PEA Supports Lumina’s Cangrejos Project in Ecuador

Lumina Gold has reported positive results from a preliminary economic assessment (PEA) of its Cangrejos gold-copper project in El Oro province, southwest Ecuador. The current PEA demonstrates substantial improvements over a previously reported 2018 PEA, with the addition of the Gran Bestia deposit, increased mineral resource definition, and an improved process flow sheet.

Highlights of the Cangrejos PEA include life-of-mine (LOM) average annual payable production of 366,000 ounces (oz) of gold and 46 million lb of byproduct copper over a 25-year mine life. An initial 40,000-metric-ton-per-day (mt/d) processing facility would process ore during years one to five of operations, with an expansion to 80,0000 mt/d planned for year six. Average cash operating costs are estimated $545/oz and all-in sustaining costs are estimated at $604/oz for gold, net of byproduct credits. LOM processed grades are 0.56 g/mt for gold and 0.10% for copper. The LOM revenue mix is 78.9% gold, 19.4% copper and 1.7% molybdenum plus silver.

Initial capital costs, including working capital and refundable value added tax, are estimated at $1 billion. Expansion capital to double throughput, including working capital, is estimated at $454 million. Lumina President and CEO Marshall Koval said, “I am extremely pleased that we increased the after-tax NPV of Cangrejos by more than $600 million to $1.6 billion, maintained average annual gold production of more than 360,000 oz per year (oz/y) for 25 years, and increased the after-tax IRR of the project to 16.2%. “Cangrejos is an exceptional global gold deposit and one of the few of this scale that is 100%-controlled by an independent developer. After commissioning Fruta del Norte and Mirador, Ecuador will turn its attention to focus on the next generation of development projects.”

The PEA contemplates large-scale open-pit mining using a 100% owner-operated equipment fleet. Five mining phases were designed for Cangrejos and two for Gran Bestia, both using a technique that optimizes present value by using a declining cut-off grade over the mine life. Gran Bestia material begins to enter the mine production schedule in year five; however, the majority of the Gran Bestia economic mineralization (88%) is mined in the last nine years of the production schedule. A 13-month preproduction stripping period is contemplated to expose sufficient material for initial operations. Haul road construction and clearing and grubbing of the pit area are expected to be performed primarily by contractors prior to the commencement of preproduction stripping.

The proposed Cangrejos processing plant is a conventional copper-gold flotation concentrator and carbon-in-leach (CIL) circuit. Near-surface saprolite and saprock materials have now been included in the mill feed since the material can be processed with the addition of the CIL plant. The saprolite and saprock account for 2% of the LOM processed material and contain 269,000 oz of gold. The CIL circuit throughput will be 4,000 mt/d during the first five years and 8,000 mt/d post expansion in year six.

The process flow sheet begins with a primary crusher adjacent to the pit and an overland conveyor to the plant. The plant consists of secondary crushing, HPGR and ball mills, copper and molybdenum concentration circuits, CIL treatment, and cyanide detox and thickening and filtering of the combined CIL and flotation tailings. The tailings are conveyed to a dry-stack tailings facility. The plant is designed to produce gold and silver doré, a copper-gold flotation concentrate, and a molybdenum concentrate, which will be trucked approximately 40 km to Puerto Bolivar, Ecuador.

As featured in Womp 2020 Vol 07 -