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Development of Value Added Products from Industrial Wastes, Deactivated Catalysts and Flyash slag

A collaborative project on the development of value added products from industrial wastes, deactivated catalysts and flyash slag etc. is being carried out in collaboration with the Institute of Chemistry and Chemical Technology, Krasnoyarsk (Russia) under the ILTP program of cooperation between DST, India and RAS, Russia. The solid waste materials have been collected from respective industries and characterized for their physico-chemical properties. The deactivated catalysts were used for the recovery of metals followed by making inorganic pigments like nickel titanate, nickel chromate etc. The flyash slag has been used as an additional source of silica in the development of frit glaze materials in combination with the solid waste generated in zinc sulphate industry to prepare glazing materials that could be cured at low temperatures. The toxic ions have been very well complexed in the glassy material of the frit. High impact strength ceramic bodies were also developed from Fly-ash + talc mixtures utilizing phosphate based complex activators. The compatibility of tiles, glaze and pigments prepared under this project is being investigated.

Hazardous Anode Mud of Zinc Industry:

  • Zinc Industry waste anode mud contains 50-60% MnO2 and 5-15% PbO2

  • Process developed for recovery of Manganese values as MnSO4   and lead values to  make lead chromate pigment

Carbothermal treatment process developed using liquid reducing agent to reduce solid waste generation and for >95% recovery of manganese values.

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    Carbothermally reducedanode mud

    Manganese sulphatefrom anode mud

    Lead chromate pigment

    Tile glazed with Lead chromate pigment

Low Temperature Sintering Materials for Developing Energy Efficient Process

Ceramic bodies are sintered to achieve acceptable level of impact strength. In the case of silicate bonding, sintering is required to be carried out at temperatures in the range of 1150-1300oC whereby reinforcing mullite crystals are formed in the matrix. To lower the temperature of sintering, the role of phosphate bonding has been investigated. The reinforcing AlPO4 crystals have been observed to form at a lower temperature of 950oC which also provide impact strength higher than the silicate bonded ones. Further, the impact strength improved significantly by the incorporation of magnesium bearing mineral (talc) due to the formation of sodium magnesium phosphate. Accordingly, in addition to the development of ceramic materials that could be processed at low temperatures and possess high impact strength, the studies have also provided a valuable insight in the sintering process.