Industrial Ecology and the Geoenvironment - Sustainable Practices in Geoenvironmental Engineering - page 118

found in the efluents can also originate from cold reduction mills, electrolytic tin lines,
and a variety of machine shop operations.
Water leaving the wet dust cleaners usually contains anywhere from 1000 to 10,000 mg/L
of suspended solids, depending upon the furnace burden, furnace size, operating meth-
ods employed, and type of gas washing equipment. Disposal of these onto the land envi-
ronment will require treatment and containment to minimize ground, groundwater, and
receiving water contamination. Some of these aspects will be discussed in Section 4.4.3
when sustainability targets are considered. The more detailed treatment will be found in
Chapter 9.
4.4.2 Nonmetal Mineral Resources Processing
Nonmetal mineral resources include (a) clays and clay minerals, (b) crushed stone, (c) sand
and gravel, (d) dimensional rock slabs such as granite and marble slabs, (e) phosphate,
(f) potash, (g) gypsum, (h) peat, (i) sulfur, (j) diamond, (k) vermiculite, and natural alkali.
Examples of utilization of the minerals supplied by upstream mining and processing
industries include
• Clays —for pottery and ceramics industries; construction industries involved in
the construction of roadway ills, embankments, and clay-engineered barriers
• Clay minerals —for paper coatings in paper industries, as catalysts for chemical
industries; as expandable slurry materials (bentonites) oil exploration industries
and also construction industries
• Crushed stone, silica, sand, and gravel —glass industries, smelting industries (silica
used as lux material) concrete production industries, bituminous concrete indus-
tries, cement industries, construction industries
• Dimensional slabs —construction industry
The two minerals chosen as examples to illustrate the geoenvironmental interactions
of activities of downstream industries transforming nonmetal minerals obtained from
upstream mining-extraction industries are the kaolin clay mineral and limestone. Figure
4.4 shows the principal steps taken to produce coatings-grade kaolin for use as kaolin-
based coating pigment for the paper industry or in other industries such as latex and alkyl
paints and primers. The process is not energy intensive in comparison to the metal indus-
tries and cement production industries and the discharges from the processing technique
can be controlled. These discharges are the clay impurities and the iron and titanium
“impurities” that are generally associated with kaolinites. The iron and titanium can be
captured and reused for other applications. Insofar as geoenvironmental interactions are
concerned, this downstream industrial activity is relatively benign.
The use of limestone for production of cement is shown in a simpliied schematic in
Figure 4.5. In respect to geoenvironmental interactions, two signiicant factors are evident:
(1) intensive energy consumption attends almost every step of the production procedure,
especially in the cyclones preheating stage and in the rotary kiln, and (2) discharge of
fugitive cement kiln dust (CKN) as airborne particulates and as land discharge from elec-
trostatic precipitators (ESPs) and other kinds of scrubbers, etc.
The signiicant human health issues attending the emission of CO 2 , NO x , SO 2 , dioxins,
and furans cannot be ignored. For example, the release of metals into the atmosphere by
copper-Ni reining, fossil fuel combustion, and iron manufacture in the northern former