Comprehensive recycling method and system for ferrous metallurgy solid waste

Abstract

The invention discloses a comprehensive recycling method and system for ferrous metallurgy solid waste, reasonable burdening is carried out according to the content of valuable metal in ferrous metallurgy dust and sludge, zinc and lead are recycled through a rotary kiln technology, iron and the like are recycled through crushing and magnetic separation of rotary kiln slag, and it is guaranteed that valuable elements Zn, Pb, K, Cl, Na, C, Au, Ag and the like are all recycled in the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of solid waste, and in particular relates to a method and system for comprehensive recycling of iron and steel metallurgical solid waste. Background Art

[0002] The metallurgical dust sludge produced by steel mills each year accounts for 8% to 12% of steel production, and zinc-containing dust sludge accounts for 20% to 30% of the total dust sludge; smoke dust mainly includes blast furnace gas ash, converter dust, etc., which contain a large amount of valuable elements such as iron, zinc, carbon, potassium, etc. The circulation of the above dust sludge in the factory will cause the blast furnace zinc load to increase, and the stability of blast furnace operation will be affected. At the same time, it is easy to have problems such as blast furnace nodules and lining erosion; electric furnace dust is listed as hazardous waste due to its high content of metal elements such as zinc, iron, cadmium, and lead. It is usually difficult to store and transport, and long-term accumulation will cause harm to humans and the living environment. The green full-scale treatment technology of the above zinc-containing dust sludge has attracted widespread attention. Therefore, it is of great research significance to the efficient enrichment and separate recycling of valuable metals in metallurgical dust sludge in steel mills.

[0003] From the perspective of the treatment process of zinc-containing solid waste, landfill, physical method, wet method, pyrolysis, plasma method, etc. are all commonly used treatment methods. The pyrolysis treatment process is the most widely used, and its main treatment processes are rotary kiln method and rotary hearth furnace method. The pyrolysis process uses reasonable ingredients and a reduction process to reduce the divalent iron and trivalent iron in the zinc-containing dust mud into metallic iron, and the zinc oxide and zinc ferrite are reduced into zinc vapor, and finally sold in the form of secondary zinc oxide powder, so as to separate iron and zinc and recycle them separately. The rotary kiln method is generally used to treat dust mud with high zinc content (generally the zinc content of the raw materials entering the furnace is ≥5-8%); while the raw materials of the rotary hearth furnace are more adaptable and can treat dust mud with low zinc and carbon content in steel plants (generally the zinc content of the raw materials entering the furnace is about 2%). The secondary zinc oxide powder produced by the pyrolysis process is currently mainly sold to zinc salt enterprises for the production of zinc sulfate products, but the potassium and chlorine content is high, which is not conducive to the leaching process, and its comprehensive utilization is limited to a certain extent; at the same time, zinc salt products are greatly affected by the downstream market. Therefore, the development of high-value utilization technology for high-chlorine zinc oxide powder is very important.

[0004] Chinese patent publication number CN111286609 A discloses a method for separation and purification of lead, zinc, cadmium and copper based on an ammonium complex system, which directly extracts various valuable elements from zinc-containing raw materials. This method has high requirements for leaching, purification, electrolysis and other processes. Since the zinc and lead grades in the raw materials are not high, a large amount of leaching agents and related supporting equipment are required, so the process is difficult to promote and apply. Chinese patent CN 107245573 B discloses a method for comprehensive recovery of zinc, germanium, lead and silver from secondary zinc oxide powder, using concentrated sulfuric acid as the leaching agent. This process has high requirements for equipment and complex process control.

[0005] Based on the above characteristics and problems, the present invention provides a comprehensive recycling and utilization method for iron and steel metallurgical solid waste, which synergistically treats iron and steel metallurgical solid waste such as blast furnace bag dust, electric furnace dust and hot-dip galvanizing slag, and realizes the separation, recovery and utilization of valuable elements such as Zn, Fe, Pb, K, Na, Cl and C. The process is flexible and the raw material adaptability is strong. The problems of difficulty in direct reuse and low comprehensive utilization value are solved, and the comprehensive utilization technology development of metallurgical solid waste such as zinc-containing dust and metallurgical slag in steel mills is of practical significance. Summary of the invention

[0006] In view of the problems of the prior art, the purpose of the present invention is to provide a method and system for comprehensive recycling of iron and steel metallurgical solid waste, which reasonably mixes materials according to the valuable metal content in the iron and steel metallurgical dust and sludge, and recovers zinc and lead through rotary kiln technology. The rotary kiln slag is crushed and magnetically separated to recover iron, etc., to ensure that valuable elements Zn, Pb, K, Cl, Na, C, Au, Ag, etc. are all recycled and utilized in this system.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a method for comprehensive recycling of iron and steel metallurgical solid waste, comprising the following steps:

[0009] S1, batching, mixing blast furnace bag ash, carbon powder, and electric furnace ash uniformly to obtain a mixture;

[0010] S2, reduction roasting, the mixed material is sent to the rotary kiln for reduction roasting, the secondary zinc oxide powder is collected by the dust collection system, and the kiln slag is discharged from the kiln head of the rotary kiln;

[0011] S3, grinding and flotation of the slag after cooling to obtain carbon powder, and performing strong magnetic roughing and strong magnetic sweeping of the flotation tailings to obtain magnetic iron powder and magnetic tailings;

[0012] S4, leaching, sending the secondary zinc oxide powder and hot-dip galvanizing slag to the chlorination leaching process, and then obtaining leaching slag and leaching liquid through liquid-solid separation;

[0013] S5, purification, sending the leaching liquid to the purification process for purification treatment to obtain purified liquid and purified slag;

[0014] S6, electrolysis, electrolyzing the purified liquid to obtain electrolytic zinc, and then melting the electrolytic zinc into zinc ingots.

[0015] Preferably, in step S1:

[0016] The blast furnace bag ash is bag dust ash collected in the ironmaking process of the blast furnace of the steel plant; the blast furnace bag ash has a Cl content of 5-10%, a Zn content of ≥5%, a Fe content of 10-30%, and a C content of 5-10%;

[0017] The electric furnace ash is dust ash produced in the process of electric furnace steelmaking; the Cl content of the electric furnace ash is 5-10%, the Zn content is 5-30%, and the Fe content is 10-20%;

[0018] The blast furnace bag ash, carbon powder and electric furnace ash are adjusted according to the raw material composition, and the composition of the mixed material after batching meets the following requirements: Fe: 20-50%, Pb: 1-3%, Zn: 10-20%, K≤4%, Ca: 4-8%, Cl≤10%, Na≤1%, C: 5-20%, H2O≤15%.

[0019] Preferably, in step S2, the rotary kiln is provided with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section.

[0020] The temperature of the preheating section is 200-500°C, the temperature of the transition section is 500-900°C, the temperature of the reduction section is 900-1300°C, the temperature of the cooling section is 1300-800°C, the temperature of the discharging section is 800-300°C, and the reduction roasting time is 60-180 minutes.

[0021] Preferably, the specific process in step S3 is as follows:

[0022] The kiln slag is cooled to below 200℃, crushed and sent to the grinding and magnetic separation system. The kiln slag is ground and floated to obtain carbon powder, and the flotation tailings are subjected to strong magnetic roughing and strong magnetic sweeping to obtain magnetic iron powder and magnetic tailings.

[0023] Preferably, in step S4, the leaching process is as follows:

[0024] The secondary zinc oxide powder and hot-dip galvanizing slag are sent to the chlorination leaching process, and the valuable metal elements enter the solution. The liquid-solid separation is carried out by plate and frame filter pressing to obtain filter residue and primary leachate;

[0025] The filter residue is subjected to secondary leaching to obtain leached residue and secondary leaching liquid;

[0026] The primary leachate and the secondary leachate are mixed as the leachate and enter the next purification process, and the leachate residue is washed with water once and filtered before returning to the batching process.

[0027] Preferably, the leaching solution used in the leaching process is waste electrolyte, and each leaching time is 45 minutes to 2 hours.

[0028] Preferably, in step S4:

[0029] The hot-dip galvanizing slag has a Zn content of 80-95% and a Fe content of 1-5%;

[0030] The Zn grade of the secondary zinc oxide powder after mixing with hot-dip galvanizing slag is 65-75%;

[0031] The liquid-to-solid ratio during the leaching process is 8 to 12:1.

[0032] Preferably, in step S5, the purification process includes primary purification, secondary purification and tertiary purification;

[0033] The primary purification is to use ferrous sulfate to remove calcium and magnesium ions in the leaching solution to obtain a primary purification slag;

[0034] The secondary purification is performed by adding zinc particles for preliminary purification to obtain secondary purified slag;

[0035] The tertiary purification is performed by adding zinc powder for further purification to obtain a purified liquid and tertiary purified slag.

[0036] Preferably, in step S6:

[0037] In the electrolyte used in the electrolysis process, the Zn ion concentration is 30-80 g / L, and the NH4Cl concentration is 200-500 g / L;

[0038] During the electrolysis process, the current density is 150-400A / m 2 , the electrolysis temperature is 20~60℃.

[0039] The second aspect of the present invention provides a comprehensive recycling system for iron and steel metallurgical solid waste, comprising:

[0040] A batching unit is used to evenly mix blast furnace bag ash, carbon powder and electric furnace ash to obtain a mixture;

[0041] A reduction roasting unit, used for reducing and roasting the mixed material obtained by the batching unit to obtain zinc-containing fume slag;

[0042] A dust collection system, used to recover the waste heat of the zinc-containing flue gas from the reduction roasting unit and to recover the secondary zinc oxide powder;

[0043] A cooling unit, used for cooling the slag obtained from the reduction roasting unit;

[0044] A grinding and flotation system, used for grinding and flotation of the kiln slag after the cooling unit to obtain carbon powder and flotation tailings;

[0045] Magnetic separation system, used to carry out strong magnetic roughing and strong magnetic sweeping of magnetic flotation tailings to obtain magnetic iron powder and magnetic tailings;

[0046] A chlorination leaching unit, used for leaching the secondary zinc oxide powder obtained by the dust collection system and the valuable elements in the hot-dip galvanizing slag to obtain leaching slag and leaching liquid;

[0047] A purification unit, used for purifying the leaching liquid to obtain purified liquid and purified slag;

[0048] An electrolytic unit, used for electrolyzing the purified liquid to obtain electrolytic zinc;

[0049] A melting and casting unit, used to melt and cast electrolytic zinc into zinc ingots;

[0050] The comprehensive recycling and utilization system for iron and steel metallurgical solid waste is used to implement the comprehensive recycling and utilization method for iron and steel metallurgical solid waste as described in claims 1 to 9.

[0051] Preferably, the reduction roasting unit adopts a rotary kiln, and the rotary kiln is provided with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section in sequence; each section is provided with a gas burner and an air burner.

[0052] The comprehensive recycling method and system of iron and steel metallurgical solid waste of the present invention also has the following beneficial effects:

[0053] 1. The present invention targets metallurgical solid wastes such as zinc dust and zinc slag from steel mills, gives full play to the characteristics of the solid wastes themselves, and maximizes the resource value through a reasonable batching system;

[0054] 2. Since the K and Cl contents in blast furnace bag ash and electric furnace ash are relatively high, the Cl content in the secondary zinc oxide powder produced by using the above raw materials is also relatively high. It needs to be washed before entering the zinc sulfate production system, and the comprehensive utilization cost is relatively high. Valuable elements will also be lost in the washing process. Therefore, the present invention makes full use of the C in the blast furnace bag ash, reduces the amount of external carbon, reduces energy consumption compared with the traditional process, and strictly controls the composition of the mixed material entering the furnace, which can better control the K, Na, and Cl content of the secondary zinc oxide powder in the rotary kiln, and the product quality is stable;

[0055] 3. In the traditional leaching process, a large amount of sulfuric acid or hydrochloric acid needs to be added as the main leaching agent, the leaching conditions are relatively harsh, and strong acid leaching has high requirements for equipment; the present invention uses waste electrolyte as a leaching agent, saving the cost of reagents and effectively reducing the cost of waste electrolyte treatment; at the same time, the ammonium salt in the waste electrolyte can be regenerated and used in the production system; in addition, the present invention uses waste electrolyte as a leaching agent, which can be recycled and only needs to be replaced regularly; the waste electrolyte is purified, impurities removed, evaporated and crystallized, and the ammonium salt produced can be reused in electrolyte configuration; this process greatly reduces the cost of reagents and water treatment, the leaching process is simple to control, and the equipment requirements are relatively low;

[0056] 4. The present invention treats the metallurgical dust and sludge of the steel plant in a coordinated manner with the hot-dip galvanizing slag, thereby realizing the efficient and full disposal of high-zinc-containing materials in the steel plant. The produced zinc ingots can be directly used in the plant, thus reducing the raw material cost for the main steel industry;

[0057] 5. The present invention can effectively realize the separation of various elements (Zn, Pb, K, Na, Cl, etc.), has flexible process, strong adaptability of raw materials, simple operation, relatively mild process conditions, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0059] Figure 1 It is a schematic flow chart of the comprehensive recycling method of iron and steel metallurgical solid waste of the present invention;

[0060] Figure 2 This is a schematic diagram of the process of producing zinc oxide powder according to the present invention;

[0061] Figure 3 The present invention is a schematic diagram of the process of producing zinc ingots. DETAILED DESCRIPTION

[0062] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.

[0063] Combination Figure 1 As shown, the comprehensive recycling method of iron and steel metallurgical solid waste provided by the present invention comprises the following steps:

[0064] S1, batching, mixing blast furnace bag ash, carbon powder, and electric furnace ash uniformly to obtain a mixture;

[0065] This step is the batching and mixing process. Figure 2 As shown, blast furnace bag ash, carbon powder, and electric furnace ash are mixed evenly in proportion to obtain a mixture. Blast furnace bag ash is bag dust ash collected in the blast furnace ironmaking process of a steel plant; the blast furnace bag ash has a Cl content of 5-10%, a Zn content of ≥5%, a Fe content of 10-30%, and a C content of 5-10%; electric furnace ash is dust ash produced in the electric furnace steelmaking process; the electric furnace ash has a Cl content of 5-10%, a Zn content of 5-30%, and a Fe content of 10-20%. Blast furnace bag ash, carbon powder, and electric furnace ash are adjusted according to the raw material composition. The general principle of batching: the composition of the mixed material after batching meets the requirements shown in Table 1, which are as follows: Fe: 20-50%, Pb: 1-3%, Zn: 10-20%, K≤4%, Ca: 4-8%, Cl≤10%, Na≤1%, C: 5-20%, H2O≤15%.

[0066] Table 1 Main components of the mixture

[0067] element Fe / % Pb / % Zn / % K / ％ Ca / % Cl / ％ Na / % C / ％ <![CDATA[H2O / %]]> content 20～50 1～3 10～20 ～4 4～8 ～10 ～1 5～20 ～15

[0068] S2, reduction roasting, the mixed material is sent to the rotary kiln for reduction roasting, the secondary zinc oxide powder is collected by the dust collection system, and the kiln slag is discharged from the kiln head of the rotary kiln;

[0069] This step is a reduction roasting process. The mixed material in step S1 is sequentially fed into the rotary kiln through the discharging belt and chute. The mixed material is fed from the tail of the rotary kiln, and after the waste heat is recovered, it is collected as secondary zinc oxide powder by the dust collection system; the kiln slag is discharged from the kiln head. The rotary kiln is provided with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section. The rotary kiln specification can be a kiln length of 60m and a kiln body inner diameter of 5m; the preheating section temperature is 200-500℃, the transition section temperature is 500-900℃, the reduction section temperature is 900-1300℃, the cooling section is 1300℃-800℃, the discharging section temperature is 800-300℃, and the reduction roasting time is 60-180min; each section is provided with a gas burner and an air burner, and the reduction atmosphere in the kiln is adjusted by controlling the gas and air flow to ensure the reduction efficiency of this process.

[0070] S3, grinding and flotation of the slag after cooling to obtain carbon powder, and performing strong magnetic roughing and strong magnetic sweeping of the flotation tailings to obtain magnetic iron powder and magnetic tailings;

[0071] This step is the magnetic separation process, which mainly processes the kiln slag by grinding, flotation, magnetic separation, etc.; the kiln slag obtained in step S2 is cooled to below 200°C, crushed and then sent to the grinding system and magnetic separation system for treatment, and the kiln slag is subjected to grinding and flotation to obtain carbon powder, which is returned to the batching process; the flotation tailings are subjected to two processes of strong magnetic roughing and strong magnetic sweeping, and finally magnetic iron powder and magnetic tailings are obtained; the magnetic iron powder is dehydrated and packaged for sale, and the magnetic tailings are sold to cement plants after sedimentation; the wastewater in this step is circulated in the magnetic separation system;

[0072] S4, leaching, sending the secondary zinc oxide powder and hot-dip galvanizing slag to the chlorination leaching process, and then obtaining leaching slag and leaching liquid through liquid-solid separation;

[0073] This step is the leaching process, combined with Figure 3 As shown, secondary zinc oxide powder and hot-dip galvanizing slag are sent to the chlorination leaching process, and valuable metal elements such as zinc, lead, and cadmium enter into the solution. Liquid-solid separation is performed by plate and frame filter pressing to obtain filter residue and primary leachate; the filter residue is then subjected to secondary leaching to obtain leaching residue and secondary leachate; the primary leachate and the secondary leachate are mixed and then used as the leachate to enter the next purification process, and the leaching residue is returned to the batching process after being washed with water once and filtered.

[0074] The above leaching process can be prepared with hot-dip galvanized slag from a steel plant, wherein the hot-dip galvanized slag used has a Zn content of 80-95% and an Fe content of 1-5%;

[0075] The batching structure of secondary zinc oxide powder and hot-dip galvanizing slag is determined according to the Zn grade in the secondary zinc oxide powder and hot-dip galvanizing slag. After the two are mixed, the Zn grade is generally 65-75%.

[0076] The leaching liquid used in the above leaching process is waste electrolyte, and the leaching time for each time is 45 minutes to 2 hours; the liquid-solid ratio during the leaching process is controlled to be 8 to 12:1.

[0077] S5, purification, sending the leaching liquid to the purification process for purification treatment to obtain purified liquid and purified slag;

[0078] This step is a purification process, in which the leaching solution containing valuable elements such as zinc, lead, and cadmium is sent to the purification process to remove valuable elements such as Ca, Mg, Pb, and Cd in turn to obtain purified liquid and purified slag.

[0079] The purification process includes primary purification, secondary purification and tertiary purification; the primary purification is to use ferrous sulfate to remove calcium and magnesium ions in the leachate to obtain primary purification slag (calcium and magnesium slag); the secondary purification is to add zinc particles for preliminary purification to remove other valuable elements such as Pb and Cd to obtain secondary purification slag; the tertiary purification is to add zinc powder for further purification to remove other valuable elements such as Pb and Cd to obtain purified liquid and tertiary purification slag. The above-mentioned primary purification slag, kiln slag and magnetic separation tailings can be mixed and sold to cement plants; the secondary purification slag and tertiary purification slag are mixed and stored together, and after sedimentation, they are regularly sent to the lead smelting system. In the above purification process, the amount of zinc particles and zinc powder added is determined according to the Pb and Cd in the purified liquid to ensure that Pb in the purified liquid is less than 5mg / L and Cd is less than 1mg / L.

[0080] S6, electrolysis, electrolyzing the purified liquid to obtain electrolytic zinc, and then melting the electrolytic zinc into zinc ingots.

[0081] This step is the electrolysis process. Before electrolysis, the electrolyte is prepared to meet the following conditions: [Zn + ] concentration = 30 ~ 80g / L, [NH4Cl] concentration = 200 ~ 500g / L. During the electrolysis process, the current density is 150 ~ 400A / m 2 , the electrolysis temperature is 20-60℃ to ensure the electrolysis efficiency. To ensure the electrolysis and leaching efficiency, the electrolyte is replaced regularly. After the waste electrolyte is purified and impurities are removed, NH4Cl, KCl, etc. are obtained through evaporation and crystallization. NH4Cl can be returned to the system for electrolyte configuration, and KCl standard products are directly exported.

[0082] The present invention also provides a comprehensive recycling system for iron and steel metallurgical solid waste, including a batching unit, a reduction roasting unit, a dust collection system, a cooling unit, a grinding flotation system, a magnetic separation system, a chlorination leaching unit, a purification unit, an electrolysis unit and a melting and casting unit. The batching unit is used to mix blast furnace bag ash, carbon powder and electric furnace ash evenly to obtain a mixture; the reduction roasting unit is used to reduce roast the mixture obtained by the batching unit to obtain zinc-containing flue gas slag; the dust collection system is used to recover the waste heat of the zinc-containing flue gas from the reduction roasting unit and recover the secondary zinc oxide powder; the cooling unit is used to cool the slag obtained by the reduction roasting unit (such as water quenching); the grinding and flotation system is used to grind and float the slag after the cooling unit to obtain carbon powder and flotation tailings; the magnetic separation system is used to perform strong magnetic roughing and strong magnetic sweeping on the magnetic separation flotation tailings to obtain magnetic separation iron powder and magnetic separation tailings; the chlorination leaching unit is used to leach the secondary zinc oxide powder obtained by the dust collection system and the valuable metals in the hot-dip galvanizing slag to obtain leaching slag and leachate; the purification unit is used to purify the leachate to obtain purified liquid and purified slag; the electrolysis unit is used to electrolyze the purified liquid to obtain electrolytic zinc; and the smelting unit is used to smelt the electrolytic zinc into zinc ingots.

[0083] The reduction roasting unit adopts a rotary kiln, which is equipped with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section in sequence; each section is equipped with a gas burner and an air burner, and the reduction atmosphere in the kiln is adjusted by controlling the gas and air flow rates to ensure the reduction efficiency of the reduction roasting process.

[0084] The comprehensive recycling and utilization method of iron and steel metallurgical solid waste of the present invention is further introduced below with reference to specific examples.

[0085] Example 1

[0086] The comprehensive recycling method of iron and steel metallurgical solid waste in this embodiment is as follows:

[0087] (1) batching and mixing, mixing blast furnace bag ash, carbon powder and electric furnace ash in proportion to obtain a mixture; the blast furnace bag ash contains 5.8% Cl, 8.2% Zn, 23.1% Fe and 9.5% C; the electric furnace ash is dust ash generated in the electric furnace steelmaking process, containing 9.8% Cl, 20.3% Zn and 15.2% Fe;

[0088] The proportion of the above-mentioned bag ash, carbon powder and electric furnace ash is adjusted according to the raw material composition. General principles of batching: after batching, the main components of the mixture are shown in Table 2.

[0089] Table 2 Main components of the mixture

[0090] element Fe / % Pb / % Zn / % K / ％ Ca / % Cl / ％ Na / % C / ％ <![CDATA[H2O / %]]> content 20.0 2.8 17.2 2.3 6.2 7.3 0.7 18.4 10.0

[0091] (2) Reduction roasting: the mixed material in step (1) is sequentially fed into the rotary kiln through the discharging belt and chute, and the mixed material is fed from the tail of the rotary kiln, wherein the preheating section temperature is 400°C, the transition section temperature is 800°C, the reduction section temperature is 1000°C, the cooling section temperature is 800°C, the discharging section temperature is 700°C, and the reduction roasting time is 90 minutes. After waste heat recovery, the secondary zinc oxide powder is collected by the dust collection system; the kiln slag is discharged from the kiln head; wherein the secondary zinc oxide powder contains 62.7% Zn, 6.3% Fe, and 8.5% Pb.

[0092] (3) Slag grinding, flotation and magnetic separation. The slag described in step (2) is cooled to below 200° C. and then enters the grinding system and the magnetic separation system. The slag is subjected to grinding and flotation to obtain carbon powder, which is returned to the batching process. The flotation tailings are subjected to two processes of strong magnetic roughing and strong magnetic sweeping to finally obtain magnetic iron powder and magnetic tailings. The magnetic iron powder is dehydrated and packaged for sale, and the magnetic tailings are settled and sold to cement plants. The waste water is circulated in the magnetic separation system. The magnetic iron powder contains 90.8% TFe and 81.2% MFe.

[0093] (4) Leaching, the secondary zinc oxide powder and hot-dip galvanizing slag in step (2) are sent to a chlorination leaching process, wherein the hot-dip galvanizing slag contains 83.2% Zn and 1.8% Pb, and the Zn content of the secondary zinc oxide powder and the hot-dip galvanizing slag is between 65% and 75% after being mixed; the valuable elements such as zinc, lead, and cadmium in the secondary zinc oxide powder and the hot-dip galvanizing slag enter the solution, and liquid-solid separation is performed by plate and frame filter pressing to obtain filter residue and primary leachate; the filter residue is then subjected to secondary leaching to obtain leaching residue and secondary leachate, and the secondary leachate is mixed with the primary leachate and enters the next purification process; the leaching residue is washed with water once and filtered, and then returned to the batching process; after two leaching steps, the mixed leachate of the secondary leachate and the primary leachate has a Zn content of 53 g / L, a Pb content of 115 mg / L, and a Cd content of 7 mg / L, and the leaching ammonium chloride concentration is 201 g / L, the temperature is 55° C., and the leaching time is 90 min;

[0094] (5) Purification: Send the zinc, lead and cadmium solution in step (4) to the purification process to remove valuable elements such as Ca, Mg, As, Sb, Pb, Cd, etc. respectively; the first purification uses ferrous sulfate to remove calcium and magnesium ions in the system to obtain a first purification slag; the second purification adds zinc particles to preliminarily purify and remove valuable elements such as Pb and Cd to obtain a second purification slag; the third purification uses zinc powder to purify again to remove valuable elements such as Pb and Cd, and finally obtains a purified liquid and a tertiary purification slag. The main components of the secondary purification slag and the tertiary purification slag are lead and cadmium. After being washed with water, the two enter the lead smelting system to smelt crude lead; the purified liquid after purification contains 55g / L Zn, 5mg / L Pb, 0.8mg / L Cd, and 0.1mg / L Fe;

[0095] (6) Electrolysis: electrolyze the purified solution in step (5) to obtain electrolytic zinc; the electrolyte contains 55 g / L Zn, 300 g / L NH4Cl, and a current density of 300 A / m 2 , the electrolysis temperature is 50℃, and 1# zinc ingot can be obtained after electrolytic zinc flake casting.

[0096] Example 2

[0097] The comprehensive recycling method of iron and steel metallurgical solid waste in this embodiment is as follows:

[0098] (1) batching and mixing, mixing blast furnace bag ash, carbon powder and electric furnace ash in proportion to obtain a mixture; the blast furnace bag ash contains 4.0% Cl, 11.3% Zn, 20.1% Fe and 9.7% C; the electric furnace ash is dust ash generated in the electric furnace steelmaking process, containing 8.9% Cl, 22.6% Zn and 18.5% Fe;

[0099] The proportion of the above-mentioned bag ash, carbon powder and electric furnace ash is adjusted according to the raw material composition. General principles of batching: after batching, the main components of the mixture are shown in Table 3.

[0100] Table 3 Main components of the mixture

[0101] element Fe / % Pb / % Zn / % K / ％ Ca / % Cl / ％ Na / % C / ％ <![CDATA[H2O / %]]> content 19.1 3.3 20.7 2.4 5.9 6.4 0.5 19.2 9.7

[0102] (2) Reduction roasting: the mixed material in step (1) is sequentially fed into the rotary kiln through the discharging belt and chute, and the mixed material is fed from the tail of the rotary kiln, wherein the preheating section temperature is 450°C, the transition section temperature is 850°C, the reduction section temperature is 1050°C, the cooling section temperature is 800°C, the discharging section temperature is 700°C, and the reduction roasting time is 75 minutes. After waste heat recovery, the secondary zinc oxide powder is collected by the dust collection system; the kiln slag is discharged from the kiln head; wherein the secondary zinc oxide powder contains 67.7% Zn, 5.3% Fe, and 9.0% Pb.

[0103] (3) Slag grinding, flotation and magnetic separation. The slag described in step (2) is cooled to below 200° C. and then enters the grinding system and the magnetic separation system. The slag is subjected to grinding and flotation to obtain carbon powder, which is returned to the batching process. The flotation tailings are subjected to two processes of strong magnetic roughing and strong magnetic sweeping to finally obtain magnetic iron powder and magnetic tailings. The magnetic iron powder is dehydrated and packaged for sale, and the magnetic tailings are settled and sold to cement plants. The waste water is circulated in the magnetic separation system. The magnetic iron powder contains 91.3% TFe and 82.2% MFe.

[0104] (4) Leaching, the secondary zinc oxide powder and hot-dip galvanizing slag in step (2) are sent to a chlorination leaching process, wherein the hot-dip galvanizing slag contains 80.4% Zn and 1.7% Pb, and the Zn content of the secondary zinc oxide powder and the hot-dip galvanizing slag is between 65% and 75% after being mixed; the valuable elements such as zinc, lead, and cadmium in the secondary zinc oxide powder and the hot-dip galvanizing slag enter the solution, and liquid-solid separation is performed by plate and frame filter pressing to obtain filter residue and primary leachate; the filter residue is then subjected to secondary leaching to obtain leaching residue and secondary leachate, and the secondary leachate is mixed with the primary leachate and enters the next purification process; the leaching residue is washed with water once and filtered, and then returned to the batching process; after two leaching processes, the mixed leachate of the secondary leachate and the primary leachate has a Zn content of 58 g / L, a Pb content of 126 mg / L, and a Cd content of 5 mg / L, a leaching ammonium chloride concentration of 211 g / L, a temperature of 53° C., and a leaching time of 95 min;

[0105] (5) Purification: Send the zinc, lead and cadmium solution in step (4) to the purification process to remove valuable elements such as Ca, Mg, As, Sb, Pb, Cd, etc. respectively; the first purification uses ferrous sulfate to remove calcium and magnesium ions in the system to obtain a first purification slag; the second purification adds zinc particles to preliminarily purify and remove valuable elements such as Pb and Cd to obtain a second purification slag; the third purification uses zinc powder to purify again to remove valuable elements such as Pb and Cd, and finally obtains a purified liquid and a third purification slag. The main components of the second purification slag and the third purification slag are lead and cadmium. After being washed with water, the two enter the lead smelting system to smelt crude lead; the purified liquid after purification contains 60g / L Zn, 4.4mg / L Pb, 0.6mg / L Cd, and 0.07mg / L Fe;

[0106] (6) Electrolysis: electrolyze the purified solution in step (5) to obtain electrolytic zinc; the electrolyte contains 58 g / L Zn, 310 g / L NH4Cl, and a current density of 350 A / m 2 , the electrolysis temperature is 52℃, and 1# zinc ingot can be obtained after electrolytic zinc flake casting.

[0107] Example 3

[0108] The comprehensive recycling method of iron and steel metallurgical solid waste in this embodiment is as follows:

[0109] (1) batching and mixing, mixing blast furnace bag ash, carbon powder and electric furnace ash in proportion to obtain a mixture; the blast furnace bag ash contains 4.8% Cl, 9.9% Zn, 21.2% Fe and 10.4% C; the electric furnace ash is dust ash generated in the electric furnace steelmaking process, containing 9.3% Cl, 21.5% Zn and 20.8% Fe;

[0110] The proportion of the above-mentioned bag ash, carbon powder and electric furnace ash is adjusted according to the raw material composition. General principles of batching: after batching, the main components of the mixture are shown in Table 4.

[0111] Table 4 Main components of the mixture

[0112] element Fe / % Pb / % Zn / % K / ％ Ca / % Cl / ％ Na / % C / ％ <![CDATA[H2O / %]]> content 20.0 2.8 17.2 2.3 6.2 7.3 0.7 18.4 10.0

[0113] (2) Reduction roasting: the mixed material in step (1) is sequentially fed into the rotary kiln through the discharging belt and chute, and the mixed material is fed from the tail of the rotary kiln, wherein the preheating section temperature is 450°C, the transition section temperature is 850°C, the reduction section temperature is 1050°C, the cooling section temperature is 800°C, the discharging section temperature is 700°C, and the reduction roasting time is 95 minutes. After waste heat recovery, the secondary zinc oxide powder is collected by the dust collection system; the kiln slag is discharged from the kiln head; wherein the secondary zinc oxide powder contains 58.5% Zn, 6.2% Fe, and 7.6% Pb.

[0114] (3) Slag grinding, flotation and magnetic separation. The slag described in step (2) is cooled to below 200° C. and then enters the grinding system and the magnetic separation system. The slag is subjected to grinding and flotation to obtain carbon powder, which is returned to the batching process. The flotation tailings are subjected to two processes of strong magnetic roughing and strong magnetic sweeping to finally obtain magnetic iron powder and magnetic tailings. The magnetic iron powder is dehydrated and packaged for sale, and the magnetic tailings are settled and sold to cement plants. The waste water is circulated in the magnetic separation system. The magnetic iron powder contains 88.6% TFe and 79.8% MFe.

[0115] (4) Leaching, the secondary zinc oxide powder and hot-dip galvanizing slag in step (2) are sent to a chlorination leaching process, wherein the hot-dip galvanizing slag contains 84.8% Zn and 2.0% Pb, and the Zn content of the secondary zinc oxide powder and the hot-dip galvanizing slag is between 65% and 75% after being mixed; the valuable elements such as zinc, lead, and cadmium in the secondary zinc oxide powder and the hot-dip galvanizing slag enter the solution, and liquid-solid separation is performed by plate and frame filter pressing to obtain filter residue and primary leachate; the filter residue is then subjected to secondary leaching to obtain leaching residue and secondary leachate, and the secondary leachate is mixed with the primary leachate and enters the next purification process; the leaching residue is washed with water once and filtered, and then returned to the batching process; after two leaching processes, the mixed leachate of the secondary leachate and the primary leachate has a Zn content of 55 g / L, a Pb content of 124 mg / L, and a Cd content of 4 mg / L, and the leaching ammonium chloride concentration is 205 g / L, the temperature is 55° C., and the leaching time is 95 min;

[0116] (5) Purification: Send the zinc, lead and cadmium solution in step (4) to the purification process to remove valuable elements such as Ca, Mg, As, Sb, Pb, Cd, etc. respectively; the first purification uses ferrous sulfate to remove calcium and magnesium ions in the system to obtain a first purification slag; the second purification adds zinc particles to preliminarily purify and remove valuable elements such as Pb and Cd to obtain a second purification slag; the third purification uses zinc powder to purify again to remove valuable elements such as Pb and Cd, and finally obtains a purified liquid and a tertiary purification slag. The main components of the secondary purification slag and the tertiary purification slag are lead and cadmium. After being washed with water, the two enter the lead smelting system to smelt crude lead; the purified liquid after purification contains Zn: 57g / L, Pb: 4.1mg / L, Cd: 0.4mg / L, Fe: 0.1mg / L;

[0117] (6) Electrolysis: The purified solution in step (5) is electrolyzed to obtain electrolytic zinc; the Zn concentration in the electrolyte is 57 g / L, the NH4Cl concentration is 306 g / L, and the current density is 263 A / m 2 , the electrolysis temperature is 52℃, and 1# zinc ingot can be obtained after electrolytic zinc flake casting.

[0118] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A comprehensive recycling method for iron and steel metallurgical solid waste, characterized in that: The following steps are involved: S1, batching, mixing blast furnace bag ash, carbon powder, and electric furnace ash uniformly to obtain a mixture; S2, reduction roasting, the mixed material is sent to the rotary kiln for reduction roasting, the secondary zinc oxide powder is collected by the dust collection system, and the kiln slag is discharged from the kiln head of the rotary kiln; S3, grinding and flotation of the slag after cooling to obtain carbon powder, and performing strong magnetic roughing and strong magnetic sweeping of the flotation tailings to obtain magnetic iron powder and magnetic tailings; S4, leaching, sending the secondary zinc oxide powder and hot-dip galvanizing slag to the chlorination leaching process, and then obtaining leaching slag and leaching liquid through liquid-solid separation; S5, purification, sending the leaching liquid to the purification process for purification treatment to obtain purified liquid and purified slag; S6, electrolysis, electrolyzing the purified liquid to obtain electrolytic zinc, and then melting the electrolytic zinc into zinc ingots.

2. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S1: The blast furnace bag ash is bag dust ash collected in the ironmaking process of the blast furnace of the steel plant; the blast furnace bag ash has a Cl content of 5-10%, a Zn content of ≥5%, a Fe content of 10-30%, and a C content of 5-10%; The electric furnace ash is dust ash produced in the process of electric furnace steelmaking; the Cl content of the electric furnace ash is 5-10%, the Zn content is 5-30%, and the Fe content is 10-20%; The blast furnace bag ash, carbon powder and electric furnace ash are adjusted according to the raw material composition, and the composition of the mixed material after batching meets the following requirements: Fe: 20-50%, Pb: 1-3%, Zn: 10-20%, K≤4%, Ca: 4-8%, Cl≤10%, Na≤1%, C: 5-20%, H2O≤15%.

3. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S2, the rotary kiln is provided with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section. The temperature of the preheating section is 200-500°C, the temperature of the transition section is 500-900°C, the temperature of the reduction section is 900-1300°C, the temperature of the cooling section is 1300-800°C, the temperature of the discharging section is 800-300°C, and the reduction roasting time is 60-180 minutes.

4. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: The specific process in step S3 is as follows: The slag is cooled to below 200℃, crushed and sent to the grinding and magnetic separation system. The slag is ground and floated to obtain carbon powder, and the flotation tailings are subjected to strong magnetic roughing and strong magnetic sweeping to obtain magnetic iron powder and magnetic tailings.

5. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S4, the leaching process is as follows: The secondary zinc oxide powder and hot-dip galvanizing slag are sent to the chlorination leaching process, and the valuable metal elements enter the solution. The liquid-solid separation is carried out by plate and frame filter pressing to obtain filter residue and primary leachate; The filter residue is subjected to secondary leaching to obtain leached residue and secondary leaching liquid; The primary leachate and the secondary leachate are mixed as the leachate and enter the next purification process, and the leachate residue is washed with water once and filtered before returning to the batching process.

6. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 5, characterized in that: The leaching solution used in the leaching process is waste electrolyte, and each leaching time is 45 minutes to 2 hours.

7. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S4: The hot-dip galvanizing slag has a Zn content of 80-95% and a Fe content of 1-5%; The Zn grade of the secondary zinc oxide powder after mixing with hot-dip galvanizing slag is 65-75%; The liquid-to-solid ratio during the leaching process is 8 to 12:

1.

8. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S5, the purification process includes primary purification, secondary purification and tertiary purification; The primary purification is to use ferrous sulfate to remove calcium and magnesium ions in the leaching solution to obtain a primary purification slag; The secondary purification is performed by adding zinc particles for preliminary purification to obtain secondary purified slag; The tertiary purification is performed by adding zinc powder for further purification to obtain a purified liquid and tertiary purified slag.

9. The method for comprehensive recycling of iron and steel metallurgical solid waste according to claim 1, characterized in that: In step S6: In the electrolyte used in the electrolysis process, the Zn ion concentration is 30-80 g / L, and the NH4Cl concentration is 200-500 g / L; During the electrolysis process, the current density is 150-400A / m 2 , the electrolysis temperature is 20~60℃.

10. A comprehensive recycling system for iron and steel metallurgical solid waste, characterized in that: include A batching unit is used to evenly mix blast furnace bag ash, carbon powder and electric furnace ash to obtain a mixture; A reduction roasting unit, used for reducing and roasting the mixed material obtained by the batching unit to obtain zinc-containing fume slag; A dust collection system, used to recover the waste heat of the zinc-containing flue gas from the reduction roasting unit and to recover the secondary zinc oxide powder; A cooling unit, used for cooling the slag obtained from the reduction roasting unit; A grinding and flotation system, used for grinding and flotation of the kiln slag after the cooling unit to obtain carbon powder and flotation tailings; Magnetic separation system, used to carry out strong magnetic roughing and strong magnetic sweeping of magnetic flotation tailings to obtain magnetic iron powder and magnetic tailings; A chlorination leaching unit, used for leaching the secondary zinc oxide powder obtained by the dust collection system and the valuable elements in the hot-dip galvanizing slag to obtain leaching slag and leaching liquid; A purification unit, used for purifying the leaching liquid to obtain purified liquid and purified slag; An electrolytic unit, used for electrolyzing the purified liquid to obtain electrolytic zinc; A melting and casting unit, used to melt and cast electrolytic zinc into zinc ingots; The comprehensive recycling and utilization system for iron and steel metallurgical solid waste is used to implement the comprehensive recycling and utilization method for iron and steel metallurgical solid waste as described in claims 1 to 9.

11. The iron and steel metallurgical solid waste comprehensive recycling and utilization system according to claim 10, characterized in that: The reduction roasting unit adopts a rotary kiln, and the rotary kiln is provided with a preheating section, a transition section, a reduction section, a cooling section, and a discharging section in sequence; each section is provided with a gas burner and an air burner.

Images