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Pulacayo Project Feasibility Study - Apogee Silver

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<strong>Pulacayo</strong> 1 000 t/d Phase I <strong>Feasibility</strong> <strong>Study</strong> - NI 43-101 Technical Report<br />

090644-3-0000-20-IFI-100<br />

The zinc cleaner concentrate recovered 7.8% of weight, 1.3% of lead, 84.7% of zinc and<br />

38.8% Ag. The concentrate assayed 0.324% Pb, 41.2% Zn and 2 463 g/t Ag.<br />

13.1.6.3 Locked Circuit Flotation Tests<br />

Large scale two cycle locked cycle flotation tests were performed using the process<br />

flowsheet similar to that developed for San Cristobal deposit.<br />

The lead concentrate assaying 62.2% Pb, 4.46% Zn and 10,891 g/t Ag, recovered 3.1%<br />

weight, 88.8% of lead, 3.9% of zinc and 63.4% of silver. The zinc concentrate assaying<br />

61.5% Zn, 0.9% Pb and 3,303 g/t Ag, recovered 5% weight, 87.6% of zinc, 2.1% of lead and<br />

31.3% of silver.<br />

The tailings were very difficult to settle due to high proportions of clay in the ore, which will<br />

impact the process flow sheet and overall plant design.<br />

The lead and zinc third cleaner concentrates were analyzed for impurities. The results<br />

indicate that penalties may be incurred on the concentrates for several impurities, as they are<br />

higher than the norm for smelter contracts.<br />

13.2 UTO Metallurgical Test Program (Stage 2)<br />

UTO conducted a metallurgical test work program on these three samples comprising<br />

comminution (only Bond Ball Work Index), open circuit flotation tests (OCT), locked cycle<br />

flotation tests (LCT), OCT tailings (non-float) size by size analyses and OCT tailings (nonfloat)<br />

sedimentation tests.<br />

Clays mineralogy studies were not carried out to determine the presence of shrinkingswelling<br />

clays (Smectites) and other type of clays that may produce very fine slimes.<br />

However, during the course of the metallurgical test work, slimes were produced affecting the<br />

flotation performance. The host rock contained significant amount of clay material, which<br />

resulted in problems in settling of tailings and flotation pulp rheology.<br />

13.2.1 Second Set of Samples<br />

In 2009, the laboratory facility of Universidad Nacional de Oruro (UTO) in Bolivia, received<br />

material from the <strong>Pulacayo</strong> <strong>Project</strong>. Individual drill intervals were combined by UTO as<br />

specified by Micon and ASL to generate three (3) composite samples.<br />

These three composites represent a higher grade, a medium grade and a lower grade<br />

composite sample (roughly 100 kg each). All the samples were metallurgical tested by UTO<br />

and the products were assayed by ALS Chemex in Lima, Peru. <strong>Silver</strong>, zinc, lead and copper<br />

concentrations were determined using an aqua regia digestion followed by spectroscopy. For<br />

samples with silver value exceeding 300 ppm the fire assays (ALS code AA26) method was<br />

used.<br />

A summary of the estimated core grades and assay values for all three composites (first<br />

sample composite set) is shown in Table 13.2. Core intervals were chosen that would result<br />

in low, medium and high grade composites. The spatial distribution of the intercepts used to<br />

prepare the bulk samples is well documented.<br />

TWP Sudamérica S.A. Av. Encalada 1257 Of. 801, Santiago de Surco Lima 33, Perú (51-1) 4377473<br />

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