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4.7 Water Recycling -- Tarkwa Gold Fields, Ghana
In this process, groundwater and wastewater from drilling operations are
pumped into an underground sump. The sump water is raised in stages into a
surface reservoir where it is mixed with raw water pumped from streams.
The water in the reservoir is allowed to settle.
Through this process of dilution and sedimentation, water quality is
improved, and the water is then recycled for use in underground mining
This technology is described in Part B, Chapter 3, "Mining and
Extent of Use
This technology is used by mining operations in the Tarkwa gold fields
Operation and Maintenance
This is a very flexible system, quick to install and designed to provide
only a limited supply of process water to any location where water is
needed. The pumps normally operate 10 hours per day.
Level of Involvement
This technology is industry-specific and is generally operated as part
of the production process within the specific industry. Trained personnel
are needed to maintain the pumping systems.
Costs are difficult to determine, but capital costs can be assumed to be
high given the need for pumps, pipelines and related equipment. Operating
costs, however, are probably similar or somewhat less than the costs of
using raw water for the same operations.
Effectiveness of the Technology
And water supply. It has proven to be very effective in conserving water
resources, while meeting the production demands of the industry.
Water re-use systems can be installed in any sub-surface mining
operation. The possibility of including a water treatment system within
the pumping network, to upgrade water quality if necessary, is high.
By containing the contaminated water generated in sub-surface mining
activities, direct pollution of surface water resources is minimized.
Contaminants are typically sediments and other dissolved chemicals which
are amenable to removal using conventional treatment methods. However, the
disposal of waste products should be monitored to limit negative inputs on
Use of this technology limits the pollutant load to surface and ground
The technology, which is based on pumping, has a high energy demand.
Further Development of the Technology
The advantages to be gained from using this system depends on the
quality of ore purification to be achieved, and the chemical processes
used. Therefore, any future development of the technology has to be in the
area of in-line water quality improvement.
Goldfields Corporation, Tarkwa and Ashanti Goldfields