Environmental Engineering Reference
In-Depth Information
Exploration activities normally
continue throughout
the feasibility study, mine
development and operation.
From the environmental point of view two considerations deserve special attention. Firstly,
exploration activities normally continue throughout the feasibility study, mine develop-
ment and operation. The chances are that proven mineral reserves will increase as more
exploration data are generated, although the reverse may also occur. Generated volumes of
mine wastes may be well above the volumes estimated during the feasibility and the EIA
studies. Secondly, measured mineral resources may turn into proven mineral reserves in
time if mineral prices increase during the mine life, lowering the initially selected cutoff
grade. Mine operations may be adjusted accordingly with the need to re-visit the original
EIA study. Similarly, low grade ore temporally stockpiled for future ore processing might
turn into permanent waste rock dumps if mineral prices were to fall. The EIA practitioner
needs to appreciate these potential changes in future mine planning to adequately evaluate
environmental protection measures that are built into mine design.
Selecting the Preferred Opportunity Realization Concept
What objective? The conceptual study, also commonly referred to as a scoping study, is the
i rst level study and the preliminary evaluation of the mining project. The environmental
scoping study is part of the conceptual design phase with the main objective of identify-
ing 'fatal l aws' or 'show stoppers'. The principal parameters for a conceptual engineering
study are mostly based on broad assumptions. Accordingly, the level of accuracy is low at
about 50 percent. Although the level of drilling and sampling must be sufi cient to dei ne
a resource, l ow sheet development, cost estimation, and production scheduling are often
based on limited data, test work, and engineering design. The results of a conceptual study
typically identify: technical parameters requiring additional examination or test work;
general features and parameters of the proposed project; magnitude of capital and operat-
ing cost estimates; and level of effort for project development. A conceptual study is useful
as a tool to determine if subsequent engineering studies are warranted. However, it is not
valid for economic decision-making, nor is it sufi cient for reserve reporting.
The environmental scoping study
is part of the conceptual design
phase with the main objective of
identifying 'fatal fl aws' or 'show
stoppers'.
The Pre-feasibility Stage
What needs to be done? The pre-feasibility study represents an intermediate step in the
engineering process to evaluate a mining project. The principal parameters for a pre-feasi-
bility study are based on various engineering data. The level of accuracy is higher than the
scoping study at about 25 percent. At the pre-feasibility study stage adequate geology and
mine engineering work has been conducted to dei ne a resource and a reserve. Sufi cient
test work has been completed to develop mining and processing parameters for equipment
selection, l ow sheet development, and production and development scheduling. Capital
and operating cost estimates are derived from preliminary test work, assumed factors, and
some vendor quotes. The economic analysis of a pre-feasibility study is of sufi cient accu-
racy to assess various development options and the overall project viability. While cost esti-
mates and engineering parameters are typically not considered of sufi cient accuracy for
i nal decision-making or bank i nancing, the pre-feasibility study helps to dei ne the limits
of a deposit and its development. Typically the pre-feasibility study considers the following
categories of limitations:
●
The level of accuracy is higher
than the scoping study at about
25 percent.
Geological limits of the mineralization correspond to the distribution zone of known
mineral resources. These limits are liable to change in time as exploration activities
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