RU2026365C1 - Device for treatment of molten metal - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: device for treatment of molten metal includes metal supply tube, plasma generator and additional heated runner-outlet (one or more) with swirling mixer installed at its end. Plasma generator is mounted inside metal supply tube vertically and coaxially with it. EFFECT: higher efficiency. 1 dwg, 1 tbl

Description

 The invention relates to metallurgy and foundry, in particular to the processes of refining and modification of ferrous and non-ferrous alloys.

 Known devices for out-of-furnace treatment of cast iron containing a gas lift column, a gas separation chamber, a tuyere for introducing a conveying gas with a desulfurizer, and a tuyere for introducing an oxygen-containing gas [1].

 The disadvantage of these devices is the loss of chemical heat of cast iron, which is extremely important when pouring it into the converter.

 Also known installation for the implementation of the circulating method of evacuation of steel [2].

 The disadvantage of such devices is that due to large heat losses during metal processing, its temperature is significantly reduced.

 The closest in technical essence to the claimed is a degassing tank for evacuating steel by the circulation method, equipped with a metal wire, the ends of which are immersed in the melt. A plasmatron is installed on the metal pipe of a degassing vessel [3].

 The disadvantages of the device selected as a prototype include the incomplete use of temperature and hydrodynamic characteristics of a plasma jet due to its small contact zone with the melt. As a result, the low effect of refining or modification of the melt and the low quality of cast products.

 The aim of the invention is to increase the efficiency of refining and modification of alloys.

 This goal is achieved by the fact that the device for processing liquid metal, including a metal wire, the plasma torch is additionally equipped with a heated drain (one or more) pipe, at the end of which a vortex mixer is installed, and the plasma torch is mounted vertically and coaxially inside the metal wire.

 Such a technical solution allows the melt to be transported in the metal pipe by high-enthalpy gas with subsequent heating of the metal in the drain pipe and to supply reagents through the vortex mixer. As a result of this, the efficiency of the processes of refining and modifying iron-carbon and non-ferrous alloys increases. Along with the specified processing of the melts by the proposed device allows you to maintain within the specified limits the temperature of the metal or overheat it during processing.

 The location of the plasma torch inside the metal wire coaxially with it allows melt to be transported in the metal wire by high enthalpy gas coming from the plasma torch. As a result of this, the melt-gas interface increases due to the intense crushing of high-temperature gas at the exit of the plasma torch nozzles. This enhances the effects of refining and modifying alloys.

 The installation of a vortex mixer at the end of the drain pipe allows the reagents to be introduced deep into the metal using a vortex turbulent jet. As a result of this, the introduced reagents are sufficiently dispersed, well mixed and evenly distributed in the melt. As a result, the degree of their assimilation increases and the effects of refining and modifying the metal increase.

 The presence of a heated drain pipe (for example, using a channel induction heater) allows you to continuously heat the metal at the outlet of the metal wire. As a result, reagents that do not interact with the metal, which enter the melt through the vortex mixer, rising with the metal through the metal wire, are additionally heated by the transporting high-temperature gas and in the drain pipe. This provides a more complete assimilation of the introduced additives and, as a result, high effects of refining and metal modification.

 The drawing shows the proposed device.

 A plasma torch 2 is installed along the axis of the metal wire 1. An induction heater 4 of the channel type is mounted on the drain pipe 3. The drain pipe is connected to the vortex mixer 5, which is mounted on the lid 6 of the bucket or crucible 7 with metal.

 The proposed device works as follows.

 The metal wire 1 with the included plasma torch 2 is immersed in the melt. In this case, the drain pipe 3 is connected to the vortex mixer 5. The high-temperature gas that comes from the plasma torch 2, the melt rises through the metal wire and enters the drain pipe 3. When passing through the drain pipe, the melt is additionally heated by an induction heater 4 of the channel type. The required processing reagents are fed into a swirling melt stream in a vortex mixer. After processing, the metal wire is removed from the melt, the lid is removed along with the vortex mixer, and the metal is cast. After this, the operations are repeated again.

 The testing of the proposed device was carried out in the foundry IPL AN USSR. The processing of the aluminum alloy AL9 by the proposed device was carried out in a resistance furnace with a crucible with a capacity of 150 kg.

 For this purpose, argon was opened to the plasmatron and the metal wire was immersed in the melt so that the end of the drain pipe docked with the landing flange of the vortex mixer with a tangential supply of metal. By closing the electrodes included plasmatron. After that, a channel-type induction heater was placed on the drain pipe. The heater was connected to the source of the IST-016 induction furnace. The argon consumption in the plasmatron was regulated by a needle valve (TU 26-07-032-76), controlled by a rotameter. The processing of the melt by the proposed device was carried out for 4 minutes During melt processing, the current on the plasmatron was maintained within 400–420 A at a voltage of 35–40 V, which were supplied from a VDU-506 UZ feeder source.

The power supplied to the induction heater was maintained in the range of 15-18 kW. During the processing time at the specified energy parameters of the melt temperature was increased from 640 to 750 ^C. These results show yet another advantage of the apparatus - it reduces the overheating temperature of the metal in the melting furnace and combine this operation with the processing of the melt in the ladle.

The melt was processed by the proposed device with the induction heater turned on and off. A universal flux of the following composition, wt.% (30 NaF + 50 NaCl + + 10 Na ₃ AlF ₆ + 10 KCl) was used as refining and modifying reagents. The flux was fed into the melt through a vortex mixer by filling it into a conical funnel with a tangential supply of metal.

 The degree of removal of hydrogen, oxides from the melt, as well as the modifying effect under various processing conditions of the alloy by the proposed device are presented in the table.

The hydrogen content in the AL9 alloy was determined by vacuum extraction, of the oxides by electrolytic precipitation, the modifying effect was determined by the number of grains per 1 cm ^{2 of a} thin section with a microscope magnification of 200 times.

 After processing the melt with the proposed device, along with its heating and efficient refining, the α-solid solution and the eutectic phase in the alloy are ground. As a result of grinding the structure and deep refining of the alloy, the strength and the plastic characteristics of cast metal increase by 10–15% and increase by 35–40%.

Claims (1)

 A device for processing liquid metal, including a metal wire, a plasma torch, characterized in that it is additionally equipped with at least one heated drain pipe, at the end of which a vortex mixer is installed, while the plasma torch is mounted vertically and coaxially inside the metal wire.

Images