Selecting a Screw Conveyor for Effective Handling of Difficult Materials
A screw conveyor is a highly versatile and cost-effective mechanical conveyance used for handling dry bulk solids. With the ability to transfer materials horizontally, vertically, or at an incline, this conveyor provides enclosed transfer from one or more inlet points to one or more discharge points. Its wide range of configurations, components, and construction materials make it suitable for even the most challenging dry bulk materials.
A screw conveyor typically consists of a screw mounted in a U-shaped trough or tubular housing, with flighting mounted on a pipe. A rotating drive shaft connects one end of the screw, while an end shaft connects the other end. Bearings at the trough ends provide support for the screw, with additional hanger bearings suspended from the top for longer conveyors. Selecting the right screw conveyor for your material requires careful consideration of components and construction materials, in collaboration with your conveyor supplier’s engineering department. The screw conveyor’s versatility and cost-effectiveness make it an ideal choice for handling dry bulk solids.
With the ability to transfer materials in multiple directions and its wide range of configurations, components, and construction materials, it can handle even the most challenging dry bulk materials. Working together with your conveyor supplier’s engineering department, you can select the optimal screw conveyor for your specific material, taking into account key components and construction materials.
Materials that can be transformed into a fluid state.
When handling fluidizable materials, such as alumina, Portland cement, powdered cocoa, fly ash, limestone dust, and talc, it’s important to select a screw conveyor with a larger diameter and a short pitch. This will slow the material’s flow and prevent uncontrollable movement. For a downstream weighing device, a double-flight short-pitch screw with two rows of flighting can be used to control the material’s flow and ensure a more uniform discharge. Using a screw conveyor with a larger diameter and a short pitch when handling fluidizable materials, such as alumina, Portland cement, powdered cocoa, fly ash, limestone dust, and talc, can help slow the material’s flow and prevent uncontrollable movement. To ensure a more uniform discharge and control the flow, consider using a double-flight short-pitch screw with two rows of flighting.
The materials used in this product do not flow freely.
When handling materials that are non-free-flowing, such as viscous or sticky materials, matting or interlocking, and packing can be an issue. Choices like single-flight ribbon screws or shaftless screws can alleviate this problem by eliminating build-up on the screw surfaces and providing an open space between the flight and pipe. For materials like aluminum chips, mica flakes, dry bagasse, wood chips, and paper pulp, their irregular shapes can cause wedging and jamming in the conveyor, leading to increased horsepower and mechanical failure. Choosing a heavy-duty conveyor and feeding the material at a controlled rate can prevent this. For materials that tend to pack, like carbon black, hydrated lime, dried milk, talc, gypsum, and wood flour, selecting a conveyor with heavy-duty construction and components can handle the higher flow resistance. Additionally, using a single-cut-flight standard-pitch screw can break up compacted material, and using fluidizing pads or aeration devices can prevent packing of fine materials. Efficiently transport non-free-flowing materials without the hassle of build-up, jamming, or packing. Our conveyors are designed with heavy-duty components and a controlled feeding rate, perfect for handling irregular shapes such as aluminum chips, mica flakes, dry bagasse, wood chips, and paper pulp. For materials prone to compacting, like carbon black, hydrated lime, dried milk, talc, gypsum, and wood flour, our conveyors offer a solution with single-cut-flight standard-pitch screws and fluidizing pads or aeration devices. Our conveyors are built to prevent mechanical failure and minimize horsepower, making them the ideal choice for any industry expert.
The use of abrasive materials
The screw conveyor’s components can be quickly worn by abrasive materials like cement clinker, iron ore, foundry sand, whole soybeans, and titanium dioxide. If your material is abrasive, consider using a conveyor trough, screw, bearings, and other components made of abrasion-resistant materials, such as hardened or hard-surfaced steel. To reduce abrasive wear, it is recommended to convey your material at a nominal depth of approximately 15 percent of the conveyor’s total volume and operate the conveyor at a low speed. A great way to minimize wear and tear on your screw conveyor is to utilize abrasion-resistant materials for its components. Consider using hardened or hard-surfaced steel for the conveyor trough, screw, bearings, and other components. This will ensure longevity and efficiency, even when dealing with highly abrasive materials. Another helpful tip is to operate the conveyor at a low speed, along with maintaining a nominal depth of approximately 15 percent of the total volume to reduce abrasive wear.
Moisture-Absorbing Substances
For materials that easily absorb moisture, like salicylic acid, dried milk powder, soap granules, and salt, it’s important to select a screw conveyor that is both vapor and dust tight. This should include shaft seals and other seals to prevent moist air from coming into contact with the material. Alternatively, you can choose a single-flight ribbon screw or a shaftless screw to avoid material buildup. If your material is hot, such as a powder discharged from a dryer, it’s crucial to keep the screw conveyor warm to prevent condensation. This can be achieved by selecting a conveyor with a heat jacket, heat tracing, or insulation. In some cases, a purging system may also be necessary to continuously draw moisture away from the material. Rely on the expertise of our conveyor design to ensure efficient and effective material handling. Our carefully designed screw conveyors feature shaft seals and other seals to prevent moist air from coming into contact with the material, and offer options such as a heat jacket, heat tracing, or insulation to keep materials warm and prevent condensation. Trust us to provide a reliable solution for materials that easily absorb moisture, like salicylic acid, dried milk powder, soap granules, and salt.
The product contains hazardous and flammable substances
To avoid potential hazards, it is crucial to carefully select a screw conveyor for handling toxic and explosive materials. These include asbestos, arsenic, benzene hexachloride, caustic soda, lead oxide, calcium carbide, seeds and grains, flour, coal, potassium nitrate, sulfur, and tobacco. Look for a vapor- and dust-tight conveyor with tight shaft seals, a dust control system, and a large clearance between the flight-tip and trough to prevent sparks. Additionally, consider using non-sparking or dissimilar metals, or purging the conveyor with an inert gas for added safety. Keep your workplace safe by choosing a screw conveyor that can handle toxic and explosive materials like asbestos, arsenic, and coal. Look for a vapor- and dust-tight conveyor with tight shaft seals, a dust control system, and a large clearance between the flight-tip and trough for added safety. Consider using non-sparking or dissimilar metals, or purging the conveyor with an inert gas to minimize the risk of sparks.