CN114410958A - Production method for reducing pulverization of pellets - Google Patents
Production method for reducing pulverization of pellets Download PDFInfo
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- CN114410958A CN114410958A CN202210188358.6A CN202210188358A CN114410958A CN 114410958 A CN114410958 A CN 114410958A CN 202210188358 A CN202210188358 A CN 202210188358A CN 114410958 A CN114410958 A CN 114410958A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/04—Blast roasting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/26—Cooling of roasted, sintered, or agglomerated ores
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Abstract
The invention discloses a production method for reducing pulverization of pellets, and belongs to the technical field of pellet preparation. The method of the invention comprises the following steps: step one, raw material pretreatment; drying the mineral powder with low bursting temperature, fully and uniformly mixing the dried mineral powder with the binder and the additive in proportion, and then adding water for mixing; step two, pelletizing treatment; pelletizing the raw materials obtained by the treatment in the step one to prepare green pellets; step three, green pellet treatment to obtain finished pellets; and D, spreading the green pellets screened in the step II into a belt type roasting machine for low-temperature drying, roasting and cooling treatment to obtain finished pellets. By adopting the technical scheme of the invention, the purposes of greatly improving the pellet bursting temperature and reducing the pulverization of the pellets of the belt type roasting machine in the drying stage can be achieved, so that the manufacturing cost is effectively reduced, and the method is suitable for preparing pellets of different raw materials.
Description
Technical Field
The invention belongs to the technical field of pellet preparation, and particularly relates to a production method for reducing pulverization of pellets.
Background
As a high-quality iron-making furnace charge, the pellet ore has unique advantages in the aspects of improving the utilization coefficient of the blast furnace, improving the air permeability of a material column, reducing the emission of waste gas, facilitating transportation and the like, and is widely applied to the production of the blast furnace. In recent years, with a series of environmental protection and capacity removal requirements of the state, the proportion of pellet in blast furnace burden is continuously increased, and the national pellet yield is also improved year by year. The main raw materials for producing the pellet ore are fine iron concentrate powder and a binder, in order to meet the requirement of a blast furnace on the iron grade of the iron-containing raw material, the production of the iron concentrate powder for the pellet usually needs to enrich, grind and select iron ore, and the produced iron concentrate powder generally has the characteristics of higher iron grade, less harmful impurities, fine granularity and the like.
The traditional method for producing the pellet mainly comprises the following steps: mixing the raw materials, adding water to prepare green pellets, and drying to remove water; then the pellets are preheated and roasted for consolidation, the pellet strength is improved, and finally the pellets are cooled to obtain finished pellets. However, in the conventional pellets, especially the pellets made of the concentrate with lower bursting temperature, the green pellets are often cracked in the drying process. Although the mechanism of green pellet explosion is mainly because the vapor pressure of the moisture in the pellet is too large and the strength of the shell of the pellet is low, the green pellet is exploded and cracked, in practice, the explosion temperature of the pellet is influenced in many ways and is an index which is difficult to control. For example, in the process of green pellet forming, in order to ensure that the falling strength and the compressive strength of green pellets are qualified, binders are added into iron ore concentrate, and although the strength of the pellets is ensured to be qualified, the existence of the binders can cause the pellets to absorb more water, so that the internal vapor pressure of the pellets is increased.
Through retrieval, the invention patents aiming at reducing the drying, cracking and pulverization of the pellets at present have related disclosures, for example, the Chinese patent application numbers are as follows: 201210191221.2, filing date: 6/11/2012, the name of invention creation is: a preparation method of additive for improving the bursting temperature and quality of pellet ore and a product thereof. The method disclosed in the application comprises the technical processes of mineral separation, crushing, drying and the like, and is characterized in that the content of MgO in the used ore raw material is 35-47%; crushing to a particle size of less than or equal to 5.0mm, roasting at 750-900 ℃ for 30-120 min, cooling and grinding to obtain the additive, wherein the additive comprises the following chemical components in percentage by weight: 77-86 parts of MgO and 5-5 parts of SiO2≤10、1≤Al2O3Burning loss is not less than 2 and not more than 6 and not more than 15, the hydration activity of the additive is not less than 80 percent, and the specific surface area is not less than 45m2(ii) in terms of/g. In the application, the moisture of the pellets is easier to escape by increasing the air permeability of the pellets mainly through ore blending (namely adding additives) and the moisture of green pellets is reduced by optimizing pelletizing parameters, although effective in addressing the species to which they are related, are not generally applicable, because the pelletizing performance of each iron ore concentrate powder is greatly different, each additive has larger influence on the improvement of the bursting temperature of specific pellets, if the pellet bursting temperature is increased only by ore proportioning and optimizing pelletizing parameters, a great deal of time and effort are needed to test, adjust the proportioning, increase the manufacturing cost and the input time cost, therefore, it is important to design a process route which has strong adaptability to pellet raw materials and can greatly increase the pellet bursting temperature without ore blending and optimization of pelletizing parameter conditions.
Disclosure of Invention
1. Problems to be solved
In view of the problems in the background art, the invention provides a production method for reducing the pulverization of pellets, which achieves the purposes of greatly improving the bursting temperature of the pellets and reducing the pulverization of the pellets of a belt type roasting machine in the drying stage by reducing the blast temperature of the blast drying section of the belt type roasting machine in the production of the pellets and increasing the blast drying air quantity through a gas circulation method, thereby effectively reducing the manufacturing cost and being suitable for the preparation of pellets of different raw materials.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention relates to a production method for reducing pulverization of pellets, which comprises the following steps:
step one, raw material pretreatment;
fully and uniformly mixing the mineral powder with low bursting temperature, the binder and the additive in proportion, and then adding water for mixing;
step two, pelletizing treatment;
pelletizing the raw materials obtained by the treatment in the step one to prepare green pellets;
step three, green pellet treatment to obtain finished pellets;
and D, spreading the green pellets screened in the step II into a belt type roasting machine for low-temperature large-air-volume drying, roasting and cooling treatment to obtain finished pellets.
Furthermore, in the third step, the belt type roasting machine is provided with an air blowing drying section, an air draft drying section, a preheating section, a roasting section, a soaking section, a cooling section and a cooling section, and the prepared green pellets are sequentially treated by a continuous process section arranged on the belt type roasting machine.
Furthermore, in the third step, when the green pellets are treated in the air blast drying section, the treatment temperature is controlled to be 150-180 ℃, the treatment time is 2-4 min, and the air blast speed is 3-4 m/s.
Furthermore, when green pellets are treated in the blast drying section, in addition to the conventional blast mixing section, the air volume of the preheating section, the roasting section, the soaking section and the cooling section on the belt type roasting machine is mixed with air to the blast drying section, so that the drying air volume is increased.
Further, for 300m2In the case of a straight grate roasting machine, whereinThe air volume from the cooling second section to the blast drying section is controlled to be 6000-7000 m3The air quantity from the soaking section to the blast drying section is controlled to be 3000-4000 m3The air quantity from the preheating section and the roasting section to the blast drying section is controlled to be 6000-8000 m3/min。
Furthermore, in the step one, the used mineral powder has low bursting temperature after being made into pellets, and is easy to have pulverization phenomenon during drying.
Furthermore, in the second step, the pelletizing time is controlled to be 16-18 min, and the consolidation time is 2 min.
Furthermore, in the second step, the water content of the green pellet is controlled to be 7-8%, the green pellet is screened after pelletizing is finished, and the diameter of the green pellet is controlled to be 12.5-13.5 mm.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the production method for reducing the pulverization of the pellets, the pellets are treated by adopting the belt type roasting machine, particularly, the blast temperature of the blast drying section of the belt type roasting machine in the pellet production is reduced, the blast air volume is increased, on the basis that the pellets are not cracked in the blast drying section, part of moisture in the green pellets is removed, and the steam pressure of the pellets when the green pellets enter the air draft drying section is reduced, so that the purposes of greatly improving the cracking temperature of the pellets and reducing the pulverization of the pellets in the drying section of the belt type roasting machine are achieved, the universality is strong, and the manufacturing cost is low.
(2) According to the production method for reducing the pulverization of the pellets, on one hand, the blast drying temperature is optimally designed in time, so that the bursting temperature of the pellets can be effectively increased, and the pulverization of the pellets on the drying section of the belt type roasting machine is reduced. On the other hand, the air charging operation is carried out on the air blowing drying section, the moisture removal in the green pellets is further improved by improving the air flow, and the steam pressure in the pellets is ensured to be at a lower level, so that the pulverization is not easy to occur.
(3) According to the production method for reducing the pulverization of the pellets, when green pellets are dried in the blast drying section, the air volume of the preheating section, the roasting section, the soaking section and the cooling second section on the belt type roasting machine is added to the blast drying section, so that the drying air volume is increased, meanwhile, the air volume of different air adding sections is respectively controlled, so that the whole air volume reaches about 2-3 times of the air volume in the conventional blast drying process, and the air in different treatment stages is added to the blast drying section, so that a proper drying environment can be created for the green pellets to be treated, the evaporation of water vapor of the pellets is facilitated, the gas recycling is facilitated, and the manufacturing cost is further reduced.
(4) Compared with the prior art, the production method for reducing the pulverization of the pellets does not need to improve the bursting temperature of the pellets by means of ore blending, changing pelletizing parameters, improving bentonite, adding a surface explosion-proof agent and the like, so that the pulverization is reduced. Meanwhile, the method of the invention has low manufacturing cost, has strong adaptability to different pellet manufacturing raw materials, and can provide an effective solution for increasing the bursting temperature of the pellets of different raw materials.
Drawings
FIG. 1 is a schematic flow diagram of the processing of green pellets of the present invention on a belt roaster;
FIG. 2 shows the main chemical components of the ore fines used in the present invention;
FIG. 3 shows the grain size composition of the ore fines used in the present invention;
FIG. 4 shows the burst temperature test results of green pellets obtained in each example and comparative example of the present invention.
In the figure:
1. a forced air drying section; 2. an air draft drying section; 3. a preheating section, 4, a roasting section; 5. a soaking section; 6. cooling for the first time; 7. cooling for the second stage; 8. a cooling air end is pumped; 9. a wind mixing end; 10. and an exhaust end.
Detailed Description
In the traditional process flow for producing pellet ore, the prepared green pellets need to be dried and dehydrated, so that the green pellets can bear the change of temperature stress when passing through a preheating section and can not crack and the like. In the conventional drying process, the pellets are very easy to crack and pulverize, so that the air permeability of a pellet production material layer is greatly influenced, the service life of equipment is prolonged, and the product quality and the yield are greatly influenced.
The main reasons for the green pellets to burst are: the moisture in the pellet becomes water vapor under the condition of drying air flow at a certain temperature, part of the water vapor is generated in the pellet, part of the water vapor escapes, meanwhile, the outer surface of the pellet is dried to form a shell with certain strength, and in the production of green pellets facing different bursting temperatures, if the drying temperature is higher for green pellets with low bursting temperatures, the water vapor pressure in the pellet is larger than the maximum bearing pressure of the shell of the pellet, and the green pellets can burst. Based on the phenomenon, the invention provides a production method for reducing pellet pulverization, and the green pellets are subjected to slow evaporation of water in the pellets and low vapor pressure without bursting under the condition of low blast temperature by reducing the blast temperature of a blast drying section (the treatment temperature is controlled to be 150-180 ℃ and the treatment time is 2-4 min) and increasing the blast drying air volume (the blast air speed is 3-4 m/s); meanwhile, the increase of the blast air volume enables the hot air which can be contacted by the green pellets to be increased without prolonging the time of the blast drying section, and the moisture removal amount can be sufficient. Then, when the green pellets after the low-temperature large-air-volume blast drying are subjected to air draft drying again, as part of water is removed, the internal steam pressure is greatly reduced, and the strength of the pellet shell is far greater than the steam pressure in the green pellets, so that the purposes of effectively improving the bursting temperature of the pellets and reducing the pellet pulverization of the belt type roasting machine on a drying section are achieved.
Specifically, the process flow of the invention comprises the following steps:
step one, raw material pretreatment;
drying the mineral powder with low bursting temperature, fully and uniformly mixing the dried mineral powder with the binder and the additive in proportion, and then adding water for mixing; wherein the raw materials comprise the following components in percentage by weight: 100% of mineral powder, 2.0% of bentonite as a binder and 6% of water content of the powder after water is added according to alkalinity calculation of an additive.
It should be noted that the embodiment of the present invention mainly relates to two kinds of concentrates with lower bursting temperature, one kind is ultra-fine-grained iron concentrate powder, and the other kind is coarse-grained iron concentrate powder, the main chemical composition table of the two kinds of ores is shown in fig. 2, and the grain size composition is shown in fig. 3. Under the condition that the falling strength and the compressive strength of the pellets are qualified by using 2.0 percent of bentonite and a proper amount of slaked lime, the bursting temperatures of the two ores are lower, wherein the main reason that the bursting temperature of the ultra-fine grain iron ore concentrate pellets is lower is that the prepared green pellets are compact, the escape of steam in the pellets is difficult, and the steam pressure is high, so that the bursting temperature of the pellets is low; although coarse steam of the coarse iron ore concentrate particles is easy to escape, the falling strength of the green pellets is high, the compressive strength is low, the pellets are easy to deform and the strength is low, so that the strength of the shells of the green pellets is lower than the steam pressure in the pellets, and the bursting temperature of the pellets is lower. Aiming at the two kinds of concentrate powder, in the process of preparing raw materials, the two kinds of concentrate powder are completely dried, then 2.0% of bentonite is added according to the mass proportion or slaked lime is added according to the alkalinity to be used as a binder, the mixture is fully mixed, then 6% of water is added for mixing, and finally the mixture is sieved and scattered for preventing agglomeration.
Step two, pelletizing treatment;
pelletizing the raw materials obtained by the treatment in the step one to prepare green pellets;
during pelletizing, the diameter of a used disc pelletizer is 1000mm, the rotating speed is set to be 23r/min, the disc inclination angle is 47 degrees, the pelletizing time is controlled to be 16-18 min, the consolidation time is 2min, the water content of green pellets is 7-8%, wherein the moisture of the superfine iron ore concentrate pellets is controlled to be 7%, the moisture of the low-silicon coarse particle pellets is preferably controlled to be 8%, and the green pellets are screened by a standard screen after pelletizing is finished, so that the diameter of the green pellets is controlled to be 12.5-13.5 mm.
Step three, green pellet treatment to obtain finished pellets;
and D, spreading the green pellets screened in the step II into a belt type roasting machine for drying, roasting and cooling treatment to obtain finished pellets.
When a belt type roasting machine is used for processing, the belt type roasting machine is mainly divided into an air blowing drying section 1, an air blowing drying section 2, a preheating section 3, a roasting section 4, a soaking section 5, a cooling section 6 and a cooling section 7, green pellets are processed through the air blowing drying section 1 and the air blowing drying section 2 respectively when being dried, and a wind charging end 9 is used for charging wind when the air blowing drying section 1 is used; the bottom of the air draft drying section 2 is provided with an exhaust end 10; and air inlets of the first cooling section 6 and the second cooling section 7 are provided with cold air pumping ends 8, and cold air is supplemented for cooling the roasted pellets.
It should be noted that, in the belt roasting machine, air is a carrier for drying and heat transfer, and in the present invention, in order to reduce the pulverization of the pellets, the air temperature is reduced, but the reduction of the air temperature can lead to incomplete drying of the pellets at the same time. The applicant finds out through experimental research that the drying effect of the pellets can be realized by reducing the air temperature and simultaneously improving the air volume, but the change of the large-amplitude air volume is difficult to obtain through the blower blowing at present in consideration of the service life and the technical limitation of the existing blower. Aiming at the difficulties, the applicant adjusts the gas circulation mode of the belt type roasting machine to ensure that the air volume of the preheating section 3, the roasting section 4, the soaking section 5 and the cooling second section 7 is mixed with air to the blast drying section 1, the three air flows are combined and subjected to blast drying at the low temperature of 150-180 ℃ under the condition of large air volume after being subjected to proper air mixing operation 9. In particular, for 300m2The air volume of the belt type roasting machine from the cooling second stage 7 to the blast drying stage 1 can be controlled to be 6000 to 7000m m3The air quantity from the soaking section 5 to the blast drying section 1 can be controlled within 3000-4000 m3The air quantity from the preheating section 3, the roasting section 4 to the blast drying section 1 can be controlled at 6000-8000 m3Min, the air quantity from the air charging end 9 to the blast drying section 1 can be controlled within 3000-4000 m3And/min, the air volume after the three sections are combined and added with the mixed air is about 2-3 times of the air volume from the original two sections to the blast drying section 1, and a reasonable dehydration rate is ensured on the basis of not increasing the drying time of the green pellets in the blast drying section 1, reducing the influence of the machine speed of the belt type roasting machine on the yield, prolonging the length of the belt type roasting machine and increasing the construction cost.
After the blast drying is finished, the bursting temperature of the pellets is measured, so that the improvement degree of the bursting temperature of the pellets by low-temperature large-air-volume blast drying under different temperatures and different drying air volume conditions is tested. The test method refers to the dynamic test method of American AC company, 20 pre-dried green pellets are put into a bursting temperature furnace each time, and in a vertical tube with a wind speed of 1.5m/s (cold state), the green pellets are taken out after staying in a drying cup for 5min, and the temperature of the green pellets is measured by a temperature measuring instrument, unit: DEG C. The bursting temperature profile of the green pellets prepared by the test is shown in FIG. 4.
The invention is further described with reference to specific examples.
Example 1
1.1. Ordinary drying at low temperature: firstly, fully and uniformly mixing 100% of superfine iron concentrate powder and 2.0% of bentonite agent, adding 6% of water for mixing, controlling the water content of green pellets to be 7% in the pelletizing process, controlling the pelletizing time to be 18min, wherein the green pellets are solidified for 2min, and controlling the diameter of the green pellets to be 12.5-13.5 mm by screening; then, the green pellets were dried at a low temperature for 2min at a drying temperature of 155 ℃ under a blowing drying wind speed of 1.5 m/s.
1.2, low-temperature large-air-volume drying: the burdening and green ball producing parts are the same as those in the example 1.1, and the air blowing drying treatment (namely, the air volume of the preheating section, the roasting section, the soaking section and the cooling section is added to the air blowing drying section) is carried out by adopting the improved belt type roasting machine of the invention, so that the air volume is effectively improved, the air blowing drying speed is 3m/s, the drying temperature is 155 ℃, the drying time is 2min, and the air blowing drying air volume is 2 times of the original air volume.
Comparative example 1
The batching and green ball making parts are the same as in example 1.1, with the difference that: the pellets in this comparative example were not subjected to low-temperature large-air-volume blast drying treatment, and were subjected to the burst temperature detection directly.
As shown in fig. 4, before low-temperature large-air-volume blast drying, the bursting temperature of the superfine iron ore concentrate green pellets in the comparative example 1 is 335 ℃, the superfine iron ore concentrate green pellets are easy to burst in the drying section of the belt type roasting machine, the bursting temperature of the superfine iron ore concentrate green pellets after low-temperature common drying in the example 1 is improved compared with that of the comparative example 1, and the bursting temperature of the superfine iron ore concentrate green pellets after low-temperature large-air-volume blast drying is obviously higher than that of the comparative example 1. Specifically, compared with the comparative example 1, in example 1, 1.1, after low-temperature large-air-volume blast drying at 155 ℃ for 2min, the bursting temperature of the green pellets is increased from 335 ℃ to 393 ℃, which is increased by 58 ℃ but is still lower than the standard of 400 ℃; compared with the comparative example 1, in the 1.2 of the example 1, after the green pellets are subjected to low-temperature large-air-volume blast drying at the temperature of 155 ℃ for 5min, the bursting temperature of the green pellets is increased from 335 ℃ to 483 ℃, which means that the original green pellets which have superfine mineral powder particle size, compact pellets and low bursting temperature and can greatly influence the air permeability of a material layer after being dried can successfully pass through a green pellet drying section of a belt type roasting machine without bursting and pulverization after being subjected to low-temperature large-air-volume blast drying.
Example 2
2.1. Ordinary drying at low temperature: 100 percent of superfine iron concentrate powder is added with slaked lime calculated by 1.2 alkalinity, 6 percent of water is added for mixing and mixing fully, the water content of green pellets is 8 percent, the pelletizing time is controlled to be 18min, wherein the green pellets are solidified for 2min, the diameter of the green pellets is 12.5-13.5 mm, the green pellets are dried normally at low temperature, the air speed of forced air drying is 1.5m/s, the drying temperature is 158 ℃, and the drying time is 2 min.
2.2. Low-temperature large-air-volume drying: the burdening and green ball producing parts are the same as the example 2.1, the drying treatment is carried out by adopting the blast drying method of the invention, the blast drying wind speed is controlled to be 3m/s, the drying temperature is 158 ℃, and the drying time is controlled to be 2 min.
Comparative example 2
The batch and green pellet preparation parts were the same as in example 2.1, and the burst temperature was directly measured without low-temperature large-air-volume forced air drying.
As shown in fig. 4, the green pellet bursting temperature in the comparative example 2 is 254 ℃, if the green pellet is not treated, bursting and pulverization are easily generated in a belt type roasting machine, so that the pellet cannot be produced, the air permeability of a material layer is greatly deteriorated, and then the bursting temperature of the green pellet is obviously higher than that of the comparative example 2 after low-temperature large-air-volume blast drying treatment, specifically, the example 2.1 is ordinary drying at low temperature, the lifting effect is only 111 ℃, and the effect is greatly different from that of the example 2.2, which shows that under the low-temperature condition, the lifting of the air volume has a good effect on improving the bursting temperature, and compared with the comparative example 2, the bursting temperature of the green pellet is improved from 254 ℃ to later more than 500 ℃ and is far higher than the requirement required by production after the low-temperature large-air-volume blast drying at 158 ℃ and the blast drying air speed of 3 m/s.
Example 3
3.1 ordinary drying at low temperature: 100 percent of coarse particle iron ore powder, 2.0 percent of bentonite and 6 percent of water are added for mixing and fully mixing, the water content of green pellets is 8 percent, the pelletizing time is 16min, the green pellets are solidified for 2min, the diameter of the green pellets is 12.5-13.5 mm, the low-temperature common drying blast drying wind speed is 1.5m/s, the drying temperature is 152 ℃, and the drying time is 2 min.
3.2 drying at low temperature and large air quantity: the burdening and green ball producing parts are the same as the example 3.1, the drying treatment is carried out by adopting the blast drying method of the invention, the blast drying wind speed is controlled to be 3m/s, the drying temperature is 152 ℃, and the drying time is 2 min.
Comparative example 3
The compounding and green pellet preparation were carried out in the same manner as in example 3.1, without low-temperature large-air-volume forced air drying, and the decrepitation temperature was directly measured.
As shown in fig. 4, the green pellet bursting temperature in the comparative example 3 is 342 ℃, the bursting phenomenon occurs in the drying section of the belt type roasting machine, and then the bursting temperature of the green pellet is significantly higher than that in the comparative example 3 after the low-temperature large-air-volume blast drying treatment, specifically, compared with the comparative example 3, in the example 3.2, after the low-temperature large-air-volume blast drying treatment of 152 ℃ and the blast drying air speed of 3m/s, the bursting temperature of the green pellet is increased from 342 ℃ to later more than 500 ℃, which is far higher than the requirement required for production, and compared with the example 3.1, the pellet bursting temperature can be significantly improved by increasing the air volume at low temperature.
Claims (7)
1. A production method for reducing pulverization of pellets is characterized in that: the method comprises the following steps:
step one, raw material pretreatment;
drying the mineral powder with low bursting temperature, fully and uniformly mixing the dried mineral powder with the binder and the additive in proportion, and then adding water for mixing;
step two, pelletizing treatment;
pelletizing the raw materials obtained by the treatment in the step one to prepare green pellets;
step three, green pellet treatment to obtain finished pellets;
and D, spreading the green pellets screened in the step II into a belt type roasting machine for low-temperature large-air-volume drying, roasting and cooling treatment to obtain finished pellets.
2. The production method for reducing pulverization of pellets as claimed in claim 1, wherein: and in the third step, the belt type roasting machine is provided with a blast drying section (1), an air draft drying section (2), a preheating section (3), a roasting section (4), a soaking section (5), a cooling section (6) and a cooling section (7), and the prepared green pellets are sequentially treated by a continuous process section arranged on the belt type roasting machine.
3. The production method for reducing pulverization of pellets as claimed in claim 2, wherein: in the third step, when the green pellets are treated in the air blast drying section (1), the treatment temperature is controlled to be 150-180 ℃, the treatment time is 2-4 min, and the air blast speed is 3-4 m/s.
4. The production method for reducing pulverization of pellets as claimed in claim 2, wherein: when green pellets are treated in the blast drying section (1), in addition to the conventional blast mixing section (9), the air quantity of the preheating section (3), the roasting section (4), the soaking section (5) and the cooling section (7) on the belt type roasting machine is mixed with air to the blast drying section (1), and the drying air quantity is increased.
5. The production method for reducing pulverization of pellets as claimed in claim 4, wherein: for 300m2The traveling grate of (1), wherein the air flow from the cooling secondary section (7) to the blast drying section (1) is controlled to 6000 to 7000m3The air quantity from the soaking section (5) to the blast drying section (1) is controlled to be 3000-4000 m3The air quantity from the preheating section (3) to the baking section (4) to the blast drying section (1) is controlled to be 6000-8000 m3/min。
6. The production method for reducing pulverization of pellets according to any one of claims 1 to 5, wherein: in the second step, the pelletizing time is controlled to be 16-18 min, and the consolidation time is 2 min.
7. The production method for reducing pulverization of pellets as claimed in claim 6, wherein: in the second step, the water content of the green pellet is controlled to be 7-8%, and the diameter of the green pellet is controlled to be 12.5-13.5 mm.
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| CN202210188358.6A Pending CN114410958A (en) | 2022-02-28 | 2022-02-28 | Production method for reducing pulverization of pellets |
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| WO2024124896A1 (en) * | 2022-12-15 | 2024-06-20 | 中冶长天国际工程有限责任公司 | Pellet drying and roasting process based on roasting system |
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| WO2024124896A1 (en) * | 2022-12-15 | 2024-06-20 | 中冶长天国际工程有限责任公司 | Pellet drying and roasting process based on roasting system |
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