Tag Archives: G-Mining Services

Bluestone widens production plans with Cerro Blanco open-pit mining PEA

Bluestone Resources has come out with a new open-pit mining plan for its Cerro Blanco project in south-eastern Guatemala that effectively doubles production and triples the potential investor returns from the gold-silver asset.

The preliminary economic assessment on Cerro Blanco, which comes just under 11 months after entering into an agreement with G Mining Services covering basic engineering and overall project optimisation efforts for the project, outlines a project able to produce 231,000 oz of gold at an all-in sustaining cost of $642/oz Au over the 11-year life of mine. This is based on a 15,000 t/d operation with a $548 million initial capital expenditure bill.

Using a base case gold price of $1,550/oz and silver price of $20/oz, an after-tax net present value (5% discount) of $907 million was calculated.

The numbers are significantly different from what the company outlined in a previous feasibility study on Cerro Blanco, completed by a consortium of independent consultants led by JDS Energy & Mining. This showed an average output of 113,000 oz/y of gold at an all-in sustaining cost of $579/oz and a capital cost of $196 million (including contingency).

Using a base case of $1,250/oz gold and $18/oz silver, this underground project was estimated to generate a post-tax net present value (5% discount) of $241 million.

Bluestone said on the PEA publication: “The recent completion of advanced engineering and optimisation work has significantly enhanced the understanding of the project and presented an opportunity to capitalise on its near-surface, high-grade mineralisation through an open-pit development scenario. This is a major change to Bluestone’s corporate strategy that will fully maximise the value of the Cerro Blanco gold project for all stakeholders.”

David Cass, Vice President of Exploration, added: “The pivot to surface mining is a culmination of our increased understanding of the geology and grade distribution that will realise the full potential of the Cerro Blanco low-sulphidation mineralisation. The inverted wedge shape of the deposit with its upper half forming the Cerro Blanco hill lends itself to surface mining with a low strip ratio.”

The project currently hosts 3 Moz of gold in the measured and indicated resource category and 250,000 oz of gold in the inferred mineral resource category.

The open-pit mining scenario envisages an owner-operated mining fleet using 65-t trucks matched with 7 cu.m hydraulic shovels supported by 8.2 cu.m wheel loaders. Mill feed will be trucked to a primary crusher located to the east of the main pit. Waste totalling 123.5 Mt will be placed in a waste storage facility.

In terms of processing, the PEA looks at treating 5.04 Mt/y of mineralised material at an average feed grade of 1.6 g/t Au and 7.26 g/t Ag through a conventional cyanide leach process plant to produce doré. The flowsheet is very similar to the previous underground mine option and includes primary crushing, single train SAG mill and ball mill to produce a target grind size of 80% passing 53 microns, atmospheric pre-oxidation, 48-hour cyanide leach, carbon-in-pulp carousel adsorption circuit, Zadra elution circuit, gold room and filtered tailings. Based on PEA metallurgical test work, the expected recoveries are 91% for gold and 85% for silver.

Filtered tailings will be configured in a dry-stack facility and eliminate the need for the construction and operation of a traditional tailings impoundment, the company says.

“The adoption of this technology (dry stacking) puts the Cerro Blanco project at the forefront of responsible mining practices being adopted for the future of sustainable mining globally,” it added.

Generation Mining readies more ‘aggressive’ Marathon PGM-copper project approach

Generation Mining says it is making headway on the development plan for its Marathon palladium-copper project, in north-western Ontario, Canada, having contracted all the major engineering companies for the study.

The study is expected to take around seven to eight months to conclude, with completion expected in early 2021, it said.

G-Mining Services will carry out the mine plan and mineral reserves, infrastructure scope of work and integration of the costs and economic analysis; Ausenco Engineering Canada is progressing the process facility layout and design based on the metallurgical testing that is currently underway at SGS-Lakefield; and Knight-Piesold is to design the tailings facility and open-pit geotechnical engineering. In support of the feasibility study and environment impact interactions, Stantec and Ecometrix P&E Mining Consultants will be responsible for the mineral resource estimate, the company said.

Jamie Levy, President and Chief Executive Officer of Generation Mining, said: “It is a very impressive team that we have assembled for the feasibility study. I am confident that these firms will optimise the value of the Marathon-PGM property and will continue to de-risk the project.

“Our goal is to maximise the net present value of the project while designing an operation which will minimise environmental impacts and provide economic benefits to the local communities. We see the Marathon project being near shovel-ready and well timed to the buoyant palladium market.”

Generation Mining acquired a 51% interest in the Marathon property from Sibanye Stillwater on July 10, 2019, and can increase its interest to 80% by spending $10 million over a period of four years. As of the March quarter, around $4 million of the $10 million has already been spent.

A preliminary economic assessment on Marathon published earlier this year outlined a 14,000 t/d open-pit operation growing to 22,000 t/d after expansion, with an average palladium output of 107,000 oz/y for 14 years. The open-pit mining would be owner-operated using conventional diesel equipment consisting of 254 mm diameter rotary drills on 10 m high benches, 29 cu.m bucket hydraulic excavators, and 221 t off-highway haul trucks and auxiliary equipment, according to the study.

On the feasibility study, Generation Mining said all groups were “integrating well” through good interactions and frequent communications.

“G-Mining will progress pit designs and sequencing that will prioritise the high-grade palladium values for initial production to bring increased palladium production into the first half of the mine life, and increase copper production in the mine’s later years,” the company said.

“Ausenco’s plant design is expected to update the quality work that was done in prior studies with newer technology, which, in turn, will improve concentrator operability and lower capital costs, while increasing palladium recovery without sacrificing copper recovery. This flowsheet is expected to be validated with the current metallurgical test work that is progressing at SGS-Lakefield.

“Knight-Piesold will be updating the past tailings dam designs to reflect current best available practices and technologies.”

Stantec and Ecometrix are involved in the feasibility study team to help facilitate the update of the Environment Impact Study report addendum and to help inform the critical path regulatory approvals process, the company added.

At this early stage, the work on the feasibility study will consider an optimised processing and mine production rate that is “more aggressive” than outlined in the PEA, the company said, contemplating starting at 5 Mt/y and expanding to 8 Mt/y after five years.