NOVELTY - The hazardous waste treatment method comprises contacting waste and a host slag material within a plasma reactor having two plasma torches, and treating the waste and the host slag material to a plasma treatment to melt the host slag material and incorporate non-combustible components of the waste within the host slag material. The oxygen is introduced directly into the waste and the host slag material. A steam is present in the plasma reactor. The plasma reactor comprises a crucible for holding the waste and the host slag material. The crucible has a cooled internal surface.    USE - The method is useful for treating harmful substances such as radioactive materials and/or hazardous waste components such as asbestos.    ADVANTAGE - The method is robust and unaffected by the different types of asbestos containing material (ACM) used. The method is effectively converting the hazardous waste including ACM into a harmless slag product.    DETAILED DESCRIPTION - The hazardous waste treatment method comprises contacting waste and a host slag material within a plasma reactor having two plasma torches, and treating the waste and the host slag material to a plasma treatment to melt the host slag material and incorporate non-combustible components of the waste within the host slag material. The oxygen is introduced directly into the waste and the host slag material. A steam is present in the plasma reactor. The plasma reactor comprises a crucible for holding the waste and the host slag material. The crucible has a cooled internal surface. During the plasma treatment, the internal wall of the crucible is maintained at 100degreesC below the solidus temperature of the components of the host slag material. The internal wall of the crucible comprises refractory lined copper. The plasma torches are in a first mode in which an electric arc is passed between the torches above the level of the waste and host slag material and operated in a second mode in which an electric arc is passed between the torches through the waste and host slag material. The plasma torches comprise graphite electrodes. The waste and the host slag material are mechanically agitated during the plasma treatment. The waste to be treated contains radioactive material and/or hazardous waste materials such as air pollution control residue or asbestos. INDEPENDENT CLAIMS are included for:    (1) an apparatus for the plasma treatment of waste; and    (2) a slag material.    DESCRIPTION OF DRAWING(S) - The diagram shows a crucible:    Inner wall; (2)    Outer wall; (3)    Water cooling channels; (3A)    External flange diameter. (A)