Fosforiidi allmaakaevandamise tehnoloogilise skeemi valik Kabala maardla tingimustes [Bakalaureusetöö. Juhendaja: T. Tomberg]

The topic of the thesis is to select and elaborate on the technology for underground mining of phosphate ore in conditions of Kabala deposit.

Kabala deposit contains ca 600 million tonnes of phosphate ore. The minimal thickness of the bed containing phosphate ore is 6,4 m, maximum 12,10 m and average 7,6 m. The deposit is located near the city of Rakvere - around 15 km.

Underground mine will be opened with a vertical shaft. Room- and pillar mining with backfilling will be used for the extraction of the ore. Extraction itself is carried out with method of drilling and blasting. Shafts and rooms will be supported by anchors and arched metal frames. Mixture, made of oil shale ash and enrichment residue, is used for the backfilling. Transport is carried out by using undergrounds loaders and belt convyor.

Current estimated mining cost of phosphate ore is 9,40 euros per ton. Present world market price (90 euros / ton) makes phosphate ore unprofitable to mine. The author´s assessment is that the mining may become profitable after market price reaches at least 250 euros per ton.