The new Roben Jig method of coal washing for analyses

by Kathrine Moore

GEOSCIENCE BC and the Canadian Carbonization Research Association (CCRA) have announced the launch of a research project to test the ability of a new coal washing process to accurately evaluate coal quality and the coking characteristics of metallurgical coal during the exploration stage. Evaluating the quality of a coal deposit is essential to determining its economic viability.

“This research will help us identify the best method of determining coal quality before a mine is built,” stated Melanie Mackay, President of the Western Canadian Coal Society and Technical Member of the CCRA. “The ability to accurately evaluate coal quality and the coking characteristics of metallurgical coal during the exploration stage is essential to determining the economic viability of a coal deposit.”

“The potential of finding a faster, safer more reliable method of determining coal quality is a real boon for the coal industry,” added Bruce Madu, Vice President, Minerals and Mining at Geoscience BC. “Ultimately, the more accurate information a prospector or company has about the quality of coal beneath the ground, the higher the value they could get for their property or the end product.”

Conventionally, the ‘float and sink’ method has been used to analyze small-scale exploration samples of metallurgical coal. This method used a variety of solvent-based chemicals to remove impurities such as ash: white spirit, methylene bromide and perchloroethylene (PCE). PCE in particular is a toxic carcinogen, commonly used in the dry cleaning industry and poses a health threat to laboratory workers.

The new Roben Jig method of coal washing for analyses uses no harmful chemicals. A coal sample is loaded into a specially designed cylinder with water. A May 2, 2017 news release describes the Roben Jig method. “A motor moves the cylinder up and down in a ‘jigging’ motion which sorts the coal particles by density, with the heaviest particles sinking to the bottom and the lightest particles moving to the top. Clean coal samples are then extracted from the jig and undergo various tests to determine quality, most notably maximum fluidity (melting and interaction/bonding behaviour), and the resultant coke is tested for coke strength after reaction or CSR (an indicator of coke performance in an industrial blast furnace).”

CCRA and Geoscience BC will be using both the Roben Jig and float and sink methods to determine the accuracy and effectiveness of both methods. They will be looking at the relative impacts on four types of coal from BC: three from south-east BC and one from northeast BC. Birtley Coal and Minerals Testing (a division of GWIL Industries Inc.) will conduct the testing. The washed samples will be sent to Ottawa for follow-up analyses at CanmetENERGY laboratories where the samples “will be carbonized in a small coke oven and resultant coke properties will be evaluated.”

The Roben Jig process will be declared successful if it “provides equivalent or superior results to traditional coal washing methods.” Success would benefit the entire coal industry as it would no longer be necessary to use harmful chemicals to clean coal for coal and coke quality analysis.

The report states that, “Coal is BC’s largest export commodity and provincial 2016 estimates peg the value of BC’s coal production at $3.32 billion. Coal production currently represents over half of the total mineral production revenues in the province. Between 70% and 90% of coal produced in BC is metallurgical coal [used to make steel].”

The CCRA is a not-for-profit agency that conducts research on behalf of Canada’s steel and metallurgical coal producers. Geoscience BC is an independent, non-profit organization that generates earth science information in collaboration with First Nations, local communities, governments, academia and the resource sector.

Final study results of the effectiveness of the Roben Jig process compared to coal washing using the traditional float-and-sink method will be available in the fall 2017 on Geoscience BC’s web-site



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