Tag Archives: Merrill Crowe

SNC-Lavalin to manage construction of Coeur’s Rochester silver-gold mine expansion

SNC-Lavalin has been awarded a $30 million contract by Coeur Rochester Inc, a wholly-owned subsidiary of Coeur Mining, to provide construction management services for the Plan of Operations, Amendment Number 11 (POA 11) expansion project, at Coeur’s Rochester mine near Lovelock, Nevada, USA.

The contract commenced in the December quarter and is estimated to be completed by the end of 2022. This win is aligned with SNC-Lavalin’s new strategy moving forward in the Services segment, it said.

The POA 11 expansion project includes the construction of a new crushing plant, including a primary, secondary and tertiary crushing circuit (high pressure grinding rolls), a new heap leach pad (272 Mt), a new Merrill-Crowe process plant (62,509 litres/min), and upgrades to existing electrical utility system infrastructure, including a new substation and power distribution lines.

Coeur says this will more than double planned annual crusher throughput capacity from around 12.7 Mt to over 25.4 Mt, post-expansion. This will see average annual silver and gold production total over 8 Moz and some 80,000 oz, respectively, for the initial 10 years, post-expansion

SNC-Lavalin said: “This mandate is well aligned with our expertise in silver, gold and base metal project delivery as well as our commitment to delivering real value to our clients.”

SNC-Lavalin’s offices in Reno, Nevada, and Toronto, Ontario, will continue to support the construction management phase of the project. In addition, a team based locally at the site will manage construction-related activities.

César Inostroza, Senior Vice-President, Mining & Metallurgy, SNC-Lavalin, said: “SNC-Lavalin’s Mining & Metallurgy strategic plan is gaining traction with this mandate. It is an example of the mining services work that our team is winning across our core geographies, including the USA. SNC-Lavalin and Coeur continue to foster a strong relationship that finds and executes services solutions to create world-class operations

“This award is a testament to the continued partnership between SNC-Lavalin and Coeur. It leverages our knowledge of the Rochester mine and engineering expertise from the previous phase of this project and expands our work in the US.”

Terrence FD Smith, Coeur’s Senior Vice President and Chief Development Officer, added: “The strong business partnership between Coeur and SNC-Lavalin will help ensure a robust project delivery for Rochester, paving the way for improved performance in the future.”

Since approval of the initial Plan of Operation in 1986, the Rochester mine has undergone periodic mine plan amendments to support development projects and continued operations. The POA 11 proposes another mine life extension, which is expected to maintain the current workforce and support full production activities at Rochester until 2033.

Orla Mining on course for first gold in 2021 at Camino Rojo Oxide project

The publication of the updated feasibility study on Orla Mining’s Camino Rojo Oxide Gold asset in Zacatecas, Mexico, has come with a 54% increase in contained gold reserves and a 3.5-year extension to the mine life of the in-construction project.

The new reserve estimate at Camino Rojo includes a proven and probable total of 67.4 Mt at 0.73 g/t Au and 14.5 g/t Ag, for total mineral reserves of 1.59 Moz of gold and 31.5 Moz of silver.

The updated study outlined open-pit mining of 67.4 Mt of oxide and transitional ore at a rate of 18,000 t/d. Ore from the pit will be crushed to 80% passing 28 mm, conveyor stacked onto a heap leach pad and leached using a low concentration sodium cyanide solution. Pregnant solution from the heap leach will be processed in a Merrill-Crowe recovery plant where gold and silver will be precipitated and doré will be produced. The site’s proximity to infrastructure, low stripping ratio, compact footprint and flat pad location all contribute to the project’s simplicity and low estimated all-in-sustaining costs of $543/oz of gold, the company said.

An after-tax net present value (5% discount) of $452 million was calculated by the study team led by Kappes Cassiday and Associates and supported by Independent Mining Consultants, Resource Geosciences Inc, John Ward Groundwater Consultant, Barranca Group, Piteau Associates Engineering and HydroGeoLogica Inc.

The main notable physical changes from the 2019 feasibility study are an increase in the size of the open pit, heap leach pad, and mine waste dump because of a layback agreement with the adjacent Fresnillo mine, all of which were anticipated in the initial design. While all material to be mined on the Fresnillo concession has been classified as waste in the latest study, Orla sees opportunities to further expand the reserve and resource base following further work on material in this area.

Jason Simpson, President and Chief Executive Officer of Orla, said: “The updated feasibility study for the Camino Rojo Oxide project demonstrates an increase in recovered gold, mine life, and cash flows.

“An already excellent project has been improved due to the hard work of the entire Orla team and I thank them for their efforts. We are pleased to announce this important enhancement and we will continue to optimise this asset as we move through construction and into production.”

Detailed engineering of the project described in the 2019 feasibility study is over 90% complete and procurement is 85% complete, with the start of earthworks announced on November 26, 2020. Since that time, 230 ha have been cleared for construction activities with over 20,000 cu.m of topsoil being removed and stockpiled. Equipment deliveries to site commenced in December, with a total of $78 million of the total project capital committed through purchase orders and contracts.

Orla says the mining contract is being finalised and expected to be in place early in the March quarter, with first gold production planned for late 2021.

Hycroft Mining ups the proprietary heap leach process ante

Hycroft Mining Holding Corp has continued to demonstrate the viability of its proprietary heap leach oxidation process at its Hycroft gold mine in Nevada, USA, over the June quarter, with the company hitting several milestones.

The Hycroft gold-silver mine was restarted in 2019 to demonstrate this process, which oxidises sulphides prior to leaching, on a commercial scale. Based on the success of initial operations and a 2019 feasibility study, Hycroft began implementing the long-term mine plan with the start of construction in April 2020 of the first phase of a large leach pad capable of processing the resource base with more than 30 years of mine life.

While gold and silver production fell below expectations over the period, the company was able to demonstrate the process on initial leach pads one and two at Hycroft, achieving higher than feasibility level gold recoveries for Brimstone ore (82% versus 65% in the feasibility study) and Central ore (91% versus 70% in the feasibility study).

It also improved the solution management system to increase solution distribution to the leach pads, while commencing the leach pad expansion on the north side of the mine in anticipation of starting heap leach stacking in the December quarter of 2020, Hycroft said.

The expansion project will provide the company with the leach pad space required for future operations, the company added.

“The initial stage of the leach pad project is being constructed in two phases by a contractor, with the first phase consisting of approximately 4 million sq.ft (3.7 million sq.m) of pad space and infrastructure for ponds, pipes and electricity, and the second phase consisting of approximately 4.6 million sq.ft, which we expect to construct in 2021,” the company said.

“With respect to the first phase, we expect the earthworks and leach pad construction to be completed in the fourth (December) quarter of 2020 and infrastructure completed and initially commissioned shortly thereafter.”

On the process side, the downstream process infrastructure is in place to ramp up operations. Hycroft is currently operating the Brimstone Merrill-Crowe facility and refinery, but it has begun planning to restart the 21,500 gallons/min (1,629 l/s) North Merrill-Crowe plant in 2021 to meet increasing solution flows from the new leach pad.

To facilitate these heap leach changes, the company expanded its mining fleet with the rental of seven 240 ton (218 t) trucks and one loader to increase mining capabilities over the quarter. It also improved its mobile equipment maintenance team to transition to self-performed maintenance and discontinue the contractor-led maintenance applied since start-up. Lastly, it began active in-pit drilling and blasting of fresh ore and reduced the mining of stockpiles.

On the crusher side, it refurbished and recommissioned the crushing system, which saw the average amount of material crushed go from 338,000 tons/mth (306,628 t/mth) in the March quarter to 459,000 tons/mth in the June quarter, an increase of 36%. It also established a comprehensive preventative maintenance program and initiated an ongoing operator training program to improve crusher efficiency and reduce downtime.

Steve Jones, Interim President and CEO of Hycroft Mining, said: “There have been a number of improvements at the mine recently that are building a strong foundation for the next phase of operations, including adding experienced technical people and increasing the reliability of process infrastructure.

“While the next few months are still considered to be transitional, we are looking forward to utilisation of the new leach pad and being able to ramp up to feasibility study operating levels.”

FLSmidth to provide gold processing package to Gold Fields’ Salares Norte

FLSmidth says it has sold three system packages to Gold Fields for its greenfield Salares Norte project in Chile.

The large downstream gold product line project comprises, FLSmidth says, three complete process islands: a Merrill Crowe, an AARL (Anglo American Research Laboratories) elution circuit and a refinery.

The process plant will treat 2 Mt/y of ore and is expected to produce an average of 2.6 Moz of silver and 286,000 oz of gold annually during its first seven years in operation, FLSmidth said.

FLSmidth’ s systems were chosen for their proven quality and the durability of the technologies involved, according to the OEM. “These factors were crucial for the customer given the modular, fully-automated and custom design required for the specificities of the gold mine, which is situated in the Atacama region of northern Chile at 4,500 m in elevation,” FLSmidth said. “Given the high altitude, it was important that the systems were as automated as possible, with the option of remote monitoring.”

The company added: “Salares Norte further solidifies our position as a premium supplier of projects and solutions even in the most challenging conditions. This contract is also noteworthy given how few new, large gold/silver mines have been established in South America in recent years. Supplying a significant portion of the flowsheet gives FLSmidth another strong reference with a major gold miner.”

Outotec and Metso have also won major orders for Salares Norte.

Jorge Carvajal, Project Sales Director, said: “These orders are the result of work well done and close collaboration. This, in conjunction with a strong focus on our customer during the entire process, were crucial in solidifying our position as a key technical solutions provider in the gold market.”

Northern Vertex Mining ready for more gold at Moss mine

Production looks like increasing at Northern Vertex Mining’s recently started up Moss gold-silver mine, in Arizona, USA, as recent modifications to the Merrill Crowe facility and additional output from the heap leach kick in.

The company produced 7,482 oz of gold and 45,876 oz of silver during the three months to the end of June, compared with 6,057 oz of gold and 25,558 oz of silver, marking the company’s strongest quarter to date. In June, alone, Northern Vertex saw 2,580 oz of gold and 18,051 oz of silver come out of the operation.

The Moss open pit and heap leach gold and silver mine hit its commercial straps in September 2018, at which point the company said expected fiscal 2019 production guidance was 36,000-40,000 oz of gold equivalent production.

Northern Vertex said this week that its operations team has made progress in correcting issues that have hampered the process plant since started up, with modifications to the filter press piping, clarifiers and vacuum pump system nearing completion.

“We have observed a large decrease in reagent consumption and an immediate improvement in recoveries of gold and silver from the pregnant solutions,” the company said.

Such improvements to the Merrill Crowe facility recently resulted in the company’s single largest gold shipment to date – of $1.2 million representing nine days of production.

The Moss team initiated a recovery study of the heap leach pad in May 2019, with the purpose to confirm consistent moisture percolation throughout the pad; measure solution volume and solution grade retained in various areas (panels) of the pad, in order to determine the gold and silver inventory remaining on the pad; obtain samples for further bottle roll testing, in order to estimate the amount of gold inventory that can be recovered by re-leach; and design and implement a leach solution application plan to recover additional gold from the leach pad inventory.

Results from the first panel (known as the ‘Central Panel’), which contains approximately 235,000 t of ore have been received, the company said. “Results show remarkable consistency in the percolation of solution, both laterally and vertically. Furthermore, the study confirms there are no dry areas, channelling is not occurring, the pad is retaining its moisture as expected and that the recoverable gold and silver in inventory will meet or exceed feasibility predicted recoveries.”

While the full study, which will include an additional five panels is ongoing, Jim Gubler, Process Manager at Northern Vertex, said the results from the Central Panel indicated there are around 5,000 oz of recoverable gold contained in this area, of which an “estimated 3,000 oz have already been dissolved in the water held in the heap and need only to be flushed and collected”.

He added: “With the leach solution application plan that we have designed, we are projecting that a significant portion of this gold will be recovered over the next several months, which should add to our normal monthly production.”

The ongoing column test program (using crushed ore samples) is predicting ultimate recoveries of approximately 80% for gold and 60% for silver from the heap leach. The column test work on the crusher samples and the heap leach pad recovery study described above will also be used to optimise and shorten the recovery curves going forward, using live ore panels for testing rather than bulk samples that were used in the feasibility, Northern Vertex said.

“Every current test being run indicates that we should be able to outperform the feasibility recovery curves,” the company concluded.