Marianaminerals
Sr. Process Engineer
San Francisco HQ
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hirly's read of this role
- Role family
- Supply chain
- Seniority
- Senior
- Work mode
- On-site / unstated
- First seen by hirly
- 1 Sept 2026
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the posting
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. Process Engineer to join our San Francisco Pilot Plant team. You will lead the design, deployment, and operation of first-of-its-kind refining processes for critical minerals, while also supporting development of software for automated plant optimization. This position is highly hands-on and will play a critical role in bridging R&D and Operations, ensuring processes are robust, safe, cost-effective, and suitable for commercial production.
What You’ll Do
Work closely with Pilot Plant Technicians to operate, maintain, troubleshoot, and improve pilot-scale processing equipment
Design experiments to evaluate process performance, recovery, throughput, and product quality
Create and maintain key engineering and operational documentation such PFDs, HMBs, P&IDs, Operating Procedures, and Process Control Narratives
Lead equipment design scopes from concept, through procurement, fabrication, installation, commissioning, and handover to Operations
Work closely with cross-functional teams including R&D, commercial plant design engineers, project execution teams, and more to scale designs from lab to the pilot to production scale
Work closely with the software and machine learning teams to develop and implement reactor and plant optimization algorithms
Travel to pilot and commercial sites to drive commissioning, startup, and ramp-up alongside operations & plant design teams
What You’ll Bring
B.S., M.S., or PhD in Chemical Engineering or related field
Minimum of 5 years of experience supporting R&D scale up, pilot plant operation, and/or commercial production in minerals processing, chemicals, specialty materials, oil & gas, or similar industry
Strong understanding of reaction engineering, solid-liquid separation, leaching, ion exchange, solvent extraction, and/or similar unit operations
Hands-on experience designing, commissioning, and operating pilot or commercial-scale process equipment
Ability to design experiments, problem-solve, and analyze complex datasets
Strong commitment to Health & Safety and experience with risk management, management of change, and hazard assessment
Excellent technical writing, communication, and teamwork skills
Comfort working in fast-paced, cross-functional environments
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!
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