Deoxidizing agent for steelmaking as well as preparation method and application of deoxidizing agent

Abstract

The invention discloses a deoxidizing agent for steelmaking. The deoxidizing agent is prepared from the following raw materials in parts by mass: 80-85 parts of silica, 25-35 parts of rare earth oxide pressed balls, 50-55 parts of a first carbonaceous reducing agent and 8-12 parts of steel cuttings. The invention further discloses a preparation method and application of the deoxidizing agent for steelmaking. According to the deoxidizing agent for steelmaking, the rare earth oxide pressed balls are selected as one of the raw materials, the materials are free of radioactivity, crushing, roasting and other links are not needed, the storage safety of the materials can be improved, occupational health of production personnel is guaranteed, the product quality is improved, and energy consumption is reduced. The deoxidizer for steelmaking solves the problems of limited utilization of rare earth resources, resource waste and the like, and has the advantages of good product quality, low material consumption and low smelting unit consumption.

Description

Technical Field

[0001] The invention relates to a deoxidizer for steelmaking, a preparation method and application thereof, and belongs to the technical field of steel deoxidizers. Background Art

[0002] Deoxidizer for steelmaking is an auxiliary material used in the refining process outside the furnace during the steel production process. It utilizes the activity of the main elements in the deoxidizer and its affinity with the oxygen element to form stable compounds under gas stirring, thereby achieving the purpose of reducing the oxygen content in molten steel.

[0003] Rare earth ferrosilicon alloy is an alloy product composed of a certain proportion of rare earth, silicon, iron and a small amount of calcium, aluminum and other elements. It is currently a widely used deoxidizer for steelmaking. At present, there are two production methods for rare earth ferrosilicon alloy: one is to use silica, cerium-rich slag or rare earth concentrate, steel scraps as raw materials, and use carbonaceous reducing agents to generate rare earth silicon alloys through a semi-closed ore-heating furnace reduction reaction, which is called the carbothermal method. Because the rare earth content in the rare earth raw materials is low and the fluorine and phosphorus content is high, the carbothermal method produces harmful gases during the production process, which is corrosive to the production equipment and harmful to human health. The amount of slag discharged during iron tapping is large, which affects the quality of the alloy, and the smelting unit consumption is high. The second is to use cerium-rich slag or rare earth concentrate to use ferrosilicon as a reducing agent to smelt rare earth ferrosilicon alloys through an electric arc furnace, which is called the silicon thermal method. The silicon thermal method has the disadvantages of overlapping energy consumption and high production costs. In the two methods of the prior art, the quality of rare earth raw materials is poor, and the products are prone to composition fluctuations and alloy powdering.

[0004] At present, the alloys used in steelmaking deoxidizers are mainly binary alloys of silicon, manganese and chromium, with limited options. However, the industry's demand for binary alloys is gradually decreasing, and the single product does not have a strong ability to resist risks. At the same time, my country has a large reserve of rare earths, and there are very few ways to use the rare earth oxides produced during the extraction of rare earths, resulting in a backlog of rare earth oxide resources. The utilization rate and development rate of rare earth oxides directly used in the preparation of rare earth ferrosilicon alloys are both low.

[0005] In view of this, it is necessary to develop a new deoxidizer for steelmaking to overcome the shortcomings of the prior art. Summary of the invention

[0006] One of the purposes of the present invention is to provide a deoxidizer for steelmaking.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: a deoxidizer for steelmaking is made of the following raw materials in parts by weight: 80-85 parts of silica, 25-35 parts of rare earth oxide pellets, 50-55 parts of a first carbonaceous reducing agent and 8-12 parts of steel scraps.

[0008] The rare earth raw materials used in the existing steelmaking deoxidizers are mostly rare earth concentrates and rare earth cerium-rich slag. Rare earth concentrates need to go through three steps of crushing, roasting and briquetting before entering the furnace. The production process is cumbersome, which increases the production cost and equipment cost. The total amount of rare earth oxides in rare earth concentrates is 50%-55%, and the total amount of rare earth oxides in rare earth cerium-rich slag is 10%-13%. Both materials contain more impurities, which have a great impact on the smelting process and product quality. Moreover, rare earth concentrates and rare earth cerium-rich slags contain a large proportion of phosphorus and fluorine, and are also radioactive.

[0009] The present invention adopts a new type of rare earth oxide briquette, which is made by recycling and enriching dust ash in the production process of rare earth materials. The material is non-radioactive and does not require crushing, roasting and other steps. It can improve the safety of material storage, ensure the occupational health of production personnel, improve product quality and reduce energy consumption.

[0010] The present invention selects rare earth oxide briquette as one of the raw materials for preparing deoxidizer for steelmaking, which has the following advantages: first, compared with rare earth concentrate and rare earth cerium-rich slag, the total amount of rare earth elements contained in the rare earth oxide is higher, which effectively reduces the content of trace elements, improves the element recovery rate, and helps to stabilize production; second, it plays a role in resource recycling, improves material quality, and has a promoting effect on energy conservation and consumption reduction and improving product quality.

[0011] Without being limited to any theory, the present invention has been subjected to many tests, utilizing the deoxidizing effect of silicon in silica, the enrichment of lanthanum and cerium in rare earth oxide pellets, the reducing effect of the first carbonaceous reducing agent, and the iron supplementation effect of steel scraps. Silicon and rare earth elements can form stable oxides with oxygen elements. It has been unexpectedly and surprisingly found that the deoxidizer for steelmaking obtained by using the above four raw materials and supplementing them with corresponding proportions has the advantages of good product quality, low material consumption, and low smelting unit consumption.

[0012] The beneficial effects of the steelmaking deoxidizer of the present invention are:

[0013] 1. The steelmaking deoxidizer of the present invention selects rare earth oxide pellets as one of the raw materials, which expands the utilization of rare earth resources, improves the utilization rate of rare earth resources, expands the selectivity of the steelmaking deoxidizer, and solves the problems of limited utilization of rare earth resources and waste of resources.

[0014] 2. The deoxidizer for steelmaking of the present invention has the advantages of good product quality, low material consumption and low smelting unit consumption.

[0015] Based on the above technical solution, the present invention can also be improved as follows.

[0016] Furthermore, the steelmaking deoxidizer is made of the following raw materials in mass parts: 83 parts of silica, 30 parts of rare earth oxide pellets, 52 parts of the first carbonaceous reducing agent and 10 parts of steel scraps. The above are the optimal parameters, and the obtained steelmaking deoxidizer has the best technical effect.

[0017] Furthermore, the mass percentage of SiO2 in the silica is greater than 98.5%, the mass percentage of Al2O3 is less than 0.8%, the particle size is 60mm-150mm, and the explosion resistance is 700℃-1000℃.

[0018] Furthermore, the mass percentage of total iron in the steel scrap is greater than 95%, the mass percentage of phosphorus is less than 0.03%, and the curling length is less than 20 mm. The steel scrap with the above parameters can obtain a better technical effect of the deoxidizer for steelmaking.

[0019] Furthermore, the steel scraps are replaced by iron pellets or iron oxide sheets. Iron pellets or iron oxide sheets can replace steel scraps, thereby reducing production costs.

[0020] Furthermore, the first carbonaceous reducing agent is any one of semi-coke, metallurgical coke and petroleum coke, or a mixture of several of them. The first carbonaceous reducing agent has a better reduction effect.

[0021] Furthermore, the mass percentage of fixed carbon in the semi-coke is >84%, the mass percentage of ash is <7%, the mass percentage of volatile matter is <9%, the mass percentage of average moisture is <15%, the powder rate is <1.5%, and the particle size of 6mm-18mm accounts for >85%; the mass percentage of fixed carbon in the metallurgical coke is >80%, and the particle size of 3mm-5mm accounts for >85%; the mass percentage of fixed carbon in the petroleum coke is >84%, the powder rate is <1%, and the particle size of 6mm-18mm accounts for >80%. The carbonaceous reducing agent with the above parameters has good chemical activity and high specific resistance, which can more effectively avoid the carbon deficiency phenomenon in the smelting process and improve the material recovery rate and quality stability.

[0022] Furthermore, the rare earth oxide pellets are prepared by the following method: take the following raw materials in mass percentage: 70%-80% rare earth oxide, 10%-15% second carbonaceous reducing agent, 6%-8% binder and 4%-8% water; mix the above raw materials evenly, press them into balls, and then dry them to obtain the product.

[0023] First, in the present invention, the rare earth oxides used are in powder form, which come from dust removal ash. If they are directly put into the furnace, the oxides will be sucked into the dust removal ash due to the strong dust removal suction force, which will increase the unit material consumption. At the same time, too much powdered raw material in the charge will cause the furnace to become sticky, causing the charge surface to harden and reducing the permeability of the charge surface. The present invention presses the rare earth oxides into balls according to a predetermined ratio with coke powder and a binder, which will increase the overall material particle size, promote the permeability of the material layer structure, and improve the reaction efficiency in the furnace; it can also ensure that the charge entering the furnace is in block form, thereby improving the material utilization rate.

[0024] Secondly, the addition of the second carbonaceous reducing agent in the present invention can increase the reduction rate of rare earth oxides in the smelting process of the electric arc furnace and improve the material reduction efficiency. The particle size of the second carbonaceous reducing agent is larger than the particle size of the rare earth oxide. When the binder is added, it is easier to demold after being processed by a ball press. It has a certain mechanical strength and is not easy to break at high temperature, making it more suitable for furnace production.

[0025] Thirdly, the present invention presses the rare earth oxide into a spherical shape, which can increase the overall material particle size, promote the permeability of the material layer structure, and improve the reaction efficiency in the furnace; secondly, it can ensure that the charge entering the furnace is in block shape, thereby improving the material utilization rate.

[0026] Furthermore, the rare earth oxide briquette is prepared by the following method: take the following raw materials in mass percentage: 75% rare earth oxide, 12% second carbonaceous reducing agent, 7% binder and 6% water; after mixing the above raw materials evenly, press them into spheres with a particle size of 80mm-130mm, and then dry them at 150℃-200℃ for 20min to obtain; wherein, the rare earth oxide is powdered lanthanum cerium oxide, the total amount of rare earth oxide is>95%, and the particle size is <0.075mm; the second carbonaceous reducing agent is any one or a mixture of semi-coke, metallurgical coke and petroleum coke; the binder is corn gum or corn starch. The above are the best ratios and preparation parameters. The prepared rare earth oxide briquette has a particle size of 80mm-130mm and a compressive strength greater than 1200N. The above rare earth oxide briquette can ensure that the charge is in block shape and has high compressive strength, which is more conducive to improving the reaction efficiency of the subsequent preparation of deoxidizer for steelmaking and improving the comprehensive utilization rate of materials.

[0027] Compared with rare earth concentrate and rare earth-rich cerium slag, the rare earth content in the rare earth oxide of the present invention is higher, which effectively reduces the content of trace elements in the subsequent preparation of deoxidizer for steelmaking, improves the quality of the deoxidizer for steelmaking and the element recovery rate, and helps to stabilize production.

[0028] Compared with other adhesives, the present invention uses corn gum or corn starch, which has good bonding effect, relatively low cost and is easy to obtain.

[0029] Furthermore, the mass percentage of fixed carbon in the second carbonaceous reducing agent is greater than 80%, the particle size is 1mm-3mm, and the mass percentage of ash is less than 7%. The particle size of the second carbonaceous reducing agent is larger than the particle size of the rare earth oxide, and it is easier to demold after being processed by a briquetting machine when a binder is added, and it has a certain mechanical strength, is not easy to break at high temperature, and is more suitable for furnace production.

[0030] It should be noted that the silica, the first carbonaceous reducing agent, the second carbonaceous reducing agent, steel scraps and the binder involved in the present invention can all be purchased commercially.

[0031] A second object of the present invention is to provide a method for preparing the above-mentioned deoxidizer for steelmaking.

[0032] The technical solution of the present invention to solve the above technical problem is as follows: The preparation method of the above steelmaking deoxidizer comprises the following steps:

[0033] Step 1: Preparation of rare earth oxide pellets

[0034] Weigh the following raw materials in mass percentage respectively: 70%-80% of rare earth oxide, 10%-15% of the second carbonaceous reducing agent, 6%-8% of the binder and 4%-8% of water; mix the above raw materials evenly, press them into balls, and then dry them to obtain rare earth oxide balls;

[0035] Step 2: Smelting

[0036] Take silica, the rare earth oxide pellets of step 1, the first carbonaceous reducing agent and steel scraps, sieve them respectively until they meet the requirements, then take 80-85 parts by mass of silica, 25-35 parts by mass of the rare earth oxide pellets of step 1, 49-54 parts by mass of the first carbonaceous reducing agent and 8-12 parts by mass of steel scraps respectively, add them to the ore-forming furnace according to the smelting process requirements, smelt for 2h-2.5h, and add 1 part by mass of the first carbonaceous reducing agent fine particles obtained by screening to the iron chute and the iron ladle when tapping iron, and then cast, cool and demold to obtain the finished deoxidizer for steelmaking.

[0037] In step 2 of the present invention, a slightly carbon-deficient operation method is adopted for smelting. In the early stage, refined materials are selected to enter the furnace. It is necessary to ensure that the total amount of fixed carbon of the carbonaceous reducing agent entering the furnace is greater than 80%, and the actual amount of reducing agent added is 1.5%-2.5% lower than the theoretical amount. The purpose is to appropriately adjust the resistance of the charge, reasonably control the current, strengthen the electrode displacement and insertion, increase the electrode pressure release, and promote the expansion of the crucible area. In addition, the slightly carbon-deficient operation can also inhibit the reduction of elements with higher reduction temperatures than silicon (Al, Mg, etc.). When the root of the electrode is prone to ignition, keep the material surface wide and flat, and pierce the eye frequently for ventilation. In principle, the deeper the collapsed material around the electrode when each electrode is unloaded, the larger the crucible, and the better the furnace condition.

[0038] In step 2 of the present invention, the fine particles of the first carbonaceous reducing agent obtained by screening during the batching process are added to the tapping chute and the ladle during the tapping process, which helps to promote the fluidity and heat preservation of the molten iron, prevent slag accumulation in the chute, hinder the flow of molten iron, maintain the safety of the furnace eye, and the coke powder in the ladle is bonded to the floating slag on the liquid surface to form an insulation layer, while isolating the air, preventing the secondary oxidation of rare earth elements, and promoting the slag sieving during casting. During casting, the intermediate fixed-point casting is adopted, and the ingot mold trolley moves left and right for casting, which inhibits alloy segregation and improves the quality of the alloy.

[0039] In step 2 of the present invention, the first carbonaceous reducing agent fine particles have a particle size of ≤6 mm.

[0040] Based on the above technical solution, the present invention can also be improved as follows.

[0041] Further, in step 2, the rated capacity of the ore-fired furnace is 33 MVA, the pole center circle diameter is 3560 mm ± 150 mm, the electrode diameter is 1360 mm, the furnace diameter is 8400 mm, the commonly used primary voltage is 35 KV-36 KV, the secondary voltage is 225 V-235 V, and the power factor is 0.7-0.8.

[0042] At present, the equipment used in the industry to produce deoxidizers for steelmaking using the carbon thermal method is mostly 12.5MVA and below rated capacity of submerged arc furnaces. This type of furnace has the disadvantages of large manual labor, simple equipment, inaccurate batching structure control, and small output during operation. The present invention uses a 33MVA submerged arc furnace to produce deoxidizers for steelmaking, which is the first in the industry, responding to the development trend of large-scale submerged arc furnaces in the alloy industry, and filling the gap in the production of rare earth ferrosilicon alloys using large submerged arc furnaces. The furnace transformer of the 33MVA submerged arc furnace is composed of 3 11MVA single-phase transformers, arranged in a triangle, equipped with energy-saving equipment such as short network and low-voltage compensation, and has certain advantages in improving electrical efficiency by controlling the cross-sectional area of ​​the power supply equipment and shortening the power supply distance. The secondary side voltage is divided into 35 levels, and the on-load voltage regulation method is adopted, which can effectively select a reasonable secondary voltage and power factor, promote the production of submerged arc furnaces, and reduce the unit consumption of smelting.

[0043] The production materials of deoxidizer for steelmaking are composed of a variety of raw materials, and the density, melting point and reaction temperature of the materials are different. The feeding system of the 33MVA submerged arc furnace is equipped with multiple silos, and rational feeding is adopted according to the density of various materials to ensure uniform mixing of materials. The key furnace parameters of the 33MVA submerged arc furnace, such as the pole circle diameter, electrode diameter, furnace depth, and furnace diameter, can provide sufficient reaction space for the reduction reaction of the materials in the furnace. In addition, the rational use and optimization of electric heat conversion can promote the further increase of alloy production. In addition, the 33MVA submerged arc furnace has a high level of automation, which reduces manual work, improves equipment accuracy, and is equipped with waste heat power generation and flue gas purification systems to save energy while protecting the environment.

[0044] Furthermore, in step 2, the daily pressure release of the smelting is 500mm-600mm, the material surface is 200mm-350mm above the furnace mouth, the furnace mouth temperature is <500°C, and the furnace charge simmering time is 25min-35min.

[0045] Slightly carbon-deficient operation can inhibit the reduction of elements (Al, Mg, etc.) with higher reduction temperatures than silicon, stabilize furnace conditions, improve alloy quality, and reduce material and smelting unit consumption. At the same time, choose a reasonable smelting time and iron-out system to increase the furnace temperature. Keep the material surface 200mm-350mm above the furnace mouth to facilitate deep insertion of the electrode. The piercing fire must be controlled well, and the furnace mouth temperature must be controlled below 500℃. Use a feeder to add materials, and the furnace charge simmering time is guaranteed to be 25min-35min.

[0046] The beneficial effects of the preparation method of the steelmaking deoxidizer of the present invention are:

[0047] 1. The preparation method of the present invention is simple, has advanced technology, low cost, high product quality, broad market prospects, and is suitable for large-scale promotion and application.

[0048] 2. The present invention adopts a slightly carbon-deficient operation method for smelting, appropriately adjusts the resistance of the charge, reasonably controls the current, strengthens the electrode displacement and insertion, increases the electrode pressure release, and promotes the expansion of the crucible area. In addition, the slightly carbon-deficient operation can also inhibit the reduction of elements (Al, Mg, etc.) with a higher reduction temperature than silicon.

[0049] 3. The present invention adds the first carbonaceous reducing agent fine particles obtained by screening during the batching process to the tapping chute and the iron ladle during iron tapping, which helps to promote the fluidity and heat preservation of the molten iron, prevent slag accumulation in the chute, hinder the flow of molten iron, and maintain the safety of the furnace eye. The coke powder in the ladle adheres to the floating slag on the liquid surface to form an insulation layer, while isolating the air, preventing the secondary oxidation of rare earth elements, and promoting slag sieving during casting.

[0050] The third object of the present invention is to provide the application of the above-mentioned deoxidizer for steelmaking.

[0051] The technical solution of the present invention to solve the above technical problem is as follows: the above steelmaking deoxidizer is used as a deoxidizer and / or inclusion refiner.

[0052] The steelmaking deoxidizer of the present invention can be used as a deoxidizer in the steelmaking refining and deoxidation process, and can reduce the amount of deoxidizer used and improve the deoxidation rate compared with aluminum-iron deoxidizers; secondly, it can be used as a refiner for steel inclusions and has a broad application market. DETAILED DESCRIPTION

[0053] The principles and features of the present invention are described below in conjunction with specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0054] Example 1

[0055] The deoxidizer for steelmaking in this embodiment is made of the following raw materials: 800kg of silica, 250kg of rare earth oxide briquette, 500kg of metallurgical coke and 80kg of steel scraps. Among them, the mass percentage of SiO2 in the silica is greater than 98.5%, the mass percentage of Al2O3 is less than 0.8%, the particle size is 60mm-150mm, and the explosion resistance is 700℃-1000℃. The mass percentage of total iron in the steel scraps is >95%, the mass percentage of phosphorus is <0.03%, and the curling length is <20mm; the mass percentage of fixed carbon in the metallurgical coke is >80%, and the particle size of 3mm-5mm accounts for >85%.

[0056] The rare earth oxide pellets are prepared by the following method: taking the following raw materials by mass: 720 kg of rare earth oxide, 120 kg of metallurgical coke, 80 kg of corn gum and 80 kg of water; mixing the above raw materials evenly, pressing them into balls with a particle size of 80 mm-130 mm, and then drying them at 180° C. for 20 minutes to obtain the pellets; wherein the rare earth oxide is powdered lanthanum-cerium oxide, the total amount of rare earth oxide is >95%, and the particle size is <0.075 mm; the mass percentage of fixed carbon in the metallurgical coke is >80%, the particle size is 1 mm-3 mm, and the mass percentage of ash is <7%.

[0057] The preparation method of the above-mentioned deoxidizer for steelmaking comprises the following steps:

[0058] Step 1: Preparation of rare earth oxide pellets

[0059] The following raw materials are weighed respectively: 720kg of rare earth oxide, 120kg of metallurgical coke, 80kg of corn gum and 80kg of water; the raw materials are mixed evenly, pressed into spheres with a particle size of 80mm-130mm, and then dried at 150°C for 20min to obtain the product; wherein the rare earth oxide is powdered lanthanum-cerium oxide, the total amount of the rare earth oxide is greater than 95%, and the particle size is less than 0.075mm.

[0060] Step 2: Smelting

[0061] Take silica, rare earth oxide briquette of step 1, semi-coke and steel scraps, sieve them to meet the requirements, then take 800kg silica, 250kg rare earth oxide briquette of step 1, 490kg metallurgical coke and 80kg steel scraps, add them to the ore-smelting furnace according to the smelting process requirements, smelt for 2h-2.5h, add 10kg of the metallurgical coke obtained by sieving to the iron chute and the ladle when tapping, then cast, cool and demould to obtain the finished deoxidizer for steelmaking.

[0062] Wherein, in step 2, the rated capacity of the ore-fired furnace is 33MVA, the pole circle diameter is 3560mm±150mm, the electrode diameter is 1360mm, the furnace diameter is 8400mm, the commonly used primary voltage is 35KV-36KV, the secondary voltage is 225V-235V, and the power factor is 0.7-0.8. The daily pressure release of the smelting is 500mm-600mm, the material surface is 200mm-350mm above the furnace mouth, the furnace mouth temperature is <500℃, and the furnace charge simmering time is 25min-35min.

[0063] The above steelmaking deoxidizer is used as a deoxidizer and / or inclusion refiner.

[0064] Example 2

[0065] The deoxidizer for steelmaking in this embodiment is made of the following raw materials: 830kg silica, 300kg rare earth oxide briquette, 520kg semi-coke and 10kg steel scraps. Among them, the mass percentage of SiO2 in the silica is greater than 98.5%, the mass percentage of Al2O3 is less than 0.8%, the particle size is 60mm-150mm, and the explosion resistance is 700℃-1000℃. The mass percentage of total iron in the steel scraps is >95%, the mass percentage of phosphorus is <0.03%, and the curling length is <20mm; the mass percentage of fixed carbon in the semi-coke is >84%, the mass percentage of ash is <7%, the mass percentage of volatile matter is <9%, the mass percentage of average moisture is <15%, the powder rate is <1.5%, and the particle size of 6mm-18mm accounts for >85%.

[0066] The rare earth oxide pellets are prepared by the following method: taking the following raw materials by mass: 750 kg of rare earth oxide, 120 kg of metallurgical coke, 70 kg of corn starch and 60 kg of water; mixing the above raw materials evenly, pressing them into balls with a particle size of 80 mm-130 mm, and then drying them at 180° C. for 20 minutes to obtain the pellets; wherein the rare earth oxide is powdered lanthanum cerium oxide, the total amount of rare earth oxide is >95%, and the particle size is <0.075 mm; the mass percentage of fixed carbon in the metallurgical coke is >80%, the particle size is 1 mm-3 mm, and the mass percentage of ash is <7%.

[0067] The preparation method of the above-mentioned deoxidizer for steelmaking comprises the following steps:

[0068] Step 1: Preparation of rare earth oxide pellets

[0069] The following raw materials are weighed respectively: 750 kg of rare earth oxide, 120 kg of metallurgical coke, 70 kg of corn starch and 60 kg of water; the raw materials are mixed evenly, pressed into spheres with a particle size of 80 mm-130 mm, and then dried at 180° C. for 20 min to obtain the product; wherein the rare earth oxide is powdered lanthanum-cerium oxide, the total amount of the rare earth oxide is greater than 95%, and the particle size is less than 0.075 mm.

[0070] Step 2: Smelting

[0071] Take silica, rare earth oxide briquette of step 1, semi-coke and steel scraps, sieve them to meet the requirements, then take 830kg silica, 300kg rare earth oxide briquette of step 1, 510kg semi-coke and 100kg steel scraps, add them to the ore-smelting furnace according to the smelting process requirements. Smelt for 2h-2.5h, add 10kg of the semi-coke obtained by sieving to the iron chute and the ladle when tapping, then cast, cool and demould to obtain the finished deoxidizer for steelmaking.

[0072] Wherein, in step 2, the rated capacity of the ore-fired furnace is 33MVA, the pole circle diameter is 3560mm±150mm, the electrode diameter is 1360mm, the furnace diameter is 8400mm, the commonly used primary voltage is 35KV-36KV, the secondary voltage is 225V-235V, and the power factor is 0.7-0.8. The daily pressure release of the smelting is 500mm-600mm, the material surface is 200mm-350mm above the furnace mouth, the furnace mouth temperature is <500℃, and the furnace charge simmering time is 25min-35min.

[0073] The above steelmaking deoxidizer is used as a deoxidizer and / or inclusion refiner.

[0074] Example 3

[0075] The deoxidizer for steelmaking in this embodiment is made of the following raw materials: 850kg silica, 350kg rare earth oxide pellets, 550kg blue coke and 120kg steel scraps. Among them, the mass percentage of SiO2 in the silica is greater than 98.5%, the mass percentage of Al2O3 is less than 0.8%, the particle size is 60mm-150mm, and the explosion resistance is 700℃-1000℃. The mass percentage of total iron in the steel scraps is >95%, the mass percentage of phosphorus is <0.03%, and the curling length is <20mm; the mass percentage of fixed carbon in the petroleum coke is >84%, the powder rate is <1%, and the particle size of 6mm-18mm accounts for >80%.

[0076] The rare earth oxide pellets are prepared by the following method: taking the following raw materials by mass: 750kg of rare earth oxide, 120kg of semi-coke, 70kg of corn starch and 60kg of water; after evenly mixing the above raw materials, pressing them into spheres with a particle size of 80mm-130mm, and then drying them at 180°C for 20min to obtain the pellets; wherein the rare earth oxide is powdered lanthanum-cerium oxide, the total amount of rare earth oxide is >95%, and the particle size is <0.075mm; the mass percentage of fixed carbon in the semi-coke is >80%, the particle size is 1mm-3mm, and the mass percentage of ash is <7%.

[0077] The preparation method of the above-mentioned deoxidizer for steelmaking comprises the following steps:

[0078] Step 1: Preparation of rare earth oxide pellets

[0079] The following raw materials are weighed respectively: 750kg of rare earth oxide, 120kg of semi-coke, 70kg of corn starch and 60kg of water; after mixing the above raw materials evenly, press them into spheres with a particle size of 80mm-130mm, and then dry them at 180°C for 20min to obtain; wherein the rare earth oxide is powdered lanthanum-cerium oxide, the total amount of rare earth oxide is>95%, and the particle size is <0.075mm.

[0080] Step 2: Smelting

[0081] Take silica, rare earth oxide briquette of step 1, semi-coke and steel scraps, sieve them to meet the requirements, then take 840kg silica, 350kg rare earth oxide briquette of step 1, 540kg petroleum coke and 120kg steel scraps, add them to the ore-smelting furnace according to the smelting process requirements. Smelt for 2h-2.5h, add 10kg of the sieved petroleum coke to the iron chute and the ladle when tapping, then cast, cool and demould to obtain the finished deoxidizer for steelmaking.

[0082] Wherein, in step 2, the rated capacity of the ore-fired furnace is 33MVA, the pole circle diameter is 3560mm±150mm, the electrode diameter is 1360mm, the furnace diameter is 8400mm, the commonly used primary voltage is 35KV-36KV, the secondary voltage is 225V-235V, and the power factor is 0.7-0.8. The daily pressure release of the smelting is 500mm-600mm, the material surface is 200mm-350mm above the furnace mouth, the furnace mouth temperature is <500℃, and the furnace charge simmering time is 25min-35min.

[0083] The above steelmaking deoxidizer is used as a deoxidizer and / or inclusion refiner.

[0084] Experimental Example 1: Composition Analysis of Deoxidizer for Steelmaking

[0085] The deoxidizers for steelmaking prepared in Example 2 were respectively taken for component detection. The average results of the component detection are shown in Table 1.

[0086] Table 1

[0087] Ca(%) Si(%) Al(％) Re(La+Ce)(%) La(%) Ce(%) 0.48 44.76 0.84 33.05 11.29 21.76

[0088] It can be seen from Table 1 that the rare earth content in the steelmaking deoxidizer of the present invention is 33.05%. According to calculation, the smelting unit consumption of Example 2 is 7845 kwh / t.

[0089] Experimental Example 2: Deoxygenation Rate Test

[0090] In the prior art, aluminum-iron deoxidizers are mainly used. A deoxidation rate test was conducted using a deoxidizer for steelmaking in the prior art and the deoxidizer for steelmaking in Example 2 of the present invention. The test scheme is shown in Table 2.

[0091] Table 2

[0092]

[0093] The deoxidation rates are shown in Table 3.

[0094] Table 3

[0095] Material Name Amount (kg) Deoxidation rate (%) Deoxidizer for steelmaking in the prior art 150 87％ Deoxidizer for steelmaking of Example 2 100 94％ Deoxidizer for steelmaking of Example 2 150 95％

[0096] It can be seen from Table 3 that, under the same addition amount (150 kg), the deoxidation rate of the steelmaking deoxidizer of Example 2 is 8% higher than that of the steelmaking deoxidizer of the prior art. When the addition amount of the steelmaking deoxidizer of Example 2 (100 kg) is less than that of the steelmaking deoxidizer of the prior art (150 kg), the deoxidation rate is increased by 7%. It can be seen that the steelmaking deoxidizer of the present invention has an excellent deoxidation rate.

[0097] Experimental Example 3: Inclusion Analysis

[0098] The furnace in which the deoxidizer for steelmaking of Example 2 was added was used as an experimental furnace, and the furnace in which the deoxidizer for steelmaking of Example 2 was not added was used as a blank furnace, and inclusion analysis was performed, as shown in Table 4.

[0099] Table 4

[0100]

[0101] As shown in Table 4, the number and size of inclusions in the experimental heats are comparable to those in the blank heats, and there is an overall positive trend of increasing small inclusions and decreasing large inclusions. Among them, the large inclusions in the later process decrease, and the small inclusions increase, indicating that the steelmaking deoxidizer of the present invention has the effect of miniaturizing the deoxidized product, that is, the effect of miniaturizing inclusions, and plays a promoting role in improving mechanical properties, corrosion resistance, hot working properties, plasticity and toughness.

[0102] Comparative Example

[0103] The difference from Example 2 is that the rare earth ore of the prior art is used as the raw material to prepare the deoxidizer for steelmaking, and the rest are the same. Fluorocarbon naesite concentrate is light yellow to brown, with a hardness of 4.0-4.5 and a density of 4.72-5.12 g / cm 3 . The rare earth oxide content is 53.4%, and the particle size is uniform. Rare earth ore must be specially pelletized before entering the furnace.

[0104] The deoxidizer for steelmaking prepared in this comparative example was taken for component detection, and the average results of the component detection are shown in Table 5.

[0105] Table 5

[0106] Ca(%) Si(%) Al(％) Re(La+Ce)(%) 0.6 52.1 1.14 31.5

[0107] As shown in Table 5, the rare earth content in the steel-making deoxidizer of the comparative example is 31.5%, which is lower than the rare earth content of 33.05% in the steel-making deoxidizer of Example 2. At the same time, the aluminum content and calcium content of the steel-making deoxidizer of the comparative example are 1.14% and 0.75% respectively, which are higher than the aluminum content (0.84%) and calcium content (0.6%) in the steel-making deoxidizer of Example 2. The rare earth element recovery rate in the steel-making deoxidizer of Example 2 is higher than the rare earth element recovery rate of the comparative example and contains less impurity elements than the comparative example. The higher the aluminum content, the easier the steel-making deoxidizer is to pulverize. Therefore, the product quality of the steel-making deoxidizer of Example 2 is better than that of the comparative example. In addition, it is calculated that the smelting unit consumption of the comparative example is 8907kwh / t, which is also higher than the smelting unit consumption of 7845kwh / t of Example 2.

[0108] In summary, the steelmaking deoxidizer of the present invention selects rare earth oxide briquette as one of the raw materials, expands the utilization of rare earth resources, improves the utilization rate of rare earth resources, expands the selectivity of the steelmaking deoxidizer, solves the problems of limited utilization of rare earth resources and waste of resources, and has the advantages of good product quality, low material consumption, and low smelting unit consumption. Therefore, the steelmaking deoxidizer of the present invention can be used as a deoxidizer in the steelmaking refining and deoxidation process, and can reduce the amount of deoxidizer used and improve the deoxidation rate compared with aluminum-iron deoxidizers; secondly, it can be used as a refiner for steel inclusions, and has a broad application market.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A deoxidizer for steelmaking, characterized in that: The invention is prepared from the following raw materials in parts by weight: 80-85 parts of silica, 25-35 parts of rare earth oxide pellets, 50-55 parts of a first carbonaceous reducing agent and 8-12 parts of steel scraps.

2. The deoxidizer for steelmaking according to claim 1, characterized in that The mass percentage of SiO2 in the silica is greater than 98.5%, the mass percentage of Al2O3 is less than 0.8%, the particle size is 60mm-150mm, and the explosion resistance is 700℃-1000℃; the mass percentage of total iron in the steel scraps is >95%, the mass percentage of phosphorus is <0.03%, and the curling length is <20mm.

3. The deoxidizer for steelmaking according to claim 1, characterized in that The first carbonaceous reducing agent is any one of semi-coke, metallurgical coke and petroleum coke, or a mixture of several of them.

4. The deoxidizer for steelmaking according to claim 1, characterized in that The rare earth oxide pellets are prepared by the following method: taking the following raw materials in mass percentage: 70%-80% rare earth oxide, 10%-15% second carbonaceous reducing agent, 6%-8% binder and 4%-8% water; mixing the above raw materials evenly, pressing them into balls, and drying them to obtain the product.

5. The deoxidizer for steelmaking according to claim 4, characterized in that The rare earth oxide pellets are prepared by the following method: taking the following raw materials in mass percentage: 75% rare earth oxide, 12% second carbonaceous reducing agent, 7% binder and 6% water; after mixing the above raw materials evenly, pressing them into spheres with a particle size of 80mm-130mm, and then drying them at 150℃-200℃ for 20min to obtain the rare earth oxide pellets; wherein the rare earth oxide is powdered lanthanum cerium oxide, the total amount of rare earth oxide is >95%, and the particle size is <0.075mm; the second carbonaceous reducing agent is any one of semi-coke, metallurgical coke and petroleum coke, or a mixture of several thereof; the binder is corn gum or corn starch.

6. The deoxidizer for steelmaking according to claim 1, characterized in that: The first carbonaceous reducing agent is any one of semi-coke, metallurgical coke and petroleum coke, or a mixture of several of them.

7. A method for preparing a deoxidizer for steelmaking, characterized in that: The steps include: Step 1: Preparation of rare earth oxide pellets Weigh the following raw materials in mass percentage respectively: 70%-80% of rare earth oxide, 10%-15% of the second carbonaceous reducing agent, 6%-8% of the binder and 4%-8% of water; mix the above raw materials evenly, press them into balls, and then dry them to obtain rare earth oxide balls; Step 2: Smelting Take silica, the rare earth oxide pellets of step 1, the first carbonaceous reducing agent and steel scraps, sieve them respectively until they meet the requirements, then take 80-85 parts by mass of silica, 25-35 parts by mass of the rare earth oxide pellets of step 1, 49-54 parts by mass of the first carbonaceous reducing agent and 8-12 parts by mass of steel scraps respectively, add them to the ore-forming furnace according to the smelting process requirements, smelt for 2h-2.5h, and add 1 part by mass of the first carbonaceous reducing agent fine particles obtained by screening to the iron chute and the iron ladle when tapping iron, and then cast, cool and demold to obtain the finished deoxidizer for steelmaking.

8. The method for preparing a deoxidizer for steelmaking according to claim 7, characterized in that: In step 2, the rated capacity of the ore-fired furnace is 33 MVA, the pole center circle diameter is 3560 mm ± 150 mm, the electrode diameter is 1360 mm, the furnace diameter is 8400 mm, the commonly used primary voltage is 35 KV-36 KV, the secondary voltage is 225 V-235 V, and the power factor is 0.7-0.

8.

9. The method for preparing a deoxidizer for steelmaking according to claim 7, characterized in that: In step 2, the daily pressure release of the smelting is 500mm-600mm, the material surface is 200mm-350mm above the furnace mouth, the furnace mouth temperature is <500°C, and the furnace charge simmering time is 25min-35min.

10. Use of the deoxidizer for steelmaking according to any one of claims 1 to 6 as a deoxidizer and / or inclusion refiner.

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