Method for preparing pellets from high-silicon and high-magnesium iron ore
By optimizing the mixing and roasting process of high-silicon and high mafic ore with other iron concentrates, the problems of low compressive strength and high reduction expansion rate of pellet ore are solved, and the quality and cost of pellet ore are improved are achieved.
Patent Information
- Application Number
- CN202510473227.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-08-01
AI Technical Summary
In the prior art, pellet ores prepared from high silicon and high mafic ore have low compressive strength and high reduction and expansion rate, resulting in a gap between the economic and technical indicators of blast furnaces and the industry level, and the pellet production cost remains high.
High-silicon, high-maf ore is mixed with other iron concentrates and bentonite in a certain proportion, and pellets are made and roasted after crushing and fine grinding, and the thermal engineering system is optimized to prepare high-quality pellet ore.
Significantly improve the compressive strength of pellet ore, reduce the reduction and expansion rate, reduce the production cost of pellet ore, and improve the economic benefits of blast furnaces.
Smart Images
Figure CN120400512A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the production of pellet ore in iron and steel metallurgy, and particularly relates to a method for preparing pellet ore by using high-silicon and high-magnesium iron ore. Background Art
[0002] Pellet ore is the most important iron-bearing burden for blast furnaces. At present, the structure of the iron charge charged into the blast furnace is generally high-alkali sinter mixed with acidic pellet ore. The proportion of pellet ore in the burden is generally 10 - 30%, and the proportion of pellet ore used in some domestic blast furnaces is more than 30%. The reduction swelling of pellet ore is one of the key indicators affecting the economic and technical indicators of blast furnaces. Due to the low SiO2 content, high contents of harmful elements such as K, Na, S, and F in the self-produced iron concentrate of an enterprise, the pellet ore prepared with the self-produced concentrate has low compressive strength and high reduction swelling rate. There is a large gap between the economic and technical indicators of the blast furnace and the industry level. How to improve the compressive strength of pellet ore and reduce the reduction swelling rate of pellet ore is a technical problem that needs to be tackled and solved.
[0003] Currently, affected by the decline in steel prices, most iron and steel enterprises use economic ore types in large quantities during the preparation of sinter to reduce the ironmaking cost, which reduces the raw material cost of the blast furnace. However, the cost of the iron concentrate used in pellet production has been remaining high. Using a certain proportion of low-cost economic ore types in pellet production to reduce the raw material cost of pellet ore is an objective requirement for reducing the raw material cost of the blast furnace.
[0004] The present patent provides a method for preparing pellet ore by using low-cost iron ore powder with high silicon and high magnesium. Since the TFe content of this ore is low, the silicon and magnesium contents are high, and the price is relatively low, it has a relatively high cost performance compared with ordinary concentrate for pellets. Through laboratory research and verification, adding an appropriate proportion of this ore to the concentrate prepared in pellet production can improve the compressive strength of pellet ore and reduce the reduction swelling rate of pellet ore. The present invention provides a technical solution for reducing the cost of pellet ore and improving the quality of pellet ore by reasonably adding high-silicon and high-magnesium concentrate. Summary of the Invention
[0005] The purpose of the present invention is to provide a method for preparing pellet ore by using high-silicon and high-magnesium iron ore, which can effectively reduce the production cost of pellet ore under the condition that the quality indexes of pellet ore meet the requirements of blast furnace smelting.
[0006] To solve the above technical problems, the present invention adopts the following technical solutions:
[0007] A method for preparing pellet ore by using high-silicon and high-magnesium iron ore of the present invention is proportioned with raw materials according to the following mass percentages: 5% - 6% of high-silicon and high-magnesium iron concentrate, 45% - 50% of iron concentrate A, 10% - 20% of iron concentrate B, 30% - 40% of iron concentrate C, and 2% - 4% of bentonite; the raw materials are fully mixed by a vertical mixer for pellet ore.
[0008] Furthermore, the iron ore is crushed and finely ground to prepare iron concentrate powder with a particle size passing through a 200-mesh sieve greater than 80%.
[0009] Furthermore, for the high-silica and high-magnesium iron ore: TFe > 52%, and the main components by mass percentage include: SiO2: 9 - 12%, MgO: 9 - 12%, CaO: 0.5% - 0.7%, F: < 0.5%, Al2O3: 1.2% - 1.3%, Ig: 0.8% - 1.8%. The particle size is 5 - 20 mm.
[0010] Furthermore, for the iron concentrate A: TFe: 64.5% - 66.5%, and the main components by mass percentage include: FeO: 27.5% - 31.0%, CaO: 0.75% - 2.35%, SiO2: 1.05% - 3.5%, MgO: 0.65% - 1.25%, Na2O: 0.05% - 0.15%, F: 0.08% - 0.3%, S: 0.65% - 0.95%, K2O: 0.05% - 0.15%, Ig: 1.0% - 2.2%. The particle size has a passing rate of 90% - 95% through a 200-mesh sieve.
[0011] Furthermore, for the iron concentrate B: TFe: 63% - 64%, and the main components by mass percentage include: FeO: 24% - 26%, CaO: 0.10% - 0.80%, SiO2: 4.0% - 4.5%, MgO: 0.25% - 0.3%, P: 0.05 - 0.15%, S: 0.50% - 0.60%, Ig: 4.5% - 6.0%. The particle size has a passing rate of 80% - 85% through a 200-mesh sieve.
[0012] Furthermore, for the iron concentrate C: TFe: 64.0% - 65.0%, and the main components by mass percentage include: FeO: 25.0 - 26.0%, CaO: 0.5 - 0.6%, SiO2: 4.0% - 4.6%, MgO: 0.7% - 0.8%, S: 0.30% - 0.40%, Ig: 1.5% - 2.5%. The particle size has a passing rate of 75% - 82% through a 200-mesh sieve.
[0013] Furthermore, for the bentonite: the montmorillonite content is higher than 65%, and the main components by mass percentage include: SiO2: 60% - 70%, Al2O3: 10.0% - 20.0%, MgO: 2.0% - 3.0%. The particle size has a passing rate of 90% - 95% through a 200-mesh sieve.
[0014] Furthermore, the mixture is conveyed to a disc pelletizer for pelletizing. The rotational speed of the disc pelletizer is 20 - 28 r / min, the inclination angle is 45 - 50°, the pelletizing time is 5 - 8 minutes. During the pelletizing process, water is added to the mixture in the way of "forming pellets with dripping water and growing with mist water", controlling the green pellet size range to be 8 - 16 mm, the moisture content of the small pellets to be 7.5% - 9%, the drop strength to be 5 - 6 times per pellet, and the compressive strength to be 10 - 12 N per batch;
[0015] The qualified green pellets prepared above are evenly distributed on the grate-kiln via a feeding device, and preheated pellet ore is obtained through the processes of air drying, suction drying and preheating on the grate-kiln. The conditions for the drying and preheating are as follows: the thickness of the material layer is 190 - 210 mm, the drying temperature is 200 - 500 °C, the time is 8 minutes, the temperature of the first preheating stage is controlled at 500 - 800 °C, the time is 5 minutes, and the temperature of the second preheating stage is controlled at 900 - 1000 °C, the time is 6 minutes.
[0016] The above-mentioned preheated pellet ore enters the rotary kiln for roasting, where the roasting temperature is 1150 - 1250 °C and the roasting time is controlled to be 30 min.
[0017] The roasted pellet ore is discharged into a ring cooler for air cooling. The thickness of the material layer in the ring cooler is 800 mm, and the temperature of the pellet ore after cooling is required to be lower than 150 °C.
[0018] The qualified pellet ore meets the following quality requirements: the TFe content of the pellet ore > 62.0%, the FeO content < 2%, R < 0.25 times, the compressive strength > 2300 N per batch; at the same time, the SiO2 content of the pellet ore prepared by this technical solution is 4.8 - 5.2%, the MgO content is 1.5 - 1.8%, and the reduction expansion rate of the pellet ore < 15%.
[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:
[0020] The present invention conducts crushing and grinding treatment on a high-silicon and high-magnesium iron ore, and prepares a fine grinding concentrate with a passing rate of more than 80% through - 200 mesh. By adopting an optimized ore blending technology and mixing with other iron concentrates in a certain ratio, the chemical components of the mixture meet the constraint conditions. At the same time, the thermal regime of the chain-grate-kiln system is adjusted to prepare high-quality pellet ore. This technical solution significantly reduces the pellet raw material cost, improves the quality of the pellet ore, and especially can significantly reduce the reduction expansion rate of the pellet ore.
[0021] Producing pellet ore from concentrate prepared with a certain proportion of high-silica and high-magnesium iron ore powder can significantly reduce the raw material cost of pellet ore. Taking a pellet production line with an annual output of 5 million tons as an example, when 5% of high-silica and high-magnesium concentrate is added to the iron material, 250,000 tons / year of ordinary concentrate can be replaced. The price of this ore type is 205 yuan / ton lower than that of the iron concentrate used in standard pellets, and the annual raw material cost of pellets can be reduced by 51.25 million yuan / year. Laboratory research shows that when using the previous technical solution to produce pellet ore, its compressive strength increases by 200 N / batch, and the reduction expansion rate decreases by 4.5%. The improvement of pellet ore quality is beneficial to reducing the fuel ratio of blast furnaces and the carbon emissions per ton of iron, and also has considerable economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be further described below in conjunction with the drawings.
[0023] Figure 1 It is a process flow chart for the method of producing pellet ore from high-silica and high-magnesium iron ore by the present invention. SPECIFIC EMBODIMENTS
[0024] In this embodiment, aiming at the problems of low cold strength and high reduction expansion rate of pellet ore prepared by a certain steel enterprise using self-produced concentrate, optimization and control measures are proposed, that is, the SiO2 content of the finished pellets is controlled at 4.5 - 5.5%, and the MgO content is controlled at 1.3 - 2.0%.
[0025] Furthermore, a technical solution of adding high-silica and high-magnesium iron ore and controlling the finished pellet ore is proposed. The chemical composition of the iron concentrate used is detected and analyzed, and the specific analysis results are shown in the following table:
[0026] Table 1 Chemical composition of raw materials for pellets (wt%)
[0027]
[0028]
[0029] Table 2 Raw material ratio of the embodiment (wt%)
[0030]
[0031] Weigh the materials in the pre-batching room according to the raw materials shown in Table 1 and the ratio shown in Table 2, and add bentonite at 2.5% to the mixture in the batching room.
[0032] After the mixture is thoroughly mixed by a vertical mixer, it is transported to a disc pelletizer for pelletizing. The rotational speed of the disc pelletizer is 20 - 28 r / min, the inclination angle is 45 - 50°, the pelletizing time is 5 - 8 minutes. During the pelletizing process, water is added to the mixture in the way of "forming pellets with dripping water and growing with mist water", controlling the green pellet size range to be 8 - 16 mm, the moisture content of the small pellets to be 7.5% - 9%, the drop strength to be 5 - 6 times per pellet, and the compressive strength to be 10 - 12 N per batch.
[0033] The qualified green pellets are evenly spread on the grate-kiln via a screening and distribution process, with the layer thickness being 180 - 190 mm, and drying and preheating treatments are carried out on the grate-kiln. The drying temperature is 200 - 500 °C, the time is 8 minutes, the temperature of the first preheating stage is controlled at 500 - 800 °C, the time is 5 minutes, and the temperature of the second preheating stage is controlled at 900 - 1000 °C, the time is 6 minutes.
[0034] The preheated pellet ore enters the rotary kiln and is roasted at 1150 - 1250 °C for 25 - 30 minutes.
[0035] The pellet ore in the rotary kiln is discharged into the annular cooler and cooled by blowing air in 4 stages. The temperature of the pellet ore is reduced to below 150 °C, and thus the production of pellet ore is completed. The specific process flow is as shown in the appendix Figure 1 as follows.
[0036] Performance comparison of the green pellets and finished pellets prepared in the reference example and the examples.
[0037] Table 3 Comparison table of green pellet performance
[0038]
[0039]
[0040] Table 4 Comparison table of chemical compositions of finished pellet ore, (mass fraction %)
[0041] Test number TFe CaO <![CDATA[SiO2]]> MgO F R Basic example 63.35 1.11 4.50 .0.72 0.07 0.246 Example 62.80 1.13 4.96 1.34 0.08 0.228
[0042] Table 5 Comparison table of performance of finished pellet ore
[0043] Test number Compressive strength, N / P Reduction expansion rate, % Basic example 2661 14.1 Example 2931 9.2
[0044] Analysis of green pellet performance: Compared with the reference example, the green pellet performance in the examples basically remains stable. As shown in Table 3.
[0045] Analysis of performance of finished pellet ore:
[0046] Compared with the composition of the pellet ore in the reference example, the TFe of the pellet ore in the examples decreases, the contents of SiO2 and MgO increase significantly, and the F content increases slightly. The chemical composition reaches the expected control target, as shown in Table 4.
[0047] Compared with the pellet composition of the reference example, the compressive strength of the pellet in the example increased from 2661 N / batch of the reference pellet to 2931 N / batch, an increase of 270 N / batch. The reduction swelling rate of the pellet in the example decreased significantly, decreasing by 4.9% compared with the reference example. As shown in Table 5.
[0048] In summary, adding 5% of high-silicon and high-magnesium iron concentrate can significantly improve the quality of pellets, solve the technical problem of high swelling rate of pellets in this enterprise, and at the same time greatly reduce the raw material cost of pellet production.
[0049] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.
Claims
1. A method for preparing pellet ore from high-silicon and high-magnesium iron ore, characterized in that: The raw materials are prepared according to the following mass percentages: 5%-6% of high-silicon and high-magnesium iron concentrate, 45%-50% of iron concentrate A, 10%-20% of iron concentrate B, 30%-40% of iron concentrate C, and 2%-4% of bentonite; the raw materials are fully mixed in a vertical mixer for pelletizing.
2. The method for preparing pellet ore by using high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The iron ore is crushed and finely ground to prepare iron ore concentrate powder with a particle size of 200 mesh and a passing rate of >80%.
3. The method for preparing pellet ore by using high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The high-silicon and high-magnesium iron ore has a TFe content greater than 52%, and its main components by mass percentage include: SiO2: 9-12%, MgO: 9-12%, CaO: 0.5%-0.7%, F: <0.5%, Al2O3: 1.2%-1.3%, Ig: 0.8%-1.8%. The particle size is 5-20 mm.
4. The method for preparing pellet ore from high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The iron concentrate A comprises 64.5% to 66.5% of TFe, and its main components include, by mass percentage, 27.5% to 31.0% of FeO, 0.75% to 2.35% of CaO, 1.05% to 3.5% of SiO2, 0.65% to 1.25% of MgO, 0.05% to 0.15% of Na2O, 0.08% to 0.3% of F, 0.65% to 0.95% of S, 0.05% to 0.15% of K2O, and 1.0% to 2.2% of Ig. The particle size is such that the passing rate through a 200-mesh sieve is 90% to 95%.
5. The method for preparing pellet ore by using high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The iron concentrate B contains TFe of 63% to 64%, and its main components, in terms of mass percentage, include FeO of 24% to 26%, CaO of 0.10% to 0.80%, SiO2 of 4.0% to 4.5%, MgO of 0.25% to 0.3%, P of 0.05% to 0.15%, S of 0.50% to 0.60%, and Ig of 4.5% to 6.0%. The particle size has a pass rate of 80% to 85% through a 200-mesh sieve.
6. The method for preparing pellet ore by using high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The iron concentrate C:TFe: 64.0% to 65.0%, the main components include, by mass percentage, FeO: 25.0% to 26.0%, CaO: 0.5% to 0.6%, SiO2: 4.0% to 4.6%, MgO: 0.7% to 0.8%, S: 0.30% to 0.40%, Ig: 1.5% to 2.5%, and the particle size has a 200-mesh sieve pass rate of 75% to 82%.
7. The method for preparing pellet ore from high-silicon and high-magnesium iron ore according to claim 1, characterized in that: The bentonite has a montmorillonite content higher than 65%, and its main components include, by mass percentage, SiO2: 60% to 70%, Al2O3: 10.0% to 20.0%, and MgO: 2.0% to 3.0%, with a particle size of 90% to 95% passing rate through a 200-mesh sieve.
8. The method for preparing pellet ore by using high-silicon and high-magnesium iron ore according to claim 1, wherein: The mixture is conveyed to the disc pelletizer for pelletizing. The disc pelletizer has a speed of 20-28 r / min, an inclination angle of 45-50°, and a pelletizing time of 5-8 minutes. During the pelletizing process, water is added to the mixture by the method of "dripping water to form balls and mist water to grow them". The particle size range of the raw balls is controlled to be 8-16 mm, the moisture content of the balls is 7.5%-9%, the drop strength is 5-6 times / piece, and the compressive strength is 10-12N / batch; The qualified green pellets prepared above are evenly distributed on the grate-kiln via a feeding device, and preheated pellet ore is obtained through the processes of air drying, suction drying, and preheating on the grate-kiln; the conditions for drying and preheating are as follows: the thickness of the material layer is 190 - 210 mm, the drying temperature is 200 - 500 °C, the time is 8 minutes, the temperature of the first preheating stage is controlled at 500 - 800 °C, the time is 5 minutes, and the temperature of the second preheating stage is controlled at 900 - 1000 °C, the time is 6 minutes; The above-mentioned preheated pellet ore enters the rotary kiln for roasting, where the roasting temperature is 1150 - 1250 °C, and the roasting time is controlled at 30 min; The roasted pellet ore is discharged into the circular cooler for air cooling; the thickness of the circular cooler material layer is 800 mm, and the temperature of the pellet ore after cooling is required to be lower than 150 °C; The qualified pellet ore meets the following quality requirements: the TFe content of the pellet ore > 62.0%, the FeO content < 2%, R < 0.25 times, the compressive strength > 2300 N / batch; at the same time, the SiO2 content of the pellet ore prepared by this technical solution is 4.8 - 5.2%, the MgO content is 1.5 - 1.8%, and the reduction expansion rate of the pellet ore < 15%.