A summary of significant points are as follows:
- The Study was started in April 2012 just prior to the publication of a positive Asmara Project prefeasibility study (PFS) that showed that all four deposits could be processed in a single central processing plant;
- The Study is on schedule to be completed in the second quarter of 2013;
- Based on new metallurgical testwork the Study will include early mining of the Direct Shipping Ore ("DSO") from Debarwa and early heap-leaching of the surface gold material from the project;
- Based on the above, cash-flow is expected a year earlier (2015) than presented in the PFS; and
- Based on the new operating scenarios, initial capital costs are expected to be reduced and overall economics enhanced in the Study compared to the PFS.
Based on the positive economics of the PFS, work started in April 2012 to support the Study; this work included drilling for metallurgical samples on the Emba Derho deposit as well as geotechnical drilling near the proposed Emba Derho pit and at proposed plant facilities.
Variations to the Prefeasibility Study Plan
As in the PFS, the Study is considering a centralized process plant near the large Emba Derho deposit using flotation for the recovery of the base metals. However, in order to enhance economics and reduce project capital cost requirements, various processing trade-off studies have shown that early selective mining and shipping of the DSO from the Debarwa deposit to a smelter as well as early heap-leaching of the known zones of gold mineralization on the project are feasible and result in the optimum economic scenario.
Direct Shipping Ore (DSO)
The DSO Zone is located within the supergene copper zone of the Debarwa deposit and contains 116kt of high grade material at an average grade of 16% copper, 3.0g/t gold and 77.0g/t silver. The DSO zone is located about 40 meters below the surface and is approximately 140 meters long. The Study will include a plan to begin mining operations on the Asmara Project by mining, crushing and direct shipping the DSO material from Debarwa, which is located about 45km south of the Emba Derho plant site. The extraction of DSO material early in the project life could provide early cash flow and reduce initial capital exposure.
The DSO material will be crushed to minus ¾ inch and transported to the port of Massawa for shipping and sale to smelters. This plan for earlier production was outlined in the feasibility study for a standalone operation at Debarwa (see news release dated May 14, 2012) however it was not included in the mining plan outlined in the PFS because additional metallurgical work was required at that time.
Heap Leach Gold Production
Sunridge has conducted extensive metallurgical test work on the gold material from the gold oxide caps of the Emba Derho and Debarwa deposits and the Gupo Gold deposit since completion of the PFS. Test work, including column tests of gold ores to simulate heap-leach gold processing, has been completed on each deposit to support heap leach production with leach results utilizing ¼ inch and ½ inch material demonstrating 51% to 71% gold recovery. The heap-leaching process will provide Sunridge the opportunity to generate revenue from the precious metals earlier in the mine life thereby benefitting the project economics. This is an improvement to the gold processing plan in the PFS which outlined a Carbon in Pulp (CIP) facility which would have stockpiled the material from the gold caps and processed it at the end of the mine life.
The Study is being conducted by Senet (Pty) Ltd. ("Senet"), based in Johannesburg, South Africa, an internationally respected leader in the design, engineering and construction of mining projects in Africa. Senet has extensive experience working in Eritrea on the Bisha Mine Project for Nevsun Resources Ltd. Senet's expertise in process plant design and infrastructure is supported by Snowden, based in Vancouver, Canada on mine planning and design. Their experience is complemented by Knight Piesold Ltd. ("KP") for tailings facility design and waste management and Blue Coast Metallurgy Ltd ("Blue Coast") for metallurgical design and supervision. The Study is focused on Sunridge's large Emba Derho copper-zinc-gold-silver volcanogenic-massive-sulphide (VMS) deposit, the nearby high grade zinc-gold-copper Adi Nefas VMS deposit, the Debarwa copper-zinc-gold-silver VMS deposit and the Gupo gold deposit all comprising the Asmara Project.
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