CN113699312A - Product and method for direct alloying of molten steel - Google Patents
Product and method for direct alloying of molten steel Download PDFInfo
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- CN113699312A CN113699312A CN202111023803.5A CN202111023803A CN113699312A CN 113699312 A CN113699312 A CN 113699312A CN 202111023803 A CN202111023803 A CN 202111023803A CN 113699312 A CN113699312 A CN 113699312A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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Abstract
The invention discloses a product and a method for directly alloying molten steel, belonging to the technical field of metallurgy. The invention mixes the fine powder of alloying element compound with fine powder of dispersant, etc. to be made into packing monomer product, before or at the beginning of tapping, it is added into steel ladle, and the direct alloying element metallization process is completed in the alloying compound under the condition of iron bath with good thermodynamic and dynamic factors in the early stage of tapping by the superposition and promotion of deoxidizer used in normal deoxidation alloying of a large amount of molten steel and alloying finished alloy material of other elements added at the same time, thus realizing the direct alloying of molten steel by adopting the alloying compound. After the product is added into the steel ladle at one time according to the method, no additional related auxiliary facilities or additional auxiliary operations are needed in the direct alloying process of the molten steel.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a product and a method for directly alloying molten steel.
Background
The process for alloying molten steel by adding alloy element compounds (mainly alloy element oxides) into a steel ladle directly removes the production process of finished ferroalloy with high energy consumption and strong pollution, has negative influence indexes in various aspects of related resource consumption, energy consumption, environmental pollution, occupational hazards and the like which are greatly superior to those of the traditional process for alloying liquid metals such as molten steel by using the finished ferroalloy, and is an important improvement direction of the liquid metal alloying process in which metallurgy workers are dedicated to research and development and make a great deal of attempts in the last seventy years.
In recent years, there have been some reports of tests and trial production of special steels containing tungsten, molybdenum, chromium, manganese or vanadium, etc. which are directly alloyed with oxides of the corresponding elements during tapping or refining, and some researchers have made detailed summaries, such as mr. jorge Madias, Metallurgical engineering, Director, metallon, San Nicolas, Buenos Aires, Argentina Technical distribution to the 49 ° semi de ariaria, part of the ABM Week, October 2nd-4th,2018,
paulo, SP, Brazil, entitled: a Review of Plant Experiences and Lab students carries out systematic induction, but although the advantages of directly Alloying molten Steel by adopting alloy element compounds are many, a plurality of methods and achievements also appear in the long-term research and development process, the popularization and application in the actual large industrial production are few, and the Direct Alloying of molten Steel by adopting the alloy element compounds is still restricted by the following problems:
1. most of the existing trial methods adopt the steps of adding alloy element oxides and reducing agents with corresponding amount into molten steel after being made into blocks, wherein the metallization reaction is carried out in the molten steel and a molten slag system thereof in an open manner, and because the molten steel contains higher oxygen, the loss of the added reducing agents is very large, the reaction environment and conditions of direct alloying are very unstable, the metallization degree of elements is poor, the alloy reduction rate is not high, and the fluctuation is large;
2. in the prior trial method, after the alloy element oxide enters the molten steel, the reduction reaction process is microcosmically mainly the solid-solid reaction of the direct alloying element compound and the reducing agent in the block body, or the melting reduction reaction of the direct alloying compound and the reducing agent after the direct alloying compound enters the slag in the furnace (ladle), the thermodynamic condition and the kinetic condition of the reaction are poor, and the efficiency is low;
3. the alloy element oxidation material block used for direct alloying in the prior direct alloying trial method has higher strength, floats on the surface of molten steel due to the density difference with the molten steel after being added into the molten steel, and is easy to enter scum to generate slagging because the scum is not quantitatively controlled, and is difficult to be reduced again to generate loss;
4. the prior trial method mostly adopts the method of adding the direct reduction element compound into a furnace for smelting reduction or a certain smelting reduction process, the required reduction process time is long, corresponding metallurgical equipment is used, the operation is complicated and fussy, and the increasingly high-efficiency steelmaking production requirement cannot be met;
5. there have been no attempts to systematically and normatively utilize and reduce the reduction of the directly bonded alloying element compounds by means of the existing deoxidizer and other alloying elements of the molten steel.
Disclosure of Invention
1. Problems to be solved
The invention aims to overcome the problems of complex and complicated solid-solid reduction or smelting reduction process operation, low reduction efficiency, poor stability and the like in the method for directly alloying the molten steel by adopting the compound in the prior art, and provides a product and a method for promoting and realizing the instant high-efficiency alloying of the directly alloyed compound to the molten steel in the early stage of tapping by adopting a direct microcosmic solid-liquid reaction design and by means of and utilizing the original alloying materials of the deoxidizer and other elements in the molten steel. By adopting the technical scheme of the invention, the alloying of the molten steel can be rapidly completed at the same time of normal tapping without any subsequent auxiliary process, so that the finished ferroalloy product is replaced by one step, and the instant direct alloying of the molten steel by the compound is realized.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention relates to a product for directly alloying molten steel, which is a blocky structure or a packaging monomer formed by mixing natural or concentrated and primarily purified compound powder serving as a direct alloying element source with dispersant powder.
Further, the compound powder is selected from at least one of oxides or salts containing tungsten, molybdenum, cobalt, niobium, chromium, boron, tantalum and vanadium, and direct alloying of more than one element can be carried out simultaneously.
Furthermore, when the product is made into a monomer by adopting a compression molding method, a proper bonding agent is required to be added into the product.
Furthermore, the dispersing agent has the functions of isolating the direct alloying materials and promoting the material monomers to be disintegrated and dispersed as soon as possible after being added into the molten steel, and the weight ratio of the dispersing agent to the direct alloying compound powder is 0-0.2.
Furthermore, the dispersing agent adopts a combination reaction gas forming material and/or a decomposition reaction gas forming material and the like.
Further, the combination reaction type gas generating material includes carbon and the like, and the decomposition reaction type gas generating material includes carbonate, metal nitride, alkaline earth metal hydroxide and the like.
Furthermore, the dispersant may also function as a reducing agent for direct metalation of the alloying element compound. For example, metallic silicon in carbon or silicon nitride in which the metallization reaction is a reduction reaction.
Furthermore, when the inherent deoxidizer of the molten steel or the alloying materials of other elements already contain the reducing agent required by the direct alloying of the molten steel, the reducing agent does not need to be added into the product; when the inherent deoxidizer of the molten steel and other alloying materials do not contain or only contain insufficient amount of the reducing agent required for the direct alloying of the molten steel, the reducing agent is added in the product in full amount in combination with the reducing capability of the dispersing agent.
The invention relates to a method for directly alloying molten steel, 1) for a thermal decomposition type directly alloying element compound of which a decomposition product is not expected to enter the molten steel, the product is added into a steel ladle in advance before steel tapping, and then all or part of deoxidizer, other alloy and supplementary reducing agent for inherent alloying of the molten steel are added into the steel ladle at the beginning of the steel tapping. When alloying molten steel, a deoxidizer, other alloys and a reducing agent are required to be added, the product can fully utilize materials which are required to be added into the molten steel originally to alloy target direct alloying elements, no addition is required in the product, and the method is undoubtedly the most economic from the perspective of production cost.
Or 2) for the thermal decomposition type direct alloying element compound and other type of direct alloying element compound whose decomposition product is desired to enter the molten steel, adding all or part of a deoxidizer, other alloy and a supplementary reducing agent for the inherent alloying of the molten steel into the ladle before or at the start of tapping, and also adding the above products into the ladle at the same time as the start of tapping.
Furthermore, the supplementary reducing agent is a reducing material supplementary part which is added into the dispersing agent but is not enough to fully reduce the direct alloying element part by utilizing one or more deoxidizing alloying materials of original other elements of the molten steel, and is added into the steel ladle together with other existing deoxidizing alloying materials at the same time in the early stage of the tapping process.
Furthermore, the supplementary reducing agent is used for repaying the consumed molten steel inherent deoxidation and alloying materials of the direct alloying material. The total oxygen combined by the supplementary reducing agent, the reducing agent in the product and the deoxidizing element in the dispersing agent is balanced with the total oxygen combined by the target element and all elements of which the oxygen binding force is weaker than that of the target element in the direct alloying element compound.
Furthermore, the reduction of the direct alloying elements in the direct alloying compounds of the molten steel in the invention is mainly completed under the condition of iron bath at the beginning stage of the tapping process by simultaneously adding 1) the existing deoxidizer of the molten steel, 2) the alloy material of other elements with the original existing oxygen bonding force stronger than the direct alloying elements of the molten steel and 3) the supplementary reducing agent into the tapping ladle.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention relates to a product for directly alloying molten steel, which adopts natural or concentrated enriched and primarily purified compound powder as a direct alloying element source, evenly mixes dispersant powder, presses or encapsulates the mixture into a packaging monomer, and adds the packaging monomer into a steel ladle once to realize the direct alloying of the molten steel. Meanwhile, the product of the invention reduces the direct alloying element compound by means of deoxidation in the molten steel in the early stage of tapping and under the condition of large relative concentration of deoxidation alloying elements such as carbon, silicon, aluminum and the like, the thermodynamics and the kinetic conditions of the reduction reaction are good, and the problems of slow slag melting and dissolution of high-melting point compounds, poor thermodynamics conditions of melting reduction, poor overall reduction kinetic conditions and the like in all previous attempts are solved, so that the metallization degree is higher, the time of the direct alloying process is short, and the metal yield is higher and stable. In addition, it should be noted that a reducing agent may be added to the product, but from the viewpoint of optimizing the alloying cost, it is most economical to complete the alloying process of the target direct alloying element by using a material having reducing property added at the time of the alloying treatment of the non-target element in the molten steel.
(2) According to the product for directly alloying the molten steel, the dispersing agent is added, the dispersing agent adopts high-melting-point reduction reaction gas generation or decomposition gas generation material fine powder and the like such as carbon, and the like, so that when the product is added into the molten steel, the direct alloying element compound fine powder can be effectively isolated and prevented from agglomerating after being added into the molten steel, and the disintegration and dispersion of a block body after being added into the molten steel are promoted, so that a high-temperature state favorable for metallization reaction can be instantly achieved. Meanwhile, the dispersant can be selected to have the function of a reducing agent of a direct alloying element compound.
(3) The invention relates to a method for directly alloying molten steel, which is characterized in that under the condition of small amount of molten steel in a ladle at the initial stage of tapping, the product of the invention is added, the characteristic that the floating substances on the surface of the molten steel and the molten steel are circularly mixed by the molten steel is utilized by the good stirring generated by the strong kinetic energy of the early stage of the tapping process and the slag and the tapping steel flow, and the metallization of target alloying elements is directly carried out in the molten steel basically without the influence of scum under the condition that the concentration of various reactants contained in the reducing agent supplemented by the existing deoxidizer, other alloys and direct alloying elements in the molten steel is in a higher level, so that the metal yield of the target alloying elements is effectively improved, and the fluctuation of the yield is small.
(4) According to the method for directly alloying the molten steel, after the product is added at one time, no additional related auxiliary facilities or additional auxiliary operations are needed, the operation of directly alloying the molten steel is simple and convenient, and the application and popularization of directly alloying the compound molten steel become possible. In addition, compared with the common method of finished ferroalloy adopted in the industry at present, the direct alloying of the compound shortens the reduction path to a great extent, protects resources, reduces pollution and energy consumption, and has great economic and social benefits.
Detailed Description
The method aims to solve the defects of the direct alloying treatment process for the molten steel recorded in the background technology. The invention provides a molten steel direct alloying product and a method, which promote the metallization of direct alloying element compounds to be fully carried out in time by designing the alloying reaction process into a solid-liquid reaction type, utilizing the original deoxidation and other element alloying materials of the molten steel, and utilizing the powerful stirring of the molten steel and the real-time dissolution of the metallized direct alloying elements.
Specifically, the product of the invention adopts natural or selected enriched and primarily purified compound powder as a direct alloying element source, and the dispersant powder is uniformly mixed and then pressed or packaged into a packaging monomer, wherein the particle size of the filled material is not more than 400 mu m. The compound used as the direct alloying element source is mainly at least one of compounds of elements such as tungsten, molybdenum, cobalt, niobium, chromium, boron, tantalum, vanadium and the like, the bonding capacity of which with oxygen at the temperature of molten steel is smaller than that of metallic silicon and carbon. The dispersing agent adopts a combination reaction type gas generating material and/or a decomposition reaction type gas generating material, wherein the combination reaction type gas generating material adopts carbon; the decomposition reaction type gas generating material comprises carbonate, metal nitride and alkaline earth metal hydroxide. The addition of the dispersing agent plays a certain role in isolation, can effectively prevent the direct alloying element compound fine powder from agglomerating after being added into the molten steel, and promotes the disintegration and dispersion of the block after being added into the molten steel. More preferably, if the added dispersing agent can have the functions of a reducing agent or a bulk bonding agent of the direct alloying element compound, the dispersing agent can also replace the addition of other reducing agents or bonding agents when manufacturing products.
It should be noted that when the product is made into a single body by compression molding, a proper amount of binder and dispersant need to be added into the product, and when the product is directly packaged into a single package, no binder needs to be added. Meanwhile, when the direct alloying element (target alloying element) source selected in the product has the function of the dispersant, no dispersant or a small amount of dispersant can be added in the product.
More optimally, the following two specific situations exist for whether the reducing agent is added to the product:
(1) from the perspective of optimal cost, when the inherent deoxidizer of the molten steel or the alloying materials of other elements already contain the reducing agent which is intended to be used for directly alloying the molten steel, the product does not need to be added with the reducing agent, and when the inherent alloying treatment is carried out on the molten steel in the actual production, the added deoxidizer and/or the reducing agent used for reducing the alloying materials of other elements can be subjected to the increment treatment.
(2) When the inherent deoxidizer of the molten steel and other alloying materials do not contain or only contain insufficient amount of reducing agent which is required to be used for directly alloying the molten steel, the sufficient reducing agent is added into the product by combining the reducing capability of the dispersing agent so as to ensure the alloying effect of the direct alloying elements.
From the viewpoint of the amount of the reducing agent to be added and the reducing function of the dispersant itself, the total oxygen amount of the deoxidizing elements in the reducing agent and the dispersant is represented as n1The total oxygen content bound in the target element and all elements having a lower binding force with oxygen than the target element in the direct alloying element compound is represented as n2Then n is1And n2The molar ratio of (A) should satisfy the range of 0 to 1.0.
In addition, a proper amount of reducing agent can be added to the product according to actual needs or personal thoughts, but materials required for alloying other elements inherent to molten steel (these materials can be used as alloying treatment for the target alloying element) should be utilized as much as possible from the viewpoint of economic cost optimization. Because of this, it is most economical both from the production cost, the packaging cost and from the transport cost.
According to the method for directly alloying the molten steel, two modes of directly alloying materials added into a steel ladle can be selected according to the influence of the metallization reaction product of the compound of the directly alloying element on the molten steel.
The first method is as follows: in the case of a thermal decomposition type direct alloying element compound, particularly in the case where the decomposition product thereof is not desired to enter molten steel, the product of the present invention is previously charged into a ladle while waiting for tapping, and then all or part of a deoxidizer, other alloy and a supplementary reducing agent for inherent alloying of molten steel are charged into the ladle at the time of starting tapping.
The second method is as follows: in the case where it is desired to introduce the direct alloying element compound reduction product into the molten steel, all or part of a deoxidizer, other alloy and a supplementary reducing agent for inherent alloying of the molten steel are added to the ladle before tapping or at the start of tapping, and the product of the present invention is added at the start of tapping.
More optimally, for the supplementary reducing agent of the added direct alloying element compound, one or more deoxidation alloying materials required by other elements in the molten steel can be used as the supplementary reducing agent of the direct alloying element compound, so that the total oxygen combined by the elements in the supplementary reducing agent and the dispersing agent is balanced with the total oxygen combined by the target element and all elements with the oxygen bonding force weaker than that of the target element in the direct alloying element compound.
The selection of the type of the supplementary reducing agent needs to be designed and selected according to the specific requirements on recarburization, temperature control, additional slag amount and slag characteristic control in the direct alloying process of different steel types, and the proportion relation between carbon and metal in the supplementary reducing agent meets 100% -0%: 0% -100%, that is, the supplementary reducing agent can adopt one or the combination of two of carbon or metal.
In addition, the alloying reaction process of the direct alloying element compound simultaneously takes the help of 1) molten steel deoxidation, and in the initial tapping period, other element alloying materials and the added direct alloying element supplement reducing agent are completely (or mostly) added into a small amount of molten steel in a steel ladle and melted (or dissolved) to form a condition with higher concentration; 2) in the beginning stage of tapping, the steel flow falls down to intensively stir a small amount of molten steel which is rich in deoxidized alloying materials and mixed with direct alloying compound materials in a steel ladle, and alloying elements and alloying processes are immediately completed under the condition of iron bath with little slag in the initial stage of tapping.
The basic principle and the design idea of the invention are as follows: firstly, the following advantages are obtained in terms of reaction thermodynamics: 1) by utilizing and utilizing the alloy materials of the existing deoxidation and other element alloying of the molten steel with a relatively larger quantity, when only a small amount of molten steel exists in the initial tapping stage, the concentration of various deoxidation alloying elements is in a higher level, and then the element metallization of alloying element compounds is directly carried out, the reaction conditions are relatively sufficient and stable, and the method is favorable for improving and stabilizing the yield of direct alloying elements; 2) by utilizing the action of the dispersing agent, the direct alloying material block is disintegrated and dispersed at the beginning when contacting the molten steel and is wrapped by the molten steel, and a high-temperature state which is favorable for the metallization reaction of the direct alloying element compound is instantly achieved; 3) by utilizing the characteristic that molten steel and various possible direct alloying elements can form high-temperature solid solution, good conditions for consuming reaction products in real time and promoting the reaction depth are formed.
Secondly, in terms of dynamics, the following advantages are provided: 1) the amount of molten steel in a steel ladle is small in the initial tapping stage, and the concentrations of various reactants contained in the reducing agent supplemented by the added direct alloying materials and the molten steel, namely all deoxidizers, other alloys and direct alloying elements, are highest; 2) the liquid level of the molten steel in the steel ladle at the initial tapping stage is low, so that the drop of the molten steel flow is large, and meanwhile, the liquid level of the molten steel in the furnace is deep, and the stirring kinetic energy of the molten steel in the steel ladle by the molten steel flow is very high under the conversion of the superposed potential energy; 3) the amount of molten steel in a steel ladle is small in the initial tapping period, the molten steel added with direct alloying materials and the molten steel with the existing deoxidizer, other alloying materials and direct alloying elements to supplement the reducer has high flowing disorder degree due to the powerful stirring of the tapped molten steel, the contained substances are fully mixed and have high circulation rate, the direct alloying element metallization reactant and the reaction product in the molten steel diffuse in a reaction interface along with the flowing of the molten steel in time and exchange is rapid, and the mass transfer condition of the reaction is excellent; 4) under the action of the dispersing agent, the direct alloying material block is disintegrated and dispersed at the beginning when contacting the molten steel, and the contact specific surface area of various reaction materials wrapped in the molten steel is large, thereby being beneficial to rapid implementation of metallization reaction.
Finally, in terms of reaction engineering, the following advantages are achieved:
1) under the condition of iron bath, the total amount of the direct alloying element compound of the direct alloying element metallization reactant is X and the concentration (set as Xc), the concentration (set as yci) of a certain deoxidizer or alloy element Yi serving as a reactant is set, the amount of molten steel in the steel ladle is Q, Xc is X/Q or yci is Yi/Q, and the product Xc yic or (Xc) n (yic) m (m and n are the balancing coefficients of reactants in the corresponding reaction formula) is the chemical potential for promoting the direct alloying element metallization reaction to progress. The chemical potential at which the reaction proceeds decreases with the increase in the quantity of molten steel in the ladle during tapping, and it is obviously necessary to add more reactants to the ladle before tapping and as early as possible as the tapping begins, in order to obtain as early as possible the chemical potential of the metallization reaction of the compounds of the direct alloying elements, it being preferable in practice to add all the relevant deoxidation alloying substances before the tapping reaches 10%.
2) Generally, before tapping is completed, dross in a ladle is mainly composed of deoxidized product slag of high-oxygen content molten steel flowing into the ladle from a steel making furnace, and increases as the molten steel in the furnace continuously enters the ladle. In the initial tapping stage, because the total amount of molten steel in the steel ladle is less, corresponding molten steel deoxidation products are less, so that the loss amount of the added direct alloying element compounds which are melted by scum and are subjected to slagging is reduced, and under the strong stirring of the tapping steel flow, a small amount of direct alloying element compounds can be subjected to slagging, enter the scum, are repeatedly crushed by the molten steel and are involved into the molten steel, and continuously react with the deoxidation alloying elements in the molten steel to form metal which is dissolved in the molten steel, so that the relatively low loss rate of the direct alloying elements is ensured;
3) compared with the direct alloying process of solid-solid reaction or solid-liquid reaction of heating and melting of reactants, which is mainly designed to be carried out in the melting reduction or reactant mixing briquetting, the metallization of direct reduction elements in the initial tapping stage can realize the whole solid-liquid reaction system with high concentration, high temperature, high mass transfer and high yield, which is formed by all reaction materials and the existing molten steel in a steel ladle by means of the iron bath condition of the molten steel.
The invention is further described with reference to specific examples. It should be noted that, since vanadium is the most strongly bonded element with oxygen among the many elements that can be used in the instant direct alloying of molten steel, the yield of other directly-alloyed elements that are suitable for the direct alloying of vanadium compounds can have the same or better results in theory, especially for those elements whose oxygen bonding force is weaker than that of iron.
Example 1
In this embodiment, vanadium-nitrogen alloying is directly performed on molten steel. Considering that the prior other alloying materials of a steel mill do not contain nitrogen-containing products, a nitrogen increasing agent needs to be added into the direct alloying materials, and the nitrogen increasing agent is selected from silicon iron nitride. Because ammonium metavanadate has a certain dispersion effect due to self ammonia decomposition, and ferrosilicon nitride also has an isolation effect and a reducing agent effect for preventing material agglomeration, ammonium metavanadate with the purity of 98% is used as a vanadium source, 79% ferrosilicon nitride is used as a supplementary nitrogen source and a dispersing agent, the ammonium metavanadate and the ferrosilicon nitride are uniformly mixed according to the proportion of 10:2, then are packaged, and the molar ratio of silicon in the ferrosilicon nitride to vanadium-combined oxygen in the ammonium metavanadate is 0.29, and the total amount of the material is 0.73 kg. The molten steel before tapping of the intermediate frequency furnace comprises 0.15 percent of C, 0.06 percent of Si, the balance of 0.003 percent of V, the basic nitrogen content of 30ppm, the temperature of 1600 ℃ and the total tapping amount of 820 kg. 0.8kg of aluminum, 2.5kg of ferrosilicon, 5.2kg of ferromanganese and 0.24kg of supplementary reduced ferrosilicon for completely balancing and reducing vanadium combined with oxygen elements in vanadium compounds (namely the molar ratio of silicon in the ferrosilicon to vanadium combined with oxygen in ammonium metavanadate is 0.71, namely the total amount of the ferrosilicon is simultaneously added before tapping) which are all available with all deoxidizers and other alloying alloys are added into a casting ladle with the capacity of 1 ton before tapping, and all other operations are not changed. Finally, the components of the steel ladle molten steel are hit, the content of the analyzed steel is 0.031%, and the yield of the alloy elements added into the direct alloying materials is 94.2%; the analysis shows that the nitrogen content in the steel is 116ppm, and the yield of the nitrogen element in the directly-alloyed material is 63 percent.
Example 2
In this example, vanadium is directly alloyed into molten steel. Powdery vanadium pentoxide with the purity of 98 percent is used as a vanadium source, anthracite powder with the fixed carbon content of 88 percent is used as a dispersing agent (the particle sizes of all materials are less than 400 mu m), the mixture ratio is 1:0.15, the molar ratio of carbon to vanadium combined with oxygen in ammonium metavanadate is 0.56, the materials are uniformly mixed and then pressurized and packaged into a miniature monomer carbon steel closed container with the external dimension of approximately 70 x 60 x 80mm and the shell wall thickness of 0.35mm, and the total amount of alloying materials is 25.1kg (together with the gross weight of the shell of the closed reactor is 38.6 kg). When the converter taps steel, all the deoxidizers, carburant carbon powder and direct alloying materials which are originally required by molten steel and 2.95kg of supplementary carbon powder for completely balancing and reducing vanadium in vanadium compounds combined with oxygen are added into a ladle with the capacity of 45 tons in advance through a storage bin, and other alloying materials are added at the same time when tapping starts. The steel liquid tapped from the converter contains 0.004 percent of residual vanadium, the temperature is 1,595 ℃, the total tapping amount is 45 tons, the vanadium content in the steel is finally analyzed to be 0.035 percent, and the yield is 96.0 percent in terms of the alloy elements added into the direct alloying materials.
Example 3
In the embodiment, the medium carbon steel liquid is directly subjected to chromium alloying to replace high carbon ferrochrome. Using Cr2O345% of south African chromite, its iron oxides FeO and Fe2O3The content is 21 percent and 6 percent respectively, anthracite powder with 88 percent of fixed carbon is used as a dispersant with reduction function, and the dispersant is added according to the weight ratio of 10 percent of the chrome ore, namely the ratio of the source compound to the dispersant is 0.1, and the molar ratio of the carbon to the chromium and the iron combined oxygen in the chromite is 0.56. Taking 8.6kg of chromite and 0.86kg of smokelessAfter the coal is mixed uniformly, 0.43kg of sodium silicate binder diluted solution is added and mixed uniformly, the mixture is pressed into a rectangular block with the size of about 40X 30X 50mm, 9.9kg of total alloying material is added before tapping, and a casting hot ladle with the capacity of 1 ton is added for waiting for tapping. The total tapping amount of the intermediate frequency furnace is 810kg, 0.8kg of pure aluminum for molten steel deoxidation alloying, 2kg of ferrosilicon containing 75% of silicon and 0.67kg of ferrosilicon serving as a supplementary reducing agent are added into a steel ladle before tapping, the molten steel components in the intermediate frequency furnace are C0.35%, Si 0.18%, and Cr0.04%, finally C0.38%, Si 0.43% and Cr 0.34% in a steel sample of the steel ladle are analyzed, the yield of alloy elements in direct alloying materials is 90.9%, and the yield level is equivalent to that of finished ferrochrome alloy.
Example 4
The embodiment is used for replacing micro-carbon ferrochrome alloy to carry out direct micro-chromium treatment on low-carbon structural steel liquid. Using Cr2O345% of south African iron ore (its iron oxides FeO and Fe)2O3The contents of which are respectively 21 percent and 6 percent) as a chromium source, calcium carbonate powder is used as a dispersing agent, and no reducing agent material is added (at the moment, the molar ratio of the reducing agent to the chromium and iron combined oxygen in the chromite which is a direct alloying compound is zero). 9.6kg of chromite (2.97 kg of pure chromium element, 1.99kg of total oxygen element combined by iron and chromium), 0.49kg of calcium carbonate powder (dispersant ratio is 0.05) and 0.49kg of sodium silicate binding agent diluted solution are uniformly mixed and pressed into a rectangular block with the size of about 40 x 30 x 50mm, the total amount of alloying materials is 10.5kg, and the rectangular block is added into a casting hot ladle with the capacity of 1 ton before tapping to wait for tapping. The total tapping amount of the intermediate frequency furnace is 900kg, 0.8kg of pure aluminum for molten steel deoxidation alloying, 2kg of ferrosilicon containing 75 percent of silicon and 1.75kg of ferrosilicon containing 75 percent of silicon for corresponding supplementary reducing agent are added into a steel ladle before tapping (at the moment, the molar ratio of the silicon to the chromium and iron combined oxygen in the chromite is 1.0). The compositions of the molten steel sampled in the steel ladle and the intermediate frequency furnace are 0.05 percent of C, 0.05 percent of Si and 0.03 percent of Si, and finally the yield of the alloy elements added into the direct alloying materials in the steel ladle steel sample is 88.7 percent by analyzing 0.06 percent of C, 0.20 percent of Si and 0.29 percent of Cr, which is equivalent to the yield level of the finished micro-carbon ferrochrome alloy.
Example 5
This example is molybdenum alloying of molten steel instead ofInstead of ferro-molybdenum. Roasting molybdenum concentrate (MoO) with Mo content of 53%3) Is a molybdenum source, and adopts calcium oxide and anthracite powder with 88 percent of fixed carbon as a dispersing agent. According to the proportion of 1:0.15:0.05 (the ratio of the dispersing agent is 0.2, the molar ratio of carbon to oxygen in the molybdenum source is 0.27), the mixture is uniformly mixed and then packaged into an iron bucket together, the total amount of alloying materials is 5.2kg, and the alloying materials are added into a casting hot ladle with the capacity of 1 ton before tapping to wait for tapping. The total steel output of the intermediate frequency furnace is 850kg, 0.8kg of pure aluminum, 2.5kg of carburant, 2kg of low-carbon ferrosilicon containing 75% of silicon and 0.9kg of corresponding carbon powder (containing 90%) for supplementing reducing agent are added into a steel ladle for deoxidizing and alloying molten steel when tapping is started, the components of the molten steel in the steel ladle and the intermediate frequency furnace are respectively C0.05%, Si 0.06% and Mo0.03%, finally C0.30%, Si 0.21% and Mo0.32% in a steel sample of the steel ladle are analyzed, the yield of alloy elements added into a direct alloying material is 96.0%, and the level of the alloy elements is equivalent to that of finished ferroalloy.
Example 6
In this example, vanadium is directly alloyed into molten steel. Because ammonium metavanadate has a good dispersing effect in the decomposition of ammonia, 44.8kg of ammonium metavanadate with the purity of 98 percent is only used as a vanadium source, and the ammonium metavanadate is directly bagged without adding a reducing agent and a dispersing agent (namely, the molar ratio of the reducing agent to vanadium-bonded oxygen in the ammonium metavanadate is 0 and the ratio of the dispersing agent is 0). When the converter is tapped and shaken, a ladle with the capacity of 45 tons is put into, and at the beginning of tapping, all other existing deoxidizers, carburant carbon powder and direct alloying materials which are originally required for molten steel and 15.7kg of supplementary carbon powder for completely balancing and reducing vanadium in vanadium compounds combined with oxygen are simultaneously added. The molten steel tapped from the converter contains 0.003 percent of residual vanadium, the temperature is 1,595 ℃, the total tapping amount is 45 tons, the vanadium content in the steel is finally analyzed to be 0.035 percent, and the yield is reduced to 93.5 percent compared with the yield of the alloy elements added into the direct alloying materials.
The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description is to be construed as illustrative only and not restrictive, and any such modifications and variations are intended to be included within the scope of the invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.
Claims (10)
1. A product of direct alloying of molten steel is characterized in that: the block structure or the packaging monomer is formed by mixing natural or refined enriched and primarily purified compound powder serving as a direct alloying element source with dispersant powder.
2. The molten steel direct alloying product of claim 1, wherein: the compound powder is at least one of oxides or salts containing tungsten, molybdenum, cobalt, niobium, chromium, boron, tantalum and vanadium.
3. A molten steel directly alloyed product according to claim 1 or 2, characterized in that: when the inherent deoxidizer of the molten steel or the alloying materials of other elements already contain the reducing agent required by the direct alloying of the molten steel, the product does not need to be added with the reducing agent; when the inherent deoxidizer of the molten steel and other alloying materials do not contain or only contain insufficient reducing agent required for the direct alloying of the molten steel, the reducing agent is added into the product in a sufficient amount in combination with the reducing capability of the dispersing agent.
4. The molten steel direct alloying product of claim 3, wherein: the total oxygen content of the deoxidizer element in the reducing agent and the dispersant is recorded as n1The total oxygen content bound in the target element and all elements having a lower binding force with oxygen than the target element in the direct alloying element compound is represented as n2，n1And n2The molar ratio of (A) to (B) is 0 to 1.0.
5. A molten steel directly alloyed product according to claim 1 or 2, characterized in that: the weight ratio of the dispersing agent to the direct alloying element compound powder is 0-0.2.
6. A molten steel directly alloyed product according to claim 1 or 2, characterized in that: the dispersing agent adopts a combination reaction type gas generating material and/or a decomposition reaction type gas generating material.
7. The molten steel direct alloying product of claim 6, wherein: the chemical combination reaction type gas generating material is carbon; the decomposition reaction type gas generating material comprises carbonate, metal nitride and alkaline earth metal hydroxide.
8. A method for directly alloying molten steel is characterized in that: adding the product of any one of claims 1 to 7 into a steel ladle in advance before waiting for or before tapping, and then adding all or part of deoxidizer, other alloy and supplementary reducing agent for the inherent alloying of molten steel into the steel ladle at the beginning of tapping; or adding all or part of deoxidizer, other alloy and supplementary reducing agent for the inherent alloying of molten steel into the ladle before tapping or at the beginning of tapping, and adding the product of any one of claims 1 to 7 at the beginning of tapping.
9. The method for directly alloying molten steel according to claim 8, wherein: the supplementary reducing agent is used for repaying the inherent deoxidation and alloying materials of the molten steel consumed by the direct alloying materials; the total oxygen combined by the supplementary reducing agent, the reducing agent in the product and the deoxidizing element in the dispersing agent is balanced with the total oxygen combined by the target element and all elements of which the oxygen binding force is weaker than that of the target element in the direct alloying element compound.
10. The method for directly alloying molten steel according to claim 8 or 9, wherein: the reduction of the direct alloying elements in the compound is mainly completed under the condition of iron bath at the initial stage of the tapping process by utilizing and adding 1) the existing deoxidizer of the molten steel, 2) the alloy material of other elements, the original existing oxygen bonding force of the molten steel is stronger than that of the direct alloying elements, and 3) the supplementary reducing agent into a tapping ladle at the same time.
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| GB513853A (en) * | 1938-03-11 | 1939-10-24 | Climax Molybdenum Co | Improvements in or relating to alloying tungsten with ferrous metals |
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| CN103667690A (en) * | 2013-12-16 | 2014-03-26 | 江苏大学 | Chrome-molybdenum metal self reduction pellet and preparation and direct steel liquid alloying methods thereof |
| CN104878159A (en) * | 2015-06-02 | 2015-09-02 | 钢铁研究总院 | Method for increasing yield of molten steel chromium in chromium ore direct-alloying |
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| GB513853A (en) * | 1938-03-11 | 1939-10-24 | Climax Molybdenum Co | Improvements in or relating to alloying tungsten with ferrous metals |
| CN101240360A (en) * | 2008-01-22 | 2008-08-13 | 谢应旭 | Oxide briquetting used for steelmaking alloy element and preparation method thereof |
| CN101302572A (en) * | 2008-06-12 | 2008-11-12 | 鞍钢股份有限公司 | Additive for preparing fine oxide dispersion steel, preparation and use thereof |
| CN103667690A (en) * | 2013-12-16 | 2014-03-26 | 江苏大学 | Chrome-molybdenum metal self reduction pellet and preparation and direct steel liquid alloying methods thereof |
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