26 km long troughed belt conveyor for Asia Cement Group

In 2004, the company decided to build a new cement plant in Sichuan. During the development phase, Asia Cement Group received approval from the Chinese government to use an abandoned railway to transport the limestone. Halfway through finishing the plant however, the government decided to build a new dam. The area intended for the transport was to be flooded, which would have changed the project conditions considerably: roads would be flooded and the trucks would have to take significant detours. Asia Cement Group was also planning on building two additional kiln lines at this location. It was determined, as a time and cost efficient alternative, to install a troughed belt conveyor able to navigate horizontal and vertical curves. For this, the company turned to us. For many years now, Asia Cement has been relying on our expertise and is currently operating several of our bucket elevators.

In May 2006, Asia Cement Group awarded the contract for the 12.5 km long system. The overland conveyor can reach a mass flow of 1,500 tons per hour and a conveying speed of four meters per second. Compared to other conveying solutions, the open troughed belt conveyors are suitable for higher throughputs. Horizontal as well as vertical curve radii are possible. They can be adapted to the specific task and topography. Using our calculation programs, we can precisely calculate the static and dynamic tractive forces of the belt during the development phase of the system. This is a prerequisite for the safe dimensioning of horizontal curves. The type of drive technology and conveyor belts needed are based on these calculations. This ensures longevity of the entire system.

Mountains, soft grounds and extreme heights

The terrain is hilly and covered with dense bamboo forest, parts of which are listed as nature reserve. For this reason, the government did not approve a service route nor deforestation. The ground also presented a major challenge for our engineers: The ground is unstable due to previous coal mining. In other areas, the ground consists mostly of granite that could only be partially removed. Another section of 1.5 kilometres had to be guided across a river. These framework conditions contributed to the fact that 90 percent of the system was installed manually on site. As it was impossible for trucks to transport the components, they were carried by mules, one part at a time, to the place of installation.

The route of the overland conveyor was coordinated between us and the cement manufacturer. We calculated the tractive forces of the belt considering the eight horizontal curves with radii of 1,000 to 5,000 metres. The routing was checked for its feasibility on site. The complete route was checked by employees on foot, passing through rough terrain, in order to reliably check the predefined positions for the 460 supports for their suitability directly on site. Whenever technically possible, the routing of the conveyor was adapted to the topography. Height differences of up to 100 metres had to be overcome within shortest distances, so several sections were equipped with bridges of up to 55 metres. One section was realised with a 130 metre long tunnel.

In close cooperation with the customer, we designed the overland conveyor and the bridges. We developed, built and supplied the core components for the drive and take-up station as well as the belt of an overall length of 25 kilometres, the idlers and the drive technology. Since February 2009, the overland conveyor has been transporting bulk material from the quarry to the bulk loading system. Since commissioning of the first section, the mass flow of the conveyor was increased in two steps. Today, the system conveys a mass flow of 2,200 tons per hour at a conveying speed of 4.5 metres per second.

The longest belt conveyor in company history

In July 2013, Asia Cement contracted us again for an additional, efficient overland conveyor to replace the trucks transporting the limestone from the bulk loading system to the cement plant. A mass flow of 2,200 tons of limestone per hour was necessary to meet the plant’s requirements. For this project, the first conveyor was to be customised to these requirements. We were planning a second troughed belt conveyor with an overall length of 13.7 kilometres. This is the longest system in our history.

Projects of that size are often unpredictable, so flexibility was needed from the engineers. During the planning phase, the cement manufacturer acquired another plant in Lanfeng, approximately ten kilometres away. Now we had to design the system so that both plants could be supplied with limestone. The team had to divide the overland conveyor in two parts. After 5.4 kilometres, an additional conveyor can be added to be fed to Lanfeng in the future. In February 2015, the system supplier started with the installation of the conveyor frame.

Both overland conveyors have four horizontal curves with radii of 1,200, 1,500 and 1,800 metres. We provided the engineering and the individual parts such as pulleys, motors, drive and control technology and the entire automation. The installation was monitored by a BEUMER supervisor and the wiring of the system was supported by a BEUMER electrical engineer. We were also in charge of the commissioning in May 2016. The troughed belt conveyor is now supplying three kiln lines, a fourth line is planned.

We took several constructive measures in order to reduce the noise emissions. We used noise-reducing idlers and customised protective covers on the drive stations. In collaboration with the operator, we optimised the conveyor frame and the completely enclosed conveyor bridge.

For the whole project, we were able to ensure that the limestone is transported safely and quietly, without disturbing the residents or disrupting the surrounding nature.