Based in Auckland, New Zealand for 1.5 years, this role offers international experience before transitioning back to the UK. We are seeking a Senior Process Engineer to drive the design and delivery of a demonstration-scale black mass refining plant, supporting the recovery of critical metals from lithium-ion batteries. You'll collaborate with contractors, vendors, and internal teams, refine process designs, and assist with commissioning and operation. The Senior Process Engineer will: Lead process engineering for LIB processing plants, including extraction, precipitation, concentration, and crystallisation. Develop and maintain engineering deliverables such as mass/energy balances, PFDs, P&IDs, equipment specifications, and operating procedures. Provide technical guidance and governance, mentoring junior engineers and reviewing engineering work. Participate in structured design reviews, HAZOPs, risk assessments, and ensure designs are safe, operable, and maintainable. Support commissioning, troubleshooting, optimisation, and operationalisation of the demonstration facility. Collaborate with contractors, vendors, and internal teams to integrate equipment, resolve design queries, and ensure regulatory compliance. The Senior Process Engineer will have: BE (Hons) or BTech in Process Engineering; Chartered or Member status preferred. Minimum 6 years post-qualification experience (3 years if MSc). Experience in hydrometallurgy, mineral processing, or related sectors is highly desirable. Strong understanding of scale-up considerations for commercial facilities. Proven experience in technical governance, reviewing engineering deliverables, and mentoring engineers. Excellent communication, analytical, and problem-solving skills with a hands-on, practical approach. If you're a hands-on, innovative Senior Process Engineer, this is your chance to lead the development of cutting-edge sustainable technology. Apply today and be part of a team shaping the future of battery recycling and critical metal recovery