Staff Process Engineer

About the company

Mariana Minerals is a software-first, vertically integrated critical minerals company that engineers, builds and operates mines and refineries using its MarianaOS platform.

About this role

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 seeking a highly motivated Process Engineer to support our next-generation minerals processing pilot plant in Houston. You will help design, deploy, and operate first-of-its-kind refining processes for critical minerals. This role is highly hands-on and will play a key role in bridging R&D and plant operations, helping scale technologies from laboratory development through pilot demonstration and ultimately to commercial production. You will work closely with technicians, engineers, and cross-functional teams to ensure processes are robust, safe, and ready for industrial deployment. WHAT YOU’LL DO - Lead equipment and process design from concept through procurement, fabrication, installation, commissioning, and startup - Operate, troubleshoot, and improve pilot-scale processing equipment in collaboration with pilot plant technicians - Design and execute pilot-scale experiments to evaluate process performance, recovery, throughput, and product quality - Develop and maintain key process documentation including PFDs, P&IDs, mass and heat balances, operating procedures, and control narratives - Analyze experimental and operational data to identify opportunities for process optimization and scale-up - Support development of automated plant monitoring and optimization tools in collaboration with software and machine learning teams - Ensure safe operations by supporting EHS, hazard assessments, risk management, and management of change processes WHAT YOU'LL BRING - B.S., M.S., or PhD in Chemical Engineering or a related field - 10+ years of experience in operations, process scale-up, or plant design in minerals processing, chemicals, specialty materials, oil & gas, or related industries - Demonstrated experience driving equipment design, commissioning, and plant operation - Strong understanding of relevant unit operations and equipment such as kilns, furnaces, ion exchange, solvent extraction, solid liquid separation, leaching, electrowinning, or similar technologies - Ability to design experiments, troubleshoot complex processes, and analyze operational datasets - Strong commitment to Health, Safety, and Environmental compliance - Excellent technical writing, communication, and teamwork skills - Comfortable working in fast-paced environments, wearing multiple hats, and managing ambiguity 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.