Tue November 15, 2011.
Bellhaven Announces that Initial Metallurgical Studies Demonstrate High Gold and Copper Recoveries for the La Mina Gold-(Copper) Project, Colombia. Conventional Flotation Process Delivers a High-Quality, Clean, Commercial-Grade Gold-Copper Concentrate
Vancouver, British Columbia – November 15, 2011. Bellhaven Copper & Gold Inc. (TSX-Venture: BHV) (“Bellhaven” or the “Company”) is pleased to announce positive results from the initial metallurgical test work performed on samples from the La Cantera and Middle Zone prospects at the Company’s 100%-controlled La Mina gold-(copper) project located in Colombia. These preliminary studies demonstrate that a conventional flotation process for La Mina can yield recoveries up to 85% to 90% of gold and copper to produce a high-quality, clean, commercial-grade concentrate containing 26-32% copper and 50-69 g/t gold.
The test work was conducted by Resource Development Inc. located in Wheat Ridge, Colorado, a leading metallurgical testing firm serving major and junior mining companies with global resource projects.
Paul Zweng, Bellhaven’s Interim CEO and Director, commented as follows:
“These initial metallurgical test results are simply outstanding. The high recoveries for both gold and copper exceeded our expectations. We are also very pleased that these studies demonstrated that a very clean (less than 0.3% arsenic) commercial concentrate can be delivered from the La Mina project. Clean concentrates such as these normally command a premium price in the market.”
“What is especially encouraging is that these results were gained using conventional flotation processes. Although additional test work needs to be done before the metallurgical process is completed, these initial metallurgical results substantially de-risk the La Mina project.”
“La Mina is one of the highest grade porphyry gold-(copper) projects in the Americas (see press release dated September 13, 2011). Now we can see a path towards high recoveries of both the gold and copper at La Mina using conventional processing techniques. These two aspects—high grade and high recovery—bode well for the project.”
Summary of Metallurgical Test Work
A series of metallurgical tests were performed on coarse reject samples from three drill holes collared at the La Cantera prospect and one drill hole at the Middle Zone prospect. These individual assay interval samples were composited to produce four composite samples ranging in grade from 0.73 to 1.5 g/t Au and 0.31 to 0.47% Cu.
The metallurgical tests included Bond’s ball mill work-index determinations, in-place bulk density measurements, gravity tests, direct cyanidation recoveries, and carbon-in-leach tests, as well as rougher and cleaner flotation tests.
The Bond’s ball mill work index determinations ranged from 10.2 to 14.0; the highest work index determination was measured from the La Cantera high-grade composite, possibly reflecting a greater abundance of quartz veins. These work indices are typical for porphyry gold-copper deposits.
Bulk densities, determined using a standard wax-coating method, ranged from 2.48 to 2.98 g/cc.
Gravity test work did not yield a high-grade concentrate indicating that there is little coarse gold at either La Cantera or Middle Zone. The lack of significant quantities of coarse gold is considered to be positive, allowing for more consistent flotation (by not requiring installation of a gravity circuit to collect the coarse gold) and cyanide leach results.
Whole-ore cyanide leach tests indicated recoveries of up to 90% of the gold and 70% of the copper whereas carbon-in-leach test results indicated recoveries of up to 87% of the gold and 73% of the copper from the four composite samples. As expected, copper recoveries were relatively low because of the chalcopyrite-dominant mineralogy of the composite samples (i.e., sulphide, not oxide, mineralogy).
A key outcome of the rougher flotation test work was that the application of a simple reagent suite of potassium amyl xathate (PAX) and Aeropromotor 404 (AP 404), at a grind size of 80% passing 150 mesh, produced high gold recoveries ranging from 93.2 to 96.8% and copper recoveries ranging from 88.7 to 90.8%.
The other key result of the rougher and open-circuit cleaner flotation test work is that, with the exception of an outlier represented by Composite 2, the test work demonstrated the potential for La Mina to deliver concentrate grades ranging from 26.7 to 31.9% copper and 61.9 to 75.8 g/t gold. These concentrates are very clean, containing only trace amounts of arsenic, antimony, and lead, and below typical penalty benchmark levels charged against concentrate sales by smelters.
The metallurgical testing program is now focused on lock-cycle tests on representative samples of the La Cantera and Middle Zone prospects, as well as crushing and grinding test work for mill design and sizing. Once completed, these subsequent metallurgical results will provide important inputs into an upcoming preliminary economic assessment used to determine the potential economic viability of a mining operation at La Mina. Bellhaven continues to drill at La Mina with the goal of expanding the existing resource.
About the La Mina porphyry Au-(Cu) prospect
La Mina (also known as Venecia) lies within the Middle Cauca belt of Miocene-age volcano-plutonic rocks in central Colombia known to host large porphyry gold deposits as well as large epithermal gold districts.
Bellhaven announced its first NI 43-101 resource for the La Mina project on September 13, 2011, establishing 1.0 Moz gold (1.6 Moz gold equivalent) at the La Cantera prospect, one of twelve porphyry gold-(copper) prospects currently known at La Mina. The average grade of 1.26 g/t AuEq (at 0.3 g/t Au cut-off grade) makes La Cantera one of the highest grade porphyry gold-(copper) prospects in the Americas.
The most important host rocks observed in drill core include the Combia Formation intermediate volcanic rocks as well as a series of intermediate composition porphyries and hydrothermal breccias. Alteration is typical of gold porphyry deposits as exemplified by a potassic-calcic core encircled by sericitic, intermediate argillic, and propyllitic alteration zones. Specifically, most of the gold and copper discovered so far at La Cantera and the Middle Zone are spatially associated with quartz-magnetite-chalcopyrite ± bornite veinlets in potassic altered porphyry and breccias containing elevated quantities of hydrothermal magnetite. As a result, the gold-bearing rocks are highly magnetic (ca. 200x10-3 SI) which creates a sharp contrast with the barren and weakly magnetic intermediate argillic-altered rocks as well as the non-magnetic sericite-altered rocks that surround the potassic core.
On behalf of the board of directors,
Paul L. Zweng, Interim CEO & Director
BELLHAVEN COPPER & GOLD INC.
Corporate Contact in North America: Corporate Contact in Panama:
Paul Zweng, CEO/Director Julio Benedetti, President/Director
+1-808-377-1947 Int’l No: +507-226-3967