A method for batching limestone-dolomite interbedded ore in sintering production

Abstract

This invention relates to the field of iron and steel smelting technology, specifically to a method for batching limestone-dolomite interbedded ore in sintering production. The method first tests each sintering raw material, including the limestone-dolomite interbedded ore, and calculates a preliminary batching ratio based on the test results. Then, the raw materials are batched according to the calculated preliminary ratio and sintered. Next, the produced sinter is tested and compared with the preliminary batching calculation results. Based on the comparison results, the preliminary batching ratio is adjusted, and the sintering and testing are repeated until the sinter testing results are substantially consistent with the batching calculation results. This invention solves the problem of comprehensive utilization of limestone-dolomite interbedded ore, completely replacing high-quality limestone and dolomite ore. It achieves efficient and comprehensive utilization of limestone-dolomite interbedded ore resources while reducing production costs for enterprises, offering advantages such as simplicity, high efficiency, and good results.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, and specifically to a batching method for using limestone-dolomite interbedded ore in sintering production. Background Technology

[0002] The Wulongquan Mine of Wuhan Iron and Steel (WISCO) serves as WISCO's production base for sintering and steelmaking flux raw materials. It primarily provides limestone, dolomite, and quicklime for sintering, and active lime and lightly calcined dolomite for steelmaking. The limestone and dolomite raw ore used by WISCO are all sourced from the Wulongquan Mine's own mine. According to known geological data, the Wulongquan Mine deposit is a gently dipping ore body with interbedded dolomite and limestone, numerous faults, and many interbedded rocks. This complex geological condition results in a large amount of interbedded ore. Interbedded ore can be further divided into limestone-dominated interbedded ore (MgO content <6%) and dolomite-dominated interbedded ore (MgO content between 6% and 16%). Due to the unstable composition of interbedded ore, precise batching during sintering is impossible, affecting the stability of the magnesium oxide content and binary basicity of the sintered ore. Therefore, it is generally not used in sintering batching. Although the MgO content of large quantities of limestone-dolomite interbedded ore is less than 16%, the MgO and CaO content of its useful minerals are consistently around 52.5%. For a long time, large quantities of this interbedded ore have been exported as building materials or stockpiled as waste rock in dumps. Currently, the use of dolomite as a flux in the sintering process is very common in major steel plants both domestically and internationally; however, most of this is high-quality dolomite with a high magnesium content. There are no reports of using limestone-dolomite interbedded ore as a sintering flux in batching.

[0003] To promote comprehensive resource utilization, Wuhan Iron and Steel (WISCO) began research in 2014 on using limestone-dolomite interbedded ore as a sintering flux. Initially, WISCO's Wulongquan Mine, Wuhan University of Science and Technology, and WISCO's ironmaking plant studied how to stabilize the composition of the limestone-dolomite interbedded ore. Through a series of measures, they achieved the goal of stabilizing the composition of the limestone-dolomite interbedded ore and developed a patented achievement, "A Method for Blending Limestone-Dolomite Interbedded Ore" (CN105117581A). Based on this, during the mining and production of limestone-dolomite interbedded ore, by adopting corresponding technical measures, and under the premise of relatively stable total MgO and CaO content in the limestone-dolomite interbedded ore, the proportions of different ore components were adjusted to ensure relatively stable MgO and CaO content without significant fluctuations, thus ensuring relatively stable binary basicity of the sinter. By 2022, WISCO's total consumption of limestone-dolomite interbedded ore for sintering production exceeded 5 million tons, and an effective sintering batching method was summarized. Summary of the Invention

[0004] The main objective of this invention is to solve the problem of comprehensive utilization of interbedded mineral resources, and to provide a method for batching limestone-dolomite interbedded minerals in sintering production. The method includes the following steps: first, testing the sintering raw materials such as limestone-dolomite interbedded minerals, and calculating the proportion of sintering raw materials based on the test results; then, batching and sintering according to the calculated proportion; next, testing the produced sinter and comparing it with the proportion calculation results; adjusting the proportion based on the comparison results and re-sintering and testing until the sinter test results are basically consistent with the adjusted proportion calculation results.

[0005] Furthermore, the sintering raw materials also include blending powder, quicklime, sintering return ore, and sintering fuel.

[0006] Furthermore, the limestone-dolomite interbedded minerals, quicklime, and sintering fuel in the sintering raw materials must all be crushed into powder with a particle size not exceeding 3mm.

[0007] Furthermore, the total MgO and CaO content in the limestone-dolomite interbedded ore is consistently maintained at 52.5% ± 0.5%. The mechanism of limestone-dolomite interbedded ore is essentially that of a mixture of limestone and dolomite, with uneven proportions during mineralization. However, to meet the needs of sintering production, we have strict requirements for its effective components MgO and CaO, requiring the mass percentage of MgO to be consistently maintained at 15% ± 1%. Based on the theoretical CaO mass percentage content of limestone ore (56%), the MgO plus CaO mass percentage content in dolomite ore is 52.3%. After deducting approximately 2% of impurities such as SiO2, theoretical calculations and years of practical testing have verified that the effective component MgO plus CaO mass percentage content is approximately 52.5%.

[0008] Furthermore, the testing items for sintering raw materials include moisture content, chemical composition, and burn-off.

[0009] Furthermore, the calculation principle for the sintering raw material ratio is as follows: based on the need for return ore balance, the initial ratio of sintering return ore is set to no more than 60%, preferably 30%; based on the requirements for ferrous oxide in sintered ore, the initial ratio of sintering fuel is set to 2.5%-5%, preferably 3.8%; the remainder is the ratio of limestone-dolomite interbedded ore, mixed powder, and quicklime.

[0010] Furthermore, the proportions of limestone-dolomite interbedded ore, blended powder, and quicklime are adjusted according to the requirement that the sintered ore contains 1.5% magnesium oxide by mass and has an alkalinity of 1.8 times.

[0011] Furthermore, when there is a difference between the sinter test results and the proportion calculation results, the proportion calculation results are corrected accordingly using an adjustment coefficient. Through repeated calculations, tests, and corrections, an appropriate component correction coefficient is determined to ensure that the proportion calculation results and test results are basically consistent.

[0012] Furthermore, when there is a discrepancy between the sinter test results and the proportion calculation results, the proportions of sinter return ore and sinter fuel can be adjusted according to actual production needs, and the composition of other fluxes (such as quicklime) can be adjusted simultaneously.

[0013] Furthermore, when the quicklime ratio needs to be adjusted, the composition of the limestone-dolomite interbedded ore can be adjusted while maintaining the basicity and magnesium oxide content of the sintered ore, thereby optimizing the quicklime ratio. The method for adjusting the composition of the limestone-dolomite interbedded ore is as follows: adjust the mixing ratio of limestone-dolomite interbedded ore with different component contents (the total content of MgO+CaO is kept stable at around 52.5%).

[0014] This invention solves the problem of comprehensive utilization of limestone-dolomite interbedded ore, achieving both efficient and comprehensive utilization of these resources and reducing production costs for enterprises. Given the current generally poor profitability in the steel industry, the rational utilization of limestone-dolomite interbedded ore has significant promotional value. As of 2022, Wuhan Iron and Steel Group (WISCO) used over 5 million tons of limestone-dolomite interbedded ore for sintering production, achieving substantial economic and social benefits. The method provided by this invention essentially achieves the goal of completely replacing high-quality limestone and dolomite ore with limestone-dolomite interbedded ore. It can better and faster determine the optimal ratio of sintering raw materials while ensuring the quality of sintered ore. It has a series of advantages such as simplicity, high efficiency, and good results, which is conducive to improving the overall competitiveness and economic benefits of steel enterprises. Detailed Implementation

[0015] To enable those skilled in the art to fully understand the technical solution and beneficial effects of the present invention, the following detailed description is provided in conjunction with specific embodiments.

[0016] Currently, sintering production generally produces high-basicity sinter (binary basicity CaO / Si2O2 greater than 1.5 times), and the fluxes typically used are quicklime, limestone, and dolomite. The technical problem this invention aims to solve is to completely replace limestone and dolomite with interbedded limestone-dolomite ore in the sintering batch, thereby comprehensively utilizing the interbedded limestone-dolomite ore while meeting sinter quality requirements and reducing production costs.

[0017] It should be noted that the percentage content of each raw material in this invention is by mass.

[0018] A batching method for using interlayered limestone and dolomite ore in sintering production, the specific process of which is as follows:

[0019] 1) Crush the limestone-dolomite interbedded minerals, quicklime, and sintered fuel required for batching into powder with a particle size not exceeding 3mm.

[0020] 2) Sampling and testing were conducted on the moisture content, chemical composition, and burn loss of the limestone-dolomite interbedded mineral powder, blending powder, quicklime powder, sintering return ore, and sintering fuel required for batching. The test results are shown in the table below:

[0021] Table 1. Test Results of Various Sintering Raw Materials (%)

[0022] Product Name <![CDATA[H2O]]> TFe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> Zn MgO CaO burn damage Limestone and dolomite interbedded minerals 1.55 / 0.74 / / 17.26 35.28 45.84 Mixed powder 7.92 60.62 4.91 1.66 0.013 0.12 0.59 6.25 quicklime / / 1.79 / / 1.10 86.64 7.61 Sintered Return Ore / 56.23 6.56 5.09 0.015 1.63 9.85 1.50 Sintered fuel 8.17 / 6.56 5.09 / / / 88.00

[0023] 3) Based on the need for return ore balance, the initial ratio of sintering return ore is set at 30%.

[0024] 4) Based on the requirements for ferrous oxide in sintered ore, the initial proportion of sintering fuel is set at 3.8%.

[0025] 5) Adjust the proportions of the blending powder, limestone-dolomite interbedded mineral powder, and quicklime powder according to the requirements of 1.5% MgO mass percentage and 1.8 times basicity of the sintered ore, to meet the various index requirements of the sintered ore. The specific calculation process of the proportions is shown in Table 2:

[0026] Table 2. Calculation process for proportions (%)

[0027]

[0028] 6) Sinter the raw materials according to the proportions calculated in the table above, then take samples of the produced sinter for analysis and testing. Compare the test results with the proportion calculation results to analyze the reasons for the differences between the two sets of results. If there are no special reasons, the proportion calculation results should be corrected accordingly using adjustment coefficients. After multiple calculations, tests, and corrections, a suitable component correction coefficient should be determined to ensure that the calculated proportion results and the test results are basically consistent. For example, if the calculated alkalinity is 1.78 times, while the actual alkalinity is 1.82 times when no abnormalities are found in the test results, then consider multiplying the calculated result of 1.78 times by the correction coefficient 1.02247 (1.82 / 1.78, i.e., test result / calculated result) to ensure the consistency between the theoretical calculation and the actual test results. The correction coefficient should be calculated through comparison of a large amount of data.

[0029] 7) Adjust the ratio of sintering return ore and sintering fuel according to actual production needs, and adjust the composition of other fluxes simultaneously.

[0030] 8) If the quicklime ratio needs to be adjusted, the composition of the limestone-dolomite interbedded ore must be adjusted while still meeting the requirements for sintered ore basicity and magnesium oxide. Analysis of years of actual testing results shows that the total MgO+CaO content in the limestone-dolomite interbedded ore is consistently around 52.5%. Adjusting one indicator will cause a corresponding change in the other, thus optimizing the quicklime ratio. The final ratio calculation results after repeated adjustments and optimizations are shown in Table 3 below, and the adjusted ratio calculation process is shown in Table 4.

[0031] Table 3. Raw material composition after adjusting limestone and dolomite composition (%)

[0032] Product Name <![CDATA[H2O]]> TFe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> Zn MgO CaO burn damage Limestone and dolomite interbedded mineral 1.55 0.35 0.74 0.2 / 10.90 41.54 45.84 Mixed powder 7.92 60.62 4.91 1.66 0.013 0.12 0.59 6.25 quicklime 0 0.50 1.79 0.30 / 1.10 86.64 7.61 Sintered Return Ore 0 56.23 6.56 5.09 0.015 1.63 9.85 1.50 Sintered fuel 8.17 0.20 6.56 5.09 / 0.20 0.30 88.00

[0033] Table 4. Adjusted proportion calculation process (%)

[0034] project Proportion Dry weight Residual amount TFe CaO MgO <![CDATA[SiO2]]> Alkalinity / Ro Limestone and dolomite interbedded mineral 6.40 6.30 3.75 0.02 2.62 0.69 0.05 / Mixed powder 56.50 52.03 48.77 31.54 0.31 0.06 2.55 / quicklime 3.30 3.30 3.05 0.02 2.86 0.04 0.06 / Sintered Return Ore 30.00 30.00 29.55 16.87 2.96 0.49 1.97 / Sintered fuel 3.80 3.49 0.42 0.01 0.01 0.01 0.23 / total 100.00 95.12 85.54 48.45 8.76 1.28 4.86 / Main components of sintered ore / / / 56.64 10.24 1.50 5.68 1.80

[0035] Since 2014, the method of this invention has been used in the old No. 2 sintering machine, the old No. 3 sintering machine, and the new No. 2 sintering machine of Wuhan Iron and Steel Plant. It has achieved good results and achieved the goal of completely replacing high-quality limestone and dolomite with limestone-dolomite intermetallic minerals. It has significantly reduced production costs and realized the efficient utilization of limestone-dolomite intermetallic mineral resources.

Claims

1. A batching method for using limestone-dolomite interbedded ore in sintering production, characterized in that... The method includes the following steps: First, the sintering raw materials are tested, and the proportion of the sintering raw materials is calculated based on the test results. The sintering raw materials include limestone-dolomite interbedded ore, blending powder, quicklime, sintering return ore, and sintering fuel. The total content of MgO and CaO in the limestone-dolomite interbedded ore is stable at 52.5wt%±0.5wt%. The principle for calculating the proportion of sintering raw materials is as follows: based on the need for return ore balance, the initial proportion of sintering return ore is set not to exceed 60wt%. Based on the requirements for ferrous oxide in the sintered ore, the initial proportion of sintering fuel is set to 2.5wt%-5wt%. The remainder is the proportion of limestone-dolomite interbedded ore, blending powder, and quicklime. Then, the raw materials are batched and sintered according to the calculated proportion. Next, the produced sintered ore is tested and compared with the proportion calculation results. Based on the comparison results, the proportion is adjusted and sintering and testing are repeated until the sintered ore test results are basically consistent with the adjusted proportion calculation results.

2. The method as described in claim 1, characterized in that: The limestone-dolomite interbedded minerals, quicklime, and sintering fuel in the sintering raw materials must all be crushed into powder with a particle size not exceeding 3mm.

3. The method as described in claim 1, characterized in that: The testing items for sintering raw materials include moisture content, chemical composition, and burn-off.

4. The method as described in claim 1, characterized in that: The proportions of limestone-dolomite interbedded ore, mixed powder, and quicklime are adjusted according to the requirements of 1.5 wt% magnesium oxide and 1.8 times the basicity of sintered ore.

5. The method as described in claim 1, characterized in that: When there is a discrepancy between the sinter test results and the proportion calculation results, the proportion calculation results are corrected using an adjustment coefficient. Through repeated calculations, tests, and corrections, an appropriate component correction coefficient is determined to ensure that the proportion calculation results and test results are basically consistent.

6. The method as described in claim 1, characterized in that: When there is a discrepancy between the sinter test results and the proportion calculation results, the proportions of sinter return ore and sinter fuel can be adjusted according to actual production needs, and the composition of other fluxes can be adjusted simultaneously.

7. The method as described in claim 6, characterized in that: When the proportion of quicklime needs to be adjusted, the composition of the limestone-dolomite interbedded mineral can be adjusted by changing the mixing ratio of different components of the limestone-dolomite interbedded mineral while maintaining the basicity and magnesium oxide content of the sintered ore. This optimizes the quicklime proportion.

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