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The work involves the evaluation of physical and chemical
factors that influence the processing of sulphide ores,
with the lowest grade of gold known in the world. The
studied sample is from Rio Paracatu Mining S.A. and is
described as Calha Brava Cl-4, belonging to the 716 bench,
block 508-B in the mine. Some industrial processing of gold
include gravity concentration and flotation processes
in order to reach the maximum gold recovery, aiming at
raising production levels with lower costs. The selection
of the mineral processing depends on several factors as
mineralogy, particle size distribution and other minerals
associated with the ore. The distribution of gold grades to
the different size fractions in the studied ore, reveals
that 80.48% of gold occur in the particle size fraction
above 104 um, and 25% of gold occur in the fine fraction (<
28 um). The global gold, sulphur and arsenic recoveries,
obtained by centrifuge gravity concentration (Knelson)
and flotation tests, were 80.44%, 64.90% and 58.22%,
respectively. To these processes, the mass recovery was
10.14%. The total gold, sulphur and arsenic recoveries
obtained in concentration processes by jig and flotation
techniques were 88.91%, 86.82% and 49.07%, respectively.
The mass recovery was 19.5%. In the flotation tests, the
maximum gold recovery (87%) was obtained with the grounded
ore (P80 = 86 um), using 30 g/t collector potassium amyl
xanthate (PAX), 20 g/t methyl isobuthyl carbinol (MIBC), pH
= 6.3 and potential of pulp 0.209 V vs Eh. The mass
recovery was approximately 4%. When coarse particles
(P80 = 130 um) were floated, the need of am increase in the
collector concentration was observed. The maximum ore
recovery (85.33%) was obtained at concentration of 60 g/t
PAX, pH = 6.3 and potential of pulp 0.218 V vs Eh. The
mass recovery was 9%.
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