VALUE FROM OLD MINES
subsequently recovered from solution using
hydrometallurgical standard techniques.
Bioleaching of refractory gold concentrates in
agitated tanks has become an established
commercial technology over the past three
decades and Mintek is one of the leading
technology suppliers.
Managing muckpiles
CSIRO, OLGA is now being field-tested at
Australian gold mines and should see OLGA
undergo full product release early in 2019.
Mintek water treatment
Mintek recently showcased a number of its
process technologies associated with tailings.
SAVMIN™is Mintek’s cost-effective technology
for the treatment of mine-impacted water,
including acid mine drainage (AMD). It is a
precipitation-based process, operating at
atmospheric temperature and pressure, and
removes heavy metals and sulphates from mine-
impacted water.
Mintek says implementation of the SAVMIN
technology has the following benefits:
n Can treat a variety of waste streams and the
process is not limited by the concentrations of
pollutants such as sulphates and heavy metals
n Can reduce sulphate concentrations to less
than 200 mg/litre
n Recovery of metals of interest and value
n Regeneration and recycling of the key reagent
aluminium hydroxide - thereby limiting the
operating costs associated with fresh reagent
addition
n Low electrical power consumption as the
process is operated at ambient temperature
and pressure
n Waste products from the process can be
disposed of as a stable waste or, in certain
instances, constitute a usable byproduct.
Biological Sulphate Reduction is a process to
remove metal sulphates from waste waters using
sulphate-reducing, naturally-occurring bacteria
that are immobilised on a suitable substrate,
such as woodchips. The process can be used for
the treatment of AMD to remove the sulphates
from solution and stabilise the toxic metal ions
present as metal sulphides.
The NICMembrane™ is a low-fouling
ultrafiltration membrane that can be used for the
treatment of AMD and mine-impacted water for
the removal of turbidity.
Metal Recovery through Ion-eXchange
(MetRIX™) is a continuous resin-in-pulp ion
exchange process for the removal of uranium or
base metals from dense slurries. The process can
operate with slurries containing up to 50% solids
and therefore does not require any upfront
filtration.
Mintek has conducted intensive research and
development over the past 10 years on the
recovery of uranium from low-grade uranium
slurries. Recent developments in the RIP
technology have focused on the recovery of base
metals from slurries. Evaluations have been
carried out on the recovery of nickel, zinc, cobalt
and copper at laboratory-scale, and zinc at pilot
plant-scale.
Some of the unique benefits of the MetRIX
process include:
n Elimination of solid/liquid separation steps;
the process recovers uranium and base metals
directly from leached pulp, consequently
lowering the capital and operating costs
n The RIP adsorption circuit, Stage 2 of the
MetRIX process, is a truly continuous, counter-
current circuit, resulting in reduced resin
inventory, improved control of resin residence
time, and minimise resin fouling and loss due
to breakage.
Finally, biological oxidation is a process to
extract precious and base metals from sulphide-
containing ore with the aid of naturally-occurring
micro-organisms. The micro-organisms act as a
catalyst and oxidise the solid metal sulphides
into soluble sulphates. The metals can be
First Cobalt Corp has begun a metallurgical study
on a high-grade inventory of refinery residue and
crushed waste rock material located near its mill
facility in the Canadian Cobalt Camp. This study
is intended to advance the company's early cash
flow strategy by assessing an optimal flowsheet
for recovering cobalt and silver.
The program will provide further insights into
opportunities for early cash flow from processing
surface muckpiles from historic underground
mining operations. The testing will be done on
three piles with a historic resource estimate,
prepared before the company acquired an
interest in the properties, totalling approximately
6,500 t with average grades ranging from 0.65%
to 1.55% Co (non-compliant with NI 43-101).
The test work is aimed at elaborating a
process flowsheet based on analytical
characterisation of the samples, gravity
concentration, hydrometallurgical recovery of
cobalt and silver, as well as arsenic removal and
stabilisation.
Success could have broader implications for
the ongoing assessment of processing options
for historical mine material throughout the
Cobalt Camp using First Cobalt's mill and
refinery.
First Cobalt has partnered with Dundee
Sustainable Technologies in Quebec to develop a
flowsheet for potentially processing the piles
using the First Cobalt mill equipment and the
First Cobalt refinery and to understand the
benefits of integrating Dundee's arsenic removal
and stabilisation technology. IM
MAY 2018 | International Mining 49