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WATER JET CONFERENCE - Waterjet Technology Association

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The hydraulic drive of the haulage system was adjusted to a value of F K = 370 kN<br />

for the pulling force acting on the chain. The average value as recorded by measurement<br />

was of approximately F K = 340 kN.<br />

The force analysis leads to the result, that the power requirement of the high<br />

pressure pumps could be reduced from P = 300 kW to P = 220 kW and the water flow<br />

could be reduced from V = 226 l/min to V = 170 l/min (Fig. 3).<br />

A main target of the underground trials was to obtain a maximum incremental<br />

area of face advance (web x travelling speed). The chain traction effort and the web s =<br />

0.4 m were kept constant for the experimental version. The travelling speed V M,<br />

however, was adapted to the prevailing coal hardness. Fig. 4 shows the optimum working<br />

configuration. At a web of s = 0.4 m a travelling speed of V M = 0.4 m/s was obtained.<br />

This corresponds to an incremental area of face advance of 9 6 m 2 /min.<br />

The corresponding values of the most efficient conventional winning machines<br />

(ploughs, shearer loaders) read 7.5 and 6.0 m 2 /min respectively for the same coal<br />

hardness.<br />

Besides these high winning performances also a considerably better particle-size<br />

distribution of the raw coal was achieved (Fig. 5).<br />

The operation mode of the machine enabled a very careful handling of the raw<br />

coal which eventually resulted not only in a better particle-size distribution but also in<br />

definitely less dust production. Comparative measurements have shown that the quantity<br />

of dust released corresponds to only approximately 30% of the dust produced by a<br />

shearer loader in the same seam.<br />

Surprisingly, the moisture content of the coal was only half as high as the one<br />

recorded for comparison in a shearer-loader face. Consequently, the moisture content of<br />

the raw coal did not cause any problem to experimental operation.<br />

In trial operation problems were encountered above all with respect to loading.<br />

The experimental unit left only little clearance underneath the machine frame so that the<br />

broken off coal could not be removed from underneath the machine. Furthermore the<br />

electrical energy supply as well as the low pressure water supply recorded frequent<br />

trouble. In this configuration the supply system a modified version of the supply system<br />

used for shearer loaders - turned out to be ill-suited.<br />

DEVELOPMENT OF THE <strong>JET</strong>-MINER<br />

Concept<br />

After successful trials run with the experimental version the development of the<br />

first Jet-Miner prototype was started in cooperation of Ruhrkohle AG, M.A.N.-GHH<br />

Sterkrade, and Bergbau-Forschung GmbH.<br />

238

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