Method for resource utilization of rolling oil sludge and coal blending combustion

Abstract

This invention discloses a method for the resource utilization and coal blending combustion of steel rolling sludge. The method involves mixing bituminous coal A with steel rolling sludge to prepare a mixture; feeding the mixture into a hot air dryer to prepare a mixed fuel; calculating the contribution of the steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel according to simplified rules; blending the mixed fuel, bituminous coal B, and bituminous coal C according to a coal blending model to prepare a blended coal; determining the R90 fineness of the blended coal obtained by pulverizing it in a coal mill based on the volatile matter content; using the obtained blended coal as fuel in a pulverized coal boiler for power generation; and determining the technical parameters of the pulverized coal boiler based on the volatile matter content. This invention couples steel rolling sludge with a coal-fired boiler, utilizing the synergistic utilization of oil and iron oxides in the steel rolling sludge. The oil rapidly releases combustible gases in the early stages of combustion, shortening the ignition delay time and improving combustion efficiency. The iron oxides act as a catalyst, promoting the oxidation of carbon particles. This achieves the harmless disposal and energy utilization of industrial solid waste without reducing boiler efficiency.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a method for the resource utilization of steel rolling sludge and its coal-fired combustion. Background Technology

[0002] Steel rolling sludge is a typical hazardous waste generated during the rolling process in the steel industry. It mainly consists of iron oxide scale, oil, and water. Steel companies need to spend a lot of money on disposal every year to achieve the harmless treatment of this hazardous waste.

[0003] While some research has been conducted on the resource utilization of steel rolling sludge, the efficiency remains low. Distillation methods require complex equipment such as deoiling towers and condensation systems, resulting in high energy consumption and limited oil recovery rates (only 50-70%) due to condensation efficiency. Furthermore, the high viscosity of the sludge increases pretreatment costs. Although the ore-blended sintering method can recover iron oxides (TFe ≥ 70%), incomplete combustion of oily substances during direct sintering can easily trigger SO2 emissions. x NO x Pollutant emissions exceed standards, and the proportion of oil sludge added must be strictly limited to avoid deterioration of sinter quality. Chemical extraction relies on solvents or surfactants, and although oil recovery rates can reach 75-99%, reagent residues can easily generate secondary hazardous waste, and treatment costs are high. Incineration can reduce emissions, but fluctuations in combustion conditions can easily generate toxic gases such as dioxins, and unburned particulate matter exacerbates fly ash pollution. Coal blending combustion technology has the potential to treat steel rolling sludge. However, existing technologies have not considered the potential of sludge as a fuel component. The oils (hydrocarbons) in sludge have high volatile content and can theoretically replace some coal. Traditional hot air drying processes have not been optimized for the combustion compatibility of the sludge-coal mixture, leading to unstable fuel calorific value. Furthermore, research on process compatibility is insufficient. The solid particle size distribution of sludge differs from the fineness required for pulverized coal combustion (R90≤22%), and direct mixing can lead to increased energy consumption or decreased combustion efficiency in the coal mill. In addition, the catalytic combustion value of metal oxides such as Fe2O3 in sludge has not been explored; traditional technologies treat it only as ash. Summary of the Invention

[0004] This invention addresses the problem of resource utilization of steel rolling mill sludge by providing a method for resource utilization of steel rolling mill sludge and coal blending combustion, thereby achieving harmless disposal and synergistic utilization of solid waste resources.

[0005] To achieve the above objectives, the present invention provides a method for the resource utilization of steel rolling sludge and its coal blending and combustion, as detailed below: 1) Raw material preparation: Mix 50-200 mesh bituminous coal A with steel rolling sludge at a mass ratio of 9-19:1 to prepare a mixture; 2) Drying: The mixture obtained in step 1) is fed into a hot air dryer to prepare a mixed fuel. The drying temperature is 100-150°C, the air velocity is 0.5-1m / s, and the drying time is 20-60min. The contribution of steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel is calculated according to simplified rules. 3) Coal blending: Mixed fuel, bituminous coal B, and bituminous coal C are mixed according to the coal blending model to prepare coal blending, and the volatile matter of the blended coal is calculated. The R90 fineness of the blended coal obtained by grinding in the coal mill is determined according to the volatile matter of the blended coal, and the coal mill process parameters are optimized to prepare coal blending with suitable R90 fineness. 4) Combustion utilization: The coal blend obtained in step 3) is used as fuel for power generation in a pulverized coal boiler, and the technical parameters of the pulverized coal boiler are determined based on the characteristics of volatile matter.

[0006] Furthermore, in step 1), the particle size of bituminous coal A is 50-200 mesh, and the weight characteristics of the composition of bituminous coal A are: volatile matter 10-20%, ash content 10-20%, carbon content 75-90%, and moisture content ≤1%. Steel rolling sludge comprises solid phase, oil, and water, by mass percentage: solid phase 60-70%, oil 5-15%, water 15-40%; the chemical composition of the solid phase by mass percentage includes: TFe 70.0-90%, C≤3.0%, MnO≤0.5%, CaO≤1.0%, MgO≤0.5%, SiO2≤2.0%, Al2O3≤0.2%, Cl≤0.2%, S≤0.1%, P≤0.1%, with the balance being O element combined with Fe and other unavoidable impurities; the particle size characteristics of the solid phase are: particles with a diameter of 0.3-2mm account for 50-80% of the total solid phase, and particles with a diameter less than 0.075mm account for ≤5% of the total solid phase.

[0007] Furthermore, in step 2), the moisture content of the mixed fuel is ≤1%; the simplified rules for calculating the volatile matter, ash content, and carbon content in the mixed fuel are as follows: all solid phase in the steel rolling sludge is included in the ash content, oil is included in the volatile matter at 85% of its mass, oil is included in the carbon content at 75% of its mass, and all carbon in the solid phase is included in the carbon content. The moisture content after drying is calculated as 0% (the moisture content of bituminous coal A does not affect the approximate calculation results and is not considered).

[0008] Further, in step 3), the weight composition of bituminous coal B is as follows: volatile matter 20-30%, ash content 15-25%, carbon content 70-80%, and moisture content ≤1%. The weight composition of bituminous coal C is as follows: volatile matter 40-45%, ash content 10-20%, carbon content 60-75%, and moisture content ≤1%. The feed rate of the coal mill is 2-4 t / h, the grinding pressure is 0.8-1.3 MPa, the ventilation volume is 25-35 m / s, the inlet temperature is 40-60°C, and the outlet temperature is 90-110°C.

[0009] Furthermore, in step 3), the coal blending model for the mixed fuel, bituminous coal B, and bituminous coal C requires that the comprehensive volatile matter V of the blended coal be... mix 28-37%, Overall Ash Content A mix ≤25%, Overall carbon content C mix ≥70%.

[0010] Furthermore, in step 3), if the volatile matter content of the blended coal is 28-<31%, the corresponding blending fineness R90 is ≤15%; if the volatile matter content of the blended coal is 31-<34%, the corresponding blending fineness R90 is 15-18%; if the volatile matter content of the blended coal is 34-37%, the corresponding blending fineness R90 is 18-22%.

[0011] Further, in step 4), the technical parameters of the pulverized coal boiler are as follows: if the volatile matter content of the blended coal is 28% to <31%, the furnace temperature is 1300-1400°C, the excess air coefficient is 1.15-1.20, and the secondary air volume ratio is 20-25%; if the volatile matter content of the blended coal is 31% to <34%, the furnace temperature is 1250-1350°C, the excess air coefficient is 1.10-1.15, and the secondary air volume ratio is 25-30%; if the volatile matter content of the blended coal is 34% to 37%, the furnace temperature is 1200-1300°C, the excess air coefficient is 1.05-1.10, and the secondary air volume ratio is 30-35%.

[0012] The technical principle of this invention is as follows: Steel rolling sludge contains a certain amount of oil in addition to ferrite, which has an agglomeration effect. In this invention, the steel rolling sludge is first mixed with fine pulverized coal to pre-homogenize the sludge, and then dried.

[0013] The oils in steel rolling sludge have high boiling points and are lost relatively little during drying; approximately 85% of their mass enters the mixed fuel as volatiles. These volatile oils rapidly release combustible gases (such as hydrocarbons) in the early stages of combustion, significantly improving the ignition performance of pulverized coal, shortening ignition delay time, and reducing the flame temperature gradient through premixed combustion, thus maintaining combustion stability.

[0014] Iron oxides (TFe ≥ 70%) in the solid phase of steel rolling sludge can act as a catalyst during combustion, improving combustion efficiency. The active sites on the surface of iron oxides (such as Fe2O3) promote the adsorption and reaction of carbon particles with oxygen, lowering the activation energy and shortening the combustion reaction path. Simultaneously, the iron oxides and ash form a porous structure, increasing oxygen diffusion channels, reducing the carbon content of fly ash, thereby improving carbon conversion and promoting the complete combustion of residual carbon.

[0015] This invention's coal blending model couples volatile matter and fineness control, dynamically adjusting mill process parameters based on the volatile matter content of the blended coal to ensure that pulverized coal fineness matches the combustion rate, within the low volatile matter range (V...mix =28-31%), requiring R90≤15%, necessitates extending the pulverized coal grinding time through high grinding pressure (1.1-1.3 MPa) and low ventilation (25-28 m / s) to generate ultrafine pulverized coal to compensate for insufficient volatile matter; in the medium-high volatile matter range (V mix With a pulverized coal content of ≥31%, the particle size distribution of pulverized coal can be relaxed (R90=15-22%). This improves pulverization efficiency by reducing grinding pressure (0.8-1.1MPa) and increasing ventilation (28-35m / s), while avoiding excessive pulverization that leads to increased energy consumption. In addition, a high iron content (TFe≥70%) lowers the ash melting point through catalytic action, which also helps reduce the risk of slagging in the furnace.

[0016] This invention achieves a balance between combustion efficiency and emissions by adjusting combustion parameters based on the volatile matter range. Low volatile fuels (V... mix At a concentration of 28-31%, carbon burnout is enhanced through high temperature (1300-1400°C) and a high excess air coefficient (1.15-1.20); high volatile fuels (V28-31%) mix At a concentration of 34-37%, nitrogen oxide formation can be suppressed by lowering the temperature (1200-1300°C) and reducing excess air (1.05-1.10).

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention couples steel rolling sludge with a coal-fired boiler, utilizing the synergistic use of oil and iron oxides in the steel rolling sludge. The oil rapidly releases combustible gas in the early stage of combustion, shortening the ignition delay time and improving combustion efficiency. The iron oxides act as a catalyst to promote the oxidation of carbon particles. Without reducing boiler efficiency, the harmless disposal and energy utilization of industrial solid waste are achieved.

[0018] 2) This invention realizes the resource utilization of steel rolling sludge, which not only saves the cost of solid waste landfill disposal, but also reduces the unit coal consumption for power generation and lowers energy costs by optimizing combustion temperature and air coefficient.

[0019] 3) The process of this invention is simple, requires little additional equipment for coal-fired power plants, and is simple and convenient, making it suitable for the preparation and application of fuel for industrial boilers or kilns.

[0020] 4) The method of the present invention achieves a dual improvement in resource efficiency and environmental benefits by integrating multi-objective synergy and process depth adaptation, namely by integrating oil combustion aid, iron oxide catalysis and particle size synergistic optimization. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] Example 1 The basic material data involved in this embodiment are as follows: Bituminous coal A: Volatile matter 12.4%, ash content 11.1%, carbon content 86.9%, moisture content 0.4%; Bituminous coal B: Volatile matter 22.2%, ash content 23.7%, carbon content 77.6%, moisture content 0.5%; Bituminous coal C: volatile matter 41.8%, ash 18.6%, carbon content 72.3%, moisture content 0.8%; Steel rolling sludge: solid phase 58%, oil 6%, water 34%. The chemical composition of the solid phase by mass percentage is: TFe 71.2%, C 0.8%, MnO 0.2%, CaO 0.4%, MgO 0.4%, SiO2 1.8%, Al2O3 0.1%, Cl 0.1%, S 0.04%, P 0.08%. Implementation process as follows Figure 1 As shown: 1) Raw material preparation: Mix 9 parts by weight of bituminous coal A (50-200 mesh) with 9 parts by weight of steel rolling sludge to prepare a mixture.

[0024] 2) Drying: The mixture obtained in step 1) is fed into a hot air dryer (drying temperature 110°C, air velocity 0.6 m / s, drying time 25 min) to prepare a mixed fuel. The approximate contribution of steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel is as follows: Raw material ratio: bituminous coal A (9 parts) + steel rolling sludge (1 part), total mass 10 parts.

[0025] Mass of oil sludge after drying: The moisture content of the steel rolling oil sludge before drying is 34%, so the dry basis mass of the oil sludge = 1 × (1-0.34) = 0.66 parts, and the total mass of the mixed fuel after drying = 9 + 0.66 = 9.66 parts.

[0026] In the mixed fuel: Volatile matter = Contribution from bituminous coal A + Contribution from oily sludge = (9 / 9.66) × 12.4% + (0.06 × 0.85 × 1 / 9.66) = 11.54% + 0.53% = 12.07%; Ash content = Contribution from bituminous coal A + Contribution from oily sludge solid phase = (9 / 9.66) × 11.1% + (0.58 × 1 / 9.66) = 10.34% + 6.01% = 16.35%; Carbon content = Contribution from bituminous coal A + Contribution from oily sludge + Contribution from solid phase carbon in oily sludge = (9 / 9.66)×86.9% + (0.06×0.75×1 / 9.66) + (0.008×0.58×1 / 9.66) = 80.83% + 0.46% + 0.05% = 81.34%; 3) Coal blending: According to the coal blending model, blended fuel (50%), bituminous coal B (30%), and bituminous coal C (20%) are mixed to prepare blended coal. Then: Total volatile matter = 12.07% × 50% + 22.2% × 30% + 41.8% × 20% = 28.5% (range of 28-31%); Overall ash content = 16.35% × 50% + 23.7% × 30% + 18.6% × 20% = 20.6% (≤ 25%); Overall carbon content = 81.34% × 50% + 77.6% × 30% + 72.3% × 20% = 78.3% (≥70%); The coal blending model is satisfied, with a volatile matter content of 28.5%. The process parameters of the coal mill are: feed rate 2-2.5t / h, grinding pressure 1.1-1.3MPa, ventilation volume 25-28m / s, inlet air temperature 55-60°C, and outlet temperature 9105-110°C, ensuring that the coal blending R90 at the coal mill outlet is ≤15%.

[0027] 4) Combustion utilization: The coal blend obtained in step 3) is used for power generation in a pulverized coal boiler. The technical parameters of the pulverized coal boiler are: furnace temperature 1300-1400°C, excess air coefficient 1.15-1.20, and secondary air volume ratio 20-25%.

[0028] Example 2 The basic material data involved in this embodiment are as follows: Bituminous coal A: volatile matter 15.2%, ash 16.4%, carbon content 82.5%, moisture content 0.6%; Bituminous coal B: Volatile matter 26.2%, ash content 19.6%, carbon content 76.3%, moisture content 0.9%; Bituminous coal C: Volatile matter 43.0%, ash 14.7%, carbon content 69.8%, moisture content 0.7%; Steel rolling sludge: 65% solid phase, 11% oil, 24% water. The chemical composition of the solid phase by mass percentage is: TFe 72.1%, C 1.4%, MnO 0.2%, CaO 0.7%, MgO 0.2%, SiO2 1.1%, Al2O3 0.1%, Cl 0.1%, S 0.05%, P 0.07%. Implementation process: 1) Raw material preparation: Mix 14 parts by weight of bituminous coal A (50-200 mesh) with 1 part by weight of steel rolling sludge to prepare a mixture.

[0029] 2) Drying: The mixture obtained in step 1) was fed into a hot air dryer (drying temperature 120°C, air velocity 0.7 m / s, drying time 38 min) to prepare a mixed fuel. The approximate contribution of steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel was calculated as follows: Raw material ratio: bituminous coal A (14 parts) + steel rolling sludge (1 part), total mass 15 parts.

[0030] Mass of dried sludge: initial moisture content of sludge is 24%, dry sludge mass = 1 × (1 - 0.24) = 0.76 parts, total mass of mixed fuel = 14 + 0.76 = 14.76 parts.

[0031] In the mixed fuel: Volatile matter = (14 / 14.76) × 15.2% + (0.11 × 0.85 × 1 / 14.76) = 14.33% + 0.63% = 14.96%; Ash content = (14 / 14.76) × 16.4% + (0.65 × 1 / 14.76) = 15.57% + 4.40% = 19.97% Carbon content = (14 / 14.76)×82.5% + (0.11×0.75×1 / 14.76) + (0.014×0.65×1 / 14.76) = 78.07% + 0.56% + 0.06% = 78.69%; Mixed fuel, bituminous coal B, and bituminous coal C are prepared by blending according to a coal blending model. The volatile matter content of the blended coal is calculated, and the R90 fineness of the blended coal obtained by grinding in a coal mill is determined based on the volatile matter content. A coal blend with a suitable R90 fineness is then prepared using a coal mill. The coal mill feed rate is 2-4 t / h, grinding pressure is 0.8-1.2 MPa, ventilation volume is 25-35 m / s, inlet air temperature is 40-60°C, discharge particle size is 80-120 μm, and discharge temperature is 90-110°C.

[0032] 3) Coal blending: According to the coal blending model, blended fuel (40%), bituminous coal B (35%), and bituminous coal C (25%) are mixed to prepare blended coal. Then: Total volatile matter = 14.96% × 40% + 26.2% × 35% + 43.0% × 25% = 31.8% (range of 31-34%) Overall ash content = 19.97% × 40% + 19.6% × 35% + 14.7% × 25% = 18.6% (≤25%) Overall carbon content = 78.69% × 40% + 76.3% × 35% + 69.8% × 25% = 74.6% (≥ 70%) The coal blending model is satisfied, with a volatile matter content of 31.8%. The process parameters of the coal mill are: feed rate 2.5-3.5t / h, grinding pressure 0.9-1.1MPa, ventilation volume 28-32m / s, inlet air temperature 50-55°C, and outlet temperature 95-105°C, ensuring that the coal blending R90 at the coal mill outlet is 15-18%.

[0033] 4) Combustion utilization: The coal obtained in step 3) is used for power generation in a pulverized coal boiler. The technical parameters of the pulverized coal boiler are: furnace temperature 1250-1350°C, excess air coefficient 1.10-1.15, and secondary air volume ratio 25-30%.

[0034] Example 3 The basic material data involved in this embodiment are as follows: Bituminous coal A: Volatile matter 18.9%, ash content 13.1%, carbon content 77.8%, moisture content 0.3%; Bituminous coal B: Volatile matter 28.8%, ash content 16.2%, carbon content 71.7%, moisture content 0.7%; Bituminous coal C: Volatile matter 44.3%, ash 11.4%, carbon content 63.9%, moisture content 0.4%; Steel rolling sludge: 69% solid phase, 14% oil, 17% water. The chemical composition of the solid phase by mass percentage is: TFe 70.1%, C 2.5%, MnO 0.4%, CaO 0.2%, MgO 0.4%, SiO2 0.9%, Al2O3 0.1%, Cl 0.1%, S 0.08%, P 0.03%.

[0035] Implementation process: 1) Raw material preparation: Mix 19 parts by weight of bituminous coal A (50-200 mesh) with 1 part by weight of steel rolling sludge to prepare a mixture.

[0036] 2) Drying: The mixture obtained in step 1) is fed into a hot air dryer (drying temperature 140°C, air velocity 0.9 m / s, drying time 55 min) to prepare a mixed fuel. The approximate contribution of steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel is as follows: Raw material ratio: Bituminous coal A (19 parts) + steel rolling sludge (1 part), total 20 parts by mass Mass of dried sludge: initial moisture content of sludge is 17%, dry sludge mass = 1 × (1 - 0.17) = 0.83 parts, total mass of mixed fuel = 19 + 0.83 = 19.83 parts.

[0037] In the mixed fuel: Volatile matter = (19 / 19.83) × 18.9% + (0.14 × 0.85 × 1 / 19.83) = 18.12% + 0.60% = 18.72% Ash content = (19 / 19.83) × 13.1% + (0.69 × 1 / 19.83) = 12.56% + 3.48% = 16.04% Carbon content = (19 / 19.83)×77.8%+(0.14×0.75×1 / 19.83)+(0.025×0.69×1 / 19.83)=74.54%+0.53%+0.09%=75.16%.

[0038] 3) Coal blending: According to the coal blending model, blended fuel (30%), bituminous coal B (25%), and bituminous coal C (45%) are mixed to prepare blended coal. Then: Total volatile matter = 18.72% × 30% + 28.8% × 25% + 44.3% × 45% = 34.6% (range of 34-37%) Total ash content = 16.04% × 30% + 16.2% × 25% + 11.4% × 45% = 13.6% (≤ 25%) Overall carbon content = 75.16% × 30% + 71.7% × 25% + 63.9% × 45% = 69.8% (≥ 70%) The coal blending model is satisfied, with a volatile matter content of 34.6%. The process parameters of the coal mill are: feed rate 3.5-4 t / h, grinding pressure 0.8-0.9 MPa, ventilation volume 32-35 m / s, inlet temperature 40-50°C, and outlet temperature 90-95°C, ensuring that the coal blending R90 at the coal mill outlet is 18-22%.

[0039] 4) Combustion utilization: The coal blend obtained in step 3) is used for power generation in a pulverized coal boiler. The technical parameters of the pulverized coal boiler are: furnace temperature 1200-1300°C, excess air coefficient 1.05-1.10, and secondary air volume ratio 30-35%.

[0040] To further illustrate the effectiveness of the method of the present invention, Table 1 lists the comparative examples of each embodiment without using steel rolling sludge. As can be seen from Table 1, although the coal blending schemes of the embodiments and the comparative examples are slightly different, the comprehensive volatile matter, comprehensive ash content, and comprehensive carbon content are similar, and the fuel conditions are similar. The present invention realizes the resource utilization of steel rolling sludge without affecting the boiler efficiency.

[0041] Table 1 Examples and Comparative Examples

Claims

1. A method for the resource utilization of steel rolling sludge and its coal blending and combustion, characterized in that: The method is as follows: 1) Raw material preparation: Mix 50-200 mesh bituminous coal A with steel rolling sludge at a mass ratio of 9-19:1 to prepare a mixture; 2) Drying: The mixture obtained in step 1) is fed into a hot air dryer to prepare a mixed fuel. The drying temperature is 100-150°C, the air velocity is 0.5-1m / s, and the drying time is 20-60min. The contribution of steel rolling sludge to the volatile matter, ash content, and carbon content of the mixed fuel is calculated according to simplified rules. 3) Coal blending: Mix the mixed fuel, bituminous coal B, and bituminous coal C according to the coal blending model to prepare the blended coal, calculate the volatile matter of the blended coal, and determine the R90 fineness of the blended coal obtained by grinding in the coal mill according to the volatile matter of the blended coal; 4) Combustion utilization: The coal blend obtained in step 3) is used as fuel for power generation in a pulverized coal boiler, and the technical parameters of the pulverized coal boiler are determined based on the volatile matter content.

2. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 1), the particle size of bituminous coal A is 50-200 mesh, and the weight characteristics of bituminous coal A are: volatile matter 10-20%, ash 10-20%, carbon content 75-90%, and moisture content ≤1%.

3. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 1), the steel rolling sludge comprises a solid phase, oil, and water, in the following mass percentages: solid phase 60-70%, oil 5-15%, water 15-40%; the chemical composition of the solid phase, in the following mass percentages, includes: TFe 70.0-90%, C≤3.0%, MnO≤0.5%, CaO≤1.0%, MgO≤0.5%, SiO2≤2.0%, Al2O3≤0.2%, Cl≤0.2%, S≤0.1%, P≤0.1%, with the balance being O element combined with Fe and other unavoidable impurities; the solid phase particle size characteristics are: particles with a diameter of 0.3-2 mm account for 50-80% of the total solid phase, and particles with a diameter less than 0.075 mm account for ≤5% of the total solid phase.

4. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 2), the moisture content of the mixed fuel is ≤1%; the simplified rules for calculating the volatile matter, ash content and carbon content in the mixed fuel are as follows: all solid phase in the steel rolling sludge is included in the ash content, oil is included in the volatile matter at 85% of its mass, oil is included in the carbon content at 75% of its mass, all carbon in the solid phase is included in the carbon content, and the moisture content after drying is calculated as 0%.

5. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 3), the weight composition of bituminous coal B is as follows: volatile matter 20-30%, ash 15-25%, carbon content 70-80%, and moisture content ≤1%.

6. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 3), the weight composition of the bituminous coal C is as follows: volatile matter 40-45%, ash 10-20%, carbon content 60-75%, and moisture content ≤1%.

7. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 3), the feed rate of the coal mill is 2-4 t / h, the grinding pressure is 0.8-1.3MPa, the ventilation volume is 25-35m / s, the inlet temperature is 40-60°C, and the outlet temperature is 90-110°C.

8. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 3), the coal blending model for mixed fuels, bituminous coal B, and bituminous coal C requires that the comprehensive volatile matter V of the blended coal be... mix 28-37%, Overall Ash Content A mix ≤25%, Overall carbon content C mix ≥70%.

9. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 3), if the volatile matter content of the blended coal is 28-<31%, the corresponding blending fineness R90 is ≤15%; if the volatile matter content of the blended coal is 31-<34%, the corresponding blending fineness R90 is 15-18%; if the volatile matter content of the blended coal is 34-37%, the corresponding blending fineness R90 is 18-22%.

10. The method for resource utilization and coal blending combustion of steel rolling sludge according to claim 1, characterized in that: In step 4), the technical parameters of the pulverized coal boiler are as follows: if the volatile matter content of the blended coal is 28% to <31%, the furnace temperature is 1300-1400°C, the excess air coefficient is 1.15-1.20, and the secondary air volume ratio is 20-25%; if the volatile matter content of the blended coal is 31% to <34%, the furnace temperature is 1250-1350°C, the excess air coefficient is 1.10-1.15, and the secondary air volume ratio is 25-30%; if the volatile matter content of the blended coal is 34% to 37%, the furnace temperature is 1200-1300°C, the excess air coefficient is 1.05-1.10, and the secondary air volume ratio is 30-35%.

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