CIBALIUNG GOLD PROJECT
The Cibaliung Gold Project is managed by Arc Exploration Limited.
The Cibaliung project is located in the Province of Banten in Java, Indonesia and Arc Exploration is entitled to a 95% interest and PT Antam Tbk holds a 5% interest.
Location Plan of Cibaliung Gold Project
The key project parameters of the Cibaliung gold mine development are:
- Mine life of 6 years with an ore production rate of 220,000 tonnes per annum;
- Recovery of gold and silver by conventional Carbon in Leach (CIL) processing;
- Mining by conventional underground cut and fill stoping with decline access;
- Annual production of approximately 70,000 ounces of gold equivalent;
- Average life of mine cash operating costs of about $US320 an ounce.
Gold - silver mineralization is hosted by a thick sequence of sub-aqueous basaltic andesite volcanic rocks, with intercalated sediments, of 11.4 million years of age based on K-Ar dating. This sequence is intruded by sub-volcanic andesite to diorite plugs and sykes and cut by a cluster of hydrothermal milled matrix breccias. These host rocks are unconformably overlain by dacitic tuff, 4.9 million years old (K-Ar dating).
The gold prospects in Cibaliung occur in a northwest trending structural corridor that is 3.5 kilometres wide and at least 6 kilometres long. Two major stages of shear-extension related tectonic deformation have been recognised. Firstly, early stage shearing represents low-grade quartz veining and a later stage of shear-extensional deformation is accompanied by high grade mineralization.
Two aligned north northwest trending sub vertical shoots, Cikoneng and Cibitung, host the currently defined resource within the steeply dipping vein system that has a minimum strike length of 1,300m.
The major mineral constituents of the veins are quartz, adularia and clay. Gold occurs mainly as electrum, a natural, pale yellow alloy of gold and silver, while silver occurs as argentite-aguilarite-naumannite and electrum and rarely as native silver, sulfosalts or tellurides. Sulfides generally comprise less than one percent by volume of the vein, with pyrite as the most dominant species. Together with pyrite, traces of a very fine-grained base metal sulfides dominated by chalcopyrite, sphalerite and galena are, in most cases, intimately associated with electrum and silver minerals.
AMC Consultants Pty Ltd prepared a three-dimensional wire frame model of the two deposits and performed a detailed geostatistical analysis. On the basis of this analysis a geological resource block model was prepared.
Geotechnical assessment of the ground conditions by BFP Consultants indicates that cut and fill stoping is the preferred mining method. The mining study, included as part of the Bankable Feasibility Study, indicated that stopes could be accessed via a small services and production decline. Ore mining will be by CSD personnel using conventional mining equipment. Ground support will be required in the decline and in stopes.
Metallurgical test work has been carried out on samples representing the major ore source areas of the Cibitung and Cikoneng deposits. A comprehensive laboratory program was conducted at Ammtec, in Perth, with input from other laboratories for specialist SAG mill test work. Test work was conducted, to assess and define the various parameters required for optimisation of the process plant design and to determine the economic extraction recoveries of gold and silver. The test work results were assessed by engineers, GRD-Minproc, and incorporated into a design package. The processing plant designed by GRD-Minproc consists of a:
- Single stage primary jaw crusher, with crushed ore being fed directly to a SAG mill;
- Two-stage leach circuit followed by six stages of CIL;
- Loaded carbon stripped in an AARL elution circuit with gold and silver recovered by electowinning and smelting to dore` bullion; and a
- Cyanide destruction circuit.
Environmental issues were also carefully considered as part of the Bankable Feasibility Study and have resulted in:
- Minimisation of the project footprint;
- Inclusion of a small, sealed, waste rock dump for the containment of potential acid generating mine waste;
- Design of the cyanide destruction circuit to ensure discharge from the tailings storage facility meets Indonesian discharge standards; and
- Management of water, noise and dust emissions and closure issues to Indonesian and Australian standards.
The Cibaliung project has been designed with the potential for expansion since exploration, which has continued throughout the course of the BFS, has identified several priority targets that may form new economic shoots and could lead to an increase in the project's resources. The discovery of a new shoot could lead to an expansion in annual production to about 100,000 ounces.
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