Environmental Engineering Reference
In-Depth Information
Atmospheric emissions may contain only gases, only particulate matter, or a combination
of both. Considering the use of sulphide ores, copper smelters, lead smelters, and zinc roast-
ers produce huge amounts of sulphur dioxide. In copper smelting, for example, typically
more sulphur dioxide is produced by weight than copper. Rather than discharging sulphur
dioxide into the air, as was once the practice (e.g. The Mount Isa Mine in Australia released
all of its sulphur dioxide directly to the atmosphere as recently as 1999), more than 99 per-
cent of the sulphur dioxide is now captured. The standard technique to limit sulphur diox-
ide emission is to convert sulphur dioxide to sulphuric acid, a valuable by-product. Common
technologies to capture particulate matter include electrostatic precipitators and bag houses.
In the USA, smelter-produced sulphuric acid amounts to approximately 10% of the
total acid production from all sources. Prior to the mid-1980s, this by-product sulphuric
acid was mostly sold as a raw material to other industries such as the fertilizer industry,
often at a loss due to the long shipping distances involved. Today mining operations them-
selves increasingly use sulphuric acid for hydrometallurgical processing of oxide ores and
sometimes of tailings as discussed in the earlier sections of this chapter.
Schlesinger (1991) established the global sulphur cycle, illustrating how liberation
of elements from the Earth by the extractive industries has resulted in regional and glo-
bal impacts, primarily the generation of acid rain and its subsequent impacts on natural
ecosystems ( Figure 6.13, Case 6.5 ). The numbers may have changed since then but the
underlying message remains the same (Jordan and D'Alessandro 2004). The major pool
of sulphur in the global sulphur cycle is found in crustal minerals, gypsum, and pyrite
(Schlesinger 1991). Many metals are mined from sulphide minerals. Sulphur is also an
important constituent of coal and oil, and large amounts of SO 2 are emitted during the
combustion of fossil fuel and the smelting of metal ores.
Coal and petroleum extraction mobilizes about 149 million tons per year (Mt/y) of sul-
phur, more than double the amount produced 100 years ago (Brimblecombe et al. 1989),
and almost twice the amount naturally liberated from the Earth's crust. Of this, about
93 Mt/y is released to the atmosphere, about twice the natural (volcanic, dust and biogenic
gases) emissions ( Figure 6.13 ). Human activities contribute the largest atmospheric sulphur
Large amounts of SO 2 are
emitted during the combustion
of fossil fuel and the smelting of
metal ores.
Anthropogenic
Emission 93
(80 to 85% due
to combustion
of fossil fuel;
remainder wastes
coming from
smelting of ore)
Transport to Sea 84
Transport to Land 20
Sea Salt
Spray
144
Biogenic
gases
43
Biogenic
gases
22
Wet and Dry
Deposition
64
Deposition
258
Volcanos
10
Volcanos
10
Dust
20
FIGURE 6.13
The Global Sulphur Cycle Emphasizing
the Role of Extractive Industries
Natural Weathering
and Erosion 72
Despite the relative insignificance of
human inputs to the global sulphur
cycle, anthropogenic atmospheric
emissions due to smelting, fossil fuel
combustion and other activities are
more than 10 times the emissions
from natural sources.
Source: Jordan and D'Alessandro 2004,
Schlesinger 1991
Mineral
Extraction
149
Pyrite
39
Hydrothermal
Sulphide
96
Figures in Mt/y
 
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