Capacity of 120,000 tonnes per year

The plant is designed for a throughput of 59 tonnes per hour. Based on planned single-shift operation for eight hours per day and 255 operating days per year, it will process more than 120,000 tonnes of incinerator bottom ash annually.

The facility is intended to recover metals from bottom ash, including both ferrous and non-ferrous fractions. Non-ferrous metals are separated into 0–4 mm, 4–30 mm and 30–150 mm size classes. Ferrous metals are divided into fractions below and above 150 mm.

Process technology for abrasive material

Eggersmann acted as general contractor and was responsible for planning, installation and commissioning. The scope also included the production of 527 metres of conveyor technology.

A key process requirement is the treatment of sintered bottom ash. This mineralised material is crushed in an impact mill to release enclosed metals. The downstream process uses magnets, screening equipment and further separation technology to recover additional metal fractions.

Fine fraction also processed

At Knockharley, the bottom ash is stored and dried for around two to three weeks before processing. At this stage, the material has a residual moisture content of 16 to 19 per cent.

The plant also processes the fine fraction from 0 to 4 mm. This reflects a wider market trend towards more complete metal recovery from IBA, including smaller particle sizes that require adapted process design.

Turnkey plant replaces modular system

Knockharley Landfill has processed incinerator bottom ash on site since 2014 before subsequent landfilling. The company previously used a mobile-modular system combining mobile machines with stationary process technology.

The new turnkey recycling plant was installed to handle higher throughputs and abrasive material with a higher level of automation. According to Eggersmann, the system is designed to reduce maintenance requirements and downtime compared with the previous configuration.