Uchalinsky Mining and Processing Integrated Works JSC (Uchaly, Russia):

Baranov S. V., Director of Underground Mine, e-mail: upr_baranov_sv@ugok.ru
Goltsov V. V., Chief Engineer of Underground Mine
Sharipov I. Kh., Deputy Head of Production and Technical Department for Blasting
Semiryakov V. B., Head of Engineering Department of Underground Mine

Uralmekhanobr JSC (Ekaterinburg, Russia):

Kotenkov A. V., Deputy Head of Department for Mining Science

Currently Uchaly deposit represented by a steep lenticular continuous sulphide ore body is mined with the combination of open and underground methods. In the South pitwall (South lens out) beyond the ultimate pit limits, the geological ore reserves amount to 90 thou t. At the stage of depletion of the open-pit mine, it was decided to extract the said geological reserves. It was required to find a technology such that to prevent from the pit wall caving, mine safety inhibition, loss of reserves and significant dilution of the extracted ore. The satisfying technology was developed—the extraction site was divided into two mining stages: the first stage was above Level 300m and the second stage was the Level 300–340m; mining was carried out with open chambers toward the open-pit mine. Stage I ore was stepwise broken toward the compensation chamber 34-3yu, preliminary mined-out without backfilling on Level 300–340m (steps 1–4), and toward the open-pit mine (steps 5–6). Ore handling was executed by remote-control load-haul-dumpers in haulage roadways in the chamber 34-3yu. After stage I ore had been extracted, the adjacent rock mass partly lost its stability, and the unbackfilled chamber was filled with caved rocks from lower benches of the open-pit mine. On the whole, the pit wall retained its stability. Stage II ore extraction in sublevel of Level 300–340m (between the stripped area and the chamber 34-3yu filled with caved barren rock) involved a protection pillar set at the interface with the barren rock. The ore was stepwise (steps 1–2) broken toward the open-pit mine and handled by the remote-control load-haul-dumpers. The ore in the protective pillar at the caved barren rock in the chamber 34-3yu was broken at the final step (step 3) by a directed blast toward the open-pit mine. Thus, the South lens-out reserves were extracted with keeping the south pit wall in stable state.

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