22" International Conference on Ground Control in Mining I Comparison of Multiple and Single Entry Roadways

for Highly Stressed Longwalls

Maus Opolony, Official Appointed Expert for Geomechanics and Roadway Support Deutsche Steinkhole AG

Heme, Germany

Ho/ger Wltthaus, Senior Mining Engineer Deutsche Montan Technologic GmbH

Essen, Germany

ABSTRACT

The world's most popular method of longwall mining requires multiple entry systems for the panels. In conirast to this mine layout the roadways in German coal mining are used for advanced mining from the rock mechanic point of view or are even re-used by a second panel. This procedure of roadway use is presented within this paper using a 3D visualisation sottware tool.

In the previous conferences in Morgantown several papas had addressed the basics of rock mechanic background, planning tools and variants.

This paper paperves a practical case study for reuse of a roadway in a German coal mine. The heading and the use of various altematives are c o t m a d under the arpect of efficiency and costs. Within the compa&on the specific &pirements and benchmarks of German coal mines are taken into consideration. The costs for a multiple entry system and fust of all the development rates that can be achieved with common road heading systems are compared with international layout altematives.

A prospect includes a discussion of pro and con for various development methods. Devices are given due to this prospect if and how multiple entry systems are applicable to German coal mines. The paper gives an initial point for international comparison and is a base for huther discussion.

INTRODUCTION

Multiple entry systems are commonly used with longwall mining. In most countries the longwall roadways were not kept open after the passage of the face line; they are used in a retreat mining method. Especially when there are good geotechnical pmmetem of the deposit the roadways are developed in d g b t lines connected by crosscuts and maintaining an optimal madway shape for the whole length of the panels. The support is designed for stabilizing the loosen strata areas and high rates of development. The development rate amounts up to 150 m per day [31.

The German coal mining in deep mines (up to I450 m 14800 feet deep) is following a different "philosophy". The roadways driven in single entry system at both sides of the longwall are kept

open alter face passage and where it is possl%le, the d w a y between the panels is re-used.

The benchmsrk, the success and the requimmts for this system were discussed several times, e.g. in the previous Morgantown Conferences on Ground Control in M i [2,4,.5,6]. Major items for handling the multiple pmcaues advanced mining are detailed planning procedum and wellzducated &. For matters of training and technical improvement 3D-Tools are used nowadays as well as spcoally developed software packages for planning. The software tools are described in the following.

3D-TOOLS FOR PLANNING AND TRAINING

The continuous process of developing more and more complex mining systems, employing expensive equipment requires high productivity, low downtimes and dective safety msnagmmt systems. This, together with the high m h a r ~ h t i o n of processes is forming the background of today's high performance mining activities. In German coal mining the virtual reality tools are implemented for planning, simulation and training activities. The business spectrum of virtual reality applications includes a virtual copy of realistic processes in the virtual world World), a simulation of the surrounding environment with original control elements (VR-Simulator) and a combination of different cooperating workstations in atraining centre (VR Training Room).

At first the materials and equipment as well as the surrounding environment is modelled within the v i d world. The objects performance is animated. The proeessea can be examined visually from various points of view, even from those which are not possible in real world.

Managing the virtual element with original control panels is simulating the interactive connection of machines handled by several employees. TIe VR-Simulator gives the crew the oppmmity of learning and

mining on the handling of machines and optimization of processes within the Training Room The crew is enabled to iind out the benchmarks of manipulation of the machines without costs of repair and decreasing the real production.

Special q x c t s of safety for the cooperation of a number of workers within the process can be recognized and optirnised and the assistants can be trained.

22- International Conference on Ground Control in Mining

B

Figure I: Example 3 D-Animation of face and shearer

Figure 1 shows an example for the development of the tace and the sheanr within the VR World. The geometric situation f o m d by geological pimunetcrs and also the whole equipment of support sn included

Figure 2 shows an example for the VR Simulator of a roadhedig with drilling and blasting development. The paint of view for the driller working at the wntrol panel of a drilling machine is simulated. Within the VR iraining room the crew gets optimised training for the drilling work and cooperation with the other workers handling the support and loader [q.

Figure 2: Example 3 D-Tool Simulator ror tne arilling unit developing a roadway with steel arches (drilling and blasting)

Tbe work of planning the roadway drivage begins a&r the support design p m s s has been completed. Tbis calls for the bea possible equipmmt to be selected for the given operating conditions. Previously each colliery in Germany had its own planning model, hut nowadays due to information systems all around the world and internationalised mining companies they have the advantage of being able to deploy diffemt planning models. Using the conventional planning instruments to compare the various models available is still a very expensive procedure and sometimes insufficient solutions wen made in adapting technologies and systems fmm other standards. ' Tbe PPO softwan (processing, planning and optimisation), which has been developed by DMT in wllaboration with Augune Victoria wlliery and the Central Division ZIT R-V of DSK- company, provides planning enginems with a simple tool. Tbe tool developed within a European R&D project of the ECSC program can be employed under similar sets of conditions at the planning stage in order to try out various equipment and manning models for the actual roadway drivage operation. The r d t of this exercise is a standardized and objective decision-making tool containing technical and output-related information [I].

After a planning model has been established which is based on the efficient deployment and availability of the operathg equipment, it is then used to provide the fundamental specifications for carrying out the roadway drivagc operation.

In Figure 3 a comparison is shown for the performance of mechanised drivage operations, d i c h use the roadheading machines, with that of the conventional drivage projects with drilling and blasting. Tbe conventional drivage uses a variety of loading machines, with roadway devclopment manning levels rrmaining relatively constant. The analysis also includes additional data relating to the impact of outbye o p t i o n s on the theoretical performana. On the basis of the performance show in the example given, mechanised drivage using an AM 105 roadheader would appear to be the most favourable solution.

22"d International Conference

Figure 3: Performance comparison for roadway drivage operations using workflow diagram (PPO hogram)

The performance calculation is based on workflow diagrams and has to be adjusted during and after the conversion process. During this procedure the accuracy of the planning tool is continuously improved for each subsequent planning phase. The more upto- date the input data for the performance calculation, the greater the efficiency of this method of roadway-model comparison [S].

MULTIPLE ENTRY SYSTEM WITH RETREAT MWMG VS RE-USE OF ROADWAY

on Ground Control in Mining with a longwall should he parallel at work with one development ot the next longwall. The average production rate of l o n g d l should be 8 metres per day that means 250 days hme for development of roadway system for the next panel.

la the comparison of multiple entry system to r e w e of single roadways 3 variations are examined looking at two panels to be mined:

A. Multiple entry system with 2 roadways at the outer edge of the two panels and a 3 road system in the centre between the roadways

B. Single entry system with each panel bas its o w main and tailgate

C. Single entry system with re-use of the central roadway between the panels to be used as maingate for the la face and tailgate for re-use.

Looking at the minrmum required size of madway shape and taking into consideration the highly stressed wnditions different size of roadway is necessary for the roadheading machine. The convergence of roadway shape must be taken into account with about 10 % after the development of the roadways, approximately 20 % for the situation at the 1' face passage and up to approximately 50 % for the 2d face passage. This means that the variants A and El can be realized with roadways without any measures behind the first face but C has to include a roadside package system. For installation special support elements are necessary in the area of the face entry of the I* face. Figure 4 gives a plan view of the situation at the face entry.

.~~ "! A comparison of multiple and single entry roadway systems for Figure 4: Plan view of face entry with squipment for

highly sassed roadways can be executed using the PPO software. The parameters for the chosen example must be fixed before the package

costs and productivity can be wmpared. For the following Beside the standard shield support of the face line special statements the bordering m e t e r s are fixed as s h o w in *le 1. units are orientated at the face end and in the

Table 1: Fixed Parameters for the comparison

Within the comparison of roadheading the direct costs will be mentioned but the indirect costs, e.8. for developing the infrastructure will not be taken into considexation to keep it as simple as possible. The approximation of machine costs and personnel costs are based on experience in German coalmining. The organization of mine is fixed in the way that one production

behind the face entry. The ~ l a n mves a typical situation for rectangular shaped rockbolted rbaawiy. Fksidethis arched shaped roadwavs with combined sumn using steel arches. backfilliw and mckbokig are used often' in G& coal &ICE. Fo; the following comparison the rectangular rockbolted roadways are examined.

COMPARISON OF COSTS AND EFFlClENCY

Table 2 shows the result of costs and efftciency for the Options A, B and C. The develoument rates for roadway drivage are taken from PPO software for the typical conditions in G~ coal mmes. The maximum development rate is estimated for d roadway shapes to be 25 metns per day. This estimation means lower rates than can be achieved e.g. in USA or Auswlia but they are resulting from a standard workflow and minimum support requi-ts that are fixed for the high stress conditions.

22"d International Conference on Ground Control In Mlning and the single entry system of roadway use can be analysed for costs and efficiency.

The comparison of multiple entry systems VS w e of single entry roadways shows significant benefits in roadway development costs for multiple-entry systems. The benefits are depending on the develooina rate and therefore thev are influenced bv the roadwav size i d &e support density. EV& under high stress-conditions th; costs are less than half of the costs for re-used roadways.

Table 2: Comparison of costs and efficiency for Options A,B,C

The comparison of costs pa meter shows benefits for Option A that mans minimum roadway shape and high development rate. The costs are 41 % of the maximum costs required for Option C dcl l ig with re-used roadways. The high ca t s of Option C are mainly caused by high expenditure for support and additional - for roadside packages.

Looking at the specific wsts per ton coal extraction the cornpsrison gives a different result. This result is mostly influenced by the total length and the number of madways to be developed. Minirmun of specific costs are resulting from single entry for r&at mining of each panel.

l l ~ e comparison of efficiency has to take into account the risk of support system as well as the requirements resulting from future mining estivities.

The length of roadways in the whole inhenccs the benefits in the specific costs related to the extraction. Multiple entry system requires more than double length to be developed.

Peripheral needs mostly are responsible for re-use of madways. Esueciallv the influence of remnant oillars on the stnss situation for mining deep seams with multiple seam mining is importrmt.

ACKNOWLEDGMENTS

This work was par~ly supported by grants of DSK R&D program and by R&D program of ECSC European Conmiasion.

REFERENCES

[I] Bassier R., Schultheis H.: (2002): Improving Roadway Dfivage Performance by Systematic Planning, Documentation and Analysis. Kolloquium Rapid Mine

m e rockbolting support has a limited tolerance to defonnation Development, Aachen, 2002.pp 139-147 snd ~nscquently secondary support might be necessary for the use in advanced mining and for re-use of roadway. In deep [2] Winhaus H., Ruppel U. (2000): Rookbolting for Highly coal mining deformations of up to 20 % convergence at the I" face Stressed Roadways. 19th lntanational Conference on passage and up to 50 % at the second face are possible. For this Ground Control tn Mining Morgantown, WV, USA high deformations additional pmps or flexible bolting an used as 2000.pp.234-240. secondary sumon. The estimated costs for these additional . .. m a g l ~ do not include unscheduled support activities e.g. as a short-tam nsction on critical results of measumnent instrumntation.

For future mining activities in muh seam mining the remnant pillars in seam above gencrah a higher vertical stress. To prevent this shess concentration Option C must he chosen.

Anothm aspect is the required time for the development of the roadways. The slngle entry Option A and B include 4000 m or less of rodway length for each panel to be developed. With a man development rate of 12 m per day and 2 development units at the aam t i m it takes approximately 170 days. This matches the length of time required for extraction. Drivage of 7 roadways for two panels in the multiple entry system (Option A) takes 280 days with two development units 'Ihe tire for development is quite longer than the extrsaion time of one face with approximately 250 days.

CONCLUSIONS

Complex system of mining activities and roadway development require special tools for planning and analysis. Virtual Reality tools are used in German coal mining for planning, baining and prooess optimization. With these tools the multiple entry system

131 Lautsch T. (2001): Roofbolting in l k e Continents- a Cornpanson. Kolloquium Roofbolting in Mining, Aachen, 2001.pp 59-76.

[4] Griesenbrock P. Hucke, A., Studeny, A., and Wittbaus, H.: Numnical and Physical Modeling as Planning Tools for Rockbolted Roadways. Zlst International Conference on Ground Control in Mining Morgantown, WV, USA 2002. pp. 195-200.

151 Opolony K., Wittbaus H.: Re-Use of Rectangular Bolted R o a m in a Cover Depth > 1000 M. 21st International Conference on Gmund Control in Mining Morgmtown, WV, USA 2002.pp.53-57.

[6] Bmdt K., Cassie J.: Rookbolted Support of R e w Longwall Gateroads at I000 m Depth- A Case History. 21 st International Conference on Ground Control in Mining Morganmwn, WV, USA M02.pp.179-188.

[q RoBmann M., Badia W.: Planung. Simulation und Echtzcitdarstellung von Raessen im Steinkohlenhgbau untR EinsaP von 'Tirlueller Realit&", G l ~ k a u f 138 (2002) Nr. 12, Verlag GlUckauf, Essm.

[8] NN: Operating manual for the PPO S m k e Program. Deutsche Montan Tecbnologie, Esscn.