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

Abstract

The subject of the application is a method for producing nickel(II) rhenate(VII) by reacting nickel(II) compounds with rhenic(VII) acid, as a result of which a nickel-rhenium solution is obtained, from which nickel(II) rhenate(VII) is separated and dried, which is characterized in that aqueous multi-component sulphate or chloride solutions containing at least 1.0 g / dm3 of Ni and Co, Fe, Cu, Mn, Al, Li and Cr are purified from cobalt, 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 pH 5.8 - 6.5, is directed to the extraction stage, using known extraction agents, and subsequently the nickel is re-extracted with aqueous solutions of sulphuric(VI) acid or hydrochloric acid, with a concentration within the range of 10% to 30%, so that the Ni concentration in the solution after re-extraction is at least 5 g / dm3, the organic phase formed after re-extraction is returned to the extraction stage,and the raffinate formed after nickel extraction is sent to lithium recovery using known methods, while the re-extraction formed after Ni re-extraction is sent to the stage of nickel(II) hydroxide separation using an aqueous NaOH solution, nickel(II) hydroxide is separated at pH >8.0, the nickel(II) hydroxide separated in this way is filtered, and the filtrate formed after separation with a concentration of <0.01 g / dm3 Ni is sent to the elimination or extraction operation, and the precipitate of raw Ni(OH)2 separated in this way is sent to the purification stage, which is carried out cyclically with water, using 0.03 - 0.08 dm3 of water per 10 g of precipitate in one cycle, in such a way that the Ni(OH)2 precipitate is mixed with water for at least 60 minutes, at a temperature in the range of 30°C - 50°C, and washing is carried out cyclically from 2 to 6 times, the solutions formed after cyclic purification combine is filtered and recycled to prepare NaOH used in the Ni(OH)2 separation operation or in the elimination process,and to the purified Ni(OH)2 precipitate remaining after the last filtration, a mixture of alcohols consisting of at least 70% by volume of isopropyl alcohol and / or ethanol and / or methanol is added, constituting / constituting the remainder, in an amount of maximum 0.05 dm3 for each 10 g of precipitate, the Ni(OH)2 precipitate is mixed with the alcohol mixture for up to 15 minutes at room temperature, and the resulting alcohol filtrates are returned to the washing stage up to 100 times, an aqueous solution of rhenic (VII) acid with a concentration of at least 200 g / dm3 is added to the thus purified Ni(OH)2, so that the final pH of the solution is not lower than 6.3, and such a mixture is stirred intensively at a temperature not exceeding 80°C, for at least 1 h, monitoring the pH all the time, after which the remaining precipitate of unreacted nickel(II) hydroxide is separated from the solution and sent to the dehydration and separation stage Ni(OH)2, and the solution with a minimum pH of 6.6 is sent to evaporation to dryness, the evaporation is carried out at a temperature not exceeding 65°C,and the separated precipitate of the hydrated form of nickel(II) rhenate(VII) is sent for drying at 200°C until dry mass is obtained and then the resulting precipitate of anhydrous nickel(II) rhenate(VII) is stored in conditions without access of air.,