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Jul 3, 2024Keywords:
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Main Article Content
Causes and consequences of inefficient drilling and blasting in mine development headings: A case study of hard rock gold mining operations in northern Tanzania
Abstract
Despite the introduction of the perimeter blasting technique at the
Tulawaka Gold Mine, the mine continued to suffer from an overbreak
of mine development headings, with an average overbreak of 24% every
22 m, which is approximately twice the acceptable 10% overbreak. The
causes of this problem include ineffective drilling practices and uneven
and excessive charging of explosives, resulting in a slightly high
powder factor of 3.94 kg/m3
instead of 3.8 kg/m3
, as per the design. The
problem of overbreak resulted in ore dilution, a longer mine
development cycle time and additional costs of approximately US$ 45
per cut, especially in mucking and hauling processes. This study
proposed and recommended new drill and blast designs to solve this
problem. Compared to the existing design, the proposed new drill
design has a total of 12 fewer drill holes; this is a significant number
of holes, which significantly reduces drilling costs. The proposed new
blast design consumes approximately 25 kg less ANFO than the existing
practice. Moreover, the study showed that large drives in the Star and
Comet in the Geita Gold Mine suffer the most from the problem of
ineffective advance per cut. One of the causes of ineffective advances
per cut is the low amount of explosives used per cut compared to the
planned amount.
