A Revolution in Bulk Materials Handling
Author: Robert Johansson
Scaniainventor Conveyor Sicon AB
Scaniainventor Conveyor Sicon AR has created a belt conveyor which is a true revolution in bulk conveying. The technique is different to any other system available but at the same time it is simple, robust and flexible. And, most important, it offers totally enclosed handling in a belt conveyor which can run round sharp corners.
The first commercial installation
The Swedish cement producer, Cementa AB, was the first ever to install a SICQN belt conveyor. It was installed at their main production plant at Slite, Sweden.
The new conveyor, which replaced a series of conventional belt conveyors, has effectively eliminated the inherent draw-backs and limitations of the old belt conveyor technique.
The SICON system could offer the following unique features:
- The conveyor belt (also the return part) is totally enclosed; no spillage, no dust.
- The conveyor runs at steep angles and through 90 bends at a radius of 0.75 meter. Therefore, one single belt can handle the total transport with no need. to transfer from one belt to another.
- It is driven by three separate drive units along the length of the conveyor, thus minimizing the belt tension.
- It requires less space than conventional belt conveyors.
Cementa uses the SICON belt to transport sand and limestone from the stockpile up to the buffer hoppers at the mill. Two feeder conveyors from under the stockpile load the material into the SICON belt which at the other end discharges onto a distributing conveyor above the buffer hoppers.
Earlier, the same transport was handled by four conventional belt conveyors connected via transfer chutes. The new SICON belt takes the material all the way without any transfers and the related dust and spillage.
The SICON delivery included the 250 m long belt conveyor with loading and discharge equipment, belt tensioner, idlers, pulleys, brackets and three drive units. It further included a 60 m long covered gallery as well as the engilleering and supervision of erection.
The order was placed in August 1987 and the installation was commissioned in April 1988.
Conventional belt conveyor technique
For many years, the conventional belt conveyor technique has been the subject of intensive product development. Designers and operators have sought solutions that would help to overcome some of the most important constraints imposed by the belt conveyor, e.g.:
- Endless efforts have been spent on developing various systems for belt cleaning. In spite of all these efforts, most operators will agree that there is no equipment available today which is maintenance-free, reliable and which does not create other problems such as increased belt wear. Environmentally, belt conveyors are still considered a nuisance because of spillage and pollution, particulary at the transfer points.
- The restricted inclination of belt conveyors have called for improvements such as rubber cleats vulcanized to tha belt. This in turn has further emphasized the problem of belt cleaning.
- Different designs of covered belt conveyors have contributed to a reduction in dust pollution but offer no solution to spillage at the transfer points or from the return part.
- Several solutions have been developed to allow belt conveyors to run in curves. Also here, the systems are expensive, complicated and still only allow curves with very large radii.
The common conveying element which has been the subject for all the above development and improvement is still the old conventional flat conveyor belt, used in various forms of troughed or tubular sections.
To overcome these fundamental problems there was a need for innovative thinking which was not constrained by the present technique, in particular with regard to the design of the belt.
The SICON conveying system
The unique part of the SICON system. is the conveyor belt itself. Although it is unique in its design, it still provides the same functions as a conventional conveyor belt.
The three basic functions are:
- To support the cargo
- To provide a track for the idlers and pulleys
- To take up the tension from the drive machinery
Whereas a conventional conveyor belt has a uniform construction aver the whole width of the belt, the SICON belt is designed with the aim of optimizing each of the above functions.
The result is a belt where the track for the idlers and the longitudinal reinforcenCents are concentrated to the edges of the belt and the intermediate part of the belt has only one function, that of supporting the cargo.
This arrangement makes it possible to design a conveyor system with some exceptional features.
A cross-section of the SICON conveyor shows the two profiles vulcanized to the load-carrying belting. The profiles serve as tracks for the angled support roller and vertical gt.iide roller and, with steel cord reinforcing, they absorb the tension of the conveyor drive system. The pear-shape belt is manufactured from a quality of rubber with very flexible, elastic and wear resistant properties. This makes it capable of negotiating very sharp corners.
Also the return part of the conveyor is enclosed in the same manner. The result is a totally enclosed conveyor which transports bulk materials from the loading point to the discharge point, without transfers, spillage and pollution.
The environmental advantages when handling dusty, even dangerous materials, are quite obvious but it also leads to direct savings in reduced maintenance and cleaning, caused by dust and spillage.
Ability to negotiate sharp corners
Thanks to its unique design, the SICQN conveyor can negotiate very sharp corners. The minimum radius of the deflection sheaves depends on the size of the belt. See table 1.
Data Sicon 100 Sicon 1000 Handling rate m3/hour 10-100 100-650 Belt speed m/sec 1-5 2-5 Min. curve radius m 0,4 0,75 Max. lump size mm 40 70
Steep inclination and two-way conveying
The SICON conveyor can run in a steep inclination (max. 20~35e depending on the transported material) and the return part does not have to follow the load route but can be arranged in a loop. It is also possible to transport material on the return part simultaneously, thus making it a true two-way conveyor.
Multiple drive units - low belt tension
With the SICON conveyor it is possible to install multiple drives. This will reduce the maximum belt tension for long conveyors.
The energy consumption is the same as for conventional belt conveyors, thus considerably lower than for screw or chain conveyors and a fraction of corresponding pneumatic conveyors. Drive Units can be fitted at any curve where the belt wrapping is minimum 90 Figure 4.
Smooth loading and acceleration even at high belt speed
Loading of the belt can take place anywhere along the conveyor. In order to ensure an even flow of material it is recommended to use either a vibrating feeder, screw feeder, chain conveyor or similar.
At the loading stations, the conveyor belt is opened into a U-shape with sufficient opening for a loading chute.
As all the belt tension is taken up by the two reinforced profiles, the payload-carrying belting is completely slack and can therefore, in the best possible way, absorb the impact of the loaded material. The result is a very efficient and quick acceleration of the material, even at comparatively high belt speeds.
Multiple discharge methods
The belt opens out by a gradual transition from its pear-shape into a flat, vertical orientation. After discharge, the return part again closes to its original shape.
Here the belt opens out into a horizontal orientation (similar to conventional belt conveyors) . On the return run, the belt closes with the dirty side inwards before twisting back to its normal position.
Any spillage from the discharge/transfer station is gathered on the lower part of the belt and nothing falls outside the conveyor.
Simple supporting structure
The SICON conveyor requires less space than a conventional belt conveyor and the supports are simple.
- Supports for wall mounting (walkway is optional).
- Covered gallery for easy access in all weather conditions.
- Out-door support with simple cover for protection against sunshine and rain.
The SICON conveyor is available in two basic sizes, SICON 100 which covers the range 0-100 m3/hour and SICON 1000 which covers 100-650 m3/hour. Both sizes are available for demonstration at the SICON plant in Helsingborg, Sweden.
For max. lump size, see table 1.
Reference installations for SICON .1000
The first SICON conveyor described above was installed by Cexnenta AR at their main production plant at Slite, Sweden. This conveyor has been in operation since April 1988 and the performance is excellent.
In fact, the same client has since ordered a second conveyor of the SICON 1000 size for handling of cement clinker. Capacity is 150 tons/hour with possibility to increase to 250 tons/hour and the total length is 220 in. This conveyor will run round three 90 curves making it possible to do the complete transport in one single conveyor. Conventional belt conveyors would have needed three transfers with corresponding spillage and costs.
The new conveyor was commissioned in June 1989 and with suitable dust extraction at the loading and discharge points it has been possible to make the total system dust-free although the product (cement clinker) is very dusty.
The following comments are made by Mr. Christer Hoglund, responsible for the purchase and installation of two SICON conveyors at Cementa's production plant at Slite, Sweden.
Experiences from installation and operation of the SICON conveying system
At the Cementa plant in Slite we now have two SICON conveyors in operation. The first conveyor handles sand and limestone and the second handles cement clinker.
The sand and limestone conveyor has been in operation since April 1988 and the clinker conveyor was commissioned in June this year. Data for these conveyors is specified below.
The two conveyor systems are quite different in their applications but they had one common requirement; to negotiate a complicated path through existing conveyor bridges and buildings.
In this respect, the SICON system offers some unique possibilities. Also, the fact that the SICON system is totally enclosed simplifies and considerably reduces the total cost for the SICON conveyor in comparison with conventional conveyors.
Sand and Limestone conveyor
In the early planning stage we were studying various different conveying systems, all of which had one common disadvantage, they all required several transfer stations. By coincidence we came across the SICON system which was not previously known to us. After we had had the opportunity to study a prototype of the SICON conveyor we realized that this system would provide the ideal solution for our application.
At this stage we could only base our judgment on the prototype which was built primarily for testing and demonstrations.
However, we felt that the SICON conveyor was sufficiently tested to minimize the risk and we decided to install the first unit at our plant in Slite. This decision has now, two years later, proved to be the correct decision.
When we started planning the clinker conveyor we were faced with new and different requirements compared to the sand and limestone conveyor. In this case, it was the dust control at the loading and discharge points as well as the high temperature of the material which was our greatest concern.
However, the experience from the first installed SICON conveyor made us convinced that the SICON conveyor was best suited also for this application. The alternative was conventional belt conveyors with transfers and associated dust extraction plants and filters.
In order to avoid excessive temperatures of the cement clinker we installed a temperature sensor (type pryometer) which automatically stops the feeding conveyor if the temperature of the material exceeds 100C. The type of rubber to be used in the belt was carefully selected to optimize such properties as flexing, temperature resistance and wear resistance. The final choice was a chlor-butyl type of rubber compound.
The dust problem at the loading and discharge stations was solved by installing two dust extraction units each with a filter area of 60m2. The result is a completely dust proof transport of cement clinker.
We now have one and a half years operation experience with the first SICON conveyor system. The environment and the working conditions for this conveyor is very tough, which is not really desirable for the first commercial installation.
The principal design of the conveyor is almost identical to the first prototype which was demonstrated to us 2 years ago. The modifications were mainly related to the design of support and guide rollers.
The initial problems and failures during the commissioning period were mainly caused by circumstances outside the conveyor system e.g. the stipulated conditions for the feeding of the belt were not fulfilled.
The main reasons for malfunction was caused by overfilling the belt with material or in some instances by filling the belt with water. The water was unfortunately draining from the stockpile, via the feeding conveyor into the SICON conveyor.
After eliminating these problems the SICON conveyor has had a very high availability.
The experiences from the sand and limestone conveyor, both from the manufacturers and the operators point of view, have been used in the design of the clinker conveyor. This conveyor has only been in service for a short period but so far we can confirm that the commissioning and performance has been completely trouble-free.
What makes the SICON conveyor so unique is the small dimensions and the enclosed handling. There is no dust and no spillage along the total length of transport thanks to the enclosed return part and the elimination of transfers.
So far the maintenance costs have been low and mostly limited to preventive maintenance and inspections of the belt and the rollers.
Reference installation for SLCON 100
A conveyor of the SICON 100 size has been ordered by the Swedish company Hoganas AR for installation at their new production unit at Hoganas. This conveyor will handle iron powder at a rate of 30 tons/hour. The total transport distance is 280 in and the conveyors will have 10 loading points and two alternative discharge points. Strict environmental requirements have influenced the design of loading and discharge points, all of which are connected to a dust extraction system. Hereby the transport is free from any dust emission and spillage and the material is protected from moisture.
The erection work started in July 1989 and commissioning will take place when the production starts up in the later half of 1989.
The SICON conveyor has created a great interest from many different sectors of the industry and for handling of a wide range of products.
- Building Industry
- Stone, Aggregate, Sand, Lime-stone, Clay, Cement, Gypsum, etc.
- Power Generation
- Coal, Wood-chips, Peat, Bottom Ash, Fly Ash, Lime, Gypsum, etc.
- Paper Industry
- Wood-chips, Paper Pulp, Kaolin, Chemicals, Waste Paper, etc.
- Steel Industry
- Ore, Coal, Slag, Metal Concentrates, Foundry Sand, etc.
- Mining Industry
- Ore, Minerals, Overburden, etc.
- Food Industry
- Flour, Sugar, Vegetables, Fish, Frozen Food, Cereals, etc.
- Feedstuff Industry
- Grain, Soya Meal, Fish Meal, Tapioca, Pellets, etc.
- Chemical Industry
- Minerals, Chemicals, Ready-made Products in Granular or Powdery Form, etc.
The company Scaniainventor Conveyor Sicon AR was formed in 1987 for the development and marketing of a wide range of products for dust-free handling of bulk materials, including the SICON conveyor.
The products are based on systems and designs patented by AR Scaniainventor of Helsingborg, Sweden, who also holds the patents for the well-known SIWERTELL shipunloader.
SICON CONVEYOR SYSTEM REFERENCE LIST
Client Site Qty Capacity x
Product AAC Diamond
Orapa Mine 1
25 tph x 105m
5 tph x 105m
50 tph x 295m
25 tph x 245m
Kimberlite Concentrate Eskom Kendal Power
6 640 tph x 90m Boiler Bottom Ash PPC Lime/ISCOR Vanderbijlpark:
200 tph x 240m
200 tph x 250m
200 tph x 400m
70 tph x 170m
200 tph x 160m
15 tph x 60m