COLLERINA Cobalt is undertaking metallurgical studies to determine the feasibility of production of a copper-gold concentrate via a gravity plus flotation process flowsheet at the Wonogiri Gold-Copper Project in central Java. The testwork is being carried out on the Randu Kuning gold-copper porphyry deposit.

Collerina, which was previously called Augur Resources, is also assessing the availability and suitability of second-hand processing plants for use at Wonogiri.

Under the current Indonesian Mining Law, the export of less than 99.99% copper is not permitted unless direct approval from the Indonesian Government is obtained and export tariffs paid. As such, the company is in discussions with several groups in regards to offtake of concentrate.

Together with JV partner Rajawali and Indonesian consulting group Geomine, the company submitted a feasibility report to the Indonesian Ministry of Mines & Energy for development of a gold-only operation. The report provided detailed information for a gold-only operation involving open-pit mining to produce gold bullion via gravity and CIL processing of ore. Under this scenario, no by-product copper would be recovered.

The Ministry has approved this report and work will now focus on completing remaining requirements as part of the AMDAL permitting, which includes environmental and social impact studies. The IUP has been extended to allow for completion of this work.

However, pending completion of ongoing metallurgical tests, Collerina intends to determine the feasibility of production of a copper-gold concentrate. This work will also take into account pending revisions to mining regulations.

Additional testwork started in September 2016 to optimise recoveries of copper and gold via combined gravity and flotation processing to produce a gold-rich, copper concentrate. The testing has established a baseline flowsheet and remaining work will involve locked cycle flotation tests. This work will indicate what recoveries and concentrate grades might be expected under actual operating conditions. 

The work has been temporarily suspended pending import clearance of some specialised reagents to enhance copper recovery.

Meantime, the Central Java Provincial Government has issued the JV an exploration IUP for aggregate covering the Randu Kuning gold-copper deposit and an adjacent area identified for a standalone quarry. 

The next step is to obtain an IUP Production permit to allow for quarry development, which requires completion of a base-line environmental study (UKL-UPL) and a feasibility study.

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