Slagging constituent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hazardous waste resource utilization, and discloses a slag former and a preparation method and application thereof.The slag former is prepared from, by mass, 40% of anode carbon residues, 59% of sludge and 1% of adhesive; the method comprises the following steps: mixing anode carbon residues, sludge and a binder to obtain a mixture, and carrying out extrusion molding on the mixture to obtain the slag former. The anode carbon residues, the sludge and the binder are mixed according to the specific proportion to obtain the slag former, the slag former production and use processes cannot pollute the environment, the resource utilization of the anode carbon residues can be achieved, the sludge can be co-treated, and the slag former production cost is reduced. The preparation cost of the slag former is extremely low, and even the benefits can be increased for the treatment of anode carbon residues and sludge.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of hazardous waste, and particularly to a slag-forming agent and its preparation method and application. Background Art

[0002] Anode carbon slag is a by-product formed during the production process of aluminum electrolysis. The formation of anode carbon slag is mainly due to the partial erosion of the carbon anode by anode gas or oxidation by air in the high-temperature electrolyte, as well as the influence of factors such as electrolyte scouring, erosion by molten aluminum and electrolyte, and scouring. As a result, the surface of the anode carbon block is oxidized and becomes porous, and then falls off into the molten salt electrolyte. These fallen carbon particles are soaked and penetrated by the electrolyte for a long time, forming a mixed floating substance floating on the surface of the electrolyte. Anode carbon slag is mainly composed of elements such as carbon, fluorine, sodium, and aluminum, among which fluorine is likely to cause pollution to soil and groundwater. If it enters the human body through these channels, it will cause harm to the teeth, kidneys, bones, etc. of the human body.

[0003] Currently, the industrial disposal technologies for anode carbon slag mainly include wet disposal and pyrometallurgical disposal. Among them, in the wet disposal process, due to the high content of fluoride salts, the treatment difficulty is large and the disposal cost is high. Moreover, the carbon purity after this method of treatment does not meet the standards and can only be used as fuel, resulting in poor economic benefits; pyrometallurgical disposal has high energy consumption and will generate a large amount of fluoride gas, which will not only reduce the service life of the disposal equipment, but also cause air pollution if leakage occurs. Therefore, there is an urgent need to provide an anode carbon slag disposal technology with low disposal cost, low environmental harm and certain economic benefits. Summary of the Invention

[0004] In view of this, the present invention provides a slag-forming agent and its preparation method and application to solve the problems that the existing anode carbon slag process disposal technology will generate harmful gases, and the required cost is high and the economic benefits brought are low.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a slag-forming agent, comprising raw materials with the following mass percentages: 40% of anode carbon slag, 59% of sludge, and 1% of binder.

[0007] Preferably, the moisture content of the sludge ≤ 60%.

[0008] Preferably, the carbon content in the dry basis of the sludge ≥ 15%.

[0009] Preferably, the mass content of calcium oxide in the ash of the sludge ≥ 30%, and the mass content of silicon dioxide ≥ 8%.

[0010] Preferably, the viscosity of the binder ≥ 100 mPa·s, and the moisture content ≤ 5%.

[0011] Preferably, the binder is heavy oil.

[0012] Preferably, the anode carbon slag is a by-product in the aluminum electrolysis production process.

[0013] Preferably, the particle size of the anode carbon slag is ≤ 5 mm.

[0014] On the other hand, the present invention provides a preparation method of the slag-forming agent described in any one of the above, comprising the following steps:

[0015] (1) Mix the anode carbon slag, sludge and binder to obtain a mixture;

[0016] (2) Extrude and form the mixture to obtain the slag-forming agent.

[0017] Preferably, the pressure for extrusion molding is ≥ 30 MPa.

[0018] In addition, the present invention also provides an application of the slag-forming agent described in any one of the above or the slag-forming agent prepared by the method described in any one of the above in electric arc furnace steelmaking.

[0019] Preferably, for every ton of steel smelted, the usage amount of the slag-forming agent is 1 - 3 kg.

[0020] The present invention provides a slag-forming agent, its preparation method and application. Compared with the prior art, the beneficial effects are as follows:

[0021] The present invention mixes the anode carbon slag, sludge and binder in a specific proportion to obtain the slag-forming agent. The production and use processes of the slag-forming agent will not cause pollution to the environment. Moreover, the present invention can not only realize the resource utilization of the anode carbon slag, but also co-dispose the sludge. The preparation cost of the slag-forming agent is extremely low, and even the disposal of the anode carbon slag and sludge can obtain benefits, improving the economic benefits. Specific Embodiments

[0022] The present invention will be described below through specific embodiments. Those skilled in the art can understand that the following specific embodiments are only for the purpose of illustration and do not limit the scope of the present invention in any way. In addition, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If the specific treatment conditions and treatment methods are not clearly described in the following embodiments, the conditions and methods well known in the art can be used for treatment.

[0023] In one aspect of the present invention, the present invention provides a slag-forming agent, comprising raw materials with the following mass percentages: 40% of anode carbon slag, 59% of sludge, and 1% of binder.

[0024] The slag-forming agent of the present invention is prepared by mixing anode carbon slag, sludge and a binder according to the above-mentioned ratio. The calcium oxide and silicon dioxide in the sludge enable the slag-forming agent to have slag-forming ability. After the materials are mixed, the fluoride ion content can be relatively reduced, thereby reducing the risk of splashing due to excessively high fluoride ion content in the anode carbon slag and slowing down the corrosion of the furnace lining. In addition, the specific ratio of the anode carbon slag, the sludge and the binder can also reduce the carbon content in the mixed material, thereby preventing the melt from heating too fast to affect the fluidity of the molten steel, and avoiding the occurrence of splashing.

[0025] It should be noted that the main source of carbon in the present invention is anode carbon slag. If the melt temperature rises too slowly during the smelting process, it can be treated by adding a carburizer, and if the total carbon content is too high, it can be treated by blowing oxygen during the smelting process.

[0026] In some embodiments of the present invention, the moisture content of the sludge is ≤60%. If the moisture content in the sludge is too high, it will lead to a high moisture content in the slag-forming agent. If the moisture content is high during the steelmaking process, an explosion may occur. Therefore, considering safety, the moisture content of the sludge is controlled below 60%. However, it should be noted that as a raw material for the sludge forming agent, the lower the moisture content of the sludge, the better. However, considering that the lower the moisture content of the sludge, the higher the processing cost, based on cost-effectiveness considerations, the moisture content of the sludge is preferably 50-60%, for example, it can be 50%, 55%, 60, etc.

[0027] In some embodiments of the present invention, the carbon content of the sludge on a dry basis is ≥20%, that is, the mass content of carbon on a dry basis of the sludge is ≥20%. By limiting the carbon content in the sludge, the slag-making agent has a certain effect of a carburizer, thereby reducing the amount of carburizer used in the steelmaking process and reducing the steelmaking cost; in addition, the carbon-oxygen reaction of carbon in molten steel can heat the molten pool, and the converted carbon oxide bubbles can be stirred from bottom to top to stir the molten pool, so that the auxiliary materials are fully in contact with the molten steel, accelerating the slag-making process; and carbon can also act as a reducing agent to reduce the ferrous oxide in the slag-making agent to iron in the interface layer, and the process of further generating carbon dioxide from the generated carbon monoxide and oxygen can also provide heat for the molten pool and reduce energy consumption.

[0028] In some embodiments of the present invention, the mass content of calcium oxide in the ash of the sludge is ≥30%, and the mass content of silicon dioxide is ≥8%. The calcium oxide in the sludge can remove the fluorine element in the anode carbon slag, adjust the basicity of the slag, and improve the fluidity and desulfurization effect of the slag; the silicon dioxide in the sludge can adjust the viscosity and melting point of the slag-making agent, and reduce the use of the binder to a certain extent.

[0029] It should be noted that the specific source of the sludge in the present invention is not specifically limited. For example, it can be papermaking sludge, domestic sludge, etc.; and the other components in the sludge are also not specifically limited. For example, in addition to calcium oxide and silicon dioxide in the sludge ash, it may also contain silicon dioxide, iron oxide, etc.

[0030] In some embodiments of the present invention, the viscosity of the binder is ≥100 mPa·s, and the moisture content is ≤5%. The binder can be, for example, heavy oil. In the present invention, the sludge and the anode carbon slag are bonded together by the binder, and by limiting the moisture content of the binder to a lower value, the risk of explosion during the steelmaking process due to the generation of a large amount of water vapor can be effectively reduced, and the reaction of excessive moisture with fluoride ions to generate hydrogen fluoride gas can be avoided, which is more environmentally friendly.

[0031] In some embodiments of the present invention, the anode carbon slag is a by-product in the aluminum electrolysis production process. The main components in the anode carbon slag include carbon, fluorine, aluminum, and sodium. Among them, fluorine can destroy the silicate ions in the slag, achieving the purpose of a slag melting agent, enabling the slag to fully contact the molten steel and complete the impurity removal process; aluminum and sodium can act as deoxidizers in the later stage of melting, and the generated aluminum oxide can also improve the fluidity of the molten steel; the carbon in the anode carbon slag has the same function as the carbon in the sludge, which will not be elaborated here.

[0032] It should be noted that the present invention does not specifically limit the composition of the anode carbon slag, the content of each component, and other conditions, as long as it is generated in the aluminum electrolysis production process. For example, in the specific embodiment of the present invention, the anode carbon slag is composed of the following components by mass percentage: carbon 40.05%, fluorine 27.53%, aluminum 14.56%, sodium 12.26%, calcium oxide 2.21%, silicon dioxide 1.87%, iron oxide 1.52%, and the pH value is 5.82.

[0033] On the other hand, the present invention provides a preparation method of the slag melting agent according to any one of the above, including the following steps:

[0034] (1) Mix the anode carbon slag, the sludge, and the binder to obtain a mixture;

[0035] (2) Extrude the mixture into a slag melting agent.

[0036] In the present invention, first, the anode carbon slag, the sludge, and the binder are mixed to obtain a mixture.

[0037] In some embodiments of the present invention, before mixing the anode carbon slag with the sludge and the binder, the anode carbon slag is crushed to a particle size of ≤5 mm to make the mixing more uniform.

[0038] It should be noted that the present invention does not specifically limit the mixing process, as long as the anode carbon slag, sludge and binder are mixed evenly.

[0039] In some embodiments of the present invention, after obtaining the mixture, the mixture is extruded into a slag-making agent.

[0040] In some embodiments of the present invention, the pressure of the extrusion molding is ≥30 MPa. The extrusion molding process is carried out in an extruder, and no special limitation is imposed on the model of the extruder. The shape of the slag-making agent after extrusion can be strip-shaped, granular, etc.

[0041] In another aspect of the present invention, the present invention also provides an application of the slag-making agent described in any one of the above or the slag-making agent prepared by the method described in any one of the above in electric arc furnace steelmaking.

[0042] In some embodiments of the present invention, during the stock preparation and melting period in electric arc furnace steelmaking, the slag-making agent is added into the furnace. For every ton of steel smelted, the usage amount of the slag-making agent is 1 - 3 kg, for example, it can be 1 kg, 2 kg, 3 kg, etc.

[0043] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with specific embodiments. The embodiments of this application are only for illustration. All other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0044] Example 1

[0045] This example provides a slag-making agent, which is composed of the following raw materials by mass percentage: 40% anode carbon slag, 59% sludge, and 1% binder.

[0046] Among them, the anode carbon slag is composed of the following components by mass percentage: 40.05% carbon, 27.53% fluorine, 14.56% aluminum, 12.26% sodium, 2.21% calcium oxide, 1.87% silicon dioxide, 1.52% iron oxide, and the pH value is 5.82.

[0047] The sludge is papermaking sludge. The water content of the papermaking sludge is 60%. The carbon content in the dry basis of the papermaking sludge is 20%. The calcium oxide content in the ash of the papermaking sludge is 44%, the silicon dioxide content is 12%, the iron oxide content is 6%, and the aluminum oxide content is 4%.

[0048] The binder is a commercially available heavy oil binder, and the viscosity of the heavy oil binder is ≥100 mPa·s, and the water content is ≤5%.

[0049] This slag-making agent is prepared by the following method:

[0050] (1) Crush the anode carbon slag to a particle size of less than 5 mm, and then mix it evenly with sludge and binder to obtain a mixture;

[0051] (2) Extrude and form the mixture under a pressure of 30 MPa to obtain a cylindrical material, which is the slag-making agent.

[0052] During the charge preparation and melting period of the electric furnace smelting, add the slag-making agent of Example 1 to a 60-ton steelmaking electric furnace. When the dosage of the slag-making agent is 60 kg, the slag formation time is 14 min; when the dosage is 90 kg, the slag formation time is 15 min; when the dosage is 150 kg, the slag formation time is 16 min.

[0053] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A slag-forming agent, characterized in that: The method comprises the following raw materials in percentage by mass: 40% of anode carbon slag, 59% of sludge and 1% of adhesive.

2. The slag-forming agent according to claim 1, characterized in that The moisture content of the sludge is ≤60%, and the carbon content of the sludge on a dry basis is ≥15%; The mass content of calcium oxide in the ash of the sludge is ≥30%, and the mass content of silicon dioxide is ≥8%.

3. The slag-forming agent according to claim 1, characterized in that The viscosity of the binder is ≥100 mPa·s, and the water content is ≤5%.

4. The slag-forming agent according to claim 3, characterized in that: The binder is heavy oil.

5. The slag-forming agent according to claim 1, characterized in that: The anode carbon slag is a by-product in the aluminum electrolysis production process.

6. The slag-forming agent according to any one of claims 1 to 5, characterized in that: The particle size of the anode carbon slag is ≤5mm.

7. A method for preparing the slag-forming agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing anode carbon residue, sludge and a binder to obtain a mixture; (2) Extruding the mixture to obtain a slag-forming agent.

8. The method for preparing a slag-forming agent according to claim 7, characterized in that: The extrusion molding pressure is ≥30MPa.

9. Use of the slag-forming agent according to any one of claims 1 to 6 or the slag-forming agent prepared by the method according to any one of claims 7 to 8 in electric furnace steelmaking.

10. Use of the slag-forming agent according to claim 9 in electric furnace steelmaking, characterized in that: For each ton of steel smelted, the usage amount of the slag-forming agent is 1-3 kg.