Mechanical Engineer

Mariana Minerals is a software-first, vertically integrated minerals company on a mission to supply the critical minerals powering modern energy, AI, and defense technologies. We’re reimagining the minerals supply chain by combining deep industry expertise with advanced software, automation, and data-driven decision-making.

Mariana Minerals is looking for a highly motivated Mechanical Engineer to join our San Francisco Pilot Plant team. You will support the design, installation, and maintenance of first-of-its-kind refining processes for critical minerals. This position plays a critical role in bridging R&D and Operations, ensuring our equipment and work processes are robust, safe, cost-effective, and suitable for commercial production.

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  Drive design, fabrication, installation, modification, startup, and commissioning of new equipment and pilot plant systems.

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  Troubleshoot mechanical issues and implement practical solutions to maintain safe, reliable, and efficient plant operations.

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  Work closely with process engineers and R&D scientists to translate process requirements into equipment modifications, mechanical designs, and plant improvements.

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  Create and maintain engineering documentation, including P&IDs, process and control narratives, equipment specifications, drawings, CAD models, and equipment manuals.

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  Identify opportunities to improve equipment reliability, maintainability, and operational performance

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  Support the development of software and to help drive rapid equipment design, plant reliability, and safe operation

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  Travel to Mariana sites to support new projects, start-up/commissioning, and troubleshooting initiatives

• B.S., M.S., or PhD in Mechanical Engineering or a related field

• Experience in automated manufacturing, operations, process scale-up, or plant design in minerals processing, chemicals, specialty materials, oil & gas, or related industries

• Demonstrated experience driving equipment design, commissioning, operations, and reliability

• Ability to wear multiple hats and take on additional scope in areas such as process engineering, operations, maintenance, and project execution

• Strong troubleshooting and problem-solving skills in hands-on plant environments

• Strong commitment to Health, Safety, and Environmental compliance and mechanical integrity standards

• Excellent technical writing, communication, and teamwork skills

• Comfortable working in fast-paced environments and managing ambiguity