Abstract: A method of treating sulphidic mattes containing from 5% to 60% iron; from 15% to 40% sulphur together with soluble non-ferrous metals such as copper, cobalt, nickel and zinc and also optionally insoluble non-ferrous metals which term includes platinum group metals gold and silver by a leaching process to effect substantial separation of the non-ferrous metals from iron as well as from insoluble residue material. The matte is contacted in a finely subdivided form with sulphate in acid medium at a temperature of from 70.degree. C. to 120.degree. C. and an oxygen partial pressure of from 50kPa to 1,000kPa. The quantity of sulphate present is at least the stoichiometric amount required for dissolving the soluble non-ferrous metals present but is limited to ensure that a substantial proportion of iron which dissolves simultaneously with the soluble non-ferrous metals precipitates out as it is replaced by dissolving non-ferrous metals.

Abstract: A polymeric ion exchange resin of the cross-linked type in which the active groups may be constituted either wholly or in part by an imidazole group which is, in turn, attached directly to a cross-linked, polymerized vinyl backbone. The optional substituents on the imidazole ring include optionally substituted pyridyl, imidazolyl or amino groups which can be substantially known type. A method of preparation of such resins includes the provision of at least the imidazole ring on the vinyl monomer before polymerization thereof. The active groups may be added or modified after polymerization with a cross-linking agent.

Abstract: A process for treating zinc sulphide materials wherein the sub-divided material is firstly leached, under pressure at less than 119.degree. C., with a sulphate leach solution low in sulphuric acid and having a high iron content together with zinc and impurities in a manner causing iron to precipitate and subsequently leaching the residue and redissolving the iron precipitate with spent electrolyte containing regenerated sulphuric acid resulting from the treatment of the leach liquor obtained from the first leach step and wherein the leach solution from the subsequent leach step constitutes the starting leach solution for the first leach step. The second leach step is carried out in two phases; a first leach phase conducted at elevated pressure and elevated temperature (less than 119.degree. C.) in the presence of oxygen and a second phase at atmospheric pressure and without the supply of free oxygen to the leach solution.

Abstract: A method of operating a multi-phase arc furnace by controlling the required values in the secondary circuits comprising the measurement and computation of such values from selected primary and/or secondary circuit measurements excluding secondary phase voltages measured with respect to the furnace bath, computing the desired values for effecting control of the furnace on the basis of an assumption that the behavior of the inductances of the secondary circuits is predictable during other variations in the particular furnace, and, applying such computed values to the furnace control optionally subject to any desired limits imposed on the variables of the furnace.

Abstract: A process for treating zinc sulphide materials wherein the sub-divided material is firstly leached, at less than 119.degree. C., with a sulphate leach solution, low in sulphuric acid and having a high iron content together with zinc and impurities in a manner causing iron to precipitate and subsequently leaching the residue and re-dissolving the iron precipitate with spent electrolyte containing regenerated sulphuric acid resulting from the treatment of the leach liquor obtained from the first leach step and wherein the leach solution from the subsequent leach step constitutes the starting leach solution for the first leach step.

Abstract: A magnetic separator comprising an annular housing rotatable about a generally vertical axis and adapted to contain a matrix therein composed of a plurality of separate elements of magnetic material said annular housing being optionally sub-divided into a plurality of partitions around the circumference thereof, outlets for elements constituting the matrix in the lower region of the said partitions, means for releasably opening said outlets at one or more required positions around the circumference of the housing, means for cleaning elements constituting said matrix and which issue from said outlet in use, and further means for returning cleaned elements to the annular housing after cleaning.

Abstract: An arc furnace electrode slip monitoring device comprising a frame-work adapted to be held fixed relative to a movable electrode, a movable unit supported by the frame-work and movable in reciprocating manner along a predetermined path which is substantially parallel to the direction of movement of an electrode. An electrode engaging member is provided in the movable unit movable transverse to the direction of movement of the movable unit to firmly engage an electrode during movement of the movable unit in one direction but to be disengaged therefrom during movement in the opposite direction. The slip monitoring device further includes detecting apparatus for detecting the position of the movable unit along its path of movement, and further apparatus for counting the number of reciprocal movements executed by the movable unit.

Abstract: An ion exchange resin having functional groups of the formula :- ##STR1## wherein :- A and B, independently of each other, represent groups forming together with the attached carbon and nitrogen atoms, an optionally substituted five or six membered heterocyclic ring which may embody a further heteroatom and wherein at least one of such heterocyclic rings is an aromatic ring; R* may be totally absent or it may represent an optionally substituted alkyl radical and Z represents a resin to which the functional groups are attached.

Abstract: A process for the dissolution of precious metal values in a concentrate thereof wherein the concentrate is caused to alloy with aluminum and the alloy is then leached in at least two steps, the first of which is to remove base metals and in the second of which the precious metals are dissolved using hydrochloric acid and chlorine gas or nitric acid as an oxidant.

Abstract: A process for the recovery or purification of rhodium wherein:(i) a solution of a soluble anionic rhodium complex is treated to precipitate insoluble pentammino-chloro rhodium dichloride;(ii) the rhodium is redissolved in the form of the equivalent hydroxo complex cation;(iii) the solution is treated to precipitate the nitrate salt of the pentammino-nitro rhodium complex;(iv) the precipitate is converted to pentamminochloro rhodium dichloride; and,(v) the latter is calcined to form rhodium metal.

Abstract: A method of recovering iridium from a solution thereof containing rhodium and impurities in the form of base metals comprising; oxidizing the iridium to the Ir(IV) oxidation state in an acid solution in the presence of chloride ions; removing the iridium chlorocomplexes formed using a suitable anion-exchange resin; washing the resin; treating the iridium with an aqueous solution of sulphur dioxide which is substantially free of chloride ions; and thereafter eluting the iridium complex formed from the resin using a suitable eluant.

Abstract: A process for the separation of platinum and/or palladium from acid starting solutions containing the chlorocomplexes thereof together with other platinum group metals and/or base metals in 0.01 to 2M acid solutions comprises contacting the starting solution with a suitable solvent extractant; the solvent extractant being substantially water insoluble, carried in an organic phase and comprising functional groups of the formula R.sub.2 N--CH.sub.2 --COOH wherein R is a long-chain alkyl group and thereafter separating the two phases and recovering the extracted platinum or palladium or both from the loaded solvent extractant.

Abstract: A process for the separation or purification of ruthenium from solutions thereof comprising conversion of the ruthenium to nitrosylruthenium complex with the ruthenium in the Ru.sup.+2 oxidation state; conversion of the nitrosylruthenium complex to a nitrosylruthenium chlorocomplex and any other platinum group metals to chlorocomplexes; and the removal of the nitrosylruthenium chlorocomplex from solution using a suitable liquid or resin anion exchanger.

Abstract: A method of x-ray diffraction determination of the concentration of predetermined minerals in slurries comprises presenting a sample in the form of a stream of slurry having areas of two opposing sides thereof unsupported by any boundary walls therefor, and making required determinations through the unsupported areas of the stream of slurry using x-radiation of a suitable wavelength.

Abstract: A method of separating gold from palladium or at least one of gold and palladium from solutions containing the chloride complexes of at least the relevant ones of these metals together with other platinum group metals and wherein base metals may be present in the solution said method comprising contacting the solution for a sufficient length of time to result in extracting of substantially all the required gold and for palladium values present therein, with a suitable quantity of a water insoluble non-volatile solvent extractant in an organic phase and having functional groups of the formula R.sup.1 --S--R wherein R.sup.1 and R may be the same or different and have a carbon atom thereof joined directly to the sulphur atom; R.sup.1 and R being chosen so that neither of them have active functional groups capable of acting as ion exchangers or complexing groups and thereafter separating the two phases and recovering the extracted gold and palladium.

Abstract: The invention is concerned with an improvement of the process and apparatus disclosed in British patent specification 1 070 251. Slids pass in countercurrent to a liquid through a number of stages. Liquid flow is cyclically pulsed so that during one part of a cycle the liquid flows upwardly, during another part the solids settle in the liquid and in still a further part solids pass between the stages and out of the last stage in countercurrent to the liquid flow. The improvement of the present invention is that the last stage is so valved that less solids can pass out of the system than can pass between the stages.