Eutectic catalyst for sinter and method of use thereof

Abstract

The application belongs to the technical field of iron ore powder sintering, and discloses a eutectic catalyst for sintered ore, which contains the following components in percentage by mass: CaO 10%~60%, Fe2O3 10%~60%, MgO 2%~50%, Al2O3 2%~50%, SiO2 2%~50%, and Re 2%~20%; the eutectic catalyst is prepared by crushing, proportioning, mixing, melting, cooling crystallization and crushing from iron ore, lime, rare earth, lightly-burned dolomite and wollastonite. By adding the eutectic catalyst in the sintering raw material, the eutectic catalyst is melted again to participate in and promote the rapid progress of the physical and chemical reactions in the sintering process, so that the vertical sintering speed, utilization coefficient and yield of the sintering machine are improved, and the low-temperature reduction pulverization and softening dripping and other metallurgical performance indexes of the sintered ore are improved.

Description

Technical Field

[0001] This invention belongs to the field of iron ore powder sintering technology, and relates to a eutectic catalyst for sintering ore and its application method. Background Technology

[0002] Sinter is a major raw material for blast furnaces. With the increasing production of steel, the quality requirements for sinter are becoming increasingly stringent. The production of sinter mainly involves three processes: solid-phase reaction, liquid-phase generation, and condensation crystallization. Various powdered iron ores are mixed with appropriate amounts of fuel and flux, along with water. After mixing and granulation, the materials undergo a series of physicochemical changes in sintering equipment using the high temperatures generated by the fuel. This process generates some low-melting-point substances, softens and melts them to produce a certain amount of liquid phase, which wets and binds the iron mineral particles together. After cooling, a porous, blocky product with a certain strength—sinter—is formed, thus providing blast furnace smelting with an artificial rich ore having a specific particle size distribution and good metallurgical properties.

[0003] The liquid phase generated during sintering possesses a certain degree of fluidity, enabling viscous and plastic flow heat transfer, thus ensuring uniform temperature and composition in the high-temperature molten zone and homogenizing the chemical composition of the sinter after the liquid phase reaction. Calcium ferrite is the main binder liquid phase for producing high-basicity or ultra-high-basicity sinter, especially the composite calcium ferrite (SFCA) binder phase, which is optimal. The reducibility, compressive strength, and porosity of the sinter all improve with increasing ferrite content, playing a crucial role in improving the quality of the sinter.

[0004] Iron ore is mainly divided into magnetite and hematite. In hematite, the formation of calcium ferrite (SFCA) during sintering occurs earlier, typically at around 1150℃, due to the direct reaction with CaO. Magnetite sintering is more complex than hematite sintering. This is because magnetite cannot directly react with CaO to form calcium ferrite during sintering; Fe3O4 must first be oxidized to Fe2O3 before reacting with CaO to form calcium ferrite. SFCA formation during magnetite sintering primarily occurs in the cooling zone; SFCA formation is minimal before the combustion zone. Due to the very short cooling time, the amount of calcium ferrite formed is very limited.

[0005] Studies have shown that the formation of SFCA depends on sintering temperature, sintering time, sintering atmosphere, and composition. Low temperature, short sintering time, oxidizing atmosphere, and suitable alumina content are all conducive to SFCA formation. Therefore, the physicochemical reaction rate of liquid phase formation is crucial in determining the vertical sintering speed, utilization coefficient, and output of the sintering machine. It is also a major factor determining the amount, properties, and distribution of the liquid phase within the sinter, as well as the physicochemical and metallurgical properties of the sinter. Therefore, increasing the physicochemical reaction rate of liquid phase formation in the sinter and shortening the reaction time can improve the output of the sintering machine and the metallurgical properties of the sinter.

[0006] The invention patent with publication number CN101509067A discloses a composite additive for iron ore powder sintering, including a combustion aid, oxygenator, reinforcing agent, catalyst, coarse rice husk, calcium fluoride, pellet binder, and boron anhydride. The additives work synergistically to improve the vertical sintering speed and simultaneously increase the utilization coefficient of the sintering machine, thereby increasing output. However, its catalyst is a mixture of manganese dioxide and ferrocene. This catalyst has a catalytic cracking effect on the gasification and combustion of solid fuels, enabling the full and rapid combustion of solid fuels and ensuring full utilization of energy.

[0007] The invention patent with publication number CN102660349A discloses a composite sintering catalyst. The catalyst composition consists of hydroxymethyl starch, borax or boric acid, dextrin, slaked lime, calcium-based bentonite, calcium lignosulfonate or sodium lignosulfonate. This catalyst improves the thermal utilization rate of fuel, enhances the reactivity of fuel, increases the permeability of the material layer, increases the vertical sintering speed, improves the utilization coefficient of the sintering machine, and increases output. However, the catalyst composition is complex and differs from that of iron ore.

[0008] The invention patent with publication number CN109777950A discloses an ultra-low temperature sintering mineralization energy-saving additive, which includes an ultra-low temperature mineralizer (borax or boric acid), an oxygenating agent (sodium nitrate), a melting agent (fluorite or gunmetal), a catalyst (NaCl or KCl), and a pore-forming agent (perlite). The catalyst plays a role in enhancing the catalytic sintering process by catalyzing the combustion of carbon through alkali metal substances.

[0009] It is evident that the catalysts currently added to sintered ore are mainly substances such as sodium chloride, potassium chloride, sodium carbonate, and ferrocene. Their role is to catalyze and activate the combustion of fuel, thereby improving combustion efficiency, enhancing the utilization system of the sintering machine, and ultimately increasing production. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a eutectic catalyst for sintered ore. During the sintering process of iron ore, the eutectic catalyst remelts and participates in and promotes the rapid progress of the physicochemical reactions in the sintering process, thereby improving the vertical sintering speed, utilization coefficient, and output of the sintering machine, and improving the metallurgical performance indicators of sintered ore, such as low-temperature reduction pulverization and softening dripping.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention provides a eutectic catalyst for sintered ore, the eutectic catalyst containing the following components in mass percentage: CaO 10%–60%, Fe2O3 10%–60%, MgO 2%–50%, Al2O3 2%–50%, SiO2 2%–50%, Re 2%–20%.

[0013] The eutectic catalyst described in the technical solution of this invention is in powder form with a particle size of 30-150 mesh.

[0014] The eutectic catalyst described in this invention is prepared from iron ore, lime, rare earth elements, lightly calcined dolomite, and wollastonite through crushing, proportioning, mixing, melting, cooling crystallization, and crushing. The mixing and melting are carried out in an electric arc furnace, with the furnace temperature controlled between 1500℃ and 1800℃. The resulting catalyst contains various eutectic molecules such as calcium ferrite, calcium aluminate, and calcium silicate. It is worth noting that iron ore, lime, rare earth elements, lightly calcined dolomite, and wollastonite are preferred raw materials for preparing the eutectic catalyst of this invention. Those skilled in the art can also appropriately select other minerals containing the respective components of the eutectic catalyst for proportioning.

[0015] This invention provides a method for using the above-mentioned eutectic catalyst for sintered ore, comprising the following steps: the sintering catalyst is lifted into a high-level silo, and after being electronically weighed and automatically fed in the high-level silo, it is added to the main belt conveyor and mixed with other sintering materials on the conveyor. The mixture is then conveyed into a mixer for homogenization, and the homogenized sintering material is conveyed into a granulator for secondary homogenization and granulation. The granulated sintering material is arranged on the sintering machine by a material distributor and enters the sintering process as the sintering machine operates.

[0016] In the technical solution of this invention, the amount of eutectic catalyst used for sintered ore accounts for 1% to 2.5% of the mass of the other sintered materials.

[0017] It is worth noting that the eutectic catalyst for sintered ore of the present invention is applicable to ordinary sintered ore and vanadium-titanium magnetite. The amount of iron ore powder, lime, rare earth, lightly calcined dolomite and wollastonite raw materials needs to be adjusted according to the specific sintering conditions to ensure that each component in the eutectic catalyst is within a suitable range. In particular, the technical and economic indicators of vanadium-titanium magnetite sintering production are significantly different from those of ordinary sintered ore, and the control of the components in its eutectic catalyst is more stringent.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention incorporates a eutectic catalyst into the sintering material. During sintering, the eutectic catalyst remelts, participating in and promoting the rapid physicochemical reactions, thereby increasing the vertical sintering speed, utilization coefficient, and output of the sintering machine. It also improves the metallurgical properties of the sinter, such as low-temperature reduction pulverization and softening dripping, and enhances the permeability of the sinter within the blast furnace. Particularly in the sintering of vanadium-titanium magnetite, the eutectic catalyst melts and reacts with titanium dioxide and perovskite to form a low-melting-point, highly fluid oxide eutectic liquid phase. This liquid phase diffuses and melts more surrounding solid phases, accelerating the solid-liquid conversion rate, thus increasing the vertical sintering speed, utilization coefficient, and output of the vanadium-titanium magnetite sintering machine, and improving the low-temperature reduction pulverization and softening dripping properties of the vanadium-titanium sinter. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the fabrication process of the eutectic catalyst of the present invention. Detailed Implementation

[0021] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the test methods in the following embodiments are conventional methods.

[0022] Example 1

[0023] The actual production conditions of a typical sintering plant are as follows: The test equipment is a fully automatic sintering cup with a loading capacity of 120kg per furnace. The sources and proportions of the sintering materials used in this plant, by mass percentage, are as follows: Indian Delta powder 7.26%, mixed powder 7.865%, high-silicon Taigang concentrate 3.63%, 65% Daixian powder 6.655%, Fushan concentrate 4.84%, Indonesian Zhoushan Hai powder 7.26%, PB powder Shennv powder 12.1%, Erlian concentrate 1.815%, miscellaneous materials 3.025%, Bacu Dabodo powder 4.235%, SP10 Haidewei powder 1.815%, dust collector 3%, quicklime 5.5%, dolomite powder 3%, coke powder 3.5%, stone powder 1.5%, and recycled ore 23%, etc. By mass percentage, the main components of the above raw materials after secondary mixing, granulation and sintering in sintering cups are: grade 56.36%, FeO 9.52%, CaO 10.85%, SiO2 5.12%, MgO 2.45%, Al2O3 2.10%, S 0.02%, P 0.067%, MnO 0.4484%, K2O 0.0657%, Na 0.056%, basicity (R) 2.12, etc.

[0024] Based on this, the eutectic catalyst of this invention was designed and manufactured. Taking 1 ton of eutectic catalyst as an example, the required materials for eutectic catalyst sample No. 1 are 400 kg of iron ore, 400 kg of lime, 160 kg of lightly calcined dolomite, 20 kg of rare earth elements, and 20 kg of wollastonite. The main components and contents of the iron ore are as follows: TFe 63.01%, SiO2 7.14%, CaO 0.87%, MgO 0.75%, Al2O3 2.10%; the main components and contents of the lime are: CaO 85.74%, SiO2 2.99%, MgO 1.86%, Al2O3 2.33%; the rare earth (Re) source is Baotou, Inner Mongolia, with Nd 95.1% as the main component; the main components and contents of the lightly calcined dolomite are as follows: CaO 44.71%, MgO 32.04%, SiO2 1.20%, Al2O3 4.36%; the wollastonite source is Lishu, Jilin, with CaO 42.71%, SiO2 48.52%, MgO 1.04%, Al2O3 1.18%.

[0025] like Figure 1 The schematic diagram of the production process shows that the above raw materials are weighed and crushed to a particle size of 5mm-45mm. After mixing the raw materials, they are fed into an electric arc furnace, ignited by electric current, melted for 8 hours, cooled and crystallized, and then crushed to obtain eutectic catalyst sample No. 1 with a mesh size of 30-150. The mineral raw material ratio is adjusted, and eutectic catalyst samples No. 2, No. 3, and No. 4 are prepared according to the above procedure. The components and percentage content of the obtained eutectic catalyst samples No. 1 to No. 4 are shown in Table 1.

[0026] Table 1. Components and percentage content of eutectic catalyst samples 1-4

[0027] serial number CaO, % Fe203, % MgO, % <![CDATA[Al2O3,%]]> <![CDATA[SiO2,%]]> Nd, % total,% 1 45.11 38.07 6.55 2.64 5.51 2.12 100 2 40.18 42.62 6.29 2.59 5.85 2.47 100 3 35.72 47.18 6.31 2.58 5.90 2.31 100 4 30.16 52.21 6.36 2.56 6.36 2.25 100

[0028] The above four different formulations of eutectic catalysts were added to the sintering material of the plant at 2% and 3% of the mass of the sintering material, respectively. The ignition temperature of the sintering cup was 950℃~1100℃. Other matters were carried out in accordance with the normal operating procedures of the sintering cup. The evaluation indicators were vertical sintering speed, drum rotation, and the 500℃ low-temperature reduction index RDI (+6.3, +3.15 and -0.5), as detailed in Table 2 below.

[0029] Table 2. Experimental results of adding different eutectic catalysts to ordinary iron ore.

[0030]

[0031]

[0032] As shown in Table 2, after adding the eutectic catalyst of this invention to the original sintering material, the vertical sintering speed increased by an average of 12.75%; the low-temperature reduction indices RDI (+6.3) and RDI (+3.15) of the sinter increased by an average of 17.37% and 10.2%, respectively, while RDI (-0.5) decreased by an average of 3.14%; and the drum strength index increased by 1.21%. In summary, by adding the eutectic catalyst of this invention, the quality of the sinter and the technical and economic indicators of sintering production were significantly improved.

[0033] Example 2

[0034] The actual production conditions of a vanadium-titanium magnetite sintering plant are as follows: The test equipment is a sintering cup with a loading capacity of 80 kg per furnace.

[0035] The plant produces vanadium-titanium ore in three proportions daily: 46-base, 53-base, and 60-base. The raw materials and their weights (kg) for the 46-base batch in each sintering cup are as follows: Baiquan 63.5kg, vanadium powder 2.08kg, Sijiaying ordinary powder 10kg, PB 8kg, miscellaneous materials 3.68kg, Chilean powder 5.28kg, KR powder 6.96kg, Yuantong 65 vanadium powder 11.36kg, 63.5 vanadium powder 5.28kg, coal 3.52kg, magnesium 0.72kg, self-return 16.96kg, and quicklime 6.22kg. The raw material sources and weights (kg) for each sintering cup with 53 base components are as follows: Baiquan 63.5kg, vanadium powder 2.16kg, Sijiaying ordinary powder 10.16kg, PB 6kg, miscellaneous materials 3.76kg, KR powder 5.44kg, Yuantong 65 vanadium powder 13.12kg, 63.5 vanadium powder 12.88kg, coal 3.44kg, magnesium 0.72kg, self-return 16.48kg, quicklime 5.20kg. The raw material sources and weights (kg) for each sintering cup with 60 base components are as follows: Baiquan 63.5kg, vanadium powder 2.16kg, Sijiaying ordinary powder 10.24kg, miscellaneous materials 3.76kg, KR powder 7.68kg, Yuantong 65 vanadium powder 14.8kg, 63.5 vanadium powder 15.04kg.

[0036] The utilization coefficient of the vanadium-titanium magnetite sintering machine and the low-temperature reduction pulverization index (RDI+3.15) of the sinter are both low.

[0037] Based on this, the eutectic catalyst of the present invention was designed and manufactured. Taking 1 ton of eutectic catalyst as an example, the required raw materials are 400 kg of iron ore, 400 kg of lime, 160 kg of lightly calcined dolomite, 20 kg of rare earth elements, and 20 kg of wollastonite. The main components and contents of the above raw materials are the same as in Example 1.

[0038] like Figure 1The schematic diagram of the production process shows that the above raw materials are weighed and crushed to a particle size of 5mm-45mm. After mixing the raw materials, they are fed into an electric arc furnace, ignited by electric current, melted for 8 hours, cooled and crystallized, and then crushed to obtain eutectic catalyst sample No. 5 with a mesh size of 30-150. The mineral raw material ratio is adjusted, and eutectic catalyst sample No. 6 is prepared according to the above procedure. The components and percentage content of the obtained eutectic catalyst samples No. 5 and No. 6 are shown in Table 3.

[0039] Table 3. Components and percentage content of eutectic catalyst samples 5-6

[0040] serial number CaO, % <![CDATA[Fe2O3,%]]> MgO, % <![CDATA[Al2O3,%]]> <![CDATA[SiO2,%]]> Nd, % total,% 5 42.11 40.07 8.55 2.03 3.71 3.53 100 6 40.18 41.62 8.22 2.59 3.83 3.56 100

[0041] The two different formulations of eutectic catalysts were added to the vanadium-titanium magnetite sinter. Schemes 10-12 were reference samples with 46, 53, and 60 catalysts respectively, without any eutectic catalyst. Schemes 13-16 were reference samples with different eutectic catalysts added. Scheme 13 added 1.2% (0.96 kg) of eutectic catalyst No. 5, Scheme 14 added 2% (1.6 kg) of eutectic catalyst No. 6, Scheme 15 added 1.5% (1.2 kg) of eutectic catalyst No. 6, and Scheme 16 added 1.2% (0.96 kg) of eutectic catalyst No. 5.

[0042] The ignition temperature of the sintering cup is 900℃~1100℃. Other matters shall be carried out in accordance with the normal operating procedures of the sintering cup. The assessment indicators are vertical sintering speed, utilization coefficient, 500℃ low temperature reduction index RDI (+3.15) and yield, as detailed in Table 4 below.

[0043] Table 4. Experimental results of adding different eutectic catalysts to vanadium-titanium magnetite.

[0044]

[0045] As shown in Table 4, adding the eutectic catalyst of this invention to the original vanadium-titanium sinter increased the vertical sintering speed of the vanadium-titanium sinter by an average of 17.63%, the utilization coefficient of the sintering machine by an average of 25.36%, the low-temperature reduction pulverization index RDI (+3.15) at 500℃ by an average of 8.88%, and the yield by an average of 1.51%. In summary, by adding the eutectic catalyst of this invention, the quality indicators of vanadium-titanium sinter and the technical and economic indicators of sintering production were significantly improved.

[0046] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A method for preparing a eutectic catalyst for sintered ore, characterized in that, The eutectic catalyst contains the following components by mass percentage: CaO 10%~60%, Fe2O3 10%~60%, MgO 2%~50%, Al2O3 2%~50%, SiO2 2%~50%, and rare earth Re 2%~20%. The eutectic catalyst is prepared from iron ore, lime, rare earth, lightly calcined dolomite, and wollastonite through crushing, proportioning, mixing, melting, cooling crystallization, and crushing. The mixing and melting are carried out in an electric arc furnace, and the furnace temperature is controlled at 1500~1800℃.

2. The method for preparing a eutectic catalyst for sintered ore according to claim 1, characterized in that, The eutectic catalyst is in powder form with a particle size of 30-150 mesh.

3. A method for using a eutectic catalyst for sintered ore, characterized in that, The process includes the following steps: after the eutectic catalyst for sintered ore prepared by the preparation method according to any one of claims 1 to 2 is mixed evenly with other sintering materials, it is fed into a granulator for secondary mixing and granulation. The granular sintering materials are arranged on the sintering machine and enter the sintering process as the sintering machine is running.

4. The method of using a eutectic catalyst for sintered ore according to claim 3, characterized in that, The amount of the eutectic catalyst used in the sintered ore accounts for 1% to 2.5% of the mass of the other sintered materials.

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