Electric furnace melt separation treatment and flue gas recycling process for low-grade ferrotitanium concentrate

Abstract

The invention relates to the technical field of ferrotitanium concentrate, in particular to a low-grade ferrotitanium concentrate electric furnace melt separation treatment and flue gas recycling process. The technology comprises the steps of raw material preparation, ore blending and burdening, electric furnace smelting reduction, titanium slag treatment and molten iron treatment, in the low-grade titanium-iron concentrate electric furnace smelting separation treatment and flue gas recycling technology, by controlling the use of the proportion of low-grade titanium-iron concentrate, high-grade titanium concentrate, coke nut and semi-coke, low-grade titanium-iron concentrate resources are fully utilized, resource waste is avoided, and the cost is reduced. The high-quality titanium slag with the Ti2O5 content of 75% or above is finally obtained by adopting an ore and carbon blending smelting mode, in addition, high-temperature coal gas is converted into available energy through a series of flue gas recycling processes of cooling, dust removal treatment, re-cooling, storage and transportation and combustion steam production, the energy utilization rate is greatly increased, the energy can be stably supplied to downstream users, and the energy utilization rate is increased. And the production stability and flexibility are enhanced, so that the comprehensive benefits of the whole process are improved.

Description

Technical Field

[0001] The invention relates to the technical field of ilmenite concentrate, and in particular to a process for electric furnace smelting and fractionation of low-grade ilmenite concentrate and for recycling flue gas. Background Art

[0002] In the field of ilmenite concentrate processing, low-grade ilmenite concentrate is a common product in the mineral processing process of mines. Low-grade ilmenite concentrate resources are relatively abundant, but due to its low grade, the traditional electric furnace smelting process often has some problems when processing low-grade ilmenite concentrate. For example: due to the characteristics of low-grade ilmenite concentrate itself, after electric furnace smelting, it is easy to have a high degree of FeO reduction, which will directly lead to a decrease in the grade of titanium slag, and then lead to low economic benefits of titanium slag; At the same time, a large amount of high-temperature coal gas will be generated during the electric furnace smelting process; these high-temperature coal gases usually carry a large amount of heat and dust. If a large amount of high-temperature coal gas is directly discharged into the environment, it will cause a waste of energy, and the dust and other pollutants carried in it will also cause pollution to the environment. In addition, the high-temperature coal gas may also contain some harmful gas components, which not only reduces the utilization rate of energy and increases production costs, but also reduces the stability and flexibility of production, thereby causing economic losses.

[0003] In view of this, there is an urgent need for an electric furnace smelting process for low-grade ilmenite concentrate and a fume recovery and utilization process. Summary of the invention

[0004] The object of the present invention is to provide a process for electric furnace smelting and fume recovery of low-grade ilmenite concentrate to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, on the one hand, the present invention provides a low-grade ilmenite concentrate electric furnace smelting process, comprising the following steps: S1.1. Raw material preparation: low-grade ilmenite concentrate, high-grade ilmenite concentrate, coke and semi-coke; S1.2, ore blending and batching: low-grade ilmenite concentrate and high-grade titanium concentrate are blended with ore blending equipment to form mixed titanium ore; coke and semi-coke are then blended to form a mixed reducing agent; thereafter, the mixed titanium ore and the mixed reducing agent are stirred and mixed with a stirring device; S1.3, electric furnace smelting reduction: the uniformly mixed materials are added to the titanium slag smelting electric furnace at a uniform speed, and then the electric furnace is powered on to increase the temperature for smelting, and the FeO in the mixture begins to be solid-phase reduced, and the temperature is continued to be increased to perform deep reduction of FeO and other oxides. The deeply reduced materials gradually melt during the continued heating and temperature increase process, and during the melting process of the materials, the high-temperature molten iron and the slag liquid are separated due to the difference in density, and titanium slag is obtained at the upper part of the molten pool, and molten iron is obtained at the bottom. At the same time, a large amount of high-temperature coal gas will be generated during the reduction process in the closed electric furnace; S1.4, titanium slag treatment: titanium slag is discharged from the slag port of the electric furnace and connected to the slag basin. The inner wall of the slag basin is built with high temperature resistant materials. Then, the high temperature slag liquid in the slag basin is treated by water spray cooling. The cooled titanium slag is crushed by multi-stage crushing equipment, and then the crushed titanium slag is screened to obtain titanium slag with a Ti2O5 content of more than 75%; S1.5. Treatment of molten iron: After being discharged from the iron mouth, the high-temperature molten iron is connected to the ladle, which is then transported to the LF furnace by a ladle car. An oxidant is added to the molten iron to remove impurities in the molten iron. Subsequently, a reducing agent is added to the molten steel to reduce the oxides to pure metals. A stirring device is then used to stir the molten iron to make the composition of the molten iron uniform. At the same time, the scum formed on the surface of the molten iron is removed to obtain pure molten iron. The pure molten iron is then added to the cast iron machine, where it can be cast into iron blocks.

[0006] As a further improvement of the present technical solution, in S1.1, the low-grade ilmenite concentrate includes at least TiO2, and the content of TiO2 is 35.28%; the high-grade titanium concentrate includes at least TiO2, and the content of TiO2 is 47.86%; the coke includes at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.5%; the lignite includes at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.3%.

[0007] As a further improvement of the technical solution, in S1.2, the weight ratio of the low-grade ilmenite concentrate to the high-grade ilmenite concentrate is 5:5, the grade of the mixed ilmenite is greater than 44%; and the total amount of ilmenite is greater than 90%.

[0008] As a further improvement of the technical solution, in S1.2, the weight ratio of the mixture of diced coke and lignite is 5:5, the fixed carbon of the mixed reducing agent is greater than 84%, and the carbon ratio of lignite is not greater than 50%.

[0009] As a further improvement of the technical solution, in S1.2, the weight ratio of the mixed titanium ore to the mixed reducing agent is 100:10-14.

[0010] As a further improvement of the technical solution, in S1.3, when the mixed material is added, it is added into the furnace in small amounts and in multiple batches.

[0011] As a further improvement of the technical solution, in S1.3, when the temperature of the electric furnace is raised by power supply and exceeds 800°C, solid phase reduction begins, and the temperature of the electric furnace continues to rise to above 1350°C for deep reduction.

[0012] On the other hand, the present invention provides a fume recovery and utilization process for low-grade ilmenite concentrate electric furnace smelting treatment, comprising recycling the high-temperature coal gas generated by the above-mentioned low-grade ilmenite concentrate electric furnace smelting treatment, and using it to produce steam after dust removal and cooling. The specific recycling process steps are as follows: S2.1. Cooling: The high-temperature gas is first cooled through a water-cooled flue; S2.2. Dust removal: Remove dust from coal gas by combining two-stage gravity dust removal with a first-stage high-temperature metal film fine dust collector to reduce the dust content of coal gas to less than 30mg / m³; S2.3, re-cooling: the gas after dust removal is cooled to below 50℃ by air cooling; S2.4, Storage and transportation: The gas after cooling and dust removal is transported to the gas tank for temporary storage; S2.5. Combustion to produce steam: The gas in the gas tank is transported to the gas boiler through a compressor to burn and produce steam.

[0013] As a further improvement of the technical solution, in S2.1, the temperature of the high-temperature coal gas is 900°C-1000°C, and the water-cooled flue is used to cool the gas down to 500°C-600°C.

[0014] As a further improvement of the present technical solution, in S2.5, the gas boiler adopts a mixed gas combustion boiler.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the process of electric furnace smelting and flue gas recovery of low-grade ilmenite concentrate, the low-grade ilmenite concentrate produced by mine dressing is blended with high-grade ilmenite concentrate in a ratio of 5:5, so as to make full use of the low-grade ilmenite concentrate resources and avoid its idle waste. At the same time, in terms of reducing agent, the relatively low-priced semi-coke and coke are blended in a ratio of 5:5 to form a mixed reducing agent, and the carbon ratio of semi-coke is controlled to be no more than 50%, and the fixed carbon of the mixed reducing agent is greater than 84%, which improves the reduction effect and reduces the cost of the reducing agent. In addition, a quantitative blending and carbon blending smelting method is adopted to finally obtain high-quality titanium slag with a Ti2O5 content of more than 75%, which can be supplied to downstream users producing titanium dioxide, sponge titanium and other products, which is beneficial to the utilization of raw materials, and effectively reduces the production cost while increasing the added value of low-grade ilmenite concentrate, thereby improving the comprehensive benefits of the entire process.

[0016] 2. In the electric furnace smelting and flue gas recovery process of the low-grade ilmenite concentrate, a large amount of high-temperature coal gas will be generated in the closed electric furnace during the smelting process. The high-temperature coal gas is converted into usable energy through a series of flue gas recovery processes such as cooling, dust removal, re-cooling, storage and transportation, and combustion to produce steam, which greatly improves the energy utilization rate. Moreover, the gas boiler adopts a mixed gas combustion boiler, which can flexibly burn coal gas, natural gas or a mixture of the two. Even when there is a shortage of coal gas, steam production can be guaranteed, and a stable supply can be provided to downstream users, which enhances the stability and flexibility of production, is conducive to improving energy utilization efficiency, achieving energy conservation and emission reduction, and thus increasing economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a process flow chart of the electric furnace smelting treatment of low-grade ilmenite concentrate and fume recovery and utilization. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] according to Figure 1 As shown, the embodiment of the present invention provides an electric furnace smelting process for low-grade ilmenite concentrate, comprising the following steps: Step 1: Raw material preparation: low-grade ilmenite concentrate, high-grade ilmenite concentrate, coke and semi-coke; including: Low-grade ilmenite concentrate contains at least TiO2, and the content of TiO2 is 35.28% (see Table 1); high-grade ilmenite concentrate contains at least TiO2, and the content of TiO2 is 47.86% (see Table 2); coke contains at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.5% (see Table 3); semi-coke contains at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.3% (see Table 4); Table 1 Chemical composition of low-grade ilmenite concentrate (wt-%) Table 2 Chemical composition of high-grade titanium concentrate (wt-%) Table 3 Chemical composition of coke diced wt-% Table 4 Chemical composition of semi-carbon wt-% Step 2, ore blending and batching: using ore blending equipment to mix low-grade ilmenite concentrate with high-grade ilmenite concentrate to form mixed ilmenite, the weight ratio of low-grade ilmenite concentrate to high-grade ilmenite concentrate is 5:5, the grade of mixed ilmenite is greater than 44%; the total amount of ilmenite is greater than 90%; then, coke and semi-coke are mixed to form a mixed reducing agent, the weight ratio of coke and semi-coke is 5:5, the fixed carbon of the mixed reducing agent is greater than 84%, and the carbon ratio of semi-coke is not greater than 50%; then, the mixed ilmenite and the mixed reducing agent are stirred and mixed using a stirring device, the weight ratio of the mixed ilmenite to the mixed reducing agent is 100:10-14, to reduce material segregation; Step 3, electric furnace smelting reduction: the mixed material is uniformly added to the titanium slag smelting electric furnace. When the mixed material is added, it is added into the furnace in small amounts and in multiple batches to prevent the material from piling up in the furnace. Then the electric furnace is powered on and heated for smelting. The FeO in the mixture begins to be solid-phase reduced. The temperature of the electric furnace exceeds 800°C and solid-phase reduction begins. The temperature is continued to be raised. The electric furnace continues to be heated to more than 1350°C for deep reduction. The deep reduction of FeO and other oxides is carried out. The deeply reduced material gradually melts during the continued heating and temperature raising process. During the melting process of the material, the high-temperature molten iron and the slag liquid are separated due to the difference in density. Titanium slag is obtained at the upper part of the molten pool and molten iron is obtained at the bottom. At the same time, a large amount of high-temperature coal gas will be generated during the reduction process in the closed electric furnace. Step 4, titanium slag treatment: After the titanium slag is discharged from the slag port of the electric furnace, it is connected to the slag basin. The inner wall of the slag basin is built with high-temperature resistant materials so that the slag basin can withstand the impact of high-temperature slag liquid. Then, the high-temperature slag liquid in the slag basin is treated by water spray cooling so that the slag liquid can be evenly cooled, effectively avoiding the slag body from being broken due to rapid cooling. The cooled titanium slag is crushed using multi-stage crushing equipment, and then the crushed titanium slag is screened to obtain titanium slag with a Ti2O5 content of more than 75% (see Table 5). This high-quality titanium slag can be used as an important raw material for the production of titanium dioxide and sponge titanium downstream products; Table 5 Titanium slag chemical composition detection wt-% Step 5, molten iron treatment: After the high-temperature molten iron is discharged from the iron mouth, it is connected to the ladle. The ladle is preheated to 800℃-1000℃ in advance to reduce the heat loss of the molten iron. The ladle filled with molten iron is transported to the LF furnace by a ladle car. An oxidant (such as iron oxide) is added to the molten iron to remove impurities in the molten iron, such as sulfur and phosphorus. Subsequently, a reducing agent is added to the molten steel (the reducing agent is not a mixed reducing agent formed by mixing coke and semi-coke, and the reducing agent is such as ferrosilicon) to reduce the oxide to pure metal to improve the quality of the molten iron. Then, a stirring device is used to stir the molten iron to make the composition of the molten iron uniform. At the same time, the scum formed on the surface of the molten iron is removed to obtain pure molten iron (see Table 6). Then, the pure molten iron is added to the cast iron machine, where it can be cast into iron blocks, which are used as raw materials in the steel plant.

[0020] Table 6 Chemical composition of molten iron wt-% according to Figure 1 As shown, the embodiment of the present invention also provides a fume recovery and utilization process for low-grade ilmenite concentrate electric furnace smelting treatment, including recycling the high-temperature coal gas generated by the low-grade ilmenite concentrate electric furnace smelting treatment, and using it to produce steam after dust removal and cooling. The specific recycling process steps are as follows: (1) Cooling: The high-temperature gas is first cooled by a water-cooled flue. The temperature of the high-temperature gas is 900℃-1000℃, and the water-cooled flue cools it down to 500℃-600℃; (2) Dust removal: The dust in the coal gas is removed by combining two-stage gravity dust removal with a first-stage high-temperature metal film fine dust collector to reduce the dust content of the coal gas to less than 30 mg / m³; (3) Second cooling: The gas after dust removal is cooled by air to below 50°C; (4) Storage and transportation: The gas after cooling and dust removal (see Table 7) is transported to the gas tank for temporary storage; Table 7 Gas chemical composition detection wt-% (5) Combustion to produce steam: The gas in the gas tank is transported to the gas boiler through a compressor to burn and produce steam. The gas boiler adopts a mixed gas combustion boiler, which can burn coal gas, natural gas, or a mixture of coal gas and natural gas. It is convenient to produce steam when there is a shortage of coal gas and supply it to downstream users.

[0021] In the invention, firstly, low-grade ilmenite concentrate and high-grade titanium concentrate are mixed in proportion, and coke and lignite are made into a mixed reducing agent in proportion, and then mixed with the mixed titanium ore in proportion, and then the evenly mixed materials are added to the titanium slag smelting electric furnace in small quantities and multiple batches for smelting reduction. This not only can achieve slag and iron separation to obtain high-quality titanium slag that can be used to produce titanium dioxide and sponge titanium downstream products, but also in the smelting process, a series of flue gas recovery and utilization processes such as cooling and cooling the high-temperature coal gas, dust removal, re-cooling, storage and transportation, and transportation to the gas boiler for combustion and steam production can effectively improve energy utilization and increase economic benefits. In addition, the gas boiler adopts a mixed gas combustion boiler, which is convenient for ensuring steam production when coal gas is short, and supplying it to downstream users, thereby enhancing production stability and flexibility.

[0022] By blending the low-grade ilmenite concentrate produced by mine dressing with the high-grade ilmenite concentrate in a ratio of 5:5, the low-grade ilmenite concentrate resources are fully utilized and their idle waste is avoided. At the same time, in terms of reducing agent, the lower-priced lignite and coke are mixed in a ratio of 5:5 to make a mixed reducing agent, and the carbon ratio of lignite is controlled to be no more than 50%, and the fixed carbon of the mixed reducing agent is greater than 84%, which improves the reduction effect and reduces the cost of the reducing agent. In addition, a quantitative ore blending and carbon blending smelting method is adopted to finally obtain high-quality titanium slag with a Ti2O5 content of more than 75%, which can be supplied to downstream users who produce titanium dioxide, sponge titanium and other products, which is beneficial to the utilization of raw materials. While increasing the added value of low-grade ilmenite concentrate, it effectively reduces the production cost, thereby improving the overall benefit of the entire process.

[0023] During the smelting process, a large amount of high-temperature coal gas will be generated in the closed electric furnace. Through a series of flue gas recovery and utilization processes such as cooling, dust removal, re-cooling, storage and transportation, and combustion to produce steam, the high-temperature coal gas is converted into usable energy, which greatly improves the energy utilization rate. Moreover, the gas boiler adopts a mixed gas combustion boiler, which can flexibly burn coal gas, natural gas or a mixture of the two. Even when there is a shortage of coal gas, steam production can be guaranteed, and a stable supply to downstream users can be provided, which enhances the stability and flexibility of production, is conducive to improving energy utilization efficiency, achieving energy conservation and emission reduction, and thus increasing economic benefits.

[0024] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-grade ilmenite concentrate electric furnace smelting treatment, characterized in that: The following steps are involved: S1.

1. Raw material preparation: low-grade ilmenite concentrate, high-grade ilmenite concentrate, coke and semi-coke; S1.2, ore blending and batching: low-grade ilmenite concentrate and high-grade titanium concentrate are blended with ore blending equipment to form mixed titanium ore; coke and semi-coke are then blended to form a mixed reducing agent; thereafter, the mixed titanium ore and the mixed reducing agent are stirred and mixed with a stirring device; S1.3, electric furnace smelting reduction: the uniformly mixed materials are added to the titanium slag smelting electric furnace at a uniform speed, and then the electric furnace is powered on to increase the temperature for smelting, and the FeO in the mixture begins to be solid-phase reduced, and the temperature is continued to be increased to perform deep reduction of FeO and other oxides. The deeply reduced materials gradually melt during the continued heating and temperature increase process, and during the melting process of the materials, the high-temperature molten iron and the slag liquid are separated due to the difference in density, and titanium slag is obtained at the upper part of the molten pool, and molten iron is obtained at the bottom. At the same time, a large amount of high-temperature coal gas will be generated during the reduction process in the closed electric furnace; S1.4, titanium slag treatment: titanium slag is discharged from the slag port of the electric furnace and connected to the slag basin. The inner wall of the slag basin is built with high temperature resistant materials. Then, the high temperature slag liquid in the slag basin is treated by water spray cooling. The cooled titanium slag is crushed by multi-stage crushing equipment, and then the crushed titanium slag is screened to obtain titanium slag with a Ti2O5 content of more than 75%; S1.

5. Treatment of molten iron: After being discharged from the iron mouth, the high-temperature molten iron is connected to the ladle, which is then transported to the LF furnace by a ladle car. An oxidant is added to the molten iron to remove impurities in the molten iron. Subsequently, a reducing agent is added to the molten steel to reduce the oxides to pure metals. A stirring device is then used to stir the molten iron to make the composition of the molten iron uniform. At the same time, the scum formed on the surface of the molten iron is removed to obtain pure molten iron. The pure molten iron is then added to the cast iron machine, where it can be cast into iron blocks.

2. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In the S1.1, the low-grade ilmenite concentrate includes at least TiO2, and the content of TiO2 is 35.28%; the high-grade titanium concentrate includes at least TiO2, and the content of TiO2 is 47.86%; the chopped coke includes at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.5%; the lignite includes at least fixed carbon Fcd, and the content of fixed carbon Fcd is 82.3%.

3. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In S1.2, the weight ratio of low-grade ilmenite concentrate to high-grade ilmenite concentrate is 5:5, the grade of the mixed ilmenite is greater than 44%; and the total amount of ilmenite is greater than 90%.

4. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In S1.2, the weight ratio of coke and semi-coke is 5:5, the fixed carbon content of the mixed reducing agent is greater than 84%, and the carbon content of semi-coke is no greater than 50%.

5. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In S1.2, the weight ratio of the mixed titanium ore to the mixed reducing agent is 100:10-14.

6. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In S1.3, when the mixed material is added, it is added into the furnace in small amounts and in multiple batches.

7. The electric furnace smelting process of low-grade ilmenite concentrate according to claim 1, characterized in that: In S1.3, the electric furnace is powered on and the temperature rises to over 800°C to start solid phase reduction, and the electric furnace continues to rise in temperature to over 1350°C for deep reduction.

8. A process for recycling flue gas from electric furnace smelting of low-grade ilmenite concentrate, characterized in that: The method comprises recycling the high-temperature coal gas generated by the electric furnace smelting treatment of the low-grade ilmenite concentrate as described in claim 1, removing dust and cooling it, and using it to produce steam. The specific recycling process steps are as follows: S2.

1. Cooling: The high-temperature gas is first cooled through a water-cooled flue; S2.

2. Dust removal: Remove dust from coal gas by combining two-stage gravity dust removal with a first-stage high-temperature metal film fine dust collector to reduce the dust content of coal gas to less than 30mg / m³; S2.3, re-cooling: the gas after dust removal is cooled to below 50℃ by air cooling; S2.4, Storage and transportation: The gas after cooling and dust removal is transported to the gas tank for temporary storage; S2.

5. Combustion to produce steam: The gas in the gas tank is transported to the gas boiler through a compressor to burn and produce steam.

9. The process for recycling flue gas from electric furnace smelting of low-grade ilmenite concentrate according to claim 8, characterized in that: In S2.1, the temperature of the high temperature coal gas is 900°C-1000°C, and the water-cooled flue is used to cool the gas to 500°C-600°C.

10. The process for recycling flue gas from electric furnace smelting of low-grade ilmenite concentrate according to claim 8, characterized in that: In S2.5, the gas boiler is a mixed gas combustion boiler.

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