A method for treating chromium-containing sludge by using waste dust removal bag and blast furnace dust removal ash

Abstract

The present application relates to a kind of method for treating chromium-containing sludge by waste dust cloth bag and blast furnace dust ash, waste dust cloth bag is calcined to obtain waste dust cloth bag calcined ash;Calcined ash is mixed with blast furnace dust ash;Mixed material 1 is added to chromium-containing waste liquid, plate-frame pressure filtration, and mixed material 2 is obtained;Carry out cutting processing, then carry out drying, after drying, calcination, the product of calcination is rapidly water-cooled, after water cooling, grinding is carried out, and the product of grinding is separated by magnetic separation, and chromium iron spinel iron concentrate containing chromium and low chromium tailings are obtained.The present application uses waste dust cloth bag and blast furnace dust ash as curing agent, realizes the solidification of heavy metal chromium in chromium-containing sludge, the leaching rate of hexavalent chromium and total chromium in the obtained product is far lower than the standard limit, realizes the harmless treatment of chromium-containing sludge, and reaches the purpose of waste control waste, the chromium iron spinel obtained can be recycled by magnetic separation, and the low chromium tailings produced can be directly landfilled or used as building materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solid waste harmless disposal, and particularly relates to a method for cooperatively treating chromium-containing sludge by using waste and old dust removal cloth bags and blast furnace dust removal ash. BACKGROUND

[0002] The bag-type dust collector has been widely applied in steel enterprises due to high dust removal efficiency, low emission concentration, strong ash removal capacity and other advantages. The cloth bag as the core of the bag-type dust collector needs to be replaced regularly due to limited service life and problems such as aging, damage, burning and blockage caused by environmental factors, which results in a large amount of waste and old dust removal cloth bags generated by the steel enterprises every year. Incineration is one of the most effective methods for realizing waste cloth bag reduction and harmless treatment. The cloth bag ash after incineration belongs to general solid waste and mainly contains CaO, SiO2 and other components, which has certain recycling value.

[0003] The blast furnace dust removal ash is a by-product carried out by blast furnace gas in the process of blast furnace ironmaking, which is mainly composed of iron and coke. According to different ironmaking raw materials and proportions, the contents of the two slightly fluctuate, but the blast furnace dust removal ash also contains a certain amount of zinc, which is an important factor causing the internal nodulation of the blast furnace and being not conducive to the stable and smooth operation of the blast furnace, and brings certain difficulties to the complete resource utilization of the blast furnace dust removal ash. For example, reasonable utilization of zinc in the blast furnace dust removal ash can well solve the above problems.

[0004] The steel enterprises will generate a certain amount of chromium-containing wastewater in the process of steel plate passivation treatment. The wastewater will form chromium-containing sludge after chemical reduction, neutralization and precipitation, and extrusion filtration. The chromium-containing sludge directly stored will easily pollute the environment and even threaten human health due to containing a certain amount of heavy metal chromium. How to reasonably dispose of the sludge has become a common problem to be solved by the steel enterprises.

[0005] China is the largest steel producer in the world. The steel enterprises will generate a large amount of waste and old dust removal cloth bags, blast furnace dust removal ash and chromium-containing sludge every year. Direct storage of the three will not only occupy a large amount of land resources, but also have certain environmental risks. Especially, the chromium-containing sludge is a hazardous waste. The trivalent chromium in the chromium-containing sludge has the risk of being oxidized into hexavalent chromium, and must be disposed of in compliance.

[0006] The patent document with application number CN202310365942.9 named "Method for cooperatively treating chromium-containing sludge, waste incinerator slag, and coal-based kaolin" includes the following steps: 1. uniformly mix fine particles of chromium-containing sludge, fine particles of waste incinerator slag, and fine particles of coal-based kaolin to obtain a mixture; 2. grind the mixture from step 1 and add water to obtain a slurry; the grinding time is 10-24 hours, and the grinding rate is 550-650 revolutions per minute; 3. microwave treat the slurry from step 2 and cure to obtain a solidified body. The invention achieves the solidification of chromium in chromium-containing sludge, but requires a planetary ball mill and microwave treatment during the treatment process, which has a high treatment cost.

[0007] The patent document with application number CN202210391445.1 named "Method for treating chromium-containing sludge in a steel plant" includes the following steps: 1. proportion chromium-containing sludge and blast furnace dust according to a weight percentage of 60-70%:30-40%; 2. proportion the mixture from step 1 with sintering raw fuel; 3. mix and granulate to obtain a secondary mixture; 4. perform air draft sintering on the secondary mixture to obtain a finished sintered ore. The invention achieves low-cost disposal and utilization of chromium-containing sludge in a steel plant, but since the blast furnace dust contains a certain amount of zinc, directly feeding it into the sintering process can easily increase the zinc load of the blast furnace, causing the blast furnace to form nodules and affecting the smooth production, so it is not the best treatment method.

[0008] The patent document with application number CN202310379332.4 named "Method for cooperatively treating tannery chromium-containing sludge and aluminum ash" includes the following steps: 1. mix, grind, and obtain a ground product from dry tannery chromium-containing sludge fine particles, aluminum ash fine particles, and sepiolite fine particles; 2. melt the ground product from step 1 and water quench to obtain water quenched slag. The invention uses the chemical properties of each component to achieve the solidification of chromium in chromium-containing sludge through a combination of mechanical chemical treatment, melting structure solidification, and water quenching glassification treatment, and simultaneously realizes the resource utilization of chromium-containing sludge and aluminum ash, but the melting temperature of this method reaches 1450-1600℃, which has a large energy consumption, and the water quenching operation after melting has a high risk coefficient.

[0009] It can be seen that the existing methods for fixing chromium in chromium-containing sludge have certain limitations and drawbacks. SUMMARY

[0010] The present application aims at providing a method for treating chromium-containing sludge by using waste dust removal cloth bags and blast furnace dust, which has low cost and high efficiency, uses waste dust removal cloth bags and blast furnace dust as solidifying agents to solidify heavy metal chromium in the chromium-containing sludge, and realizes harmless treatment of the chromium-containing sludge and the purpose of waste treatment by waste, and the chromium iron spinel obtained can be recycled by magnetic separation, and the low-chromium tailings can be directly landfilled or used as building materials.

[0011] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0012] A method for treating chromium-containing sludge by using waste dust removal cloth bags and blast furnace dust, specifically comprising the following method steps:

[0013] 1) Put the waste dust removal cloth bags into a muffle furnace and calcine at a temperature of 800-1000 DEG C for 80-120 minutes to obtain calcined ash of the waste dust removal cloth bags;

[0014] 2) Mix the calcined ash obtained in step 1) with blast furnace dust to obtain a mixture 1;

[0015] 3) Add the mixture 1 in step 2) to the chromium-containing waste liquid, stir thoroughly, and then perform plate and frame pressure filtration to obtain a mixture 2;

[0016] 4) Cut the mixture 2 in step 3) to obtain a mixture 3;

[0017] 5) Dry the mixture 3 in step 4), and then send it to a high-temperature furnace for calcination to obtain a calcined product;

[0018] 6) Rapidly water-cool the calcined product obtained in step 5), and then grind to obtain a ground product;

[0019] 7) Perform magnetic separation on the ground product obtained in step 6) to obtain chromium iron spinel iron concentrate and low-chromium tailings.

[0020] The waste dust removal cloth bag is a glass fiber cloth bag, and the SiO2 content in the calcined ash is greater than 50%.

[0021] The blast furnace dust has a water content of less than 5wt%, a ZnO content of 2wt%-10wt%, and a Fe2O3 content of 20wt%-50wt%; and the mixing mass ratio of the calcined ash to the blast furnace dust is controlled to be 1:(1-5).

[0022] The chromium-containing waste liquid is detoxified by reduction and neutralization, and the content of Cr is required to be more than 99% 6+ reduced to Cr 3 + , and the total Cr content is less than 20 g / L.

[0023] The mass ratio of the chromium-containing waste liquid to the mixture 1 is controlled to be 100:(50-80), and the mixture is stirred while adding to make the mixture uniform.

[0024] The particle size of the mixture 3 should be controlled to be 20-50 mm.

[0025] The mixture 3 is dried in the step 5), the drying temperature is controlled to be 100-105 DEG C, and the water content of the dried material is controlled to be less than 5 wt%.

[0026] In the step 5), the heating rate of the roasting is controlled to be 5-10 DEG C / min, the roasting temperature is controlled to be 900-1250 DEG C, and the holding time is controlled to be 2-4 hours.

[0027] The high-temperature furnace should have a dust removal and recovery device to recover the possible zinc-containing dust and reduce the risk of environmental pollution.

[0028] In the step 6), the water temperature is controlled to be 5-20 DEG C, the water quenching time is controlled to be 3-5 minutes, the water quenching water residue ratio is controlled to be (10-20):1, and the grinding particle size is controlled to be less than 0.074 mm, and the content of the particle size is greater than or equal to 80%.

[0029] The magnetic field strength of the magnetic separation is controlled to be 80-240 KA / m.

[0030] The present application is to reduce the environmental risk of three solid wastes, i.e., waste dust removal bag, blast furnace dust removal ash and chromium-containing sludge, solidify chromium in the chromium-containing sludge, and invent a method for cooperatively treating chromium-containing sludge by using waste dust removal bag and blast furnace dust removal ash, which achieves satisfactory solidification effect.

[0031] In the present application, the ash obtained by incinerating the waste dust removal bag and mixed with the blast furnace bag ash can be used as a solidification additive, the acidic oxide SiO2 in the waste dust removal bag ash reacts with CaO in the chromium-containing sludge to generate CaSiO3, which inhibits the oxidation of Cr(III) to Cr(VI) in the roasting process, and ZnO and Fe2O3 in the blast furnace bag dust removal ash react with chromium in the chromium-containing sludge to generate ZnCr2O4 and Fe 3-x Cr xO4 spinel, which fixes chromium in the spinel structure, inhibits the oxidation and migration of Cr(III), and the carbon contained in the blast furnace dust can provide a reducing atmosphere during high-temperature roasting, inhibit the oxidation of chromium, and promote the reduction of iron. The magnetic materials such as chromium-iron spinel obtained after treatment can be recovered by magnetic separation, and the low-chromium tailings can be directly landfilled or used as building materials.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] 1) The present application provides a method for treating chromium-containing sludge by using waste dust cloth bags and blast furnace dust, which has lower treatment cost than the prior art using commercial chemical agents as solidifying agents, and reduces the environmental risk of waste dust cloth bags and blast furnace dust storage, achieving the purpose of waste treatment with waste.

[0034] 2) The present application mixes waste dust cloth bag roasting slag and blast furnace dust uniformly and then adds it to chromium-containing waste liquid for pressure filtration. Compared with the prior art of mixing first and then briquetting, this method is simpler and more practical, has better mixing effect, more uniform distribution of elements, and more complete contact, and does not require the addition of binder, but relies on the pressure of the plate and frame filter press to meet the strength requirements of the briquettes, and the treatment cost is more economical.

[0035] 3) In the present application, through high-temperature roasting, the chromium in the chromium-containing sludge is fixed in chromium-iron spinel and zinc-chromium spinel under the joint action of SiO2 in waste dust cloth bag slag and ZnO and Fe2O3 in blast furnace dust, and due to the presence of C in blast furnace dust, a reducing atmosphere is provided during roasting, reducing the possibility of oxidation of trivalent chromium to hexavalent chromium.

[0036] 4) In the present application, the roasting product is rapidly cooled by water cooling, which can prevent secondary oxidation of iron, promote the crushing of the material, improve the wear resistance of the material, and save the grinding cost.

[0037] 5) The iron concentrate containing chromium-iron spinel and the low-chromium tailings are respectively leached by the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method" (HJ / T299-2007), and the concentrations of hexavalent chromium and total chromium in the leachate are in the range of 0.01mg / L-0.1mg / L and 0.01mg / L-0.1mg / L, respectively, which is far lower than the required limit of 5mg / L and 15mg / L of hexavalent chromium and total chromium in "Hazardous Waste Identification Standard-Toxicity Identification" (GB5085.3-2007), meeting the safety and environmental protection requirements, and the fixation effect is better than that of the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The process flowchart of the present application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the specific implementation methods of this invention will be further described below in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of this invention. These embodiments are only general descriptions of the content of this invention and do not limit the content of this invention.

[0040] The chromium-containing wastewater used in this invention example has undergone detoxification pretreatment such as reduction and neutralization, resulting in a chromium content of over 99%. 6+ Reduced to Cr 3+ The total Cr content was 10.13 g / L, and the moisture content was 71.23%. The main chemical components of the ash from the roasting of waste dust collector bags were: SiO2: 55.62%, TFe: 3.62%, MgO: 1.62%, CaO: 16.42%. The main components of the blast furnace dust were: Fe2O3: 26.45%, C: 28.22%, SiO2: 6.86%, ZnO: 4.22%, CaO: 6.14%, and the moisture content was 0.98%.

[0041] Example 1:

[0042] The implementation steps of the method described in this embodiment are as follows:

[0043] 1) Place the waste dust collector bags into a muffle furnace and roast them at 900℃ for 90 minutes to obtain the roasting ash residue of the waste dust collector bags;

[0044] 2) Mix the roasted ash obtained in step 1) with the blast furnace dust at a mass ratio of 1:5 to obtain mixture 1;

[0045] 3) Add the mixture 1 from step 2) to the chromium-containing waste liquid, wherein the mass ratio of the chromium-containing waste liquid to the mixture 1 is 100:80. After thorough stirring, perform plate and frame filter press to obtain mixture 2.

[0046] 4) Cut the mixture 2 from step 3) into pieces to obtain mixture 3 with a particle size of about 20 mm;

[0047] 5) The mixture 3 in step 4) is dried at 105℃. When the moisture content after drying is 3%, it is sent to a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 1250℃, and the calcination time is 4 hours. The calcined product is obtained after the calcination is completed.

[0048] 6) The calcined product obtained in step 5) is rapidly cooled with water at a water temperature of 5°C, a water-to-slag ratio of 20:1, and a water quenching time of 5 minutes. After water quenching, the product is ball-milled and crushed to obtain a ball-milled product with a particle size of less than 74 micrometers and ≥80%.

[0049] 7) The ground product obtained in step 6) is subjected to magnetic separation under the condition of a magnetic field strength of 240 KA / m to obtain a chromite spinel iron concentrate and a low-chromium tailing.

[0050] 8) The iron concentrate containing chromite spinel and the low-chromium tailing are subjected to leaching according to the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), and the content of hexavalent chromium and total chromium is detected by inductively coupled plasma atomic emission spectrometry. The results show that the concentration of hexavalent chromium in the leaching solution is 0.013 mg / L and 0.01 mg / L, respectively, and the concentration of total chromium is 0.022 mg / L and 0.016 mg / L, respectively, which are far lower than the required limit values of 5 mg / L and 15 mg / L for hexavalent chromium and total chromium in "Hazardous Waste Identification Standard-Toxicity Identification" (GB 5085.3-2007), meeting the safety and environmental protection requirements.

[0051] Example 2:

[0052] The method described in this example is implemented by the following steps:

[0053] 1) Put the waste dust cloth bag into a muffle furnace and calcine at a temperature of 1000℃ for 80 minutes to obtain calcined ash of the waste dust cloth bag;

[0054] 2) Mix the calcined ash obtained in step 1) with blast furnace dust at a mass ratio of 1:4 to obtain a mixture 1;

[0055] 3) Add the mixture 1 in step 2) to the chromium-containing waste liquid, wherein the mass ratio of the chromium-containing waste liquid to the mixture 1 is 100:70, and after sufficient stirring, a plate and frame filter is performed to obtain a mixture 2;

[0056] 4) Cut the mixture 2 in step 3) to obtain a mixture 3 with a particle size of about 30 mm;

[0057] 5) Dry the mixture 3 in step 4) at a temperature of 100℃, and when the moisture content after drying is 5%, send it to a muffle furnace for calcination, with a heating rate of 5℃ / min, a calcination temperature of 1100℃, and a calcination time of 3 hours, to obtain a calcination product.

[0058] 6) Rapidly water-cool the calcination product obtained in step 5), with a water temperature of 10℃, a water-quenching water residue ratio of 15:1, and a water-quenching time of 3 minutes, and then perform ball milling and crushing treatment to obtain a ball milling product with a particle size of less than 74 microns and a content of ≥80%.

[0059] 7) The ground product obtained in step 6) is subjected to magnetic separation under the condition of a magnetic field strength of 200 KA / m to obtain a chromite spinel iron concentrate and a low-chromium tailing.

[0060] 8) The iron concentrate containing chromite spinel and the low-chromium tailing are subjected to leaching according to the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), and the content of hexavalent chromium and total chromium is detected by inductively coupled plasma atomic emission spectrometry. The results show that the concentration of hexavalent chromium in the leaching solution is 0.025 mg / L and 0.016 mg / L, and the concentration of total chromium is 0.032 mg / L and 0.025 mg / L, respectively, which is far lower than the requirement limit of 5 mg / L and 15 mg / L for hexavalent chromium and total chromium in "Hazardous Waste Identification Standard-Toxicity Identification" (GB 5085.3-2007), meeting the safety and environmental protection requirements.

[0061] Example 3:

[0062] The method described in this example is implemented by the following steps:

[0063] 1) Put the waste dust cloth bag into a muffle furnace and calcine at a temperature of 800℃ for 120 minutes to obtain calcined ash of the waste dust cloth bag;

[0064] 2) Mix the calcined ash obtained in step 1) with blast furnace dust in a mass ratio of 1:2 to obtain a mixture 1;

[0065] 3) Add the mixture 1 in step 2) to the chromium-containing waste liquid, wherein the mass ratio of the chromium-containing waste liquid to the mixture 1 is 100:60, and after sufficient stirring, a plate and frame filter is performed to obtain a mixture 2;

[0066] 4) Cut the mixture 2 in step 3) to obtain a mixture 3 with a particle size of about 40 mm;

[0067] 5) Dry the mixture 3 in step 4) at 105℃, and when the moisture content is 1%, send it to a muffle furnace for calcination, with a heating rate of 10℃ / min, a calcination temperature of 1000℃, and a calcination time of 3 hours, to obtain a calcination product.

[0068] 6) Rapidly water-cool the calcination product obtained in step 5), with a water temperature of 15℃, a water-quenching water residue ratio of 10:1, and a water-quenching time of 4 minutes, and then perform ball milling and crushing treatment to obtain a ball milling product with a particle size of less than 74 microns and a content of ≥80%.

[0069] 7) The ground product obtained in step 6) is subjected to magnetic separation under the condition of a magnetic field strength of 160 KA / m to obtain a chromium-iron spinel-containing iron concentrate and a low-chromium tailing.

[0070] 8) The chromium-iron spinel-containing iron concentrate and the low-chromium tailing are subjected to leaching according to the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), and the content of hexavalent chromium and total chromium is detected by inductively coupled plasma atomic emission spectrometry. The results show that the concentration of hexavalent chromium in the leaching solution is 0.038 mg / L and 0.022 mg / L, respectively, and the concentration of total chromium is 0.052 mg / L and 0.034 mg / L, respectively, which are far lower than the required limit values of 5 mg / L and 15 mg / L for hexavalent chromium and total chromium, respectively, in "Hazardous Waste Identification Standard-Toxicity Identification" (GB 5085.3-2007), and meet the safety and environmental protection requirements.

[0071] Example 4:

[0072] The method described in this example is implemented by the following steps:

[0073] 1) The waste dust cloth bag is placed in a muffle furnace and calcined at a temperature of 950℃ for 110 minutes to obtain calcined ash of the waste dust cloth bag;

[0074] 2) The calcined ash obtained in step 1) is mixed with the blast furnace dust at a mass ratio of 1:1 to obtain a mixture 1;

[0075] 3) The mixture 1 in step 2) is added to the chromium-containing waste liquid, wherein the mass ratio of the chromium-containing waste liquid to the mixture 1 is 100:50, and after being fully stirred, a plate and frame filter pressing is performed to obtain a mixture 2;

[0076] 4) The mixture 2 in step 3) is subjected to cutting treatment to obtain a mixture 3 with a particle size of about 50 mm;

[0077] 5) The mixture 3 in step 4) is subjected to drying treatment at 105℃ until the moisture content is 3%, and then sent to a muffle furnace for calcination, with a heating rate of 10℃ / min, a calcination temperature of 900℃, and a calcination time of 2 hours. The calcination product is obtained.

[0078] 6) The calcination product obtained in step 5) is subjected to rapid water cooling, with a water temperature of 20℃, a water quenching slag ratio of 20:1, and a water quenching time of 5 minutes. After water quenching, ball milling and crushing treatment are performed to obtain a ball milling product with a particle size of less than 74 microns and a content of ≥80%;

[0079] 7) The ground product obtained in step 6) is subjected to magnetic separation under the condition of a magnetic field strength of 80 KA / m to obtain a chromium-iron spinel-containing iron concentrate and a low-chromium tailing.

[0080] 8) The iron concentrate containing chromite and low chromium tailings were leached by the leaching method provided in "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method" (HJ / T299-2007), and the content of hexavalent chromium and total chromium was detected by inductively coupled plasma atomic emission spectrometry. The results showed that the concentration of hexavalent chromium in the leaching solution was 0.055 mg / L and 0.036 mg / L, respectively, and the concentration of total chromium was 0.072 mg / L and 0.056 mg / L, respectively, which were 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" (GB5085.3-2007), meeting the safety and environmental protection requirements.

Claims

1. A method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust, characterized in that, Specifically, the methods and steps include the following: 1) The waste dust collector bags are roasted at a temperature of 800-1000℃ for 80-120 minutes to obtain the roasting ash residue of the waste dust collector bags; 2) Mix the roasted ash obtained in step 1) with the blast furnace dust to obtain mixture one; 3) Add the mixture from step 2) to the chromium-containing waste liquid, stir thoroughly, and then perform plate and frame filter press to obtain mixture 2; 4) Cut the mixture from step 3) into pieces to obtain mixture 3; 5) Dry the mixture from step 4), and then calcine it to obtain the calcined product; 6) The calcined product obtained in step 5) is cooled with water, and then ground to obtain the ground product. 7) The grinding product obtained in step 6) is subjected to magnetic separation to obtain iron concentrate containing chromium iron spinel and low chromium tailings; The waste dust collector bags are fiberglass bags, and the SiO2 content in the calcined ash is greater than 50%. The blast furnace dust contains: a moisture content of less than 5 wt%, a ZnO content of 2 wt% to 10 wt%, and a Fe2O3 content of 20 wt% to 50 wt%; the mixing mass ratio of the roasted ash and the blast furnace dust is controlled at 1:(1 to 5). In step 5), the heating rate of calcination is controlled at 5-10℃ / min, the calcination temperature is controlled at 900-1250℃, and the holding time is controlled at 2-4 hours. The acidic oxide SiO2 in the ash residue of waste dust collector bags reacts with CaO in chromium-containing sludge to form CaSiO3.

2. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, The chromium-containing waste liquid undergoes detoxification pretreatment, reducing chromium content by over 99%. 6+ Reduced to Cr 3+ Furthermore, the total Cr content is less than 20 g / L.

3. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, The mass ratio of the chromium-containing waste liquid to the first mixture is controlled at 100:(50-80). During mixing, the mixture is added while stirring to ensure uniform mixing.

4. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, The particle size of the mixture should be controlled between 20 and 50 mm.

5. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, In step 5), the mixture is dried at a temperature of 100-105°C and the moisture content of the dried material is controlled below 5 wt%.

6. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, In step 6), the water temperature is controlled at 5-20℃, the water quenching time is controlled at 3-5 minutes, the water quenching slag ratio is controlled at (10-20):1, and the grinding particle size is controlled to have a particle size content of less than 0.074mm ≥80%.

7. The method for co-treating chromium-containing sludge using waste dust collector bags and blast furnace dust as described in claim 1, characterized in that, The magnetic separation process involves controlling the magnetic field strength between 80 and 240 kA / m.

Images