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Preparation and characterization of molybdenum trioxide from spent hydrodesulfurization catalyst
Barsha Dash,Indra Narayan Bhattacharya,Bhaskara Venkata Ramanamurthy,Raja Kishore Paramguru 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.7
An approach to produce molybdenum trioxide from spent hydrodesulfurization (HDS) catalyst, obtained from a petroleum refinery, is presented here. The spent catalyst was devolatilized at 600 ℃ so as to make it free from oils,organics and other volatile species. It was then roasted with sodium carbonate at a temperature of 850 ℃ for 30 min. The leaching efficiency for 20% soda roasted sample at 10% pulp density was 99.8%. From the solution molybdenum was precipitated out as ammonium molybdate at pH 1.0 with HCl and ammonium chloride. This ammonium molybdate was calcined at 750 ℃ to get MoO_3. The product was characterized by XRD. Its purity was determined titrimetrically and by ICP-AES.
N. K. Sahu,Barsha Dash,Suchismita Sahu,I. N. Bhattacharya,T. Subbaiah 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
The paper deals with the extraction of copper from the deposited material of the liner of the electrostatic precipitator (ESP) of the copper smelter plant. These precipitates of ESP liner (ESP dust) generally contain mixed phases of copper and arsenic. An attempt is made to extract copper from ESP dust, subsequently removing arsenic from the leach liquor. The ESP dust containing paramelaconite (6CuO·Cu2O), α-domeykite (Cu3As), metadomeykite (Cu3As),enargite (Cu3AsS4) and (Cu,Fe) SO4·H2O is not a naturally occurring geological mineral; thus comparatively high acid concentration and temperature are required to break the matrix of this mixed material so as to liberate the content. The leaching efficiency of copper was 97% at 97 oC. The acid concentration of 1.5M and pulp density of 20% was found to be optimum. The removal of arsenic as ferric arsenate was carried out in two stages: increasing the pH and precipitation of arsenic by adjusting pH of the solution and by adding ferrous sulfate and hydrogen peroxide. The optimum removal of arsenic was 95% when pH was raised to 2.35 followed by precipitation. The key progression of the process is the recovery of copper from ESP dust as well as removal of arsenic from the leach liquor.