FUTURE MINING AND UNDERGROUND AUTOMATION
“ The problem arose,” Shields explains,“ in the long material drop to the conveyor loading zone. There was a 3.67 m fall from a 1,829 mm belt onto the 1,524 mm receiving belt. This proved a challenging application for the belt support systems. The long drop led to damaging levels of impact below the loading zone of the receiving conveyor. The mine had regularly seen failures with conventional impact idlers; it would typically need to change four or five damaged rollers, and one or two broken idler frames in an‘ average’ month of operation.
“ These challenging conditions made it seem that the high speed roller impact cradle would be the right equipment for this application.
“ After installing a series of high-speed impact cradles, the mine put 2.9 Mt of copper ore through the transfer point during a two-week period. There were zero idler failures. While this can be seen as a brief trial, the severity of the application holds the promise of improved performance for those installations where high conveyor belt speeds limit the opportunities for improved belt support systems.
“ In another application, the high speed impact cradles performed well in a coal mine application in South Africa, demonstrating reduced impact damage and material spillage.”
Digital age coal mining
Karol Bartodziej, Operational Director of FAMUR, notes the“ the efforts to connect all the machinery involved in the production process into one coherent network, so as to make it possible to create a centralised system of production supervision and control. The widely promoted development of IIoT technology( Industrial Internet of Things) or the concept of Industry 4.0 make it become clear that, despite the existence of several industrial data transmission standards, the standard to be a leading one in the near future is the transmission of process data over Ethernet.”
In underground coal mining such systems have not been very popular so far.“ This was mainly due to two factors: the presence of explosive atmospheres near the transmission devices and the presence of large quantities of impurities. The design of network devices that can operate in explosive atmospheres enforces the limitation of energy at their outputs, which significantly impedes the transfer of high speed digital signals over long distances. In turn, the use of the fibreoptic technique for the transmission of data poses challenges related to the need of keeping connectors clean. In the highly impure environment, maintaining the efficiency of fibreoptic lines is a huge challenge and requires great working discipline from operators. Assuming that the underground mining machinery is located several kilometres away from the nearest server room, this issue seems significant. In such operating conditions, the well-known DSL technologies turn out to be helpful – they allow the users to extend Ethernet networks using telephone lines and are ideal for mining conditions provided that their signal is properly adjusted to the intrinsic safety regime. Building vast underground Ethernet networks is the first step towards the implementation of IIoT or Industry 4.0 concepts.
“ Another key element in the mining process is the use of machines with control systems that enable transmission over such networks. A perfect example of a machine that is ready for integration in Ethernet network with the entire technological process is the KGE-710FM shearer, supplied to one of the customers of FAMUR. This machine is quite unusual, because mining industry safety regulations usually require that an operator is present in sight of the extracting machines.” This restriction results in typical shearers only sending their diagnostic data to SCADA systems, without the possibility of remote control of the machine.
However, the aforementioned KGE-710FM shearer has been supplied to a customer operating in very difficult mining and geological conditions that cause frequent rock bumps and roof collapses. In view of the fact that local rock falls can be life-threatening for the miners who operate the machine, the customer obtained the consent of the mining safety supervision authority for the remote control of the shearer in locations of locally occurring risks to workers. The remote control station is designed in such a way as to ensure that the actions performed by an operator are identical to those performed during his regular work directly on the machine. Therefore, the station is fitted with a monitor displaying the screens that are identical to those the shearer operator sees on the machine in his everyday work and control panels that are the same as those on the shearer, and additionally
all other control-related functionalities are mirrored so that the operator would not have to learn a different way of operation. The station is additionally equipped with a set of cameras which permit observation of the machine in operation. The procedure of starting the shearer in remote control mode is based on guidelines on the equipment operational safety, issued by an appropriate state authority.
“ It has therefore some specific activating procedures to prevent starting the machine without complete knowledge on whether its operation could endanger the safety of any person,” Bartodziej explains. The station can be located at any Ethernet node, so it might as well be installed in the mining galleries near the operating machine or on the surface, or even anywhere in the world thanks to the possibility being connected through the Internet. Thanks to such network architecture, the location of the operator ' s workstation is solely up to the user.”
The KGE-710FM shearer is only one of the examples. Most FAMUR longwall shearers for many years have been fitted with control systems that enable the transmission of data using Ethernet. So there are no technical impediments to equipping these machines with similar functions to those mentioned above. However, Bartodziej notes,“ an aspect preventing the development of remote controlled shearers, or even automatic ones, is the fact that many decisions of the longwall shearer operator are based on their subjective opinion and experience. Therefore, very often the decisive factors are the ones that are difficult to measure, such as the way of crushing the mined rock, or the sound of the shearer ' s cutting drum coming into contact with the mining spoil. As a result, in combination with varying geological conditions, the remote control of the machine or the replacement of an operator with the standalone operation algorithms is a relatively difficult subject.”
Electric power
A February article( IM, pp68-77) focussed on underground electric power( see also MacLean’ s news in the Canadian article). Since then Artisan
26 International Mining | APRIL 2017