Process Engineer

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. Key responsibilities Process ownership – SX and EW Act as the engineering owner of the SX and EW circuits, including mixer-settlers, organic and electrolyte handling, tank house, cell house and associated utilities. Monitor daily plant performance (PLS grade and flow, extraction and stripping efficiency, phase continuity, entrainment, current efficiency, cathode quality) and act on deviations. Define and maintain operating envelopes, control set points and alarm limits together with operations and control engineers. Lead technical troubleshooting of process upsets such as crud formation, organic degradation, impurity build-up (Fe, Mn, Cl, NO₃), short circuits and poor cathode morphology. Manage reagent strategy for extractant, diluent, smoothing agents and cobalt sulfate, including consumption tracking and supplier technical liaison. Produce daily, weekly and monthly process performance reports and metallurgical balances. Process improvement Identify, evaluate and lead improvement projects that increase recovery, throughput, current efficiency and cathode grade, or reduce energy, reagent and operating costs. Use data analysis, mass and energy balances, and process modeling to quantify opportunities and build business cases. Plan and run plant trials and test work with the laboratory, vendors and external partners, then implement and verify results. Drive root-cause analysis on recurring losses and production incidents, and track corrective actions to closure. Support control-system optimization and the use of instrumentation and online analyzers. Expansion and capital projects Provide process input to studies for capacity expansion, debottlenecking and new circuits, from concept through feasibility and detailed design. Develop and review process design criteria, PFDs, P&IDs, mass balances, equipment sizing and datasheets. Represent operations in design reviews, HAZOP and constructability workshops so new assets are operable and maintainable. Support pre-commissioning, commissioning and ramp-up of new or modified equipment. Contribute to cost estimates, schedules and risk assessments for capital projects. Safety, standards and people Apply process safety and management-of-change (MOC) practice to every process modification, with particular focus on fire risk in SX and acid mist in EW. Write and update SOPs, process descriptions and training material for operators. Coach operators, metallurgists and junior engineers, and share knowledge across teams. Support environmental compliance for effluents, emissions and organic losses. Required qualifications This role suits a hands-on hydrometallurgical/mechanical/chemical engineer who enjoys spending time in the plant, turning data into decisions, and seeing improvements through from idea to commissioning. 2+ years of process engineering experience in commissioning of chemical factories, mechanical equipment knowledge or project/design upgrades. Proven track record delivering process improvement projects with measurable results. 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!