Abstract: An integrated pressure leaching, heap leaching process for recovering copper from sulphidic feed containing iron, arsenic, and copper. Aqueous feed slurry of the sulphidic feed is pressure oxidized to form a liquid phase containing free sulphuric acid and aqueous copper sulphate, and to precipitate arsenic as solid iron arsenic compounds. Treated slurry is withdrawn from the pressure vessel and the liquid phase is separated from the solids. Copper is recovered from the separated liquid phase and generates a solution enriched in acid and depleted in copper. At least a portion of this solution is neutralized in a copper heap leach to produce a PLS containing copper and reduced in acid. At least a portion of the heap leach PLS is neutralized to produce a solution further reduced in acid, and solids containing copper precipitates, followed by a liquid solid separation.

Abstract: An integrated pressure leaching, heap leaching process for recovering copper from sulphidic feed containing iron, arsenic, and copper. Aqueous feed slurry of the sulphidic feed is pressure oxidized to form a liquid phase containing free sulphuric acid and aqueous copper sulphate, and to precipitate arsenic as solid iron arsenic compounds. Treated slurry is withdrawn from the pressure vessel and the liquid phase is separated from the solids. Copper is recovered from the separated liquid phase and generates a solution enriched in acid and depleted in copper. At least a portion of this solution is neutralized in a copper heap leach to produce a PLS containing copper and reduced in acid. At least a portion of the heap leach PLS is neutralized to produce a solution further reduced in acid, and solids containing copper precipitates, followed by a liquid solid separation.

Abstract: Process for recovering one or both of copper and silver from a sulphidic feed containing iron, arsenic, copper and silver by pressure oxidizing an aqueous feed slurry of the sulphidic feed in a pressure vessel to form a liquid phase containing free sulphuric acid and aqueous copper sulphate, and to precipitate arsenic as solid iron arsenic compounds. The process includes operating the pressure vessel at a sufficiently low solids content to maintain a free acid level below 30 g/L in the liquid phase, and providing sufficient heat to maintain a temperature in the pressure vessel above 200° C. Copper metal is recovered from the liquid phase and/or silver may be recovered from the solids by cyanide leaching without the need for a jarosite destruction step.

Abstract: Process for recovering one or both of copper and silver from a sulphidic feed containing iron, arsenic, copper and silver by pressure oxidizing an aqueous feed slurry of the sulphidic feed in a pressure vessel to form a liquid phase containing free sulphuric acid and aqueous copper sulphate, and to precipitate arsenic as solid iron arsenic compounds. The process includes operating the pressure vessel at a sufficiently low solids content to maintain a free acid level below 30 g/L in the liquid phase, and providing sufficient heat to maintain a temperature in the pressure vessel above 200° C. Copper metal is recovered from the liquid phase and/or silver may be recovered from the solids by cyanide leaching without the need for a jarosite destruction step.

Abstract: A method and apparatus for comminuting particulate material by interparticle comminution in a bed of particles are disclosed. The apparatus includes a vertical roller mill with a horizontal grinding table rotating about a vertical mill axis. At least one grinding roller presses resiliently against a bed of particulate material on the grinding track and applies a compressive force. The geometry of the mill is such that the roller engages the bed of particulate material with a substantially pure rolling action. This minimizes shear forces applied to the particle bed and minimizes the reduction of fines.

Abstract: A method and apparatus for comminuting particulate material by interparticle comminution in a bed of particles are disclosed. The apparatus includes a vertical roller mill with a horizontal grinding table rotating about a vertical mill axis. At least one grinding roller presses resiliently against a bed of particulate material on the grinding track and applies a compressive force. The geometry of the mill is such that the roller engages the bed of particulate material with a substantially pure rolling action. This minimizes shear forces applied to the particle bed and minimizes the reduction of fines.

Abstract: A method and apparatus for comminuting particulate material by inter-particle comminution in a bed of particles are disclosed. The apparatus includes a vertical roller mill with a horizontal grinding table rotating about a verticle mill axis. At least one grinding roller presses resiliently against a bed of particulate material on the grinding track and applies a compressive force. The geometry of the mill is such that the roller engages the bed of particulate material with a substantially pure rolling action. This minimises shear forces applied to the particle bed and minimises the reduction of fines.

Abstract: The invention provides a method and installation for processing heterogeneous value bearing material by pressure comminution. The material is compressed in a bed of particles, at low pressures and at low bulk material densities, and preferably no more than is necessary to liberate the desired values, thereby to minimise the formation of fines. The compressive bed pressure applied to the material does not exceed 300 MPa, and the process is preferably operated in an open circuit mode. Surprisingly, these measures lead to enhanced liberation of values compared with conventional comminution techniques.

Abstract: The invention provides a method and installation for processing heterogeneous value bearing material by pressure comminution. The material is compressed in a bed of particles, at low pressures and at low bulk material densities, and preferably no more than is necessary to liberate the desired values, thereby to minimise the formation of fines. The compressive bed pressure applied to the material does not exceed 300 MPa, and the process is preferably operated in an open circuit mode. Surprisingly, these measures lead to enhanced liberation of values compared with conventional comminution techniques.

Abstract: The invention provides a method and installation for processing heterogeneous value bearing material by pressure comminution. The material is compressed in a bed of particles, at low pressures and at low bulk material densities, and preferably no more than is necessary to liberate the desired values, thereby to minimise the formation of fines. The compressive bed pressure applied to the material does not exceed 300 MPa, and the process is preferably operated in an open circuit mode. Surprisingly, these measures lead to enhanced liberation of values compared with conventional comminution techniques.