The disclosure relates to the oxidation and immobilization of trivalent arsenic from arsenic-containing solutions. The process includes oxidation of trivalent arsenic (As.sup.3+) species to the pentavalent state (As.sup.5+). A carbon additive (e.g., activated carbon) and oxygen are used to promote the arsenic oxidation processes. After oxidation of arsenic to the pentavalent state, the arsenic can be removed by precipitation to ferric arsenate or calcium arsenate or other arsenic containing compounds known in the art. The oxidation of arsenic can also occur simultaneously with the production and precipitation of ferric arsenate (e.g., scorodite). Ferrous iron can be oxidized to ferric iron in the presence of activated carbon and oxygen.

A method for vitrification of arsenic and antimony, comprising substituting oxygen to sulfur on thiosalts, incorporating resulting sodium arsenate and sodium antimonate into a sodium silicate glass-forming mixture and vitrifying the sodium silicate glass-forming mixture into a resulting glass sequestering the arsenic and antimony.

A stabilization process for an arsenic solution comprising thiosulfates, the process comprising: acidifying the arsenic solution to decompose the thiosulfates, to yield an acidified solution; oxidizing the acidified solution to oxidize residual As.sup.3+ to As.sup.5+ and reduced sulfur species to sulfates, to yield a slurry comprising elemental sulfur; separating elemental sulfur from the slurry to yield a liquid; oxidizing the liquid to oxidize residual reduced sulfur species, to yield an oxidized solution; and forming a stable arsenic compound from the oxidized solution.

A stabilization process for an arsenic solution comprising thiosulfates, the process comprising: acidifying the arsenic solution to decompose the thiosulfates, to yield an acidified solution; oxidizing the acidified solution to oxidize residual As.sup.3+ to As.sup.5+ and reduced sulfur species to sulfates, to yield a slurry comprising elemental sulfur; separating elemental sulfur from the slurry to yield a liquid; oxidizing the liquid to oxidize residual reduced sulfur species, to yield an oxidized solution; and forming a stable arsenic compound from the oxidized solution.

A process is provided for separation of at least one metal sulfide from a mixed sulfide concentrate. The process includes: subjecting the mixed sulfide concentrate to flotation in which at least one sulfide including antimony, arsenic and a first metal is floated and at least one sulfide including a second metal is depressed. The flotation yields a first metal concentrate having the at least one sulfide including antimony, arsenic and the first metal and a second metal concentrate having the at least one sulfide including the second metal. The first metal concentrate is leached to yield a further concentrate and a leach solution. The further concentrate includes the first metal and the leach solution includes soluble antimony and soluble arsenic. The process further includes oxidizing the leach solution to yield an antimony precipitate and an arsenic solution, and forming a stable arsenic compound from the arsenic solution.

A process is provided for separation of at least one metal sulfide from a mixed sulfide concentrate. The process includes: subjecting the mixed sulfide concentrate to flotation in which at least one sulfide including antimony, arsenic and a first metal is floated and at least one sulfide including a second metal is depressed. The flotation yields a first metal concentrate having the at least one sulfide including antimony, arsenic and the first metal and a second metal concentrate having the at least one sulfide including the second metal. The first metal concentrate is leached to yield a further concentrate and a leach solution. The further concentrate includes the first metal and the leach solution includes soluble antimony and soluble arsenic. The process further includes oxidizing the leach solution to yield an antimony precipitate and an arsenic solution, and forming a stable arsenic compound from the arsenic solution.

A method for vitrification of arsenic and antimony, comprising substituting oxygen to sulfur on thiosalts, incorporating resulting sodium arsenate and sodium antimonate into a sodium silicate glass-forming mixture and vitrifying the sodium silicate glass-forming mixture into a resulting glass sequestering the arsenic and antimony.

A method for removing lead-210 (.sup.210Pb) from a metal, the method comprising determining a .sup.210Pb concentration in a metal to be refined; determining an amount of low alpha lead to be added to the metal to be refined from the .sup.210Pb concentration, the low alpha lead having a .sup.210Pb concentration below that of the metal to be refined; forming a doped metal mixture by adding the low alpha lead to the metal to be refined; refining the doped metal mixture to separate at least a portion of the lead in the doped metal mixture to form a refined metal having a .sup.210Pb concentration lower than that of the metal to be refined.

A method for removing lead-210 (.sup.210Pb) from a metal, the method comprising determining a .sup.210Pb concentration in a metal to be refined; determining an amount of low alpha lead to be added to the metal to be refined from the .sup.210Pb concentration, the low alpha lead having a .sup.210Pb concentration below that of the metal to be refined; forming a doped metal mixture by adding the low alpha lead to the metal to be refined; refining the doped metal mixture to separate at least a portion of the lead in the doped metal mixture to form a refined metal having a .sup.210Pb concentration lower than that of the metal to be refined.

A method for production of potassium antimony tartrate by utilizing one or more residues bearing antimony includes the step of leaching of the one or more residues bearing antimony for a first pre-determined time interval in each of one or more jacketed reactors. In addition, the method includes filtering obtained slurry from a leached solution of the one or more residues products bearing antimony to obtain an aqueous solution and a solid residue. The method also includes crystallizing the obtained aqueous solution to form one or more crystals of the potassium antimony tartrate in a jacketed crystallizer. The antimony contained in the one or more residues is in an oxidic form and the oxidic form of the antimony is more than 20%. The solid residue is a leached cake.