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 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!