A process to beneficiate oxidized iron ore can include the steps of: (1) adding a polysaccharide to the oxidized iron ore; (2) adding at least one amine; and (3) adding at least one salt; wherein the pH of the process is below 10 and greater than 5.

A process and reactor for arsenic fixation in which a first gas stream comprises oxygen and an iron-containing particulate material. The oxygen and particulate material may be fed to reactor through respective first and second inlets. A second gas stream containing one or more volatile arsenic compounds is fed through a third inlet and mixed with the first gas stream and the particulate material to produce a combined gas stream containing the volatile arsenic compounds and the particulate material. The arsenic compounds are reacted with iron in the particulate material as the combined gas stream flows through the reactor to produce solid iron arsenates which are then recovered. The portion of the reactor including the first, second and third inlets is vertically oriented, and the reactor may include a venturi arrangement having a throat at which the second inlet is located.

A process and reactor for arsenic fixation in which a first gas stream comprises oxygen and an iron-containing particulate material. The oxygen and particulate material may be fed to reactor through respective first and second inlets. A second gas stream containing one or more volatile arsenic compounds is fed through a third inlet and mixed with the first gas stream and the particulate material to produce a combined gas stream containing the volatile arsenic compounds and the particulate material. The arsenic compounds are reacted with iron in the particulate material as the combined gas stream flows through the reactor to produce solid iron arsenates which are then recovered. The portion of the reactor including the first, second and third inlets is vertically oriented, and the reactor may include a venturi arrangement having a throat at which the second inlet is located.

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 P.sub.80 of less than 25 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.

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 P.sub.80 of less than 25 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.

Process for enhanced metal recovery from, for example, metal-containing feedstock using liquid and/or supercritical fluid carbon dioxide and a source of oxidation. The oxidation agent can be free of complexing agent. The metal-containing feedstock can be a mineral such as a refractory mineral. The mineral can be an ore with high sulfide content or an ore rich in carbonaceous material. Waste can also be used as the metal-containing feedstock. The metal-containing feedstock can be used which is not subjected to ultrafine grinding. Relatively low temperatures and pressures can be used. The metal-containing feedstock can be fed into the reactor at a temperature below the critical temperature of the carbon dioxide, and an exotherm from the oxidation reaction can provide the supercritical temperature. The oxidant can be added to the reactor at a rate to maintain isothermal conditions in the reactor. Minimal amounts of water can be used as an extractive medium.

Process for enhanced metal recovery from, for example, metal-containing feedstock using liquid and/or supercritical fluid carbon dioxide and a source of oxidation. The oxidation agent can be free of complexing agent. The metal-containing feedstock can be a mineral such as a refractory mineral. The mineral can be an ore with high sulfide content or an ore rich in carbonaceous material. Waste can also be used as the metal-containing feedstock. The metal-containing feedstock can be used which is not subjected to ultrafine grinding. Relatively low temperatures and pressures can be used. The metal-containing feedstock can be fed into the reactor at a temperature below the critical temperature of the carbon dioxide, and an exotherm from the oxidation reaction can provide the supercritical temperature. The oxidant can be added to the reactor at a rate to maintain isothermal conditions in the reactor. Minimal amounts of water can be used as an extractive medium.

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.

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.

Provided is a mineral processing method that allows obtaining a concentrate having a low arsenic grade from a raw material having a high arsenic grade. The mineral processing method includes: a repulping step of adding water to a raw material containing a non-arsenic-containing sulfide mineral as a sulfide mineral not containing arsenic and an arsenic-containing sulfide mineral as a copper sulfide mineral containing arsenic to obtain a mineral slurry; a pH adjusting step of adjusting a pH of a liquid phase of the mineral slurry to 10 or more; a conditioning step of adding an oxidant and xanthate alkali metal salt to the mineral slurry; and a flotation step of performing flotation using the mineral slurry to separate the raw material into a floating ore having a grade of the non-arsenic-containing sulfide mineral higher than a grade of the non-arsenic-containing sulfide mineral of the raw material and a precipitating ore having a grade of the arsenic-containing sulfide mineral higher than a grade of the arsenic-containing sulfide mineral of the raw material. The raw material contains the arsenic by 4.4 to 5.8 pts. wt. per 100 pts. wt. of copper.