RU2603409C2 - Electroslag remelting furnace with hollow nonconsumable electrode - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to special electrometallurgy, in particular to electroslag remelting furnaces, and can be used during metal working industry wastes remelting in form of alloyed steels chips. Furnace is equipped with electrode auger feeder with electric drive fitted in upper part, charge materials supply batching system, installed above electrode butt-to-butt with intermediate funnel, which outer side is coated with electrically insulating material, post mounted on electrode displacement mechanism, on which mounted attachment and movement mechanisms of said bin, dosing unit and electric drive with possibility to adjust their position in vertical plane relative to post independently from each other, and metal chips remelting process automatic control system, integrated with charge materials supply batching system control and auger feeder rotation speed control system, wherein said electrode is made hollow along entire length, and said bin, batching system and electric drive attachment and movement mechanisms and electric drive and auger feeder connection are equipped with electrically insulating inserts.

EFFECT: invention allows creating electroslag remelting furnace with nonconsumable hollow graphitized electrode for metal chips recycling without production process disrupting due to charge materials hanging.

1 cl, 1 dwg

Description

The invention relates to metallurgy, in particular to electroslag remelting furnaces, and can be used in the recycling of metal processing wastes in the form of metal shavings.

A known method (patent RU 2405843, publ. 10.12.2010), allowing the use of lump and chip waste of tool production for the production of ingots from tool steel by electroslag remelting.

The disadvantage of this method is the impossibility of remelting metal chips in an ESR furnace without the use of additional equipment, in this case an arc furnace, because preliminary smelting of electrodes from lump scrap is necessary. The use of double remelting significantly increases the cost of the resulting workpiece. Also, when melting high alloy steels in an arc furnace, high fumes of alloying elements are possible due to the influence of an electric arc, which will require additional alloying with ferroalloys even if the steel grade in the lump scrap was initially identical to that smelted. This method involves the melting of scrap in an arc furnace, and remelting chips in the furnace electroslag remelting together with the previously melted consumable electrode. From this description it is not clear what should be done if there is no lump scrap necessary for melting in an arc furnace with the further manufacture of a consumable electrode. In terms of the set of technical and economic indicators, the proposed method is comparable with the “classical” two-stage method of remelting (arc furnace - ESR).

It is also known a device (RU 72227, publ. 10.04.2006), which allows smelting cast iron shavings in a melting tank, containing a melting tank with a drain device and a lifting vault, equipped with a refractory heat-insulating lining, a fixed hearth electrode and a movable non-consumable electrode.

The disadvantage of this device is that the melting tank used is suitable only for remelting cast iron or ordinary steel grades. When smelting high-grade grades of steel, fusion of the lining material is possible.

Also known is a device (RU 2483126, publ. 05.27.2013), which allows smelting metal-containing waste directly in the furnace electroslag remelting using non-consumable electrodes.

The disadvantage of this invention is refractory spraying on the surface of the mold, because this coating can only be used in electroslag remelting furnaces with a mechanism for drawing an ingot from a mold or a movable mold. Also, in furnaces with a fixed ingot, mold and pan, the use of refractory spraying is impossible, because as the ingot melts, the liquid metal, and subsequently directly the ingot itself, will begin to come into contact with this deposition, which will lead first to a deterioration of the surface of the obtained ingot, and subsequently to a change in the diameter of the ingot, commensurate with the thickness of the refractory spraying. It is also possible that particles of spraying enter liquid metal, which will lead to marriage of the resulting product.

It should be noted that at present, electroslag remelting plants with a movable mold and a tray are used, as a rule, for smelting medium and large ingots, but smelting ingots of this size from metal-containing waste is not economically feasible, because for the production of such ingots, it is difficult to choose a mixture in the form of metal-containing waste of homogeneous chemical composition, and it is also difficult to control the quality of products obtained by this technology. In the event of a marriage during the smelting of medium and large ingots, the economic indicators of this technology are lower than in the classical scheme with steel electrode melting.

At its core, the proposed device is one of the options arc-slag, not electroslag remelting with all its inherent disadvantages, primarily the high fumes of alloying elements under the influence of the arc. When remelting high alloy steels according to the proposed scheme, this can lead to a defect in chemical composition due to the burning of elements such as, for example, chromium and titanium.

The closest to the proposed technical essence and the achieved result is an ESR furnace used for remelting chips (Intensification of special metallurgy processes, Shalimov A.G., Gotin V.N., Tulin N.A. M .: Metallurgy, 1988, p. 295-302).

This furnace allows for one-stage electroslag remelting of chips, which can provide insignificant fumes of the main alloying elements of high-speed steels, eliminating additional doping during remelting of chips with a final chemical composition; a defect-free surface of the ingots that does not require stripping before deformation; high chemical and structural homogeneity of the metal with a low content of impurities and gases, and, as a result, increased yield of the product due to the increased deformability of the ingot and a decrease in the head and bottom trimmings; the best complex of physicochemical properties compared to conventional smelting metal; simplicity and reliability of the equipment used. The described device is taken as a prototype of a utility model.

The device consists of a hopper for charge materials, an inclined trough, an intermediate funnel, a vibrating batcher, a consumable metal or non-consumable graphitized electrode, a power source and a crystallizer.

The disadvantage of this prototype is that when using a non-consumable electrode, it is located coaxially with the funnel and has a circular shape in cross section. In practice, this leads to the supply of chips from only one side of the electrode, as well as to the hanging of charge materials, in this case, chips, between the electrode and the funnel. To minimize charge sticking, it is possible to reduce the diameter of the graphitized electrode, this is especially true when carrying out the process in installations with a small crystallizer diameter, but this can lead to electrode destruction due to dissolution of graphite in the slag. The destruction process with a small diameter of the electrode is confirmed experimentally - this is due to the large current flowing through a unit surface of the electrode.

The technical result of the invention is to eliminate the suspension of charge materials in the form of chips in the process of electroslag remelting according to the proposed scheme, as well as, if necessary, increasing the area of the non-consumable graphitized electrode in order to reduce the current passing through the surface unit of the graphitized electrode, and, as a result, reduce erosion of the electrode and minimizing carburization of metal.

The technical result is achieved as follows - the electrode is made hollow. The electrode is made of graphitized material and is non-expendable. A screw feeder is installed in the upper part of the electrode to prevent the charge materials from hanging due to the welding of chip particles in the lower part of the electrode under the influence of high temperature. As in the classical electroslag remelting process, the electrode is used to supply electric current and maintain a given temperature of the slag bath. The outer side of the protective funnel is covered with an insulating material. A device for attaching a protective funnel is also electrically isolated from the power circuit of the electroslag remelting unit. The control system of the feed meter for the charge of materials is connected to a control system for the rotational speed of the screw feeder, as well as to a system for automatically controlling the remelting process. The parameters of the control systems are selected depending on the diameter of the mold used, the grade of the melted metal and other technological characteristics.

The invention is illustrated in the drawing, where in FIG. 1 shows a device.

On the electroslag remelting furnace, on the mechanism (1) for moving the electrode, a rack (2) is fixed, on which mechanisms (3, 4, 5) are mounted for fastening and moving the following units: hopper (6) for charge materials, batcher (7) charge materials, electric drive (8). Mounting and moving mechanisms allow you to adjust the position of the units in a vertical plane independently of each other. For electrical safety purposes, mechanisms are equipped with electrical insulating inserts (9, 10, 11).

The steel consumable electrode was replaced by a hollow non-consumable electrode (13). Melting is carried out in a copper water-cooled crystallizer (14) with a copper water-cooled tray (15). The electrode holder and the pallet are connected according to the attached diagram with a power source (16). In the upper part of the electrode cavity there is a screw feeder (17), driven by an electric drive (8). The connection of the electric drive with the screw feeder is equipped with an insulating insert (12). The electric motor together with the screw feeder by means of the device (5) move can change the vertical position relative to the non-consumable electrode. Over the electrode, end-to-end, a funnel (18) is placed along which charge materials enter the hole of the electrode.

The principle of operation is as follows: the chips, previously cleaned of cutting fluids, are loaded into the bunker for charge materials, from where it enters the dispenser, and then into the intermediate funnel. Then, the chips enter the hole of the electrode and gradually pass through the cavity of the electrode and drop into the slag bath, the metal in the form of drops through a layer of liquid slag enters the liquid metal bath, and when metal passes through the flux layer, refining from non-metallic inclusions occurs. Subsequently, the metal crystallizes in a water-cooled crystallizer. The feed rate of the charge materials is controlled by the dispenser, and for a more uniform feed into the melting zone, an auger feeder is also installed. The principle of heat generation in a slag bath is similar to that used in ESR furnaces with a consumable electrode. Productivity depends on the feed rate of the charge materials.

The technical result consists in the possibility of using an electroslag remelting furnace with a non-consumable graphitized electrode for recycling metal chips without disrupting the process due to the suspension of charge materials, as well as minimizing carburization of the melt.

Claims (1)

An furnace for electroslag remelting of metal shavings, containing a non-consumable graphitized electrode with an electrode holder and a mechanism for moving it, a water-cooled mold, an intermediate funnel, a hopper for charge materials and a power source, characterized in that it is equipped with an electrically driven screw feeder installed in the upper part of the electrode, and a feed dispenser charge materials installed above the end-to-end electrode with an intermediate funnel, the outer side of which is covered with electrical insulation ion material fixed to the mechanism for moving the electrode by a rack on which the mechanisms for fastening and moving the said hopper, dispenser and electric drive are installed with the possibility of regulating their position in the vertical plane independently from each other, and an automatic control system for the remelting of metal chips integrated with the dispenser control system supply of charge materials and a control system for the rotational speed of the screw feeder, wherein said electrode Execute the hollow over the entire length, and said mounting and moving mechanisms hopper, metering device and the actuator and connecting the actuator and the screw feeder provided with insulating inserts.

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