HC Deb 20 March 1998 vol 308 cc746-7W
Mr. Gordon Prentice

To ask the Secretary of State for the Environment, Transport and the Regions what is the source of the thallium cited in tables 4.65–4.66 of the Government Agency's volume, "Monitoring at Castle Cement"; what was the total thallium content, gas phase and particulate phase of emissions to air on 28 and 29 October 1996; and what factors underlie the difference in thallium inputs and outputs between the No. 5, No. 6 and No. 7 stacks. [34455]

Angela Eagle

The Environment Agency has advised my officials that some 75–80% of thallium emitted in the cement manufacture process comes from the raw material used, with the remainder emanating from the fuel. The Agency further advises that Tables 4.65 and 4.66 of the Air Quality Monitoring Report indicate that the total amount of thallium released to air from kilns 5 and 6 was 0.02kg on each of 28 and 29 October 1996, with 95% being emitted in the particulate phase. The Environment Agency has explained that kilns 5 and 6 use the "wet" production process, whilst kiln 7 use the "dry" process. The two types of process differ in many characteristics including releases. Differences in thallium releases are a feature of the difference in process technology and are higher in the "dry" process. A wet scrubber due to be installed on kiln 7 in April will reduce emissions of thallium from that kiln. The Environment Agency has advised that it is in the process of making further investigations into thallium and that it would be happy to provide further information direct.

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