Method for resourceful treatment of heavy metal gypsum sludge and secondary zinc oxide smoke dust

Abstract

The invention discloses a method for resourceful treatment of heavy metal gypsum sludge and secondary zinc oxide smoke dust, and belongs to the technical field of solid waste resourceful utilization. Grinding and mixing the heavy metal gypsum sludge, the secondary zinc oxide smoke dust and a carbonaceous reducing agent, and roasting to obtain a roasted material containing ZnS and CaO; the roasted material is leached through hydrochloric acid, and zinc sulfide enriched slag and leachate are obtained; according to the method, the volatilization rates of toxic elements fluorine, chlorine and arsenic in the solid waste raw materials reach 97.22%, 97.28% and 98.41% respectively, the vulcanization rate of zinc reaches 96.89%, the recovery rates of zinc sulfide and calcium oxide can reach 98% or above, and the technical problems that a vulcanizing agent needs to be added in the vulcanization roasting process, and the recovery rate of valuable metal is low are solved.

Description

Technical Field

[0001] The invention relates to a secondary zinc oxide smoke recovery method, in particular to a method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke, belonging to the technical field of industrial solid waste resource utilization. Background Art

[0002] Zinc oxide dust is a secondary resource containing zinc, but it contains a large amount of valuable metals and toxic elements, such as Pb, Zn, Cu, Fe, Bi, F, Cl, As, etc., and is also a hazardous waste. It mainly comes from the flue dust produced by the volatilization of rotary kilns and flue furnaces during the lead and zinc smelting process, as well as the blast furnace and converter dust produced during the steel smelting process. At present, the main methods for treating zinc oxide are landfill, hydrometallurgical process and pyrometallurgical process. The landfill method can avoid the large accumulation of secondary zinc oxide flue gas, but it will cause serious pollution to the soil environment and groundwater quality, and cause waste of resources. The commonly used methods for the pyrometallurgical treatment of secondary zinc oxide are rotary kiln roasting and multi-layer furnace roasting, which are mainly to remove harmful elements such as F and Cl in the secondary zinc oxide that are not conducive to zinc electroplating. The hydrometallurgical process mainly uses acidic and alkaline solvents to dissolve, purify, precipitate and calcine the metal oxides (ZnO, PbO, etc.) in the secondary zinc oxide dust. Leaching media such as sulfuric acid and hydrochloric acid are usually used to achieve efficient leaching of elements in their equivalent state, such as Zn, Pb, and Cu, but they can also lead to the leaching of impurity elements such as Fe, F, Cl, and As. Subsequently, a highly selective extractant is required to purify the valuable metals. In addition, some researchers have recovered valuable metals such as Zn, Pb, and Cu by microbial-assisted leaching, but there are disadvantages such as low leaching efficiency and long reaction time. Therefore, there is an urgent need to develop new methods for recovering secondary zinc oxide dust.

[0003] In recent years, the sulfidation roasting-flotation method has been widely used to extract valuable metals from zinc-containing secondary resources. Chinese patent CN 110983029A proposes a method for the coordinated sulfidation roasting of lead-zinc smelting slag and gypsum slag, which specifically uses sulfidation roasting to convert the lead and zinc valuable metals in the slag into lead-zinc sulfides, reduces and volatilizes the arsenic in the slag and enriches it in the smoke, and the compounds of calcium, silicon and iron are converted into calcium silicate and calcium ferrite, and then the lead and zinc sulfides in the resulting reduced sulfidation roasting slag are recovered by conventional flotation. The patent only mentions the sulfidation roasting process, and the specific subsequent flotation process is not mentioned. In fact, the sulfides obtained by the conventional sulfidation roasting process have a small grain size and poor crystal surface structure, which cannot meet the requirements of conventional flotation for mineral particles; moreover, the flotation process cannot achieve efficient separation of sulfidation products, and the floated products still need to be processed by pyrometallurgy or hydrometallurgy, which has a long process and does not meet the requirements of today's industrial production. For example, Chinese patent CN106755961A proposes a method for recovering lead and zinc from difficult-to-treat zinc oxide materials by stepwise sulfidation roasting-flotation. Finally, a zinc concentrate with a grade of 37.6% and a recovery rate of 81.5% and a lead concentrate with a grade of 54% and a recovery rate of 87.6% are obtained through a sulfidation roasting and flotation process.

[0004] The current sulfiding roasting-flotation technology used in the secondary zinc resource recovery process has the following problems: the need to add sulfiding agents (sulfur, calcium sulfide, iron sulfide, etc.), the small particle size of the sulfidation product, the slightly water-soluble calcium oxide or water-soluble calcium salt in the product is not conducive to flotation separation, the flotation efficiency is low, the floated products still need to be processed by pyrometallurgical or wet process, the process is long, the cost is high, and it does not meet the requirements of today's industrial production. These are technical problems that need to be improved. Summary of the invention

[0005] In view of the difficulties that the sulfidation roasting-flotation technology in the prior art is difficult to achieve efficient recovery of valuable metals in secondary zinc oxide, and the flotation products still need to be treated by pyrometallurgical or hydrometallurgical processes, need to add sulfiding agents (sulfur, calcium sulfide, iron sulfide, etc.), have long processes, high costs, and do not meet the requirements of current industrial production, the purpose of the present invention is to provide a method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke. The method uses the idea of ​​"treating waste with waste" and uses the high content of calcium sulfate in the heavy metal gypsum sludge as a sulfiding agent. During the reduction roasting process, the elemental zinc in the heavy metal gypsum sludge and the secondary zinc oxide is selectively sulfided into acid-insoluble zinc sulfide, while the calcium is converted into calcium oxide, which is a poisonous element; the roasting product is subjected to low-acid autothermal leaching to efficiently separate zinc sulfide and calcium oxide, thereby realizing the green comprehensive utilization of heavy metal gypsum sludge and secondary zinc oxide, overcoming the technical problems of the prior art that a sulfiding agent needs to be added, the flotation efficiency is low, the flotation products still need to be treated by pyrometallurgical or hydrometallurgical processes, have long processes, and high costs.

[0006] In order to achieve the above technical objectives, the present invention provides a method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust, the method comprising the steps of grinding and mixing heavy metal gypsum sludge, secondary zinc oxide dust and a carbonaceous reducing agent and then roasting to obtain a roasting material containing ZnS and CaO; leaching the roasting material with hydrochloric acid to obtain zinc sulfide enriched slag and a leachate; and evaporating and concentrating the leachate to obtain calcium chloride.

[0007] The present invention roasts heavy metal gypsum sludge, secondary zinc oxide smoke and a carbonaceous reducing agent. During the roasting process, the poisonous elements F, Cl and As are mainly removed by volatilization, while ZnO and CaSO4 are directionally converted into ZnS and CaO. The two can be separated by low-acid autothermal leaching to achieve ZnS and CaO, and calcium oxide is leached by hydrochloric acid to obtain a calcium chloride byproduct.

[0008] The specific reaction of the roasting process of the present invention is as follows:

[0009] CaSO4+2C=CaS+2CO2(g) (1)

[0010] ZnO+CaSO4+2C=CaO+ZnS+2CO2(g) (2)

[0011] ZnO+CaS=CaO+ZnS (3)

[0012] The specific reaction of the leaching process of the present invention is as follows:

[0013] CaO+H2O=Ca(OH)2 (4)

[0014] Ca(OH)2+2HCl=CaCl2+2H2O (5)

[0015] The innovative points of the present invention are as follows: 1. utilizing the innovative idea of ​​"treating waste with waste", utilizing calcium sulfate in heavy metal gypsum sludge as the sulfiding agent required in the sulfidation roasting process, without the need to add an additional sulfiding agent; 2. realizing the directional conversion of elemental zinc and calcium into zinc sulfide and calcium oxide respectively during the sulfidation roasting process, thereby providing a basis for subsequent acid leaching separation; 3. separating zinc sulfide and calcium oxide through a low-acid self-heating leaching process, wherein the self-heating is manifested in that calcium oxide reacts with water to release a large amount of heat, and subsequent dripping of concentrated hydrochloric acid can also generate a large amount of heat, without the need to add an additional heat source; 4. dripping the hydrochloric acid in a dripping manner, which can continuously generate heat and strengthen leaching; 5. obtaining a calcium chloride byproduct through evaporation and crystallization of the filtrate after the acid leaching, thereby realizing the recovery of the calcium source.

[0016] As a preferred solution, the mass ratio of the heavy metal gypsum sludge to the secondary zinc oxide dust is m (重金属石膏污泥) :m (二次氧化锌烟尘)=1~3. The main component of heavy metal gypsum sludge is calcium sulfate, while the main component of secondary zinc oxide dust is zinc oxide. The ratio of heavy metal gypsum sludge to secondary zinc oxide dust can be determined based on the ratio of calcium sulfate and zinc oxide contained therein. The minimum dosage of heavy metal gypsum sludge should ensure that all zinc oxide in the secondary zinc oxide dust is converted into zinc sulfide, but excessive dosage of heavy metal gypsum sludge will lead to partial calcium sulfidation. The mass ratio of heavy metal gypsum sludge to secondary zinc oxide dust is further preferably m(heavy metal gypsum sludge):m(secondary zinc oxide dust)=1.2~1.4. The main components and mass contents in heavy metal gypsum sludge are: CaSO4 55~80%, ZnO1~5%, fluorine-containing compounds 1%~5%, chlorine-containing compounds 1~5%, and As-containing compounds 1~5%. The main components and mass contents of the secondary zinc oxide are: ZnO 50-70%, zinc sulfate ≤5%, fluorine-containing compounds 2%-5%, chlorine-containing compounds 1-5%, and As-containing compounds 2-5%.

[0017] As a preferred solution, the amount of the carbonaceous reducing agent is 10% to 30% of the total mass of the heavy metal gypsum sludge and the secondary zinc oxide dust. When the mass ratio of the carbonaceous reducing agent is too high, zinc will be reduced to a metal element and volatilized and lost. If the mass ratio of the carbonaceous reducing agent is too low, it will not only be unfavorable for the sulfidation of zinc, but also lead to the overflow of sulfur dioxide gas. The amount of the carbonaceous reducing agent is further preferably 20% to 30% of the total mass of the heavy metal gypsum sludge and the secondary zinc oxide dust. The carbonaceous reducing agent is, for example, carbon powder.

[0018] As a preferred solution, the calcination conditions are: under a protective atmosphere, the calcination temperature is 500-900°C, and the calcination time is 30min-180min. The calcination temperature is further preferably 650-750°C. The calcination time is further preferably 60min-120min. As a more preferred solution, the protective atmosphere includes an inert gas and / or nitrogen, and the flow rate of the inert gas and / or nitrogen is 0.1-3L / min. The inert gas is, for example, argon. The flow rate of the inert gas and / or nitrogen is further preferably 0.5-2L / min; most preferably 0.8-1.5L / min. The introduction of flowing inert gas or nitrogen can not only isolate oxygen, but also facilitate the volatilization of harmful substances during the calcination process. As the calcination temperature increases, it is beneficial to the progress of reactions (1)-(3) and the volatilization of poisonous elements, but too high a calcination temperature easily leads to the decomposition of calcium sulfate to produce sulfur dioxide, which cannot fully sulfide the zinc oxide and also causes environmental pollution. Similarly, a suitable roasting time is conducive to the progress of reactions (1) to (3) and the volatilization of poisonous elements, so that calcium sulfate and zinc oxide are fully converted into calcium oxide and zinc sulfide. However, if the roasting time is too long, it will also increase the cost and be unfavorable for production.

[0019] As a preferred solution, the leaching adopts a low-acid self-heating leaching method: after the roasted material is added to water for digestion reaction, concentrated hydrochloric acid is slowly added under stirring for leaching. During the digestion reaction, calcium is selectively converted into calcium hydroxide by the reaction between calcium oxide and water. At the same time, the reaction is an exothermic reaction. A large amount of heat is beneficial to the subsequent leaching process. Then concentrated hydrochloric acid is slowly added for leaching. Concentrated hydrochloric acid added to water will also generate heat. The slow addition of concentrated hydrochloric acid can ensure that the temperature of the leaching system is relatively stable on the one hand. On the other hand, too fast addition of concentrated hydrochloric acid will lead to excessive local acid concentration and overheating, which is not conducive to the selective conversion of calcium hydroxide.

[0020] As a preferred solution, the digestion reaction time is 1 to 5 minutes.

[0021] As a preferred solution, the leaching conditions are: slurry concentration of 50-150g / L, stirring speed of 50-150r / min, slurry acid concentration of 25g / L-100g / L, and concentrated hydrochloric acid addition time of 20-60min. The slurry concentration is further preferably 50-100g / L. The slurry acid concentration is further preferably 25g / L-50g / L. The concentrated hydrochloric acid addition time is further preferably 30-45min. At an appropriate acid concentration, it can be ensured that calcium hydroxide is completely converted into calcium chloride, and at the same time the solubility of calcium chloride can be ensured, which is conducive to the efficient separation of zinc sulfide and calcium chloride. However, the acidity cannot be too high, as excessive acidity will cause partial zinc leaching.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] 1) The present invention is the first to propose a co-sulfurization roasting-low-acid autothermal leaching process for the secondary zinc oxide dust, which realizes the directional conversion of zinc and calcium elements in the heavy metal gypsum sludge and the secondary zinc oxide dust into ZnS and CaO, and simultaneously realizes the selective leaching of calcium oxide.

[0024] 2) The present invention utilizes the idea of ​​treating waste with waste to achieve the coordinated disposal of heavy metal gypsum sludge and secondary zinc oxide smoke, thereby realizing the resource utilization of the two solid wastes.

[0025] 3) The process of the present invention is simple, has low energy consumption, and less pollution, and is conducive to industrial production.

[0026] In summary, the present invention proposes a "waste-to-waste" treatment scheme for heavy metal gypsum sludge and secondary zinc oxide dust for the first time. The removal rate of poisonous elements F, Cl, and As reaches more than 97% through the co-sulfurization roasting-low-acid autothermal leaching process, and the zinc and calcium elements are directionally converted into ZnS and CaO, respectively. The zinc sulfidation rate reaches 96.89%, and the recovery rates of ZnS and CaO reach more than 99%. The problem of green comprehensive utilization of heavy metal gypsum sludge and secondary zinc oxide is solved, and the efficient separation and recovery of zinc oxide is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a process flow chart for the resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke.

[0028] Figure 2 This is the XPS spectrum of zinc in the secondary zinc oxide of Example 1.

[0029] Figure 3 This is the XPS spectrum of sulfur in the heavy metal gypsum sludge of Example 1.

[0030] Figure 4 This is the XPS spectrum of zinc in the medium-acid leaching residue of Example 1.

[0031] Figure 5 This is the XPS spectrum of sulfur in the acid leaching residue in Comparative Example 1.

[0032] Figure 6 This is the XRD pattern of the sulfurized calcined product of Example 1. DETAILED DESCRIPTION

[0033] The present invention will be described below in conjunction with the embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0034] Example 1

[0035] The raw materials are heavy metal gypsum sludge and secondary zinc oxide dust obtained from a lead-zinc smelter of a new energy enterprise in Hunan. The main components of the heavy metal gypsum sludge are shown in Table 1, and the main components of the secondary zinc oxide are shown in Table 2. XPS was used to analyze the existence forms of zinc and sulfur in the raw materials. The analysis results are as follows Figure 2 , Figure 3 As shown, according to Figure 2 and Figure 3 It can be concluded that the sulfur in heavy metal gypsum mainly exists in the form of calcium sulfate, and the zinc in secondary zinc oxide smoke mainly exists in the form of zinc sulfide.

[0036] Table 1 Analysis results of chemical composition of heavy metal gypsum sludge.

[0037]

[0038] Table 2 Chemical composition analysis results of secondary zinc oxide.

[0039]

[0040] according to Figure 1 The specific treatment process of heavy metal gypsum sludge and secondary zinc oxide dust includes the following steps:

[0041] S1. The heavy metal gypsum sludge and secondary zinc oxide to be treated are firstly proportioned, and then carbon powder is added and ground evenly. Specifically, m (heavy metal gypsum sludge): m (secondary zinc oxide dust) = 1.4, and the amount of carbon powder is 30%.

[0042] S2. The ground mixture is subjected to a co-sulfurization roasting treatment at a roasting temperature of 700° C., nitrogen is an inert gas, the inert gas flow rate is 1 L / min, and the roasting time is 90 min to obtain a sulfurized roasting product and a volatile product (a mixture of F, Cl, and As), wherein the sulfurization rate of zinc reaches 96.89%, and the volatilization rates of F, Cl, and As reach 97.22%, 97.28%, and 98.41%, respectively.

[0043] S3. The obtained sulfurized roasted solid product is subjected to low-temperature autothermal acid leaching, the slurry concentration is controlled to be 100 g / L, the stirring speed is 100 r / min, the solution acidity is controlled to be 30 g / L, and the concentrated hydrochloric acid addition time is controlled to be 40 min. Note that the concentrated hydrochloric acid should be added immediately after the water is added to the beaker containing water for 1 min.

[0044] S4, filtering the slurry after the low-temperature autothermal leaching reaction to obtain a filter residue and a filtrate;

[0045] S5. Dry the separated filter residue to obtain solid ZnS. The filtrate is evaporated and crystallized at 150°C for 30 min to obtain CaCl2. The recovery rates of zinc sulfide and calcium oxide are 98.21% and 98.46%, respectively. The XPS results of zinc and sulfur in the zinc sulfide product are as follows: Figure 4 and Figure 5 shown.

[0046] Example 2

[0047] Example 1 was repeated, except that m(heavy metal gypsum sludge):m(secondary zinc oxide dust)=1.2 in S1, and the other conditions remained unchanged. The results showed that the recovery rate of zinc sulfide obtained by low-acid autothermal leaching was 90.86%, indicating that increasing m(heavy metal gypsum sludge) is conducive to more complete sulfidation of zinc element during the co-sulfidation roasting process, thereby improving the sulfidation rate of zinc.

[0048] Example 3

[0049] Example 1 was repeated, except that m(heavy metal gypsum sludge):m(secondary zinc oxide dust) in S1 = 1.5, and the other conditions remained unchanged. The results showed that the recovery rate of zinc sulfide obtained by low-acid autothermal leaching was 97.01%, indicating that further increasing m(heavy metal gypsum sludge) was not very meaningful in improving the zinc sulfide rate.

[0050] Example 4

[0051] Example 1 was repeated, except that the amount of carbon powder was 25%, and the other conditions remained unchanged. It was found that the zinc sulfidation rate was only 92.5%. Compared with Example 1, it was shown that the addition of carbon powder was beneficial to the conversion of calcium sulfate in the heavy metal gypsum slag into calcium sulfide, thereby promoting the sulfidation of zinc and thus improving the zinc sulfidation rate.

[0052] Example 5

[0053] Example 1 was repeated, except that the amount of S1 and carbon powder was 35%, and the other conditions remained unchanged. It was found that the zinc vulcanization rate was 96.88%. Compared with Example 1, it was shown that continuing to add carbon powder had little significance in improving the zinc vulcanization rate.

[0054] Example 6

[0055] Example 1 was repeated, except that S2 and the calcination temperature were 650°C, and the other conditions remained unchanged. The results showed that the sulfidation rate of zinc was 93.89%, and the volatilization rates of F, Cl, and As were 92.21%, 92.55%, and 93.32%, respectively, which indicated that increasing the temperature was beneficial to improving the sulfidation rate of zinc and the volatilization rates of F, Cl, and As.

[0056] Example 7

[0057] Example 1 was repeated, with the only difference being that S2 and the roasting temperature were 750°C, and the other conditions remained unchanged. The results showed that the sulfidation rate of zinc was 95.49%, and the volatilization rates of F, Cl, and As were 97.23%, 97.35%, and 98.45%, respectively, which indicated that increasing the temperature may cause the calcium sulfate in the heavy metal gypsum sludge to decompose and produce sulfur dioxide gas and calcium oxide, resulting in a decrease in the sulfidation rate of zinc, while the volatilization rates of F, Cl, and As did not change much. Therefore, it is not very meaningful to continue to increase the roasting temperature.

[0058] Example 8

[0059] Example 1 was repeated, with the only difference being that the flow rate of inert gas S2 was 0.5 L / min, and the vulcanization rate of zinc was 92.25%. This indicates that the flow rate of inert gas is too small, which will allow air to enter and consume carbon powder, thereby failing to fully vulcanize zinc and resulting in a low vulcanization rate.

[0060] Example 9

[0061] Example 1 was repeated, with the only difference being that the flow rate of inert gas S2 was 1.2 L / min, and the sulfidation rate of zinc was 96.98%. This shows that further increasing the flow rate of inert gas is not very meaningful in increasing the sulfidation rate of zinc.

[0062] Example 10

[0063] Example 1 was repeated, with the only difference being that S2 and the roasting time were 60 min. The results showed that the sulfidation rate of zinc was only 94.87%, and the volatilization rates of F, Cl, and As were only 94.28%, 95.02%, and 95.78%, respectively. This indicates that extending the roasting time is beneficial to the full sulfidation of zinc and the full volatilization of the poisonous elements F, Cl, and As.

[0064] Embodiment 11

[0065] Example 1 was repeated, with the only difference being that S2 and the roasting time were 100 min. The results showed that the sulfidation rate of zinc was only 96.85%, and the volatilization rates of F, Cl, and As were 97.21%, 97.26%, and 98.39%, respectively. This indicates that further extending the roasting time is not very meaningful in improving the sulfidation rate of zinc and the volatilization rates of the poisonous elements F, Cl, and As.

[0066] Example 12

[0067] Example 1 was repeated, except that: S3, the solution acidity was 25 g / L, and the other conditions remained unchanged. The results showed that the recovery rates of zinc sulfide and calcium oxide were 96.21% and 96.11%, respectively. This indicates that increasing the acidity is beneficial to the separation of zinc sulfide and calcium oxide, thereby increasing the recovery rates of zinc sulfide and calcium chloride.

[0068] Example 13

[0069] Example 1 was repeated, except that: S3, the solution acidity was 35 g / L, and the other conditions remained unchanged. The results showed that the recovery rates of zinc sulfide and calcium oxide were 97.01% and 97.21%, respectively. This indicates that further increasing the acidity may cause part of the zinc sulfide to be leached, thereby reducing the recovery rates of zinc sulfide and calcium chloride. Therefore, appropriate acidity is conducive to the efficient separation of zinc sulfide and calcium oxide.

[0070] Comparative Example 1

[0071] Example 1 was repeated, with the only difference being that: S3, during the acid leaching process, the prepared hydrochloric acid solution was directly added to the beaker, and the other conditions remained unchanged. The results showed that the recovery rates of zinc sulfide and calcium oxide were 86.11% and 86.62%, respectively. This indicates that adding water first can react with calcium oxide to release a large amount of heat, and the subsequent dropwise addition of concentrated hydrochloric acid can also generate a large amount of heat, thereby promoting the full dissolution of calcium in the sulfide product in the acid solution. Therefore, when water is added to the beaker containing the material and allowed to stand for 1 minute, the addition of concentrated hydrochloric acid can promote the efficient separation of zinc sulfide and calcium oxide in the sulfide product.

[0072] Comparative Example 2

[0073] Example 1 was repeated, except that: S3, concentrated hydrochloric acid was directly added dropwise without standing for 1 min after adding water, and the other conditions remained unchanged. The results showed that the recovery rates of zinc sulfide and calcium oxide were 95.59% and 96.02%, respectively. This indicates that adding water first can cause the water and calcium oxide to react and release a large amount of heat. However, if acid is directly added dropwise without standing for 1 min after adding water, calcium oxide will react directly with concentrated hydrochloric acid, thereby reducing the release of heat, which is not conducive to the full dissolution of calcium in the sulfide product in the acid solution.

Claims

1. A method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke, characterized in that: Heavy metal gypsum sludge, secondary zinc oxide dust and carbonaceous reducing agent are ground, mixed and roasted to obtain a roasted material containing ZnS and CaO; the roasted material is leached with hydrochloric acid to obtain zinc sulfide enriched slag and leaching solution; the leaching solution is evaporated and concentrated to obtain calcium chloride.

2. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust according to claim 1, characterized in that: The mass ratio m of the heavy metal gypsum sludge to the secondary zinc oxide dust (重金属石膏污泥) :m (二次氧化锌烟尘) =1~3.

3. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke according to claim 1, characterized in that: The amount of the carbonaceous reducing agent used is 10% to 30% of the total mass of the heavy metal gypsum sludge and the secondary zinc oxide smoke.

4. A method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust according to claim 1, 2 or 3, characterized in that: The calcination conditions are: in a protective atmosphere, the calcination temperature is 500-900° C., and the calcination time is 30 min-180 min.

5. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust according to claim 4, characterized in that: The protective atmosphere includes inert gas and / or nitrogen, and the flow rate of the inert gas and / or nitrogen is 0.1-3 L / min.

6. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide smoke according to claim 1, characterized in that: The leaching adopts a low-acid autothermal leaching method: after the roasted material is added into water for digestion reaction, concentrated hydrochloric acid is slowly added dropwise under stirring for leaching.

7. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust according to claim 6, characterized in that: The digestion reaction time is 1 to 5 minutes.

8. The method for resource treatment of heavy metal gypsum sludge and secondary zinc oxide dust according to claim 6, characterized in that: The leaching conditions are as follows: slurry concentration is 50-150 g / L, stirring speed is 50-150 r / min, slurry acid concentration is 25 g / L-100 g / L, and concentrated hydrochloric acid addition time is 20-60 min.

Images