High‐temperature decontamination and utilization of phosphogypsum
Abstract
Waste piles of phosphogypsum formed from deposits of phosphoric acid production by‐product loom near the city of Kedainiai in the center of Lithuania. Every year about 250 thousand tons of this by‐product were gathered when the plant was in full operation. At present, about 13 to 15 million tons of phosphogypsum have accumulated which is mainly gypsum dihydrate – (95–98) %, however, contaminated with phosphoric and fluoric acids as well as with other hazardous admixtures what makes this raw material ecologically harmful and also hampers the use of phosphogypsum instead of natural gypsum for the production of binding materials. These materials pollute the environment. Phosphogypsum can be “deacidified” with lime and then treated as normal natural gypsum to obtain hemi hydrate gypsum. However, good‐quality binding materials were not obtained in this case. Heating of phosphogypsum up to a temperature of 600 °C provides for the decomposition and elimination of binding obstruction admixtures. Heating to 1000 °C and higher temperatures causes the decomposition of the former with the formation of an activator in anhydrite lime and thus anhydrite cement. In general, the utilization of this environmentally harmful waste and the binding of toxic pollutants can contribute to the solution of environmental problems in the central region of Lithuania.
Reikšminiai žodžiai: nukenksminimas, utilizavimas, fosfogipsas, kaolinas, aukštatemperatūris apdeginimas, rišamosios medžiagos.
First Published Online: 14 Oct 2010
Keyword : detoxication, utilization, phosphogypsum, kaolin, high‐temperature burning, binding materials
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