The goal of this work was investigation of physical and chemical properties of calcining products obtained from bone sludge. The calcining process was carried out at the temperatures of 873-1223K, in chamber kilns in air atmosphere. X-ray investigations of phase composition confirmed that hydroxyapatite is the main component of calcining products. The phosphorus content in these products was close to the level of concentration of this element in typical phosphoric raw materials which proved right using waste materials from meat industry as a substitute for phosphoric raw materials. Studies of morphology of ashes obtained at different temperatures showed that the calcining temperature did not affect the product properties in essential manner. In all cases fine-crystalline products, with a similar shape and size of grain were obtained. Only ashes calcined at 1223K were characterized by slightly melted crystallites.