Bucket elevators are essential for handling potash at various stages of processing, storage, and distribution. From mining and ore processing to fertilizer production and loadout, these elevators efficiently transport potash in both raw and processed forms. However, the unique characteristics of potash—namely its hygroscopic and corrosive nature—pose significant design challenges that must be addressed to ensure reliable operation. This article explores the key applications of bucket elevators in potash handling, essential design considerations, and strategies for preventing corrosion and maintaining system longevity.
Applications for Bucket Elevators in Potash Handling
Bucket elevators are found throughout the potash processing lifecycle, vertically conveying material in a range of settings. From initial mining through to load out, potash is transported via bucket elevator several times:
During Mining and Ore Processing
- Transporting crushed potash ore
- Carrying potash between process equipment
- Reclaiming stockpiled crushed ore
At the Fertilizer Production Plant
- Moving potash between granulators, screening equipment, glazing, and dryers
- Conveying off-spec material between the process and recycle circuits
During Storage & Loadout
- Filling silos, bins, and bunkers
- Reclaiming stored material
- Loading railcars, trucks, and ships
At Blending Plants
- Transporting potash between blending and mixing equipment
- Feeding packaging lines
While the role bucket elevators can play varies significantly, the challenges associated with handling potash in nearly any form are the same.
Potash Bucket Elevator Design
Bucket elevators are versatile in design and can be customized to suit a range of applications. The high tonnages associated with handling potash requires an especially robust solution, with most potash elevators following a few standard design decisions:
Continuous Configuration
Continuous-style elevators are preferred for their seamless, gentle handling, which is critical in maintaining potash integrity.
Super Capacity
Super-capacity elevators are designated as any continuous dual-chain elevator beyond 100 TPH. These elevators are reserved for the highest-capacity applications and are therefore widely used in potash settings.
Chain
Continuous elevators handling greater than 100 TPH utilize two strands of chain, as single chain and belts are not an option with continuous elevators beyond this capacity.
Historically, chain guides were employed to prevent the chain from swaying, allowing buckets to contact the casing. And while chain guides are still an option, better tolerances in chain manufacturing tend to limit sway. Additional casing width can also be used to ensure proper clearance.
Gravity Take-up
While a screw take-up may be an option with smaller elevators, gravity-style take-ups (GTUs) are the only option for super-capacity chain elevators. A screw take-up would be insufficient for properly managing tension, given the extreme forces present.
Further, in contrast to the rigid fixed placement of a screw take-up, a GTU allows the boot shaft to float, which reduces the potential for catastrophic failure of chains, shafts, bearings, and other mechanical components.
Gravity-style take-up on a super-capacity potash elevator
Super-Capacity Buckets
While those working with lower-tonnage elevators have a few bucket style options at their disposal, super-capacity elevators have a single standard for bucket style, referred to as super-capacity buckets.
Super-capacity buckets are specially designed for maximum handling capacity in continuous-style applications where the back surface of the leading bucket provides a sliding surface for the material discharging from the trailing bucket. This allows for a continuous discharge of material from bucket to elevator discharge spout.
Shaft-Mounted Drive Assembly
Gone are the days of in-line foot-mounted motors and reducers, which were connected to the head shaft with low-speed chains. Today’s bucket elevators utilize a shaft-mounted torque arm style reducer. This can be mounted to the head shaft with rigid couplings or shrink fit into the hollow bore of the reducer. To save valuable space, motors can be mounted directly over the reducer and connected with high-speed V-belts, or mounted at a right angle and directly coupled.
Access & Inspection Doors
Access doors can be vital in the event that the elevator is not running properly or is experiencing issues. Available in several sizes and configurations, including hinged, bolted, and lift boom style, these doors provide an essential access point for troubleshooting and repairs.
Inspection doors, used exclusively for visual observation, are available in a range of sizes, up to 24” x 24”.
Depending on the surrounding infrastructure and specific operational concerns, additional safety measures and accessibility options may also be included, such as the incorporation of ladders and service platforms, as well as various types of sensors and instrumentation.
Self-Supporting
Depending on available structural steel, the elevator may or may not be self-supporting. Outdoor applications where structural steel is not present often utilize the self-supporting design to avoid the added cost of incorporating structural steel.
If the elevator is self-supporting, the build will also need to be more robust. This typically includes the use of heavy duty structural steel angle iron and horizontal crimp stiffeners on the casing.
Heavy-duty angle iron is used to reinforce the casing on this self-supporting bucket elevator
Specially designed head section for a self-supporting elevator
Preventing Corrosion in Potash Bucket Elevators
Corrosion is the primary concern that must be considered during the initial design stages. Potash’s risk for corrosion is two-fold; in addition to generally being corrosive, potash is also hygroscopic, meaning it absorbs moisture from its surrounding environment. This is especially problematic because potash becomes increasingly corrosive the higher its moisture content.
This also means that where a bucket elevator is situated in the overall process can influence its design, as moisture levels change throughout the potash production cycle. For example, a bucket elevator feeding wet potash to a dryer will require more corrosion-protection measures than an elevator carrying product away from the dryer.
Thus, bucket elevator manufacturers must take measures to minimize both protection against corrosion and the opportunity for potash to absorb moisture from the surrounding environment. This is primarily addressed through selecting proper materials of construction and fabrication techniques.
Construction Materials & Fabrication Techniques
While elevators can be constructed from carbon steel, this material is susceptible to corrosion. As such, carbon steel elevators often receive an additional surface treatment or paint system for enhanced protection. While FEECO employs a single-coat epoxy for most elevator applications, we utilize a three-coat epoxy or polyurethane treatment when the elevator will be handling potash.
Additionally, handling hot material may cause condensation to form on the elevator casing. Since condensation can expedite the corrosion process, it may be beneficial to apply an external insulation. This can be a foam, fiberglass, or even a paint-like system up to 20 mils thick applied to the elevator casing. External insulation can also protect personnel from hot touch points.
Internal seal welding can also be incorporated to fight against corrosion by preventing material from becoming trapped between casing plates and structural angle iron. This consists of four vertical welds at each casing corner.
Manufacturers may also employ different grades of stainless steel such as 304L or 316L as an alternative to carbon steel in elevator construction.
Case Study
A global mining industry leader selected FEECO International to engineer and manufacture fourteen (14) bucket elevators for what is set to become one of the world’s largest potash mines. As a trusted provider of custom potash processing and handling equipment—and one of the only OEMs capable of supplying extremely large, super-capacity elevators—FEECO was uniquely positioned to meet the mine’s demanding requirements.
Challenge
Developing a world-class potash mine requires robust material handling infrastructure capable of supporting high-throughput production while ensuring operational efficiency and reliability. The client needed bucket elevators that could:
- Handle high capacities, ranging from 270 MTPH to 572 MTPH
- Operate in a demanding mining environment with mine-duty construction
- Support process efficiency in a compaction plant where granular potash would be vertically conveyed between processing stages
- Meet stringent safety and maintenance standards
- Integrate with state-of-the-art process controls and equipment condition monitoring
Given the scale of the operation—projected to produce 8.5 million tons per year (Mtpa) of potash for global agricultural markets—reliability and longevity were critical design considerations.
Solution
FEECO designed and manufactured fourteen custom-engineered bucket elevators, each built for the rigorous demands of potash handling. These elevators incorporated:
- Mine-duty construction for long-term durability in a high-wear environment
- Safety-first design to facilitate ease of maintenance and reduce downtime
- Integration with advanced process controls to enhance automation and operational monitoring
Each elevator was manufactured to FEECO’s stringent quality standards, ensuring optimal performance and minimal maintenance requirements.
Results
Following the success of the first fourteen bucket elevators, the client placed an additional order for eighteen (18) more elevators of the same design, further solidifying FEECO’s role as a key partner in the project.
Once fully commissioned, the mine is expected to play a crucial role in supporting global food security by supplying high-quality potash to agricultural markets worldwide.
Conclusion
Bucket elevators are an indispensable part of potash handling, facilitating the efficient movement of material from mining through processing, storage, and distribution. However, designing bucket elevators for potash applications requires careful consideration of the material’s unique properties, particularly its hygroscopic and corrosive nature.
By addressing these challenges at the design stage, bucket elevator manufacturers can provide durable, high-performance conveying solutions that optimize efficiency and reduce downtime in potash processing facilities. Investing in well-designed bucket elevators not only enhances material flow but also extends equipment lifespan, ultimately improving the overall profitability of potash operations.
The potash industry relies on FEECO for the best in custom bucket elevators and service support. For more information on our potash bucket elevators, contact us today!