Cross Belt Sampling Systems

McLanahan Cross Belt Sampling Systems

Representative Sampling Directly from Conveyor Belts

McLanahan Cross Belt Sampling Systems are designed to automatically collect representative samples from bulk material conveyed on a moving belt.

The system is suitable for applications where accurate sampling of a continuous material stream is required for quality control, process monitoring, laboratory analysis and production accounting.

A cross-belt sampler travels across the full width of the material burden on the conveyor, collecting an increment from the complete cross-section of the material stream. This helps minimize sampling bias that can occur when samples are collected from only one portion of the conveyor.

How Cross Belt Sampling Systems Work

The Cross Belt Sampler is installed above or around the conveyor belt at the selected sampling location.

During a sampling cycle, the sampler moves across the full width of the conveyor belt and collects a portion of the material.

After completing the sampling pass, the collected material is transferred to the sample handling system.

Depending on the application, the sample can then be:

Cross Belt Sampler → Sample Transfer → Secondary Sampling → Crushing → Sample Division → Final Sample

The exact configuration depends on the material characteristics, conveyor capacity, particle size and laboratory requirements.

Full-Stream Cross-Belt Sampling

One of the key advantages of cross-belt sampling is the ability to collect material across the complete width of the conveyor burden.

Material can segregate on a conveyor according to particle size, density and other physical characteristics.

Collecting material from only one location can therefore produce a sample that does not accurately represent the complete material stream.

By traversing across the conveyor, the Cross Belt Sampler can collect material from different portions of the burden and provide a more representative sample.

Representative Sampling

Representative sampling is critical when laboratory results are used to make decisions about the material being processed.

A properly designed Cross Belt Sampling System helps reduce sampling errors associated with:

Particle segregation
Variable particle size
Variable material density
Uneven material distribution
Changes in material composition
Manual sampling locations

The sampler should be designed according to recognized sampling principles and the specific characteristics of the material and process.

Sampling from a Moving Conveyor

Cross Belt Sampling Systems are designed to operate with the conveyor running.

This allows samples to be collected from a continuous production stream without requiring the conveyor to be stopped.

The sampling cycle can be initiated according to a predetermined schedule or sampling requirement.

Sampling frequency can be based on:

Time
Tonnage
Production quantity
Batch
Process conditions

Automated Sampling

The Cross Belt Sampling System can be integrated into the plant control system to automate the sampling process.

Automation reduces operator involvement and provides consistent sampling according to the selected sampling schedule.

Benefits of automated sampling include:

Consistent sampling frequency
Reduced manual intervention
Improved repeatability
Improved operator safety
Better process monitoring
Reduced sampling variability
Integration with plant control systems

Sample Handling and Preparation

The Cross Belt Sampler can form part of a complete automated sample preparation system.

After the primary sample is collected, additional equipment can be incorporated to prepare the material for laboratory analysis.

Depending on the application, the sample preparation system may include:

Secondary samplers
Crushers
Screens
Sample dividers
Collection containers
Conveyors
Dust-control equipment

The objective is to reduce the original bulk material stream to a manageable laboratory sample while maintaining representative material characteristics.

Primary and Secondary Sampling

The Cross Belt Sampler normally performs the primary sampling function by extracting an increment from the main conveyor stream.

Where a smaller laboratory sample is required, a secondary sampling stage can be incorporated.

The secondary sampler reduces the quantity of material while maintaining representative characteristics.

Multiple stages can be used when a large production stream must ultimately be reduced to a small laboratory sample.

Sample Crushing

Some applications require the primary or secondary sample to be reduced in particle size.

A crusher can be incorporated into the sample preparation circuit to reduce the material to the required size.

Sample crushing can make subsequent sample division more consistent and prepare the material for laboratory analysis.

Crusher selection depends on:

Maximum feed particle size
Material hardness
Material abrasiveness
Required product size
Sample capacity

Sample Division

After the material has been reduced in size, a Sample Divider can be used to produce smaller representative portions.

Proper sample division is important because the final laboratory sample must continue to represent the original material stream.

The sample divider can be selected according to the required sample mass, particle size and material characteristics.

Sampling Frequency and Increment Size

The required sampling frequency and increment size depend on the material and the purpose of sampling.

Important considerations include:

Conveyor capacity
Material variability
Particle size
Material density
Required analytical accuracy
Required final sample mass
Production rate
Laboratory requirements

A sampling program should be established to provide sufficient increments to represent the variability of the material over the required production period.

Applications

McLanahan Cross Belt Sampling Systems can be used for:

Mining
Mineral processing
Coal handling
Aggregates
Industrial minerals
Bulk material handling
Mineral laboratories
Quality control
Process monitoring
Production accounting
Metallurgical accounting
Material characterization
Continuous process sampling

Typical Materials

Cross Belt Sampling Systems can be configured for a wide range of bulk materials, including:

Ores
Coal
Aggregates
Sand
Minerals
Industrial minerals
Concentrates
Other bulk solid materials

The final system configuration depends on the material's physical and chemical characteristics.

Key Features & Benefits

Automated sampling from moving conveyor belts
Sampling across the conveyor material burden
Representative primary sampling
Reduced manual sampling requirements
Consistent sampling frequency
Improved sampling repeatability
Suitable for continuous production streams
Can be integrated with sample preparation equipment
Optional secondary sampling
Optional sample crushing
Optional sample division
Integration with plant control systems
Improved operator safety
Suitable for laboratory sample preparation
Configurable for different conveyor and material conditions

Factors Affecting Cross Belt Sampler Selection

The correct Cross Belt Sampling System depends on several process and material parameters, including:

Material type
Bulk density
Maximum particle size
Particle size distribution
Material moisture
Material hardness
Material abrasiveness
Conveyor belt width
Conveyor belt speed
Material burden depth
Conveyor capacity
Sampling frequency
Required sample mass
Required final sample size
Sampling location
Conveyor configuration
Available installation space

Designing the Right Cross Belt Sampling System

To properly design a Cross Belt Sampling System, the following information is typically required:

Material description
Bulk density
Capacity
Maximum particle size
Particle size distribution
Moisture content
Material hardness
Material abrasiveness
Conveyor belt width
Conveyor speed
Material burden depth
Sampling frequency
Required increment mass
Required final sample mass
Sampling location
Conveyor arrangement
Available installation space
Required level of automation
Laboratory requirements

Representative material testing may also be recommended where material characteristics are uncertain or where high sampling accuracy is required.