Sr. Process Engineer

Mariana Minerals; San Francisco, Northern (CA, KY); Hybrid; USD 150,000 - 210,000; Full time

Job summary

Mariana Minerals is seeking aSr. Process Engineer to lead the design, deployment, and operation of pioneering refining processes for critical minerals at our San Francisco pilot plant. You will also support software-driven plant optimization and bridge R&D with Operations.

The role is hands-on and cross-functional, requiring strong process know-how and collaboration across teams to scale from lab to production while maintaining safety and cost-efficiency.

Qualifications

• BS, MS, or PhD in Chemical Engineering or related field.
• Minimum 5 years in R&D scale-up, pilot plant operation, or production in minerals processing or related industries.
• Strong understanding of reactor engineering and unit operations.
• Hands-on experience designing, commissioning, and operating pilot or scale equipment.
• Ability to design experiments and analyze complex data sets.
• Commitment to health & safety and risk management.
• Excellent technical writing, communication, and teamwork.
• Comfort in fast-paced, cross-functional environments.

Responsibilities

• Operate, maintain, troubleshoot, and improve pilot-scale processing equipment with technicians.
• Design experiments to evaluate performance, recovery, throughput, and product quality.
• Create and maintain PFDs, HMBs, P&IDs, operating procedures, and process control narratives.
• Lead equipment design scopes from concept through procurement, fabrication, installation, and handover.
• Collaborate with R&D, design engineers, and project teams to scale designs from lab to pilot to production.
• Work with software and ML teams to develop reactor and plant optimization algorithms.
• Travel to pilot and commercial sites to support commissioning, startup, and ramp-up.

Skills

Reaction engineering

Solid-liquid separation

Leaching

Ion exchange

Solvent extraction

Pilot-scale operation

Experiment design

Data analysis

Technical writing

Teamwork & communication

Education

BS, MS, or PhD in Chemical Engineering or related field

Job description

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!