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ScotAsh Upgrading of Power Station Waste

Challenge

Improve the quality of fly ash to allow its use in higher-value cement product.

Problem

Pulverised fuel ash has been sold by power plants to the construction industry for many years as a low-value product. The cement industry is ideally placed for this example of industrial ecology. It traditionally uses large volumes of primary extracted raw materials that cannot be sourced sustainably, but also uses chemistry compatible with a wide range of raw materials.

Solution

ScotAsh, a joint venture between ScottishPower and Lafarge cement has developed methods to upgrade the ash for use in advanced cement products. Using electrostatic separation to remove carbon from the ash, and large storage facilities to even out quantity and quality of product across the year, ScotAsh now has a rapidly growing business.

Benefits

When fly ash is used to extend traditional Portland cement, the saving in carbon dioxide emissions per tonne of concrete are in the region of 20-30% for mixes designed with equal 28-day strength
82% of ScottishPower’s ash is sold in products, diverting 1.6 million tonnes of ash from landfill, saving two million tonnes of primary aggregate, and saving and 20,000 tonnes of CO₂

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