Abstract: A process for adsorbing gold from a leach pulp by means of activated carbon is described in which the leach pulp (the leach solution together with the subdivided gold bearing ore) is diluted to a specific gravity of less than that of the activated carbon and is subsequently passed upwardly through a multistage liquid/solid contacting column. The contacting column is of the type having perforated plates or trays defining a series of vertically adjacent stages and the operation of the column has a cycle which includes a first part during which upward flow of diluted pulp fluidizes the activated carbon, a second part in which the carbon is allowed to settle on the trays and a third part during which a reverse flow of diluted pulp carries carbon downwardly through the column from one stage to another. In the third part of the cycle, loaded carbon is removed from the lowermost stage and treated to recover adsorbed gold therefrom.

Abstract: A liquid/solid contacting column and method of operating same is provided. The column is of the type in which a vertical series of stages is defined by vertically spaced perforated plates or trays which allow for forward flow up the column during which solid adsorbent in a fluidized state is contacted by liquid flowing up the column, and flow of solid adsorbent and liquid down the column during a reverse flow part of the operating cycle. The column is provided with outlet means in the form of one or more ports or ducts for a stream of liquid and solid adsorbent from the space above the lowermost plate or tray and wherein such outlet means is located at a predetermined height above said lowermost plate or tray.

Abstract: The invention provides a magnetic separator for the separation of a fluid mixture into a more magnetic portion and a less magnetic portion wherein the magnetic field generator comprise a pair of solinoid coils located opposite each other and between which a conveyor assembly carrying a matrix of magnetic elements and the fluid material to be treated passes during use of the magnetic separator.

Abstract: A process is provided for the production of magnesium from magnesium oxide, generally in the form of calcined dolomite, in which magnesium vapor is produced in a heated reaction zone from solid reactants fed substantially continuously to such reaction zone. The solid reactants include a reductant and optionally a slag forming agent, preferably ferrosilicon and alumina respectively. The reaction zone is heated by a thermal plasma, the electrical current of which includes the furnace bath as an integral part of it. The plasma forming gas is preferably argon.

Abstract: A method of regenerating strong-base anion exchange resins which have been used in the extraction of complex anions followed by elution with a thiocyanate strip solution is provided. The method involves the use of ferric ions in a regenerating solution together with a substitute anion for attachment of the resin, the regeneration taking place under conditions in which ferric-thiocyanate complex cations are formed and washed from the resin by the regenerating solution. The thiocyanate can be recovered by neutralizing the regenerating solution to precipitate ferric hydroxide and leave thiocyanate in solution.

Abstract: A method of treating ferromanganese alloys in a suitable reactor wherein the feed material is heated by a transferred-arc thermal plasma and is fed directly to the reactor bath. Accordingly, the molten bath defines a reaction zone and at least a part of the molten bath defines a lower electrode surface for the arc. In particular, ferromanganese alloy fines may be remelted to form a physically more massive form of the alloy and additionally may be refined by the addition of suitable metal oxides to yield a product wherein the content of at least silicon or carbon is lowered.

Abstract: A process for the extraction of metal values, in particular divalent metal ions such as copper, nickel, zinc, cobalt and manganese from aqueous solutions thereof which may be well in the acid range for example of pH 2 to 4. Extraction is effected using known organophosphorus or carboxylic acid extractants but in combination with non-chelating oximes, preferably of aldehydes wherein the alpha-carbon atom is primary or secondary. A synergistic effect between the extractant and oxime enables extraction to take place at a lower pH than heretofore thereby saving in acid and neutralizing agents in many instances.

Abstract: A thermal plasma generating electrode assembly of the type having a central, water-cooled electrode and an outer sheath defining therewith a path for gas is provided. The sheath is made as a non-water cooled sheath of a high melting, electrically conductive material to avoid damage to the electrode as a result of stray arcing by attracting such stray arcing to the sheath rather than the electrode. In addition the electrode can be retractable within the sheath to enable the latter to be employed for making initial electrical contact with the co-operating electrode of opposite polarity for the purposes of "striking" or initiating the arc upon start-up.

Abstract: A process for the production of ferrochromium by smelting chromite ore and in which ferrochromium fines may form a part of the feed materials, or for the further treatment of ferrochromium fines alone, in each case in the presence of a limited amount of carbonaceous reductant, is provided. The amount of reductant is generally limited to a maximum of 150% of the stoichiometric amount required for reduction of all the chromium and iron to metal or carbide form and to produce the required level of silicon in the product (normally 2 to 4%). The process is carried out by feeding the preferably premixed feed materials to a liquid slag phase in the bath of the furnace at a rate chosen to maintain the molten state and temperature of such material. Oxygen is substantially excluded from the reaction zone which is heated by a transferred arc thermal plasma.

Abstract: A process for the refining of high carbon ferrochromium metal in which the ferrochromium metal is refined, in the liquid state, with liquid metal oxide, generally including oxide fines. The heating is carried out in a transferred arc thermal plasma with substantial exclusion of carbon; although a consumable carbon electrode can be employed to generate the plasma. The ferrochromium metal is preferably premixed with the required oxides and fluxes and the feed is added to the furnace bath at a rate controlled to ensure that the slag and metal remain molten and at a chosen temperature.