Process Modeling Engineer

Department: Plant & Process Engineering

Location: San Francisco HQ, Houston, TX

Compensation: $100K – $160K • Offers Equity

Employment Type: FullTime

Role Overview

Mariana Minerals is seeking a highly motivated 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.

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

• 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.)