Staff Process Engineer

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 FOUR PRINCIPLES: Everyone Gets Home Safe. We never put speed or cost ahead of people. 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!