The type of screening media a quarry uses is partially dictated by the type of materials it's excavating. Polyurethane, wire and rubber each accommodate different operations.
In some cases, screening rip rap may not be necessary.
Rip rap, gravel and sand are generally processed the same way, although subtle differences between the procedures exist. This article will assess each material's handling requirements and determine which type of screening media is suited their systems.
Typically used to combat erosion along coastlines, rip rap is defined as rough-edged rocks that are relatively similar in dimension, according to the US Department of the Interior's Bureau of Reclamation.
At times, screening isn't necessary, as the material can be quite large (121 centimetres in diameter). Downer Contracting, a Canadian quarrying service, processes rip rap of this size by using excavators equipped with thumbs. When choosing specific media, consider the size of the material shown in the video below:
For quarries processing smaller class rip rap (around 15 centimetres), using heavy woven wire screens is typically the best option. Polyurethane screens will likely encounter damage when handling such heavy stone.
Depending on certain dimensions (particularly thickness), rubber media may be useful as well.
When handling gravel, the key is to separate any sand or other debris from the crushed stone so that it can be used for roads, foundations and other purposes. The US Environmental Protection Agency (EPA) maintained that this process typically necessitates water, so it's important to assess how wet material will impact the effectiveness of certain screens.
As far as creating a slick surface goes, polyurethane and water are a match made in quarrying Heaven. Combining the two creates a lubricant that enables gravel to move more quickly down the media.
In regard to the actual design, a polyurethane ripple screen is arguably the best choice. This will allow sand to easily slip through the apertures, and will probably reduce the amount of times you'll have to clean it.
More often than not, a conversation regarding gravel typically involves a discussion about sand. In regard to water-based processing, sticking with polyurethane ripple screen is probably best.
In other instances, fine wire screens are often better for drier conditions. The vibrations combined with thin metal screening can create just the right amount of flexibility need to shake sand to carrier belts located beneath the media.
It should be noted that fine wire may pose some minor frustrations in regard to pegging and blinding, depending on the size of the stone mixed in with the sand. If larger stones are involved, then this will probably be less of an issue.
Be aware that choosing between polyurethane, wire and rubber depends on numerous factors. The recommendations above are for very specific situations, and may not be applicable to your protocols.