Carbon-neutral iron ore sintering method based on biomass energy

Abstract

The present invention discloses a carbon-neutral iron ore sintering method based on biomass energy, comprising the steps of: 1. Carbonizing Class A biomass with low alkali metal content according to alkali metal content to obtain Class A biomass charcoal, carbonizing Class B biomass with high alkali metal content to obtain Class B biomass charcoal, or crushing Class B biomass; 2. Adding Class A biomass charcoal as a high-temperature sintering heat source to a sintering mixture, and the sintering mixture is laid on a sintering trolley to form a sintering material layer; 3. Adding Class B biomass or Class B biomass charcoal as a biomass fuel for heating circulating hot air into a hot blast furnace for combustion, and heating the circulating hot air mixed with sintering flue gas and ring cooling flue gas, and sending the circulating hot air to a high-temperature hot air hood; 4. Ignite the sintering material layer, and make the sintering material layer realize carbon-neutral iron ore sintering under the circulating hot air, and then cool and sieve the whole grain to obtain the finished sintered ore. The present invention can completely replace fossil fuels with biomass energy to achieve carbon-neutral iron ore sintering.

Description

Technical Field

[0001] The invention relates to a sintering process in the metallurgical industry, and in particular to a carbon-neutral iron ore sintering method based on biomass energy. Background Art

[0002] China's hot metal production has accounted for more than 60% of the world's total production for many years. However, since China's metallurgical process currently mainly adopts the process of sintering + blast furnace ironmaking, the steel industry's CO2 emissions are relatively high, accounting for about 15% of China's total emissions. CO2 emissions generated during the sintering process mainly come from fossil energy consumption. Therefore, the key to reducing CO2 emissions is to reduce the use of fossil fuels.

[0003] As a renewable clean carbon resource, biomass is a carbon-neutral substance compared to traditional fossil fuels, and can be regarded as not increasing CO2 emissions to the earth when burned. China produces 740 million tons of agricultural and forestry waste each year, accounting for 20%-30% of the world's total agricultural and forestry waste, but most of them are burned on site, causing serious waste and frequent fires and air pollution accidents. Using biomass in the sintering process can, on the one hand, effectively reduce the dependence of sintering on fossil energy and reduce the emission of pollutants such as CO2; on the other hand, it can also consume a large amount of agricultural and forestry waste, reduce the impact of open-air burning on the environment and society, and improve the utilization efficiency of waste.

[0004] In recent years, the use of different types of biomass fuels to partially or completely replace coke powder for sintering can reduce sintering greenhouse gas and pollutant emissions to a certain extent. For example, wood charcoal produced from red eucalyptus has a low ash content and few residual impurities after combustion. It can partially replace coke powder for sintering, but it will reduce the strength of the sintered ore. The higher the amount of wood charcoal used, the more significant the reduction in the drum strength of the sintered ore. For another example, when using biomass such as sunflower seed shells, olive residue, and almond shells to replace coke powder, the replacement ratio is less than 10% to not affect the strength of the sintered ore; when using wood charcoal, straw charcoal, and molded sawdust to replace coke powder, the replacement ratios are less than 40%, less than 20%, and less than 15%, respectively, to not affect the strength of the sintered ore. Therefore, the proportion of biomass fuel replacing coke powder is very limited.

[0005] Chinese invention patent ZL201110180196.3 discloses a method for preparing and applying biomass briquette fuel for iron ore sintering. The preparation of biomass briquette fuel is to hot-press and shape it under the condition of adding silica sol and slaked lime to obtain solid briquette fuel. The biomass briquette fuel is applied to iron ore sintering, replacing 0-40% of fossil fuels according to the heat replacement ratio of 0.75-1.0.

[0006] Chinese invention patent ZL201110180200.6 discloses a biochar for iron ore sintering and its preparation and application. The biochar adopts a two-stage carbonization process, through the combination of low-temperature carbonization and high-temperature carbonization, and under the strengthening effect of the additive asphalt, the density of 1.1-1.4g / cm 3 , biochar with a fixed carbon content of 75-90%, a volatile content of 5-15%, and a calorific value of 25-32MJ / kg, and crush it into a suitable particle size composition. Applying biochar to iron ore sintering can replace 0-60% of fossil fuels.

[0007] Chinese invention patent ZL201110180961.1 discloses an iron ore sintering method combining flue gas circulation and biomass energy, which circulates the sintering flue gas with high pollutant concentration at the tail of the sintering machine to the sintering material layer using biomass as fuel. By controlling the composition, temperature and circulation method of the circulating flue gas, the performance and amount of the biomass fuel are controlled, so that the sintering heat transfer behavior and combustion behavior of the flue gas circulation and biomass energy combined have good matching.

[0008] Although the above patent can partially replace coke powder with biomass fuel for sintering, thereby reducing the consumption of fossil fuels, there are the following problems:

[0009] 1. Biomass is added to sintering in the form of solid fuel, which can only partially replace solid fossil fuels, but cannot replace gaseous fossil fuels used for sintering ignition.

[0010] 2. The alkali metal content in agricultural and forestry biomass, especially agricultural biomass, is particularly high. If biomass fuel is directly added to sintering in a high proportion in the form of solid fuel, a large amount of alkali metals will be introduced, resulting in a high alkali metal content in the sintered ore. The large-scale use of sintered ore with high alkali metal content in blast furnaces will accelerate the deterioration of the metallurgical properties of coke and ore in the furnace, affecting the normal production of the blast furnace.

[0011] 3. Under the process conditions of directly adding biomass fuel into sintering in the form of solid fuel, in order to avoid excessive alkali metal in the sintered ore, the selection range of biomass or the proportion of biomass must be strictly controlled, and the type and amount of biomass are subject to great restrictions.

[0012] 4. The volatile content of biomass fuel is particularly high. Even after two carbonizations, the volatile content of biomass fuel is as high as 5-15%, which is much higher than the volatile content of coke powder. If biomass fuel is directly added to sintering at a high proportion, a large amount of high-molecular organic matter will be produced during the sintering process, thus affecting the efficiency and life of the sintering flue gas electrostatic precipitator system and the desulfurization and denitrification system. Summary of the invention

[0013] The purpose of the present invention is to provide a carbon-neutral iron ore sintering method based on biomass energy, which can use biomass energy to completely replace fossil fuels, does not increase CO2 emissions, and achieves carbon-neutral iron ore sintering.

[0014] The present invention is achieved in that:

[0015] A carbon-neutral iron ore sintering method based on biomass energy comprises the following steps:

[0016] Step 1: dividing the biomass into Class A biomass with low alkali metal content and Class B biomass with high alkali metal content according to the alkali metal content, and performing carbonization pretreatment on Class A biomass to obtain Class A biomass charcoal, performing carbonization pretreatment on Class B biomass to obtain Class B biomass charcoal, or crushing Class B biomass;

[0017] Step 2: Class A biomass charcoal is used as a high-temperature sintering heat source, and Class A biomass charcoal is mixed with iron ore powder, flux and return ore to form a sintering mixture, and the sintering mixture is laid on the sintering trolley to form a sintering material layer;

[0018] Step 3: Add the crushed Class B biomass or Class B biomass charcoal as biomass fuel for heating circulating hot air into the hot air furnace for combustion, and heat the circulating hot air mixed with sintering flue gas and ring cooling flue gas, and transport the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley;

[0019] Step 4: Ignite the sintering material layer, and make the sintering material layer realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore.

[0020] In step 1, the alkali metals include potassium and sodium; in terms of mass percentage, low alkali metal content means: the content of potassium + sodium in the biomass is ≤0.2%, and high alkali metal content means: the content of potassium + sodium in the biomass is >0.2%.

[0021] In the step 1, the carbonization pretreatment method of Class A biomass is: first pre-press the Class A biomass under a pressure of 200-250MPa, then heat the pre-pressed Class A biomass to 600-700°C at a heating rate of 5-15°C / min for pyrolysis and carbonization, and the carbonization time is 15-30min to obtain Class A biomass charcoal.

[0022] The average particle size of the Class A biochar is 3-5 mm, the volatile matter content is 3-8%, and the density is 1.3-1.6 g / cm 3 , the calorific value is 28-35MJ / kg.

[0023] In the step 1, the crushing particle size of the Class B biomass is less than 5 mm, and the calorific value is ≥ 18 MJ / kg.

[0024] In the step 1, the carbonization pretreatment method of the Class B biomass is: heating the biomass to 400-500°C at a heating rate of 15-25°C / min for pyrolysis carbonization, the carbonization time is 15-30min, and Class B biomass charcoal is obtained.

[0025] The particle size of the Class B biochar is less than 5 mm, and the calorific value is greater than or equal to 18 MJ / kg.

[0026] In the step 3, the coverage range of the high-temperature hot air hood above the sintering trolley is from the distribution device to the bellows where the over-wet zone of the sintering material layer disappears, and the proportion of Class A biochar in the sintering mixture is inversely proportional to the temperature of the circulating hot air in the high-temperature hot air hood.

[0027] The temperature of the circulating hot air is 1000-1200° C., and the proportion of Class A biochar in the corresponding sintering mixture is 1.8-0.8%.

[0028] In the step 3, the sintering flue gas is the dust-removed flue gas from the main flue of the sintering machine, and the ring cooling flue gas is the flue gas generated by the ring cooler in the process of cooling the hot sintered ore, and the temperature of the ring cooling flue gas is 100-400°C; by volume percentage, the sintering flue gas accounts for 50-80% of the circulating hot air, and the ring cooling flue gas accounts for 20-50% of the circulating hot air.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention divides biomass into Class A biomass with an alkali metal content of ≤0.2% and Class B biomass with an alkali metal content of >0.2% according to the alkali metal (K+Na) content, and carbonizes Class A biomass as a high-temperature sintering heat source and adds it to the sintering mixture, while crushing or carbonizing Class B biomass as a biomass fuel to heat the circulating hot air, so that Class A biomass and Class B biomass can completely replace fossil fuels, which can not only avoid the problem of increased alkali metal content in sintered ore, but also expand the range of biomass types for iron ore sintering, thereby realizing efficient resource value-added utilization of most biomass in the iron ore sintering process.

[0031] 2. The present invention heats the circulating hot air mixed with sintering flue gas and ring cooling flue gas to 1000-1200°C by burning biomass fuel, and the circulating hot air is transported to the sintering mixture layer with Class A biomass charcoal with low alkali metal content as high-temperature sintering heat source for ignition and sintering. This can completely avoid the use of fossil fuels and achieve carbon-neutral iron ore sintering.

[0032] 3. Since the present invention strictly limits the average particle size, volatile matter content and addition ratio of Class A biochar used as a high-temperature sintering heat source, it can effectively mitigate the negative impact of volatile matter and fine carbon powder on the sintering flue gas electrostatic precipitator system and the desulfurization and denitrification system.

[0033] 4. The circulating hot air of the present invention mainly comes from the main flue gas, which can achieve NO x 、SO x It can circulate and enrich pollutants such as sulfur dioxide and nitrogen oxides, and reduce the flue gas treatment volume of the desulfurization and denitrification system, thereby greatly improving the operating efficiency of the desulfurization and denitrification system.

[0034] The present invention adds biomass charcoal with low alkali metal content to the sintering mixture, and adopts biomass charcoal with high alkali metal content or biomass to heat circulating hot air and perform high-temperature hot air sintering through circulating hot air, so as to realize the complete replacement of fossil fuels with biomass energy; at the same time, biomass, as a carbon-neutral substance, can be regarded as not increasing CO2 emissions when burned, thereby realizing carbon-neutral iron ore sintering without affecting the quality of sintered ore, and at the same time, it can also make full use of various types of biomass fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the carbon-neutral iron ore sintering method based on biomass energy of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] Please see attached Figure 1 , a carbon-neutral iron ore sintering method based on biomass energy, comprising the following steps:

[0038] Step 1: The biomass is divided into Class A biomass with low alkali metal content and Class B biomass with high alkali metal content according to the alkali metal content, and the Class A biomass is carbonized and pretreated, and the Class B biomass is crushed or carbonized.

[0039] The alkali metals include potassium (K) and sodium (Na); in terms of mass percentage, low alkali metal content means: the content of potassium + sodium in the biomass is ≤0.2%, and high alkali metal content means: the content of potassium + sodium in the biomass is >0.2%.

[0040] The carbonization pretreatment method of Class A biomass is: first pre-press the Class A biomass under a pressure of 200-250MPa, then heat the pre-pressed Class A biomass to 600-700°C at a heating rate of 5-15°C / min for pyrolysis and carbonization, and the carbonization time is 15-30min to obtain Class A biomass charcoal, so that it can replace part of solid fossil fuels.

[0041] The average particle size of the Class A biochar is 3-5 mm, the volatile matter content is 3-8%, and the density is 1.3-1.6 g / cm 3The calorific value is 28-35MJ / kg, which can effectively reduce the negative impact of volatile matter and fine carbon powder on the sintering flue gas electrostatic precipitator system and desulfurization and denitrification system.

[0042] Class B biomass with a higher calorific value can be directly used after being crushed. The crushed particle size of the Class B biomass is <5 mm, and the calorific value is ≥18MJ / kg. The existing crushing equipment can be used to crush the Class B biomass.

[0043] For Class B biomass with low calorific value, carbonization treatment can be performed to increase the calorific value before use. The carbonization pretreatment method of Class B biomass is: heating the biomass to 400-500°C at a heating rate of 15-25°C / min for pyrolysis and carbonization, and the carbonization time is 15-30min to obtain Class B biomass charcoal.

[0044] The particle size of the Class B biochar is less than 5 mm, and the calorific value is greater than or equal to 18 MJ / kg.

[0045] Step 2: Class A biomass charcoal is used as a high-temperature sintering heat source, and Class A biomass charcoal is mixed with iron ore powder, flux and return ore to form a sintering mixture, and the sintering mixture is distributed to the sintering trolley by a distribution device to form a sintering material layer. The ratio of Class A biomass charcoal, iron ore powder, flux and return ore can adopt the ratio of fossil fuel, iron ore powder, flux and return ore in the prior art.

[0046] Step 3: Add the crushed Class B biomass or Class B biochar as biomass fuel for heating circulating hot air into the hot air furnace for combustion, and heat the circulating hot air mixed with sintering flue gas and ring cooling flue gas, and then transport the circulating hot air to the high-temperature hot air hood covering the sintering trolley. Class A biochar can replace part of the solid fossil fuels in fossil fuels, and the circulating hot air can be used to replace the remaining solid fossil fuels and gaseous fossil fuels in fossil fuels, so that Class A biomass and Class B biomass can completely replace fossil fuels and completely avoid the consumption of fossil fuels during sintering.

[0047] The proportion of Class A biochar in the sintering mixture is inversely proportional to the temperature of the circulating hot air in the high-temperature hot air hood, that is, the higher the temperature of the circulating hot air, the lower the proportion of Class A biochar in the sintering mixture, and conversely, the lower the temperature of the circulating hot air, the higher the proportion of Class A biochar in the sintering mixture.

[0048] The temperature of the circulating hot air is 1000-1200°C, and the proportion of Class A biochar in the corresponding sintering mixture is 1.8-0.8%. The circulating hot air at 1000-1200°C can provide sufficient heat for the sintering process and replace gas fossil fuels for ignition, thereby achieving complete replacement of fossil fuels with biochar.

[0049] The sintering flue gas is the dust-removed flue gas from the main flue of the sintering machine, and the ring-cooling flue gas is the ring-cooling flue gas generated by the ring-cooler in the process of cooling the hot sintered ore, and the temperature of the ring-cooling flue gas is 100-400°C; by volume percentage, the sintering flue gas accounts for 50-80% of the circulating hot air, and the ring-cooling flue gas accounts for 20-50% of the circulating hot air.

[0050] The hot blast furnace can be an indirect heat exchange hot blast furnace, and the combustion of Class B biomass or Class B biomass charcoal in the hot blast furnace will not change the composition of the circulating hot air.

[0051] The coverage range of the high-temperature hot air hood above the sintering trolley is from the material distribution device to the wind box where the over-wet zone of the sintering material layer disappears.

[0052] Step 4: Ignite the sintering material layer, and make the sintering material layer realize carbon neutral iron ore sintering under circulating hot air, and then cool and screen the whole grain to obtain the finished sintered ore. The sintering, cooling and screening of the sintering material layer can adopt the existing process flow, which will not be repeated here.

[0053] Embodiment 1:

[0054] Step 1: Pre-press the Class A biomass with a potassium + sodium content of 0.2% under a pressure of 200 MPa, and then heat the pre-pressed Class A biomass to 600°C at a heating rate of 15°C / min for pyrolysis and carbonization for 30 minutes to obtain Class A biochar. The average particle size of Class A biochar is 5 mm, the volatile content is 8%, and the density is 1.3 g / cm 3 , the calorific value is 28MJ / kg.

[0055] Class B biomass with a potassium + sodium content of 0.3% is crushed to a particle size of less than 5 mm and used as biomass fuel for heating circulating hot air.

[0056] Step 2: Class A biochar is used as a high-temperature sintering heat source. Class A biochar is mixed with iron ore powder, flux and return ore to form a sintering mixture. By mass percentage, the sintering mixture includes 1.8% Class A biochar, 67.56% iron ore powder, 9.69% flux and 20.95% return ore. The sintering mixture is distributed to the sintering trolley by the distribution device.

[0057] Step 3: Add the crushed Class B biomass into the indirect heat exchange hot air furnace for combustion, heat the circulating hot air mixed with 50% of the sintering flue gas after dust removal from the main flue and 50% of the 100-200℃ ring cooling flue gas to 1000℃, and convey the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley. The coverage of the high-temperature hot air hood above the sintering trolley extends from the material distribution device to the wind box where the over-wet zone of the sintering material layer disappears.

[0058] Step 4: Ignite the sintering mixture, and make the sintered mixture realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore.

[0059] In this example, the yield of sintered ore is 78.32% and the utilization coefficient is 1.48 t / m 2 / h, the consumption of fossil fuels is 0kg / ts, which completely avoids the consumption of fossil fuels on the basis of ensuring the quality of sintered ore and does not increase CO2 emissions, thus realizing carbon-neutral iron ore sintering.

[0060] Embodiment 2:

[0061] Step 1: Pre-press the Class A biomass with a potassium + sodium content of 0.15% under a pressure of 220MPa, and then heat the pre-pressed Class A biomass to 650℃ at a heating rate of 10℃ / min for pyrolysis and carbonization for 25min to obtain Class A biochar. The average particle size of Class A biochar is 4mm, the volatile content is 6%, and the density is 1.4g / cm 3 , the calorific value is 30MJ / kg.

[0062] Class B biomass with a potassium + sodium content of 1.0% was carbonized at 400°C for 15 minutes to obtain Class B biomass charcoal. The average particle size of the Class B biomass charcoal was 4.8 mm and the calorific value was 18 MJ / kg, which was used as a biomass fuel for heating circulating hot air.

[0063] Step 2: Class A biochar is used as a high-temperature sintering heat source. Class A biochar is mixed with iron ore powder, flux and return ore to form a sintering mixture. By mass percentage, the sintering mixture includes 1.3% Class A biochar, 68.06% iron ore powder, 9.69% flux and 20.95% return ore. The sintering mixture is spread on the sintering trolley by the spreading device to form a sintering material layer.

[0064] Step 3: Add Class B biochar to the indirect heat exchange hot air furnace for combustion, heat the circulating hot air mixed with 60% of the sintering flue gas after dust removal from the main flue and 40% of the 200-300℃ ring cooling flue gas to 1100℃, and transport the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley. The coverage of the high-temperature hot air hood above the sintering trolley extends from the material distribution device to the wind box where the over-wet zone of the sintering material layer disappears.

[0065] Step 4: Ignite the sintering material layer and make the sintering material layer realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore.

[0066] In this example, the yield of sintered ore is 78.57% and the utilization coefficient is 1.50t / m 2 / h, the consumption of fossil fuels is 0kg / ts, which completely avoids the consumption of fossil fuels on the basis of ensuring the quality of sintered ore and does not increase CO2 emissions, thus realizing carbon-neutral iron ore sintering.

[0067] Embodiment 3:

[0068] Step 1: Pre-press the Class A biomass with a potassium + sodium content of 0.1% under a pressure of 250MPa, and then heat the pre-pressed Class A biomass to 700℃ at a heating rate of 5℃ / min for pyrolysis and carbonization for 15min to obtain Class A biochar. The average particle size of Class A biochar is 4mm, the volatile content is 5%, and the density is 1.5g / cm 3 , the calorific value is 33MJ / kg.

[0069] Class B biomass with a potassium + sodium content of 10.0% was carbonized at 500°C for 30 minutes to obtain Class B biomass charcoal. The average particle size of the Class B biomass charcoal was 4 mm and the calorific value was 24 MJ / kg, which was used as a biomass fuel for heating circulating hot air.

[0070] Step 2: Class A biochar is used as a high-temperature sintering heat source. Class A biochar is mixed with iron ore powder, flux and return ore to form a sintering mixture. By mass percentage, the sintering mixture includes 1.1% Class A biochar, 68.26% iron ore powder, 9.69% flux and 20.95% return ore. The sintering mixture is spread on the sintering trolley by the spreading device to form a sintering material layer.

[0071] Step 3: Add Class B biochar to the indirect heat exchange hot air furnace for combustion, heat the circulating hot air mixed with 80% of the sintering flue gas after dust removal from the main flue and 20% of the 300-400℃ ring cooling flue gas to 1100℃, and transport the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley. The coverage of the high-temperature hot air hood above the sintering trolley extends from the material distribution device to the wind box where the over-wet zone of the sintering material layer disappears.

[0072] Step 4: Ignite the sintering material layer and make the sintering material layer realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore.

[0073] In this example, the yield of sintered ore is 78.32%, and the utilization coefficient is 1.51t / m 2 / h, the consumption of fossil fuels is 0kg / ts, which completely avoids the consumption of fossil fuels on the basis of ensuring the quality of sintered ore and does not increase CO2 emissions, thus realizing carbon-neutral iron ore sintering.

[0074] Embodiment 4:

[0075] Step 1: Pre-press the Class A biomass with a potassium + sodium content of 0.05% under a pressure of 250MPa, and then heat the pre-pressed Class A biomass to 700℃ at a heating rate of 5℃ / min for pyrolysis and carbonization for 30min to obtain Class A biochar. The average particle size of Class A biochar is 3mm, the volatile content is 3%, and the density is 1.6g / cm 3 , the calorific value is 35MJ / kg.

[0076] Class B biomass with a potassium + sodium content of 2.0% was carbonized at 500°C for 30 minutes to obtain Class B biomass charcoal. The average particle size of the Class B biomass charcoal was 3 mm and the calorific value was 27 MJ / kg, which was used as a biomass fuel for heating circulating hot air.

[0077] Step 2: Class A biochar is used as a high-temperature sintering heat source. Class A biochar is mixed with iron ore powder, flux and return ore to form a sintering mixture. By mass percentage, the sintering mixture includes 0.8% Class A biochar, 68.56% iron ore powder, 9.69% flux and 20.95% return ore. The sintering mixture is spread on the sintering trolley by the spreading device to form a sintering material layer.

[0078] Step 3: Add Class B biochar to the indirect heat exchange hot air furnace for combustion, heat the circulating hot air mixed with 70% of the sintering flue gas after dust removal from the main flue and 30% of the 300-400℃ ring cooling flue gas to 1200℃, and transport the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley. The coverage of the high-temperature hot air hood above the sintering trolley extends from the material distribution device to the wind box where the over-wet zone of the sintering material layer disappears.

[0079] Step 4: Ignite the sintering material layer and make the sintering material layer realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore.

[0080] In this example, the yield of sintered ore is 77.85%, and the utilization coefficient is 1.53t / m 2 / h, the consumption of fossil fuels is 0kg / ts, which completely avoids the consumption of fossil fuels on the basis of ensuring the quality of sintered ore and does not increase CO2 emissions, thus realizing carbon-neutral iron ore sintering.

[0081] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A carbon-neutral iron ore sintering method based on biomass energy, characterized by: The following steps are involved: Step 1: dividing the biomass into Class A biomass with low alkali metal content and Class B biomass with high alkali metal content according to the alkali metal content, and performing carbonization pretreatment on Class A biomass to obtain Class A biomass charcoal, performing carbonization pretreatment on Class B biomass to obtain Class B biomass charcoal, or crushing Class B biomass; Step 2: Class A biomass charcoal is used as a high-temperature sintering heat source, and Class A biomass charcoal is mixed with iron ore powder, flux and return ore to form a sintering mixture, and the sintering mixture is laid on the sintering trolley to form a sintering material layer; Step 3: Add the crushed Class B biomass or Class B biomass charcoal as biomass fuel for heating circulating hot air into the hot air furnace for combustion, and heat the circulating hot air mixed with sintering flue gas and ring cooling flue gas, and transport the circulating hot air to the high-temperature hot air hood covering the top of the sintering trolley; Step 4: Ignite the sintering material layer, and make the sintering material layer realize carbon-neutral iron ore sintering under circulating hot air, and then successively cool and screen the whole particles to obtain the finished sintered ore; In the step 1, the alkali metal includes potassium and sodium; in terms of mass percentage, low alkali metal content means: the content of potassium + sodium in the biomass is ≤ 0.2%, and high alkali metal content means: the content of potassium + sodium in the biomass is > 0.2%; The temperature of the circulating hot air is 1000-1200° C., and the proportion of Class A biochar in the corresponding sintering mixture is 1.8-0.8%.

2. The carbon-neutral iron ore sintering method based on biomass energy according to claim 1 is characterized in that: In the step 1, the carbonization pretreatment method of Class A biomass is: first pre-press the Class A biomass under a pressure of 200-250MPa, then heat the pre-pressed Class A biomass to 600-700°C at a heating rate of 5-15°C / min for pyrolysis and carbonization, and the carbonization time is 15-30min to obtain Class A biomass charcoal.

3. The carbon-neutral iron ore sintering method based on biomass energy according to claim 2 is characterized in that: The average particle size of the Class A biochar is 3-5 mm, the volatile matter content is 3-8%, and the density is 1.3-1.6 g / cm 3 , the calorific value is 28-35MJ / kg.

4. The carbon-neutral iron ore sintering method based on biomass energy according to claim 1 is characterized by: In the step 1, the crushing particle size of the Class B biomass is less than 5 mm, and the calorific value is ≥ 18 MJ / kg.

5. The carbon-neutral iron ore sintering method based on biomass energy according to claim 1 is characterized by: In the step 1, the carbonization pretreatment method of the Class B biomass is: heating the biomass to 400-500°C at a heating rate of 15-25°C / min for pyrolysis carbonization, the carbonization time is 15-30min, and Class B biomass charcoal is obtained.

6. The carbon-neutral iron ore sintering method based on biomass energy according to claim 5 is characterized by: The particle size of the Class B biochar is less than 5 mm, and the calorific value is greater than or equal to 18 MJ / kg.

7. The carbon-neutral iron ore sintering method based on biomass energy according to claim 1 is characterized by: In the step 3, the coverage range of the high-temperature hot air hood above the sintering trolley is from the distribution device to the bellows where the over-wet zone of the sintering material layer disappears, and the proportion of Class A biochar in the sintering mixture is inversely proportional to the temperature of the circulating hot air in the high-temperature hot air hood.

8. The carbon-neutral iron ore sintering method based on biomass energy according to claim 1 is characterized by: In the step 3, the sintering flue gas is the dust-removed flue gas from the main flue of the sintering machine, and the ring cooling flue gas is the flue gas generated by the ring cooler in the process of cooling the hot sintered ore, and the temperature of the ring cooling flue gas is 100-400°C; by volume percentage, the sintering flue gas accounts for 50-80% of the circulating hot air, and the ring cooling flue gas accounts for 20-50% of the circulating hot air.

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