A system and method for decoating a scrap coated metal in a leach solution uses direct measuring of the corrosion potential of the scrap metal in the system to determine the progress of the decoating process and end the process when the scrap is decoated. Corrosion potential measurements are made using a working electrode comprising more than one piece of scrap coated-metal within the system. The decoating system and method may include a system for recycling leach solution.

The present invention relates to separation and recovery of metals from ground alkaline batteries using anode mud (zinc electrolysis waste) and other manganese and zinc containing materials. The material commonly referred to as alkaline black (AKB) is solubilized into sulfate media and the manganese to zinc ratio is adjusted. The solution containing metals is processed using crystallization and ion exchange methods to produce manganese sulfate and zinc sulfate solutions for several possible applications.

A method for recovering zinc from slag derived from lead smelting comprises subjecting the slag to a leaching step under conditions in which zinc is dissolved into solution and silica present in the slag dissolves and re-precipitates in a form that is readily separable from liquid, and recovering zinc from the solution. The slag may be subjected to leaching in at least two stages in which in a first leaching stage only part of the zinc is removed from the slag and further zinc leaching from the slag occurs in a second stage to form a pregnant leaching solution and recovering zinc from the solution. The method may be used to remove SO.sub.2 from a gas stream by using the SO.sub.2-containing gas stream to leach a slurry of the slag.

A method of recovering metal values from metal-bearing materials such as slags and drosses includes the steps of pulverizing the material to particles less than about 100 m; leaching the pulverized material with a solution of ammonium chloride, sodium chloride, and potassium chloride; sequentially recovering at least two metals from the leachate by the addition of zinc using a sequential cementation process; and recovering zinc from the solution by electrowinning.

The invention discloses a treatment method of a chlorine-containing zinc oxide secondary material, which comprises the following steps: 1) leaching the chlorine-containing zinc oxide secondary material I through an acid solution; 2) selectively extracting zinc through di-(2-ethylhexyl)phosphoric acid (P204)-kerosene solvent; 3) implementing stripping-electrolysis zinc recovery; 4) repeating steps 1)-4); 5) taking out the raffinate obtained from the Step (4), mixing the residual taken out raffinate with chlorine-containing zinc oxide secondary material II when balance on chlorine ion input and taking out is achieved; carrying out liquid-solid separation; leaching the separated deposit through acid raffinate of the step 1); 6) after separated solution achieves preset conditions, purifying the chlorine-containing aqueous phase; 7) evaporating and concentrating to crystallize out KCl and NaCl products. The invention is environment-friendly and energy-saving, and free from process wastewater emission; production cost is greatly reduced and secondary pollution of the current dechloridation process is eliminated thoroughly.

The present disclosure provides a method for removing chlorine from a process solution in zinc hydrometallurgy, the method comprising: a step for preparing the process solution from a leaching process of leaching a zinc calcine; a step for introducing the process solution to a reactor and introducing a lead concentrate into the reactor while blowing-in oxygen; a step for solid-liquid separating of a slurry in a filtration tank, the slurry being produced in the reactor; and a step for post-processing a filtrate and a lead concentrate residue separated in the step for solid-liquid separating, wherein chlorine ions in the process solution and silver contained in the lead concentrate react with each other in the reactor to precipitate a silver chloride.

A zinc production method includes a reaction step such as a leaching step (101) of bringing electric arc furnace dust (1) containing zinc oxide or the like into contact with a chlorine gas (8) to obtain a zinc oxide component in the electric arc furnace dust (1) or the like as crude zinc chloride (3), a purification step (102) of heating the crude zinc chloride (3) obtained at the reaction step to produce zinc chloride vapor, and cooling and condensing the zinc chloride vapor, thereby obtaining purified zinc chloride (6), and an electrolysis step (103) of electrolyzing the purified zinc chloride (6) obtained at the purification step (102) in a molten state to obtain a zinc melt (9) and the chlorine gas (8).

A process is described for recovering a non-ferrous metal from a first solid residue comprising iron. In this process, the first solid residue is mixed with a second solid residue including sulphur, thereby obtaining a particulate mixture. The particulate mixture is subjected to a roasting step at a temperature of at least 650 C. to obtain a roasted mixture, and the roasted mixture is subjected to leaching in a liquid at a pH of at least 5.5 to obtain a solution enriched with the non-ferrous metal.

The present invention relates to a process for recovering zinc and iron products from zinc-containing waste materials obtained from the zinc or steel industry, or both, by first treating the waste material(s) with strong acid, to convert any zinc ferrites into leachable compounds, and then leaching the acid-treated material, neutralizing the acid of the leach solution, recovering zinc from the neutralized ferrous iron-containing solution, recovering iron from the thus obtained solution, and circulating at least a fraction of the raffinate solution obtained from the iron recovery back to the leaching step.

A process has been developed in order to recover and recycle the metals present in spent batteries, including alkaline spent batteries alone or mixed with other types of spent batteries. This method shows a good potential in terms of metals recoveries efficiencies and economic feasibility. Firstly, the spent batteries are crushed (optionally after having been frozen in the case of spent batteries of mixed types). Then, the undesirable parts (plastics, steel cases, papers, etc.) are removed by screening. The collected powder, containing the metals, is mixed with a solution of sulfuric acid in the presence of a reducing agent. The solid/liquid separation is carried out by filtration and the leachate is purified in order to selectively recover the metals. The purification steps consist of: a) recovering Zn by solvent extraction followed by an electrowinning process; b) simultaneously recovering Mn and Cd by solvent extraction process; c) selectively recovering Cd from the mixture solution of Cd and Mn by electrowinning process; d) precipitating Mn from a pure solution of MnSO.sub.4 in a carbonate form; e) removing the impurities present in the effluent by solvent extraction in order to obtain a pure NiSO.sub.4 solution; f) precipitating Ni from a NiSO.sub.4 solution in a carbonate form.