POBOLJŠANJE METODE OTKOPAVANJA U LEŽIŠTIMA BOKSITA

The underground bauxite excavation in Yugoslavia is getting more important recently due to gradual exploitation of shallow deposits. The main excavation method is sublevel caving method. That technology of exploitation is characterized by high excavation loosses reaching even to 50% due to mixing of bauxite with waste. By beds with competent limestone roof which are not liable to direct caving are formed unplanned open spaces so the work safety is often dangercd by sudden caving. That was the reason for carrying out the observations in situ and investigations on mathematical models to define boundary of excavated space stability. This investigation were the basis for the new conception of further excavation of the »Jukići-Didare« mine with the application of even three exploitation methods maximally adapted to the characteristics of the remaining part of deposit.Zbog postupnog iscrpljivanja plićih ležišta, jamska proizvodnja u SFR Jugoslaviji dobiva sve više na važnosti. Podetažna otkopna metoda predstavlja osnovnu metodu. Karakteriziraju je visoki otkopni gubici i do 50% zbog miješanja boksita s jalovinom, dok se kod ležišta s čvrstom neposrednom krovinom stvaraju veliki otvoreni otkopani prostori koji zbog opasnosti od iznenadnog zarušavanja ugrožavaju sigurnost rada. Da bi se definirala granica stabilnosti takvih prostora obavljena su opažanja in situ i istraživanja na matematičkim modelima aplikacijom metode konačnih elemenata, na osnovi kojih je postavljena nova koncepcija daljnjeg otkopavanju jame Jukići-Đidare, Dalmatinskih rudnika boksita — Obrovac, uz, primjenu čak tri otkopne metode maksimalno prilagođene karakteristikama preostalog dijela ležišta

THE IMPROVEMENT OF THE EXCAVATION METHODS IN BAUXITE DEPOSITS

The underground bauxite excavation in Yugoslavia is getting more important recently due to gradual exploitation of shallow deposits. The main excavation method is sublevel caving method. That technology of exploitation is characterized by high excavation loosses reaching even to 50% due to mixing of bauxite with waste. By beds with competent limestone roof which are not liable to direct caving are formed unplanned open spaces so the work safety is often dangercd by sudden caving. That was the reason for carrying out the observations in situ and investigations on mathematical models to define boundary of excavated space stability. This investigation were the basis for the new conception of further excavation of the »Jukići-Didare« mine with the application of even three exploitation methods maximally adapted to the characteristics of the remaining part of deposit