While bucket elevators are an effective and widely used means for conveying powders, they are not immune to the effects of material deposition. When powders and fines deposit onto an elevator’s drive pulleys and wheels, they may accumulate to an extent that compromises equipment performance and/or contaminates product. For this reason, it is important to consider the equipment designs and options available for addressing the build-up of powder and fines in bucket elevators when choosing this type of conveying equipment.
Causes of Powder and Fines Build-up in Bucket Elevators
Conveying powdered material through a bucket elevator can result in direct deposition of the powder onto drive assembly components, such as pulleys and wheels. Fine powders, and especially those which are prone to dusting, can be especially problematic in this regard. However, even products in non-powder form, such as pellets, prills, tablets, etc., can throw off fines as they move through the conveyor. These fines then deposit and accumulate on vital drive assembly components.
While dry powders can be especially problematic, powders with a low moisture content can also deposit and accumulate within a bucket elevator. For example, hydrated lime, a material with a low moisture content, is quite prone to depositing onto an elevator’s pulley rims, web facings, and shafts. In this case, the low moisture content of the material contributes to the propensity of the product to adhere onto the equipment parts and components, once deposited.
Consequences of Powder and Fines Build-Up
If left unchecked, the build-up of powder and fines on bucket elevator pulleys may cause equipment stoppages and unplanned downtime. This often occurs when material builds up on pulley rims to the extent that the drive belt either mistracks or becomes disengaged from the pulley. In either case, a maintenance intervention is required to restore the conveyor to normal functioning.
A more serious consequence is the potential for product contamination. Material adhering to a pulley, wheel, shaft, or mistracking belt can become dislodged and fall into the buckets moving through the conveyor. This problem is particularly acute in the “product zone” of the conveyor, where the conveyor buckets are being filled with fresh product from upstream processes.
Addressing the Build-Up of Powder and Fines in Bucket Elevators
At UniTrak, we recognize the importance of reducing or eliminating the build-up of powder and fines in the TipTrak™ bucket elevators we supply. We accomplish this via the following:
• TipTrak™ bucket elevators can be equipped with pulley scrapers and self-clearing drive wheels to address material buildup. These equipment options keep pulleys and drive wheels free from deposited material, reducing equipment downtime and the risk of product contamination.
• Bucket elevators which use metal roller chains and toothed drive wheels are especially prone to material build-up. These designs provide offer more places in which material can lodge and accumulate, and due to the nature of their designs, are much harder to keep clear of material accumulation. In contrast, the rubber beltchain and smooth pulleys of TipTrak™ conveyors avoid these problems, and permit the use of the cleaning options described above to prevent unwanted material accumulation.
• For applications where the risk of material build-up is high, we can offer TipTrak™ conveyors with a quadrant design which eliminates pulleys and shafts on which material can accumulate. This design option is preferred for applications where material deposition and accumulation is especially problematic and troublesome.
If you have an application where addressing the build-up of powder and fines in a bucket elevator is a primary concern, UniTrak can help. To find out more about the equipment solutions we can provide, please contact our sales department.