The Automatic CHUTE SAMPLER – Free-Fall Discharge Model is a heavy-duty mechanical sampling unit engineered for the extraction of representative increments at gravity discharge points of dry bulk mineral materials. Typical installation locations include conveyor belt head discharges, transfer chutes, and inter-equipment transfer points.
The operating principle is based on full cross-sectional, equi-probable interception of the free-falling material stream, ensuring unbiased sample extraction without particle size segregation bias or velocity discrimination effects.
1. Operating Principle
The system incorporates a straight-path transverse cutter mechanism that traverses the entire free-falling material stream at a constant and controlled velocity.
During each cutting cycle:
- The full cross-section of the falling stream is intercepted.
- A representative primary increment is extracted.
- The increment is conveyed to the sample discharge chute for subsequent reduction or storage.
- The rejected stream continues its natural trajectory without interference.
The cutting frequency is programmable via PLC and supports sampling modes based on:
• Time intervals
• Tonnage (integrated with belt scale systems)
• External signal from the plant control system
2. Main Components
- Cutter Mechanism
- Cutter scoop fabricated in AISI 304 or AISI 316 stainless steel
- Replaceable reversible anti-wear cutting edges
- Anti-backflow load control geometry
- Dynamic counterweight system for mechanical stability
- Controlled cutter velocity to prevent fine particle loss
- Traversing System
- Cutter carriage driven by industrial-grade roller chain
- Dual heavy-duty linear guide assemblies mounted on sealed bearings
- Six high-strength spherical bearing wheels
- Guided travel path to eliminate vibration and oscillation during traversal
- Drive System
- Three-phase gearmotor rated at 3 HP (or as per design requirements)
- Integrated electromagnetic brake
- Mining-grade IP-rated enclosure protection
- Fully enclosed transmission system with mechanical guarding
- Main Housing / Structural Frame
- Fabricated from ASTM A36 structural steel
- Flanged sectional design for maintenance accessibility
- Inspection windows
- Optional internal lining in UHMW polyethylene or anti-abrasive rubber
- External discharge chute
- Instrumentation and Control
- Inductive position sensors
- Flow presence sensors
- Zero-speed switch
- Integration with IP66 / NEMA 4 control panel
- PLC-based control system with RS-232 / RS-485 or Profibus communication
- Local and remote alarm capability
3. Key Technical Features
- Extra-Heavy-Duty design for continuous mining operation
- Full transverse stream interception compliant with representative sampling principles
- Elimination of extraction and delimitation errors
- Stable cutter trajectory without oscillation
- Optimized counterbalance resulting in low energy consumption
- Easy inspection and preventive maintenance access
- Operational safety via interlocks and protective systems
- Average service life ≥ 8 years (excluding wear components)
4. Regulatory Compliance and Theoretical Basis
The CHUTE SAMPLER design is based on:
- Pierre Gy’s Theory of Sampling (TOS)
- ASTM D2234 – Collection of Gross Samples of Coal
- ASTM D2013 – Sample Preparation of Coal
- CODELCO CNAM 007 criteria
- International best practices for bulk material sampling
The system operates under equi-probabilistic sampling criteria, significantly reducing Total Sampling Error (TSE) and contributing to improved metallurgical accounting accuracy.
5. Typical Applications
- ROM ore sampling
- Primary screen discharge sampling
- Conveyor transfer point sampling
- Crusher feed control sampling
- Dry concentrate discharge sampling
- Metallurgical and commercial control systems
6. Benefits for Metallurgical Accounting
The Free-Fall CHUTE SAMPLER model:
- Ensures statistically representative sampling
- Reduces deviations in metallurgical balances
- Improves reliability in commercial settlement calculations
- Allows integration with automatic secondary sample reduction systems
- Minimizes manual handling and human intervention
7. Safety and Protection Systems
- Emergency stop pushbutton
- Anti-plugging protection
- Safety interlock on inspection window opening
- Alarms for power failure or absence of material flow
- Fully guarded drive system
8. Integration Options
The system may be integrated with:
- Jaw crusher systems
- Belt feeder systems
- Secondary rotary sample dividers
- Plant-wide SCADA systems
