Staff Process Modeling Engineer

About the company

Mariana Minerals is a software-first, vertically integrated critical minerals company that engineers, builds and operates mines and refineries using its MarianaOS platform.

About this role

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. THE ROLE 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. WHAT YOU’LL DO - 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. WHAT YOU’LL BRING - 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.) 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.