You’re choosing between reclaimed sand and new sand for your casting operations, and the decision affects your production costs, casting quality, and waste management strategy. Reclaimed sand costs $1-8 per ton to process compared to $40-80 per ton for new sand, but you’ll need to understand how processing affects performance before making the switch.
Reclaimed sand is spent foundry sand that’s been cleaned through mechanical, thermal, or wet processing to remove binders and contaminants, while new sand is virgin silica material purchased directly from mining operations.
New sand arrives with consistent, predictable properties. Virgin silica sand has a specific gravity between 2.5 and 2.8 depending on the source.
Most foundries purchase sand classified as AFS 80 under the American Foundry Society grain fineness numbering system. This classification measures average particle size distribution, and it directly affects surface finish and permeability in your molds.
New sand costs $40-80 per ton before you add transportation fees. Transportation can significantly increase your delivered cost, especially if your foundry sits far from mining operations.
The consistency is the main advantage. Every shipment meets the same specifications, which reduces variability in your molding process.
Reclaimed sand goes through one of three processing methods. Mechanical reclamation uses motion energy to physically break down spent sand into clean, grain-size particles. This process costs approximately $1 per ton.
Thermal reclamation adds heat treatment at temperatures between 600°C and 750°C to burn off residual resins and organic binders. Operating costs run $6-8 per ton. Studies show that mechanically reclaimed sand delivers superior performance for sand reusability and casting quality compared to thermal methods.
Wet reclamation uses chemical treatments with substances like sulfuric acid or sodium hydroxide to strip binder coatings from sand grains. This method produces excellent results but generates chemical sludge that requires disposal.
Reclaimed sand must be cooled, dried, screened, and de-lumped after processing. Temperature control is critical because using sand that’s too hot or too cold reduces casting quality throughout your production line.
Foundries typically recover 70-95% of spent sand for reuse. The reclamation rate depends on your processing method, binder system, and quality requirements.
| Property | New Sand | Reclaimed Sand (Mechanical) | Reclaimed Sand (Thermal) |
|---|---|---|---|
| Cost per ton | $40-80 + transport | ~$1 processing | $6-8 processing |
| Specific gravity | 2.5-2.8 | 2.5-2.8 (maintained) | 2.5-2.8 (maintained) |
| AFS fineness | Consistent (typically AFS 80) | May vary slightly | Consistent after processing |
| LOI (Loss on Ignition) | 0.29% | Higher (affects binder needs) | <0.1% |
| Binder requirements | Standard ratios | Standard ratios | Substantially reduced |
| Processing requirements | None | Cool, dry, screen, de-lump | Cool, dry, screen, de-lump |
| Consistency | Excellent | Good with quality control | Excellent |
| Disposal cost savings | $0 | $30-100/ton avoided | $30-100/ton avoided |
Properly processed reclaimed sand can match the casting quality of new sand when you maintain strict quality controls and testing schedules. The key difference is that reclaimed sand requires more frequent monitoring because its properties change gradually with each reclamation cycle.
Grain size determines surface finish quality in your castings. Finer sand grains produce smoother surfaces because the particles pack more closely together in the mold cavity.
The AFS Grain Fineness Number (AFS-GFN) measures average particle size. Higher GFN numbers indicate smaller grains. The calculation comes from a 15-minute sieve test where you pass dried sand through progressively finer screens.
Mechanically reclaimed sand sometimes exhibits higher LOI values compared to new sand. Visual inspections show that castings made with high-LOI reclaimed sand can have rough surfaces and silica inclusions embedded in the metal.
Thermal reclamation solves this problem. Sand processed at 600-750°C has LOI values below 0.1%, which matches or beats new sand specifications.
Thermally reclaimed sand needs less binder than new sand to reach the same mold strength. This advantage comes from the ultra-clean surface of thermally processed grains.
Some foundries run all sand through thermal processing to achieve consistent quality, even when using virgin material. This practice standardizes the sand properties entering your molding system.
Sand degrades with repeated reclamation cycles. Sodium silicate bonded sand can cycle through 8-12 uses before you see significant strength loss.
Recycled sand accumulates sodium carbonate and fine particles over time. After 10 reclamation cycles, strength typically drops by about 15% due to this contamination buildup.
High sodium carbonate content eventually forces you to use wet or thermal reclamation at 600-800°C, which increases your energy costs. The alternative is removing degraded sand from the system and adding fresh material.
| Defect Type | New Sand Risk | Reclaimed Sand Risk | Prevention Strategy |
|---|---|---|---|
| Rough surface finish | Low | Medium (mechanical) to Low (thermal) | Use thermal reclamation or maintain LOI <0.1% |
| Silica inclusions | Low | Medium (high LOI sand) | Monitor LOI levels, increase processing temperature |
| Gas porosity | Medium | Medium to High (low permeability) | Control fines content, test permeability regularly |
| Metal penetration | Depends on GFN | Depends on GFN | Match grain size to metal type and temperature |
| Mold deformation | Low | Medium (if improperly cooled) | Cool reclaimed sand to consistent temperature |
| Burn-on defects | Medium | Medium to High (carbonate buildup) | Remove aged sand, maintain proper sand-to-metal ratio |
The defect comparison shows that most quality issues with reclaimed sand stem from incomplete processing or inadequate quality control. When you cool, dry, and screen reclaimed sand properly, defect rates match those of new sand systems.
You should investigate sand reclamation when your foundry generates 2 tons per hour of spent sand and strongly consider implementation at 5 tons per hour or higher. Below these thresholds, the equipment investment typically exceeds the savings from reduced sand purchases and disposal costs.
High-volume operations benefit most from reclamation. When you’re running continuous production, the equipment utilization justifies the capital investment.
Standard casting applications don’t require virgin sand consistency. Products like manhole covers, machine bases, and structural components work fine with properly processed reclaimed material.
Critical surface finish requirements sometimes demand new sand. Precision castings for aerospace, medical devices, or visible consumer products may specify virgin material.
The first sand entering a new molding system should be virgin material. Starting with new sand establishes your baseline properties before you introduce reclaimed material.
Most foundries operate with blended systems rather than 100% reclaimed or 100% new sand. Typical starting blends are 70% particulated sand and 30% new sand.
For jobs requiring superior surface conditions, adjust your mix to 50% reclaimed and 50% new sand. This approach lets you maintain quality on demanding castings while still achieving significant cost savings.
As you develop confidence in your reclamation process, increase the reclaimed percentage. Many operations successfully run 95% reclaimed and 5% new sand for all but the most critical applications.
When to adjust blend ratios:
