Application method of limonite type laterite-nickel ore in sintered ore production

Abstract

According to the method, blast furnace return ore and limonite type laterite-nickel ore are used for stirring, important parts such as a trough front grid plate and a small ore trough grid plate are densified, hematite and magnetite are used in cooperation in low-alkalinity sintered ore production, and sintering and blast furnace positive coping adjustment operation modes and other modes are adopted, so that the defects of limonite type laterite-nickel ore sintered ore are overcome; on the basis of not influencing the quality and the yield of the sintered ore, the limonite type laterite-nickel ore is applied to the production of the sintered ore, and the monovalent advantage of the laterite-nickel ore and the benefits of the Ni element to part of steel types are fully utilized.

Description

Technical Field

[0001] The present technology relates to the technical field of iron ore sintering, and in particular to an application method of limonitic laterite nickel ore in sintered ore production. Background Art

[0002] Laterite nickel ore has the advantages of rich reserves and low mining difficulty. With the continuous improvement of its processing technology, it has become the main raw material for nickel production. According to the profile of its deposit, laterite nickel ore is divided into limonite type (Ni: 0.8% ~ 1.5%; TFe: 40% ~ 52%), transition type (Ni: 1.5% ~ 1.8%; TFe: 25% ~ 40%) and sapropelic type (Ni: 1.8% ~ 3.0%; TFe: 10% ~ 25%) from the surface to the bottom. The pyrometallurgical treatment process of laterite nickel ore has gradually become the mainstream production process of laterite nickel ore with its advantages of short process, wide range of raw material adaptability and relatively mature process.

[0003] Different from the high-grade iron concentrate used in conventional blast furnace ironmaking, limonitic laterite nickel ore is a low-grade complex ore without pre-enrichment processes such as beneficiation. It contains about 50% iron and has an iron grade more than 10% lower than that of iron concentrate. The particle size is between concentrate powder and rich ore. The ore powder is yellow (the water-containing part is yellowish brown) and contains a certain amount of nickel. The distribution ratio of nickel in molten iron is close to 100% (that is, it basically does not enter the slag). However, nickel has no obvious disadvantages to blast furnace smelting, and even has certain benefits when smelting some steel grades. Therefore, this ore powder can be treated as a general raw material in the sintering batching.

[0004] Because laterite nickel ore has high viscosity, high moisture content, and contains a large amount of stones and other debris, sintering may cause material slack and material unloading difficulties during the batching process. Therefore, there are many difficulties in the sintering and blast furnace smelting process. Limonite-type laterite nickel ore has high physical water and crystallization water content, high aluminum content, easy material adhesion, and is not easy to load and transport. It has the characteristics of large burn-out, fast sintering speed, short high-temperature retention time of sintered ore, low sintering terminal temperature, and fast cooling speed of the material surface, which leads to poor sintering permeability, high energy consumption, and low yield rate. After low-quality sintered ore enters the blast furnace, it leads to high energy consumption, increased slag volume, and the position of the blast furnace soft melting zone is biased upward. The permeability of the upper charge of the blast furnace deteriorates, and the temperature of the molten iron in the lower part of the furnace cylinder drops, which affects the fluidity of the molten iron and causes difficulties in separating slag and iron.

[0005] At present, domestic enterprises generally have problems such as low sintering ore yield, high return ore volume, low drum strength, and unsatisfactory particle size distribution in the sintering production process of laterite nickel ore. In addition, due to the large fluctuations in the chemical composition of nickel grade, iron grade, etc. of laterite nickel ore of different types and regions, domestic enterprises rely entirely on imports for laterite nickel ore raw materials, resulting in unstable raw material sources and other factors that significantly increase the difficulty of production.

[0006] The invention patent with patent number 201810025669.4 discloses a sintering method for laterite nickel ore. The alkalinity setting value of the invention is 1.2, which is a self-fluxing sintered ore. However, most steel mills mainly use a combination of high-alkali sintered ore and low-alkali sintered ore in production practice.

[0007] This invention mainly studies the sintering performance of single-fired laterite nickel ore. Single-fired ore powder is limited by indicators and mineral properties, has poor economic and technical indicators, and is difficult to apply in practical production. Summary of the invention

[0008] In view of the above problems existing in the sintering of limonitic laterite nickel ore and the production of molten iron in blast furnace smelting, the present invention provides a method for using limonitic laterite nickel ore as a general sintering raw material in the practical production of low-alkali sintered ore to solve the above technical problems.

[0009] The present invention provides a method for using limonitic laterite nickel ore as a general sintering raw material in the practical production of low-alkali sintered ore, comprising: Firstly, blast furnace return ore is mixed with nickel-containing ore powder in a ratio of 3:1. The moisture content of nickel ore is balanced by utilizing the dry and water-free property of blast furnace return ore. The adverse effect of easy adhesion of nickel ore is weakened by utilizing the property of blast furnace return ore with more particles and less powder. After mixing, the ore trough with freshly prepared blast furnace return ore is used for loading. According to the amount of blast furnace return ore, the ratio of laterite nickel ore mixed with blast furnace return ore in the sintering mixture is maintained between 10% and 17%.

[0010] Then, the laterite nickel ore is mixed with high return, sintered iron-containing coarse ore powder, concentrate powder, sintering flux and sintering solid fuel, and water is added to prepare a sintering mixture, and the sintering mixture is sintered under high-temperature sintering conditions.

[0011] Furthermore, the high temperature sintering conditions include: The binary basicity of the sintered ore is adjusted by quicklime, and the binary basicity CaO / SiO2 of the sintered ore is controlled to be within the range of ≤0.8 times; the SiO2 content of the sintered ore is controlled to be within the range of 6.5±0.5%; the FeO content of the sintered ore is controlled to be within the range of 12.0±2.0%; the MgO content of the sintered ore is adjusted by magnesite powder, and the MgO content of the sintered ore is controlled to be within the range of 4.0±1.0%; the sintering negative pressure range is controlled to be -15±1kpa; the sintering mixture temperature range is controlled to be >65°C; the sintering ignition negative pressure is controlled to be 50-60% of the sintering negative pressure; the sintering exhaust gas temperature range is controlled to be 140±20°C; the sintering end point position is controlled to be: the second to last bellows; the sintering end point temperature range is controlled to be 480±20°C; the sintering material layer range is controlled to be >700mm.

[0012] Furthermore, the method further comprises: The grate plates in front of the trough, grate plates in small ore troughs and other important parts are denser to reduce the negative impact on production when stones are mixed in the limonite laterite nickel ore.

[0013] Furthermore, the method further comprises: Place the sintering mixture in a small ore hopper and pass steam to the small ore hopper to make the temperature of the mixture reach above 65℃; Control the segregation distribution of small ore bins; Control the ignition negative pressure of the sintering machine to be slightly negative pressure; Control the load of sintering single roll crusher; Control the sinter screening particle size; Control the adjustment of sintering carbon content to ensure that the strength and output of sintered ore are not affected; Furthermore, the starting ignition procedure includes: Turn on the gas and ignite it, start exhaust, start dust removal, start flue gas treatment, and discharge the treated flue gas.

[0014] Furthermore, the method further comprises: The proportion of the limonitic laterite nickel ore in the sintering mixture does not exceed 5.0%, and the proportion of the limonitic laterite nickel ore in the sintering mixture is maintained between 10% and 17%.

[0015] Furthermore, the method further comprises: The suitable proportion of the limonitic laterite nickel ore in the sintering mixture is 3.0±2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0017] Figure 1 is a schematic sintering flow chart of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the examples described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0019] Specifically, the application method of the limonitic laterite nickel ore in sintered ore production includes: Blast furnace return ore is used to mix with nickel-containing ore powder in a ratio of 3:1, and the moisture of nickel ore is balanced by using the dry and water-free characteristics of blast furnace return ore, and the adverse effect of easy adhesion of nickel ore is weakened by using the characteristics of more particles and less powder of blast furnace return ore. After mixing, the ore trough of the freshly prepared blast furnace return ore is used for loading. The proportion of the limonitic laterite nickel ore in the sintering mixture does not exceed 5.0%, and the proportion of laterite nickel ore mixed with blast furnace return ore in the sintering mixture is maintained between 10% and 17% according to the amount of blast furnace return ore.

[0020] The grate plates in front of the trough, grate plates in small ore troughs and other important parts are denser to reduce the negative impact on production when stones are mixed in the limonite laterite nickel ore.

[0021] Control the adjustment of sintering carbon content to ensure that the strength and output of sintered ore are not affected.

[0022] The acidic sinter has a dense structure and a low degree of reduction (RI). It is more appropriate to use limonitic laterite nickel ore in the production of acidic sinter, and the binary basicity CaO / SiO2 of the sinter is controlled in the range of ≤0.8 times.

[0023] SiO2 is the main component of the liquid phase of acidic sintered ore. When the SiO2 content is lower than 5.8%, the amount of liquid phase in the sintered ore is too small and the strength of the sintered ore is poor. When the SiO2 content exceeds 7.0%, the liquid phase in the sintered ore is too much, the brittleness increases, and the strength decreases. Generally, the SiO2 content of acidic sintered ore is controlled at 6.5±0.5%.

[0024] Limonitic laterite nickel ore has high water content, which is not conducive to drum strength, sintering productivity and sintering fuel consumption. The proportion of dense hematite powder and magnetite concentrate powder with poor fluidity can be appropriately increased to ensure drum strength and sintering productivity.

[0025] The laterite nickel ore is mixed with high return, sintered iron-containing coarse ore powder, concentrate powder, sintering flux and sintering solid fuel, and water is added to prepare a sintering mixture, and the sintering mixture is sintered under high temperature sintering conditions.

[0026] The high temperature sintering conditions include: The binary basicity of the sintered ore is adjusted by quicklime, and the binary basicity CaO / SiO2 of the sintered ore is controlled to be within the range of ≤0.8 times; the SiO2 content of the sintered ore is controlled to be within the range of 6.5±0.5%; the FeO content of the sintered ore is controlled to be within the range of 12.0±2.0%; the MgO content of the sintered ore is adjusted by magnesite powder, and the MgO content of the sintered ore is controlled to be within the range of 4.0±1.0%; the sintering negative pressure range is controlled to be -15±1kpa; the sintering mixture temperature range is controlled to be >65°C; the sintering ignition negative pressure is controlled to be 50-60% of the sintering negative pressure; the sintering exhaust gas temperature range is controlled to be 140±20°C; the sintering end point position is controlled to be: the second to last bellows; the sintering end point temperature range is controlled to be 480±20°C; the sintering material layer range is controlled to be >700mm.

[0027] Place the sintering mixture in a small ore hopper and pass steam to the small ore hopper to make the temperature of the mixture reach above 65°C; Control the segregation distribution of small ore bins; Control the sintering machine to start the ignition procedure, that is, to ignite the gas, start the exhaust, start the dust removal, start the flue gas treatment, and discharge the treated flue gas; Control the load of sintering single roll crusher; After the sintered ore is cooled, it is screened. The ore with a particle size of less than 5 mm is added to the sintering mixture as a circulating return ore, the ore with a particle size of 8 to 20 mm is used as an auxiliary base material, and the rest enters the ore trough of the blast furnace.

[0028] The following are test examples: At 23:35 on May 23, the third burner and at 23:45 on May 23, 15% laterite nickel ore was mixed with high-return coal. At 11:52 on May 26, the ratio of laterite nickel ore mixed with high-return coal was increased by 15% to 17%.

[0029] 1. Laterite nickel ore mixed with high return ingredients According to the statistics of the particle size of the mixture screening, the increase of 6.1% in the particle size of <1mm is the main factor affecting the sintering permeability.

[0030] 2 Mixing particle size after feeding laterite nickel ore When the second and third sintering materials are mixed with laterite nickel ore at a high ratio of 15%, and other conditions remain unchanged, the material layer is significantly reduced by 30 to 50 mm, and the sintering permeability becomes worse.

[0031] 3 Production parameters of secondary calcination using laterite nickel ore The second and third firings are for stable production batches of 91-90kg / t, and the internal return increases by 1kg / t.

[0032] 4. Production parameters of third-burning nickel ore using laterite The second and third fired products are mixed with laterite nickel ore and the drum is reduced by 1% after high return.

[0033] 5 Sintering drum index After the second and third firings with laterite nickel ore mixed with high return, the particle size of sintered ore greater than 40mm has no obvious change.

[0034] 6 Sinter granularity Adjustment of slag making system: After using laterite nickel ore sintering ore, the condition of small blast furnace was obviously improved. In order to ensure good slag fluidity and reduce the difficulty of slag discharge, the basicity was appropriately lowered. In June, the basicity of final slag was reduced by 0.03, which improved the working condition of the furnace and ensured stable and uniform airflow distribution.

[0035] Adjust the thermal system: after using the laterite nickel ore sintering ore, the physical heat of molten iron shows a downward trend, especially in the small blast furnace, the silicon content in pig iron is appropriately increased. In June, the small blast furnace increased it by 0.09%. The physical heat of molten iron was controlled to be >1465℃ for small blast furnaces and >1485℃ for large blast furnaces. The physical heat of molten iron was increased by 10℃ in June for small blast furnaces and 3℃ for large blast furnaces, to ensure sufficient heat in the furnace and stable and smooth furnace conditions.

[0036] Adjust parameter control: raise the theoretical combustion temperature, operate at full air temperature for small blast furnaces, ensure air temperature above 1170℃, and oxygen enrichment of 8500~9000min / h; ensure air temperature above 1200℃ and oxygen enrichment of 14000min / h for large blast furnaces. Strictly control the pressure-volume relationship, actively add air if conditions permit, increase blast kinetic energy, activate the furnace, and increase air volume for large blast furnaces in June 137m 3 / min, laying a solid foundation for the stable and smooth operation of the furnace condition after using laterite nickel ore sintering.

[0037] The purpose of material adjustment is to stabilize the edge and center airflows, prevent the edge airflow from overdeveloping, eliminate pipeline travel, and reduce slag skin shedding. Small blast furnaces gradually move the ore coke platform outwards and properly guide the center airflow. Large blast furnaces gradually move the ore coke platform inwards and properly develop the edge airflow, eventually forming two stable airflows.

[0038] Strengthen the discharge of slag and iron, contact the distribution tank in time to discharge iron, and ensure that the iron interval is within 20 minutes. Control the flow rate of molten iron to ensure that the amount of smelting slag and iron is balanced with the discharge amount, and there is no slag and iron in the furnace. Spray the iron mouth more than 2 times per shift to activate the furnace to prevent accumulation.

[0039] Nippon Steel Yingkou Medium Plate Co., Ltd. has overcome the shortcomings of limonitic laterite nickel sinter by mixing blast furnace return ore with limonitic laterite nickel ore, increasing the density of important parts such as the grate plate in front of the trough and the grate plate of the small ore trough, using hematite and magnetite in the production of low-alkalinity sinter, and actively adjusting the operation methods of sintering and blast furnace. On the basis of not affecting the quality and output of the sintered ore, limonitic laterite nickel ore has been applied in the production of sintered ore, making full use of the unit price advantage of laterite nickel ore and the benefits of Ni element to some steel grades.

Claims

1. A method for applying limonitic laterite nickel ore in sintered ore production, Features: The blast furnace return ore and the iron-containing laterite nickel ore powder are mixed in a ratio of 3:1, and the moisture of the nickel ore is balanced by using the dry and water-free characteristics of the blast furnace return ore, and the adverse effect of the easy adhesion of the nickel ore is weakened by using the characteristics of the blast furnace return ore with more particles and less powder. After mixing, the ore trough of the blast furnace return ore is used for feeding, and according to the amount of blast furnace return ore, the ratio of laterite nickel ore mixed with blast furnace return ore in the sintering mixture is maintained between 10% and 17%; Mixing laterite nickel ore with high return, sintering iron-containing coarse ore powder, concentrate powder, sintering flux, and sintering solid fuel, adding water to prepare a sintering mixture, and sintering the sintering mixture under high temperature sintering conditions; sintering the sintering mixture under high temperature sintering conditions; Wherein, the high temperature sintering conditions include: The binary basicity of the sintered ore is adjusted by quicklime, and the binary basicity CaO / SiO2 of the sintered ore is controlled to be within the range of ≤0.8 times; the SiO2 content of the sintered ore is controlled to be within the range of 6.5±0.5%; the FeO content of the sintered ore is controlled to be within the range of 12.0±2.0%; the MgO content of the sintered ore is adjusted by magnesite powder, and the MgO content of the sintered ore is controlled to be within the range of 4.0±1.0%; the sintering negative pressure range is controlled to be -15±1kpa; the sintering mixture temperature range is controlled to be >65°C; the sintering ignition negative pressure is controlled to be 50-60% of the sintering negative pressure; the sintering exhaust gas temperature range is controlled to be 140±20°C; the sintering end point position is controlled to be: the second to last bellows; the sintering end point temperature range is controlled to be 480±20°C; the sintering material layer range is controlled to be >700mm. The grate plates in front of the trough, grate plates in small ore troughs and other important parts are denser to reduce the negative impact on production when stones are mixed in laterite nickel ore.

2. Application of a limonitic laterite nickel ore according to claim 1 in sintered ore production, It is characterized in that The method further comprises: Place the sintering mixture in a small ore hopper and pass steam to the small ore hopper to make the temperature of the mixture reach above 65℃; Control the segregation distribution of small ore bins; Control the ignition negative pressure of the sintering machine to be slightly negative pressure; Control the load of sintering single roll crusher; Control the particle size of sintered ore screening; Control the adjustment of sintering carbon content to ensure that the strength and output of sintered ore are not affected; Control the load of sintering single roll crusher; After the sintered ore is cooled, it is screened. The ore with a particle size of less than 5 mm is added to the sintering mixture as a circulating return ore, the ore with a particle size of 8 to 20 mm is used as an auxiliary bottom material, and the rest enters the ore trough of the blast furnace.

3. The method for applying a limonitic laterite nickel ore in sintered ore production according to claim 3, It is characterized in that Starting the ignition program includes: passing gas for ignition, starting ventilation, starting dust removal, starting fume treatment, and discharging the treated fume.

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