Lead Feature

Minerals from ashes, a real green story

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But a UK-based company, RockTron Ltd, says it has found a solution to the fly ash waste that is spewed by the plants - convert it into a legitimate use and relieve the burden on the planet.

Speaking to PRA at the recent International Greentech and Eco Products (IGEM) exhibition in Kuala Lumpur, Malaysia, Yazleen Dato' Yazid, Managing Director of RockTron's Asian arm, said the technology is the only one in the world that takes waste from the ground, cleans it (removes the carbon) and separates it into different products. The patented process takes dirty ash through a series of steps using reagents, centrifugal force and water separation to break it into parts.

"The minerals that are produced are hollow spheres (rare in some parts of the world), solid alumino-silicate microspheres (<1 to 300 micron) and solid paramagnetic microspheres," she said, adding that the products had an interesting appeal in the oil industry for lubricants and for rubber and plastics applications.

The minerals can be used to replace man-made inorganic fillers and extenders such as talc, GCC, glass fibres, glass microspheres, barytes, dolomite and clay. They can also be used as functional fillers in rubbers to give improved physical properties including sound absorption and improved wear resistance for components and coatings. The company says that usage is 20-25% lower than conventional fillers, thereby saving on raw material costs.

"Not only are these minerals 100% recyclable but also have a negative carbon footprint unlike conventional minerals that have to be dug out from the ground. So there is none of the usual mining, excavation, crushing, processing or energy costs associated with the production of ordinary inorganic fillers and extenders," said Peter Crofts, Head of Marketing of RockTron Ltd, speaking to PRA at IGEM.

He also said that the products are energy neutral. During the process, the plant recovers unburned carbon from fly ash, which is returned to the power station as fuel

Based in Malaysia, RockTron Asia, is a subsidiary of the UK-based company that innovated the technology, and was set up two years ahead of schedule. Following the signing of its first franchise in the UK, at the IGEM, the company signed an MOU with Tenaga Nasional Bhd (Malaysia's national electricity board) to convert the fly ash from its power generation plants.

"We are aiming to franchise the technology to various parts of the world like China, Australia, Poland, Russia and the US," said Crofts, adding the return on investment is recoverable in two years, though the company would not disclose the franchise fee.

Why Asia and why in Malaysia? The answer lies in the 2 million tonnes of fly ash produced a year in Malaysia. Of this, 1 million tonnes is already stored in ash ponds and is predicted to grow rapidly. Indonesia produces 2 million tonnes each year and this is predicted to double by 2013 while the accumulated deposited amount of fly ash has exceeded 2,500 million tonnes in China.

The UK plant is located at Fiddler's Ferry, near Widnes in Cheshire, and is able to produce up to 800,000 tonnes of eco-minerals each year. Scottish and Southern Energy, which owns Fiddler's Ferry, put up £30 million to finance the plant.

The technology is the fruition of four UK inventors, two of whom are deceased, and has been on the drawing boards for two decades. As the story goes, the co-founders of RockTron, Philip Michael and John Watt, a geophysicist, set the company up in 2000 and were turned down by around 50 banks before Scottish and Southern Energy offered support in 2007.

The technology is able to process 100% fresh and stock-piled coal-fired power station waste into eco-minerals, with no waste stream. The company also claims that performance wise its products are superior, in some cases, or comparable with conventional minerals.

Test results from independent rubber consultants, ARTIS (Avon Rubber Technology Innovation and Science) augment previous research by Queen's University in Belfast showing that in a silica passenger tyre compound, RockTron's products demonstrated increased tan delta at 0°C (for improved tyre wet grip) and reduced tan delta at 70°C (for reduced tyre rolling resistance).

Another advantage is that the products are naturally spherical, thereby removing surface alkali salts to enhance performance. Other attributes include lower melt viscosity and lower density compared to inorganic fillers. The glass microspheres (Mohs hardness scale = 5-6) also allow for low oil absorption, reducing the amount of raw material required.

But for the time being the products come in a blackish grey colour with a white being formulated but not yet released on an industrial scale.

The potential for use in plastics is expandable, said Crofts. "Car companies like BMW, VW and Ford are looking at the use of the fillers in under-the-hood parts like engine covers and interiors," he added.

The products are also targeted at the cement/concrete industry, which does use fly ash currently but is controversial due to the high levels of carbon present in the ash. Also, every tonne of cement currently produces approximately 0.82 tonnes of carbon dioxide during the manufacturing process (circa 5% of annual man-made carbon dioxide). Hence, the company says substituting 500,000 tonnes of RockTron eco-minerals on a one to one basis with that of man-made glass spheres could save over 450,000 tonnes of carbon dioxide in a year.

It is offering its products under the brand names of MagTron (spherical paramagnetic), CenTron (hollow glass microspheres) and MinTron (solid alumino-silicate glass spheres).