Process industries are the foundation of the European economy, transforming raw materials into building blocks for strategic products and applications in today's society. Such industries range from steel, cement, or minerals to chemicals such as lubricants for wind turbines and polymers that prevent waste in logistic supply chains. The downside of this foundation industry is its high environmental impact regarding emissions, and intensive use of energy and resources. One of the key strategies to address such challenges is industrial symbiosis: various industries establish collective efforts to find value while transitioning to a more circular economy. This paper presents an exploratory analysis of databases on IS case studies. We used the European standard classification for economic activities (NACE) to draw industrial sector profiles for the most relevant energy-intensive industries: chemicals, steel, and cement, coupled with urban synergies. The majority of the synergies includes the chemicals sector with most commonly shared streams being energy, water, and carbon dioxide. IS cases are ranked in terms of frequency, then classified in topical groups and finally, the sustainability impact of the different categories is discussed. The outcome is a methodology to frame and assess industrial symbiosis case collections useful for future exploring and exploiting circularity projects in public and private organisations.