An Introduction to Mining and Metallurgy - Thanatia: The Destiny of the Earth's Mineral Resources - page 176

7.6.1.4 Air pollution
Fossil fuel consumption either for electricity production or for materials transport
and handling emits enormous amounts of GHG. In the future and within the frame-
work of sustainable mining, mining facilities will need to apply either carbon capture
and storage (CCS) or intensive renewable energy use. Such abatement costs will
raise mining expenditure 11 . The use of diesel oil in transport, for example, will need
to be replaced with alternative means such as electrical conveyors or cleaner fuels.
GHG emissions aside, mining companies may have specific hazardous airborne
emissions such as those of mercury and lead. Lead may provoke neuropsychological
effects and cognitive defects, especially in children. Meanwhile mercury, if inhaled,
is physiologically converted into methyl-mercury which is one of the most power-
ful neurotoxins. And, according to the U.S. Toxic Release Inventory 12 , the metal
mining industry is responsible for approximately 9% of all U.S. industrial mercury
emissions to air.
Other metallic pollutants caused by mining are As;Sb;Be;Cd;Cr;Co;Cu;Mn
and Ni. Finally, diesel combustion and electricity production also emit a number
of polycyclic aromatic hydrocarbons (PAH) and other non-metal compounds that
should be monitored. In fact, good monitoring and an oversight with transparency
will help avoid both short and long term (latent) catastrophic failures.
7.6.2 The environmental impact of smelting
Smelting processes generally need a reducing agent, a solvent to facilitate the reac-
tion and high temperatures to melt the ore. The necessary temperature is obtained
from the combustion of a fossil fuel, usually coal. The oxide reducing agent is ge-
nerally coke and the solvent, or flux, limestone. If the process is electrochemical,
electricity is required, which is usually generated from coal combustion. This pro-
duces staggering amounts of CO 2 . Other air pollutants may also be emitted such
as sulphur dioxide originating from sulphide smelting and hydrogen fluoride from
aluminium processing. Fugitive gases can also produce smog, ozone, nitrogen and
sulphur oxides, carbon monoxide and particulate material, thus contaminating the
surrounding environment, including soils and waterways. The large volumes of sul-
phuric acid used in metal production are another important issue which can lead
to acid rain.
The solid waste slag meanwhile produced by smelters contains significant
amounts of heavy metals (lead, cadmium, arsenic, chromium, mercury, nickel, cop-
per, selenium and/or zinc) that require appropriate treatment in order to avoid
metal-bearing dust particles and wastewater.
11 Furthermore, the polluters pay principle means that at the final link of the chain, consumers
need to be aware of the environmental impact of mining and pay for it.
12 Toxic Release Inventory (TRI). http://www.epa.gov/tri/. Accessed April 2013.