Investigation of vanadium precipitation induced by melamine in high-concentration vanadium solutions

V precipitation plays a vital role in the extraction of V from slags. Current industry-prevalent method for V precipitation, involving acidic ammonium salt, faces challenges such as high energy consumption, elevated levels of ammonia-nitrogen in wastewater, and complex treatments. These issues exert detrimental impacts on the environment and significantly hinder the sustainable growth of the V sector. Consequently, this study focused on utilizing melamine as a precipitation agent for V and systematically investigated the effects of various factors on V precipitation. Proposed process was optimized using response surface methodology, which included a comprehensive analysis of the mechanism and kinetics of V precipitation. Results indicated that under specific conditions (namely, pH = 2.0, melamine dosage (n(C3H6N6)/n(V)) = 0.25, V precipitation time (t) = 30 min, precipitation temperature = 80 degrees C, and stirring intensity = 300 rpm), the V precipitation rate surpassed 99 %. (NH4)2(VO(C2O4)2H2O)(H2O) was identified as the primary component of the V precipitation products, with V predominantly existing in the V5+ oxidation state. Additionally, the calcination of the V precipitate only yielded CO2 without generating harmful gases. Qualities of the final products met the specifications outlined in the industry standard YB/T 5304-2017. Importantly, the supernatant resulting from V precipitation lacked NH4+. V precipitation followed a pseudo-second-order kinetic mechanism and was diffusion-controlled, with activation energies below 42kJ/mol. Proposed novel technique demonstrates the potential to save 5310 Yuan per ton of V2O5 produced. This process exhibits an extremely high V recovery rate and low cost while mitigating the environmental impact associated with ammonia-nitrogen wastewater, demonstrating excellent prospects for industrial applications.