A composite biomass heating agent for steelmaking, its preparation and steelmaking method

Abstract

The present invention discloses a composite biomass heating agent for steelmaking, its preparation and steelmaking method, and belongs to the technical field of converter and electric furnace steelmaking; it solves the technical problem that the existing biomass heating agents cannot be directly used for steelmaking because they do not have metallurgical functions, have low specific gravity and are flammable at room temperature. The composite biomass heating agent for steelmaking of the present invention includes an aluminum-thermal composite biomass heating agent, a silicon-thermal composite biomass heating agent, a manganese-thermal composite biomass heating agent, a fossil-thermal composite biomass heating agent and a low-temperature flame-retardant composite biomass heating agent. The composite biomass heating agent provided by the present invention can achieve the effect of supplementing heat in the furnace while also helping to melt the slag and promote the progress of metallurgical reactions.

Description

Technical Field

[0001] The present invention relates to the technical field of converter and electric furnace steelmaking, and in particular to a composite biomass heating agent special for steelmaking, a preparation method thereof, and a steelmaking method. Background Art

[0002] In metallurgical production, scrap steel is a recyclable iron resource. Increasing the scrap-to-steel ratio and reducing the iron-to-steel ratio will significantly reduce environmental pollution and overall energy consumption in the steel industry, resulting in significant economic, environmental, and social benefits. Over the past decade, the global scrap steel ratio has remained between 35% and 40%, with an average of 37%.

[0003] In the 1970s, oxygen converters rapidly replaced open-hearth furnaces, achieving excellent metallurgical results. However, because the scrap ratio of converters was much lower than that of open-hearth furnaces, a large amount of scrap steel accumulated in society, and blast furnace production capacity was clearly insufficient.

[0004] At present, if biomass heating agents are used directly in steelmaking, there are still the following major problems. First, the function of biomass heating agents is single, and they do not have metallurgical functions such as slag melting and fluxing. Second, the specific gravity of biomass heating agents is relatively low, and it is difficult for them to enter the molten steel pool after being added to the furnace. Most of the heat generated by their combustion is carried away by the furnace gas, which has limited effect on the temperature rise of the molten pool and low heating efficiency. Third, the ignition point of biomass heating agents is 200-300℃, which is relatively low. It is easy to cause spontaneous combustion during storage at room temperature during steelmaking, posing a safety hazard. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a composite biomass exothermic agent for steelmaking, its preparation and steelmaking method, in order to solve the following problems existing in biomass fuel particles when they are directly used for steelmaking:

[0006] First, biomass fuel particles have a single function and do not have metallurgical functions such as slag melting and fluxing;

[0007] Secondly, the specific gravity of biomass fuel particles is relatively low, and it is difficult for them to enter the molten steel pool after being added to the furnace. Most of the heat generated by their combustion is carried away by the furnace gas, which has limited effect on heating the molten steel pool and low heating efficiency.

[0008] Furthermore, the ignition point of biomass fuel particles is 200-300℃, which is relatively low. It is easy to cause spontaneous combustion during storage at room temperature during steelmaking, creating a safety hazard.

[0009] The purpose of the present invention is mainly achieved through the following technical solutions:

[0010] The present invention provides a composite biomass heating agent specially used for steelmaking, the types of which include aluminum-thermal composite biomass heating agent, silicon-thermal composite biomass heating agent, manganese-thermal composite biomass heating agent, fossil-thermal composite biomass heating agent and low-temperature flame-retardant composite biomass heating agent.

[0011] In one possible design, the aluminum-thermal composite biomass heating agent, the silicon-thermal composite biomass heating agent, the manganese-thermal composite biomass heating agent, the fossil-thermal composite biomass heating agent and the low-temperature flame-retardant composite biomass heating agent all include biomass fuel particles.

[0012] In a possible design, the biomass fuel particles are one or more of fir particles, pine particles, and straw particles.

[0013] In one possible design, the particle size of the biomass fuel particle raw material is 3-15 mm.

[0014] In one possible design, biomass fuel pellets are compressed under high pressure and have a carbon content of 40%-50%.

[0015] In one possible design, the thermite composite biomass heat-generating agent also includes industrial aluminum slag;

[0016] The weight content of industrial aluminum slag is 10-90%, and the weight content of biomass fuel particles is 10-90%.

[0017] In one possible design, the silicon-thermal composite biomass heat-generating agent also includes ferrosilicon powder;

[0018] The weight content of ferrosilicon powder is 10-90%, and the weight content of biomass fuel particles is 10-90%.

[0019] In one possible design, the metallic silicon content in the ferrosilicon powder is 50-90%.

[0020] In one possible design, the manganese-thermal composite biomass heating agent also includes ferromanganese powder;

[0021] The weight content of the ferromanganese powder is 10-90%, and the manganese content in the ferromanganese powder is 40-80%.

[0022] The weight content of biomass fuel particles is 10-90%.

[0023] The present invention also provides a method for preparing a composite biomass exothermic agent, which is used for the above-mentioned composite biomass exothermic agent dedicated to steelmaking.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] (1) The present invention combines biomass fuel particles with industrial aluminum slag, ferrosilicon powder, ferromanganese powder, fossil powder and inorganic flame retardants, thereby eliminating the problems of biomass fuel particles having no metallurgical function, low specific gravity and flammability at room temperature, thereby forming a series of composite biomass heating agents specifically for steelmaking, which can be better applied to steelmaking production practice.

[0026] (2) The composite biomass heating agent provided by the present invention can meet the process requirements of converter and electric furnace steelmaking processes for heat supplementation in steelmaking, thereby achieving the purpose of consuming more cold materials.

[0027] (3) The composite biomass heating agent provided by the present invention can not only achieve the effect of supplementing heat in the furnace, but also help melt the slag and promote the progress of metallurgical reactions.

[0028] (4) The composite bio-heating agent provided by the present invention can reduce steelmaking costs and increase the scrap steel ratio without increasing the carbon emissions of the heat supplement agent, thereby achieving the purpose of reducing carbon in converter smelting.

[0029] (5) The composite biomass heating agent of the present invention can save a large amount of aluminum, silicon, manganese and fossil heating agents due to the use of biomass fuel particles, thus protecting precious earth resources; in addition, a large amount of previously discarded plant products can be converted into valuable energy, turning waste into treasure; at the same time, the open-air burning of waste plant products is reduced, thereby reducing pollution to the environment.

[0030] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the embodiments of the description and the contents particularly pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. Throughout the drawings, the same reference symbols denote the same components.

[0032] Figure 1 This is a schematic structural diagram of the composite biomass heating agent for steelmaking of the present invention. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0034] On the one hand, the present invention provides a composite biomass heating agent specially used for steelmaking, including aluminum-thermal composite biomass heating agent, silicon-thermal composite biomass heating agent, manganese-thermal composite biomass heating agent, fossil-thermal composite biomass heating agent and low-temperature flame-retardant composite biomass heating agent.

[0035] It should be noted that the composite biomass heating agent for steelmaking of the present invention is a multi-layer core-shell structure. Figure 1 As shown; wherein, the components from the inner core to the outermost layer are: fossil composite biomass heating agent, aluminum thermal composite biomass heating agent, manganese thermal composite biomass heating agent, silicon thermal composite biomass heating agent and low-temperature flame retardant composite biomass heating agent.

[0036] The present invention designs the composite biomass exothermic agent into the above-mentioned multi-layer core-shell structure because:

[0037] First, the present invention uses the low-temperature flame-retardant composite biomass heating agent as the outer shell of the composite biomass heating agent, which can ensure that the composite biomass heating agent is easy to store in a dry and relatively hot environment and can be used for daily preservation.

[0038] Secondly, the fourth layer, third layer and second layer structures of the composite biomass heating agent of the present invention from the inside to the outside are silicon-thermal composite biomass heating agent, manganese-thermal composite biomass heating agent and aluminum-thermal composite biomass heating agent respectively. These heating agents comply with the oxidation sequence law of the converter when burned in the furnace. They can not only achieve the effect of heating in the furnace and quickly increase the temperature in the furnace, but also help melt the slag and promote the progress of metallurgical reactions.

[0039] Finally, the present invention uses the fossil composite biomass heating agent as the core because when the fossil composite biomass heating agent begins to burn, the temperature in the converter has already risen and reached the carbon combustion period. This combustion atmosphere is conducive to the full combustion of the fossil composite biomass heating agent and the exertion of thermal efficiency. At the same time, a large number of bubbles are generated to facilitate the stirring of the molten pool.

[0040] It should be noted that in the above-mentioned multi-layer core-shell structured composite biomass heating agent, the weight content ratio of the fossil composite biomass heating agent, the aluminum thermal composite biomass heating agent, the manganese thermal composite biomass heating agent, the silicon thermal composite biomass heating agent and the low-temperature flame retardant composite biomass heating agent is 1:1-1.6:0.9-1.0:0.9-1.0:1-1.4.

[0041] It should be explained that, under normal circumstances, in the above-mentioned multi-layer core-shell structured composite biomass heating agent, the weight content ratio of the fossil composite biomass heating agent, the aluminum thermal composite biomass heating agent, the manganese thermal composite biomass heating agent, the silicon thermal composite biomass heating agent and the low-temperature flame retardant composite biomass heating agent is 1:1:1:1:1.

[0042] In special circumstances, the weight content of each component can be adjusted according to actual conditions. For example, in summer and autumn when the temperature is relatively high, the weight content of the low-temperature flame-retardant composite biomass heating agent, which serves as the shell of the composite biomass heating agent, can be increased by 30%-40%. In addition, when the silicon content of molten iron is high, the weight content of the silicon-thermal composite biomass heating agent can be reduced to less than 10%.

[0043] The multi-layer core-shell composite biomass heating agent of the present invention has a specific gravity of 1.85-2.36, which is 1.8-2.0 times that of pure citrus stalk biomass. Therefore, the composite biomass heating agent of the present invention can increase the specific gravity of biomass fuel particles, promote thermal efficiency in the furnace, and reduce heat loss.

[0044] It should be noted that the aluminum-thermite composite biomass heating agent, silicon-thermite composite biomass heating agent, manganese-thermite composite biomass heating agent, fossil-thermite composite biomass heating agent and low-temperature flame-retardant composite biomass heating agent of the present invention all include biomass fuel particles.

[0045] The CO₂ released during combustion of biomass pellet fuel is roughly equivalent to the CO₂ absorbed through photosynthesis during its growth. Therefore, the biomass fuel pellets of the present invention produce zero greenhouse gas CO₂ emissions. Biomass fuel pellets are also a renewable energy source. As long as there is sunlight, green plants continue to photosynthesize, and biomass energy will not be depleted, maintaining a dynamic balance of greenhouse gases and eliminating any environmental pollution issues.

[0046] The biomass fuel particles of the present invention are dense biomass particles. The raw materials of the biomass fuel particles include one or more of fir particles, pine particles and straw particles. The calorific value and economic cost of the biomass pellet fuel are very advantageous, as shown in Table 1 and Table 2 below. Among them, the calorific value of fir particles is 4646 kcal / kg; the calorific value of pine particles is 4751 kcal / kg; and the calorific value of straw particles is 3919 kcal / kg. The calorific value and cost of the biomass pellet fuel are comparable to those of coal.

[0047] Table 1 Comparison of calorific value and cost of various fuels

[0048]

[0049] Table 2 Energy consumption of various fuels for producing one ton of steam boiler

[0050]

[0051] It should be noted that the biomass in the aforementioned biomass fuel pellets includes one or more of fir wood pellets, pine wood pellets, and straw pellets. The biomass fuel pellets are 3-15 mm in size and are formed through high-pressure compression, with a carbon content of 40%-50%. The specific process includes the following:

[0052] Step 1: crush and screen one or more of fir wood particles, pine wood particles and straw, and the particle size of the crushed biomass fuel particle raw materials is 0-60 mesh.

[0053] Step 2: The raw materials are screened through the lower screen of the crusher, and the materials with a mesh size of less than or equal to 60 are discharged along the screen, while those with a mesh size greater than 60 are returned for further crushing;

[0054] Step 3: Dry the screened raw materials, compress them under high pressure, and then cool and package them.

[0055] It should be noted that during the processing of biomass fuel pellets, the biomass is transformed from a powdery form to a spherical pellet, the volume of the biomass changes, and the volume density of the biomass increases by 0.3-0.5 times. After being processed into biomass fuel pellets, it is convenient for transportation, storage and feeding.

[0056] After the biomass fuel particles are made into a composite biomass heating agent specifically for steelmaking, the specific gravity of the composite biomass heating agent is higher than that of pure biomass fuel particles. When the composite biomass heating agent is used in steelmaking, the biomass fuel particles can sink in the slag to oxidize and generate heat, thereby avoiding being sucked away by the fan, and ultimately improving their utilization efficiency in the molten pool.

[0057] Existing biomass exothermic agents must be prepared into biochar before use. However, carbonizing biomass materials requires not only high-temperature treatment but also high-pressure treatment, which is complex and energy-intensive, increasing costs. Furthermore, carbonizing biomass materials reduces their bulk density, requiring the addition of a weighting agent during pelletization. The use of a weighting agent, in turn, reduces the thermal efficiency of the exothermic agent.

[0058] The biomass fuel particles of the present invention do not require high-temperature treatment. On the one hand, they can provide low-cost raw materials for steelmaking, reduce production costs, and alleviate the cost pressure in the steelmaking and carbon reduction process; on the other hand, the biomass fuel particles of the present invention are non-carbonized particles with a high specific gravity, which is more conducive to the adjustment of specific gravity.

[0059] It should be noted that when existing biomass fuel particles are directly used in steelmaking, the function of the biomass fuel particles is single and they do not have metallurgical functions such as slag melting and fluxing. Secondly, the specific gravity of the biomass fuel particles is relatively low, and it is difficult for them to enter the molten steel pool after being added to the furnace. Most of the heat generated by their combustion is carried away by the furnace gas, and the molten pool cannot be heated, resulting in low heating efficiency. Thirdly, the ignition point is low, at 200-300°C, which can easily cause spontaneous combustion during storage at room temperature during steelmaking, creating a safety hazard.

[0060] Compared with the existing technology, the biomass fuel particles used in the present invention have a high calorific value. Among them, the calorific value of fir particles is 4646 kcal / kg, the calorific value of pine particles is 4751 kcal / kg, and the calorific value of straw particles is 3919 kcal / kg. In addition, biomass fuel particles are clean and pollution-free, easy to store and transport, and will gradually become a substitute for fossil energy (coal) in some fields, thus forming a new type of high-tech environmentally friendly energy product.

[0061] In order to simultaneously meet the requirements of steelmaking slag and temperature increase, the thermite composite biomass heating agent of the present invention also includes industrial aluminum slag; the weight content of the industrial aluminum slag is 10-90%, and the weight content of the biomass fuel particles is 10-90%; among which, the weight content of metallic aluminum in the industrial aluminum slag is 15-45%.

[0062] Controlling the weight content of the above-mentioned industrial aluminum slag within the above-mentioned range is conducive to slagging and metallurgical reactions in the steelmaking process; controlling the biomass fuel particles within the above-mentioned range is conducive to heat supplementation in the steelmaking process, and does not increase carbon emissions during the steelmaking heat supplementation process, while increasing the molten pool temperature and saving costs, environmental protection and utilization of plant waste.

[0063] It should be emphasized that the thermite composite biomass heating agent of the present invention has a core-shell structure with biomass fuel particles as the core and industrial aluminum slag as the shell.

[0064] Setting the aluminothermic composite biomass heating agent into the above-mentioned core-shell structure can make full use of industrial aluminum slag, a by-product of the non-ferrous industry, reduce waste emissions, save the earth's aluminum resources, increase the cold material ratio of steelmaking, promote the diversification of slag, and help slag smelting.

[0065] The preparation method of the above-mentioned thermite composite biomass heating agent comprises the following steps:

[0066] Step 1: Add biomass fuel particles into a pelletizer and spray a binder therein;

[0067] Step 2: adding the industrial aluminum slag to a granulator according to a process ratio of 10-90% by weight of industrial aluminum slag and 10-90% by weight of biomass fuel particles, and spraying a binder into the granulator for granulation;

[0068] Step 2: obtaining aluminothermic composite biomass particles with biomass fuel particles as the core and industrial aluminum slag as the shell;

[0069] Step 3: The aluminothermic composite biomass particles are subjected to high-pressure molding using a roller pelletizer, wherein the molding pressure of the roller pelletizer is 200-230 tons to obtain an aluminothermic composite biomass heating agent;

[0070] Step 4: Store, weigh and package the thermite composite biomass heating agent as required.

[0071] It should be noted that the basic components of the industrial aluminum slag of the present invention are shown in Table 3 below. Industrial aluminum slag is a by-product in non-ferrous industrial aluminum smelting, and its main components are shown in Table 3.

[0072] Table 3 Basic composition of industrial aluminum slag

[0073]

[0074] The aluminum slag in Table 3 above contains not only aluminum oxide but also a significant amount of pure aluminum. Calculations using metallurgical thermodynamic data for the aluminum slag in Table 1 indicate an oxidation heat generation of 6900-7100 kJ / kg, comparable to the heat generation of biomass fuel pellets. Mixing industrial aluminum slag with biomass fuel pellets to create a new composite biomass heat-generating agent would be even more significant.

[0075] First, my country produces a large amount of aluminum waste slag every year, and the discharge of this waste slag pollutes the environment. The present invention combines industrial aluminum slag with biomass fuel particles to produce a thermite composite biomass heating agent. On the one hand, it will significantly reduce the discharge of aluminum waste slag, reduce environmental pollution, and benefit environmental protection; on the other hand, it will turn industrial aluminum slag into treasure, realizing the reuse of aluminum resources. Furthermore, using industrial aluminum slag as a raw material for steelmaking heating agent will not increase carbon emissions.

[0076] Secondly, the present invention adopts the aluminothermic composite biomass heating agent in steelmaking, which can increase the steelmaking capacity at a lower cost and obtain greater economic benefits by consuming more scrap steel.

[0077] Furthermore, the thermite composite biomass heating agent can form rich multi-component slag in the converter during steelmaking, promoting the melting of the converter slag and the metallurgical reaction of impurity removal.

[0078] For example, taking the thermite composite biomass heating agent as an example, the present invention applies the prepared thermite composite biomass heating agent to a medium-sized converter electric furnace, achieving good economic benefits, as shown in Table 4 for details.

[0079] Table 4 Application examples of thermite composite biomass heating agent

[0080]

[0081] The composite biomass heating agent for steelmaking of the present invention also includes a silicon-thermal composite biomass heating agent, wherein the silicon-thermal composite biomass heating agent also includes ferrosilicon powder; the weight content of the ferrosilicon powder is 10-90%, and the weight content of the biomass fuel particles is 10-90%.

[0082] It should be noted that the content of metallic silicon in the above-mentioned ferrosilicon powder is 50-90%.

[0083] The present invention controls the weight content of ferrosilicon powder and biomass fuel particles within the above-mentioned range. On the one hand, when the silicon-thermal composite biomass heating agent of the present invention is adopted, it can meet the process requirements of converter and electric furnace steelmaking processes for steelmaking heat supplementation, thereby achieving the purpose of consuming more cold materials; on the other hand, while achieving the heat supplementation effect in the furnace, the metallic silicon in the silicon-thermal composite biomass heating agent can form silicon oxide, which can increase the fluidity of the slag, thereby helping to melt the slag and promote the diversified composition of the slag and the progress of metallurgical reactions.

[0084] It should be emphasized that the above-mentioned silicon-thermal composite biomass heating agent is a core-shell structure with biomass fuel particles as the core and ferrosilicon powder as the shell.

[0085] Setting the silicon-thermal composite biomass heating agent into the above-mentioned core-shell structure can make full use of industrial waste slag, a by-product of the non-ferrous industry, reduce waste emissions, save the earth's aluminum resources, increase the cold material ratio of steelmaking, reduce the viscosity of slag, and help slag reduction.

[0086] The preparation method of the above-mentioned silicon-thermal composite biomass heating agent comprises the following steps:

[0087] Step 1: Add biomass fuel particles into a pelletizer and spray a binder therein;

[0088] Step 2: adding ferrosilicon powder to a granulator according to a process ratio in which the weight content of ferrosilicon powder is 10-90% and the weight content of biomass fuel particles is 10-90%, and spraying a binder into the granulator for granulation;

[0089] Step 2: obtaining silicon-thermal composite biomass particles with biomass fuel particles as the core and ferrosilicon powder as the shell;

[0090] Step 3: The silicon-thermal composite biomass particles are subjected to high-pressure molding using a roller pelletizer, wherein the molding pressure of the roller pelletizer is 200-230 tons to obtain a silicon-thermal composite biomass exothermic agent;

[0091] Step 4: Store, weigh and package the thermite composite biomass heating agent as required.

[0092] The composite biomass heating agent for steelmaking of the present invention also includes a manganese-heat composite biomass heating agent, wherein the manganese-heat composite biomass heating agent also includes ferromanganese powder; the weight content of the ferromanganese powder is 10-90%, and the weight content of the biomass fuel particles is 10-90%.

[0093] It should be noted that the weight content of metallic manganese in the ferromanganese powder is 50-80%.

[0094] Compared with the existing technology, the manganese-thermal composite biomass heating agent of the present invention can not only meet the process requirements of converter and electric furnace steelmaking processes for steelmaking heat supplementation, and achieve the purpose of consuming more cold materials; in addition, it can also achieve the effect of heat supplementation in the furnace. After the manganese in the manganese-thermal composite biomass heating agent forms manganese oxide, it will also increase the fluidity of the slag, help the melting of the slag, and promote the diversified composition of the slag and the progress of metallurgical reactions.

[0095] It should be emphasized that the above-mentioned manganese-thermal composite biomass heating agent is a core-shell structure with biomass fuel particles as the core and manganese iron powder as the shell.

[0096] Designing the manganese-thermal composite biomass heating agent into this structure can increase the cold material ratio of steelmaking, reduce the viscosity of the slag, help slag reduction, and facilitate the removal of impurities in the steel.

[0097] The composite biomass heating agent for steelmaking of the present invention also includes a fossil composite biomass heating agent, wherein the weight content of fossil powder in the fossil composite biomass heating agent is 10-90%, the weight content of biomass fuel particles is 10-90%, and the fixed carbon content in the fossil powder is 50-90%.

[0098] Compared with the use of biomass fuel particles alone, the use of fossil heat composite biomass heating agent can more efficiently increase the calorific value, improve the thermal efficiency of the converter, and achieve the goal of increasing steelmaking capacity.

[0099] It should be emphasized that the fossil composite biomass heating agent of the present invention has a core-shell structure with biomass fuel particles as the core and fossil powder as the shell.

[0100] Setting the fossil composite biomass heating agent into the above-mentioned core-shell structure can increase the cold material ratio of steelmaking, help stir the molten pool, promote the decarbonization reaction, help slag, and facilitate the removal of impurities in steel.

[0101] The preparation method of the fossil composite biomass heating agent comprises the following steps:

[0102] Step 1: Add biomass fuel particles into a pelletizer and spray a binder therein;

[0103] Step 2: adding the fossil powder to a pelletizer according to a process ratio of 10-90% by weight of the fossil powder and 10-90% by weight of the biomass fuel particles, and spraying a binder into the pelletizer for pelletizing;

[0104] Step 2: obtaining fossil composite biomass particles with biomass fuel particles as the core and fossil powder as the shell;

[0105] Step 3: The fossil composite biomass particles are subjected to high-pressure molding using a roller pelletizer, wherein the molding pressure of the roller pelletizer is 200-230 tons to obtain a fossil composite biomass heating agent;

[0106] Step 4: Store, weigh and package the fossil composite biomass heating agent as required.

[0107] The composite biomass heating agent specially used for steelmaking of the present invention also includes a low-temperature flame-retardant composite biomass heating agent, which includes an inorganic flame retardant and biomass fuel particles, wherein the weight content of the inorganic flame retardant is 5-20%, and the weight content of the biomass fuel particles is 80-95%.

[0108] It should be noted that inorganic flame retardants include aluminum hydroxide and magnesium hydroxide. These materials combine flame retardancy, smoke suppression, and filling properties. They are non-toxic, non-corrosive, and stable, producing no toxic gases or smoke suppression. The use of low-temperature flame-retardant composite biomass heating agents allows for easy storage of the heating agent components in high-temperature, dry conditions, preventing heating and spontaneous combustion during storage.

[0109] It should be emphasized that the low-temperature flame-retardant composite biomass heating agent of the present invention has a core-shell structure with biomass fuel particles as the core and an inorganic flame retardant material as the shell.

[0110] Designing the low-temperature flame-retardant composite biomass heating agent into the above-mentioned core-shell structure can increase the cold material ratio of steelmaking, help stir the molten pool, promote the decarbonization reaction, and help slag, allowing for the full utilization of natural waste such as orange straw, turning waste into treasure and protecting the environment.

[0111] The preparation method of the low-temperature flame-retardant composite biomass heating agent comprises the following steps:

[0112] Step 1: Add biomass fuel particles into a pelletizer and spray a binder therein;

[0113] Step 2: adding the inorganic flame retardant into a granulator according to a process ratio of 5-20% by weight of the inorganic flame retardant and 80-95% by weight of the biomass fuel particles, and spraying a binder into the granulator for granulation;

[0114] Step 2: obtaining fossil composite biomass particles with biomass fuel particles as the core and inorganic flame retardant material as the shell;

[0115] Step 3: The fossil composite biomass particles are subjected to high-pressure molding using a roller pelletizer, wherein the molding pressure of the roller pelletizer is 200-230 tons to obtain a low-temperature flame-retardant composite biomass heating agent;

[0116] Step 4: Store, weigh and package the low-temperature flame-retardant composite biomass heating agent as required.

[0117] The present invention also provides a method for using a composite biomass heating agent specifically for steelmaking, comprising the following steps:

[0118] Step 1: Add scrap steel and molten iron to the converter in sequence, and calculate the converter heat balance and material balance using a converter smelting static model based on process parameters such as the chemical composition of the molten iron, temperature, amount of scrap steel added, and furnace conditions.

[0119] Step 2: Prepare the composite biomass heating agent and slag-forming agent according to the calculation results of the converter smelting static model;

[0120] Step 3: Straighten the converter body, lower the top oxygen lance to the oxygen opening position, blow oxygen and start smelting;

[0121] Step 4: After ignition for 1-2 minutes after blowing, add the first batch of slag into the converter, which is 1 / 3-1 / 2 of the total amount of slag. At the same time, add the composite biomass heating agent prepared in step 2 into the converter through the high-level silo;

[0122] Step 5: After the first batch of slag is basically melted and covers the surface of the molten pool, add the second batch of slag, which may also contain biomass composite particles;

[0123] Step 6: Continue blowing to the end point, raise the top oxygen lance and stop blowing oxygen; then open the tapping port and pour the furnace to tap the steel;

[0124] Step 7: After the steel is tapped, the next batch of steel is smelted.

[0125] It should be noted that, when the composite biomass heating agent with a multi-layer core-shell structure of the present invention is used for steelmaking, since the phosphorus and sulfur content in the composite biomass heating agent is low, it has no effect on the phosphorus and sulfur at the smelting end point; in addition, since the composite biomass heating agent contains biomass fuel particles whose raw materials are fir particles, pine particles and straw, as well as industrial aluminum slag, ferromanganese powder, ferrosilicon powder and other wastes, the composite biomass heating agent can be used as a temperature-raising agent during the steelmaking process to achieve zero carbon emissions during the steelmaking heat supplement process, which provides strong support for the converter to achieve a large scrap steel ratio smelting under the premise of zero carbon heat supplement; at the same time, the digestion of waste plants such as straw through converters and electric furnaces also avoids the environmental problems caused by their unorganized combustion in fields and at the end of the land.

[0126] In existing steelmaking heat supplementation processes, the main heat supplementation materials used to improve thermal efficiency are metal and non-metallic heat supplementation agents. These metal and non-metallic heat supplementation agents have advantages such as high calorific value and high heat supplementation efficiency, but they also bring some negative impacts to steelmaking production and society. The main ones are as follows:

[0127] First, these metallic and non-metallic supplemental heat agents are valuable resources formed by the Earth's long evolutionary process and are non-renewable. Second, existing metallic and non-metallic supplemental heat agents are expensive, significantly increasing steelmaking costs. Third, when siliceous supplemental heat agents are used as metal supplemental heat agents, the silica formed upon addition to the furnace will enter the slag, reducing its alkalinity and, in turn, reducing its desulfurization and dephosphorization effectiveness. This also increases corrosion of the furnace lining, increasing steelmaking costs. Fourth, when aluminum is used as a metal supplemental heat agent, aluminum is a more valuable resource and an excellent aerospace structural material. It is the most commonly used deoxidizer in steelmaking. Using large quantities of aluminum as a supplemental heat agent would be a significant waste. Furthermore, using large amounts of aluminum supplemental heat would result in the formation of a certain amount of aluminum oxide inclusions, which would degrade steel quality.

[0128] It should be noted that the type of composite biomass heating agent added to the present invention can be selected according to the type of steel being smelted or the process requirements. For example, when smelting high-grade silicon steel, the lower the [Mn] content in the steel is required to be, the better, then manganese biomass heating agent is not selected; in addition, some steel types, such as automobile plates, may have requirements for carbon emission indicators, then fossil biomass heating agents are not selected.

[0129] It should be noted that in steelmaking production vessels such as converters and electric furnaces, the multi-layer core-shell structure composite biomass exothermic agent of the present invention can be added according to the process requirements, or only one of the components can be added to achieve the effect of supplementing heat in the furnace. For example, it is necessary to consider the difficulty and cost of obtaining the added exothermic agent. When aluminum waste is easy to obtain and the cost is low in some places, the aluminum heat composite biomass exothermic agent can be used alone; and when manganese waste is easy to obtain and the cost is low, the manganese heat composite biomass exothermic agent can be used alone.

[0130] Example 1

[0131] This embodiment uses aluminothermic composite biological exothermic agent to carry out steelmaking, and the specific process is as follows:

[0132] 93 tons of scrap steel and 140 tons of molten iron were added to the converter at a temperature of 1399°C, with a carbon content of 4.24% and a silicon content of 0.20%. The amount of biomass heat booster and slag-forming agent was calculated based on the molten iron temperature and composition, and the materials were prepared based on the calculated results.

[0133] After the converter was opened and ignited, the calculated heat supplement and auxiliary raw materials were added, including 8.162 tons of aluminothermic composite bio-heating agent, 3.09 tons of metallized pellets, 17.649 tons of lime, and 3.231 tons of light-burned dolomite. The converter continued blowing, and at 14'57", the auxiliary lance was measured, showing a TSC temperature of 1571°C and a TSC carbon of 0.25%. Blowing continued until the end point, when the lance was removed and the auxiliary lance was measured again. The end point temperature was 1585°C, the end point carbon was 0.04%, the end point phosphorus was 0.0065%, and the end point sulfur was 0.0052%. The end point composition temperature was acceptable, and steel was tapped. After tapping was completed, the next heat of steel was smelted. The scrap ratio of this heat reached 39.9%.

[0134] Example 2

[0135] This embodiment uses aluminothermic composite biological exothermic agent to carry out steelmaking, and the specific process is as follows:

[0136] The converter was charged with 31.5 tons of scrap steel and 200 tons of molten iron at a temperature of 1399°C, a carbon content of 4.12%, and a silicon content of 0.15%. The amount of biomass heat supplement and slag-forming agent was calculated based on the molten iron temperature and composition, and the materials were prepared based on the calculated results.

[0137] After the converter was started and ignited, the calculated heat supplement and auxiliary raw materials were added, including 2.162 tons of aluminothermic composite biological heating agent, 3.09 tons of metallized pellets, 4.649 tons of lime, 3.231 tons of light-burned dolomite, and 1.407 tons of raw dolomite. The converter continued to blow, and the auxiliary lance was measured at 11'57". At this time, the TSC temperature was 1571°C and the TSC carbon was 0.15%. The converter continued to blow to the end point, then the lance was lifted and the auxiliary lance was measured again. The end point temperature was 1585°C, the end point carbon content was 0.04%, the end point phosphorus content was 0.0069%, and the end point sulfur content was 0.0051%. The end point composition temperature was qualified, and steelmaking was organized. After steelmaking was completed, the next batch of steel was smelted.

[0138] Example 3

[0139] This embodiment uses aluminothermic composite biological exothermic agent to carry out steelmaking, and the specific process is as follows:

[0140] The converter was charged with 24.9 tons of scrap steel and 199.7 tons of molten iron at a temperature of 1361°C, a carbon content of 4.12%, and a silicon content of 0.16%. The amount of biomass heat supplement and slag-forming agent was calculated based on the molten iron temperature and composition, and the materials were prepared based on the calculated results.

[0141] After the converter was started and ignited, the calculated heat supplement and auxiliary raw materials were added, including 7.487 tons of aluminothermic composite biological heating agent, 1.778 tons of metallized pellets, 4.985 tons of lime, 2.796 tons of light-burned dolomite, and 1.04 tons of ore. The converter continued to blow, and the auxiliary lance was measured at 11'09". At this time, the TSC temperature was 1576℃ and the TSC carbon was 0.40%. The blowing was continued to the end point, the lance was lifted, and the auxiliary lance was measured again. The end point temperature was 1619℃, the end point carbon content was 0.03%, the end point phosphorus content was 0.0081%, and the end point sulfur content was 0.0055%. The end point composition temperature was qualified, and steel was tapped. After tapping was completed, the next batch of steel was smelted.

[0142] Example 4

[0143] This embodiment uses aluminothermic composite biological exothermic agent to carry out steelmaking, and the specific process is as follows:

[0144] The converter was charged with 27.4 tons of scrap steel and 199.7 tons of molten iron at a temperature of 1356°C, containing 4.17% carbon and 0.15% silicon. The amount of biomass heat booster and slag-forming agent was calculated based on the molten iron temperature and composition, and the materials were prepared based on the calculated results.

[0145] After the converter was started and ignited, the calculated heat supplement and auxiliary raw materials were added, including 2.885 tons of aluminothermic composite biological heating agent, 2.556 tons of metallized pellets, 4.976 tons of lime, 2.765 tons of light-burned dolomite, and 0.506 tons of raw dolomite. The converter continued to blow, and the auxiliary lance was measured at 10'09". At this time, the TSC temperature was 1570℃ and the TSC carbon was 0.24%. The blowing was continued to the end point, the lance was lifted, and the auxiliary lance was measured again. The end point temperature was 1591℃, the end point carbon content was 0.07%, the end point phosphorus content was 0.0097%, and the end point sulfur content was 0.0054%. The end point composition temperature was qualified, and steel tapping was organized. After tapping was completed, the next batch of steel smelting was carried out.

[0146] Example 5

[0147] This embodiment uses aluminothermic composite biological exothermic agent to carry out steelmaking, and the specific process is as follows:

[0148] The converter was charged with 26.7 tons of scrap steel and 199.4 tons of molten iron at a temperature of 1403°C, containing 4.25% carbon and 0.25% silicon. The amount of biomass heat booster and slag-forming agent was calculated based on the molten iron temperature and composition, and the materials were prepared based on the calculated results.

[0149] After the converter was started and ignited, the calculated heat supplement and auxiliary raw materials were added, including 2.509 tons of aluminothermic composite biological heating agent, 5.561 tons of metallized pellets, 5.309 tons of lime, 2.966 tons of light-burned dolomite, and 1.104 tons of ore. The converter continued to blow, and the auxiliary lance was measured at 12'09". At this time, the TSC temperature was 1550℃ and the TSC carbon was 0.174%. The blowing was continued to the end point, the lance was lifted, and the auxiliary lance was measured again. The end point temperature was 1608℃, the end point carbon content was 0.036%, the end point phosphorus content was 0.0062%, and the end point sulfur content was 0.0058%. The end point composition temperature was qualified, and steel tapping was organized. After tapping was completed, the next batch of steel smelting was carried out.

[0150] Table 5 Steelmaking using aluminothermic composite biomass in Examples 1 to 5

[0151]

[0152] As shown in Table 5 above, Examples 1 to 5 are all examples of using a 200-ton converter to make steel using a thermite composite biomass exothermic agent. By applying the thermite biomass exothermic agent to actual steelmaking, the effectiveness of using the thermite composite biomass exothermic agent in actual production is fully demonstrated, and its effect of consuming more scrap steel is obvious: Among them, in Example 1, 8.163 tons of thermite composite biomass exothermic agent was added, and the amount of scrap steel processed was 93 tons. In Examples 2 to 4, the average amount of thermite composite biomass exothermic agent added per furnace was 2-3 tons, and the amount of scrap steel processed was 27-31 tons. In Example 5, the average weight ratio of scrap steel / thermite composite biomass exothermic agent was 9.0-11 tons / ton; the above five examples all illustrate that the use of the thermite biomass exothermic agent of the present invention has a significant and stable effect on the converter consuming more cold materials.

[0153] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A composite biomass heating agent for steelmaking, characterized in that: The composite biomass heating agent for steelmaking is a multi-layer core-shell structure, and its components from the inner core to the outermost layer are: fossil composite biomass heating agent, aluminum thermal composite biomass heating agent, manganese thermal composite biomass heating agent, silicon thermal composite biomass heating agent and low-temperature flame retardant composite biomass heating agent; The specific gravity of the multi-layer core-shell composite biomass heating agent is 1.85-2.36; The aluminum-thermite composite biomass heating agent, silicon-thermite composite biomass heating agent, manganese-thermite composite biomass heating agent, fossil-thermite composite biomass heating agent and low-temperature flame-retardant composite biomass heating agent all include biomass fuel particles; The aluminothermic composite biomass heating agent also includes industrial aluminum slag; the aluminothermic composite biomass heating agent is a core-shell structure with biomass fuel particles as the core and the industrial aluminum slag as the shell; The silicon-thermal composite biomass heating agent further comprises ferrosilicon powder; the silicon-thermal composite biomass heating agent is a core-shell structure with the biomass fuel particles as the core and the ferrosilicon powder as the shell; The manganese-heat composite biomass exothermic agent further includes ferromanganese powder, and the manganese-heat composite biomass exothermic agent is a core-shell structure with the biomass fuel particles as the core and the ferromanganese powder as the shell; The fossil composite biomass exothermic agent also includes fossil powder; the fossil composite biomass exothermic agent is a core-shell structure with the biomass fuel particles as the core and the fossil powder as the shell; The low-temperature flame-retardant composite biomass heating agent also includes an inorganic flame retardant substance; the low-temperature flame-retardant composite biomass heating agent is a core-shell structure with biomass fuel particles as the core and inorganic flame retardant substance as the shell.

2. The composite biomass exothermic agent for steelmaking according to claim 1, characterized in that: The biomass fuel particles are one or more of fir particles, pine particles and straw particles.

3. The composite biomass exothermic agent for steelmaking according to claim 2, characterized in that: The size of the biomass fuel particles is 3-15 mm.

4. The composite biomass exothermic agent for steelmaking according to claim 3, characterized in that: The biomass fuel particles are formed by high-pressure compression and have a carbon content of 40%-50%.

5. The composite biomass exothermic agent for steelmaking according to claim 1, characterized in that: In the thermite composite biomass heating agent, the weight content of the industrial aluminum slag is 10-90%, and the weight content of the biomass fuel particles is 10-90%.

6. The composite biomass exothermic agent for steelmaking according to claim 1, characterized in that: In the silicon-thermal composite biomass heating agent, the weight content of the ferrosilicon powder is 10-90%, and the weight content of the biomass fuel particles is 10-90%.

7. The composite biomass exothermic agent for steelmaking according to claim 6, characterized in that: The content of metallic silicon in the ferrosilicon powder is 50-90%.

8. The composite biomass exothermic agent for steelmaking according to claim 1, characterized in that: In the manganese-thermal composite biomass heating agent, the weight content of the ferromanganese powder is 10-90%, and the weight content of the biomass fuel particles is 10-90%.

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