A method of recovering a metal from a low-grade ore which is subjected to cyanide leaching to produce a PLS which contains a metal cyanide which is removed from the PLS by ultrafiltration and nano-filtration, and then acidified and sulphidised to produce a metal sulphide from which the metal is extracted, and hydrogen cyanide which is recycled to the cyanide leaching step.

A method of recovering a metal from a low-grade ore which is subjected to cyanide leaching to produce a PLS which contains a metal cyanide which is removed from the PLS by ultrafiltration and nano-filtration, and then acidified and sulphidised to produce a metal sulphide from which the metal is extracted, and hydrogen cyanide which is recycled to the cyanide leaching step.

The present invention relates to a method for extracting base and precious metals, all contained in refractory minerals, using aqueous media. The aim is to replace the current flotation/smelting-method for extracting minerals in Chilean and global mining or classical leaching with a method comprising a simple and robust pre-treatment that leads to solubilisation of the refractory matrices thereof. The method consists of mixing the mineral (Cu2S, CuS,CuFeS2, Cu5FeS4, FeS2, FeAsS.NiS, (Ni,Fe)xSy), ground to an appropriate size (2.5 centimetres), with a specific dose of solid reagent in a rotary agglomeration drum and then adding slightly acidified water to obtain a defined water content (5-8%) depending on the type of gangue contained in the metal-containing solid, thereby forming an agglomerate that will form a heap, which is subsequently allowed to stand for a period of several days (20-60 days), during which the conditions required to transform the refractory matrix into a highly soluble solid will be generated. Finally, appropriately regulated irrigation is applied, thus resulting in extraction of the metal by simple aqueous washing. In essence, the method achieves maximum transformation of the original refractory mineral into a highly soluble solid salt during a step prior to the conventional leaching process. Thus, the metal will be contained in a solid with a much higher solubility than the original matrix, therefore the dissolution thereof will be faster, more efficient and require a minimal use of consumables and reagents.

The present invention relates to a method for extracting base and precious metals, all contained in refractory minerals, using aqueous media. The aim is to replace the current flotation/smelting-method for extracting minerals in Chilean and global mining or classical leaching with a method comprising a simple and robust pre-treatment that leads to solubilisation of the refractory matrices thereof. The method consists of mixing the mineral (Cu2S, CuS,CuFeS2, Cu5FeS4, FeS2, FeAsS.NiS, (Ni,Fe)xSy), ground to an appropriate size (2.5 centimetres), with a specific dose of solid reagent in a rotary agglomeration drum and then adding slightly acidified water to obtain a defined water content (5-8%) depending on the type of gangue contained in the metal-containing solid, thereby forming an agglomerate that will form a heap, which is subsequently allowed to stand for a period of several days (20-60 days), during which the conditions required to transform the refractory matrix into a highly soluble solid will be generated. Finally, appropriately regulated irrigation is applied, thus resulting in extraction of the metal by simple aqueous washing. In essence, the method achieves maximum transformation of the original refractory mineral into a highly soluble solid salt during a step prior to the conventional leaching process. Thus, the metal will be contained in a solid with a much higher solubility than the original matrix, therefore the dissolution thereof will be faster, more efficient and require a minimal use of consumables and reagents.

A process for leaching a mineral particulate material comprising the steps of feeding the mineral particulate material to a leaching step (10) 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.

A process for leaching a mineral particulate material comprising the steps of feeding the mineral particulate material to a leaching step (10) 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.

Described herein are compositions and methods for preferentially separating mercury from a metal product where both are present in an ore leachate. The separation is accomplished by adding a precipitating agent and a coagulant to an ore leachate followed by separating a mercury-laden precipitate therefrom to collect the treated leachate. The treated leachate includes about 0 to 50% by weight of the mercury and about 90% to 100% by weight of the metal product present in the ore leachate. In embodiments, the method further includes adding a flocculant to the ore leachate prior to the separating of the mercury-laden precipitate.

Described herein are compositions and methods for preferentially separating mercury from a metal product where both are present in an ore leachate. The separation is accomplished by adding a precipitating agent and a coagulant to an ore leachate followed by separating a mercury-laden precipitate therefrom to collect the treated leachate. The treated leachate includes about 0 to 50% by weight of the mercury and about 90% to 100% by weight of the metal product present in the ore leachate. In embodiments, the method further includes adding a flocculant to the ore leachate prior to the separating of the mercury-laden precipitate.

A solution for leaching metals from clay containing ore and a method of leaching ore is described. The solution comprises a cyanide; a wetting agent; and a clay stabilizing polymer.

A solution for leaching metals from clay containing ore and a method of leaching ore is described. The solution comprises a cyanide; a wetting agent; and a clay stabilizing polymer.