Quick review of rotary kiln technological process and applications

Rotary kiln process

1. Raw material preparation and drying and crushing process

Two kinds of materials, desulfurizer and reducing agent, are put into the quantitative hopper, and the quantitative hopper sends the materials to the drying chamber through the conveyor according to the weight ratio of the two materials to dry and mix the two materials. The moisture content of the dried material is less than 3%. The dried material is sent to the reducing agent crusher through the conveyor for crushing, and the crushing particle size is less than 1.5mm. The crushed materials are lifted to the high-level silo by the conveyor, and then sent to the storage silo by the conveyor. The concentrate powder is directly sent to the drying unit by the conveyor for drying. The moisture content after drying is less than 3%. The dried concentrate powder is sent to the high-level silo by the conveyor, and then sent to the storage material by the conveyor. warehouse.

2. Automatic loading process

This process can produce barrel-shaped, column-shaped or tile-shaped direct reduced iron as required. The charging system is composed of three parts: silo, quantitative pipe and charging head. The concentrate powder and reducing agent are discharged into the distribution silo through the storage silo, and then loaded into each reducing crucible by the charging head to realize the charging process crucible cloth.

3. Reduction roasting process

This process is completed in a rapid reduction furnace. Appropriate and stable furnace temperature and reduction time are the keys to determine the quality of DRI. This process includes three stages: preheating, reduction and cooling. First, the truck passes through the transmission mechanism, and sends the truck into the preheating section of the rapid reduction furnace. During this time, the moisture in the material is completely evaporated, the desulfurizer is decomposed, the temperature rises to the reduction temperature, and enters the high-temperature reduction section. The iron oxide is fully reduced to form elemental iron, and then enters the cooling section for cooling, and is cooled to below 200 °C before being released from the furnace.

4. Automatic unloading process

After the material is released from the furnace, it will drop to 100 ℃ ~ 50 ℃ at room temperature and then enter the unloading system for unloading. The ash is sucked away by the wind, and the direct reduced iron is taken away from the crucible by the grasping tongs to realize automatic unloading.

5. Product processing procedure

This process completes the direct reduced iron magnetic separation, crushing and passivation treatment - briquetting. The unloaded truck enters the loading system for loading. The DRI enters the intermediate silo through the unloading device. The direct reduced iron in the intermediate silo is transported to the direct reduced iron crusher for crushing through the conveyor, the crushed direct reduced iron is subjected to magnetic separation by the dry magnetic separator, and the magnetically separated direct reduced iron powder is transported by the conveyor to HDYJ for reduction. The iron briquetting unit is used for briquetting and storage through the transmission mechanism. The realization of cold briquetting effectively improves the oxidation resistance of DRI. It reduces the water absorption of DRI and reduces the volume, which is beneficial to the long-term storage and long-distance transportation of DRI. At the same time, it also improves the yield of molten steel when used. Therefore, it is very popular among steel-making enterprises. In the market competition It has strong vitality and competitiveness.

The rotary cement kiln's main purpose

1. In the building materials industry, in addition to calcining cement clinker, the rotary kiln process is also used for calcining clay, limestone and slag drying. In the production of refractory materials, the raw materials are calcined in a rotary kiln to make them stable in size and increase in strength, and then processed and formed.

2. During the beneficiation process, the rotary kiln process is used to magnetize and roast the lean iron ore, so that the original weak magnetism of the ore is changed to strong magnetism, which is beneficial to the magnetic separation.

3. In the chemical industry, the rotary kiln process is used to produce soda, calcine phosphate fertilizer, barium sulfide, etc. In the 1960s, LapPle and others in the United States invented a new process for producing phosphoric acid with a rotary kiln. The method has the advantages of low energy consumption, low electricity consumption, no need for sulfuric acid and the availability of medium and low grade phosphate rock.

4. The entire production process of cement is summarized as "two grinding and one firing", in which "one firing" is the process of firing the prepared raw meal after grinding into clinker under the high temperature of the rotary kiln. Therefore, the rotary kiln is the main engine in cement production and the key equipment in the cement production line, commonly known as the "heart" of the cement factory.

5. In terms of environmental protection, the rotary kiln process has been used to incinerate hazardous waste and garbage for more than 20 years. This not only reduces the amount of waste and makes it harmless, but also uses waste as fuel to save pulverized coal and achieve waste resourceization.