Bulk Handling Global - Hopper discharge systems
Solutions to bulk solids and powder flow problems.
The handling of cohesive, high moisture, fibrous and flushing type products are common place in minerals processing, mining, food processing pharmaceutical and sewage plants. Unless silos and hoppers, dischargers / feeders and bulk handling equipment are designed correctly, it is not uncommon to find plant that is operating at de-rated design capacities, high in maintenance, and at times, the requirement to mothball a plant. These problems can be easily avoided.
Here are a few short videos (click on picture to start video) of difficult to manage bulk solids and powders. By avoiding compaction, and utilizing gravity effectively, mass flow discharge of commonly difficult to discharge products is easy and absolutely controllable.
Brown Coal 62% Moisture Content |
Granular Ammonium Sulphate |
Food Paste |
Filtercake - 47% Moisture content |
Feldspar - Fluid like when in motion |
Clay - Cohesive |
Cement |
In fact, there is no such thing as a difficult to handle product - only the way that bulk solids and powders are traditionally handled it makes it difficult. Having a real understanding of product pressure relations as well as accurately testing of bulk solids makes the handling difficult products easy.
By carrying out bulk solids and powder flow properties testing, we predict the flowability of a bulk solid or powder.
Once it has been established and we have measurable values that the product is either an ideal plastic, or very cohesive, we learn that the product is very pressure sensitive, will have a significant variation in bulk density depending on consolidation pressure, will have limitations as to how much head height the material can be stored under.
Controlled gravity discharge is paramount when discharging ideal plastic or cohesive bulk solids. Full control and seamless discharge can easily be achieved.
It is extremely important when discharging and conveying of these types of products that there is no compaction or vibration imparted to the product. If compaction occurs, then adhesion of the product to surfaces is inevitable, resulting in loss of volumetric capacity. It is usual to line sliding surfaces with a low friction liner, which can have the benefit of low adhesion under high consolidation loads.
Flushing type products have the tendency to entrap air. The surface product absorbs gas molecules – the smaller the particle size, the greater the surface area is resulting in greater gas absorption. When the gas absorption rate is high, the gas dominates friction values, and the product is considered practically frictionless, and has liquid like characteristics.
Products that are in a fluidised state can not be effectively controlled with devices such as belt or screw feeders for example.
The binding forces for a gas are not stable, and after a certain time in storage the gases are released, and the product regains mechanical characteristics including friction. These types of products require de-aeration time, and result in a silo that requires additional capacity.
Temperature and humidity have a big influence on these products, and usually require silos that condition the product and are insulated.
Depending on the handling system, process requirements may need to allow for a significant variation in bulk density of the product.
If you have a difficult to handle product, contact us and we will be happy demonstrate your product.
