Coal Upgrading

Basics

• A Process by which Lower Grade Coals are "Upgraded" to a Product Functionally Identical to Higher Grade Coals
• Can be done via washing, drying/pyrolysis, and briquetting/pelletising
• The main goal is to reduce Ash Content and increase the Heating Value
• Due to Fossil Fuels obviously not being part of OSE's Strategy, this page is intended as a place to have information on this technolgy placed for reference in developing the Charcoal Fuels Workflow especially in regards to Ultra Pure Charcoal Fuel

Methods

Washing

• A Patent Titled "Process for preparing ultra-pure coal by using acid-alkali method" (Seems to be lab scale though? Odd and some potential translation issues, but interesting nonetheless)
• A 2001 Study Titled "The production of ultra clean coal by chemical demineralisation" (Uses Nitric Acid ...after Aqueous Hydrofluoric Acid So nasty stuff, did get from sh content of approximately 7.9% by weight and a sulphur content of 2.6% by weight to an ash content of 0.6% and Sulfur Content of 1.4%
• A 2020 Study Titled "Ultra clean coal production by microwave irradiation pretreatment and sequential leaching with HF followed by HNO3" (Initial ash contents from two sites of 8.31% and 10.36%, respectively to 0.39% and 0.69%)
  • Quote:
    • "Ultra Clean Coal (UCC) is defined as a coal that is washed using conventional methods, ground into fine particles, and then chemically treated to remove ash so that the final ash content of the coal is less than 1%. UCC has various potential uses, such as serving as the carbon source for the silicon smelting industry [2]; replacing oil for the production of aromatic chemicals and materials [2]; producing a coal slurry fuel that can be used to replace oil combustion in diesel engines [3], [4], [5], [6], [7]; producing activated carbon used in filters for water and air purification; producing carbon fiber that is an extremely strong reinforcement material used in construction [8]; fabricating carbon anodes to replace petroleum coke [2]; and serving as the fuel for advanced power generation technologies, such as direct firing in gas turbines [9]."
• A 2023 Study Titled "Study on preparation of ultra-clean coal from bituminous coal using the ionic liquid extraction"
• A 2011 Study Titled "Generation of ultra-clean coal from Victorian brown coal — Sequential and single leaching at room temperature to elucidate the elution of individual inorganic elements"
• A 2022 Study Titled "Production of Ultra-Clean Coal by the Combined Method of Grinding and Collector Gasification Flotation"
  • Interesting terms that lead to other rabbit holes:
    • "Collector Gasification Flotation Method" (Essentially adapting Froth Flotation to Coal Upgrading with various Solvents and Wetting Agents )
    • In digging i found the term coal gasification fine slag from This 2022 Paper Titled "Study on the mechanism of flotation of coal gasification fine slag reinforced with naphthenic acids"
• A 2023 Study Titled "Study on Preparation of Ultra-Clean Coal Based on Ionic Liquid"
• A 2014 Study Titled "ULTRA CLEAN COAL PRODUCTION USING DENSE MEDIUM SEPARATION FOR THE SILICON MARKET"
• A 2015 Study Titled "COAL PREPARATION TECHNOLOGY: STATUS AND DEVELOPMENT IN CHINA"
• A 2019 Open Access Paper from “The Egyptian Journal of Petroleum” Titled “ Desulfurization of high sulfur petroleum coke by molten caustic leaching”
  • Supposedly some of the sulfur in Petcoke can be a bit stubborn to remove due to it being bound to molecules in the tar in the coke, so either rounds of leaching/washing are needed, or high temperature Calcining / Steam Stripping
  • This took an odd sounding route, but was supposedly a bit in between the two in terms of efficiency so may be economical
  • A bath of molten Sodium Hydroxide or Potassium Hydroxide is made and petcoke is fed through it
  • Experiment may need to be more thorough to get clear guidance for parameters, but the process does work
  • May potentially increase ash content, but a followup study with more rigid protocol / integration with other procedures may clear this up

Briquetting / Pelletization

• An Article by "Mining Review" Titled "Coal fines waste pelletising technology launched"
• A Product Page by ACAN on their Carbon Black Briquetting Technology Titled "BRIQUETTE MAKING OF CARBON BLACK FROM PYROLYSIS PROCESS OF SCRAP TYRE"
• Patent US5916826A - 1997 Patent Titled "Pelletizing and briquetting of coal fines using binders produced by liquefaction of biomass" (Expired Already)
• A 2017 International Mining Article Titled "CoalTech completes its first economically viable industrial plant using coal pelletising technology"
• A 2018 Paper Titled "Value addition of coal fines and sawdust to briquettes using molasses as a binder" (Under a Creative Commons License so that's neat
• A 2020 Paper Titled "Influence of briquetting on thermal behavior of bituminous coal oxidized during storage"

Internal Links

• Ultra Pure Charcoal Fuel

External Links

• The Wikipedia Page on Refined Coal
• This 2022 Study Titled "Production of Ultra-Clean Coal by the Combined Method of Grinding and Collector Gasification Flotation" as far as i have dug upo so far is one of the most recent papers, and thus has a decent coverage of the State of the Art / TRL of the methods in it's Abstract and Introduction sections (with all the Et Al s)
• A 2014 Study Titled "The Technical Analysis on Upgrade and Coupling of Low-Quality Coal"
• A 2016 Study Featured in Volume 158 of "Fuel Processing Technology" Titled "A Review on Chemical Upgrading of Coal: Production Processes, Potential Applications and Recent Developments"
• A 2002 Report Titled "COAL UPGRADING TO REDUCE CO2 EMISSIONS"
• A 2020 Study Titled "A study of coal upgrading in briquette making based on briquette characteristics using heated mechanical methods"
• A 2004 Article Titled "Significance of Ultra-pure Coal preparation and Brief Introduction of preparation method"