© Springer International Publishing Switzerland 2015 C. Niemann-Delius. (ed.), Proc. of the 12th Int. Symp Continuous Surface Mining - Aachen 2014,

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Lecture Notes in Production Engineering, DOI: 10.1007/978-3-319-12301-1_3

Maintenance of Belt Conveyor Systems in Poland – An Overview

Radoslaw Zimroz1,2, Monika Hardygóra1,2, and Ryszard Blazej2

1 KGHM CUPRUM Ltd CBR Sikorskiego 2-8, 53-659 Wrocław, Poland 2 Machinery Systems Division, Wroclaw University of Technology, Na Grobli 15, 50-421 Wroclaw, Poland {monika.hardygora,radoslaw.zimroz,ryszard.blazej}@pwr.wroc.pl

Abstract. The tendency to increase efficiency and safety in mining industry leads to quick development of monitoring, diagnostic and management systems. It can cover different aspect of mining activities. In this paper recent achievement in Polish mining industry related to machinery systems will be discussed. Selected solutions deployed by research teams from Wroclaw University of Technology in both opencast and underground mining companies in Poland will be briefly pre-sented and discussed. The purpose of this paper is to provide current state of the research and practices focused on maintenance of belt conveyors. In particular, among others, following projects will be overviewed :i) Online monitoring system for drive units developed for lignite mine, ii) Portable monitoring system for con-veyor belt with steel cords developed for lignite mine, iii), Diag Manager – main-tenance system for belt conveyor transport network, iv) Laboratory and in situ research on belt conveyor technology (belts, joints, idlers resistance to motion, energy efficiency, etc). The Authors will try to summarize challenges in this field and point out future work at the end of the paper

Keywords: belt conveyor, condition based maintenance, nondestructive testing, condition monitoring.

1 Introduction

Nowadays every company should compete with other players on the market in terms of efficiency, quality of products, production cost etc. Any troubles (break-downs) with often complicated, unique machinery systems used in the company is very undesirable due to financial loses as well as safety of the staff and environ-mental issues. It was reported by Babiarz and Dudek [1] that due to unexpected breakdowns several heavy duty machines in Polish opencast lignite mining was destroyed completely and other required significant investment to rehabilitate ma-chine or used mechanical systems. Similar problem might be find in underground mining (hard coal, copper). What kind of reasons have been occurred in men-tioned cases? The most spectacular have been related to basic machines in lignite mine industry as bucket wheel excavator (planetary gearbox failure – several

22 R. Zimroz, M. Hardygóra, and R. Blazej

month of production breakdown, BWE boom failure, burning of machine due to belt ignition, etc).

In this paper we would like to be focused on belt conveyors in both opencast and underground mines. Critical problems for this mechanical system are related to belt (longitudinal intersection, joint failure), pulleys (damages of coating, bear-ings, shaft) and other element of drive units (damages of electric motor, coupling, gearbox). Due to mechanical contact of pulley’ coating and belt, it has sometimes happen that temperature is increasing and belt ignition might initiate. This is very dramatic situation for underground mines and usually results in serious conse-quences in terms of organization of production in the mine, investigation by local mining authority, financial losses for mine and managers, unfortunately it might me also affect safety of mining staff.

Any failure of the machines in the mine might be very difficult to repair due to sparse parts and experienced staff availability, environmental factors etc. To avoid such situations, to maintain effectively machines and to manage of maintenance process, many project have been launched in last decade in Polish mining indus-try. The purpose of this paper is to list and review them as well as to synthesize current effort to project what would be important in the near future in Poland.

A current state of the research and practices focused on maintenance of belt conveyors will be discussed, in particular, among others, following projects will be overviewed: i) Online monitoring system for drive units developed for lignite mine(2010), ii) Portable monitoring system for conveyor belt with steel cords de-veloped for lignite mine(2013), iii), Diag Manager – maintenance system for belt conveyor transport network (2011 and 2013), iv) Laboratory and in situ research on belt conveyor technology (belts, joints, idlers resistance to motion, energy effi-ciency, etc). Mentioned industrial project have been deployed by research teams from Wroclaw University of Technology, to provide whole picture regarding situ-ation in Poland, other important implementation in both opencast and underground mining companies in Poland will be recalled as well.

2 Belt Conveyor and Belt Conveyor System

To realize how important problem is discussed in the paper a brief description of conveyor and example of conveyor based transportation system in the mine will be presented. Fig 1a presents simplified diagram of a belt conveyor, which con-sists of: a drive unit(s), a belt loop, idlers and some auxiliary elements. From the very first view it doesn’t look so complicated. However, the problem with main-tenance of belts, drive units, idlers etc is related to specificity of mining industry. Today over 500 km of conveyor belts are installed in 4 lignite surface mines in Poland, even more conveyor belts are installed in underground mines. In this pa-per research is focused on belts and drive units. Different loading, harsh environ-mental conditions, large dimensions and weight of conveyor components, high power required to transport materials etc require innovative approaches for belt conveyor maintenance management. It is important to notice, that elements of

Maintenance of Belt Conveyor Systems in Poland – An Overview 23

conveyor-based system are located on large area of mine (so called spatially dis-tributed system) that requires also specific logistic procedures (Fig2). Taking into account all these factors and different detailed problems of given conveyor com-ponent, dedicated systems have to be developed, and finally information from them should be integrated to make a decision on maintenance action.

Idlers Loading point

Conveyor beltDrive pulley

Return pulley

Fig. 1 Simplified diagram of a belt conveyor

Fig. 2 Example of belt conveyor based transportation system for one of lignite mine in Poland

3 Belt Conveyor Laboratory

Transportation system in the mine is a key component in production chain in the mine. There is very undesired by the miners to do any “passive” experiments that might affect production efficiency. Any “active” experiments (introducing dam-age) to test efficiency of monitoring system are not possible due to financial, or-ganizational and safety reasons. In such a case the only possible solution is to play with test rig. Such a conveyor for testing was built several years ago in our labora-tory to test diagnostic systems. The belt is 17m length, 40 cm width, conveyor is

24 R. Zimroz, M. Hardygóra, and R. Blazej

equipped with speed control system, unfortunately, there is no load applied to the conveyor (no material stream). It should be highlighted that it cannot replace final test in situ, however it significantly decreased cost of testing belt diagnostic sys-tems, vibration monitoring system, infrared thermography based diagnostic proce-dures. Other equipments to identify parameters of belts or their joints have been described in [2]

Fig. 3 A test rig used for monitoring/diagnostic oriented research

4 Monitoring and Diagnostic Systems for Belt Conveyor

In this chapter following subsections will discuss: i) Online monitoring system for drive units developed for lignite mine (2010), ii) Portable monitoring system for conveyor belt with steel cords developed for lignite mine (2013), iii), Diag Man-ager – maintenance system for belt conveyor transport network developed for underground copper ore mine (2011 and 2013). Again, number of element, their different importance in the system, motivates us to develop different solution: portable diagnostic system that has to be installed for each measurement and de-installed after that and online, stationary system. Reasonable decision making should be based on many factors, including average lifetime, loading condition, damage type, importance of monitored component in whole chain and finally cost of single stationary monitoring system

4.1 Diagnostic System for Conveyor Belts

A key difference between condition evaluation of belts and other object is that length of the belt could reach several kilometers and the belt is moving with speed equals approx. several m/s. Moreover, number, size and density (along belt length and width) of damage could be very different and non-uniformly distributed. It is due to the fact that belt’ loop consists of sections with different length. So in other words there is no other option for using automatic monitoring and diagnostic sys-tem. However, specific practices in belt operation requires dedicated solution that need to be implemented in the system (“beginning” of the loop, differentiation be-tween damage and joint, influence of belt speed, etc.). All these issues have been taken into account in system presented in Fig 4 – hardware and software part are presented, respectively [3, 4].

Maintenance of Belt Convey

Fig. 4 Diagnostic system in owindow of developed softwa

Fig5 shows example oFig5a shows spatial distrthe belt, note that joints adescribing number of damof detected damages vs be

Fig. 5 Visualisation of diab) histogram no of damagd)distribution of amplitudes

From Fig 5 one might damages that should be bagement. More informatio

yor Systems in Poland – An Overview 2

operation: a) during measurement in the mine, b) view on maiare

f results obtained for conveyor operating in lignite minribution of detected damages (along width and length ore not visualized here), while Fig 5b-d aggregated resul

mages vs belt width, length and finally sum of amplitudeelt width.

agnostic results: a) spatial distribution of detected damagees per channel ,c) distribution of damages vs. belt’ lengtof damages per channel,

extract knowledge about size number and distribution obasis for decision making in modern maintenance manon about system could be found in [3,4]

25

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26

4.2 Maintenance MConveyor Syste

Continues belt conveyormany conveyors. There ain several regions of the mstream transport. It is obvequipped with continuousrisk, other conveyor coulcommon conclusion mademeasurement is performedata acquisition takes no laptop (fulfilling militarymine) automatically colleformation on machine conviding a data package forthat is used in the office (Fig 8). More information

Fig. 6 Diagnostic data acqurometers), b) laptop with app

Fig. 7 Visualisation of measfeatures extracted after signa

.

R. Zimroz, M. Hardygóra, and R. Blaz

Management System for Underground Belt em

based transport system form of complex structure oare two group of conveyors: low capacity conveyors usemine and high capacity conveyors used for main materivious that second group is more important and should bs monitoring systems. Due to financial reasons and loweld be maintain by periodic diagnostic inspection. It wae by engineers and researchers. Fig 6 shows how such

ed. Installation of the sensors, launching the software anmore than a few minutes. The software installed on th requirements due to harsh environment in undergroun

ect and process the data (Fig 7) and finally provides inndition. The portable data acquisition system is also pror data base – kind of maintenance management softwarto prepare reports, to plan maintenance action and so o

n are provided by [5,6]

uisition: a) view on sensors location (tacho probe and 2 accelpropriate software for data acquisition and diagnostics

urement and feature extraction: a) raw vibration signal (60s), al segmentation – 60 features with reference to operating cond

zej

of ed ial be er as

h a nd he nd n-o-re on

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Maintenance of Belt Convey

Fig. 8 Diag Manager II – stransportation system

4.3 Condition Mon

As it was said, in the stpower plant or main transto assure very high reliabiveyor operation automatideveloped and installed intion and scheme of belt cosystem collect different ttional shaft speed and vgearbox and pulleys comconsists of sensors, wire10a), WiFi transmission f(Fig 10b, 11a) and finally11b). More details about t

Fig. 9 a)View on monitorecomponents to be monitor

Fig. 10 Hardware componeb) central unit CU with comp

yor Systems in Poland – An Overview 2

software for maintenance management of belt conveyor base

nitoring System for Lignite Belt Conveyor

trategic part of transportation system (i.e. lignite to thsport line directly to mining shaft), there is a serious neeility of belt conveyors. Due to tendency to make the conic, a dedicated condition monitoring system have been the mine. Fig 9 show a picture of monitored drive stonveyor with marked key components to be monitor. Thtype of physical variables (temperatures, currents, rot

vibration), process them, diagnose condition of enginmponents. The system follow modular/layer structure ane transmission to the Data Acquisition Unit (DAU, Fifrom DAU to Central Unit (CU), processing layer at Cy visualization, reporting and publishing (Web) layer (Fithe system could be found in [7]

d drive station, b) scheme of belt conveyor with marked ke

ents developed for the project:a) data acquisition unit DAUputer for control, visualization and web-acces services

A

B

C

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28 R. Zimroz, M. Hardygóra, and R. Blazej

Fig. 11 Visualisation of diagnostic results: a) main window of user interface with all chan-nels providing information about current condition, b) long term trend analysis

5 Trends in Monitoring and Diagnostic Systems for Belt Conveyor

Development of sensor and measurement technologies as well as data transmis-sion and processing techniques make possible to apply very advanced, multichan-nel monitoring systems for maintenance purposes. Moreover, apart from measurement, it is often require to combine knowledge from measurements with knowledge about failure analysis, human factors influence, environmental impact and so on. All these information are nowadays available in modern corporations in various data bases and information systems. In authors belief, the future of main-tenance management will be based on data/information and knowledge fusion. Problem of mining machines is that they operates in very harsh conditions, and problem of maintenance seems to be very complicated [8]. It is due to number of factors that should be taken into account. Additional problem that was recently deeply studied by Bartelmus is influence of varying operating condition [9] and unique degradation scenarios [10] in mining industry. This problem is partially re-lated to data fusion concept suggested by Galar [11], because apart from current diagnostic features values, knowledge about operational condition should be taken into account Also history of operation (number of startup and shut down events, repair action etc.) might significantly modify results of condition assessment and prognosis. Research team lead by Barszcz [12] pointed out that due to harsh con-ditions, complexity of machines and influence of external factors, data collecting by automatic systems should be carefully interpreted and validated. It appears that many data acquired by condition monitoring systems doesn’t contain any diagnos-tic information due to, for example, damaged sensor. Finally, the last key issue and in fact serious challenge for diagnostic is problem of decision making based on collected data. Decision scheme commonly used in monitoring system follow the “if then else” rule, that basically mean constant thresholds for warning or alarm [13-15]. It has been proved among others by Bartelmus [9] that in machines operated in time varying conditions values of thresholds should be load dependent and might be linear or nonlinear function of load. Mentioned challenges (feature-

Maintenance of Belt Conveyor Systems in Poland – An Overview 29

operating condition dependencies, validation, load dependent threshold, data fu-sion) seems to be universal problems both for rotating machines as well as belts condition monitoring. It should be noticed that there are other commercial solu-tions that also are used in mining companies ([16-18]) as well as other research in-stitutes. As far as we know, at least in systems operated in mining companies, mentioned problems were not solved in systematic way. Thresholds are “adapted” according to engineering experience (what if machine is unique?), data fusion is not performed, varying load is not taken into account. A final conclusion could be formulated in optimistic manner: there is a lot of work to do with monitoring and diagnostic in mining industry from research perspective and fortunately, there are more and more mining companies that want to invest money in Condition Monitoring.

6 Conclusion

In the paper a review of last developments of condition based maintenance solu-tions dedicated to belt conveyors is presented. They have been prepared by mem-bers of Machinery Systems Division and prototypes were installed in opencast and underground mine. A brief description of basic functions implemented in these system is provided in appropriate sections. Finally, several challenges for future work are pointed out. They seem to be complicated task and according to authors knowledge many research teams work on them. Finally in the paper we point out several challenges that come out from many years of experience with mining ma-chines, monitoring and diagnostics. Unfortunately they seem to be classical ones: experimental data validation, data processing, modeling, analysis, decision mak-ing, information processing and visualization.

Acknowledgements. This work is partially supported by Applied Research Programme (PBS): “Intelligent system for automated testing and continuous diagnosis of the conveyor belt” (2012-2015) – R. Blazej and KGHM Cuprum – M Hardygora and R. Zimroz

References

[1] Babiarz, S., Dudek, D.: Kronika awarii i katastrof maszyn podstawowych w polskim górnictwie odkrywkowym Oficyna Wydawnicza Politechniki Wroclawskiej (2007)

[2] Błażej, R., Jurdziak, L., Zimroz, R., Hardygóra, M., Kawalec, W.: Investigations of conveyor belts condition in the Institute of Mining Engineering at Wroclaw Universi-ty of Technology. In: 23rd World Mining Congress, Montreal, Canada, August 11-15, pp. 1–9. Canadian Inst. of Mining, Metallurgy and Petroleum (2013)

[3] Błażej, R., Jurdziak, L., Zimroz, R.: Novel approaches for processing of multi-channels NDT signals for damage detection in conveyor belts with steel cords. In: Key Engineering Materials, vol. 569/570, pp. 978–985 (2013)

30 R. Zimroz, M. Hardygóra, and R. Blazej

[4] Błażej, R., Zimroz, R., Jurdziak, L., Hardygóra, M., Kawalec, W.: Conveyor belt condition evaluation via non-destructive testing techniques Mine planning and equipment selection. In: Drebenstedt, C., Singhal, R. (eds.) Proceedings of the 22nd MPES Conference 2013, Dresden, Germany, October 14-19, vol. 2, pp. S.1119–S.1126. Springer (2014)

[5] Zimroz, R., Król, R., Hardygóra, M., Górniak-Zimroz, J., Bartelmus, W., Gładysiewicz, L., Biernat, S.: A maintenance strategy for drive units used in belt conveyors network. In: Eskikaya, Ş. (ed.) 22nd World Mining Congress & Expo, Is-tanbul, September 11-16, vol. 1, Aydoğdu Of set, Ankara (2011)

[6] Stefaniak, P., Zimroz, R., Krol, R., Gorniak-Zimroz, J., Bartelmus, W., Hardygora, M.: Some remarks on using condition monitoring for spatially distributed mechanical system belt conveyor network in underground mine – A case study. In: Fakhfakh, T., Bartelmus, W., Chaari, F., Zimroz, R., Haddar, M. (eds.) Condition Monitoring of Machinery in Non-Stationary Operations, vol. 110, pp. 497–507. Springer, Heidel-berg (2012), http://dx.doi.org/10.1007/978-3-642-28768-8_51

[7] Zimroz, R., Król, R., Hardygóra, M., Bartelmus, W., Gładysiewicz, L.: Condition monitoring system for drive units in belt conveyor. Transport & Logistics (Bel-grade) 7, 342–346

[8] Hardygóra, M., Bartelmus, W., Zimroz, R., Król, R., Błażej, R.: Maintenance, diag-nostics and safety of belt conveyors in the operations. Transport & Logistics (Bel-grade) 6, 351–354

[9] Bartelmus, W., Zimroz, R.: A new feature for monitoring the condition of gearboxes in non-stationary operating conditions. Mechanical Systems and Signal Processing 23, 1528–1534 (2009)

[10] Bartelmus, W.: Gearbox damage process. Journal of Physics. Conference Se-ries. 305(1), 1–9 (2011)

[11] Galar, D., Gustafson, A., Tormos, B., Berges, L.: Maintenance Decision Making based on different types of data fusion. Eksploatacja i Niezawodnosc – Maintenance and Reliability 14(2), 135–144 (2012)

[12] Jablonski, A., Barszcz, T.: Validation of vibration measurements for heavy duty ma-chinery diagnostics. Mechanical Systems and Signal Processing 38(1), 248–263

[13] Cempel, C.: Limit value in practice of vibration diagnosis. Mechanical Systems and Signal Processing 4(6) (1990)

[14] Brooks, R., Thorpe, R., Wilson, J.: A new method for defining and managing process alarms and for correcting process operation when an alarm occurs. Journal of Ha-zardous Materials 115 (2004)

[15] Jablonski, A., Barszcz, T., Bielecka, M., Breuhaus, P.: Modeling of probability distri-bution functions forautomatic threshold calculation in condition monitoring systems. Measurement 46(1), 727–738 (2013)

[16] http://famur.com.pl/ - description of FAMAC VIBRO system [17] http://www.pruftechnik.com.pl/, description of diagnostic systems from

Pruftechnik [18] http://www.ec-systems.pl/pl/, description of diagnostic solutions from

EC Systems