Abstract: Flotation apparatus (10) for removing finely divided bodies of an insoluble substance dispersed in an aqueous medium, such as oil and solids dispersed in water, comprises a vertical flotation column (12) having a feed inlet (14) and an outlet (22) for the aqueous medium, a sparging system (16) for generating gas bubbles rising upwardly in the aqueous medium to capture and raise the finely divided bodies of the insoluble substance to the surface of the aqueous medium in the column to form a layer (31) of the insoluble substance on the surface of the aqueous medium, a launder (18) for receiving an overflow of the insoluble substance and an outlet (20) for the insoluble substance in the launder. The apparatus (10) can be used in both countercurrent and co-current fashion. In a particular embodiment, the apparatus includes a mechanism for the intermittent dumping of the layer (31) of insoluble substance from the column (12).

Abstract: Flotation apparatus (10) for removing finely divided bodies of an insoluble substance dispersed in an aqueous medium, such as oil and solids dispersed in water, comprises a vertical flotation column (12) having a feed inlet (14) and an outlet (22) for the aqueous medium, a sparging system (16) for generating gas bubbles rising upwardly in the aqueous medium to capture and raise the finely divided bodies of the insoluble substance to the surface of the aqueous medium in the column to form a layer (31) of the insoluble substance on the surface of the aqueous medium, a launder (18) for receiving an overflow of the insoluble substance and an outlet (20) for the insoluble substance in the launder. The apparatus (10) can be used in both countercurrent and co-current fashion. In a particular embodiment, the apparatus includes a mechanism for the intermittent dumping of the layer (31) of insoluble substance from the column (12).

Abstract: A tandem drive unit (24) on a flexible conveyor belt (12) comprises a primary drive pulley (20) and a secondary drive pulley (22) driven by a primary drive motor (26, 28) and a secondary drive motor (34) respectively. The primary drive motor (26, 28) has a predetermined full-load speed and the secondary drive motor (34) has a full-load speed which is not greater than a theoretical speed value for the secondary drive pulley (22) obtained by calculating the speed differential between the primary and secondary pulleys as a function of the horsepower applied to the first and secondary drive pulleys and the modulus of elasticity of the conveyor belt (12). Alternatively, a secondary drive motor with a predetermined full-load speed may be selected and the required full-load speed of the primary drive motor may be determined. A method of non-mechanically coupling a primary and a secondary drive pulley in a tandem conveyor drive of a conveyor belt is also provided.

Abstract: A process for the extraction of copper from a sulphide copper ore or concentrate comprises subjecting the ore or concentrate to a first leaching at an elevated temperature and pressure in the presence of oxygen and a lixiviant which comprises an acidic solution of chloride and bisulphate or sulphate ions to produce an insoluble basic copper sulphate. The basic copper sulphate so produced is leached in a second leaching preferably at atmospheric pressure with an acidic sulphate solution to dissolve the basic copper salt to produce a leach liquor containing copper sulphate in solution. The resulting leach liquor is subjected to solvent extraction to produce a copper concentrate solution and a raffinate comprising protons and bisulphate or sulphate ions in solution.

Abstract: A process for the extraction of copper from a sulphide copper ore or concentrate comprises the steps of subjecting the ore or concentrate to agitation leaching at an elevated temperature and pressure to obtain a resulting acidic leach liquor containing dissolved copper and reducing the acidity of the resulting acidic leach liquor by effecting percolation leaching of a bed of low-grade copper ore or granular rock with the acidic leach liquor. The agitation leaching is carried out in two stages, i.e. a first leaching step at an elevated temperature and pressure in the presence of oxygen and an acidic chloride solution as lixiviant and a second leaching step at atmospheric pressure with an acidic sulphate solution. In a preferred embodiment, the bed of low-grade copper ore or granular rock is in the form of a heap and the percolation leaching comprises heap leaching. Copper is extracted from the leach liquor by solvent extraction.

Abstract: A process for the extraction of copper from a copper ore or concentrate comprises first subjecting the ore or concentrate to agitation leaching at an elevated temperature and pressure in the presence of oxygen and water to obtain a resulting acidic leach liquor which contains dissolved copper. The acidity of the resulting acidic leach liquor is then reduced by affecting percolation leaching of a bed of low grade copper ore or waste rock with the resulting acidic leach liquor, whereby the pH of the leach liquor is raised, for example to a value of about 1.5 to 2. In a preferred embodiment the bed of low grade ore or waste rock is in the form of a heap and the percolation leaching comprises heap leaching.