Low-carbon construction materials for the builders of tomorrow.

In the next 40 years, we’re set to double the amount of infrastructure in the world — equivalent to a new Manhattan every month. A lot of this is crucial to the energy transition, but all of it will require steel and cement. These two materials represent 15% of global emissions. 

We’re committed to tackling the climate emergency by decarbonising heavy industries and creating low-carbon construction materials. Our patent-pending process captures CO2 and upcycles by-products from steel manufacturing into a cement alternative. 

We’re a small, but mighty team (and growing), backed by world-class investors in climate, hardware and industrial decarbonisation.

About Us

We’re building an incredible team of people with a range of skills, superpowers and experiences. Great ideas, advice and feedback can come from everywhere. We’re not afraid to share our thoughts or seek input from others.

Use the power of people

We empower every individual to take ownership of their work and drive meaningful progress. From idea generation to execution, we encourage autonomy, initiative, and accountability.

Take ownership, drive progress

We’ve got a big challenge ahead of us, but that doesn’t mean it can’t be fun too. We believe that when work feels like fun, it sparks creativity, strengthens collaboration, and builds resilience.

Find the fun

&nbsp;We’re building equipment for heavy industry, which involves potential hazards. Safety is front of mind when running experiments, developing technology and working with clients.

Safety as a priority

&nbsp;What we’re doing will always have uncertainties, whether it’s because of the nature of scientific experiments or the fact that we’re an early-stage start-up. Sometimes the answer will be “I don’t know”, but this is best coupled with “we can find out by…”.

Embrace uncertainty, seek clarity

Our Values

Freddie Scott

Eliot Brooks

William Knapp

Meet Our Team

Gallery

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Engineering Technician (contract)
Responsibilities:&nbsp;
Join our dynamic team and play a key operational role in delivering prototype hardware, maintaining our high temperature equipment, and assisting in hardware trials to test our prototypes at scale. Your contributions will be instrumental in accelerating our research as we start scaling our technology out of the lab.
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Mechanical and basic hydraulic assembly of prototype equipment.
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Assisting in prototype trials at our research partner in the north of England with potential travel to the US Q2 2025
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Light machining and modifications of metal and plastic components (cutting, drilling, grinding, welding, pipe joining)
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Maintaining our high-temperature furnaces (one induction furnace and two box furnaces): monitoring general health, packing and unpacking crucibles, making repairs to insulation/refractories when necessary
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Moulding of castable refractory components.
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Creating components using additive manufacturing techniques
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Understanding CAD models and modelling basic components
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Assist in the instrumentation and wiring of test beds
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Troubleshooting of machinery faults during build and test.
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This role will initially be contracted for 6 months full time. However, there is an opportunity for it to be extended or converted into a permanent position towards the end of the initial term.
About you
We want to build Cocoon with a ‘hands-on’ team of people who can wear multiple hats. The perfect candidate will be comfortable working in an engineering workshop environment: able to carry out tasks independently and seek advice as and when required. If you possess the following qualifications/qualities we would love to hear from you:&nbsp;
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5+ years experience as an engineering technician in a related industry
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Basic proficiency in CAD (Solidworks)
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Experience in light machining of metal and plastic components (cutting, drilling, grinding)
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Full UK driving licence
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Bonuses:&nbsp;
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Welding qualifications
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Electrical installation/wiring qualifications
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Experience working in foundries/with high temperature furnaces
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Basic knowledge of industrial controls, instrumentation&nbsp; and PLCs
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Join us on our exciting mission as we work together to shape the future of our company and make a meaningful impact in tackling the climate crisis.
How We Work:
 
As a company building hardware we require hands-on members of the team to be in HQ (office/engineering/lab space) full time.
 
Compensation:
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Base salary £35,000-£45,000 pro rata per annum subject to experience
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Cocoon is an equal opportunities employer. We embrace diversity as a core value and commit to providing equal opportunities for all employees, job applicants, clients, and customers, irrespective of race, ethnicity, gender, sexual orientation, religion, age, disability, or any other protected characteristic. We regularly review our policies, provide training, and encourage open dialogue to ensure a supportive and inclusive workplace for all.
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Engineering Technician

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Principal Process Engineer
About <a href="https://www.cocooncarbon.com/">Cocoon</a>:
Cocoon is creating a low-carbon cement substitute for the builders of tomorrow. Our patent-pending process upcycles by-products from steel manufacture into a cement alternative (also known as a supplementary cementitious material or SCM). We are on a mission to make steel greener and cement cleaner.
In the next 40 years, we will witness the construction of double the amount of infrastructure as there is in the world today, equivalent to a new Manhattan every month. Much of this infrastructure is crucial to the energy transition, catering to migrating populations, and achieving sustainable development goals. Steel and cement are integral to this construction, yet they contribute 15% of global emissions. Cocoon is committed to addressing the climate emergency by decarbonizing these crucial industries, paving the way for a better future for all.
Our core technology involves manipulating molten steel slag to produce desired cementitious properties. We are seeking an experienced principal process engineer to lead our scaleup and deployment activities as we move towards our first TRL6 deployment on an active steel plant in Q2 2025 and subsequent journey to TRL 8 and beyond.
We are a small but formidable team, backed by world-class and global investors in climate, hardware and industrial decarbonisation.
Responsibilities:
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Responsible for the technical definition, development and delivery of a commercial scale slag activation process for creating Cocoon’s products
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Lead the deployment of a TRL6 demonstration on a US steel plant in Q2 25, managing a successful setup, operation and teardown of the system and delivering multiple tonnes of material suitable for concrete use cases
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Lead the design of a pilot 12ktpa slag processing system for deployment commencing 2026
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Identify, appoint and manage relationships with key stakeholders including EPC partners and steel plants to support delivery of both TRL6 demonstrator and pilot
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Review existing technology readiness and input into process R&amp;D strategy
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About You:
We are seeking individuals to join Cocoon who are 'hands-on' engineers capable of wearing multiple hats, bridging the gap between an in-depth understanding of the physics of our technology and the industrial engineering required to deliver it at scale. The ideal candidate will be an experienced process engineer with a background in scaling materials processing technologies to TRL8, ideally within pyrometallurgy, mineral processing or relevant adjacent industry. Unafraid of challenges, you will be empowered by the team to lead a critical workstream in the scale-up of our technology as we look to demonstrate commercial and technical viability of our process at industrial scale. If you possess the following qualifications/qualities, we would love to hear from you:
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10+ yrs Industry experience in chemical/process engineering; including process design, hot + cold commissioning, project/construction management
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Experience working in pyrometallurgical processes (steel, copper, aluminium) or mineral processing
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Experience scaling and integrating novel processes/technologies into already live processes
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Willingness to work in a fast-paced and dynamic startup environment
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Bonuses:
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Experience working in the US
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Experience working in/with startups
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Knowledge of cement and concrete production
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Knowledge of refractory engineering
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Experience managing material transport and logistics
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Join us on our exciting journey as we collaborate to shape the future of our company and make a meaningful impact in addressing the climate crisis.
How We Work:
 
As a company building hardware we require the team to be in our London HQ the vast majority of time. For some roles, remote working may make sense 1-2 days a week and this is something that can be discussed during the application process. We will always try to accommodate alternative working hours to suit individuals - talk to us!
Compensation:
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Highly competitive salary, plus stock options
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Relocation financial support may be discussed at the offer stage if relocation is required
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Cocoon is an equal opportunities employer. We embrace diversity as a core value and commit to providing equal opportunities for all employees, job applicants, clients, and customers, irrespective of race, ethnicity, gender, sexual orientation, religion, age, disability, or any other protected characteristic. We regularly review our policies, provide training, and encourage open dialogue to ensure a supportive and inclusive workplace for all.
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Job Openings

Engineering Technician

Principal Process Engineer