The present invention relates to a sustainable regeneration process for metallurgical plant dusts and sludges for producing iron-containing, heavy metal-depleted secondary raw materials and recovering lead and zinc, by providing a first starting material which comprises at least one iron, zinc, lead and further heavy metal components containing metallurgical plant dust and/or sludge, and a second starting material containing at least one chlorine component, mixing the starting materials and drying the mixture, pyrolyzing the mixture for expelling zinc, lead and further heavy metal components, capturing the gas phase of the pyrolysis in sulfuric acid, and providing the residue which remains as an iron-containing secondary raw material depleted in zinc, lead and further heavy metal components.

Provided is a method for inhibiting extractant degradation comprising preparing step, extracting step and scrubbing step, the method including: (a) the preparing step of a DSX solvent by adjusting the extractant concentration of the DSX solvent to a specific range; (b) the extracting step of metal included in the feed solution by adjusting the ratio of the organic (solvent) and an aqueous (solution) as a feed solution; (c) the scrubbing step of adjusting the zinc concentration of the solution using zinc sulfate; and (d) stripping step.

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.

Provided is a method for producing calcium zincate. The method comprises: an extraction step: mixing a ground zinc-containing raw material with an extracting agent, followed by filtration to obtain an extract, wherein the extracting agent is a mixed aqueous solution of ammonia and {NH.sub.4HCO.sub.3 and/or (NH.sub.4).sub.2CO.sub.3; optionally, purifying the extract; a decarburization step: adding calcium oxide and/or calcium hydroxide to the extract, stirring, and filtering to obtain a first solid and a first filtrate; a calcium zincate synthesis step: adding calcium hydroxide and/or calcium oxide to the first filtrate, stirring to react, and filtering to obtain a second solid and a second filtrate; optionally, rinsing the second solid with water; a drying step: drying the second solid to obtain the final calcium zincate product.

A method of inhibiting degradation of an extractant by utilizing several auxiliary means in the DSX process: includes (a) preparing adjustment of the concentration of an extractant of a DSX solvent to a certain range; (b) extracting a metal contained in a pregnant leached solution by adjusting the ratio of the extractant and the diluent in the DSX solvent to a certain range; (c) measuring the pH of the aqueous phase solution by separating mixture into the aqueous phase solution and the organic phase solvent using a settler after step of extracting; (d) controlling the pH by adding soda ash (Na.sub.2CO.sub.3) so as to maintain the pH of the aqueous phase solution to be 3 to 7; and (e) scrubbing with scrubbing solution having a zinc concentration of 2 to 20 g/L by zinc sulfate (ZnSO.sub.4) to remove the manganese from the organic phase solvent containing the extracted metal.

Provided is a method of inhibiting degradation of an extractant by an anhydrous environment avoiding and metal stripping, the method including the steps of: (a) stopping the addition of soda ash (Na.sub.2CO.sub.3) to an extracting reaction tank; (b) starting solution recirculation and stopping solvent recirculation of a settler; (c) supplying a solvent from a loaded organic tank to a scrubbing reaction tank, in which the scrubbing reaction tank, stripping reaction tank and extracting reaction tank are connected for circulation and operating stirrers of the scrubbing reaction tank, stripping reaction tank and extracting reaction tank; (d) supplying a sulfuric acid solution having a controlled concentration with a diluting solution to the stripping reaction tank; (e) transferring the solvents of the settler, the loaded organic tank and all the pipes to the scrubbing reaction tank; and (f) stopping the step (e) and initiating solvent recirculation.

Provided is a method for inhibiting extractant degradation comprising preparing step, extracting step and scrubbing step, the method including: (a) the preparing step of a DSX solvent by adjusting the extractant concentration of the DSX solvent to a specific range; (b) the extracting step of metal included in the feed solution by adjusting the ratio of the organic (solvent) and an aqueous (solution) as a feed solution; (c) the scrubbing step of adjusting the zinc concentration of the solution using zinc sulfate; and (d) stripping step.

Provided is a method for inhibiting extractant degradation in the DSX process through the metal extraction control, the method comprising steps of: (a) adding limestone to a copper solvent extraction-raffinate to precipitate iron (Fe) and aluminum (Al) as a slurry, recovering a clarifying liquid; and (b) adding sulfuric acid to the recovered clarifying liquid to adjust the pH thereof.

A method of extracting metals from polymetallic sulphide ores or concentrates comprising at least Cu, Zn, Pb and Ag, comprising a first step of atmospheric leaching in sulphate medium in the presence of recycled silver for extracting Cu and Zn and a second step of atmospheric leaching in chloride medium for extracting Pb and Ag.

Provided is a method for recovering a valuable metal sulfide, the method including: (a) adding limestone to a residual solution including a valuable metal to remove iron and aluminum; (b) adding sulfuric acid and a sulfide to the solution from which the iron and aluminum are removed to recover the valuable metal sulfide; and (c) adding air or sulfuric acid to the solution from which the valuable metal sulfide is recovered to remove sulfur.