Pulacayo Project Feasibility Study - Apogee Silver

Pulacayo 1 000 t/d Phase I Feasibility Study - NI 43-101 Technical Report
090644-3-0000-20-IFI-100
13.3.3 Flotation Test work
Twelve (12) open circuit flotation tests (OCT were conducted on each of the samples PUL-
HG and PUL-LG. These tests were carried out to confirm the previous flotation results (UTO)
and to evaluate the effect of flotation response at a finer grind sizes as seen in the flowcharts.
The slurry samples were pre-treated with activated carbon to adsorb the metallic ions (Cu 2+ )
present in the mineral. The Cu 2+ ions activate sphalerite and pyrite to float in the lead circuit
and the carbon pre-treatment removes the Cu 2+ ions in order to obtain higher lead
concentrate grades. It was also reported that the lead grade was constrained by the
presence of mixed, intertwined galena-sphalerite assemblage.
The flotation tests, carried out on the PUL-HG samples indicated that it is possible to obtain
commercial lead and zinc concentrates with grades of lead and zinc of 42.1% and 43%,
respectively. The concentration of silver in the lead and zinc concentrates were reported as
7,010 g/t and 198.2 g/t, respectively (Test no 5, PUL-HG-5 sample). The straightforward
conventional selective lead-silver and zinc-silver flotation techniques after carbon pretreatment
are able to recover 85.7% of silver in the lead concentrate (with a mass pull of
3.1%) and 2.93% of silver in the zinc concentrate (with a mass pull of 3.75%). The lead and
zinc recoveries are estimated as almost 80% and 77.8%, respectively.
The lime consumption for the open circuit flotation test PUL-HG-5 is 28.3 kg/t.
The flotation tests, carried out on the PUL-LG samples indicated that it is possible to obtain
commercial lead and zinc concentrates with grades of lead and zinc of 41% and 43.1%,
respectively. The concentration of silver in the lead and zinc concentrates were reported as
6,734 g/t and 207 g/t, respectively (Test no 6, PUL-LG-6 sample). The straightforward
conventional selective lead-silver and zinc-silver flotation techniques after carbon pretreatment
are able to recover 74% of silver in the lead concentrate (with a mass pull of
1.95%) and 3.27% of silver in the zinc concentrate (with a mass pull of 2.8%). The lead and
zinc recoveries are estimated as almost 77.6% and 71.9%, respectively.
The lime consumption for the open circuit flotation test PUL-LG-6 is 26.2 kg/t.
In overall, better flotation (open circuit tests) performances are obtained at a grind size of P80
of 74 µm. Locked cycle tests at this grind size will be necessary to confirm these results.
13.4 FLSmidth Paste Thickening Testwork
A set of paste thickening tests were run on dry samples of the flotation test (tailings) carried
out by ED&ED (PUL-HG-5 and PUL-LG-6. These samples were received by FLSmidth from
Apogee Silver staff.
Thickening tests were conducted on dry flotation tailings samples provided by the Client to
investigate the performance of FLSmidth Deep Cone Paste thickening technology. Screening
flocculent tests were carried out. Anionic flocculent (Floenger PHP 50 Plus) was selected to
improve sedimentation performance based on settling rates and observed visual supernatant
clarity.
Experience has shown that it is difficult to scale paste flow characteristics from small-scale
tests to full-scale pipeline conditions, pilot-scale pumping tests are usually necessary. PLC -
TWP Sudamérica S.A. Av. Encalada 1257 Of. 801, Santiago de Surco Lima 33, Perú (51-1) 4377473
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