flow diagram of sand and gravel plant

# Flow Diagram of a Sand and Gravel Processing Plant

Sand and gravel processing plants are essential for producing high-quality construction materials. The process involves several stages, including extraction, crushing, screening, washing, and stockpiling. Below is a detailed flow diagram outlining the typical operations in a sand and gravel plant.

## 1. Extraction (Mining)
- Raw material is excavated from pits or dredged from riverbeds using loaders, excavators, or dredges.
- The extracted material is transported to the processing plant via trucks or conveyor belts.

## 2. Primary Crushing
- Large rocks and oversized gravel are fed into a jaw crusher or gyratory crusher for initial size reduction.
- Crushed material is then conveyed to secondary crushing or screening stages.

## 3. Screening (Scalping & Classification)
- A vibrating grizzly screen removes oversized rocks before further processing.
- Material passes through trommel screens or vibrating screens to separate sand from gravel by size:
- Coarse gravel (>20mm) → Sent for further crushing or stockpiled as final product.
- Medium-sized gravel (5–20mm) → Washed and classified for concrete aggregate.
- Sand (<5mm) → Sent to washing systems for impurity removal.

## 4. Secondary Crushing & Tertiary Crushing (If Needed)
- Medium-sized gravel may be crushed further in a cone crusher or impact crusher.
- Fine material undergoes additional screening before washing.

## 5. Washing & Scrubbing
- Sand and fine aggregates pass through a log washer, sand screw, or hydrocyclone to remove clay, silt, and organic impurities.
- Cleaned sand is dewatered using vibrating screens or centrifuges before stockpiling.

## 6. Stockpiling & Distribution
- Processed sand and gravel are stored in separate stockpiles based on size specifications (e.g., coarse aggregate, fine sand).
- Final products are loaded onto trucks or railcars for delivery to construction sites or concrete plants.

[Simplified Flow Diagram]

```
Extraction → Primary Crushing → Screening → Secondary Crushing → Washing → Stockpiling
```

Key Equipment Used:
- Crushers (Jaw, Cone, Impact)
- Vibrating Screens