Operating principle of the bucket sand washer

Detailed description of the operating principle

Power transmission system

The bucket sand washer is driven by an electric motor. After reducing the speed and increasing the torque through a gearbox, the water wheel or bucket device in the washing tank performs continuous circular motion, providing stable and reliable power support for effective sand washing.

Mixing and washing process

Under the constant action of the bucket or water wheel, sand, gravel, or mineral slag particles in the washing tank are continuously rolled, mixed, and washed in water. Dust, clay, and impurities adhering to the material surface gradually separate and disperse under the water flow, being discharged through the upper overflow outlet, ensuring deep cleaning of sand and gravel.

Water circulation and impurity separation

Throughout the entire technological process, clean water is continuously added, forming a powerful circulation flow. The upward water flow timely carries away lighter clay particles, impurities, and foreign inclusions from the washing tank, which are discharged through the upper overflow outlet into the wastewater treatment system, ensuring quality washing while simultaneously recycling water resources.

Dewatering and unloading of finished products

After thorough washing and preliminary dewatering, clean sand and gravel are lifted by the bucket device from the bottom of the washing tank. As the bucket tips, sand and gravel are evenly unloaded into the discharge opening and smoothly proceed to the next stage of the technological process, completing the full working cycle of washing, dewatering, and transportation.

Construction diagram

Case of equipment modernization at the tunnel excavation soil processing site in Shenzhen

I. Project Background

At the tunnel shield spoil processing site in Shenzhen, a traditional technological scheme was used at the initial stage of the project   belt feeder + vibrating screen   for washing sand and removing impurities to enable resource utilization of tunnel excavation waste and improve economic efficiency. This scheme functioned normally when processing dry loose materials, but encountered serious technical problems in actual production.

II. Key Problems

Complex material characteristics

Tunnel excavation soil has a complex composition with the following features:

High moisture content material is wet and viscous, moisture content reaches 20%-30%

Strong adhesion clay and sand are tightly bonded, difficult to separate

Many impurities mixed with construction debris, concrete blocks, wood, plastic, and other foreign objects

Uneven particle size ranging from fine clay to large stones with a wide particle size distribution

Frequent equipment failures

The traditional belt feeder showed serious unsuitability when processing tunnel excavation soil:

Frequent belt slippage

• Wet viscous material adhered to the belt surface, reducing friction
• Frequent slippage between the belt and drive drum, sharply reducing transportation efficiency
• Required stops for cleaning 2-3 times a day, seriously affecting production continuity

High frequency of belt breaks

• Sharp stones, rebar, and other foreign objects in the complex material easily scratched and punctured the belt
• Belt service life reduced from normal 6-12 months to 1-2 months
• Frequent belt replacements led to a sharp increase in maintenance costs, with annual replacement expenses exceeding 100,000 yuan

Low productivity

• Frequent maintenance stops resulted in effective working time of less than 60%
• Material accumulation, inability to maintain continuous stable feeding
• Overall productivity was only 50%-60% of the design capacity

III. Solution — Bucket Sand Washer

Considering the specific requirements for processing tunnel excavation soil, our company's engineering team developed a customized   solution for the client to replace with a bucket sand washer implementing a comprehensive upgrade of equipment characteristics.

Advantages of the equipment choice

Our company's bucket sand washer is specially designed for harsh operating conditions and has the following key advantages:

High adaptability

• Bucket design, independent of friction force, completely eliminates slippage issues
• Forced feeding, not afraid of materials with high moisture content and high viscosity
• Can process extremely wet materials with moisture content up to 35%

High reliability

• Solid steel buckets made of wear-resistant alloy steel (NM400)
• No belts or other quickly wearing parts, failure rate reduced by more than 85%
• Service life of 5-8 years, significantly reduced maintenance costs

High washing efficiency

• Buckets perform reciprocating motion in water, material is fully rolled and soaked
• Dual washing action with high-pressure water jets + mechanical stirring
• Complete separation of clay and sand, clay content in finished sand ≤2%

Continuous stable operation

• Continuous 24-hour operation, no frequent maintenance required
• Equipment utilization rate increased from 60% to over 95%
• Actual productivity reaches or even exceeds the design capacity

IV. Actual results after modernization

Comparative performance data

Economic efficiency analysis

Direct benefits

• Productivity growth by 70%, annual processing volume increased from 120,000 to 200,000 tons
• Annual maintenance savings of 100,000 yuan
• Reduction of equipment downtime losses, annual production increase of approximately 1.5 million yuan

Indirect benefits

• Improved quality of finished sand, market price increased by 15 yuan/ton
• Increased customer satisfaction, order growth by 30%
• Improved equipment stability, reduced management costs

Return on investment

• Investment in equipment modernization about 500,000 yuan
• Projected payback period:   6-8 months
• Average annual net profit growth:   more than 1.8 million yuan

V. Customer feedback

"After switching to the bucket sand washer, the stability of the production line operation has qualitatively changed. Previously, we struggled daily with belt slippage and breakage issues; now the equipment runs continuously for a month without stopping for maintenance. Productivity increased by 70%, failure frequency is almost zero — this investment was worth it! Thank you for your professional technical support!"

— Manager Li, site leader in Shenzhen

VI. Technical summary and dissemination value

Technical innovations

1. For the specific conditions of tunnel excavation soil, an innovative bucket forced feeding method was applied
2. Use of wear-resistant materials, significantly extending equipment service life
3. Integrated design implementing feeding, washing, and transportation functions

Industry significance

This case provides a successful example of resource recycling in challenging conditions such as tunnel excavation spoil and construction waste, demonstrating the importance   of targeted equipment selection   to improve productivity and economic efficiency. Currently, this solution is successfully replicated at several sites in Shenzhen, Guangzhou, Dongguan, and other cities.