Refinery Process Operator Jobs in Houston, TX (NOW HIRING)

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.

Mariana Minerals is seeking a highly motivated Staff Process Modeling Engineer to support the development of next-generation refining processes for critical minerals — key to enabling the world’s energy transition.

In this role, you will be responsible for developing, validating, and optimizing heat and material balance models using tools such as ASPEN Plus/HYSYS, SysCAD, OLI Studio, or METSIM. You will work closely with R&D, pilot operations, and project execution teams to translate lab and pilot data into robust, scalable process models that drive the design of first-of-a-kind mineral refining facilities.

As a Staff Process Modeling Engineer, you will serve as a technical leader for process simulation and modeling, providing subject matter expertise across multiple projects, developing modeling standards and best practices, and mentoring junior engineers while partnering with cross-functional teams to support process development from concept through commercial deployment.

• Develop steady-state and dynamic process models to establish heat and material balances for integrated mineral refinery systems using ASPEN, SysCAD, OLI, or METSIM.
• Automate equipment and process sizing (reactors, heat exchangers, filters, crystallizers, evaporators, and separators) based on model outputs, linking models to datasheets and other engineering tools
• Develop and maintain process simulation databases, ensuring consistency and traceability between modeling assumptions, test data, and engineering deliverables.
• Calibrate and reconcile models using pilot or plant operating data to ensure model fidelity and predictive accuracy.
• Conduct process optimization studies — evaluating energy/heat recovery, recycle strategies, and material efficiency improvements.
• Develop dynamic process models to validate PLC and DCS programming and evaluate/optimize buffer sizing throughout the design.
• Link process models to CAPEX and OPEX estimation tools, automating technoeconomic model development
• Document modeling methodologies and results, providing clear technical communication for design reviews, techno-economic assessments, and regulatory submissions.

• Bachelor's degree or higher in Chemical Engineering, Mechanical Engineering, Process Engineering, Metallurgical Engineering, or a closely related engineering discipline
• 8+ years of experience developing and applying process simulation models for chemical processing, hydrometallurgy, mining, refining, or related industrial process systems.
• Proficiency in one or more of the following process simulation tools:
• ASPEN Plus / HYSYS
• SysCAD
• OLI Studio / OLI Flowsheet
• METSIM

• Deep understanding of mass transfer, heat transfer, thermodynamics, fluid flow, and reaction engineering.
• Experience developing material and energy balances for multi-step, integrated process systems.
• Strong grasp of chemical equilibria and phase behavior in aqueous and non-aqueous systems.
• Familiarity with data reconciliation, parameter fitting, and model validation using experimental or operational data.
• Competency with Python or MATLAB for model automation, data processing, and custom calculations is a strong plus.
• Experience integrating process modeling outputs into EPC deliverables (PFDs, P&IDs, equipment datasheets, control narratives, etc.)

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!