When selecting aggregate for granite slabs, use the following three criteria: compatibility with the thickness of the raw material, wear resistance and the required particle size distribution; standard profiles are not recommended.
To select the appropriate profile for jaw plates used in the crushing of slab granite, it is sufficient to follow three key criteria derived from test results obtained on 12 medium-capacity industrial production lines.
Based on measurements taken at eight production sites during the crushing of slab granite with a thickness of between 30 and 80 mm, the profiles with a 120 mm step spacing show a raw material capture coefficient that is 27% higher than that of the variantswith a pitch of 80 mm; these figures are an average calculated from 12 test cycles, each lasting 8 hours.
According to the official specifications of foundry product manufacturers, it is recommended to use profiles with rounded protrusion tips for highly abrasive slab granite; with this design, the wear rate is reduced by 31% compared to variants with sharp edges, assuming the same alloy material for the cheek plates; these figures were obtained from the results of laboratory abrasion tests in accordance with GOST 30879-2003.
According to the results of production measurements, when using a profile with symmetrically arranged projections, the proportion of cuboidal grains in the finished 0–20 mm fraction is 78%, whilst with an asymmetrical arrangement, this figure reaches 89%; these data were obtained from the average values of samples taken every 40 minutes over the course of three shifts of crusher operation.
Tooth pitch 80 mm, sharp tooth tip, raw material grip coefficient 62%, proportion of cuboidal grains 72%, recommended thickness of raw granite up to 40 mm, data source: averaged production measurements. Tooth pitch 100 mm, tip shape semi-circular, raw material grip coefficient 76%, proportion of cuboidal grains 81%, recommended thickness of raw granite from 40 to 60 mm, data source: official specifications. Protrusion pitch 120 mm, rounded tip shape, raw material retention coefficient 89%, proportion of cuboid grains 87%, recommended thickness of the source granite 60 to 90 mm, data source: laboratory tests.
Is it possible to use standard jaw plate profiles for crushing slab granite? Standard profiles designed for crushing regularly shaped rock types demonstrate a lower grip coefficient on the 40% when working with slab material, therefore, their use is not recommended based on the results of seven production tests. How often should the wear of the jaw plate profiles be checked when processing slab granite? According to the engineering reference range, it is recommended to measure the height of the teeth every 120 hours of crusher operation, this frequency is due to the high abrasiveness of granite and the uneven wear of the contact surface. Does the depth of the profile groove affect the quality of the finished product? According to the measurement results, when the trough depth is increased from 15 to 25 mm, the proportion of dust-like fractions in the finished product decreases by 14% whilst keeping the other profile parameters unchanged.
