Method for producing all-vanadium-titanium pellets through belt type roasting machine

Abstract

The invention relates to the technical field of metallurgy, in particular to a method for producing all-vanadium-titanium pellets through a belt type roasting machine. The method comprises the steps that S1, vanadium titano-magnetite is dried and finely ground; s2, circularly feeding the rolled vanadium titano-magnetite offcut, adding bentonite, a flux and fly ash, and uniformly mixing; s3, pelletizing: screening out qualified green pellets with the particle size of 8-16 mm, distributing the materials, transporting the materials to a roasting system, and returning the unqualified green pellets to a pelletizing chamber to participate in pelletizing again; s4, the green pellets are sequentially subjected to a forced air drying section, an air draft drying section, a preheating section, a roasting section, a soaking section, a first cooling section and a second cooling section on a belt type roasting machine, and pellets are formed after cooling; pellet production is met through high-pressure rolling and grinding and proper circulation volume setting, and in the production process, the performance of produced pellets is excellent by adding bentonite in a reasonable proportion, controlling pelletizing parameters and meanwhile through a reasonable roasting system.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, in particular to a method for producing all-vanadium titanium pellets using a belt roaster. Background Art

[0002] Pellet production is the process of rolling fine-grained materials (iron concentrate) into balls on special pelletizing equipment under water conditions, and then roasting and consolidating them into spherical iron-containing raw materials with certain strength and metallurgical properties, namely pelletized ore.

[0003] At present, the main pellet production process technologies are belt roaster process and chain grate-rotary kiln process. In comparison, due to the strong adaptability of the belt roaster to raw materials, high production efficiency, low operating cost (6-9 yuan / ton lower than the chain grate-rotary kiln) and large-scale advantages, in recent years, with the changes in global raw material conditions, high-quality pellet raw materials are becoming less and less, and coupled with the continuous progress of ironmaking, it has become a trend to use a large proportion of pellets in blast furnaces, and the production of flux pellets and magnesium pellets has become a development direction, which has inevitably promoted the development of the belt roaster process.

[0004] The price of vanadium-titanium ore powder is relatively low. The use of vanadium-titanium powder in pellets is conducive to reducing costs and increasing efficiency, and the vanadium in vanadium-titanium ore has a high economic value. However, due to the coarse particle size and poor ball-making performance of vanadium-titanium ore, it is difficult to produce vanadium-titanium balls. At present, there are few domestic belt roasting pellet manufacturers, and there are even fewer manufacturers that use belt roasters to produce pellets for all-vanadium-titanium ore (100% vanadium-titanium ore). There is very little research in this field at home and abroad. Due to the lack of theoretical research and technical support, the production of vanadium-titanium pellets by belt roasters has high energy consumption, poor product quality, and backward technical indicators.

[0005] In view of this, the present application aims to provide a method for producing all-vanadium titanium pellets using a belt roaster to better solve the above technical problems. Summary of the invention

[0006] To solve the above problems, the present invention provides a method for producing all-vanadium titanium pellets using a belt roaster, which solves the technical problems of high energy consumption and poor product quality in producing all-vanadium titanium pellets using a belt roaster through a reasonable roasting system and production process.

[0007] The technical solution adopted by the present invention is:

[0008] A method for producing all-vanadium titanium pellets using a belt roaster comprises the following steps:

[0009] S1. The vanadium-titanium magnetite is dried using a drum dryer, using blast furnace gas as a heat source, and then finely ground using a high-pressure roller press;

[0010] The drying method is downstream drying, which is designed based on the inlet moisture of 11.0% and the outlet moisture of ≤8%. At the same time, a bypass system is designed. When the moisture content of the vanadium-titanium magnetite meets the requirements of pelletizing, it does not need to be dried and can be transported to the roller press room through the bypass.

[0011] Among them, the high-pressure roller press is equipped with a bypass system and a side material circulation system. When roller pressing is not required, the bypass system is used. A debris roller screen is installed in front of the roller press, and a weighing material level meter is installed in the buffer bin at the front end.

[0012] S2. The vanadium-titanium magnetite edge material after roller pressing is recycled and added with bentonite, flux and dust removal ash and mixed;

[0013] S3. Use a rotary support disc ball making machine to make balls. The speed and inclination of the disc ball making machine can be adjusted. Each ball making machine corresponds to a roller screening machine to screen out qualified green balls with a particle size of 8-16mm, distribute them, and transport them to the roasting system. The unqualified green balls are returned to the ball making room to participate in ball making again;

[0014] S4. The green balls are sequentially subjected to the blast drying section, exhaust drying section, preheating section, roasting section, soaking section, first cooling section and second cooling section on the belt roaster. After cooling, the pellets are screened by a vibrating screen to separate the finished products with a particle size larger than 12mm or 12.5mm for the bottom and side materials. The other finished pellets are transported to the finished product storage and transportation system by a belt conveyor;

[0015] The waste gas generated during the drying and preheating process is dedusted, and the dedusted ash formed is used as the ingredient in step S2.

[0016] Furthermore, in step S2, the side material circulation is based on a feed rate of 28-32%, the amount of bentonite is 1-1.8%, the flux is slaked lime, the addition ratio is 3-5%, and the moisture content of the mixture is 5.6-8.0%.

[0017] Furthermore, in step S3, the specific process of green ball distribution is: reciprocating distributor - wide belt - roller distributor - belt roasting machine.

[0018] Furthermore, in step S4, the green balls are dried with a dry airflow at 300-350°C in the air drying section to remove water attached to the green balls and avoid over-humidification of the lower green balls. The dry airflow comes from the hot airflow of the second cooling section of the roaster, and the hot airflow is sent to the air drying section through the fan and the pipeline system.

[0019] Furthermore, in step S4, the exhaust drying section uses the ~350°C hot exhaust gas recovered from the rear section of the roasting machine and the equalizing section bellows, and introduces it into the upper cover of the exhaust drying section through the heat recovery fan to dry the material layer, so that the raw balls are dehydrated and dried, and can withstand the temperature above 600°C in the preheating section.

[0020] Furthermore, in step S4, the main heat source of the preheating section is the hot exhaust gas from the cold section of the roasting machine I, and a part of the hot air flow of ~350°C from the heat recovery fan is added to the front of the preheating section, and the burner installed on the upper cover of the preheating section provides heat, so that the green balls are preheated and have a certain strength, and enter the roasting section to undergo roasting and hardening at >1000°C.

[0021] Furthermore, in step S4, the preheated pellets enter the roasting section, undergo a roasting atmosphere of 1200-1300°C formed by the heat supplied by the burner, and are hardened and consolidated. The combustion-supporting air required for the burner combustion is composed of the primary ambient air provided by the combustion-supporting fan and the secondary combustion-supporting hot air from the cold section of the roaster I. The pellets reach the required strength after roasting.

[0022] Furthermore, in step S4, after the calcined pellet layer enters the equalizing section, the pellet layer is continuously temperature-homogenized by the >1000°C hot air from the I cooling section under exhaust treatment, so that the pellets at different heights of the layer are kept at a balanced temperature and enter the cooling section.

[0023] Furthermore, in step S4, the cooling section I uses a cooling blower to introduce ambient air into the wind box and penetrate the pellet material layer to cool the high-temperature pellets that have been roasted. After the heat exchange, the hot air at ~1000°C is sent to the equalizing section, roasting section, and preheating section through the upper cover and the pipeline; the cooling section II continues to cool the pellet material layer, and after the pellets are cooled to no more than 120°C, they are transported to the finished product grading process after unloading. After heat exchange, the hot air with a temperature of about 330°C is introduced from the upper cover by the drying blower into the drying section for raw ball drying.

[0024] Furthermore, in step S4, the waste gas generated in the drying and preheating process is purified by dust removal, enters the desulfurization and denitrification system for further treatment, and is then discharged.

[0025] The beneficial effects of the present invention are as follows:

[0026] The method for producing full vanadium-titanium pellets by a belt roaster provided by the present invention improves the particle size and specific surface area of ​​vanadium-titanium magnetite by drying and rolling it, thereby achieving basic pelletizing conditions for vanadium-titanium ore with poor pelletizing property, and facilitates batching and pelletizing through a suitable circulation amount. Meanwhile, bentonite is added in the batching process to effectively solve the problem of low bursting temperature of green balls. After the green balls are made, the green balls are passed through a belt roaster for a total of seven process sections, namely, a blast drying section, an exhaust drying section, a preheating section, a roasting section, a soaking section, and a first cooling section and a second cooling section. Through a reasonable roasting system, FeO in the vanadium-titanium magnetite is fully oxidized, thereby consolidating the pellets and improving their strength, thereby ensuring product quality and performance, solving the problem of poor quality of vanadium-titanium balls produced by the belt roaster, and fully meeting the requirements of blast furnace production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart of an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively by way of examples, and preferred embodiments of the present invention are given below. However, the present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently replacing the technical scheme of the present invention without creative results are within the protection scope of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0030] The numerical values ​​disclosed in the embodiments of the present invention are approximate values, not definite values. When the error or experimental conditions permit, all values ​​within the error range may be included without being limited to the specific numerical values ​​disclosed in the embodiments of the present invention.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0032] The following are specific embodiments of the present application:

[0033] This embodiment provides a method for producing all-vanadium titanium pellets using a belt roaster, comprising the following steps:

[0034] S1. The vanadium-titanium magnetite is dried using a drum dryer, using blast furnace gas as a heat source, and then finely ground using a high-pressure roller press;

[0035] The drying method is downstream drying, which is designed based on an inlet moisture of about 11.0% and an outlet moisture of no more than 8%. A bypass system is also designed. When the moisture content of the vanadium-titanium magnetite meets the requirements for pelletizing, it does not need to be dried and can be transported to the roller press room through the bypass.

[0036] The high-pressure roller press is equipped with a bypass system and a side material circulation system. When roller pressing is not required, the bypass system is used. The roller pressing and bypass systems are designed at 100% capacity. A debris roller screen is installed in front of the roller press, and a weighing material level meter is installed in the buffer bin at the front end.

[0037] S2. The vanadium-titanium magnetite edge material after roller pressing is recycled, and the edge material is recycled at 30% of the feeding amount, and is added with bentonite, flux and dust removal ash, and mixed;

[0038] Here, the amount of bentonite is 1.1%, the moisture content of the mixture is 5.6% to 6.5%, and the moisture content of the green ball is 8.2% to 9.0%. Under this condition, the green ball drop strength is 5.3 times / ball, the compressive strength is 13.2N / ball, and the burst temperature is 350℃;

[0039] S3. Use Φ7.5m rotary support disc ball making machine to make balls. The speed and inclination of the disc ball making machine can be adjusted. Each ball making machine corresponds to a roller screening machine to screen out qualified green balls with a particle size of 8-16mm. The qualified green balls are transported to the roasting system by a belt conveyor, and the unqualified green balls are transported back to the ball making room by a belt conveyor to participate in ball making again;

[0040] The specific process of green ball distribution is: reciprocating distributor - wide belt - roller distributor - belt roasting machine;

[0041] S4. The green balls are sequentially subjected to the blast drying section, exhaust drying section, preheating section, roasting section, soaking section, first cooling section and second cooling section on the belt roaster. After cooling, the pellets are screened by a vibrating screen to separate the finished products with a particle size larger than 12mm or 12.5mm for the bottom and side materials. The other finished pellets are transported to the finished product storage and transportation system by a belt conveyor;

[0042] Specifically:

[0043] Blast drying section: The green balls are dried with a dry airflow of 300-350℃ in the blast drying section to remove the water attached to the green balls and prevent the lower green balls from being too wet. The hot airflow from the second cooling section of the roaster is sent to the blast drying section through the fan and pipeline system;

[0044] Air drying section: The hot exhaust gas of about 350℃ recovered from the wind box of the roasting rear section and the soaking section of the roasting machine is introduced into the upper cover of the air drying section through the heat recovery fan to dry the material layer, so that the green balls are dehydrated and dried, and can withstand the temperature above 600℃ in the preheating section;

[0045] Preheating section: The main process function is to heat and raise the temperature, so that the chemical water and carbonate in the pellets can be decomposed and oxidized. The main heat source is the hot exhaust gas from the cold section of the roaster I, and part of the hot air flow of about 350℃ from the heat recovery fan is added to the front of the preheating section, and the burner installed on the upper cover of the preheating section provides heat, so that the green balls can be preheated and have a certain strength, and then enter the roasting section to undergo roasting and hardening at more than 1000℃;

[0046] Roasting section: The preheated pellets enter the roasting section, where they are subjected to a 1200-1300°C roasting atmosphere formed by the heat supplied by the burner and are hardened and consolidated. The combustion-supporting air required for the burner combustion is composed of the primary ambient air provided by the combustion-supporting air fan and the secondary combustion-supporting hot air from the cold section I of the roaster. After roasting, the pellets reach the required strength;

[0047] Soaking section: After the calcined pellets enter the soaking section, the pellets are continuously temperature-homogenized by the hot air of more than 1000°C from the I cooling section under the ventilation treatment, so that the pellets at different heights of the material layer are kept at a balanced temperature and enter the cooling section;

[0048] I Cold section: A cooling blower is used to introduce ambient air into the wind box and penetrate the pellet layer to cool the roasted high-temperature pellets for heat exchange. After heat exchange, the hot air at about 1000℃ is sent to the equalizing section, roasting section, and preheating section through the upper cover and pipelines;

[0049] II Cold section: Continue to cool the pellet layer. After the pellets are cooled to no more than 120°C, they are transported to the finished product classification process through unloading. After heat exchange, the hot air with a temperature of about 330°C is introduced from the upper cover by the drying blower into the blast drying section for raw pellet drying;

[0050] The waste gas generated during the drying and preheating process is dedusted, and the dust ash formed is used as the ingredient in step S2. The waste gas after dedusting is then sent to the desulfurization and denitrification system for further treatment before being discharged.

[0051] Specifically, the roasting conditions were tested, and the test structure is shown in the following table:

[0052]

[0053]

[0054] The above experimental results show that when the preheating temperature is 1050℃, the preheating time is 12min, the roasting temperature is 1250℃, and the roasting time is 12min, the compressive strength of the pellets is close to 2300N / piece, and the FeO content is greater than 2.0%; when the preheating temperature is 1050℃, the preheating time is 15min, the roasting temperature is 1250℃, and the roasting time is 15min, the compressive strength of the pellets is greater than 2300N / piece, and the FeO content is less than 1.0%. Vanadium-titanium magnetite has a high FeO content, and a long preheating time is required to fully oxidize the FeO, consolidate the pellets, and improve the strength; to ensure the strength of the pellets, the appropriate total roasting time is 50-53min, that is: blast drying for 3min, exhaust drying for 4min, preheating stage for 10-12min, roasting for 10-15min, soaking for 5min, cooling stage 1 for 10min, and cooling stage 2 for 5min.

[0055] In this embodiment, the chemical composition of the vanadium-titanium magnetite used is shown in the following table:

[0056]

[0057] The specific surface area test results of the vanadium-titanium magnetite are shown in the following table:

[0058]

[0059] The spheroidization index test results of the vanadium-titanium magnetite are shown in the following table:

[0060] Raw material name W points,% W gross,% Balling index K grade Vanadium Titanium Magnetite 2.58 16.67 0.18 weak

[0061] It can be seen that the vanadium-titanium magnetite used in this embodiment has a high ferrous content and a relatively high sulfur content, which will increase the difficulty of oxidation of the pellets. The specific surface area of ​​the vanadium-titanium magnetite is lower than the requirement for suitable pelletization, and the pelletization performance is poor and the particle size is coarse, with -200 mesh only 70.9% and -325 mesh only 50.4%, which does not meet the requirements of the fineness of the iron concentrate for the production of football pellets. Therefore, in this embodiment, the vanadium-titanium magnetite is subjected to high-pressure roller pressing, and the side material circulation is designed according to a 30% feeding amount. After rolling, the -200 mesh content reaches 76.12%, and the specific surface area reaches 1330cm 2 / g, to meet the pelletizing conditions.

[0062] In this embodiment, the results of the physical and chemical properties test of the bentonite used are shown in the following table:

[0063]

[0064]

[0065] In the above embodiment, the chemical composition analysis results of the finished pellets are shown in the following table:

[0066]

[0067] In the above embodiment, the physical properties of the finished pellets are as follows:

[0068] Compressive strength N / ball 2478 Drum index>6.3mm% 96.40 Anti-wear index <0.5mm% 3.10

[0069] In the above embodiment, the metallurgical properties test results of the pellets are shown in the following table:

[0070]

[0071] To sum up, in this embodiment, the vanadium-titanium ore with poor ball-forming properties is subjected to a high-pressure roller mill and a suitable circulation volume is set to meet the pellet production. During the production process, the problem of low raw ball bursting temperature is solved by adding a reasonable proportion of bentonite and controlling the ball making parameters. At the same time, a reasonable roasting system is used to solve the problem of poor quality of vanadium-titanium balls produced by a belt roaster, so that the produced pellets have excellent metallurgical properties and can better meet the needs of iron smelting.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for producing all-vanadium titanium pellets using a belt roaster, characterized in that: The steps include: S1. The vanadium-titanium magnetite is dried using a drum dryer, using blast furnace gas as a heat source, and then finely ground using a high-pressure roller press; The drying method is downstream drying, which is designed based on the inlet moisture of 11.0% and the outlet moisture of ≤8%. At the same time, a bypass system is designed. When the moisture content of the vanadium-titanium magnetite meets the requirements of pelletizing, it does not need to be dried and can be transported to the roller press room through the bypass. Among them, the high-pressure roller press is equipped with a bypass system and a side material circulation system. When roller pressing is not required, the bypass system is used. A debris roller screen is installed in front of the roller press, and a weighing material level meter is installed in the buffer bin at the front end. S2. The vanadium-titanium magnetite edge material after roller pressing is recycled and added with bentonite, flux and dust removal ash and mixed; S3. Use a rotary support disc ball making machine to make balls. The speed and inclination of the disc ball making machine can be adjusted. Each ball making machine corresponds to a roller screening machine to screen out qualified green balls with a particle size of 8-16mm, distribute them, and transport them to the roasting system. The unqualified green balls are returned to the ball making room to participate in ball making again; S4. The green balls are sequentially subjected to the blast drying section, exhaust drying section, preheating section, roasting section, soaking section, first cooling section and second cooling section on the belt roaster. After cooling, the pellets are screened by a vibrating screen to separate the finished products with a particle size larger than 12mm or 12.5mm for the bottom and side materials. The other finished pellets are transported to the finished product storage and transportation system by a belt conveyor; The waste gas generated during the drying and preheating process is dedusted, and the dedusted ash formed is used as the ingredient in step S2.

2. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S2, the side material circulation is based on a feed rate of 28-32%, the amount of bentonite is 1-1.8%, the flux is slaked lime, the addition ratio is 3-5%, and the moisture content of the mixture is 5.6-8.0%.

3. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S3, the specific process of green ball distribution is: reciprocating distributor - wide belt - roller distributor - belt roasting machine.

4. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the green balls are dried with a dry air flow at 300-350°C in the blast drying section to remove water attached to the green balls and avoid over-humidification of the lower green balls. The dry air flow comes from the hot air flow of the second cooling section of the roaster, and the hot air flow is sent to the blast drying section through the fan and the pipeline system.

5. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the exhaust drying section uses the ~350°C hot exhaust gas recovered from the rear section of the roasting machine and the bellows of the equalizing section, and introduces it into the upper cover of the exhaust drying section through the heat recovery fan to dry the material layer, so that the raw balls are dehydrated and dried, and can withstand the temperature above 600°C in the preheating section.

6. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the main heat source of the preheating section is the hot exhaust gas from the cold section of the roasting machine I, and a part of the hot air flow of ~350℃ from the heat recovery fan is added to the front of the preheating section, and the burner installed on the upper cover of the preheating section provides heat, so that the green balls are preheated and have a certain strength, and enter the roasting section to undergo roasting and hardening at >1000℃.

7. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the preheated pellets enter the roasting section, undergo a roasting atmosphere of 1200-1300°C formed by the heat supplied by the burner, and are hardened and consolidated. The combustion-supporting air required for the burner combustion is composed of the primary ambient air provided by the combustion-supporting fan and the secondary combustion-supporting hot air from the cold section of the roaster I. The pellets reach the required strength after roasting.

8. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, after the calcined pellet layer enters the equalizing section, the pellet layer is continuously temperature-homogenized by the >1000°C hot air from the I cooling section under exhaust treatment, so that the pellets at different heights of the layer are kept at a balanced temperature and enter the cooling section.

9. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the cooling section I uses a cooling blower to introduce ambient air into the wind box and penetrate the pellet material layer to cool the high-temperature pellets that have been roasted. After the heat exchange, the hot air at ~1000°C is sent to the equalizing section, roasting section, and preheating section through the upper cover and the pipeline; the cooling section II continues to cool the pellet material layer. After the pellets are cooled to no more than 120°C, they are transported to the finished product grading process through unloading. After heat exchange, the hot air with a temperature of about 330°C is introduced from the upper cover by the drying blower into the drying section for raw ball drying.

10. The method for producing all-vanadium titanium pellets by a belt roaster according to claim 1, characterized in that: In step S4, the waste gas generated during the drying and preheating process is purified by dust removal, enters the desulfurization and denitrification system for further treatment, and is then discharged.

Images