Pressure differential mining tool
Pretreatment for fracturing coal seams
Process and apparatus for fragmenting rock and like material usi
Process for hydraulically mining coal
Process for hydraulically mining coal employing a cutting monito
Process for making general use of the earth's heat and obtaining
Process for separation of asbestos-containing material and preve
Process of and an arrangement for mining
Production of lignite from underground deposits
Pumpable product hydraulic mining apparatus and method