The complete process of pebble crushing and sand making needs to go through multi-stage crushing, screening, shaping and cleaning, etc., and finally produce the mechanism Pebble sand making sand which meets the standard of construction sand.
I. Pebble sand making Raw material preparation and pretreatment
1.Raw material source
Riverbed pebbles, mountain weathered pebbles or mine-mined pebbles (particle size ≤ 1200mm).
2.Pre-treatment
Impurity removal: remove impurities such as wood chips and metals by hand or mechanically (e.g. excavator magnetic separator).
Pre-screening: use vibrating grizzly screen to separate soil and super size stones (>1200mm need to be crushed manually).
Cleaning (optional): If the mud content >5%, use drum washing machine to pre-wash the mud.
Core crushing and sand making process
1. Coarse crushing stage
Equipment: Jaw Crusher
Function: Crush the raw material to the medium size of ≤300mm.
Process:
Raw material → Vibrating feeder uniform feeding → Jaw Crusher crushing → Belt conveying to transit pile or directly into the medium crushing stage.
2. Medium and fine crushing stage
Equipment: fine jaw crusher or impact crusher.
Function: To further crush the coarse crushed material to ≤50mm fine aggregate.
Selection logic:
High hardness pebbles are preferred to fine jaw crusher (strong wear resistance, low cost);
If the pursuit of particle shape and the raw material is dry, the impact crusher can be chosen (the finished product has more angles, but fast wear).
Process:
Coarse crushed material → fine crushing jaw crusher → belt conveyor to screening section.
3. Pebble sand making Screening and circulation
Equipment: circular vibrating screen (2-3 layers of mesh)
Role: Classify the aggregates with different particle sizes, and return the over-sized materials to be re-crushed.
Screen configuration:
Upper screen hole: 40-50mm (return to the crusher);
Middle screen: 20-30mm (into the sand making machine);
Lower screen: 5mm (directly as fine aggregate or into the sand making machine).
Process:
Medium crushed material → vibrating screen grading → qualified material enters the sand making process, oversized material returns to the medium crusher.
4.Sand making and shaping
Equipment: Roll Crusher
Role: crushing ≤30mm aggregate to 0-5mm mechanism sand, and optimise the particle shape.
Process:
Aggregate after screening → sand making machine crushing → belt conveying to screening or sand washing section.
5. Secondary screening and finished product grading
Equipment: high frequency dewatering screen or air screen
Role:
Separate the 0-5mm finished sand from the sub-standard coarse sand (return to sand making machine);
Control fineness modulus (usually 2.2-3.0).
Process:
Sand making machine discharging → vibrating screen grading → qualified sand enters the cleaning link, coarse sand circulates crushing.
Raw material → vibrating feeder (with grizzly screen) → jaw crusher → fine jaw crusher → roll sand making machine → high frequency dewatering screen → bucket washer → fine sand recycling machine → finished sand pile
