Brief introduction, pictures and technical parameters of rotary kiln
In building materials, metallurgy, chemical industry, environmental protection and many other production industries. Rotary circulating equipment is widely used for mechanical, physical or chemical treatment of solid materials, which is called rotary kiln.
The application of rotary kiln originated from cement production. 1824, British cement worker J. ASP invented the intermittent soil shaft kiln. 1883, Dietz invented the continuous multi-layer vertical kiln; 1885 British Langsam invented the rotary kiln, which was put into production after being patented in Britain and America, and soon gained considerable economic benefits. The invention of rotary kiln makes the cement industry develop rapidly, and also promotes the research on the application of rotary kiln. Soon rotary kiln was widely used in many industrial fields, and became more and more important in these production, becoming the core equipment of the corresponding enterprises. Its technical performance and operation largely determine the quality, output and cost of enterprise products. The folk proverb "As long as a big kiln turns, there will be tens of millions" vividly describes the importance of rotary kiln in production. In the application field of rotary kiln, the cement industry has the largest number. The whole production process of cement is summed up as "two grinding and one burning", in which "one burning" means mixing the raw materials prepared by grinding.
The process of burning mature materials under high temperature in rotary kiln. Therefore, rotary kiln is the main engine in cement production, commonly known as the "heart" of cement plant. In the building materials industry, rotary kiln is used to remove calcined cement.
In addition, it is also used for drying calcined clay, limestone and slag; In the production of refractories, raw materials are calcined in a rotary kiln to stabilize the size and increase the strength, and then processed and shaped. In the metallurgy of nonferrous metals and ferrous metals, iron, aluminum, copper, zinc, tin, nickel, tungsten, chromium, file and other metals are sintered and roasted in rotary kiln as melting equipment. For example, it is used to roast aluminum hydroxide into alumina in aluminum production; Used to produce pellets for blast furnace ironmaking; Foreign "SL/RN method" and "Krupp method" use it to directly reduce iron ore; Chlorination volatilization roasting method uses it to extract tin and lead. In mineral processing, lean iron ore is treated by rotary kiln.
Magnetization roasting can change the original weak magnetism of ore into strong magnetism, which is beneficial to magnetic separation. In chemical industry, rotary kiln is used to produce soda ash, calcined phosphate fertilizer and barium sulfide. In 1960s, LapPle and others in the United States invented a new process for producing phosphoric acid in rotary kiln. This method has the advantages of low energy consumption, low power consumption, no need for sulfuric acid, and the use of low-grade phosphate rock, and has been rapidly popularized.
In addition, in terms of environmental protection, the developed countries in the world have used cement kilns to burn hazardous wastes and garbage for more than 20 years, which not only realized the reduction and harmlessness of wastes, but also used wastes as fuel, saving pulverized coal and recycling wastes.
rotary cement kiln
At present, there are two main types of cement kilns. One is rotary kiln (also known as rotary kiln), the kiln barrel is horizontal (slightly inclined) and can do rotary motion; Another kind of kiln is vertical and does not rotate, which is called vertical kiln.
Types and characteristics of cement rotary kiln;
The development of cement industry has different production modes and different types of rotary kilns. According to the preparation methods of raw materials, it can be divided into dry production and wet production, and the rotary kiln suitable for production methods can be divided into dry rotary kiln and wet rotary kiln. Due to the different heat exchange devices at the kiln tail, it can be divided into different types of kilns. The classification of rotary kilns is roughly as follows:
1, type of wet rotary kiln:
The cement kiln used in wet production is called wet kiln, and wet production is to make raw materials into slurry with water content of 32%~40%. Due to the preparation of slurry with fluidity, the raw materials are evenly mixed, the composition of raw materials is uniform and the quality of sintered clinker is high, which is the main advantage of wet production.
2. Types of dry rotary kiln:
Compared with wet rotary kiln, dry rotary kiln has completely opposite advantages and disadvantages. Dry method makes raw meal into raw meal dry powder, and the water content is generally less than 65438 0%, so the heat required for evaporation of water is reduced compared with wet method. Due to the high exhaust temperature of hollow kiln, the heat consumption is not low. Dry production, raw meal is made into dry powder, and its fluidity is worse than mud. Therefore, the raw materials are not well mixed and the ingredients are uneven.
Types and characteristics of cement vertical kiln
There are two kinds of shaft kilns currently used in China: ordinary shaft kilns and mechanical shaft kilns.
Ordinary vertical kiln is manual feeding and manual unloading or mechanical feeding and manual unloading; Mechanical vertical kiln is mechanical feeding and mechanical unloading. The output, quality and labor productivity of mechanical shaft kiln are higher than those of ordinary shaft kiln. According to the technical policy requirements of building materials, small cement plants gradually replace ordinary vertical kilns with mechanized vertical kilns.