Environmental Engineering Reference
In-Depth Information
caving operation or support itself in an underground mine. Metallurgical treatment meth-
ods can be most effectively researched by pilot testing techniques, and disposal of waste
can be carefully researched using the waste from these original testing programmes, with
the crushed bulk sample fed into a pilot plant.
Typically, large-scale bulk sampling is undertaken in the last stages of exploration of a
low grade ore deposit to be developed by open pit methods. In a major project, bulk sam-
pling provides sufi cient ore to operate a pilot plant with a capacity of 50 to 100 tons per
day for several months. The pilot plant may be established on-site, but more commonly, a
pre-existing off-site plant will be used, with the bulk sample shipped to that facility. Bulk
sampling takes on the character of a small-scale mining operation with all its related envi-
ronmental impacts, requiring its own environmental permit.
The pilot plant is a miniature version of the full-scale plant to be built to concentrate the
ore from the mine. The design of the pilot testing plant is based on knowledge of the type
of ore in the deposit and the details of bench testing of ore from exploration core drill-
ing. Details of crushing, grinding, concentration characteristics, and waste disposal can be
studied over a period of time in a pilot plant. Also considered are the effects that a change
in one part of the process will have on another, as well as the overall efi ciency of the pro-
cess. Depending on the results, alterations are made in the design of the full-scale plant.
Costs of construction, operating costs, and waste disposal problems can be determined for
use in broad planning and in the i nal feasibility study.
Typically, large-scale bulk sampling
is undertaken in the last stages of
exploration of a low grade ore
deposit to be developed by open
pit methods.
Greenfi eld and Brownfi eld Exploration
Exploration is termed either Greeni eld or Browni eld, depending on the extent to which
previous exploration has been conducted on the target area in question. While loosely
dei ned, the general meaning of Browni eld exploration is that which is conducted within
geological terrains within close proximity to known ore deposits or within a known min-
eral province. Greeni elds are the remainder.
Greeni eld exploration is highly conceptual, relying on the predictive power of ore gen-
esis models to search for mineralization in unexplored virgin ground. This may be terri-
tory which has been drilled for other commodities, but with a new exploration concept is
considered prospective for commodities not sought there before.
Greeni eld exploration has a lower strike rate, because the geology is poorly understood at
the conception of an exploration programme, but the rewards are greater because it is easier
to i nd the biggest deposit in an area earlier, and it is only with more effort that the smaller
satellite deposits are found. Also, the explorer making the i rst discovery in a Greeni eld area
may be able to secure exploration rights to most or all of the prospective ground, whereas, in
Browni eld areas exploration and mining areas are commonly fragmented and new discov-
eries may extend into areas controlled by competitors. Browni eld exploration is less risky, as
the geology is better understood and exploration methodology is well known, but since most
large deposits are already found, the rewards may be incrementally less.
4.3 FEASIBILITY - IS IT WORTH MINING?
The evaluation of a mineral
deposit from exploration
through development and
production is a lengthy and
complicated process.
In mineral exploration, something is always better than nothing ( Figure 4.7 ) and, when
successful, exploration delivers the discovery of a mineral deposit. But is the discovery
worth mining? The evaluation of a mineral deposit from exploration through development
and production is a lengthy and complicated process. Determining the technical and
 
Search WWH ::




Custom Search