Metallurgical auxiliary material protecting slag and its preparation method and application

Abstract

The present application belongs to the technical field of steel continuous casting auxiliary materials in metallurgical industry, and provides a metallurgical auxiliary protection slag and a preparation method and application thereof. The metallurgical auxiliary protection slag provided by the present application takes phosphorous slag as a preparation raw material base material, the phosphorous slag is composed of homogenization, the melting temperature is stable, and the uneven melting phenomenon of the protection slag in the melting process can be avoided. In addition, the phosphorous slag is mostly in a glass phase, which ensures that the protection slag has good lubricating performance. Finally, the phosphorous slag has large production and low price, which not only solves the storage, land occupation and pollution problems of the phosphorous slag, but also greatly reduces the cost of the protection slag. Fluorite is a control material of the viscosity of the protection slag: in a molten state, the F ‑ can block the Si 4+ and O 2‑ particles to form a network structure, so as to reduce the melting point and viscosity of the protection slag, improve the fluidity of the molten state of the protection slag, and make the protection slag have excellent spreading property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molten steel continuous casting auxiliary materials in metallurgical industry, and particularly relates to a metallurgical auxiliary material protecting slag and a preparation method and application thereof. BACKGROUND

[0002] The protecting slag, as an important metallurgical auxiliary material for continuous casting, plays an indispensable and important role in molten steel casting and has become a kind of established metallurgical auxiliary material and is widely used. From the initial mold casting, the powder protecting slag with graphite as a base material and artificial selection and mixing, to the present scientific mass production of protecting slag which is batch-standardized and matched with continuous casting machines and steel grades, although the unit consumption of the protecting slag is only 0.5 kg / ton of steel, the protecting slag plays a decisive role in the surface quality of the casting blank and is valued by metallurgical workers.

[0003] At the end of the last century, with the promotion of full continuous casting, higher requirements are put forward for the protecting slag, and the pre-melted protecting slag is favored, and the protecting slag plants under construction across the country have all started pre-melted furnaces. However, the cost of the pre-melted protecting slag is as high as 3000 yuan / ton or more.

[0004] With the continuous release of the steel industry capacity and the continuous improvement of the continuous casting equipment, the protecting slag, which was initially a favorite, gradually became an object of price compression. Therefore, optimizing the selection of raw materials for the protecting slag and reducing the cost of the protecting slag have become one of the important directions of research for metallurgical auxiliary material enterprises. SUMMARY

[0005] In view of this, the present application aims to provide a metallurgical auxiliary material protecting slag and a preparation method and application thereof. The metallurgical auxiliary material protecting slag provided by the present application has low cost.

[0006] In order to achieve the above-mentioned application purpose, the present application provides the following technical scheme:

[0007] The present application provides a metallurgical auxiliary material protecting slag, which comprises the following mass percentage of preparation raw materials:

[0008] Phosphorus slag 50% to 75%, fluorite 5% to 15%, sodium carbonate 8 to 15%, carbon additive 1% to 5%, high-carbon graphite 2% to 10%, and medium-super carbon black 1% to 5%.

[0009] Preferably, the preparation raw materials further comprise the following mass percentage of substances:

[0010] Quartz sand 0.1% to 4%, and glass powder 0.1% to 11%.

[0011] Preferably, the metallurgical auxiliary material protecting slag comprises the following mass percentage of ingredients:

[0012] CaO 31.21~37.19%, SiO2 31.69~34.28%, Al2O3 1.44~2.16%, MgO 2.4~4.40%, Fe2O3 0.53~0.84%, Na2O+K2O 4.32~7.43%, F - 2.02~5.66%, C 10.22%, S 0.02~2.02%, the balance being volatile matter.

[0013] Preferably, the particle size of the metallurgical auxiliary protecting slag is 0.25mm~2.0mm, and the water content is 0.2%~0.5%.

[0014] Preferably, the carbon additive includes one or more of petroleum coke, calcined white coal and semi-coke coal.

[0015] The application also provides a preparation method of the metallurgical auxiliary protecting slag.

[0016] The preparation raw materials and water are mixed, and then grinding and spray granulation are sequentially performed to obtain the metallurgical auxiliary protecting slag.

[0017] Preferably, the solid content of the slurry obtained by grinding is 50%~55%, the viscosity of the slurry is ≤1000 centipoise, and the fineness of the slurry is -300 mesh.

[0018] Preferably, the spray granulation includes the following steps: the slurry obtained by grinding is pumped into a spray drying tower through a high-pressure plunger mud pump;

[0019] The pressure of the high-pressure plunger mud pump is 2MPa;

[0020] The temperature of the slurry into the spray drying tower is 600℃;

[0021] The pressure of the spray drying tower is ≤300Pa;

[0022] The heating mode of the spray drying tower is a natural gas hot blast stove;

[0023] The inlet temperature of the spray drying tower is 480℃~650℃, and the outlet temperature of the bottom of the spray drying tower is 130℃~180℃.

[0024] The application also provides an application of the metallurgical auxiliary protecting slag in a carbon steel billet crystallizer.

[0025] Preferably, the continuous casting steel grade of the carbon steel billet crystallizer includes one or more of Q345, Q235, Q195 and 60Si2Mn; and the continuous casting speed of the carbon steel billet crystallizer is 1.2~4.5m / min.

[0026] The present application provides a metallurgical auxiliary protection slag, comprising the following mass percentage of raw materials: phosphorus slag 50% to 75%, fluorite 5% to 15%, sodium carbonate 8 to 15%, carbon additive 1% to 5%, high-carbon graphite 2% to 10%, and medium-super carbon black 1% to 5%. The metallurgical auxiliary protection slag provided by the present application takes phosphorus slag as the raw material base, and the phosphorus slag is composed of homogeneous crystal phase structure, which has stable melting temperature and can avoid uneven melting of the protection slag during melting. The homogeneous crystal phase structure makes the protection slag have better inclusions, which can adsorb inclusions in the molten steel. At the same time, after adsorbing inclusions, the physical properties change little. In addition, the raw material of the phosphorus slag itself has a wollastonite structure, which forms the phosphorus slag after water quenching treatment, so that the phosphorus slag has a crystal grain structure with multiple pores, a developed glass phase, a small bulk density, and thus can improve the heat preservation effect of the protection slag. The phosphorus slag with a developed glass phase can also improve the lubricity of the protection slag. At the same time, the small bulk density of the phosphorus slag can improve the gas permeability of the protection slag. In addition, the alkalinity (CaO / SiO2) of the phosphorus slag is generally about 1.17, which is close to the requirement of the protection slag, and the content of other elements in the phosphorus slag is low, which is convenient for the formula design of the protection slag. Finally, the production of the phosphorus slag is large and the price is low, which not only solves the storage and land pollution problems of the phosphorus slag, but also greatly reduces the production cost of the protection slag. The fluorite is a viscosity control material for the protection slag: in the molten state, the F - Can block Si 4+ and O 2- particles form a network structure, thereby reducing the melting point and viscosity of the protection slag, improving the fluidity of the molten state of the protection slag, and making the protection slag have excellent spreading property. It can be seen that the metallurgical auxiliary protection slag provided by the present application not only has low cost, but also has excellent lubricity, spreading property and gas permeability. The data of the examples show that the raw material cost of the metallurgical auxiliary protection slag provided by the present application is 1050 to 1200 yuan / ton.

[0027] The present application also provides a preparation method of the metallurgical auxiliary protection slag described in the above technical solution, comprising the following steps: mixing the raw materials and water, and then carrying out grinding and spraying granulation in sequence to obtain the metallurgical auxiliary protection slag. The preparation method provided by the present application is simple in operation and low in cost.

[0028] The present application also provides the application of the metallurgical auxiliary protection slag described in the above technical solution or the metallurgical auxiliary protection slag obtained by the preparation method described in the above technical solution in a carbon steel small square billet crystallizer. When the metallurgical auxiliary protection slag of the present application is applied, the protection slag provided by the present application has good spreading property, less slag strips, and the protection slag in the crystallizer is clean, which ensures the smooth process. DETAILED DESCRIPTION

[0029] The present application provides a metallurgical auxiliary protection slag, comprising the following mass percentage of raw materials:

[0030] Phosphorus slag 50%~75%, fluorite 5%~15%, sodium carbonate 8~15%, carbon additive 1%~5%, high-carbon graphite 2%~10%, medium-super carbon black 1%~5%.

[0031] The preparation raw material of the metallurgical auxiliary material protective slag provided by the application comprises phosphorus slag with a mass percentage of 50%~75%, preferably 55%~60%. In the application, the particle size of the phosphorus slag is preferably ≤300 mesh. In the application, the phosphorus slag is used as a preparation raw material base, and the phosphorus slag is composed of a homogeneous crystal phase structure, has stable melting temperature, and can avoid uneven melting of the protective slag in the melting process; and the homogeneous crystal phase structure makes the protective slag have better inclusions, can absorb inclusions in the molten steel, and the physical properties change little after absorbing the inclusions. In addition, the preparation raw material of the phosphorus slag itself has a wollastonite structure, and the phosphorus slag is formed by water quenching treatment, so that the phosphorus slag has a crystal grain structure with multiple pores, a developed glass phase, small bulk density, and further improved heat preservation effect of the protective slag; and the protective slag with the developed glass phase can also improve the lubricity of the protective slag; at the same time, the small bulk density of the phosphorus slag can improve the gas permeability of the protective slag. In addition, the alkalinity (CaO / SiO2) of the phosphorus slag is generally about 1.17, close to the requirement of the protective slag, and the content of other elements in the phosphorus slag is low, facilitating the formula design of the protective slag. Finally, the production of the phosphorus slag is large, and the price is low, which not only solves the storage, land occupation and pollution problems of the phosphorus slag, but also greatly reduces the production cost of the protective slag. It can be seen that the protective slag prepared by taking the phosphorus slag as a basic raw material has the advantages of heat preservation, lubrication, heat transfer control, inclusion absorption and prevention of secondary oxidation.

[0032] The preparation raw material of the metallurgical auxiliary material protective slag provided by the application comprises fluorite with a mass percentage of 5%~15%, preferably 8%~14%. In the application, the particle size of the fluorite is preferably ≤300 mesh. In the application, the fluorite is a material for controlling the viscosity of the protective slag: in a molten state, F - Can block Si 4+ and O 2- particles form a network structure, thereby reducing the melting point and viscosity of the protective slag, improving the flowability of the protective slag in a molten state, and making the protective slag have excellent spreading property.

[0033] The preparation raw material of the metallurgical auxiliary material protective slag provided by the application comprises sodium carbonate with a mass percentage of 8~15%, preferably 8%~11%. In the application, the particle size of the sodium carbonate is preferably ≤300 mesh. In the application, the sodium carbonate can reduce the melting point of the protective slag; at the same time, the sodium carbonate can decompose and release CO2 at high temperature, and play a role of active atmosphere in the use process of the protective slag.

[0034] The preparation raw material of the metallurgical auxiliary protective slag provided by the present application comprises 1-5% of carbon additive, preferably 2-4%. In the present application, the particle size of the carbon additive is preferably ≤300 mesh.

[0035] The preparation raw material of the metallurgical auxiliary protective slag provided by the present application comprises 2-10% of high-carbon graphite, preferably 5-8%, and further preferably 6-7%. In the present application, the particle size of the high-carbon graphite is preferably ≤300 mesh.

[0036] The preparation raw material of the metallurgical auxiliary protective slag provided by the present application comprises 1-5% of medium-super carbon black, preferably 2-4%. In the present application, the particle size of the medium-super carbon black is preferably ≤300 mesh.

[0037] In the present application, the carbonaceous materials (carbon additive, high-carbon graphite and medium-super carbon black) can block the aggregation of the molten droplets of the protective slag, ensure the protective slag to have a molten layer, a sintered layer and a powder slag layer on the surface of the molten steel in continuous casting, avoid over-sintering, and form slag strips. The carbonaceous materials consume the oxygen on the surface of the molten steel by combustion, avoid the oxidation of the molten steel, and stir the powder slag by the flame out of the combustion, thus actively the slag surface of the crystallizer, so as to ensure the protective slag to have a clean structure. Since the ignition points of the carbon additive, the high-carbon graphite and the medium-super carbon black are different (the ignition point of the graphite is the highest, the ignition point of the carbon additive is in the middle, and the ignition point of the carbon black is the lowest), the control of different temperature zones can be achieved.

[0038] The preparation raw material of the metallurgical auxiliary protective slag provided by the present application preferably further comprises 0.1-4% of quartz sand, and further preferably 3-4%. In the present application, the particle size of the quartz sand is preferably ≤300 mesh. In the present application, the quartz sand can adjust the content of SiO2 in the finished product of the protective slag and optimize the basicity (CaO / SiO2).

[0039] The preparation raw material of the metallurgical auxiliary protective slag provided by the present application preferably comprises 0.1-11% of glass powder, and further preferably 9-11%. In the present application, the particle size of the glass powder is preferably ≤300 mesh. In the present application, the glass powder can optimize the composition of the protective slag, and the glass powder contains Na + , so as to reduce the melting point of the protective slag and optimize the cost structure.

[0040] In the present application, the metallurgical auxiliary protective slag preferably comprises the following components with the following mass percentages:

[0041] CaO 31.21-37.19%, SiO2 31.69-34.28%, Al2O3 1.44-2.16%, MgO 2.4-4.40%, Fe2O3 0.53-0.84%, Na2O+K2O 4.32-7.43%, F - 2.02-5.66%, C 10.22%, S 0.02-2.02%, the balance being volatile.

[0042] The metallurgical auxiliary protective slag provided by the application comprises CaO with a mass percentage of 31.21-37.19%.

[0043] The metallurgical auxiliary protective slag provided by the application comprises SiO2 with a mass percentage of 31.69-34.28%.

[0044] The metallurgical auxiliary protective slag provided by the application comprises Al2O3 with a mass percentage of 1.44-2.16%.

[0045] The metallurgical auxiliary protective slag provided by the application comprises MgO with a mass percentage of 2.4-4.40%.

[0046] The metallurgical auxiliary protective slag provided by the application comprises Fe2O3 with a mass percentage of 0.53-0.84%.

[0047] The metallurgical auxiliary protective slag provided by the application comprises Na2O+K2O with a mass percentage of 4.32-7.43%.

[0048] The metallurgical auxiliary protective slag provided by the application comprises F with a mass percentage of 2.02-5.66%. - .

[0049] The metallurgical auxiliary protective slag provided by the application comprises C with a mass percentage of 10.22%.

[0050] The metallurgical auxiliary protective slag provided by the application comprises S with a mass percentage of 0.02-2.02%.

[0051] The metallurgical auxiliary protective slag provided by the application comprises the balance of volatile.

[0052] In the application, the particle size of the metallurgical auxiliary protective slag is preferably 0.25-2.0 mm, and the water content is preferably 0.2%-0.5%.

[0053] The application further provides a preparation method of the metallurgical auxiliary protective slag.

[0054] The preparation raw materials and water are mixed, and grinding and spray granulation are sequentially performed to obtain the metallurgical auxiliary protective slag.

[0055] In the present application, the refining method is preferably agitator refining.

[0056] In the present application, the solid content of the pulp obtained by refining is preferably 50% to 55%; the viscosity of the pulp is preferably ≤1000 centipoise, further preferably 500 to 800 centipoise, more preferably 600 to 700 centipoise; and the fineness of the pulp is preferably -300 mesh.

[0057] In the present application, the spray granulation preferably comprises the following steps: pumping the pulp obtained by refining into a spray drying tower by a high-pressure plunger mud pump. In the present application, the pressure of the high-pressure plunger mud pump is preferably 2 MPa; the temperature of the pulp into the spray drying tower is preferably 600°C; the pressure of the spray drying tower is preferably ≤300 Pa; the heating method of the spray drying tower is preferably a natural gas hot air furnace; the tower top inlet temperature of the spray drying tower is preferably 480°C to 650°C, and the tower bottom outlet temperature is preferably 130°C to 180°C.

[0058] The present application also provides the application of the metallurgical auxiliary protecting slag prepared by the above-mentioned technical solution or the preparation method of the metallurgical auxiliary protecting slag in a carbon steel billet crystallizer.

[0059] In the present application, the continuous casting steel grade of the carbon steel billet crystallizer preferably comprises one or more of Q345, Q235, Q195 and 60Si2Mn. In the present application, the continuous casting speed of the carbon steel billet crystallizer is preferably 1.2 to 4.5 m / min; and the continuous casting section is preferably 120x120 mm 2 , and the thickness of the liquid slag layer poured is preferably 8 to 12 mm.

[0060] The metallurgical auxiliary protecting slag, the preparation method and the application thereof provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0061] Example 1

[0062] The preparation raw materials are weighed according to the following mass percentage: phosphorus slag 50%, fluorite 14%, soda ash 11%, petroleum coke carbon additive 4%, high-carbon graphite 6%, medium-super carbon black 2%, quartz sand 4%, and glass powder 9%.

[0063] The preparation raw materials and water are mixed, and the obtained slurry (solid content 55%, fineness -300 mesh, viscosity 680 centipoise) is pumped into a spray drying tower for spray granulation by a high-pressure plunger slurry pump (pressure 2 MPa) (the temperature of the slurry into the spray drying tower is 600 ℃, the pressure of the spray drying tower is ≤300 Pa; the heating mode of the spray drying tower is a natural gas hot blast stove; the inlet temperature of the top of the spray drying tower is 650 ℃, and the outlet temperature of the bottom is 155 ℃) to obtain the protective slag.

[0064] The specific gravity of the obtained protective slag is 0.6 g / cm 3 , the moisture content is 0.35%, and the particle size of 0.25-1.6 mm accounts for more than 95%.

[0065] The cost of the obtained protective slag is 1200 yuan / ton.

[0066] Example 2

[0067] The preparation raw materials are weighed according to the following mass percentage: phosphorus slag 58%, fluorite 8%, soda ash 11%, petroleum coke carbonizer 4%, high-carbon graphite 6%, medium-super carbon black 2%, and glass powder 11%.

[0068] The preparation raw materials and water are mixed, and the obtained slurry (solid content 55%, fineness -300 mesh, viscosity 680 centipoise) is pumped into a spray drying tower for spray granulation by a high-pressure plunger slurry pump (pressure 2 MPa) (the temperature of the slurry into the spray drying tower is 600 ℃, the pressure of the spray drying tower is ≤300 Pa; the heating mode of the spray drying tower is a natural gas hot blast stove; the inlet temperature of the top of the spray drying tower is 650 ℃, and the outlet temperature of the bottom is 155 ℃) to obtain the protective slag.

[0069] The specific gravity of the obtained protective slag is 0.63 g / cm 3 , the moisture content is 0.2%, and the particle size of 0.25-1.6 mm accounts for more than 95%.

[0070] The cost of the obtained protective slag is 1100 yuan / ton.

[0071] Example 3

[0072] The preparation raw materials are weighed according to the following mass percentage: phosphorus slag 56%, fluorite 8%, soda ash 11%, calcined white coal carbonizer 4%, high-carbon graphite 6%, medium-super carbon black 2%, quartz sand 4%, and glass powder 9%.

[0073] The preparation raw materials and water are mixed, and the obtained slurry (solid content 55%, fineness -300 mesh, viscosity 680 centipoise) is pumped into a spray drying tower for spray granulation by a high-pressure plunger slurry pump (pressure 2 MPa) (temperature of the slurry into the spray drying tower 600 ℃, pressure of the spray drying tower ≤300 Pa; the heating mode of the spray drying tower is a natural gas hot blast stove; the inlet temperature of the top of the spray drying tower is 650 ℃, and the outlet temperature of the bottom is 150 ℃) to obtain the protective slag.

[0074] The specific gravity of the obtained protective slag is 0.62 g / cm 3 , the moisture content is 0.2%, and the particle size of 0.25-1.6 mm accounts for more than 95%.

[0075] The cost of the obtained protective slag is 1150 yuan / ton.

[0076] Example 4

[0077] The preparation raw materials are weighed according to the following mass percentage: phosphorous slag 75%, fluorite 5%, soda ash 8%, semi-coke carbon additive 4%, high-carbon graphite 6%, and medium-super carbon black 2%.

[0078] The preparation raw materials and water are mixed, and the obtained slurry (solid content 55%, fineness -300 mesh, viscosity 680 centipoise) is pumped into a spray drying tower for spray granulation by a high-pressure plunger slurry pump (pressure 2 MPa) (temperature of the slurry into the spray drying tower 600 ℃, pressure of the spray drying tower ≤300 Pa; the heating mode of the spray drying tower is a natural gas hot blast stove; the inlet temperature of the top of the spray drying tower is 650 ℃, and the outlet temperature of the bottom is 150 ℃) to obtain the protective slag.

[0079] The specific gravity of the obtained protective slag is 0.62 g / cm 3 , the moisture content is 0.2%, and the particle size of 0.25-1.6 mm accounts for more than 95%.

[0080] The cost of the obtained protective slag is 1150 yuan / ton.

[0081] The components of the protective slag obtained in Examples 1-4 are determined, and the results are shown in Table 1.

[0082] Table 1 Components of the protective slag obtained in Examples 1-4 (wt%)

[0083] Examples CaO / SiO2 CaO Al2O3 SiO2 MgO Na2O + K2O Fe2O3 F - ]]> [C 固 ]]> S Volatile matter 1 0.98 32.1 1.44 32.64 2.4 7.16 0.71 5.66 10.22 0.02 7.65 2 0.98 32.32 1.67 32.94 3.4 7.43 0.84 3.23 10.22 1.02 6.93 3 0.91 31.21 1.61 34.28 4.4 7.16 0.75 3.23 10.22 2.02 5.12 4 1.17 37.19 2.16 31.69 4.4 4.32 0.53 2.02 10.22 2.02 5.45

[0084] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A metallurgical auxiliary material protecting slag, characterized by, The preparation raw material comprises the following mass percentages of ingredients: 50%~75% of phosphorus slag, 5%~15% of fluorite, 8~15% of sodium carbonate, 1%~5% of carbon additive, 2%~10% of high-carbon graphite, and 1%~5% of medium-super carbon black; the carbon additive comprises one or more of petroleum coke, calcined white coal, and semi-coke coal; The metallurgical auxiliary protective slag comprises the following mass percentages of ingredients: CaO 31.21~37.19%, SiO2 31.69~34.28%, Al2O3 1.44~2.16%, MgO 2.4~4.40%, Fe2O3 0.53~0.84%, Na2O+K2O 4.32~7.43%, F - 2.02~5.66%, C 10.22%, S 0.02~2.02%, the balance is volatile.

2. The metallurgical adjunct protective slag according to claim 1, characterized in that, The preparation raw material further comprises the following mass percentages of substances: 0.1%~4% of quartz sand and 0.1%~11% of glass powder.

3. The metallurgical adjunct protective slag according to claim 1 or 2, characterized in that, The particle size of the metallurgical auxiliary protective slag is 0.25mm~2.0mm, and the water content is 0.2%~0.5%.

4. The method of producing a metallurgical auxiliary material covering flux according to any one of claims 1 to 3, characterized by, The method comprises the following steps: The preparation raw material and water are mixed, and then grinding and spray granulation are sequentially performed to obtain the metallurgical auxiliary protective slag; The solid content of the slurry obtained by grinding is 50%~55%, the viscosity of the slurry is ≤1000 centipoise, and the fineness of the slurry is -300 mesh; The spray granulation comprises the following steps: the slurry obtained by grinding is pumped into a spray drying tower through a high-pressure plunger mud pump; The pressure of the high-pressure plunger mud pump is 2MPa; The temperature of the slurry entering the spray drying tower is 600℃; The pressure of the spray drying tower is ≤300Pa; The heating mode of the spray drying tower is a natural gas hot air furnace; The inlet temperature of the top of the spray drying tower is 480℃~650℃, and the outlet temperature of the bottom is 130℃~180℃.

5. Application of the metallurgical auxiliary protective slag of any one of claims 1~3 or the metallurgical auxiliary protective slag obtained by the preparation method of claim 4 in a carbon steel billet crystallizer.

6. Use according to claim 5, characterized in that, The continuous casting steel grade of the carbon steel billet crystallizer comprises one or more of Q345, Q235, Q195, and 60Si2Mn; and the continuous casting speed of the carbon steel billet crystallizer is 1.2~4.5m / min.