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Advances in coal drying commercialisation- Part 2

World Coal,

The GTLE technology

GTLE has developed a patented and proprietary coal beneficiation technology to upgrade low rank coals. The technology uses a combination of high compaction pressure and low temperature evaporation to remove moisture from low rank coals, producing a high energy, lower emission and stable product suitable for export or domestic markets.

Figure 3.

Unlike other alternative technologies, the GTLE process uses mechanical pressure and low, indirect heat to remove moisture (Figure 3). The use of commercially available briquetting and drying equipment, modified to GTLE specifications, reduces both the economic and technical risks inherent in the deployment of novel technologies. Adding additional trains or modules, minimising scale-up issues, can easily expand the capacity of a full-scale process plant.

Figure 4.

With GTLE technology, the release of volatile hydrocarbons is negligible and the product cools to ambient temperatures quickly (thereby reducing spontaneous combustion risks). The physical changes to the internal structure of the coal (Figure 4), reduces the porosity of the material, limiting moisture re-absorption, providing physical stability and ultimately producing a high energy, stable briquette.

Since 2010, GTLE has successfully tested dozens of different coals at its pilot plant test facility in Golden, Colorado. In addition, it has produced briquettes at its commercial-scale facility in South Heart, North Dakota, using coals from Indonesia, North Dakota and New Zealand.

Figure 5.

On April 20, 2013, GTLE completed commissioning of the Mataura coal drying facility (Figure 5), meeting all operating criteria (technology warranties) established in the license agreement with the owner, Solid Energy New Zealand Ltd (SENZ). The Mataura plant’s capacity is rated at a nominal 100,000 tpa, converting a 40% total moisture (TM), 3600 kcal/kg lignite into a 14% TM, 5100 kcal/kg product –matching the quality produced in the bulk trials run at the South Heart test facility. This is a single train commercial-scale plant that has addressed scale-up risks associated with technology development.

The Mataura plant has enabled GTLE to develop the suite of environmental, health and safety and production driven standard operating procedures (SOP), which are required for the maturing and delivery of a technology.

Production from the Mataura facility is being used to establish the New Zealand market for high-grade coal briquettes, while proving conclusively that the technology can produce marketable product in a safe, reliable and continuous process, with suitable stockpile, transport and combustion characteristics.

The Mataura plant will also be available for evaluating other Asia-Pacific coals before project development, to undertake large volume export transportation and combustion trials, as well as acting as a test platform to further enhance the GTLE technology.

Steps toward a successful project

The economic viability for coal upgrading is dependent on both market and project specific variables. Key criteria to evaluate when looking at possible projects should include the following:

Markets with large price differentials for quality

Focus on markets where a significant premium exists for high quality products. Asia is currently the best region fitting these criteria, with US domestic options challenged due to an abundance of gas and restricted coal development.

Coals that can be converted into a premium product

Steer away from high ash coals that can limit upside calorific value potential, or coals with high sulfur or mercury content that can adversely impact environmental acceptance.

Coal reserves with low mining costs

The amount of coal required to make one tonne of beneficiated product is directly proportional to the moisture content of the feed coal. By example, coal with 40% TM will need 1.5 t of feed per tonne of product, versus a 65% TM coal, which needs 2.5 t of feed per tonne of product. This feed cost leveraging drives companies to limit high moisture candidates to surface mineable, very low-cost of production reserves – typically under US$ 15/t.

Stranded coal reserves

For some low quality, location challenged resources, coal beneficiation may be the only option for making these reserves commercially viable, and moving these assets from resources to the reserves category, adding value to the corporate financials.

Favourable logistics

This includes both mine-to-plant and plant-to-market transportation costs, as well as consideration for existing transport networks that do not require large capital expenditures or multiple projects to be economic. Some coal reserves are not just stranded due to high moisture, but also because of the cost of transport to market, they may not be suitable targets for upgrading.

Next generation coal drying

With these criteria in mind, GTLE has initiated early development of its next generation plant: a 1 million tpa coal drying facility, which will be located in Kalimantan, Indonesia.

In 2012, GTLE signed a Memorandum of Understanding (MoU) with an Indonesian coal producer to secure a plant site, coal supply and access to infrastructure (barge loading and transhipment) to support project development. The mine is an existing operation with sufficient coal reserves to support the project over its 20+ year life. The proposed site has useful existing infrastructure for product handling and low cost transfer to FOB vessel. Mine, plant and barge loading are all within a few kilometers of each other.

Raw coal quality is estimated at 45% TM and 3500 kcal/kg with very low ash and sulfur. Product quality should reach 5500 kcal/kg, which is a highly desired product in Asian markets. Preliminary coal beneficiation trials have been completed at Hazen Research with positive results.

Figure 6.

The GTLE engineering team has developed the base engineering package, which includes a 3-D model (Figure 6), flow sheets, equipment specs, motor list, heat and material balance and the necessary P&ID, etc. It also incorporates lessons learned from the Mataura plant operations. This will enable the preparation of a definitive cost estimate and detailed feasibility work. The feasibility study results will be used to support sourcing of project finance and, if successful, secure the necessary commitments to proceed.


With the ever increasing need for sub-bituminous and lignite resources to replace the diminishing sources of high-grade bituminous coals, economically viable coal beneficiation technologies offer one of the cleanest and quickest solutions.

While there remains the challenge of overcoming an industry history of shortcomings, seven years and over US$ 45 million of investment on R&D activity, the GTLE technology is ready for commercial deployment around the world.

Written by Claude C. Corkadel.

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