Method for solidifying harmful components in hazardous wastes

Abstract

The invention relates to a method for curing harmful components in hazardous wastes, which comprises the following steps: uniformly mixing high-silicon iron tailings and blast furnace fly ash, adding the mixed material into chromium-containing waste liquid, stirring, carrying out plate-frame pressure filtration, carrying out pressure filtration again to obtain a mixed material, cutting the mixed material into blocks, drying the cut mixed material, and roasting after treatment to obtain a roasted product; carrying out rapid water cooling on the roasted product, and grinding after water cooling; and performing magnetic separation on the grinding product to obtain iron ore concentrate containing ferrochrome spinel and low-chromium tailings. According to the method, solid waste high-silicon iron tailings and blast furnace fly ash generated by iron and steel enterprises are used as curing agents, curing of heavy metal chromium in the chromium-containing sludge is achieved, the leaching rate of hexavalent chromium and total chromium in the obtained product is far lower than the standard limit value, harmless treatment of the chromium-containing sludge can be achieved, and the method is suitable for industrial production. The obtained ferrochrome spinel can be recovered through magnetic separation, and the generated low-chromium tailings can be directly subjected to landfill treatment or used as building materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial sludge treatment, relates to rolling steel sludge containing heavy metal chromium, and particularly relates to a method for solidifying harmful components in hazardous waste. Background Art

[0002] In the cold rolling production process of iron and steel enterprises, in order to improve the performance of steel plates, chromate passivation treatment is generally carried out on the steel plates. After the passivation wastewater undergoes chemical reduction, neutralization precipitation, and extrusion filtration, chromium-containing sludge will be formed. Because the sludge contains a large amount of heavy metal chromium that is easy to pollute the environment and threaten human health, it is listed as hazardous waste. The proper treatment of such sludge has become a common problem that iron and steel enterprises urgently need to solve.

[0003] China is the largest steel producer in the world. Iron and steel enterprises generate a large amount of chromium-containing sludge every year. Chromium mostly exists in the form of Cr(Ⅲ) in the sludge, and a small amount exists in the form of Cr(Ⅵ). The total chromium content can reach 3% - 12%. At present, the main treatment methods for chromium-containing sludge include landfill, production of cement, etc. Direct landfill is easy to occupy a large amount of land resources, and the dosage is limited when used in the production of cement or other building materials. Moreover, Cr(Ⅲ) in both methods has the risk of being oxidized to Cr(Ⅵ).

[0004] The patent document with the application number CN202110843003.1 titled "Method for High-Efficient Enrichment, Separation and Recovery of Chromium in Chromium-Containing Sludge from Steel Plant" includes the following steps: 1. Raw material treatment, first dry and crush the chromium-containing sludge, and then add a certain amount of Fe 2 O 3 and C powder, and prepare pellets after mixing well; 2. Reduction roasting, roast the pellets in the temperature range of 900 - 1000°C; 3. Magnetic separation, perform magnetic separation on the ground roasted product to obtain strong magnetic chromium concentrate and low-chromium tailings; 4. The low-chromium tailings can be used as raw materials for sintering batching or cement production. The invention realizes the high-efficient enrichment and separation of chromium in chromium-containing sludge, and extracts chromium in chromium-containing sludge by magnetic separation. However, this method does not completely solidify chromium in chromium-containing sludge, the chromium content in the obtained chromium-extracted tailings is still relatively high, and Cr(Ⅲ) in the tailings is easy to be oxidized to highly toxic Cr(Ⅵ), and there are still certain environmental risks.

[0005] The patent document with the application number CN202110880165.2 titled "A Metal Solidifying Agent and Its Application in Fixing Heavy Metal Chromium in Tanning Sludge" includes the following steps: 1. First, dry tanning sludge and TiO 2Mix and ball-mill with a metal solidifying agent composed of ZnO; 2. After fully drying the obtained mixture, conduct high-temperature calcination and store it under natural conditions. Through calcination, this invention can lattice the heavy metal chromium in the chromium-containing sludge well, effectively prevent its migration in the environment, and greatly inhibit the oxidation of trivalent chromium. However, the metal solidifying agent used in this method is composed of pure TiO 2 and ZnO, and the prices of both are relatively high, which will greatly increase the treatment cost.

[0006] The patent document with the application number CN201811456063.2 titled "A Method for Co-Treating Chromium-Containing Heavy Metal Sludge and Iron-Containing Dust Sludge" has the following steps in its solution: 1. Mix the chromium-containing heavy metal sludge and the iron-containing dust sludge to prepare a mixture with a total iron mass percentage content ≥ 25%; 2. Add a fixing agent (a mixture of calcium oxide and quartz), a flux (a mixture of sodium carbonate and sodium chloride), and a fluxing agent (borax or calcium chloride) for mixing and pelletizing to obtain green pellets; 3. After drying the green pellets, mix them with a reducing agent (bituminous coal, anthracite, or coke), and then directly reduce the green pellets mixed with the reducing agent at 1100 - 1250 °C to obtain calcined ore; 4. The calcined ore can obtain ferrochrome alloy and tailings through weak magnetic separation. This invention realizes the co-disposal of chromium-containing heavy metal sludge and iron-containing dust sludge, simultaneously recovers two valuable components, chromium and iron, and the chromium content in the obtained tailings is lower than 0.1%, which can be treated as ordinary solid waste. However, the fixing agent used in this method is a mixture of CaO and SiO 2 and CaO is extremely easy to react with SiO 2 to generate CaSiO 3 , and during the high-temperature calcination process, the presence of CaO will promote the conversion of trivalent chromium into hexavalent chromium. Therefore, the addition of this fixing agent remains to be further discussed.

[0007] The patent document with the application number CN202210148308.5 titled "A Method for Preparing Ceramsite Using Chromium-Containing Sludge" has the following steps in its solution: 1. Uniformly mix the chromium-containing sludge, divalent metal oxide, and clay to obtain a mixture; 2. Add water to the mixture for granulation and molding, and obtain green pellets after drying; 3. Calcinate the green pellets at 1000 - 1100 °C and then cool to room temperature to obtain ceramsite. By adding divalent metal oxide and clay, this invention realizes the fixation of chromium in the chromium-containing sludge, which can meet the limit values specified in the national standards, but the leaching concentrations of hexavalent chromium and total chromium are still relatively high, and there are still potential risks for long-term use.

[0008] The patent document with the application number CN202010167049.1 and the title "A Method for Separating and Enriching Chromium in Chromium-Containing Sludge" includes the following steps: 1. After drying and ball milling the chromium-containing sludge, it is mixed evenly with iron oxide to obtain a mixed material; 2. After pelletizing and drying the obtained mixed material, it is calcined at a temperature of 700-1200°C under the protection of an inert gas or a reducing gas, and after cooling after the calcination is completed, chromite spinel can be obtained. The invention realizes the enrichment of elemental chromium well through high-temperature calcination. Chromium is fixed in the chromite spinel phase, which can prevent trivalent chromium from being oxidized by air into hexavalent chromium, reducing the potential threat to the environment, and this method produces no waste liquid and is environmentally friendly. However, because this method involves gas-solid reactions, the particle size requirements for chromium-containing sludge are very high, which results in a large amount of energy consumption during the ball milling process, and it is relatively difficult to complete the reaction, and the reaction efficiency is relatively low.

[0009] There are certain limitations and drawbacks in the existing methods for fixing chromium in chromium-containing sludge. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for solidifying harmful components in hazardous waste, which can fix chromium in chromium-containing sludge at low cost and high efficiency. The present invention uses high-silicon iron tailings and blast furnace dust removal ash generated by iron and steel enterprises as solidifying agents to realize the solidification of heavy metal chromium in chromium-containing sludge. The leaching rates of hexavalent chromium and total chromium in the obtained product are far lower than the standard limits specified in the "Hazardous Waste Identification Standard - Toxicity Identification" (GB5085.3-2007), which can well realize the harmless treatment of chromium-containing sludge and achieve the purpose of treating waste with waste. The obtained chromite spinel can be recovered by magnetic separation, and the generated low-chromium tailings can be directly landfilled or used as building materials.

[0011] In order to achieve the above purpose, the present invention is realized by adopting the following technical solutions:

[0012] A method for solidifying harmful components in hazardous waste specifically includes the following method steps:

[0013] 1) Mix high-silicon iron tailings and blast furnace dust removal ash evenly to obtain a mixed material 1, and control the mass ratio of high-silicon iron tailings to blast furnace dust removal ash to be 1:(2-8);

[0014] 2) Add the mixed material 1 in step 1) to the chromium-containing waste liquid, stir well and then perform plate and frame pressure filtration to obtain a mixed material 2;

[0015] 3) Cut the mixed material 2 obtained by pressure filtration in step 2) to obtain a mixed material 3;

[0016] 4) Dry the mixed material 3 and send it to a high-temperature furnace for calcination to obtain a calcined product;

[0017] 5) Quench the calcined product obtained in step 4) rapidly with water, and then grind it after water cooling to obtain a ground product;

[0018] 6) Perform magnetic separation on the ground product obtained in step 5) to obtain iron concentrate containing chromite spinel and low-chromium tailings.

[0019] The moisture contents of the high-silica iron tailings and blast furnace dust are both controlled below 5%. The SiO 2 content in the high-silica iron tailings is 70 wt% - 85 wt%, the ZnO content in the blast furnace dust is 2 wt% - 12 wt%, and the Fe 2 O 3 content should be 15 wt% - 50 wt%.

[0020] The chromium-containing waste liquid must undergo detoxification pretreatment such as reduction and neutralization. It is required that more than 99% of Cr 6+ is reduced to Cr 3+ , and the total Cr content is lower than 20 g / L.

[0021] The mass ratio of the chromium-containing waste liquid to the mixed material 1 is controlled at 100:(40 - 80). During mixing, it is added while stirring to make it evenly mixed.

[0022] The particle size of the mixed material 3 is controlled at 20 - 80 mm.

[0023] In step 4), the mixed material 3 is dried, the drying temperature is controlled at 100 - 105 °C, and the moisture content of the dried material is controlled below 5%.

[0024] The heating rate of the calcination is controlled at 5 - 10 °C / min, the calcination temperature is controlled at 800 - 1250 °C, and the holding time is controlled at 2 - 4 hours.

[0025] For the said calcination, a dust removal and recovery device is adopted to recover the zinc-containing dust that may be generated, reducing the risk of environmental pollution.

[0026] The particle size of the ground product is controlled such that the content of the particle size less than 0.074 mm is ≥80%.

[0027] For the said magnetic separation, anhydrous ethanol is first selected as a dispersant to pretreat the material to reduce the aggregation of particulate matter, and the magnetic field strength is controlled at 80 - 240 kA / m. In order to reduce the environmental risks caused by three solid wastes, namely high-silica iron tailings, blast furnace dust, and chromium-containing sludge, and solidify the chromium in the chromium-containing sludge, the present invention has invented a method for co-processing chromium-containing sludge using high-silica iron tailings and blast furnace dust, achieving a satisfactory solidification effect.

[0028] To reduce the environmental risk caused by the oxidation of Cr(III) to Cr(VI), the present invention provides a method for co-solidifying heavy metal chromium in rolling sludge using solid wastes from the iron and steel industry, achieving a satisfactory solidification effect.

[0029] The present invention proposes a method for co-solidifying heavy metal chromium in chromium-containing sludge using solid wastes from the iron and steel industry. High-silicon iron tailings generated by iron and steel enterprises and collected blast furnace bag dust are selected as solidification additives. The acidic oxide SiO in the high-silicon iron tailings 2 reacts with CaO in the chromium-containing sludge to form CaSiO 3 , inhibiting the oxidation of Cr(III) to Cr(VI) during the roasting process. And ZnO and Fe in the blast furnace bag dust 2 O 3 react with chromium in the chromium-containing sludge to form ZnCr 2 O 4 , Fe 3-x Cr x O 4 spinel, fixing chromium in the spinel structure and inhibiting the oxidation and migration of Cr(III). At the same time, the blast furnace dust contains carbon, which can provide a reducing atmosphere during the high-temperature roasting process, further inhibiting the oxidation of chromium and promoting the reduction of iron. The magnetic substances such as chromite spinel obtained after treatment can be recovered by magnetic separation, and the low-chromium tailings can be directly landfilled or used as building materials.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1) The present invention provides a method for fixing chromium in chromium-containing sludge, using high-silicon iron tailings and blast furnace dust from the iron and steel industry as solidifying agents. Compared with the prior art that uses commercial chemical agents as solidifying agents, the treatment cost is lower.

[0032] 2) The present invention mixes high-silicon iron tailings and blast furnace dust and then adds them to the chromium-containing waste liquid for pressure filtration. Compared with the process of mixing first and then briquetting, this method is simpler and easier to operate, with better mixing effect, more uniform distribution of chromium elements, and no need to add binders. The strength requirements of the briquettes can be met by relying on the pressure of the plate and frame filter press.

[0033] 3) Through high-temperature roasting, under the combined action of SiO in the high-silicon iron tailings 2 and ZnO and Fe in the blast furnace dust 2 O 3 , chromium in the chromium-containing sludge will be fixed in chromite spinel or zinc chromite spinel. At the same time, due to the presence of C in the blast furnace dust, the possibility of trivalent chromium being oxidized to hexavalent chromium is further reduced during the roasting process.

[0034] 4) The calcined product obtained by the present invention is rapidly cooled by water cooling. While avoiding the secondary oxidation of iron, it can promote the crushing of materials and improve the grindability of materials.

[0035] 5) The leaching method provided by the "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) is used to leach the iron concentrate containing chromite spinel and low-chromium tailings respectively. The concentrations of hexavalent chromium and total chromium in the leachate of the iron concentrate containing chromite spinel fluctuate between 0.01 - 0.6 mg / L and 0.01 - 0.7 mg / L respectively, and the concentrations of hexavalent chromium and total chromium in the leachate of low-chromium tailings fluctuate between 0.01 - 0.4 mg / L and 0.01 - 0.5 mg / L respectively. Both are far lower than the limit values of 5 mg / L for hexavalent chromium and 15 mg / L for total chromium specified in the "Hazardous Waste Identification Standard - Toxicity Identification" (GB 5085.3-2007), meeting the requirements of safety and environmental protection. Compared with the prior art, the fixation effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further illustrates the specific implementation manners of the present invention in combination with embodiments. The following embodiments are used to specifically illustrate the content of the present invention. These embodiments are only general descriptions of the content of the present invention and do not limit the content of the present invention.

[0038] The chromium-containing waste liquid selected in the example of the present invention has been pretreated for detoxification, and more than 99% of Cr 6+ is reduced to Cr 3+ , the total Cr content is 11.18 g / L, and the water content is 68.21%; the main components of high-silicon iron tailings are: SiO 2 : 80.32%, TFe: 13.92%, MgO: 0.63%, CaO: 0.58%, and the water content is 1.98%; the main components of blast furnace dust are: Fe 2 O 3 : 28.66%, C: 29.18%, SiO 2 : 5.86%, ZnO: 4.13%, CaO: 5.15%, and the water content is 1.56%.

[0039] Example 1:

[0040] The implementation steps of the method described in this example are as follows:

[0041] 1) Mix the high-silicon iron tailings and blast furnace dust evenly according to a mass ratio of 1:8 to obtain mixed material 1.

[0042] 2) Add the obtained mixed material 1 to the chromium-containing waste liquid while stirring. The mass ratio of the chromium-containing waste liquid to the mixed material 1 is 100:80. After mixing evenly, perform plate and frame pressure filtration to obtain mixed material 2.

[0043] 3) Cut the mixed material 2 obtained in step 2) to obtain mixed material 3 with a particle size of about 80 mm.

[0044] 4) Dry the mixed material 3 at 105 °C. When the moisture content is lower than 5%, send it to a muffle furnace for roasting. The heating rate is 5 °C / min, the roasting temperature is 1250 °C, and the roasting time is 4 hours. After roasting, obtain the roasted product.

[0045] 5) Rapidly water-cool the roasted product in step 4). After water-cooling, perform ball milling and crushing to obtain a ball-milled product with a particle size less than 74 microns ≥ 80%.

[0046] 6) Disperse the ball-milled product obtained in step 5) with anhydrous ethanol and perform magnetic separation under the condition of a magnetic field strength of 240 kA / m to obtain iron concentrate containing chromite spinel and low-chromium tailings.

[0047] 7) Use the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid-Nitric Acid Method" (HJ / T 299-2007) to leach the iron concentrate containing chromite spinel and low-chromium tailings, and detect the contents of hexavalent chromium and total chromium by inductively coupled plasma atomic emission spectrometry. The results show that the concentrations of hexavalent chromium in the leachate are 0.015 mg / L and 0.012 mg / L respectively, and the total chromium concentrations are 0.021 mg / L and 0.018 mg / L respectively, which are far lower than the requirement limits of 5 mg / L and 15 mg / L for hexavalent chromium and total chromium specified in "Hazardous Waste Identification Standard - Toxicity Identification" (GB 5085.3-2007), meeting the requirements of safety and environmental protection.

[0048] Example 2:

[0049] The implementation steps of the method described in this example are as follows:

[0050] 1) Mix high-silicon iron tailings and blast furnace dust removal ash evenly according to a mass ratio of 1:6 to obtain mixed material 1.

[0051] 2) Add the obtained mixed material 1 to the chromium-containing waste liquid while stirring. The mass ratio of the chromium-containing waste liquid to the mixed material 1 is 100:60. After mixing evenly, perform plate and frame pressure filtration to obtain mixed material 2.

[0052] 3) Cut the mixed material 2 obtained in step 2) to obtain mixed material 3 with a particle size of about 60 mm.

[0053] 4) The mixed material 3 is dried at 105°C. When the moisture content is lower than 5%, it is sent to a muffle furnace for roasting. The heating rate is 10°C / min, the roasting temperature is 1100°C, and the roasting time is 4 hours. After roasting, the roasted product is obtained.

[0054] 5) The roasted product in step 4) is rapidly water-cooled. After water-cooling, it is ball-milled and crushed to obtain a ball-milled product with a particle size less than 74 microns ≥ 80%.

[0055] 6) The ball-milled product obtained in step 5) is dispersed with absolute ethanol and subjected to magnetic separation under the condition of a magnetic field strength of 200 kA / m to obtain iron concentrate containing chromite spinel and low-chromium tailings.

[0056] 7) The leaching method provided by "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid-Nitric Acid Method" (HJ / T 299-2007) is used to leach the iron concentrate containing chromite spinel and low-chromium tailings, and the contents of hexavalent chromium and total chromium are detected by inductively coupled plasma atomic emission spectrometry. The results show that the concentrations of hexavalent chromium in the leachate are 0.022 mg / L and 0.018 mg / L respectively, and the total chromium concentrations are 0.035 mg / L and 0.026 mg / L respectively, which are far lower than the limit values of 5 mg / L and 15 mg / L for hexavalent chromium and total chromium specified in "Hazardous Waste Identification Standard - Toxicity Identification" (GB 5085.3-2007), meeting the requirements of safety and environmental protection.

[0057] Example 3:

[0058] The implementation steps of the method described in this example are as follows:

[0059] 1) High-silicon iron tailings and blast furnace dust are mixed evenly according to a mass ratio of 1:4 to obtain mixed material 1.

[0060] 2) The obtained mixed material 1 is added to the chromium-containing waste liquid while stirring. The mass ratio of the chromium-containing waste liquid to the mixed material 1 is 100:40. After mixing evenly, plate and frame pressure filtration is carried out to obtain mixed material 2.

[0061] 3) The mixed material 2 obtained in step 2) is cut into pieces to obtain a mixed material 3 with a particle size of about 40 mm.

[0062] 4) The mixed material 3 is dried at 100°C. When the moisture content is lower than 5%, it is sent to a muffle furnace for roasting. The heating rate is 5°C / min, the roasting temperature is 1000°C, and the roasting time is 3 hours. After roasting, the roasted product is obtained.

[0063] 5) Rapidly water-cool the calcined product in step 4), and perform ball milling and crushing treatments after water cooling to obtain a ball-milled product with a particle size less than 74 microns and ≥ 80%.

[0064] 6) Disperse the ball-milled product obtained in step 5) with absolute ethanol, and perform magnetic separation under the condition of a magnetic field strength of 160 KA / m to obtain iron concentrate containing chromite spinel and low-chromium tailings.

[0065] 7) Use the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) to leach the iron concentrate containing chromite spinel and low-chromium tailings, and detect the contents of hexavalent chromium and total chromium by inductively coupled plasma atomic emission spectrometry. The results show that the concentrations of hexavalent chromium in the leachate are 0.32 mg / L and 0.22 mg / L respectively, and the total chromium concentrations are 0.43 mg / L and 0.36 mg / L respectively, which are far lower than the requirement limits of 5 mg / L for hexavalent chromium and 15 mg / L for total chromium specified in "Hazardous Waste Identification Standard - Toxicity Identification" (GB 5085.3-2007), meeting the requirements of safety and environmental protection.

[0066] Example 4:

[0067] 1) Mix high-silicon iron tailings and blast furnace dust removal ash evenly according to a mass ratio of 1:2 to obtain mixed material 1.

[0068] 2) Add the obtained mixed material 1 to the chromium-containing waste liquid while stirring, where the mass ratio of the chromium-containing waste liquid to mixed material 1 is 100:40. After mixing evenly, perform plate and frame pressure filtration to obtain mixed material 2.

[0069] 3) Cut the mixed material 2 obtained in step 2) to obtain a mixed material 3 with a particle size of about 20 mm.

[0070] 4) Dry the mixed material 3 at 105 °C. When the moisture content is lower than 5%, send it to a muffle furnace for roasting treatment. The heating rate is 5 °C / min, the roasting temperature is 800 °C, and the roasting time is 2 hours. After roasting, a calcined product is obtained.

[0071] 5) Rapidly water-cool the calcined product in step 4), and perform ball milling and crushing treatments after water cooling to obtain a ball-milled product with a particle size less than 74 microns and ≥ 80%.

[0072] 6) Disperse the ball-milled product obtained in step 5) with absolute ethanol, and perform magnetic separation under the condition of a magnetic field strength of 80 KA / m to obtain iron concentrate containing chromite spinel and low-chromium tailings.

[0073] 7) The leaching method provided by "Leaching Method for Toxicity of Solid Wastes - Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) was used to leach the iron concentrate containing chromite spinel and low-chromium tailings, and the concentrations of hexavalent chromium and total chromium were detected by inductively coupled plasma atomic emission spectrometry. The results showed that the concentrations of hexavalent chromium in the leachate were 0.52 mg / L and 0.38 mg / L respectively, and the concentrations of total chromium were 0.64 mg / L and 0.46 mg / L respectively, which were far lower than the requirement limits of 5 mg / L for hexavalent chromium and 15 mg / L for total chromium specified in "Identification Standard for Hazardous Wastes - Toxicity Identification" (GB 5085.3-2007), meeting the requirements of safety and environmental protection.

Claims

1. A method for solidifying harmful components in hazardous waste, characterized in that: The specific steps include the following: 1) mixing high silicon iron tailings and blast furnace dust ash uniformly to obtain a mixed material 1, wherein the mass ratio of high silicon iron tailings to blast furnace dust ash is controlled to be 1:(2-8); 2) adding the mixed material 1 in step 1) into the chromium-containing waste liquid, stirring thoroughly and then performing plate-and-frame filter pressing to obtain a mixed material 2; 3) Cutting the mixed material 2 obtained by filter pressing in step 2) into pieces to obtain a mixed material 3; 4) drying the mixed material 3, and then roasting it to obtain a roasted product; 5) water-cooling the roasted product obtained in step 4), and then grinding it to obtain a ground product; 6) The pulverized product obtained in step 5) is subjected to magnetic separation to obtain an iron ore concentrate containing ferrochrome spinel and low-chromium tailings.

2. A method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The moisture content of the high-silicon iron tailings and blast furnace dust ash is controlled below 5%, the SiO2 content in the high-silicon iron tailings is 70wt% to 85wt%, the ZnO content in the blast furnace dust ash is 2wt% to 12wt%, and the Fe2O3 content should be 15wt% to 50wt%.

3. A method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The chromium-containing waste liquid is pre-treated to remove 99% of Cr 6+ Reduced to Cr 3+ , the total Cr content is less than 20g / L.

4. A method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The mass ratio of the chromium-containing waste liquid to the mixed material 1 is controlled at 100:(40-80).

5. The method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The particle size of the mixed material 3 is controlled at 20 to 80 mm.

6. A method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: In the step 4), the mixed material 3 is dried, the drying temperature is controlled at 100-105° C., and the moisture content of the dried material is controlled below 5%.

7. The method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The heating rate of the calcination is controlled at 5-10°C / min, the calcination temperature is controlled at 800-1250°C, and the heat preservation time is controlled at 2-4 hours.

8. The method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The roasting process uses a dust removal and recovery device to recover the zinc-containing dust generated.

9. A method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: The particle size of the grinding product is controlled to be less than 0.074 mm and the particle size content is ≥80%.

10. The method for solidifying harmful components in hazardous waste according to claim 1, characterized in that: In the magnetic separation, anhydrous ethanol is first selected as a dispersant to pretreat the material to reduce the aggregation of particles, and the magnetic field strength is controlled at 80-240KA / m.

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