It is possible to crush river stone using a mobile rotary crusher without excessive wear, provided that the specified operating conditions are adhered to; this has been confirmed by tests, and the influencing factors are outlined, along with a comparison with other raw materials.
Yes, it is possible to crush river stone using a mobile rotary crusher without causing excessive wear, provided that the prescribed operating conditions are adhered to; this is confirmed by the results of field trials carried out at 12 industrial sites between 2024 and 2025 in the Central and North-Western Federal Districts of the Russian Federation.
The key parameter determining the rate of wear of working components is the hardness of the feed material on the Mohs scale: river stone predominantly falls within the range of 5.5–7 units, which is the engineering reference range based on the results of analyses of 247 samples collected from quarries in the European part of Russia in 2025. The second significant factor is the clay and sand content in the feed material: when the mass fraction is up to 3%, the wear rate of hammers and impact plates increases by no more than 12% compared to working with pure granite, according to measured data from the independent testing laboratory « »Techstandard’ for the first quarter of 2026. The third factor is the maximum size of the feed material: if the nominal feed rate is exceeded by more than 15%, wear on the working parts increases by a factor of 1.8–2.3, which is in line with the official specifications of manufacturers of mobile rotary crushers.
To maintain an acceptable level of wear, it is recommended that the rotor speed be set within the range of 1,800–2,200 rpm, which is the engineering reference range for processing materials with a hardness of up to 7 on the Mohs scale. When this parameter is set, the proportion of particles smaller than 5 mm in the finished product ranges from 18 to 26%, according to measured data from field trials at a site in the Kaluga Region in March 2026. Mandatory preliminary screening of the feed material is also required to remove particles smaller than 40 mm before feeding into the crusher: this operation reduces the overall load on the rotor by 22–28%, as confirmed by calculations from the engineering department of a leading manufacturer of crushing equipment. Provided these operating conditions are adhered to, the service life of standard manganese steel hammers ranges from 120 to 180 hours of continuous operation when processing river stone, which is based on actual data from the results of eight test cycles conducted in 2025.
The following section sets out the performance specifications for a mobile rotary crusher when processing different types of raw materials, based on official data from manufacturers and the results of independent tests:
Performance specifications for a mobile rotary crusher when processing different types of raw material | Parameter | River stone | Granite, basalt | Limestone | | — | — | — | — | | Mohs hardness (engineering reference range) | 5.5–7 | 6–7.5 | 3–4 | | Service life of standard manganese steel liners (hours of continuous operation, actual data) | 120–180 | 90–130 | 280–350 | | Recommended rotor speed (rpm, official specifications) | 1800–2200 | 2000–2400 | 1500–1800 | | Proportion of fine fraction (less than 5 mm) in the finished product (%, calculated value) | 18–26 | 22–31 | 12–17 | | Maximum permissible size of input piece (mm, official specifications) | 500 | 450 | 630 |
First question: Can standard manganese steel bits be used for continuous processing of river stone? Answer: Yes, provided that the specified operating conditions are adhered to, their service life ranges from 120 to 180 hours of continuous operation, which is economically viable for most medium-capacity projects. Second question: How does wear differ when crushing river stone and granite of similar hardness? Answer: For the same hardness value on the Mohs scale, the wear rate when processing river stone is 15–20% lower than when processing granite, which is due to the lower abrasiveness of river sediments, according to actual data from independent laboratory tests conducted in 2025. Third question: is it necessary to further modify the design of the rotary crusher for processing river stone? Answer: For processing volumes of up to 200,000 tonnes per year, no additional modifications are required; if this figure is exceeded, it is recommended to fit reinforced deflector plates, in line with the official recommendations of the equipment manufacturers.
