Separating Steel from Demolition Rubble

J&R Magnetics' customer was struggling with continuous conveyor trips due to scrap pieces of steel being detected in the concrete rubble from a major demolition site in Sydney's CBD. A 'Hire' solution enabled proof of concept!

Magnetic Separation


The Problem

Urgent action was required, as the customer, a civil contractor, was losing productivity. The process objective was to crush concrete rubble such that it could be used for road base and fill. Steel pieces found their way into the rubble during demolition of the building structure, in all shapes and sizes. The crushing process would stop several times per hour requiring operator intervention to clear the steel from the belt.


The Solution - An Over-band Magnet

J&R Magnetics worked closely with the customer to develop a solution to remove the nuisance steel items before they reached the metal detector and importantly before they damaged the crushing section of the equipment. This solution involved the use of equipment from J&R's hire fleet, with some modification, to suit specifically the application. 


Proof of Concept

A large industrial electromagnet capable of being suspended over the conveyor belt was tested in J&R's workshop with the customer, to demonstrate how effectively it could collect large pieces of steel as they rolled past.

A cooling oil reservoir, or header tank, was fabricated and fitted to enable the magnet to be suspended at an appropriate angle over the conveyor belt. This ensured the magnet winding always remained immersed in the oil.

A diesel generator set was modified to include a magnet power supply & controller. This Controller included a transformer to step the voltage down to 120VAC, a rectifier to convert to DC, and switchgear & controls to enable the correct cycle of 'lift and drop' polarity.

The complete system was tested in the J&R workshop, delivered to site and commissioned.


The Result

To prove the system, the magnet was suspended over the conveyor belt with the use of an excavator. It worked, and the magnet continuously grabbed the steel pieces. The magnet was cleared regularly of steel, and the crushing process continued uninhibited. This test using the 'Equipment Hire' solution from J&R Magnetics has given the confidence to proceed with a permanent system.  


In Conclusion

J&R's local design, manufacturing and site capability regarding electromagnet applications ensured the best solution was developed and proven in a very short time frame. Utilising J&R's hire fleet provided the client with confidence, reducing risk, before proceeding to purchase a permanent asset. 


Contact us here  today if you would like assistance to remove nuisance steel items from your material handling process!