Holcim US - Energy and Raw Materials

Holcim (US) uses four key performance indicators to monitor the eco-efficiency of clinker production.

1. Clinker factor
The clinker factor is the percentage of clinker in cement. Clinker can be substituted by other materials (known as mineral components) to make different kinds of cement. Lowering the clinker factor reduces the amount of fuel required per ton of cement produced, and substituting the clinker with suitable waste materials reduces the volume of virgin raw materials required. Suitable materials include fly ash from coal-fired power generation and blast furnace slag from iron production.

2. Thermal energy efficiency of clinker production
The thermal energy efficiency of cement plants is measured as the total thermal energy consumed per ton of clinker produced and is almost entirely a function of the technology applied in the production process. Thus, significant improvements in thermal energy efficiency result from investment in modern efficient plants and closure of old energy-intensive kilns.

3. Thermal substitution rate
Substitution of fossil fuels by alternative, waste-derived fuels is a common practice in many parts of the world. It is an important eco-efficiency driver because it reduces fuel costs, carbon dioxide emissions, and use of natural resources. This enables the industry to provide a service to society by dealing safely with wastes that are often difficult to dispose of in any other way. We are committed to increasing our use of these waste materials, while ensuring that they have no adverse impact on public health, the environment, or product quality.

4. Cement kiln dust (CKD) disposal rate
CKD and bypass dust are extracted and discarded from the cement production process when it is necessary to reduce sodium and potassium concentrations in the cement, and the chlorine content of the process. In many cases CKD and bypass dust can be recycled back into the system, but this cannot occur in some regions where cement standards require low alkali concentrations. The CKD disposal rate is a measure of our eco-efficiency, as the more we dispose of, the less efficient is our use of raw materials. On a global scale, in 2002 we extracted and could not return to the kiln system 19 kilograms of CKD per ton of clinker.