Method for cleaning dust from the dry electrostatic precipitator in the pyro-metallurgical production process of zinc and lead

摘要

The object of the invention is the treatment of dust arising from the pyrometric process, e.g. Imperial Smelting Process (ISP) technology,from fluorine and chlorine to return them to production. The dust treatment method is characterised by the process consisting of three successive technological phases in which the solution undergoes the following operations as it passes through the next technological blocks. In the first phase, sulphuric acid dust is used to obtain in suspension after pH prolongation of "slightly acidic";ending this phase with a chapter on suspension phases. At this stage, the dust is fluorinated and discoloured, and after the phase chapter, a solid product is obtained which returns to the technological process (ISP technology) and a solution which goes to the second technological block, in which excess acid is removed from the filter and fluorine is removed in the form of a mixture of gypsum and calcium fluoride, adding to the solution calcium hydrated to pH at level 3,5-4. The process ends with a split of suspension phases and a solid product, consisting of a mixture of calcium fluoride and gypsum, is obtained after a split of phases, and a solution which is directed to the third technological block,In which cadmium and zinc in the form of carbons are removed from the solution. To this end, sodium carbonate is added to the solution at the pH level 6,8-8,0, resulting in the precipitation of a mixture of cadmium and zinc carbons. The process ends with a suspension phase, which results in the recovery of cadmium and zinc in the form of carbons, resulting in a solid product in the form of cadmium and zinc carbons, which reverts back to the technological process (ISP technology) and a filtrate constituting the effluent.