Embodiments of the invention relate to a process for removing fluoride from a solution or suspension containing zinc, in particular a solution of zinc sulfate, a defluoridated solution of zinc sulfate obtainable by such a process, its use as well as processes for producing zinc and hydrogen fluoride or hydrofluoric acid. The process for removing fluoride comprises (i) providing a solution or suspension A containing zinc, wherein the solution or suspension A containing zinc further contains fluoride ions; (ii) adding a solution B containing a dissolved salt of a rare earth element to the solution or suspension A containing zinc, wherein a solid comprising a rare earth element fluoride and a solution C containing zinc are formed; and (iii) separating the solid from the solution C containing zinc, wherein the solution C containing zinc has a lower concentration of fluoride ions than the solution or suspension A containing zinc.

A solvent extraction method for separation and recovery of nickel, cobalt, manganese, and zinc is proposed. More particularly, the present method relates to a solvent extraction method for separation and recovery of nickel, cobalt, manganese, and zinc, the method being capable of separately recovering four kinds of valuable metals as respective monotype metals from a starting material containing nickel, cobalt, manganese, and zinc by involving: a first solvent extraction step in which the starting material is separated into a first aqueous phase solution containing nickel and cobalt and a second aqueous phase solution containing nickel, cobalt, manganese, and zinc; a second solvent extraction step in which nickel (Ni) and cobalt (Co) are separated and recovered; a third solvent extraction in which zinc (Zn) is recovered; and a fourth solvent extraction step in which manganese (Mn) and cobalt (Co) are separated and recovered.

A vertical autoclave according to an embodiment of the present disclosure is a vertical autoclave including an inlet port through which a process solution is introduced, an outlet port configured through which the process solution is discharged, an oxygen inlet port through which oxygen is supplied to the process solution, an agitator configured to mix the process solution, an inner wall, an acid-resistant brick layer lined on a lower portion and a side portion of the inner wall, and an acid-resistant metal layer lined on an upper portion of the inner wall.

A method of recovering iron from a zinc sulfate solution according to an embodiment of the present disclosure is associated with recovering iron from a zinc sulfate solution produced by a leaching process in which zinc ore is dissolved in sulfuric acid. The method comprises a conditioning process including a step of reducing a conditioning process input solution, which is the zinc sulfate solution, and an iron precipitation process for recovering iron as hematite, including a step of pressurizing and oxidizing an iron precipitation process input solution discharged from the conditioning process. The iron precipitation process is performed at a temperature ranging from 135 C. to 150 C. and a pressure ranging from 5 barg to 10 barg.

The present invention provides a method for the treatment of sludge containing iron and between 4.5% to 12% by weight of zinc. This method includes a leaching step wherein leaching agents include hydrochloric acid and chlorate, and wherein the pH of the leachate directly resulting from this leaching step is set at a value below 1.5. A recycling method and treatment installation are also provided.

Any metal having a low ?-ray emission, the metal being any one of tin, silver, copper, zinc, or indium, wherein an emission of an ?-ray after heating the metal at 100? C. in an atmosphere for six hours is 0.002 cph/cm.sup.2 or less. Any metal of tin, silver, copper, zinc and indium each including lead as an impurity is dissolved to prepare a hydrosulfate aqueous solution of the metal and lead sulfate is precipitated and removed in the solution. The lead sulfate is precipitated in the hydrosulfate aqueous solution by adding a lead nitrate aqueous solution including lead having an ?-ray emission of 10 cph/cm.sup.2 or less to the hydrosulfate aqueous solution, from which the lead sulfate has been removed, and, at the same time, the solution is circulated while removing the lead sulfate to electrowinning the metal using the hydrosulfate aqueous solution as an electrolytic solution.

A bioleaching and solvent extraction process with selective recovery of copper and zinc from polymetallic sulphide concentrates is described, comprising a bioleaching and ferric ion reducing process and a copper and zinc solvent extraction process. The bioleaching and ferric ion reducing process comprises a concentrates pulp conditioning step; a bioleaching step, wherein once the pulp is conditioned it is subjected to a bioleaching process using a plurality of bioreactors of the stirred-tank type with an air injection and diffusion system, which allows handling of a pulp density higher than 15%; a step of solid separation from a solution rich in metallic ions from the bioleaching step; and, a ferric ion reduction step, wherein the pulp from the previous step is subjected to a transformation step of ferric ions into ferrous ions. The solvent extraction step comprises a copper solvent extraction and electrolysis step; an arsenic control step, wherein arsenic is controlled in the solution once copper has been extracted from it; and, a zinc solvent extraction and electrolysis step, which uses a phosphinic acid-based zinc extraction dissolution.

A process and its relating plant for recycling zinc oxide residues. Thereby, zinc oxide residues are granulated to particles with a size of d.sub.80 between 0.3 and 5 mm, preferably between 0.5 and 2 mm. These particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1.200? C., preferably 800 to 1.100? C. in a fluidized bed to form a calcine. The zinc oxide residues are zinc oxide dusts with a particle size below d.sub.80 100 ?m, preferably below d.sub.80 75 ?m coming from kiln, submerges lances furnaces, ferric reduction furnaces, galvanizing and/or recycling processes, particularly recycling of steel, copper, lead, nickel and/or electronic scrap, and/or that the zinc oxide residues comes from foundry for lead and zinc, ashes and/or dross from a Zamac process, oxide zinc ash, catalysts, melting and casting of Zn and/or zinc slag.

The present invention provides a method of recovering copper and zinc from an aqueous sulfate and chloride containing solution. In the first process step zinc and copper are simultaneous extracting with an extraction solution comprising a liquid chelating cation exchanger and a liquid anion exchanger. The extraction is followed by consecutive stripping stages. First the anionic species are washed from the organic phase with one or more aqueous solutions and finally the copper is stripped with an aqueous acidic solution.

A method for the treatment of sludge containing iron, the method including a leaching step wherein the sludge containing iron is mixed with an acid and an oxidation agent so as to create an oxidized leachate, and a step of precipitation of iron wherein the oxidized leachate is mixed with a neutralizing agent so as to create a mixture composed of a solid part including precipitated iron and of a liquid part, the neutralizing agent including at least 30% in weight of dust recovered from a bag filter treatment of ironmaking, steelmaking, coke making or sintering gas.