Glencore Technology Pty Limited

Glencore Queensland Limited

Paul Benjamin Voigt

Ahmad Ghahreman

Michael Matthew Hourn

Duncan Turner

Daniel Mallah

A process for leaching minerals that contain metal sulphides and one or more precious metals or precious metal compounds, the process comprising the steps of a first leaching step to leach the minerals under oxidative conditions at a pH of less than 4 to form a slurry or pulp, the slurry or pulp comprising a solid phase containing unreacted components, solid reaction products and elemental sulphur, and subjecting the slurry or pulp or solid residue from the first leaching step to a second leaching step comprising oxidative leaching at pH of at least 9.0 to thereby form thiosulphate, whereby the thiosulphate leaches precious metal from the solid residue.

Sulphide oxidation in leaching of minerals

A process for leaching a mineral particulate material comprising the steps of feeding the mineral particulate material to a leaching step () in which at least one valuable metal in the mineral particulate material is leached into a leach solution to form a pregnant leach liquor and a solid residue containing undissolved mineral matter, the leaching step being conducted under conditions such that elemental sulphur is formed in the leaching step, wherein beads or particles that take up elemental sulphur are added to the leaching step such that elemental sulphur is taken up by or collects on the beads or particles, and separating the beads or particles from the pregnant leach liquor and the solid residue. The beads or particles may be treated to remove sulphur and the beads or particles are returned to the leaching step. Alternatively the mineral doesn't need to comprise a soluble component and can be a refractory sulphide of iron and/or arsenic containing precious metals that require oxidation before downstream conventional processes such as cyanidation.

Process for leaching a mineral particulate material

A method for treating a mineral composition containing iron, arsenic or other Group VA compounds comprises milling the mineral composition to a particle size of Pof less than 25 &#x3bc;m and leaching the mineral composition in the presence of lime and/or limestone and a soluble alkali complexing agent and in the presence of an oxygen containing gas at a pH in the range of from 3.5 to 6.

Leaching of minerals

A method for recovering zinc from slag derived from lead smelting comprises subjecting the slag to a leaching step under conditions in which zinc is dissolved into solution and silica present in the slag dissolves and re-precipitates in a form that is readily separable from liquid, and recovering zinc from the solution. The slag may be subjected to leaching in at least two stages in which in a first leaching stage only part of the zinc is removed from the slag and further zinc leaching from the slag occurs in a second stage to form a pregnant leaching solution and recovering zinc from the solution. The method may be used to remove SOfrom a gas stream by using the SO-containing gas stream to leach a slurry of the slag.

Recovery of zinc from lead slag

A method of precipitating a zinc containing solid from an acidic solution containing dissolved zinc and magnesium comprising contacting the solution with a calcium containing neutralizing agent to raise the pH of the solution to 4.5 to 7.5 at a temperature of from 70 to 95&#xb0; C. to thereby precipitate a solid zinc containing material and gypsum without causing substantial precipitation of magnesium, and separating the zinc containing material from the gypsum.

Growing community of inventors

Nundah, Australia

Paul Benjamin Voigt