Abstract: The present invention relates to a process for reducing the amounts of zinc and lead in starting materials comprising iron which comprises the steps of: —selectively leaching Zn and Pb comprised in the starting materials by mixing the starting materials with hydrochloric acid and an oxidizing agent comprising at least 5 wt-% of manganese dioxide in one or several reactor(s) at a temperature superior or equal to 35° C. and at a p H comprised between 0.5 and 3.

Abstract: The present invention relates to a method for removing halides, in particular chlorides and fluorides, from starting secondary zinc oxides, for example Waelz or Primus oxides, comprising the steps (1) for washing the secondary zinc oxides with sodium carbonate and separating the solid residue from the basic liquid, (2) leaching at least one portion of the solid residue of step 1 by means of H2SO4, preferably up to a pH between 2.5 and 4, and separating the solid residue from the acid liquid, and (3) treating the liquid from step 2 by adding Al3+ and PO43? ions and a neutralizing agent in order to remove the residual fluoride, preferably at a pH<4, and separating the liquid from the solid residue containing fluorides.

Abstract: Disclosed is a process and apparatus for the treatment of divided metal residues contaminated by one or more organic compounds, including mixing, inside a chamber, of metal residues with at least one calcium/magnesium compound capable of reacting exothermically with water; exothermic reaction of the at least one calcium/magnesium compound with the water that the metal residues contain; rise in temperature of the metal residues subject to an exothermic reaction; dehydration of the metal residues during this exothermic reaction; oxidation of the organic compounds during the mixing, by bringing the metal residues contaminated by one or more organic compounds mixed with the at least one calcium/magnesium compound into contact with a gas stream containing at least partly oxygen; and removal from the chamber of a handleable dehydrated treated product having a residual content of organic compounds of less than 1% by weight of the treated product.

Abstract: The invention describes a method for recovering molybdenum, nickel, cobalt or their mixtures from used or regenerated catalysts in an electric arc furnace containing a heel of liquid cast iron, surmounted with a fluid slag, comprising the following steps: a) adding used or regenerated catalysts into the heel contained in the electric arc furnace, b) adding dosed lime in order to obtain a slag with a CaO to Al2O3 ratio comprised between 0.7 and 1.3, c) mixing the heel by injecting gas so as to avoid formation of crusts, d) melting the used or regenerated catalysts in the electric arc furnace in order to obtain a liquid ferro-alloy.

Abstract: The invention describes a method for recovering molybdenum, nickel, cobalt or their mixtures from used or regenerated catalysts in an electric arc furnace containing a heel of liquid cast iron, surmounted with a fluid slag, comprising the following steps: a) adding used or regenerated catalysts into the heel contained in the electric arc furnace, b) adding dosed lime in order to obtain a slag with a CaO to Al2O3ratio comprised between 0.7 and 1.3, c) mixing the heel by injecting gas so as to avoid formation of crusts, d) melting the used or regenerated catalysts in the electric arc furnace in order to obtain a liquid ferro-alloy.

Abstract: Process and apparatus for the treatment of divided metal residues contaminated by one or more organic compounds, comprising: mixing, inside a chamber, of said metal residues with at least one calcium/magnesium compound capable of reacting exothermically with water; exothermic reaction of said at least one calcium/magnesium compound with the water that the metal residues contain; rise in temperature of the metal residues subject to an exothermic reaction; dehydration of said metal residues during this exothermic reaction; oxidation of the organic compounds during said mixing, by bringing the metal residues contaminated by one or more organic compounds mixed with said at least one calcium/magnesium compound into contact with a gas stream containing at least partly oxygen; and removal from the chamber of a handleable dehydrated treated product having a residual content of organic compounds of less than 1% by weight of said treated product.