In order to reveal the ring formation mechanism in the active lime rotary kiln of Bao-steel, the chemical composition, phase composition and microstructure of the ring are analyzed by wet chemical analysis, X-ray diffraction analysis and electronic scanning microscope. The high temperature simulation experiment reveals that the conditions for the ring formation are that low melting point matter functions as binding phase and the ash after coal burning reacts with calcium oxide to form low melting point oxides,these low melting point oxides stick to calcium oxides and the matters on the ring become thicker with the process progress. The liquid phase formation of the ash in coal under high temperature is the key problem for the ring formation in the active lime rotary kiln fired with coal.

Refractory Company of Anshan Iron and Steel Group summarized the experience on metallurgical lime production for many years and has realized the recovery and utilization of qualified undersize lime product, collected dust and undersize limestone. This not only realizes the comprehensive utilization of resource and reduces the waste discharge, but also creates the considerable economic benefit.

The cause of the breakage of refractory for the active lime rotary kiln is analyzed. It is thought that the adhering material on the lining of the rotary kiln is related with the reaction of silica and iron oxide, and calcium silicate and calcium oxide are main components for ring formation. The improvement of refractory can raise the service life of the rotary kiln.

The energy-saving shaft kiln calcines the limestone with small grain size ranging from 30mm to 80mm. Its monthly production of lime is 8 000t. The average calcium oxide content in lime is 91%；the reactivity of produced lime is 300mL；both over-burnt and under-burnt rates are ≤8%.Considerable economic benefit is obtained, and the waste of resource and production cost are reduced.

The laboratory of Hansteel Mining Subsidiary has worked out the best conditions and most reasonable method for measuring lime reactivity with optimized acid-base nitration method through laboratory experiment. The adoption of the optimized acid-base nitration measuring method shows that 10 times increase of the indicator concentration can make the final color change sensible, this has solved the issue of difficult observation and raised the accuracy of analyzed result and is favorable to control and improve the lime quality.

The refractory plastic based on calcined hard clay is prepared with calcined hard clay, pyrophyllite and clay. The physical properties of the refractory plastic based on calcined hard clay and of the refractory plastic based on bauxite are compared and analyzed. The result shows that the physical properties of the refractory plastic based on calcined hard clay are slightly lower than those of the refractory plastic based on bauxite, but its production cost is lower. The refractory plastic based on calcined hard clay can be substituted for part of the refractory plastic based on bauxite and used at the roof area in the low temperature zone and flue area of heating furnace, with good application result.