Method for recovering Ni from spent nickel catalysts in the form of a high-concentration nickel(II) nitrate(V) solution

Abstract

The subject of the application is a method for the recovery of Ni from spent nickel catalysts in the form of a nickel(II) nitrate(V) solution with a high Ni concentration, which is characterized in that nickel from spent nickel catalysts of the Ni(NiO) / Al2O3 and / or Ni(NiO) / CaO-Al2O3 type, with a Ni content above 8% by weight, which may also contain Mg, Ca, Fe, Zn, Cr, Cu, Si, S, is recovered in a two-stage leaching process, wherein the first stage of leaching is carried out by leaching spent Ni(NiO) / Al2O3 and / or Ni(NiO) / CaO-Al2O3 catalysts in a nitric acid(V) solution with a concentration of ≥250 g / dm3, using a solid to liquid phase ratio (w / v) from 1:1 to 1:4, the leaching is carried out at a temperature of 40°C - 99°C, for 1 - 12 hours, the undissolved residue after separation from the solution by filtration is washed with water on the filter and partially recycled to a new portion of the leached, used catalyst or sent for disposal by known methods,and the solution obtained after the first leaching and filtration stage together with the washings is used in the second leaching stage, in which metallic nickel and / or nickel cathodes of high purity 99.99% are leached, the leaching process of metallic nickel and / or nickel cathodes is carried out at a temperature of 40°C - 99°C, with intensive mixing of the leaching solution and replenishing in the event of exhaustion of the leaching metallic nickel and / or nickel cathodes and the free nitric acid (V) consumed during the process in such an amount that the increase in the Ni concentration in the solution within 1 hour is not lower than 5 g / dm3, the leaching process is carried out until the Ni concentration in the solution is not lower than 180 g / dm3, and the concentration of free nitric acid (V) is not higher than 10 g / dm3,the solution thus obtained, after separation by filtration from undissolved metallic nickel and / or nickel cathodes, is directed directly to the support impregnation process in order to produce a new Ni(NiO) / Al2O3 or Ni(NiO) / CaO-Al2O3 catalyst, and the undissolved metallic nickel and / or nickel cathodes are returned to the leaching with a new portion of the solution obtained after the first leaching stage.,