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A common question for material handling systems with concrete and fly ash is: “How to minimize the amount of dust while maintaining plant productivity?” dust and debris in the cement industry.
Inhalation of cement dust is known to be associated with silicosis, a serious and sometimes fatal lung disease. 1 This is in addition to many other diseases caused by dust inhalation. The cleaner the environment of the enterprise, the better the health of employees is protected. With outdoor facilities, the ability to reduce dust emissions can reduce the negative impact on the health of residents in neighboring areas. It could also reduce common local complaints about soot and residue covering their homes. Also, don’t forget the importance of meeting OSHA silica standards. 2 Keeping silica within acceptable limits will help cement companies avoid heavy fines. Fewer airborne particles also prevent fires and dust explosions. The National Fire Protection Association has its own set of combustible dust standards. 3
Dust containment issues are particularly important in commercial, large buildings and transfer facilities. A large transfer volume of any material creates dust emission problems. Modern open belt conveyors create excessive dust or material spillage during loading or unloading.
Enclosed conveyor belts help minimize this effect by keeping product in a closed loading skirt system and trapping most of the material in the discharge area to avoid pooling in downstream equipment. It also prevents product loss as well as a ribbon scraper on the head to reduce transfer to the tail. Enclosed belt conveyors often also include self-cleaning liners and paddle wheels with flaps to better clean liners. Most enclosed belt conveyors use external bearings instead of internal bearings to help keep the product inside and extend the life of the bearings as well as some wear parts. In addition, enclosed belt conveyors are capable of moving large volumes of material, minimizing product transfer points and preventing unnecessary aeration. Setting the included hoist for continuous (gravity) discharge will also help prevent product aeration during unloading.
Many in the concrete industry are as concerned about product release from elevator legs as they are about conveyor belts. Unfortunately, it is impossible to have a machine that is 100% sealed and still have access to its parts for maintenance and repair. However, bucket elevators may include some features that can help control material. One is a lip or tight seal that protects the bearing and prevents product from leaking out of the boot and head. This is especially useful when working with thin materials. Continuous welding is also recommended for the design and manufacture of elevator heads and shoes to avoid material gaps through which fine material can escape. Gaskets between connection points and between loading and unloading chutes will prevent product loss. Finally, buckets help operators retrieve material and return it to the system.
Enclosed belt conveyors, in addition to dust collection and material retention, offer countless advantages over other belt conveyors. The design of the enclosed belt conveyor allows for more flexible system design as it can be horizontal or inclined and can have multiple loading and unloading points. Most enclosed belt conveyors are equipped with CEMA C6 idler rollers, allowing users to move a wider range of products, from light (concrete and ready mix) to very heavy (sand and gravel). In addition, CEMA C6 Idler Pulleys are standard off-the-shelf components available from various vendors. Enclosed belt conveyors also produce much less noise than other belt conveyors. The EBC has no exposed parts such as exposed conveyors and the exposed shafts are provided with the necessary guards to prevent trap points.
Sweet Manufacturing Company Enclosed Belt Conveyors are ideal for high volume commercial and industrial sectors as they can be serviced with minimal tools and do not require access. The solution was designed with the needs of operators and plant maintenance in mind. Spare parts are located outside the company’s closed conveyor belt. This design allows the user to service and replace the CEMA C6 Chute Idler and Return Rollers without removing the top or bottom panels or unwinding the belts. This significantly reduces the number of tools needed and downtime in the event of a breakdown. What’s more, it improves safety as maintenance crews can perform maintenance while standing on a platform or walkway instead of climbing inside the machine. In addition, the bearings are easily accessible from the outside of the enclosed conveyor belt for lubrication, removal or replacement without removing the belt.
The Sweet® Enclosed Belt Conveyor is constructed from 10 gauge steel and is heavy duty commercial grade equipment. Conveyors are made of American grade G140 galvanized steel to withstand not only harsh factory environments but also outdoor installations. G140 steel can withstand harsh working conditions, it can be especially useful for any facility near ports, salt and inclement weather. Hip roofs are used to further protect conveyors from rain and snow. Inside the conveyor, loading and unloading points are lined with polyurethane, anti-reflective, ceramic sheets or tiles to extend the life of the equipment. The EBC design also includes a heavy duty horizontal pulley on the chute or loading side of the conveyor. Heavy duty pulleys will allow the belt to withstand the heaviest loads, while thicker materials are stronger and therefore more durable.
The company’s enclosed conveyor belts feature built-in sensor ports that can be paired with multiple optional sensors that can be selected individually or integrated with the 4B Watchdog™ Super Elite Hazard Monitoring System. The system includes sensors for shaft speed, bearing temperature, plug groove and belt displacement sensors. The ability to monitor equipment health and performance is critical to ensure timely repair of certain components that can deteriorate over time. Sweet® elevators have similar hazard monitoring features. The company has several different models of elevators; The combination of an enclosed belt conveyor with suitable infeed and unloading equipment will make the operation smoother and safer.
Thus, the main advantages of closed conveyor belts in comparison with standard belt conveyors are in three aspects:
Thus, high volume concrete plants can benefit from the inclusion of enclosed belt conveyors in their systems.
Brandon Fultz is a Business Development Specialist at Sweet Manufacturing Company. He has 10 years of OEM experience in industrial applications.
In any belt conveyor system that transports bulk materials, the belt must move straight and realistically to maximize its life, minimize material release and safety hazards, and achieve high system efficiency.
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