PP plastic lid for the sedimentation tank of an acid treatment plant


The conditions at the Aurubis copper mill in Hamburg / Germany are extremely demanding – the metalworking industry works with extremely aggressive chemicals, after all. The old lead-lined lid of the sedimentation tank, which is also lined with lead and acid-resistant bricks, naturally could not withstand the harsh environment forever, and it has now, after roughly 50 years in service, been replaced by a PP solution.

The new PP-H lid has an overall diameter of 5.39 metres and was constructed in three sections due to its enormous transport dimensions. The middle of the three sections weighs 700 kg, the two outer ones 800 kg each. Final assembly of the lid took place in mid-September at the customer‘s site.

In order to achieve greater rigidity, steel beams were used, enclosed in PP to prevent corrosion. The PP pipes used for this were heated together with the installed HEA steel wide-flange beams. Then the pipe was drawn onto the steel beam via vacuum.

The required pipes were also fabricated in Höhr-Grenzhausen using the butt fusion welding technique and installed later at the construction site.

Steuler process technicians invested many production hours in manufacturing the lid, welding 195 seam metres with the extruder and 90 seam metres via hot gas string bead welding.

For the PP lid, roughly 20 m² of custom manufactured PP / GFRP gratings were milled, cut and adapted using the CNC machine in addition. When placed in the mounting on the lid, the gratings form a work platform that allows maintenance to be carried out and workers to cross at an installation height of around seven to eight metres. The work platform is complemented by a walkway to other parts of the plant, several stepladders and a guard rail made from GFRP – everything planned, externally sourced, manufactured and finally installed.

The exciting order was delivered within two months and installed by Karl Ferdinand and his team on time.

PP lid on the sedimentation tank of an acid treatment plant with grating and safety railing

Built-in lid with grating, safety railing and transition stage in the background

Assembled individual parts of a PP lid for a sedimentation tank in an acid treatment plant

Assembled individual parts in production

PP lid detail before joining in the acid treatment plant

PP lid detail before joining in the acid treatment plant