Sintering method of limonite with high aluminum and high crystal water

Abstract

The invention discloses a sintering method of limonite with high aluminum and high crystal water, and belongs to the technical field of sintering. According to the method, high-aluminum and high-crystal-water limonite is preheated through high-temperature flue gas at the tail of a sintering machine, the limonite is fully decomposed under the action of the sintering flue gas, then different batches of limonite are mixed according to the granularity level difference of iron ore, fine-granularity limonite, steel slag and magnetite form a mixture A, coarse-granularity limonite, flux and fuel form a mixture B, and the mixture A is mixed with the mixture B; and pelletizing by taking the ball core B as a pelletizing core and the mixture A as adhesive powder to prepare a sintered material mixture C, and distributing the mixture C on a sintering trolley for sintering and mineralizing. According to the method, the efficient utilization efficiency of the steel slag and the high-aluminum and high-crystal-water limonite is remarkably improved, and the problems that in the large-proportion sintering process of the high-aluminum and high-crystal-water limonite, the sintering speed is high, liquid phase generation in the sintering process is insufficient, the sintered ore finished product strength is poor, the yield is low, and burnup is high are solved; the purposes of reducing the overall sintering cost and recycling solid waste are achieved.

Description

Technical Field

[0001] This invention belongs to the field of sintering technology, and specifically relates to a sintering method for high-alumina, high-crystallization-water limonite. Background Technology

[0002] Iron ore sintering is the first step in steel production, and the refined raw materials it provides are the foundation for achieving high-quality, high-yield, and low-consumption steel production. Limonite is one of the iron ore types used in sintering. Compared with magnetite and hematite, its physical characteristics include a loose structure, low bulk density, high porosity, and rough surface. Its theoretical water of crystallization content is as high as 5.33% to 25.23%, resulting in high loss on ignition. It also has a low assimilation temperature, strong assimilation properties, good liquid phase fluidity, low binder phase strength, and a high capacity for producing calcium ferrite. Generally, iron ores with a water of crystallization content greater than 8% are classified as high-water-of-crystallization iron ores.

[0003] Currently, the main varieties include BHP Yangdi, RioTino Ha Yangdi, FMG mixed powder, and FMG super-special powder, with burn-off generally exceeding 8%. When high-water limonite is sintered in a large proportion, the excessive permeability of the bed leads to a rapid sintering speed, insufficient liquid phase generation during sintering, poor binder phase strength, poor strength of the sintered ore, low yield, and high fuel consumption. Therefore, although limonite has a relatively low cost, a high proportion can worsen sintering indicators and hinder stable sintering production. Baosteel has increased the proportion of high-water limonite in its sintering production from 23% to 40%, and Xingcheng Special Steel has increased the proportion from 25% to 35%.

[0004] Chinese invention patent 202111198165.0 discloses a sintering method for high-proportion limonite, comprising the following steps: S1. Mixing limonite, iron concentrate, Brazilian iron powder, and other iron-containing materials to form a homogenized ore, wherein the mass percentages of each component in the homogenized ore are as follows: limonite 40-65wt%, iron concentrate 5-15wt%, Brazilian iron powder 15-20wt%, with the remainder being other iron-containing materials; S2. Sintering the homogenized ore obtained in step S1 with flux and fuel through mixing, granulation, distribution, and ignition. Iron concentrate can stabilize the permeability of the material layer and also increase the amount of adhering powder during sintering, increasing the amount of binder phase and improving the strength of the binder phase; Brazilian iron powder can increase the skeleton material in the sintered material to increase the physical strength of the sintered product. Using this method can increase the proportion of limonite used, suppress the deterioration of the sintered ore quality due to the increased proportion of limonite, and increase sintering yield; at the same time, since the price of limonite is low, adding a large proportion can reduce the cost of sintering raw materials. Currently, both domestically and internationally, the main approach is to directly incorporate limonite into the sintering material. In production, technical measures such as increasing the material layer height, increasing basicity, increasing the fuel ratio and increasing the fuel particle size, and optimizing the ore blending and rationally controlling the limonite ratio are used to enhance the sintering process. Although these measures have achieved some results, they still cannot completely eliminate the adverse effects of limonite crystal water on sintering, and they also have drawbacks such as high fuel consumption and limited limonite ratio. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a sintering method for high-alumina, high-crystal-water limonite. This invention utilizes the high-temperature flue gas from the tail of the sintering machine to preheat the high-alumina, high-crystal-water limonite, allowing the limonite to fully decompose under the action of the sintering flue gas. Different batches are mixed according to the differences in iron ore particle size. Fine-grained limonite, steel slag, and magnetite form mixture A, while coarse-grained limonite, flux, and fuel form mixture B. Using pellet core B as the granulation core and mixture A as the adhering powder for pelletizing, sintering mixture C is produced. Mixture C is then distributed onto a sintering trolley for sintering. This method improves the high-efficiency utilization of steel slag and high-alumina, high-crystal-water limonite, and addresses problems such as rapid sintering speed, insufficient liquid phase generation during sintering, poor strength of the sintered ore, low yield, and high fuel consumption in the large-scale sintering process of high-alumina, high-crystal-water limonite. This achieves the goal of reducing the overall sintering cost and recycling solid waste.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a sintering method for high-alumina, high-crystallization-water limonite, comprising the following steps: (1) Preheating treatment of limonite: A "rotary kiln" type limonite preheating treatment device is installed at the tail of the sintering machine. High-alumina, high-crystallization-water limonite enters from one end of the "rotary kiln" and flows out from the other end of the "rotary kiln". The high-temperature sintering flue gas from the last 2 to 4 wind boxes at the tail of the sintering machine is introduced into the rotary kiln, where it moves countercurrently with the high-alumina, high-crystallization-water limonite and exchanges heat with it. The temperature range of the sintering flue gas is 200 to 500°C, and the continuous heat exchange time is 20 to 60 minutes. (2) Iron ore pre-screening: The preheated limonite is screened, and the limonite powder with a particle size <1mm is used to prepare mixture A. The iron ore with a particle size ≥1mm is subjected to drum collision and further screening. The limonite powder with a particle size <1mm is used to prepare mixture A, and the limonite with a particle size ≤1mm and ≤10mm is used to prepare mixture B. (3) Preparation of sintering mixture: Mixture A is composed of limonite powder with a particle size <1mm, steel slag and magnetite. The mass fraction of limonite powder with a particle size <1mm is 70~80%, the mass fraction of steel slag is 9~17%, and the mass fraction of magnetite is 4~12%. The basicity of mixture A is controlled at 1.5~1.9. Water is added to mixture A and mixed evenly. Mixture B is composed of limonite with a particle size ≤10mm, fuel and flux. The mass fraction of limonite with a particle size ≤10mm is 85~95%, the mass fraction of fuel is 3~6%, and the mass fraction of flux is 4~10%. The basicity of mixture B is controlled at 2.0~2.4. Mixture B with water and granulate to obtain sphere B. Using sphere B as the granulation core and mixture A as the adhesive powder to form spheres, sintering mixture C is prepared. The mass ratio of mixture B to mixture A is 1~4. (4) Sintering: The sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 30~50mm, and the thickness of the sintering material layer is 950~1100mm. Sintering is carried out by ignition and ventilation.

[0007] Based on the above technical solution, further, the mass fraction of crystal water in the high-alumina, high-crystallization-water limonite mentioned in step (1) is 7~11%, and the mass fraction of Al2O3 is 3~5%.

[0008] Based on the above technical solution, further, the length of the "rotary kiln" mentioned in step (1) is 20~30m, the tilt angle range is 1~5°, and the processing capacity is 30~50t / h.

[0009] Based on the above technical solution, further, in step (2), a vibrating screen is used for screening, and the time range of the drum collision is 10~30min.

[0010] Based on the above technical solution, further, the chemical elements and weight percentages of the steel slag mentioned in step (3) are as follows: CaO content is 35~39%, TFe content is 15~19%, CaO / SiO2 is 2.1~2.9, P2O5 content is 1.3~2.0%, and MgO content is 8~10%.

[0011] Based on the above technical solution, further, in step (3), the amount of water added to mixture A is 6.0~7.0% of the total mass of mixture A.

[0012] Based on the above technical solution, further, in step (3), the amount of water added to mixture B is 7.0~9.0% of the total mass of mixture B.

[0013] Based on the above technical solution, further, the fuel mentioned in step (3) is one or more of coke powder, anthracite, and carbon-containing biomass.

[0014] Based on the above technical solution, further, the flux mentioned in step (3) is one or more of quicklime, limestone, magnesite, and dolomite.

[0015] Based on the above technical solution, further, the diameter of the spherical core B mentioned in step (3) is 2~12mm.

[0016] Based on the above technical solution, further, the TFe content in the mixture C mentioned in step (3) is 55~60%, CaO / SiO2=1.8~2.3, (CaO+MgO) / (SiO2+Al2O3)=1.7~2.2, and the P2O5 content is 0.01~0.20%.

[0017] Based on the above technical solution, further, in step (4), the ignition temperature range is 850~1050℃, the ignition time range is 1.0~3.0min, and the ignition negative pressure range is 3.0~5.0kPa; the sintering machine speed range is 1.50~1.80m / min, the sintering exhaust negative pressure is 17~20kPa, and the exhaust flow rate is 50~65m³ / min. 3 / min, the air leakage rate of the sintering machine system is less than 40%.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention utilizes the waste heat of high-temperature flue gas from the last few air boxes at the tail of the sintering machine to preheat high-alumina, high-crystallization-water limonite, making full use of the waste heat of the high-temperature flue gas, improving the degree of solid waste recycling, and enhancing the high-efficiency utilization of high-alumina, high-crystallization-water limonite and steel slag, thereby achieving the beneficial effects of reducing the total production cost of sintering and recycling solid waste. (2) The present invention uses a combination of rotary drum screening and batch mixing based on particle size differences to produce a sintering mixture by using a mixture containing coarse-grained limonite as the granulation core and a mixture containing fine-grained limonite as the adhesive powder for pelletizing. This significantly improves the problems of fast sintering speed, insufficient liquid phase generation during sintering, poor strength of sintered ore, low yield, and high fuel consumption. Detailed Implementation

[0019] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0020] Example 1 This embodiment provides a sintering method for high-alumina, high-crystallization-water limonite, comprising the following steps: (1) The effective sintering area of ​​the sintering machine is 600m² 2 A 20m long rotary kiln-type iron ore preheating device is installed at the tail of the sintering machine, with an inclination angle of 1.5° and a flow rate of 30t / h. High-alumina, high-crystal-water limonite enters the kiln from one end and exits from the other. High-temperature sintering flue gas from the two last two air boxes at the tail of the sintering machine is introduced into the rotary kiln by an induced draft fan, where it flows counter-currently with the limonite and exchanges heat with it. The temperature range of the sintering flue gas is 491.3℃, and the continuous heat exchange time is 30min. The high-alumina, high-crystal-water limonite has a crystal water mass fraction of 7.82% and an Al2O3 content of 3.24%.

[0021] (2) The preheated iron ore is pre-screened using a vibrating screen. Iron ore powder with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the drum machine for drum collision. The drum collision time is 10 min. After drum collision, the iron ore is pre-screened. Similarly, iron ore with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the batching room to prepare mixture B.

[0022] (3) The mass fraction of limonite with an average diameter of less than 1 mm is 71%, the mass fraction of steel slag (CaO content is 36.67%, TFe content is 16.8%, CaO / SiO2 content is 2.8, P2O5 content is 1.68%, MgO content is 8.7%) is 17%, and the mass fraction of magnetite is 12%, so that the basicity of mixture A is 1.8. Mix mixture A with water, wherein the amount of water added is 6.5% of the total mass of mixture A. The mixture B contains 90% limonite with an average diameter of 1mm and 10mm, 5% coke powder, and 5% quicklime, resulting in an alkalinity of 2.1. Water is added to the mixture B, with the water amount being 8.5% of the total mass of the mixture B. Granulation yields 5mm diameter spherical cores B. Using spherical cores B as the granulation core and mixture A as the binding powder, sintering mixture C is produced, with a mass ratio of mixture B to mixture A of 1.5. The mixture C contains 57.25% TFe, CaO / SiO2 = 1.95, (CaO+MgO) / (SiO2+Al2O3) = 1.76, and P2O5 content of 0.1%.

[0023] (4) The above-mentioned sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 50 mm, the thickness of the sintering material layer is 1100 mm, the ignition temperature is 850℃, the ignition time is 2.5 min, the ignition negative pressure is 3.0 kPa, the sintering machine speed is 1.55 m / min, the sintering exhaust negative pressure is 20 kPa, and the exhaust flow rate is 65 m³ / min. 3 The air leakage rate of the sintering machine system was 37.8% at a rate of 0.000 m / min, resulting in high-quality sinter.

[0024] Example 2 This embodiment provides a sintering method for high-alumina, high-crystallization-water limonite, comprising the following steps: (1) The effective sintering area of ​​the sintering machine is 405m². 2 A 30m long rotary kiln-type iron ore preheating device is installed at the tail of the sintering machine, with an inclination angle of 4.8° and a flow rate of 48t / h. High-alumina, high-crystal-water limonite enters the kiln from one end and exits from the other. High-temperature sintering flue gas from the last three air boxes at the tail of the sintering machine is introduced into the rotary kiln by an induced draft fan, where it flows counter-currently with the limonite and exchanges heat with it. The temperature range of the sintering flue gas is 288.6℃, and the continuous heat exchange time is 55min. The high-alumina, high-crystal-water limonite has a crystal water mass fraction of 8.86% and an Al2O3 content of 4.04%.

[0025] (2) The preheated iron ore is pre-screened using a vibrating screen. Iron ore powder with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the drum machine for drum collision. The drum collision time range is 20 min. After drum collision, the iron ore is pre-screened. Similarly, iron ore with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the batching room to prepare mixture B.

[0026] (3) The mass fraction of limonite with an average diameter of less than 1 mm is 80%, the mass fraction of steel slag (CaO content is 37.86%, TFe content is 17.6%, CaO / SiO2 content is 2.76, P2O5 content is 1.57%, MgO content is 9.3%) is 12%, and the mass fraction of magnetite is 8%, so that the basicity of mixture A is 1.6. Mix mixture A with water, wherein the amount of water added is 6.8% of the total mass of mixture A. The mixture B comprises 88% limonite (1mm ≤ average diameter ≤ 10mm), 4% coke powder, 5% limestone, and 3% magnesite, resulting in an alkalinity of 2.3. Water is added to the mixture B, with the water amount being 8.5% of the total mass of the mixture B. Granulation yields spherical cores B with a diameter of 7mm. Using spherical cores B as the granulation core and mixture A as the binder powder for pelletizing, sintered mixture C is prepared, wherein the mass ratio of mixture B to mixture A is 1.1. The mixture C contains 57.01% TFe, CaO / SiO2 = 1.98, (CaO+MgO) / (SiO2+Al2O3) = 1.86, and P2O5 content of 0.08%.

[0027] (4) The above-mentioned sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 40 mm, the thickness of the sintering material layer is 1000 mm, the ignition temperature is 950℃, the ignition time is 2.0 min, the ignition negative pressure is 4.0 kPa, the sintering machine speed is 1.55 m / min, the sintering exhaust negative pressure is 18 kPa, and the exhaust flow rate is 55 m³ / min. 3 The air leakage rate of the sintering machine system was 38.6% at a rate of 0.000 m / min, resulting in high-quality sinter.

[0028] Example 3 This embodiment provides a sintering method for high-alumina, high-crystallization-water limonite, comprising the following steps: (1) The effective sintering area of ​​the sintering machine is 360m² 2A 25m long rotary kiln-type iron ore preheating device is installed at the tail of the sintering machine. The high-alumina, high-crystal-water limonite, with an inclination angle of 3° and a flow rate of 45t / h, enters the kiln from one end and exits from the other. High-temperature sintering flue gas from the two rearmost air boxes at the tail of the sintering machine is introduced into the rotary kiln by an induced draft fan, where it flows counter-currently with the limonite and exchanges heat with it. The sintering flue gas temperature ranges from 350.8℃, and the continuous heat exchange time is 45min. The high-alumina, high-crystal-water limonite has a crystal water mass fraction of 9.68% and an Al2O3 content of 4.36%.

[0029] (2) The preheated iron ore is pre-screened using a vibrating screen. Iron ore powder with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the drum machine for drum collision. The drum collision time range is 15 min. After drum collision, the iron ore is pre-screened. Similarly, iron ore with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the batching room to prepare mixture B.

[0030] (3) The mass fraction of limonite with an average diameter of less than 1 mm is 75%, the mass fraction of steel slag (CaO content is 38.53%, TFe content is 18.55%, CaO / SiO2 is 2.68, P2O5 content is 1.85%, MgO content is 8.67%) is 13%, and the mass fraction of magnetite is 12%, so that the basicity of mixture A is 1.7. Mix mixture A with water, wherein the amount of water added is 7.0% of the total mass of mixture A. The mixture B contains 89% limonite (1mm ≤ average diameter ≤ 10mm), 5% coke powder, and 6% dolomite, resulting in an alkalinity of 2.2. Water is added to the mixture B, with the water amount being 8.0% of the total mass of the mixture B. Granulation yields 9mm diameter spheres (B). Using spheres (B) as the granulation core and mixture A as the binder powder, sintered mixture C is prepared, with a mass ratio of mixture B to mixture A of 3. The mixture C contains 56.96% TFe, 1.96 CaO / SiO2, 1.88 (CaO+MgO) / (SiO2+Al2O3), and 0.09% P2O5.

[0031] (4) The above-mentioned sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 30 mm, the thickness of the sintering material layer is 950 mm, the ignition temperature is 1050℃, the ignition time is 1.8 min, the ignition negative pressure is 4.0 kPa, the sintering machine speed is 1.75 m / min, the sintering exhaust negative pressure is 17 kPa, and the exhaust flow rate is 50 m³ / min. 3 The air leakage rate of the sintering machine system was 36.8% at a rate of 0.000 m / min, resulting in high-quality sintered ore.

[0032] Example 4 This embodiment provides a sintering method for high-alumina, high-crystallization-water limonite, comprising the following steps: (1) The effective sintering area of ​​the sintering machine is 405m². 2 A 24m long rotary kiln-type iron ore preheating device is installed at the tail of the sintering machine, with an inclination angle of 2.0° and a flow rate of 36t / h. High-alumina, high-crystallization-water limonite enters the kiln from one end and exits from the other. High-temperature sintering flue gas from the last three air boxes at the tail of the sintering machine is introduced into the rotary kiln by an induced draft fan, where it flows counter-currently with the limonite and exchanges heat with it. The temperature range of the sintering flue gas is 300.68℃, and the continuous heat exchange time is 60min. The high-alumina, high-crystallization-water limonite has a crystal water mass fraction of 10.46% and an Al2O3 content of 4.73%.

[0033] (2) The preheated iron ore is pre-screened using a vibrating screen. Iron ore powder with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the drum machine for drum collision. The drum collision time range is 20 min. After drum collision, the iron ore is pre-screened. Similarly, iron ore with an average diameter of less than 1 mm is sent to the batching room to prepare mixture A. Iron ore with an average diameter of 1 mm ≤ 10 mm is sent to the batching room to prepare mixture B.

[0034] (3) The mass fraction of limonite with an average diameter of less than 1 mm is 80%, the mass fraction of steel slag (CaO content is 37.45%, TFe content is 17.83%, CaO / SiO2 is 2.25, P2O5 content is 1.45%, MgO content is 8.86%) is 9%, and the mass fraction of magnetite is 11%, so that the basicity of mixture A is 1.52. Mix mixture A with water, wherein the amount of water added is 6.6% of the total mass of mixture A. The mixture B contains 92% limonite with an average diameter of 1mm and 10mm, 4% coke powder, and 4% quicklime, resulting in an alkalinity of 2.0. Water is added to the mixture B, with the water amount being 8.5% of the total mass of the mixture B. Granulation yields 11mm diameter spheres (B). Using spheres B as the granulation core and mixture A as the binder powder, sintering mixture C is produced, with a mass ratio of mixture B to mixture A of 2.5. The mixture C contains 56.68% TFe, 2.15 CaO / SiO2, 1.95 (CaO+MgO) / (SiO2+Al2O3), and 0.05% P2O5.

[0035] (4) The above-mentioned sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 40 mm, the thickness of the sintering material layer is 1000 mm, the ignition temperature is 1000℃, the ignition time is 1.90 min, the ignition negative pressure is 3.5 kPa, the sintering machine speed is 1.58 m / min, the sintering exhaust negative pressure is 18 kPa, and the exhaust flow rate is 60 m³ / min. 3 The air leakage rate of the sintering machine system was 36.8% at a rate of 0.000 m / min, resulting in high-quality sintered ore.

[0036] Comparative Example 1 This comparative example provides a conventional sintering method for high-alumina, high-crystal-water limonite, comprising the following steps: sintering 70% by mass of high-alumina, high-crystal-water limonite (crystal water content 10.46%, Al2O3 content 4.73%) and 9% by mass of steel slag (CaO content 36.75%, TFe content 16.54%, CaO / SiO2 ratio 2.66). A mixture of magnetite (1.64% P2O5, 7.49% MgO), coke powder (4% coke powder), and flux dolomite (6% flux dolomite) with a mass fraction of 11% was mixed for 8 minutes in a primary and secondary mixer to form mixture D with an alkalinity of 2.0. Mixture D was then distributed onto a sintering trolley using a material distributor. The trolley had a base material thickness of 45 mm and a sintering material layer thickness of 850 mm. The ignition temperature was 1050℃, the ignition time was 2.00 min, the ignition negative pressure was 5.5 kPa, the sintering machine speed was 1.88 m / min, and the sintering exhaust negative pressure was 16 kPa, ultimately yielding the finished sintered ore.

[0037] Table 1. Sintering parameters of Examples 1-4 and Comparative Example 1

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sintering method for high-alumina, high-crystallization-water limonite, characterized in that, The following steps are involved: (1) Preheating treatment of limonite: A "rotary kiln" type limonite preheating treatment device is installed at the tail of the sintering machine. High-alumina, high-crystallization-water limonite enters from one end of the "rotary kiln" and flows out from the other end of the "rotary kiln". The high-temperature sintering flue gas from the last 2 to 4 wind boxes at the tail of the sintering machine is introduced into the rotary kiln, where it moves countercurrently with the high-alumina, high-crystallization-water limonite and exchanges heat with it. The temperature range of the sintering flue gas is 200 to 500°C, and the continuous heat exchange time is 20 to 60 minutes. (2) Iron ore pre-screening: The preheated limonite is screened, and the limonite powder with a particle size <1mm is used to prepare mixture A. The iron ore with a particle size ≥1mm is subjected to drum collision and further screening. The limonite powder with a particle size <1mm is used to prepare mixture A, and the limonite with a particle size ≤1mm and ≤10mm is used to prepare mixture B. (3) Preparation of sintering mixture: Mixture A is composed of limonite powder with a particle size <1mm, steel slag and magnetite. The mass fraction of limonite powder with a particle size <1mm is 70~80%, the mass fraction of steel slag is 9~17%, and the mass fraction of magnetite is 4~12%. The basicity of mixture A is controlled at 1.5~1.

9. Water is added to mixture A and mixed evenly. Mixture B is composed of limonite with a particle size ≤10mm, fuel and flux. The mass fraction of limonite with a particle size ≤10mm is 85~95%, the mass fraction of fuel is 3~6%, and the mass fraction of flux is 4~10%. The basicity of mixture B is controlled at 2.0~2.

4. Mixture B with water and granulate to obtain sphere B. Using sphere B as the granulation core and mixture A as the adhesive powder to form spheres, sintering mixture C is prepared. The mass ratio of mixture B to mixture A is 1~4. (4) Sintering: The sintering mixture C is spread onto the sintering trolley. The thickness of the base material on the sintering trolley is 30~50mm, and the thickness of the sintering material layer is 950~1100mm. Sintering is carried out by ignition and ventilation.

2. The sintering method according to claim 1, characterized in that, The high-alumina, high-crystallization-water limonite mentioned in step (1) has a crystal water mass fraction of 7~11% and an Al2O3 mass fraction of 3~5%; the "rotary kiln" has a length of 20~30m, an inclination angle range of 1~5°, and a processing capacity of 30~50t / h.

3. The sintering method according to claim 1, characterized in that, In step (2), a vibrating screen is used for screening, and the time range of the drum collision is 10~30min.

4. The sintering method according to claim 1, characterized in that, The chemical elements and weight percentages of the steel slag mentioned in step (3) are as follows: CaO content is 35~39%, TFe content is 15~19%, CaO / SiO2 is 2.1~2.9, P2O5 content is 1.3~2.0%, and MgO content is 8~10%.

5. The sintering method according to claim 1, characterized in that, In step (3), the amount of water added to mixture A is 6.0~7.0% of the total mass of mixture A; the amount of water added to mixture B is 7.0~9.0% of the total mass of mixture B.

6. The sintering method according to claim 1, characterized in that, The fuel mentioned in step (3) is one or a mixture of two or more of the following: coke powder, anthracite, and carbonaceous biomass.

7. The sintering method according to claim 1, characterized in that, The flux mentioned in step (3) is one or more of quicklime, limestone, magnesite, and dolomite.

8. The sintering method according to claim 1, characterized in that, The diameter of the spherical core B mentioned in step (3) is 2~12mm.

9. The sintering method according to claim 1, characterized in that, The mixture C mentioned in step (3) has a TFe content of 55~60%, CaO / SiO2 = 1.8~2.3, (CaO+MgO) / (SiO2+Al2O3) = 1.7~2.2, and a P2O5 content of 0.01~0.20%.

10. The sintering method according to claim 1, characterized in that, In step (4), the ignition temperature range is 850~1050℃, the ignition time range is 1.0~3.0min, and the ignition negative pressure range is 3.0~5.0kPa; the sintering machine speed range is 1.50~1.80m / min, the sintering exhaust negative pressure is 17~20kPa, and the exhaust flow rate is 50~65m³ / min. 3 / min, the air leakage rate of the sintering machine system is less than 40%.

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