Staff Mechanical 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 Staff Mechanical Engineer to support our next-generation minerals processing pilot plant in Houston. You will lead the design, integration, and deployment of pilot-scale mechanical systems and processing equipment used to demonstrate and scale innovative refining technologies for critical minerals. This role is highly hands-on and will play a key role in building and maintaining a first-of-its-kind pilot plant. You will work closely with process engineers, technicians, and cross-functional teams to design, install, commission, and improve pilot-scale equipment while ensuring systems are reliable, safe, and scalable to commercial production. WHAT YOU’LL DO - Design, specify, and deploy mechanical systems and equipment for pilot-scale mineral processing operations - Work closely with process engineers to translate process requirements into practical mechanical and plant designs - Support installation, troubleshooting, and maintenance of pilot plant equipment including pumps, piping systems, reactors, separators, filtration systems, and material handling equipment - Develop and maintain mechanical design documentation including equipment specifications, layout drawings, piping schematics, and CAD models - Identify opportunities to improve equipment reliability, maintainability, and operational performance - Coordinate with vendors, fabricators, and contractors during equipment procurement and installation - Support safe plant operations by contributing to hazard reviews, equipment safety design, and mechanical integrity programs DESIRED QUALIFICATIONS - B.S., M.S., or PhD in Mechanical Engineering or a related field - 9+ 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, operations, and reliability - Experience designing and maintaining furnaces, pumps and fluid handling systems, pressure vessels and reactors, piping systems and valves, filtration and separation equipment, and materials handling systems - Ability to work closely with cross-functional teams including process engineering, operations, and project execution - Strong troubleshooting and problem-solving skills in hands-on plant environments - Strong commitment to Health, Safety, and Environmental compliance and mechanical integrity standards - 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.