CN104152682A - Method for harmlessly treating electroplating sludge in metallurgical sintering blast furnace - Google Patents

Abstract

The invention provides a method for harmlessly treating electroplating sludge in a metallurgical sintering blast furnace. The method comprises the following steps: firstly, pre-treated electroplating sludge and reducing metallurgical waste material are taken as raw materials to produce a spherical core; secondly, the spherical core is pre-coated, and then the pre-coated spherical core, sulfate pitch and metallurgical waste material are made into compound pellets by a secondary material compounding technology; finally, the compound pellets are put in a sintering blast furnace system. The method provided by the invention can solve the problem about reutilization of metallurgical waste material resources produced in large amounts by iron and steel enterprises as well as the problem of environmental pollution caused by a great amount of electroplating sludge containing heavy metals and hexavalent chromium and produced by electroplating enterprises, achieves harmless treatment of electroplating sludge and reutilization of metallurgical waste materials, and meanwhile improves the metallurgical performance of sintering and mixing materials.

Description

A method for harmless treatment of electroplating sludge using metallurgical sintering blast furnace

technical field

The invention belongs to the field of metallurgical ironmaking and steelmaking technology and hazardous and harmful solid waste treatment technology, and specifically relates to the production of pellets in metallurgical ironmaking, the production of steelmaking slagging agents and the harmless treatment technology for electroplating sludge. The recycling of metallurgical waste and metallurgical performance can realize the harmless treatment of electroplating sludge. the

Background technique

At present, for the recycling of metallurgical waste resources and the harmless treatment of electroplating sludge, all iron and steel enterprises and related electroplating production enterprises are facing the same problem, and there is no effective technology to completely solve it. Some iron and steel enterprises only consume a small amount of metallurgical waste, and a large amount of metallurgical waste has a direct restriction on the load of the production line. the

Electroplating sludge is solid waste produced by electroplating enterprises in the production process, which contains high concentrations of heavy metals Pb, Cd, Hg, Cr, Cu, Zn, etc., and electroplating sludge contains a large amount of hexavalent chromium, and hexavalent chromium is swallowed Inhalation poison/inhalation poison, skin contact may cause sensitivity, more likely to cause genetic defects, inhalation may cause cancer, and has persistent danger to the environment. in order to prevent its pollution to the environment. At present, conventional electroplating sludge treatment basically cannot achieve thorough and effective harmless treatment. the

Contents of the invention

In order to solve the problem of recycling of metallurgical waste resources produced by iron and steel enterprises and the environmental pollution caused by a large amount of electroplating sludge containing heavy metals and hexavalent chromium produced by electroplating enterprises, and to overcome the problem that the existing technology cannot completely process metallurgical waste and electroplating sludge Insufficient, the present invention provides a method for harmless treatment of electroplating sludge by metallurgical blast furnace, realizes harmless treatment of electroplating sludge and recycling of metallurgical waste, and at the same time improves the metallurgical properties of sintering and mixing materials. the

The technical solution adopted by the present invention to solve its technical problems is as follows:

A method for the harmless treatment of electroplating sludge by using a metallurgical sintering blast furnace, the method is to use the pretreated electroplating sludge and reducing metallurgical waste (such as reducing metallurgical ash) as raw materials to produce spherical cores, and then Pre-coat the ball core, and then use secondary material compounding technology to make composite pellets with sulfuric acid slag and metallurgical waste, and finally enter the sintering and blast furnace. Specific steps are as follows:

Step 1. Ball core production:

(1.1) First send the electroplating sludge into the deep dehydration equipment, and pretreat the electroplating sludge so that the water content is lower than 50%;

(1.2) Using electroplating sludge and reducing metallurgical waste (metallurgical gravity dust as the main material), the ball core with a diameter of 3 to 6 mm is produced by a coulter mixer; the ball core with a particle size of less than 3 mm enters the primary manufacturing nuclear disk nucleation;

Step 2. Core pre-coating:

(2.1) Ingredients: Send the reducing metallurgical waste into the pre-coating equipment synchronously with the electroplating sludge ball core in the proportion of 25-40% of the core weight, and the pre-coating equipment is a double-screw mixer;

(2.2) Pre-coating: a layer of shell is coated on the outside of the spherical core containing electroplating sludge through pre-coating equipment;

Step 3. Secondary compounding into balls: Finally, the ball core, sulfuric acid slag, and metallurgical waste are strengthened into balls in a disc pelletizer to make secondary material composite pellets with a diameter of 5 to 12 mm, and a compound pellet with ( 2 to 4) mm thick shell. the

Step 4. Metallurgical sintering: Mix the composite pellets into the sintering mix, send them into the sintering trolley as the sinter raw material, roast them in the sintering machine to form molten sinter, and enter the blast furnace to smelt the molten sinter to form Nickel-chromium-containing pig iron completes the harmless treatment of electroplating sludge and the recycling of metallurgical waste, and at the same time improves the metallurgical properties of the sintered mixture. the

The deep dehydration equipment, coulter mixer, disc pelletizer for primary nucleation, pre-coating equipment, disc pelletizer for secondary pelletization, sintering trolley, and blast furnace are sequentially connected by material conveyor belts to form a A production line, and the deep dehydration equipment, coulter mixer, disc pelletizer for primary nucleation, pre-coating equipment, and disc pelletizer for secondary pelletization are all arranged in a closed environment to prevent heavy The electroplating sludge of hazardous metals and their compounds forms secondary pollution. the

The active reducing composite binder should be added in the composite pelletizing of the secondary materials, and the proportion of the active reducing composite binder in the solid material is 12-18%. the

The active reduction composite adhesive is based on conventional metallurgical adhesives (such as bentonite and water glass in inorganic silicates, carboxymethyl cellulose in organics, humic acid, etc.) The water used is process water, coal slime, activator, and stabilizer, which are formed by high-speed dispersion and mixing. Among them, the activator and stabilizer can be selected from common types of metallurgical adhesives. the

The preparation ratio of the active reduction composite binder is shown in the following table:

The beneficial effect of the present invention is that, using the existing equipment and production line of metallurgical sintering and blast furnace, under the condition of not changing the original process, the electroplating sludge is harmlessly treated in the production process of conventional pellets at the same time, and the electroplating sludge is formed. The metallurgical composite pellets of sludge can not only make the sintering performance of sintering material greatly exceed that of conventional sintering ore, improve the metallurgical performance of sintering ore, greatly reduce costs, but also avoid electroplating sludge containing heavy and dangerous metals and their compounds during the treatment process Secondary pollution occurs, no new harmful substances are produced, and electroplating sludge does not cause diffuse pollution. While thoroughly and effectively treating electroplating sludge, it lays a good foundation for improving smelting technical and economic indicators, and at the same time ensures the resource regeneration of metallurgical waste and electroplating sludge Comprehensive utilization. The specific manifestation is as follows:

1. The present invention uses 40-60% electroplating sludge as the main material of the spherical core, and the rest is reducing metallurgical waste, and the electroplating sludge must be dehydrated and the water content is lower than 50%. , compressive strength, drop strength, etc. the best choice. The following is the mixing experiment of electroplating sludge and reducing metallurgical waste:

When the ratio of electroplating sludge to reducing metallurgical waste is 1:2, the moisture of the mixture is 12.1%, and when the ratio is 1:1.5, the moisture is 13.7%. The final moisture of the two is not much different, and the moisture of the mixture is both Suitable for ball making. When the ratio is 2:1, the moisture reaches 26.1%, and the moisture content of the mixture is relatively large. Considering the amount of reducing metallurgical waste and the moisture content of the mixture suitable for pelletizing, when the amount of electroplating sludge in the mixture is 20-70% Both can meet the granulation requirements of the ball core, but through the comprehensive analysis of the ball core balling rate, compressive strength, drop strength and other requirements through the test, the amount of electroplating sludge in the ball core is set at 40-60%. Reductive metallurgy The amount of waste is set at 60-40%, which can achieve the best effect. The specific performance is shown in the table below: 

Mixing ratio 1:2 data

However, when the mixing ratio of electroplating sludge and reducing agent is 2:1, the moisture content of the composite pellets is too high, resulting in a significant decline in the performance of the composite pellets in terms of drop strength and compressive strength, which is lower than that of metallurgical sintering. Requirements, see the table below:

2. The present invention adopts the pre-coating process step, adding reducing metallurgical waste pre-coating method, so that the electroplating sludge ball core and the added reducing metallurgical waste are specially wrapped in the pre-coating system equipment to form a layer The shielding layer does not produce secondary diffusion pollution of electroplating sludge during the production process, and improves the operability of the composite pellets of secondary materials. The metallurgical properties and quality of the secondary material composite pellet sintered ore, see the examples for comparative data. the

3. The present invention adopts sulfuric acid slag as the raw material for secondary pelletizing. The waste slag that can be used for ironmaking discharged during the production of sulfuric acid or sulfurous acid from sulfuric acid slag is used in the present invention to improve the iron grade of composite pellets. the

4. Recycling of metallurgical waste is a common problem in the production process of the iron and steel metallurgy industry, and it is one of the main solid wastes produced in smelting. Compared with the traditional recycling of metallurgical waste, it is suitable for pelletizing all metallurgical waste. Through the reuse of secondary material compound pelletizing technology, it can prevent the secondary diffusion and pollution of electroplating sludge, and the product has uniform particle size, good air permeability, and its performance greatly exceeds that of The traditional direct reuse can comprehensively improve the technical and economic indicators of the sintering machine, the emission of sinter waste gas and dust does not change significantly, the environmental protection benefits are extremely obvious, and its metallurgical performance is greater than that of pure metallurgical waste. Conventional metallurgical waste has almost no particle size, and direct utilization will seriously affect the air permeability of the sintering machine, and will also generate a large amount of waste gas and dust emissions. the

5. Recycling of ordinary metallurgical waste can neither increase the amount of molten steel nor increase the output of steel. The use of electroplating sludge secondary composite pellet sintering, in the process of recycling metallurgical waste and harmless treatment of electroplating sludge, electroplating sludge is not only used as a slagging agent, but also partially reduces the slagging agent used in the smelting process , to reduce CO ₂ emissions. Moreover, the reducing agent in the electroplating sludge pellet core and the metallurgical waste wrapped outside have certain reducibility, which can reduce consumption, and at the same time increase the content of useful metals such as chromium and titanium in molten steel, which is conducive to improving the quality of molten steel.

6. The secondary composite pellet technology of electroplating sludge can effectively prevent secondary diffusion pollution of chromium-containing solid waste, and the subsequent harmless treatment-recycling method can deal with most problems existing in electroplating sludge. Tests have proved that the electroplating sludge secondary composite pellets produced by the composite pelletizing technology of secondary materials of electroplating sludge can basically eliminate the diffusion pollution of electroplating sludge, so that the electroplating sludge can be completely sealed in the metallurgical In the waste shell, the back-end sintering and blast furnace harmless treatment can completely eliminate the hexavalent chromium in the electroplating sludge, completely eliminate the pollution of the electroplating sludge to the environment, and will not bring new pollution to the sinter and subsequent smelting . the

7. The present invention adopts secondary material composite balls—metallurgical sintering and blast furnace process technology line to carry out harmless treatment of hazardous solid waste (electroplating sludge) and comprehensive utilization of resources. The process flow is simple, and no need to establish a new high-temperature Detoxification equipment, less investment; the secondary composite ball process line is close to the metallurgical sintering, the raw materials (electroplating sludge, metallurgical waste) and the composite ball have a short transportation distance, the production connection is convenient, and the operation cost is low; the composite ball roasting does not affect the existing metallurgical sintering Process; composite balls can replace a certain amount of smelting raw materials. Therefore, the economic and social benefits of the process are significant. the

The following is the mechanism analysis of electroplating sludge secondary material compound pelletizing technology to treat electroplating sludge: 

1. Restoration performance

According to the current sintering process of metallurgical sintering, the sintering temperature will reach above 1200°C. If hexavalent chromium ions (Cr ⁶⁺ ) cannot be reduced in a highly oxidizing atmosphere, part of the trivalent chromium ions (Cr ³⁺ ) is oxidized to hexavalent chromium ions (Cr ⁶⁺ ), and other heavy metals and their compounds will also be oxidized to high-valent metal ions. Since the reducing metallurgical waste in the electroplating sludge ball core has reducing properties, and the metallurgical waste contains part of the reduced coal powder, it can be known from metallurgical principles that the chromium ions (Cr ³⁺ , Cr ⁶⁺ ), copper Ions (Cu ²⁺ ), lead ions (Pb ²⁺ ), zinc ions (Zn ²⁺ ), etc. are in a high-temperature reducing atmosphere, which will not form secondary pollution or produce new toxic substances, and will also be able to contain iron raw materials Partially restored.

The difference is that

2. Metallurgical properties:

1. Consolidation mechanism:

From the electroplating sludge and reducing metallurgical waste, a uniform reducing electroplating sludge ball core is formed through a disc pelletizer. After passing through the ball core pre-coating system, the mixture of sulfuric acid slag and metallurgical waste is pre-coated The electroplated sludge ball core enters the pelletizing disc machine to form the shell. Utilize the good bonding performance of the active-reduction composite binder liquid to produce sintered pellets that meet the metallurgical properties, which not only treats and reuses metallurgical waste, but also improves the air permeability of the sintered mix and increases the sintered mix. The reducing atmosphere causes a direct reduction reaction between the sinter and metallurgical waste, and generates a certain amount of sponge iron, which greatly improves the metallurgical performance index of the recycled sinter. the

2. Alkalinity:

The content of CaO in metallurgical waste is relatively high, and the secondary composite pellets of electroplating sludge also contain part of CaO, so the recycled pellets (secondary composite pellets containing chromium-containing solid waste) have a higher alkalinity than conventional metallurgical pellets. Slightly high, it is beneficial to reduce flux consumption in the blast furnace production process, optimize the proportion of sinter ore, finally increase the proportion of recycled pellets into the furnace, and improve the blast furnace production process system. the

In summary, the metallurgical performance indicators of the electroplating sludge secondary composite pellets produced by the secondary material composite pelletizing process are improved compared with conventional metallurgical pellets. Recycling and recycling waste can also improve the technical and economic indicators of ironmaking blast furnaces. While saving energy, reducing emissions, environmental protection, and treating social hazardous solid waste, it will create considerable social benefits and also create considerable economic benefits. the

Detailed ways

The method of the present invention is that electroplating sludge and reducing metallurgical waste are produced into ball cores as the main raw materials, and the reducing metallurgical waste is added in proportion to pre-coating, and the pre-coating is completed in the ball core pre-coating system and transported to the disc manufacturing The ball machine produces secondary composite pellets of electroplating sludge. the

The process of the present invention is achieved by successively passing through the dehydration equipment, coulter mixer, disc pelletizer for primary nucleation, pre-coating equipment, disc pelletizer for secondary pelletization, sintering trolley, and blast furnace. It is carried out on a production line connected by a material conveyor belt. The deep dehydration equipment, coulter mixer, disc pelletizer for primary nucleation, pre-coating equipment, and disc pelletizer for secondary pelletization are all arranged in a closed In order to ensure that there is no secondary diffusion pollution of electroplating sludge during the process of mixing, pelletizing and transportation. the

The process steps are as follows:

1. Production of electroplating sludge spherical core

40-60% of electroplating sludge and 60-40% of reducing metallurgical waste are mixed and stirred completely to form electroplating sludge spherical cores. the

A. Pretreat the electroplating sludge first, and use deep dehydration equipment to dehydrate it so that its water content is lower than 50%;

B. Ingredients: Mix the treated qualified electroplating sludge and reducing metallurgical waste in proportion to send

into the coulter mixer to produce electroplated sludge-containing pellets;

C. Spherical cores with a particle size of 3-6mm are sent to the pre-coating equipment, and those with a particle size of less than 3mm are sent to the primary nucleation disc equipment, and an appropriate amount of active reducing composite binder is added to produce the spherical core with electroplating sludge. the

2. Formation of electroplating sludge spherical core shielding layer

A. The electroplating sludge ball core is sent into the ball core pre-coating system, and the reducing metallurgical waste is synchronously added in the proportion of 25-40% of the electroplating sludge amount. the

B. Turn on the ball core pre-coating system to fully pre-coat the electroplating sludge ball core. The pre-coating system uses a double-screw mixer. the

3. Secondary material composite pelletizing

Using pre-coated electroplated sludge spherical core as raw material,

A. Send the pre-coated electroplating sludge ball core into the pelletizing disk; simultaneously add the mixture of sulfuric acid slag and metallurgical waste according to the ratio of ball core to 1: (1~2). the

B. The active reducing composite bonding liquid is sprayed in an amount of 12-18% of the specific gravity of the solid material, so that the electroplating sludge ball core, sulfuric acid slag, and metallurgical waste mixture are rolled to form composite pellets of the electroplating sludge secondary material. the

4. Metallurgical sintering:

Mix the composite pellets into the sintering mixture, send it into the sintering trolley as the sinter raw material, roast it in the sintering machine to form a molten sinter, and enter the blast furnace to smelt the molten sinter to form nickel-chromium-containing pig iron, and complete the electroplating Harmless treatment of sludge and recycling of metallurgical waste, while improving the metallurgical properties of sintered mixed materials. the

Reductive metallurgical waste can be gravity dedusting ash and sintering dedusting ash. the

The preparation ratio of the active reduction composite binder is shown in the following table:

. the

Here are a few specific examples of ingredients and a comparison of their detoxification effects with and without pre-coating:

Example 1: 40% electroplating sludge and 60% reducing metallurgical waste are used as raw materials for the ball core, the weight of the ball core is 1 kg, and the particle size is (3-6) mm. 30% (0.3kg) of the weight of the core is added with a pre-coating material (gravity dust removal) for pre-coating. Then the ball core is pre-coated according to the weight ratio of 1:1 (1.3kg) to cover the spherical shell with sulfuric acid Slag and sintering dust to form secondary composite pellets. After sintering, the hexavalent chromium is 1.31mg/L (less than the national standard 5mg/L), and the nickel is 0.5mg/L (less than the national standard 5mg/L).

Comparative example: 40% of electroplating sludge and 60% of reducing metallurgical waste are used as raw materials for the spherical core, the weight of the spherical core is 1 kg, and the particle size is (3-6) mm; Sinter the dedusted ash to form secondary composite pellets. After sintering, the hexavalent chromium is 2.35mg/L, and the nickel is 1.78mg/L. the

Example 2: 50% of electroplating sludge and 50% of reducing metallurgical waste are used as raw materials for the core, the weight of the core is 1 kg, and the particle size is (3-6) mm; 25% (0.25 kg) of the weight of the core is added with pre-coating material (gravity dust removal) for pre-coating. Then, according to the ratio of 1:1 (1.25kg) of the pre-coated ball core, add spherical shell material sulfuric acid slag and sintering dust to form a secondary composite pellet. After sintering, the hexavalent chromium is 1.5mg/L (less than the national standard 5mg/L), and the nickel is 1.1mg/L (less than the national standard 5mg/L)

Comparative example: 50% of electroplating sludge and 50% of reducing metallurgical waste are used as raw materials for the ball core, the weight of the ball core is 1 kg, and the particle size is (3-6) mm; After sintering, it was detected that hexavalent chromium was 2.80mg/L and nickel was 1.98mg/L. the

Example 3: 60% of electroplating sludge and 40% of reducing metallurgical waste are used as raw materials for the ball core, the weight of the ball core is 1 kg, and the particle size is (3-6) mm; pre-coating material gravity dust is added according to 40% of the weight of the ball core material 0.4kg, pre-coated. Then add the sulfuric acid slag of the spherical shell material and 2.8 kg of sintering dedusting ash according to the weight ratio of 1:2 to the pre-coated ball core to form a secondary composite pellet. After sintering, the hexavalent chromium is 0.21mg/L (less than the national standard 5mg/L), and the nickel is 0.8mg/L (less than the national standard 5mg/L). the

Comparative example: 60% of electroplating sludge and 40% of reducing metallurgical waste are used as raw materials for the ball core, the weight of the ball core is 1kg, and the particle size is (3-6) mm; then the spherical shell material is added in a ratio of 1:2 to the weight of the spherical shell 2kg. After sintering, it was detected that hexavalent chromium was 3.28mg/L and nickel was 2.5mg/L. the

As can be seen from the above data, although the detection of all comparative examples for leaching toxicity detects that the content of hexavalent chromium and nickel is less than the national standard, they are far greater than the content of the leaching toxicity of the product processed by this method. It can be seen that this method Among them, the pre-coating layer not only prevents the secondary pollution of electroplating sludge during material transportation, but also facilitates the detoxification treatment of electroplating sludge more thoroughly. The nickel and chromium in the electroplating sludge are reduced to elemental nickel and elemental chromium and enter the pig iron to form nickel-chromium-containing pig iron. the

Claims (3)

1. A method of utilizing metallurgical sintering blast furnace for harmless treatment of electroplating sludge, characterized in that: the method is to use pretreated electroplating sludge and reducing metallurgical waste as raw material to produce bulb core, and then The ball core is pre-coated, and then compound pellets are made of secondary material compounding technology with sulfuric acid slag and metallurgical waste, and finally enter the sintering blast furnace system; the specific steps are as follows: Step 1, core production: (1.1) First send the electroplating sludge into the dehydration equipment for deep dehydration, and pretreat the electroplating sludge so that its water content is lower than 50%; (1.2) Use electroplating sludge and reducing metallurgical waste to produce nuclei with a diameter of 3 to 6 mm through a coulter mixer; the nuclei with a particle size of less than 3 mm enter the primary nucleation disc for nucleation Step 2, core pre-coating: (2.1) Ingredients: Send the reducing metallurgical waste into the pre-coating equipment synchronously with the electroplating sludge ball core according to the proportion of 25-40% of the core weight, and the pre-coating equipment is a double-screw mixer; (2.2) Pre-coating: a layer of shell is coated on the outside of the spherical core containing electroplating sludge through pre-coating equipment; Step 3, secondary compounding into balls: finally, the ball core, sulfuric acid slag, and metallurgical waste are strengthened into pellets in a disc pelletizer to make secondary material composite pellets with a diameter of 5-12mm; Step 4, metallurgical sintering-blast furnace: mix the composite pellets into the sintering mixture, send it into the sintering trolley as the sinter raw material, roast in the sintering machine to form molten sinter, and the molten sinter enters the blast furnace Smelting to form nickel-chromium-containing pig iron, complete the harmless treatment of electroplating sludge and the recycling of metallurgical waste, and improve the metallurgical properties of sintering and mixing materials at the same time; The dehydration equipment, the coulter mixer, the disc pelletizer for primary nucleation, the pre-coating equipment, the disc pelletizer for secondary pelletization, the sintering trolley, and the blast furnace are sequentially connected into a single conveyor belt. The production line, and the deep dehydration equipment, coulter mixer, pre-coating equipment, disc pelletizer for primary nucleation and secondary pelletization are all arranged in a closed environment; In the primary nucleation and secondary material compound pelletizing, an active reduction composite binder should be added, and the proportion of the active reduction composite binder in the solid material is 12-18%. 2. The method for harmless treatment of electroplating sludge by metallurgical sintering blast furnace according to claim 1, characterized in that: the active reduction composite adhesive is a conventional metallurgical adhesive as the main raw material, adding water at a suitable temperature And coal slime, activator, stabilizer, formed by high-speed dispersion mixing; The preparation ratio of the active reducing composite binder is shown in the table below: . 3. The method for harmless treatment of electroplating sludge by metallurgical sintering blast furnace according to claim 1, characterized in that: the reducing metallurgical waste is solid dust waste produced in the smelting process that is not conducive to conventional smelting recycling, including gravity Dedusting ash, sintering dedusting ash.