Belt Conveying in Recycling Plants

Every other industry specifies a conveyor for a known material. A recycling plant specifies it for an unknown one: mixed waste, commercial and industrial residue, construction material, or a kerbside stream whose composition changes with the season and the collection round.

Each component damages the machine differently. Sharp metal cuts the belt cover and then the carcass. Textiles, film and wire wrap around shafts and pulleys until the drive stalls. Glass abrades. Moisture and organics corrode and smell. And lithium cells, which arrive in the stream whatever the rules say, ignite when they are crushed.

Loading is uneven, which makes tracking harder than with a graded product. An unevenly loaded belt wanders, and a wandering belt spills, and a plant that spills builds up material under the conveyor where a fire can take hold.

And the whole thing is usually inside a building, which concentrates the dust, the odour and the consequences of a fire.

The usual way to specify a belt conveyor starts from a known material, and a known material is exactly what a recycling line does not have.

Separation that happens as early in the line as possible, so that every metre of belt downstream is carrying a stream that has already lost its worst components.

Shafts protected against wrapping, with clearing points that can be reached and isolated safely, because clearing will happen often.

Fire detection and a response plan along the conveying route, and a building design that does not let material accumulate where it cannot be cleaned.

In a building materials plant spillage is the load the structure carries every day rather than a housekeeping cost, and crystalline silica makes it an exposure question as well.

The line is designed from the separation backwards. Magnets, eddy current separators and oversize screening sit as early as the layout allows, because the protection they give applies only to what is downstream of them.

Belt specification then covers cut resistance and impact rather than only capacity, with a replacement interval that is planned rather than discovered. In many plants the belt is a consumable measured in months, and the design question is how quickly it can be changed.

Anti wrap protection goes on every shaft and pulley that fibre can reach, with accessible clearing points and a lockout arrangement that makes clearing a two minute job done safely rather than a five minute job done badly.

Fire detection is specified along the route and at transfer points, with thermal imaging or linear detection, and the response plan covers what happens to a burning load on a running belt. Housekeeping is designed in: no ledges under the conveyor, access to clean, and surfaces that shed rather than collect.

• Magnets, eddy current separation and oversize screening placed as early as the layout allows.
• Belt specified for cut resistance and impact, with a planned replacement interval.
• Anti wrap protection on every reachable shaft, with safe accessible clearing points.
• Fire detection along the route and at transfer points, with a written response plan.
• No ledges or dead areas under conveyors, and access to clean what accumulates.
• Dust and odour control designed for the building rather than for the machine.

• Composition of the incoming stream and how much it varies, which is the primary design input.
• Separation steps available upstream, since protection only applies downstream of them.
• Belt cut resistance and the replacement interval the plant can accept.
• Fire detection and suppression strategy, including lithium cells in the stream.
• Clearing frequency and how safely and quickly a wrap can be removed.
• Dust and odour control for an enclosed building.