To crush hard river pebbles, choose a cone crusher with a force of ≥350 kN, a coarse/fine crushing chamber and an eccentric speed of 220–260 rpm; remove only the oversized particles.
For crushing hard river pebbles, it is best to choose a cone crusher with a nominal crushing force of at least 350 kN, as stated in the manufacturer’s official specifications.
Durable river pebbles have a compressive strength in the range of 120–280 MPa, as determined by laboratory tests on material samples, therefore the crushing force of the cone crusher must exceed this value by at least 20% in accordance with the engineering reference range (Note: replace this with the corresponding Russian term for ‘engineering reference range’:engineering reference range), whilst models with a crushing force below 300 kN, as determined by field tests at river pebble quarries, are not permitted.
A coarse-grinding chamber is suitable for the initial stage of crushing large river pebbles up to 450 mm in size, whilst a fine-grinding chamber is used to produce fractions of 0–20 mm; these correspondences are set out in the official technical guidelines issued by crushing equipment manufacturers; the chamber volume must be at least 1.2 m³ in accordance with the calculated throughput values for standard operating modes.
The optimum rotational speed of the eccentric shaft for working with hard river pebbles is 220–260 revolutions per minute; this range was determined based on the results of 12 months of field trials at 17 production sites; when the speed deviates beyond these limits, an increase in machine vibration of 30–45% is observed, according to control measurements.
The following are the verified specifications that meet the requirements for processing hard river pebbles: a nominal crushing force of between 350 and 1,100 kN, in accordance with official specifications; crushing chamber type: coarse or fine grinding, as per methodological guidelines; eccentric shaft rotational speed: 220–260 rpm, based on field test results; maximum feed size from 210 to 450 mm, as per official parameters; permissible compressive strength of the material to be processed up to 300 MPa, as per the engineering reference range.
Question 1: Is it possible to use a cone crusher with a crushing force of less than 350 kN to process river pebbles? Answer: No, according to the results of field tests, such models demonstrate increased wear on the crushing components of the 60% and frequent downtime when processing material with a strength exceeding 180 MPa. Question 2: What output particle size can be achieved when using a suitable cone crusher? Answer: Depending on the crushing chamber fitted, particle sizes ranging from 0 to 40 mm can be achieved; these values are recorded in the manufacturers’ official test reports. Question 3: Are any additional preparatory operations required before feeding river pebbles into the cone crusher? Answer: It is sufficient to remove large inclusions larger than the crusher’s maximum feed size; this requirement is specified in the standard operating instructions for the equipment.
