Process with low environmental impact and reduced energy consumption for the recovery of lead from the electrode pastes of end-of-life batteries

Process for obtaining metallic lead from its compounds present in an end-of-life lead-acid battery by direct solid-solid reaction with metallic zinc, said process comprising:

• a) a dry mixing step of a mixture of lead compounds present in an end-of-life lead-acid battery with a metered quantity of metallic zinc powder, obtaining a mass;
• b) an addition to the mass, during mixing, of water and of an aqueous solution containing a substance capable of forming soluble zinc salts;
• c) a separation of a solid portion, consisting of metallic lead, from a liquid portion in which a soluble zinc salt is present;
• d) an electrolytic treatment of the liquid portion separated in step c) in order to recover metallic zinc suitable for reuse in the treatment referred to in step a);
• wherein the mixing step lasts for a time substantially comprised between 2 minutes and 10 minutes and wherein the aqueous solution containing the substance capable of forming soluble zinc salts comprises potassium hydroxide,
• and/or wherein the addition to the mass, during the mixing step, of water and of the aqueous solution containing a substance capable of forming soluble zinc salts is an addition in two steps, comprising a first step of adding said substance, in particular sulfuric acid between 6% and 14%, and comprising a second step of adding said substance, said substance being sulfuric acid between 20% and 30%, said second step being subsequent to said first step and taking place when the free acidity of a resulting intermediate mixture is substantially absent,
• and/or comprising a step of crystallization of the soluble zinc salts, said crystallization step taking place after a purification process of said soluble zinc salts,
• wherein the crystallization step is a crystallization step of zinc salts of said liquid portion separated in step c).