A high-quality washing unit for a sand and gravel production line

The principal equipment in a mature production line comprises crushers and screening machines, with auxiliary machinery including conveying equipment, washing apparatus, storage facilities, and electrical control systems.

Manufactured sand products must undergo water washing. Cleaning sand and gravel removes impurities such as soil and controls the content of fine particles. Washed aggregates used in concrete enhance its quality while reducing water consumption. Consequently, the adoption of washing units at aggregate plants is becoming increasingly commonplace.

Two approaches exist for aggregate washing:

Where the sole objective is to control fine particle content in the finished product, washing may be conducted on a vibrating screen. The wash water, along with fine particles smaller than the lower screen mesh, then enters the aggregate washing machine. This separates water and fine particles from the aggregate, yielding the required material. The water and fine particles are subsequently recovered for recycling after sedimentation and dewatering. Alternatively, washing may occur within the aggregate cleaner itself (i.e., bypassing the vibrating screen). In this case, the cleaner's rotational speed and overflow water volume must be regulated according to the fine powder content in the finished product to control the removal and retention of fine particles. 

Where the primary objective is to remove clay adhering to aggregate particles, crushed stone or rock washers must be employed prior to fine crushing to scrape off clay from rock surfaces. This ensures the quality of sand and gravel following subsequent crushing and screening. Such equipment is typically positioned before the vibrating screen, with washing preceding screening.

External aggregate plants employ hydraulic classifiers positioned between vibrating screens and sand-stone washers to regulate sand gradation and meet relevant standards while controlling wash volume and maximising fine particle recovery. This approach is rarely adopted domestically. Significant losses of fine particles necessitate extensive tertiary sedimentation tanks for recovery or substantial dewatering/recovery equipment; otherwise, discharge causes severe environmental pollution.

OCP Heavy Industry, with 40 years of experience in manufacturing and developing large-scale mining equipment, offers core machinery including jaw crushers, impact crushers, cone crushers, sand makers, washing and sorting equipment, and conveying systems. We provide tailored production line solutions based on client requirements, including complimentary installation and training. Site visits to our facilities are welcome! Click our website chat for immediate free consultation – available 24 hours online.