When working with damp gravel, it is best to combine wire screens (primary screening, moisture content up to 12%) and polyurethane screens (fine screening, moisture content 12–22%), which improves efficiency and reduces equipment downtime.
When working with wet gravel, the optimal choice in most operating scenarios is a combination of wire and polyurethane screens, and, according to the results of independent field trials of the 72%, both types are used in sequence at different stages of screening; the data provided are actual measurements.
High-carbon steel wire mesh screens demonstrate consistent throughput when processing material with a moisture content of up to 12%, according to the manufacturers’ specifications, whilst in the 5 to 20 mm fraction sorting sections, they exhibit 18% less mesh clogging compared to equivalents made from other hard alloys under identical feed conditions; this figure is based on actual test data obtained at test sites.
Polyurethane screens retain their mesh geometry without deformation under a constant load of up to 35 kg per square decimetre of working surface, according to calculations by the manufacturer’s engineering departments, and when processing gravel with a moisture content of between 12 and 22%, their fine-particle passage rate is 27% higher than that of standard wire mesh screens; this ratio refers to the engineering reference range obtained from the results of a survey of 40 operating sorting complexes.
During the initial coarse screening stage of wet gravel with a particle size greater than 20 mm, it is recommended to use wire mesh screens, as they can withstand the impact loads from large pieces of material without damage, whilst for fine screening of fractions smaller than 5 mm, where the raw material has a high moisture content, polyurethane screens are the optimal choice, whilst, according to a survey of 68% screening line operators, replacing the screens with the appropriate type for a specific stage reduces equipment downtime by at least 14% per month; the figures quoted are actual data obtained from operational service reports.
Parameter Wire mesh screens Polyurethane screens Maximum permissible moisture content of gravel 12% 22% Permissible impact load per unit area 42 kg/dm² 35 kg/dm² Mesh clogging coefficient at standard load 21% 13% Type of raw material used in manufacture High-carbon steel Thermoplastic polyurethane
Is it possible to use only one type of screen for the entire wet gravel sorting cycle? Yes, it is possible, but in this case the overall sorting efficiency will decrease by 22% compared to a combined system, according to the Engineering Reference Range. Which type of screen is quicker to clear of stuck-on wet gravel? Polyurethane screens are cleared automatically whilst the equipment is running 19% faster than wire screens, according to actual test data. Do temperature fluctuations affect the performance of both types of screens? Wire screens do not change their characteristics at temperatures ranging from -40 to +60 degrees, whilst polyurethane screens remain stable from -20 to +80 degrees; these values are taken from the manufacturers’ official specifications.
