A green sand reclamation line is a specialized set of equipment and processes used in the foundry industry to recycle and reuse used green sand (also called molding sand). Green sand is a mixture of silica sand, clay (binder), water, and additives, which is widely used for making molds and cores in casting processes. After casting, the used green sand becomes contaminated with metal oxides, broken sand grains, excess binder, and other impurities. The reclamation line processes this used sand to restore its physical and chemical properties, making it suitable for reuse in new molding operations.

The line typically consists of a series of interconnected machines, arranged in a logical sequence to complete cleaning, separation, and conditioning of used green sand. The core equipment includes:

1. Sand Crushing & Lump Breaking Equipment
   • Lump Breakers/ Crushers: Break large clumps of used green sand (formed by heat and pressure during casting) into smaller particles. Common types are jaw crushers, roll crushers, or vertical shaft impact crushers.
   • Attrition Mills: Use high-speed rotating paddles or impellers to rub sand grains against each other. This removes the bonded clay layer on the sand surface, which is the key step for restoring sand flowability.
2. Separation & Screening Equipment
   • Vibrating Screens: Classify sand grains by size. Oversized particles (such as metal shot, large sand lumps, or debris) are removed, while qualified sand grains pass through for further processing.
   • Air Classifiers: Use airflow to separate light impurities (like dust, clay fines, and organic residues) from sand grains. This improves the cleanliness of the reclaimed sand.
   • Magnetic Separators: Remove ferromagnetic impurities (such as iron filings and metal scraps) from the sand, preventing damage to subsequent equipment and ensuring casting quality.
3. Conditioning & Mixing Equipment
   • Sand Coolers: Used green sand has a high temperature after casting. Coolers (such as fluidized bed coolers or rotary coolers) reduce the sand temperature to the optimal range for molding.
   • Humidifiers & Mixers: Adjust the moisture content of reclaimed sand and mix it with a small amount of fresh binder, water, or additives to restore its bonding performance and workability, matching the requirements of new molding sand.
4. Conveying & Dust Collection Equipment
   • Conveyors: Belt conveyors, screw conveyors, or bucket elevators that transport sand between different processing units, ensuring continuous operation of the line.
   • Dust Collectors: Bag filters or cyclone dust collectors that capture dust generated during crushing, screening, and attrition processes. This protects the working environment and meets environmental emission standards.

1. Cost Reduction
   • Reduces the consumption of fresh silica sand and binders. Reclaimed sand can replace 50%–90% of new sand in most foundry applications, significantly lowering raw material procurement costs.
   • Cuts down waste disposal costs. Used green sand accounts for a large proportion of foundry solid waste; reclamation reduces the amount of sand that needs to be landfilled or transported.
2. Environmental Protection
   • Minimizes the environmental impact of foundry waste. Less new sand mining reduces damage to natural resources, and less waste sand disposal reduces soil and water pollution risks.
   • The dust collection system controls airborne dust emissions, improving workshop air quality and complying with environmental regulations.
3. Improved Casting Quality & Process Stability
   • Reclaimed sand has uniform particle size distribution and stable performance, avoiding the quality fluctuations caused by inconsistent properties of new sand batches.
   • Controlled removal of excess binder and impurities reduces defects such as sand holes, scabs, and pinholes in castings.
4. Enhanced Production Efficiency
   • The automated reclamation line realizes continuous processing of used sand, matching the rhythm of large-scale casting production and reducing downtime caused by sand supply shortages.
   • Conditioned reclaimed sand has good flowability and moldability, which speeds up the molding process and reduces mold repair time.