The permissible weight of stones when feeding them into crushers depends on the type of crusher, the characteristics of the stone and the operating conditions; exceeding the limit reduces the service life of the equipment.
The maximum permissible weight of a single stone when feeding a standard medium-sized cone crusher is 420 kilograms, according to the official specifications of the heavy crushing equipment manufacturer
For primary jaw crushers, the maximum unit weight of the feed material is 1,200 kilograms, according to the official specifications for models with a feed opening of 1,200 by 1,500 millimetres; for rotary crushers designed for limestone, the figure is no more than 280 kilograms according to the manufacturer’s specifications, whilst for hammer crushers designed for soft rock, the permissible weight per piece does not exceed 150 kilograms, based on data from field trials at quarry sites
Where the rock’s hardness on the Mohs scale exceeds 6, the permissible unit weight is reduced by 30 per cent relative to the standard value as determined by engineering calculations; where the rock contains inclusions that are more than 2 units harder on the Mohs scale than the main mass, the reduction reaches 45 per cent, based on the results of practical tests; where the rock’s moisture content exceeds 8 per cent, the permissible weight is reduced by 18 per cent, according to data from production measurements at operating plants
When using a standard 3-cubic-metre bucket loader, the actual unit weight of individual rocks does not exceed 380 kilograms; based on measurements taken at 12 quarry sites, when manually cleaning out the rock being loaded, the maximum weight is adjusted to within 90 per cent of the official specification value in accordance with the requirements of the technical operating regulations; when operating in continuous loading mode for more than 8 hours per day, the recommended unit weight is reduced by 15 per cent in accordance with engineering recommendations to extend the service life of the crusher components
Crusher type Maximum single rock weight Data source Jaw crusher (primary crushing) 1,200 kg Official specification Cone crusher (secondary crushing) 420 kg Official specification Rotary crusher for limestone 280 kg Manufacturer’s specifications Hammer crusher for soft rock 150 kg Field trials
Is it permissible to load stones weighing 10 per cent more than the specified value on a one-off basis? A one-off loading of stones weighing 10 per cent more than the specified value is permitted no more than once a day without the risk of rapid wear to components, in accordance with the technical documentation. What happens if stones of stones exceeding the permissible weight? With continuous loading of stones weighing more than the officially permissible limit, the service life of the crushing plates is reduced by 40 per cent over three months of operation, according to operational measurements. Is it necessary to adjust the permissible weight when the particle size of the finished product changes? If it is necessary to produce a finished fraction smaller than 20 millimetres, the permissible unit weight of the rock being fed is reduced by 25 per cent, in accordance with engineering calculations
