Focus on ink: Recycling ceramic inks with the Life Replay project

Researcher Jorge Gonzalex discusses the Life Replay project, which aims to recycle ceramic inkjet ink wastes back into the industrial process, achieving sustainability goals and minimising the cost of waste disposal. This project will also demonstrate the feasibility of using the inkjet ink wastes as new raw materials for the ceramic industry, transforming them in an environmentally friendly and cost-effective alternative source of pigment and solvent

In 2019, 2,399t/yr of waste were generated from the ceramic inkjet inks at European level without being re-used nor recycled. Their treatment and disposal induce costs of about €14.4M/year at European level. The two leading countries at EU level in terms of production and waste generation are Spain (641t/yr) and Italy (503t/yr), representing a total cost above €6M/year.

The ceramic inkjet inks are generally made up of complex mixtures consisting, mainly, of a heavy metal-based solids component comprising (singly or jointly) inorganic pigments/refractory materials/ceramic frits (25–55(wt)%), organic solvents (45–65(wt)%), and different additives (1–10(wt)%). The presence of heavy metals (such as Ni, Pr, Cr, Co, Fe, etc.) in the solid component and the organic nature of the solvents (paraffinic and naphthenic oils, ester, glycol-ether, etc.) used in the formulation entails important environmental problems, increasing health and environmental risks (i.e. soil and water contamination).

The hazardous uncertainty of the waste generated and the economic cost of waste treatment and disposal obligate the ceramic industry to take appropriate actions to prevent and/or minimise waste generation, to increase resource efficiency and to mitigate negative impacts.

Indeed, the European Commission implemented the Directives 2008/98/EC, 2014/957/EU, and 1357/2014 on wastes, as well as COM(2015) 614 final on circular economy. The different communitarian countries adopted, therefore, these strategies by means of specific regulations. In Spain, a draft law (APL/2020) was established to transpose the EU directives; and in Italy and Bulgaria, the Law 221/2015 and LEX-FAOC164398 (2016) respectively were accordingly approved and implemented.

Despite this fact, the difficulties related to the separation process, the sub-micron particle sizes required, and the non-aqueous nature of the solvents present in the ceramic inkjet ink wastes are the main constrains and limitations for the countries to accomplish the regulations.

Thanks to LIFE REPLAY, ceramic inkjet ink wastes will be reintroduced in the industrial process by using a specific separation procedure which fulfils the industrial requirements for quality management. The promotion of sustainability and, thus, the minimisation of the costs of waste disposal are the main goals of this project. This project will also demonstrate the feasibility of using the inkjet ink wastes as new raw materials for the ceramic industry, transforming them in an environmentally friendly and cost-effective alternative source of pigment and solvent.

READ MORE:

Focus on ink: Artist makes ink from a clone of Sir Isaac Newton’s apple tree

Project objectives

The main goal of the project was to demonstrate the technical feasibility of employing ceramic inkjet ink waste as a source of new raw materials (by-products) for the ceramic industry, prior separation of those, resulting in a solid component based on heavy-metal inorganic pigments and in a liquid component consisting of organic solvents.

The LIFE REPLAY project had the following specific objectives:

• To demonstrate in a real environment the valorisation of inkjet ink waste in the ceramic SMEs.
• To implement a value chain pilot based on circular economy pillars through industrial symbiosis among SMEs.
• To demonstrate the competitive edge of the business model and measure the economic benefits for all SMEs, especially those related to the ceramic, decorative glass and cathodic/anodic application industries.
• To develop a prototype for the separation procedure of the inkjet ink waste in a simple and low-cost process.
• To deploy the new business model for the transformation of the inkjet ink waste as a new resource for the ceramic industry.
• To assess the environmental impact on the production of brand-new ceramic products reusing and recycling inkjet ink waste as well as on the ceramic tile and inkjet ink production.
• To replicate the solution of the innovative valorisation scheme in other ceramic SMEs (not only the consortium).
• To transfer the solution into other SMEs devoted to other sectors/application areas.
• To foster social awareness related to the environmental troubles caused by inkjet ink wastes, comparing the current situation with the new situation after this project.

Results

Physical-chemical separation process

The project started with data collection to evaluate the environmental impact associated to the ceramic inkjet ink waste. An examination of industry best practices was carried out.

Following this initial stage, a waste separation prototype was constructed. Subsequent steps included initial testing for the treatment of approximately 11 tons of ceramic inkjet ink waste.

The prototype was submitted to a validation process to further optimise its performance, ensuring strict adherence to prevailing industrial quality standards.

Finally, the prototype has been successfully implemented, introducing an efficient and sustainable initial approach to managing ceramic inkjet ink waste in the industry.

First ink obtained from the solid component

The first inkjet ink lab composition was developed valorising the solid component obtained from the separation process, replacing 10wt% of the current inorganic pigment (Figure 1).

Figure 1. First inkjet ink developed valorising the by-products obtained through LIFE REPLAY implementation.

New screen-printing ink from the effluent component

Additionally, a new screen-printing ink was developed at a laboratory scale by replacing 26wt% of the organic solvent with the effluent component obtained (Figure 2).

Figure 2. First screen-printing ink composition developed valorising the by-products obtained through LIFE REPLAY implementation.

READ MORE:

View from the US: Focus on sustainability has powder coatings poised for growth in the US

Expected results

The main measurable outputs achieved during the project execution are:

• Separating capacity of 0.5 t/h. Performance 90-98%

• 100t ceramic inkjet ink wastes provided to CTR will be treated to obtain 58.8t of organic effluent and 39.2 tons of solid component.

• 10,000sq.m “eco” ceramic tiles will be produced by KEROS, where 30-40% of the current solvent used in traditional decoration will be replaced by the new organic effluent (0.88t). 100% of the current pigment used in coloured-body tiles (3,300sq.m), glaze (3,300sq.m) and traditional decoration (3,300sq.m) will be replaced by the treated solid (0.79, 0.42 and 3.3t respectively)

• 80t “eco” ceramic inkjet inks (40% solid content) will be produced by AKCOAT, where 15-25% of the current pigment and 100% of solvent will be replaced by the treated solid and effluent (4.8-8t and 48t, respectively)

• 30t “eco” pigment will be prepared by AKCOAT. 25-40% of the current pigment used will be replaced by the treated solid (7.5-12t)

• 9t of “eco” cleaner will be totally substituted (100%) by the liquid effluent obtained thanks to LIFE REPLAY

• 100% reduction in the generation of industrial wastewaters during the treatment of inkjet wastes at CTR (15-20kg fresh water/kg wastes: 1,500-2,000t)
• 46% reduction in energy consumption within the inkjet ink production (0.29kWh/kg of ink leading to a reduction of 23,200 kWh)

• 51% reduced energy consumption in the pigment production (0.23 kWh/kg of inorganic pigment produced leading to a reduction of 6,900kWh)

Acknowledgements

This project is financed by the LIFE Programme 2014-2020 of the European Union for the Environment and Climate Action under the project number LIFE20/ENV/ES/000115. Also, the project is co-financed by the Generalitat Valenciana, through IVACE.

For more information about the Life Replay project, visit: https://lifereplay.eu