Method for obtaining cobalt(II) rhenate(VII) using waste materials

Abstract

The subject of the application is a method for producing cobalt(II) rhenate(VII) by reacting cobalt(II) compounds with rhenic(VII) acid, as a result of which a cobalt-rhenium solution is obtained, from which cobalt(II) rhenates(VII) are subsequently separated and dried, which is characterized in that aqueous, multi-component sulphate or chloride solutions containing at least 2.5 g / dm3 of Co and Ni, Fe, Cu, Mn, Al, Li and Cr are purified from copper, aluminium, chromium, iron and manganese by known methods, so that the concentration of each of the mentioned metals is not higher than 0.01 g / dm3, the solution thus obtained, with a pH of 5.5 - 5.8, is directed to the extraction stage, using known extraction agents, and subsequently cobalt is re-extracted with aqueous solutions of sulphuric(VI) acid or hydrochloric acid, with a concentration within the range of 10% to 25%, so that the Co concentration in the solution after re-extraction is at least 5 g / dm3,the raffinate formed after cobalt extraction is sent to the recovery of nickel and lithium using known methods, and the re-extraction formed after Co re-extraction is sent to the stage of separation of cobalt(II) hydroxide, using an aqueous solution of NaOH, at pH >8.0 cobalt(II) hydroxide is separated, the cobalt(II) hydroxide separated in this way is filtered, and the filtrate formed after separation with a concentration of <0.01 g / dm3 of Co is sent to the stage of purification of multi-component solutions from copper, aluminum, chromium, iron and manganese, and the precipitate of raw Co(OH)2 separated in this way is sent to the stage of purification, which is carried out with water, using 0.01 - 0.03 dm3 of water in one cycle for every 10 g of precipitate, in such a way that the Co(OH)2 precipitate is mixed with water for at least 30 minutes, at a temperature in the range of 20°C - 40°C, washing is carried out cyclically from 2 to 6 times, the washings are combined and returned to the stage of preparation of the aqueous NaOH solution directed to the precipitation of Co(OH)2,and an aqueous solution of rhenic(VII) acid with a maximum concentration of 350 g / dm3 is added to the purified Co(OH)2 precipitate remaining after the last filtration, so that the final pH of the solution is not lower than 6.0, and this mixture is stirred intensively at a temperature not exceeding 75°C for a minimum of 60 minutes, monitoring the pH all the time, after which the remaining precipitate of unreacted cobalt(II) hydroxide is separated from the solution, and the solution with a minimum pH of 6.5 is sent for evaporation to dryness, evaporation is carried out at a temperature not exceeding 55°C, and the separated precipitate of the hydrated form of cobalt(II) rhenate(VII) is sent for drying at a temperature of 180°C until dry mass is obtained, and subsequently the resulting precipitate of anhydrous cobalt(II) rhenate(VII) is stored in conditions without access to air.,