FLOTATION_proof 25/05/2016 10:20 Page 7
FLOTATION
percent of solids, and particle grind size.
Clariant Mining Solutions considers that
product innovation doesn’t always originate from
strictly a pricing strategy. This holds especially
true when it comes to flotation chemistry for the
collection of precious metals. A variety of factorsregulatory, environmental and safety- often
coalesce to make a once-standard collector more
challenging to use.
Alkali metal xanthate has been one of the most
important classes of collectors for use in
sulphide mineral flotation applications. The lowcost commodity is often used in flotation
schemes where selectivity between various
sulphide minerals is not critical. When high
selectivity is required, xanthate may act as a
scavenger or secondary collector in a multicollector system.
Clariant says that “while important, critical
safety and handling drawbacks are making the
use of xanthate collectors more challenging and
expensive. Rated as flammable, powder and
pellet xanthates are more difficult to transport,
which can increase lead times, and the emptied
containers are problematic to dispose. For new
plant construction, significant infrastructure
investment is required for xanthate storage.”
On the production side, workers must mix
xanthate collectors in a water solution, exposing
them to xanthate dust and foul odours. Since the
mixture is unstable, the solution is typically
prepared up to three times per week, increasing
operational costs.
The decomposition rate of a xanthate solution
is 1-3% per 24 hours at 20°C and increases
sharply above 40°C. For this reason, if a mine has
a xanthate collector delivered in solution, it is
mixed at a much higher, 25 to 30%, concentration
in water, which must be consumed within three
weeks.
“Significant progress has been made in the
development of new, more sustainable
alternatives to hazardous xanthate collectors.
Working with mines globally, we developed the
HOSTAFLOT® collector line as safer alternatives to
xanthates,” says Jorge Arias, Global Head of
Technology for Clariant Mining Solutions.
The chemical supplier recently worked with a
copper producer, who was starting a new
flotation plant, to develop a cost-effective
alternative to a proposed 50/50 mixture of
sodium ethyl xanthate (SEX) and sodium isobutyl
xanthate (SIBX) collector. The producer wanted
to avoid building a large storage facility for the
powder, eliminate bi-weekly solution preparation,
remove the need to discard contaminated
packing, and replace the proposed two-collector
system with a single collector.
Using ore samples collected from mines
operated by the producer, Clariant scientists first
determined the samples’ content values. “We
developed experiments to compare performance
characteristics between our HOSTAFLOT and the
SEX/SIBX collectors,” comments Jacques
Bezuidenhout, Senior Metallurgist, EMEA region
for Clariant. “We also tested the performance
effects of storage temperature on the two collectors.”
For the initial flotation performance test, the
Clariant and xanthate collectors were prepared
freshly as a 1% solution. All collectors showed
excellent recovery, each exhibiting a greater than
90% cumulative copper recovery