5.3　Water Addition，Mixing and Granulating

5.3.1　When iron ore fines are the major raw materials，two-stage mixing shall be adopted.When the iron ore concentrates are the major raw materials and if pellet sintering is adopted，the three-stage mixing can be adopted with external coating of solid fuels.

5.3.2　The total mixing and granulating time should be 5-9min when adopting the drum mixer，the lower limit should be adopted when iron ore fines are the major raw materials，and the medium and upper limits should be adopted when iron ore concentrates are the major raw materials，including the granulating time for outside coating of solid fuels.

5.3.3　The filling ratio of the primary drum mixer should be 10%-16%，and that of the secondary drum mixer should be 9%-15%.

5.3.4　The primary drum mixer and the secondary drum mixer should be set up on the ground.

5.3.5　The drum mixer and feeding belt should be in a straight line.

5.3.6　The coal coating device of medium and small sized sinter machines should be installed on the high level platform of sintering and cooling room.

5.3.7　The particle size of external coating coal shall be less than 3mm.

5.3.8　The water addition to the mixture shall be automatically measured and controlled.

5.3.9　The mixture should undergo heating treatment，the heating media may be hot water and steam.The hot water shall be added into mixer and granulating machine，and steam should be added into coal coating device and mixture bin.