VANCOUVER, BRITISH COLUMBIA--(Marketwire - Feb. 19, 2013) - Calibre Mining Corp. (TSX VENTURE:CXB) (the "Company" or "Calibre") is pleased to announce that the Company's joint venture partner B2Gold Corp. ("B2Gold") has completed initial scoping level metallurgical testwork on samples of gold-copper mineralization from the Primavera porphyry project in north-east Nicaragua. B2Gold has earned a 51% interest in the Primavera gold-copper porphyry project as well as 322 km2 of additional mineral concessions in the region.
In a report entitled "An Investigation into Scoping Level Testwork on Primavera Project Samples" dated February 8th, 2013 by SGS Canada Inc. of North Vancouver ("SGS Canada") four composite samples of Primavera porphyry mineralization from drill hole PR-012-16 (201.35 m grading 0.77 g/t Au and 0.36% Cu) were submitted for initial metallurgical studies. Sample head assays are outlined in Table 1. Individual sample weights ranged from 18.6 kg to 30.3 kg. The metallurgical tests conducted on the Primavera project samples included rougher flotation kinetic and cleaner flotation tests and whole ore cyanide leach tests.
|Table 1 - Summary of Head Assays
|| Sample Number
In optimized rougher flotation tests on the four Primavera samples gold recoveries ranged from 86% to 91% and copper recoveries ranged from 94% to 98%. Initial metallurgical tests indicate that the recovery of gold, copper and sulphur are strongly related to each other and recovering sulphur by flotation will recover most of the copper and gold. Two different grind sizes were tested during the study with the finer grind returning the best recoveries. Additionally, whole ore leach tests on the four Primavera samples extracted 90.0% to 96.6% of the gold using 1.2 kg/t to 2.43 kg/t of NaCN. Gold kinetics on the leach tests are moderately fast reaching plateau within 30 hours and gold in all leach tests exhibited free milling qualities.
Mr. Greg Smith, President and CEO of Calibre stated: "While preliminary in nature we are very encouraged with the results from the initial metallurgical testing on Primavera porphyry gold-copper mineralization. Initial flotation tests showed excellent recoveries for both gold and copper and gold recoveries in whole ore leach tests were also excellent. Calibre controls a 49% interest in the Primavera joint venture while B2Gold controls a 51% interest and is project operator. Calibre is very pleased that B2Gold is funding an initial $2.0 million 2013 exploration program at Primavera while the two companies work together to define the terms of a joint venture agreement."
Based on the results of the initial metallurgical testing of Primavera mineralization SGS Canada has recommended that future testwork be directed at optimizing flotation and leaching parameters of the gold-copper mineralization as well as tests to determine grindability, abrasiveness and work index. To review the complete Primavera metallurgical test results the full SGS Canada report can be accessed on the Calibre website www.calibremining.com.
Mr. Gregory Smith, P.Geo, the President and CEO of the Company, is the Qualified Person as defined by NI 43-101, and is responsible for the accuracy of the technical data and information contained in this news release.
About Calibre Mining Corp.
Calibre Mining Corp. is a TSX Venture Exchange listed company (TSX VENTURE:CXB) that is focused on the acquisition, exploration and development of gold and silver deposits in Central America. The Company is focused on its 100% owned Riscos de Oro gold-silver deposit, the drilling program at the Primavera gold-copper project in conjunction with B2Gold Corp. and the exploration program on the Rosita copper-gold-silver project in conjunction with Alder Resources Ltd. Major shareholders of Calibre include gold producer B2Gold and investment fund Sun Valley Gold.
Calibre Mining Corp.
Greg Smith, P.Geo., President and CEO
Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.