The Samson® Feeder has found an additional application as a Surface Storage Feeder (SSF), reducing the complexity and increasing the cost effectiveness of cement mill operations. Used in this manner, the feeder enhances flexibility in handling different materials and in adapting the plant layout to changing production demands.
Samson® Storage Feeder SSF from AUMUND functioning as storage buffer.
A fast reaction to changing demands and short-term fuel or raw material costs is a key factor in the profitability of plant operations in today’s cement industry. However, a production process involving deep pits, bunkers or bins requires the construction of large foundations, as well as a site where deep digging is possible. Relocating machinery quickly due to changing production processes or evolving market situations is not always possible, meaning that flexibility remains rather limited.
However, the cement industry does not always need the vast buffer storage provided by bunkers and bins. The storage capacity provided by a Surface Storage Feeder, such as the Samson® Feeder, has proven to be fully sufficient. The SSF is surface mounted without the need for special foundations and it can be relocated rather easily within the plant or even between sites, should the need arise. Furthermore, the SSF can handle materials of different consistency, from cohesive and sticky to abrasive and beyond. It can be supplied in virtually any size and length to build a buffer capacity based on a plant’s needs.
The SSF in operation
The SSF receives material directly from either rear tipping trucks or front-end loaders. The entry section provides a certain storage capacity within the unit itself for initial material reception with quick vehicle turnaround times, and the total amount of storage depends upon the application, material density, feed rate and size of the unit. The SSF keeps a constant level of material within its head chute to act as a surge bin, which is then extracted at either a constant or variable rate determined by the customer by means of a weigh feeder, weighing belt or a similar device.
Multiple Samson® Storage Feeders at Lehigh Cement.
A combination of several SSF units can be used when more than one material is to be added. The different materials can be metered at determined percentages based on the plant’s requirements. Enclosures on the SSF can also be included for handling dusty materials or those that need to be kept dry. The key element to the feeder’s flexibility and performance is that the material is stored horizontally. The material height cannot exceed the width, meaning that bridging is impossible. The feeder’s large width also means that a high storage capacity is possible. The conveying and discharge function is carried out at very low belt speed. This allows for a higher belt angle than would otherwise be considered, resulting in a compact elevation rise to permit weight feeder or conveyor belt loading.
Simplifying a complex plant design
The cement plant design for a raw mill feed incorporates an additive covered storage area, which frequently utilises front-end loaders to load multiple materials via a hopper and feeder. This feeder, whether apron or other type, feeds a long conveyor belt system with reversible belts or a multi-chute system to distribute the additive to 3 – 5 bins. Such a layout dictates that the additive storage area must be some distance from the feed bins to allow a 15° belt to convey material to the top of the raw mill feed bins. The various additives are then metered out of the feed or buffer bins. Depending upon the material properties these bins will have to be of special construction and inefficient storage shapes in an attempt to resolve anticipated flow problems. Often, expensive liners and special feeders, such as those of the rotary plough type, have to be used. If hard rock limestone or additives are required, apron feeders combined with belt weigh feeders may be needed. These metering devices and the assortment of feeders then finally feed onto the mill feed belt. All in all, this is a very complex and expensive installation. It requires a lot of maintenance and can cause mill downtime. Furthermore, if the plant wants or needs to use other raw material resources in future, significant modifications or feeding problems might occur.
Samson® Storage Feeder SSF at a Lafarge cement mill.
To avoid these complications, in an ideal plant layout, the additive storage building could now be placed next to the mill feed belt by using the Samson® Feeder as an SSF. The special bins, feeders, belt transfer and distribution systems are to be eliminated. The loader now feeds additives directly to the SSF units. A bank of 3 – 5 of those units can be arranged along the storage building, which would feed directly onto the mill feed belt via weigh belt feeders. Each feeder receives material by loader. In turn, the feeder maintains a level of material in the outlet chute, which feeds the weigh feeder. Due to the SSF’s wide profile of 10 ft, maintaining such a material level is not a problem. Even if the time between loading the unit creates gaps on the feeder, the constant material supply to the production process can be maintained by relying upon the buffer function of the SSF. Its variable speed maintains the needs of the weigh feeder and the weigh feeder meters the requirements of the raw meal mix and grinding process. In terms of operation and maintenance, the plant has only 3 – 4 SSF and belt feeders to deal with. All of these are located at ground level.
Examples of use
AUMUND provided two Samson® Feeder Systems to Lehigh Cement in Edmonton, Canada. The task was to feed synthetic gypsum into separate finish mill lines. The material is loaded into the Samson® feeders by front-end loaders. It is then fed directly onto the finish mill belt conveyor through a weigh feeder and a TKF chain conveyor.
AUMUND supplied one Samson® Feeder to the Lafarge cement mill in Whitehall, Pennsylvania, USA. In conjunction with a weigh feeder and a transfer conveyor belt, this feeds lime mud directly onto the finish mill belt. The material is fed into the Samson® Feeder via both rear tipping truck and front-end loader.
Beyond simplifying the material feeding process at cement plants, the use of the Samson® Feeder opens up many other new opportunities. This type of wide surface storage feeder can offer greater flexibility than conventional storage/feeder systems, with lower installed costs and less maintenance. Although not a new concept, equipment development and evolution may mean that now is the time for horizontal storage.
AUMUND SSF in operation at Lehigh-Edmont.
In the Americas, installation costs now account for a far greater percentage of the overall total cost of any industrial project. Equipment such as the SSF therefore provides an opportunity to reduce installed costs in some critical areas of a plant, while also offering some real operational benefits.
The Samson® Feeder used as a SSF provides an all-purpose solution for the reception of many types of bulk material cargoes transferred from the port to storage or production facilities by tipping truck or front-end loader. For new plant developments, the surface mounted SSF solution offers an economical and flexible alternative to conventional underground unloading systems, storage bins and feeders.
Written by Jason Birnbaum, AUMUND Corporation, USA. Adapted to World Cement's house style by Louise Fordham
Read the article online at: https://www.worldcement.com/product-news/22012015/samson-feeder-finds-new-application-153/