Method for dry grinding, automatic grading and thermochemical activation of coarse mineral powder

Abstract

The invention discloses a dry grinding, automatic grading and thermochemical activation method for coarse ore powder, which comprises the following steps: 1) mixing limonite and specularite according to a ratio of 7: 3, and carrying out dry grinding to form embedded novel fine grinding iron ore powder; 2) dynamically drying for more than 28 seconds through a thermal medium at 450-550 DEG C to remove 1.5-6.5% of crystal water from materials entering a mill, promoting conversion of 10-30% of limonite phase into hematite, reducing the heat sensitivity and burning loss of the hematite, and improving the roasting performance of the pellets; (3) through dynamic drying-vertical roller milling integrated pretreatment, the surface activity and the surface energy of the coarse iron ore powder are improved under the action of a thermal medium and mechanical force; and (4) finished fine ground iron powder collected by the cloth bag powder collector is conveyed to a finished product bin for storage through a closed chute and a bucket elevator, is metered by a sealed belt weigher, is humidified by a humidifier and then enters an M1 belt to participate in pellet batching. According to the method, the adding proportion of specularite and limonite powder in pellet production is greatly increased, the wide caliber of pellet raw materials is achieved, and the raw material production cost of pellet ore is reduced.

Description

Technical Field

[0001] The invention relates to the field of mineral processing, and in particular to a method for dry grinding, automatic grading and thermochemical activation of coarse ore powder under the action of a heat medium. Background Art

[0002] Limonite has high porosity and strong water holding capacity, making it difficult to settle and filter during wet grinding. Specularite has low surface activity and high resistance to particle migration during roasting. Under a high proportion of hematite-limonite, the thermal stability of the raw pellets is poor, the bursting temperature is low, and the crack rate of the pellets is high; the roasting temperature is high, and the process energy consumption is high; the finished pellets have poor consolidation and low strength.

[0003] In view of the above situation, it is necessary to develop new technologies in a targeted manner to solve the problem that single mirror iron ore powder is difficult to form into balls, and single limonite powder is highly hydrophilic and easy to deform; to break through the technical bottleneck of preparing pellets with high proportion of mirror iron ore / limonite powder, and greatly increase the proportion of mirror iron ore and limonite powder in pellet production. Summary of the invention

[0004] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a method for dry grinding, automatic grading and thermochemical activation of coarse ore powder, which solves the problem that single mirror iron ore powder is difficult to form into balls, and single limonite powder has strong hydrophilicity and is easy to deform; it breaks through the technical bottleneck of preparing pellets with high proportion of mirror iron ore / limonite powder, greatly improves the addition ratio of mirror iron ore and limonite powder in pellet production, realizes the wide-caliber pellet raw materials, and reduces the raw material production cost of pellet ore.

[0005] Technical solution: A method for dry grinding, automatic classification and thermochemical activation of coarse ore powder of the present invention is characterized by comprising the following steps:

[0006] 1) Mixing limonite and specularite in a ratio of 7:3 and dry grinding to form a mosaic of new finely ground iron ore powder;

[0007] 2) Dynamic drying with a hot medium at 450℃ to 550℃ for more than 28s removes 1.5% to 6.5% of the crystal water of the material entering the mill, promotes the conversion of 10% to 30% of the limonite mineral phase into hematite, reduces its thermal sensitivity and burning loss, and improves the roasting performance of the pellets;

[0008] 3) Through the integrated pretreatment of dynamic drying and vertical roller mill, the surface activity and surface energy of the coarse iron ore powder can be improved under the action of heat medium and mechanical force, and the Blaine specific surface area reaches 3000cm 2 / g or more;

[0009] 4) The finished finely ground iron ore concentrate collected by the bag collector is transported to the finished product warehouse through the closed chute and bucket elevator for storage, and then measured by the sealed belt scale and humidified by the humidifier before being transported to the M1 belt to participate in pelletizing.

[0010] The grinding mill is connected with a grinding belt, a metering belt, a disc, and 6-8 batching bins in sequence.

[0011] Among them, the 6-8 batching bins are pre-batch chambers 6#, 7#, and 8# pre-batch bins for storing iron ore.

[0012] Wherein, the grinding mill is connected with the powder collector, the finished product bin and the MA belt in sequence.

[0013] Wherein, the grinding mill is connected with a drying furnace.

[0014] Wherein, the drying furnace performs drying by burning blast furnace gas.

[0015] Wherein, the powder collector is provided with an induced draft fan.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention partially converts limonite with high crystal water content and strong heat sensitivity into fine-grained hematite; at the same time, it can improve the surface activity of specularite and reduce the resistance of particle migration during roasting. After limonite and specularite are ground in appropriate proportions, they are added to the pellet production in a certain proportion, which can reduce the burning loss of the mixture, improve the surface activity of the pelletizing raw material particles, and significantly improve the balling performance of the mixture and the roasting performance of the pellets. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0019] A method for dry grinding, automatic classification and thermochemical activation of coarse ore powder of the present invention comprises the following steps:

[0020] 1) Mixing limonite and specularite in a ratio of 7:3 and dry grinding to form a mosaic of new finely ground iron ore powder;

[0021] 2) Dynamic drying with a hot medium at 450℃ to 550℃ for more than 28s removes 1.5% to 6.5% of the crystal water of the material entering the mill, promotes the conversion of 10% to 30% of the limonite mineral phase into hematite, reduces its thermal sensitivity and burning loss, and improves the roasting performance of the pellets;

[0022] 3) Through the integrated pretreatment of dynamic drying and vertical roller mill, the surface activity and surface energy of the coarse iron ore powder can be improved under the action of heat medium and mechanical force, and the Blaine specific surface area reaches 3000cm 2 / g or more;

[0023] 4) The finished finely ground iron ore concentrate collected by the bag collector is transported to the finished product warehouse through the closed chute and bucket elevator for storage, and then measured by the sealed belt scale and humidified by the humidifier before being transported to the M1 belt to participate in pelletizing.

[0024] The mill of the present invention is connected with the milling belt, the metering belt, the disc, and the 6-8 batching bins in sequence. The 6-8 batching bins are pre-batch chambers 6#, 7#, and 8# pre-batch bins for storing iron ore. The mill is connected with the powder collector, the finished product bin, and the MA belt in sequence. The mill is connected with the drying furnace. The drying furnace dries by burning blast furnace gas. The powder collector is provided with an induced draft fan.

[0025] The raw material system of the present invention uses the pre-batch chamber 6#, 7#, and 8# pre-batch bins to store iron ore. It is connected in parallel with the original system and does not affect the normal operation of the original system. The disc feeder at the bottom of the pre-batch bin and the metering belt conveyor are used to transport the iron ore to the mill belt conveyor, and then the iron ore is sent to the mill for grinding through the screw conveyor.

[0026] The powder making system of the present invention: the raw material enters the vertical mill through the screw conveyor and falls between the grinding disc and the grinding roller. The grinding roller is loaded with a grinding force to crush the iron ore through a system composed of a hydraulic cylinder, an accumulator and a hydraulic device. The grinding disc is driven by a motor through a gear reducer. The hot air blown out of the air nozzle ring installed on the outside of the grinding disc dries the iron ore powder after rolling.

[0027] The automatic classification of the present invention: the finished iron ore powder after rolling is transported to the powder classifier by hot air, the motor drives the powder classifier blades to rotate, and the centrifugal force generated by the powder classifier classifies the finished ore powder. The finished ore powder of the specified fineness is transported to the next process through the powder classifier, the finished ore powder of the medium grade falls on the grinding disc and is crushed and rolled again, and the slag of the coarser grade will be discharged from the grinding disc and transported to the feeding device by the external circulation system, and then sent to the mill for rolling together with the new raw materials.

[0028] The hot blast furnace heating system of the present invention is equipped with a hot blast furnace, and the fuel medium of the hot blast furnace adopts blast furnace gas. The hot blast generated by burning the blast furnace gas is mixed with the self-circulating flue gas of the pulverizing system and then enters the mill.

[0029] The finished product batching system of the present invention: the finished finely ground iron ore concentrate collected by the bag powder collector is transported to the finished product warehouse for storage by a closed chute and a bucket elevator, and then is measured by a sealed belt scale, humidified by a humidifier, and then sent to the M1 belt to participate in pelletizing.

[0030] The invention solves the problem that single specularite powder is difficult to form into balls, and single limonite powder has strong hydrophilicity but is easy to deform; it breaks through the technical bottleneck of preparing pellets with high-ratio specularite / limonite powder, greatly improves the addition ratio of specularite and limonite powder in pellet production, realizes the wide-caliber pellet raw materials, and reduces the raw material production cost of pellet ore.

[0031] Finely ground powder is added to the pellet raw materials in a certain proportion to improve the strength and thermal explosion resistance of the green balls, reduce the impact of high burning loss and high crystallization water iron ore powder roasting on the pellet structure, and reduce the amount of bentonite from the initial 1.5% to 0, thereby producing acid-base balance benefits in the large system before iron.

[0032] The particle size of the coarse ore powder is significantly finer, with a specific surface area of ​​up to 3000cm 2 ·g-1 or more; the particle size distribution of dry-milled powder is wide, which is conducive to the compact packing of iron ore particles and also helps to improve the ball-forming property. The static ball-forming property index is increased by more than 1 times.

[0033] According to the test, the proportion of post-grinding powdered limonite added by Nangang Enterprise is 20%, the monthly pellet output is 220,000 tons, the ore consumption coefficient is 1.025, the average price difference between magnetite and low-grade brown hematite is 300 yuan·t-1, and the annual effective operating time is 11 months. The annual raw material structure cost reduction benefit is approximately: 220,000 tons × 1.025 × 20% × 11 months × 300 yuan / ton = 148.83 million yuan / year.

Claims

1. A method for dry grinding, automatic classification and thermochemical activation of coarse ore powder, characterized in that: The steps include: 1) Mixing limonite and specularite in a ratio of 7:3 and dry grinding to form a mosaic of new finely ground iron ore powder; 2) Dynamic drying with a hot medium at 450℃ to 550℃ for more than 28s removes 1.5% to 6.5% of the crystal water of the material entering the mill, promotes the conversion of 10% to 30% of the limonite mineral phase into hematite, reduces its thermal sensitivity and burning loss, and improves the roasting performance of the pellets; 3) Through the integrated pretreatment of dynamic drying and vertical roller mill, the surface activity and surface energy of the coarse iron ore powder can be improved under the action of heat medium and mechanical force, and the Blaine specific surface area reaches 3000cm 2 / g or more; 4) The finished finely ground iron ore concentrate collected by the bag collector is transported to the finished product warehouse through the closed chute and bucket elevator for storage, and then measured by the sealed belt scale and humidified by the humidifier before being transported to the M1 belt to participate in pelletizing.

2. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 1, characterized in that: The grinding machine is connected with a grinding belt, a metering belt, a disc and 6-8 batching bins in sequence.

3. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 2, characterized in that: The 6-8 batching bins are pre-batch chambers 6#, 7#, and 8# pre-batch bins for storing iron ore.

4. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 1, characterized in that: The grinding mill is connected with a powder collector, a finished product bin and an MA belt in sequence.

5. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 1, characterized in that: The mill is connected with a drying furnace.

6. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 5, characterized in that: The drying furnace performs drying by burning blast furnace gas.

7. The method for dry grinding, automatic classification and thermochemical activation of coarse ore powder according to claim 1, characterized in that: The powder collector is provided with an induced draft fan.

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