Sergey Tkachenko
Faculty Environmental and Chemical Engineering
Speciality: the "Environment metallurgy"
Research of resource and environmental features of direct iron production in Ukraine
The scientific adviser: Ivan Mishenko
Abstract
Content
Introduction
1. Hot topics
2. Goals and objectives
3. Objects of research
4. Scientific novelty of work
5. Practical significance of results
6. Analysis of the organization of direct production of iron in foreign and domestic enterprises
6.1 Status vnedomennogo production abroad
6.2 Status vnedomennogo production in Ukraine
7. Options and process flow of organization of production of iron
8. Comoarison of some characteristics of iron and steel industry
8.1 Features of poor processing of iron ores
8.2 The presence of impurities of other elements
8.3 Physical properties of the ore
8.4 Use of fuels are not scarce
8.5 Using new types of energy
Conclusions
References
So far, the bulk of iron or steel (98%) was prepared by a two-stage scheme of iron-steel. Under this scheme, the iron from the ore in the blast furnace is almost completely converted to the iron and steel produced from iron or steel in converters furnaces. It does not matter for what proportion of scrap (up to 100%) was obtained steel as scrap, in turn, was derived from the iron.
Two-stage process, despite the apparent complexity compared to the direct production of steel from ore, has the following advantages: the ability to get the metal out of any given grade iron ore material, the high unit productivity of the unit, a relatively low level of material and energy costs, etc. Until recently, no one direct way of obtaining steel from ore could not stand the competition with a two-stage scheme.
In the second half of XX century. The situation in industry has changed dramatically. Incurred deficits of energy sources, area, distribution of metal production in developing countries, a sharp increase in the quality requirements of the metal and increased environmental demands made to revise the criteria for success in obtaining ferrous metals. It turned out, for example, that the maximum productivity of labor, characteristic of the most powerful blast furnaces and converters, and low energy costs they are not in themselves evidence of the advantages of these units, as this may not be the final national economic performance criteria. Substantially increased the value of factor "comfort" a person at work, level of intellectual contribution for his participation in the production process. It is likely that these factors are not very conscious, but still more powerful influence on the structure of production and its contents.
No wonder that in the second half of XX century. in the steel industry began to actively express themselves non-traditional methods of metal production. These methods are often combined under one name "direct provision of iron," although it is not very accurate, as will be discussed in more detail below.
The relevance of my work lies in the fact that the world reserves of coking coal are reduced, and in some regions they do not. In the well-known scheme is the intermediate product of steel cast iron, 50% of the cost of which is coke. Therefore in the future, sooner or later, blast furnaces will be replaced by direct receipt of iron, the main aspects of receiving it are considered in this paper.
The aim of this work is the analysis of resource and environmental capacity of iron production schemes exclude from the domain of the technological scheme and coke production.
The main objectives:
1. Reveal the essence of the methods of obtaining vnedomennogo metal;
2. Compare some of the characteristics of iron metallurgy and the metallurgy of iron;
3. Offer an alternative storage and disposal of plastic;
4. To study the classification of the processes of direct production of liquid metal;
5. Consider the reasons for the active development of iron metallurgy in the future;
The object of the study are as different technological schemes of sponge iron, and resource capabilities of our country.
Currently in Ukraine there is no one company working on advanced technological scheme (sponge iron - electric), but as mentioned earlier, global trends lead to the fact that sooner or later shift to the production of this scheme is inevitable.
5 PRACTICAL SIGNIFICANCE OF RESULTS
As a result of the conclusions will be drawn on the possibility of introducing vnedomennogo production in Ukraine and what are the consequences of such alterations will be.
6 ANALYSIS OF ORGANIZATION THE DIRECT PRODUCTION OF IRON IN FOREIGN AND DOMESTIC ENTERPRISES
The existing technological scheme for ferrous metals (iron and steel) is designed for the consumption of high-quality raw materials and smelting of ordinary quality. But the quality of natural raw material is continuously decreasing and the quality requirements of the metal is constantly increasing. In the future, the gap between the quality of raw materials and steel products will increase. This is due to the fact that stocks of high quality raw materials are depleted or are in the least developed areas, as well as the deterioration of mining and geological conditions of production and the need to organize the long haul. Therefore, the work on the existing technological scheme could lead to further reduction in the efficiency of production of ferrous metals. Requires fundamental changes in
This scheme, involving the use of fundamentally new technological processes and equipment. These changes will require a costly and long periods of time. This is due to several reasons. First, new technological processes of production of ferrous metals are still under development, are being extremely slow. Second, the fixed assets of steel industry are enormous and need to update them for decades. In the short term, along with the development and industrial development of new processes to achieve more efficient use of existing assets.
6.1 Status vnedomennogo production abroad
The development of the steel industry - the industry's leading iron and steel industry in the U.S. - is largely based on large reserves of iron ore in the area of the lake. Superior. Iron ore reserves in the country are far from exhausted, but the best ores have been developed as a result of predatory more than a century of operation. Huge stocks of relatively low quality ores in the vicinity of the lake. Superior began to develop only from the mid 50s. However, the process of industrial concentration takonitov not cost effective - the cost of iron ore pellets produced significantly higher cost of imported iron ore. Starting in the 50s steel monopoly to force the United States began importing high-quality iron ore, mainly from Canada and Venezuela. If in 1945 was provided by imports only 1% of all the needs of the U.S. steel industry for iron ore, in 1956 this proportion had risen to 23%, and c. 1995 - up to 41%. U.S. forced to import most of the alloying metals, including manganese, chromium and nickel. Due to the small amount of coking coal reserves and the rising cost of coke on the world market in the United States are actively developing and implementing methods of industrial production vnedomennogo iron.
One of the world's giant steel company "Nippon Steel" (Japan) started to commercialize the process of liquid-phase production of the metal "Romelt." It belongs to the considerable scientific and engineering achievements of modern technology and can play a significant role in future technological and environmental upgrading of metallurgical production.
In general, the process of liquid-phase reduction Romelt for their technical and economic parameters and quality, of course, refers to the considerable scientific and engineering achievements of modern metallurgy. According to Russian and foreign experts, this technology can play a significant role in the future, technological and environmental upgrading of metallurgical production.
6.2 Status vnedomennogo production in Ukraine
Currently in Ukraine, the processes of direct production of the metal are at the stage of development and undergo laboratory tests, for implementation on an industrial scale as such is not received.
This is largely due to the fact that the reserves of coking coal in Ukraine have not yet depleted, respectively, the transition to vnedomennye technology is uneconomical, since in this case will have to make significant capital investments for the upgrading of the whole metallurgical cycle.
7 OPTIONS AND PROCESS FLOW OF ORGANIZATION OF PRODUCTION OF IRON VNEDOMENNOGO
In the developed world, many schemes the direct production of metal from ore mined, most of them are fundamentally do not differ. But the technological scheme of the direct production of iron is significantly different from the classical scheme of steel using a blast furnace. Due to the fact that in obtaining the metal directly from the mined ore, on the basis of certain processes, eliminating the need to use not only the blast furnace and sinter plant, coke production, and in some cases may even refuse processing plant. For comparison, consider two schemes of production, the classic (using the blast furnace), and using the aggregate of direct reduction of iron ore.
7.1 Comparison of process flowsheet 2
Figure 7.1 presents a comparative diagram of the two most common patterns of production of industrial raw materials stali.Peredvizhenie the classical scheme indicated by black arrows. The scheme dates back to the iron ore, which, after the production is transferred to the processing plants for the separation of ore and rock, and then get a metal concentrate. Next, concentrate on the sintering process is sinter, and then sintered agglomerates is loaded into the blast furnace. It is also an important element of the production scheme is a Coke, because impossible without the coke blast furnace, coke is ready to load into the blast furnace along with the agglomerate. Product is iron blast furnace with a high carbon content is iron. Further, following the classical scheme of iron smelting is directed to a basic oxygen furnace or electric arc furnace. In the traditional scheme of steel can be used both of these units, depending on the need to obtain certain characteristics of the final metal.
1 - charge 2 - enrichment, 3 - agglomeration, 4 - unit is direct reduction of iron, 5 - blast furnace, 6 - coke production, 7 - ESP 8 - basic oxygen furnace, 9 - CCM
Figure 7.1 Flow chart of steel production by various methods.
Next, from the liquid steel smelting units entered the continuous casting machine and as a result of crystallization are the final products - slabs. The movement of raw materials for an alternative scheme indicated by red arrows. Vnedomennogo feature production is that in the aggregate (set Midrex) may be used as feedstock as well as sintering products directly using no rich iron ore. In the aggregate direct reduction of iron, the product of a melting sponge iron, which is subsequently sent to the electric-furnace steel for a given chemical composition and physical properties. Figure 7.2 shows the scheme of the installation with the use of tubular rotary kilns
1 - Elevator 2 - starting material, 3 - rotary kiln, 4 - vibrating feeder, 5 - Dust Collector, 6 - Cleaning the dust, and 7 - the zone of burning fuel and the melting of materials 8 - burner.
Figure 7.2 The experimental setup with tubular rotary oven (method Aznikur)
8 COMPARISON OF SOME CHARACTERISTICS OF IRON AND STEEL INDUSTRY IRON AND STEEL. CAUSES OF IRON AND STEEL
Assessment of the prospects of development of iron metallurgy requires a comparison of the main characteristics of iron and steel metallurgy of iron.
8.1 Features of poor processing of iron ores
Blast furnace process provides conditioned pig iron from iron ore with any iron. The content of iron affects only the technical - economic indices of the process. Metallization of low-grade ores (used for the purpose of iron metallurgy) can be effective only for bloomery iron and molten metal. Part of metalized material and sponge iron produced from low-grade ores is inefficient. Upon receipt of partially metallized materials from low-grade ores need more heat to the heating of waste rock and a greater consumption of reducing agent, due to diffusion difficulties in the recovery of iron oxides. In the production of sponge iron content in the ore tailings in the amount of> 2.5-3.0% leads to a sharp increase in energy consumption in electric arc furnaces, owing to the greater amount of slag.
8.2 The presence of impurities of other elements
Blast furnace provides conditioned Sulphur iron. Removal of iron from copper, phosphorus, arsenic is not possible. Low-temperature recovery processes vnedomennogo not provide removal of virtually any element other than the associated sulfur, where the degree of removal in the blast furnaces is 30%. In other words, all the incidental elements present in the original ore remains in the sponge iron and steelmaking unit in the fall. The same applies to getting bloomery metal (there can be some degree of sulfur removal). Preparation of the liquid metal can remove zinc from the process, alkali, and the degree of desulfurization and removal of arsenic and, possibly, phosphorus depends on the mode of the process.
8.3 Physical properties of the ore
In the blast furnace lump iron ore is processed exclusively material and the size of the pieces should not be less than 3-5 mm. Hence the need to process ore sintering (sintering, pelletizing). This requirement is mandatory for processes of sponge iron and bloomery shaft and rotary kilns. Low-temperature metallization of the crushed ore is available in special units (eg, fluidized-bed units). For most methods of obtaining vnedomennogo liquid metal pieces the size of the ore has no value, which excludes from metallurgical processes are costly agglomeration of fine ore.
8.4 Use of non-deficient fuels
For modern blast furnaces can not use another type of fuel, except for metallurgical coke. This is primarily due to the high strength characteristics of coke, the persistence of high temperatures. None of the presently known types of solid fuels can not compete in this respect with coke. One can certainly argue that the absence or disappearance of sources of coke will mean the end of the domain mode of production of the metal.
Currently, most known methods and techniques of metallurgy of iron does not require the use as a component of the charge of coke. Apply their different way of reducing gases (mainly in the production of sponge iron), non-deficient forms of coal, brown coal and their products, petroleum products, etc. The choice of fuel in this case is mainly due to the economic situation in the region.
Despite the fact that the use of plasma energy, nuclear and other new energy sources for the blast furnace is not excluded, the greatest effect on their application meets vnedomennomu obtaining the metal. This increases the chances of new technologies in competition with the domain process in the foreseeable future. The main issue, which determines in the future will determine the advantage of a method for producing the metal, is the power consumption of the process. In simplified form, it can be reduced to the flow of heat (or heat source) per unit of product. Leaving aside temporarily in other important indicators of technology (product quality, the requirements for charge materials, etc.), try to roughly estimate these quantities for different methods of iron metallurgy..
CONCLUSIONS
In connection with the above, we can draw some conclusions regarding the prospects for the development of iron metallurgy in modern conditions.
A. One of the main points that stimulate the current development of various methods of metallurgy of iron, a sharp decline in stocks or complete absence in the different regions of the world's coking coal (more coal, of which the different ways you can receive metallurgical coke). Blast Furnaces can not exist without the use of coke. Thus, in regions devoid of opportunities to get coke, the only way to get the primary metals industry is how to iron. The choice of method for producing a metal depends on the specific conditions (availability and quality of ore reserves and fuel type, range and the required amount of metal production, energy resources, etc.).
Two. At the present time have changed the requirements for the quality of the metal. Various technologies ensure receipt of iron metallurgy of ferrous metals of varying quality. Industrial experience has shown convincingly that the steel, resulting in electric furnaces from the sponge iron has better properties (strength, ductility, etc.). Exhaustive explanation of this phenomenon is still there. Most often the root cause of seeing that the metalized materials, in contrast to the scrap metal, essentially free of undesirable impurities, especially impurities of nonferrous metals. In this sense the "firstborn of the properties' mehallizovannyh materials, or" original charge ", stressing that the sponge iron is not passed before the stage of steel refining. Add that little metalized materials also contain dissolved gases in metal and nonmetallic inclusions.
Metal produced by liquid-phase reduction, as a rule, does not differ for the better the quality of pig iron. Most often as a unit for receiving molten metal from the mixture using an analog of the blast furnace hearth. These structural and technological features determine the behavior of elements (iron, silicon, manganese, sulfur, chromium, vanadium, etc.) and the composition of pig iron. In the most general case, we can say that the absence of coke heads, the channels that drain into the blast furnace slag and liquid metal, apparently, cause there was no significant recovery of manganese, vanadium, chromium, silicon, and others, and some increase in slag content of FeO. Is particularly limited in terms of liquid-phase reduction furnace hot metal desulphurization slag (slag due to lack of filtration and the growth of iron FeO content in slag), which determines the high content of sulfur in the liquid metal as compared to pig iron. Quality bloomery metal, usually much less than obtained by other methods.
Three. Technical and economic indices of blast furnaces improved somewhat with increasing size of the blast furnaces. In other words, build and operate a large blast furnaces often more profitable than low-power. Meanwhile, for small and medium-sized countries and individual regions need small plants that would be able to flexibly and quickly to change the production program, the range of raw materials and metal.
Units vnedomennogo get metal to a greater extent than the technological scheme of a blast furnace -> converter satisfies these requirements. In this connection, mini-plants built in the last two decades and are characterized by the volume of metal production by 1 million tons per year, have been widely disseminated.
Each element in the chain of production of modern coke plant -> concentrator -> sintering plant -> blast furnace shop -> converter plant is environmentally dangerous. The technology of iron metallurgy provides an exception to this chain of one of the most hazardous industries - Coke, concentration and agglomeration. Advanced factories, working on the technology of metallurgy of iron is almost completely harmless to the environment. This advantage of the new production scheme is one of the key, and in the future will be decisive.
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