Production method of low-carbon molten steel desulfurizing agent

Abstract

The invention discloses a production method of a low-carbon molten steel desulfurizing agent, which comprises the following steps: 1, mixing 40-95 parts by weight of quick lime and 5-50 parts by weight of fluorite serving as raw materials and 5-10 parts by weight of aluminum oxide and 3-5 parts by weight of silicon dioxide serving as auxiliary materials to form a mixed material, and 2, roasting the prepared mixed material in an electromagnetic kiln, 3, pouring the fired mixed material into a collecting device from the electromagnetic kiln, and carrying out next treatment after the mixed material is cooled, and 4, carrying out grinding treatment by adopting a grinding machine with the particle size of 0-1mm, and packaging. In the invention, the electromagnetic kiln is used for production, the production mode is simpler and more convenient, and energy conservation and process stability are realized; common fluorite is used for replacing high-quality fluorite, so that the production cost is reduced; the preparation problem of the low-carbon quick lime is solved, the low-carbon quick lime produced by the method is more stable in quality, and compared with a traditional rotary kiln and smoldering kiln process, the underfiring rate is lower and can be within 0.5%, and fluctuation of the carbon content of the quick lime is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for producing a low-carbon molten steel desulfurizer. Background Art

[0002] CaO-CaF2 slag is widely used in steel refining due to its high sulfur capacity, high activity and high basicity. For steel refining and desulfurization of special steels such as electrical steel and ultra-low carbon steel, the carbon content of the desulfurizer needs to be strictly controlled, otherwise the steel will be "carbonized", and the carbon content of the desulfurizer is often required to be ≤0.2%, or even lower.

[0003] At present, CaO-based desulfurizers for steelmaking are steelmaking auxiliary materials with CaO as the main component and composed of various materials. Functional auxiliary materials include CaF2, Al2O3, CaC2, SiC, Mg, rare earth metals, etc. Among them, CaO plays a major desulfurization role. The more common CaO-based desulfurizers are CaO-CaF2 and CaO-Al2O3, which can be divided into general and low-carbon lime desulfurizers according to the carbon content.

[0004] The general production process of low-carbon lime desulfurizer is as follows: the main raw materials are low-carbon quicklime and low-carbon fluorite, and the other raw materials are all low-carbon raw materials. Various raw materials are made into powder or granular forms as required, and mixed in different proportions to prepare powder or granular or block product desulfurizers for steelmaking desulfurization. Low-carbon quicklime preparation process: limestone is prepared by roasting in a high-temperature kiln. High-temperature kilns generally include vertical kilns (vertical kilns, sleeve kilns, Maerz kilns, etc.), rotary kilns, simple earth kilns, etc. The basic principle is to use the high temperature generated by the combustion of coal, natural gas, coal gas, oil and other fuels or electric heating to decompose limestone into CaO and CO2, thereby obtaining quicklime. In general, due to the incomplete high-temperature decomposition of limestone, quicklime contains a certain amount of undecomposed limestone (greater than 2%, equivalent to a carbon content of more than 0.25%), and low-carbon quicklime (less than 1%, equivalent to a carbon content of less than 0.12%) has a lower carbon content than general quicklime. Preparation process of low-carbon fluorite: select low-carbon fluorite blocks with CaF2 content above 90% for dry grinding or flotation preparation.

[0005] The existing low-carbon molten steel desulfurizer mainly uses low-carbon quicklime and low-carbon fluorite as the main production raw materials. The current production process of the two raw materials is: low-carbon quicklime mainly adopts rotary kiln (coal, fuel oil and gas as heat source), earth kiln smoldering and other production processes, which have the problems of high process control difficulty, large fluctuation of quicklime raw and over-burning, extensive production method, high energy consumption and large pollution. The main reasons for roasting low-carbon quicklime using the above-mentioned high-temperature kiln are: first, the use of fuel combustion kiln, because the fuel combustion will produce a large amount of CO2, high-temperature gas and other waste gas emissions, which is more than 2 times higher than the waste gas generated by electric heating, and the roasting time is long; second, the high-temperature gas is unevenly distributed, and the area with too much high-temperature gas distribution has excess heat and over-burning, and the area with less high-temperature gas distribution has insufficient heat and raw burning, raw burning and over-burning exist at the same time, and the quality fluctuates greatly; third, the production efficiency is low and the cost is high. Summary of the invention

[0006] In order to solve the above-mentioned problems of high control difficulty, large fluctuations in raw and over-burned quicklime, extensive production methods, high energy consumption, and large pollution, and the use of fuel combustion kilns, which will generate a large amount of CO2, high-temperature gas and other waste gas emissions due to fuel combustion, which is more than 2 times higher than the waste gas generated by electric heating, long roasting time, and uneven distribution of high-temperature gas. In areas where high-temperature gas is distributed too much, excess heat causes overburning, and areas where high-temperature gas is distributed less have insufficient heat to cause raw burning, raw burning and overburning exist at the same time, and the quality fluctuates greatly, the present invention provides a production method for a low-carbon molten steel desulfurizer, and the technical scheme adopted is as follows: A method for producing a low-carbon molten steel desulfurizer, the production method comprising: (1) Material ratio: by weight, the raw material is 40-95 parts of quicklime mixed with 5-50 parts of fluorite, and the auxiliary materials are 5-10 parts of alumina and 3-5 parts of silicon dioxide, and the raw material and the auxiliary materials are mixed to form a mixed material; (2) Calcination process: the prepared mixed material is placed in an electromagnetic kiln for calcination for 30-150 minutes; (3) Collecting and cooling: pouring the fired mixed material from the electromagnetic kiln into a collecting device, waiting for it to cool before proceeding to the next step; (4) Post-processing: Grinding is performed using a grinding machine, the particle size of the powder is 0-1 mm, and then packaging is performed.

[0007] In some embodiments, the powder of the quicklime and the fluorite has a particle size of 0-3 mm; and / or the powder of the quicklime and the fluorite has a particle size of 0-40 mm.

[0008] In some embodiments, the CaO content in the quicklime is not less than 80%, and the CaF2 content in the fluorite is not less than 70%.

[0009] In some embodiments, the auxiliary material further includes MgO.

[0010] In some embodiments, the electromagnetic kiln firing temperature is controlled at 900°C-1200°C.

[0011] In some embodiments, the electromagnetic kiln is any one of an electromagnetic rotary kiln, an electromagnetic vertical kiln and an induction medium frequency furnace.

[0012] In some embodiments, the raw material further includes limestone, and the CaCO3 content of the limestone is not less than 70%.

[0013] Compared with the prior art, the present invention has the following technical advances: 1. Using electricity as energy can avoid the large amount of tail gas emissions produced by traditional petrochemical energy, which is more low-carbon and environmentally friendly.

[0014] 2. The electromagnetic kiln is used for production, which makes the production method simpler and the roasting temperature can be accurately controlled within ±5℃, achieving energy saving and process stability.

[0015] 3. Greatly reduce production costs. Ordinary fluorite (CaCO3>1%) can be used instead of fine fluorite, reducing production costs by more than 30%. High temperature is used to decompose carbon-containing substances in fluorite to reduce the total carbon content of the mixture, thereby preparing a low-carbon desulfurizer in one go.

[0016] 4. Solve the preparation problem of low-carbon quicklime. The quality of low-carbon quicklime produced by this method is more stable. Compared with the traditional rotary kiln and smoldering kiln process, the burning rate is lower and can reach less than 0.5%, avoiding the fluctuation of the carbon content of quicklime. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0018] In the attached picture: Figure 1 It is a schematic diagram of the steps of the production method of the low-carbon molten steel desulfurizer of the present invention. DETAILED DESCRIPTION

[0019] The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0020] like Figure 1As shown, the present invention discloses a method for producing a low-carbon molten steel desulfurizer. The steelmaking desulfurizer is added in the steel production process to reduce the S element content in the molten steel. After the desulfurizer is added to the molten steel, it chemically reacts with the S in the molten steel to generate CaS that enters the steel slag. The solid steel slag is separated from the molten steel, thereby removing the S element content in the molten steel.

[0021] Among them, the production method of low carbon molten steel desulfurizer includes: S100, material ratio: by weight, the raw materials are 40-95 parts of quicklime and 5-50 parts of fluorite, and the auxiliary materials are 5-10 parts of aluminum oxide and 3-5 parts of silicon dioxide, and the raw materials and the auxiliary materials are mixed to form a mixed material; During the production process, the producer accurately proportions the raw materials according to the requirements of the product, and selects ordinary quicklime and fluorite as the main components, with the components ranging from 40-95 parts and 5-50 parts. In order to improve the performance of the desulfurizer, the producer can select some auxiliary materials, such as 5-10 parts of aluminum oxide and 3-5 parts of silicon dioxide, and mix them with the raw materials to form a mixed material. In one example, 55 parts of quicklime and 45 parts of fluorite, as well as 5 parts of aluminum oxide and 5 parts of silicon dioxide can be mixed. In another example, 80 parts of quicklime and 20 parts of fluorite, as well as 6 parts of aluminum oxide and 4 parts of silicon dioxide can be mixed to prepare for the next step of firing.

[0022] S200, roasting process: putting the prepared mixed material into an electromagnetic kiln for roasting, and the roasting time is 30-150 minutes; The prepared mixed material is loaded into the electromagnetic kiln for roasting. The electromagnetic kiln generates heat through electromagnetic induction and directly acts on the mixed material, avoiding the heat transfer loss in the traditional kiln, and has the characteristics of high efficiency and energy saving. The roasting time is controlled to be 30-150 minutes. For example, the roasting time is selected to be 40 minutes to achieve the required performance. For example, the roasting time is selected to be 100 minutes to improve stability. It should be noted that the specific time depends on the properties of the mixed material and the product requirements. During the roasting process, the high temperature environment provided by the electromagnetic kiln can promote the internal chemical reaction of the mixed material, so that the effective components of quicklime and fluorite are combined, thereby improving the desulfurization efficiency. At the same time, the use of electromagnetic kilns can ensure the uniformity of temperature, so that the materials are heated evenly, avoiding the problem of local overburning or underburning of materials. The production method of electromagnetic kilns is simpler. In addition, the electromagnetic kiln can be started and stopped immediately without a big impact on the kiln itself, which is not available in other high-temperature kilns. The roasting temperature of the electromagnetic kiln is precisely controlled at ±5℃, achieving energy saving and process stability. S300, collecting and cooling: pouring the fired mixed material from the electromagnetic kiln into a collecting device, waiting for it to cool down before proceeding to the next step; After the roasting is completed, the fired mixed material is taken out from the electromagnetic kiln and transferred to a collection device to prevent it from continuing to react or undergo physical changes due to high temperature. The temperature is allowed to cool naturally to protect the particle structure and performance of the mixed material and ensure its stability in subsequent processing.

[0023] S400, post-processing: grinding with a grinding machine, the particle size of the grinding is 0-1mm, and then packaging.

[0024] The cooled mixture is ground into powder by a grinding machine to form a desulfurizer. The particle size of the powder is 0-1 mm, for example, the particle size of the powder is 0.5 mm, to ensure the fineness and uniformity of the final desulfurizer. Finally, the treated desulfurizer is sealed and packaged and stored in a dry and ventilated warehouse for supply at any time.

[0025] In some embodiments, the chemical composition of quicklime is mainly calcium oxide, and the main component of fluorite is calcium fluoride. The powders of quicklime and fluorite can be adaptively set as needed. In one example, the powders of quicklime and fluorite have a particle size of 0-3 mm, for example, the particle size of quicklime is 2 mm, the particle size of fluorite is 3 mm, and for another example, the particle sizes of quicklime and fluorite are both 1 mm. In another example, the particle size of quicklime and fluorite is 0-40 mm, for example, the particle size of quicklime is 11 mm, the particle size of fluorite is 20 mm, and for another example, the particle size of quicklime and fluorite is both 25 mm.

[0026] In some embodiments, the CaO content in quicklime is not less than 80%, and the CaF2 content in fluorite is not less than 70% to ensure the performance of the final product. For example, quicklime with a CaO content of 85% and fluorite with a CaF2 content of 75% are used. For example, quicklime with a CaO content of 90% and fluorite with a CaF2 content of 80% are used.

[0027] In some embodiments, the auxiliary material also includes MgO, which is added to the raw material and evenly mixed, and then subjected to processes such as roasting, cooling, and grinding to produce a high-quality desulfurizer.

[0028] In some embodiments, the electromagnetic kiln roasting temperature is controlled at 900°C-1200°C. In this temperature range, the electromagnetic kiln uses electromagnetic induction heating technology to make the temperature uniform and stable, avoiding the hot spot or cold spot problems that may occur in traditional heating methods, thereby improving the uniformity and efficiency of the roasting process. In addition, the temperature control system of the electromagnetic kiln can flexibly adjust the heating speed and time according to the characteristics of the material and the roasting requirements to ensure that the roasting effect reaches the best state, which helps to improve the quality and performance of the final product. For example, during the roasting process, the roasting temperature of the electromagnetic kiln is controlled at 900°C, and for another example, 1200°C is used for roasting to achieve energy saving and process stability.

[0029] In some embodiments, the electromagnetic kiln is any one of an electromagnetic rotary kiln, an electromagnetic vertical kiln and an induction medium frequency furnace. In one example, the electromagnetic kiln is an electromagnetic rotary kiln, which is composed of a high-temperature resistant steel tubular kiln body and an electromagnetic coil surrounding the kiln body. The electromagnetic coil converts electrical energy into heat energy of the high-temperature resistant steel tubular kiln body, and the high-temperature kiln body heats the material inside the kiln body. This technology uses electromagnetic coils to heat the high-temperature resistant stainless steel kiln body, and the kiln body transfers heat energy to the mixed material, and the mixed material is prepared at a high temperature of 1000°C to prepare a powdered low-carbon desulfurizer. The electromagnetic rotary kiln is characterized by high efficiency (greater than 90%) in converting electromagnetic energy into heat energy, which is much higher than the thermal efficiency (less than 50%) of other fuel combustion, more energy-saving, small quality fluctuations, no waste gas other than material decomposition, and more environmentally friendly. In another example, the electromagnetic kiln is an electromagnetic vertical kiln. The vertical structure of the electromagnetic vertical kiln allows the material to fall naturally under the action of gravity, and is combined with an electromagnetic heating device to achieve efficient thermal energy utilization. It is more energy-saving during operation. Compared with traditional kilns, electromagnetic vertical kilns can greatly reduce energy consumption and improve production efficiency. In another example, the electromagnetic kiln is an induction medium frequency furnace (with a mechanical stirring device). The induction medium frequency furnace is a device that uses the medium frequency electromagnetic induction principle for heating. The high-frequency current generates an induced current inside the metal material, thereby rapidly heating and melting. The induction medium frequency furnace has the advantages of fast heating speed, precise temperature control, and high resource utilization.

[0030] In some embodiments, the raw material further comprises limestone, and the CaCO3 content of the limestone is not less than 70%. In the present application, limestone can replace quicklime and be mixed with fluorite, so that auxiliary materials are added and mixed evenly to form a mixed material, and roasting, cooling, grinding and other processes are performed to form a desulfurizer.

[0031] The present invention can be better understood with reference to the following examples.

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments; the present invention can be better understood according to the following embodiments. However, it is easy for those skilled in the art to understand that the specific material ratios, process conditions and results described in the embodiments are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without any creative work are within the scope of protection of the present invention.

[0033] Case 1 First, 70 parts of quicklime and 30 parts of fluorite, as well as 7 parts of alumina and 3 parts of silica are uniformly mixed and added into an electromagnetic rotary kiln for roasting at a temperature of 1000°C. The material is discharged after roasting in the kiln for 90 minutes, collected, naturally cooled to room temperature, and then loaded into a grinding mill for powdering with a particle size of 0-1mm. The material is then collected in bags and the carbon content of the desulfurizer obtained is 0.10%.

[0034] Case 2 First, 85 parts of limestone and 15 parts of fluorite, as well as 6 parts of alumina and 4 parts of silicon dioxide are uniformly mixed and added into an electromagnetic rotary kiln for roasting at a temperature of 1100°C. The material is discharged after roasting in the kiln for 60 minutes, collected, naturally cooled to room temperature, and then loaded into a grinding mill for powdering with a particle size of 0-1mm. The desulfurizer finally has a carbon content of 0.08%.

[0035] Case 3 First, 60 parts of quicklime and 40 parts of fluorite, as well as 5 parts of alumina and 5 parts of silica are uniformly mixed and added into a medium frequency induction furnace for roasting at a temperature of 1000°C. The material is discharged after being kept warm in the furnace for 60 minutes, and then collected, cooled naturally to room temperature, and then loaded into a grinding mill for powdering with a particle size of 0-1mm. The material is then collected in bags and the carbon content of the desulfurizer obtained is 0.10%.

[0036] Case 4 First, 70 parts of quicklime and 30 parts of fluorite, as well as 7 parts of alumina and 3 parts of silica are uniformly mixed, added into a medium frequency induction furnace with mechanical stirring for roasting at a temperature of 1100°C, kept warm in the furnace for 30 minutes before discharging the material, then collected, naturally cooled to room temperature, and then loaded into a grinding mill for powdering with a particle size of 0-1mm, and collected in bags. The final desulfurizer has a carbon content of 0.09%.

[0037] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0038] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0040] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0041] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0042] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A method for producing a low-carbon molten steel desulfurizer, It is characterized in that The production method comprises: (1) Material ratio: by weight, the raw materials are 40-95 parts of quicklime and 5-50 parts of fluorite, and the auxiliary materials are 5-10 parts of alumina and 3-5 parts of silicon dioxide. The raw materials and the auxiliary materials are mixed to form a mixed material; (2) Calcination process: the prepared mixed material is placed in an electromagnetic kiln for calcination for 30-150 minutes; (3) Collecting and cooling: pouring the fired mixed material from the electromagnetic kiln into a collecting device, waiting for it to cool before proceeding to the next step; (4) Post-processing: Grinding is performed using a grinding machine, the particle size of the powder is 0-1 mm, and then packaging is performed.

2. The method for producing a low-carbon molten steel desulfurizer according to claim 1, Features: The powder of the quicklime and the fluorite has a particle size of 0-3 mm; and / or the powder of the quicklime and the fluorite has a particle size of 0-40 mm.

3. The method for producing a low-carbon molten steel desulfurizer according to claim 1, Features: The CaO content in the quicklime is not less than 80%, and the CaF 2 The content is not less than 70%.

4. The method for producing a low-carbon molten steel desulfurizer according to claim 1, Features: The auxiliary material also includes MgO.

5. The method for producing a low-carbon molten steel desulfurizer according to claim 1, Features: The electromagnetic kiln calcining temperature is controlled at 900°C-1200°C.

6. The method for producing a low-carbon molten steel desulfurizer according to claim 5, Features: The electromagnetic kiln is any one of an electromagnetic rotary kiln, an electromagnetic vertical kiln and an induction medium frequency furnace.

7. The method for producing a low-carbon molten steel desulfurizer according to claim 1, Features: The raw materials also include limestone, wherein the CaCO 3 The content is not less than 70%.

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