• Increasing pH during hydrolysis precipitation mitigates the negative effect of manganese, although higher Mn concentrations (5.69–15.38 g/L) ultimately lower the vanadium precipitation rate at elevated temperatures and longer times.
• Elevated manganese concentration leads to denser precipitates, reduced V2O5 grain size, enhanced agglomeration, and a 2.55% decrease in product purity.
• In acidic ammonium salt precipitation, raising pH counteracts the negative influence of manganese and reduces the required ammonium sulfate dosage, while Mn is unevenly adsorbed on precipitates.
• Despite grain shrinkage and densification during ammonium salt precipitation, final V2O5 purity remains above 99.3%, indicating manganese roasting mainly affects hydrolysis rather than acidic ammonium salt precipitation.