant is existing technology and is not related to the problem solved by this invention, therefore it will not be described in detail.

[0037] Similarly, the treatment of leaching residue using pyrometallurgical furnaces is also existing technology and is unrelated to the problem solved by this invention, so it will not be described in detail.

[0038] Advantageously, the present invention is highly adaptable to the added zinc roasted ore, and is particularly suitable for processing high-silicon zinc roasted ore.

[0039] To illustrate the present invention more clearly, the following specific embodiments will be described in detail.

[0040] Example 1 The zinc roasted ore contained 59.65 wt% Zn, 9.86 wt% Fe, and 3.53 wt% SiO2; the second leachate from the first leaching round contained 15 g / L H2SO4 and Fe... 3+ 8 g / L, Si 1.1 g / L; the third leachate from the first leaching round contained 80 g / L H₂SO₄ and Fe. 3+ 27 g / L, Si 0.5 g / L.

[0041] Take 1500 mL of the second leachate from the first leaching round, 1000 mL of zinc electrolysis waste liquid, and add 200 g of zinc roasted ore for the first time. After 1.0 h at 90℃, determine the concentration of H2SO4 in the solution to be 10 g / L and the concentration of Fe. 3+ 3.84 g / L, Si 2.02 g / L, Fe 3+ The mass ratio of zinc ore to Si was 1.90:1. A second addition of 100g of zinc roasted ore was made at 80℃ for 0.5h, with a final leaching pH of 5.4. After static clarification, the slurry had a supernatant rate of 78.51%, yielding 1840mL of supernatant and the first underflow. The supernatant contained 10mg / L Fe, 0.05mg / L As, and 0.2mg / L Sb, meeting the purification requirements.

[0042] 1000 mL of the third leachate from the first leaching round was added to the first underflow for a second leaching at 85℃ for 1.0 h. After settling and clarifying, 1520 mL of the second leachate and the second underflow were obtained. The second leachate contained 14.5 g / L H₂SO₄ and Fe. 3+ 8.06 g / L, Si 1.1 g / L.

[0043] A dilute sulfuric acid solution was added to the second underflow for a third leaching process at 90℃ for 2.0 h. The slurry was then filtered to obtain 1010 mL of the third leaching solution and leaching residue. The third leaching solution contained 80 g / L H₂SO₄ and Fe. 3+26.8 g / L, Si 0.43 g / L; the dry weight of the leaching residue is 111.7 g, containing 5.50 wt% Zn and 26.52 wt% Fe, with a zinc leaching rate of 96.57%; the iron in the zinc roasted ore enters the leaching residue and will not accumulate in the liquid.

[0044] Example 2 The zinc roasted ore contained 57.54 wt% Zn, 10.73 wt% Fe, and 5.12 wt% SiO2. The second leachate from the first leaching round contained 48 g / L H2SO4 and Fe... 3+ 9 g / L, Si 1.6 g / L; the third leachate from the first leaching round contained 60 g / L H₂SO₄ and Fe. 3+ 28 g / L, Si 0.6 g / L.

[0045] Take 1500 mL of the second leachate from the first leaching round, 1000 mL of dilute sulfuric acid solution, and add 210 g of zinc roasted ore for the first time. After 1.0 h at 85℃, the solution contains 5.1 g / L of H2SO4 and Fe. 3+ 4.3 g / L, Si 3.1 g / L, Fe 3+ The mass ratio of zinc ore to Si was 1.39:1. 90g of zinc roasted ore was added a second time at 85℃ for 0.5h. The leaching endpoint pH was 5.0. After static clarification, the slurry had a supernatant rate of 76.42%, yielding 1830mL of supernatant and the first underflow. The supernatant contained 8mg / L Fe, 0.08mg / L As, and 0.23mg / L Sb, meeting the purification requirements.

[0046] 1000 mL of the third leachate from the first leaching round was added to the first underflow for a second leaching at 80℃ for 2.0 h. After settling and clarifying, 1520 mL of the second leachate and the second underflow were obtained. The second leachate contained 8.2 g / L H₂SO₄ and Fe. 3+ 8.06 g / L, Si 1.5 g / L.

[0047] Zinc electrolysis waste liquid was added to the second underflow for a third leaching process at 80℃ for 3.0 h. The slurry was filtered to obtain 1010 mL of the third leaching solution and leaching residue. The third leaching solution contained 60 g / L H2SO4 and Fe. 3+ 27.9 g / L, Si 0.6 g / L; the dry weight of the leaching residue is 110.6 g, containing 5.65 wt% Zn and 28.11 wt% Fe, with a zinc leaching rate of 96.26%; the iron in the zinc roasted ore enters the leaching residue and will not accumulate in the liquid.

[0048] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0049] In the description of this specification, references to terms such as "one embodiment," "some embodiments," or "example" indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and / or combine the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A leaching method for zinc roasted ore, characterized in that, Includes the following steps: The zinc roasted ore is added to the second leaching solution and acid solution for the first leaching to obtain the first underflow and the middle and supernatant; The first underflow is subjected to a second leaching to obtain a second underflow and a second leachate, and the second leachate is returned to the first leaching. Acid solution is added to the second underflow for a third leaching, resulting in leaching residue and a third leachate. The third leachate is then returned to the second leaching.

2. The method according to claim 1, characterized in that, The first leaching process involves adding the zinc roasted ore at least twice. The leaching endpoint acidity of the first addition of zinc roasted ore is 5–10 g / L, and the leaching endpoint pH of the second addition of zinc roasted ore is 5.0–5.

4.

3. The method according to claim 1 or 2, characterized in that, The first leaching produces ferrous sulfate and ferrosilicon precipitates.

4. The method according to claim 3, characterized in that, The ferrosilicon precipitate is in the form of ferrosilicon silicate.

5. The method according to claim 1, characterized in that, Iron alum is formed during the second leaching.

6. The method according to claim 1, characterized in that, The second leaching process parameters are: temperature 80-85℃, time 1.0-2.0h, and endpoint acidity 8-15g / L.

7. The method according to claim 1, characterized in that, The third leaching process parameters are: temperature 80-90℃, time 1.0-2.0h, and final acidity 60-80g / L.

8. The method according to claim 1, characterized in that, The acid solution is zinc electrolysis waste liquid and / or dilute sulfuric acid.

9. The method according to claim 1, characterized in that, The supernatant is sent for purification; the leaching residue is sent for pyrometallurgical treatment.