Mechanical Engineer

Department: Plant & Process Engineering

Location: San Francisco HQ, Houston, TX

Compensation: $100K – $160K • 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 how minerals are sourced, refined, and optimized by combining deep industrial expertise with software, automation, and data-driven decision-making. Join us as we build the future of responsible mineral sourcing and supply.

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. Responsibilities will include designing, building, and commissioning pilot and modular commercial scale plants, developing first principles based models of refining equipment and processes, and leading equipment scopes from concept through to design, installation, commissioning, ramp, and handover to the operations team.

What You’ll Do

• Lead mechanical engineering scopes across project phases—from concept and feasibility through detailed design, procurement, fabrication, installation, and commissioning

• 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

• Design, evaluate, and integrate solids-handling and material-conveyance systems, including silos, bins, hoppers, feeders, conveyors (belt, screw, drag), 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

• Strong understanding of engineering fundamentals and demonstrated ability to leverage the understanding to solve challenging problems

• Experience preparing and reviewing mechanical equipment specifications, vendor documentation, and engineering deliverables for both brownfield modifications and greenfield facilities

• 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

• 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

• Working knowledge of relevant industry standards and codes, such as CEMA, ASME, API, and material-handling design guidelines

• Ability to work effectively with cross-functional teams, manage competing priorities, and deliver high-quality engineering packages under schedule constraints

• Proficiency in mechanical designs software such as AutoCAD

• Experience with fluids, thermal, and Multiphysics CFD simulations a plus

Mariana is an Equal Opportunity Employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We do not discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, veteran status, or any other protected status.