Synergetic Effect of Coal Flyash as a Scrubber to Acidic Wastes of the Phosphate Fertilizers Industry

Fly ash is produced in Israeli power stations via bituminous combustion At present 1.5 million tons of fly ash are produced annually in 4 power stations and only ~50% of it is used as a cement additive. The rest is utilized in the construction industry. Environmental regulations in Israel define fly ash as a non hazardous material but still the regulations impose that any potential utilization needs special permit from the Ministry of Environmental Affairs. Thus the regulations imply that the ash to be used will be in accordance with the CALWET or the improved EPA-TCLP1311 leaching methods. The fly ash produced in Israel is very basic due to the low sulfur appreciable (up to 12%) mineral matter of the imported coals. Thus it is a good potential chemical scrubber to acidic wastes. The fertilizer industry in Israel produces mainly phosphate based products. The production methods rely heavily on dissolution of phosphate rock in strong acids. Thus large quantities of acidic wastes are produced. These wastes have to be treated before final storage. We have checked the possibility of using the fly ash to neutralize the acidity and fix the heavy toxic elements contained within the wastes. The results show that the fly ash is an excellent scrubber and also that it's large surface area serves as a very efficient absorber to the toxic heavy metals from