CN118256678A

CN118256678A - Microorganism-treated LF refining slag and preparation method and application thereof

Info

Publication number: CN118256678A
Application number: CN202410296492.7A
Authority: CN
Inventors: 吴昊天; 肖业明; 吴光亮; 李骞
Original assignee: CHANGSHA DONGXIN ENVIRONMENTAL PROTECTION MATERIAL CO LTD; Central South University
Current assignee: CHANGSHA DONGXIN ENVIRONMENTAL PROTECTION MATERIAL CO LTD; Central South University
Filing date: 2024-03-15
Publication date: 2024-06-28

Abstract

The invention discloses LF refining slag treated by microorganisms and a preparation method and application thereof. The LF furnace refining slag provided by the invention is prepared by mixing limestone, bauxite, dolomite, potassium feldspar, carbon-containing minerals and the like in proportion, crushing and grinding, adding the ground powder, microorganism bacteria, an organic adhesive, powdery metal aluminum, silicon carbide powder and carbon powder in proportion, uniformly mixing, extruding, forming and curing. The refining slag prepared by the method is used in the secondary refining process of molten steel, especially in LF furnace refining, the sulfur content in the molten steel can be reduced to below 0.0003%, and the desulfurization rate is more than 90%; the total content of impurity elements in the steel [ O ] + [ S ] + [ H ] + [ N ] + [ P ] is less than or equal to 0.0050%; class D and class B inclusions are less than or equal to 0.5 level; the slag is also used as a slag former in the slag washing and vacuum treatment processes in the tapping process, and has wide application prospect.

Description

Microorganism-treated LF refining slag and preparation method and application thereof

Technical Field

The invention relates to LF refining slag, in particular to LF refining slag treated by microorganisms and a preparation method and application thereof, and belongs to the technical field of biological metallurgy.

Background

Along with the continuous promotion of industrial modernization, the quality requirements of steel materials are higher and higher, especially the market demand of clean steel is higher and higher, and the requirements of industrial steel materials for engineering, aerospace, machinery, military industry, electronics and the like on the cleanliness of the steel materials are higher and higher, for example, bearing steel requires that the oxygen content in the steel is less than 0.0010 percent and the sulfur content is less than 0.0010 percent; the spring steel requires the oxygen content in the steel to be less than 0.0015 percent and the sulfur content to be less than 0.0010 percent; oil and gas pipe steel, steel for offshore oil production platforms, ship plates, aviation steel and the like all require that the sulfur content in the steel is less than 0.0010 percent, and some high-pressure containers even require that the sulfur content is less than 0.0005 weight percent; automobile panels, silicon steel, etc. require oxygen levels of less than 0.0015%, sulfur less than 0.0010%, and even lower; in addition to harmful elements such as [ O ], [ S ], [ N ], the control of the number, size and morphology of inclusions such as oxides, sulfides and nitrides formed by the elements is also an important factor influencing the quality improvement of steel; the damage of inclusions to steel is mainly related to the number and size of inclusions. The steel types are different and limited by smelting cost, the requirements on inclusions are also different, and the total oxygen is less than or equal to 50ppm and the size of the inclusions is less than or equal to 50um for common steel. IF steel, silicon steel, cord steel, pipeline steel and the like, the total oxygen content and inclusion index requirements are strict, for example, the steel cord requires that the Al ₂O₃ inclusion size is less than or equal to 10-15um, and the requirement of 20-ten thousand meters of no broken ends in the wire drawing process can be met. Therefore, the key to improving the quality of steel products and producing clean steel is to remove harmful elements in the steel and control and remove impurities formed in the steel. Most of the inclusions in the molten steel are removed by floating the inclusions in the molten steel into the top slag through buoyancy and forming a complex with smaller activity with components in the top slag. The key to remove inclusions in steel is a secondary refining process technology of molten steel, which takes slagging and improvement of molten pool dynamics conditions as main means. On one hand, a proper slag system is selected, meanwhile, the contact area of slag steel is increased, the rapid reaction of harmful elements in the steel and components in slag is ensured to generate stable oxides, sulfides or nitrides and the like, and meanwhile, low-melting-point compounds are formed; on the other hand, the harmful element in the steel is promoted to generate products which float to the slag layer rapidly, and compounds or complexes with smaller activity are formed with corresponding components in the slag. The secondary refining technology comprises core technologies such as slag stopping tapping, synthetic slag washing, slag modification, LF furnace white slag refining, feeding and steel medium inclusion shape control, molten steel temperature and component accurate control, vacuum decarburization, degassing, inclusion floating separation and the like, wherein LF furnace external refining has become the most effective and widely applied technology for modern metallurgy. Proper refining slag systems are selected according to metallurgical requirements of different steel grades, harmful elements in steel and components in slag are promoted to furthest react positively to form low-melting-point compounds, and the compounds float up to slag layers rapidly to adsorb impurities (oxides, sulfides, nitrides and the like), so that the purpose of purifying molten steel is achieved.

The LF ladle refining furnace (LadleFurnace is called LF furnace for short) has the characteristics of simple equipment, low investment, flexible operation and good refining effect since the 70 th century, can remove impurity elements such as inclusion, sulfur, oxygen and the like in molten steel, purify the molten steel, prevent the molten steel from sucking air, reduce heat loss, improve the quality of steel and the like, and has become an indispensable process in the steel production flow. Besides adopting mature secondary refining technologies such as reducing atmosphere submerged arc heating, vacuum degassing, air brick argon blowing stirring and the like, the LF refining furnace also introduces synthetic slag refining technology, and realizes the purposes of desulfurizing, deoxidizing and even denitrifying through a slag making process, thereby effectively adsorbing impurities in steel, controlling the forms of the impurities, forming foam slag submerged arc, improving the thermal efficiency, and reducing refractory erosion and molten steel secondary oxidation. LF refining slag is a clean key raw material for LF process production, and metallurgical workers are constantly researching and developing.

In connection with LF refining slag, the related patents disclosed in the search literature are as follows:

【1】 Application publication No. CN101319267A, composite sphere for refining desulfurization outside furnace and removing fine inclusion and its preparation method. The composite sphere is used for refining desulfurization and fine inclusion removal of various microalloy steel or special steel. The ball core is mainly composed of low-melting-point premelting slag powder, calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate, and the shell is mainly composed of one or two mixtures of calcium oxide and magnesium oxide. The inclusion in the molten steel can be effectively removed, and the sulfur content in the steel can be rapidly reduced to below 0.003%. The ball core is prepared from the following raw materials in percentage by weight: low melting point premelting slag powder: 1-70%; 1-60% of calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate; 0-40% of calcium fluoride; an adhesive: 0-20%. Preferably, a low melting premelted slag powder: 10-50%; 10-45% of calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate; 5-30% of calcium fluoride; an adhesive: 5-15%. The low-melting-point premelting slag powder is prepared from the following components in percentage by weight: caO:10-70%, al ₂O₃：15-50％,SiO₂：0-10％,MgO：0-10％,CaF₂: 0-30%, and its melting point is 1100-1550 ℃; the shell comprises 0-20% of adhesive, wherein the adhesive is any one or more than two of clay, common cement, bentonite and water glass; the steps are as follows: (1) preparing a ball core: mixing: the raw materials of the core part are taken according to the formula ratio, crushed, rolled and ground, the granularity of the raw materials is 1nm-3.5mm, the powder and the adhesive are put into a mixer for fully stirring and mixing, and the mixing time is 1h-3h for standby. And (3) drying, namely fully drying the mixed powder in a dryer, wherein the drying humidity is 80-150 ℃ and the drying time is 2-8 hours. And (3) ball core manufacturing, namely manufacturing the ball core by the dried powder through ball manufacturing equipment, wherein the diameter of the ball core is 1-20mm. (2) preparing a composite sphere: mixing the shell: fully mixing the raw materials required by the shell in a mixer according to a proportion, wherein the activity of calcium oxide and magnesium oxide is 200ml, and the mixing time is 1-3 hours for standby. Compounding: and (3) compounding the prepared ball core and shell raw materials on ball preparing equipment to prepare balls, wherein the size of the prepared compound balls is 5-60mm. And (3) integral drying: and (3) drying the composite spheres prepared by the steps in a dryer at 60-200 ℃ for 10-24 hours to obtain the finished product.

The slag essence also takes CaO, al ₂O₃, mgO and the like as basic slag, and calcium fluoride is taken as a solvent, so that the problems of high slag making material consumption and low efficiency caused by the fact that the product of the reaction between the surface layer of calcium oxide or magnesium oxide and sulfur or Al ₂O₃ is wrapped on the surface of calcium oxide or magnesium oxide particles to prevent further reaction are not solved; the problem that spherical impurities are difficult to remove when high-alkalinity slag is formed under the vacuum condition is not solved; in addition, calcium fluoride is used as a solvent, which causes environmental pollution and the like.

【2】 Application number 201811394005.1, a high performance LF refining slag. Comprises the following components ：CaO：44-51％、SiO₂：8-12％、MgO：6-8％、CaF₂：5-7％、Al₂O₃：22-25％、B₂O₃：3-5％、 binary alkalinity R (CaO/SiO ₂): 5-6, the obtained LF refining slag has proper viscosity and melting point, the precipitation of high-melting-point mineral phases is controlled, the phenomenon of crusting of the refining slag can not occur in the refining process, and the number of inclusions in steel is effectively reduced. CaF ₂/B₂O₃ is controlled between 1.2 and 1.6. Typical example components ：CaO 48％、SiO₂：8.4％、MgO：7％、CaF₂：6.7％、Al₂O₃：24％、B₂O₃：5％. the slag is mainly desulfurized and inclusion removed by means of calcium aluminate and magnesium aluminate, and the problem of low efficiency of calcium oxide and magnesium oxide is still not solved, so that the requirements of ultra-clean steel are difficult to meet; in addition, calcium fluoride and boron oxide are adopted as fluxing agents, so that environmental pollution exists;

The Chinese patent publication No. CN101956045A discloses a refining slag which comprises the following components in parts by weight: 40-55 parts of CaO, 30-45 parts of SiO ₂, 10-25 parts of CaF ₂, less than or equal to 3 parts of Al ₂O₃ and less than or equal to 2 parts of TiO ₂, wherein the contents of Al ₂O₃ and TiO ₂ are not 0, and the value of the alkalinity CaO/SiO ₂ of refining slag is preferably 1.0-1.4, so as to reduce the impurity content in molten steel such as cord steel and improve the cleanliness of the molten steel. However, the fluidity of the refining slag is not ideal because the alkalinity of the refining slag is too low, and the apparent viscosity and the melting point of the slag are both too high because the content of Al ₂O₃ is too low, so that the comprehensive performance is not as good as that required.

The Chinese patent publication No. CN102409140A discloses a refining slag for bearing steel steelmaking process, which comprises the following components in percentage by weight: caO: 45-55%, al ₂O₃：14～20％,SiO₂: 14 to 18 percent of MgO3 to 12 percent, 3 to 8 percent of metallic aluminum, less than or equal to 0.15 percent of TiO ₂, less than or equal to 0.050 percent of P+S and the balance of impurities; the granularity of the refining slag is 10-40mm, and the CaO/SiO ₂ value range is controlled between 2.7 and 3.5. However, the refining slag obtained by the above technical scheme also has the problems of unsatisfactory melting point, viscosity and foamability and easy crusting.

【3】 Application publication number CN109880971, a method for recycling molten state of refining slag in LF furnace. The method comprises the following steps: 1) Slag tapping and charging: after the normal smelting of the LF furnace is finished, charging continuous 2-3 LF refining slag and a small amount of molten steel into a desulfurizing device, wherein the mass ratio of slag to gold is 5-10, and the temperature of slag is 1300-1400 ℃; 2) Vacuumizing: covering a ladle cover of the desulfurization device, firstly discharging gas in the ladle through an air pump, enabling the pressure in the ladle to reach a certain vacuum degree, reducing the partial pressure of SO ₂ gas, and being beneficial to discharging SO ₂ gas out of the furnace; the vacuum degree control range is as follows: 100 Pa-1000 Pa; 3) And (3) desulfurization by an external electric field: inserting a cathode into the slag, wherein the insertion depth of the cathode is 1/2-2/3 of the total depth of the slag, inserting an anode into a steel water layer, applying a stable electric field outside, conducting outside-furnace O ₂ into the slag through a cathode solid electrolyte, reacting with S in the slag to generate SO ₂ gas, and removing outside a ladle; the output voltage U of the externally applied direct current power supply is less than UE, the UE is the decomposition voltage of the cathode solid electrolyte, and the output current I of the externally applied direct current power supply is 1-10A; 4) And (3) collecting SO ₂: the high-temperature SO ₂ gas enters the SO ₂ collecting device through the pipeline, and the SO ₂ gas is dissolved in the seawater in the SO ₂ collecting device to form sulfite or sulfate, SO that the environmental pollution caused by the discharged air of SO ₂ is reduced; the salinity of the seawater is more than 4.5 weight percent, and the alkalinity is more than 3.4 mmol.L-1; 5) And (5) recycling the waste liquid in an LF furnace: stopping power supply after the power supply sulfur in the slag is removed for a period of time, lifting a cathode, opening a ladle cover, and reloading the slag into an LF furnace as premelting slag for desulfurizing molten steel; the power supply desulfurization time isThe initial S mass percent of the slag, (S) t is the S mass percent of the slag at the moment t, K is the desulfurization rate, the unit is 1/min, and K=0.012-0.021.

The patent is a method for refining molten steel in an LF furnace by recycling LF refining slag. The method belongs to cyclic use of slag after LF refining, has higher sulfur content in the slag, and particularly after repeated cyclic use, the sulfur content in the slag, the content of substances such as aluminum oxide and the like reach a saturated state, thereby greatly reducing the desulfurization efficiency and the inclusion adsorption capacity.

【4】 Application number 202110662389.6, a submerged arc refining slag for square billet LF refining and a production process and a production device thereof. The raw materials comprise the following components in percentage by weight: 40-65% of CaCO ₃, 0-20% of MgO, 5-10% of SiO ₂, 0-20% of BaCO ₃, 0-10% of Na ₂CO₃, SiC is 0-15%, caF ₂ is 0-15%. uses carbonic acid substance (CaCO ₃、BaCO₃、Na₂CO₃、MgCO₃) and the like as main raw materials, the carbonic acid substance is decomposed at high temperature after entering molten steel to generate a large amount of CO ₂ bubbles, and the carried SiC, C, caC ₂ and the like react with CO ₂ to generate CO, thereby obtaining a large number of bubbles and realizing the purpose of submerged arc. Preferably, the raw materials comprise the following components in percentage by weight: 50-65% of CaCO ₃, 0-20% of MgO, 5-10% of SiO ₂, 0-20% of BaCO ₃, 0-10% of Na ₂CO₃, 0-15% of SiC and 0-15% of CaF ₂; The CaCO ₃ can be synthetic or natural limestone; the BaCO ₃ may be a waste material which is commercially available or which contains barium; the Na ₂CO₃ is industrial sodium carbonate; the MgO can be any one of magnesia, light burned magnesia, magnesia dolomite or magnesite; the SiC can be any one of industrial smelting grade silicon carbide or waste material containing silicon carbide; the SiO ₂ can be any one of silica, quartz sand or bentonite; the production process of the submerged arc refining slag for square billet LF refining comprises the following steps: step 1: all the raw materials are added into a stirrer according to a proportion for mixing for 5-10min; step 2: putting the materials mixed in the step 1 into a high-pressure ball press to press into spheroidal particles, and sending the semi-finished products with unqualified moisture into drying equipment to be dried, wherein the baking temperature is 200-300 ℃ and the duration is 10-30min; Step 3: and (3) introducing the material pressed into balls in the step (2) into a vibrating screen for screening, wherein the screen plate is 3-40mm, and continuously recycling the material which does not meet the requirements after being cleaned, and leading the spherical material which meets the requirements out through the screen plate for collection.

The invention uses limestone, magnesia, barium carbonate and other raw materials, uses calcium fluoride, silicon oxide and the like as fluxing agents and SiC, C, caC ₂ as reducing agents to form a mechanical mixture, is used for standby after molding, is not substantially different from calcium oxide or magnesia slag, and also uses calcium fluoride, so that the inherent defects of the calcium fluoride are still not solved.

【5】 Application number 202111074984.4, a refining slag for LF refining and a use method thereof. The refining slag comprises the following components in parts by mass: 35 to 45 parts of CaO, 29 to 33 parts of Al ₂O₃, 5 to 7 parts of MgO, 7 to 11 parts of carbonate, 3 to 6 parts of reducing agent and 0.5 to 1 part of CaCl ₂. Preferably, the composition of the components in parts by mass is as follows: 40 parts of CaO, 30 parts of Al ₂O₃, 6 parts of MgO, 7-11 parts of carbonate, 3-6 parts of reducing agent and 0.5-1 part of CaCl ₂. The typical example consists of the following components in parts by mass: 40 parts of CaO, 30 parts of Al ₂O₃, 6 parts of MgO, 9 parts of carbonate, 5 parts of reducing agent and 0.5 to 1 part of CaCl ₂. The carbonate is at least one of calcium carbonate and magnesium carbonate. The carbonate is a composition of calcium carbonate and magnesium carbonate with the mass ratio of 1-2:1-2. The reducing agent is at least one of SiC and CaSi. The reducing agent is a composition of SiC and CaSi with the mass ratio of 1-2:1-2. The method comprises the following steps: step (1): adding refining slag and limestone fragments with mass ratio of 1-2:1-2 into a ladle for smelting before tapping in an electric furnace; step (2): when LF refining is carried out, refining slag accounting for 1-2% of the molten steel mass is added once again. And (3) the mass ratio of the refining slag to the limestone fragments in the step (1) is 1:1.

The essence is also calcium aluminate and magnesium aluminate refining slag, caCl ₂ is used as a fluxing agent, siC and CaSi are used as reducing agents for slagging, and the slag is also a simple mechanical mixture material, so that the inherent defects of calcium oxide or magnesium oxide refining are not solved.

【6】 Application number 202210790996.5, a method for preparing slag agent for converter from LF furnace refining slag. Mixing LF refining slag, iron scale, binder, auxiliary materials and water to obtain a mixture; performing ball pressing molding on the mixture, and drying to obtain a slag agent for the converter; wherein, in the mixture, the mass fractions of the LF furnace refining slag, the iron scale, the binder, the auxiliary materials and the water are respectively as follows: LF furnace refining slag: 20-60 percent of iron oxide scale: 5-25% of adhesive: 0-3% of auxiliary materials: 10-30% of water: 3 to 10 percent. Performing ball pressing molding on the mixture, and drying to obtain a slag agent for the converter; wherein, in the mixture, the mass fractions of the LF furnace refining slag, the iron scale, the binder, the auxiliary materials and the water are respectively as follows: LF furnace refining slag: 20-60 percent of iron oxide scale: 5-25% of adhesive: 0-3% of auxiliary materials: 10-30% of water: 3-10%; the binder is an organic binder or glass water; the auxiliary materials comprise aluminum slag ash and fluorite, and the mass ratio of the aluminum slag ash to the fluorite is 3:5, a step of; in the ball pressing forming, the feeding speed is 200-300 kg/min, the pressure is controlled at 20-40 Mpa, and the rotating speed is controlled at 30-90 r/min; the drying is natural airing or drying at 40-100 ℃; the water content of the slag agent for the converter is less than 0.5%, the strength is more than or equal to 1000N/ball, and the grain diameter is 20-50 mm. The LF furnace refining slag, the iron scale, the binder, the auxiliary materials and the water are mixed to obtain a mixture, and the method specifically comprises the following steps: stirring the LF refining slag, the iron scale, the binder, the auxiliary materials and the water for 5-10 min until the mixture is uniformly mixed, and obtaining the mixture. The scale is produced through a molten steel continuous casting process. The grain sizes of the LF refining slag and the iron scale are smaller than 1mm, and the grain sizes of the auxiliary materials are smaller than 60 meshes. The water is industrial water.

Essentially, the converter flux is prepared by recycling LF refining slag. Similar problems exist as in patent [ 3], which are not solved.

【7】 Application number 201010174311.1, molten steel composite slag lotion based on LF furnace refining slag and a preparation method thereof. Consists of 65-85% of LF furnace refining waste slag, 10-30% of active lime and 5-15% of industrial soda. The LF furnace refining waste residue consists of CaO：50～60％,Al₂O₃：25～35％,SiO₂：4～8％,MgO：4～7％,MnO+FeO：0.5～1.0％,P₂O₅：0.005～0.02％,S：0.01～0.3％; the active lime contains CaO: 90-94%, activity degree 350-380 ml/4N-HCl, granularity: 0.5-3.0 mm; industrial soda Na ₂CO₃: 99.2 percent and the granularity is 0.5 to 1.0mm. The preparation method comprises the steps of processing the LF refining waste residue and the active lime into particles with the granularity of 0.5-3.0 mm, mixing and stirring uniformly according to the proportion, dry-pressing to form, and packing the particles with the granularity of 25-35 mm in a waterproof way. Under the condition that the addition amount is 4-6 Kg/t, the desulfurization rate can reach more than 30%, the total oxygen reduction rate is more than 25%, the hot top calcining qualification rate is improved from 80% to 95%, the recycling utilization of the LF refining waste residues is realized, and the energy conservation and emission reduction of iron and steel enterprises are facilitated.

The essence is that the LF refining slag is regenerated as LF furnace refining slag after adding active lime and industrial soda. Similar to patent [ 3 ], although a certain amount of active lime is added, the problems of patent [ 3 ] are thoroughly solved, and the addition of industrial soda causes pollution to the environment and serious corrosion to ladle slag lines.

Name: converter fluxing agent using LF refined slag as raw material, production method thereof and patent application number: 200710159128.2 discloses a technical scheme for using LF refining slag in a converter steelmaking fluxing agent. Similar problems exist as in patent [ 6 ].

The name is: the invention relates to a molten steel refining agent and its preparing process, wherein the molten steel refining agent is prepared from ladle furnace refining slag, caO and Al ₂O₃ mixture and binder (magnesium chloride solution), wherein the process comprises mixing the constituents homogeneously, granulating, charging into heating furnace, heating at 600-900 deg. C for 1.5-3 h, discharging and natural cooling. The patent is not scientific and reasonable in component composition and preparation method except for refining slag under the condition of not defining the refining slag of the ladle furnace. The patent uses refined waste residue, lime and aluminum oxide, uses magnesium chloride solution as adhesive, and heats for 1.5-3 hours at 600-900 ℃ after granulating, which has the following problems: chloride ions in magnesium chloride can have corrosion effect on equipment and pollute the environment; high-temperature long-time heating has high energy consumption.

【8】 Application number 201210408082.4, a recycling process of LF furnace refining slag. LF slag and iron-containing waste are mixed, and the weight percentages of the LF slag and the iron-containing waste are as follows: 10-30% of LF slag and 70-90% of iron-containing waste, wherein the water content in the mixture is controlled to be 13-18%, the mixture is put into a mixing mill according to a proportion to be mixed and milled for 20-30 minutes, and the mixture is uniformly mixed, pressed and molded by a cold press molding machine and naturally placed for 25-30 days to obtain metallurgical cold-pressed pellets; the invention has the advantages that the pellet prepared by the method has the single-pellet compressive strength of more than 2500N, the free drop test with the height of 1 meter of more than 20 times, completely meets the requirement of the metallurgical cold-pressed pellet strength, and can be applied to a blast furnace or a converter. The LF furnace refining slag is used for pressing high-strength pellets without adding binders, so that not only is one direction provided for recycling metallurgical iron-containing waste materials, but also the production cost of cold-pressed pellets is reduced. The iron-containing waste comprises converter dust or mud, gas ash or mud and blast furnace mine trough ash, wherein the weight percentage of the converter dust or mud, the gas ash or mud and the blast furnace mine trough ash in the iron-containing waste is 20-40%. There are similar drawbacks to patent [ 3 ].

The research is also more in China, and the paper published by any snow et Al in Anhui university of industry university in 2009 and entitled "recycling property of LF furnace refining slag" indicates that w (Al ₂O₃) =20-40% in common LF furnace refining slag is equivalent to low-grade bauxite. The slag phase of the common LF slag is composed of complex phases of calcium aluminum and silicon calcium, has the value of recycling in metallurgical production, belongs to recycling of refining slag, and has similar defects as those of patent [ 3 ].

In recent years, researches on the extensive utilization of common LF slag have been developed gradually, such as recycling the LF slag by utilizing the residual heat in the molten state of the LF slag, but the availability and economy of the slag are weaker, and the utilization method is based on the smelting of the same steel, so that the application range is narrower.

Dai Wen et Al, in 2011, disclose a method for recycling LF furnace steel slag, in which LF furnace steel slag is used as a raw material, after metal iron in slag removal is performed through cooling, crushing, magnetic separation and screening processes, caO-Al ₂O₃-SiO₂ -MgO series LF steel slag containing sulfur is mixed with a proper amount of modifying agents such as lime and the like, and sulfur in the slag is completely oxidized or oxidized to a preset degree in a proper heating furnace at a certain temperature, so that LF furnace premelted refined slag with excellent performance is finally obtained, and the purpose of recycling the steel slag in the steel industry is achieved. The patent has better effect, but the working procedure is more complex.

Jin Aijun et al, published in 2010 under the patent number CN10845536A, state that the molten steel composite slag lotion based on LF refining slag and the preparation method thereof consist of 65-85% of LF refining slag, 10-30% of active lime and 5-15% of process soda. Mixing and stirring uniformly according to a certain proportion, dry-pressing to form, and packing with granularity of 25-35 mm in a waterproof way. The preparation of the slag detergent realizes the resource utilization of the refining waste slag of the LF furnace, and is beneficial to energy conservation and emission reduction of steel enterprises. There are similar drawbacks to the patent [ 3 ].

Patent No. CN1865458a published by any son et al in 2006, "LF furnace steel slag pellet" indicates that the pellets are formed by mixing LF furnace steel slag and an aqueous solution of hydroxymethyl cellulose, the aqueous solution of hydroxymethyl cellulose (weight percent) =88-96%: 4-12%, and the pellet granularity is 30-40 mm. The steel slag balls are used as slag formers for converter steelmaking, can improve and increase the converter slagging speed, can greatly reduce environmental pollution, reduce transportation cost and reduce steelmaking cost, and although the invention also provides a way for recycling LF slag, the invention only plays a role in slagging, but the invention is different from the way in which the LF slag can be recycled, and can also treat iron-containing dust and mud waste, and the LF slag plays a role of a pellet binder. At present, no report about the preparation of the cold bonded pellets by using LF slag as a binder exists.

【9】 Application number 201310433094.7, a production process of an aluminum slag modifier for an LF refining furnace. Taking waste refractory materials, cooling to room temperature, crushing into 5-50mm particles, adding the particles into a Raymond mill, processing into powder with the particle size less than 3mm, mixing with limestone powder with the particle size less than 1mm according to the mass percentage of 1:9, placing the mixture into a forced stirring mixer for stirring and mixing uniformly, discharging, adding the mixture into a steel slag powder ball press or a refractory material ball press for pressing into a ball with the particle size of 20+/-5 mm, and drying at the temperature of 20-50 ℃ for use. In the LF smelting process, 50-150kg of aluminum slag modifier is added for every 100-300kg of lime. Taking the production of an AC-LF refining furnace as an example, the steps are implemented; 1) Selecting waste refractory materials, picking out industrial garbage and iron-containing raw materials, cooling to room temperature, crushing into 5-50mm particles by a jaw crusher, adding the particles into a Raymond mill, and processing into powder with the particle size of less than 3mm for later use; wherein the Al ₂O₃ content of the waste refractory material is 71%; 2) Selecting limestone powder with CaCO ₃ content of 95% and granularity smaller than 1mm for standby; 3) Mixing the materials in the steps 1) and 2) according to the mass percentage of 1:9, and placing the materials in a forced stirring mixer for stirring and mixing uniformly to obtain the material; wherein the time for adding 1 ton of the mixture is controlled within 15min, and the stirring time is 15-20min; 4) And 3) adding the discharged material in the step 3) into a steel slag powder ball press or a refractory material ball press to press into a ball with the diameter of 20+/-5 mm, and drying at the temperature of 20-50 ℃ for use. In the production process, in the LF smelting process, 50-150kg of aluminum slag modifier is added every time 100-300 lime is added. The slag is a single aluminum slag modifier which needs to be used together with active lime, is mainly derived from aluminum-containing waste refractory materials, has higher melting point and slower slag forming rate, needs higher temperature, and can greatly reduce metallurgical effects of slag such as desulfurization and inclusion removal.

The search literature relating to this patent discloses:

(A) Liu Lei, wen Jinbao, yao Jiang in the paper "study of mechanochemical effect of steel slag" published in 2005 by volume 26 and 2, "mechanochemical reaction is a chemical reaction induced by mechanical force. The mechanical force chemical effect producing mechanism, especially the synthesis and decomposition reaction and surface modification, has positive pushing effect on deep mineral processing, chemical industry and material science. Therefore, the method has important theoretical significance and practical value for researching the mechanochemical effect of the steel slag. The expression "is used. The present invention is mainly directed to how to improve the dynamics condition of steel slag, and does not relate to the chemical characteristics of the refining slag.

(B) Yao Jinfu, cui Weiping and Hong Jianguo in the paper published in refractory materials, 2010, volume 44, 3, the paper "regeneration of post-use refractory materials for iron and steel enterprises," one in the middle, "from an economic point of view, the reuse of post-use refractory materials is considered for refractory material products to exert potential values, and then metallurgical auxiliary materials are considered. The expression "and the document also mention the content of" Al ₂O₃ -SiC-C bricks for ladles mainly applied to the production of refined synthetic slag and the production of ladle repair materials ". (3) Tian Shouxin and Chen Zhaoyou in the paper published in refractory materials 1995 (1), "the additives SiC and Si make the study of the oxidation resistance mechanism of the carbonaceous materials" the intermediate is that the additives capable of making the carbonaceous refractory materials oxidation resistant are expressed by gasifying at high temperature in the carbonaceous layer, and then diffusing outwards to the surface through a pore channel to react to generate high-melting-point oxide when encountering strong oxidation atmosphere such as O ₂. According to the above documents, the aluminum-silicon carbide-carbon brick is not a precedent for preparing an aluminum slag modifier at present, and can be applied to the steelmaking process of an LF refining furnace after the aluminum slag modifier is crushed and ground and the potential chemical activity is induced by mechanical force. Similar defects as those of the patent [ 9 ] are not solved, the waste refractory material is recycled, the melting point is high, the melting speed is low, and the refining metallurgical effect is poor.

【10】 Application number 201410152388.7 is a method for full-scale resource utilization of LF furnace refining slag. After the LF refining slag is pretreated, the LF refining slag is divided into high-alumina slag, high-silica slag and silicon aluminum slag, any two of the three refining slag types are mixed according to the mass ratio and then are prepared into slurry with water, and then, main components CaO, mgO and Si ₂O₃、Al₂O₃ in the refining slag are separated and S in the slag is removed through carbonation reaction, naOH alkali dissolution for extracting silicon and aluminum, filtration and aging and crystallization reaction, and the CaO and MgO components are prepared into steelmaking or sintering flux, and the Si ₂O₃、Al₂O₃ component is prepared into 4A zeolite. The invention can realize the full recycling of the refining slag of the LF furnace, has simple process, can realize the waste preparation by waste, and has good economic benefit and environmental benefit. The method comprises the following steps: (1) pretreatment of refining slag: crushing, selecting iron and grinding LF refining slag to below 0.1 mm; (2) classification of refining slag: dividing the pretreated refining slag into high-alumina slag, high-silica slag and silicon-aluminum slag according to the contents of SiO ₂ and Al ₂O₃; (3) Batching and mixing refining slag: weighing two of the high-alumina slag, the high-silicon slag or the silicon-aluminum slag in the step (2) according to the mass ratio, and fully mixing the two refining slag in a mixer; (4) Carbonation of refining slag and absorption treatment of sulfide in slag: mixing the refining slag fully mixed in the step (3) with water according to the solid-to-liquid ratio of 1:1-1:10, uniformly stirring to prepare a refining slag suspension, then introducing CO ₂ gas into the suspension, wherein the volume concentration is 50-100%, the preferential pressure of the CO ₂ gas is 0.2-5 atmospheres, Introducing for 30-90 min, wherein the suspension temperature is preferably 65-90 ℃, S in the slag is released in the form of H ₂ S, and H ₂ S is absorbed by NaOH alkali liquor with the concentration of 1-5%; (5) Alkali dissolution of refining slag to extract Si and Al: adding NaOH into the slag after carbonating in the step (4), wherein the adding amount of the NaOH is 20% -50% of that of the refined steel slag, fully stirring the suspension for 30-120 min at 60-90 ℃, and finally filtering or centrifuging to separate solid phases from liquid phases; (6) preparation of steelmaking or sintering flux: fully washing the solid residue obtained in the step (5) with water until the solid residue is neutral, and drying the solid residue to be used as a steelmaking or sintering flux; the wash water is retained for H ₂ S absorption as described in step (4); (7) 4A zeolite preparation: and (3) using the liquid phase obtained in the step (5) to prepare zeolite, aging the liquid phase at the temperature of 60-70 ℃ for 1-2 h, crystallizing the liquid phase at the temperature of 85-95 ℃ for 4-8 h, and finally filtering and washing to obtain the 4A zeolite. The preferable mass ratio of the high-alumina slag to the high-silica slag is 0.7-1.2 when the high-alumina slag and the high-silica slag are used for proportioning, wherein the chemical composition range of the high-alumina slag is ：35％～60％CaO,2％～15％SiO₂,20％～35％ Al₂O₃,2％～5％MgO,0.5％～3％ Fe₂O₃,0.3～5％SO₃., the chemical composition range of the high-silica slag is 35％～60％CaO,20％～40％SiO₂,1％～5％ Al₂O₃,2％～5％MgO,0.5％～3％ Fe₂O₃,0.3～5％ SO₃., and the chemical composition range of the high-alumina slag is 35％～60％CaO,10％～20％SiO₂,10％～20％ Al₂O₃,2％～10％MgO,0.5％～3％ Fe₂O₃,0.3～5％SO₃.. When the high-alumina slag or the high-silica slag and the silicon-aluminum slag are used for proportioning, the preferable mass ratio of the two slag ranges from 0.05 to 0.3. Similar drawbacks as those of patent [ 3 ] and the like are not overcome.

Chinese patent CN103045778 prepares the ladle slag of the LF furnace into refining slag after natural cooling, magnetic separation, crushing and screening, thereby being beneficial to improving the capability of the ladle slag for adsorbing silicate inclusion, reducing the oxidizing property of molten steel, reducing the consumption of steel and iron materials and alloy of a converter and further improving the quality of molten steel. Similar drawbacks as those of patent [ 3 ] and the like are not overcome.

Chinese patent CN103276201 discloses a cyclic utilization method of carbon steel LF refining slag, which is to press the refining slag into balls, and to replace premelted slag after maintenance. Because S and other impurities contained in the refining slag are easy to cause molten steel pollution, the recycling amount of the refining slag in a metallurgical process is limited. Similar drawbacks as those of patent [3] and the like are not overcome.

Chinese patent CN101717843 uses a roasting method to remove S from refining slag, but this method is costly, and can only remove S from CaS, but cannot remove S dissolved in calcium aluminate and calcium aluminate. Because the metallurgical recycling amount of the refining slag is limited, most of the refining slag is still mainly piled up in iron and steel enterprises or is simply mixed with converter slag for use, and the utilization value of the refining slag is not fully exerted. Similar drawbacks as those of patent [ 3 ] and the like are not overcome.

Chinese patents CN101402460 and CN101259969 disclose methods for extracting Al from refined slag by acid leaching and Na ₂CO₃ alkali dissolution methods, respectively. The acid leaching method has large acid consumption and low aluminum dissolution rate, and the Na ₂CO₃ alkali dissolution method can dissolve Si in the slag, so that the obtained Al ₂O₃ product contains Si impurities, and S in the slag cannot be removed. And these two methods are directed to only high Al refining slag and are not applicable to refining slag having high Si content.

【11】 Application number 201410360962.8, a process method for removing sulfur from LF refining slag and recycling metallurgical, which is applied to the field of recycling waste slag in steelmaking and metallurgical industry. It is characterized in that 10 to 25 percent of Fe ₂O₃ or iron ore is added into slag in the slag discharging process after LF refining is finished, air or oxygen is introduced into the slag after the slag discharging is finished for 10 minutes, sulfur in the slag is discharged in the form of SO ₂, higher desulfurization rate can be obtained, the sulfur content in the slag after desulfurization is lower, and meanwhile, a certain amount of Fe ₂O₃ is added, the desulfurized refining slag is not easy to pulverize, and can be used as a fluxing agent in a converter or molten iron pretreatment process, and finally the purpose of high-efficiency recycling of the LF refining slag is achieved. In the deslagging process after LF refining is finished, after a certain amount of Fe ₂O₃ or iron ore is added into slag, air or oxygen is introduced to desulfurize the slag, and the desulfurized LF refining slag is used as a fluxing agent in the converter or molten iron pretreatment process, so that the LF refining slag can be efficiently recycled in metallurgy, and the method comprises the following steps: (1) In the deslagging process after LF refining is finished, fe ₂O₃ or iron ore is added into the slag, the adding amount is 10% -25% of the slag amount; (2) Introducing air or oxygen into the slag after the slag discharge is finished for 10min to perform oxidative desulfurization treatment on the refined slag; (3) Controlling the ventilation flow to be 50-300 Nm ³/(h.t), and keeping the blowing temperature to be 1200-1400 ℃ in the blowing process for 30 min; (4) After desulfurization, the refining slag is crushed and then added into molten iron pretreatment or a converter to be used as a fluxing agent, so that the LF refining slag can be recycled in metallurgy. The specific operation of the step (1) is as follows: (1) When the LF refining is finished and slag is discharged by 1/5, fe ₂O₃ or iron ore is added along with slag flow, and the addition amount is 10-25% of the weight of slag. The specific operation of the step (2) is as follows: after the slag is discharged, stirring the slag for 10min, then introducing air or oxygen to carry out oxidation desulfurization on refined slag, blowing the slag in a top blowing mode, and inserting a top blowing device into the position 1/2-2/3 of the height below the slag liquid level. Crushing the desulfurized refining slag obtained in the step (4), adding the crushed desulfurized refining slag into a molten iron pretreatment or a converter to prepare a fluxing agent, and adding the fluxing agent into the converter to prepare the fluxing agent, wherein the addition amount of the fluxing agent is 20-40 kg/t. Similar drawbacks as those of patent [ 3 ] and the like are not overcome.

The invention patent CN201811481819.9 is a slag former for a steelmaking converter and a preparation method thereof, and comprises the following raw materials in percentage by weight: 40-45% of quartz sand with the grain diameter of 0.149-5 mm, 40-45% of manganese ore powder with the grain diameter of 0.149-5 mm, 35-40% of dust with the grain diameter of 0.074-0.149 mm, 3-5% of metal silicon powder with the grain diameter of less than 0.044mm and 5-8% of cement with the grain diameter of less than 0.044 mm; adding 0.8 to 1 percent of bonding agent with the grain diameter smaller than 0.044 mm; the slag former for the steelmaking converter comprises the following components in percentage by weight: mnO is more than or equal to 2%, TFe is more than or equal to 20%, siO ₂: 45-50%, P is less than or equal to 0.15%, S is less than or equal to 0.15%, and water is less than or equal to 4.5%. The waste dust in the steelmaking converter is recycled, and the slag-forming raw material is added to prepare the cold-bonded pellets to be returned to the converter for use, so that iron resources are recovered, the consumption of steel raw materials is reduced, the rapid slag-forming can be realized, the dephosphorization efficiency is improved, the molten steel is purified, the pollution is reduced, and the production cost is reduced. The essence is that the metallurgical waste is used for preparing the converter slag former, and the slag former contains P, S and other impurity elements, so that the slag former is particularly enriched after being used for many times, and the slag former has adverse effect on the quality of molten steel of a converter or increases the desulfurization and dephosphorization load of the converter.

The other category relates to not only waste utilization, but also the compounding of slag formers, in fact, most of slag formers are compounded conventionally, and calcium oxide, fluorite and the like are rarely used independently, for example, the Chinese patent No. 2019100042948 discloses a method for preparing a magnesium-calcium composite slag former by byproduct magnesium chloride in a salt lake, which comprises the following steps: mixing lime milk with a salt lake byproduct magnesium chloride raw material for reaction to obtain slurry, carrying out solid-liquid separation on the obtained slurry to obtain magnesium hydroxide, and calcining the obtained magnesium hydroxide to obtain magnesium oxide; grinding and uniformly mixing the obtained magnesia, lime and a binder, and then performing compression molding to obtain the magnesium-calcium composite slag former. The magnesium-calcium composite slag former prepared by the byproduct magnesium chloride in the salt lake has controllable and adjustable components and proportion, simple preparation process, lower calcination temperature than mineral raw materials, lower energy consumption, lower production cost and good slag forming effect. The waste after the potassium extraction of the salt lake is used as the raw material of the slag former, which not only accords with the development mode of circular economy, but also further improves the utilization way and the utilization scale of the salt lake magnesium resource and the sustainable development and balance of the salt lake resource. The method has high calcining energy consumption, and chloride ions in the byproduct magnesium chloride in the salt lake have serious pollution to equipment and environment.

As for the components of the slag former, mainly calcium oxide is used as main component, as disclosed in Chinese patent No. CN201810734687.X, the slag former is applied to refining production, and comprises the following main components in percentage by mass: 42-55% of CaO and 1.12-3.25% of SiO ₂ 10.5-12.1％、MgO 6.5-11.5％、Al₂O₃, wherein the granularity of the slag former is 5-25mm, and the slag former is used for replacing 20-30% of lime by mass and is added into a ladle in the tapping process of a converter. The slag can be formed by replacing part of lime, the alkalinity and slag system requirements of a slag forming process of a refining furnace are met, and the casting blank has normal performance and quality, so that the purpose of replacing lime is achieved; meanwhile, the improved slag former has stable components and low price, and achieves the aim of reducing the slag cost. In addition, limestone can be selected, the main component of the limestone is calcium carbonate, few iron and steel smelting is performed to select calcium aluminate, the main component of the limestone is calcium oxide, and after the lime desulfurization reaction product is wrapped, the lime desulfurization reaction product is prevented from further reaction, so that the metallurgical efficiency of the limestone is reduced. German patent DE200410025779 discloses a slag former, the slag forming material being added in solid form to the metal charge to be melted. Before complete melting, a solid composition is formed in the oven. Or charging the furnace with solid material for melting and solid slag material. Mixing may also be performed on partially molten metal in the furnace. The slag former is calcium aluminate or is matched with other slag formers. The calcium aluminate needs to be synthesized at high temperature, so that the energy consumption is high, and the pollutant emission is increased.

Further japanese patent technology JP2001040430a similarly discloses that a slag-making material of CaO excellent in rapid slag without using fluorite is obtained without using fluorite by using powdered lime or dolomite as a raw material, using aluminum ash in a prescribed proportion as a refining slag in aluminum smelting, and mixing and pressing them into a mixture. The solution is as follows: the mixing ratio of the aluminum ash is 5-60wt.%, and then the lime is pulverized into fine powder, which is then solidified by a high pressure molding apparatus. Lime formed after the primary pulverization treatment has excellent heat conductivity, and can be rapidly slagging by contact with molten steel in a furnace, and slag formation refining can be performed in a short time. The aluminum ash is mixed into lime, mixed and pressed to form, and then the mixed solid is added to a high temperature. If calcium aluminate of low melting point is generated at the boundary of both CaO and Al ₂O₃ in a blast furnace of > =1500 ℃, slag formation is easy. CO ₂ gas is produced by mixing 1-20wt.% of granular calcium carbonate as a slag making activator to activate the slag. The method is characterized in that fluorite with the granularity of 20-50mm is added into slag with high CaO calcium aluminate composition, and the fluorite is essentially prepared by grinding minerals containing calcium oxide and aluminum oxide into fine powder and synthesizing the calcium aluminate slag at high temperature. . If the development of the slag former is to be traced back, only in theory each individual component has been tried, as in the 90 s of the last century even the use of calcium aluminate as slag former has been mentioned, as according to the nillan patent technology NL1002684, it is known that the calcium aluminate obtained can be applied to iron and steel smelting slag formers.

It can also be seen indirectly from the above patents, beyond the general theory of textbook slag formers known in the art, that conventional smelting processes require lime and fluorite as slag formers, which are sometimes also natural minerals, such as limestone, with a high impurity content. In the metallurgical lime standard, the special-grade lime with the best quality comprises CaO more than or equal to 92.0%, mgO% < 5.0%, siO ₂ less than or equal to 1.5%, S less than or equal to 0.020%, burning loss less than or equal to 2%, and activity (mol/mL, 40+/-1 ℃ for 10 min) more than or equal to 360; in the fluorite standard, caF ₂ is more than or equal to 97.0, siO2 is less than or equal to 2.5, S and P are not required, and the water content is less than or equal to 5.0%; however, taking Si as an example, even the special lime has Si content of 1.5%, and the fluorite fine powder with higher quality in fluorite has Si content of 2.5%;

Such as chinese patent CN104328278a. The further more obvious production practice is that the effective components of the calcium oxide of the composite slag former in the prior art are lower, the granularity requirement of the calcium oxide or other slag formers is more severe, the splashing is caused by the too low granularity, the activity is insufficient and the reaction is slower.

【12】 Application number 202110677162.9, a submerged arc slag melting agent for LF refining, and a production process and equipment thereof, wherein the submerged arc slag melting agent comprises the following components in percentage by weight: 40-60 percent of CaCO ₃, 0-20 percent of BaCO ₃, 0-10 percent of Na ₂CO₃, 0-8% of SiC, 0-15% of CaF ₂, 0-8% of C, 0-5% of MgO, 0-6% of CaC ₂ and 0-10% of Al. Wherein the CaCO ₃ is synthetic or natural limestone; the BaCO ₃ may be a hazardous waste containing barium; the Na ₂CO₃ is industrial sodium carbonate; the C can be any one of petroleum coke, graphite electrode waste, carbonaceous material waste or calcined coal; The Al can be any one of aluminum ingot, aluminum-containing waste of an aluminum factory or waste containing metal aluminum; the SiC is industrial smelting grade silicon carbide; the MgO can be any one of magnesia, light burned magnesia, magnesia dolomite or magnesite; the CaC ₂ is an industrial calcium carbide particle. The method comprises the following steps: step 1: pre-fusion slag of 40% CaCO ₃, 3% MgO, 7% BaCO ₃, 5% Na ₂CO₃, 3% SiC and 6% CaF ₂, weighing 3% of Al according to a proportion, and then placing the mixture into a forced stirrer for stirring for 3-5min; Step 2: adding 0-10% of lanthanum-cerium-rare earth mineral, 0-10% of Al, 0-8% of C and 0-6% of CaC ₂, controlling the granularity of the materials, and ensuring that the materials have deoxidizing and desulfurizing capabilities so as to accelerate the desulfurizing rhythm; step 3: and (3) introducing the mixed material in the step (2) into a dryer for thorough drying, and then, putting the mixed material into a high-pressure ball press for dry pressing to obtain a ball-like finished product with proper granularity. The slag former has various raw materials, particularly contains CaF ₂ for environmental pollution, has extremely high storage and transportation safety risks of CaC ₂, and uses Na ₂CO₃ as industrial sodium carbonate dust to prevent the defects of high cost and the like.

【13】 Application number 201710842130.3, a recycling method of LF furnace refining slag. Cooling refining slag obtained after refining in an LF furnace; adding the cooled refining slag into a ladle in KR desulfurization; stirring molten iron in KR desulfurization, and desulfurizing the molten iron by utilizing CaO in the refining slag. The LF refining slag adopted by the invention has the characteristic of high alkalinity, contains a large amount of CaO and CaF ₂, is premelted slag, and is recycled for the KR desulfurization process, so that the consumption of desulfurizing agent can be reduced, the slag melting speed and the desulfurization efficiency can be improved, the metal yield can be further improved, the emission of industrial waste can be reduced, and the harm to the environment can be reduced. The essence is that LF refined slag is recycled to KR desulfurization, and similar problems as patent [ 3 ] exist and are not solved.

The method comprises the following steps: cooling refining slag obtained after refining in an LF furnace; adding the cooled refining slag into a ladle in KR desulfurization; stirring molten iron in KR desulfurization, and desulfurizing the molten iron by utilizing CaO in the refining slag. The refining slag is premelted slag. The alkalinity R of the refining slag is 6-20. The alkalinity R of the refining slag is 10-15. The refining slag does not get water when cooled. The refining slag is added into the ladle together with a desulfurizing agent. The mass ratio of the refining slag to the desulfurizing agent is 1:2-3. The granularity of the refining slag is less than or equal to 3mm. The CaO content in the refining slag is 45-55%.

【14】 Application number 201910361050.5, a refining slag for LF refining. The refining slag comprises the following components in percentage by mass: al ₂O₃ 18-50％、CaCO₃ -80%, unavoidable impurities not greater than 10%, including SiO ₂、MgO、Fe₂O₃, S and P. The invention has the advantages that: (1) The product uses fine powder with the granularity of 0-1mm as raw materials, is fully stirred and has uniform components, and compared with simple mixed refining slag, the product has uniform components, low dust content and high strength, and can effectively improve the operation environment of a use site; (2) The product is as follows: the granularity is 5-15mm, the granularity is moderate, the rapid melting on the surface of steel slag is facilitated, and experiments prove that the melting speed is basically the same as that of premelted refining slag; (3) The product uses high-purity calcium carbonate minerals, can effectively utilize thermodynamic conditions and dynamic conditions of high-temperature molten steel to quickly decompose in the use process, generates foam slag, facilitates quick slag making and submerged arc operation, improves the thermal efficiency, and reduces the erosion of electric arcs to furnace lining and refractory materials. The method comprises the following steps: the first step, the tapping amount of the first furnace is 120t, the slag comprises 50-55% of CaO, 15-17% of SiO ₂ and 20-25% of Al ₂O₃, the basicities of CaO and SiO ₂ are controlled according to 3-4, lime unit consumption is 9-10kg/t, aluminum series premelting slag is 2.0-2.5kg/t, and aluminum series premelting slag is added in the tapping process to obtain total slag quantity of 1500-1800 kg/furnace, and slag layer thickness is 100-150mm; Secondly, adding 1.2-1.5kg/t of aluminum premelting slag in the tapping process of the second furnace; thirdly, after continuously casting steel, pouring 1/2 slag of the residual steel slag into a slag basin by using an overhead travelling crane; pouring the residual 1/2 slag containing the residual steel into the top of the ladle after tapping of the next furnace, wherein the net space of the top of the ladle is more than or equal to 500mm; fourth, placing the ladle poured into the recycled LF refining slag into a refining station, and adding lime according to 5kg/t by halving the lime addition; and fifth, circularly operating according to the steps from the second step to the fourth step. The slag comprises 50% of CaO, 17% of SiO ₂ and 20% of Al ₂O₃, the lime unit consumption is 9kg/t, and the aluminum premelting slag is 2.0kg/t. The slag comprises 55% of CaO, 15% of SiO ₂ and 25% of Al ₂O₃, the lime unit consumption is 10kg/t, and the aluminum premelting slag is 2.5kg/t. And adding 1.2kg/t of aluminum premelting slag in the second furnace tapping process. And adding 1.5kg/t of aluminum premelting slag in the second furnace tapping process. The refining slag is directly untreated by adopting high-purity limestone, and has the advantages of low melting rate, high unit consumption, high energy consumption and lower refining efficiency.

【15】 Application publication number CN101012489A, premelted submerged arc composite refining slag and a preparation method thereof. A novel composite material for external refining of steelmaking furnace is prepared by taking premelting slag as a basic raw material and adding foaming submerged arc materials accounting for 10-30% of the total preparation amount; taking premelted refining slag with granularity of 2-30mm as a basic raw material; adding foaming submerged arc materials accounting for 10-30% of the total preparation amount and having granularity smaller than 30mm, and fully and uniformly mixing mechanically or manually to complete the preparation process of the premelted submerged arc composite refining slag. The desulfurization and inclusion adsorption capability is stronger, the electricity can be saved by 5-10%, and the service life of the furnace lining can be prolonged by 5-15%; compared with the method of adding premelted refining slag and submerged arc slag respectively, the method reduces the slag consumption, improves the slag system performance, and reduces the slag cost by more than 20 percent under the same condition. The premelted submerged arc composite refining slag is a novel composite material for external refining of a steel-making furnace, and is a foaming submerged arc material which takes premelted submerged arc refining slag as a basic raw material and accounts for 10-30% of the total preparation amount; the premelted refining slag is formed by: limestone, dolomite, bauxite and fluorite are used as raw materials; when the cupola furnace is a melting furnace and uses coke fuel, the ash after combustion is also used as a raw material; the foaming submerged arc material is prepared from carbonate: limestone, barite, dolomite, soda and carbon and carbide: carbon powder, calcium carbide and silicon carbide are used as raw materials of the foaming submerged arc material; the foaming submerged arc material can be configured according to two or more of refining requirements, and the emphasis is that the back phosphorus is prevented from being added with more barium calcium stone, the reinforced reduction performance is properly enhanced, and the carburetion is prevented from being added with little or no carbon and carbide. Adding foaming submerged arc materials with granularity smaller than 30mm and accounting for 10-30% of the total preparation amount into premelted refining slag with granularity of 20-30mm as a basic raw material, fully mixing mechanically or manually, and completing the preparation process of premelted submerged arc composite refining; the prepared premelted submerged-arc composite refining slag has the chemical composition ：CaO：30-54％,Al₂O₃：16-45％,SiO₂：≤6％,MgO：0-10％,CaF₂：0-10％,BaCO₃：3-12％,CaCO₃：6-24％,MgCO₃：0-8％,Na₂CO₃：0-8％,C：0-8％,CaC₂：0-8％,SiC：0-8％. that the premelted refining slag is prepared from the following raw materials by weight: 700-1150Kg of limestone, 0-450Kg of dolomite, 250-500Kg of bauxite and 0-120Kg of fluorite; 40-60Kg of coke ash; the foaming submerged arc material is prepared from the following raw materials in parts by weight: 55-255Kg of limestone, 45-180Kg of barium calcium stone, 0-80Kg of dolomite, 0-80Kg of soda, 0-80Kg of carbon powder, 0-80Kg of calcium carbide and 0-80Kg of silicon carbide. The premelting slag is used as a basic raw material, the energy consumption in the premelting slag preparation process is high, and the environmental pollution treatment cost in the preparation process is high.

【16】 Application publication No.: CN101463406a, converter fluxing agent using LF refined slag as raw material and production method thereof. Mixing LF refined slag, sieving, magnetically separating to remove part of slag blocks and iron particles to obtain powder sand-like material with uniform texture below 10mm as production raw material; mixing the raw materials with water, wherein the adding amount of the water is 10-15% of the weight of the raw materials, mixing and rolling, and feeding the materials into compacting equipment to form a solid when partial moisture in the materials is evaporated and the compactness requirement is met; after the molded solid is forced dried or naturally aired, the strength is less than or equal to 11Mpa, and the water content is less than or equal to 1%. The problems of nonuniform chemical components and easiness in pulverization of original refined slag are solved, the converter fluxing agent has the advantages of high slag melting speed, reduction of the phenomena of 'dry return' and slag sticking of an oxygen lance, replacement of iron-vanadium soil, saving of part of limestone, effective utilization of waste slag, reduction of environmental pollution and reduction of steelmaking production cost. The main component of the fluxing agent is LF refining slag; iron ore powder and dust mud are added into LF refining slag, and the addition amount is 5-10% of the weight of the LF refining slag; the production method comprises the following steps: uniformly mixing LF refined slag, and then carrying out screening and magnetic separation treatment to remove part of slag blocks and iron particles in the LF refined slag to obtain powdery sand-like materials with uniform texture below 10mm as production raw materials; mixing the above materials with water, wherein the water content is 10-15% of the total weight of the raw materials. After mixing and rolling, part of water in the material is evaporated, and the material is sent into compacting equipment to be formed into a solid body when the compactness requirement is met; the water content of the formed solid is 1% after forced drying or natural airing, and the strength is 11Mpa. Mixing and rolling for 10-30 min, and naturally airing for 1-3 days. The adhesive is cellulose adhesive. Essentially, LF refining slag is prepared into a converter fluxing agent, and similar problems exist in the patent [ 7 ].

【17】 Application number 201010597673.1, a novel method for manufacturing white slag by using an LF refining furnace. The method comprises the following steps: after the arc striking of the lower electrode of LF refining is successful, firstly adding 2.0-4.0 kg/t of calcium-aluminum balls of steel into molten steel, refining for 1-2 min after adding, and then adding lime slag into the molten steel, wherein the adding amount is controlled to be 6-10.0 kg/t of steel; then adding auxiliary materials containing Al ₂O₃ of 1.0-3.0 kg/t steel into the ladle after refining for 1-5 min so as to further improve the slag melting speed. The slag forming method has the advantages that the rapid whitening of slag can be ensured in a short time, the slag component index meets the requirement of slag system adsorption inclusion with low melting point, the addition amount of other slag materials is saved, the cost is low, and the smelting time can be shortened. After the arc striking of the lower electrode of LF refining is successful, firstly adding 2.0-4.0 Kg/t of calcium-aluminum balls of steel into molten steel, refining for 1-2 min after adding, and then adding lime slag into the molten steel, wherein the adding amount is controlled to be 6-10.0 Kg/t of steel; then adding auxiliary materials containing Al ₂O₃ of 1.0-3.0 Kg/t steel into the ladle after refining for 1-5 min to further improve the slag melting speed. The patent is a slag making method, wherein a slag former is an LF refining method which takes lime and a reducing agent as raw materials and assists a solvent in slag making, after the lime surface layer is wrapped by a reaction product, the inner lime does not participate in the reaction, the utilization efficiency of the lime is reduced, the content of active lime in the slag is too high, and the treatment or the comprehensive utilization of the slag is affected.

【18】 Application number 201210244389.5, a high-efficiency desulfurization refining process for high-low carbon steel. Desulfurizing according to the high and low grade steel with carbon content, wherein the steel tapping sulfur of the low-carbon steel converter is required to be controlled to be 0.010-0.019 (wt%), and the steel tapping sulfur of the high-carbon steel converter is required to be controlled to be 0.015-0.037 (wt%); aiming at the consumption of the lime required by high and low carbon steel, the consumption of the lime of the high carbon steel refining slag is 3.5-4.2 (kg/t), and the consumption of the lime of the low carbon steel refining slag is 6.5-8.0 (kg/t); the alkalinity (CaO/SiO ₂) of the refining slag is required to be between (4.0 and 9.0), the content of FeO and MnO in the refining final slag is controlled, the content of FeO and MnO is less than 0.6 (wt%) and the refining period is 35 to 45 minutes, and the desulfurization time in the earlier stage of refining is prolonged by 3 to 5 minutes. The advantages are that: the existing refining equipment is reasonably utilized, the desulfurization process is determined according to the high-low carbon steel types, the production cost is reduced, the desulfurization efficiency is improved, the yield of the high-low carbon low sulfur steel reaches 95%, and the technical support is provided for producing high-grade low sulfur steel types by the steel cladding. Desulfurizing according to the high and low grade steel with carbon content, and limiting the converter tapping sulfur content of high carbon steel and low carbon steel, wherein the converter tapping sulfur of the low carbon steel is required to be controlled to be 0.010-0.019 (wt%), and the converter tapping sulfur of the high carbon steel is required to be controlled to be 0.015-0.037 (wt%); aiming at the consumption of the lime required by high and low carbon steel, the consumption of the lime of the high carbon steel refining slag is 3.5-4.2 (kg/t), and the consumption of the lime of the low carbon steel refining slag is 6.5-8.0 (kg/t); the alkalinity (CaO/SiO ₂) of the refining slag is required to be between (4.0 and 9.0), the content of FeO and MnO in the refining final slag is controlled, the content of FeO and MnO is less than 0.6 (wt%) and the refining period is 35 to 45 minutes, and the desulfurization time in the earlier stage of refining is prolonged by 3 to 5 minutes. Similar to patent [ 17 ], there are similar problems.

【19】 Application number 201610597939.X, an LF refining slag system of vanadium-containing low alloy steel and a slag forming method. Lime is used as slag, vanadium slag is used as cosolvent, and aluminum powder and calcium silicate powder are used as deoxidizer. CaO-SiO ₂-Fe₂O₃ generated by vanadium slag slagging in the slag system is used as a main body, and the melting point is 1300-1350 ℃ lower than the melting point 1402 ℃ of fluorite; therefore, the invention has the characteristic of low melting point, is beneficial to the rapid melting of slag, promotes the dissolution of lime, ensures the rapid refining, and improves the metallurgical effect and the smelting efficiency. The slag system adopts vanadium slag to make slag, and a certain amount of FeO, mnO, V ₂O₅ and other oxidizing substances in the vanadium slag can have a certain influence on alloy recovery, but the auxiliary use of aluminum powder and calcium silicate powder for deoxidation can effectively control the FeO+MnO content of slag to be within 3.0 percent. The ladle slag refining method for the LF furnace not only reduces the cost of ladle refractory materials, but also can be used for carrying out V microalloying to replace the dosage of partial vanadium alloy, and has the effect of achieving two purposes at one time. Lime is used as slag, vanadium slag is used as cosolvent, and aluminum powder and calcium silicate powder are used as deoxidizer. The addition amount of each raw material is as follows: lime 5-8 kg/ton steel, vanadium slag 1.5-3 kg/ton steel, aluminum powder 0.25-0.4 kg/ton steel, and silicon-calcium powder 0.2-0.4 kg/ton steel. The TFe content in the slag system is 15-20wt%. The granularity of the vanadium slag is 5-20 mm; the granularity of the lime is 5-20 mm; the granularity of the aluminum powder is 1-4 mm. The method comprises the following steps: (1) 3-4 kg/ton of steel lime is added along with the alloy in the tapping process of the converter; (2) After molten steel reaches an LF furnace, 1-2 kg/ton of lime and 1.5-2 kg/ton of vanadium slag are added, and then 0.25-0.4 kg/ton of aluminum powder is added to the slag surface; the lime is added in the heating process to be 1-2 kg/ton and the vanadium slag is added in the heating process to be 0-1 kg/ton; (3) In the LF refining process, 0.2-0.4 kg/ton of calcium silicate powder is added into slag. In the step (3), calcium silicate powder is added until the FeO+MnO content in the slag is less than or equal to 3.0wt%. The granularity of the vanadium slag is 5-20 mm; the granularity of the lime is 5-20 mm: the granularity of the aluminum powder is 1-4 mm. The slag formation treatment is carried out by using lime which is not a main phase, so that the problems are not solved, meanwhile, the raw materials are various, and the difficulty in the LF refining process is increased.

【20】 Application number 201710053424.8, an LF furnace refining slag and a preparation method thereof. The composite refining slag of the LF furnace is prepared from 60-100 parts of aluminum electrolysis waste lining bricks and 0-40 parts of aluminum ash, wherein the granularity of the aluminum electrolysis waste lining bricks and the aluminum ash is crushed to be less than 5mm, mixed for 10-20 min, and dried at the temperature of below 300 ℃ to ensure that the water content of the mixture is less than 0.5% of the total weight of the mixture, so as to obtain the composite refining slag of the LF furnace; according to the invention, the refining slag agent is prepared by utilizing the aluminum electrolysis waste lining bricks and aluminum ash, and when silicon carbide in the waste lining bricks and aluminum in the aluminum ash are added into an LF furnace, heat is released, so that a reducing atmosphere is formed, and the removal of oxygen content in steel is facilitated; Compared with other LF furnace deoxidizing slag agents, the aluminum electrolysis waste lining bricks and aluminum ash are low in price, the production cost of LF furnace slagging is reduced, and the LF furnace refining slag is stable in quality, so that the recycling of the aluminum electrolysis waste lining bricks and aluminum ash waste is achieved, and the added value of solid waste is improved. The composite slag former comprises the following raw materials: aluminum electrolysis waste lining bricks and aluminum ash. The composite material consists of the following raw materials in parts by weight: 60-100 parts of aluminum electrolysis waste lining bricks, 0-40 parts of aluminum ash and 100 parts of the sum of the weight parts of raw materials. The composite material consists of the following raw materials in parts by weight: 75 parts of aluminum electrolysis waste lining bricks, 25 parts of aluminum ash and 100 parts of the sum of the weight parts of raw materials. Based on 100 parts by weight, the main components of the aluminum electrolysis waste lining brick comprise: 60-75 parts of SiC, 14-25 parts of Si3N4, 13 parts of Na ₂SiO₃, 2 parts of NaF and the balance of impurities; The aluminum ash comprises the following main components in parts by weight: 10 to 25 portions of Al, 31.55 portions of Al ₂O₃, 5.5 portions of SiO ₂, 3 portions of MgO, 2 portions of CaO, 3 portions of Na ₂ O, the other content is impurity. The method comprises the following steps: step one: crushing the granularity of the aluminum electrolysis waste lining bricks and aluminum ash to below 5 mm; step two: mixing the aluminum electrolysis waste lining bricks obtained in the step one with aluminum ash for 10-20 min according to the composition weight of the raw materials to obtain a mixture; step three: drying the mixture at the temperature below 300 ℃ to ensure that the water content of the mixture is less than 0.5 percent of the total weight of the mixture, thereby obtaining the refining slag. The main raw materials of the refining slag are waste refractory materials for electrolytic aluminum, wherein the alkalinity of slag is ensured by mainly utilizing the reducing metal aluminum, al ₂O₃ and the like and adding MgO and CaO, the inherent defects of the slag are not solved, the content of magnesium oxide is increased, the fluidity of the slag is poor, and the metallurgical effect is poor.

【21】 Application number 201711146099.6, a slag-forming process of an LF refining furnace and a slag-forming agent. The method comprises the following steps: heating molten steel; adding calcite particles into the molten steel according to the pre-calculated calcite required amount; observing the slag condition to determine whether calcite particles need to be continuously added, and if so, continuously adding the calcite particles into the molten steel; if not, the following steps are entered. The slag former in the invention is calcite particles. Calcite is a natural mineral, does not deliquesce and deteriorate, does not need special storage conditions, has no use time limit and does not pollute the environment. Compared with the traditional separate addition of the slag former and the foaming agent, the invention reduces the labor amount and shortens the processing time. The CaO slag former and the CO ₂ foaming agent are added simultaneously all the time, so that continuous foaming can be ensured, and the method is favorable for quickly forming refining slag with high alkalinity, good fluidity and good foaming effect. The method comprises the following steps: s1: heating molten steel S2: adding calcite particles into the molten steel according to the pre-calculated calcite required amount; s3: observing the slag condition to determine whether the calcite particles need to be continuously added, and if so, continuously adding the calcite particles into the molten steel; if not, the following steps are entered. The step S2 of adding calcite particles to molten steel specifically includes: calcite particles are added to the molten steel in batches over a prescribed period of time and at elevated temperatures. The "within a prescribed time" is specifically within 8 minutes to 12 minutes. The particle size of the calcite particles in the step S2 is 20 mm-50 mm. The step S2 of adding calcite particles into molten steel is specifically to send the calcite particles into the molten steel through vibration of a bin. The "heating molten steel" in the step S1 specifically includes: heating molten steel through an electrode; the electrode is pre-buried above molten steel; the electrode is first lifted before "observe slag condition to decide whether or not the addition of calcite particles needs to be continued" in step S3. The slag former is calcite particles. The single calcite is directly added into LF for refining, so that the melting rate is low, the energy consumption is high, the generated slag component is single, the sulfur capacity and the inclusion adsorption capacity are low, and the metallurgical effect is reduced.

【22】 Application number 202310632635.2 is an environment-friendly refining slag for improving inclusions in spring steel and a smelting process. The components in percentage by weight are: 17-20% of Al ₂O₃:18～22％,MgO:5～10％,CaO:50～55％,SiO₂, and controlling the alkalinity to 2-3. The refining slag effectively avoids the use of fluorine-containing substances, reduces the release of fluorine-containing harmful substances, is more green and environment-friendly, and accords with the green development direction. The method comprises the following steps: (1) The tapping starts to see steel flow, carbon powder is immediately added for pre-deoxidation, metal manganese, ferrosilicon and refining slag are added for 5-10kg/t, low titanium ferrochrome and 15-20kg/t refining slag are added after the tapping is finished, and the steel is opened after high-flow bottom blowing; (2) Adding high-purity silicon carbide in batches for diffusion deoxidation in the refining process, wherein the refining process is carried out on the power supply slag, slag charge is not added any more, quartz sand is strictly forbidden to be added, and white slag is kept for 15-20min; (3) The vacuum treatment dipping pipe enters molten steel, carbonized rice hulls are immediately added, and the exposure of the molten steel is strictly forbidden. The addition amount of the carbon powder in the step (1) is 3-5kg/t. The flow rate in the step (1) is controlled to be 500-600l/min, and the bottom blowing time is more than or equal to 3min. The addition batch of the step (2) is 3-5 batches. The total amount of the high-purity silicon carbide added in the step (2) is controlled to be 100-200kg. The high-purity silicon carbide in the step (2) is added in the power transmission process and is added on the slag surface close to the lower part of the electrode, so that the molten steel is prevented from entering the exposed surface of the molten steel. The vacuum degree in the step (3) is less than or equal to 2.0mbar, and the treatment time is 15-20min. And (3) carrying out vacuum treatment, wherein the static stirring time is more than or equal to 20min. The refining slag still adopts lime base, and the common problem with the similar patent is still unsolved, and meanwhile, the use amount of the refining slag is large, and the utilization efficiency is lower.

CN114075619a discloses a slag making method of fluoride-free CaO-SiO ₂ refining slag in steel making technology. Lime and industrial sodium carbonate are added as slag forming during and after tapping, and slag components CaO of 27-51% and SiO ₂:25-32％,Na₂ O are controlled: 8-31%, and the basicity of slag is controlled to be 1.1-1.6. The common problem of lime refining and similar patents is still unsolved, and the environment pollution caused by using industrial sodium carbonate is serious, and the corrosion of ladle refractory materials is serious.

CN111926141a discloses a refining slag for obtaining CaO-SiO ₂ -MgO low melting point inclusion. The composition is used for the cord steel, the mass percentage of each component of the refining slag is 15-25% of MgO, the Al ₂O₃ is less than 3%, the balance is CaO and SiO ₂, the alkalinity is 0.7-1.0, the CaO-SiO ₂ -MgO inclusion with low melting point can be obtained, and the erosion of the refining slag to the steel ladle refractory material can be reduced. The refining slag is limited in application range only for the cord steel, and the problem of lime refining is not solved.

In summary, LF refining slag is divided into basic slag (CaO-Al ₂O₃ slag system), fluxing agent (CaF ₂), foaming agent (silicon carbide, calcium carbide) and the like, in the LF refining process, the mutual reaction of all components is carried out to obtain the refining slag with low melting temperature, moderate viscosity, good foaming performance and good deoxidization and desulfurization performance, the characteristics of high alkalinity, low oxidizing property and high sulfur capacity of the refining slag are utilized to refine molten steel, So as to realize the metallurgical functions of deoxidizing and desulfurizing molten steel, adsorbing impurities in the steel, controlling the forms of the impurities, and the like. The basic slag of the LF furnace is composed of slag systems which are positioned at low melting points in a ternary phase diagram of CaO-SiO ₂-Al₂O₃ systems. The improvement of slag alkalinity reduces the oxygen content balanced with the slag alkalinity in the steel, and simultaneously improves the distribution ratio of sulfur among slag steels, thereby being beneficial to deoxidation and desulfurization. If the alkalinity of the refining slag is too large, if R (CaO/SiO ₂) is more than or equal to 5, the viscosity of the refining slag is too large, the melting is difficult, the fluidity is poor, and the deoxidizing and desulfurizing effects of molten steel are affected. When the domestic aluminum killed steel and other varieties of steel are produced, the alkalinity (CaO/SiO ₂) is more than or equal to 2, and the process belongs to a high-alkalinity slag refining process, has better desulfurization and degassing effects, but is unfavorable for the effective control of oxide inclusions such as B type and D type, the oxide inclusions such as B type and D type are high-melting-point and non-deforming inclusions, and quality defects such as microcracks, cavities and the like can be generated on the interface between the steel and the steel base, so that the fatigue, drawing and other performances of the subsequent processing process of the steel are obviously reduced, and the performance improvement of the steel is difficult; the CaO-SiO ₂-Al₂O₃ slag system adopts a high-alkalinity slag refining process, the process is difficult to effectively control the quantity of non-deforming spherical oxide inclusions in steel, and particularly when producing high-carbon hard wire steel, bearing steel, spring steel and other steel types with strict requirements on inclusions, the quality control is unstable, and the requirement on subsequent processing and use is difficult to meet. In addition, the reducing slag formed after LF refining is mainly CaO-MgO-SiO ₂ slag system for smelting silicon killed steel and CaO-Al ₂O₃-SiO₂ slag system for smelting aluminum killed steel, and has the characteristics that: 1) One of the main components is dicalcium silicate, and the gamma-C ₂S→β-C₂ S crystal form transformation occurs at the temperature lower than 675 ℃, And with 5% volume change, pulverization is generated, and environmental pollution is serious. 2) CaO, siO ₂、Al₂O₃ and MgO components exist in a large amount in the LF refining reducing slag, but the LF refining slag contains very high sulfur, which is a substance harmful to molten steel, so that the recycling of the refining reducing slag in the metallurgical industry is hindered. The solid wastes are only used in a small amount as an iron-making sintering solvent and for manufacturing special cement, no effective large-scale treatment process exists for the treatment of white slag in the metallurgical industry at present, the discharge treatment is always a problem avoided by steel-making enterprises, and the discharge treatment is contrary to converter steel slag, which can be fully treated and utilized at present.

At present, the actual production has a plurality of types of refining slag for the LF furnace, and metallurgical workers continuously develop and try various refining slag for the LF furnace according to different steel types and different refining processes. But mainly comprises several kinds, namely synthetic slag prepared from lime, bauxite or fluorite slag and the like; the slag is formed by carrying out proper processing treatment on the raw materials and then carrying out simple mechanical mixing, has the advantages of low slag forming rate, high slag material consumption, high energy consumption and heavy environmental load, and fluorine-containing slag also aggravates lining erosion and environmental pollution, and can not well achieve the purpose of LF refining and slag formation, and particularly has lower quality qualification rate and high ton steel cost when smelting high-grade steel. The second category is pre-fused slag, which is obtained by melting limestone, dolomite, solvent calcium fluoride or bauxite and the like at high temperature, and mainly comprises calcium aluminate series, wherein the slag has lower melting point and higher sulfur capacity, but the slag has long production flow, high energy consumption and large environmental pollution, and the inherent defects of the slag belong to CaO-SiO ₂-Al₂O₃ slag series. The third type is regenerated synthetic slag obtained by treating metallurgical waste slag as a raw material, such as LF refining slag subjected to high-temperature heating or liquid slag, after oxygen blowing to remove sulfur therein, caO, siO ₂、Al₂O₃ and MgO contained in the slag are recycled in the LF refining process, but the repeated recycling of harmful elements such as SiO ₂, P, S and the like in the slag can be enriched and increased; The mineral phase structure of components such as CaO, siO ₂、Al₂O₃, mgO and the like tends to be stable, the activity is reduced, the refining effect is seriously affected, and the production requirement of high-cleanliness steel is hardly met; in addition, the waste metallurgical slag is high in energy consumption, serious in environmental pollution and the like in the recovery treatment process, so that the scale application of the waste metallurgical slag is limited. And fourth class, taking calcium carbonate, magnesium carbonate or superfine powder of the mixture of calcium carbonate and magnesium carbonate as a main raw material, and adding refined slag powder formed by calcium oxide, magnesium oxide or the mixture of calcium oxide and magnesium oxide, low-melting-point premelting slag, calcium fluoride and the like. The method adopts superfine powder of calcium carbonate, magnesium carbonate or a mixture of calcium carbonate and magnesium carbonate as an in-situ forming agent of tiny bubbles, and the decomposition process of the calcium carbonate and the magnesium carbonate comprises the following steps: caCO ₃—CO₂+CaO;MgCO₃—CO₂ +MgO. When the calcium carbonate and magnesium carbonate powder is fine enough, the size of the generated bubbles is equivalent to the size of the powder. Ultrafine bubbles (bubbles between 10 and 300um in size) can be induced in the molten steel. The finer the size of the bubbles, the higher the removal efficiency of the inclusions. in addition, the size of the other product magnesium oxide or calcium oxide after the composite spheres of the added mixture of calcium oxide, magnesium oxide or calcium oxide pre-magnesium oxide, low-melting point pre-slag, calcium fluoride, calcium carbonate, magnesium carbonate or calcium carbonate pre-magnesium carbonate are decomposed is small, slag drops can be quickly melted in molten steel and form low-melting point calcium aluminate with Al ₂O₃ inclusion in the molten steel, and the low-melting point calcium aluminate is easy to float into ladle slag, so that the quantity and the size of Al ₂O₃ inclusion generated by refining are reduced. Fine bubbles are generated, the collision probability with the inclusions is high, and meanwhile, the fine slag drops have slag washing function, so that the inclusions in the molten steel can be effectively removed, and the sulfur of the molten steel after desulfurization is reduced to about 0.0012%. After the surface layer of the calcium oxide or magnesium oxide still reacts with sulfur or Al ₂O₃, the product is wrapped on the surface of the calcium oxide or magnesium oxide particles to prevent the further reaction, so that the slag forming material has high consumption and low efficiency; the slag is superfine powder, and dust pollution and a large amount of slag waste can be caused in the storage, transportation and use processes; The added CaO and MgO are extremely easy to absorb water and deteriorate because of superfine powder, and seriously affect the service performance.

The metallurgical work is based on the requirement of different steel grades on the cleanliness, and LF refining slag and refining technology thereof are continuously developed to meet the production requirement of high-cleanliness or ultra-cleanliness steel. In order to maintain and exert the advantages of the existing LF refining slag, the adverse effects of the LF refining slag are restrained, and the problems of high energy consumption, high inclusion content of steel products, bad inclusion shape or oversized steel products, slow slag forming speed or insufficient foaming, short duration, slow desulfurization rate, weak inclusion adsorption capacity, environmental pollution of the slag during or after refining and the like of the existing refining slag are overcome. The high-efficiency environment-friendly LF refining slag is developed, so that the high-efficiency environment-friendly LF refining slag is suitable for secondary refining slag systems of molten steel, and particularly meets the requirements of LF production of clean steel or ultra-clean steel refining slag, further improves the efficiency of removing desulfurization and absorbing inclusion, reduces consumption and improves efficiency, is more environment-friendly, and becomes a problem to be solved urgently by practitioners in the industry.

Disclosure of Invention

The invention aims to solve the problems and defects in the prior art and provides LF refining slag treated by microorganisms and a preparation method and application thereof. The LF refining slag solves the problems of high consumption, low desulfurization rate and efficiency, high energy consumption, high inclusion content in steel, poor inclusion shape or oversized inclusion, slow slag forming rate or insufficient foaming, short duration, weak inclusion adsorption capacity, environmental pollution of the refining process or post-refining slag and the like in the preparation or refining process of the refining slag in the prior art. The fluorine-free environment-friendly LF refining slag integrating inclusion modification, inclusion adsorption, desulfurization, reducing agent, cosolvent and the like has the advantages of low melting point, high sulfur capacity, strong desulfurization capability, good desulfurization effect, strong inclusion adsorption capability, capability of adsorbing and removing large-particle inclusion, capability of capturing fine inclusion, low manufacturing cost and safety and convenience in transportation and storage. In particular, the invention does not contain fluoridation, belongs to green environment-friendly LF refining slag and a manufacturing method and application thereof, and is realized by the following technical scheme.

The preparation method of the LF refining slag by the microorganism treatment comprises the following steps:

firstly, respectively cleaning limestone, bauxite, dolomite, potassium feldspar and carbon-containing minerals, removing impurities, and then respectively processing into granular particles; mixing according to a certain proportion, grinding into raw ore powder; respectively processing metal aluminum, silicon carbide and carbon-containing materials into powder;

Step two, raw ore powder, metal aluminum, silicon carbide and powder of carbon-containing materials, microorganism bacteria, microorganism nutrient and organic adhesive obtained in the step one are added according to the proportion, a proper amount of vegetable oil is added, and the mixture is uniformly mixed and then extruded for forming;

Maintaining the extrusion molded product, wherein after carbon or organic matters in the extrusion molded product are phagocytized by microorganism bacteria, fine and porous holes are formed in the extrusion molded product;

and step four, heating or adopting ultraviolet rays to kill the microorganism bacteria to obtain the porous extrusion molded product.

In the first step, 60-76% of raw limestone, 18-30% of bauxite, 2-8% of dolomite, 1-10% of potassium feldspar and 1-3% of carbon-containing mineral in raw ore mixture of raw limestone, bauxite, dolomite, potassium feldspar and carbon-containing mineral; in the second step, the raw ore powder obtained in the first step accounts for 65-87% of the total mixture; the microbial bacteria accounts for 0.6 to 1.5 percent of the total mixture; the microbial nutrient accounts for 0.5 to 1.3 percent of the total mixture; the organic adhesive accounts for 1-9% of the total mixture; the metal aluminum accounts for 2-10% of the total mixture; the silicon carbide accounts for 2-9% of the total mixture; the carbon-containing material accounts for 2-6% of the total mixture.

Further, the method comprises the steps of,

The limestone content in the limestone raw ore after the impurity removal by gravity separation is more than 95 percent; the Al ₂O₃ content in the bauxite is more than 90 percent; the content of dolomite in the dolomite raw ore is more than 95 percent; the content of potassium feldspar in the potassium feldspar raw ore is more than 95 percent; the carbon-containing minerals are low sulfur, S is less than or equal to 0.1 percent, phosphorus is less than or equal to 0.1 percent, and the content of activated carbon is more than or equal to 90 percent, such as coal or graphite ore and other carbonaceous raw materials; the powdery metal aluminum is processed by metal aluminum with aluminum content more than or equal to 98.5 percent; the SiC content in the silicon carbide is more than 90 percent; the carbonaceous material comprises: graphite with carbon content more than or equal to 90%, waste electrode powder, low sulfur, S less than or equal to 0.1%, low phosphorus, P less than or equal to 0.1% and other materials.

The microbial nutritional agent comprises: at least one of corn flour, rice flour, potato and sweet potato flour.

The organic adhesive is at least one of sugar residues, molasses, organic silicone oil, corn or potato or sweet potato starch, organic asphalt and other organic adhesives; the vegetable oil comprises at least one of rapeseed oil, corn oil and peanut oil.

The microorganism includes: at least one of yeast, lactobacillus and bifidobacterium. Preferably, the concentration of the bacterial liquid is not lower than 1X 10 ⁸/mL.

The preparation method comprises the following more detailed steps:

firstly, raw minerals such as limestone, bauxite, dolomite, potassium feldspar, carbon-containing minerals and the like are cleaned, the impurities are removed by gravity selection, the raw minerals are processed into granular particles not more than 25mm, the granular particles are proportioned according to a proportion, and the granular particles are placed in a ball mill or a Raymond mill and ground into raw mineral powder with the particle size of-180 to-240 meshes; then processing the metal aluminum, the carbon-containing material and the silicon carbide into powder with the granularity of-80 to-100 meshes for later use;

step two, raw ore powder with the meshes of-180 to-240, microorganism bacteria, microorganism nutrient, organic adhesive, metal aluminum powder, carbon-containing material powder and silicon carbide powder are proportioned, vegetable oil (preferably accounting for 1-5 percent of the total amount of all materials) is added, uniformly mixed and then extruded for forming.

Step three, the pressed extrusion molding is cured for 1 to 4 days at the ambient temperature of 0 to 45 ℃ and the humidity of 30 to 80 percent, and micro-organisms engulf carbon or organic matters in the extrusion molding to form fine and porous holes inside;

And fourthly, placing the extrusion molded product into a microwave heating furnace, preheating by utilizing industrial waste, or heating by utilizing gas or natural gas or electricity, and keeping the temperature of 90-130 ℃ for 1-20 minutes, or sterilizing by adopting ultraviolet rays, and obtaining the LF refining slag after killing the microorganism bacteria.

The invention also provides LF refining slag prepared by the method.

The LF refining slag comprises the following components: density 2.5-3.8 tons/cubic meter, melting point 1230-1330 deg.C, porosity 20-36%, granularity: 15-50mm accounts for more than 90%, preferably rectangular or square blocks with a particle size of length (15-50 mm) x width (10-40 mm) x height (10-40 mm); when CaO/SiO ₂ = 1.8-3.0, the sulfur content in the molten steel is reduced to below 0.0003%, and the desulfurization rate is more than 90%; the total content of impurity elements in the steel [ O ] + [ S ] + [ H ] + [ N ] + [ P ] is less than or equal to 0.0050%; the class D and class B inclusions are less than or equal to 0.5 level.

The invention also provides application of the LF refining slag prepared by the method in a secondary refining process of molten steel, in particular in refining in an LF furnace.

The fluorine-free environment-friendly LF refining slag integrating inclusion modification, strong inclusion adsorption capacity, deep desulfurization, reducing agent, cosolvent and the like has the advantages of low melting point, high sulfur capacity, strong desulfurization capacity, good desulfurization effect, strong inclusion adsorption capacity, capability of adsorbing large-particle inclusion, capability of capturing fine inclusion, low manufacturing cost, and safety and convenience in transportation and storage. The density of the refining slag is as follows: 2.5-3.8 tons/cubic meter, melting point: 1230-1330 ℃, porosity: 20-36%, granularity: 15-45mm accounts for 95% of the characteristics; when the slag binary alkalinity CaO/SiO ₂ =1.8-3.0 is used in the secondary refining process of molten steel, especially in the refining process of an LF furnace, the treatment period is 20-35min, the sulfur content in the molten steel can be reduced to below 0.0003%, and the desulfurization rate is more than 90%; the method can realize the purpose of LF refining pure steel or ultra pure steel, is used for LF refining, and can reach the total amount of impurities [ O ] + [ S ] + [ H ] + [ N ] + [ P ] in steel less than or equal to 0.0050%; the class D and class B inclusions are less than or equal to 0.5 level.

The preparation method of the invention; raw ore is adopted as a main raw material, and the raw ore is subjected to impurity removal, processing into fine powder, mixing and homogenizing, extrusion molding, microbial maintenance and low-temperature sterilization to obtain LF refining slag with high porosity and large specific surface area.

The main raw materials used in the invention are raw minerals, the raw minerals are processed and finely ground into powder by physical processing, then microbial bacteria are added into the raw minerals and then are formed into blocky materials, the microbial bacteria are propagated in the blocky materials in a large quantity and uniformly distributed in the blocky materials under a certain temperature and humidity environment, organic nutrition or carbonaceous substances uniformly distributed in the blocky materials are phagocytized, then the microbial bacteria are killed at a higher temperature, the blocky materials form materials with extremely high void ratio, when LF refining or tapping is carried out, steel slag is mixed and washed, molten steel enters the interiors of blocky refining slag from the void, free oxygen in the molten steel and reducing substances such as aluminum, carbon, silicon, microbial bacteria and the like in the refining slag block rapidly generate oxidation exothermic reaction, a large quantity of heat is released, and meanwhile, the refining slag is heated together by the high physical heat of the molten steel, the lime or dolomite and the like are quickly heated to decompose and release CO ₂ or CO tiny bubbles, simultaneously, the newly-generated active CaO and MgO have extremely high volume and rapid change, the reactions are carried out under the condition of high porosity in the bulk slag, the contact area between molten steel and slag is increased, the bottleneck problem that the reaction products on the surface layer of CaO or MgO are wrapped and the further reaction capacity is lost is thoroughly solved, the CaO and MgO and the like with extremely high activity react with [ S ], [ O ], [ N ] in steel to generate corresponding compounds, al ₂O₃ or SiO ₂ and alkali metal oxides on the one hand play the roles of accelerating the melting and the slag formation of refined slag, and on the other hand play the roles of quickly desulfurizing and adsorbing inclusion, thereby realizing the high-efficiency desulfurization and inclusion adsorption, including tiny oxide, sulfide and nitride inclusion of class D and class B which are less than or equal to 0.5 level; in addition, the oxygen in the molten steel and reducing agents such as aluminum and silicon in LF refining slag, especially CO ₂ or CO tiny bubbles generated by the reaction of carbon and killed microorganism bacteria, and meanwhile, the alkalinity of the refining slag is moderate, the LF refining slag forms continuous foaming, thereby being beneficial to controlling the suction and the adsorption of impurities in the molten steel and realizing the aim that the total amount of [ O ] + [ S ] + [ H ] + [ N ] + [ P ] after the refining of the molten steel is less than or equal to 0.0050%.

The percentages expressed in the present invention are generally percentages by weight unless otherwise indicated.

Detailed Description

The following examples are set forth to provide those of ordinary skill in the art with a more complete understanding of the present invention and are not intended to limit the present invention; the test methods described in the examples below, unless otherwise specified, are all conventional; the reagents and materials, unless otherwise specified, are commercially available.

Example 1

Selecting raw limestone ore with 96% of the content of the limestone subjected to the heavy selection and impurity removal, wherein the raw limestone ore accounts for 61.3% of the total mixture of the raw ores; bauxite with 92% Al ₂O₃ content accounts for 29.0% of the total raw ore mixture; dolomite raw ore with the dolomite content of 98.7 percent accounts for 3.6 percent of the total mixture of the raw ore; potassium feldspar raw ore with the potassium feldspar content of 96.8 percent accounts for 3.5 percent of the total mixture of the raw ore; coal with 0.083% of S, 0.076% of P and 2.6% of active carbon C=93.1% of total mixture of raw ores is accurately weighed, added into a ball mill for grinding, the mixture is ground into fine powder of-200 meshes to-220 meshes, and then placed into an intermediate storage bin or a storage tank for storage; processing metal aluminum with the aluminum content of 98.8% into powder with the granularity of-80 to-120 meshes, and storing the powder in a closed storage tank; processing silicon carbide (the rest comprises impurities such as SiO ₂) material with SiC content of 92.5% into powder with granularity of-80 to-120 meshes, and storing in a closed storage bin; processing the sulfur-removed petroleum coke with the C content of 90.5 percent (the balance comprises impurities such as gangue) into powder with the granularity of-80 to-120 meshes, and storing the powder in a closed storage bin; then weighing ingredients, weighing the raw ore fine powder mixture accounting for 86% of the total amount, weighing microorganism bacteria-saccharomycetes accounting for 0.98% of the total amount, wherein the concentration of the microorganism bacteria-saccharomycetes is 1X 10 ⁸/mL, weighing microorganism nutrient agent-corn flour accounting for 0.52% of the total amount, and weighing organic adhesive-potato starch accounting for 6.3% of the total amount; the content of the metal aluminum in the mixture is 2.10 percent; silicon carbide accounts for 2.1% of the mixture; the content of the carbon-containing material-sulfur-removed petroleum coke in the mixture is 2.0 percent; adding proper amount of anhydrous rapeseed oil, the addition amount of the anhydrous rapeseed oil accounts for 1.3 percent of the total weight of the mixture, stirring and mixing uniformly by a turntable mixing machine and a powerful mixing machine, pressing into blocks with the length of 50mm multiplied by the width of 40mm multiplied by the height of 10mm by an isostatic pressing machine, stacking for 3.5 days under the environment with the humidity of 32.5 percent at the environment temperature of 6.5 ℃, placing the processed blocks into a microwave heating furnace, keeping for 18 minutes at the temperature of 100 ℃, and killing microorganism bacteria to obtain the rest porous blocks which are LF refining slag. The density of the refining slag is 3.15 tons/cubic meter, the melting point is 1281 ℃, the void ratio is 21.3 percent, and the granularity is as follows: 50X40X10mm accounts for 91%.

Molten steel is smelted by a converter with nominal capacity of 100 tons, the converter molten steel is refined and slagged in an LF furnace with nominal capacity of 100 tons, and the incoming molten steel comprises the following components: 0.83% of C, 0.16% of Si, 0.23% of Mn, 1.15% of Cr, 0.0015% of P and 0.034% of S, 6.0Kg/t of steel is used as refining slag, the smelting period is 32 minutes, and the final slag is: caO:42.65%, siO ₂:18.23％,Al₂O₃:28.7%, mgO 5.65%, TFe:0.45%, the ingredients of the outgoing LF refining station are as follows: 0.95% of C, 0.27% of Si, 0.30% of Mn, 1.61% of Cr, 0.0013% of P, 0.00028% of S, 0.0010% of O, 0.0003% of H, 0.0010% of N, less than 0.5 level of B-class and D-class inclusions, and a desulfurization rate of 99.18%.

Comparative example 1

In comparison with example 1, the same furnace or the same batch of molten iron as in example 1 was used, and the charged amount of the furnace was substantially the same as in example 1. For the adjacent smelting times of the embodiment, the smelting operation is basically the same as the embodiment, except that the LF refining slag adopts the conventional quicklime, calcium carbide, fluorite, carbon powder and aluminum particles to carry out LF foam slag, the lime addition amount is 12 Kg/ton of steel, the calcium carbide is 1.52Kg/t, the fluorite is 1.45Kg/t, the carbon powder is 2.2Kg/t, the aluminum particles are 1.82Kg/t, and the incoming molten steel comprises the following components: c0.86%, si0.21%, mn0.28%, cr1.18%, P0.0021%, S0.032%, refining period 43 minutes, final slag binary basicity r=4.52, tfe=0.78%, and LF outbound molten steel composition: c=1.04%, si0.31%, mn0.38%, cr1.58%, p=0.0027%, s=0.0064%, o=0.0018, n=0.0046%, h=0.0004%, molten steel temperature class B-class D inclusions are at 1.0-1.5 level, desulfurization rate is 80.0%. The smelting period is prolonged by 34.3%, the slag charge consumption is increased by 2 times, and the TFe content in the slag is increased by 0.33%.

Example 2

Selecting limestone raw ore with 97% of the content of the limestone subjected to the heavy selection and impurity removal, wherein the limestone raw ore accounts for 75.8% of the total mixture of the raw ore; bauxite with 92% Al ₂O₃ content accounts for 18.5% of the total raw ore mixture; dolomite raw ore with the dolomite content of 98.0 percent accounts for 3.0 percent of the total mixture of the raw ore; potassium feldspar raw ore with the potassium feldspar content of 96 percent accounts for 1.2 percent of the total mixture of the raw ore; coal with 0.083% of S, 0.076% of P and 1.5% of active carbon C=95% of total mixture of raw ores is accurately weighed, then added into a ball mill for grinding, the mixture is ground into fine powder of-200 meshes to-220 meshes, and then the fine powder is placed into an intermediate storage bin or a storage tank for storage; processing metal aluminum with the aluminum content of 99% into powder with the granularity of-90 to-100 meshes, and storing the powder in a closed storage tank; processing silicon carbide material with the SiC content of 92% into powder with the granularity of-80 to-100 meshes, and storing the powder in a closed storage bin; processing graphite with 93% C content into powder with granularity of-80 to-100 meshes, and storing in a closed silo; then weighing ingredients, weighing the fine powder mixture of the raw ores accounting for 78.5 percent of the total amount, weighing microorganism bacteria-lactobacillus and saccharomycetes (the concentration of which is 1 multiplied by 10 ⁸/mL) (the ratio of the two bacteria is 1:1), weighing microorganism nutrient agents-wheat flour and rice flour (1:1) accounting for 0.6 percent of the total amount, and weighing organic adhesive-potato starch and sweet potato starch and molasses (1:1:1) accounting for 4.1 percent of the total amount; the total mixture of the metal aluminum accounts for 9.60 percent; the silicon carbide accounts for 3.1% of the total mixture; the carbon-containing material-graphite accounts for 3.3% of the total mixture; adding proper amount of anhydrous vegetable oil and corn oil accounting for 2.1% of the total amount of the mixture, stirring and mixing uniformly by a turntable mixer and a powerful mixer, extruding into balls by a pair of rollers, and pressing into granular balls (the granularity is equal to that of the embodiment 1). Stacking the pressed granular balls for 1.5 days in an environment with the humidity of 56% at the temperature of 43.6 ℃, placing the processed granular balls into a microwave heating furnace, and keeping the temperature of 100 ℃ for 12 minutes to kill microorganism bacteria, wherein the residual porous balls are LF refined slag. The density of the refining slag is 2.6 tons/cubic meter, the melting point is 1267 ℃, and the void ratio is 35.2%;

Refining and slagging are carried out in an LF furnace with nominal capacity of 150 tons, and the incoming molten steel comprises the following components: c0.003%, si0.03%, mn0.16%, P0.0015%, S0.036% and Al _S 0.036.036 are used for refining 6.5-7.0Kg/t steel of the refining slag, the smelting period is 31 minutes, and the final slag is: caO:42.12%, siO ₂:23.26％,Al₂O₃:26.3%, mgO:7.76%, TFe:0.48%, the ingredients of the outgoing LF refining station are as follows: c=0.004%, p=0.0011%, s=0.0003%, o=0.0010%, al _S＝ 0.032.032%, h=0.0002%, n=0.0015%, B class and D class inclusions less than 0.5 level, and the desulfurization rate reaches 99.17%.

Comparative example 2

Compared with example 2, the same furnace and the same batch of molten iron as in example 2 were smelted in the same converter, and the charging amount of the converter was substantially the same as in example 2. For the adjacent smelting times of the embodiment, the smelting operation is basically the same as the embodiment, except that the LF refining slag adopts the conventional quicklime, calcium carbide, fluorite, carbon powder and aluminum particles to carry out LF foam slag, the lime addition amount is 13 Kg/ton of steel, the calcium carbide is 1.81Kg/t, the fluorite is 1.65Kg/t, the carbon powder is 2.8Kg/t, the aluminum particles are 2.81Kg/t, and the incoming molten steel comprises the following components: c0.006%, si0.030%, mn0.18%, P0.0018%, S0.033%, refining period 45 minutes, final slag binary basicity r=3.55, tfe=0.76%, and LF outbound molten steel composition: c=0.0084%, si0.08%, mn0.21%, p=0.0024%, s=0.0075%, o=0.0032, n=0.0045%, h= 0.00043%, B-class and D-class inclusions in steel are at 1.0-1.5 level, and desulfurization rate is 77.27%. The smelting period is prolonged by 45.16%, the slag consumption is increased by more than 2 times, and the TFe content in the slag is increased by 0.28%.

Example 3

Selecting limestone raw ore with 98% of the content of the limestone subjected to the heavy selection and impurity removal, wherein the limestone raw ore accounts for 70.1% of the total mixture of the raw ore; bauxite with 93 percent of Al ₂O₃ content accounts for 21.3 percent of the total mixture of raw ores; dolomite raw ore with the dolomite content of 98.0 percent accounts for 3.1 percent of the total mixture of raw ore; potassium feldspar raw ore with the potassium feldspar content of 98 percent accounts for 4.1 percent of the total mixture of the raw ore; coal with 0.083% of S, 0.076% of P and 1.4% of active carbon C=97% of total mixture of raw ores is accurately weighed, then added into a ball mill for grinding, the mixture is ground into fine powder of-200 meshes to-220 meshes, and then the fine powder is placed into an intermediate storage bin or a storage tank for storage; processing metal aluminum with the aluminum content of 99% into powder with the granularity of-90 to-100 meshes, and storing the powder in a closed storage tank; processing silicon carbide material with the SiC content of 92% into powder with the granularity of-80 to-100 meshes, and storing the powder in a closed storage bin; processing graphite with 93% C content into powder with granularity of-80 to-100 meshes, and storing in a closed silo; then weighing and proportioning, weighing the raw ore fine powder mixture accounting for 75.3 percent of the total material, weighing microorganism bacteria-lactobacillus and bifidobacterium accounting for 1.4 percent of the total material, wherein the concentration of the microorganism bacteria-lactobacillus and bifidobacterium is 1 multiplied by 10 ⁸/mL, (the ratio of the two bacteria is 1:1), weighing microorganism nutrient agents-wheat flour and potato flour accounting for 1.3 percent of the total material (1:1), and weighing organic adhesive-potato starch and sweet potato starch and molasses accounting for 2.5 percent of the total material (1:1:1); the content of the metal aluminum in the mixture is 5.3 percent; silicon carbide accounts for 8.6% of the mixture; the content of the carbon-containing material-graphite powder in the mixture is 5.6 percent; adding proper amount of anhydrous vegetable oil and corn oil accounting for 2.1% of the total amount of the mixture, stirring and mixing uniformly by a turntable mixing machine and a powerful mixing machine, and pressing into blocks by an isostatic pressing machine. And (3) stacking for 2 days in an environment with the humidity of 43% at the temperature of 26 ℃, placing the processed blocks into a microwave heating furnace, and keeping the temperature of 128 ℃ for 1.8 minutes to kill microorganism bacteria and obtain the residual porous blocks which are LF refining slag. The density of the refining slag is 3.75 tons/cubic meter, the melting point is 1317 ℃, the porosity is 25.3 percent of granularity: 25X35X30mm accounts for 93%;

Example 4

Selecting limestone raw ore with 98% of the content of the limestone subjected to the heavy selection and impurity removal, wherein the limestone raw ore accounts for 65.3% of the total mixture of the raw ore; bauxite with the Al ₂O₃ content of 95 percent accounts for 25.2 percent of the total mixture of the raw ores; dolomite raw ore with the dolomite content of 98.0 percent accounts for 2.1 percent of the total mixture of raw ore; potassium feldspar raw ore with 97 percent of potassium feldspar content accounts for 4.8 percent of the total mixture of the raw ore; coal with 0.083% of S, 0.076% of P and 2.6% of active carbon C=95% of total mixture of raw ores is accurately weighed, then added into a ball mill for grinding, the mixture is ground into fine powder of-220 meshes to-240 meshes, and then the fine powder is placed into an intermediate storage bin or a storage tank for storage; processing metal aluminum with the aluminum content of 99% into powder with the granularity of-90 to-100 meshes, and storing the powder in a closed storage tank; processing silicon carbide material with the SiC content of 92% into powder with the granularity of-80 to-100 meshes, and storing the powder in a closed storage bin; processing graphite with 93% C content into powder with granularity of-80 to-100 meshes, and storing in a closed silo; then weighing and proportioning, weighing the raw ore fine powder mixture accounting for 66.2% of the total material, weighing microorganism bacteria-bifidobacterium and saccharomycetes accounting for 0.70% of the total material, wherein the concentration of the microorganism bacteria-bifidobacterium and saccharomycetes is 1 multiplied by 10 ⁸/mL, (the ratio of the two bacteria is 1:1), weighing microorganism nutrient-sweet potato powder and rice powder accounting for 0.8% of the total material (1:1), and weighing organic adhesive-organic asphalt and sweet potato starch accounting for 8.8% of the total material (1:1); the content of the metal aluminum in the mixture is 9.0%; silicon carbide accounts for 8.5% of the mixture; the content of the carbon-containing material, namely the sulfur-removed petroleum coke and the graphite powder (1:1), in the mixture is 6.0 percent; adding proper amount of anhydrous peanut oil accounting for 1.6% of the total amount of the mixture, stirring and mixing uniformly by a turntable mixer and a powerful mixer, extruding into balls by a pair of rollers, and pressing into granular balls. Stacking the pressed granular balls for 3 days in an environment with the humidity of 36% at the temperature of 18 ℃, placing the processed granular balls (the granularity is equivalent to that of the embodiment 1) into a microwave heating furnace, keeping the temperature of 103 ℃ for 6 minutes, and killing microorganism bacteria to obtain the residual porous pellets which are LF refining slag. The density of the refining slag is 3.66 tons/cubic meter, the melting point is 1325 ℃, and the porosity is 22.1%.

Example 5

Selecting limestone raw ore with 98% of the content of the limestone subjected to the heavy selection and impurity removal, wherein the limestone raw ore accounts for 60.4% of the total mixture of the raw ore; bauxite with the Al ₂O₃ content of 95 percent accounts for 23.1 percent of the total mixture of the raw ores; dolomite raw ore with the dolomite content of 98.0 percent accounts for 6.8 percent of the total mixture of the raw ore; potassium feldspar raw ore with the potassium feldspar content of 96 percent accounts for 8.4 percent of the total mixture of the raw ore; coal with S of 0.081%, P of 0.073% and active carbon C=95% accounting for 1.3% of the total mixture of raw ores is accurately weighed, then added into a ball mill for grinding, the mixture is ground into fine powder of-200 meshes to-220 meshes, and then the fine powder is placed into an intermediate storage bin or a storage tank for storage; processing metal aluminum with the aluminum content of 99% into powder with the granularity of-90 to-100 meshes, and storing the powder in a closed storage tank; processing silicon carbide material with the SiC content of 92% into powder with the granularity of-80 to-100 meshes, and storing the powder in a closed storage bin; processing graphite with 93% C content into powder with granularity of-80 to-100 meshes, and storing in a closed silo; then weighing ingredients, weighing the raw ore fine powder mixture accounting for 78.7 percent of the total amount, weighing microorganism bacteria-lactobacillus accounting for 0.6 percent of the total amount, wherein the concentration is 1X 10 ⁸/mL, weighing microorganism nutrient agents-potato powder and rice powder (1:1) accounting for 0.90 percent of the total amount, and weighing organic adhesive-organic silicone oil and sweet potato starch (1:1) accounting for 4.5 percent of the total amount; the metal aluminum accounts for 7.6% of the mixture; the silicon carbide accounts for 3.2% of the mixture; the carbon-containing material-graphite accounts for 4.5% of the total amount of the mixture, a proper amount of anhydrous rapeseed oil accounts for 4.5% of the total amount of the mixture, and after being stirred and mixed uniformly by a turntable mixer and a powerful mixer, the mixture is extruded into pellets by a pair of rollers and pressed into pellets (the granularity is equivalent to that of the embodiment 1). Stacking the pressed granular balls for 2 days in an environment with the humidity of 80% at the temperature of 25 ℃, placing the processed granular balls into a microwave heating furnace, and keeping the temperature of 100 ℃ for 5 minutes to kill microorganism bacteria, wherein the residual porous balls are LF refining slag. The density of the refining slag is 2.9 tons/cubic meter, the melting point is 1236 ℃, and the porosity is 32.4%.

Claims

1. A preparation method of LF refining slag by microorganism treatment is characterized by comprising the following steps: the method comprises the following steps:

2. The method of manufacturing according to claim 1, characterized in that: in the first step, 60-76% of raw limestone, 18-30% of bauxite, 2-8% of dolomite, 1-10% of potassium feldspar and 1-3% of carbon-containing mineral in raw ore mixture of raw limestone, bauxite, dolomite, potassium feldspar and carbon-containing mineral; in the second step, the raw ore powder obtained in the first step accounts for 65-87% of the total mixture; the microbial bacteria accounts for 0.6 to 1.5 percent of the total mixture; the microbial nutrient accounts for 0.5 to 1.3 percent of the total mixture; the organic adhesive accounts for 1-9% of the total mixture; the metal aluminum accounts for 2-10% of the total mixture; the silicon carbide accounts for 2-9% of the total mixture; the carbon-containing material accounts for 2-6% of the total mixture.

3. The preparation method according to claim 1 or 2, wherein the limestone content in the raw limestone ore after the impurity removal by the reselection is more than 95%; the Al ₂O₃ content in the bauxite is more than 90 percent; the content of dolomite in the dolomite raw ore is more than 95 percent; the content of potassium feldspar in the potassium feldspar raw ore is more than 95 percent; the carbon-containing minerals are low sulfur, S is less than or equal to 0.1 percent, phosphorus is less than or equal to 0.1 percent, and the content of activated carbon is more than or equal to 90 percent, such as coal or graphite ore and other carbonaceous raw materials; the powdery metal aluminum is processed by metal aluminum with aluminum content more than or equal to 98.5 percent; the SiC content in the silicon carbide is more than 90 percent; the carbonaceous material comprises: graphite with carbon content more than or equal to 90%, waste electrode powder, low sulfur, S less than or equal to 0.1%, low phosphorus, P less than or equal to 0.1% and other materials;

the microbial nutritional agent comprises: at least one of corn flour, rice flour, potato and sweet potato flour;

the organic adhesive is at least one of sugar manufacturing slag, honey, organic silicone oil, corn or potato or sweet potato starch, organic asphalt and other organic adhesives; the vegetable oil comprises at least one of rapeseed oil, corn oil and peanut oil.

4. The production method according to claim 1 or 2, wherein the microorganism comprises: at least one of yeast, lactobacillus and bifidobacterium is preferably not less than 1×10 ⁸/mL.

5. The method of any one of claims 1-4, wherein:

step two, raw ore powder with the meshes of-180 to-240, microorganism bacteria, microorganism nutrient, organic adhesive, metal aluminum powder, carbon-containing material powder and silicon carbide powder are proportioned, vegetable oil is added, uniformly mixed and then extruded for forming.

6. The method of any one of claims 1-5, wherein: step three, the pressed extrusion molding is cured for 1 to 4 days at the ambient temperature of 0 to 45 ℃ and the humidity of 30 to 80 percent, and micro-organisms engulf carbon or organic matters in the extrusion molding to form fine and porous holes inside;

7. The LF refinery slag produced by the method of any one of claims 1-6.

8. The LF refinery slag of claim 7 wherein: density 2.5-3.8 tons/cubic meter, melting point 1230-1330 deg.C, porosity 20-36%, granularity: 15-50mm accounts for more than 90%, preferably rectangular or square blocks with a particle size of length (15-50 mm) x width (10-40 mm) x height (10-40 mm); when CaO/SiO ₂ = 1.8-3.0, the sulfur content in the molten steel is reduced to below 0.0003%, and the desulfurization rate is more than 90%; the total content of impurity elements in the steel [ O ] + [ S ] + [ H ] + [ N ] + [ P ] is less than or equal to 0.0050%; the class D and class B inclusions are less than or equal to 0.5 level.

9. Use of the LF refinery slag prepared by the method of claim 7 or 8 in a secondary refining process of molten steel, especially in a LF furnace refining.