History of the White Coal Technology
The drying of brown coals followed by the stabilization of the product by briquetting has been successfully practiced for over one hundred years, though the cost of such operations would make them unviable in the current general coal market. However, the technology applied to these brown coals, rotary steam tube dryers followed by ram extrusion briquetters, has not been successfully applied to sub-bituminous coals. The physical characteristics of the sub-bituminous coals are such that they could not be formed into stable briquettes that had the strength to withstand handling and stockpiling and that were not highly subject to spontaneous combustion. At least one reason for this is that the sub-bituminous coals are much harder and cannot be deformed into the desired shape at practical compaction pressures.
Several attempts have been made at what could be called “chemical” modification to the dried coal in order to improve the stability of sub-bituminous coals. Amax Belle Ayr attempted to dry and briquette a Powder River, USA sub-bituminous coal. It was reported that they were able to produce briquettes of adequate strength; however the briquettes were still subject to spontaneous combustion. While brown coal could be formed into dense impermeable briquettes that did not permit the ingress of airborne moisture—the initiator of spontaneous combustion—it would appear that this was not possible for the sub-bituminous coal.
Upgrading of these coals through reduction of the moisture content has been a goal of sub-bituminous coal producers and consumers. Despite many proposed solutions over many years, however, no process for upgrading these coals has yet been adopted at a commercial scale. As a generalization, these processes failed either because the upgraded product was subject to spontaneous combustion, the processing cost was too high, there was insufficient gain in energy content or there were unacceptable environmental impacts. An upgrading process for sub-bituminous coal based on a relatively simple thermal drying process followed by physical and chemical stabilization through a novel binderless briquetting process has proven to be economically attractive while at the same time providing an upgraded shippable product that can be handled and stored safely. The process is known as Binderless Coal Briquetting (BCB), or alternatively, the White Coal Technology.
The White Coal Technology process has developed from the work of KR Komarek in the late 1950’s, one of the worlds leading manufacturers of briquetting equipment. This work was picked up by TraDet Inc. (USA), a world authority on coal thermal drying and CSIRO (Australia). CSIRO started the development of the White Coal Technology in 1993 by taking some early reports of binderless briquetting and applying its knowledge of coal chemistry and processing to develop an understanding of the mechanisms necessary for binderless briquetting and the methods by which those mechanisms can be made to occur. Through seeking expertise in dryer and briquetting technologies, CSIRO formed a group that would work together to develop the White Coal Technology.
The development progressed through laboratory scale work at CSIRO and initial pilot scale work in the USA, through a 0.2 tonne per hour pilot plant at CSIRO, a 3 tonne per hour development plant in USA and finally a 10 tonne per hour development plant in Collie, Western Australia. This 10 tonne per hour development plant was built by Griffin Coal (Australia), operated from 1997 to 2005 and was the basis on which most of the patented intellectual property was developed. Griffin Coal is a major miner of sub-bituminous coal in Western Australia. The aim of the development plant was to demonstrate the binderless briquetting of Collie sub-bituminous coal. Scale-up of the process to this plant proved to be far more complex than had been anticipated and the exercise became a 6 year development project in which key features of the White Coal Technology process were developed and the design of commercial scale elements, particularly the briquette presses, were proven. Achieving quality briquette production at a small scale (production rates of less than 1 tonne per hour) was one thing, but achieving these same features at commercially relevant production rates required the slow and costly development of some subtle design and operational features. It involves the specific way that the coal is dried and the way in which the coal particles are brought together during compaction so as to form intimate coal to coal bonds between them. The figure below shows the Collie plant. While it was not a particularly attractive plant, being housed in a disused 1940’s vintage power alcohol distillery building, it does incorporate all the features of a commercial scale plant and it has operated stably, with as little as one operator and one general assistant, to produce over 10,000 tonne of briquettes.
The process developed into a commercially viable process capable of producing low moisture, physically and chemically stable briquettes from sub-bituminous coal at large scale and with attractive economics. The process was also developed and demonstrated for a wide range of bituminous coals ranging in rank up to anthracites. Superficially the White Coal Technology process that was finally developed looks like a simple combination of drying and briquetting but it incorporates key features which enable it to produce dense, stable briquettes where the individual coal grains have been bonded to each other and formed into intimate contact. The fact that the process appears quite simple (and as a result inexpensive) belies the fact that it has many years of development and substantial intellectual property integrated into many subtle aspects of it. The figure below shows photomicrographs of the structure of a White Coal Technology briquette and the coal particles from which it was formed. It can be seen that the coal particles have formed intimate contact with each other and virtually all voidage has been eliminated. This is reflected in the briquette density of 1.33gm/cc for briquettes made from Collie sub-bituminous coal which had an original density of 1.30gm/cc.
Approximately 10,000 tonne of briquettes were produced at the White Coal Technology development plant at Collie. Most of these have been produced from Collie coal but significant tonnages of both high rank bituminous coal and very low rank brown coal have also been processed. Although Powder River coals have not been available in sufficient tonnages to conduct trials on the Collie plant around one tonne of Powder River coal was subjected to the White Coal Technology process using the smaller 0.2 tonne per hour pilot plant at CSIRO’s laboratory in Sydney (later moved 160km North to Newcastle). These tests showed that the Powder River coals could be formed into low moisture briquettes with properties very similar to those produced from the Collie coal.
Binderless Coal Briquetting Company Pty Ltd (BCBC) acquired the exclusive global rights to the underlying technology on 27th April 2005. BCBC is a subsidiary of White Energy Technology Limited which in turn is a fully owned subsidiary of White Energy Company Limited. White Energy Company Limited went on to undertake a back door listing into a public company vehicle in June 2006, with an associated name change (previous name Amerod Resources). Since acquiring the White Coal Technology, White Energy developed it further with innovations around plant design, improvement in processes, development of process models for dynamic simulation, finite element analysis of briquetting machine, design of unique coal dryer and product cooling system and development of plant control logic and software.
The parent company White Energy Company Limited has demonstrated its ability to raise capital successfully on the public market. White Energy will continue to commercialize this technology and conduct further research and development around plant scale up and design. There will also be significant research and development activities in working with different types of coals and demonstrating to potential customers the end product result and costings. White Energy’s business objectives are to:
- Market and commercially diffuse the White Coal Technology worldwide
- Implement and carry out the following projects:
- build White Coal Technology plants
- sublicense White Coal Technology to plant owners and operators
- build own and operate plants
- manufacture White Coal Technology briquette product
- develop new markets and utilize the core skill set to develop new related products
- provide a financial return on R&D investment.
