Sr. Pyrometallurgical Process Engineer

Department: Plant & Process Engineering

Location: San Francisco HQ, Houston, TX

Compensation: $130K – $160K • Offers Equity

Employment Type: FullTime

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.

The Role

Mariana Minerals is looking for a highly motivated Pyrometallurgical Process Engineer to help build the critical minerals supply chain supporting the world’s energy transition.

As a Pyrometallurgical Process Engineer at Mariana Minerals, you will lead the development and deployment of first-of-its-kind high-temperature refining and thermal processing systems. You will play a central role in designing, modeling, scaling, and commissioning pyrometallurgical unit operations, while supporting development of software tools for capital project execution and automated plant optimization.

Responsibilities include leading equipment and process scopes from concept and modeling validation through detailed engineering, installation, commissioning, ramp-up, and handover to operations.

What You’ll Do

• Lead pyrometallurgical process scopes from early concept development and thermodynamic modeling through procurement, detailed engineering, fabrication, installation, commissioning, and ramp-up

• Develop detailed heat and material balances for high-temperature process trains, including drying, calcination, roasting, reduction, smelting, converting, slag cleaning, refining, and off-gas treatment

• Design and validate thermal process flowsheets and PFDs/P&IDs for pyrometallurgical circuits, ensuring safety, reliability, and scalability

• Build first-principles thermodynamic and kinetic models for high-temperature reactors and furnaces (e.g., rotary kilns, calciners, electric arc furnaces, submerged arc furnaces, reverberatory furnaces, flash smelters) to support scale-up and commercial deployment

• Model and optimize phase equilibria, slag chemistry, metal recovery, refractory performance, and energy efficiency

• Define specifications and operating envelopes for high-temperature process equipment, burners, power systems, refractory linings, and gas-handling systems

• Identify, evaluate, and implement process improvements to maximize metal recovery, minimize energy consumption, control emissions, and ensure stable furnace operation under varying feedstock chemistries

• Collaborate closely with R&D, lab teams, and pilot-plant engineers to translate bench- and pilot-scale findings into robust commercial pyrometallurgical designs

• Work with environmental and controls teams to design and optimize off-gas handling systems (e.g., cyclones, baghouses, scrubbers, thermal oxidizers, heat-recovery systems)

• Partner with software and machine-learning teams to automate process-engineering workflows and develop advanced control, optimization, and digital-twin models for high-temperature reactors and furnaces

Desired Qualifications

• Strong understanding of engineering fundamentals and demonstrated ability to leverage the understanding to solve challenging problems

• Strong foundation in chemical engineering, metallurgical engineering, or process engineering, with demonstrated ability to apply engineering fundamentals to complex pyrometallurgical systems

• Experience with equipment engineering and design. Including but not limited to:

• Brownfield modifications and upgrades of process equipment (e.g., leach tanks, reactors, filtration systems, solvent extraction circuits)

• Greenfield design of hydrometallurgical unit operations and integrated circuits

• Troubleshooting, evaluation, and optimization of operating pyrometallurgical or chemical-process equipment

• Experience with the following industries and/or production environments:

• Pyrometallurgical mineral processing or metal refining

• Large-scale mining, critical-minerals processing, or battery-materials production

• Industrial chemical manufacturing with complex aqueous/chemical reaction systems

• Engineering, procurement, and construction (EPC/EPCM) firms supporting mining and mineral processing industry projects

Why Join Us?

At Mariana Minerals, you’ll be part of a mission-driven team reshaping the way critical minerals are sourced and supplied globally. You’ll have the autonomy to make big decisions, the tools to innovate, and a culture that values ownership, smart automation, and collaboration.

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.

Mariana is an Equal Opportunity Employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We do not discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, veteran status, or any other protected status.