Renewable Energy
major corporate reorganisation of the UK Electricity Generating Sector in the early 1990s and the bursting of the dot com bubble in 2002. RockTron’s beneficiation technology has now been proven with the construction in 2008 of the world’s first 800 000 tonne per annum capacity commercial plant in the UK, licensed to a major energy utility company. Further plants are already under construction around the world. RockTron’s innovation is that its technology enables
consistent production of quality controlled cementitious minerals, despite the often poor initial quality of the original fly ash produced by the power station. RockTron’s process uses ‘Froth Flotation’, a proven wet mineral processing technique, and other specialist processes to treat the total fly ash feedstock. Te result is a very green system that produces
neither solid nor liquid waste streams and enables the highly efficient separation of the valuable minerals that make up fly ash. Te first stage involves the removal of cenospheres,
hollow glass spheres for use in applications such as lightweight fillers and coatings. Tis improves the density of the remaining alumino-silicate particles. Te second stage involves the removal of carbon.
First, this carbon can be returned to the power station to be re-burnt as fuel, thereby reducing the overall energy impact of the production plant. Second, carbon provides a negative contribution to strength development in concrete and has a deleterious effect on air entraining agents and additives, which it preferentially adsorbs. Tis often requires the more expensive CEM I to be added per cubic metre of concrete produced. Te RockTron process is very efficient at removing the carbon from fly ash, improving the water to cement ratio, increasing concrete strength development at a lower cost base and producing a consistent lighter coloured concrete. RockTron Alpha cement substitute has a typical LOI (carbon content) of <5 per cent in the UK, making it the lowest carbon / finest particle size cement
substitute available on the market. Te process then recovers the much higher specific gravity spherical maghemite particles, which further helps lighten the colour of the final alpha product and thus produces a whiter concrete. Tis spherical maghemite product can be used in a variety of shielding and sound absorption applications including specialist high density concretes, often required in hospitals and the wider nuclear industry. Te remaining beneficiated material comprises clean, beneficiated solid alumino-silicate glass spheres, which are classified into cementitious products graded into RockTron Alpha and Delta. ●
Philip Michael is Co-Founder of RockTron, Keynsham, Bristol, UK.
www.rktron.com
N
Solar policies on track to create 10 000 jobs by April 2012 UK homeowners face an ever-growing
ew analysis by Engensa, the UK solar energy company, s a y s the UK’s Feed-in Tariff (FiT) will
create 10 000 green jobs by early 2012. First introduced in April 2010 to support domestic alternative energy production, the policy is expected to create nearly 50 000 additional jobs by 2015 if kept at current levels, according to Engensa’s research. In addition, in the short term, the solar industry is generating more tax revenue for UK plc than is being paid out on the FiT: Engensa estimates up to £65m positive value in the period ending April 2012.
rise in electricity bills with today’s rates 62 per cent higher than six years ago. The current version of the FiT policy enables companies to offer free solar installations that can save around £200 per year on energy bills. Homeowners who choose to pay for
solar panels for their homes can also make money from feeding excess energy back into the grid. The first year of the FiT yielded 70 000 installations in the UK alone. The FiT enables homeowners to benefit from clean, affordable energy and the UK
Fig. 2. Solid glass spheres.
to compete globally in the renewables marketplace. The rapid growth of the solar industry is the answer to jobless figures in the UK, where key economic indicators show growth of 0.2 per cent of GDP in Q2 2011 and record unemployment rising by 38 000 in the three months to June. A complimentary market to solar, the construction industry, has been particularly hard hit with a loss of 21 000 jobs in the 12 months to June 2011. ●
For more information,
www.engensa.com/greenjobs www.engineerlive.com 57
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