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 how minerals are sourced, refined, and optimized by combining deep industrial expertise with software, automation, and data-driven decision-making. Join us as we build the future of responsible mineral sourcing and supply.

The Role

Mariana Minerals is looking for a highly motivated Hydrometallurgical Process Engineer to work on building the critical minerals supply chain to support the world’s energy transition.

As a Hydrometallurgical Process Engineer at Mariana Minerals, you will lead the development and deployment of first-of-its-kind chemical refining processes, while also supporting development of software for capital project execution and automated plant optimization. Responsibilities will include leading equipment scopes from concept through to design, installation, commissioning, ramp, and handover to the operations team.

What You’ll Do

• Lead hydrometallurgical process equipment scopes from concept development and modeling validation through procurement, detailed engineering, fabrication, installation, commissioning, and ramp-up

• Manage external technology licensors, equipment vendors, and engineering partners to deliver fully integrated and performant hydrometallurgical refining systems

• Develop detailed heat and material balances for complex hydrometallurgical process trains, including leaching, solution purification, solvent extraction/ion exchange, precipitation, crystallization, and residue handling

• Build hydraulic models and process flow diagrams/P&IDs for hydrometallurgical circuits, ensuring operability, reliability, and safety

• Create first-principles models of chemical reactors and unit operations (e.g., leach reactors, autoclaves, SX settlers, IX columns, precipitation reactors, filtration systems) to validate scale-up and derisk commercial designs

• Identify, evaluate, and implement engineering solutions to optimize extraction, purification, and recovery processes under varying chemistry, feedstock qualities, and operating conditions

• Collaborate deeply with R&D, lab staff, pilot-plant engineers, and operations teams to translate bench-scale insights into robust and scalable hydrometallurgical flowsheets

• Work closely with software and machine-learning teams to automate process-engineering workflows and develop advanced control, optimization, and digital-twin models for hydrometallurgical reactors and plants

What You’ll Bring

• 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 hydrometallurgical 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 hydrometallurgical or chemical-process equipment

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

• Hydrometallurgical 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.