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2020 / 2021 Edition

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Tarmac cut carbon with lime kiln investment

TARMAC Ltd are set to reduce carbon emissions from two of their lime kilns by 40% a year at the company’s Tunstead site, near Buxton, Derbyshire, following a £13.4 million investment in a new kiln.

As part of Tarmac’s ongoing commitment to reduce energy consumption across all of their operations, the new ‘Maerz’ kiln replaces two existing rotary kilns installed at the Tunstead site in 1955.

The new, more efficient kiln will help to reduce costs and atmospheric emissions at the site, which has already cut energy consumption by 25% in the past five years by investment in efficient plant and by introducing waste-derived fuels, such as used tyres and meat and bone meal, in its cement-making operations.

The Maerz kiln is the most efficient lime kiln currently available. By pre-heating the feed limestone, much of the heat is recovered – ensuring less energy per tonne of lime is required in production. The new kiln will reduce carbon emissions per tonne of quicklime by 40% and cut sulphur dioxide by over 90%.

‘Managing greenhouse gas emissions and reducing energy use are key sustainability commitments for Tarmac. This new kiln will help to better manage the environmental impact of our operations and reduce energy consumption,’ said Dr Martyn Kenny, head of sustainability at Tarmac Ltd.

‘Investing in new, more efficient technology is vital to delivering the sustainability targets that are central to our business strategy, and also helps to ensure that we run our operations as costs-effectively as possible.’

Fuelled by natural gas, the Maerz kiln processes 40–20mm limestone to produce high-purity quicklime (calcium oxide), a product commonly used in industrial effluent treatment, concrete building blocks, steel making and soil stabilization.

It took nearly two years to complete the design and construction of the new kiln, which consists of two interconnected vertical shafts, linked to each other by a cross-over channel, which are fired in sequence to achieve high levels of energy efficiency.

Two of the Swiss-made Maerz kilns, developed by engineering company Maerz Ofenbau AG, have been operated successfully by Tarmac at their site in Hindlow, Derbyshire, since 1981.

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