New Pacific Reports High Recovery of Silver from Various Metallurgical Processes FOR Sulphide, Transition and Oxide Styles of Mineralization from Silver SAND, Bolivia
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NEWS RELEASE
Trading Symbol: TSX-V: NUAG / OTCQX: NUPMF
NEW PACIFIC REPORTS HIGH RECOVERY OF SILVER FROM
VARIOUS METALLURGICAL PROCESSES FOR SULPHIDE, TRANSITION AND
OXIDE STYLES OF MINERALIZATION FROM SILVER SAND, BOLIVIA
VANCOUVER, British Columbia – August 20, 2019 – New Pacific Metals Corp. (TSX-V: NUAG)
(OTCQX: NUPMF) (the “Company”) is pleased to announ ce the final results of a preliminary
metallurgical test work program for its Silver Sand Project. The Company is very pleased with the
positive results achieved so far from the completed test work. The results suggest that the
mineralized materials from the Silver Sand Project would be amenable to processing using
conventional flotation or whole ore cyanidation at atmospheric pressure at large scale. This
preliminary metallurgical program has demonstrated that good silver extraction rates are possible
using these simple extraction methods and that furt her improvements and refinements should be
possible in future programs after fine-tuning the various test parameters.
HIGHLIGHTS OF THE COMPLETED TEST PROGRAM
• Composite samples of sulphide, transition and oxide mineralization were submitted for
laboratory-scale rougher-scavenger flotation testin g and this achieved up to 96.0%, 86.8%
and 92.0% silver recovery respectively.
• Composite samples of sulphide, transition and oxide mineralization were submitted for
bottle roll cyanidation testing and this achieved u p to 96.7%, 97.0% and 96.3% silver
extraction respectively.
• Samples of oxide mineralization were submitted for coarse column leach cyanidation testing
and this achieved up to 82% silver extraction.
• High recoveries achieved during cyanidation tests indicate that silver-bearing minerals within
the sulphide and transition composite samples teste d can be considered non-refractory in
nature.
• Composite samples were found to be mostly in the soft to medium grindability range with
low to medium values of abrasion index .
METALLURGICAL TEST WORK DETAILS
Several metallurgical composites of oxide, transiti on and sulphide mineralization from two areas of
the Silver Sand deposit were prepared from samples of available half-core. A geometallurgical
sampling approach was used and was designed to high light the effect of differences in silver grade,
degree of oxidation and lithology.
Four independent geo-metallurgical test work progra ms (mineral characterization, comminution,
froth flotation and cyanide leaching) were carried out on the different metallurgical composites. Six
metallurgical domains (MET1 to MET6) were identifie d for the flotation and leaching test work and
six geological domains (GEO1 to GEO6) were branded for the comminution test work.
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Comminution, flotation and leaching programs were c ompleted by SGS Mineral Services in Lima,
Peru, while the mineral characterization work was completed by the Research Centre for Mining and
Metallurgy (CIMM) and Oruro Technical University (O TU) in Bolivia. Results from the individual test
work programs are summarized below.
Mineral Characterization
Mineral characterization work consisted of size fraction assaying, heavy liquids testing and a
preliminary program of quantitative mineralogy. The mineral characterization and Sink &
Float tests are designed to assess the mineral response to gravity separation.
Size Fraction Assaying:
Twelve crushed composites were screened into seven size fractions, and each fraction
was individually assayed to obtain a distribution o f silver by size. Figure 1 shows the
results and illustrates that for almost every compo site, the silver tends to concentrate
into the finest size fraction (-74 microns). This c oncentration effect gives rise to an
upgrade in silver content of approximately 2.5 to 3 times within that fraction – a
potentially useful processing characteristic.
Figure 1 - Silver Distribution by Size Fraction
Heavy Liquid Testing:
Six of the composites (high and low grade oxide, tr ansition and sulphide mineralization)
were sized into seven fractions each, and these wer e then subjected to a simple gravity
separation using heavy liquid at a density of 2.58 kg/l. On average for all composites,
roughly 46% of the total silver was concentrated in to 15% of the mass as a “dense”
(>2.58 kg/l) fraction. Importantly however, this ef fect was far more pronounced on
average within certain size fractions, as shown in the chart below, with roughly 80% of
silver concentrated into less than 20% of the mass (in the 595 to 74-micron range).
The gravity concentration effect was not seen in the coarser size fractions (+595 micron),
likely due to insufficient liberation of silver minerals in these size fractions.
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Figure 2 – Average Mass & Silver Recovery in the >2.58 kg/l Density Class
Comminution Testing
Four geological domain composites were subjected to a program of comminution scoping
tests, including Crushing Work Index (CWi), Bond Ba ll Mill Work Index (BWi) and Abrasion
Index (Ai). Twenty-one samples were tested in total . CWi tests reported energy
consumptions between 4.8 and 11.3kWh/t, while the B Wi measurements were from 4.8 to
15.9kWh/t with only one sample above 14 kWh/t. Thus , the majority of the samples tested
fell into the category of soft or medium competency level for crushing and gr inding . These
early indications suggest that relatively low capit al and operating costs could be anticipated
for any potential comminution circuits. The reporte d values of abrasion index of between
0.06g and 0.54g corresponds to low to medium abrasivity for these samples. Sulphide
materials reported the highest values in the range of medium abrasion behaviour, while the
oxides were generally the lowest.
Flotation Testing
Three metallurgical composites of oxide, transition and sulphide mineralization were
prepared for a program of froth flotation scoping work, consisting of 23 bench scale rougher-
scavenger tests using a variety of conditions (grind sizes, reagent types, reagent dosages and,
slurry pH). Composite grades are shown in Table 1 below.
Table 1 – Flotation Program Composite Details
Composite ID
Head Assay
Ag, g/t Stot % Cu, % Pb, % Zn, %
Oxide (Z1 FLOATMET 4) 201 0.12 0.006 0.108 0.003
Transition (Z1 FLOATMET 5) 123 1.01 0.02 0.391 0.01 0
Sulphide (Z1 FLOATMET 6) 124 1.63 0.03 0.217 0.812
In general, the flotation performance of these comp osites was very good, with high silver
recoveries achieved using Potassium Amyl Xanthate ( PAX) as the primary mineral collector.
Silver recoveries of up to 96% for the sulphide com posite and 86.8% for the transition
composite were reported using this simple approach. Silver recovery appeared to be relatively
insensitive to pulp pH although finer grinds and the addition of a secondary collector appeared
to give marginal increases in metallurgical performance for the transition composite.
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Table 2 – Summary of Results for Rougher-Scavenger Test Work
Composite Flotation conditions % Recovery
P80 (µm) Collector Mix/Dose Pulp pH Flotation
Gas
Ag % Ssul %
Sulphide (Z1 FLOATMET 6) 74 PAX, 45 g/t 9.0 Air 96. 0 98.4
Transition (Z1 FLOATMET 5) 74 PAX, 30 g/t + OX100, 15 g/t Natural Air 86.8 94.8
Oxide (Z1 FLOATMET 4) 74 PAX, 45 g/t + OX100, 20 g/ t 9.0 N 2 92.0 49.9
The oxide composite also responded well to standard sulphide flotation conditions with silver
recoveries in the 90% range. Maximum recoveries were achieved using nitrogen gas for oxide
composite flotation, although this slight improveme nt appears to have been achieved
primarily as a result of higher concentrate mass pull.
These initial scoping tests show that silver minera ls can be efficiently concentrated using
relatively simple froth flotation conditions. Flota tion concentrates containing 2,500 – 3,000
g/t silver were produced without using a cleaner flotation stage.
Bottle Roll Leach Testing
Four metallurgical composites of oxide, transition and sulphide mineralization were prepared
for cyanide leaching test work as summarized in Tab le 3. The bottle roll test work program
comprised of a battery of 33 individual scoping tes ts, each running for 72 hours and using a
variety of conditions (grind sizes, cyanide solution strength, oxygen levels, and temperatures)
to assist begin definition of the metallurgical characterization of Silver Sand mineralization.
Table 3 - Bottle Roll Composite Details
Composite ID Head Assay
Ag, g/t Stot % Cu % Pb % Zn %
LG Oxide (Z1 LEACHMET 1) 29 0.15 0.010 0.062 0.008
HG Oxide (Z1 LEACHMET 4) 132 0.21 0.009 0.055 0.003
HG Transition (Z1 LEACHMET 5) 157 1.45 0.040 0.120 0.343
HG Sulphide (Z1 LEACHMET 6) 124 2.13 0.031 0.089 0. 054
A variety of results were obtained from the work. A summary of the better data points is
presented in Table 4 below.
Table 4 - Bottle Roll Test Results Summary
Composite ID Grind
P80 , µm
% Sol.
Strength
Consumption,
kg/t
Temp
℃℃ ℃℃
Sparge
Gas
% Extraction
NaCN NaCN CaO Ag Cu
LG Oxide (Z1 LEACHMET 1) 74 0.30 6.71 0.78 59 O 2 81.6 48.5
HG Oxide (Z1 LEACHMET 4) 74 0.30 3.94 0.78 59 O 2 96.3 34.5
HG Transition (Z1 LEACHMET 5) 50 0.30 9.78 0.78 56 O2 97.0 81.6
HG Sulphide (Z1 LEACHMET 6) 50 0.30 10.2 0.79 57 O 2 96.7 73.7
Very high silver extractions (greater than 96%) wer e achieved for the sulphide and transition
composites when intensive cyanidation conditions were used (oxygen sparging plus elevated
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pulp temperature). Oxide composite performance was more variable, with silver extractions
between 81 and 96% achieved under similar conditions.
These leaching results are in general very encourag ing and further optimization test work is
recommended to better characterize the deposit.
Column Leach Testing
Column leach tests were completed on the two oxide samples, using coarser material than
the bottle roll work (crushed to 100% passing 1/2”). Each column test ran for 75 days and the
dissolved oxygen (DO) level was maintained throughout all tests.
Table 5 – Column Leach Test Results Summary
Composite ID Mesh of
Grind
mm
% Sol.
Strength
Solution
Rate
l/h/m 2
Consumption, kg/t % Extraction
(calculated from PLS concs)
NaCN NaCN CaO Ag Cu
Z1 LEACHMET 1 -12.7 0.40 7.0 6.3 1.4 75.3 45.8
Z1 LEACHMET 4 -12.7 0.40 10.0 8.6 1.6 84.4 45.1
Z1 LEACHMET 1 -12.7 0.40 7.0 6.4 1.4 88.3 29.3
Z1 LEACHMET 4 -12.7 0.40 10.0 8.1 1.6 86.6 29.4
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Technical information contained in this news release has been approved by Andy Holloway, P.Eng.,
CEng., Principal Process Engineer at AGP Mining Con sultants Inc., who is a Qualified Person for the
purposes of National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-
101”).
ABOUT NEW PACIFIC
New Pacific is a Canadian exploration and development company which owns the Silver Sand Project
in Potosí Department of Bolivia, the Tagish Lake gold project in Yukon, Canada and the RZY Project in
Qinghai Province, China. Its largest shareholders are Silvercorp Metals Inc. and Pan American Silver
Corp., one of the world's largest primary silver pr oducers, which operates six mines, including the
San Vicente mine located in the Potosí Department of Bolivia.
For further information, contact:
New Pacific Metals
Corp. Gordon Neal
President
Phone: (604) 633-1368
Fax: (604) 669-9387
www.newpacificmetals.com
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the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release.
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changes in any other events affecting such statemen ts or information. For the reasons set forth above ,
investors should not place undue reliance on forward-looking statements or information.
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Securities laws. NI 43-101 is a rule developed by th e Canadian Securities Administrators that establish es
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