Ferro-titanium is widely used in iron and steel production and can be used as a deoxidizer, denitrifier, and alloy additive. The main factors affecting the recovery rate are as follows:
First, the raw material factors The higher the grade of titanium concentrate and rutile, the better the smelting effect, more iron, TI alloy content is high; when the grade of rutile is more than 90%, the grade of titanium concentrate is more than 50%, the recovery The rate is higher; the sand mine is better than the original ore smelting effect. The higher the ratio of FEO/FE2O3 in the titanium concentrate, the better the roasting effect before smelting and the better the economic and technical indicators. The particle size of titanium concentrate and rutile should be appropriate, and the loss due to overflying rules increases; overcoarse, and the reaction of aluminum heat is insufficient, and the recovery rate decreases; therefore, the particle size of rutile is generally controlled at 100-160 mesh, and the particle size of titanium concentrate is controlled at 40-100 mesh. The proportion of titanium concentrate and rutile should be kept around 3.5:1. The roasting temperature is generally controlled at 750°C-850°C, and the roasting time is 3-5H. The insufficient roasting temperature and the short time will affect the unit thermal effect and the reduction reaction fully, and have an adverse effect on the recovery rate.
For the production of ferro-titanium, the higher its grade, the more favorable it is to the reduction reaction. Generally, more than 98% of aluminum is used. The particle size of ** will affect the speed of chemical reaction and the utilization of aluminum, ** too coarse, small specific surface area, long interface chemical reaction, is not conducive to heat concentration, and slag iron is not easy to separate, less iron out ** Too fine, flying and burning loss increase, at the same time, the amount of alumina in the fine ** increases, resulting in insufficient aluminum, affecting the reduction of titanium; appropriate ** particle size is generally 60 mesh -1.5MM, accounting for more than 90%.
Lime is used as a flux in the charge, which can reduce the melting point of the slag, improve the fluidity of the slag, promote the sinking of the metal suspended substance, and prevent the combination of TIO and AL2O3, which is beneficial to increase the recovery rate of titanium. Lime contains CAO to be high, particle size 1-2MM, not using unburnt and powdered lime. The amount of lime to be added should be appropriate, the amount should not be too large, too much heat in the reduction process to consume too much, reducing the maximum temperature to reach the system, making the reaction difficult.
The silicon in ferrosilicon combines with titanium in the alloy to form TI5SI3 and other compounds, preventing the formation of aluminum compounds, reducing the amount of aluminum entering the alloy, and improving the utilization of aluminum, thereby facilitating the improvement of TI recovery. The silicon-iron powder containing about 75% silicon and the particle size of 0-1 MM is more advantageous for smelting titanium-iron.
Second, the unit thermal effect of the unit of thermal effects are: 1) the heat of the chemical reaction of the charge; 2) the physical heat brought into the charge. The heat of chemical reaction is mainly determined by the grades and ingredients of materials such as titanium concentrates, rutile, and cesium, and the physical heat is mainly determined by the calcination temperature of titanium concentrate and rutile. Production practice shows that the unit calorific value is low, the reduction reaction is difficult to carry out, the slag has poor fluidity, there are many metal balls containing TI in the slag, the slag iron is not easy to separate, the iron output is small; the unit calorific value is high, the reaction is fierce, and the slag stirring causes Splattering, process loss, low output.
Third, the aluminum coefficient from the test that the recovery rate of titanium with the increase in the amount of aluminum, but the amount of aluminum will reduce the reaction unit of thermal effects, making the slag thicker, but also easily lead to excessive aluminum alloy content, Affect product quality. Therefore, in order to obtain a higher recovery rate of titanium, the amount of aluminum must be controlled within an optimal range. Tests have shown that when the aluminum distribution coefficient is 1.03-1.06, the TTI in the slag is lower, and the aluminum content in the finished product conforms to GB3282- 87 requirements, the best smelting effect.
Fourth, the feeding speed of the material feeding process should follow the "first slow, intermediate fast, last slow" principle; the end of the reaction is completed when adding the main material, the material should be slow, until the molten pool is increased and then increase the feeding rate, the appropriate speed should be The reaction is rapid and uniform, and the reaction should be slowed down in the later period of the reaction to prevent the reaction from becoming overly aggressive and causing splashing. Appropriate feeding rate will help the concentration of heat, iron sedimentation, iron output increased. Feeding too fast and easy to spray slag, the alloy contains low titanium, the high content of aluminum contains too little heat, the heat loss is large, and the amount of iron is low. Finally, we must pay attention to uniform feeding, to prevent the feed rate changes too much or stop feeding to make the alloy slag. Production practice shows that the total amount of charging material is 8T, and the blanking time is controlled at 9-12MIN.
Fifth, the refining material is also known as precipitant. The purpose of adding the refining material is to increase the slag temperature and enhance the fluidity of the slag, so that the titanium-iron metal particles can be easily settled from the slag; at the same time, the iron droplets produced by the reaction of the refining material go from the top to the bottom. After passing through the slag layer, the metal beads suspended in the slag layer containing higher TI and smaller specific gravity can be brought into the molten pool, thereby increasing the titanium recovery rate. At the end of the smelting reaction, with the thickening of the slag layer, the velocity of the crust on the surface of the liquid will also increase. Therefore, the refining material should have enough reaction heat, and should be preheated as much as possible (temperature 150-200°C), and the material should be added at the same time. Timely, uniform and focused. After the reaction of the refining material is completed, 20-30 KG of lime is added to protect the surface of the slag and retard it, which is beneficial to the settlement of iron particles. Practice has shown that, in addition to the iron scales, ** and lime, the amount of ferrosilicon equivalent to the main material should also be added to the refining material, which will help to better control the amount of aluminum in the finished product and save **.
Sixth, slagging and de-slaging time After smelting, attention should be paid to controlling the slagging and defoaming time. After sedation 5-8MIN, slagging is performed. After cooling, the furnace shell can be removed after 12H. If the sedation time is too short, the iron is not completely settled, the TTI in the slag is high, and the cooling time is too short. On the other hand, the iron is not completely solidified and easily leached on the one hand. On the other hand, titanium is easily oxidized at high temperatures and the loss is increased.
VII. Quality of smelting furnace barrels Sand sockets made of magnesite or other refractories must be vibrated tightly to flatten and compact the surface to prevent alloy extravasation and increase the amount of alloying on the surface of the tie layer. , so as not to affect the alloy yield. Practice has shown that the size of the knotted material at the bottom of the sand pit is 0-3 MM, and the particle size of the surface knotting material controlled at 0-1 mm can reduce the amount of slag iron bond.
VIII. Recovery of fine powder The fine powder of 0-10MM produced during the process of crushing the finished product can only be sold at a lower price due to its narrow range of use. The price is lower than the finished product price by 4000-6000 RMB/T. The production practice shows that the fine powder is added into the reaction raw material, and the method of adding is that after the reaction material is added, an annular platform is formed on the edge of the furnace bottom and the fine powder (50-100 KG) is evenly spread on the platform. However, the fine powder cannot be in contact with the bottom of the smelting furnace, which is beneficial to the heat absorption of the fine powder. Since the fine powder is on the material surface, it is not in full contact with the charge material, and the reduction of titanium in the fine powder is avoided. This can recover part of the fine powder indirectly improve the yield of titanium iron.
Nine, other factors To obtain a good recovery rate, but also to achieve accurate sampling, mixing evenly, the dust ash and raw materials scattered on the production site back to the furnace smelting.
First, the raw material factors The higher the grade of titanium concentrate and rutile, the better the smelting effect, more iron, TI alloy content is high; when the grade of rutile is more than 90%, the grade of titanium concentrate is more than 50%, the recovery The rate is higher; the sand mine is better than the original ore smelting effect. The higher the ratio of FEO/FE2O3 in the titanium concentrate, the better the roasting effect before smelting and the better the economic and technical indicators. The particle size of titanium concentrate and rutile should be appropriate, and the loss due to overflying rules increases; overcoarse, and the reaction of aluminum heat is insufficient, and the recovery rate decreases; therefore, the particle size of rutile is generally controlled at 100-160 mesh, and the particle size of titanium concentrate is controlled at 40-100 mesh. The proportion of titanium concentrate and rutile should be kept around 3.5:1. The roasting temperature is generally controlled at 750°C-850°C, and the roasting time is 3-5H. The insufficient roasting temperature and the short time will affect the unit thermal effect and the reduction reaction fully, and have an adverse effect on the recovery rate.
For the production of ferro-titanium, the higher its grade, the more favorable it is to the reduction reaction. Generally, more than 98% of aluminum is used. The particle size of ** will affect the speed of chemical reaction and the utilization of aluminum, ** too coarse, small specific surface area, long interface chemical reaction, is not conducive to heat concentration, and slag iron is not easy to separate, less iron out ** Too fine, flying and burning loss increase, at the same time, the amount of alumina in the fine ** increases, resulting in insufficient aluminum, affecting the reduction of titanium; appropriate ** particle size is generally 60 mesh -1.5MM, accounting for more than 90%.
Lime is used as a flux in the charge, which can reduce the melting point of the slag, improve the fluidity of the slag, promote the sinking of the metal suspended substance, and prevent the combination of TIO and AL2O3, which is beneficial to increase the recovery rate of titanium. Lime contains CAO to be high, particle size 1-2MM, not using unburnt and powdered lime. The amount of lime to be added should be appropriate, the amount should not be too large, too much heat in the reduction process to consume too much, reducing the maximum temperature to reach the system, making the reaction difficult.
The silicon in ferrosilicon combines with titanium in the alloy to form TI5SI3 and other compounds, preventing the formation of aluminum compounds, reducing the amount of aluminum entering the alloy, and improving the utilization of aluminum, thereby facilitating the improvement of TI recovery. The silicon-iron powder containing about 75% silicon and the particle size of 0-1 MM is more advantageous for smelting titanium-iron.
Second, the unit thermal effect of the unit of thermal effects are: 1) the heat of the chemical reaction of the charge; 2) the physical heat brought into the charge. The heat of chemical reaction is mainly determined by the grades and ingredients of materials such as titanium concentrates, rutile, and cesium, and the physical heat is mainly determined by the calcination temperature of titanium concentrate and rutile. Production practice shows that the unit calorific value is low, the reduction reaction is difficult to carry out, the slag has poor fluidity, there are many metal balls containing TI in the slag, the slag iron is not easy to separate, the iron output is small; the unit calorific value is high, the reaction is fierce, and the slag stirring causes Splattering, process loss, low output.
Third, the aluminum coefficient from the test that the recovery rate of titanium with the increase in the amount of aluminum, but the amount of aluminum will reduce the reaction unit of thermal effects, making the slag thicker, but also easily lead to excessive aluminum alloy content, Affect product quality. Therefore, in order to obtain a higher recovery rate of titanium, the amount of aluminum must be controlled within an optimal range. Tests have shown that when the aluminum distribution coefficient is 1.03-1.06, the TTI in the slag is lower, and the aluminum content in the finished product conforms to GB3282- 87 requirements, the best smelting effect.
Fourth, the feeding speed of the material feeding process should follow the "first slow, intermediate fast, last slow" principle; the end of the reaction is completed when adding the main material, the material should be slow, until the molten pool is increased and then increase the feeding rate, the appropriate speed should be The reaction is rapid and uniform, and the reaction should be slowed down in the later period of the reaction to prevent the reaction from becoming overly aggressive and causing splashing. Appropriate feeding rate will help the concentration of heat, iron sedimentation, iron output increased. Feeding too fast and easy to spray slag, the alloy contains low titanium, the high content of aluminum contains too little heat, the heat loss is large, and the amount of iron is low. Finally, we must pay attention to uniform feeding, to prevent the feed rate changes too much or stop feeding to make the alloy slag. Production practice shows that the total amount of charging material is 8T, and the blanking time is controlled at 9-12MIN.
Fifth, the refining material is also known as precipitant. The purpose of adding the refining material is to increase the slag temperature and enhance the fluidity of the slag, so that the titanium-iron metal particles can be easily settled from the slag; at the same time, the iron droplets produced by the reaction of the refining material go from the top to the bottom. After passing through the slag layer, the metal beads suspended in the slag layer containing higher TI and smaller specific gravity can be brought into the molten pool, thereby increasing the titanium recovery rate. At the end of the smelting reaction, with the thickening of the slag layer, the velocity of the crust on the surface of the liquid will also increase. Therefore, the refining material should have enough reaction heat, and should be preheated as much as possible (temperature 150-200°C), and the material should be added at the same time. Timely, uniform and focused. After the reaction of the refining material is completed, 20-30 KG of lime is added to protect the surface of the slag and retard it, which is beneficial to the settlement of iron particles. Practice has shown that, in addition to the iron scales, ** and lime, the amount of ferrosilicon equivalent to the main material should also be added to the refining material, which will help to better control the amount of aluminum in the finished product and save **.
Sixth, slagging and de-slaging time After smelting, attention should be paid to controlling the slagging and defoaming time. After sedation 5-8MIN, slagging is performed. After cooling, the furnace shell can be removed after 12H. If the sedation time is too short, the iron is not completely settled, the TTI in the slag is high, and the cooling time is too short. On the other hand, the iron is not completely solidified and easily leached on the one hand. On the other hand, titanium is easily oxidized at high temperatures and the loss is increased.
VII. Quality of smelting furnace barrels Sand sockets made of magnesite or other refractories must be vibrated tightly to flatten and compact the surface to prevent alloy extravasation and increase the amount of alloying on the surface of the tie layer. , so as not to affect the alloy yield. Practice has shown that the size of the knotted material at the bottom of the sand pit is 0-3 MM, and the particle size of the surface knotting material controlled at 0-1 mm can reduce the amount of slag iron bond.
VIII. Recovery of fine powder The fine powder of 0-10MM produced during the process of crushing the finished product can only be sold at a lower price due to its narrow range of use. The price is lower than the finished product price by 4000-6000 RMB/T. The production practice shows that the fine powder is added into the reaction raw material, and the method of adding is that after the reaction material is added, an annular platform is formed on the edge of the furnace bottom and the fine powder (50-100 KG) is evenly spread on the platform. However, the fine powder cannot be in contact with the bottom of the smelting furnace, which is beneficial to the heat absorption of the fine powder. Since the fine powder is on the material surface, it is not in full contact with the charge material, and the reduction of titanium in the fine powder is avoided. This can recover part of the fine powder indirectly improve the yield of titanium iron.
Nine, other factors To obtain a good recovery rate, but also to achieve accurate sampling, mixing evenly, the dust ash and raw materials scattered on the production site back to the furnace smelting.
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