Environmental Impact Assessment - Mining and the Environment: From Ore to Metal - page 90

Products

Commodity Hydrate 141,000 t/yr
47,000 t/yr
180,000 t/yr
25,000 t/yr

Bauxite Ore from Mine Speciality Hydrate

Ore from Mine 1,852,595 t/yr

850,000 t/yr

Commodity Alumina

Washed Ore Speciality Alumina

BAUXITE PREPARATION
AND ALUMINA PRODUCTION

Water

Mine Wastes

Mining

Fresh Water from
River

Tailings
Bauxite Residue

1,002,595 t/yr
235,200 t/yr

Washing
Comminution
Digestion
Separation
Precipitation
Calcination
Power Plant
Other Supporting Activites

937 m 3 /hr

Energy
Coal

Gaseous Emissions
Power Plant
Alumina Plant

155,000 t/yr
11,040 m 3 /yr

110,000 dry Nm 3 /h
100,000 dry Nm 3 /h

Fuel (IDO)

Auxiliary Materials
Caustic Soda
Hydrate Lime
Sulphuric Acid
Flocculant

58,000 t/yr
9,000 t/yr
1,500 t/yr
120 t/yr

Aqueous Emissions
Waste Water Treatment Plant
Water Pool
Tailings Pond

28 m 3 /hr

664 m 3 /hr
200 m 3 /hr

FIGURE 2.6
Indicative Mine Inputs and Outputs
for a Hypothetical Maximum Mine
Operation Illustrated

a biologist, an environmental engineer, or a physicist reviews the mining project (a trend
often repeated by the approval authorities).
The review of the project design is critical. Is acid generation likely, and if so when and
where? Which metals are likely to remain in the mine waste, and at what concentrations?
Does the process produce acidic or caustic efl uents? Does an alternate tailings detoxii cation
scheme exist? What are the technical implications of relocating the mill site? Is backi lling
of tailings a realistic option? Admittedly the answer to most technical questions is best left to
the project proponent. After all, the mining company owns the EIA, and the preparation of
the EIA is a team effort: the mining company is providing technical expertise; environmen-
tal input is outsourced to environmental specialists. However, for the biologist, the environ-
mental engineer, or the physicist to meaningfully participate in the impact assessment, and
to ask the right questions, experience with and knowledge of the mining sector is essential.
A methodological approach to the project review will help. Firstly, what are the main
mine inputs and outputs (see Figure 2.6 as an example)?
The next question is: What characterizes emissions? For each emission stream (that is,
emissions to air, emissions to water and waste emissions), list source, quantity, quality or
characteristic, and discharge point and/or management option as illustrated in Figure 2.7 .
Once this exercise is completed, there is a good understanding of the various waste streams
and emissions associated with the mine development.

For the biologist, the
environmental engineer, or
the physicist to meaningfully
participate in the impact
assessment, and to ask the right
questions, experience with and
knowledge of the mining sector
is essential.

Assess Project Alternatives

The section in which project alternatives are addressed is often called the heart of an envir-
onmental impact assessment because it organizes and clarii es the choices available to the
decision makers. The project proponent, the approval authority, or the public can generate
alternatives, including the 'no action' alternative (see the section below on establishing the
environmental baseline). While generally the assessment of alternatives can relate to both
the design and the location of a project, alternative siting of a mine is understandably not an
option. However, alternative methods exist to accomplish the proposed action, such as differ-
ent mining and mineral processing methods, alternative size or production rate, different tim-
ing in mine development, different layouts of supporting mine infrastructure, and different

The credibility of the
environmental impact assessment
is at risk if the mine proposal
is identifi ed as the preferred
solution and is put into a
favourable light by comparing it
to poor or 'straw man' alternative
solutions.