RU2235256C1 - Technogenious raw material processing electric furnace - Google Patents

Abstract

FIELD: non-ferrous metallurgy.

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

EFFECT: improved reliability of operation 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 technogenic raw materials, including a housing with side walls, loading devices, electrodes combined in groups, one of which is mounted on the bottom of the furnace and connected to the negative pole of the current source, and the other group, the electrodes in which arranged in a row, immersed in the melt of processed raw materials and connected to the positive pole of the current source (RF patent No. 2088869, IPC F 27 V 3/08, C 22 V 7/04, publ. 08/27/97, BI No. 24).

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 mounted on the bottom of the furnace and connected to the negative pole of the current source, and the other group, the electrodes in which arranged in a row, immersed in the melt of the processed raw materials and connected to the positive pole of the current source, according to the claimed invention between electrodes of different polarity are installed vertical partitions replicated on the side walls of the furnace, made of non-conductive material and immersed in the melt of the processed 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, excludes the occurrence of short-circuit currents along the layer of light metal 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.

For each 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 the conditions of maximum the total economic effect of 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 by 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 the negative pole of the current source, and the other group of electrodes 7 is connected to the positive pole. The potential for the electrodes is supplied through the contact jaws 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 made, made of non-conductive material, for example, XM refractory, intersecting a 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 melt 10 in a chemically dissolved state and in the form of a mechanical suspension.

With the cathodic (negative) polarization of the electrodes 4 and, respectively, of the bottom phase 9 and the anodic (positive) polarization of the electrodes 7, oxygen will be released at the anodes, followed by its interaction with the carbon of the electrodes and the reducing agent and the formation of carbon monoxide, which additionally reduces non-ferrous metals from the slag.

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 of the processed technogenic raw materials, intersect the layer of light metal 12 that accumulates on the surface of the melt 10, and thereby avoid the short circuit of the system, which may occur due to 12 short-circuit currents flowing through the layer 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 molten material being processed. The processing was subjected to converter slag composition, 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 - 52.6; lead - 5.1; zinc - 1.0; iron - 20.3;

alloy composition, wt.%: copper - 1,66; silicon - 10.3; iron - 0.62; zinc - 0, 41; magnesium - 0.57; Manganese - 0.25; the rest is aluminum;

dump slag composition, wt.%: copper - 0.36; lead - 0.28; zinc - 0.48; iron - 26.4; silicon dioxide - 36.3; calcium oxide - 10.5, 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 case with side walls, loading devices, electrodes combined in groups, one of which is mounted on the bottom of the furnace and connected to the negative pole of the current source, and the other group, the electrodes in which are arranged in a row, is immersed in the melt of the processed raw material and connected to the positive pole of the current source, characterized in that between the electrodes of different polarity installed vertical partitions mounted on the side walls of the furnace, made f of non-conductive material and immersed in the melt of processed raw materials.