A method for producing hematite concentrate using limonite rich powder

Abstract

This invention discloses a method for producing hematite concentrate from rich limonite powder. The rich limonite raw material has a moisture content of 9% or less. The raw material enters a dry grinding mill through a vibrating feeder at a controlled flow rate. The mineral particles produced by grinding are heated and sorted using circulating high-temperature flue gas and then captured by a gravity dust collector and dust collector to produce the hematite concentrate. This method reduces the production costs of sintered ore and pelletized ore, improves productivity, and reduces overall energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of steel smelting, and in particular to a method for producing hematite concentrate by utilizing limonite rich powder. Background Art

[0002] During the processing of pre-iron products (sintered ore and pellets) at steel mills, a certain proportion of concentrate powder is added to ensure the sintered ore and pellets possess appropriate physical and metallurgical properties. The addition of concentrate powder to pelletize sintered ore generates a liquid phase in the appropriate proportion, allowing for bonding and agglomeration. Pellets utilize the large surface area and strong capillary water absorption properties of concentrate powder to form pellets, which consolidate through a solid-liquid reaction during roasting.

[0003] Currently, the mainstream iron ore concentrates are hematite and magnetite, both produced through a grinding-beneficiation process. Compared to limonite (5 ≤ ≤ 5.5), hematite (5.5 ≤ ≤ 6 hardness) and magnetite (5.5 ≤ ≤ 6.5 hardness) have higher Hardgrove Grindability coefficients, resulting in higher grinding energy consumption and costs.

[0004] Compared with limonite (3.3≤true density≤4.3), hematite (4.9≤true density≤5.3) and magnetite (4.9≤true density≤5.2) have higher true density and smaller specific surface area. The granulation effect of the produced concentrate is lower than that of limonite concentrate. However, limonite concentrate contains crystalline water, which will cause the pelletizing balls to burst during sintering or roasting, reduce the permeability of the sintering and pelletizing processes, and lead to an increase in the return rate, a decrease in productivity, and an increase in energy consumption. The hematite concentrate produced from limonite rich powder has a large specific surface area and a good granulation effect, which can reduce the amount of additives used to enhance the granulation effect during the granulation process.

[0005] The price of rich limonite powder is the lowest among all iron ore powders. Researching and developing new technologies to produce hematite concentrate by grinding limonite rich powder can reduce the cost of sintered ore and pelletized ore, improve productivity and reduce overall energy consumption. It is a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0006] Purpose of the invention: In view of the shortcomings and defects of the existing technology, the present invention provides a method for producing hematite concentrate using limonite rich powder, which reduces the production cost of sintered ore and pelletized ore, improves productivity and reduces comprehensive energy consumption.

[0007] Technical solution: The present invention provides a method for producing hematite concentrate using limonite rich powder, characterized in that: the moisture content of the limonite rich powder raw material is ≤9%; the raw material enters a dry grinding mill through a vibrating feeder with a regulated flow rate, the mineral particles generated by the grinding are heated and sorted using circulating high-temperature flue gas, and are captured by a gravity dust collector and a bag dust collector;

[0008] The dust-laden flue gas first passes through a gravity dust collector to remove more than 70% of the mineral particles, and then passes through a primary heat exchanger for heat exchange to reduce the flue gas temperature to ≤350℃; the dust-laden flue gas is then removed by a dust collector, and the dust content of the flue gas after dust removal is ≤10mg / m3, and then passes through a secondary heat exchanger for heat exchange to reduce the flue gas temperature to ≤150℃; part of the flue gas is discharged, and part of the flue gas enters the variable frequency circulation fan through an adjustable reflux baffle door, and the reflux flue gas enters the flue gas main pipe of the dry mill and mixes with the high-temperature flue gas from the afterburning furnace. The flue gas temperature after mixing is between 500℃ and 550℃. After mixing, the high-temperature flue gas enters the dry mill to heat and sort the limonite rich powder raw material, decompose the limonite crystal water, and obtain the hematite concentrate product.

[0009] Among them, the primary heat exchanger and the secondary heat exchanger use air in series for heat exchange. Cold air enters from the secondary heat exchanger, passes through the primary heat exchanger, and enters the supplementary burning furnace. After heat exchange, the hot air is used to support combustion in the supplementary burning furnace, and the supplementary burning furnace fuel uses blast furnace gas.

[0010] The amount of flue gas generated by the supplementary combustion furnace is regulated by a fuel regulating valve, and the amount of fuel and air is set according to the air-fuel ratio.

[0011] The total amount of flue gas required by the dry grinding machine = the amount of flue gas generated by the afterburning furnace + the amount of refluxed flue gas.

[0012] The dust particle size of the hematite concentrate product is controlled by the flow rate of high-temperature flue gas, and the flow rate of high-temperature flue gas is adjusted by a variable frequency circulating fan.

[0013] The hematite concentrate collected by the gravity dust collector and dust collector is transported to the ore storage tank through a pneumatic conveying system.

[0014] Wherein, the particle size of the hematite concentrate product is -0.074mm particle size ≥60%.

[0015] The limonite-rich powder raw material is located in a limonite storage tank and then enters a vibrating feeder.

[0016] Wherein, the vibrating feeder is a variable frequency vibrating feeder, and the dry grinding mill is a dry vertical grinding mill.

[0017] Wherein, the dust collector is a bag dust collector, and the primary heat exchanger and the secondary heat exchanger are both tubular heat exchangers.

[0018] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: the present invention uses rich limonite powder to produce hematite concentrate through dry grinding, thereby obtaining concentrate powder with a large specific surface area that is more suitable for sintering and pelletizing production needs, so as to achieve the purpose of reducing the production cost of sintered ore and pelletized ore, improving productivity and reducing comprehensive energy consumption.

[0019] This invention can be applied to steel companies that use concentrate powder as raw material for sintering and pelletizing processes, reducing the overall cost of iron materials before ironmaking. Compared with wet grinding, it uses less water, occupies less floor space, and emits fewer pollutants. The processing cost per ton of ore is ≤ 40 yuan, which is ≥ 60 yuan less than that of imported hematite concentrate powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0022] The price of rich limonite powder is the lowest among all iron ore powders. If rich limonite powder is used to produce hematite concentrate through grinding, the cost of sintered ore and pelletized ore can be reduced. Because the hematite concentrate produced from limonite has a large specific surface area and good pelletizing effect, it is more suitable for sintering and pelletizing production processes, which can reduce the production cost of sintered ore and pelletized ore, improve productivity, and reduce overall energy consumption. To this end, the present invention provides the following solution:

[0023] The method for producing hematite concentrate by utilizing rich limonite powder is characterized in that: the moisture content of the rich limonite powder raw material is ≤9%; the raw material enters a dry grinding machine through a vibrating feeder to adjust the flow rate; the mineral particles generated by the grinding are heated and separated by circulating high-temperature flue gas, and are captured by a gravity dust collector and a dust collector; the dust-containing flue gas first passes through the gravity dust collector to remove more than 70% of the mineral particles, and then passes through a primary heat exchanger for heat exchange to reduce the flue gas temperature to ≤350°C; the dust-containing flue gas is then dedusted by the dust collector, and the dust content of the flue gas after dedusting is ≤10mg / m 3 , heat is exchanged through the secondary heat exchanger to reduce the flue gas temperature to ≤150℃; part of the flue gas is discharged, and part of the flue gas enters the variable frequency circulation fan through the adjustable reflux baffle door. The reflux flue gas enters the flue gas main pipe of the dry grinding mill and mixes with the high-temperature flue gas from the afterburning furnace. The flue gas temperature after mixing is between 500℃-550℃. After mixing, the high-temperature flue gas enters the dry grinding mill to heat and separate the limonite rich powder raw materials, decompose the limonite crystal water, and obtain the hematite concentrate product.

[0024] The primary and secondary heat exchangers utilize air in series heat exchange. Cold air enters the secondary heat exchanger, passes through the primary heat exchanger, and enters the afterburner. The hot air after heat exchange is used to support combustion in the afterburner, which uses blast furnace gas. The flue gas volume generated by the afterburner is regulated by a fuel regulating valve, with the fuel and air usage set according to the air-fuel ratio. The total flue gas required by the dry grinding mill equals the flue gas volume generated by the afterburner + the return flue gas volume. The dust particle size of the hematite concentrate product is controlled by the high-temperature flue gas flow rate, which is regulated by a variable-frequency circulating fan. The hematite concentrate product, collected by the gravity dust collector and dust collector, is pneumatically conveyed to the ore storage hopper. The hematite concentrate product has a particle size of ≥60% of the -0.074mm fraction. The limonite enriched fines are stored in the limonite storage hopper and then enter the vibrating feeder. The vibrating feeder is a variable-frequency vibrating feeder, and the dry grinding mill is a dry vertical mill. The dust collector is a bag dust collector, and the primary heat exchanger and the secondary heat exchanger are both tubular heat exchangers.

[0025] The present invention produces hematite concentrate by dry-grinding limonite. During the grinding process, the crystal water of the limonite is removed, resulting in a concentrate with a large specific surface area and excellent pelletizing effect. This improves the productivity of the sintering and pelletizing processes, reduces emissions, and lowers the cost per ton of iron. This solves the problem that steel companies cannot use limonite concentrate in large quantities due to its inherent characteristics, high crystal water content, and sintering and pelletizing process limitations.

[0026] According to tests, compared with wet grinding, the present invention reduces the use of water resources, occupies a small area, emits less pollutants, and has a processing cost of 40 yuan per ton of ore. Compared with imported hematite concentrate powder, the cost per ton of ore is reduced by 60 yuan or more.

Claims

1. A method for producing hematite concentrate using limonite rich powder, characterized by: The moisture content of the limonite-rich powder raw material is ≤9%. The raw material enters the dry grinding mill through a vibrating feeder to adjust the flow rate. The mineral particles produced by grinding are heated and sorted using circulating high-temperature flue gas and captured by gravity dust collectors and bag dust collectors. The dusty flue gas first passes through a gravity dust collector to remove more than 70% of the mineral particles, and then passes through a primary heat exchanger for heat exchange to reduce the flue gas temperature to ≤350℃; the dusty flue gas is then removed by a dust collector, and the dust content of the flue gas after dust removal is ≤10mg / m 3 , heat is exchanged through the secondary heat exchanger to reduce the flue gas temperature to ≤150℃; part of the flue gas is discharged, and part of the flue gas enters the variable frequency circulation fan through the adjustable reflux damper door. The reflux flue gas enters the flue gas main pipe of the dry grinding mill and mixes with the high-temperature flue gas from the afterburning furnace. The flue gas temperature after mixing is between 500℃ and 550℃. After mixing, the high-temperature flue gas enters the dry grinding mill to heat and separate the limonite rich powder raw materials, decompose the limonite crystal water, and obtain the hematite concentrate product; The primary heat exchanger and the secondary heat exchanger adopt air series heat exchange. Cold air enters from the secondary heat exchanger, passes through the primary heat exchanger, and enters the afterburning furnace. After heat exchange, the hot air is used for combustion in the afterburning furnace, and the fuel of the afterburning furnace uses blast furnace gas.

2. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The amount of flue gas generated by the supplementary combustion furnace is regulated by a fuel regulating valve, and the amount of fuel and air is set according to the air-fuel ratio.

3. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The total amount of flue gas required by the dry grinding machine = the amount of flue gas generated by the afterburning furnace + the amount of refluxed flue gas.

4. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The dust particle size of the hematite concentrate product is controlled by the flow rate of high-temperature flue gas, and the flow rate of high-temperature flue gas is adjusted by a variable frequency circulating fan.

5. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The hematite concentrate product captured by the gravity dust collector and the dust collector is transported to the ore storage tank through the pneumatic conveying system.

6. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The particle size of the hematite concentrate product is -0.074mm, and the particle size is ≥60%.

7. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The limonite rich powder raw material is placed in a limonite storage tank and then enters a vibrating feeder.

8. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The vibrating feeder is a variable frequency vibrating feeder, and the dry grinding mill is a dry vertical grinding mill.

9. The method for producing hematite concentrate using limonite rich powder according to claim 1, wherein: The dust collector is a bag dust collector, and the primary heat exchanger and the secondary heat exchanger are both tubular heat exchangers.

Images