Dependable handling and storage solutions...
By Barry Woodbine, AUMUND Group
The AUMUND Group with its headquarters in Rheinberg Germany have established an enviable reputation for state-of-the-art materials handling solutions with equipment delivered to over 100 countries. Even in the very difficult financial climate of recent years AUMUND, including their German subsidiary Schade Lagertechnik, have forged ahead improving their client service and support by opening new sales operations in Russia and Dubai (serving the MENA region generally) in addition to their existing facilities in China, India, France, USA, Brazil and through their subsidiary B&W Mechanical Handling of the UK.
As regards recent plant completions: starting at the quarry AUMUND have delivered examples of their heaviest apron plate feeder type BPB-SF for recent projects in locations as diverse as Austria (Lafarge Perlmooser AG, Retznei) and Venezuala at the Holcim San Sebastian plant and there are many other examples of the BPB range in other locations worldwide. The BPB series machines are used universally for raw material feeding in many other industries including, for example, a recent new contract handling Iron Ore in Mauritania, West Africa. The SNIM organisation (Société Nationale Industrielle et Minière) is the 7th largest iron exporter in the world and is presently upgrading its preparation plant and handling systems. As part of this development AUMUND will supply a pair of heavy Apron Feeders to extract ore from a buffer hopper located between the stockyard and the ship loading systems. Each feeder, type BPB-SF, is 6 metres in length with a pan width of 2,600 mm. and each has a design output capacity of 6,000 tons per hour extracting from a common bunker. Using the bunker capacity as a buffer the feeders may be stopped for a short time period to allow the ship loader to be moved between holds without stopping the stockyard equipment.
This is an excellent example of the diversification of the AUMUND Group into the Mining and Minerals sector with a new division, based in Rheinberg, responsible for this market. Clearly mining and quarrying are inextricably linked to the cement industry and experience in both sectors extends the knowledge base for the benefit of all...
In North Africa, AUMUND have recently delivered multiple units of their type DPB-K Weigh Feeder to ERCE SpA (Cimenterie d'Ain Touta) in Algeria. Based on the deep drawn pan design of the type KZB clinker transport, for which AUMUND and justly famous, the weigh feeder incorporates a weigh rail with load cells to measure the mass per unit length of the conveyor and thus with the chain speed the output rate may be computed and with a variable frequency drive (FVD) the system set up for blending to a common conveying system.
In this particular application Gypsum, Limestone, Pozzolana and Slag will be handled at varying dose rates to suit the process demands. Whilst the DPB-K is based on the overlapping pan design of the KZB there are alternatives based on the Arched Plate design of plate feeder which presents a smooth surface to the material allowing the pans to be easily cleaned when handling cohesive materials such as clay.
Remaining in Algeria AUMUND France have delivered four elevators of the type BWZ central chain design to NUH Cement but there are many other examples worldwide in Brazil, Bangladesh, Kingdom of Saudi Arabia, India, Russia and many more handling limestone and other coarse additions material plus hot clinker on the other side of the kiln line as part of the clinker transport...
The elevator may be combined with other plant as a system for the import of cold clinker. For example AUMUND is delivering a combination of the SamsonTM Surface Feeder and a type BWZ Central Chain vertical Bucket Elevator plus type TKF drag chain conveyor to Eurocement in Russia for their Maltsovsky Portlandcement plant at Briansk. This new installation intakes imported cement clinker into a SamsonTM 1600 Series feeder which provides a controlled discharge rate at 200 tons per hour to the vertical elevator which discharges to a silo via the type TKF drag chain. Combining a SamsonTM Surface Feeder with a Vertical Elevator eliminates the need for expensive deep pits and hoppers and offers the minimum plant footprint for a compact installation. Being surface mounted the SamsonTM concept minimises the material free fall and thus dust generation is almost eliminated at source reducing the need for expensive and energy intensive dust control equipment.
This solution of combining feeder and elevator is particularly interesting at Grinding Plant where the compact arrangement is a major benefit by reducing the required ground space. Often grinding plant may be located close to ports where deep excavations are costly to keep out the ground water and land is expensive.
Closer to home at Dyckerhoff AG, Plant Amöneburg in Germany two units of the type BWZ elevator is also found handling Granulated Blast Furnace Slag... Also on the fuel side the BWZ elevator has recently found favour handling Pet-Coke in Brazil at Votorantim Cimentos, Fábrica Primavera with four units delivered to this one plant. However, in the energy market today we have to consider many Alternative Fuels such as Tyre-Chip and other Waste materials plus Biomass Fuels such as Wood Chip where the BWZ elevators have also found a niche market with recent deliveries to Malaysia and Russia particularly.
The general move towards the Mega Cement plant concept, started with the Holcim Ste. Genevieve project where AUMUND supplied all of the core elevators and clinker transport systems, but now moving on with recent orders placed for the raw meal elevation for new plants at Tongling on the Yangtze, Cong Thanh Cement in Vietnam plus several in the MENA region now operating at 10,000 tons per day plus.
To reflect the demands of such mega projects AUMUND have extended the design envelope of their long established type BWG Belt-Bucket elevator to a maximum lift of 175 metres and a maximum handling rate of over 1,850 m3 per hour with a 2,000 mm wide bucket running at a belt speed of only 1.9 metres per second. A number of units are already delivered with lift heights to over 140 metres and two units already operating at a handling rate of 1,350 tons per hour with larger machines in progress. Clearly the raw meal elevation is a mission critical part of the process and the kiln performance is directly linked to the durability of this equipment. The economies of scale obtainable from these mega plants can only be realised if the critical machinery around the kiln remains reliable operating 24/7, it is in this environment dependable solutions are paramount.
After the clinker cooler AUMUND are famous for their extensive range of chain based Pan Conveyors able to handle materials temperatures up to 700 degrees with a maximum handling rate of 1,300 m3 per hour continuously with a pan width of 2,400 mm. running at 0.35 metres per second. It is in these conveyors we see the incremental improvements that deliver both extended performance and enhanced durability, in particular the recent application of new chain technology based on laser profiling has extended the chain rupture strength to 2 X 3,000 kN.. Using these high strength chains with the type KZB-Q design (including internal baffles for steep angle conveying) has enable AUMUND to achieve a single lift height of 78 metres at 45 degrees elevation. With the type BZB Bucket Conveyor using the same conveyor chain type this is extended to 90 metres at 60 degrees elevation. These high performance chains often enable a direct lift from cooler to clinker silo inlet eliminating the need to split the lift using an intermediate transfer tower.
Steel chain pan conveyors are practically impervious to a kiln flush, that is where accumulated material breaks clear and flushes through the kiln causing an instantaneous overload at the cooler thus spilling very hot clinker onto the on-going conveyors. Whilst this is clearly not a regular occurrence it is a certainty that at some point it will happen, in fact one UK plant reported 3 flushes in a single year and paid a dear price in fines for the associated pollution.
For the first so called mega plant, Holcim Ste. Genevieve, AUMUND installed four pan conveyors extracting material from a pair of large concrete silos via standard AUMUND clinker discharge gates. Each pan conveyor delivers to a dedicated vertical cement mill directly. No mill bunkers are included or required since the pan conveyors are fitted with VFD controllers such that the extraction rate from the silo may be set for each mill independently and therefore each pan conveyor also acts both as a feeder and extractor. To monitor the handling rate close to the clinker silo outlet each of the four pan conveyors is fitted with a weigh rail mounted to load cells.
Gypsum, either natural or synthetic, is added at low level metered directly on the pan conveyors before they rise up to the mill inlet using a combination of weigh belt feeders and four CentrexTM silo extractors. By mounting the gypsum silos at low level there is no need to elevate these materials the height normally required for the mill bunkers saving on costs in this area also.
Schade Lagertechnik (AUMUND Group since 2001) have also benefited from the AUMUND international sales and service setup in particular with the buoyancy of the Brazilian market with important new orders this year (2011) from Votorantim, Cimento Itambe and Cimento Apodi covering both Bridge and Cantilevered boom reclaimers. The Bridge Reclaimers are handling Limestone with a maximum reclaim rate of 1,200 tons per hour and are used both for reclaim from storage and for blending to achieve a homogeneous output of varying materials grades delivered to the raw meal system for grinding and finally blending before injecting to the kiln pre-heater via AUMUND vertical bucket elevators.
In conclusion, these are difficult times but AUMUND have continued to deliver world class engineering standards and thereby expand their market penetration worldwide through their dedicated sales and service outlets strategically located bringing dependable support to a local level.