Sand preparation is the general term for producing formable, ready-to-use moulding sand for sand moulding, shell moulding, or core making. A basic distinction is made between the preparation of new (fresh) sand and the preparation of reclaimed (used) sand.
How Sand Preparation Works
In practice, sand preparation typically follows a repeating sequence. First, the base sand (new sand or returned reclaimed sand) is mixed with binder and, in the case of green sand, water and additives, so that it takes on the moulding properties required for compaction. Because mixing generates heat and moisture is added during processing, the sand must then be cooled and, depending on the system, aerated before it can be used. Sand coolers take on this task: they bring the freshly mixed sand down to a defined temperature and moisture level so that mould and core quality stay consistent from batch to batch. The prepared sand is then screened to remove lumps, metal residues, and oversized particles before it goes to the moulding or core-making station. After casting and shake-out, used sand is returned to the preparation circuit, where it is reclaimed and, if its properties allow, mixed back in with fresh sand and binder for reuse.
Special sands such as zircon sand are prepared and handled separately from standard silica sand. Zircon sand is valued for its high density and very low thermal expansion, which makes it useful where dimensional accuracy and resistance to expansion-related casting defects are especially important.
New Sand vs. Reclaimed Sand
| Aspect | New sand | Reclaimed (used) sand |
|---|---|---|
| Origin | Fresh raw sand delivered to the foundry | Used moulding sand returned from shake-out after casting |
| Preparation steps | Mixing with binder (and water/additives for green sand), cooling, screening | Reclamation to remove spent binder and fines, cooling, re-mixing with fresh binder as needed |
| Reusability | First use; establishes baseline moulding properties | Can be reused multiple times if reclamation quality is sufficient, reducing raw material and disposal costs |
Frequently Asked Questions
What is the difference between new sand and reclaimed sand?
New sand is fresh raw sand being prepared and used for the first time. Reclaimed sand is used sand that has gone through casting and shake-out and is then processed so it can be mixed with binder again and reused in moulding or core making.
Why is sand cooled after preparation?
Mixing sand with binder generates heat and adjusts its moisture content. Cooling the sand afterwards brings it to the temperature and moisture level needed for consistent compaction and mould quality before it reaches the moulding machine.
What is sand preparation used for?
Sand preparation supplies formable, ready-to-use sand for sand moulding, shell moulding, and core making, and is closely linked to equipment such as moulding machines and binder systems like furan resin binders.