About Mariana Minerals

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.

Role Overview

Mariana Minerals is seeking a highly motivated Metallurgical Engineer to support process development activities and pilot-scale testing for our CopperOne mine pilot facility in San Francisco. You will work alongside experienced engineers and technicians supporting our bioleaching columns and other pilot-scale equipment used to develop new mining technologies.

In this role, you will execute metallurgical test work, support pilot plant operations, and contribute to the development and optimization of innovative mineral processing technologies. You will work closely with R&D, technicians, metallurgists, and cross-functional teams to analyze process performance, troubleshoot operational issues, and help scale new technologies from pilot testing toward commercial deployment.

What You’ll Do

• Operate, troubleshoot, and improve leaching columns and other pilot-scale processing equipment in collaboration with technicians

• Plan and execute pilot-scale metallurgical experiments, including sample collection, test execution, and data analysis.

• Develop and maintain key process documentation including PFDs, P&IDs, operating procedures, and mass balances

• Perform material balance calculations and evaluate process performance to identify opportunities for optimization.

• Analyze experimental and operational data to help identify opportunities for process improvement

• Support implementation of process improvements to increase recovery, improve efficiency, and enhance pilot plant performance.

• Support development of automated monitoring and optimization tools in collaboration with software and machine learning teams

• Support safe operations by following EHS procedures and assisting with hazard assessments, risk management, and management of change processes

What You’ll Bring

• B.S. or M.S. in Chemical Engineering, Mining Engineering, Metallurgy, or a related field

• 2–4 years of relevant experience in hydrometallurgy, mineral processing, extractive metallurgy, pyrometallurgy, pilot plant operations, process development, or a related field

• Experience supporting laboratory or pilot-scale metallurgical testing and interpreting experimental results

• Experience with the design, operation, troubleshooting, and optimization of pyrometallurgical reactors, such as kilns, retort furnaces, and fluidized beds

• Experience with high-temperature metallurgical reactions and processes (>800°C)

• Experience with granular material handling operations, including conveying, milling, and mixing

• Proficiency in solid, liquid, and gas characterization methods

• Strong problem-solving skills and the ability to troubleshoot process and operational issues

• Experience analyzing data using Excel, Python, MATLAB, or similar tools is a plus

• Strong commitment to Health, Safety, and Environmental compliance

• Excellent technical writing, communication, and teamwork skills

• Comfortable working in a fast-paced environment, learning new skills, and collaborating across teams

Our culture is built on three principles:

Extreme Ownership – We take full responsibility for outcomes, relentlessly driving toward solutions.

Engineer Out Requirements, then Automate – We simplify, optimize, and then automate for scale.

Share Your Legos – We collaborate openly, share knowledge, and empower each other to build bigger, better solutions.

Join us as we build the future of responsible mineral sourcing and supply.