DSP-100 project with complex off-furnace steel treatment

Contents

INTRODUCTION

1. GENERAL PART

1.1. General description of arc electric smelting furnaces

1.2. Lining of arc electric smelting furnaces

1.3. Charge materials for arc electric steelmaking furnaces

1.4. Metal electromagnetic mixing device

1.5. Advantages and disadvantages of electric arc furnaces

2. SPECIAL PART

2.1. Design of modern high-power DSP-

2.2. Calculation of geometric dimensions of DSP-

2.3. Calculation of material balance of steel smelting in DSP-

2.4. Calculation of the energy balance of steel smelting in DSP-

2.5. Calculation of power of DSP- furnace transformer

 

3. ORGANIZATION OF METALLURGICAL PRODUCTION

3.1. Arrangement of charge melting technology in arc electric smelting furnaces

3.2. Organization of complex off-furnace steel processing technology

3.3. Organization of process control

3.4. Organization of production personnel

3.5. Layout of electric steel smelters with complex out-of-furnace treatment and continuous casting of steel

4. ECONOMICS OF PRODUCTION

4.1. Technical and economic indicators of electric steelmaking shop operation

4.2. Technical and economic indicators of DSP-

4.3. Justification of production need for project implementation 

4.4. Capital investments for  project implementation

4.5. Calculation of cost-effectiveness of the project

5. OCCUPATIONAL AND ENVIRONMENTAL PROTECTION 

ELECTRIC STEELMAKING

5.1. Main negative factors

5.2. Safety requirements

5.3. Fire and Electrical Safety

5.4. Calculation of ventilation and artificial lighting

5.5. Environmental protection

CONCLUSION

LIST OF SOURCES USED

Appendix A - Calculation of cost of 1 ton of open-hearth steel at OJSC "PMZ" in the base and design period

Appendix B - Specification. General view of DSP-

Appendix C - Specification. DSP-100 in section

Appendix D - Specification. Electrical smelter process diagram

Introduction

During the execution of the diploma project (DSP100 Project with complex off-furnace steel treatment) and the subsequent presentation of the studied material in the explanatory note, I will describe in detail the proposed modernization of the steel production technology at OJSC Chusovskaya Metallurgical Plant. Proposing the design of an arc electric furnace with a capacity of 100 tons (DSP100) with a complex off-furnace treatment of steel.

In a special part of the diploma project, I expect an arc steelmaking furnace with a capacity of 100 tons (DSP100). This type of furnace is classified as direct arc furnaces. In such furnaces, the arc burns between the electrodes and the molten metal, directly heating the metal. The center of high temperature (arc) is located near the surface of the metal. Thanks to the shielding effect of the electrodes, the vault of the furnace is partially protected from direct radiation of arcs, therefore, very large volumetric powers are permissible here, and high-temperature processes can be carried out. Electrodes in such furnaces are suspended vertically and work mainly for tension, and only when the furnace is inclined - for bending. Therefore, it is possible to use relatively long graphitized electrodes of large cross-section allowing significant operating currents. Arc furnaces can be very powerful and productive, and work on three-phase current. In addition, in a special part, calculations were made of the design and geometric dimensions of DSP100, the material and thermal balances of smelting steel of reduced hardenability 62p110, and the calculation of the necessary power of the furnace transformer.

Due to the technological advantages in furnaces of this type, almost all highly alloyed steels and many structural steels are smelted in the form of ingots. In addition, a significant part of steel shaped casting is performed in them. The electric furnace is better suited for processing scrap metal, and the entire furnace volume can be occupied with solid charge, and this does not impede the melting process. Metallized pellets replacing scrap metal can be loaded continuously into an electric furnace using automatic metering devices.

In the DSP100 Project with complex off-furnace processing of steel, the most detailed issues related to the production technology of steel smelting in DSP100, the technology of off-furnace processing of steel in the complex steel processing unit (ACOS) or easier - the metallurgical unit is ladled, issues on the organization of production and maintenance personnel in the electric steel smelting shop. Technical and economic indicators of operation of electric steel smelter and DSP100 with subsequent complex off-furnace processing of steel. Measures to improve the quality of steel. Organization of control over compliance with production technology and safety, fire and electrical safety. Issues related to occupational and environmental protection in the electric smelting industry.

In addition, the corresponding calculations in the economic part of the diploma project proved the production and economic efficiency of the DSP100 Project with complex off-furnace processing of steel.

Three drawings and a cost-effectiveness poster of the proposed project are presented in the graphic part of the DSP100 Project with complex off-furnace processing of steel. Figure three shows the proposed layout of the electric steel smelter. The first figure shows a general view of the proposed DSP100, and the second figure shows a longitudinal section of the spherical bath DSP100 with the designation of the main components of the refractory lining of an arc electric steel smelting furnace.

General part

1.1. General description of arc electric smelting furnaces

Arc furnace consists of working space (furnace itself) with electrodes and current leads and mechanisms ensuring furnace inclination, retention and movement of electrodes and charge loading.

Steel is melted in working space limited from above by domed arch, from below by spherical hearth and from sides by walls. Refractory masonry of hearth and walls is enclosed in metal casing. Removable vault is assembled from refractory bricks resting on support ring. Through three holes symmetrically located in the arch, current-conducting electrodes are introduced into the working space, which can move up and down using special mechanisms. The furnace is powered by three-phase current.

Charge materials are loaded on the furnaces, after they are melted, a layer of metal and slag is formed in the furnace. Melting and heating is carried out due to heat of electric arcs occurring between electrodes and liquid metal or metal charge.

Ready steel and slag are discharged through steel outlet and trough by inclination of working space. The operating window closed by the shutter is designed to monitor the progress of melting, repair of the hearth and loading of materials. [21]

1.2. Lining of arc electric smelting furnaces

Refractory materials are used to create working space of arc furnaces including bottom, walls and vault. The service life of the refractory lining has a significant impact on the capacity of the furnace, the quality of the molten metal and its cost. Frequent lining repairs increase the downtime of the furnace, worsen the rhythmicity of the unit, reduce labor productivity, and increase the consumption of electricity and materials.

During melting, refractory materials are exposed to:

high temperatures (more than 1800 ° C);

heavy mechanical loads;

abrupt temperature changes;

aggressive slags and many other destructive effects.

To withstand these factors, materials must have sufficient refractoriness, low thermal conductivity, and minimal electrical conductivity.

Refractory materials used for furnace lining

All refractory products and plastic masses according to their properties must comply with certain standards and technical requirements fixed in GOST and TU. It is accepted that the refractoriness of the material is determined by the temperature at which the standard sample begins to deform under the influence of its own gravity.

Refractory materials in electric furnace masonry experience significant loads under high temperature conditions and can soften at a temperature lower than that which characterizes their refractoriness. Therefore, it is very important to know the softening start temperature under a load of 2 N/cm2.

Refractory articles must have sufficient compressive or crushing resistance, i.e., the required mechanical strength under heating conditions. The steel furnace lining undergoes frequent temperature changes (the so-called temperature differences): during filling and loading with a charge, the lining is cooled to very low temperatures, and during the melting period it experiences rapid heating. To ensure sufficient resistance of the furnace lining, the refractory material must have increased heat resistance, that is, good resistance, in other words, work without cracking and breaking under conditions of sharp temperature fluctuations.

The property of refractory material at high temperatures to resist destruction from the effects of slags and metal is called chemical resistance or slag resistance. In the lining of a furnace with sufficient slag resistance, as a result of chemical action with metal and slag, a large number of low-melting oxide compounds are not formed, it is well opposed to the destructive effect of metal and slag.

The electrical conductivity and thermal conductivity of refractory materials usually increase with increasing temperature. Lower thermal conductivity and electrical conductivity of the furnace lining ensure a reduction in thermal losses and specific energy consumption. The length of service of the lining also depends on the amount of change in the volume of refractory materials as a result of heating and cooling, reflecting additional shrinkage or expansion (growth) of the refractory. Therefore, when manufacturing the lining, it is necessary to take into account this property of the material to change its volume with an increase or decrease in temperature and during operation as a whole. Expansion of the lining can result in crushing of the masonry elements, its expansion and destruction of the furnace casing, and shrinkage - to the loss of construction strength of the lining.

According to the chemical composition, refractory materials are divided into basic, neutral and acidic. Magnesite, chamotte, magnesitochromite, periclasoppinelid, dolomite, dinas were the most used for lining electric steelmaking furnaces. Asbestos, diatomite, lightweight brick are used as heat-insulating materials. The binding materials are coal resins, pitch and liquid glass. Technical characteristics, chemical composition, properties and dimensions of refractory products, as well as refractory masses, powders and concretes are given in the corresponding GOST and TU.

Improving the resistance of arc furnace lining

The lining of the arc furnace in operation is worn out unevenly, so that individual sections of it are repaired at certain intervals.

The following measures help to increase the resistance of the lining of arc electric smelting furnaces:

improved quality of used refractory materials;

improvement of lining manufacturing methods;

setting the optimum size of the melting space;

reduction of melting duration due to increase of specific power of transformers and improvement of technology;

heating of metal charge;

use of oxygen.

With careful care of the lining, it is possible to increase the working time of the melting unit. The most responsible part of the lining of the arc furnace is the hearth, since it directly contacts with liquid metal and slag and in case of its malfunction, "melting off" is possible.

The condition of the hearth is evaluated after the release of each smelting. The surface of the bottom should always be smooth, without growths, mounds and pits. Irregularities are eliminated, for which purpose, systematically, after release of each melting, the hearth is filled with refractory welding materials.

To reduce the cleaning period of the furnace, it is necessary that the slag before discharge is liquid-moving, it is drained with metal from the furnace without residue. If only metal is discharged into the furnace and the ladle, the bottom shall be inspected, cleaned and filled after a series of melts. The slope at the drain hole is kept gentle to ensure complete removal of liquid metal and slag into the ladle.

The slope at the working window should be smooth, have a slope of 4560 ° towards the bottom so that it can be quickly cleaned of slag and metal residues. After cleaning the bottom, the damaged spots on the bottom and slopes are boiled, as a rule, with dry or humidified liquid glass, fine-grained magnesite powder (alone or mixed with dolomite).

Filling of lining with layers of magnesite and magnesitodolomite mixture is carried out quickly, which is necessary for rational use of high temperature of working space of furnace for better sintering of grains of refractory materials between each other and with lining.

For throwing powders or humidified masses onto the lining of the hearth, slopes, front wall and nearby sections, throw filling machines of tape type and machines of other structures are used. High quality filling of slag zone and lining walls is provided by hot torcretation.

To prevent destruction of filled zones during charge loading, thick layers of welding are covered with fine lime and sheet iron.

After loading a portion of the charge onto damaged sections of the furnace slopes, the magnesite and liquid glass basket is discharged from the trays using scrap pieces to hold the mass on the lining.

When smelting high-chromium steel using oxygen, the furnace bath is overgrown with slag and refractory materials. This phenomenon is undesirable, since it leads to a decrease in the mass of melting and to work on false (welded) thresholds.

In order to eliminate lining overgrowth, the grade of steel grades to be melted is changed, in addition, the hearth, furnace slopes are carefully cleaned and quartz sand is periodically thrown onto them.

In order to prevent accidental removal of liquid metal through the lining of the hearth and slopes of the furnace, it is necessary to:

clean and refill damaged lining areas with high-quality refractory materials;

prevent overgrowth of the bottom and the formation of false thresholds;

use picking and restoration of the bottom and slopes during the current cold repairs of the lining;

prevent long-term operation on thick magnesia and acidic silica slags;

exclude cases of local overheating and violation of electric and thermal modes of melting.

The stability of the walls and vault of the main arc furnace is significantly lower than the resistance of the hearth and depends on factors such as:

electric mode of melting;

the residence time of the liquid metal in the furnace;

composition, viscosity and reflectance of slag;

thermal mode of melting;

quality of repair works and used refractory materials, etc.

The wear of the walls and vault increases significantly if smelting is carried out on open powerful long arcs and the metal is heated in the last refinement period. It should be borne in mind that the furnace lining is sufficiently heated by the time the smelting is discharged and reaches the softening temperature of the refractories.

Smelts with a shorter exposure of liquid metal in the furnace under foam slags (after coke addition) are favorable with respect to the effect on increasing the stability of the walls and arch. Increasing the basicity of the slag by increasing the calcium oxide content and reducing the concentration of iron oxides also has a positive effect on the stability of the walls and vault.

Destruction of the slant lining at the slag belt level deprives the support of the wall masonry located above the section and causes its showering.

The construction of the slag zone of slopes from high-density magnesite brick on a spinelide bundle improves the resistance of the lining to blurring with slags and increases the durability of wall masonry. Wall endurance is enhanced by:

reduction of melting time;

installing electrodes at an angle of 48 ° to the center of the furnace in order to increase the distance between the arcs and the lining;

equalization of power by phases.

Partial replacement of the brickwork of the walls of high-power furnaces with metal panels (caissons) with water or steam evaporation cooling leads to a decrease in the consumption of refractories, an increase in labor productivity during repairs and an increase in the duration of the working campaign of lining the walls of the furnace between repairs.

Water-cooled panels for installation in walls of super-powerful arc furnaces are made with forced water circulation system, for which seamless pipes with diameter 60-90 mm with wall thickness up to 16 mm are used, gap between pipes is 2-5 mm. The advantage of thin panels having different shapes depending on the operating conditions is the absence of welds. The panels ensure normal operation at specific heat flow up to 250 kWh/m2. Surface of panel facing working space of furnace is covered with special refractory material preventing panel from critical heat flow.

The main reason for the destruction of magnesitochromite arches is the absorption by the working surface of the arch of iron oxides.

Penetrating the refractory masonry, iron oxides change its composition and volume, causing chipping of bricks. As a rule, the central part of the magnesitochromite vault wears out much faster than the peripheral areas (1.3 and 0.3-0.4 mm per melting, respectively).

To increase the stability of the vault, the central part and areas subject to faster wear are laid out of bricks of greater length. Increasing the resistance of the roof lining can be achieved if:

ensure high quality masonry and use high-quality refractory products and masses;

prevent overheating of the lining due to long-term operation with an open mirror of liquid metal and liquid moving slags;

clean the outer surface of the arch from dust;

carefully inspect the inner (working) surface of the vault before turning on the furnace for melting;

practice partial repairs of worn-out areas of the vault masonry on the template;

the operation of the furnace after installing a new vault should be started with smelting of steels of less labor-intensive grades;

prevent operation on faulty electrode seals and without them.

Significant increase in the stability of the arches is achieved by replacing the peripheral part of the refractory lining with metal structures with water or steam evaporation cooling.

In addition to increasing the resistance of the furnace lining, measures should be taken to reduce the duration of hot (without disassembling the furnace), cold (replacing part of the lining) and capital (replacing the lining and part of the equipment) repairs. [23]

1.3. Charge materials for arc electric steelmaking furnaces

The main component of the charge (75100%) of electric smelting is steel scrap. Scrap shall not contain non-ferrous metals and shall have a minimum amount of nickel and copper; preferably, the phosphorus content of the scrap does not exceed 0.05%. With a higher phosphorus content, the melting time increases. Scrap should not be highly oxidized (rusty). With rust (iron oxide hydrate), a lot of hydrogen is introduced into the metal. Scrap must be heavy-weight so that the charge is loaded in one take (one badge). With lightweight scrap, after partially melting the first portion of the charge, it is necessary to reopen the furnace and plant the charge, which increases the melting time. [28]

Recently, the use of metallized pellets and sponge iron, products of direct reduction of enriched iron ores, has been expanding. They contain 8593% Fe, the main impurities are iron oxides, SiO2 and Al2O3. A distinctive feature of this raw material is the presence of carbon from 0.20.5 to 2% and a very low content of sulfur, phosphorus, nickel, copper and other impurities usually found in steel scrap. This makes it possible to melt steel, which is distinguished by increased purity from impurities. Remelting the waste of alloyed steels saves expensive ferroalloys. These wastes are sorted by chemical composition and used in smelting steels containing the same alloying elements as wastes. [29]

To increase the carbon content in the charge, cast iron, coke and electrode scrap are used. The main requirement for cast iron is the minimum content of phosphorus, therefore, in order not to add a lot of phosphorus to the charge of small (< 40 tons) furnaces no more than 10% of cast iron, and in heavy trucks no more than 25%. [21]

Lime, limestone, melting spar, bauxite, chamotte battle are used as slag-forming in the main furnaces; in acidic furnaces - quartz sand, chamotte battle, lime. Iron ore, rolling scale, agglomerate, iron pellets and oxygen gas are used as oxidizing agents. Slag-forming and oxidizing agents are subject to the same requirements as in other steelmaking processes: lime must not contain more than 90% CaO, less than 2% SiO2, less than 0.1% S and be freshly equipped so as not to introduce hydrogen into the metal. Iron ore should contain less than 8% SiO2 because it reduces the basicity of slag, less than 0.05% S and less than 0.2% P; it is desirable to use an ore having a size of 4,0100 mm, since such pieces easily pass through the slag layer and react directly with the metal. In smelting spar used for slag liquefaction the content of CaF2 shall exceed 85%. [28]

In the electric steel smelting industry, almost all known ferroalloys and alloying elements are used for doping and deoxidation.

1.4. Metal electromagnetic mixing device

To average the chemical composition of the liquid bath, equalize temperature, accelerate exchange reactions between metal and slag and download slag, a metal electromagnetic mixing device is used. It consists of a stator located under the non-magnetic bottom of the furnace, resembling a segment of the stator of a two-phase asynchronous motor, and a two-phase low-frequency generator (0.52 Hz) powered by two-phase alternating current shifted in phase by 90 °.

This creates a traveling magnetic field that penetrates the molten metal bath. Interaction of currents occurring in bath with travelling magnetic field causes movement of lower layers of metal along hearth of furnace in direction of field movement - from working window to outlet hole, and upper layers in reverse direction.

When the coil poles are switched, the direction of metal movement changes. For 100 ton arc furnaces, the power of the two-phase stator is 520 kV∙A, voltage 130 V, current 2000 A, cos 0.6, frequency 0.55 Hz. In furnaces with higher transformer capacity, after the introduction of out-of-furnace metal treatment, electromagnetic mixing of the bath is not used in ladles. [32]

1.5. Advantages and disadvantages of electric arc furnaces

Advantages of steel melting in arc furnaces

1) carbon, alloyed and highly alloyed steels and alloys, iron, non-ferrous metal alloys, more than 100 types and grades of metal are smelted in arc steelmaking furnaces; [32]

2) improved production efficiency due to reduced consumption of scrap and alloying elements; [30]

3) the use of electric energy as an alternative type of energy to modern obsolete fuels such as coal, oil, gas; [1]

4) flexible technology of steel smelting, due to the use of a wide range of technical and technological methods of smelting (such as, for example, argon metal treatment, synthetic slag smelting, the possibility of using a single slag process, blowing steel with powdered materials); [32]

5) possibility of metal heating to high temperatures (~ 1800 ° C); [21]

6) high level of automation and use of computers for program control of smelting; [28]

7) possibility of design of CPD guaranteed to ensure environmental safety in conditions of continuous tightening of requirements to environmental protection of metallurgical production; [1,6]

8) rapid adaptation to changing market conditions, due to flexible technology and a large range of smelting steels; [33]

9) high price competitiveness of smelted carbon, high-quality and high-alloy steel, due to the high productivity of arc electric steelmaking furnaces, extremely low content of harmful impurities and non-metallic inclusions; [31]

10) minimum cost of liquid intermediate product due to minimum consumption of scrap and alloying additives for carbon monoxide and various types of metal loss; [32]

11) the capital cost of the CPD installation is much cheaper than the installation of similar metallurgical units, for example, the CPD installation is on average 40% cheaper than the installation of open-hearth furnaces of equal productivity. [33]

Disadvantages of steel melting in arc furnaces

1) initially high requirements for charge materials, if the steel production process does not provide for a refining period of steel directly in an electric arc furnace and the use of out-of-furnace steel processing (i.e., an additional steel processing operation in a steel casting ladle);

2) high local overheating under the electrodes; [18]

3) difficulty of mixing and averaging the chemical composition; [21]

4) a significant amount of combustion products and noise during operation;

5) increased complexity of design and process equipment (relative to other furnace units for steel production, such as an oxygen converter or an open-hearth furnace); [32]

6) the need for highly qualified technological personnel.

Organization of metallurgical production

Organization of production, this is the most important task of absolutely any organization or enterprise. How production is organized from the very beginning ultimately depends on its economic and production efficiency.

Modern steel production with steel production in arc furnaces, it is best to organize in several separate and consecutive technological directions:

The first direction is the melting of charge materials, for the Chusovsky Metallurgical Plant, the optimal will be the use of an electric arc furnace with a capacity of 100 tons.

The second production direction is the complex out-of-furnace treatment of steel in a ladle-furnace unit. At this stage, it is most optimal to deoxidize and refine the metal.

The third direction of production, phased and post-operational control over compliance with all technical and technological measures by the production personnel of the electric steel shop, which originates from checking the quantity and chemical composition of charge materials and ultimately ends with quality control of finished products.

Organization of complex off-furnace steel processing technology

In modern ladle-furnace metallurgy, this is an aggregate that most rationally provides the ability to flexibly control the process of forming the physicochemical state of the melt to achieve the goal - to obtain high-quality steel with a given chemical composition and properties. It is for these reasons that, after melting steel in an arc furnace, it is recommended to supplement the technological process with such a modern unit as a ladle furnace. [18]

Ladle furnace unit

The main purpose of the steel processing process in a ladle furnace is to carry out a number of technological operations faster and more efficiently than in conventional steelmaking units. The "Kovshpech" unit (AKP) is designed to bring the smelting to the standard state in terms of chemical composition, temperature and cleaning of steel from gases and non-metallic inclusions.

The ladle furnace plant also serves as a kind of shock absorber between the metal smelting and casting process with high accuracy in terms of temperature requirements and tolerances for the chemical composition. In a ladle furnace, you can reheat the metal, set the desired temperature and control the properties of the metal. It is also possible to specify the exact parameters of the final chemical composition of steel at a minimum cost for its production.

The ladle furnace operates with a high power factor and with long arcs immersed in slag, which provide efficient power input.

During this process, the liquid metal is mixed with an inert gas, which is supplied through porous plugs located in the bottom of the ladle. Inert gas also serves to protect the surface of the metal from atmospheric air, which can flow during the steel treatment through loosely closed slots in the hearth of the ladle furnace. [28]

The "Furnace - Ladle" plants are designed for the treatment of liquid steel in a steel casting ladle both using metal finishing plants (UDM) and a slag download machine (MSW), and without them. The ladle furnace unit allows the following operations:

reducing the sulphur content of steel to the required level ;

production of steel with content of alloying elements within specified narrow limits ;

performing metal release for casting in a given temperature range;

treatment of steel with active elements (calcium, titanium, boron, etc.) with maximum and stable absorption ;

change due to microlegination of morphology and number of non-metallic inclusions;

in the case of operation with MNLF, the ladle furnace unit is a buffer tank that allows you to supply metal - strictly in the necessary time during serial casting of steel;

in case of metal release with excess chemical composition due to harmful impurities due to dilution of other smelting with pure metal, exclude metal scrap due to chemical composition ;

In case of MNLF emergency shutdown, eliminate metal losses by heating it to start MNLF.

one of the main conditions for performing metal refining on a ladle furnace is cutting off oxidized furnace slag (or its removal) at the outlet from the melting unit and aiming refining slag. [18]

Peculiarities of steel out-of-furnace processing processes

Increasing the capacity of CPD and the specific power of transformers makes refining processes, especially with a recovery period, irrational. Significant effect in improvement of TEP with simultaneous improvement of steel quality is provided by out-of-furnace treatment of liquid steel using vacuum, oxygen and inert gases, metal powders, alloys and compounds, synthetic slag.

A feature of metal refining outside the furnace is the use of the most favorable physical and physicochemical conditions for the removal of impurities from the metal and the production of steel of the necessary composition. Compared to CPD, conditions for off-peak refining are characterized by:

increased speed of metal interaction with slag or gas phase due to significant increase of contact surface between these phases, as well as due to mixing, which promotes crushing of steel into small volumes with large surface.

improved thermodynamic conditions for removal of impurities as a result of changing the composition of the gas phase or creating a vacuum, treatment with slag with optimal physicochemical properties.

Out-of-furnace refining methods solve the following problems:

Decarburization of the metal to very low carbon concentrations (< 0.010%) is achieved by vacuum treatment, oxygen blowing together with inert gases.

Deep refining of the metal from sulfur (≤0,003%) is achieved by treatment with slag or the introduction of desulfurizing additives into the metal.

Deoxidation to obtain steel with little contamination with non-metallic inclusions of controlled shape and size is achieved by vacuumizing or treating with powder of metals and other materials.

Removal of hydrogen from the metal (≤ 2⋅104%) by vacuumization.

Production of metal of required composition with control of content of deoxidizers and alloying elements within narrow limits, as well as with reduction of their carbon monoxide - evacuation, introduction of deoxidizers and alloying slag or gas phases in contact with metal at low oxidation potential.

Equalization of metal composition and temperature in ladle volume, temperature adjustment by blowing with inert gas, additional heating in ladle. [18]

Structural features of ladle-furnace units

During the creation and implementation of separate methods and units of out-of-furnace processing, the feasibility of their combined (integrated) use and the need to compensate for thermal losses when using them to ensure the reliability of the technology has become clear. In this regard, the out-of-furnace refining of the metal in the complex steel treatment unit (ACOS), which is a combination of a metal treatment unit in a ladle with a vacuum and a device for heating the melt in the ladle with electric arcs to the required temperature, and allowing the metal to be treated with refining slags, inert gas, powder mixtures and wire with various filler compositions, has been intensively developed. These devices can be combined in a single unit or placed on separate stands equipped with vehicles for transferring a ladle, for example, from a vacuumizing bench to a heating bench and vice versa. If necessary, ACOS shall be equipped with a device for removal of oxidizing slag from the ladle after smelting. [25]

The efficiency of the ladle-furnace unit depends to a large extent on the availability and reliability of process devices, the main of which are:

argon stand;

device for injection of powder of carbonaceous materials into metal (supercharger);

system of silos, weighing and supply of slag-forming and alloying materials to steel-casting ladle;

tribe apparatus;

device for upper blowing of steel with aron;

device for temperature measurement and sampling (thermoprobe);

slag download machine. [11]

Organization of process control

Along with replacement production personnel (craftsmen, foremen and others) in the electric smelting shop of any enterprise, control over the implementation of technological instructions for smelting, off-furnace processing and casting of steel is carried out by employees of the technical control department (TOC). Strict compliance with the established technology is a mandatory requirement of the OTC for craftsmen, steelworkers, bottlers, operators and other workers of the workshop.

Production personnel should know that non-compliance with the process instruction leads either to a decrease in metal quality or to the occurrence of scrap, deterioration of technical and economic indicators of production and non-fulfillment of consumer orders.

The quality of the finished metal products is largely determined at the stage of steelmaking. Therefore, at metallurgical enterprises there is not only a system for monitoring the compliance of the quality of products with the requirements of the relevant standards and technical conditions, but also a constant check of the execution of individual operations and modes of the current technological process in the electric steel shop.

At the same time, the duties of CTC employees include the functions of preventing violations of technology and possible marriage. OTC controllers in the charge span of the workshop check the quality and quantity of scrap, cast iron and alloying components set in the loading badge, as well as lime, iron ore (agglomerate), chamotte battle or quartzite, coke and other carburizers. In the furnace span, the recording of suspended materials in the operating map, the order, amount and time of additive in the furnace or ladle of slag-forming (lime, melting spar, chamotte, etc.), oxidizers, carburizers, oxygen gas, deoxidizers and alloying ferroalloys are controlled. In the process of smelting, dryness of used materials, puncturing of alloying materials, time of metal and slag sampling, compliance of their chemical composition and degree of bath heating with requirements of technological instructions are controlled.

The duration of the oxidation and refinement periods, the quality of the slag download, the careful treatment of the outlet hole and the drainage of metal into the steelmaking ladle are subject to control.

During out-of-furnace treatment of melt, sequence of process operations, their duration, flow rate of gas and materials, metal temperature before and after treatment, as well as residual pressure, mass of metal portions and number of cycles during evacuation are controlled.

Before starting casting, check:

quality of lining of steelmaking and intermediate ladles;

composition and dryness of slag heat-insulating mixtures;

quality of molds, center and add-ons and their dryness;

horizontal installation of pallets;

quality of molds and center molds and their stability on the pallet;

coincidence of mould cup with hole in siphon brick and purity of gate channels and molds.

The envisaged holding of metal in the ladle before casting and the time of casting start are monitored and marked in the operating map.

The chemical composition of steel is determined by two bucket samples taken in the middle of casting from a jet of metal, well heated with a steel spoon into cast-iron cups - molds (probes).

All deviations (violations) from the current technology are taken into account, recorded in a special log with the indication of the guilty persons and the causes of the violation, and considered by the shop management with production teams and shifts with a specific definition of measures to eliminate deviations and prevent such violations in further work. [25]

3.4. Organization of production personnel

The Chusovskaya Metallurgical Plant consists of departments of management, production workshops, departments, sites, brigades, laboratories operating on the basis of internal economic calculation. The plant operates on the principles of economic calculation and self-financing. The production, social activity of the plant and remuneration are carried out at the expense of the funds earned by the labor collective. The plant reimburses its material costs from the proceeds from the sale of products and ensures the improvement of the technological process. Profit, or income, is a generalizing indicator of the economic activity of the plant.

The electric steel smelting shop ensures the production of steel of the specified grade grade and the required quality and is the main one at the metallurgical enterprise.

The head of a large workshop has deputies for production, technology and equipment. In small workshops or areas of the workshop, control over the operation of the equipment is carried out by the mechanic and electrician of the workshop, subordinate directly to the head of the site or workshop. The head of the workshop is subordinate to the heads or heads of the charge preparation departments, steel smelting, off-furnace processing and casting, to which, in turn, replacement masters are subordinate. The shop manager for each given shift is the shift supervisor, reporting to the shop manager and his deputies.

The leading role in the production is performed by replacement craftsmen who directly direct the work of brigades serving one or more metallurgical units in their shift.

Depending on the nature of production processes, the conditions for their implementation apply two forms of labor organization:

individual (such a form of organization of labor in which one worker performs the production process from start to finish, for example, a set of stops and gates);

brigade (a form of organization of labor in which a group of workers with different qualifications performs the production process; each member of the brigade performs certain production and technical operations assigned to him, and the foreman leads the whole work).

At metallurgical enterprises, a brigade form of work prevails: for example, an electric furnace is served by a team of steelworkers, an installation of continuous casting of steel - a team of spillers, and so on.

The main task of the correct organization of labor is to develop the maximum number of high-quality products with the lowest cost of labor and funds. Production teams achieve high productivity by continuously improving the methods of performing individual technological operations and reducing their duration. The right organization of labor also provides for the timely provision of the necessary materials and tools to workplaces.

Each electric furnace is served by a brigade consisting of a foreman (steelworker) and his henchmen. The duties of the brigadier include instructing and supervising brigade members. The foreman (steelworker) reports to the replacement foreman, is responsible to him for completing the task, directs the work of the brigade members and performs the entire amount of his own work.

High-performance work of the steelmaker team at the furnace is possible subject to the following conditions:

rational placement of tools, additional, filling and fluxing materials, as well as auxiliary equipment (scales, hoses, throwing machine, fuel-oxygen lance, etc.);

absence of tools and materials already used on the work site;

availability of modern tools for measuring, monitoring and controlling the steel smelting process;

serviceability and serviceability of loading and filling machines and mechanisms ;

sufficient equipment of the workplace with means of protection against increased heat radiation and industrial noise;

availability of process instructions on smelting at workplaces and rules of equipment operation;

maintaining the necessary sanitary and hygienic conditions and cleanliness at workplaces;

execution of procedures for reception and delivery of workplaces at the beginning and end of the shift .

Before taking a shift, the steelworker team receives a shift task from the foreman or at an operational meeting from the shift supervisor. Reception of the shift by the foreman (steelworker) and his henchmen means that the team receiving the work post evaluates:

condition of the electric furnace (mechanical and electrical equipment, lining and other mechanisms);

serviceability of cooling devices;

compliance with smelting technology;

the availability of tools and materials;

serviceability of instrumentation;

serviceability of ventilation systems, gas cleaning and other equipment.

For the successful introduction of mechanization and automation of control and control of the process in the electric steelmaking industry, a high level of qualification of all members of the team and, first of all, the steelmaker is required. The main task of the electric steel shop team is to fulfill and exceed the production plan, produce products of a given grade, ensure the required quality of metal and reduce the cost of ingots.

Such a task is successfully solved when organizing labor and production in an electric steel shop according to the most effective system - the so-called regulated regime, that is, according to the schedule.

Work on the schedule provides for the execution of production operations in sequence and in time, ensuring strict fulfillment of the established task on the volume (plan), grade and quality of products. Operation of the workshop according to the schedule means creation of conditions that ensure high performance during the process and its quick adjustment after elimination of violations of the specified mode.

The basis of shop planning is the smelting release schedule. Having a task from the production department of the plant for a week, the deputy head of the production workshop draws up a daily schedule for the production of smelts for each furnace with indication of steel grades, process instructions for smelting, casting and assignment of rolled metal according to standards and specifications, as well as a repair schedule indicating their nature and duration.

The schedule provides for:

regulation of shop areas (feed of charge, fluxes, deoxidizers);

preparation of out-of-furnace treatment units;

supply of casting buckets and compositions;

preparation of continuous steel casting units, etc.;

uniform loading of workshop equipment during the day.

According to the schedule, the possibility of simultaneous release of several melts is excluded, downtime of furnaces is not allowed due to the absence of bridge cranes. The workshop daily schedule reflects the activities of all sections of the workshop, from charge to casting and thermal compartments. The following are taken into account:

existing standards for the duration of the entire smelting and its individual periods;

Actual start time of the last operation (by the time of scheduling)

specified steel grades in accordance with orders of metal products consumers;

state of furnace lining;

shutdown of units for repair and its duration according to standards;

requirement of uniform distribution of smelting outlets during the day;

composition of charges for individual grades taking into account the norms of specific consumption of ferroalloys and deoxidizers;

availability of stock of charge, refractories, fluxing and other materials in the workshop and their receipt.

In accordance with the daily schedule, the shop manager, his deputy or the duty administrator together with the shift dispatcher make up an operational shift task, based on the actual start time of the last operation (by the time the task is compiled), as well as the state of the furnace linings. In accordance with the shift assignment, the shift supervisor at a short operational meeting before work introduces the masters, foremen and workers of all sections with the work program for the shift.

Tasks for the crews serving the furnace are written out on special boards near the furnace, and for charge compartments, off-furnace processing and casting - on forms.

In addition to the shift supervisor and foremen, control over the execution of operational schedules is carried out by a shift dispatcher, whose duties include:

Recording the actual time of operations in the log

checking the timeliness of execution of the operational schedule and tasks;

information of the shift supervisor on the progress of the schedule and transfer of orders to the production areas;

Timely information of masters of different sections on planned changes in the time of individual shift schedule operations;

Monitoring of ingress and withdrawal of pouring compositions;

control of material unloading;

control over readiness of continuous steel casting units for metal acceptance;

performance of other works.

A clear division of duties among the members of the production teams, high responsibility of the personnel for the quality and timeliness of technological operations, labor and technological discipline are those mandatory conditions that determine the successful implementation of smelting, smelting according to the schedule, without violating the technological instructions and high metal quality indicators.

Economics of production

4.1. Technical and economic indicators of electric steelmaking shop operation

Modern electric steelmaking production is characterized by the creation and introduction into practice of single automated technological modules, including super-powerful arc furnaces, complex off-furnace steel processing units (ACOS) and SNRS.

Domestic arc furnaces of the new generation correspond to the world technical level in terms of equipment quality, productivity, degree of automation of the technological process and indicators of environmental protection against harmful emissions.

The process of steel smelting in these furnaces is organized in such a way that refining operations are taken out of the smelting unit into a steel-smelting ladle, that is, electric steel-smelting shops are equipped with modern means for refining and refining metal outside the furnace.

The high-performance module - a super-powerful arc furnace, ACOS and SNRS - provides almost three times the productivity of 100 ton CPD and high stability of metal quality from smelting to smelting.

At the same time, the furnace is used for intensive melting of the charge and oxidation of impurities, and ACOS - for refining the metal from sulfur, oxygen and non-metallic inclusions, as well as for alloying and heating the melt to casting temperatures at the ECU.

The application of the module changed the requirements for metal charge. While in traditional technology heavy steel scrap has produced some technological advantages, for a high-performance furnace, scrap with a density in the range of 0.60.8 t/m3 is optimal, provided that the maximum size of the scrap fractions is not more than 500 mm. At the same time, the use of scrap heating by gases leaving the arc furnace and the use of gas-oxygen wall burners with a capacity of 3-6 MW leads to a significant reduction in the melting time of the charge. Improvements in the performance of electric steel shops in the consumption of raw materials, materials and energy savings are achieved by partial addition of alloying materials to the ladle at off-furnace steel processing plants. Increasing the consumption of carburezers from 5-7 to 1517 kg/t reduces the consumption of cast iron in the charge and reduces metal carbon monoxide.

Increase of oxygen consumption during melting period from 2 - 3 to 15 - 20 m3/t provides saving of electric power by 35 - 40 kWh/t and reduction of melting duration by 3 - 7%.

Plant-wide overheads include:

Wages and accruals to factory management employees;

lifting when workers move from the enterprise;

travel expenses;

office and postal and telegraph expenses;

passenger transport content;

maintenance and amortization of buildings, offices and plant management equipment;

maintenance of buildings, structures and general-purpose equipment, factory warehouses, general-purpose laboratories, etc.;

costs of rationalization and invention; "various mandatory deductions, taxes and charges;

ongoing repairs;

costs of testing and research;

expenses for special types of enterprise security;

labour protection and improvement costs;

Production training and practice costs for school and student students;

Other costs.

Non-production (commercial) expenses include:

contributions to the financing of research and development;

Costs of maintenance of off-plant base warehouses and transshipment points;

contributions to subsidiary farms;

the cost of loading and transportation of metal products to the place of sale.

The reduction of overhead costs and unit costs is achieved by:

reduction of non-productive costs (fines for overprotection of wagons, penalties and penalties under contracts, lack of materials);

minimizing administrative and management costs (by reducing travel, management staff, office supplies and other costs);

Reduced costs of loading and unloading operations through mechanization and robotization, as well as through more efficient use of all modes of transport for the transport of materials (road and water transport, wide use of containers).

The costs of redistribution in the electric smelting shop largely depend on the duration of smelting and the productivity of smelting units, the power of furnace transformers. Intensification of the process and out-of-furnace metal treatment have a positive effect on reducing the cost of redistribution and the cost of steel.

An effective measure in reducing the cost is the transition of electric steel shops and individual sites to the economic settlement and organization of small enterprises. At the same time, the personal material interest of the workers of the workshop and individual sites in the economical expenditure of funds and materials is increased.

Justification of production need for project implementation

Today, steel production at OJSC Chusovskaya Metallurgical Plant is represented by converters and open-hearth furnaces.

Currently, Russia confidently ranks eighth in the world in the number of smelted steel in arc electric furnace, its production volume exceeds 23%, while global steel production has already overcome the mark of 30%. According to the Strategy for the Development of the Metallurgical Industry of Russia, by 2020 the share of steel smelted by the electric arc method can reach the global average and reach - 40%.

Open-hearth furnaces themselves are technically and even morally obsolete metallurgical units. According to the Ministry of Industry and Trade of the Russian Federation in 2012, open-hearth production is still carried out at five Russian plants on this list and the Chusovskaya Metallurgical Plant with its two open-hearth furnaces. It is no secret that the technology of steel production in open-hearth furnaces is inferior to modern electric smelting units in absolutely all technical and economic indicators. The quality of open-hearth steel is not amenable to any comparison with the quality of electric steel.

One of the main conditions for obtaining high stable results of steelmaking is strict compliance with the main rule of industry - "in keeping with time." The electric arc furnace with a complex out-of-furnace treatment of steel today is and will remain for a long time precisely the technological and technical achievement of the industry, which makes it possible to make such a problematic branch of the economy as ferrous metallurgy - economically and productively efficient. Thanks to a number of undeniable advantages and disadvantages that do not play a special role, which in turn will serve only the purpose of further development and improvement of arc electric steel furnaces.

To date, it will be rational for the Chusovsky Metallurgical Plant to switch to the production of electric steel, thereby finally stopping the open-hearth production of steel, which in turn will entail the possibility of a significant increase in the productivity of the steelmaking workshop by more than 450 thousand tons per year. In addition, the problem of steel quality is no longer a problem, since electric steel with complex off-furnace processing of steel is no doubt today and will remain the highest quality steel for a long time. The consumption of alloying elements and the yield of suitable metal in arc electric furnaces significantly exceeds the values ​ ​ of open-hearth furnaces. Finally, with the proper organization of electric steelmaking production, environmental pollution rates are sharply reduced, which also does not lend itself to any comparison with pollution of the environment by open-hearth furnaces. Perhaps the only and very significant drawback of electrometallurgy is the cost of electricity, which today remains very high. But this shortcoming will become insignificant over time, because the electric power industry also does not stand still and every year it is developing more rapidly and more rapidly. About every 2-3 years, new nuclear power plants are built in the world, almost every year there are new alternative power plants that accumulate energy from sunlight, wind and air. Thus, electricity is becoming more affordable and therefore electrometallurgy can calmly develop now.

The implementation of the DSP100 Project with complex off-furnace processing of steel will make it possible to modernize the steelmaking production of the Chusovsky Metallurgical Plant and bring the plant to a fundamentally new level of technical equipment.

Conclusion

Modern technological schemes involving the smelting of steel in arc electric steel smelting furnaces using a complex out-of-furnace treatment of steel at a ladle-furnace unit and the subsequent transfer of liquid steel to intermediate devices, and then to continuous steel casting plants, significantly increase the productivity of steel smelters and metallurgical enterprises as a whole. They recoup their costs by reducing the consumption of material resources, improving the quality of metal products produced and making it possible to achieve high economic results, which in principle can be possible at enterprises in the metallurgical industry.

The implementation of the DSP100 Project with complex off-furnace processing of steel is only the initial part of the modernization of the enterprise according to the above-described modern and advanced technological scheme, which in turn should certainly develop into a complete modernization of the technology and technological equipment of such a truly significant production for OJSC PMZ, such as steel production. Which, in turn, should and will contribute to increasing the competitiveness of ChMZ OJSC in the ferrous metal market, due to a significant increase in the yield of suitable steel, a decrease in the consumption of alloying elements, a reduction or even a reduction in the "no" of rejected smelts, an increase in the productivity of steelmaking production and a sharp improvement in the quality of metal products produced.

Considerable investments in the DSP100 Project with integrated off-furnace processing of steel with well-coordinated and well-organized work pay off within three years and contribute to the transition of ChMZ OJSC to a completely new technical and technological level of production.

The implementation of the DSP100 Project with complex off-furnace processing of steel allows to almost double the steel production volumes, while the quality of the produced steel will meet absolutely all, even the highest consumer requirements. Which in turn will allow ChMZ OJSC to abandon long-standing morally and technically obsolete open-hearth steel production.

The implementation of the DSP100 Project with complex off-furnace processing of steel will drastically reduce the polluting effect of the plant on the environment, on the production and maintenance personnel of ChMZ OJSC. Which should have an extremely favorable effect on the health of the staff of the city-forming enterprise and on the comfort of living in the city of Chusovoy.

The completion of the diploma project made it possible in the most detailed way to consider all the subtleties and features of electric steel production and to propose a project for implementation that contributes to the sharp technological and economic breakthrough of ChMZ OJSC, which fully justifies the necessary investments in its implementation.

What actually was considered and proved during my thesis project in the specialty of metallurgy of ferrous metals.