Production of Nickel Oxalate Dihydrate from Spent Ni-Mo Hydrodesulfurization Catalyst

Abstract

Spent Ni-Mo HDS catalyst is one of the most important secondary resources for the recovery of valuable metals. Recovery processes are important from the economical and environmental point of view. Ni content of Ni-Mo HDS catalyst was determined as 5.27 % after oxidative roasting. Production of NiC2O4 center dot 2H(2)O from roasted HDS catalyst was investigated in this work. It is seen from the ICP-OES analysis that nickel concentration in the solution was increased to a maximum value at the beginning of the experiment and then decreased. NiC2O4 center dot 2H(2)O was formed in a consecutive reaction in two steps. NiC2O4 center dot 2H(2)O was produced with efficiency of 99.1 % from the experiment carried out using 1/10 solid/liquid ratio, 40 degrees C temperature, 1 M oxalic acid, 300 rpm stirring speed and 480 minutes reaction duration. TG-DTA analysis performed in dry air atmosphere showed that NiC2O4 center dot 2H(2)O produced decomposed in two steps and formed Ni0 after second decomposition step at about 350 degrees C.