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EP-4737536-A1 - COKE PRODUCTION METHOD

EP4737536A1EP 4737536 A1EP4737536 A1EP 4737536A1EP-4737536-A1

Abstract

Provided is a new index for biomass-derived raw material that can replace a portion of coal used in the production of coke for blast furnaces, and a means for producing high-strength coke even when biomass-derived raw material is blended with coal. Biomass having a micro-strength index (MSI 0.21 ) of 45 or more in coke for testing obtained by dry-distilling the biomass alone is blended with a coal blend to produce coke.

Inventors

  • KAWAI, YUYA
  • TAKASHIMA, TAKANORI
  • DOHI, YUSUKE
  • YAMAMOTO, TETSUYA
  • MATSUI, TAKASHI

Assignees

  • JFE Steel Corporation

Dates

Publication Date
20260506
Application Date
20240425

Claims (8)

  1. A method of producing coke, the method comprising: blending biomass in a defined proportion with a coal blend for coke production to form a mixture, and dry-distilling the mixture to produce coke, wherein a micro-strength index of coke for testing obtained by dry-distilling the biomass alone is 45 or more.
  2. The method of producing coke according to claim 1, wherein the micro-strength index is 60 or more.
  3. The method of producing coke according to claim 1 or 2, wherein a temperature at which the coke for testing is dry-distilled is 1000 °C.
  4. The method of producing coke according to any one of claims 1 to 3, wherein volatile content of the biomass on a dry basis is 6.0 mass% or more.
  5. The method of producing coke according to any one of claims 1 to 4, wherein the biomass includes at least one of palm kernel shells or woody biomass.
  6. The method of producing coke according to any one of claims 1 to 5, wherein the biomass is carbonized biomass obtained by heat-treating unheated biomass.
  7. The method of producing coke according to any one of claims 1 to 6, wherein a proportion of the biomass in the mixture is 1.0 mass% or more and 10 mass% or less.
  8. The method of producing coke according to any one of, claims 1 to 7, wherein a proportion of the biomass having a particle size of 3.0 mm or less in the biomass is 70 mass% or more, and a proportion of the coal blend having a particle size of 3.0 mm or less in the coal blend is 70 mass% or more.

Description

TECHNICAL FIELD The present disclosure relates to a method of producing coke using biomass as a portion of raw material. BACKGROUND Coke is a mainly carbon agglomerate product obtained by dry-distilling coal. Blast furnace coke used in a blast furnace functions as a heat source and a reducing agent, and also as a support material that secures gas permeability and liquid permeability inside the blast furnace. Therefore, in order to secure stable operation of the blast furnace, the agglomerate coke is required to have sufficient mechanical strength. In the production of blast furnace coke, a coal blend in which multiple types of coal are blended in a defined proportion is used. The coal blend is dry-distilled at a temperature of 1000 °C or higher either as is or after being molded, to obtain agglomerated coke in which coal particles are bonded together. By using a type of coal called caking coal, which has a property of easily softening and melting, as a portion of the coal blend, it is possible to obtain coke that has high strength. Two types of measured values of coal have conventionally been used as indices for managing coke strength. One is an average maximum reflectance of vitrinite (hereinafter referred to as "Ro") as specified in Japanese Industrial Standard M 8816:1992 "Solid mineral fuels - Methods of microscopical measurement for the macerals and reflectance". The higher the Ro value of coal, the higher the degree of carbonization and the stronger the coke matrix tends to be. The other is maximum fluidity according to a Gieseler plastometer (hereinafter referred to as "MF"), as specified in Japanese Industrial Standard M 8801:2004 "Coal-testing methods". The higher the MF value of coal, the more the coal tends to soften, melt, and flow when heated. In recent years, societal efforts to mitigate the impact of global warming by decreasing carbon dioxide emissions into the atmosphere, one of the greenhouse gases, have been accelerating. For this reason, studies are underway to replace a portion of the coal used to make coke with carbon-neutral raw material such as biomass. For example, in Patent Literature (PTL) 1, a method of producing coke is described in which woody biomass material that has been heat-treated at a temperature higher than 300 °C and 400 °C or less is mixed with coal and dry-distilled in a coke oven. Further, in PTL 2, a method of producing highly reactive blast furnace coke is described, in which biomass is heated to 1000 °C or higher to pyrolyze the biomass, and the resulting solid biomass char having a diameter of 1 mm or less is added to a coal blend. CITATION LIST Patent Literature PTL 1: JP 2005-272569 APTL 2: JP 2014-077086 A SUMMARY (Technical Problem) When attempting to replace a portion of the coal used to make coke with a biomass-derived raw material, even a small substitution ratio can significantly decrease the strength of the resulting coke. Conventionally, Ro and MF, which are effective indices for managing the strength of coke, are both indices for measurement of coal. Therefore, when attempting to measure Ro and MF for a sample consisting only of biomass-derived raw material, the properties of coal and biomass are significantly different, and therefore it is either impossible to carry out the measurements, or even if the measurements could be carried out, the measured values could not be used as indices for managing the strength of such coke. Therefore, a new index for managing the strength of coke is required. In view of the problems described above, it would be helpful to provide a new index for biomass-derived raw material that can replace a portion of the coal used in producing coke for blast furnaces, and to provide a means of producing high-strength coke even when biomass-derived raw material is blended with coal. (Solution to Problem) In order to clarify the cause of the decrease in strength of coke that uses biomass as a portion of the raw material, the inventors of the present patent application conducted detailed observations of defects present inside agglomerate coke having decreased strength. As a result of the observations, it was found that in coke containing biomass-derived raw material, the biomass-derived portion has low strength and is easily broken when stress is applied from the surrounding area. That is, it was estimated that the strength of the coke as a whole was decreased because the biomass-derived portion became an initiation point of breakage. Further, the inventors investigated a micro-strength index, an index of microscopic strength, of raw material derived from various types of biomass, and discovered that the micro-strength index varies greatly depending on the type of biomass used as raw material. The inventors then discovered that by using the micro-strength index of biomass as a new index and selectively using biomass suitable for blending with a coal blend, it is possible to suppress a decrease in coke strength, and arrived at the pre