It seemed impossible. One of the most unusual projects of FAMUR Group

In 2020, the pandemic changed the reality dramatically for lots of entrepreneurs around the world. Most employers have learned to manage their teams so that they can continue operating in their own markets in spite of the threat and limitations. But what to do if our business commitments extend beyond our 'home turf and would normally involve an employee traveling to a foreign contractor? Meanwhile, we are separated by both the barrier of national quarantines, cancelled flights and traffic bans, but also by the fears of the employees themselves concerning travelling far away at such an uncertain time.

This type of situation occurred to FAMUR Group during the implementation of a project related to the Mikrus complex for a customer in China. The delivery was successful, the unpacking inspection was flawless and suddenly... a total change of circumstances occurred - a pandemic. Instead of implementing the next phase, that was providing the maintenance and engineering services to commission the longwall complex delivered, we faced traffic bans, and the growing epidemic threat made it virtually impossible to perform our contractual obligations as planned.

In the first few months of the pandemic, everyone hoped that it would last a few weeks, a few months at most. However, the situation was getting worse and worse, the feeling of uncertainty and helplessness was growing, and no one could tell how long all this would last. We were aware that the client had invested a lot in our equipment with total confidence that it would help them increase the efficiency of their field, so we could not wait forever. We knew that we had to do everything that we could to enable the Chinese mine to use the longwall complex, even though we would not be able to enter the Middle Kingdom for a long time.

MIKRUS longwall system in the production plant in Poland, 2019.

It is worth noting that the Mikrus system is a set of machines consisting of a cutting and loading head GUŁ, a face conveyor, a beam stage loader, a belt tail piece (boot end), a power supply and control system. We sell a custom-made product so it usually needs the final parameterisation of its operation in the mine, in co-operation with suppliers of the other longwall equipment. Our delivery did not include powered roof support units with electro-hydraulic control system, a 3.3kV power supply system, a safety interlock system or a pump station, and we were the integrator of the longwall complex automation. Unfortunately, due to the reason mentioned above, it was not possible to carry out all the work related to the control system software in Poland, before shipment. Consequently, the direct presence of our engineering services on the first days of the machine's operation and the presence of an experienced service technician during installation were to have a significant impact on the proper operation of the system. The situation was unusual since we had to co-ordinate our control system with Chinese suppliers providing equipment that we were dealing with for the first time ever. Moreover, the contract stipulated that correct interaction between these systems had to enable maintenance-free coal mining in the complex, which was a real challenge in itself.

Since the beginning of the pandemic, despite the restrictions, we applied to Chinese authorities for visas for our employees and letting them enter the Middle Kingdom. However, the decision were postponed all the time due to the epidemiological threat. Thus, it became clear that we had to make every effort to launch our machines... remotely. Since the contract provided for a compatibility test to be performed on the surface before underground operation, we and the client decided that performing this task remotely was likely to be successful.

Remotely? OK... But how do you do that technically?

Our company started with hiring a team of service technicians in China to be our representatives, and under remote supervision, step by step, we began assembling the machines together. Then, we commissioned and parameterised the control system. They were not trained how to handle the product but we needed someone available locally who would perform the necessary tasks diligently, who would be our hands and eyes in the place where remote links were not enough.

We knew that we would need a seamless instant messenger for video conferencing, and a VPN connection in order to use network communications in much the same way as if we were plugged into the machine's network on site. After all, the system tuning work performed by programmers often requires uploading a new version of software to the PLCs or observing the operating parameters to check whether everything works as expected or making adjustments until it is.

Mikrus longwall system’s operator cabin, FAMUR production plant in Poland.

Anyone who has ever been to China knows the difficulties of trying to use the Internet resources available outside the country. Internet in China is separated from external networks under the government Golden Shield Project. Unfortunately, it does not let any typical traffic generated by machines or file transfers, and this was extremely important to us.

Bypassing these protections is rather onerous, and Chinese operators limit transfers to a minimum for such connections automatically. For instance, an average Chinese citizen will say that YouTube, Google or Facebook is not available in their country. A more advanced user, on the other hand, will say that these services are very slow and that their Chinese equivalents are much better because they work in a flash. Therefore, an unexperienced European is often helpless after arriving in China because Google is the primary tool for solving all kinds of everyday problems for us, from finding your way on a map, through timetable information, to using an online translator. If we add the lack of access to Skype, Messenger, WhatsApp, Hangouts messengers to that and Google Play store not working on the phone, life becomes really complicated.

We made several attempts with different Chinese internet providers to get a link that would allow our remote work. Although we were guaranteed higher and higher transfer packages in our agreements, in fact we could only communicate with Poland over an encrypted link at speeds as low as 0.02Mb/s, with the transmission breaking every now and then. The offered links provided the declared parameters yet in China only, and it was impossible to count on any stable transfer outside the country. On the first days of the commissioning, it seemed that we would fail with our task because of this mundane barrier.

Determination of our client, China Energy, which is a major Chinese state-owned enterprise, helped. They arranged a link for us on special terms that was not to be covered by the Golden Shield. Our server was connected on site directly via a fiber optic cable to an international hub in Xi'an, from where the connection to Europe comes out of China. Despite the fact that, in theory, it was a link not supervised under the Golden Shield, the transfer never exceeded 0.25Mbps, although it was supposed to be 500 Mbps according to the operator's declaration. Nevertheless, it was a success. Besides, the connection did not brake and it ensured slow but stable operation. It was a defining moment in the commissioning of the complex.

It is worth mentioning that the programmer has to upload updates repeatedly while tuning the control system of longwall complexes and debug his or her code (analyse whether the code works correctly after corrections and look for possible errors). It is typically done by connecting the laptop directly to the programmable logic controller; the software update usually takes seconds, though it stretches out to minutes with such a slow transfer rate. Each interruption ruins the programmer's work and forces him or her to start over. As such, if disconnections occurred more frequently than once every minute, the programmers' work became impossible. This is why establishing a stable connection to Poland was a milestone in our work. This was also a problem that we would probably never encountered in any other country.

Installation and commissioning

GUŁ cutting and loading head with medium drums (ø 1.40 m). Commissioning on the surface, 2020.

The complex was assembled in two phases before mining began. First, surface testing and training took place from mid-March to late May 2020, followed by a second underground installation phase at the target longwall.

Conducting tests on the surface is not a standard procedure, of course. Nonetheless, due to the unusual design of the Mikrus system and the fact that the suppliers of the longwall roof support and many ancillary components, such as pumps and power stations, were Chinese, the client stipulated in the contract that a compatibility test and training must be carried out on the surface. It made it much easier for us to transfer the knowledge on how to properly assemble and operate the system to our newly-hired Chinese service technicians and the client.

Thanks to the use of the Webex video conferencing system and the Chinese messenger WeChat, online communication was not a problem, and despite the pandemic-related constraints, we worked with the entire team including all necessary specialists to set up the system's various components. Ironically, sometimes this way of working actually made things easier for us, as we had better direct contact with the most experienced constructors in our company, if necessary. 

On-line consultation between our Chinese service staff and the design and maintenance team from Poland.

Time to start mining

The second installation phase – already at the target longwall – took place in June 2020. The first cuts were made in early July. The feeling of satisfaction that accompanied this sight is simply unimaginable. The complex began to fulfil its primary purpose. Chinese trade newspapers began to publish articles about this achievement, and many curious visitors from the nearby mines showed up to see the unusual way the complex works first hand.

The Mikrus complex just before creating the first fully sumped-in cut.

Chinese service technicians we hired were present on site throughout the entire period of the longwall system operation to make sure that it performed correctly. At the same time, a 24/7 supervision process continued at FAMUR Group headquarters to make it possible to immediately respond to any issues and provide substantive support to the Chinese service staff in analysing possible causes of downtime. The wall was equipped with a WiFi network with Internet access, and our Chinese service team used MA-certified phones which they could use to exchange photos, videos and other information with the Service Centre in Poland.

There were three system elements that had the greatest impact on the success of the automatic operation. The first is, of course, the coordination of the movement cycle of the cutting and loading head with the operation of the electro-hydraulic system controlling the powered roof support. The second is the UPZP-1200 belt tailpiece, which automatically follows the mining progress and is part of the beam stage loader. The third element is the SmartMine visualisation and control system, which enabled not only classic supervision of the current state of the machines but also, through the analytical functions, tuning of the drive control parameters to the existing geological conditions, which is crucial for autonomous operation.

The home page of the SmartMine control and visualisation system.

Yet another benefit of the longwall system automation is the Mikrus system's remarkable duty cycle. Unlike in the case of classic longwall shearer systems, the Mikrus cutting and loading head does not have to cut into the wall at an oblique angle, wasting valuable time at each end of the longwall, but it travels to the roadway instead and cuts into the face perpendicularly. This greatly facilitates the automation of powered roof support units and saves time that would otherwise be wasted on diagonal cutting – like in the case of classic longwall shearers. When our system is working in automatic mode, the time spent by the head on the return end or the chute, during which the beam stage loader is being sumped and hoisted, is approximately 3.5 minutes, after which the next cut is made automatically. Our analyses show that most classic longwalls lose more than 20% of their working time precisely for the diagonal sumping of the shearer into the next face.

The cutting and loading head in its extreme position – almost fully extended into the heading, enabling perpendicular sumping (from the drum's front) and possible servicing of the machine.

Complications and a happy ending

In the middle of the longwall length, miners encountered a rock overburden of above-average hardness that had not been detected by previous geological surveys. Since it was not visible from the cut galleries, it was a major surprise to everyone.

The cutting drum power in shearers used for such low longwalls is typically about 200 kW, and no more than 300 kW. However, the Mikrus system's cutting and loading head features a 500kW motor, and as such, we have the full 500kW power for the drum available at the moment of cutting. The control system automatically detected the increased load on the drum and slowed down the head's feed accordingly, so that the entire rock overburden was machined in a way that limited the load on the system and ensured its safety.

The mining on the longwall was concluded on 6 December 2020. During its operation, the Mikrus system showed what it was made for. Not only did it allow us to work in automatic mode but it also managed to mine a bed that no other machine could have mined.

This longwall has made history in Chinese mining. It was the first longwall with perpendicular machine sumping and also the first longwall to operate in fully automatic mode, including automatic hoisting of the beam stage loader.

This is a special achievement also due to the fact that it was a low thickness seam wall (1.40-1.55 m). China's mining industry is showing a great need to exploit more attractive deeper layers of high thickness seams below residual low thickness seams. At the same time, anyone who has worked in a low longwall knows how unimaginably harsh the conditions are and how important it is to minimise the number of people in the area. The Mikrus system offers the possibility of mounting an even smaller drum, with a diameter of 1.2m, so it makes for a good response to the needs of the Chinese market.

Working conditions for people in low longwalls. The wall shown in the photo had a working range of 1.40-1.55 m.

Thanks to the determination of both parties, the installation was successfully completed, both on the surface and underground. At the bottom of the mine, both the assumed daily output and automatic operation of the system were achieved.

Remotely – does it make sense?

Real-life conditions have shown that the entire mining process at the first longwall where Mikrus worked had to be handled remotely. We were unable to get to the site to provide user support in person. Therefore, we were particularly pleased with the decision not to delay the launch of the machine until we arrived in China. We were only able to send a group of delegates to this country at the end of November last year, and given that they had to spend a total of 28 days in quarantine, they did not arrive on site until the time of the machinery inspection. The maintenance work has already been completed and the Mikrus system is scheduled to begin operation in the next longwall in July 2021.

Remote deployment and service is the future of the entire automation industry. It is not merely a matter of the ongoing pandemic. Such services will also become standard soon during normal deployments provided by global companies. While this is not a novelty in many industries, no one in the mining industry has practiced such a comprehensive implementation before. Automatic operation of a longwall system requires time-consuming coordination between the machines of the various suppliers of other longwall equipment. It is a huge task that has usually been carried out side by side by the automation specialists of the individual companies at the destination site. The experience gained during this commissioning showed us how we could further enhance the remote diagnostics features so that start-ups, like the one discussed in this article, would be easier for us and our customers and could become an everyday occurrence. With this knowledge, we can confidently offer our products to foreign markets even during periods of hard lockdown or other cross-border restrictions.