After the end of the strand, the sinter passes through a spiked roll crusher and the hot screens to the rotating circular cooler. A number of fans are usually used for cooling, and the speed of the cooler is determined by:
The fines removed by the hot screens are conveyed to the return fines bin.
After cooling, the sinter is passed into the discharge bunker. At this stage, the level is controlled by varying the outlet feed rate (usually vibros).
The sinter then passes to the cold screening area, where it is passed through crushers and screens to produce particles in a specific size range. Sinter below the required size passes over a belt weigher and returns with the hot fines to the return fines bin.
The difference between the weight of the cold fines, and the weight of the total fines produced, gives a measure of the hot fines. Any abnormal variation in the rate of production of hot or cold return fines indicates a possible plant fault.
The following factors can affect the rate at which fines are produced:
Two important properties of sinter are basicity, which is controlled by the amount of limestone, and strength, which is controlled by coke content.
The sinter is now suitable for use in the blast furnace. Conveyors transport the material to the blast furnace stock house, where it is added to other materials to form the blast furnace burden.