CN109652643B

CN109652643B - High-quality sinter for COREX smelting reduction iron-making process and preparation method thereof

Info

Publication number: CN109652643B
Application number: CN201910091107.4A
Authority: CN
Inventors: 朱德庆; 潘建; 郭正启; 李启厚; 薛钰霄; 李思唯; 田宏宇; 石玥; 鲁胜虎; 徐继伟; 王欣
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2019-01-30
Filing date: 2019-01-30
Publication date: 2020-09-01
Anticipated expiration: 2039-01-30
Also published as: CN109652643A

Abstract

The invention provides a sinter for a COREX smelting reduction iron-making process and a preparation method thereof, wherein 30-50% of iron ore concentrate and 4-7% of iron ore concentrate are divided from the total amount of the iron ore concentrateThe flux 1 and 1.0-1.5 percent of solid fuel are mixed evenly to prepare flux-type internal-matched carbon green pellets; mixing the residual iron ore concentrate after shunting with iron-containing miscellaneous materials, return ores, a flux 2 and solid fuel, and uniformly mixing to obtain a mixture; and mixing the obtained green pellets and the mixture for granulation, material distribution, ignition, sintering, cooling, crushing and screening to obtain sintered ore and return fine. The sintered ore prepared by the method can meet the low-temperature reduction degradation value RDI of the sintered ore by the COREX shaft furnace when the alkalinity is 1.8_+6.3More than or equal to 50 percent, and the mass ratio of the sintering ore to the furnace can be more than 50 percent, thereby effectively reducing the cost of the iron-making furnace charge.

Description

High-quality sinter for COREX smelting reduction iron-making process and preparation method thereof

Technical Field

The invention relates to the field of ferrous metallurgy, in particular to a high-quality sinter for a COREX smelting reduction iron-making process and a preparation method thereof.

Background

COREX is a smelting reduction iron-making process developed by the austempered steel union, which uses lump ore or pellet ore as a raw material and uses non-coking coal as a reducing agent and fuel. The COREX process is the only smelting reduction iron-making process for realizing the industrial production at present, adopts non-coking coal as main disposable energy and reducing agent, only uses a small amount of coke, can produce molten iron with the quality equivalent to that of blast furnace iron-making, greatly reduces the dependence of the iron-making process on high-quality metallurgical coke, has the characteristics of coal-substituted coke, short flow, small environmental pollution and the like, and meets the strategic requirements of sustainable development of the steel industry in China. China has abundant coal resources and huge non-coking coal reserves, and the development of the COREX smelting reduction technology has the advantages of innate energy. However, the charging materials of the COREX iron-making system are mainly pellet and lump ore, and the pellet production capacity is limited in China and the high-quality lump ore resources are deficient. Therefore, when the COREX smelting reduction process is developed in China, the charging material structure in foreign industrial production is used, pellets must be purchased outside or pellet factories must be built by oneself, and the raw material cost of the COREX process is greatly increased. On the other hand, the sinter production capacity in the iron and steel enterprises in China is in a surplus state for a long time, and the existing production capacity resources are not fully utilized. The sintered ore is used in the COREX process in a large amount, so that the cost of ironmaking raw materials can be reduced, the development of the process in China can be promoted, and the energy resource distribution of the existing sintered ore of iron and steel enterprises in China can be optimized. Compared with pellet ore and lump ore, the reduction performance of the sinter ore is better, and the reduction degradation performance is poorer. According to the prior production experience, when the sintered ore is used in a COREX iron-making system, the low-temperature reduction degradation rate of the sintered ore in a COREX shaft furnace is strictly controlled. The low-temperature reduction pulverization performance of the sinter is improved, the breakage rate and pulverization rate of the sinter during reduction in a low-temperature area of the COREX shaft furnace can be reduced, the air permeability of a charge column in the COREX shaft furnace is improved, and the charging proportion of the sinter is improved.

The method for adjusting the components of the sinter by adopting the ore blending is considered to be an effective method for improving the low-temperature reduction degradation of the sinter in a blast furnace, but is limited by factors such as resource conditions, ore blending cost and the like, and is difficult to popularize and apply; at present, in industrial production, most enterprises spray chloride with a certain concentration on the surface of a sinter ore to inhibit low-temperature reduction and pulverization of the sinter ore in a blast furnace, and a good effect is achieved. However, the chloride brought into the blast furnace causes problems of furnace wall damage, pipeline corrosion, exhaust gas pollution aggravation and the like in the blast furnace smelting process.

Chinese patent CN103409616A discloses a method for inhibiting low-temperature reduction degradation of iron ore sinter, which comprises the steps of preparing iron ore concentrate into granulating materials with the granularity of 3-15 mm, uniformly mixing the granulating materials with a sintering mixture, distributing, sintering and roasting; by adding a small amount of flux or solid fuel in the granulating material, optimizing the solid fuel dosage and the flux dosage in the sintering mixture, reducing the negative pressure of air draft of sintering roasting and the cooling speed of the sintering ore, inhibiting the low-temperature reduction degradation of the sintering ore and effectively improving the technical and economic indexes of blast furnace smelting.

At present, the published and reported documents are all directed to a blast furnace ironmaking system, and no report on technical research or industrial production of low-reduction-pulverization-rate sinter preparation for a COREX process is available at home and abroad.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-quality sinter for a COREX smelting reduction iron-making process and a preparation method thereof, aiming at sintering domestic iron ore concentrate mainly to prepare the sinter with good quality index and higher furnace entering ratio, and ensuring that the low-temperature reduction pulverization performance of the sinter in a COREX shaft furnace meets the requirements.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of high-quality sinter for a COREX smelting reduction iron-making process comprises the following steps:

1) preparation of green pellets

30-50% of iron ore concentrate is divided from the total amount of the iron ore concentrate, the iron ore concentrate is mixed with a flux 1 accounting for 4-7% of the iron ore concentrate obtained by dividing and a solid fuel accounting for 1.0-1.5% of the iron ore concentrate obtained by dividing, and green pellets are prepared after uniform mixing;

wherein the flux 1 comprises quicklime and one or more of limestone, dolomite, magnesite or serpentine;

2) preparation of the mix

And (3) mixing the iron ore concentrate left after the shunting with the iron-containing miscellaneous materials, return ores, a flux 2 and solid fuel according to the mass part ratio of (50-60): 5: (25-30): (16-29): (4-8) burdening, and uniformly mixing to obtain a mixture;

wherein the iron-containing miscellaneous materials are one or more of iron-containing dust, iron-containing pellets and iron-containing lump ore undersize powder of a steel mill; the flux 2 comprises limestone and one or more of quick lime, dolomite, magnesite or serpentine;

3) production of sinter

Mixing and granulating the green pellets obtained in the step 1) and the mixture obtained in the step 2) to obtain prepared granules; distributing, igniting, sintering, cooling, crushing and screening the obtained granules to obtain sintered ores and return ores; wherein, the obtained return ores are returned to the step 2) for continuous use.

Preferably, the iron element content in the iron ore concentrate is more than 62.5%; the mass content of the fraction smaller than 0.074mm in the granularity of the iron ore concentrate is larger than 40 percent.

Preferably, the solid fuel comprises coke powder or anthracite.

Preferably, the basicity of the green pellets in step 1) is 0.8-1.2; the mass fraction of MgO in the green pellets is 1.2-1.8%.

Preferably, the diameter of the green pellets in step 1) is 8-20 mm.

The invention also provides a sintered ore for the COREX smelting reduction iron-making process, and the sintered ore is prepared by any one of the methods.

Preferably, the particle size of the sintered ore is 5-40 mm; the alkalinity of the sintered ore is 1.6-2.0; the content of MgO in the sintered ore is 1.6-2.1%.

Preferably, the requirement of the COREX shaft furnace on the low-temperature reduction powdering performance of the sinter can be met when the mass ratio of the sinter to the furnace is higher than 50%.

In a conventional sintering process, the basicity of the sinter is greater than 1.8. The higher the basicity of the sinter, the higher the strength of the sinter, the better the reducibility, and the DRI (reduced degradation rate) at low temperature_+6.3And RDI_+3.15The higher the value of (A), the higher the yield, the more beneficial to the subsequent smelting process, the lower the molten iron production cost and the less the fuel consumption. When the alkalinity of the sintered ore is lower than 1.2, the sintered ore belongs to acid sintered ore, the alkalinity is low, the strength of the sintered ore is increased and is lowThe performance of warm reduction pulverization is improved, but the energy consumption is high and the yield is low. The strength and the low-temperature reduction degradation performance of the sintered ore are the worst when the alkalinity of the sintered ore is 1.4-1.6. Therefore, in order to enable the sinter to be used for iron making by a COREX process, when a conventional sintering process is adopted, the alkalinity of the sinter is required to be more than 2.4, the MgO content is required to be more than 2.4%, the strength and the low-temperature reduction pulverization performance of the sinter can meet the requirements, and the charging proportion of the sinter is only about 20%. The alkalinity and MgO content of the sintered ore are limited by the subsequent smelting, and the higher the alkalinity and MgO content of the sintered ore, the lower the use proportion in the subsequent smelting. In order to reduce the production cost of molten iron, if the use proportion of the sintered ore is increased in the subsequent smelting, the alkalinity and MgO content of the sintered ore must be reduced, which inevitably results in the deterioration of the strength of the sintered ore and the DRI (reduced reduction degradation rate) at low temperature_+6.3And RDI_+3.15The reduction can not affect the subsequent smelting of molten iron, thereby leading to the reduction of the yield of the molten iron and the increase of energy consumption. Therefore, how to solve the problem that the strength, reducibility and low-temperature reduction degradation performance indexes of the sintered ore are basically maintained when the alkalinity and MgO content of the sintered ore are reduced has great significance in improving the proportion of the sintered ore in the subsequent smelting process and improving the economic benefit of enterprises.

The scheme of the invention has the following beneficial effects:

(1) the method provided by the invention can realize the sintering of the ultra-high proportion iron ore concentrate, even the sintering of the full iron ore concentrate, and more reasonably utilize the self-produced iron ore concentrate resources of the iron and steel enterprises in China. According to the method, part of the iron ore concentrate is distributed to a disc pelletizer to be pelletized to prepare raw pellets with the diameter of 8-20mm, other sintering ore raw materials are still treated according to a conventional sintering process, and the raw pellets are mixed with the raw pellets after being mixed for secondary mixing and pelletizing, so that the air permeability of a sintering material layer is improved, the vertical sintering speed and the utilization coefficient are obviously improved, and the problems of poor air permeability of the material layer and poor quality index of sintered ore products during full-concentrate sintering in the conventional sintering process are solved.

(2) By adopting the method provided by the invention, under the condition that the total alkalinity and MgO content of the sintered mineral product are stable, the basicity of green pellets is controlled within the range of fluxed pellets and MgO by adding a small amount of flux (quicklime, limestone and dolomite) and solid fuel into the shunt iron concentrateThe content is properly increased, so that the strength of the pellet part is improved, and the low-temperature reduction degradation performance of the pellet part is improved; the basicity of the mixture of the part treated by the conventional sintering process is improved, the MgO content is reduced, the strength of the part of the sintered ore is increased, and the low-temperature reduction degradation performance is improved. The mineral composition and microstructure of the final finished sintered ore are improved by the measures, and the mosaic structure of the pellet ore with high strength and good low-temperature reduction degradation performance embedded in the sintered ore with high strength and good low-temperature reduction degradation performance is finally formed, so that the strength of the final finished sintered ore is increased, and the DRI value is reduced and degraded at low temperature_+6.3And RDI_+3.15And (4) rising. The finished sintered ore prepared by the method can meet the low-temperature reduction degradation value RDI of the sintered ore by the COREX shaft furnace when the alkalinity is 1.8_+6.3≥50％，RDI_+3.15The method has the advantages that the requirement of more than or equal to 70 percent is met, when the mass percentage of iron-containing furnace materials of the sintering ore in a COREX iron-making system reaches more than 50 percent, the reducing gas in the COREX shaft furnace rises smoothly, the pre-reduction reaction of the furnace materials is sufficient, the shaft furnace runs stably, and the cost of the iron-making furnace materials is reduced. Meanwhile, the dependence of the COREX iron making process on coke is greatly reduced, and the method is a great development of the blast furnace process which heavily depends on the coke oven iron making.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

Comparative example 1

When the alkalinity of the sinter is controlled to be 1.8 and the MgO content is controlled to be 1.3 percent, when the sinter is prepared according to the conventional sintering process, firstly, iron ore concentrate and iron-containing miscellaneous materials (comprising iron-containing dust and iron-containing pellets in a steel mill), return ores, quick lime, limestone, dolomite and solid fuels (coal powder) are weighed and proportioned according to the following mass fractions (95:5:30:4:6:6:7) to meet the chemical component requirements of the sinter for subsequent smelting, then, primary mixing (uniform mixing) and secondary mixing (granulation) are carried out according to the requirements of the conventional sintering process, and finally, the granules are prepared on a sintering machineThe finished product of sinter ore (the grain diameter is 5-40mm) and return fines (5 mm) are prepared by material distribution, ignition, sintering, cooling, whole grain screening. Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 69.60%, the drum strength was 57.60%, and the utilization factor (yield) was 1.40 t.m^-2·h^-1The solid fuel consumption is 35.02 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.323.32% RDI_+3.15The content was 57.91%. At alkalinity of 1.8, the strength of the sinter is poor, the utilization coefficient is low, and the low-temperature reduction degradation performance RDI_+6.3And RDI_+3.15Are all far below the required indexes.

Comparative example 2

When the alkalinity of the sinter is controlled to be 2.0 and the MgO content is controlled to be 1.5 percent, when the sinter is prepared according to the conventional sintering process, firstly, iron ore concentrate and iron-containing miscellaneous materials (comprising iron-containing dust and iron-containing pellets in a steel mill), return ores, quick lime, limestone, dolomite and solid fuel (coke powder) are weighed and proportioned according to a certain mass fraction (92:5:30:4:8:7:7) to meet the chemical component requirements of the sintering ores for subsequent smelting, then, primary mixing (uniform mixing) and secondary mixing (granulation) are carried out according to the requirements of the conventional sintering process, finally, material distribution, ignition, sintering, cooling and granule screening are carried out on a sintering machine to prepare finished sinter and return ores (the particle size is less than 5 mm). Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 71.36%, the drum strength was 60.24%, and the utilization factor was 1.57 t.m^-2·h^-1The solid fuel consumption is 37.02kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.341.56% RDI_+3.15It was 64.78%. At an alkalinity of 2.0, the strength and yield of the sinter are significantly improved. Compared with the comparative example 1, the performance indexes of the sintered ore are obviously improved. However, low temperature reduction degradation performance RDI_+6.3And RDI_+3.15Are all far below the required indexes.

Comparative example 3

When the alkalinity of the sinter is controlled to be 2.4 and the MgO content is controlled to be 2.0 percent, when the sinter is prepared according to a conventional sintering process, firstly, iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust in a steel mill) are weighed and proportioned with return ores, quick lime, limestone, dolomite and solid fuels (coal powder) according to a certain proportion (90:5:30:4:10:8:6) to meet the requirements of subsequent smelting on the chemical components of the sinter, then, primary mixing (uniform mixing) and secondary mixing (granulation) are carried out according to the requirements of the conventional sintering process, and finally, material distribution, ignition, sintering, cooling and granule screening are carried out on a sintering machine to prepare finished products of the sinter and the return ores (the particle size is less than 5 mm). Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 73.36%, the drum strength was 65.24%, and the utilization factor was 1.63 t.m^-2·h^-1The solid fuel consumption is 38.01 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.356.23% RDI_+3.15The content was 70.32%. At alkalinity of 2.4, the strength and yield of the sinter ore are further improved, and the low-temperature reduction degradation performance RDI_+6.3And RDI_+3.15All reach the required indexes. And calculating according to the structure of the subsequent smelting furnace materials, wherein the mass percentage of the sintered ore with the alkalinity of 2.5 entering the furnace is 30 percent. Compared with comparative examples 1 and 2, the low-temperature reduction degradation performance RDI is only obtained when the alkalinity is increased to 2.4 and the MgO content is controlled to 2.0 percent_+6.3And RDI_+3.15All reach the required indexes, but the mass ratio of the raw materials entering the furnace is only 30 percent.

Comparative example 4

When the alkalinity of the sinter is controlled to be 2.6 and the MgO content is controlled to be 2.4 percent, when the sinter is prepared according to the conventional sintering process, firstly, iron ore concentrate and iron-containing miscellaneous materials (comprising iron-containing dust, iron-containing pellets and iron-containing lump ore undersize powder of a steel mill) and return ores, quicklime, limestone, dolomite and solid fuels (coke powder) are weighed and proportioned according to the proportion (88:5:30:4:11:10:5), so as to meet the chemical component requirements of the sintering ore for subsequent smelting, then, primary mixing (uniform mixing) and secondary mixing (granulation) are carried out according to the requirements of the conventional sintering process, and finally, the material distribution and ignition of the granulating material are carried out on a sintering machineSintering, cooling, sieving, and preparing sintered ore and return fine (particle size less than 5 mm). Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 69.25%, the drum strength was 65.27%, and the utilization factor was 1.43 t.m^-2·h^-1The solid fuel consumption is 36.56kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.362.18% RDI_+3.15The content was 80.64%. At alkalinity of 2.4, the strength and yield of the sinter ore are further improved, and the low-temperature reduction degradation performance RDI_+6.3And RDI_+3.15All reach the required indexes. And calculating according to the structure of the subsequent smelting furnace materials, wherein the mass percentage of the sintered ore with the alkalinity of 2.5 entering the furnace is 25%.

Compared with the comparative examples 1-4, the conventional sintering process is adopted to prepare the sintered ore, so that the alkalinity and MgO content of the sintered ore are improved, the strength and the yield of the sintered ore can be improved, and the low-temperature reduction degradation performance of the sintered ore is improved. Because the alkalinity and the MgO content are uniformly distributed in the sinter, the low-temperature reduction degradation value RDI of the sinter is reduced to a value of powder only when the alkalinity of the sinter is increased to 2.4-2.6 and the MgO content is increased to 2.0-2.4 percent_+6.3And RDI_+3.15Can meet the subsequent smelting Requirement (RDI)_+6.3≥50％，RDI_+3.15Not less than 70 percent) and the balance between the slag alkalinity and the MgO content can be maintained only when the mass percentage of the sintering ore entering the furnace is controlled within 25 to 30 percent. Therefore, the purposes of improving the charging quality ratio of the sintered ore and reducing the production cost of molten iron cannot be achieved by only improving the alkalinity and the MgO content of the sintered ore by adopting the conventional sintering process.

Example 1

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.6%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is separated, finely ground quicklime accounting for 2.5% of the iron ore concentrate obtained by separation, 4% of dolomite and 1.4% of solid fuel (coke powder) are added into the iron ore concentrate for proportioning and uniformly mixing to obtain a mixture 1, wherein the granularity of the iron ore concentrate is-0.074 mm and is more than 40%, and the content of iron elements is more than 62.5%. Pelletizing the mixture 1 on a discDirectly making into green ball with diameter of 8-20mm in machine, and adding CaO and SiO₂The ratio of the mass percent) is 1.0, the MgO content is 1.8 percent, and the mass ratio of the solid fuel is 1.4 percent.

Weighing and batching 70% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust and iron-containing pellets in a steel mill) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, dolomite and solid fuel according to the following mass fraction (60:5:28:3:10:3:7), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

And then carrying out secondary mixing granulation on the green pellets and the mixture 2 in a cylinder mixer to obtain granulated materials, and finally carrying out material distribution, ignition, sintering, cooling, crushing and screening on the granulated materials on a sintering machine to obtain finished sintered ore (the particle size is 5-40mm) and return ore (the particle size is less than 5 mm).

The height of the sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 70.05%, the drum strength was 66.29%, and the utilization factor was 1.53 t.m^-2·h^-1The solid fuel consumption is 34.56 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.369.36% RDI_+3.15The content was 75.64%.

Compared with comparative examples 3-4, when the alkalinity of the sintered ore is reduced from 2.4-2.6 to 1.8 and the MgO content is reduced from 2.0-2.4% to 1.6%, the sintered ore has high strength and low-temperature reduction degradation RDI_+6.3Greater than 50%, RDI_+3.15Greater than 70%; is far superior to each performance index of comparative examples 1-2. And the charging proportion can be improved from 25-30% to 50%.

Example 2

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.6%. 50% of iron ore concentrate in the total amount of the iron ore concentrate is branched out, and finely ground quicklime accounting for 3% of the iron ore concentrate obtained by branching, 3.5% of dolomite and 1.2% of solid fuel (anthracite powder) are added into the iron ore concentrate for blending and uniformly mixing to obtain a mixture 1, wherein the granularity of the iron ore concentrate is more than 40% when the granularity is-0.074 mm, and the content of iron elements is more than 62.5%. The mixture is directly prepared into 8mm-20 on a disc pelletizer, the alkalinity of green pellets is 1.2, the MgO content is 1.7 percent, and the mass ratio of solid fuel is 1.2 percent.

Weighing and batching 50% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust and iron-containing pellets in a steel mill) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, dolomite and solid fuel according to the following mass fractions (50:5:30:3:15:5:6), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

And then uniformly mixing the green pellets with the mixture 2, mixing and granulating in a cylindrical mixer according to the traditional sintering process to obtain granulated materials, and then distributing, igniting, sintering, cooling, crushing and screening the granulated materials on a sintering machine to obtain finished sintered ore (the particle size is 5-40mm) and return ore (the particle size is less than 5 mm).

Sintering under the conditions of the height of a sintering material layer of 700mm, the ignition temperature of 1100, the ignition time of 1.5min, the height of the sintering material layer of 700mm, the sintering negative pressure of 12kPa, the cooling negative pressure of 5kPa and the cooling time of 5min, wherein the yield of the obtained sintered ore is 70.26 percent, the drum strength is 60.60 percent, and the utilization coefficient is 1.60 t.m^-2·h^-1The solid fuel consumption is 35.06kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.356.67% RDI_+3.15The content was 75.69%.

Compared with the embodiment 1, as the proportion of the shunt iron ore concentrate is increased from 30 percent to 50 percent, the proportion of green pellets in the granulating material is increased, the grain size of the granules is increased, the air permeability of a sinter bed is improved, the yield of the sinter is improved, the utilization coefficient is increased, the strength of the sinter is reduced, but the RDI (powder metallurgy index) with low-temperature reduction degradation performance is reduced_+6.3And RDI_+3.15The required value can still be achieved, and the prepared sintering ore can still be used as a subsequent CCOREX iron-making process furnace charge.

Compared with comparative examples 3-4, when the alkalinity of the sintered ore is reduced from 2.4-2.6 to 1.8 and the MgO content is reduced from 2.0-2.4% to 1.6%, the sintered ore has high strength and low-temperature reduction degradation RDI_+6.3Greater than 50%, RDI_+3.15More than 70 percent, better than the comparative examples 3-4 and further better than the performance indexes of the comparative examples 1-2. And the charging proportion can be improved from 25-30% to 50%.

Example 3

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.6%. 60% of iron ore concentrate in the total amount of the iron ore concentrate is separated, finely ground quicklime accounting for 2% of the iron ore concentrate obtained by separation, 2.5% of magnesite and 1.4% of solid fuel (coke powder) are added into the iron ore concentrate, the materials are mixed and evenly mixed to obtain a mixture 1, wherein the granularity of the iron ore concentrate is-0.074 mm and is larger than 40%, and the content of iron elements is larger than 62.5%. The mixture is made into green pellets with the diameter of 8mm-20mm directly on a disc pelletizer, the alkalinity of the green pellets is 0.8, the MgO content is 1.0 percent, and the mass ratio of the solid fuel is 1.4 percent.

Weighing and batching 40% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust, iron-containing pellets and iron-containing lump ore undersize powder) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, serpentine and fuel according to the following mass fractions (50:5:28:3:19:5:4), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

Sintering under the conditions of the height of a sintering material layer of 700mm, the ignition temperature of 1100, the ignition time of 1.5min, the height of the sintering material layer of 700mm, the sintering negative pressure of 12kPa, the cooling negative pressure of 5kPa and the cooling time of 5min, wherein the yield of the obtained sintered ore is 68.79 percent, the drum strength is 57.89 percent, and the utilization coefficient is 1.45 t.m^-2·h^-1The solid fuel consumption is 38.56kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.347.67% RDI_+3.15The content was 68.34%.

Compared with the embodiment 1 and the embodiment 2, as the proportion of the shunt iron ore concentrate is improved from 30 percent and 50 percent to 60 percent, the green ball proportion in the granulating material is further increased, the grain size of the material grain is too large, the air permeability of the sinter bed is too good, the sintering speed is too fast, and the output and the strength of the sinter are reduced. And low temperature reduction degradation propertyRDI_+6.3And RDI_+3.15Obviously reduced and can not meet the requirement.

Compared with comparative examples 3-4, when the alkalinity of the sintered ore is reduced from 2.4-2.6 to 1.8 and the MgO content is reduced from 2.0-2.4% to 1.6%, the shunt ratio is as high as 60%, not only the strength and yield of the sintered ore are reduced, but also the RDI (reduced powder index) performance at low temperature is improved_+6.3And RDI_+3.15Although significantly higher than the comparative example, the charging requirement could not be satisfied. Therefore, when the iron concentrate diversion ratio reaches 60%, the obtained sinter cannot enter the furnace.

Example 4

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.6%. And (2) separating out 15% of the iron ore concentrate in the total amount of the iron ore concentrate, adding finely ground quicklime accounting for 2% of the iron ore concentrate obtained by separation, 2% of dolomite and 1.4% of solid fuel (coke powder) into the iron ore concentrate, blending and uniformly mixing to obtain a mixture 1, wherein the granularity of the iron ore concentrate is-0.074 mm and is more than 40%, and the content of iron elements is more than 62.5%. The mixture is made into green pellets with the diameter of 8mm-20mm directly on a disc pelletizer, the alkalinity of the green pellets is 0.6, the MgO content is 0.8 percent, and the mass ratio of the solid fuel is 1.4 percent.

Weighing and batching 85% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing pellets and iron-containing lump ore undersize) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, serpentine and fuel according to the following mass fractions (55:5:29:3:16:8:8), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

Sintering under the conditions of the height of a sintering material layer of 700mm, the ignition temperature of 1100, the ignition time of 1.5min, the height of the sintering material layer of 700mm, the sintering negative pressure of 12kPa, the cooling negative pressure of 5kPa and the cooling time of 5min, wherein the yield of the obtained sintered ore is 67.21 percent, the drum strength is 59.93 percent, and the utilization coefficient isIs 1.40 t.m^-2·h^-1The solid fuel consumption is 38.56kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.329.21% RDI_+3.15The content was 66.16%.

Compared with the examples 1-3, because the proportion of the shunt iron ore concentrate is reduced from 30-60% to 15%, the raw ball proportion in the granulating material is low, the grain size of the material grain is small, the air permeability of a sinter bed is not good, the sintering speed is obviously reduced, and the yield and the strength of the sinter are reduced. And low temperature reduction degradation performance RDI_+6.3And RDI_+3.15Also obviously decreases and can not meet the requirements.

Compared with comparative examples 3-4, when the alkalinity of the sintered ore is reduced from 2.4-2.6 to 1.8 and the MgO content is reduced from 2.0-2.4% to 1.6%, the strength and yield of the sintered ore are obviously reduced and the RDI (reduced powder index) performance at low temperature is reduced due to low shunt ratio_+6.3And RDI_+3.15Slightly higher than the comparative example, but can not meet the furnace charging requirement. Therefore, when the iron concentrate diversion ratio is as low as 15%, the obtained sinter cannot be charged into the furnace.

In summary, the practical examples 1-4 show that the proper flow ratio of the iron ore concentrate should be controlled at 30-50%.

Example 5

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.8%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is branched out, fine ground quicklime accounting for 2.5% of the iron ore concentrate obtained by branching, 2.7% of limestone and 0.6% of solid fuel (anthracite powder) are added into the iron ore concentrate, the materials are mixed and evenly mixed to obtain a mixture 1, wherein the granularity of the iron ore concentrate is more than 40% when the granularity is-0.074 mm, and the content of iron elements is more than 62.5%. The mixture 1 is made into green pellets with the diameter of 8mm-20mm directly in a disc pelletizer, the alkalinity of the green pellets is 1.0, the MgO content is 1.3 percent, and the mass ratio of the solid fuel is 0.6 percent.

Weighing and batching 70% of iron ore concentrate and iron-containing miscellaneous materials (iron-containing pellets) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, dolomite and solid fuel according to the following mass fractions (60:5:29:3:14:7:6), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

And then carrying out secondary mixing granulation on the green pellets and the mixture 2 in a cylinder mixer to obtain granulated materials, and finally carrying out material distribution, ignition, sintering, cooling, crushing and screening on the granulated materials on a sintering machine to obtain finished sintered ore (the particle size is less than 5-40mm) and return ore (the particle size is 5 mm).

The height of the sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 69.70%, the drum strength was 57.52%, and the utilization factor was 1.62 t.m^-2·h^-1The solid fuel consumption is 36.16 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.341.20% RDI_+3.15The content was 71.32%.

Compared with example 1, the green pellet made of the mixture 1 formed by 30% of the iron ore concentrate in the total amount of the iron ore concentrate flowing out has the solid fuel ratio reduced from 1.4% to 0.6% and the MgO content reduced from 1.8% to 1.3%, which results in insufficient heat in the pellet part of the sintered ore, and thus the sintered ore yield and strength are reduced. The solid fuel proportion in the green pellets is reduced, the content of ferrous oxide is reduced, and the low-temperature reduction degradation performance of the green pellets is poor. RDI finally reflected in the strength and low-temperature reduction degradation performance of sintered mineral products_+6.3And RDI_+3.15Also obviously decreases and can not meet the requirements.

Example 6

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.8%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is branched out, finely ground quicklime accounting for 2.5% of the iron ore concentrate obtained by branching, serpentine accounting for 3.0% of the iron ore concentrate and solid fuel (anthracite powder) accounting for 1.0% of the iron ore concentrate are added into the iron ore concentrate, the materials are mixed and evenly mixed, and a mixture 1 is obtained, wherein the granularity of the iron ore concentrate is more than 40% when the granularity is 0.074mm, and the content of iron elements is more than 62.5%. The mixture 1 is made into green pellets with the diameter of 8mm-20mm directly in a disc pelletizer, the alkalinity of the green pellets is 1.0, the MgO content is 1.5 percent, and the mass ratio of the solid fuel is 1.0 percent.

Weighing and batching 70% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust and iron-containing lump ore undersize powder in a steel mill) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, magnesite and solid fuel according to the following mass fraction (60:5:29:3:13:7:7), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

The height of the sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 70.25%, the drum strength was 60.68%, and the utilization factor was 1.59 t.m^-2·h^-1The solid fuel consumption is 37.16 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.350.20% RDI_+3.15The content was 73.32%.

Compared with example 1, the green pellet made of the mixture 1 formed by 30% of the iron ore concentrate in the total amount of the iron ore concentrate flowing out has the solid fuel ratio reduced from 1.4% to 1.0% and the MgO content reduced from 1.8% to 1.5%, which results in insufficient heat in the pellet part of the sintered ore, and thus the sintered ore yield and strength are reduced. The solid fuel proportion in the green pellets is reduced, the content of ferrous oxide is reduced, and the low-temperature reduction degradation performance of the green pellets is poor. RDI finally reflected in the strength and low-temperature reduction degradation performance of sintered mineral products_+6.3And RDI_+3.15All decrease, but can also meet the requirements.

Compared with the example 5, the solid fuel proportion in the green ball is improved from 0.6 percent to 1.0 percent, the MgO content is improved from 1.3 percent to 1.5 percent, the heat required by green ball sintering is increased, and simultaneously, the ferrous oxide content of the green ball is favorably improved, so the strength of sintered mineral products and the low-temperature reduction degradation performance RDI_+6.3And RDI_+3.15Are all improved.

Example 7

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 1.8%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is separated, finely ground quicklime accounting for 2% of the iron ore concentrate obtained by separation, dolomite accounting for 3% of the iron ore concentrate and solid fuel (coke powder) accounting for 1% of the iron ore concentrate are added into the iron ore concentrate, the materials are mixed and evenly mixed, and a mixture 1 is obtained, wherein the granularity of the iron ore concentrate is-0.074 mm and is larger than 40%, and the content of iron elements is larger than 62.5%. The mixture 1 is made into green pellets with the diameter of 8mm-20mm directly in a disc pelletizer, the alkalinity of the green pellets is 0.8, the MgO content is 1.5 percent, and the mass ratio of the solid fuel is 1.0 percent.

Weighing and batching 70% of iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust, iron-containing pellets and iron-containing lump ore undersize) in the total amount of the iron ore concentrate, return ores, quick lime, limestone, dolomite and solid fuel according to the following mass fraction (60:5:27:3:16:7:6), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

The height of the sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 69.29%, the drum strength was 58.68%, and the utilization factor was 1.45 t.m^-2·h^-1The solid fuel consumption is 38.19kg t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.346.23% RDI_+3.15The content was 68.33%.

Compared with example 1, when the green ball alkalinity is reduced from 1.0 to 0.8 and the MgO content is reduced from 1.8% to 1.5%, the strength of the sintered ore is reduced and the low-temperature reduction degradation performance RDI is reduced when other conditions are unchanged_+6.3And RDI_+3.15Cannot meet the requirements.

It can be seen from the comprehensive examples 1 and 4-7 that the suitable solid fuel proportion in the green pellets is 1.0-1.4%, the alkalinity is 1.0-1.2, the MgO content is 1.2-1.8%, and the sintered ore strength and low-temperature reduction degradation performance index obtained by shunt pelletizing and sintering can meet the requirements of subsequent smelting.

Example 8

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 2.1%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is branched out, finely ground quicklime accounting for 3% of the iron ore concentrate obtained by branching, 2.8% of dolomite and 1% of solid fuel (anthracite powder) are added into the iron ore concentrate, the materials are mixed and mixed uniformly, and a mixture 1 is obtained, wherein the granularity of the iron ore concentrate is-0.074 mm and is more than 40%, and the content of iron elements is more than 62.5%. The mixture 1 is made into green pellets with the diameter of 8mm-20mm directly in a disc pelletizer, the alkalinity of the green pellets is 1.2, the MgO content is 1.5 percent, and the mass ratio of the solid fuel is 1.0 percent.

Weighing and batching iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust, iron-containing pellets and iron-containing lump ore undersize) accounting for 70 percent of all iron-containing raw materials, return ores, quick lime, limestone, serpentine and fuel according to the following mass fractions (57:5:30:3:14:9:6), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

And then uniformly mixing the green pellets with the mixture 2, carrying out mixing granulation in a cylindrical mixer according to the traditional sintering process to obtain granulated materials, and then carrying out material distribution, ignition, sintering, cooling, crushing and screening on the granulated materials on a sintering machine to obtain finished sintered ore (the particle size is 5-40mm) and return ore (the particle size is less than 5 mm). Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 70.06%, the drum strength was 58.60%, and the utilization factor was 1.72 t.m^-2·h^-1The solid fuel consumption is 37.40 kg.t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.367.62% RDI_+3.15The content was 85.45%.

Compared with the embodiment 1 and the embodiment 2, when the total MgO content of the sintered ore is increased from 1.6 percent to 2.1 percent, the strength of the sintered ore is reduced more, but the index of the low-temperature reduction degradation performance is improved to a degree far superior to the related index requirement, and the requirement of entering the furnace can be met.

Example 9

According to the requirement of subsequent smelting on the mass percent of the sintering ore entering the furnace being 50%, the alkalinity of the sintering ore is designed to be 1.8, and the MgO content is designed to be 2.1%. 30% of iron ore concentrate in the total amount of the iron ore concentrate is branched out, and 3% of finely ground quicklime, 3.5% of dolomite and 1.5% of solid fuel (anthracite powder) accounting for 3% of the iron ore concentrate obtained by branching are added into the iron ore concentrate for proportioning and uniformly mixing to obtain a mixture 1, wherein the granularity of the iron ore concentrate is more than 40% when the granularity is-0.074 mm, and the content of iron elements is more than 62.5%. The mixture 1 is made into green pellets with the diameter of 8mm-20mm directly in a disc pelletizer, the alkalinity of the green pellets is 1.2, the MgO content is 1.7 percent, and the mass ratio of the solid fuel is 1.5 percent.

Weighing and batching iron ore concentrate and iron-containing miscellaneous materials (including iron-containing dust, iron-containing pellets and iron-containing lump ore undersize) accounting for 70 percent of all iron-containing raw materials, return ores, quick lime, limestone, dolomite and fuel according to the following mass fraction (60:5:26:3:14:10:6), and carrying out primary mixing treatment according to a traditional sintering process to obtain a mixture 2.

And then uniformly mixing the green pellets with the mixture 2, carrying out mixing granulation in a cylindrical mixer according to the traditional sintering process to obtain granulated materials, and then carrying out material distribution, ignition, sintering, cooling, crushing and screening on the granulated materials on a sintering machine to obtain finished sintered ore (the particle size is 5-40mm) and return ore (the particle size is less than 5 mm).

Sintering is carried out under the conditions that the height of a sintering material layer is 700mm, the ignition temperature is 1100, the ignition time is 1.5min, the sintering negative pressure is 12kPa, the cooling negative pressure is 5kPa, and the cooling time is 5 min. The yield of the obtained sintered ore was 70.10%, the drum strength was 59.20%, and the utilization factor was 1.70 t.m^-2·h^-1The solid fuel consumption is 38.85 kg-t^-1RDI (powder metallurgy) with low-temperature reduction degradation performance of COREX shaft furnace_+6.369.62% RDI_+3.15The content was 87.45%.

When the total MgO content of the sintered ore is increased from 1.6% to 2.1%, the MgO content in the green pellets is increased correspondingly, and the fuel ratio in the green pellets must be increased, thereby increasing the sintering temperature of the pellets and improving the strength and the low-temperature reduction degradation performance thereof, compared with example 8 and example 1.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A preparation method of high-quality sinter for a COREX smelting reduction iron-making process is characterized by comprising the following steps:

1) preparation of green pellets

the flux 1 comprises quicklime and one or more of limestone, dolomite, magnesite or serpentine;

the alkalinity of the green pellets is 0.8-1.2; the mass fraction of MgO in the green pellets is 1.2-1.8%;

2) preparation of the mix

3) production of sinter

2. The preparation method according to claim 1, wherein the iron concentrate contains iron element more than 62.5%; the mass content of the fraction smaller than 0.074mm in the granularity of the iron ore concentrate is larger than 40 percent.

3. The method of claim 1, wherein the solid fuel comprises coke breeze or anthracite fines.

4. The method as claimed in claim 1, wherein the diameter of the green pellets in step 1) is 8-20 mm.

5. A sinter for use in a COREX smelting reduction ironmaking process, wherein the sinter is produced by the method of any one of claims 1 to 4, and the sinter has a particle size of 5 to 40 mm; the alkalinity of the sintered ore is 1.6-2.0; the MgO content in the sintered ore is 1.6-2.1%, and the requirement of the COREX shaft furnace on the low-temperature reduction powdering performance of the sintered ore can be met when the charging mass ratio of the sintered ore is higher than 50%.