NEWS
Poor blasting practices erode
mines’ financial bottom lines
and are bad for the environment,
according to BME technical
director, Tony Rorke.
Highlighting that many
greenhouse gases are generated
in the explosives chain, Rorke
says that nitrous oxide (N 2 O)
is particularly dangerous – at
almost 300 times more harmful
to the climate system than
carbon dioxide.
“Ironically, there is little
public awareness of N 2 O, which
is why it is sometimes referred
to as the ‘forgotten’ greenhouse
gas,” says Rorke. “However,
containing N 2 O emissions can
also present an opportunity to
mines and other explosives users
to significantly improve their
carbon footprint,” adds Rorke.
Rorke emphasises that there
are other downstream activities
on a mine that also contribute
to the operation’s carbon
footprint – and which can also
be improved to result in less
Blast better for greener results
Blasting rock releases greenhouse gases.
CO 2 emissions. Research shows
that for every cubic metre of
rock mined, about 4kg of CO 2
is produced by the explosives,
5kg of CO 2 by the process of
loading and hauling and 27kg
of CO 2 by crushing and milling
– a total of 36kg.
An important negative
result of a bad blast is difficult digging conditions – loaders
will struggle to dig where the
required fragmentation has not
been achieved, which means the
machines will burn more diesel
and emit more CO 2 . Coarser
fragmentation also leads to
less efficient functioning of
the crushers and the mill,
which will in turn consume more electricity – also a major
greenhouse gas contributor.
“By blasting badly, a mine will
also effectively be losing ore; so,
despite creating all these extra
greenhouse gases, there is even
less ore to show for it,” says Rorke.
“The result is that more mining
is necessary to reach targeted
production levels.”
Africa’s GDP. After reaching an
eight-quarter high of 127 at the
end of 2016, the ACI declined for
two successive quarters before
recovering in the third quarter.
It increased again in the fourth
quarter of 2017 by 1.9% to reach a
level of 125.4 (see graph 1). The construction sector at
large continues to outperform
the economy as a whole by
a considerable margin, with
the ACI having expanded by
25.4% since the third quarter
of 2010 (the base period). This
is substantially higher than the
rate of growth of 15.8% for the
economy over this period (in
real terms).
Andries van Heerden, Afrimat
CEO, says that the results of the
ACI fourth quarter numbers are
encouraging and he is hopeful
that the positive trend will flow
into the first quarter of 2018.
“We witnessed a reduction
in sales volumes during the
last quarter of 2017, with
the slow-down exacerbated
in November and December
in construction material products. This was felt more
strongly in KwaZulu-Natal
and southern Gauteng,
where our Glen Douglas and
Clinker operation experienced
reduced volumes. We
nevertheless are optimistic
about the change in leadership
of the country – there is
no doubt that the political
uncertainly of the last few
months of 2017 worsened the
situation,” says Van Heerden.
He adds that it is heartening
that President Ramaphosa
is directly addressing issues
the people of South Africa
face, that incorporates public
private partnerships as well
as addressing failings within
certain state-owned enterprises,
where various bottlenecks make
service delivery a problem.
ACI gains steam
Afrimat recently released
the findings of the Afrimat
Construction Index (ACI) for
the fourth quarter of 2017.
For the three months between
October and December 2017,
the trend broadly followed the
upward movement of South
8 _ QUARRY SA | MAY/JUNE 2018