| 摘要 |
The present invention relates to a lead extraction method that involves feeding melted potassium hydroxide, lead-containing raw materials and an oxygen-containing gas into a reaction area at a temperature of between 600 and 700 DEG C. The lead is extracted from the reaction area and a first aqueous lixiviation is carried out in order to provide a suspension consisting of a mixture that comprises solid particles of potassium sulphate, potassium carbonate, zinc, copper and iron sulphides and waste rock as well as an aqueous solution mainly containing potassium hydroxide. The suspension is then filtered in order to obtain a solution essentially containing potassium hydroxide and a solid residue. The potassium hydroxide solution is then evaporated and the melted potassium hydroxide thus obtained is further fed to the reaction area. After the first lixiviation and rinsing step, the solid residue is submitted to a second aqueous lixiviation where a reverse solution and sulphuric acid are introduced while maintaining the pH between 6 and 8. The suspension thus obtained is filtered so as to provide a cake which is rinsed with water and withdrawn from the process. The potassium sulphate crystals are then removed from the aqueous and saturated solution of potassium sulphate, said crystals being withdrawn from the process. The mother solution resulting from the potassium sulphate crystallisation is added to the cake rinsing water and submitted to a second lixiviation. |
