RU2235258C1 - Technogenious material processing electric furnace - Google Patents

Abstract

FIELD: nonferrous metallurgy.

SUBSTANCE: invention relates to designing and operation of ore-smelting electric furnaces operating with dipping of electrodes into melt of material and it can be used in ferrous metallurgy and in chemical industry. Proposed electric furnace has body with side walls, charging devices, electrodes assembled into groups, one of which is installed in furnace hearth and connected to one pole of current source, and other is dipped into melt of processable raw material and is connected to other pole of current source. Electrodes of different polarity are installed at alternation, one after the other. Moreover, vertical partitions made of non-conducting material and dipped into melt of processed technogenious raw material are installed between different-polarity electrodes on side walls of furnace. Invention is aimed at improving reliability of dc electric furnace in operation when furnace is used for processing technogenious raw materials containing heavy and light nonferrous metals-out-of-balance and rebellious polymetallic ores, current and accumulated intermediate products such as slags, slimes, clinkers with high content of valuable components and secondary raw materials and practically any waste materials with distilling volatile changing over non-volatile valuable components into bottom phase.

EFFECT: improved processing of raw materials at increased yield.

1 dwg

Description

The invention relates to the field of non-ferrous metallurgy, in particular to the design and operation of ore-thermal electric furnaces working with immersion of electrodes in the melt of the processed material, and can also be used in ferrous metallurgy and chemical industry.

Known depletion furnace for processing slag, lined with refractory, with electrodes connected to an alternating current source, the working ends of which are located at some distance from the bottom (Silver Y.L. Electrofusion of copper-nickel ores and concentrates. - M .: Metallurgy, 1974, p. 233-237).

A disadvantage of the known design is the low productivity due to the increased loss of valuable components with slag and excessive dust build-up on the bottom of the furnace.

The closest analogue to the claimed invention is an electric furnace for processing anthropogenic raw materials, including a housing with side walls, loading devices, electrodes combined in groups, one of which is installed on the bottom of the furnace and connected to one pole of the current source, and the other group is immersed in the melt of the processed raw materials and connected to the opposite pole of the current source, while the electrodes of different polarity are installed through one (RF patent No. 1704536, IPC F 27 V 3/08, publ. 26.08.93).

A significant drawback of the known furnace design is its low reliability in the case of processing materials containing light metals in it.

It was experimentally established that in the case of processing materials containing light metals (for example, aluminum) in a given electric furnace, the latter accumulate in a layer on the melt surface of the processed material, which can lead to a short circuit between electrodes of different polarity and failure of the installation as a result of operation overcurrent protection.

The claimed invention is aimed at improving the reliability of the DC electric furnace used for processing technogenic raw materials containing heavy and light non-ferrous metals - off-balance and difficult-to-recycle polymetallic ores, current and accumulated non-target intermediate products (slag, sludge, clinker, etc.) with a high content of valuable components, as well as secondary raw materials and almost any waste with distillation of volatile and transfer of non-volatile valuable components to the bottom phase.

To achieve the technical result noted above in an electric furnace for processing technogenic raw materials, including a case with side walls, loading devices, electrodes combined into groups, one of which is installed on the bottom of the furnace and connected to one pole of the current source, and the other group is immersed in the melt of the processed raw materials and connected to the opposite pole of the current source, while the electrodes of different polarity are installed through one, in accordance with the claimed invention between the electrodes of different polar In these cases, vertical partitions mounted on the side walls of the furnace are made of non-conductive material, the lower part of which is immersed in the melt of the processed technogenic raw materials.

The invention consists in the following.

The conducted experimental studies showed that the installation of vertical partitions fixed on the side walls of the electric furnace made of non-conductive material, the lower part of which is immersed in the molten material being processed, eliminates short-circuit currents flowing through the light metal layer located on the melt surface, which significantly increases the reliability of the furnace in the case of processing materials containing both heavy and light valuable metals, thereby expanding the scope of application of ele DC furnace.

For each technological process, the relative position of the groups of electrodes of different polarity, the number of electrodes in the group, the dimensions and design features of the furnace body, electrodes and non-conductive partitions, including how to attach the latter to the furnace body and their cooling, and other parameters, are determined experimentally and calculated based on conditions the maximum total economic effect from the extraction of valuable components of technogenic raw materials, which is the subject of know-how for the claimed invention.

The essence of the invention is illustrated in the drawing, which shows the inventive electric furnace for processing of technogenic raw materials. The furnace contains a lined casing 1, loading devices 2, electrodes 3, of which one group 4 is mounted on the bottom 6 of the protective plate 5, which is sealed as a result of preliminary slagging of the new furnace and is connected to one pole of the current source, for example, to the positive, and the other group of electrodes 7 is connected to the other pole, for example to the negative. The potential for the electrodes is supplied through the contact cheeks 8 of the power source. The ends of the electrodes of group 4 are immersed in a layer of metal or matte 9 on the bottom of the furnace, and the electrodes of group 7 are immersed in the melt 10 of the processed technogenic raw materials. Between the electrodes of different polarity, vertical partitions 11 are installed, made of non-conductive material, for example, XM refractory, crossing the layer of light metal 12. Partitions 11, the lower part of which is immersed in the melt 10, are mounted on the side walls 13 of the furnace.

The furnace operates as follows.

After the melt 10 of the processed technogenic raw material has been set, a direct current voltage is applied to the electrodes through the contact jaws 8, the value of which is regulated and selected in such a way as to ensure that the sealing cover 5 is maintained at the bottom 6 of the hearth and to prevent excessive lay formation that impedes normal operation of the furnace. With this slag composition, this determines the position of the group 7 electrodes in the furnace working space vertically. A reducing agent, for example coke, is charged into the bath, which helps to restore metals from oxides chemically. In the steady state, an electric current between the electrodes 4 and the electrodes 7 flows through the melt 10 mainly along the following path: electrodes 4 - a layer of metal or matte 9 - electrodes 7.

Chemically reduced metal (or matte) accumulates in the molten state in layer 9. In this case, light metals accumulate on the surface of melt 10, forming layer 12. Part of the reduced metal remains in the melt in a chemically dissolved state and in the form of a mechanical suspension.

When direct current flows through melt 10 of the processed technogenic raw materials, it becomes depleted, on the one hand, due to the electrolytic release of metal from a chemical solution, and on the other, as a result of the directed action of an electric field on charged drops of metal (or matte) and their transfer to one of electrodes.

Fixed on the side walls 13 of the furnace, vertical partitions 11 made of a dielectric, the lower part of which is immersed in the melt 10, intersect the layer of light metal 12 that accumulates on the surface of the melt 10, and thereby avoid short circuiting of the system, which may occur due to leakage through the layer 12 short-circuit currents and lead to failure of the entire system.

The device was tested on a six-electrode closed rectangular depletion furnace with a rated power of 250 kVA with electrodes with a diameter of 100 mm located along the long axis of the bath. On the side walls of the furnace there are fixed vertical partitions made of water-cooled caissons with a refractory coating of chromomagnesite, having dimensions of 700 × 200 × 70 mm; the lower part of the partitions is immersed in the melt of the processed technogenic raw materials. Converter slag of the composition was subjected to processing, wt.%: Copper - 5.8; lead - 3.8; zinc - 4.1; iron - 29.0; silicon dioxide - 29.9; calcium oxide - 8.5; the rest is oxygen and others, as well as crushed piston aluminum scrap containing 98% metals.

The duration of the furnace was 48 hours.

As a result of melting was obtained:

matte composition, wt.%: copper - 52.2; lead - 5.0; zinc - 1.3; iron - 20.1;

alloy composition, wt.%: copper - 1,67; silicon - 10.2; iron - 0.63; zinc - 0, 38; magnesium - 0.59; Manganese - 0.26; the rest is aluminum;

dump slag composition, wt.%: copper - 0.43; lead - 0.55; zinc - 1.6; iron - 27.0; silicon dioxide - 35.2; calcium oxide - 10.2, the rest is oxygen and others.

The tests carried out confirmed the optimality and high reliability of the claimed design of the furnace, which allows to process materials containing both heavy and light metals.

Claims (1)

An electric furnace for processing technogenic raw materials, including a housing with side walls, loading devices, electrodes combined into groups, one of which is mounted on the bottom of the furnace and connected to one pole of the current source, and the other group is immersed in the melt of the processed raw materials and connected to the opposite pole of the source current, while electrodes of different polarity are installed through one, characterized in that between the electrodes of different polarity there are installed vertical barriers fixed to the side walls of the furnace ki made of non-conductive material and immersed in the melt of processed raw materials.