VANCOUVER, BRITISH COLUMBIA--(Marketwired - Jul 22, 2015) - Rockhaven Resources Ltd. (TSX VENTURE:RK) ("Rockhaven") is pleased to announce updated metallurgical results for its 100%-owned, road accessible Klaza property located in the Dawson Range Gold Belt of southern Yukon. Metallurgical testing was conducted by Blue Coast Research Ltd. on three zone-specific and one property-wide composite.
Highlights from this test program include:
- 95% combined gold recovery with 65% of the recovered gold produced as doré
- 91% combined silver recovery to high value base metal concentrates or doré
- High recoveries with the same flowsheet on all zones as well as a blended composite
"We're highly encouraged by these outstanding metallurgical results," stated Matt Turner, CEO of Rockhaven Resources. "Not only have recoveries increased substantially, we now have increased confidence that the same process works on all zones and at resource grades."
The locked cycle flotation test, followed by pressure oxidation (POX) and carbon-in-leach (CIL) cyanidation of a gold-bearing sulphide concentrate, on a project-wide composite (PWC), yielded overall recoveries of 95.0% gold, 90.8% silver, 91.2% zinc, and 84.6% lead to potentially saleable products. Grades and recoveries of each product are given in the following table.
| |
|
| Product |
Assays |
| |
Au
(g/t) |
Ag
(g/t) |
Pb
(%) |
Zn
(%) |
| Lead concentrate |
106.4 |
4092.8 |
49.2 |
3.9 |
| Zinc concentrate |
16.9 |
1379.3 |
2.0 |
47.5 |
| Product |
% Distribution |
| |
Au |
Ag |
Pb |
Zn |
| Lead concentrate |
26.1 |
54.3 |
84.6 |
4.1 |
| Zinc concentrate |
7.5 |
33.2 |
6.3 |
91.2 |
| POX-CIL gold extraction* (doré) |
58.9 |
0.8 |
|
|
| Tails leach (doré) |
2.5 |
2.4 |
|
|
| TOTAL Recovery |
95.0 |
90.8 |
84.6 |
91.2 |
| |
| *POX-CIL gold extraction is from a gold-rich arsenopyrite-pyrite concentrate, totaling 12% of the feed, floated after the lead and zinc concentrates are floated. |
| |
Metallurgical Test Program
The process flowsheet consists of lead flotation, followed by zinc flotation, and then by arsenopyrite-pyrite flotation. The arsenopyrite-pyrite concentrate is then pressure oxidized to liberate the gold and leached with cyanide. The overall flotation tails are also leached with cyanide. Final products from this process are precious-metal rich lead and zinc concentrates and gold as doré.
Metallurgical test work was conducted by Blue Coast Research Ltd. at its Parksville, British Columbia facility under the guidance of Chris Martin, C.Eng. The work included 33 batch flotation tests, one locked-cycle flotation test, three cyanide leach tests and one POX and CIL cyanide leach test. Batch tests were conducted on variability composites from each of the Western Klaza, Central Klaza and Western BRX zones, as well as a PWC prepared by combining material from each of the three previously mentioned zones.
The following table shows the grade of each composite.
| |
|
|
|
|
|
| Composite |
%
of
PWC |
Au
(g/t) |
Ag
(g/t) |
Pb
(%) |
Zn
(%) |
| Central Klaza |
53% |
4.84 |
70.1 |
0.80 |
1.52 |
| Western Klaza |
16% |
5.56 |
261.7 |
0.67 |
0.94 |
| Western BRX |
31% |
6.27 |
96.8 |
0.98 |
1.16 |
| PWC |
-- |
5.79 |
121.0 |
0.88 |
1.21 |
| |
|
|
|
|
|
Based on the batch test work conducted to date, there is every reason to believe that material from each of the zones can be processed through the same facility, while the good response of the PWC shows that multiple zones can also be blended with no adverse effect on overall metal recovery.
The locked cycle, cyanide leach, POX and CIL tests were conducted on the PWC. A total of five cycles were run in the locked cycle test and stability was reached quickly and remained stable throughout.
Potential penalty elements include cadmium in the zinc concentrate, arsenic in the lead and zinc concentrates and antimony in the lead and zinc concentrates. These penalty elements are not at levels that are expected to impact marketability and will be minimal in relation to the value of precious metals in each concentrate.
Qualified Persons
Results for the metallurgical test program were provided and approved by Chris Martin, C.Eng., of Blue Coast Metallurgy Ltd. and qualified person for the purpose of National Instrument 43-101. All other technical information in this news release has been approved by Matthew R. Dumala, P.Eng., a geological engineer with Archer, Cathro & Associates (1981) Limited and qualified person for the purpose of National Instrument 43-101.
About the Klaza Project and Rockhaven
The road accessible Klaza project hosts a recently announced maiden inferred mineral resource estimate that includes 7,040,000 tonnes containing 948,348 oz gold, 21,780,313 oz silver, 121,060,093 lbs lead and 144,340,881 lbs zinc at an average grade of 4.19 g/t gold, 96.23 g/t silver, 0.78% lead and 0.93% zinc using a 1.5 g/t gold cut-off (see Klaza Property Amended Technical Report dated June 19, 2015.) A fully funded exploration and engineering program that includes 15,000 m of diamond drilling is currently underway. The drilling is primarily designed to expand the current resource while providing key geotechnical and environmental data.
For additional information concerning the Klaza project or Rockhaven please visit our website at www.rockhavenresources.com.
Matthew Turner, CEO and Director
Rockhaven Resources Ltd.
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