The series of rotary roasting kilns for mineral powder are energy-saving kilns developed and manufactured by Changzhou Ganlin Dry on the basis of atmosphere protection kilns. The furnace temperature control is uniform, the long-term operation has a low failure rate, a long service life, and is stable and reliable. Inert gas protection, oxygen content in the furnace ≤ 20ppm. Suitable for roasting mineral powder.

During the roasting process, the rotary cylinder has a small inclination, and the material continuously moves from the feed end to the discharge end in the kiln. Kilns generally operate continuously and fully automatically. They can directly transport materials without the need for further conveying equipment, making these kilns more energy-efficient. Due to the significant mechanical impact of the rotary kiln roasting process on materials, it is necessary to specifically design a rotary kiln for the materials it processes. In the design and engineering of pyrolysis equipment, it is necessary to consider the characterization parameters of materials, including flow characteristics, flowability, bulk density, moisture content, and process temperature. For different materials, the inclination of the rotary cylinder along its length, the rotation speed of the rotary cylinder, and the additional components welded to the cylinder must be designed accordingly. In the ceramic, glass, and binder industries, rotary kilns are now used for heat treatment of powders, granules, blocks, and dry or wet mixtures. The main uses include drying, desorption, preheating, calcination, foaming, sintering, etc. On this basis, combined with typical applications under different atmospheres, according to the key production process differences of rotary roasting kilns, the heating types of equipment are the basic differences. There are two types: direct heating rotary kiln (Figure 1) and indirect heating rotary kiln (Figure 2). In the indirect heating rotary kiln, the rotary cylinder is heated from the outside. This can be achieved through a burner or electric heating Especially when the processed product is prone to generate strong dust, it must go through different temperature gradient requirements or be treated under special process conditions, such as inert or protective atmospheres. As the material of the rotary cylinder, metal pipes can be used at 1150 ° C according to the requirements of temperature, atmosphere, and material processing strength in the process. Internal heating rotary tubes are used to protect products from contamination and allow for much higher temperatures than metal tubes (up to 1600 ° C). However, the manufacturing process of the internal hot kiln is limited due to its geometric shape.

Figure 3 is a 3D model of a rotary roasting kiln with separate heating and cooling

Figure 3

The rotating cylinder is supported by two rolling rings on the tugboat. Driven by gears or sprockets using chains. The product is fed from the left side through a feeding screw conveyor or vibrating feeder. Mechanical seals are used at both ends of the rotary cylinder to isolate the kiln chamber atmosphere from the surrounding air. The sealing system is installed between the rigid shell components (feeding cover and discharging cover) and the rotating cylinder, and selecting the best sealing material can reduce the frictional force of relative motion. For those with inert gas or gas reacting in the rotary cylinder, sealing gas is usually used to assist in sealing. For roasting, only air is used, and radial packing is often used for sealing.

In the rotating drum, different internal cutting plates need to be welded according to the different process requirements and product performance of the processed materials. These are not only used to assist in the advancement of products, but also to improve the heat transfer and mixing of product flow, for example, by using additional baffle rings at the kiln outlet to increase the filling level of flowable bulk solids in the kiln. The heating equipment is installed in the enclosed furnace outside the rotating cylinder Heating is carried out through a burner or electric heater. According to the process requirements, the burner is divided into several control groups, and then the rotary cylinder is heated with flue gas to obtain a specific temperature distribution.

After heat treatment in a heated rotary tube, the product is usually cooled to near room temperature using a cooling process. Materials can be transported from the rotary roasting furnace to the cooling rotary kiln through a chute, as shown in Figure 3. Another method is to directly have a high-temperature roasting furnace and a cooling rotary kiln in a straight line, as shown in Figure 4

Figure 4

The rotary kiln must be fed and discharged through a locking system to reliably prevent air from entering the rotary cylinder body and avoid the problem of process gas entrainment into the cooling zone, which may cause moisture absorption. In addition, it is important to seal the rotating cylinder to prevent leakage.

The following is an introduction to direct rotary kilns:

The rotary kiln for direct heating is heated by a burner directly burning into the rotary cylinder, as shown in Figure 4. For this reason, this type of kiln is called an internally heated rotary kiln. The rotary kiln with direct heating is usually lined with fire-resistant bricks in the rotary tube. The main function of refractory bricks is thermal insulation, and in any case, they must be designed more as wear protection or as an inert protective layer between pipelines and solid blocks. This type of rotary kiln is heated directly and has a burner in front. In general, the direction of combustion gas and flue gas is opposite to that of the product.

Figure 4 shows the schematic diagram of the structure of a direct heating rotary kiln. The feeding system feeds materials from the left. The other end of the discharge end is the burner. The flue gas flows along the length of the inclined rotating tube towards the product. The cooling pipe enters through a shaft with a chute, and the cooling kiln is located under the unloading truck. For example, when the product is fed in the form of slip or slurry, a directly heated drum is also used. In this case, as shown in the figure below, a pre dryer with refractory insulation and internal components such as chains or scrapers is installed upstream of the rotating tube to avoid or eliminate any sedimentation formation.

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Application materials

mineral powder