MINING CHEMICALS
Reagents for harsh waters
Clariant Mining has many years of experience in
modern explosive emulsifier technology
currency and reached CHF347 million, bolstered
by acquisitions. In the difficult industry
environment, the underlying Oil and Mining
Services sales were slightly negative, but were
helped by acquisitions. Functional Minerals
continued its solid growth development. Sales
in Catalysis were up by 2% in local currency to
CHF142 million with a soft demand recovery in
the Asian and European markets.”
BASF’s Mining Solutions business has been
able to improve gold processing circuits around
the globe and has recently been active in West
Africa. One key to success has been the
extensive test work and subsequent benefits
that Rheomax ® DR1050 has provided.
The first visit to Ghana took place in 2014.
After systematic visits and laboratory
evaluations, DR1050 was found to give
promising performance in thickeners, and plant
trials were conducted in 2016. The trials showed
a significant reduction in tailings volume and
polymer consumption. Unlike in many other
African countries, water scarcity is not as big a
challenge in Ghana. However, the cyanide leach
process defines strict environmental limitations
and water reuse is essential for the process
circuit.
A pre-leach thickener (PLT) was performing
well with the incumbent flocculant, but due to
solution make-up station limitations a new
flocculant was introduced. DR1050 was found to
be very reactive and very dose-effective. The
dose requirement was over 30% lower. The
objective was to keep underflow density as
stable as possible, which was successfully
achieved.
Feed slurry from CIL leach tanks is washed in
counter-current decantation (CCD) circuit, which
consist in this case of two thickeners. Underflow
densities had been too low and solids had been
10 International Mining | JUNE 2017
going to run off and a process water pond. Due
to volume constraints in the process water
pond, the focus was to improve CCD2 underflow
density. This would minimise the water outlet to
tailing storage facilities and improve water
recovery and reuse in mining operations.
With Rheomax DR1050, it was possible to
achieve ~7% higher underflow densities without
compromising rake torque and underflow
pumping. This improvement corresponds to
close to 300 m³/h less water to tailings facilities.
Simultaneously, the flocculant dose amount was
decreased by 30%.
In previous studies, it has been found that
Rheomax gives a more stable performance and
less process fluctuation.
The customer was happy with BASF’s
achievements and committed project team. The
next step is an extended six-month trial
campaign with improved process control to
eliminate process variations as much as
possible.
The current focus of Flottec’s research efforts is
to understand how its reagents behave in harsh
waters including sea water and brines. Frank
Cappuccitti, Flottec President told IM: “Many
new operations are faced with poor quality
waters which greatly affect the flotation
performance. We have created new reagents for
control of soluble activating ions in solution in
harsh water and conducting research on how
frothers behave in these types of water.
Previous research has shown that ionic strength
of the water creates small bubbles without
frother. So frothers are needed more for their
froth creation than bubble reduction properties.
Initial observations show that frothers seem to
be less strong in harsh waters than fresher
waters. Our research work this year will centre
on understanding the mechanisms of frother
behaviour in harsh waters and determining how
the chemistry of frothers need to be modified for
these types of conditions.”
Another focus area is on better hydroxamic
acids. Over the last several years, there has
been a renewal of interest in