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Direct leaching studies of mixture of zinc sulphide concentrate (concentrate) of Himalayan origin... more Direct leaching studies of mixture of zinc sulphide concentrate (concentrate) of Himalayan origin and manganese ore (ore) in stoichiometric proportion according to the reaction : ZnS + Mn02 + 2H2SO4 = ZnSO4 + MnSO4 + S° + 2H20 in dilute sulphuric acid (present in spent liquor from electro-winning cells) were carried out to test its amenability to a novel process developed at National Metallurgical Laboratory (NML). The liberated sulphur in the sludge was extracted in pure form. The effects of controlling parameters viz. acid-concentration, temperature and duration of leaching were investigated to optimize the leaching conditions. Extraction efficiencies of zinc and sulphur under best condition were —82% each, while that of manganese was —95%. The inextricable portion of zinc sulphide was investigated with the help of XRD analysis of the concentrate and the final residue. The leach solution purified by conventional hydro-metallurgical technique was fed to an electrolytic cell for sim...
This investigation deals with the recovery of chromium as sodium chromate of 99.5% purity from st... more This investigation deals with the recovery of chromium as sodium chromate of 99.5% purity from stainless steel dust containing 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.7 1%) and manganese (3.5 5%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that the roasting at 1073 K in 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed topochemical model involving chemical reactions at the surface with activation energy of 22 kJmol" 1. TG/DTA, XRD phase identification and SEM-EDX confirmed the experimental observation and the mode of reaction.
Electronic waste are generating all over the world. Due to large amount of electronic items used ... more Electronic waste are generating all over the world. Due to large amount of electronic items used in the recent past, a huge amount of electronic waste has dumped on the earth. Because of hazardous contents in the waste it is difficult for the environment to tolerate. This paper contains the different aspects of environment which has been created by electronic wastes. Mercury, lead, nickel, arsenic, tetrachloride, xylenes, tolune, styrene and methylene are most harmful to human health especially at high concentrations. These are very harmful substances and these are one kind of pollutants. It creates problem in the environment and pollute our water, earth and trees. Large amount of plastic generated by computer is also one kind of problem. The organic substances containing tetra-chloride, xylenes, toluene and styrene are creating problem in air. A suitable management of these waste alongwith recycling will solve the problem
The Journal of Solid Waste Technology and Management, 2011
The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity fr... more The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity from stainless steel dust. The dust contains 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.71%) and manganese (3.55%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that roasting at 1073 K for 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed a topochemical model involving chemical reactions at the surface with activation energy of 39 kJmol-1. TG/DTA, XRD phase identification and SEM microphotographs confirmed the experimental observation and the mode of reaction.
Direct leaching studies of mixture of zinc sulphide concentrate (concentrate) of Himalayan origin... more Direct leaching studies of mixture of zinc sulphide concentrate (concentrate) of Himalayan origin and manganese ore (ore) in stoichiometric proportion according to the reaction : ZnS + Mn02 + 2H2SO4 = ZnSO4 + MnSO4 + S° + 2H20 in dilute sulphuric acid (present in spent liquor from electro-winning cells) were carried out to test its amenability to a novel process developed at National Metallurgical Laboratory (NML). The liberated sulphur in the sludge was extracted in pure form. The effects of controlling parameters viz. acid-concentration, temperature and duration of leaching were investigated to optimize the leaching conditions. Extraction efficiencies of zinc and sulphur under best condition were —82% each, while that of manganese was —95%. The inextricable portion of zinc sulphide was investigated with the help of XRD analysis of the concentrate and the final residue. The leach solution purified by conventional hydro-metallurgical technique was fed to an electrolytic cell for sim...
This investigation deals with the recovery of chromium as sodium chromate of 99.5% purity from st... more This investigation deals with the recovery of chromium as sodium chromate of 99.5% purity from stainless steel dust containing 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.7 1%) and manganese (3.5 5%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that the roasting at 1073 K in 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed topochemical model involving chemical reactions at the surface with activation energy of 22 kJmol" 1. TG/DTA, XRD phase identification and SEM-EDX confirmed the experimental observation and the mode of reaction.
Electronic waste are generating all over the world. Due to large amount of electronic items used ... more Electronic waste are generating all over the world. Due to large amount of electronic items used in the recent past, a huge amount of electronic waste has dumped on the earth. Because of hazardous contents in the waste it is difficult for the environment to tolerate. This paper contains the different aspects of environment which has been created by electronic wastes. Mercury, lead, nickel, arsenic, tetrachloride, xylenes, tolune, styrene and methylene are most harmful to human health especially at high concentrations. These are very harmful substances and these are one kind of pollutants. It creates problem in the environment and pollute our water, earth and trees. Large amount of plastic generated by computer is also one kind of problem. The organic substances containing tetra-chloride, xylenes, toluene and styrene are creating problem in air. A suitable management of these waste alongwith recycling will solve the problem
The Journal of Solid Waste Technology and Management, 2011
The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity fr... more The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity from stainless steel dust. The dust contains 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.71%) and manganese (3.55%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that roasting at 1073 K for 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed a topochemical model involving chemical reactions at the surface with activation energy of 39 kJmol-1. TG/DTA, XRD phase identification and SEM microphotographs confirmed the experimental observation and the mode of reaction.