Pre-treatment method for raw materials

Abstract

A method for pretreating a feed material, the method comprising: subjecting either coal that is outside the blast-furnace-production range or a coal-substitute solid fuel to a dry distillation treatment under such conditions that the maximum dry distillation temperature is 900°C or higher; separating the combustible substances resulting from the dry distillation treatment into a solid fuel, a liquid fuel, and a gaseous fuel; and blowing some or all of the solid fuel, liquid fuel, or gaseous fuel into a metallurgical furnace.

Description

Technical Field

[0001] The present invention relates to a pretreatment method for raw materials in a blast furnace ironmaking process that also includes sintering machines and carbonization furnaces. In particular, it relates to the pretreatment and handling of raw materials in the blast furnace ironmaking process, and concerns the expansion of raw material options and CO2 reduction.

Background Art

[0002] In the blast furnace process, coke and iron ore are charged from the furnace top, and hot air (high-temperature air at 1000°C or higher) as well as pulverized coal or the like as a reducing agent are blown in from the tuyeres located at the lower part of the furnace. Accordingly, the pulverized coal and coke combust, generating a large amount of heat together with high-temperature reducing gas (CO and H2), which rises inside the furnace and heats and reduces the descending iron ore.

[0003] Blast furnace coke is required to have low ash and sulfur contents, appropriate porosity, and strength that prevents pulverization even at high temperatures. For the production of coke that meets such conditions, only a limited number of coals among bituminous coals are used, which are called coking coal (application classification name) and are distinguished from steam coal that is mainly used as fuel for power generation.

[0004] In a coke oven, crushed and blended coking coal is charged into a carbonization chamber, and is indirectly heated at 1,000 to 1,300°C for 14 to 20 hours to perform destructive distillation (carbonization), thereby producing coke. At this time, fuel gas (COG), tar and the like are obtained as by-products.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0006] [Non-Patent Document 1] Katsuhiko Yamamoto, Shinichi Misawa, Kazuhiko Koizuka, and Ryohei Mimura, "Experiments on the Development of Uses for Recycled Fuel (RDF) through Carbonization Treatment," Transactions of the Japan Society of Waste Management, Japan Society of Waste Management and Resource Recycling, 2000, Vol. 11, No. 4. [Non-Patent Document 2] Uwe Essmann, “Biochar-pellets as substitute for fossil coal in metallurgical processes”, Master's thesis Renewable Energy ENE500, University of Agder, 2018 [Non-Patent Document 3] Japan Energy Society (ed.), "Biomass Handbook (2nd Edition)", Japan Energy Society, 2009. [Non-Patent Document 4] Nippon Steel Corporation, "Recycling Technology for General Waste Plastics Using Coke Oven Chemical Raw Material Method," 58th Okouchi Memorial Production Award, Okouchi Memorial Association, 2011. [Non-Patent Document 5] Tatsuya Oki, Junichi Tanaka, and Taneomi Harada, "Factors in the pulverizability of coal," Resources and Materials, Japan Society for Resources and Materials, 1996, Vol. 112, No. 1, pp. 37-42. [Non-Patent Document 6] Takuya Furuzono, Akihiro Hoshino, Tsuyoshi Teramae, Ikuo Hosoya, and Toru Yamashita, "Basic Study on the Grinding Characteristics of Semi-Carbonized Pellets," The 54th Coal Science Conference of the Japan Energy Society, 2017. [Non-Patent Document 7] Kazuhiko Nakaoji, Yoichi Nakamura, and Katsumi Muroi, "Deashification Technology for Coal and its Practical Application," Hitachi Review, Hitachi Review Co., Ltd., 1984, Vol. 66, No. 2. [Overview of the project]

[0007] In blast furnaces, which are metallurgical furnaces, the quality of pulverized coal (PC) blown in through the tuyere is limited, although there are fewer constraints than with coking coal. Therefore, instead of blowing the coal or coal substitute solid fuel (tuyere-blown solid fuel) directly through the tuyere, the coal is separated into solid, liquid, and gaseous components in a high-temperature carbonization furnace such as a coke oven. The solid component (char) is then blown in through the blast furnace tuyere, the gaseous component (COG) is reformed into a high-temperature reducing gas and blown into the blast furnace, and the combustible component (tar, etc.) in the liquid is blown in through the blast furnace tuyere. This leads to a reduction in the decomposition heat of the tuyere-blown solid fuel, which increases the effective calorific value of the fuel, reduces the amount of tuyere-blown solid fuel used, and reduces the fuel ratio and combustion-supporting gas (oxygen) in the blast furnace, thereby reducing CO2 emissions.

[0008] According to the above method, renewable fuels with very high VM (volatile content) (such as biopellets and biochar), RDF (Refuse Derived Fuel; solid fuel produced from combustible general waste), and RPF (Refuse Paper and Plastic Fuel; solid fuel produced from combustible industrial waste) can be used as blast furnace fuel (reducing agent) as coal substitute solid fuels. Here, impurities such as heavy metals and alkalis in the waste are removed from the char by chlorine volatilization in the high-temperature carbonization furnace due to the chlorine in the waste, so there is no hindrance to the operation of the blast furnace as a metallurgical furnace.

[0009] By using renewable fuels and solid waste fuels, the use of fossil fuels (coal) can be reduced, eliminating the need for CO2 treatment costs and energy derived from the reduction in fossil fuels (coal) or from alternative fuels. [Problems that the invention aims to solve]

[0010] The steel industry uses fossil fuels such as coal and natural gas as reducing agents and combustion fuels in blast furnaces, resulting in large emissions of CO2, and reduction measures are expected. Underground storage of CO2 presents challenges in terms of stable ground and local agreement, and the reuse of CO2 (C recycling) and H2 reduction require large amounts of H2 and green electricity, making it economically challenging, including infrastructure. The inventors of this invention have devised an unprecedented CO2 reduction measure for blast furnaces (Patent Document 1), but even with this, there is still room for further reduction in CO2 emissions when C recycling and underground storage are not considered. Furthermore, while this invention can reduce the coke ratio to less than 1 / 5 of the conventional method, reducing coke also reduces the by-product, powdered coke. Since powdered coke is used as a binder in sintering machines, it is necessary to compensate for the powdered coke shortage with anthracite, but there are concerns that the VM (volatile matter) of anthracite cannot be effectively utilized thermally and will generate tar, causing various problems.

[0011] Furthermore, according to Patent Document 1, blast furnace tuyeres injected fuel has a high primary combustion heat (the reaction C + 0.5 × O2 = CO), and the thermal decomposition heat generated before combustion (C i H j O k Materials with a low amount of heat required to decompose into i × C + 0.5j × H2 + 0.5k × O2 are preferred, and a low amount of VM is desirable. This is why, in conventional blast furnace PCI (Pulverized Coal Injection) facilities, there has recently been a trend towards using LV coal (low VM coal). The reason why the injection of biochar into tuyeres is being considered worldwide as a CO2 reduction measure is that the VM of biofuels is very high, so the idea is to carbonize them at collection sites (dry distillation at 400-700°C) to reduce the VM to the level of anthracite to MV coal (medium VM coal) (increasing the calorific value) and then inject them into the furnace. However, the yield of char when carbonizing biomass is only about 20%, and gases and tars are difficult to utilize effectively except for the heat required for carbonization, resulting in low energy efficiency.

[0012] On the other hand, greenhouse gas emissions from waste incineration in Japan amount to approximately 40 million tons, accounting for 3% of Japan's total emissions and equivalent to about 40% of emissions from the steel industry.

[0013] Increasingly, general waste incineration facilities are being equipped with power generation equipment to effectively utilize waste heat. However, challenges remain regarding incineration residues caused by chlorine, alkali, and heavy metals in the waste, and coupled with boiler wall corrosion issues, power generation efficiency is low, averaging around 15% nationwide. Energy efficiency, including self-consumption, is even lower. Furthermore, from the perspective of reducing CO2 emissions, power generation using incinerators or RDF / RPF does not reduce CO2 emissions; rather, it is a form of thermal recycling where the increased power generation may reduce the use of fossil fuels in thermal power plants. Biomass power generation and renewable fuel power generation also fall under the realm of thermal recycling, and for essential CO2 reduction, it is crucial to rationally implement material recycling and chemical recycling. [Means for solving the problem]

[0014] In the raw material pretreatment method according to an embodiment of the present invention, coal or coal substitute solid fuel outside the range of coke production is subjected to carbonization under conditions where the carbonization temperature reaches a maximum of 900°C or higher, the combustible material generated by the carbonization is separated into solid fuel, liquid fuel, and gaseous fuel, and then some or all of the solid fuel, liquid fuel, or gaseous fuel is blown into a metallurgical furnace, such as a blast furnace. [Effects of the Invention]

[0015] The above-described pre-treatment method for raw materials allows for the replacement of blown solid fuels such as coal and coal substitutes (hereinafter referred to as "coal, etc.") with char (C+Ash) which has almost no volatile matter (VM) in a high-temperature carbonization furnace where the maximum temperature exceeds 900°C. This eliminates the decomposition heat of the blast furnace tuyere-injected solid fuel and increases the calorific value. As a result, the blast furnace tuyere-injected solid fuel ratio (kg / tp) and the oxygen ratio (Nm³) of the combustion gas required to produce 1 ton of molten iron are lower than when coal, etc. is directly injected from the blast furnace tuyere. 3This reduces the amount of waste ( / tp). Furthermore, this makes it possible to use high-VM fuels such as HV coal, biomass solid fuels, and waste solid fuels as reducing agents for blast furnaces. Here, impurities such as heavy metals and alkalis in the waste are removed from the char by chlorine volatilization in the high-temperature carbonization furnace due to the chlorine in the waste, so there is no disruption to blast furnace operation.

[0016] The above-mentioned pre-treatment method for raw materials increases the amount of gas (hereinafter referred to as COG; Coke Oven Gas) generated in coke ovens and high-temperature carbonization furnaces (hereinafter referred to as high-temperature carbonization furnaces, etc.) compared to when coal is directly injected into the blast furnace. COG is mainly hydrogen but also contains components such as CH4 and CO2, so if it is converted to H2 and CO and heated before being injected into the blast furnace, the gas reduction of the ore can be promoted, thereby reducing the use of other fuels.

[0017] The above-mentioned pre-treatment method for raw materials increases the amount of combustible liquid (referring to tar, crude light oil, etc., hereinafter referred to as "tar, etc.") generated in high-temperature carbonization furnaces, etc., compared to when coal is directly injected into the blast furnace. While tar, etc. can be used as combustion fuel in ironmaking equipment (hot blast furnaces, coke ovens, sintering machines), it is preferable to use it as a tuyere injection reducing agent, and even better, to utilize it as oil (transportation method and tuyere injection fuel) for COM (Coal Oil Mixture), which is the means of transporting and injecting solid fuel injected into blast furnace tuyeres.

[0018] The char produced by the above-mentioned pre-treatment method for raw materials can also be used as a binder for sintering machines, solving the problems that arise when using anthracite as a binder for sintering machines. Furthermore, when producing char for binders, the amount of COG and tar produced as by-products in the high-temperature carbonization furnace is increased and can be used as a blast furnace reducing agent, thus reducing the fuel ratio (reducing agent ratio) of the blast furnace, and it can also be used as oil when using COM.

[0019] In summary, by pre-treating coal in a high-temperature carbonization furnace, regardless of its caking properties, and extracting the three phases of fuel—solid, liquid, and gas—and using each phase appropriately, the total amount of fossil fuels used in the entire ironmaking facility, including blast furnaces, sintering machines, and coke ovens, can be reduced. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 shows an embodiment of this design, illustrating the overall flow diagram of supplying char to the blast furnace from the tuyeres at the bottom of the furnace. [Figure 2] Figure 2 shows the overall flow diagram of the reducing agent and setting agent before applying this embodiment. [Figure 3] Figure 3 shows a flow chart in which this embodiment is applied only to the blast furnace tuyere injection line in Figure 2. [Figure 4] Figure 4 shows a flow chart in which this embodiment is applied to the sintering machine binder, in addition to the components shown in Figure 3. [Figure 5] Figure 5 shows a comparison of the carbon material processing flow diagrams for the conventional PCI method and this embodiment. [Figure 6] Figure 6 shows the nitrogen / chlorine balance diagram according to the mixing ratio of coal and chlorine-containing fuel. [Figure 7] Figure 7 shows an embodiment of this design, illustrating the overall flow diagram of char supply to the blast furnace from the furnace top and lower tuyeres. [Figure 8] Figure 8 shows a model of unreacted nuclei when chlorine-containing waste is formed into spherical briquettes. [Figure 9] Figure 9 is Table 1, which shows the components of the RDF from Non-Patent Document 1. [Figure 10] Figure 10 is Table 2, which shows the industrial analysis values, elemental analysis values, and LCV for coking coal, LV coal, and HV coal, respectively. [Figure 11] Figure 11 is Table 3, which shows a comparison of the estimated carbon consumption results for the case using LV coal in Figure 2 and the case using LV coal or HV coal in Figure 3, where this embodiment is applied to the blast furnace tuyere injection line. [Figure 12] Figure 12 is Table 4, which shows the case in Figure 4 where LV carbon or HV carbon is used, in which this embodiment is also applied to the binder of the sintering machine. [Figure 13] Figure 13 is Table 5, which shows the case in Figure 1, which serves as a model case for this embodiment, where LV coal or HV coal is used. [Figure 14] Figure 14 is Table 6, which shows a comparison of carbon consumption in the case of Figure 1 and the case of Figure 7 when using HV coal as shown in Table 2 (Figure 10). [Modes for carrying out the invention]

[0021] With reference to the attached drawings, several exemplary embodiments are described below. It should be noted that the drawings illustrate typical equipment related to this embodiment, but do not provide detailed information including ancillary equipment or combustion fuel.

[0022] Throughout the following description and the attached claims, each term is used in a sense consistent with the definitions well known to those skilled in the art, except for some terms which have the following meanings: “Lower Furnace” means the fusion zone and the area below it, or the region at temperatures above 1200-1300°C where permeability deteriorates due to ore softening (depending on the reduction rate of the ore). “Partial Combustion” means combustion that does not result in complete combustion. “Primary Combustion” means the reaction C + 0.5·O2 = CO, and the partial combustion that produces CO, H2, and H2S from coke and tuyere-injected fuel, and the heat generated by primary combustion is called “primary combustion heat.” “Fuel Ratio” and “Reducing Agent Ratio” are both the total weight (kg / tp) of coke and tuyere-injected fuel (also called tuyere-injected reducing agent) required to produce 1 ton of pig iron. In principle, the two are synonymous, but the term reducing agent is often used to distinguish it from combustion fuel, so both are used depending on the context. Unless otherwise specified, the fuel ratio does not include reducing gases (CO, H2) injected from the tuyeres during top gas circulation. "Low-temperature pyrolysis," "medium-temperature pyrolysis," and "high-temperature pyrolysis" are classifications of relatively slow pyrolysis methods based on the pyrolysis temperature, and are not precisely defined even among those skilled in the art. However, here, low-temperature pyrolysis is defined as the temperature range for semi-carbonization (torrefaction), medium-temperature pyrolysis as the temperature range for general biochar production (VM = approximately 5-25%), and high-temperature pyrolysis as the temperature range for coke and biocoke production (residual VM = approximately a few percent), with these defined as "200-300°C," "400-700°C," and "900-1300°C," respectively.

[0023] The PCI (Percutaneous Coal Injection) method, which involves blowing pulverized coal into a blast furnace, is a method of injecting pulverized coal through the blast furnace tuyeres. Its purpose is to replace expensive and valuable coke (referring to the lump coke charged from the top of the blast furnace) with inexpensive, non-coking coal, and it utilizes finely pulverized coal (VM = 10-40%) to improve combustion efficiency. Therefore, even if anthracite or pulverized coke (the yield loss from lump coke) is used in special circumstances, it is clear that there is no rationale for finely pulverizing lump coke (the main product of the coke oven) and blowing it in through the tuyeres.

[0024] The operating method disclosed below is conceived contrary to the common sense of those skilled in the art, and in general terms, it involves not directly injecting coal from the blast furnace tuyeres, but rather deliberately feeding charred material that has undergone high-temperature carbonization treatment into the furnace, along with gas and liquid fuel produced as by-products in the gas purification equipment (ancillary equipment such as high-temperature carbonization furnaces).

[0025] Specifically, first, coal or solid fuel substitutes outside the range of blast furnace coke production are subjected to carbonization at temperatures of up to 900°C or higher to separate them into solid fuel (char and ash) and other crude gas. Next, the crude gas is separated in a gas purification facility into gaseous fuel (COG), liquid fuel (tar, etc.), and residual liquid (mainly water, equivalent to ammonia water in coal carbonization and wood vinegar in biomass carbonization). In other words, solid fuel (char), liquid fuel (tar, etc.), and gaseous fuel (COG) are extracted from the charging raw materials through the carbonization process and the separation of combustible materials.

[0026] Furthermore, for solid fuels, a portion or all of them are coarsely ground in a coarse grinder to obtain coarse char, which is used as a binder for sintered ore. A portion or all of the solid fuel, which has been finely ground so that the proportion of particles with a particle size of 0.1 mm or less is 70% or more, is then injected from the blast furnace tuyeres at the bottom of the furnace. For gaseous fuels, a synthesis gas (reducing gas) mainly composed of CO and H2 is produced (reformed) from a portion or all of them and injected into the blast furnace body at a temperature of 800°C or higher. For liquid fuels, a portion or all of them are injected into the furnace from the blast furnace tuyeres at the bottom of the furnace.

[0027] The present invention will be described in more detail below.

[0028] The coke (lump coke) charged into a blast furnace plays a crucial role in maintaining permeability and fluid permeability at the bottom of the furnace, requiring high-temperature strength, particle size, and low reactivity. Therefore, raw coal, blended with coking agents and vapor vaporizers, is carbonized in a coke oven at 1000-1300°C, and only lump coke of the required particle size is ultimately charged into the blast furnace. Lump coke also serves as a reducing agent (direct reduction or gas reduction) and a heat source (source of thermal energy supply through combustion), and historically, far more coke than necessary to ensure permeability and fluid permeability at the bottom of the furnace has been charged.

[0029] In contrast, PCI (Percutaneous Coronary Injection) is a technology that transfers the roles of coke as a reducing agent and heat source to inexpensive, non-caking coal. To increase the combustion rate, the coal is finely ground so that 70-80% or more of the particles are 200 mesh (74 μm) or smaller, thereby increasing the specific surface area. Coal grades have also been studied, from HV coal (high VM coal) to LV coal (low VM coal), and there has been a shift from HV coal, which prioritizes combustion rate, to LV coal, which has a higher calorific value as the PC ratio increases. In recent years, research has been conducted worldwide on mixing biomass-derived chars into PC as a CO2 reduction measure, but this is an extension of conventional PCI technology.

[0030] The present inventor has devised a method for reducing CO2 emissions in the blast furnace method (Patent Document 1). According to the CO2 reduction method for the blast furnace method described in Patent Document 1, the blast furnace tuyeres injected fuel has a high primary combustion heat and a high thermal decomposition heat (C i H j O k It is desirable that the amount of heat required to decompose coal into i × C + 0.5j × H2 + 0.5k × O2 is small. The heat of thermal decomposition of coal is also the heat of thermal decomposition of VM (volatile matter), so LV coal is desirable for blast furnace tuyeres injected as fuel. This is a common issue in conventional PCI methods as well.

[0031] To address the difficulty in using HV coal, this invention proposes a method in which coal with VM ≥ 6% is not directly supplied to the bottom of the blast furnace, but is instead carbonized into solid fuel (char) with VM < 5% (preferably ≤ 1%) in a high-temperature carbonization furnace with a maximum temperature of 900°C or higher, and then supplied to the blast furnace by means of gaseous fuel (COG) or liquid fuel (tar, etc.) produced as by-products in a gas purification facility attached to the high-temperature carbonization furnace, using the most suitable means for each fuel.

[0032] Here, a high-temperature carbonization furnace is a facility that can secure a carbonization temperature of 900°C or higher with a structure that prevents outside air from entering, and is equipped with gas purification equipment. For logistical reasons, it is desirable to install it near the blast furnace. There are no restrictions on its form; equipment such as a vertical coke oven is also acceptable, and many conventional coke ovens can be reused, including CDQ (coke dry quenching) equipment. When producing coke or char, separation of the carbonization furnace and cooling equipment is necessary, but the gas purification equipment can be shared. The reason for specifying a carbonization temperature of 900°C or higher is that there is a correlation between the carbonization temperature of coal and gasification (thermal decomposition), and gasification, including H2, is completed at around 900°C.

[0033] Figure 5 compares the conventional PCI method with this embodiment.

[0034] In conventional PCI (Percutaneous Coronation) methods, attempts have been made to use biochar (wood-based biochar, also called charcoal) with a VM (Voltage Value) of approximately 6-25% mixed with coal as a CO2 reduction method utilizing biomass. Due to the properties of biomass (low bulk density, high moisture content, low yield of carbonized material, etc.), it is generally carbonized in a medium-temperature carbonization furnace 14 at 400-600°C at a biomass collection point and then transported and delivered to the end-user (steel mill). Furthermore, because coal contains moisture, it is first dried to a moisture content of 1% or less in a dryer 13, then finely pulverized in a pulverizer 7, and then blown into the furnace as PCI from a tuyer (not shown) of the blast furnace 1.

[0035] In this embodiment, coal and other materials brought to the steelworks are separated in a high-temperature carbonization furnace 2 into solid fuel (char), liquid fuel (tar, etc.), gaseous fuel (COG), and water-based residue (corresponding to ammonia water in coal carbonization and wood vinegar in biomass carbonization), and only the fuel, excluding the residue, is supplied to the blast furnace 1. The char is finely pulverized in a pulverizer 7 as needed so that the proportion of particles smaller than 0.1 mm is 70% or more, and then blown into the blast furnace tuyeres at the bottom of the blast furnace. The COG is partially combusted or gas-reformed in a reforming / heating furnace (hot blast furnace) 5 using a medium gas (H2O, CO2) to produce a CO and H2-based reducing gas (synthesis gas) and then blown into the blast furnace 1. Tar and other materials are blown into the furnace from blast furnace tuyeres at the bottom of the blast furnace. It is desirable that the solid fuel (char) be finely pulverized by the blast furnace injection pulverizer 7.

[0036] Since the vapor vapor (VM) in the coal is separated beforehand and char is injected from the blast furnace tuyeres, the endothermic reaction due to the thermal decomposition of coal (including the heat of heat generation and thermal decomposition of the residual liquid removed in the high-temperature carbonization furnace 2) is eliminated, and the calorific value (kJ / kg) increases. Therefore, the required fuel ratio (kg / t) and oxygen ratio (Nm³) per ton of molten iron can be increased. 3 This can reduce the amount of / t.

[0037] The char is finely ground in a pulverizer 7 to increase its specific surface area (∝ combustion rate) and then blown in through a dedicated blowing lance at the lower tuyer of the furnace. The Hardgrove Grindability Index (HGI; a higher number indicates easier grinding) increases with the carbonization temperature and degree of carbonization (Non-patent documents 5 and 6), so HV char and biomass-based fuels can also be easily finely ground by carbonization, reducing grinding energy.

[0038] Since COG is recovered at room temperature, when it is injected into the blast furnace as a reducing gas, it is undesirable if it is not preheated to a temperature above the injection site temperature, as it will become a cooling source and cool the charges inside the furnace. Even when injecting it into the shaft, it is desirable to heat it to above 800°C, but the gas contains hydrocarbon gases such as CH4, and heating it to above 800°C will cause soot to be generated due to the cracking phenomenon (CH4 = C + 2H2). Therefore, partial combustion of hydrocarbons (Cn H m +0.5n·O2=n·CO+0.5m·H2), or using a medium gas (H2O, CO2) to perform gas reforming into a reducing gas (synthesis gas) mainly composed of CO and H2 in a high-temperature atmosphere, and then blowing the resulting gas into a blast furnace is desirable. By blowing the reducing gas to an appropriate location at an appropriate temperature, the gas reduction rate can be increased and the fuel ratio (reducing agent ratio) can be reduced (Patent Document 1).

[0039] Tar and the like are utilized as a reducing agent by being blown into the furnace from the tuyere as in the conventional heavy oil blowing method, as a form of chemical recycling. It is desirable to blow them from the lower furnace tuyere using a dedicated blowing lance similar to the blowing lance for heavy oil.

[0040] The effects of the above embodiments will be explained with reference to the outside of the "ironworks boundary" shown in FIG. 5. In the conventional PCI route, biochar is generally produced in a medium-temperature carbonization furnace 11 installed at a biomass accumulation site. Since the yield and VM of biochar are inversely correlated with the carbonization temperature, the yield of low-VM biochar suitable for PCI is as low as 20 to 30%, and by-product gas, tar and the like are difficult to utilize other than for the combustion heat of the carbonization furnace, so the net energy yield of the carbonization furnace (=latent heat of recovered fuel / (latent heat of charged raw material + externally input heat amount)) is low.

[0041] In the present embodiment, the high-temperature carbonization furnace 2 is installed inside the ironworks, and COG, tar and the like derived from VM can be utilized within the plant, so a high-VM fuel can be used as the charged raw material without problem. Accordingly, fuel production facilities that prioritize energy yield, such as a low-temperature carbonization furnace (semi-carbonization furnace) 15 at 200 to 300°C and a solidification facility 16 at less than 200°C, can be adopted at the biomass accumulation site.

[0042] Figures 2 (an example of non-application of this embodiment; Patent Document 1) and 3 (an example of application of this embodiment) summarize the flow within the steelworks boundary shown in Figure 5 into a pig ironmaking process flow that includes the coke oven 3 and sintering machine 9. In both examples, gas reforming is assumed to be a partial combustion method using oxygen in the hot blast furnace (reformation / heating furnace) 5. The flow allows for the circulation of top gas from which CO2 has been removed in the CO2 separation device 4, according to the amount of reducing gas required in the blast furnace 1, and also allows for the adjustment of the amount of reducing gas produced and heated in the hot blast furnace 5 by supplying CH4 from an external source. In both examples, the flow uses anthracite coal to supplement the amount of powdered coke that is insufficient as a binder for the sintered ore produced in the sintering machine 9. Note that although there is a screen indication in the flow, it is used broadly to mean a classification device 10, and it may be a literal screen type, or it may be a wind classification or fluidized bed type (common to other figures as well).

[0043] The amount of binder used per ton of pig iron is calculated as follows: Ore ratio: OR (kg / tp; amount of ore charged per ton of pig iron), Sintered ore ratio: SR (%; percentage of sintered ore in the charged ore), Binder ratio: C str (kg / ts; amount of agglomerate per ton of sintered ore) = OR × SR × C str This is the result. On the other hand, the amount of powdered coke supplied is calculated as follows: coke ratio: CR (kg / tp; amount of coke per ton of molten iron), lump coke ratio: R cc (%; yield of lump coke by weight relative to raw coal), pulverized coke ratio: R fc (%; Weight yield of powdered coke relative to raw coal) = CR × R fc / R cc Therefore, the amount of coking agent (powdered coke) needed per ton of pig iron is: L c (kg / tp) is, L c =OR × SR × C str -CR×R fc / R cc (1) Therefore, the shortfall is generally covered by anthracite coal.

[0044] Furthermore, it is clear that the shortage increases if the first term on the right-hand side of equation (1) increases or the second term decreases (and vice versa). Because self-fluxing sintered ore (sintered ore containing auxiliary raw materials for adjusting slag basicity) is highly reactive in the blast furnace, SR (∝ first term) is on the rise, coupled with the depletion of high-quality lump ore. CR (∝ second term) is also decreasing due to the increase in PC ratio and the trend towards CO2 reduction, and the shortage of coking agent (powdered coke) is intensifying. According to the method of Patent Document 1, CR can be reduced to less than 1 / 5 of that in the conventional blast furnace method, thus making the powdered coke shortage critical.

[0045] On the other hand, there have been conventional challenges in using anthracite in sintering machines, and its use has been limited. Another feature of this embodiment is that, instead of supplementing the lack of agglutinant with anthracite, it is supplemented with char produced by high-temperature carbonization of coal, etc., and at the same time, liquid fuel (tar, etc.) and gaseous fuel (COG) produced as by-products of carbonization are recovered, and the COG is gas-reformed into a reduced gas (synthesis gas) mainly composed of CO and H2 using partial combustion or a medium gas (H2O, CO2) before being injected into the blast furnace body, while the tar, etc. is injected into the furnace from the tuyeres at the bottom of the blast furnace.

[0046] The raw materials (coal, coal substitutes, etc.), equipment (high-temperature carbonization furnaces, gas purification equipment, etc.), and operating methods (carbonization temperature, carbonization time, etc.) for this process can be standardized and shared with blast furnace blown char production, which allows for synergistic improvements in equipment efficiency and operational efficiency. The integrated ironmaking process flow is shown in Figure 4.

[0047] In Figure 3, "anthracite" and "LV coal" are combined into "general coal / coal substitute fuel" in Figure 4, and the entire amount is processed in the high-temperature carbonization furnace 2. A portion of the carbonized solid fuel (char) is used as coarse char powder as a sintering ore binder, and the remainder is injected into the blast furnace as fine char powder.

[0048] The supply destinations for the liquid fuel (tar, etc.) and gaseous fuel (COG) by-products in the high-temperature carbonization furnace 2 in Figure 4 are the same as in Figure 3, but the supply volume increases by the amount added to the production of the sintered ore binder used in the sintering machine 9 in the high-temperature carbonization furnace 2. In other words, conventionally, even when anthracite was used as the binder, its latent heat of vapor deposition (VM) could hardly be effectively utilized, but in this embodiment, it can be effectively recovered and utilized as liquid fuel and gaseous fuel.

[0049] The burning time of the binder is roughly proportional to the square of the particle size and is a factor that determines the burning pattern (burning temperature and holding time in the sintering bed) which affects the sintered ore grade and yield, so a narrow particle size range is desirable. Therefore, it is desirable to control the particle size range to, for example, 2 to 3 mm, but it is difficult to finely classify materials with moisture (the sieve mesh tends to clog), and even when using powdered coke, a considerable amount of material smaller than 1 mm and larger than 5 mm has been included. The char discharged from the high-temperature carbonization furnace is dry-cooled to about 150°C in a CDQ (Coke Dry Quencher) (not shown) for the purpose of sensible heat recovery, similar to coke, and then coarsely pulverized, so it is completely dry and easy to screen and air classify. Furthermore, for example, material smaller than 2 mm that passes through the sieve does not result in a loss of yield and can be supplied to the blast furnace injection pulverizer 7, so the particle size range sent to the sintering machine 9 can be controlled to a narrow range. The precise particle size range is determined by factors such as the exhaust gas suction speed and FFS (Flame Front Speed) of the sintering machine, but it is desirable to use coarse powder with a particle size of at least 1 mm to 6 mm as a binder for the sintered ore.

[0050] Controlling the particle size of the binder is also effective for pulverized coke. In Figure 4, in parallel with the line supplying to the mixer 8, a line for charging pulverized coke with particles smaller than 3 mm or larger than 5 mm into the high-temperature carbonization furnace 2 is indicated with an asterisk (*).

[0051] The method for injecting the fine char into the furnace body shown in Figures 3 and 4 assumes pneumatic transport, similar to the conventional PCI method. Since the fine char produced by high-temperature carbonization contains almost no vapor vapor (VM), the risk of coal dust explosion is low even with pneumatic transport. However, in the case of pneumatic or nitrogen transport, N2 will enter the furnace, and considering compatibility with CO2 separation (difficult to separate N2) and the top gas circulation system (easy to concentrate N2), it is desirable to use a reducing gas (such as the top gas after decarbonation) as the pneumatic gas. Since it is a pressurized system that injects into the pressurized blast furnace, external air is less likely to enter the injection system, making it possible to use preheated pneumatic gas, and by increasing the sensible heat of the injected char and gas, the fuel and oxygen consumption can be reduced. As a means of increasing the sensible heat of the injected char, it is also possible to indirectly heat the transport piping from outside the pneumatic system using electric heaters or steam.

[0052] Methods other than pneumatic injection can be applied to the injection of fine char into the blast furnace tuyeres. When liquid fuel (such as tar) is injected simultaneously, using COM (Coal Oil Mixture) is the most rational approach, and the process flow is shown in Figure 1.

[0053] COM12 is a facility that transports finely powdered solid fuel by turning it into a slurry using oil such as heavy oil or tar as the transport medium. In Figure 1, finely powdered char and liquid fuel such as tar are pre-mixed and injected into the blast furnace as COM fuel. The slurry concentration (the proportion of solids in the total transport weight) is typically limited to around 50%, so when bituminous coal is used as the raw material, auxiliary liquid fuel (reducing agent) such as heavy oil is added to prevent the slurry concentration from becoming too high. Furthermore, since the amount of finely powdered char can be reduced in proportion to the amount of heavy oil added, the overall energy efficiency and CO2 emissions do not deteriorate.

[0054] Incidentally, the yield of solid and liquid fuels in a high-temperature carbonization furnace (the ratio of recovered material to the weight of raw materials such as coal) varies depending on the material such as coal and the vapor mass (VM). Generally, as VM increases, the yield of solid fuel decreases and the yield of liquid fuel increases. When wood-based biomass fuel is carbonized at 1000°C, the yield is roughly 20% solid, 55% liquid, and 25% gas (Non-Patent Literature 2). Subtracting the yield of wood vinegar, which cannot be used as fuel, from the 55% liquid (Non-Patent Literature 3), the ratio of solid fuel:liquid fuel:gaseous fuel becomes 20%:25%:25%, resulting in a slurry concentration of about 44% (<50%). When waste plastics are carbonized at high temperature, the ratio of solid fuel:liquid fuel:gaseous fuel becomes 1:2:2 (Non-Patent Literature 4), so the slurry concentration is about 33% (<50%). In other words, depending on the type of coal substitute fuel and its blending ratio, auxiliary liquid fuels such as heavy oil may not be necessary. Even if alternative fuels to coal are not used, CO2-free auxiliary liquid fuels such as biomaster or e-fuel can be used instead of heavy oil.

[0055] By applying COM, the two control systems, the pneumatic and liquid systems, can be integrated into one, and the tuyere injection lance can also be integrated. Furthermore, the heat of vaporization of the liquid can be used to protect the lance from the harsh temperatures inside the furnace. In addition, although the liquid injection temperature of heavy oil-based COM is usually below 100°C, it is easy to indirectly heat the liquid fuel to near its boiling point (for example, 200°C, as both heavy oil and tar have a wide range of boiling points) before tuyere injection, and by increasing the sensible heat of the solid and liquid fuels, the fuel ratio (kg / tp) and oxygen ratio (Nm) can be improved. 3 This reduces the amount of fuel ( / tp). Furthermore, heating promotes vaporization of the liquid fuel, thus improving the COM combustion rate.

[0056] Having described the features of this embodiment, primarily focusing on the process, we will now discuss the options for coal-alternative fuels and their characteristics in this embodiment.

[0057] In this embodiment, as a coal substitute fuel, biomass fuel (including semi-carbonized fuel) can be used, as well as waste solid fuels (RDF, RPF, etc.) containing a certain amount of impurities. When using waste, impurities and non-combustible materials contained in the waste are a challenge, and pre-sorting and pre-treatment are important, as with other methods of using waste solid fuel. However, for the following reasons, this embodiment makes it easier to use waste compared to other methods.

[0058] First, the method of generating steam power by burning waste has the problem that chlorides in the waste corrode metal walls, including boiler walls, and generate large amounts of dioxins. This is the reason for the low power generation efficiency of incinerators, and even with power generation using RDF (Refuse Derived Fuel) where the chlorine concentration is controlled to around 1% or less, it leads to increased burden of countermeasures and limitations on the amount of fuel charged, which undermines the cost advantage (economic viability) of waste-to-energy and hinders its widespread adoption.

[0059] Next, there is a method of chemical recycling similar to this embodiment, in which waste plastics are mixed with raw coal and charged into a coke oven (Patent Document 2, Non-Patent Document 4). The advantage of this method is that, under the high-temperature reducing atmosphere of the coke oven, more than 90% of the chlorine contained in the waste plastics is transferred into the gas as HCl, and when cooled with ammonia-containing water produced from nitrogen derived from raw coal, it becomes ammonium chloride (NH4Cl) and is rendered harmless. However, despite being able to render 5.3 kg / t-coal (150 mol / t-coal) of chlorine per ton of charged coal harmless, the coke strength begins to decrease for reasons other than chlorine when only 1-2 wt% of waste plastics are charged (approximately 0.2-0.4 kg / t-coal in terms of chlorine), so the effective proportion of waste plastics to be charged is limited to a few wt%, which is a drawback. Furthermore, this method is limited to waste plastics as the target of coal alternative fuel, and does not target biomass fuels or waste other than waste plastics.

[0060] In this embodiment, the use of a high-temperature carbonization furnace is the same as in Patent Document 2, and the ability to detoxify chlorine in the charged raw materials is the same. However, since coarse or fine char is produced instead of coke, there are no raw material constraints required for coke strength, so the proportion of waste plastic charged can be increased up to the balance limit with ammonia derived from coal (5.3 kg-Cl / t in the case of raw coal). According to Patent Document 2, it is possible to increase the amount of waste plastic with 2 wt% chlorine to 26 wt% relative to the raw coal, and since the N and Cl in coal and the N in waste plastic are 0.045 wt%, 1.59 wt%, and 0.4 wt%, respectively, the weight ratio of nitrogen (N) to chlorine (Cl) in the charged raw materials to the high-temperature carbonization furnace (N / Cl) is 3.0. Here, if the waste plastic is changed to RDF while keeping the same coal, for example, the RDF in Non-Patent Document 1 will contain the components shown in Table 1 in Figure 9. As shown in Table 1, although the chlorine content is relatively high (>1 wt%), it is possible to charge up to 37 wt% of RDF to achieve an N / Cl ratio of 3.0. Note that the RDF carbide in Table 1 (Figure 9) is obtained by dry distillation of RDF at 500°C.

[0061] The above describes charging restrictions to detoxify hydrogen chloride generated from chlorine in the charged raw materials with ammonia generated from nitrogen, also in the charged raw materials. However, in this embodiment, the RDF charging ratio can be further increased by effectively utilizing chlorine in the furnace before detoxifying it. Before explaining this point, we will first describe impurities in the waste in relation to it.

[0062] RDF, a solid fuel derived from general waste, has quality issues because it contains impurities other than chlorine, such as heavy metals and alkalis. When RDF is used as fuel for thermal power generation, it causes problems similar to chlorine, such as deposits on boiler walls and material corrosion, and increases the cost of treating exhaust gases and fly ash.

[0063] When using RDF as fuel injected into blast furnace tuyeres, there are issues related to the properties of the RDF (industrial analysis values; FC, VM, Ash, and moisture content), in addition to issues related to the quality of the pig iron and the quality of the RDF that affect blast furnace operation. For example, the RDF shown in Figure 9 (Table 1) (Non-Patent Literature 1) has too high a VM, and the heat of its decomposition cools the lower part of the furnace, making it unsuitable as fuel injected into blast furnace tuyeres. The RDF carbide shown in Figure 9 (Table 1) is obtained by dry distillation of RDF at 500°C (Non-Patent Literature 1), but because the carbide yield is low (about 30%), the Ash content of the carbide is concentrated / increased to 43.3% dry, making it unsuitable as fuel injected into tuyeres.

[0064] Incidentally, it is well known that if chlorine is present in the raw materials charged to a high-temperature carbonization furnace, chlorine (Cl2) and hydrogen chloride (HCl) are generated by thermal decomposition. It is also well known that high-temperature chlorine-based gases chlorinate many oxides and metals to produce chlorides with high vapor pressure, and this has been used for heavy metal recovery as the chlorination roasting method (chlorination volatilization method).

[0065] In this embodiment, the high-temperature reducing atmosphere of the high-temperature carbonization furnace and the chlorine brought in by the charged raw materials such as waste are actively utilized to perform reductive chlorination roasting of the charged material in parallel with carbonization. This improves the quality of the carbonized material and removes ash by chlorinating and volatilizing heavy metals and alkalis in the ash.

[0066] The chlorination reaction of metal element M to an oxide is expressed by the following equation. MO a +b × Cl2 = MCl 2b +a / 2 × O2ΔG 0 0 < 0 (2) The standard free energy change (ΔG) is a function of temperature. 0 ) is ΔG 0 The reaction will not proceed unless it is <0, but the chloride reaction is ΔG 0 It is easy for the value to become <0. Regarding chlorine volatilization, its use has been considered for the treatment of heavy metals in the incinerated ash of municipal solid waste, but these were based on the assumption of an oxidizing atmosphere, so it was said that the heavy metals that could be volatilized were limited. However, the inside of a high-temperature carbonization furnace is an atmosphere in which CO and H2 gases are generated and carbides (C) are produced, and the following reaction proceeds in parallel. C + 1 / 2 × O2 = CO ΔG 0 C <0 (3) CO + 1 / 2 × O2 = CO2ΔG 0 CO <0 (4) H2 + 1 / 2 × O2 = H2O ΔG 0 H2 <0 (5)

[0067] Multiply equations (3), (4), and (5) by a and add them to equation (2): MO a +a × C + b × Cl² = MCl 2b +a×CO ΔG 0 0+ΔG 0 C (6) MO a +a×CO+b×Cl2=MCl 2b +a×CO2ΔG 0 0+ΔG 0 CO (7) MO a +a×H2+b×Cl2=MCl 2b +a×H2O ΔG 0 0+ΔG 0 H2 (8) Therefore, at 300-1200°C, -500 < ΔG 0 C ,ΔG 0 CO ,ΔG 0 H2 Since the free energy change is <-300 kJ / mol, the free energy changes in equations (6), (7), and (8) are all significantly lower than those in equation (2), so the reduction chlorination reaction proceeds more easily in terms of free energy. Note that chlorine is consumed in the reaction with hydrogen to produce hydrogen chloride (H2 + Cl2 = 2HCl), so it is important to check whether the free energy change is lower than the standard free energy change for this reaction.

[0068] Furthermore, in the carbonization chamber of a vertical coke oven, for example, the heating of the charge progresses from the furnace wall towards the center. This allows the chlorine-containing gas and the charge to come into contact over a wide temperature range. As a result, the reduction and chlorination reaction proceeds sequentially during the heating process, and chlorides with high vapor pressure at low temperatures volatilize sequentially. Therefore, a variety of oxides can be reduced and volatilized until the completion of carbonization at over 900°C. However, since the temperature of the chlorine-generating gas is lower than the chlorine volatilization reaction temperature, depending on the width from the furnace wall to the center of the coke oven, the generated chlorine gas may flow through the lower-temperature charge and rise, potentially significantly reducing the efficiency of the chlorine volatilization reaction. However, the efficiency of the chlorine volatilization reaction can be increased by pre-treating the raw materials, such as by molding some or all of the chlorine-containing charge (into briquettes or injection-molded products, etc.) before charging it into a high-temperature carbonization furnace (such as a coke oven).

[0069] Figure 8 shows an unreacted nucleus model assuming a spherical briquette. During the heating process after charging, a temperature gradient is created in the thickness direction (radial direction) within the briquette. When chlorine gas generated in the low-temperature part of the briquette (chlorine gas generation surface in Figure 8; radius R1) is exhausted from the briquette surface (high temperature close to the furnace temperature), it passes through the chlorine volatilization temperature surface of impurity A (impurity A reaction surface in Figure 8; radius R2), and thus impurity A on this surface is removed by chlorine volatilization. The chlorine gas reaction surface and the impurity A reaction surface start near the briquette surface immediately after charging and move inward as the carbonization time progresses (R1 and R2 approach zero), so chlorine volatilization proceeds in many regions within the sphere. Other impurities also have corresponding volatilization temperatures, but chlorine gas always passes through that temperature range (R2, different from A), so it can be removed by chlorine volatilization at that time. In other words, impurities with a chlorine volatilization temperature lower than the carbonization temperature can be efficiently removed by briquetting. Furthermore, the excess chlorine gas exhausted from the briquettes is given the opportunity to react with unreacted charge materials in the flow path, and the longer the flow path, such as in a vertical coke oven, the easier it is to improve the reaction efficiency.

[0070] As can be seen in Figure 8, if R1 and R2 are far apart, impurities inside R2 cannot be volatilized by the chlorine in the briquette once R1 reaches the center of the furnace. In other words, the temperature gradient inside the briquette is important, and not only the chlorine concentration inside the briquette, but also the moisture and oil content, their latent heat of gasification (cooling source) promotes a steeper temperature gradient, contributing to improved reaction efficiency. Furthermore, since the gas flow is upward in a coke oven, a method of charging briquettes with high chlorine content and moisture / oil content in the lower layer and inserting briquettes or powdered charge materials with low chlorine content and moisture / oil content in the upper layer delays the timing of chlorine gas generation in the lower layer and increases the heating rate of the upper layer, thus allowing the chlorine volatilization reaction in the upper layer to proceed, which is effective in improving the efficiency of impurity removal and the effective utilization of chlorine gas.

[0071] The above explanation uses briquettes as an example, but injection-molded products such as RDF or RPF, or even pellets, are also acceptable. While a round shape is ideal, cylindrical or pillow-shaped forms are also acceptable. Although vertical coke has higher reaction efficiency, horizontal coke can also be effectively utilized by forming briquettes or similar products.

[0072] A detailed investigation of the free energy changes in chlorination reactions and the vapor pressure of chlorides for the main components contained in RDF revealed that heavy metals (Zn, Pb, Cu) and alkali metals (Na, K), which affect blast furnace conditions and pig iron quality, can be volatilized and removed. Furthermore, it was found that Fe, Mn, Mg, and Ca are also volatilized and removed, which has the advantage of reducing ash (decalcification). Conversely, while Si, Al, and Cr can be volatilized as metals, it was found that as oxides (SiO2, Al2O3, Cr2O3), hydrogen chloride is preferentially produced, resulting in stable compounds. Therefore, these are suitable as refractory components for high-temperature carbonization furnaces.

[0073] Next, we will explain in detail, using Figure 6, how to determine the appropriate amount of chlorine when coal and RDF are mixed and charged into a high-temperature carbonization furnace. The horizontal axis of the figure shows the mixing ratio X of the two types of charged raw materials, for example, X=0 is 100% coal and X=1 is 100% RDF. The vertical axis shows the ratio (wt%) of N and Cl components in the charged raw materials, but for N, it is expressed on a scale multiplied by the conversion ratio to NH3 of 1 / k. K depends on the type of fuel, so it needs to be checked for each fuel, but in the case of a mixture of coal and waste plastic, K=3 as mentioned above. The ratio of N (wt%) in the mixed fuel at mixing ratio X is Y. N (X), Cl ratio (wt%) is Y Cl If we let (X), it can be expressed by the following equation, as shown by the dotted and solid lines in Figure 6. Y N (X) = (N1 - N0)·X + N0(9) Y Cl (X) = (Cl1 - Cl0)·X + Cl0(10) N0: Percentage of N in coal (wt%) N1: Percentage of N in RDF (wt%) Cl0: Percentage of Cl in coal (wt%) Cl1: Percentage of Cl in RDF (wt%)

[0074] The amount of Cl consumed to chlorinate impurities in RDF and coal is Cl v If (X), then chlorine Y in the fuel mixture. Cl (X) is Y after the chlorination reaction. Cl (X)-Cl v (X) Y Cl (X)-Cl v At a mixing ratio of (X) < 0, the amount of chlorine is insufficient for the target to be chlorinated, Y Cl (X)-Cl v It is desirable that (X) ≥ 0. Conversely, Y Cl (X)-Cl v (X) If ≥ 0, HCl is produced, so the conditions under which neutralization is possible by NH3 in ammonia water [Y N (X)≧Y Cl (X)-Cl v (X) must be satisfied.

[0075] In RDF100% operation, Y Cl (1)-Clv(1)=Cl1-Clv(1). Therefore, it can be seen that we should use an RDF with a Cl ratio that satisfies the following equation (Equation 11). N1 / k≧Cl1-Clv(1)≧0 ⇔ N1 / k+Clv(1)≧Cl1≧Clv(1) (11) For example, the Ash in the RDF shown in Figure 9 (Table 1) contains 60 wt% SiO2 and Al2O3 (inferred by the inventors of this application from Non-Patent Document 1), and it is possible to volatilize (decalcify) the remaining 40 wt% by reducing chloride, and calculations based on the Ash components suggest that Cl v (1) = 5.5 wt%. The current Cl content in RDF is 1.2 wt%, and even at a mixing ratio of 1 (100% RDF), there is insufficient chlorine for the chlorination reaction, so the chlorine concentration can be increased to 5.5% or more.

[0076] In conventional carbonization furnaces, if the chlorination reaction is not considered, then Cl v (X)=0 (Cl1<3), and X in Figure 6 v0 The mixing ratio becomes the RDF mixing limit, and in the case of Figure 9 (Table 1), X v0 =0.37 (Cl1=1.2) This is the limit point explained (X v0 *Cl1 = 0.44%). This embodiment allows for the active use of chlorine in the chlorine volatilization of impurities, thereby increasing the proportion of chlorine-containing waste to 100% and further increasing the chlorine concentration in the waste. Note that the chlorine concentration Cl1 in the waste and the amount of chlorine added from the waste (Cl1·X) are also relevant. vo However, even without going as far as the above explanation, it is clear that the effects of the present invention can be enjoyed to a considerable extent when the values ​​are increased from conventional standards or limits, and the chlorine concentration Cl1 (wt% dry) in the waste charged into the high-temperature carbonization furnace and the waste charging ratio X vo (wt%_dry) is at least Cl1≧3% or Cl1·X vo This applies if any of the following conditions are met: ≥0.5%.

[0077] Furthermore, understanding Clv(X) is important, but it is possible to determine this before operation by analyzing Ash, and it can also be corrected during operation based on the NH3 concentration in the ammonia water. Also, YN (X=Y Cl Based on the properties of (X)-Clv(X), the amount of HCl generated can be adjusted by changing the mixing ratio. Therefore, by knowing the NH3 and NH4Cl concentrations in the ammonia water, it is possible to determine the margin for adjustment in the mixing ratio before making any changes.

[0078] Now, let's reconsider the ash (SiO2, Al2O3) remaining in the char produced from RDF in a high-temperature carbonization furnace. In this embodiment, 40% of the ash in the RDF shown in Figure 9 (Table 1) can be reduced and volatilized (decalcified), reducing the ash content from 11.5% to 6.9%. However, because the FC content of the RDF is low at 14.7%, the ash ratio to FC is high (Ash / FC = 47%). As mentioned earlier, the tar yield of plant-based biomass is similar to the char yield, so the ash content (wt%) of the entire injected fuel, including both solid and liquid components, can be considered to be about half the ash content (wt%) of the solid fuel alone. Nevertheless, compared to the coking coal and LV coal shown later [Table 2 in Figure 10], where Ash / FC = 12.5% ​​and 14%, respectively, further reduction of ash is desirable for blast furnace tuyeres injected fuel.

[0079] Therefore, focusing on the characteristic of this embodiment that "char produced in a high-temperature carbonization furnace is finely pulverized (similar to PCI) and blown into the blast furnace tuyeres via COM transport," we devised a method to further deash by adding a "deash facility using a selective coagulation method with heavy oil, etc." between the fine pulverization equipment and COM transport. In other words, we devised a method to use the aforementioned liquid fuel, at least partially, to deash the char, which is a solid fuel after fine pulverization.

[0080] Coal deashment methods can be broadly classified into flotation and selective flotation, which utilize the difference in hydrophobicity between coal and ash, and heavy liquid methods, which utilize the difference in specific gravity. To increase the deashment rate, it is important to finely grind the coal and separate the coal and inorganic components. However, with heavy liquid methods and conventional flotation, the finer the grinding, the lower the deashment rate and the lower the coal recovery rate. In this respect, oil agglomeration and flotation using heavy oil are advantageous and have already been developed as coal deashment technologies (Patent Document 3, Non-Patent Document 7). Another advantage of performing these deashment treatments after fine grinding is that it is possible to remove water-soluble impurities that may remain in the char as unreacted components to some extent.

[0081] As shown in Figure 1, in this embodiment, the char from the high-temperature carbonization furnace is entirely pulverized for the blast furnace fuel portion, so the pretreatment (pulverization) required for the deash process is completed. It is desirable to add a deash equipment 11 downstream of the pulverizer 7, depending on the ash content of the char (for example, for high-temperature carbonization furnaces using RDF, the furnace group after its discharge equipment is dedicated to that process). As a flocculant (binder), an oil with low volatility is desirable, and it is desirable to utilize heavy oil or tar generated in the coke oven 3 or high-temperature carbonization furnace 2. When using heavy oil or tar as a flocculant, it is desirable to maintain it at 40-60°C due to its viscosity characteristics. In this embodiment, the related equipment (high-temperature carbonization furnace 2, COM 12, blast furnace 1) is preferably installed adjacent to each other, as shown in Figure 5. The sensible heat of the deash equipment 11 is taken over by the sensible heat of the COM fuel and is ultimately introduced into the furnace as the sensible heat of the blast furnace tuyere fuel, so there is no energy waste.

[0082] In Figure 1, the flow is shown in which the entire amount of powdered coke is charged into the high-temperature carbonization furnace. This allows alkalis (Na, K) remaining in the powdered coke and hindering the operation of the sintering machine and blast furnace to be removed in the high-temperature carbonization furnace (reduced chlorination and volatilization), and the reduced chlorination reaction of equation (6) can be promoted using powdered coke as a C source. [Examples]

[0083] As an example, the amount of carbon (∝CO2 emissions) consumed in the ironmaking area (blast furnace, coke oven, sintering machine) was estimated using the coal materials shown in Figure 9 (Table 1), assuming 100% sintered ore was used. Raw coal is coal whose coking properties and degree of coalification have been adjusted for use in coke production, while LV coal and HV coal are general coal with no (or low) coking properties and are used in high-temperature carbonization furnaces.

[0084] It should be noted that while a high-temperature carbonization furnace is equipment that carbonizes coal and other materials at temperatures of 900°C or higher, the calculations in this example assume equipment (including gas purification equipment) that carbonizes at temperatures equivalent to those of a conventional coke oven. Furthermore, it is assumed that all COG generated from coke ovens and high-temperature carbonization furnaces is used as a reducing agent (blast furnace reducing gas), and that combustion fuel for carbonization heat, combustion fuel for hot blast furnaces, and combustion fuel for sintering machines (ignition furnace, denitrification equipment) is supplied using blast furnace top gas or external fuel (CH4).

[0085] First, Figure 11, Table 3, compares the estimated carbon (C) consumption results for the case using LV coal in Figure 2 (Patent Document 1), which does not apply this embodiment, and the case using LV coal or HV coal in Figure 3, which applies this embodiment to the blast furnace tuyere injection line. Note that the numbers in the table are rounded to the nearest whole number, and the sum of the numbers does not necessarily match (the same applies to other tables).

[0086] Comparing the cases of "Figure 2 × LV coal" and "Figure 3 × LV coal," which use the same LV coal, the case of "Figure 3 × LV coal" to which this embodiment is applied shows an improvement of approximately 18 kg / tp in carbon consumption in the blast furnace. Although approximately 9 kg / tp of carbon consumption is added in the high-temperature carbonization furnace, the total carbon consumption in the ironmaking area can be reduced by approximately 9 kg / tp.

[0087] In Figure 3, even when LV coal is changed to HV coal, the total increase in C consumption is limited to 3 kg / tp, reducing the impact of the coal type change and improving by 5 kg / tp compared to "Figure 2 × LV coal" where this embodiment is not applied. Although not shown in the table, in the case of "Figure 2 × HV coal" where this embodiment is not applied, the coal consumption per unit × oxygen consumption is 582 kg / tp × 368 Nm 3HV coal cannot be used because it would make operation difficult due to the / tp ratio. However, in the "Figure 3 × HV coal" case, the unit consumption is 228 kg / tp × 137 Nm 3 The amount of carbon (C) can be reduced by more than half compared to conventional methods, and the carbon consumption (CO2 emissions) can be lower than in LV charcoal usage examples that do not apply this embodiment (Patent Document 1). In other words, it is clear that the range of charcoal materials can be expanded.

[0088] The bottom row of Figure 11 (Table 3) shows the carbon reduction when CH4 is converted to H2. Since the carbon consumption of the conventional hot-air-based blast furnace method is approximately 630 kg / tp (equivalent to 2.3 t / tp of CO2), if green hydrogen can be used instead of CH4, CO2 emissions can be halved without considering CO2 reuse or underground storage.

[0089] Next, in Figure 4, where this embodiment is also applied to the binder of a sintering machine, the case in which LV carbon or HV carbon is used is shown in Table 4 of Figure 12.

[0090] In the "Figure 4 x LV coal" case, carbon consumption worsens (increases) by 7 kg / tp compared to "Figure 3 x LV coal," and in the "Figure 4 x HV coal" case, carbon consumption worsens by 10 kg / tp compared to "Figure 3 x HV coal." This is mainly due to the increased carbon consumption of the high-temperature carbonization furnace resulting from the increased production of setting agents. Furthermore, "Figure 4 x HV coal" has 8 kg / tp lower carbon consumption than "Figure 2 x LV coal," demonstrating its ability to contribute to CO2 emission reduction across different coal types.

[0091] Furthermore, by converting HV coal to biomass-based fuels (including semi-carbonized fuels), carbon emissions from HV coal can be reduced to zero. If the entire amount can be converted, carbon emissions can be reduced by 248 kg / tp, reducing total carbon emissions from 381 kg / tp to 133 kg / tp (less than 1 / 4 of the conventional blast furnace method). By converting CH4 to green H2, carbon emissions can be reduced by another 57 kg / tp, bringing total carbon emissions down to 76 kg / tp (about 1 / 8 of the conventional blast furnace method). Moreover, 45 kg / tp of the 76 kg / tp is the carbon component in pig iron (molten iron), which can be recovered as CO gas when pig iron is smelted into steel in a converter installed downstream, and can also be used as reducing gas in the blast furnace. In other words, total carbon emissions can be reduced to about 30 kg / tp (about 1 / 20 of the conventional blast furnace method).

[0092] As mentioned above, according to this embodiment, waste other than pure biomass fuel can also be used as a coal substitute fuel. Although the coal emission factor of waste solid fuel is not zero, it has substantially the same CO2 reduction effect as biomass fuel in that it reduces CO2 emissions derived from the fossil fuel (coal) that is replaced.

[0093] Table 5 in Figure 13 shows a case in which LV coal or HV coal is used in Figure 1 (where fine char transport is changed from pneumatic transport in Figure 4 to COM transport), which serves as a model case for this embodiment.

[0094] Total carbon consumption remains unchanged for LV coal compared to Table 4 in Figure 12, but worsens for HV coal compared to Table 4. However, it can be seen that replacing coal or heavy oil with biomass fuels in both cases results in a greater improvement than the biomass fuel conversion shown in Table 4.

[0095] The amount of heavy fuel oil required for CO2 combustion is determined by the ratio of solid fuel to liquid fuel, with a 1:1 ratio eliminating the need for heavy fuel oil. As mentioned earlier, biomass fuels and waste plastics often have a higher liquid fuel yield than solid fuel yield, so by increasing their blending ratio (reducing the coal ratio), heavy fuel oil will eventually become unnecessary, and with a coal blending ratio of 0, the solid fuel concentration of the CO2 will be <50 wt%. In other words, since fossil fuels such as coal and heavy fuel oil are no longer needed, apparent CO2 emissions can be reduced to 114 kg / tp (less than 1 / 5 of the conventional blast furnace method). The gaseous fuel (COG) yield from biomass fuels and waste plastics is also higher than that of HV coal, so if the coal blending ratio is increased, externally procured CH4 can be replaced by increased COG, making it possible to achieve total carbon emissions of 76 kg / tp without using green H2 or carbon recycling / CO2 storage. This value is about 1 / 10 of the total carbon emissions in the conventional blast furnace method. In this regard, the fact that 200 million tons of waste are incinerated domestically each year (estimated by the inventor of this application) is an advantage from the perspective of the availability of coal alternative fuels (an urban-type circular resource generated annually). By chemically recycling waste that meets the quality and economic requirements as coal alternative fuels in this embodiment, it is possible to contribute to the reduction of CO2 emissions from the steel industry and waste.

[0096] In the embodiments and examples described so far, as a method of utilizing char produced in a high-temperature carbonization furnace as a blast furnace method, a coarse char obtained by coarsely grinding part or all of the char in a coarse grinder is used as a binder for sintered ore, and a method of blowing in the sieved powder generated in the coarse grinding process or the finely ground char that has undergone the fine grinding process from the tuyeres at the bottom of the furnace has been described. However, as a means of supplying char into the blast furnace, in addition to the method of blowing it in from the tuyeres at the bottom of the furnace after the fine grinding process, there is also a method of charging part or all of the coarsely ground char together with coke and ore from the top of the furnace, as shown in Figure 7.

[0097] As the char charged into the furnace reaches the lower furnace, it is preheated to the lower furnace boundary temperature (e.g., 1300°C). This allows (1) the efficiency of heat transfer from the char to the lower furnace to be increased, and (2) the amount of heat required to heat the ash (mainly SiO2) in the char, which is discharged as slag at approximately 1500°C, to be reduced to about 1 / 5, thus further reducing the fuel ratio. In other words, charging the char into the furnace has a thermal effect equivalent to reducing the ash content to 1 / 5, so even char produced from raw materials with a high ash content relative to FC (fixed carbon), such as RDF, can be used without deash treatment. Furthermore, the preheating effect of the ash in the char can, in principle, be expected to have a similar effect when used as a binder for sintered ore charged into the furnace.

[0098] If the char charged from the top of the furnace has been pre-treated with high-temperature carbonization, it will contain almost no volatile components. Even if gas is generated from the char due to preheating to over 900°C, it will contain almost no tar or hydrocarbons. Even if hydrocarbons are present, they will be reformed by H2O and CO2, so it can be processed as normal top-of-furnace gas (CO, H2, CO2, H2O, N2) without disrupting operations.

[0099] Charring from the top of the furnace is not only more thermally efficient than blowing it directly into the bottom of the furnace, but because char is more reactive than coke, it has the function of preserving coke quality by self-sacrificing itself by gasifying before the coke undergoes the gasification reaction (C + CO2 = 2CO, H2O + C = H2 + CO). The reaction rate of particles (kg / s) is determined by the specific surface area (m²). 2 Since it is proportional to the combustion rate ( / kg), it is desirable for the particle size to be fine enough to prevent scattering. If the average particle size of the coke at the bottom of the furnace is about 30-35 mm, then in order to have 10 times the specific surface area (∝ combustion rate), a particle size of 10 mm or less is desirable, and in order to prevent it from being blown away by some gas leakage, a particle size of 3 mm or larger is desirable. In other words, it is desirable for the char charged to the top of the furnace to be mainly composed of particles between 3 mm and 10 mm (i.e., 70% or more).

[0100] Because classification devices such as screens have classification efficiency, char smaller than the sieve mesh is also charged into the furnace. However, char discharged outside the furnace along with the furnace top gas can be recovered by a primary or secondary dust remover, finely pulverized, and blown back in through the lower tuyeres. However, since it also contains iron-based dust and auxiliary material dust in addition to carbon material, it can be effectively utilized as a sintering ore raw material (coagulant), as has been done conventionally.

[0101] By increasing the amount of char charged to the top of the furnace, the fuel burned in the lower part of the furnace shifts from being mainly tuyeres-injected fuel (fine char and tar, etc.) to char charged to the top. Combustion using tuyeres-injected fuel tends to result in higher combustion heat towards the furnace walls than in the center, as in conventional blast furnaces. However, since char charged to the top can be distributed equally in the radial direction, combustion tends to occur more evenly in the radial direction, and the furnace center temperature at which combustion ends can be increased. In other words, the heat distribution in the lower part of the furnace can be adjusted by adjusting the proportion of char charged to the top of the furnace.

[0102] In addition to the methods mentioned above, another way to adjust the heat distribution at the bottom of the furnace is to mix coarse-grained powder with fine-grained powder to extend the burning time of the char. In Figure 7, a line is installed that allows the powder that passes through the screen after coarse grinding (fine-grained char) to be mixed with the fine-grained char by bypassing the grinder, in order to adjust the burning time of the fine-grained char. However, for char with a high ash content, it is desirable to perform fine grinding and deashing treatment before converting it to COM. Since the amount of fine-grained char injected is reduced by charging char to the top of the furnace, it becomes possible to supply the oil necessary for COM transport with only coal or tar derived from coal substitute fuels (i.e., external fuels such as heavy oil become unnecessary).

[0103] On the other hand, the disadvantages of charging char to the top of the furnace include an increase in slag volume and auxiliary materials (sources of CO2 originating from raw materials) compared to blowing with tuyeres and ash removal when the char has a high ash content, and a longer time to reach the bottom of the furnace, resulting in reduced responsiveness to changes in the conditions at the bottom of the furnace. Therefore, it is desirable to appropriately adjust the ratio of top charging to blowing at the bottom of the furnace while considering the ash content in the char, the rate of liquid fuel generation such as tar, the rate of sieving generation due to coarse char grinding, and, as mentioned above, the radial heat distribution at the bottom of the furnace. Furthermore, the ability to adjust operations according to the raw materials and furnace conditions is an advantage of using both top charging and blowing at the bottom of the furnace.

[0104] From the above, it can be seen that the method of using char, a solid fuel produced in a high-temperature carbonization furnace, by coarsely grinding part or all of the solid fuel in a coarse grinder, and using the solid fuel as a binder for sintered ore, a furnace top charge material for the blast furnace, or both the binder and the furnace top charge material, and then blowing in part or all of the solid fuel, which has been finely ground so that the proportion of particles with a particle size of 0.1 mm or less is 70% or more, from the blast furnace tuyeres at the bottom of the furnace, is a distinctive and effective operating method in the blast furnace ironmaking process.

[0105] Table 6 in Figure 14 shows a comparison of carbon consumption between Case 1 (fine char injection into the lower part of the furnace alone; no deashification) and Case 7 (coarse char charging from the top of the furnace in combination) when using HV coal as shown in Table 2 in Figure 10. In the "Figure 7 x HV coal" case, an example is given where the ratio of coarse char charged to the top of the furnace and fine char injected into the lower part of the furnace is determined so that external fuel (heavy oil) is not required as COM for lower furnace injection. In the "Figure 7 x HV coal" case, this ratio is 77%:23%. However, this ratio will vary depending on the proportion of FC (fixed carbon) and VM (volatile matter) in the coal (or coal substitute fuel), including coking coal, the gangue content of the ore, the operating conditions of the coke oven or high-temperature carbonization furnace, etc.

[0106] In the "Figure 7 × HV coal" case in Table 6 of Figure 14, the total carbon consumption is lower than in any other example (case) because high carbon emission factors such as coal and heavy oil were reduced. Therefore, it is desirable to charge the char into the furnace top as much as possible when using coal without deashing, as described in Table 2 of Figure 10, and it can also be used as a binder for sintered ore that is similarly charged into the furnace top. Furthermore, the total char consumption of coarse and fine powder in this case (=173 kg / tp) is the lowest compared to the other cases in Figures 1, 4, and 5, and the CH4 consumption is the highest compared to the other cases. This indicates that this method is the most suitable for using biomass-based fuels (including waste-based fuels) with low carbon yield and high COG yield as alternative fuels.

[0107] Existing steel mills often have two or more blast furnaces. In this case, as a method for reducing CH4-derived CO2 as described in Tables 3 (Figure 11) to 6 (Figure 14), one or more blast furnaces can be converted to the method of the present invention, and the surplus energy (including converter gas) from the remaining conventional blast furnaces can be used instead of CH4. This means that the production volume using the method of the present invention will contribute to the overall CO2 reduction effect of the steel mill.

[0108] For example, in the "Figure 7 × HV coal" case in Figure 4 (Table 6), the carbon consumption per ton of molten iron is 362 kg / tp, but by utilizing surplus gas from an adjacent blast furnace, the carbon consumption from CH4 is 68 kg / tp (= 128 Nm³). 3 CH4 / tp (4.6 GJ / tp) becomes unnecessary, and carbon consumption becomes 294 kg / tp (equivalent to 1.08 tCO2 / tp in CO2 emissions). In other words, almost all of the coking coal can be changed to HV coal, and without using expensive external fuels, blast furnace CO2 emissions can be halved from the current approximately 2.2 tCO2 / tp to 1.08 tCO2 / tp. The surplus energy of the conventional blast furnace method, including tar, etc., is 7.4 GJ / tp (estimated by the inventor of this application), and for every 1 tp of "Figure 7 × HV coal" production, it balances out with the conventional blast furnace production of 0.62 tp (= 4.6 / 7.4).

[0109] Although this invention has been described in the context of blast furnaces, its principles and effects make it applicable to other metallurgical furnaces as well. Several examples are given below.

[0110] For example, as a measure to reduce CO2 emissions in the steel industry, a method has been developed in Europe and Japan that, instead of the conventional blast furnace method, "produces DRI (directly reduced iron) in a hydrogen-based direct reduction furnace, and then melts and carburizes the DRI in an electric melting furnace to produce pig iron (molten pig iron)." Direct reduction furnaces (metallurgical furnaces) require green hydrogen as an alternative to conventional natural gas, and electric melting furnaces (metallurgical furnaces) require carburizing materials such as coke, so there are challenges in terms of energy efficiency and CO2 reduction. However, according to the present invention, coke ovens that become idle facilities when existing blast furnaces are shut down can be utilized as high-temperature carbonization furnaces, and waste materials that are close to carbon neutral (CN) can be pre-treated as raw materials, thereby supplying CN gaseous fuel (COG) as a substitute for hydrogen as a reducing agent, and CN high-quality solid fuel (char) as a substitute for coke as a carburizing agent. Liquid fuel can also be used as heating fuel for gas reforming furnaces for direct reduction furnaces, etc.

[0111] Since the carburizing agent needs to penetrate the slag layer, which is denser than the carbon material, and enter the molten iron, high-temperature carbonization is important to minimize the amount of VM (volatile matter) that generates gas. Furthermore, since the carburizing rate is inversely proportional to the particle size, it is also effective to finely grind the material before blowing it into the molten iron.

[0112] Furthermore, as a measure to reduce CO2 emissions in the steel industry, the conventional method of "producing molten steel by melting scrap and DRI in an arc-type electric furnace" is also being pursued as an alternative to blast furnaces. However, since electricity costs significantly impact the economics of arc-type electric furnaces (metallurgical furnaces), in countries with high electricity rates, such as Japan, fossil fuels (injection of carbon, natural gas, heavy oil, etc.) have been widely used as slag forming materials and fuel for scrap melting burners in order to reduce electricity consumption per unit. Moreover, burners are needed to decompose DXN at high temperatures as a countermeasure against dioxins in electric furnace exhaust gases, and fuel consumption is even on the rise, contrary to efforts to reduce electricity consumption per unit. However, according to the present invention, coke ovens that become idle facilities when existing blast furnaces are shut down can be utilized as high-temperature carbonization furnaces, and high-quality slag forming materials and metallurgical fuels can be obtained in CN.

[0113] It can also be used for pre-treatment of raw materials in other metallurgical furnaces such as cupolas (especially cokeless cupolas), molten reduction furnaces, non-ferrous metal smelting furnaces, and lime calcination furnaces.

[0114] Furthermore, the direct reduction furnaces and electric melting furnaces exemplified above also exist as standalone metallurgical furnaces, and the present invention can be applied to each of them. In addition, while the use of existing coke ovens was exemplified as a high-temperature carbonization furnace from the perspective of utilizing existing equipment, the present invention is not limited to this, and there is no problem in installing a high-temperature carbonization furnace of a different type from a coke oven in a steel mill that does not have a coke oven. [Industrial applicability]

[0115] The technology according to the present invention also relates to reducing CO2 emissions from waste.

Claims

1. A coal or coal substitute solid fuel that is non-coking or has coking properties that prevent it from becoming blast furnace coke is charged into a high-temperature carbonization furnace as a raw material for char, and the high-temperature carbonization treatment is performed using the high-temperature carbonization furnace under conditions that the maximum carbonization temperature is 900°C or higher. The combustible material produced by the high-temperature carbonization process is separated into solid fuel, liquid fuel, and gaseous fuel as char, A method for pre-treating raw materials, comprising injecting part or all of the solid fuel, liquid fuel, or gaseous fuel into a metallurgical furnace.

2. A portion or all of the solid fuel is subjected to coarse grinding or fine grinding, and the sieved powder generated in the coarse grinding process or the solid fuel that has undergone the fine grinding process is blown into the metallurgical furnace. The method for pre-treating raw materials according to claim 1.

3. CO and H from part or all of the aforementioned gaseous fuel 2 The main synthesis gas is produced and blown into the metallurgical furnace at a temperature of 800°C or higher. The method for pre-treating raw materials according to claim 1.

4. A portion or all of the aforementioned liquid fuel is injected into the lower part of the metallurgical furnace. The method for pre-treating raw materials according to claim 1.

5. The finely ground solid fuel and the liquid fuel are mixed in advance and blown into the lower part of the metallurgical furnace. The method for pre-treating raw materials according to claim 4.

6. A portion or all of the aforementioned solid fuel is crushed to obtain solid fuel with a particle size of 1 mm or more and 10 mm or less, which is used as a binder or furnace top charge material for sintered ore, or both the binder and the furnace top charge material. A portion or all of the solid fuel, which has been finely ground so that the proportion of particles with a particle size of 0.1 mm or less is 70% or more, is blown in from the tuyeres of the metallurgical furnace. A method for pre-treating raw materials according to any one of claims 1 to 5.

7. Using waste as a coal substitute fuel, the chlorine concentration in the waste charged into the high-temperature carbonization furnace is Cl 1 (wt%_dry) and waste charge ratio X vo (wt%_dry) is at least Cl 1 ≥3% or Cl 1 ・X vo Any of the following applies: ≥0.5% A method for pre-treating raw materials according to any one of claims 1 to 5.

8. To deash the solid fuel after it has been finely ground, use at least some of the liquid fuel. The method for pre-treating raw materials according to claim 7.

9. The method for pre-treating raw materials according to claim 7, wherein some or all of the waste to be charged into the high-temperature carbonization furnace is pre-molded before being placed inside the furnace.

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