Research on V2O3 preparation by stepwise catalysis solution-phase hydrogen reduction from shale V-rich solution

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Solution-phase hydrogen reduction reaction (SpHR) was introduced to overcome the problems of ammonia nitrogen pollution, high energy consumption, and long production flow of traditional reduction roasting. From φ-pH diagram, the increase of reaction temperature, vanadium concentration and H2 partial pressure is beneficial to the preparation of V2O3. High purity V2O3 could not be prepared by single addition catalysis and synchronous catalysis in SpHR process, and the Ni + NiSO4 stepwise catalysis can effectively eliminate the problem of nickel wrapped in vanadium precipitates during the precipitation process. Under the optimal conditions of Ni + NiSO4 stepwise catalysis of nickel powder dosage 5 g/L, NiSO4 dosage 8 g/L, nickel powder catalytic time 90 min, NiSO4 catalytic time 30 min, the precipitate with nickel content 11.15 % was obtained, and Ni catalyst can be separated by magnetic separation with nickel recovery ratio of 99.52 %. Ni2+ in SpHR precipitates to Ni(OH)2 and then disintegrates and reduces to Ni, and Ni + NiSO4 stepwise catalysis includes two steps of pre-catalysis and secondary catalysis. After fourth cyclic experiment, the vanadium content of V2O3 product obtained was 67.46 % (i.e. 99.21 % V2O3 purity met the requirements of GB 40301–2021), the total recovery was 98.68 %, and the vanadium loss ratio was stable at 1.22 %. The process of SpHR has no ammonia nitrogen wastewater or waste gas discharge, and the price of V2O3 with purity more than 99 % on the market is about 260,000 ¥/t. The stepwise catalysis SpHR has remarkable environmental benefits and economic benefits.