Institut za rudarstvo i metalurgiju Bor

Table 2. Degrees of metal leaching with
water from concentrate after
sulphatization
Element Leaching degree, %
Cu 96.7
Fe 98.3
Ag 0.2
In the first phase of leaching, the zinc,
copper and iron are removed from concentrate.
The second phase is presented by the
cyanide leaching for the aim of silver
transfer into solution.
Cyanide Leaching of Silver
Laboratory investigations for cyanide
leaching experiments on samples were
carried out on the sulphatization process
products after the recovery of copper, zinc
and iron.
Leaching parameters are:
• Temperature: 25 o C
• S:L ratio: 1:2
• NaCN concentration: 0.15%
• Stiring rate: 800 min -1
• Oxidant: oxygen
• Leaching time: 8 h
• NaOH concentration: 0.03%
• pH: 10 - 11
The result of cyanide leaching test, obtained
after 8 h of leaching, was 71.8 % Ag.
Silver Leaching with Thiourea Directly
from Concentrate
The test of untreated concentrate leaching
was carried out with thiourea as the reagent.
The main advantage of this reagent is
that it eliminates the pre-treatment concentrate
processes of roasting and leaching. The
economic effect is also achieved since leaching
is the process with small power consumption
(at temperature of 40 o C).
A sample of 100 g of sulphide concentrate
was treated with thioruea solution and
addition of oxidizer at temperature of
40 o C. The results are shown in Table 3.
Table 3. Metals leaching degree
Element Leaching degree, %
Ag 47.40
Zn 2.76
Fe 14.01
Pb 0.008
Cu 1.16
This preliminary test has shown that
the silver leaching from untreated concentrate
is possible. The following investigation
will be aimed to the defining of optimal
technological leaching parameters.
CONCLUSION
Based on the obtained experimental results
of investigation the silver leaching
from sulphide concentrate from the
»Rudnik« mine, it could be concluded the
following:
1. Low temperature sulphatization of
concentrate leads to the destruction
of present metal sulphides
2. Leaching degree of non-ferrous metals
(copper, iron and zinc) over 95 %
was obtained by leaching of
sulphatization products with water
3. Silver leaching degree of 71.8 % was
obtained by cyanide leaching of
silver in the presence of oxidant
4. Silver leaching degree of 47.4 % was
obtained by direct leaching of silver
with thiourea from concentrate.
Acknowledgements
The authors are grateful to the Ministry
of Science and Technological Development
for financial support (Project TR :
19002)
No 1,2010. 87
MINING ENGINEERING