Investment in recycling plant pays off for skip hirer

McKinstry Skip Hire, a family owned business founded in 1969, has responded to changes in the skip hire business over the past few years - not least of which was the effect of the introduction of the Landfill Tax - by establishing facilities in waste treatment to recycle and reclaim the large annual tonnage that the company's fleet of skips and roll-on-off containers was handling. An initial investment in a Powerscreen screening plant some nine years ago saw the establishment of a close and business relationship between McKinstry Skip Hire, Powerscreen International and its dealer McGurk Screening Systems.

The latest manifestation of this working partnership comes with McKinstry investing in new Powerscreen equipment and associated conveying systems from McGurk. McKinstry Skip Hire is taking a new and enhanced prototype version of the Powerscreen Trommel 725 for extensive testing and appraisal at its facility. Operating within a 30-40 mile radius of its Nutts Corner, Crumlin, premises, McKinstry Skip Hire has a fleet of over 500 skips, 50 roll-on-off bins supported by eight skip trucks and four roll-on-off lorries. Additionally, the company has diversified into dumper and excavator hire and contracts out a special 38 tonner Renault scrap metals transporter and operates another 38 tonner Renault tug-and-low-loader combination, which is busy handling the transportation of excavators and other heavy construction plant throughout Northern Ireland.

In the order of 100,000 tonnes of building waste goes through the McKinstry waste management system during the year and, using a combination of shredders, a trommel screen, a "blower" density separator, overband magnet and a modern picking station, around 1,200 tonnes of saleable material (including 500 tonnes of fines) is extracted on a weekly basis. The reclamation systems in place effectively reduce the volume of waste to landfill by some 60%, which has the dual benefits of diverting material from landfill and producing reusable materials for sale to a loyal customer base in the region.

Pre-sorting proces

On arrival at McKinstry's three-acre site, all the building waste is pre-sorted to remove the larger pieces of scrap metal, timber, boulders etc. Wheeled loaders stockpile this sorted material ready for pre-shredding which is carried out almost non-stop by a Powerscreen Powershredder 1800 which is fed by a wheeled Case excavator with long-reach industrial stick and five-tyne grab. This shredder prepares the raw materials for the next stage which is screening and separating by a Powerscreen Trommel 615LL, fed by the loading shovels. This trommel is housed inside a purpose-built shed with the tail fines conveyor stockpiling through an aperture in the wall, while the oversize material is conveyed via a Powerscreen TR Blower, to remove lightweight materials such as paper, PVC and polystyrene, and then conveyed directly to the covered picking station. Here, four sorting stages select and stockpile rubble, timber, cardboard and plastics along the 12 metres long conveyor belt and, at the end of the process, ferrous metals are removed by an overband magnet conveyor. The bins constructed below the overhead picking station are all designed to accept "40 yarders" so that materials drop straight into these receptacles, obviating the need for additional rehandling.

The reclaimed materials are converted into a multitude of saleable products for McKinstry. The fines are predominantly used at both public and private sector landfill sites for "blinding" between strata of waste material within the cells; clean timber, which is stored under cover for temperature and humidity control, is shredded for onward sale to chipboard and MDF manufacturers, while the remaining wood products are used for industrial heating boiler fuels and, in a recent innovative development by McKinstry, shredded to smaller sizes and used as cattle bedding in outdoor corrals. Here 3-4 metres depths are spread, serving as an ideal dry, warm and easily replaceable "green" outdoor surfacing for both beef and dairy herds during the winter months. Rubble is transported all over the region where it is used on building projects, for temporary haul roads and as general hardcore substrate.

The Powershredder 1800 produces a consistent and uniform material sizing using a range of toolheads to match, is quiet in operation and has a low dust emission level. Automatic and fixed reverse shafts that are easy to replace makes are designed for easy maintenance and efficient processing of materials. Additionally, full remote control is available for safe operating distance. A generously proportioned low loading and tipping hopper allows the shredder to be fed by conveyor, excavator or loading shovel. The hydraulically raised discharge conveyor, with chevron belting, has a discharge height of some three metres for good stockpiling capacity.

The Trommel 615LL has a 19m2 rotating screen area with variable speed control, a folding tail conveyor for fines and an optimum output of 150-200 tonnes per hour, depending on application and mesh size. The twin axle unit has hydraulic jacklegs which, with the hydraulically folding conveyor, greatly improves mobility and significantly reduces set-up time, should the unit need to be moved or transported to another site. The low-loading hopper means that raw material discharge is made easy for most sizes of loading shovel or excavator.

The Trommel 615LL is compatible with all Powerscreen equipment and, therefore, can form an integral component in a screening, washing and stockpiling installation. Power is usually provided by a diesel engine, although electric motors are available as an option - and all trommel hydraulics are protected by an automatic shut-down system. A conveniently located control panel provides finger-tip management of all machine functions. In the McKinstry set-up, the Trommel 615LL has an hydraulic take-off to provide all the power for the conveyor in the picking station and its three metres long inclined feed conveyor - both of which have infinitely variable speeds.

Picking station

The TR Blower removes light materials, which are caught in a net and then "skipped". Products from this process include recyclable paper, which can be baled and sold on for pulping, and other light waste for incineration or landfill. The heavier materials then pass up a feed conveyor to the elevated picking station conveyor for hand removal and chute discharge for disposal or reclamation. Powerscreen's picking stations can be customised to virtually any size to suit customers' applications. At McKinstry Skip Hire, pickers can be positioned on both sides of the conveyor and, for enhanced working conditions for operatives, the fully enclosed cabin work station has heating and lighting. Four discharge chutes are positioned on both sides of the 12m long conveyor for convenient "binning" of materials in their respective stockpiles.


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