Tag Archives: Guatemala

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.

Bluestone and G Mining to optimise Cerro Blanco project

Bluestone Resources says it has entered an agreement with G Mining Services covering basic engineering and overall project optimisation efforts for its Cerro Blanco project, in southern Guatemala.

Together, Bluestone and G Mining, a multidisciplinary mining and project management company, will form an integrated project team to manage aspects of the project, covering optimisation of all areas of the design, execution plan, and basic engineering, it said.

It is expected that basic engineering will be completed, and detailed engineering will be initiated, by the December quarter. During this time, the detailed plan for procurement, site early works, construction, and commissioning will be established as part of the next phase of the project, according to Bluestone.

Jack Lundin, CEO of Bluestone, said: “I recently worked alongside the G Mining team at Fruta del Norte, in Ecuador, and we are excited to have them join Bluestone in advancing Cerro Blanco through this important next phase.

“We will be looking to replicate the recent success in Ecuador leveraging key aspects of the execution strategy and team for Cerro Blanco. The Fruta del Norte project was delivered on time and on budget and represents one of the most recent major mining projects to be commissioned in Latin America.”

Key areas of focus in the near term will be optimisation, trade-off, and basic engineering scopes, Bluestone said. The optimisation work will include process and layout trade-off studies, which are currently underway. Further metallurgical test work is nearing completion, which will finalise the flowsheet, allowing equipment selection to be confirmed, according to the company. Basic engineering will be advanced and updated project capital and operating cost estimates will be prepared for the mine, processing facilities, and balance-of-project facilities.

Additionally, Bluestone says it is well advanced on the mine development contract and has been recently building out its recruitment, training plans, and project readiness initiatives. Progress on the project financing package also continues to advance as planned, it noted.

A feasibility study on Cerro Blanco, completed by a consortium of independent consultants led by JDS Energy & Mining, 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, the underground project was projected to generate a post-tax net present value (5% discount) of $241 million.

Doppelmayr RopeCon transporting the tonnes at Guatemala cement operation

Doppelmayr Transport Technology has come up with an innovative way to connect Cementos Progreso SA’s crusher with its new San Gabriel cement plant using RopeCon® material transport technology.

The San Gabriel cement plant is located some 35 km northwest of Guatemala City, Guatemala, where Cementos Progreso produces some 2.2 Mt/y of cement for the local market. The limestone needed for the process is mined in a quarry around 200 m lower than the cement plant, with the terrain between the crusher in the quarry and the plant being hilly and wooded and stretching over a distance of 1.58 km.

The company had been planning to build a new cement plant for some time yet, among other things, the project required an innovative solution to transport the limestone and marl from the crusher over the hilly terrain to the processing plant.

By using RopeCon to transport the limestone between the crusher and the processing plant Cementos Progreso is able to cross the terrain in a straight line despite the topographical situation. This means that a gradient of 22° is reached where the terrain is steepest.

Because the RopeCon belt is fitted with axles with running wheels at regular intervals, no additional cleats were required to tackle that gradient.

The system requires no more than four towers over its entire length and, thanks to the long rope spans between the towers, the amount of space required on the ground can be reduced to a minimum.

The need to interfere with vegetation remains limited to a small number of points and the track does not represent an insurmountable obstacle for wildlife or humans, according to Doppelmayr.

The RopeCon installation has now taken up operation. The material is loaded onto RopeCon by a feeder conveyor and unloaded at the unloading station via a housed-in chute. Some 2,100 t/h of limestone and marl is transported to cover the demand for cement production using a 1,680 kW motor operating at a speed of 3.6 m/s.

RopeCon has been developed by Austrian ropeway manufacturer Doppelmayr to offer the benefits of a belt conveyor as well as those of a cable car by “successfully combining what is best in both technologies”, according to the company.

The system is currently in use for a variety of material transport applications and consists of a cross-reinforced continuous flat belt with corrugated side walls driven and deflected by a drum in the head or tail station. The belt is fixed to axles arranged at regular intervals, which support the belt. Running wheels are fitted to either end of the axles. These run on track ropes with fixed anchoring and guide the belt.

The three track rope pairs form the line structure for the system and are elevated off the ground on tower structures. The system, therefore, requires only a minimum of space on the ground and is ideally suited for difficult terrain and to cross obstacles of all kinds.