FLOTATION
productivity improvement on the cells using
REXA actuators was noticed in less than two
weeks and the copper mine promptly ordered 22
more of these actuators. For 2017, the mine
planned to install ~38 REXA actuators to retrofit
all of the actuators to REXA on the rougher
banks.
Reagent refinements
One paper at the Flotation ’17 conference in
November by Tarun Bhambhani, D.R. Nagaraj and
O. Yavuzkan (Cytec Solvay Group, USA) was
Improving flotation recovery of oxide copper
minerals. Bhambhani explains: “In mixed
oxide/sulphide type orebodies, there is the dire
need to improve the recovery of oxide Cu
minerals. In particular, certain minerals like
chrysocolla and pseudomalachite do not respond
to the traditional reagent scheme (i.e. controlled
potential sulphidisation or CPS, as described
below).
“Alkyl hydroxamates have long been known as
collectors to float these minerals. However, they
have remained a laboratory curiosity, with almost
no plant scale applications. The application
knowledge for hydroxamates is lacking,
particularly the use of these reagents alongside
sulphidisation. In this paper we include case
studies to achieve improved recoveries using
hydroxamates in conjunction with sulphidisation.
One size definitely does not fit all.”
The paper explains that the recovery of oxide
Cu minerals by flotation is a longstanding
challenge, especially for ores not economical for
direct acid leaching. Current practice involves
sulphidisation using NaSH or Na 2 S) followed by
flotation using traditional sulphide collectors.
CPS has been shown to improve recovery of oxide
Cu but is not a satisfactory solution because of
HSE issues, high consumption of NaSH, and
inability to recover minerals refractory to
sulphidisation.
Numerous collectors have been evaluated for
direct flotation (i.e. without sulphidisation) of
oxide Cu minerals, the most researched of which
is alkyl hydroxamate. While there are numerous
p