Abstract (EN):
The mineral raw-materials are non-renewable resources and those of better quality
are being quickly depleted, so it becomes more and more necessary to preserve
them for nobler ends, and to treat those of inferior value in order to improve their
quality. Moreover the globalisation of the market increased the number of demanding
consumers, who will not tolerate products without quality, as well as of foreign
suppliers with capacity to fulfil the required specifications. All these prerequisites
force the producers to look at the possibility of having to valorise their raw-materials.
In the case of metallic ores, most of the mines that were still in operation until the
beginning of the eighties, were closed down. Only the high grades and tonnage of
Neves-Corvo (massive sulphide, bearing mainly Cu and Sn) and Panasqueira
(hydrothermal deposit, mainly containing W, Sn and Cu) Mines, allow their current
labouring, although also dependent on external factors.
From mid-nineties, a decrease in the production of the mining subsector was
registered, as a consequence of the fast regression that was verified in metallic,
precious and energy ores. This was caused by a decrease in the international
quotation of precious and base metals and the reduction in the production of energy
minerals: coal and uranium. In the case of coal, the extreme consequence was the
closing down of Pejão Mine, situated near Porto, in the North of Portugal. In the case
of uranium it was the decrease in its importance, as an energy mineral, that
contributed to the reduction of this subsector.
In the case of the ornamental stones, industrial minerals and non-metallic ores, due
to their more common occurrence at the surface or at low depths, they could, most of
the times, be used in industry as R.O.M. or after very little beneficiation.
In Portugal there are mineral resources, which are reasonably well studied, of which,
due to their importance and meaning, the following should be pointed out.
Language:
Portuguese
Type (Professor's evaluation):
Scientific
Contact:
mldinis@fe.up.pt