LJH Group Limited / News Articles / South Wales Recycling

LJH SORT OUT SOUTH WALES RECYCLING PROJECT!

The blower system LJH Group of Chantry, Somerset have just designed, manufactured and installed a new bespoke recycling facility for South Wales Mineral Recycling Centre Ltd, (trading as Pant Recycling). Commissioned March 2004 at Pant Quarry, Bridgend, South Wales the waste sorting system is housed in a purpose built 17,000 sq ft building. Designed to handle 72,000 tonnes of heavy duty commercial mixed waste per year it is capable of reducing waste to landfill by as much as 95%.

An important aspect of the operation involves all recycled aggregate and soils being reintegrated back into the production process of the Tarmac operated quarry which complies fully with the European Directive.

The South Wales Recycling waste sorting system was designed to specific criteria and comprises of a waste feed hopper, trommel screen, blower, picking belt and magnet. It is required to handle a wide range of material; mainly commercial and domestic skip waste at the rate of 100 tonnes per hour depending on material bulk, density and condition.

Pull wire and emergency stop button Feed material was limited to 450mm maximum size and 50kgs maximum weight; any combustible or corrosive material was removed. The system allows manual selection and rejection of particular materials not required in the end product, into 35 cubic yard skips.

The LJH integrated waste sorting system removes the fines materials from the waste stream as they pass through the trommel screen, with the blower carrying light materials, paper and plastics etc, via a duct to a 35m3container. The remaining material transfers to a picking belt where sorting of up to six products including wood metal, glass and non-ferrous is completed by hand selection. The hand selected products are dropped through collection bins to 35m3 containers positioned below the picking belt with the remaining heavy material, ie, hardcore, being rejected to a fourth bay eliminating the necessity for handling.

The incoming waste is deposited into a series of pre-sorting bins, this material is then fed at a feed height of 3 metres into the 10 cubic metres heaped capacity ground level feed hopper.

Feed hopper within the building A General Kinematics 4 x 1.2 metre wide vibrating tray feeder is mounted under the feed hopper to absorb the shock loads of the material dropping from the loading machinery and provide a metered flow onto the feed conveyor belt, this feeder is supported by a heavy-duty fully welded tower, rigidly tied and braced for maximum stability.

Material is then fed into a heavy-duty receiving hopper, supported on rubber impact bars complete with a low friction running surface this feeds material onto the inclined conveyor, 16.87 metre centres x 1.2 metre belt width driven by a 50 Hz TEFV motor through a shaft mounted gearbox to the head drum shaft. The head drum is lagged with rubber diamond pattern material to prevent belt slippage. High sided steel skirts are provided on the conveyor, along its entire length to prevent material spillage, soft rubber sealing strips that are easily adjustable for wear are also fitted to minimize spillage of fine materials.

This conveyor feeds into the heavy-duty 2400mm diameter x 9500mm long six-bay trommel, inclined at 6 degrees it is mounted on polyurethane tyred wheels and fitted with solid machined steel roller paths to facilitate smooth running and minimize tyre wear.

Inclined feed conveyor and trammel Supported by a heavy-duty fully welded tower and trestle rigidly tied and braced for maximum stability the trommel is driven by a 50 Hz TEFV motor unit through a heavy-duty chain drive with segmented sprockets bolted to the trommel feed ring, thus ensuring a positive slip-free drive at all times. The screening elements are of 10mm thick mild steel plates with apertures punched to diameters of 50mm and 25mm which are bolted to the trommel frame for ease of replacement or renewal, additionally six heavy-duty brushes on spring loaded bearing units complete with hinged frames for ease of maintenance are fitted to clean the screen plates.

The trommel then feeds onto the feed chutes of two separate fines conveyors providing fines stockpiles of -25 and -50/+25. Oversize material from the trommel feeds onto the picking belt conveyor; to enable separation of heavy and light materials a blower unit is situated below the discharge of the trommel enabling separation of materials whilst in free fall onto the picking belt.

This blower unit comprises of a centrifugal fan, backward curve type, high quality mild steel impeller balance to ISO 6.3 standard, mounted to a fully machined EN8 shaft and running on plumber block bearing units. Enclosed in a mild steel casing with fabricated inlet cone to ensure a smooth flow of air; it is driven by a 50Hz motor unit coupled to the impeller shaft. A manually adjustable damper fitted to the air duct regulates the airknife pressure.

Initial stages of construction on picking belt section outside of the building The picking station is built of heavy-duty fully welded lattice gantry construction to minimize the amount of support legs required in the skip area. The picking belt is 18.23 metre centres x 1.2 metre width fitted with two picking stations each side. The picking stations comprise of a 1200mm x 400mm discharge chute with an adjacently mounted emergency stop. At the feed section the belt is supported on rubber impact bars complete with a low friction running surface. Closed pitched parallel idlers are fitted there after and the picking section of the belt is supported on low friction, ultra high molecular weight polyethylene running strips.

The picking station belt is driven by a 50Hz TEFV motor through a shaft-mounted gearbox to the head drum shaft, the head drum is lagged with diamond pattern material to prevent belt slippage. Additionally conveyor drums are of heavy-duty design and constructed with welded EN8 shafts. The belt speed is variable between 0 and 0.25 metres per second and controlled from a rotary switch mounted on a control box, each side of the picking belt.

Picking belt station with magnet at far end. This is before enclosure is fitted A portable frame was supplied to support the customers cladded building that housed the picking station this has a nominal clearance height under bins of 3.7 metres.

Material then passes under a permanent self-cleaning overband magnet separator which is mounted to the picking station to remove any ferrous materials from the oversize material, this is complete with support frame and discharge chute suspended across the picking station; hardcore material is then discharged to a fourth bay.

All necessary access was provided by galvanized grip walk type open floor mesh and galvanized tubular handrailing, additionally 800mm wide platforms were constructed from durbar pattern floor plates in the picking station area.

Emergency stop buttons and pull wires were located throughout in relevant positions.

The complete LJH integrated waste sorting system was built to comply with European Directive 98/37/CE; all conveyors were fully guarded to BS7300. The system was installed with electrical connection, controls and commissioning in less than four weeks.