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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.
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.
Bulk Handling Global - Product Treatment and Proportioning Silo systems
The Treatment Silo design is an ideal flow silo system, incorporating unique functions to accommodate free flowing and cohesive products. With complete flexibility, this system provides complete control of the product – fully controlled discharge rates; variable flow functions to suit changing product flow characteristics and instantaneous shut off. The requirement for downstream feeders is eliminated.
By electronic control through a PLC, the treatment silo design can alter the flow regime from the silo or hopper, to allow blending and proportioning of multiple products according to sequence/process requirements. Different velocities across the silo cross section can be achieved, also with controlled eccentric flow pattern – if required. These systems can be supplied for batch or continuous operations, and eliminate the need for high shear and high powered mixers or blenders.
The following flow regimes can easily be achieved for all bulk solids and powders:
Ideal Flow
Mass Flow
Eccentric Flow
Funnel Flow
The Proportioning Silo systems are suitable for the following applications:
Mixing of multiple products
Avoiding segregation
Avoiding agglomeration
Avoiding degradation
Avoiding caking of product
Cooling
Heating
Minimizing explosion hazards
Typical service applications:
- Avoiding degradation of active coal pellets in silo and, providing segregation in coal bunker storage facilities where the material is highly cohesive (brown or black coal).
- Avoiding agglomeration following production, example - ammonium nitrate and citric acid.
- Condition Soya Bean Meal in a free flowing state in the case of long storage in port storage facilities.
- Providing a minimum of difference in residence time in the case of cooling Plastic Pellets immediately after a pelletizer.
Bulk Handling Global - Product Treatment and Proportioning Silo systems
The Treatment Silo design is an ideal flow silo system, incorporating unique functions to accommodate free flowing and cohesive products. With complete flexibility, this system provides complete control of the product – fully controlled discharge rates; variable flow functions to suit changing product flow characteristics and instantaneous shut off. The requirement for downstream feeders is eliminated.
By electronic control through a PLC, the treatment silo design can alter the flow regime from the silo or hopper, to allow blending and proportioning of multiple products according to sequence/process requirements. Different velocities across the silo cross section can be achieved, also with controlled eccentric flow pattern – if required. These systems can be supplied for batch or continuous operations, and eliminate the need for high shear and high powered mixers or blenders.
The following flow regimes can easily be achieved for all bulk solids and powders:
Ideal Flow
Mass Flow
Eccentric Flow
Funnel Flow
The Proportioning Silo systems are suitable for the following applications:
Mixing of multiple products
Avoiding segregation
Avoiding agglomeration
Avoiding degradation
Avoiding caking of product
Cooling
Heating
Minimizing explosion hazards
Typical service applications:
- Avoiding degradation of active coal pellets in silo and, providing segregation in coal bunker storage facilities where the material is highly cohesive (brown or black coal).
- Avoiding agglomeration following production, example - ammonium nitrate and citric acid.
- Condition Soya Bean Meal in a free flowing state in the case of long storage in port storage facilities.
- Providing a minimum of difference in residence time in the case of cooling Plastic Pellets immediately after a pelletizer.
Bulk Handling Global - Silo Blending / Mixing systems
Industry typically uses high energy mixers / blenders to mix products. These mixers require feed of product at a controlled rate. So in addition to the requirement of using a mixer, associated feeders, additional silos, conveying and elevating equipment, controls and switchgear, access ways and maintenance are required. These systems tend to be high in capital costs, and maintenance intensive. A simpler and cost effective alternative is to use the silo as a blending system it self. The design can allow for either continuous or batch blending systems.
The Silo Blending / Mixing systems provide an unprecedented technique of blending or mixing products. It combines high quality of blending / mixing that eliminates heat development, degradation of product/s, and eliminates wear and reduces energy requirements. These are the most important advantages of this mixing system over high shear and high energy mixers.
Short blending or mixing time is guaranteed. Typically, most products require one cycle for equalizing and two cycles for mixing.
Very intensive mixing is achieved by incorporating the Siletta® Discharger to control the product flow pattern in a predetermined sequence.
The Universal blender/mixer systems can be used as continuous or batch modes.
There are no mechanical components in the system i.e. no ploughs, paddles or ribbons. The issues of wear, maintenance and possible product contamination are eliminated.
In the case where products have to be wetted before discharge, the addition of spray systems can be incorporated at the final discharge. This system for example replaces the use of pug mills that tend to be high in wear and maintenance.
Service applications for Universal Blender / Mixing systems:
Eliminates the requirement for multiple silos and complete conveying and feeder systems
Mobile batch plant
Proportioning and micro additives
Laboratory mixing
Blending of products from 10 Liters to 500m3. Mobile units up to 2.0m3.
Where high accuracy of mixing is required
