Page 339 - Design for Environment A Guide to Sustainable Product Development

314 Cha pte r Se v e ntee n

substances to the atmosphere. To assure continuous improve-
ment, Holcim (US) has established a three-pronged global
emissions monitoring and reporting standard as follows:
1. Continuous emission monitoring to measure airborne
emissions of nitrous gases, sulfur dioxide, carbon diox-
ide, oxygen, and volatile organic compounds.
2. Annual stack tests for heavy metals, dioxins/furans, hydro-
gen chloride, benzene, and ammonia.
3. Equipment certification at least once per year by an exter-
nal, qualified organization. This standard is often more
stringent than corresponding federal or state require-
ments, and allows performance comparisons with other
Holcim Group companies.
• Resource conservation and recycling. Efficient use of natural
resources is an important cornerstone of Holcim’s environ-
mental policy. The company promotes eco-efficiency, conser-
vation of nonrenewable natural resources, and recycling of
secondary materials (waste and industrial by-products). For
example, some Holcim plants use fly ash from electric power
plants to help supply natural elements required for cement
production. In addition, heat and dust are captured during
the production process to make kilns run more efficiently and
cleanly. To reduce the environmental footprint of cement pro-
duction, Holcim uses a number of strategies:
Substituting natural raw materials with industrial
by- products such as fl y ash
Replacing fossil fuels with alternative fuels from indus-
trial waste streams
Improving process efficiency to reduce energy and

material consumption
Recycling or reuse of solid wastes, primarily cement
kiln dust (CKD) and bypass dust.

At selected plants, Holcim has been partially replacing fossil fuels
with EPA-approved supplemental fuels, such as used paint thinners,
used dry cleaning fluids, and industrial solvents. The highly efficient
burning temperatures in cement kilns can eliminate as much as
99.9999% of these organic materials. At some plants, Holcim is using
scrap tires as supplemental fuels, which offers several advantages [5]:
• Tires produce the same amount of energy as oil and 25%
more energy than coal.
• The ash residues from tire derived fuel may contain lower
heavy metals content than some coals.