Abstract: A self-propelled mining vehicle is disclosed which is self supporting above the floor of a mine tunnel. The vehicle is adapted to be supported above the floor of the mine tunnel such that conventional rock removing vehicles are operable therebeneath. The vehicle has an elongated carrier or frame having a mining apparatus mounted at one end. Four transverse bracing cap assemblies are included, and are adapted to engage side walls of a mine tunnel for supporting the carrier above the tunnel floor. Four suspension links extend downwardly from each cap assembly for suspending the carrier beneath the cap assemblies. The suspension links are longitudinally movable with respect to the carrier and cap assemblies for causing movement of the carrier and cap assemblies relative to one another. With such a construction, the vehicle is able to hold its position above a mine tunnel floor without contacting the floor.

Abstract: A process for producing metallic lead and silver from materials such as ores and concentrates containing the corresponding sulfides and particularly a mixture of minerals such as galena and tetrahedrite in which process the minerals are initially roasted under neutral conditions which include a non-oxidizing or even slightly reducing atmosphere at an elevated temperature for a time equivalent to about 1.5 hours at about 550.degree.-600.degree.C. to produce a roasted mineral product in which the roasting causes certain unidentified changes but with the resulting roasted product being more easily leachable so that the process of removing the silver and lead can be greatly simplified.