Selective metal leaching process

Abstract

The invention refers to a selective metal leaching process from the materials that contain them, in which said metals come into contact with a solution comprising said process two or more in this order, of the following leaching steps: (a), (b) or (c) in the following order: (a) Treatment of the material with an aqueous solution in the presence of oxygen; (b) Treatment of the remaining material with an aqueous solution in the presence of oxygen and ozone; (c) Treatment of the remaining material with an aqueous solution in the presence of oxygen, ozone and a third reagent. And optionally a step of separation of phases is carried out after every one of the previously steps (a), (b) or (c). Said process is used for the recovery of metals from scrap, ores, concentrates and mixtures of these.

1 . Process of leaching metals from the materials containing them, characterized in that these materials come into contact with a solution containing oxygen, ozone and a third complexing reagent.  
     
     
         2 . Process according to  claim 1 , characterized in that these metals are precious metals.  
     
     
         3 . Process according to  claim 1  or  claim 2 , characterized in that these metals are preferably gold and palladium.  
     
     
         4 . Process according to  claim 1 , characterized in that the third complexing reagent is a type of redox pair whose reduced form is liable to be oxidized in the leaching solution and whose oxidized form is capable of attacking the materials to be leached.  
     
     
         5 . Process according to  claim 1 , characterized in that the third complexing reagent is a depassivating or pickling reagent.  
     
     
         6 . Process according to  claim 1 , characterized in that the third complexing reagent is an anion, preferably chloride.  
     
     
         7 . Process according to  claim 6 , characterized in that this chloride anion is added to the solution in the form of HCl, chloride salts or mixtures of any of these substances.  
     
     
         8 . Process of selective leaching and/or passivation of materials containing metals, characterized in that it includes two or more, in this order, of the following leaching steps: 
 (a)Treatment of the material with an aqueous solution in the presence of oxygen.    (b)Treatment of the material with an aqueous solution in the presence of oxygen and ozone.    (c)Treatment of the material with an aqueous solution in the presence of oxygen, ozone and a third reagent.    
     
     
         9 . Process according to  claim 8 , characterized in that after each of the leaching steps separation of the resultant phases is performed.  
     
     
         10 . Process according to  claim 8 , characterized in that prior to this process the following steps are performed: 
 i)Treatment of the material with an aqueous solution in the absence of oxygen.    ii)Separation, where applicable, of the resultant phases.    
     
     
         11 . Process for recovery of metals from the materials that contain them, characterized in that the recovery of a noble metal from a laminar material comprising a base metal and said noble metal is carried out according to the following leaching step: 
 Treating said laminar material with an aqueous solution comprising a gas so that a selective leaching of said base metal is carried out by releasing said noble metal when said base metal is dissolved.    
     
     
         12 . Process according to  claim 11 , characterized in that said gas is oxygen, ozone or mixtures thereof.  
     
     
         13 . Process according to  claim 11 , characterized in that said noble metal is gold, silver, rhodium or palladium.  
     
     
         14 . Process according to  claim 11 , characterized in that said base metal comprises at least one of the following metals: copper, silver or nickel.  
     
     
         15 . Process according to claims  8 ,  10  or  11 , characterized in that the aqueous solution is acidic.  
     
     
         16 . Process according to  claim 8 ,  10  or  11 , characterized in that the aqueous solution is alkaline.  
     
     
         17 . Process according to  claim 15 , characterized in that the acid of the solution is an inorganic acid.  
     
     
         18 . Process according to  claim 17 , characterized in that the inorganic acid is sulphuric acid.  
     
     
         19 . Process according to  claim 16 , characterized in that the alkaline solution comprises an inorganic base.  
     
     
         20 . Process according to  claim 19 , characterized in that the inorganic base is sodium hydroxide.  
     
     
         21 . Use of the process according to any one of the previous claims for leaching of metals from scrap, ores, concentrates, by-products, waste, soils and mixtures thereof.