Treatment process for solid waste containing iron and zinc

Abstract

The invention relates to a treatment process for solid waste containing iron and zinc, and belongs to the technical field of solid waste treatment. The method specifically comprises the following steps: pretreating iron and zinc-containing solid waste raw materials; carrying out a high-temperature calcination process on an iron and zinc-containing material; a zinc element and sulfur-containing flue gas separation process; preparing and storing zinc oxide slurry; a sulfur-containing flue gas purification process; and preparing zinc sulfate. The zinc oxide product generated in the solid waste treatment process is used for treating the flue gas containing sulfur dioxide generated in the solid waste treatment process, the low-quality secondary zinc oxide product is changed into the high-quality zinc sulfate product while sulfur dioxide is treated, the flue gas is discharged after reaching the standard, and no new solid waste is generated.

Description

Technical Field

[0001] The invention relates to a treatment process for solid waste containing iron and zinc, and belongs to the technical field of solid waste treatment. Background Art

[0002] Iron-containing and zinc-containing solid wastes in the steel industry are solid wastes generated by the steel production process. They are characterized by many types, large output, and complex composition. They contain harmful elements such as K, Na, Zn, and Cl. The treatment of iron-containing and zinc-containing solid wastes has become a difficult problem that steel mills need to deal with urgently. The rotary kiln is a widely used iron-reducing and zinc-reducing reduction equipment. Iron-containing materials are reduced in the high-temperature atmosphere of the rotary kiln. Zinc-containing materials enter from the high end of the rotary kiln. After entering the kiln, the materials are preheated, dried, calcined, reduced, and other processes under the action of high-temperature flue gas. Zinc vapor volatilizes into the gas phase under the action of flue gas flow, and iron elements are discharged from the lower end of the rotary kiln with the solid phase. In the process of treating iron-containing and zinc-containing solid wastes, flue gas containing sulfur dioxide is generated.

[0003] In the prior art, my country's invention patent application number: 202010216864.2 discloses a device and method for reducing and recovering reduced iron and secondary zinc oxide using zinc-containing and iron-containing solid waste. The invention adopts a two-stage short-process rotary kiln method and a double-base deep reduction and slag-iron separation and reduction process technology. By innovating and improving the original process wind and heating methods, slag-iron separation and reduction smelting is carried out. After the iron-containing and zinc-containing solid waste is treated in a rotary kiln, solid iron-containing products and secondary zinc oxide products are produced. The quality of secondary zinc oxide is generally not high and contains impurities, etc. The cost of recycling and recovering secondary zinc oxide products is very high.

[0004] In the prior art, when treating flue gas containing sulfur dioxide, wet desulfurization or semi-dry desulfurization processes are used, which will produce new solid wastes such as gypsum or desulfurization ash. my country's invention patent application number: 201910700484.3, discloses a method and system for preparing desulfurization gypsum from dry desulfurization ash using social waste acid, including the following steps: mixing water and dry desulfurization ash, stirring to prepare dry desulfurization ash solution; adding social waste acid to the dry desulfurization ash solution, passing oxygen and stirring to carry out oxidation reaction; adding the mixed solution to a solid-liquid separation device for solid-liquid separation; the solid separated from the solid-liquid separation enters the distillation device; the solid-liquid separation is carried out in the distillation device, and the distilled solid is used as desulfurization gypsum. The quality of desulfurization gypsum is not high, and the reuse of desulfurization ash is an industry problem. Therefore, the prior art generates new solid waste while treating one solid waste. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a treatment process for iron- and zinc-containing solid waste by treating waste with waste. The zinc oxide product generated in the solid waste treatment process is used to treat the flue gas containing sulfur dioxide generated in the solid waste treatment process. While treating the sulfur dioxide, the low-quality zinc oxide product is converted into a high-quality zinc sulfate product. The flue gas meets the emission standards and no new solid waste is generated.

[0006] To achieve the above object, the present invention provides a process for treating solid waste containing iron and zinc, which specifically comprises:

[0007] Step 1: Pretreatment process of solid waste raw materials containing iron and zinc;

[0008] Step 2: high temperature calcination process of iron and zinc containing materials;

[0009] Step 3, separation process of zinc element and sulfur-containing flue gas;

[0010] Step 4: preparing and storing zinc oxide slurry;

[0011] Step 5: sulfur-containing flue gas purification process;

[0012] Step six, preparation of zinc sulfate.

[0013] Furthermore, the step 1 specifically comprises pre-treating the iron- and zinc-containing solid waste by cold pressing or disc pelletizing, pressing the powdered iron- and zinc-containing solid waste into agglomerates, and then entering into a calcination process.

[0014] Furthermore, in the step 2, the iron-containing and zinc-containing materials pretreated in the step 1 are subjected to high-temperature calcination in a rotary kiln, iron elements are recovered from the kiln head of the rotary kiln, and zinc-containing elements and sulfur dioxide gas are discharged from the kiln tail of the rotary kiln along with the flue gas.

[0015] Furthermore, in the step three, the zinc-containing and sulfur dioxide-containing flue gas discharged from the rotary kiln tail in step two is passed through a waste heat recovery device, a surface cooler, and then a bag filter to separate it into a zinc oxide product and a sulfur dioxide-containing flue gas.

[0016] Furthermore, in the step 4, the zinc oxide product produced in the step 3 is prepared into a slurry, and the prepared zinc oxide slurry is stored in a slurry tank for standby use.

[0017] Furthermore, in the step 5, the sulfur dioxide-containing flue gas in the bag filter of step 3 is introduced into the desulfurization purification tower through an induced draft fan, and the zinc oxide slurry prepared in step 4 is pumped into the desulfurization purification tower through a pump. In the desulfurization purification tower, a circulating pump is used to contact the zinc oxide slurry with the sulfur-containing flue gas, and after the sulfur dioxide in the flue gas is removed, the flue gas is discharged through a chimney, and the zinc oxide solution generates zinc sulfate and zinc sulfite solutions.

[0018] Furthermore, in step six, oxygen is introduced into the desulfurization purification tower through an oxidation blower to oxidize the zinc sulfite into a zinc sulfate solution, and then the zinc sulfate solution is pumped into a filter press to produce a zinc sulfate product.

[0019] The invention discloses a treatment process for iron- and zinc-containing solid wastes, and the beneficial effect is that the method prepares and stores slurry from low-grade secondary zinc oxide products generated after a bag filter, and is used to remove sulfur dioxide-rich flue gas generated after the bag filter, thereby achieving the effect of treating waste with waste; in the process of removing sulfur dioxide from the flue gas, no new solid waste is generated, and the pollutant sulfur dioxide to be removed in the flue gas is recycled in the form of a zinc sulfate product, and the quality is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 The present invention is a schematic diagram of a treatment process flow of iron- and zinc-containing solid waste. DETAILED DESCRIPTION

[0022] The present invention aims at the problems that under complex formation background conditions, there is not a clear understanding of the laws of oil-water distribution and the state of remaining oil occurrence, and water injection development is difficult, the recovery rate is low, and there is a large amount of remaining oil distribution in the later development work. The present invention provides a method for realizing water-oil microscopic displacement observation and quantitative analysis based on high-temperature and high-pressure components. The method uses representative real cores to prepare high-temperature and high-pressure visualization components, which can not only observe the microscopic dynamic process of oil and water displacement, but also quantitatively analyze the oil-water distribution after displacement and microscopically observe the state of remaining oil occurrence, and the operation is simple and the cost is low.

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In order to further understand the content of the invention, this technical solution is further described below in conjunction with specific implementation methods.

[0025] Example 1: Figure 1 As shown, this embodiment provides a treatment process for iron- and zinc-containing solid waste, which specifically includes:

[0026] Step 1: Pretreatment process of iron-containing and zinc-containing solid waste raw materials, specifically, pretreatment of iron-containing and zinc-containing solid waste by cold pressing process, pressing powdered iron-containing and zinc-containing solid waste into agglomerates, and then entering into calcination process.

[0027] Step 2: High-temperature calcination process of iron-containing and zinc-containing materials, specifically, calcining the iron-containing and zinc-containing materials pressed into agglomerates pretreated in step 1 in a rotary kiln at a high temperature of 1000-1300°C, recovering iron elements from the head of the rotary kiln, and discharging zinc elements and sulfur dioxide gas from the tail of the rotary kiln along with the flue gas.

[0028] Step 3: Zinc element and sulfur-containing flue gas separation process, specifically, the high-temperature zinc-containing and sulfur dioxide-containing flue gas of about 700-800℃ discharged from the rotary kiln tail in step 2 is recovered by the waste heat recovery device, and the flue gas temperature is reduced to 350-360℃ and then enters the surface cooler and further cooled to 120-130℃ before entering the bag filter. Under the filtering condition of the bag filter, the zinc oxide product in the flue gas is separated in powder form, and the output of zinc oxide product is about 1t / h; sulfur dioxide is discharged with the flue gas, and the exhaust flue gas volume is 100000Nm 3 / h, sulfur dioxide concentration in flue gas 1500mg / Nm 3 .

[0029] Step 4: zinc oxide slurry preparation and storage, specifically, 38% of the zinc oxide product produced in step 3, i.e., 0.38 t / h of the zinc oxide product, is prepared into a slurry, and the zinc oxide product is prepared into a zinc oxide slurry with a concentration of 20% to 30%. The prepared slurry is stored in a zinc oxide slurry tank for standby use, and the remaining 0.62 t / h of zinc oxide is directly sold as a product.

[0030] Step 5: Sulfur-containing flue gas purification process, specifically, introducing the sulfur dioxide-containing flue gas at 120-130° C. separated by the bag filter in step 3 into a desulfurization purification tower through an induced draft fan, pumping the 20%-30% concentration zinc oxide slurry configured in step 4 into the desulfurization purification tower through a pump, using a circulating pump in the desulfurization purification tower to contact the slurry with the sulfur-containing flue gas, removing the sulfur dioxide in the flue gas and discharging the flue gas through a chimney, and the zinc oxide solution generates zinc sulfate and zinc sulfite solutions.

[0031] Step 6: Preparation of zinc sulfate, specifically, introducing oxygen into the desulfurization purification tower through an oxidation blower, oxidizing zinc sulfite into zinc sulfate solution, and then pumping the solution into a filter press to produce zinc sulfate products. The system produces 0.35 t / h of zinc sulfate products.

[0032] In Example 1, the system produces 1 t / h of zinc oxide product, with an effective content of about 50% zinc oxide, about 6172 mol / h. The exhaust gas generated is 100000 Nm 3 / h, the sulfur dioxide concentration in the flue gas is 1500mg / Nm 3 , the sulfur dioxide in the flue gas is 0.15t / h, about 2344mol / h. According to the material balance calculation, the system produces a large surplus of zinc oxide products. After reacting with sulfur dioxide in the flue gas, 0.62t / h of zinc oxide products can be left over. The surplus is large and sold in the form of zinc oxide products. In Example 1, a steel iron-containing zinc-containing solid waste treatment process system with a high zinc content and a low sulfur content is provided. The system produces 4910t of zinc oxide products and 2772t of zinc sulfate products annually.

[0033] Embodiment 2: As attached Figure 1 As shown, this embodiment provides a process for treating iron and zinc solid waste containing high zinc content and low sulfur content, and the process method comprises the following steps:

[0034] Step 1: Pretreatment process of iron-containing and zinc-containing solid waste raw materials, specifically, pretreatment of iron-containing and zinc-containing solid waste by cold pressing process, pressing powdered iron-containing and zinc-containing solid waste into agglomerates, and then entering into calcination process.

[0035] Step 2: High-temperature calcination process of iron-containing and zinc-containing materials, specifically, calcining the iron-containing and zinc-containing materials pressed into agglomerates pretreated in step 1 in a high-temperature environment of 1000-1300°C in a rotary kiln, recovering iron elements from the head of the rotary kiln, and discharging zinc elements and sulfur dioxide gas from the tail of the rotary kiln along with the flue gas.

[0036] Step 3: Zinc element and sulfur-containing flue gas separation process, specifically, the high-temperature zinc-containing and sulfur dioxide-containing flue gas of about 700-800°C discharged from the rotary kiln tail in step 2 is recovered by the waste heat recovery device, and the flue gas temperature is reduced to 350-360°C and then enters the surface cooler and further cooled to 120-130°C before entering the bag filter. Under the filtering condition of the bag filter, the zinc oxide product in the flue gas is separated in powder form, and the output of the zinc oxide product is about 1t / h; sulfur dioxide is discharged with the flue gas, and the amount of discharged flue gas is 100,000Nm 3 / h, sulfur dioxide concentration in flue gas 1500mg / Nm 3 .

[0037] Step 4: zinc oxide slurry preparation and storage, specifically, all the 1 t / h zinc oxide product produced in step 3 is prepared into slurry, the zinc oxide product is prepared into a zinc oxide slurry with a concentration of 20% to 30%, and the prepared slurry is stored in a zinc oxide slurry tank.

[0038] Step 5: Sulfur-containing flue gas purification process, specifically, introducing the sulfur-containing flue gas at 120-130° C. after the bag filter in step 3 into the desulfurization purification tower through an induced draft fan, pumping the 38% zinc oxide slurry in the zinc oxide slurry tank in step 4 into the desulfurization purification tower through a pump, using a circulating pump in the desulfurization purification tower to contact the zinc oxide slurry with the sulfur-containing flue gas, removing sulfur dioxide from the flue gas and discharging the flue gas through a chimney, and the zinc oxide solution generates zinc sulfate and zinc sulfite solutions.

[0039] Step 6: Preparation of zinc sulfate: Oxygen is introduced into the desulfurization purification tower through an oxidation blower to oxidize the zinc sulfite into a zinc sulfate solution, and then the zinc sulfate solution is pumped into a filter press to produce a zinc sulfate product. The desulfurization tower system produces 0.35 t / h of zinc sulfate product.

[0040] A 93% concentrated dilute sulfuric acid solution is purchased from outside, and the 62% zinc oxide slurry in the zinc tetroxide slurry tank in the step is pumped into the reactor to react with the 93% concentrated dilute sulfuric acid solution purchased from outside to generate a zinc sulfate solution. The reaction system produces 0.57 t / h of zinc sulfate product, and the system produces a total of 0.92 t / h of zinc sulfate product.

[0041] In Example 2, the system produces 1 t / h of zinc oxide product, with an effective content of about 50% zinc oxide, about 6172 mol / h. The exhaust gas generated is 100,000 Nm 3 / h, the sulfur dioxide concentration in the flue gas is 1500mg / Nm 3 , the sulfur dioxide in the flue gas is 0.15t / h, about 2344mol / h. According to the material balance calculation, the zinc oxide product produced by the system is relatively abundant. After reacting with the sulfur dioxide in the flue gas, 0.62t / h of zinc oxide product can be left. The abundance is relatively large, but the quality of the zinc oxide product is not high, and it is difficult to sell it directly. The 93% concentration of sulfuric acid is purchased to convert all the zinc oxide products into zinc sulfate products, which are sold in the form of zinc sulfate products. In Example 2, a steel iron-containing zinc-containing solid waste treatment process system with a high zinc content and a low sulfur content is provided, which produces 7286t of zinc sulfate products annually.

[0042] Embodiment 3: As attached Figure 1 As shown, a process for treating iron and steel solid waste containing iron and zinc with low zinc content and high sulfur content, the process flow comprises the following steps:

[0043] Step 1: Pretreatment process of iron-containing and zinc-containing solid waste raw materials, specifically, pretreatment of iron-containing and zinc-containing solid waste by disc ball making process, preparing powdered iron-containing and zinc-containing solid waste into 10mm spherical materials, and then entering the calcination process.

[0044] Step 2: High-temperature calcination process of iron-containing and zinc-containing materials, specifically, calcining the spherical iron-containing and zinc-containing materials pretreated in step 1 in a rotary kiln at a high temperature of 1000-1300°C, recovering iron elements from the kiln head of the rotary kiln, and discharging zinc elements and sulfur dioxide gas from the kiln tail of the rotary kiln along with the flue gas.

[0045] Step 3: Zinc element and sulfur-containing flue gas separation process, specifically, the high-temperature flue gas containing zinc and sulfur dioxide at about 700-800℃ discharged from the tail of the rotary kiln in step 2 is recovered by the waste heat recovery device. The flue gas temperature is reduced to 350-360℃ and then enters the surface cooler and further cooled to 120-130℃ before entering the bag filter. Under the filtering condition of the bag filter, the zinc oxide product in the flue gas is separated in powder form, and the output of zinc oxide product is about 0.5t / h; sulfur dioxide is discharged with the flue gas, and the amount of flue gas discharged is 100000Nm 3 / h, sulfur dioxide concentration in flue gas 3000mg / Nm 3 .

[0046] Step 4: Preparation and storage of zinc oxide slurry: Prepare slurry of 0.5 t / h zinc oxide product produced in step 3 and 0.1 t / h purchased zinc oxide product, prepare the zinc oxide product into zinc oxide slurry with a concentration of 20% to 30%, and store the prepared slurry in a zinc oxide slurry tank.

[0047] Step 5: Sulfur-containing flue gas purification process, specifically, introducing the sulfur-containing flue gas at 120-130° C. after the bag filter in step 3 into the desulfurization purification tower through an induced draft fan, pumping the 20%-30% concentration of zinc oxide slurry in the zinc oxide slurry tank in step 4 into the desulfurization purification tower through a pump, using a circulating pump in the desulfurization purification tower to contact the slurry with the sulfur-containing flue gas, removing sulfur dioxide from the flue gas and discharging the flue gas through a chimney, and the zinc oxide solution generates zinc sulfate and zinc sulfite solutions.

[0048] Step 6: Preparation of zinc sulfate, specifically, introducing oxygen into the desulfurization purification tower through an oxidation blower, oxidizing zinc sulfite into zinc sulfate solution, pumping the solution into a filter press to produce a zinc sulfate product, and pumping the zinc sulfate solution produced in step 5 into a filter press to produce a zinc sulfate product. The system produces 0.75 t / h of zinc sulfate product.

[0049] In Example 3, the system produces 0.5 t / h of zinc oxide product, with an effective content of zinc oxide of about 50%, about 3086 mol / h. The exhaust gas generated is 100000 Nm3 / h, the sulfur dioxide concentration in the flue gas is 3000mg / Nm 3 , the sulfur dioxide in the flue gas is 0.3t / h, about 4688mol / h. According to material balance calculation, the zinc oxide product produced by the system is insufficient, and it reacts with the sulfur dioxide in the flue gas, and it is impossible to remove all the sulfur dioxide in the flue gas. Therefore, it is necessary to purchase zinc oxide products to supplement the insufficient zinc oxide in the system. According to material calculation, 0.1t / h of zinc oxide needs to be purchased. In Example 3, a steel iron-containing zinc-containing solid waste treatment process system with a high zinc content and a low sulfur content is provided, which produces 5977t of zinc sulfate products annually.

[0050] The present invention includes a pretreatment process for iron-containing and zinc-containing solid waste, a rotary kiln solid waste treatment process, and a kiln slag coolant recovery iron product process. The flue gas generated in the process of treating iron-containing and zinc-containing solid waste in the rotary kiln enters the bag filter after the heat exchange process of the waste heat boiler and the cooling process of the surface cooler. The bag filter separates the zinc oxide product and the flue gas rich in sulfur dioxide. The low-grade zinc oxide product generated after the bag filter is subjected to slurry preparation and slurry storage, and the flue gas rich in sulfur dioxide is removed by zinc oxide slurry. No new solid waste is generated in the process of removing sulfur dioxide from the flue gas. At the same time, the low-grade zinc oxide product generates a zinc sulfate product with higher quality, realizing a process technology of treating waste with waste.

[0051] The usage of the intermediate product zinc oxide is determined according to the molar number of sulfur dioxide in the flue gas to ensure that the emission concentration of sulfur dioxide in the flue gas meets the national environmental protection requirements. When the concentration of sulfur dioxide in the flue gas is very high and the zinc oxide produced in the solid waste treatment process is insufficient, zinc oxide products should be supplemented. When the concentration of sulfur dioxide in the flue gas is very low and the zinc oxide produced in the solid waste treatment process is excessive, sulfuric acid can be added to the system to convert all the zinc oxide produced in the solid waste treatment process into zinc sulfate products. The waste heat recovery device adopts a waste heat boiler.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for treating solid waste containing iron and zinc, characterized in that: Step 1: Pretreatment process of solid waste raw materials containing iron and zinc; Step 2: high temperature calcination process of iron and zinc containing materials; Step 3, separation process of zinc element and sulfur-containing flue gas; Step 4: preparing and storing zinc oxide slurry; Step 5: sulfur-containing flue gas purification process; Step six, preparation of zinc sulfate.

2. A process for treating solid waste containing iron and zinc according to claim 1, characterized in that: Step one specifically involves pre-treating the iron- and zinc-containing solid waste by cold briquetting or disc pelletizing, pressing the powdered iron- and zinc-containing solid waste into agglomerates, and then entering a calcination process.

3. A process for treating solid waste containing iron and zinc according to claim 2, characterized in that: Step 2: The iron-containing and zinc-containing materials pretreated in step 1 are subjected to high-temperature calcination in a rotary kiln, and the iron element is recovered from the kiln head of the rotary kiln, and the zinc element and sulfur dioxide gas are discharged from the kiln tail of the rotary kiln along with the flue gas.

4. A process for treating solid waste containing iron and zinc according to claim 3, characterized in that: In step three, the zinc-containing and sulfur dioxide-containing flue gas discharged from the rotary kiln tail in step two passes through a waste heat recovery device, a surface cooler, and then a bag filter to separate it into a zinc oxide product and a sulfur dioxide-containing flue gas.

5. A process for treating solid waste containing iron and zinc according to claim 1, characterized in that: In step 4, the zinc oxide product produced in step 3 is prepared into a slurry, and the prepared zinc oxide slurry is stored in a slurry tank for standby use.

6. A process for treating solid waste containing iron and zinc according to claim 1, characterized in that: In step 5, the sulfur dioxide-containing flue gas in the bag filter of step 3 is introduced into the desulfurization purification tower through an induced draft fan, and the zinc oxide slurry prepared in step 4 is pumped into the desulfurization purification tower through a pump. A circulating pump is used in the desulfurization purification tower to contact the zinc oxide slurry with the sulfur-containing flue gas. After the sulfur dioxide in the flue gas is removed, the flue gas is discharged through a chimney, and the zinc oxide solution generates zinc sulfate and zinc sulfite solutions.

7. A process for treating solid waste containing iron and zinc according to claim 1, characterized in that: Step 6: oxygen is introduced into the desulfurization purification tower through an oxidation blower to oxidize the zinc sulfite into a zinc sulfate solution, and then the zinc sulfate solution is pumped into a filter press to produce a zinc sulfate product.

Images