A method for treating zinc-iron solid waste and co-producing iron-based adsorbent

Abstract

The present application relates to the field of solid waste treatment, in particular to a method for treating zinc-iron solid waste and co-producing iron-based adsorbent, wherein the zinc-iron solid waste is subjected to countercurrent acid leaching to obtain iron-zinc leaching solution; a reducing agent is added to the iron-zinc leaching solution to perform reduction reaction, and then ammonia water is added to perform selective precipitation reaction, followed by solid-liquid separation to obtain iron-based adsorbent and iron-zinc-free solution; the zinc-iron solid waste is zinc smelting iron slag containing zinc ferrite and at least one impurity selected from Pb, Mn, Mg, Al, Na and Cu; the molar ratio of the reducing agent to Fe element in the iron-zinc leaching solution is 1:1-10; the volume ratio of the ammonia water to the iron-zinc leaching solution is greater than or equal to 0.5; and the temperature in the selective precipitation reaction stage is greater than or equal to 50 DEG C. The treatment method can realize the separation of zinc and iron, and can also co-produce iron-based adsorbent with high adsorption capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid waste treatment, in particular to a comprehensive recovery method of zinc-iron solid waste. BACKGROUND

[0002] Iron is an important impurity element in zinc smelting industry, because iron is often associated with zinc concentrate in the form of pyrite and magnetite, and often replaces zinc in sphalerite in the form of isomorphism, and coexists with zinc in the form of franklinite. The boiling roasting technology is usually used to treat zinc concentrate in the plant, in which process, Fe in zinc concentrate is converted into Fe2O3, and Zn is converted into ZnO, and Fe2O3 reacts with ZnO to form complex metal oxide ZnFe2O4. ZnFe2O4 has spinel structure, and its melting point is about 1600℃, and it has stable chemical properties, wear resistance, high temperature resistance and corrosion resistance, and generally does not react with acid and alkali. Therefore, a large amount of leaching residue solid waste mainly composed of ZnFe2O4 is often produced in the leaching process, and a large amount of water-soluble zinc (ZnSO4) is often contained in the leaching residue solid waste, which is derived from the residual of leaching rich liquid in the leaching residue. Iron removal is very important in the liquid purification process, and a large amount of iron removal residue solid waste composed of iron-containing compounds such as FeOOH, Fe(OH)3, KFe3(SO4)2(OH)6 and a small amount of CaSO4 and ZnSO4 is often produced in this process according to different iron removal methods selected by enterprises. At the same time, the above zinc-iron residue often contains elements such as Pb, Mn, Mg, Al, Na and Cu, which is a kind of solid waste with complex composition and difficult to recycle.

[0003] In summary, a large amount of zinc-iron containing solid waste is inevitably produced in the zinc smelting process. In order to reduce the process, various types of zinc-iron residue are often mixed and stored before being treated uniformly in the actual production process, and the zinc-iron solid waste residue mainly composed of Zn and Fe, mainly containing ZnFe2O4, and containing part of water-soluble zinc, various iron-containing compounds and various complex elements is often obtained after storage. The zinc content in the zinc-iron solid waste is usually more than 15%, and the iron content is about 30%, and the most commonly used treatment method is to enter the fuming furnace, rotary kiln and other pyroprocessing equipment to treat and recover secondary zinc oxide, while a large amount of iron can only be discarded as residue, and other valuable metals such as lead and manganese cannot be effectively utilized.

[0004] Therefore, although there are existing mature recovery processes for treating zinc-iron solid waste, they are mainly focused on the recovery of zinc element, and it is urgent to develop a comprehensive recovery method to fully realize the resourceization and high value of zinc-iron solid waste. SUMMARY

[0005] Aiming at the problem that zinc-iron solid waste is difficult to comprehensively and efficiently recover, the application aims to provide a method for treating zinc-iron solid waste and co-producing iron-based adsorbent, so as to realize high-selective recovery and utilization of iron and zinc.

[0006] A method for treating zinc-iron solid waste and co-producing iron-based adsorbent, characterized in that: zinc-iron solid waste is subjected to countercurrent acid leaching to obtain iron-zinc leaching liquor; a reducing agent is added to the iron-zinc leaching liquor to perform a reduction reaction, and then ammonia water is added to perform a selective precipitation reaction, followed by solid-liquid separation to obtain iron-based adsorbent and iron-zinc liquid.

[0007] The zinc-iron solid waste is zinc smelting iron slag, which contains zinc ferrite and at least one impurity of Pb, Mn, Mg, Al, Na and Cu;

[0008] The molar ratio of the reducing agent to Fe elements in the iron-zinc leaching liquor is 1:1-10;

[0009] The volume ratio of the ammonia water to the iron-zinc leaching liquor is greater than or equal to 0.5;

[0010] The temperature of the selective precipitation reaction stage is greater than or equal to 50 DEG C.

[0011] The application first proposes the technical idea of separating zinc and iron in zinc-iron solid waste generated in the zinc smelting process and co-producing iron-based adsorbent material, however, it is found in the early stage of research and development that to realize the technical idea, it is necessary to overcome the problems of unsatisfactory zinc-iron recovery rate caused by stable composition and phase of zinc-iron solid waste, low selectivity of zinc-iron and impurity separation caused by high iron content, and unsatisfactory adsorption performance caused by difficulty in controlling the composition, phase and morphology of iron-based adsorbent from solid waste. In view of the technical problems faced by the technical idea, the application finds that the zinc-iron solid waste is innovatively subjected to countercurrent acid leaching treatment, and then combined with reduction, ammonia water assisted selective precipitation and parameter control, so as to realize the effective recovery and high-selective separation of zinc and iron in zinc-iron solid waste in a synergistic manner. Furthermore, the phase and morphology structure of the iron-based adsorbent can be unexpectedly controlled, and the performance of the iron-based adsorbent can be improved. Based on the process, the zinc-iron solid waste can be effectively separated, and the iron-based adsorbent material with better adsorption performance can be unexpectedly obtained from the solid waste.

[0012] In the application, the zinc-iron solid waste further contains at least one phase composition of Fe2O3, ZnO, FeOOH, CaSO4, ZnSO4, Fe(OH)3, KFe3(SO4)2(OH)6 and NaFe3(SO4)2(OH)6;

[0013] The zinc-iron solid waste can be a solid waste with high iron content which is difficult to treat, for example, the zinc content is 15 wt.% or more, and further can be 15-30 wt.%. The iron content is 15 wt.% or more, and further can be 15-35 wt.%.

[0014] In the present application, the zinc-iron solid waste is treated by countercurrent acid leaching, reduction and ammonia selective precipitation, which can realize synergy, help to realize efficient recovery and selective separation of iron and zinc in the solid waste, and more importantly, can regulate the selective use of beneficial and non-beneficial components adsorbed in the solid waste, regulate the phase and morphology of the adsorbent, and then unexpectedly facilitate the obtaining of high-performance iron-based adsorption materials.

[0015] In the present application, the acid solution in the countercurrent acid leaching stage is at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0016] Preferably, the concentration of the acid solution is 1-4 M.

[0017] In the present application, the leaching temperature is not particularly required, and considering the treatment cost, the leaching stage is carried out at room temperature.

[0018] Preferably, the countercurrent acid leaching stage is 2-5 stages.

[0019] In the present application, based on the countercurrent acid leaching process, it is helpful to improve the controllable leaching of beneficial adsorbed components in the solid waste, and not only that, but also to obtain iron-based adsorbents with high adsorption performance.

[0020] In the present application, the iron-zinc leaching solution is a high-iron zinc leaching solution with a Fe concentration of greater than 30 g / L and a Zn concentration of greater than or equal to 15 g / L, and further preferably, the high-iron zinc leaching solution has an ionic iron concentration of 50-100 g / L and an ionic zinc concentration of 50-100 g / L.

[0021] In the present application, the high-iron zinc leaching solution is subjected to reduction treatment, and further in combination with the control of the amount of the reducing agent, which is conducive to the controllable adjustment of the components, the subsequent separation of zinc and iron, and the obtaining of high-performance iron-based adsorbents.

[0022] As preferred, the reducing agent is at least one of iron powder, zinc powder, ZnS and ZnSO3.

[0023] As preferred, the molar ratio of the reducing agent to Fe in the iron-zinc leaching solution is 1:5-8.

[0024] Preferably, the temperature of the reduction reaction is 15-95 DEG C, and further preferably 50-90 DEG C.

[0025] In the present application, the n(Fe 3+ ):n(Fe2+ The molar ratio of the high-iron zinc leaching solution and the ammonia water can be 1.9-2.1:1.

[0026] In the application, ammonia water is added to the zinc-iron solution to perform a selective separation reaction of iron and zinc, so that the iron in the solution is selectively transformed and precipitated, and the zinc is enriched in the solution. Research has found that by controlling the addition volume of ammonia water and the reaction temperature, the separation of iron and zinc can be realized, and in addition, the controlled treatment of trace elements is also beneficial, so that the obtained iron-based adsorbent is more suitable for the adsorption of Tl and the like.

[0027] In the application, the concentration of the ammonia water is greater than or equal to 10%, and considering the convenience of material source, the ammonia water can be saturated ammonia water.

[0028] As preferred, the volume ratio of the ammonia water and the high-iron zinc leaching solution is greater than or equal to 1, and further greater than or equal to 1.5; considering the treatment cost and effect, it is further preferred to be 1.8-3:1, and further preferred to be 2-2.2:1.

[0029] As preferred, the temperature of the separation reaction stage is 50-100 DEG C, and considering the treatment effect and process cost, it is further preferred to be 60-80 DEG C. Under the preferred dosage and temperature, the separation effect of iron and zinc can be further improved in a synergistic manner, and the adsorption performance of the prepared material on pollutants such as Tl can be improved.

[0030] As preferred, acid is added to the iron-zinc-removed solution to perform a second precipitation reaction, and solid-liquid separation is performed to obtain a zinc precipitate and an ammonium salt solution;

[0031] Preferably, the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid; and further, in order to obtain a more pure and single ammonium salt solution, sulfuric acid is selected as the precipitant;

[0032] Preferably, the pH at the end point of the second precipitation reaction is 4.5-7, and can further be 5-5.5.

[0033] The application further provides an iron-based adsorbent prepared by the method.

[0034] The application further provides an application of the iron-based adsorbent prepared by the method, which is used as a thallium adsorption material.

[0035] Preferably, the iron-based adsorbent is used as a thallium adsorption material to adsorb thallium in a solution.

[0036] The application has found that the iron-based adsorbent recovered by the solid waste treatment method can unexpectedly exhibit excellent thallium adsorption capacity.

[0037] Advantages

[0038] The application is innovatively based on the efficient and high-selective controllable leaching of zinc-iron solid waste by countercurrent acid leaching process, and further cooperates with the subsequent reduction and ammonia precipitation process and the control of treatment conditions, so as to realize synergy, improve the recovery rate and separation selectivity of iron and zinc, and research finds that the recovery rate of iron and zinc is more than 90%, and the zinc is basically not lost in the process of precipitating iron, and has excellent selectivity. Moreover, the phase, morphology and structure of the obtained iron material can be selectively regulated, so that the iron material has excellent thallium adsorption performance.

[0039] The application has small investment and simple process, and the comprehensive recovery of zinc-iron solid waste can be realized only by using a conventional reaction kettle, a filter press and an electromagnet, and no difficult-to-handle waste residue and waste water are generated. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 It is a countercurrent leaching flowchart of Example 1;

[0041] Figure 2 It is a zinc-iron solid waste treatment flowchart;

[0042] Figure 3 It is an XRD chart of zinc-iron solid waste, mainly zinc ferrite;

[0043] Figure 4 It is a countercurrent leaching flowchart;

[0044] Figure 5 It is an XRD chart of the iron-based adsorbent prepared in Example 1;

[0045] Figure 6 It is a product chart prepared in Comparative Example 3; DETAILED DESCRIPTION

[0046] It should be noted that the described examples are only a part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0047] The present application provides a new comprehensive recovery method for treating zinc-iron solid waste, which is used for treating zinc-iron solid waste generated in zinc smelting industry with a zinc content of 15-30%, an iron content of 15%-35% and a main phase of zinc ferrite, including one or several solid wastes such as leaching residue of zinc leaching process, iron precipitation residue of each liquid purification process and mixtures thereof. An embodiment of the method comprises the following steps:

[0048] Step 1, efficient leaching

[0049] The multi-stage countercurrent leaching method is used, and dilute sulfuric acid is selected as the leaching agent. The movement direction of the leached material and the leaching agent is opposite, that is, the material depleted after several times of leaching is in contact with the new leaching solution, and the original leached material is in contact with the leaching solution, as shown in the accompanying drawings. Figure 1 .

[0050] Preferably, the concentration of dilute sulfuric acid is 1-4 mol / L; in order to reduce the treatment cost of solid waste, leaching is carried out at room temperature; the number of leaching stages can be adjusted according to the type of residue, and the preferred number of leaching stages is 2-5.

[0051] The leaching rate of zinc and iron can reach more than 90%, and the leaching solution mainly contains zinc sulfate and iron sulfate (containing 20-100 g / L of zinc and 30-100 g / L of iron).

[0052] Step two, zinc-iron separation:

[0053] Due to the characteristics of zinc-iron solid waste raw materials, the leaching solution obtained in step one has the characteristics of low zinc and high iron (more than 30 g / L).

[0054] A reducing agent is added to the leaching solution obtained in step one (containing 20-100 g / L of zinc and 30-100 g / L of iron), and the n(Fe 3+ ):n(Fe 2+ ) in the solution is controlled to be close to 2:1 (such as 1.9-2.1:1). Then ammonia water is quickly added, and stirring is carried out to carry out iron-zinc separation reaction. Then solid-liquid separation is carried out to obtain an iron-based adsorbent and an iron-removed solution. In the solid-liquid separation stage, the solid-liquid separation process can be accelerated by applying an electromagnet at the bottom of the container. With the aid of the electromagnetic device, the separation efficiency of the solid-liquid separation process can be greatly improved.

[0055] Preferably, the reducing agent can be iron powder Fe, zinc powder Zn, ZnS, ZnSO3, etc. The amount of the reducing agent added should be 1.0-1.5 times the theoretical amount (just enough to make the reduced solution n(Fe 3+ ):n(Fe 2+ )=2:1). The reaction temperature of the reduction reaction can be 15-95℃, and the reaction time can be 15-60 min. The amount of ammonia water added is 0.5-2.0 times the volume of the solution to be treated. The reaction temperature is 50-100℃, and the reaction time is 15-150 min.

[0056] Through step two, an iron-removed solution with pH≥10 can be obtained, which is acidified and precipitated to obtain a zinc product.

[0057] Step three, preparation of high-purity zinc hydroxide:

[0058] Sulfuric acid is added to the iron-removed solution obtained in step two to make the pH of the solution about 5-7, and white zinc hydroxide precipitate and ammonium sulfate solution are obtained.

[0059] Step four, preparation of iron-based adsorbent:

[0060] The iron-based adsorbent obtained in step two is immersed with distilled water for more than 3 times, dried at 40-100℃ for 4-24h, the obtained solid powder is ground through 100-200 mesh sieve, sealed for standby, and can be used as thallium removal adsorbent for treating thallium-containing wastewater. The iron-based adsorbent obtained from solid waste recycling has unexpectedly excellent thallium adsorption performance.

[0061] The specific embodiments of the present application are as follows:

[0062] Example 1

[0063] In this embodiment, the treated zinc-iron solid waste comes from a mixed zinc-iron slag of a zinc smelting enterprise in Hunan, which is a mixture of leaching slag and iron-removed slag. After drying at 80℃ for 24h and crushing through 200 mesh sieve, the phase composition analysis is carried out, and the XRD pattern and ICP analysis results are shown in FIG. 1 and Table 1 respectively. The composition of the waste iron slag is relatively complex, the main phase is zinc ferrite ZnFe2O4, the main elements are Zn (20.9%) and Fe (20.8%), in addition to this, it also contains Pb (3.66%), Mn (1.72%), Si (1.7%), Ca (1.05%) and the like. Figure 3

[0064] Step one, efficient leaching: The experiment uses 3M dilute sulfuric acid as leaching solution, takes 200mL each time, and the solid ratio of leaching solution is 2:1. The four-stage countercurrent leaching method shown in FIG. 2 is adopted. The more specific operation is shown in FIG. 3, in which the orange arrow represents the flow direction of the leaching solution, and the blue arrow represents the flow direction of the iron slag. The leaching slag of experiment ① is reacted with fresh leaching solution again as experiment ②, the filtrate of experiment ② is reacted with the iron slag without leaching reaction as experiment ④, and so on. When filtering, a small amount of deionized water is used to rinse the filter cake, and the total volume of the rinsing liquid and the filtrate is made constant to 200mL, and 0.5mL of the mixed solution is taken for ICP analysis. Through the multi-stage countercurrent leaching method, the zinc leaching rate of 95% and the iron leaching rate of 92% are obtained, and the composition of the obtained leaching solution is shown in Table 2, the zinc concentration is 80.28g / L, the iron concentration is 71.43g / L (which belongs to high-iron solution), in addition to this, it also contains impurity elements such as Al, As, Ca, Cd, Cu, Mg, Mn, Na and the like.

[0065] Figure 1 Figure 4

[0066]

[0067] Step two, zinc-iron separation: ​​​

[0068] Each group of 50 mL of the leaching solution obtained in step one is reduced by adding iron powder / zinc powder (see Table 3 for the amount), and is reacted in a water bath at a certain temperature for 0.5 h, and the reaction temperature is shown in Table 3. Then a certain amount of ammonia water is quickly added, and the reaction is stirred in a water bath for 0.5 h. The precipitate (iron-based adsorbent) collected at the bottom of the beaker by an external magnet is detected by ICP, and the concentration of the filtrate is calculated to obtain the iron removal rate and the zinc loss rate, and the experimental results are shown in Table 3.

[0069] It can be known from the experimental results that the new process designed by the application has good zinc-iron separation performance, the most important factor affecting the iron removal rate and the zinc loss rate is the amount of ammonia water added, and under the optimal conditions obtained in the experiment, the iron removal rate of 99.5% and the zinc loss rate close to 0% can be obtained. The composition of the post-iron precipitation solution obtained under the optimal process conditions is shown in Tables 3-4, and it can be known that the process has excellent zinc-iron separation effect while also having good removal effect on harmful elements such as As. The precipitate obtained by the process is a black solid with magnetism, and the XRD diagram measured after drying and grinding is shown in FIG. 2, and it can be known that the precipitate is magnetite. Moreover, according to the experimental results, it is found that under the experimental conditions that the amount of ammonia water added is more than 0.5 times the volume of the solution to be treated, preferably 1-3 times, and further preferably 2-2.5 times, and the reaction temperature is 50-100℃, the change of the experimental conditions has little effect on the iron removal rate, and the increase of the amount of ammonia water added and the decrease of the precipitation reaction temperature are both beneficial to the stability of zinc in the solution, thereby being more beneficial to the selective precipitation of iron. Figure 5

[0070] Step three: preparation of high-purity zinc hydroxide:

[0071] Sulfuric acid is added dropwise to the mixed solution obtained in the experiment of step two numbered S1-9 until the pH of the solution is 5.0, and white zinc hydroxide precipitate and ammonium sulfate solution are obtained. The white precipitate is washed with distilled water for 3 times, dried at 80℃ for 12 h, ground through a 200 mesh sieve, and sealed for storage. The sample is dissolved and diluted with aqua regia, and ICP analysis is performed, and it is found that the impurity content of the zinc hydroxide product obtained in this step is extremely low, and no other impurities are detected by the instrument.

[0072] Step four: preparation of iron-based adsorbent:

[0073] The precipitate (iron-based adsorbent) obtained in the experiment numbered S1-9 in step two is immersed and washed with distilled water for 3 times, and is dried at 40℃ for 24 h. The obtained solid powder is ground through a 200 mesh sieve.

[0074] Fifth step: Tl adsorption

[0075] Tl adsorption performance verification is performed on the iron-based adsorbent prepared in the fourth step: ​

[0076] The iron-based adsorbent was used for the treatment of actual industrial wastewater (pH 12, Tl content 62 μg / L), the amount of adsorbent was 5-50 g / L (see Table 7), the treatment temperature was room temperature, and the treatment time was 15 min.

[0077] Comparative Example 1

[0078] The zinc-iron solid waste treated in this comparative example was consistent with Example 1. In this comparative example, 3M dilute sulfuric acid was used as the leaching liquid, and the effects of different liquid-solid ratios on the leaching rate and the zinc and iron concentrations in the leaching liquid were studied. The experimental results are shown in Table 5. According to the experimental results, this method either has a low leaching rate that cannot meet the recovery requirements or has a low zinc and iron concentration in the leaching liquid that is not conducive to further recycling.

[0079] Comparative Example 2

[0080] The zinc-iron solid waste treated in this comparative example was consistent with Example 1. In this comparative example, a hydrothermal tank was used as the reaction container, 3M dilute sulfuric acid and zinc-iron solid waste were fully mixed according to a certain liquid-solid ratio, the hydrothermal tank was tightly sealed, and the leaching reaction was carried out at different temperatures for 2 h. After the reaction container was cooled to room temperature, it was opened, filtered, and the zinc and iron concentrations in the filtrate were detected by ICP and the leaching rate was calculated. The experimental results are shown in Table 6. By high temperature and high pressure, the leaching rate can be effectively improved, but it still cannot meet the demand of efficient zinc recovery. The highest zinc leaching rate obtained by this method is 87%, but at this time the leaching liquid concentration is low and the system liquid volume is large, which is not conducive to zinc recovery.

[0081] Comparative Example 3

[0082] In this comparative example, the zinc-iron solid waste treated was consistent with Example 1, Step 1 was consistent with Example 1, and the leaching liquid obtained was consistent with Example 1.

[0083] In Step 2, neutralization precipitation method, goethite method, and jarosite method were used to remove iron from the leaching liquid, but during the experiment, the experimental phenomena shown in the above were all appeared, the solution system was yellow-brown sticky paste, and further recovery work could not be carried out. Figure 6

[0084] Comparative Example 4

[0085] Compared with Example 1, the only difference is that in the fifth step, the adsorbent used is a commercially available chemical product, ferric oxide (Aladdin, 99%).

[0086] Comparative Example 5

[0087] ​The difference compared with Example 1 is only that the adsorbent is changed in the fifth step, and the preparation steps of the adsorbent of the present comparative example are as follows: 100 mL of a solution containing Fe 2+ = 23.3 g / L, Fe 3+ = 46.6 g / L is prepared and heated to 90 DEG C, 100 mL of ammonia water is rapidly added, the reaction is carried out for 0.5 h, the precipitate is attracted to the bottom by a magnet, and the precipitate is immersed in distilled water for 3 times, and then dried at 40 DEG C for 24 h, and the obtained solid powder is ground through a 200-mesh sieve.

[0088] Comparative Example 6

[0089] The difference compared with Example 1 is only that the reaction temperature (T1) is changed to constant 45 DEG C in the second step, and other experimental conditions are consistent with the experiment numbered S1-9, the obtained iron removal rate is 94.41%, the zinc loss rate is 35.87%, and the precipitate is yellow-brown, and the solid-liquid separation performance is obviously worse than that of Example 1, whether the electromagnetic device is assisted or the ordinary standing settlement, suction filtration or pressure filtration, the separation speed is very slow. The obtained precipitate is immersed in distilled water for 3 times, and then dried at 40 DEG C for 24 h, and the obtained solid powder is ground through a 200-mesh sieve. The Tl adsorption performance of the iron-based adsorbent prepared in the present comparative example is verified, and the treated wastewater is consistent with Example 1.

[0090] The Tl adsorption effects of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6 are shown in Table 7:

[0091]

[0092] The solid waste-based iron adsorbent material obtained by the method of the present application can unexpectedly obtain better Tl adsorption performance.

Claims

1. A method for treating zinc-iron solid waste and simultaneously producing iron-based adsorbent, characterized in that, Zinc-iron solid waste is subjected to countercurrent acid leaching to obtain iron-zinc leachate; a reducing agent is added to the iron-zinc leachate for reduction reaction, and then ammonia water is added for selective precipitation reaction. After solid-liquid separation, an iron-based adsorbent and an iron-zinc removal solution are obtained. The zinc-iron solid waste is zinc smelting slag, which contains zinc ferrite and at least one impurity selected from Pb, Mn, Mg, Al, Na, and Cu. The reducing agent is at least one of iron powder, zinc powder, ZnS, and ZnSO3; the molar ratio of the reducing agent to Fe in the iron-zinc leaching solution is 1:1 to 10. The volume ratio of the ammonia water to the iron-zinc leachate is greater than or equal to 0.5; The temperature of the selective precipitation reaction stage is greater than or equal to 50℃.

2. The method as described in claim 1, characterized in that, The zinc-iron solid waste also contains at least one phase component selected from Fe2O3, ZnO, FeOOH, CaSO4, ZnSO4, Fe(OH)3, and KFe3(SO4)2(OH)6.

3. The method as described in claim 2, characterized in that, The zinc-iron solid waste contains more than 15 wt.% zinc and more than 15 wt.% iron.

4. The method as described in claim 1, characterized in that, The acid solution used in the countercurrent acid leaching stage is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

5. The method as described in claim 4, characterized in that, The concentration of the acid solution is 1~4M.

6. The method as described in claim 1, characterized in that, The countercurrent acid leaching stages are 2 to 5.

7. The method as described in claim 1, characterized in that, In the iron-zinc leachate, the Fe concentration is greater than 30 g / L and the Zn concentration is greater than or equal to 15 g / L.

8. The method as described in claim 1, characterized in that, The temperature for the reduction reaction is 15~95℃.

9. The method as described in claim 1, characterized in that, The ammonia solution mentioned is saturated ammonia solution.

10. The method as described in claim 1, characterized in that, The volume ratio of the ammonia water to the iron-zinc leachate is greater than or equal to 1.

11. The method as described in claim 10, characterized in that, The volume ratio of the ammonia water and the iron-zinc leachate is greater than or equal to 1.

5.

12. The method as described in claim 11, characterized in that, The volume ratio of ammonia water to iron-zinc leachate is 1.8 to 3.

13. The method as described in claim 12, characterized in that, The volume ratio of ammonia water to iron-zinc leachate is 2 to 2.

2.

14. The method as described in claim 1, characterized in that, The temperature for selective precipitation reaction is 50~100℃.

15. The method as described in claim 14, characterized in that, The temperature for selective precipitation reaction is 60~80℃.

16. The method according to any one of claims 1 to 15, characterized in that, Acid was added to the iron and zinc removal solution to carry out a second precipitation reaction, and the solid and liquid were separated to obtain zinc precipitate and ammonium salt solution; The acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid; The pH at the endpoint of the second precipitation reaction is 4.5~7.

0.

17. An iron-based adsorbent prepared according to any one of claims 1 to 16.

18. An application of an iron-based adsorbent prepared according to any one of claims 1 to 16, characterized in that, Iron-based adsorbents were used as thallium adsorbents.

19. The application as described in claim 18, characterized in that, Iron-based adsorbents were used as thallium adsorbents to adsorb thallium in solution.

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