The development history of rotary kiln

          Rotary equipment,which is called rotary kiln, is widely used in buiding material, metallurgy,  chemical engineering, and environment protection industrials for the mechanical, physical or chemical treatments to solid materials.
          The application of rotary kiln originated from the cement production. British cementer J.Asp invented soil shaft kiln of intermittent operation in 1824; A German invented multilayer shaft kiln of continuous operation in1883; British ERansome invented the rotary kiln in 1885 which was put into production after obtaining the patent in England and America and gained considerable economic benefits. The invention of rotary kiln makes the cement industry develop rapidly and promotes the study on application of rotary kiln. The rotary kiln is used in many industrial fields and takes a more important role in these productions. The rotary kiln becomes the core equipment in enterprise production. The technical characteristic and service behavior of rotary kiln are essential to the quality, output and cost of the product. "As long as the big kiln is running, the money is coming." This ballad is a vivid description on the importance of rotary kiln in production.     
          The rotary kiln is most often used in cement industry. The whole production technology of cement is summarized as "two grinding and one burning". "One burning" means the technological process of burning the ground and prepared raw material into clinker by the high temprature of rotary kiln. So the rotary kiln is the main engine in cement production, and is commonly referred to as "heart" of cement factory. In building material industry, besides roasting cement clinker, the rotary kiln is also used for roasting clay, limestone and drying slag, etc. In the refractory material production, the rotary kiln is adopted to roast raw material to stabilize its dimention and increase its strenghth, and then the material is reprocessed and shaped up.In nonferrous and ferrous metallurgy, the rotary kiln is the smelting equipment of iron, aluminium, copper,zinc,tin,nickel,tungsten,chromium,file,etc.The rotary kiln is used for sintering and roasting to ore, concentrate, intermedium, etc.
          For example,in the production of aluminium,the rotary kiln is used to roast aluminium hydroxide into alumina; in iron-making, the rotary kiln is used to produce pellet for blast-furnace ironmaking;in the overseas "SL/RN method" and "Krupp method", the rotary kiln is used for direct reduction to iron ore; the chlorination volatilization roasting method uses rotary kiln to extract tin and lead; in the process of beneficiation, the rotary kiln is used for magnetizing roast to the lean iron ore to make the ore change from its previous weak magnetism to strong magnetism which is good for magnetic separation;in chemical industry, the rotary kiln is used to produce soda, roast phosphatic fertilizer and barium sulphide. LapPle from America invented a new process of producing phosphoric acid by rotary kiln in 1960's. That process features in low energy consumption, low power utilization, no sulfuric acid and allowing to use middle and low grade phosphorite, and so is popularized soon.
         In environmental protection, the rotary cement kiln is used to burn hazardous wastes and garbage in developped country for more than 20 years, which not only make the wastes minimization and harmlessness, but also utilize the waste as fuel, save the coal powder, and recycle the waste.