Uniform particles formed by hydrolysis of acid mine drainage with urea

The study describes a new way of treating of acid mine drainage (AMD) waters containing sulphate of Fe+ 3 and Al+ 3 as dominant components using homogenous thermal hydrolysis with urea. The model solution and the acid mine drainage solution were kept with urea at one of the selected temperatures (60 °C, 80 °C and 95 °C) in thermostatic bath. X-ray powder diffraction spectra identified four main phases in the hydrolysis products, namely: goethite, schwertmannite, ferrihydrite and jarosite. No crystalline phases of aluminum were detected. Depending on the precipitation conditions, the prepared samples consist of spherical aggregates of nanocrystals of various modifications of hydrated iron oxides. The specific surface area results show that with increasing content of Al3+, the specific surface area in the final product decreases. The results reveal that by homogenous hydrolysis of acid mine drainage with urea, it is possible to prepare easily filterable relatively pure oxide precipitates with a high degree of separation of Fe and Al.