Aggregate Washing: Why Is Washed Material Better?
Washing separates clay, silt and stone dust from aggregate. Learn how this stage affects concrete, what equipment is common, and how water and sludge are managed.
Production and processing
Screening and Grading: How Aggregate Is Separated into Sizes
A vibrating screen turns crusher output into separate products. Learn what affects screen efficiency, the main media types and common problems such as blinding.
Crusher output is a mix of sizes. Screening turns it into separate classes, and the grading of the product reaching a stockpile largely results from how well this stage works.
How a screen works
A vibrating screen spreads material over the deck. Coarse particles rise to the top and fine particles work down to the deck to pass through the openings. Multi-deck screens make several products at once.
What affects efficiency
- Feed rate: a thick bed stops fine particles reaching the deck.
- Feed distribution: feed should spread evenly across the screen’s width.
- Angle and stroke: these set how fast material travels.
- Moisture: damp fines stick to each other and to the deck.
- Particle shape: elongated particles may not pass, or may lodge in an opening.
Common media
Woven steel wire is widely used and economical. Polyurethane and rubber media last longer in abrasive materials and reduce blinding but have less open area.
Common problems
| Problem | Result | Where to check |
|---|---|---|
| Fines in coarse product | Out of grading limits | Feed rate and washing |
| Oversize in fine product | Contaminated class | Torn media |
| Blinded openings | Lower capacity | Moisture and media type |
Monitoring the product
Torn media may go unseen for hours yet contaminates every load. Regular sampling and comparing the grading curve reveal the problem early. After screening, keeping the grading depends on stockpiling correctly.
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