The development of gold recovery technology from pyrite-pyrrhotite-bearing
ores
V.M.Mullov, L.V.Kin, O.D.Khmelnitskaya, V.V.Lodeischikov, A.V.Yevdokimov, S.V.Petrov
IRGIREDMET JSC, 38, Gagarina blvd., Irkutsk, 664025, Russian Federation
E-mail: ianayko@gmail.com
Currently, processing of refractory ores containing pyrrhotite poses an actual problem. Typically,
flow sheets based on gravity separation and flotation followed by lime treatment and cyanidation
of the resulting concentrates are used to process these ore types.
IRGIREDMET Institute developed a flow sheet to recover gold from refractory ore from a
Russian deposit. The ore contained 1.32 g/t Au, 1.3% of pyrite and 2.2% of pyrrhotite. The
recovery of gold achieved was 89.6% using gravity with generation of high grade recoverable
gold concentrate and gravity middlings. In the course of lime treatment, cyanidation of the
middlings followed by tailings detoxification the consumption of reagents was 13.0 kg/t CaO, 95
kg/t NaCN and 72 kg/t Ca(OCl)2 of the concentrate. This was capital intensive.
In order to decrease the consumption of reagents, magnetic separation of the middlings of the
concentrates gravity separation and the filtration of the slurry after lime treatment combined with
the polysulfide-containing solutions discharge were added to this flow sheet. Pyrrotite recovered
to magnetic fraction, which did not contain gold in accordance to this advanced flow sheet. The
mass yield of pyrite gold-bearing non-magnetic fraction decreased down to 1.5 times in relative
to gravity middling. The slurry filtration prior to cyanidation allowed the organization of cyanide
solution recycling.
The results of pilot plant tests using the developed flow sheet showed that the content of
pyrrhotite in the magnetic fraction decreased from 59.1% to 11.3%. The reagents consumption
was 12 kg/t CaO, 3 kg/t NaCN and 16 kg/t Ca(OCl)2 of the concentrate. The total gold recovery
using this flow sheet was 86%.
The results obtained were used in the project design criteria to design a processing plant with the
annual throughput of 2.6 million tonnes of ore.
KEYWORDS
Pyrite-pyrrhotite-bearing ores, gold, gravity, magnetic separation, cyanidation, recovery