Process for introducing material into a treatment device

A method of heating and mixing a particulate material composition comprising the steps of:

• supplying hot gases to a rotatable drum and directing the hot gases from a point of introduction through an interior space of the drum toward an input end of the drum;
• introducing a first particulate material into the drum adjacent the input end and conveying the first particulate material in a direction counter to the direction of the hot gases toward the output end while heating the material and drum;
• diverting the heated first particulate material into an outer mixing chamber by directing the first material through radially extending openings provided between the interior space and the outer mixing chamber, the heated first particulate material being diverted into the mixing chamber at a point upstream of the point at which the hot gases are supplied to the drum relative to the direction of conveyance of the first material;
• introducing a second particulate material into the outer mixing chamber at a point upstream of the point of introduction at which the hot gases are supplied, and mixing the heated first particulate material with the second particulate material;
• conveying the first and second particulate materials along the outer mixing chamber in a direction counter to the direction of the hot gases toward the output end of the drum while shielding the materials from the hot gases with flights that extend circumferentially over the openings;
• heating the first and second particulate materials while the materials are moving through the outer mixing chambers, the second material being heated by contact with both the first particulate material and the heated drum while being shielded from the hot gases by the flights;
• and
• delivering the heated mixture of first and second materials from the outer mixing chamber and from the apparatus.