SU1765222A1 - Method of electro-slag ferrotitanium melting - Google Patents

Abstract

Use: in the field of special electrometallurgy, and is intended to obtain ferrotitanium from titanium chips by electroslag melting. SUMMARY OF THE INVENTION: A slag bath is induced in the crystallizer by means of non-consumable metal cooled electrodes and titanium and steel chips are gradually melted in the slag. When loading steel chips in an electrical circuit, periodically disconnect the current for 1-3 seconds with a frequency of 0.1-2 minutes. 1 hp f-ly, 2 tab.

Description

The invention relates to the field of special electrometallurgy and is intended to produce ferrotitanium from titanium and steel chips.

The purpose of the invention is to ensure uniformity of the chemical composition of the ingot and stable energy regimes of the electroslag process.

The essence of the invention is as follows.

In the crystallizer, non-consumable metal cooled electrodes induce a slag bath and titanium and steel chips are fed from the bunker at a given weight ratio, which melts in the slag, the metal accumulates under it, and the ingot gradually cools. Periodically, as chips stick to the electrode, the current is interrupted in the electrical circuit. After the current is turned off around the electrode, the magnetic field disappears and the chips fall into the slag bath. The current in the electrical circuit was interrupted by a special thyristor device included in the primary circuit.

power transformer. After a control signal is applied to the thyristor, it closes an interruption in the current circuit. Accordingly, the current is also interrupted in the secondary power circuit of the transformer, i.e. and on the electrode.

The intervals through which the current is interrupted (0.1–2 min) and the time it is interrupted (1–3 s) are interrelated with the process indicators and ensure the achievement of the set goal.

First, if the current is not disconnected, the steel chips will adhere to the electrode and not get into the slag bath, i.e. we will not get ferrotitanium ingot. Only titanium will melt. Secondly, as the amount of chips adhering to the electrode increases, a short circuit occurs through it between the mold and the electrode, or between two electrodes.

Cutting off the current at the specified intervals and dropping the chips from the electrode into the slag bath ensures that it is evenly fed to the mold at specified weight ratios from the titanium

J

WITH

ate you

shavings and thereby ensures the uniformity of the chemical composition over the height of the ferrotitanium ingot.

Melting was carried out in a laboratory setup in a mold with a diameter of 270 mm. The current to the slag bath was supplied by non-consumable metal cooled electrodes with tips of molybdenum. Remelting was carried out on ANF-1P slag (pure calcium fluoride — CaFa) with the addition of 8–10% titanium oxide TI02) at a voltage of 40 to 60 V and a current of 2000–3000 A. The chips (titanium and steel) were loaded separately from different bunkers.

Before melting, the chips were crushed and burned in a resistance furnace at 350-400 ° C for 1.5 hours. This allowed the use of a mechanized load and the elimination of slag foaming during emulsion burn-up.

Ferrotitanium ingots with titanium content of 40 and 70% were produced. The weight of the ingot was 100-150 kg. The ingots had a good surface, differed by the uniformity of the chemical composition.

Remelting the prepared chips (crushed and burnt from the emulsion when the current is interrupted is not difficult. During the experiments, optimal intervals and the current off time were set.

The time for which the current is switched off for 0.5-3 s is justified by the data in Table 1.

If the switch-off time is less than 1 second, then, firstly, not all chips are detached from the electrode, and, secondly, those that are torn off and not having time to reach the slag bath, the chips again stick to the electrode.

If the off time is longer than 3 s, then a layer of slag is frozen on the cooled electrode, which begins to influence the process parameters. By increasing the resistance in the electrical circuit introduced by a thin crust of slag, the current is reduced. After some time (approximately 40-50 seconds), the slag crust melts and the process stabilizes. However, a decrease in the current and a decrease in heat generation in the slag affects the technical and economic performance of the process, namely the productivity of the propellant.

Table 2 presents the results of the experiments depending on the change in the periodicity of current interruption.

The frequency of switching off the current 0.1-2 minutes is due to the stable conduct of the electroslag process. When the current is turned off after 0.05 minutes further by 0.5 s, no

stable electroslag process. A gradual decrease in the current takes place and after a while the electroslag process fades and stops. This occurs as a result of a gradual increase in slag skull on the electrode.

The upper limit of 2 min is set based on the uniformity of the chemical composition of the ingot. As the chips load, it sticks to the electrode and when the current is turned off, the chips fall into the slag bath. The amount of chips adhering to the electrode is constantly increasing, and with the amount of chips that comes off after 2 minutes, it is possible to obtain a uniform chemical composition of the ingot by averaging titanium metal and iron in a metal bath.

Experiments were carried out at a chip loading rate of 50 to 300 kg / h and showed that the energy parameters of the process (U, J), the slag temperature, the productivity of the melt, the size of the liquid metal bath are very interconnected. With an increase in the power input, the temperature of the slag increases, the rate of penetration and the volume of the metal bath increase. But on average, in the range of input power from 80 to 180 kW, the speed of fusion is from 50 to 300 kg / h, the upper limit is 2 minutes. was indicative throughout the range. Here, the height of the slag bath plays a major role, the slag temperature along the height of the slag bath, since titanium has a density of 4.5 g / cm3, and steel 7.5-7.8 g / cm3 and their melting occurs in different layers of slag, besides, their melting points are 1725 and 1350 ° С.

Thus, the claimed method, with the parameters indicated in the application, ensures obtaining high-quality ingot of ferrotitanium from titanium and steel (magnetic) chips.

Claims (2)

1. A method of electroslag smelting of ferrotitanium from titanium and steel chips, including pointing in a crystallizer by means of non-consumable metal cooled electrodes of a slag bath and gradual melting of titanium and steel chips in slag, in order to ensure uniform chemical composition of the ingot and stable energy modes of electroslag process, when loading steel chips in an electrical circuit periodically shut off the current. 2. The way pop. 1, characterized in that the current is switched off at 1-3 at intervals of 0.1-2 minutes. Options The nature of the electroslag process Current in A through, min one ten thirty The thickness of the slag skull on the electrode after 30 min, mm The uniformity of the chemical composition of the ingot Table 2 ----------------- ---- .. "." .. ".-, .. Interruption of a current, min. P, 05  0.1 1.0 I 2.0 J 2.5 Dies out Stabil. Stabilized. Stabilized. Stabilized. zoo zoo zoo zoo Zoo Zoo Zoo Zoo Zoo Zoo Zoo Zoo 1.6 0.05Second No No Not there is There is Not