About Cocoon At Cocoon, we’re building low-carbon construction materials for the builders of tomorrow. Steel and cement together account for nearly 15% of global CO₂ emissions — and we’re tackling that challenge by developing and scaling a low-carbon cement substitute. We’re an early-stage, fast-growing company moving from pilot trials into demonstration and capital project delivery. This role sits at the heart of that transition, shaping how our process is designed, de-risked, and implemented at scale, and playing a critical role in turning our technology into an operational reality. The Role We’re looking for a Senior Process Engineer to lead process design, scale-up, and project delivery across Cocoon’s next-generation slag activation system. You’ll work closely with process and mechanical engineers, material scientists, researchers, and technicians to optimise our core process and integrate it with existing steelmaking infrastructure. This role spans front-end engineering, pilot and lab development, capital project delivery, and commissioning. You’ll take ownership of process design packages, champion process safety, and represent process engineering internally and externally as we scale from pilot to demonstration, and to commercial scale. Responsibilities Process Design and Scale-Up Own and deliver process design packages (PFDs, mass and energy balances, equipment specifications) across front-end engineering, detailed design, and execution phases. Produce and review process models and calculations, ensuring sound engineering fundamentals underpin all designs. Plan, execute, and analyse lab and pilot-scale development trials to de-risk process scale-up. Lead process engineering input across the project lifecycle, from design through installation and commissioning. Ensure alignment of process design with cost, schedule, operability, and performance targets. Process Safety, Risk & External Engagement Lead and support process safety reviews (e.g. HAZID, HAZOP) and proactively manage process risks. Ensure designs meet internal, regulatory, environmental, and safety requirements. Represent process engineering in discussions with equipment vendors, consultants, trial partners, and contractors. Clearly define and manage technical scope and requirements with third parties. Champion sustainable design, energy efficiency, and continuous improvement in process and equipment selection. Leadership and Culture Provide technical leadership and mentorship to engineers and technicians. Support the development of fellow engineers and contribute to a collaborative, inclusive, knowledge-sharing culture. Contribute to continuous improvement in design practices, safety performance, and project outcomes. Support installation, commissioning, and testing activities in the UK and internationally. You’ll Succeed In This Role If You… Hold a Master’s degree in Chemical or Process Engineering and have 5 years of industry experience in process development and scale-up. Bring a strong technical foundation in process design, modelling, engineering calculations, and process safety. Are comfortable owning deliverables in lean project teams without heavy functional support. Thrive in fast-paced, evolving environments and bring a practical, hands-on problem-solving mindset. Communicate clearly and confidently across technical and non-technical audiences, including vendors and partners. Bonus qualities Hands-on experience across the capital project lifecycle, including design, construction, commissioning, and operations. Experience scaling technologies from lab or pilot to demonstration or full-scale implementation (TRL 4/5 to TRL 8/9). Familiarity with stage-gate development processes and capital project lifecycles. Knowledge of minerals processing, solids handling equipment, or industrial water systems. Background in steelmaking, pyrometallurgy, or high-temperature fluid/refractory systems, including FMEA or structured risk methodologies. What We Offer A senior role at the heart of Cocoon’s scale-up and deployment journey. Direct ownership of process design and safety for first-of-a-kind technology. Close collaboration with a multidisciplinary, mission-driven team. Competitive salary, stock options, and strong growth opportunities as we scale. Apply Now If you’re excited about scaling new industrial processes and helping decarbonise the steel and cement industries, we’d love to hear from you.