Robbins 9.3m diameter TBM planned for Santa Cruz copper mine

Ivanhoe Electric is planning to use a remanufactured 9.3m-diameter Robbins Crossover XRE TBM to excavate a 4km-long mine access decline at its Santa Cruz Copper Project in Arizona, where the company has now secured an indication of up to US$1.1bn in potential debt financing. A portion of the machine components have been used previously for the excavation of two declines at Anglo American’s Grosvenor coal mine in Queensland, Australia, These components along with newly manufactured components are expected to arrive for assembly in Arizona in the first quarter of 2027. Tunnelling is scheduled to start in the third quarter of that year, with the 4km drive targeted for completion in approximately 12 months. The US Export-Import Bank (US EXIM) has issued Ivanhoe Electric with a Preliminary Project Letter (PPL) for potential financing of US$1.1bn for Santa Cruz, up from the US$825M indicated in an April 2025 Letter of Interest. The financing remains subject to further review and approval, with final US EXIM board consideration anticipated in spring 2027. Ivanhoe Electric identified the availability of the Robbins TBM in late 2025 and secured a binding option to acquire it from Robbins in March this year. Robbins, in turn, agreed to reacquire the machine from Anglo American. The Robbins Crossover XRE is designed for variable ground, the machine can operate through hard rock, in pressurized or EPB mode for wet and running ground and mixed-face conditions during a single drive. Ivanhoe Electric said investigations at Santa Cruz indicate that these conditions will be encountered during decline construction. The machine combines EPB capability with a bi-directional cutterhead and high-torque cutterhead drive. Its EPB mode allows the cutterhead chamber to be pressurised against groundwater to maintain face stability and control inflows when crossing water-bearing zones and aquifers. During excavation, the TBM will erect a continuous sealed lining of steel-reinforced precast concrete segments, creating a permanent flat-bottomed decline. The system will also incorporate a permanent conveyor which has also been designed and supplied by Robbins which will initially remove excavated material during the TBM boring operations before being retained for ore handling during mine production. Robbins will carry out a substantial overhaul and remanufacturing of the TBM before delivery to Arizona, including complete refurbishment of the 9.3m-diameter cutterhead at its facilities in Ohio. The TBM will also receive updated technology and modifications tailored to the anticipated Santa Cruz geology. Ivanhoe Electric puts the acquisition cost of the TBM and material handling system, including refurbishment, at approximately US$64.7M. The mechanised tunnelling solution replaces the roadheader excavation, silica gel grouting and Railveyor material handling system proposed in the project’s 2025 Preliminary Feasibility Study (PFS). Ivanhoe Electric estimates the resulting net increase in initial project capital at less than US$20M. The change also removes the requirement for a Class V Underground Injection Control permit associated with the proposed silica gel grouting. Box-cut excavation for the decline is scheduled to begin in the third quarter of 2026. Following TBM excavation from Q3 2027, underground mine development is scheduled to begin in Q3 2028, with first copper cathode production targeted for Q2 2029. The TBM could have a role beyond the initial Santa Cruz development. Ivanhoe Electric said ownership of the machine would give it the capability to pursue future expansion, including development towards the Texaco copper deposit approximately 2km northeast of Santa Cruz. An updated PFS, expected in September, will incorporate the TBM decline, material handling system and engineering work undertaken since the 2025 study. US EXIM’s PPL follows preliminary due diligence on Santa Cruz and represents a step towards a potential financing agreement rather than a firm funding commitment. The application is being considered under the bank’s Make More in America Initiative, which supports US projects intended to increase domestic production and strengthen critical supply chains. Santa Cruz is planned as an underground operation producing 99.99% pure copper cathode onsite without conventional smelting. Comments: