The raw material, proportioning ratio and production process for water free stopping mix for blast furnace tapping hole are described. At present under the condition of high capacity of blast furnace,the stopping mix for blast furnace tapping hole is developed in the directions of high strength, high corrosion resistance, long service life and environmental protection. Emphasis should be given to improve the structure and properties of the stopping mix for blast furnace tapping hole to produce a high quality stopping mix.
Study on modification of mechanical vertical cement kiln into lime kiln
Through the modifications of process equipment, such as the kiln proper, proportioning system, air supply system and discharge system etc. of the unused mechanical vertical cement kiln, the cement kiln is made to meet the requirement of lime calcination process. The qualified lime is produced with the comprehensive utilization of limestone tailings with grain size from 10mm to 20mm.
In order to eliminate the dangerous factors which may occur during the lime production of rotary kiln and avoid accident occurring, a deeper analysis is given to the hidden danger of safety existing in the various links of production and specific safety measures are put forward at the same time.
The key points, such as process flow, gunning process and corresponding parameters for kiln lining gunning repair technology of No.1 250m3 mechanical shaft kiln of Xintong Kiln Lining Material Co.，Ltd. of Xiangsteel, Hunan and the subsequent kiln heating-up schedule etc. are described. After the gunning repair of the kiln lining, the kiln has operated stably for one year. Up to now, no spalling phenomenon of gunned material occurs.
By using electro-fused magnesia as raw material, the effects of adding amounts and modes of α-Al2O3 and Cr2O3 on the creep resistance of magnesian material under high temperature are studied.And on the basis of this, the effects of additions of different types of Al2O3 on the creep resistance of magnesian material under high temperature are studied with addition of 3% Cr2O3. The result shows that with the increase of addition amount of Al2O3 the creep resistance of magnesian material under high temperature has increased. The creep resistance of the magnesian material with addition of 3% Cr2O3 is better than that of the low creep resistance high alumina bricks used on hot blast stove.
Through the site investigation of some passivated lime production plants in China, the working principle and grinding efficiency of different lime grinding equipment are described and compared in order to solve the issue of equipment selection in the active lime grinding process.
The analysis of working principle of ring hammer mill and its modification are carried out from the structure of the mill so that the mill can be operated on lime production line stably.
Technical modification of rotary distributor for Maerz limekiln of Handan Iron and Steel Company
Blocking phenomenon occurs often in the rotary distributor of 600t•d-1 Maerz limekiln of the Mining Subsidiary of Handan Iron and Steel Company during production, which affects the production output and quality of active lime seriously. Through study and analysis, several modifications are done and the problem of blocking phenomenon of the distributor is solved satisfactorily. This provides the guarantee for smooth production.
The course of technical improvement of the de-dusting process system for the exhausted gas from the lime shaft kiln of Shaoguan Calcination Plant of Shaoguan Iron and Steel Group Co. Ltd. is described. After the pulse bag filter de-dusting process that is advanced in process is used to substitute the water scrubbing and spraying de-dusting process, the difficult problem of exhausted gas over-standard discharge is solved thoroughly, the good de-dusting result is obtained, and the discharge within standard and clean production are realized.
In order to meet the requirements of different users, a new type step shape shaft kiln with the mode of space calcination has been developed. The shaft kiln is characterized by material falling with pushing rod, multiple fuel adapation, less investment and high active lime reactivity. Through trial industrial use of the shaft kiln, a good result has been achieved and it has a good popularization use value.
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.
Practice and perception of energy-saving type shaft kiln for calcination of small grain size limestone
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.
ISSN 1673-7792 CN 21-1544/TQ Sponsor:ACRE Coking & Refractory Engineering Consulting Corporation,MCC Postal Code:8-29
