Bulk material handling equipment such as bucket elevators and belt conveyors transports material in and around processing and shipping facilities, lending automation and flexibility to industrial operations of all types.
While bulk material handling equipment design is relatively straightforward, a number of material- and facility-specific factors influence the unique design for each piece of handling equipment and must be carefully considered.
FEECO is a preferred provider of custom bulk material handling equipment. The following provides a guide on how material characteristics and facility considerations influence the design process to achieve optimized bulk solids handling.
Bulk Material Handling Equipment
Bulk material handling equipment comes in a range of types, sizes, and configurations. A summary of the standard pieces often found in a typical handling operation is provided here:
Bucket Elevators
Bucket elevators are chosen for high-capacity vertical handling applications ranging from light, fluffy materials to heavy aggregates.
Troughed Belt Conveyors
Troughed belt conveyors offer large handling capacities as a result of a troughed idler design. This type of belt conveyor is subsequently also better at keeping material contained on the belt. Numerous opportunities for belt conveyor customization are available.
It is common to equip belt conveyors with the following to improve flexibility of the unit:
Conveyor Belt Plow
Conveyor belt plows are added to troughed belt conveyors to increase the number of discharge points; the addition of a plow allows material to be discharged from either side of the belt at predetermined locations.
Conveyor Belt Tripper (Tripper Conveyor)
Similar to belt plows, conveyor belt trippers, also known as tripper conveyors, also increase the number of discharge points along the conveyor. The tripper can be used to discharge material from one or both sides of the conveyor, either at a fixed position, or as a traveling unit for layered stacking.
Belt Feeders
Belt feeders are frequently added to conveyors in order to meter stockpiled material into the conveyor system at a controlled feed rate.
Reversing Shuttle Conveyors
Reversing shuttle conveyors, or shuttle conveyors, are ideal conveying solutions for building in-line, continuous piles of material, or likewise, feeding multiple fixed discharge points. While they are similar to troughed belt conveyors, they differ in that they are fitted onto a track system, allowing material to be conveyed in either direction or discharged at either end of the conveyor.
Steep Incline & Incline Conveyors
Incline conveyors are troughed belt conveyors set at a fixed incline – up to 18°. Beyond 18°, inclined conveyors are considered steep incline conveyors and can convey material at up to 90° using corrugated sidewall or pocket belting to keep material contained. The use of alternative belting sometimes has these conveyors known as sidewall conveyors or pocket belt conveyors.
Material Characteristics that Influence Bulk Handling Equipment Design
Each type of bulk material handling equipment is best designed around the material to be handled for best results. A number of material characteristics influence equipment design parameters, from the drive assembly, to the materials of construction, and even the use of accessories.
Material characteristics that have an impact on equipment design include:
Bulk density
Bulk density is measured in lb/ft3 or kg/m3 and defines the weight of a material at a given volume. A material’s bulk density is primarily a concern in terms of the load the unit(s) will need to handle. Load subsequently plays into the sizing of bulk material handling equipment, as well as mechanical components such as the motor, drive system, and more.
Angle of Repose
A material’s angle of repose is the steepest angle at which it can be piled before it begins to slide against itself. Measured in degrees, the angle of repose influences how much material can be loaded into buckets or onto conveyors, which ultimately contributes to overall equipment sizing.
Moisture content
The moisture content of a material is measured as a percentage by weight. Since a material’s moisture content will determine how well it will feed and discharge between transfer points, it plays a crucial role in the materials of construction. Moisture content is also important to consider when working with a corrosive material, as some materials may become more corrosive as the moisture content increases, requiring further protections to equipment.
Particle Size Distribution
The particle size distribution of a given material plays a major role in several aspects of designing bulk material handling equipment. Not only does it factor into maximum allowable capacity and unit sizing, but it can also influence conveying speed, particularly when working with dusty materials. Similarly, it may require additional accessories such as dust pick-off points to manage fugitive dust.
Material Temperature
The temperature of the material being conveyed influences the materials of construction. This is especially true of conveyor belting and elevator buckets. A hot material may require a heat-resistant belting or material of construction, or a different blade selection for a belt plow.
Similarly, a cold material may require special belting to deal with condensation or protect against frozen material.
In the case of bucket elevators, the material temperature also influences the decision between a belt or chain configuration.
Material Fragility
While fragility doesn’t typically influence most handling equipment, it is a concern when working with bucket elevators, with ramifications on the chosen discharge style.
Materials that are prone to degradation or that cannot be aerated are best served by a continuous-style discharge elevator, as it offers more gentle handling, limiting the amount of degradation and attrition (the breakdown of particles into dust) that can occur. When fragility is not a concern, centrifugal-style bucket elevators are often preferred, as they allow higher capacities.
Special Requirements
Some materials may exhibit characteristics that can influence bulk material handling equipment design in less common ways. This might include a material that is prone to combustion, presents a toxicity concern, is highly abrasive or corrosive, or otherwise.
Depending on the specific requirements of the material, discharge behavior, materials of construction, and the need for additional accessories may be necessary. Fortunately, bulk material handling equipment is highly customizable and is easily tailored to meet these unique specifications.
Design Parameters/Facility Requirements that Affect Bulk Material Handling Equipment
In addition to the specific material characteristics that influence equipment design, various aspects of the facility and processing operation will impact equipment design as well:
Capacity
Meeting the desired capacity is the central focus of handling equipment and system design and serves as the primary consideration in sizing equipment.
Spatial Restrictions
When designing equipment for an existing facility (and even new facilities), spatial restrictions such as surrounding equipment and infrastructure will often require a little creative engineering on the part of the OEM. This might mean increasing belt speed to get a higher capacity from a smaller conveyor, using special high-capacity buckets on elevators, spacing buckets closer together, and more. However, the manufacturer should always stay within recommended guidelines and industry standards.
Equipment Height and Length
The required rise (height) and run (length) for conveyors, as well as discharge height for bucket elevators is defined at the outset of the project by the customer. While this, along with available support locations, conveyor spans, elevation above grade, and more, primarily influences the structural components, it could also guide decisions in equipment. For example, if a client has defined a rise and run that are too steep for an inclined troughed belt conveyor, a steep incline conveyor may be chosen instead.
Environmental Conditions
The environment in which the equipment will be operating is a critical aspect of design, especially when equipment will be operating outdoors. Factors such as ambient temperature, requirements for wind, snow, and ice loads, or even seismic loads will influence the conveyor’s truss design.
Material handling equipment operating outside in a coastal area may also require additional protection from corrosion due to the increased amount of salt it is likely to be exposed to.
Accessories
Bucket elevators, troughed belt conveyors, incline conveyors, and other material handling equipment are a highly specialized aspect of every processing facility. In addition to regular housekeeping and maintenance access, some requirements may call for additional features such as:
- Walkways
- Service platforms
- Stairs
- Supports
- Belt cleaners and scrapers
- Loading skirtboards
- Weather covers
- Transfer chutes
- Belt scales
- Safety cables and shut-offs
Instrumentation may also be desirable to improve site automation and control.
Conclusion
Bulk material handling equipment such as troughed belt conveyors and bucket elevators meet critical transport objectives both in and around industrial facilities. Their effectiveness is largely tied to the optimization of each piece of equipment to the specific characteristics of the material to be conveyed, as well as the many facility requirements, with factors such as material temperature, angle of repose, spatial restrictions, and more, playing a part in several aspects of the equipment design.
Industries working with everything from specialty chemicals to aggregates rely on FEECO custom material handling equipment for an optimized handling solution. Our Customer Service Team ensures that equipment continues to run as designed for years of reliable service. For more information on our custom bulk solids handling equipment, contact us today!