A. L. Petelin

The role of alkalis and conserving resources in blast-furnace smelting

In ferrous metallurgy, the potential for conserving resources is often determined by the behavior of the impurity elements in metals production. This behavior may be highly complex, and its features may be interpreted differently by different experts. For example, the presence of zinc and alkali metals in the blast-furnace charge is known to result in excessive coke consumption, a reduction in the productivity of the furnace, an increase in the yield of top dust, shortening of the campaign, and in some cases to complete destabilization of the smelting operation. In choosing a technology for blast-furnace smelting, accounting for the entry of alkali metals and zinc into the furnace is one of the most important factors that determines the expediency of controlling the heat “from the top” or “from the bottom” features of the slag formation process, the gasdynamics of the smelting operation, and other characteristics.

Distribution of secondary gas emissions around steel plants

A method is proposed for analysis of the distribution of secondary gas emissions close to the ground around steel plants. The concentration field of secondary sulfuric-acid emissions in the atmosphere around OJSC Magnitogorsk Iron and Steel Works is derived for 2013. Charts of the sulfuric-acid distribution are prepared for two months with different wind patterns (July and September). The position of the concentration peak is determined in each case.

Possibility of cyanide formation in blast furnaces

5There is great concern currently about the presence of cyanides (salts of hydrocyanic acid) and other compounds containing the CN radical in metallurgical emissions. Cyanides are highly toxic and have a very deleterious impact on human health and on the environment. Cyanide formation is highly likely in ferrous metallurgy. In particular, cyanides may be formed from the components involved in blast-furnace processes: carbon, nitrogen, hydrogen, and alkali metals. The temperature in the working space of the blast furnace varies widely: from 100‐200 ° C (at the charge hole) to 2000‐ 2300 ° C (in the tuyeres). Various compounds containing the CN group are stable within this region. Analysis of the chemical composition of metallurgical emissions confirms the presence of cyanides. Thus, in the water of the slurry tank at Kosogorsk metallurgical plant, an elevated concentration of CN radicals is observed. This tank contains the byproducts obtained in purifying blast-furnace gas: charge-hole dust and slurry. In the present work, we analyze the thermodynamic conditions of cyanide stability in various temperature zones of the blast furnace, for different compositions of the batch and atmosphere, using IVTANTERMO thermodynamic-simulation software. This software permits the calculation of complex chemical equilibria in multicomponent, multiphase systems. The equilibrium composition of the reagents in the system may be calculated for specified temperature, pressure, and concentrations of the elements. The computational algorithm is based on minimizing the Gibbs energy of the system. The distinguishing feature of the IVTANTERMO software used in the present work is that the thermodynamic parameters employed are obtained by the analysis of primary data in the literature [1, 2]. A special calculation procedure has been developed for thermodynamic simulation of the blast-furnace process. The chemical elements in the system are selected on the basis of information regarding their presence in the blast furnace for specified conditions. Thus, the initial system includes nine elements: C, O 2 , H 2 , N 2 , Fe, K, Na, Cl, and F. Preliminary calculations show that the other elements in the blast furnace, such as Si, Ca, Al, Mg, Mn, etc., have little influence on the formation and decomposition of materials containing cyanides. Research shows that most of the cyanides formed in the blast furnace are the compounds CN, CN 2 , HCN, KCN, and NaCN. The salts NaCN and KCN and hydrocyanic acid HCN are most stable, i.e., correspond to the broadest interval of existence with variation in the external conditions, such as temperature, pressure, chemical composition, and redox potential. Thermodynamic analysis indicates that the quantity of each material formed in the blast furnace is determined by the following parameters:

Predicting the Risk of Generalized Air Pollution by Metallurgical Enterprises

The main factors responsible for the transportation of gaseous emissions from industrial enterprises over large distances are identified. A general approach to predicting the spatial distribution of gaseous emissions at large distances from metallurgical enterprises is proposed. This approach is based on the principle of maximum risk.

Effect of the Removal of Arsenic from Metal on the Environment

demand for ultrapure metals and alloys has increased in recent years, which is making it necessary to elevate product quality in order to reliably maintain market share. On the other hand, requirements are also being tightened in regard to toxic emissions. This trend is embodied in the promulgation of the new standards ISO-14000. Together, these two factors , along with the increasing use of new sources of raw materials – new deposits, industrial by-products, and household wastes – are making it necessary to carefully analyze the distribution of impurity elements between the main products and by-products of metallurgical processes. Special attention should be given to the elements that are harmful both to metallur-gical products and to the environment. One of the elements most deserving of such attention is arsenic, since it is fairly widespread in the traditional raw materials – ores, coal, and secondary resources. This situation presents additional problems related to the need to remove arsenic from raw materials during the preparatory stages and in metal production processes. Arsenic is an impurity which adversely affects the quality of the products of ferrous metallurgical plants. Arsenic tends to undergo dendritic segregation during the crystallization of steel ingots, which then leads to the formation of striated structures and makes the mechanical properties of the rolled product more anisotropic. A high arsenic concentration in steel lowers its ductility properties, reduces its strength characteristics, adversely affects weldability, and somewhat increases its tendency to undergo strain-hardening. The presence of arsenic in structural carbon and alloy steels reduces their hardenabil-ity and makes them more susceptible to reversible and irreversible temper brittleness. In the course of its removal from raw materials and metals, arsenic enters slag (in blast-furnace smelting) or changes to the gaseous state (mainly in pellet and sinter production and the blast-furnace process). Thus, arsenic enters the hydro-sphere and atmosphere of industrial regions through metallurgical waste products (solid slag, sludge, gaseous emissions, etc.). As a result, one important problem which arises in the production of metal from arsenic-bearing raw materials is study of the consequences of the removal of arsenic from those materials and the behavior of arsenic in the environment. Unfortunately, these matters have thus far received little attention. We will examine the environmental aspects of metallurgical production involving arsenic – one of the elements that poses a significant danger to the environment. It has a toxic effect not only on individual organisms …

Modeling the atmospheric concentration of secondary steel-plant emissions

A model is proposed for calculating the spatial distribution of secondary gaseous emissions around steel plants. The model is based on the maximum-risk principle. The following are the basic factors determining the maximum risk of exceeding the permissible concentration of the secondary emission: the formation of the emissions, the propagation of the emissions; and the falloff in concentration. Fundamental differences in the methods of calculating the propagation of primary and secondary gas emissions are noted. In particular, secondary emissions are generated not by point sources but over the whole region where the concentration of the primary emission exceeds its background value in the atmosphere. The concentration field of secondary sulfuricacid emissions is analyzed for a spatially distributed source on the basis of data from OAO Magnitogorskii Metallurgicheskii Kombinat. The H2SO4 concentration is plotted as a function of the distance from the source of the primary emission, for different wind speeds. The functional dependence of the H2SO4 concentration on the distance has a clear maximum. The position of the peak and the corresponding H2SO4 concentration may be determined for any wind speed if the mean power of the primary emission is known over the specified time interval.

CALCULATION MODEL FOR THE CONCENTRATION OF SECONDARY METALLURGICAL EMISSIONS INTO THE ATMOSPHERE

The model for calculating the distribution of secondary gas emissions in the outer influence zone of metallurgical enterprises is proposed. The model is based on the principle of maximum danger. The main factors that determine the risk of exceeding the maximum allowable concentration of the secondary emissions are denoted. There are 4. the forming factor, the distribution emissions factor and the concentration shrinkage factors. Fundamental differences of calculation methods of primary and secondary gas emissions were shown. There was also defined that the formation of secondary emission occurs in the volume of air space in which the concentration of primary emission exceeds 5. its background concentration in the atmosphere. The analysis of the secondary emissions concentration as a function of the distance from OJSC “Magnitogorsk Iron and Steel Works” was built with the help of the spatially distributed source method. Graphs of the H 2 SO 4 concentration depending on the distance from the source of the primary emission were built at different wind speeds. It has been found that the function of the concentration dependence on distance has a distinct maximum which value can be determined for any wind speed, knowing the average power of the primary emissions for a specific time period.

Diffusion along grain boundaries in multilayer materials

Metallographic data reveal the influence of the layer thickness in multilayer materials on the diffusion depth in chemicothermal nitriding. A model of accelerated penetration of the diffusional element at the layer boundaries is proposed.

Atmospheric propagation of gas emissions from metallurgical plants

807 Industrial gas emissions are of great concern to environmental agencies, who oversee air quality in the vicinity of industrial enterprises, in and around cities, and at population centers within industrial zones. Metallurgical gas emissions, while less hazardous than