RU2348715C2 - Furnace of magnesium continuous refinement - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns devices for refinement of magnesium. Furnace of magnesium continuous refinement with salt heating includes lined cylindrical casing installed inside on supports alloying basket with central vertical channel, crown, introduced through side wall lower than alloying basket electrodes and bottom with bevels. At that distance from bottom till electrodes is 200-300 mm, and distance from electrodes till alloying basket is 1.0-2.0 of electrodes height. Electrodes are located symmetrical relative to vertical axes of furnace and relative to each other. In crown above electrodes there are implemented manholes with covers. Supports of alloying basket bear on electro- insulating supports or gaskets, and top edge of electrodes is implemented as bevel. Diameter of bottom horizontal part is 0.5-0.95 of distance between diametrical electrodes.

EFFECT: stabilisation of electrical and temperature conditions of furnace.

7 cl, 2 dwg

Description

The invention relates to the production of non-ferrous metals, particularly to devices for refining magnesium.

Known furnace with salt heating for melting magnesium (ed. St. USSR No. 1603916, F27B 3/08, C22B), containing a lined shaft with bevels on the bottom, electrodes and an annular cap, and the electrodes are located below the cap. The disadvantage of the furnace is a possible violation of the electric mode of the furnace when the electrodes are located unacceptably close to the bell or hearth with sludge accumulated on it.

A known furnace for refining magnesium, including a casing with a lined bath with electrodes, inside of which a bell with nozzles and a bottom is installed. The disadvantage of such a furnace, shown in the drawing in the description of the patent of the Russian Federation No. 2222623, is the location of the heating electrodes opposite the bell walls, which leads during operation to the misuse of the power of the heating transformer, to the need to increase the distance between the lining and the bell, increasing the overhead volume of the furnace.

Known furnace continuous refining of magnesium (RF patent No. 2228964), adopted as a prototype, including a arch, a casing with a lined bath with electrodes, with a bell installed inside it. In the drawing, in the description, the bell is mounted on the anodes above the electrodes. The disadvantage of this furnace is the instability of the electric and temperature conditions of the furnace when the electrodes are insufficiently removed from the bell element and the hearth with the magnesium-containing sludge accumulated on it. In addition, the electrodes do not have access for cleaning.

The technical result is the stabilization of the electric and temperature conditions of the furnace, and therefore, the quality of the refining and productivity of the furnace by clarifying the location of the electrodes in the furnace.

The technical result is achieved in that the furnace includes a cylindrical vertical lined casing, a bell with a central channel mounted inside the supports, a hearth with bevels, a vault and electrodes introduced through the side wall below the bell;

the distance from the bottom to the electrodes is 200-300 mm, and the distance from the electrodes to the bell is 1.0-2.0 of the height of the electrodes;

while the electrodes relative to the vertical axis are located symmetrically and at the same level;

while in the arch above the electrodes are made hatches with covers;

wherein the bell stands are located symmetrically between the electrodes;

while the bell supports are supported by insulating supports or gaskets;

the upper face of the electrodes in the furnace volume is made beveled;

the diameter of the horizontal part of the hearth is 0.5-0.95 of the distance between the diametrically located electrodes.

Figure 1 shows a vertical section of the furnace, and figure 2 is a layout of the electrodes and supports of the bell in the plan. The numbers indicate: 1 - electrode; 2 - support; 3 - lining; 4 - bell; 5 - arch; 6, 7 - hatches; 8 - insulating gasket; 9 - beveled edge of the electrode; 10 - hearth. The letters denote: a - the distance from the bottom to the electrode; b is the distance from the electrode to the bell; C is the height of the bell; L is the distance between the electrodes; ⌀D is the diameter of the horizontal part of the hearth.

The optimal ratios of the position of the electrodes, the bell and the lining have been studied and selected on an analog water model of the furnace.

Changing the distance from the hearth to the electrodes —– less than 200 mm according to the conditions of working with the melt, can lead to short circuits through the metal-containing sludge, and when –– more than 300 mm, an overlay on the bottom can form, since the melt flows will be closed in higher layers.

The distance from the electrodes to the bell -b- less than one height of the electrodes reduces the overall electrical resistance of the furnace, since part of the current branches into the bell material; at a distance of -b- more than two electrode heights, the depth of the furnace unreasonably increases and its maintenance is complicated. This refers to the actual height of the electrodes 80-300 mm, and with a larger value, a smaller ratio is taken, for example, with c = 300 mm b = 1.0 · s, and with c = 80 mm b = 2.0 · s.

The symmetrical arrangement of the electrodes makes it possible to rationally heat the largest area of the hearth and evenly the bell.

The symmetrical arrangement of the stands also aligns the electric field in the salt environment.

Placing the bell in the supports on insulating supports or gaskets reduces leakage currents through the lining and reduces the possibility of violating the integrity of the lining.

On the upper face of the electrodes, sludge may settle, so sloping it helps to clean the electrode. In addition, the hatches in the arch above the electrodes allow you to monitor the condition of the electrodes and, if necessary, blow them with air.

The diameter of the horizontal part of the hearth is less than the distance between the electrodes (⌀D <L = 0.5-0.95L) facilitates cleaning the hearth from sludge with tools and mechanisms and reduces the possibility of shorting the electrodes with metal-containing sludge.

The furnace operates as follows.

Salt from a mixture of chlorides of alkali and alkaline earth metals, which serves as a refining and heating medium, is poured into the furnace, raw magnesium is poured into the bell and, after settling for 10-30 minutes, refined magnesium is removed. The process temperature of 690-710 ° C is supported by alternating current supplied to the electrodes of the furnace through a step-down furnace transformer, which can be either three-phase (in this case the number of electrodes is a multiple of three) or single-phase (the number of electrodes is a multiple of two).

The sludge-salt mixture is periodically removed from the furnace by adding fresh portions of salt melt or partially loading in solid form.

The heated melt rises along the lining, and the flow closes through the central channel in the bell.

Tests of the pilot industrial version of the furnace with the proposed parameters and elements showed its reliable operation and the ability to control the temperature of the melt.

Claims (7)

1. A continuous salt-refined magnesium refining furnace, including a lined cylindrical casing, a bell with a central vertical channel mounted inside the racks, a vault, electrodes introduced through the side wall below the bell, and a bevel with bevels, characterized in that the distance from the bottom to the electrodes is 200 -300 mm, and the distance from the electrodes to the bell is 1.0-2.0 of the height of the electrodes. 2. The furnace according to claim 1, characterized in that the electrodes relative to the vertical axis of the furnace are located symmetrically and at the same level. 3. The furnace according to claim 1, characterized in that in the arch above the electrodes are made hatches with covers. 4. The furnace according to claim 1, characterized in that the bell supports are located symmetrically between the electrodes. 5. The furnace according to claim 1, characterized in that the bell supports are supported by electrical insulating supports or gaskets. 6. The furnace according to claim 1, characterized in that the upper face of the electrodes in the volume of the furnace is made beveled. 7. The furnace according to claim 1, characterized in that the diameter of the horizontal part of the hearth is 0.5-0.95 of the distance between the diametrically located electrodes.

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