Washed sand is made by cleaning natural silica sand with a sand washer to meet construction standards. In essence, it's natural sand that has been scrubbed and rinsed with water to remove impurities.
Here's a breakdown of the process:
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Extraction of Natural Sand: The process begins with extracting natural sand from sources like riverbeds, quarries, or coastal areas. This raw sand typically contains various impurities.
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Feeding into a Sand Washer: The extracted natural sand is then fed into a specialized piece of equipment called a "sand washer."
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The Washing Process: The sand washer uses a combination of water and mechanical agitation to separate and remove unwanted materials from the sand. These materials can include:
- Silt
- Clay
- Dust
- Organic matter
- Small pebbles or debris
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Types of Sand Washers: Different types of sand washers exist, including:
- Screw Washers: These use a rotating Archimedes screw within a trough of water to agitate and convey the sand, allowing impurities to settle or overflow.
- Wheel Washers: These utilize a large rotating wheel with buckets that scoop up sand and water, depositing the sand onto a screen where it's rinsed with high-pressure water jets.
- Log Washers: Used for more heavily contaminated sand, these machines have rotating logs with paddles that aggressively scrub the sand.
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Separation and Discharge: As the sand is washed, the lighter impurities are suspended in the water and overflow the sides of the washer. The cleaned sand, being heavier, settles and is discharged from the machine.
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Dewatering (Optional): In some cases, the washed sand may be further dewatered to reduce its moisture content. This can be done through methods like drainage beds or mechanical dewatering equipment.
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Quality Control: The washed sand is then tested to ensure it meets specific quality standards for particle size distribution, cleanliness, and other properties relevant to its intended use in construction.
Therefore, the key to making washed sand is the use of a sand washer to physically separate and remove undesirable components from natural sand using water as the primary cleaning agent. This ensures that the sand is suitable for various construction applications.
