Sr./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. ROLE OVERVIEW Mariana Minerals is looking for a highly motivated Sr./Staff Mechanical Engineer to work on building the critical minerals supply chain to support the world’s energy transition. As a Mechanical 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 project execution and plant optimization. You will design, build, and commission mineral processing and metallurgical refining equipment, develop first-principles-based models of refining equipment and processes, and lead equipment scopes from concept through to design, installation, commissioning, ramp, and handover to the operations team. This is a hands-on, first-principles role for an engineer who wants to help build the world’s most advanced minerals refining facilities. WHAT YOU’LL DO - Lead mechanical engineering scopes across project phases—from concept and feasibility through detailed design, procurement, fabrication, installation, and commissioning - Manage vendors throughout the equipment lifecycle—from specification, RFQ, and technical bid evaluation through drawing review and approval, fabrication expediting and inspection (ITP/FAT), delivery, installation and commissioning support, and warranty close-out - Develop site-wide and area-level plant layouts, optimizing equipment arrangement, maintainability access, constructability, safety, and integration with other disciplines - Prepare mechanical equipment specifications, data sheets, and requisition packages for a range of process and solids-handling equipment, and support technical bid evaluations and vendor selection - Perform static equipment design of tanks, silos, bins, pressure vessels, and other stationary equipment, including mechanical sizing, wall/shell thickness, and structural load calculations ensuring code compliance - Conduct finite element analysis (FEA) to validate equipment and component designs for stress, fatigue, thermal, and operational loading conditions - Design, evaluate, and integrate solids-handling and material-conveyance systems, including silos, bins, hoppers, feeders, conveyors, bucket elevators, chutes, and dust-control systems - Support development of 3D models and piping/mechanical interface layouts, ensuring alignment with process, structural, civil, and electrical engineering requirements - Review vendor drawings and calculations, ensuring mechanical design compliance with project requirements, codes, standards, and operability/maintainability expectations - Collaborate with multidisciplinary EPC teams—including process, structural, piping, electrical, instrumentation, and construction management—to deliver cohesive and constructible engineering packages - Provide mechanical engineering support during construction and commissioning, including responding to RFIs, reviewing field changes, and assisting with equipment installation and start-up   WHAT YOU’LL BRING - Bachelor’s degree in Mechanical Engineering or a related engineering discipline - Strong understanding of engineering fundamentals and demonstrated ability to leverage that understanding to solve challenging problems - Experience preparing and reviewing mechanical equipment specifications, vendor documentation, and engineering deliverables for both brownfield modifications and greenfield facilities - Demonstrated ability to complete static equipment design of tanks, silos, bins, vessels, and other stationary equipment, including code-based mechanical and structural calculations - FEA capabilities—proficiency with finite element analysis tools to validate equipment and component designs for stress, fatigue, and thermal/operational loading - Working knowledge of relevant industry standards and codes, such as ASME and API - Ability to work effectively with cross-functional teams, manage competing priorities, and deliver high-quality engineering packages under schedule constraints - Proficiency in mechanical design software such as AutoCAD PREFERRED - Hands-on experience with solids-handling and conveyance equipment, including: Silos, bins, hoppers, chutes, and bulk storage systems | Feeders (vibratory, belt, screw, rotary, apron) | Conveyor systems (belt, screw, drag/chain, pneumatic, bucket elevators) | Screens, crushers, and material-transfer equipment - Experience with pyrometallurgical processes and equipment, such as rotary kilns, electric arc furnaces, converters, dryers, and flash kilns - Familiarity with industrial and process-industry environments, such as: Mining and mineral processing | Cement, aggregate, or bulk-materials handling | Chemical or industrial manufacturing facilities | Power generation or heavy industrial sectors - Experience with fluids, thermal, and Multiphysics CFD simulations 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!