Synthesis and characterization of potassium silicate fertilizer using fly ashes of bituminous and sub-bituminous and lignite coal

Present study focuses on coal fly ash, a waste acquired from coal power plants for the synthesis of potassium based fertilizer by means of coal fly ash and lignite with simple blending of KOH and adding small amount of citric acid. Lignite and two types of fly ash bituminous and sub-bituminous were utilized for the formulation of fertilizer. X-ray diffraction (XRD) revealed the occurrence quartz and oxides of potassium in all fly ashes. XRD pattern also exhibited the orthoclase, mullite and zeolite as major compounds in fertilizer which were made from sub-bituminous ash. K2O, P2O5 and N were determined as essential compounds in sub-bituminous through using wet analysis. However, major presence of humic acid and organic matter were observed in lignite through wet analysis. Fourier transform infrared (FTIR) spectroscopy also confirmed the occurrence of humic acid in the form of carboxylic group in lignite and bituminous. Surface Mean Diameter measured by sieve analysis showed that particle size of sub-bituminous ash was smaller than others that most appropriate for synthesis of potassium silicate fertilizer.