Hydrothermal decomposition of potassium feldspar under alkaline conditions

For the first time, a transitional compound [Ca2+ ≡ 2AlSi3O8− ≡ xOH−] was observed for K-feldspar hydrothermal alkaline decomposition, and a model was presented.

The Preparation of Ferronickel Powder from Nickel-Contained Sodium Jarosite Residue

nickel and iron was recovered as ferronickel from sodium jarosite residue containing nickel, the processes include alkaline decomposing residue, hydrogen reducing precipitations produced in alkaline decomposition process and magnetic separating reduced precipitations. The effects of alkaline decomposition temperature, the concentration of NaOH solution and solid/liquid ratio on the process of alkaline decomposing residue were examined. Meanwhile, the influence of hydrogen reduction temperature on the reduced products was studied, too. The results shown the natrojarosite in residue can be near completely decomposed to form hydroxide precipitations in the process of alkaline decomposition. In the process of hydrogen reduction, the rise of reduction temperature can increase the percent reduction for both nickel and iron in reduced results. But it is easier to reduce nickel than to reduce iron at the range of 750°C-950°C. When hydrogen reduction temperature was 950 °C, the percent reduction for nickel and iron in hydrogen reduction process was 95.81% and 94.4%, respectively. XRD tests indicated, except for ferronickel, there were still some impurities such as barium sulfate and barium oxide in reduced product. SEM test indicated the particles of precipitations will become fused together during hydrogen reduction process, so it is difficult to magnetic separate ferronickel purely from reduced results. The content of nickel and iron in magnetic separating product was only 11.64% and 62.40%.