The application conditions and requirement of the refractories for firing zone of cement rotary kiln are analyzed and the applications of magnesia chrome bricks, magnesia spinel bricks, dolomite bricks and magnesia-calcium-zirconia bricks to the cement rotary kiln are discussed. The existing disadvantages and improvement measures are pointed out. It is considered that its developing direction is to use magnesia-calcium-zirconia bricks and spinel bricks and their application prospect is looked forward.
A summary is done for the problems occurring often during the bricklaying work of lime kiln.The effect of bricklaying quality on lime kiln is analyzed and prevention measures and solutions are put forward correspondingly.
The function of the mold powder for continuous casting and the structure features，working principle and technical specifications of a new type special equipment that produces the mold powder are described simply and the example of its practical data and result is given． The issue of difficult selection of the production mixing equipment for mold powder at present and the difficult issue of poor mixing result are solved． It has extensive potential applications．
Discussion on cement clinker production with hot melting state blast furnace slag and converter slag
Through the comparison and analysis of the components of ironmaking blast furnace slag, converter slag and cement clinker, it is known that their components are similar. The preliminary study deems that the optimization of the components of blast furnace slag and converter slag to make them to be mixed homogeneously under hot melting state, or the addition of part of mineral in them can produce the basically same components of cement clinker. This not only fully utilizes blast furnace slag, converter slag and their surplus heat, but also reduces the consumption of cement clinker resource and reaches the goal of comprehensive utilization of waste slag, energy saving, discharge reduction and low carbon.
The performance of PFL-1500 type vertical complex crusher, the actual application of the crusher in the metallurgical lime system in the calcination plant, the analysis of problems arising in the production process and corresponding prevention measures are described simply in the paper.
Technical practice of production capacity expansion and modification of beckenbach kiln
The major factors that restrict the expansion of Beckenbach kiln from 500t•d-1 to 550t•d-1 are described. The corresponding technical modification proposal is studied and discussed, the equipment modification is organized and implemented successfully and practical result is achieved. The use for reference and guiding significance are provided for the modification and design of the same type kilns.
Performance analysis and selection of silica materials for silicamortar of coke oven
Used as coke oven refractories, silicamortar is as important as silica brick to the life of coke oven. Therefore, to meet the requirement of super large volume coke oven, this paper focuses on the influence of various factors to the performance of silicamortar starting with the proportion of raw materials.
The energy-saving type vertical kiln is characterized by less investment, simple operation,short circle of construction, low energy consumption and so on, the more important point is that waste gas can be recovered and treated. Seven-layer kiln lining combination is used, which has a good thermal insulation performance. The cheap anthracite chip can be used as fuel. The production with hidden fire operation can control the standard coal consumption of each ton of lime within 145kg. The implementation of hidden fire operation can make the full utilization of the heat generated by fuel combustion and the limestone fed into the kiln can be fully preheated.
Kiln car is one of important integral part of tunnel kiln. The timely repair of worn kiln cars and safety travel of kiln cars in tunnel kiln have an important effect on the normal operation of tunnel kiln and heating schedule in tunnel kiln. We use the method of steel plate welding to the kiln front end to repair worn kiln car to make firing state more stable and to improve product quality. Through taking the measure of hole-drilling on kiln wall to rake sand, observe and remove the accumulated sand in tunnel kiln, the safety travel of kiln car and normal operation of tunnel kiln are ensured.
The process plan and construction investment for the phase Ⅱ magnesia lime production project are described. During production process, the crushing process for metallurgical magnesia lime is optimized. The rationality and advanced feature of the process of the new plan are expounded from the aspects of construction investment, operation result and so on.
Alumina hollow ball castable is produced with alumina hollow ball having different grain sizes as raw material and gel formed by silica fume as binder. Electro-fused magnesia is added in the castable to study the effect of magnesia in the electro-fused magnesia on the property of alumina hollow ball castable bonded by gel.
The corundum castable samples with different nano-CaCO3 contents are prepared by taking tabular corundum, alumina powder, commodity calcium carbonate, Alphabond300 as main raw materials and FS10 as water reducer, and their apparent porosities, bulk densities and crushing strengths after the heat treatments at 1 000℃ and 1 600℃ are measured. The microstructures of the materials are observed with scanning electronic microscope. The result shows that when the water reducer is added in a constant amount, with the increase of nano-CaCO3 addition amount the water demand is increased gradually, apparent porosity is raised and crushing strength is heightened inch by inch. Under the condition that the basically same flow values of the castables are controlled, apparent porosity is enlarged obviously, but crushing strength is heightened gradually with the increase of the nano-CaCO3 addition amount.
Silicon powder and aluminum powder are added into the matrix of corundum based refractory, β-Sialon is formed through in-situ nitrogenizing reaction and it is used to prepare β-Sialon bonded composite phase material. The effect of β-Sialon formed amount on the physical property, mechanical property, thermal shock resistance and so on of the material is studied. The phase composition and microstructure of the material are analyzed by XRD and SEM.
By using alumina hollow balls with grain sizes of 5~3mm, 3~2mm, 2~1mm and 1~0.2mm as raw material and adding SiO2 micro-powder the gel bonded alumina hollow ball castable is formed. The effect of pre- synthesized magnesia-alumina spinel on the properties of gel bonded alumina hollow ball castable is studied. The property determination of spinel specimens adding different amounts of spinel is carried out with various kinds of refractory product determining and analytical equipment and instrument.In combination with the theoretical analysis done with magnesia-alumina-silica phase diagram, the result shows that the addition of spinel promotes the sintering function of corundum phase in castable, raises the cold crushing strength and apparent porosity of gel bonded alumina hollow ball castale and reduces the bulk density of it. Spinel has the strengthening function to the matrix of the gel bonded alumina hollow ball castable and is favorable to improve the thermal shock resistance of it.
According to the features of Maerz lime kiln and in combination with the production experi ence of Maerz lime kiln of Hansteel, it is described that the equipment needs to be inspected and corre sponding measures are to be taken when the temperature of 11m lime discharge platform is too high. The good temperature control of 11m discharge platform of Maerz lime kiln is favorable to produce high quality product and prolong the service life of the lime kiln.
The method for direct determination of the silicon content in industrial silicon with hydrofluoric acid weight method is described. Sample is decomposed with nitric acid and hydrofluoric acid to form silicon tetrafluoride for removal and then it is burned in a high temperature oven. According to the mass difference before and after treatment of hydrofluoric acid, the mass percentage of silicon is calculated by subtracting the increment of ferric oxide formed by iron oxidation. The relative deviation of the method is below 0.20%.
In the production of siliceous bricks for hot blast stove, the method of mixing loading of checker bricks with other shaped bricks that is used in the past is changed and the centralized loading of checker bricks on the selected kiln cars in “two-step pit” location in tunnel kiln is done and the brick setting method is improved. Therefore the finished product qualified rate of checker bricks is raised and no influence on finished product rate of other shaped bricks is ensured.
The semidry process gunning mix which is suitable for the hot gunning of the coking chamber wall of coke oven is developed by taking calcined kaolinite, hard fireclay chamotte, SiO2 micropowder etc.as main raw material and selecting different kinds of binders and additives. The semidry gunning mix for coke oven hot repair is characterized by less water addition, low rebound rate and long gunning mix“hangingup” time, and its quality is up to and exceeds the quality of the same kind of foreign products.
The importance of the gap between the loosening sleeve type rolling ring and barrel backing plate, the methods for the theoretical value calculation and gap measurement are described. Through the analysis of the actually measured standardizing data of rotary kiln on site, the reliability of calculation and measuring methods are proved, and at the same time, the gap adjustment method is presented.
The problems often found in the production process of magnesia prefabricated parts are discussed and corresponding solving methods areput forward. These methods have a certain reference value for the production of magnesia prefabricated parts.
Environmental protection and energy saving light weight mullite thermal insulating brick is developed by taking fireclay and kyanite as raw materials and single pure sawdust as pure forming agent.Through the measurements of the bulk density, thermal coefficient and so on of the brick, it is showed that under the appropriate process conditions, the light weight thermal insulating brick with the density of 0.57g•cm-3 and 0.16W•（m•K）-1 thermal coefficient at 400℃ can be made and has the advantages of low cost, energy saving and environmental protection.
Application of coal-fired lime rotary kiln exhausted gas in pulverized coal preparation system medium for pulverized coal in the pulverized coal preparation system. Thus, it can not only make full use of waste heat in rotary kiln exhausted gas, save energy and reduce consumption, but also greatly improve the safety of coal preparation system because of low oxygen content in rotary kiln exhausted gas.
A high strength corundum silicon carbide castable is developed by using brown corundum and silicon carbide as major starting materials and calcium aluminate cement as binder. Through optimizing grain composition and adjusting the adding amounts of cement and composite micropowder, the cold and high temperature strengths of sample which is affected by various factors are determined. The result shows that the developed corundum silicon carbide castable not only had a higher stength at normal temperature, but also possesses a very high hot strength.
There is a Beckenbach lime kiln in Xingsteel. Its daily production capacity is 500t in which the metallurgical lime for steelmaking is about 450t and lime powder for sintering is approximate 50t. In order to verify the control index of CaO content in the metallurgical lime of the kiln, a calcination test is carried out for metallurgical lime. The test has found that the control of CaO content of metallurgical lime in the range from 88% to 89% is feasible whether it is considered from the aspect of energy saving or from the aspect of slagging.
Brief introduction to production line process and technical features of 600t•d-1 active lime rotary kiln
The production line for active lime of Bozhou Western Mining Co., Ltd., Xinjiang consists of two rotary kilns with production capacity of 600t•d-1 each. The project follows the process often used and combines with the local actual conditions. The site commissioning of the project is successful and it is put into production.
The process improvement of 600t•d-1 Maerz kiln is made through summarizing the operation experiences and lessons of Maerz lime kilns with production capacities of 400t•d-1 and 500t•d-1. Remarkable results is obtained.
The effect of adding different quantities of three kinds of micropowder additives A, B and C on the microstructure and properties of RM45 is studied with help of the method of SEM, XRD and so on. The result shows that the additions of all three kinds of micropowder additives can improve the microstructure of RM45 and reduce the formation of cristobalite phase, but additive C has the best result. After additive C is added into the raw materials of RM45, the redundant part of SiO2 is consumed to form the low melting point solid solution without the cristobalite phase formation in RM45. Its property can be compared favorably with Molochite produced in Great Britain.
An introduction is given to the heating-up process and key points for 80m long tunnel kiln with small cross section of the Refractory Materials Company of Masteel. It is pointed out that preparation work should be done well in early stage and temperature and pressure should be controlled accurately to ensure the smooth progress of the heating-up process.
In this paper, present situation of existing gas fired lime shaft-kiln is analyzed, and issues needing attention are proposed and the measures should be taken when coke oven gas is used as fuel for gas fired lime shaft-kiln for calcining lime.
ISSN 1673-7792 CN 21-1544/TQ Sponsor:ACRE Coking & Refractory Engineering Consulting Corporation,MCC Postal Code:8-29
