Processes for the recovery of ruthenium from materials containing ruthenium orruthenium oxides or from ruthenium-containing noble metal ore concentrates

Abstract

Processes for the recovery of ruthenium from materials containing ruthenium or ruthenium oxides or from ruthenium-containing noble metal ore concentrates, with the steps of A. the introduction of the material into a highly alkaline alkali hydroxide melt in the presence of nitrate as oxidising agent with the formation of an oxidised melt residue with water-soluble ruthenate (RuO 4 ) 2− , B. the dissolution of the oxidised melt residue obtained in water, C. the addition of a reducing agent, D. the precipitation of the metals formed, can also be used for separating off selenium. Optionally, ruthenium is separated off by distillation, instead of precipitation, following step B, with the steps of 5C the treatment of the ruthenate-containing solution with an oxidising agent, 5D distilling off of the RuO 4 obtained, 5E taking up of the RuO 4 from step 5D in hydrochloric acid. By way of further subsequent purification steps, processes for the recovery of ruthenium targets are obtained.

1 . Process for the recovery of ruthenium from materials containing ruthenium or ruthenium oxides or from ruthenium-containing noble metal ore concentrates with the steps of
 1A. the introduction of the material into an alkali hydroxide melt in the presence of nitrate as oxidising agent with the formation of an oxidised melt residue with water-soluble ruthenate (RuO 4 ) 2− ,   1B. the dissolution, in water, of the oxidised melt residue obtained,   1C. the addition of a reducing agent,   1D. the precipitation of the metals formed.   
   
   
       2 . Process for the separation of selenium from materials containing ruthenium or ruthenium oxides or from ruthenium-containing noble metal ore concentrates with the steps of
 2A. the introduction of the material into an alkali hydroxide melt in the presence of nitrate as oxidising agent with the formation of an oxidised melt residue with water-soluble ruthenate (RuO 4 ) 2− ,   2B. the dissolution, in water, of the oxidised melt residue obtained; the solution subsequently contains ruthenate (RuO 4 ) 2−  and selenate (SeO 4 ) 2− ,   2C. the addition of a reducing agent,   2D. the precipitation of water-containing ruthenium(IV) oxide, selenium being dissolved quantitatively in step 2B as selenate.   
   
   
       3 . Process according to  claim 1  or  2  characterised in that step 1A or 2A is carried out in an apparatus consisting of nickel base alloy. 
   
   
       4 . Process according to  claim 3 , the nickel base alloy having a Cr content of at least 10% by wt. 
   
   
       5 . Process for the recovery of ruthenium from materials containing ruthenium or ruthenium oxides and for the subsequent separation of ruthenium with the steps of
 5A the introduction of the material into an alkali hydroxide melt in the presence of nitrate as oxidising agent with the formation of water-soluble ruthenate (RuO 4 ) 2− ,   5B the dissolution, in water, of the oxidised melt residue obtained to give a ruthenate-solution,   5C the treatment of the ruthenate-containing solution with an oxidixing agent,   5D distilling off of the RuO 4  obtained,   5E absorbing the RuO 4  from step 5D in hydrochloric acid.   
   
   
       6 . Process according to  claim 5 , the materials containing ruthenium or ruthenium oxides being ruthenium targets. 
   
   
       7 . Process according to one of the preceding claims, the alkali hydroxide melt being a KOH melt. 
   
   
       8 . Process according to one of the preceding claims, the nitrate being NaNO 3 . 
   
   
       9 . Process according to  claim 6  with the additional purification steps of
 6F the concentration of the hydrochloric acid solution,   6G the precipitation of an ammonium ruthenate with NH 4 Cl,   6H the calcination of the ammonium ruthenate,   6I rolling,   6J reduction under hydrogen,   6K grinding.   
   
   
       10 . Process according to  claim 9 , step 6F taking place at 450-700° C. 
   
   
       11 . Process according to  claim 9 , step 6F taking place at 600° C.