Mechanical Engineer

Department: Plant & Process Engineering

Location: San Francisco HQ, Houston, TX

Compensation: $140K – $175K • Offers Equity • Estimated Base Salary, Final salary dependent on level of experience, location, and other factors.

Employment Type: FullTime

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 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 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.