With the increasingly strict requirement of users on the sulfur content in steel,the theory and technology of clean steel deep desulfurization has been the focus of some research.To produce ultra-low sulfur clean steel,it couldn’t be achieved only by secondary refining,but by controlling the sulfur content during each smelting process, and it must according to the sulfur content of different steel type to choose the proper refining process.This paper under the enhanced desulfurizer to improve the performance of slag infiltration desulfurization process,developed a new type of desulfurizer.Through experiments on resistance furnace,we investigated the reaction mechanism in the ultra-low-sulfur-steel,and analyzed the key factors on elective desulphurization.This investigation provides the theatrical direction for the production of new ultra-low-sulfur-steels.This paper deals with sintering technology and desulphurization ability of new refining slag of 12CaO·7Al2O3,which has been opened up by foreign country in past two years,and investigated desulphurization ability of less-fluoride premelted slag. According to some diferent trial procedures,we did the thermodynamic balance trials and desulphurization tirals,and got the conclusions as follows.The calcium aluminate premelted slag has lower melting temperature and better fluidity in refining temperature on the base of low melting point phase 12CaO·7Al2O3.Because of high basicity and Al2O3 content,the slag system has high desulphurization ability,its desulphurization ability is highly improved by adding a lot of lime in course of refining process,especially it fits to Al-deoxidization steel desulphurization. The premelted slag containing CaC2 or BaO has satisfied the requirement of less-fluoride or free-fluoride,and which is harmless to the environment.The desulphurizer has the good desulphurization capability.Furthermore,the desulphurizer which has the high desulphurization speed could satisfy the requirement of high production rhythm in practice and its fit for the slag infiltration of ultra-lowsulfur-steels.The desulphurized slags which we researched has wide resource and low cost,its easy to storage and transport.
Zinc Hydrometallurgy is the most important method to produce zinc. The zinc electrowinning is a important procedure in zinc electronic deposition, whose Economic Index reflects the technical level of zinc smelting. The power consumption of the zinc electrowinning takes up 70% of the general energy consumption. The operation, technology and economic target of the zinc electrowinnin not only reflects the quality of Zinc Hydrometallurgy, but also the power consumption. To ensure sustainable development, the country has unveiled a series of concrete measure. It makes it difficult for local companies to enter the industry, which brings in more difficulty for industry expansion. More and more companies must have technical reform in order to improve electric energy using status and reduce power consumption.The electric energy of anodic reaction takes up 60% in the process. So it is important to choose the anode materials. Insoluble anodes were employed in the zinc tank. Nowadays, binary alloy anode plate and multi-alloy anode plate are commonly used. They can meet the requirement of the production, but the effectiveness and cost are not the same.How to select anode materials in production process is an important period. The performance characteristic of binary alloy anode plate and multi-alloy anode plate is analyzed by experiment in production groove, the amount and component of zinc separating out, the electric energy of consumption, the thickness and weight of anode electrode and useful time of anode electrode plate are researched with emphasis. Through the characteristic comparison of two kinds of anode electrode plate, the different of comprehensive characteristic in binary alloy anode plate and multi-alloy anode plate is realized. The temperature of electrolyte and the concentration of Mn2+ are also discussed. It can say that the concentration of Mn2+ is the main reason for characteristic change of anode electrode and high electric energy consumption, the targeted measure is given in controlling the temperature of electrolyte and the concentration of Mn2+.The research results can guide to develop the new anode materials. It can be used to choose scheme of zinc electrowinning in the transformation projects.
Zinc is one of the important nonferrous metals. China is the world’s leading zinc producer. Nowadays, the consumption and production of zinc are respectively increasing year by year. Zinc smelting industries are generally facing a conflict between the increasing demand for zinc and the shortage of zinc concentrate. Changeful and high miscellaneous zinc concentrate will become the main raw materials of zinc smelting. The use of Changeful Zinc Concentrate will have a direct impact on the production conditions of zinc hydrometallurgy process. Fluidized roasting is an important process during the Zinc Smelting. The operating conditions such as roasting temperature, roasting time, the ratio of wind to material and the exports’ pressure of fumes will have an important impact on the quality of zinc calcine. It is related to normal operation of the whole zinc hydrometallurgy process.Firstly, the main existing problems, new progress and the developmental orientation of zinc hydrometallurgy process are discussed in this paper. Then there is a focus on the changes of fluidized roasting process for zinc and associated elements. The thermodynamics and kinetics of fluidized roasting process are studied, and the Mechanism of zinc ferrite formation is analyzed. It points out that the formation of zinc ferrite is the main factor which affects the quality of zinc calcine. At the same time a way to reduce zinc ferrite generation is proposed.Based on collecting samples and data of roasting production on the production site and the theoretical analysis, the influence factors for the rate of soluble zinc, soluble iron, soluble sulphur and soluble silicon dioxide are studied. When the Zinc Concentrate have complex sources, the prediction BP neural network between material constituent, technological conditions and above zinc calcine are established. The BP neural network can predict the quality of zinc calcine, and can play a guide role in adjusting the roasting process operating parameters. There is no determined theory or method in choosing the number of hidden layer nodes in neural network. In this paper an optimization algorithm based on the principle of golden section is adopted to design the number of hidden layer nodes in neural network. By adopting traingdm function (momentum gradient drop the back-propagation algorithm) to train BP network, by comparing the predictive indexes with industrial data, and by drawing a conclusion that the predictive effect is good, neural network can be predicted accurately to set up prediction network.By designing the BP neural network the problem of hard establishment for mathematical model between technological conditions and the quality of zinc calcine is solved. So it is a meaningful attempt at zinc fluidized roasting process.
It is an important measure to increase the pulverized coal injection (PCI) for reducing the coke ratio and production cost of iron-making in the blast furnace (BF) production. However, as the greatly increasing of the coal injection ratio, the measure appears many problems such as the unburned coal powder increasing before the tuyere, permeability deterioration in a certain condition of burden, etc. By taking measures to enhance combustion of pulverized coal (PC), the coal powder can burn faster in the tuyere. By adding the appropriate amount of combustion-supporting agent on pulverized coal injection for BF, and combining with measures such as blast furnace operation, the ignition temperature of coal powder to furnace can be decreased, the combustion efficiency be improved, the coke ratio of BF and production cost of iron-making be decreased accordingly.In practice of increasing the PCI of YiCheng steel company, along with the increase of the coal injection ratio, many problems were found, such as decline in burning rate of pulverized coal, increase in the carbon content of blast furnace Gas Ash. According to actual condition of iron manufacture in YiCheng steel company, by using the methods of theoretical analysis and experimental research, the practical production to seek for the suitable combustion-supporting agent on PCI for BF in YiCheng steel company was studied; meanwhile, some suggestions were given to the reasonable industrial production for BF in YiCheng steel company.Through the two stages of the development in laboratory and the industrial production of combustion-supporting agent on PCI for BF, conclusions are as follows:(1)The laboratory result showed that the combustion properties of PC can be improved obviously by adding combustion-supporting agent, and the addition of the second formula has the best effect. By the addition of the second formula in 0.4%, the ignition temperature of PC decreased 24℃, the burning completely temperature decreased 51.5℃, and the relative completed burning time reduces 15.4%. Meanwhile, the calculation of exothermal area on DSC curve method was used to compare and analyse the influence when the combustion catalyst was injected into the PC, the results showed that the addition in 0.4% has the best effect, and the combustion properties has a downward trend over 0.4%.(2) By increasing the proportion of PC at -200 mesh and improving oxygen-enriched rate, the combustion properties of PC can be improved more favorable, and the combustion-supporting effect can be given more fully play. The laboratory result showed that a better combustion efficiency has been achieved in the condition of 70% pulverized coal -200, 3% oxygen-enriched rate and 0.4% combustion-supporting agents blending rate.(3) It was found that in the industrial production of combustion-supporting agent on PCI for BF in YiCheng steel company , the coal injection rate and the coal injection effect has a great improving by adding with the combustion-supporting agents. Meanwhile, the ignition temperature of PC was decreased; the combustion rate and the combustion efficiency were improved. Though the expected goal of the experiment has be achieved basically, it is also needed more industrial production practice for master the coal injection influence of blast furnace operation and the grade of raw mineral. And the next goal is designing a suitable equipment and process of combustion-supporting agent on PCI for BF.
In the construction process, the progress and quality management, investment (cost), security management tied one of the four, and quality is fundamental, investment is the key, security is protected and progress is the core, is to ensure that the investment income on time Decisive factor, no progress of the project, other work on the management did not object. For different construction projects, its management methods will have some differences, the need to combine theory with practice, constantly sum up experience and lessons.In a joint venture in the iron and steel, construction management BF most complex and difficult also the largest. In this paper, the construction progress of the blast furnace project management, use of the progress of construction project management theory and application systems theory, operational research and network technology approach, combining features of the blast furnace systems engineering and construction experience, from the progress of the preparation of plans, implementation, Check and adjust to a more systematic study. In this paper, the results include the following:1、the blast furnace project in the construction of the basic structure of the decomposition of the system, and considered the working relationship on the basis of a blast furnace project summarized the progress of the construction methods.2、through the implementation of the scheme to progress in the process of Jiaodi, responsibilities, programmes and measures to study the progress of plans to blast furnace construction project in the process of management methods. 3、plans to check the progress, need to collect, collate, compared to the actual analysis of specific data, and the progress of the adjustment of principles and plan corrective methods, on the steps.For the above three areas, use of Zhangjiagang in Jiangsu Sha-Steel, Acer # 3 blast furnace steel-making Co., Ltd. (2500 m~3) works were carried out as an example of the positive note, with a view to the blast furnace project management of construction progress can play a reference.
In modern continuous metal cast process, the quality of liquid steel is the promise of that of the steel products, while the slag is the main cause of pollution of liquid steel ,it is very severe to prevent slag from flowing from one process to the next process ,that just is Slag Detecting ,which includes two main phases: converter-ladle slag detecting and ladle-tundish slag detecting. This subject focuses on the later.According to the existing slag detecting method based on infrared image, we came up with our own approach in this dissertation, which paid more attention on processing the infrared image of the surface of the tundish ,and then calculated the character when slag emerges, which made the criterion of the wholesome detection.In this dissertation, reasonable presumption was made on the character of the object’s infrared image, and according such presumption, image was weighted ,by which, meaningful signal was intensified, while redundant signal was depressed. Then algorithm for feature extraction based on moment function of images was developed.This dissertation intended mainly on theoretical research, in which we proposed some presumption, extracted some models of movement of slag, did some physical experiments. On the whole, this dissertation made some necessary exploration ,and will have some guiding significance in some extent.
This thesis is based on the No. 2 blast furnace(BF) of the Baosteel Group. Here, we put the RCM theory into practice and fulfilled its use in the maintenance of blast furnace equipment.The Baosteel Group is the biggest and most advancing iron-steel company in China. Most of the BF maintenance practice are based on the theory of CBM and AM nowadays. Although there are many obvious traits in this kind of maintenance program, it is impossible to give attention to both sides of integrity and cost. However, the RCM method can meet it very well.In the thesis, we firstly introduce the RCM theory, then we put it to the full use of analysis of equipment of Baosteel No.2 BF, and lastly we got a whole RCM program on equipment of BF. As the core of the iron system, the BF has a large number of equipment, and some advanced instruments are technical protected, so it is impossible to analyze every piece of equipment here. Provided this condition, we just discuss the key parts of BF. The main coverage includes dust system, cooling system, gas supply system, refractory etc. Besides ,we has centered on the core part of RCM–decision table. But for the sake of integrality of maintenance program, here we introduced the principles of other necessary parts, including construction of the data, combination of repair works. But those are not only appeared in RCM program, so this part of work is rather summary.Through the RCM analysis on equipment of No.2 BF of Baosteel,comparing the exist practice,we found that new maintenance method can not only improve the reliability of equipments with dangerous failure affect, but also prolong the service life of the whole equipment of BF under the asked safety.
Electromagntic stirring (EMS)can transform electromagntic power into rotary power of molten steel and drive the the molten steel rotating.Because of these,it can control solidification structure of molten steel, crystal state,inclusion, skin blowhole and intergranular and center segregation effectivly.Finally,the quality of steel can be improved.Mould electromagntic stirring (M-EMS) technology has been carried out on No.1 and No.5 billets caster in Chongsteel.The technical parameters are mainly from plant providing EMS technology.With the increase of steel grades , output and casting speed of No.1 and No.5 casters, in order to meet the requirement of steel quality, the further study must be done to make sure the better matching between M-EMS process parameter and continuous casting process.Based on the magnetic induction intensity of 150mm×150mm and 150mm×210mm cross sections been measured, the electromagnetic process parameters of tipical steel grades were analyzed.By industrial field tests,the optimal process parameters which assure the better steel subcutaneous quality and crystal structure were obtained. The study results provided the theoretical and practical foundation for M-EMS technology applied properly at Chongsteel.The test results of electromagnetic stirring magnetic field of two cross sections showed that the maximums of magnetic induction of both cross sections were both at 100mm from mould upper port,that is the nearby center of mould.At 100mm from mould upper port (at meniscus),the magnetic induction of both cross sections were less than 50Gs,and the stirring current and frequency change had little effects on magnetic induction. At the mould upper half part , the increasing trend of magnetic induction of 150mm×210mm was stronger than that of 150mm×150mm.At 200mm from mould summit,that is 100mm from meniscus,the magnetic induction of 150mm×210mm was about 400Gs,but the magnetic induction of 150mm×150mm was only 150Gs at 300mm from mould summit,The magnetic induction was little larger at mould wall than at center,and with the increase of magnetic induction ,the difference was bcome larger.Using numerical simulation,the distribution feature of fluid profile under the function of electromagnetic force field was analysed.By analysing the strand quality with different electromagnetic stirring process parameters in Chongsteel,when the electrical current is 4Hz, the optimal process parameters of typical steel grades were obtained:the optimal electrical current of 70steel was 360A; the optimal electrical current of 40Cr、45A were both 320A; the optimal electrical current of 20CrMnTi was from 280A; the optimal electrical current of AM3 steel was 230A.
Research and Development of Powder Used for Prepairing Failing Forging Mould of Aeroengine Blade by Laser Cladding
As to backwards for big cracking susceptibility caused by thermal spraying powders used in the failing aeroengine pieces high-temperature forging mould repaired with laser cladding technology and problems for easy abscission of coating caused in high-temperature service environment（＞800℃）,a kind of Fe-based alloy powder used in the failing forging mould repaired with laser cladding technology is researched and developed,through strain of thought of combination of alloying principle of materials with melting and solidifying characteristics during laser cladding and physical and chemical characteristics between substrate and powder,based on the mould steel（4Cr5W2SiV）.The optimum formulas of the powder and effect of the technological parameters on the microstructure and properties have been investigated.The microstructure and properties of coating prepared by laser cladding are studied by means of OM,SEM and XRD.The results indicate that no cracks coating and excellent chemical metallurgical bonding between cladding coating and substrate are obtained under condition of optimum formulas（wt.%:0.3C,25Cr,1.0Ni,1.7Si,1.5B,rest Fe）.The contents of slag agent B element must been controlled strictly:The optimum properties could been obtained under condition of 1.5wt.%B,Otherwise there may be many defects such as rough surface,cracks,holes and so on.Under condition of narrow laser cladding technology,other technological parameters are fixed,the hardness of the cladding coating changes within a certain of range with increase of the scaning speed.The cladding coating with good microstructure and properties ia obtained under condition of P=2.5KW,V=5mm/s,d=3mm, f=300mm,However,Since narrow laser cladding has more overlapping zones,leading to more soft band,furthermore,performance life is affected.Multi-cladding techenology of wide-band laser is a good approach to obtaining deeper cladding layers.This method is very suitable for repairing failure parts with serious wear.The optimum technological parameters of broadband laser cladding is as followed: f=315mm,P=3kW,V=3mm/s,d=3×15mm2.Under the condition of optimum technological parameters,the transition of microstructure is smooth in cladding coating.The whitebright band is plane crystals in the bonding zone.Cellular crystals is obtained in the bottom of cladding coating.The microstructure from the center to the surface of cladding coating transformes from dendritic crystals and cylinder crystals to equiaxed crystals.The delution ratio is less than 10%and the character of the powder is preserved in the cladding coating. The matrix phase in cladding coating isα-Fe,a certain amount of amorphous alloys such as Fe2B,Fe3C,FeSi and intermetallics such as Ni-Cr-Fe,Fe-Cr,Fe-Ni are distributed on the matrix phase.Therefore,good hardness and wear resistance of the cladding coating can be guaranteed.The hardness of surface is relatively low,the hardness about 0.3mm distance from surface increases obviously,the hardness keeps smooth increase from 0.3mm to 0.9mm. The hardness has the maximum in the H.A.Z,up to 810HV0.2,then it drops quickly from H.A.Z to substrate.The wear resistance of cladding coating is 1.5 times greater than that of substrate.
0Cr13 steel, one type of stainless steel, is liable to generate crack. Heat stress is one of the major reasons for the cracks. This experiment simulated the temperature field and stress field based on the equipment parameters and process parameters of the 0Cr13 steel thick slab continuous caster from TISCO, providing technical guidance for the establishment of the 0Cr13 steel thick slab cooling process.This paper firstly summarized the slab defects,second cooling system,thermo-stress model and survey of stress studying.Then the model of thermo-stress for continuous casting of slab was developed with considering stress condition of slab.At the same time material thermo-properties relating to temperature were considered.Through some investigation in product spot ,the temperature field and stress field of 1020×200mm slab were discussed in production casting speed.The simulation shows that thermo-stress is very great because of surface reheating of slab when the slab goes out of mold.It is the main reason of crack defects.Exterior shell bears tensile stress and interior shell bears compressive stress during the early stage of solidification.As casting speed and superheat increases , stress decreases.It is possible to describe the formation of crack and to estimate danger areas.Thereby rational cooling system should be adopted to decrease the temperature gradients to avoid crack formation.The simulation results to determine a reasonable production of continuous casting system has some help.