Profitable recovery of phosphorus fromsewage sludge and meat bone mealby the Mephrec process – a new meansof thermal sludge and ash treatment

摘要

A special metallurgical recycling process has been developed to simultaneouslygenerate phosphate slag and gas for power generation within a single process. This wouldbe the prerequisite for the phosphorus recycling at acceptable costs. The material to beprocessed might be sewage sludge and/or meat & bone meal as well as ashes from theirmono-incineration. Depending upon market conditions this process can be operated forproducing greater phosphorus containing slag while simultaneously generating less gasfor power generation or for greater gas generation while simultaneously producing slag withlower phosphorus content.The Mephrec process has attained this goal by performing a special metallurgicalrecycling method. The waste material is agglomerated by briquetting and subsequentlysmelted in a shaft furnace using limestone or dolomite for slag formation and coke for energysupply that simultaneously acts as a reducing agent. The liquid slag produced and a smallliquid metallic phase will be tapped at about 1450°C and granulated within a jet of water orwithin a water bath.Now ingitec reports on studies with the Mephrec process performed within a small shaftfurnace situated at the hot test facility of the Freiberg Technical University (BergakademieFreiberg), Saxony/Germany, representing a smelting capacity of 300 kg/h of briquettedmaterial. The studies were performed using the above mentioned phosphorus containingwast materials.