Tag Archives: Santa Cruz

Ivanhoe Electric planning for all-electric underground fleet and Railveyor tech at Santa Cruz copper project

Ivanhoe Electric has published the results of an Initial Assessment (IA) carried out on its Santa Cruz copper project, in Arizona, USA, highlighting the potential to build a 5.9 Mt/y underground mining operation that uses an all-electric underground heavy mining fleet, in combination with Railveyor technology for material movement.

The use of an all-electric underground heavy equipment fleet alone represents an estimated 70-80% reduction in Scope 1 emissions when compared to a traditional high-efficiency diesel-powered heavy equipment fleet, Ivanhoe says, adding thatthe use of Railveyor technology would further the efficiencies associated with moving mined mineralisation from underground to surface.

The IA base case assumes 70% of the total electric power requirements for the project will be generated by on-site renewable infrastructure, enabling copper production with very low carbon dioxide equivalent (CO2e) emissions of 0.49 t of CO2e per tonne of copper for Scope 1 and 2 emissions. This compares favourably with a global mining industry average of approximately 3.9 t of CO2e per tonne of copper equivalent, Ivanhoe says. The subsequent prefeasibility study for the project will evaluate the potential use of combined solar power, battery storage and a geothermal-driven microgrid as renewable power sources to provide up to 100% of the electricity requirements for the project.

The Santa Cruz IA outlines a potential 5.9 Mt/y underground mining operation, supported by 105.2 Mt of modelled mill feed with an average grade of 1.58% Cu from the Santa Cruz and East Ridge Deposits, resulting in an estimated 20-year mine life.

The IA focuses exclusively on the high-grade exotic, oxide and enriched domains of the Santa Cruz and East Ridge Deposits, with the oxide and enriched domains of the Texaco deposit not included in the current study (2.7 Mt indicated grading 1.42% total copper and 27.3 Mt inferred grading 1.39% total copper, using a 0.80% cut-off grade).

Future studies could evaluate the potential addition of the large primary sulphide domains at Santa Cruz (76.2 Mt indicated grading 0.88% total copper and 8 Mt inferred grading 0.92% total copper, using a 0.70% cut-off grade) and at the Texaco Deposit (900,000 t indicated grading 1.05% total copper and 35 Mt inferred grading 1.06% total copper, using a 0.80% cut-off grade), subject to market conditions.

Copper recoveries of 95.4% are expected to be achieved through a combination of solvent extraction and electrowinning and conventional froth flotation. The IA includes life of mine production for the project of 1 Mt of copper in the form of 99.99% pure copper cathode and 600,000 t of copper contained in a 48% copper concentrate with very low deleterious elements, such as arsenic or lead.

The IA contemplates initial project capital expenditures of $1.15 billion, and life of mine sustaining capital expenditures totaling $0.98 billion. A three-year construction period is envisioned to develop the underground workings and build the surface processing facilities.

As a result of the small surface footprint required for underground copper mining activities included in the IA, the total land area expected to be required for the mine, plant, tailings storage facilities and potential on-site generation of renewable solar power covers approximately one-third of the total land package.

The IA also contemplates placing 50% of the mine tailings back underground as cemented paste fill. The remaining 50% will be stored on the surface as thickened tailings at 65% solid content. Surface tailings will be contained within a ring dyke dam with a capacity to store 56.7 Mt. Water management associated with tailings storage is minimised as a result of thickened tailings and high evaporation rates in the Sonoran Desert, the company says.

Executive Chairman, Robert Friedland, said: “Completing the Initial Assessment for our Santa Cruz copper project is an important achievement for Ivanhoe Electric as we work to advance a new source of responsibly produced ‘green’ copper in the United States. Our goal is to develop a modern copper mine that produces copper with among the lowest levels of carbon dioxide output in the industry; a product we think has the potential to attract a premium price in the future.

“Using primarily on-site renewable electricity generation, and with the potential to increase that to meet the project’s entire future needs, the IA shows us that we are on the right track to achieving our goal at Santa Cruz and our larger goal of enhancing US supply chain independence for critical metals. We are excited about the future for our Santa Cruz project in Arizona.”

In the IA, twin declines, each measuring 4.3 km, would be developed to access the upper parts of the Santa Cruz and East Ridge deposits. One decline is required for air intake and access, while the other will be required for air exhaust and material movement. To develop the declines, the IA assumes that construction of the portal box cut would begin in 2026, decline development in 2027 and continues through 2028 to access the top portion of the mine. Under these assumptions, stoping activities would begin in 2029 with a one-year ramp up to the full 15,000 t/d capacity.

Mining of the upper portion would proceed for the first eight years before additional capital expenditures are required to extend the declines by 1.9 km. Additional surface infrastructure would be required once mining of the lower portion commences. This would include the second phase construction of a refrigeration plant, ventilation, water handling and material handling.

Mine sequencing would employ typical transverse longhole stopes for the Santa Cruz deposit on a primary-secondary sequence with paste backfill for support. Mining of the Santa Cruz exotic mineralisation has been evaluated using a drift and fill technique with access from the Santa Cruz longhole stoping levels. The East Ridge deposit will apply a drift and fill mining technique with access directly from the twin declines.

Over the total life of mine, 105.2 Mt of mineralised material is expected to be mined. This includes 88.6 Mt from the Santa Cruz deposit, 1.9 Mt from the Santa Cruz exotic mineralisation, 9.8 Mt from the East Ridge deposit and 4.9 Mt of low-grade material required to access the deposits.

Sandvik Mining and Rock Solutions bolsters Argentina service offering

To reduce response times, increase service quality and be closer to key mining clients, Sandvik Mining and Rock Solutions is decentralising its workshop in Buenos Aires, Argentina, to invest in a service centre in Caleta Olivia in the Province of Santa Cruz.

The maintenance and repair workshop for mining equipment, which opened in July, is strategically located and equipped with advanced systems such as South America’s first test bench for transmissions, axles and converters, according to Sandvik. It not only allows for the equipment to rotate, but can also take a heavy load, helping to guarantee reliability and quality of repairs.

“The objective of the Sandvik service centre in Caleta Olivia is to deliver results with high quality standards, in a timely manner,” Sebastián Issel, Country Manager of Sandvik Argentina SA, said. “To do this, we are strongly committed to the strategic development of local suppliers.”

The workshop entails a reception area, a 1,775-sq.m service area for repairs (featuring capacity for four service teams), a specific area for component repairs, training rooms and offices. The workshop is designed to carry out repairs of all types of components and equipment that Sandvik currently has in service in Argentina, including surface and underground drills and underground trucks and loaders.

The new facilities will also serve to complement training connected to mine sites for Sandvik technicians and customer representatives alike, Sandvik said.

As a supplier to many key mining operators in the southern region of Argentina, Sandvik says it sees the opening of the new service centre as an important move to provide a more localised service offering. The opening of the Caleta Olivia workshop represents a distribution point and satellite to have a faster response when a customer needs a specific component or spare part, it said. Its location in Caleta Olivia allows for less travel and smooth shift changes for service technicians.

Sandvik’s presence in key mining and construction provinces in Argentina delivers, the company says, a strategic combination for customers in the area, with the headquarters located in San Justo and the facilities in Caleta Olivia serving as the distribution and repair centre in the region.

South Star’s filtered tailings plan for Santa Cruz graphite project stacks up

South Star Mining Corp’s aim of using a filter press and eliminating the requirement for a tailings storage facility at its Santa Cruz graphite project in Bahia, Brazil, has been given a boost following positive bench scale test results.

The Toronto-listed company said it had received positive results for the laboratory bench scale filtered tailings tests performed on two simulated tailings samples from Santa Cruz. Two tailings samples (+325 mesh and -325 mesh) were generated and tested in laboratory facilities in Belo Horizonte, Brazil, it said.

Five scenarios were completed for the leaf filter tests with various solids densities, feed rates, vacuum pressures, and cake thickness:

  • -325 mesh sample at 10% solids;
  • -325 mesh sample at 10% solids at higher feed rate and vacuum pressures;
  • -325 mesh sample at 20% solids;
  • -325 mesh sample at 20% solids with minimized cake thickness, and;
  • +325 mesh sample at 10% solids.

The tests resulted in cake with humidity varying between 23% to 35% and cycle times ranging from 19:23 to 49:47 minutes, according to the company. Based on the bench scale leaf tests, additional pilot tests are being performed to better quantify the range of possible solutions and also test a mixture of the +325 and -325 mesh materials to create a third sample type, the company said, adding that results of the pilot tests were expected shortly.

South Star said the goal of the testing programme was to examine the potential for altering the proposed flow sheet from the process circuit presented in the preliminary economic assessment (PEA) to include a filter press and eliminate the requirement for a tailings storage facility.

“By incorporating filtered tailings technology, the majority of the water from the tailings would be removed and recirculated and allow the dried tails to be placed together with waste rock in a co-disposal waste facility,” the company said.

South Star CEO, Eric Allison, said: “We are very pleased with these initial results from our filtered tailings test programme and their positive implications for utilising dry stack tailings at Santa Cruz for both our trial mining plant and the final full-scale facility. Co-disposal of the waste should not only reduce the project’s environmental impact, risk profile and physical footprint, but should streamline our permitting and licensing processes as well.”

The company plans to incorporate the results of the programme into the prefeasibility report scheduled for completion in the September quarter, it said.

The mid-2017 PEA on Santa Cruz outlined an indicated resource of 14.99 Mt at 2.70% Cg with 404,741 t Cg, and inferred resources of 3.57 Mt at 2.90% Cg with 103,591 t Cg. Graphite deposition at Santa Cruz is found at surface within oxidised material providing a very favourable strip ratio, and requiring no crushing or blasting, according to the company.

The PEA stated Santa Cruz has a post-tax internal rate of return of 78% and a payback period of two years. Mine planning for the existing graphite deposit outlined a 12 Mt mineable resource with a diluted grade of 2.63% Cg providing support for a 19-year open-pit mine. Life of mine average yearly production came in at 15,800 t alongside operating costs of $413/t.