Quicklime is used to neutralise the acid
effluents generated by the acid plants
associated with copper smelters. Lime
products are also used to neutralise the
dumps in an effort to remediate acid mine
drainage (AMD).
In copper mining, about 80% of the
produced quicklime is used in flotation
processes. Depending on the ore to be
treated, the quicklime unit consumption
value ranges from 1.5 to 1.7kg/ton of
processed copper ore.
The major copper-producing countries
like Zambia and Chile have domestic supply
of lime and can produce limited amounts
of quicklime. The domestic production,
however, does not meet the annual demand
and these countries are dependent on
import. In the case of Zambia, quicklime is
also imported from South Africa, and Chile
imports from Argentina.
“The quicklime market was significantly
affected by the worldwide economic
downturn and on average, the demand
decreased by about six per cent per year
since 2012,” says Scott. The situation is
estimated to turn around with the current
commodity price uptick and
market recovery anticipated
in 2019.
Quicklime prices are
not readily available, but
the average selling price in
2015 was USD156.70/ton. In
the period 2005–2015, the
average year to year increase
in quicklime prices were
9.9%, with the trend set to
continue for the near future.
Limestone is mined from a number of quarries around
This scenario is dependent
the country.
on the assumption that
quicklime import volumes do
not increase substantially, and no new
The downside potential is that the
quicklime production projects come
production of quicklime is highly fossil-fuel
into full production in the next two to
intensive and it produces large amounts
three years. The consumption of lime
of CO 2 , subsequently being the focus
is most likely to remain stable as a pH
of environmental concerns. Although
modifier and acid neutraliser in the
smelting remains the preferred method of
production of copper cathodes. In the
processing, hydrometallurgical processes
absence of any cheaper replacement
are being refined and may take a larger
product and in the increase of demand,
portion of the market in future. Research is
particularly from the copper-producing
being conducted to reduce the consumption
industry, demand is set to increase for
of lime in flotation of copper- and nickel-
the near future.
bearing minerals. ■
QUARRY SA | JULY/AUGUST 2018 _ 35
BUSINESS