Portland cement is manufactured by heating limestone or chalk with clay in a rotary kiln to a high temperature (about 1450°C) to produce hard nodules of clinker that are then ground with a little gypsum in a ball mill. The firing process consumes significant quantities of fuel, usually coal or petroleum coke. Reduced fuel use is a fundamental objective of the cement industry. The major environmental concerns of cement manufacture are outlined in the Table.

The manufacturers have taken steps to minimise the impacts by:

1 Reducing primary raw material needs by increasing the use of by-products from other industries, along with dust suppression measures and landscaping after quarrying.

2 Use of waste products as alternative fuels (oil, solvents, tyres) along with greater emissions control and investment in more efficient plant (heat exchangers, pre-heaters, insulation). Reducing cement clinker by replacing during the grinding process with cementitious materials from by-products of other industries e.g. fly ash, ground granulated blastfurnace slab

3 Use of grinding aids to reduce clinker milling time and improved equipment efficiency.

4 Overnight deliveries, increased rail use, fuel efficient vehicles, reduction of empty truck movements by making use of returned concrete loads instead of dumping on site.

For information see MPA Cement