Abstract: An apparatus for producing fused silica includes at least one anodic plasma arc electrode and at least one cathodic plasma arc electrode adjustably arranged with respect to one another so that the plasma arcs formed thereby couple together to form a plasma arc coupling zone. A feedstock material is fed into a region between the electrodes or to a region near the electrodes where the plasma arc coupling zone is formed. A platform is located beneath the plasma arc coupling zone to receive the silica product which is formed in the plasma arc coupling zone. The platform may be rotated about its axis and move up and down along its axis. A cooling device also may be included with the platform. The plasma anode torch used in the apparatus includes a cylindrical nozzle with a non-consumable, copper, blunt ended electrode disposed therein. A channel is provided between the electrode and the nozzle wall to allow the plasma gas to pass through the torch.

Abstract: Method for the production of fused silica in which a particulate silica feedstock material is passed from a silica feed tube through or near a plasma arc coupling zone in which at least two plasma arcs of opposite polarity are coupled, thereby raising the temperature of the feedstock material and collecting the material as fused silica.

Abstract: A method of melting materials at power densities in excess of 25 KW/ft.sup.2 of area within the metal shell of a melting vessel which method consists essentially of continuously feeding the material to be melted to a plasma arc furnace which is equipped with at least two transferred arc plasma electrodes and with means to rotate at least the portion of the furnace containing the material to be melted, melting the said feedstock material using the at least two transferred arc plasma electrodes whilst rotating at least the rotatable portion of the furnace containing the material to be melted and continuously discharging the material which has been melted from the furnace.Apparatus for melting materials under power densities of greater than 25 KW/ft.sup.2 is also disclosed.

Abstract: A process for the recovery of gold from a refractory of non-refractory gold containing concentrate which contains sulphide minerals, which process comprises the steps of:(i) heating the gold containing concentrate to a temperature of above 1150.degree. C. in order to thermally decompose the sulphide minerals contained therein, and(ii) subjecting the thermal decomposition product obtained from step (i) to reaction with oxygen in a plasma arc furnace maintained at a temperature of above 1150.degree. C.

Abstract: Forming a blood trace of predetermined length and width on a flexible supporting strip by depositing a blood sample on the strip, contacting the sample with a trace tip carried by an adjacent strip and moving the sample relative to the tip through a predetermined course to control the width and length of said trace.