Design of mechanization of repair of DSP-50 lining in conditions of electric steel smelting shop of CJSC "STAX"

Contents

1 General part

1.1 Sulinsky Metallurgical Plant - Stax CJSC, stages

development

1.2 Development of electric steelmaking. The general

directions

2 Process Part

2.1 Arc electric smelting furnace. Smelting technology

in electric steelmaking furnaces

2.2 Technology of steel production in DSP-50 under conditions

Stacks Electric Steelmaking Shop

3 Special part

3.1 Design and operation of filling machine

3.2 Calculation of drive power and selection of electric motor as per

guidance materials

3.3 Kinematic calculation of the drive and selection of the gear box

3.4 Calculation and selection of brakes

3.5 Selection of drive lubrication system and lubricants

3.6 Repair of crane wheels

4 Occupational Safety and Industrial Safety

4.1 Repair of hot shop equipment - typical equipment

safety

4.2 Equipment installation and repair works - equipment

safety/special requirements/

5 Ecology and Environmental Protection

5.1 Environmental activities in enterprises related to

metal production and processing and operation

of metal products

5.2 Gaseous emissions from metal smelting in DSP- furnaces

and cleaning them

6 Economic part

6.1 Depreciation charges and their use on

enterprise

6.2 Calculation of physical and moral depreciation of fixed assets

7 List of sources used

2.2.3 Preparation of furnace for melting (filling)

2.2.3.1 In order to ensure the normal condition of the lining of electric arc furnaces, the following conditions must be observed:

- slope angle on the side of the outlet hole shall ensure complete metal and slag descent from the bottom;

- outlet hole shall have dimensions of 230x240x350mm;

- charge filling is performed at the command of the master of furnaces only after high-quality filling of slopes and dines.

2.2.3.2 For filling of the hearth and slopes, cooking of the furnace walls, electrical periclase (magnesite) powder of PPE88 or PPE87 grade is used as per GOST 2486281.

2.2.3.3 In order to ensure a more complete release of slag from the furnace, it is necessary that it is liquid-moving throughout the smelting.

2.2.3.4 After the smelting, the furnace is inspected by the master and steelworker. If there are damages of the lining in the form of separate pits and recesses on the slopes and undercarriage, the latter are probed with a metal shompole to determine the amount of metal remaining in them.

2.2.3.5 After the smelting, inspect the outlet hole and, if necessary, cut it to the required dimensions. Without cutting the outlet to nominal dimensions, it is forbidden to turn on the furnace for the next smelting.

2.2.3.6 If there are metal residues and slag on the bottom, they shall be removed by the following methods:

- at the beginning, the rear slope is filled with compliance with the conditions of paragraph 2.2.3.1. After that, tilt the furnace "to drain" and remove metal and slag residues through the outlet hole or "freeze" them on the filled rear slope;

- after filling the rear slope with a jet of oxygen (or air), blow out the remnants of metal and slag. At the same time, during oxygen blowing, the end of the oxygen tube must be kept at a distance of about 200 mm from the metal mirror. Under the stream of oxygen, it is necessary to give a large periclase powder in small portions, which is enveloped with metal, easily blown out of the pits onto the slopes;

- knock down the threshold (if it is high), then pour periclase powder on the slope at the threshold and remove the remains from the furnace with wooden scrapers. If the pits are located under the threshold slope, clean them with bent scrapers;

- when wooden scrapers fail to completely remove metal from the pits, the remainder of it can be removed by iron scrapers, by freezing metal on them, or kneading metal with magnesite in the form of "crits" and removing them from the furnace.

2.2.3.7 In the event of a "jamming" of the hearth or excessive cooling of the liquid metal, heat the metal with a jet of oxygen and, in accordance with 2.2.3.6, remove it from the furnace.

2.2.3.8 The slag in the recess is best removed using metal scrapers.

2.2.3.9 It is necessary to ensure that the metal is completely removed from the bottom of the furnace, otherwise the whole sub-welding will be lifted during the next melting.

2.2.3.10 Upon completion of removal of residual metal and slag from the furnace, the steelmaker shall inspect the condition of the furnace lining.

2.2.3.11 If there are damaged places, proceed to their correction by welding. Cooking is carried out with magnesite powder and powder from ground periclase - chromite brick.

2.2.3.12 Filling of bottom and slopes shall be performed as quickly as possible so that furnace lining does not cool down.

2.2.3.13 Filling (sub-welding) of the bottom is recommended to be performed with a layer of not more than 3040mm (visually). This thickness provides better sintering of periclase powder. Lime is not allowed on the filled bottom.

2.2.3.14 In case of large wear of slopes or presence of separate damages on them, reinforced filling with periclase powder wetted in liquid glass under the guidance of the master is performed.

2.2.3.15 In case of "overgrowth" of hearth and slopes by metal, the master of furnaces and steelworker shall "etch" the overgrowth areas with quartz sand. It is allowed to consume not more than 300 kg of sand for one etching. Etching can also be carried out with iron ore or cast iron, for which the latter is blended onto the bottom of the loading bucket and after the melt is released, the softened layer is removed by metal scrapers.

2.2.3.16 The condition of the furnace lining after the smelting discharge, the measures taken for the brewing, the cutting of the outlet hole and the welding of the walls, as well as the results of the measurement of the bath depth are put by the steelworker in the furnace lining status log.

2.2.3.17 The lower part of the furnace walls shall be filled with a filling machine or manually with periclase powder moistened with an aqueous solution of liquid glass. In case of significant wear of individual sections of walls, they are welded after charge filling.

2.2.3.18 Fine charge shall be filled in the place of proposed welding of walls. Filling of oil chips is not allowed. To ensure this condition, the master of furnaces must give instructions to the workers of the charge span on the procedure for laying the charge in the basket and check

2.2.3.19 The outlet arch shall be welded if its thickness is less than 200mm. The outlet arch is boiled with periclase powder closed with an aqueous solution of liquid glass. Welding is performed through the working window until charge filling. Before welding the arch, the outlet must be well separated, then a special metal tube Ø80mm, 350mm long, is inserted into the hole.

2.2.3.20 After welding the arch under the guidance of the master or steelmaker, the outlet hole is closed. The hole is clogged with dry magnesite powder. For denser clogging of the hole, magnesite powder is rammed with lime or wooden ramming. When clogging the outlet, it is allowed to use up to 50% of magnesite powder used. The closure of the opening is enhanced by a propped brick wall laid out in the drain chute at a distance of about 300400mm from the opening. Magnesite powder is packed into space between wall and hole.

2.2.3.21 Upon completion of furnace filling, electrodes are bypassed. For precise alignment of electrodes a special template is used.

2.2.4. Furnace Vault Care

2.2.4.1 When replacing the vault, the sealing seal (sandbox) must be loosened, metal, pieces of brick, slag and other materials larger than 30 mm are removed from it. If necessary, the shutter is supplemented with sand up to 2/3 of its height.

2.2.4.2 Electrode hole seals shall be installed on a mass of periclase-chromite powder and clay closed with an aqueous solution of liquid glass. In case of rains between the vault and seals, they must be immediately closed with the above mass.

2.2.4.3 In case of water leak to the roof from water-cooled valves, the furnace is immediately shut down and the necessary repair is carried out, preventing further water ingress to the roof lining.

2.2.4.4 Prevent overheating of the roof lining due to the continuous operation of the furnace with an open metal mirror.

2.2.6 Filling of charge materials

2.2.6.1 Filling basket (bucket) is installed on a special bench. The charge is carefully stacked in the basket and weighed.

2.2.6.2 The loading procedure of the filling basket is specified in paragraph 2.2.2.3 of this description.

2.2.6.3 Prior to filling the furnace, the master shall make a charge schedule to ensure the required composition of steel and record its results in the operational smelting chart.

2.2.6.4 For the intensity of the oxidation reaction of impurities of carbon, silicon, manganese, phosphorus and others, solid oxidizing agents (iron ore, pellets, etc.) with a mass of not more than 350 kg can be given to the roll. In case of such a need, a part of the litter is given on the bottom of the furnace with the help of a box in the form of small wastes, then solid oxidite-li is charged, and after that the main litter is made with a basket.

2.2.6.5 The basket shall be lowered smoothly into the furnace, at the same time it shall not be allowed to open prematurely and hit the bottom.

2.2.6.6 The furnace sludge mass shall ensure the level of liquid metal and slag in the furnace not higher than the lower level of the outlet.

2.2.6.7 When using a fine scrap of steel, low bulk density of which does not allow to cast the whole charge into the furnace in one take, after incomplete melting of the first portion of the charge, basements are made, at that large heavy scrap must be excluded from the charge of basements.

2.2.6.8 Filling basket with loaded and suspended charge is lowered smoothly into the furnace, melt touching is not allowed. During basements, the furnace window must be tightly closed, the workers must be at a safe distance from the furnace.

2.2.7 Beginning of melting/melting/

2.2.7.1 After filling the charge, the furnace is switched on to the 4 stage and for 10 minutes the wells in the charge are burned, after which the furnace is switched to the 1 stage until further melting.

2.2.7.2 The unalloyed part of the charge, which is on slopes, the steelworker collides to the middle of the bath or is cut with oxygen. Electrodes are raised when this operation threatens to break them. It is permitted to start purging of liquid metal with oxygen under current after melting of at least 80% of the charge (approximately) and excess of carbon content above the average value in the metal by at least 0.30.5%.

2.2.7.3 During the period of melting of the charge, as the amount of liquid metal increases to direct slag in the furnace, lime or limestone of the fraction 20100mm with a total mass of up to 3.0% of the weight of the metal charge is assigned in several methods. If necessary, in order to reduce the viscosity of slag, an additive of chamotte combat or melting spar is allowed.

2.2.7.4 3035 minutes before the charge is completely melted, solid oxidizers (iron ore, pellets, etc.) with a total mass of 10 kg begin to be added to the furnace by hand. per ton of steel in three receptions with an interval between portions of 3-5 minutes. Each subsequent portion of oxidizer is added when the boiling intensity is reduced. At the same time, the slag should be foam and liquid-moving and go through the threshold of the working window. It is allowed to take a preliminary sample to determine the chemical composition of the metal before the charge is completely melted. In the case of low phosphorus content in steel (less than 0.02% for 35GG steel), slag is not allowed to be fully downloaded .

In the case of "soft" melting (i.e. reduced carbon content), carburize the metal with the necessary carbon-containing materials (coke, coal, broken graphitized electrodes, etc.) supplied to the metal, having previously downloaded slag.

2.2.7.5 After complete melting of the whole charge, the whole mass of slag (approximately) is removed from the furnace (under current) and updated by means of lime additive or limestone 10-12 kg/t, chamotte fighting of fraction 20100mm to 2 kg/t of steel.

2.2.8 Oxidation period of melting

2.2.8.1 The oxidation period begins after the metal is heated to a temperature of at least 15300. After that, the bath is thoroughly mixed with a metal rod and a metal sample is taken for complete chemical analysis.

The sampling time of the first sample was the beginning of the oxidation period.

The task of the oxidizing period is to oxidize carbon, remove phosphorus, reduce the content of impurities, gases, partially sulfur and heat the metal in the metal composition.

2.2.8.2 During the bale period slag shall be main, foam, liquid-moving and gravity flow through the threshold of the working window.

To ensure this state of slag, lime or limestone is deposited simultaneously with solid oxidizers, as well as chamotte battle.

Solid oxidizers are added in portions that do not exceed 75 kg with the interval between the delivery of the next portion of 3-5 minutes, maintaining vigorous boiling of the bath.

The introduction of large portions of oxidizing agents is undesirable because it can cause cooling of the metal and boiling will be weak.

The excess of unreacted solid oxidite lei in the bath during subsequent heating of the metal can cause a very rapid oxidation of carbon and lead to the release of metal and went from the furnace. Therefore, in the event of a boiled bath, the oven is disconnected and the personnel serving the oven are removed to a non-hazardous area. Only after a significant decrease in boiling intensity is another portion of oxidizing agents added. The input power is controlled according to the temperature of the metal, which should be gradually increased.

2.2.8.3 During the boiling period, at least 0.200.30% carbon for St 5 and 0.300.40% carbon for St3 is oxidized.

2.2.8.4 After the addition of the last portion of solid oxidizers or the completion of oxygen purging, the bath is kept at "pure" boiling (oxidation should occur due to the early introduction of oxides) for at least 10 minutes, after which the slag is downloaded at the beginning under current, and therefore when the furnace is turned off.

Before downloading the slag, a metal sample is taken for complete chemical analysis, the metal temperature is measured.

The mass fraction of phosphorus should be not more than 0.020%, the mass fraction of carbon - for St5 0.200.30% and St3 - 0.090.16%.

In case of significant metal reoxidation (carbon mass fraction less than 0.09%), it is recommended to perform preliminary metal deoxidation at the end of the bale with an additive of ferromanganese or cast iron with the mass agreed with the limits of the given analysis for manganese and carbon.

The metal temperature before loading the slag shall be within 161016300C.

2.2.8.5 The following conditions are required for sulphur removal during the smelting oxidation period:

- liquid-moving, active, foam main slags (coke, lime, chamotte battle is periodically placed on the slag to maintain the slag in the foamed state);

- reduction of Ca content - in slag by its gravity flow through the threshold of the working window and guidance of new slag;

- increased metal temperature 1620-16300С

The oxidative period shall be not less than 30 minutes. It is allowed to supply metal with oxygen at increased carbon content during the oxidizing period.