English
Russian
Principles for Designing the Production Process Flow
A well-designed mechanized sand production process must balance process rationality, operational reliability, energy efficiency, and equipment compatibility. Optimal circuit layouts are engineered according to raw feed size, rock compressive strength, abrasiveness, and target aggregate specifications. Key engineering principles include:
Stage Reduction Ratios: Recommended reduction ratios are Primary Crushing (i=3-5), Secondary Crushing (i=4-5), and Tertiary Shaping/Sand Making (i=5-8). Maintaining balanced reduction prevents bottlenecking at downstream screens and crushers.
Product Shape & Cubicity: Concrete aggregate standards enforce strict cubical geometry limits (flaky and elongated particles < 10%). Impact crushers and VSI centrifugal crushers utilizing rock-on-rock autogenous beds ensure high particle roundness.
Moisture and Fine Control: Wet classification requires hydrocyclone fine recovery, while dry process systems incorporate air classifiers to adjust filler content between 5% and 10%.
Core Equipment Selection: Matching Crushers to Rock Hardness
Primary Stage: Heavy-duty PE Jaw Crushers or Gyratory Crushers handle raw blast quarry rocks up to 1000mm.
Secondary Stage: Multi-Cylinder Hydraulic Cone Crushers excel in crushing hard rocks (granite, basalt, quartzite) with compressive strength exceeding 250 MPa, minimizing flakiness.
Sand Shaping Stage: Deep-chamber VSI Sand Making Crushers running at rotor tip speeds of 65-80 m/s achieve optimal continuous gradation and controlled fineness modulus (FM 2.6 - 3.0).
Engineering FAQ: Sand Making Plant Design
Q1: How do you adjust the Fineness Modulus (FM) in a dry VSI sand plant?
Adjusting the rotor speed via VFD directly influences fines generation (higher speed yields finer sand). Simultaneously, adjusting the waterfall bypass ratio (cascade feed) regulates the ratio of rock-on-rock shaping versus direct impact crushing, fine-tuning the FM within +/- 0.2 points.
Q2: When should a dry air-classifier be chosen over wet sand washing?
Dry air classification is ideal in water-scarce regions, cold climates prone to freezing, or when processing limestone where stone powder (< 0.075mm) has commercial value as asphalt filler. Wet washing is mandatory when raw gravel contains plastic clay or sticky soil clumps.