ARTISANAL AND SMALL-SCALE GOLD MINES IN BURKINA FASO ...

esult is a very incomplete mining of mineralized structures, which involves selecting the richest parts.
Because of insufficient pumping means, it is common to see high-grade (>50 g/t Au) ore from the
cementation zone remain in places below several metres of water. Another problem is that, because of a
lack of dynamite or sufficiently heavy mining tools, some well-mineralized parts of massive veins have to
be abandoned in favour of wall rock and fracture zones.
Generally speaking, in order to cover his relatively high operating costs and attain the precarious
financial equilibrium of his operation, the artisanal miner is constrained to process only the rich ore. For a
standard operation without pumping below 30 m, the cut-off grade is commonly 20 to 30 g/t Au. After
hand-sorting (‘cobbing’) the run-of-mine at the edge of the pit, the poorest ore is dumped as “waste” on the
tips, from where it may be recovered by the villagers (mostly women) or other miners who have just been
hired. Finally, our analyses have established that the recovery rates from processing are better than the 40%
estimated before in the literature, but still are only around 60 to 65%. An ore grading of 20 to 30 g/t Au
will, after three grinding and washing cycles, still produce tailings that grade eight to 12 g/t Au; in this
respect, the residual gold content was remarkably constant from one site to the next.
Where a massive gold-bearing vein is mined, only 20 to 40% of the potential reserves are recovered. In
short, because of their basic equipment, major technical constraints and high operating costs, the artisanal
miners of Burkina cannot prevent a “high-grading” of their resources. Figure 2 illustrates these problems.
Fig. 2 – Distribution of gold grades of a typical artisanal gold vein mine in Burkina Faso
A HIGHLY STRUCTURED AND JOB-CREATING ACTIVITY
Artisanal mines of Burkina Faso, commonly overpopulated, are striking in terms of their teeming and
abundant character. Some of these mines, such as Bouda (Passoré province) in 1991, or Mogrenore
(Boulgou province) in 1998, hosted up to 40,000 individuals during the paroxysmal phase of the gold rush.
Such abundant labour, outwardly excessive, is necessary because of the low level of material means
deployed. The activity is thus characterized by very low productivity, but a very large potential in terms of
available jobs:
- The actual extraction zone of the mine generally contains 30 to 40% of the active population on site
(not counting shops). This is the preserve of men, women and children being theoretically absent.
However, young boys of less than 15 years old can occasionally be seen hauling ore that was mined and
sorted at the bottom of the pit.
- The ore-processing areas and grinding shops, which can be several kilometres distant if there is
insufficient water on the mine site, host the remaining 60 to 70% of the working population on site.
These are occasional labourers coming from villages in the region, some from over 100 km away.
Here, the majority are generally women and children.
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