In a method and an apparatus for burning away organic components in raw phosphate, the burning taking place in two stages carried out in two reactors each having its separate air supply. A first suspension transport reactor (3) and a second reactor (5) are coupled in series via a separator (4), to which reactors combustion air (9), (11), preheated raw material (14), (15) and, if desired, fuel (8) are supplied separately. The reaction temperature in both reactors preferably lies in the range 700.degree.-850.degree. C. The majority of the organic components are burnt in the first stage which operates with a suspension having a density of 1-50 kg/m.sup.3. The remaining part of the organic components is burnt in the second stage which operates with a suspension density of 75-1600 kg/m.sup.3, a material retention time which is at least 4, preferably 10 times as long as the material retention time in the first stage, an air supply which is less than half the air supply for the first stage, and an oxygen percentage which is at least twice that of the first stage.