Brief description of the structure of the drum granulator
Drum granulator is widely used in fertilizer granulation and iron ore spheroidization. It mainly consists of the following structures:
①rotary cylinder; ②motor; ③retaining ring; ④screen; ⑤belt conveyor; ⑥chute pipeline;
As shown below.
When the granulation starts, the binder can be added at the beginning, or it can be added after the material enters. In the process of spheroidizing iron ore, it is not necessary to add cohesive liquid. In the middle stage of spheroidizing, use a sprayer at a fixed position to spray water into the drum to replenish moisture, which is helpful for the spheroidizing process. In the granulation process of mixed fertilizers using other solutions such as mud, the required specific binding liquid can also be sprayed into the appropriate position through the spray device. Then feed the material (the material is composed of fresh material and recycled material) through the feeding system (belt conveyor, chute pipeline and other similar equipment) to make it rotate with the drum. When the liquid content of the material is appropriate, the material will be The granulation process takes place. The drum has a slope, and the angle between its axis and the horizontal plane is less than 10°. In this way, the material can be controlled to roll along the length of the tube while the drum is rotating, increasing the residence time of the material. And like the swash plate granulator, the structure of the inner surface of the drum has a great influence on the rolling of the material in the drum and the quality of the product. Usually, kidney lining, baffle, scraper and other structures are arranged in the drum. For example, in the iron ore spheroidizing process, the inside of the steel drum is usually lined with a layer of cement (about 25mm), or a layer of thermal expansion metal.
The function of the scraper is to maintain a corresponding thickness of the material on the inner surface of the drum, so that the material layer is uniform, and it is convenient for the material to turn and roll. Rubber baffles and liners and external vibrators are used to prevent accumulation during fertilizer granulation. In order to prevent material backflow and leakage, retaining rings are provided at both ends of the drum. For the retaining ring at the discharge end, it also has the effect of increasing the thickness of the material layer and the residence time of the material, and the retaining ring at the discharge end is different for different products. For example, when iron ore is spheroidized, a spiral discharge ring is usually used. The material is transported to the screen at the rear end of the drum through the discharge end. Sometimes the screen is also made into a cylindrical shape, which is integrated with the drum to form the discharge port of the product.