Problem solving

Automated recycling of fluorescent light tubes

Reliable, safe gas extraction

Recycling used fluorescent light tubes makes good commercial sense since 97% of the material involved can be re-used. The fluorescent material itself can be fully recycled and re-used in the manufacture of new tubes. Provided, of course, that you have a high-performance, customised unit for the extracting gas and dusts produced when breaking up the old lamps. LAREC^® GmbH in Brand-Erbisdorf, south of Freiberg in Germany, is a specialist in recycling fluorescent light bulbs. At its new, automated plant it uses a RUWAC extraction unit, specially developed for this application.

The Kapp-Trenn^® cutter developed by LAREC® GmbH cuts the lamp base from the glass body and a blast of compressed air blows the dust-laden gas out through the other end of the tube into a receiving hopper. From here the waste is vacuumed through a filter at 230 mbar.

The dusts then pass through a separator fitted with an AGLA-TF, PTFE-coated, class C filter. Dust analyses have shown that this filter is truly efficient. Filter dedusting is automatic. A differential pressure sensor measures the filter load and triggers the deduster device automatically when required. The deduster blasts the clean gas side with compressed air so that the dirt detaches and drops down into the collector bin. The differential pressure is monitored constantly throughout dedusting. When the setpoint value is reached and efficient cycle operation can be guaranteed once again, the dedusting cycle is stopped. The unit ensures a high level of safety. Safe, trouble-free, automatic operation is guaranteed. Another particularly advantageous feature of the unit is that the cleaning cycle takes place while the unit is on-line, i.e. during the operating cycle.

This extractor system consists of three, parallel separator lines which prepare the three fluorescent gases for LAREC^® light tubes. Downstream from the three separators there is a central active carbon filter which removes any gaseous dirt. The dust collected in the separators is fed into a silo and then collected in 200-litre drums. Proximity switches monitor drum contents and indicate when the drums are full. If there is no drum under an active silo, this is detected by the system controller which triggers an alarm signal. Sensors enable correct positioning of the drums.

The vacuum unit PLC processes sensor signals, triggers automatic dedusting and communicates with the higher-level system controller when the separator for the current fluorescent material has to be activated.

Once again this extraction unit has been customised and purpose-built specifically for this application. The side-channel blower, the separators and the other core components of this system are standard units from RUWAC's modular range - another feature which makes this system particularly cost-effective.