CA1145806A - Electric installation for heating of molten metals and/or salts and solutions - Google Patents
Electric installation for heating of molten metals and/or salts and solutionsInfo
- Publication number
- CA1145806A CA1145806A CA000355138A CA355138A CA1145806A CA 1145806 A CA1145806 A CA 1145806A CA 000355138 A CA000355138 A CA 000355138A CA 355138 A CA355138 A CA 355138A CA 1145806 A CA1145806 A CA 1145806A
- Authority
- CA
- Canada
- Prior art keywords
- heating element
- bath
- electric installation
- installation according
- contact
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Resistance Heating (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Electric installation for direct heating of a charge, such as a bath of metals and/or salts in melted state and solutions, comprising: at least one heating element for heating the charge, each heating element being in the form of a vessel or partition made of at least two parts of different physico-chemical properties, these parts being firmly joined to each other and having a portion immersed in the heated bath. Contact materials are in contact with a first surface of the heating element, a first electrode is dipped at least partially into the con-tact materials, and means are provided for applying an electric potential difference between the electrode and a second electrode located at least partially in the bath.
An electric circuit is connected to the heating element and includes current supply means to the electrodes. The bath is in contact with a second surface of the heating element, and the contact materials are included in the electric circuit of the heating element.
Electric installation for direct heating of a charge, such as a bath of metals and/or salts in melted state and solutions, comprising: at least one heating element for heating the charge, each heating element being in the form of a vessel or partition made of at least two parts of different physico-chemical properties, these parts being firmly joined to each other and having a portion immersed in the heated bath. Contact materials are in contact with a first surface of the heating element, a first electrode is dipped at least partially into the con-tact materials, and means are provided for applying an electric potential difference between the electrode and a second electrode located at least partially in the bath.
An electric circuit is connected to the heating element and includes current supply means to the electrodes. The bath is in contact with a second surface of the heating element, and the contact materials are included in the electric circuit of the heating element.
Description
The present invention relates to an electric installation for a charge such as a bath of metals and/or salts in melted state and solutions.
The electric heating installations so far known, wherein the heat generated in the heating elements is transmitted directly to the bath, are provided with heating elements as in the Polish Patent Nr 81,320 in the shape of one or several partitions located preferably parallel to the electrodes situated either in the bottom or in the walls of the melting tank. The partitions are built pref-erably of a uniform plate of ceramic materials and divide the melting bath in two or more parts, or they are built in the walls or bottom of the melting tank and at least their one surface is in contact with the metallic bath or, as in the Polish Patent Nr 106,380, said partitions are provided with heating elements shaped as a vessel situated in the furnace chamber and the current supply units are situated inside the vessel shaped as an electrode, preferably a graphite one, and the melted metal adheres to the bottom and walls of the heating element.
The drawbacks of known electric heating installa-tions is their limited range of application, they are used mainly for non-ferrous metals, a relatively low power carrying capacity and a short service-life of the heating elements because of the destructive effect of thermal stresses arising in heating elements, a poor utilization of heating element surfaces due the variable submersion depth of the heating elements, short life of electrodes and current supplies to heating elements caused by direct in-fluence of the charge and atmosphere in the installation aswell as a very difficult start-up of the equipment from a cold state because of a rather poor contact of the heating elements with the solid charge.
The aim of this invention is to eliminate the ~ ' ~
above mentioned drawbacks or reduce their effects.
According to the present invention, there is provided an electric installation for direct heating of a charge, such as a bath of metals and/or salts in melted state and solutions, comprising: at least one heating element for heating the charge, each heating element being in the form of a vessel or partition made of at least two parts of different physico-chemical properties, said parts being firmly joined to each other and having a portion immersed in the heated bath, ~ontact materials being in contact with a first surface of said heating element, a first electrode dipped at least partially into said contact materials, means for appiying an electric potential differ-ence between said electrode and a second electrode located at least partially in the bath, an electric circuit con- -nected to said heating element and including current supply means to said electrodes, said bath being in contact with a second surface o said heating element, said contact materials being included in said electric circuit of said heating element.
The aim of the present invention is achieved, among others, by the application of a suitable shape and manufacturing method of heating elements, by series or series-parallel and also double series connections of con-tact materials into the heating element circuit, and byincreasing the electrically active area of heating elements - in using contact materials.
The Electric installation of the present invention can further present at least one of several of the following features.
The heating element can consist of two vessels partly dipped in the bath being heated, one of - these vessels being situated inside the other one and the space between both the vessels, as well as the inside of the
The electric heating installations so far known, wherein the heat generated in the heating elements is transmitted directly to the bath, are provided with heating elements as in the Polish Patent Nr 81,320 in the shape of one or several partitions located preferably parallel to the electrodes situated either in the bottom or in the walls of the melting tank. The partitions are built pref-erably of a uniform plate of ceramic materials and divide the melting bath in two or more parts, or they are built in the walls or bottom of the melting tank and at least their one surface is in contact with the metallic bath or, as in the Polish Patent Nr 106,380, said partitions are provided with heating elements shaped as a vessel situated in the furnace chamber and the current supply units are situated inside the vessel shaped as an electrode, preferably a graphite one, and the melted metal adheres to the bottom and walls of the heating element.
The drawbacks of known electric heating installa-tions is their limited range of application, they are used mainly for non-ferrous metals, a relatively low power carrying capacity and a short service-life of the heating elements because of the destructive effect of thermal stresses arising in heating elements, a poor utilization of heating element surfaces due the variable submersion depth of the heating elements, short life of electrodes and current supplies to heating elements caused by direct in-fluence of the charge and atmosphere in the installation aswell as a very difficult start-up of the equipment from a cold state because of a rather poor contact of the heating elements with the solid charge.
The aim of this invention is to eliminate the ~ ' ~
above mentioned drawbacks or reduce their effects.
According to the present invention, there is provided an electric installation for direct heating of a charge, such as a bath of metals and/or salts in melted state and solutions, comprising: at least one heating element for heating the charge, each heating element being in the form of a vessel or partition made of at least two parts of different physico-chemical properties, said parts being firmly joined to each other and having a portion immersed in the heated bath, ~ontact materials being in contact with a first surface of said heating element, a first electrode dipped at least partially into said contact materials, means for appiying an electric potential differ-ence between said electrode and a second electrode located at least partially in the bath, an electric circuit con- -nected to said heating element and including current supply means to said electrodes, said bath being in contact with a second surface o said heating element, said contact materials being included in said electric circuit of said heating element.
The aim of the present invention is achieved, among others, by the application of a suitable shape and manufacturing method of heating elements, by series or series-parallel and also double series connections of con-tact materials into the heating element circuit, and byincreasing the electrically active area of heating elements - in using contact materials.
The Electric installation of the present invention can further present at least one of several of the following features.
The heating element can consist of two vessels partly dipped in the bath being heated, one of - these vessels being situated inside the other one and the space between both the vessels, as well as the inside of the
- 2 -first vessel, being partly filled with contact materials.
The heating element can also be made in the - shape of a solid or solids located in the limiting ring, preferably made of a ceramic materiaIs, the said solid or soIids being partly dipped in the bath being heated and covered with a layer of contact material, preferabLy melted salt of a-density not exceeding the density of the bath being heated and the heating element.
The said /
/ .
' - 2a -~ .
11'~5806 heating element can also be made in the shape of a solid or solids situated in a limiting ring, preferably made of a ceramic material, the said solid or solids being partly dipped in the bath being heated and covered with a layer of contact material, preferably the molten metal separated from the level of the bath being heated by another layer of contact material, preferably melted salt.
The heating element in a shape of a tube can also be partly dipped in the bath being heated, one end of the tube being tightly fixed in the bottom of the chamber of the heated bath of a preferably tiltable arrangement.
The heating element can also have the shape of a double vessel consisting of two single heating elements, connected in a series partly dipped in the heated bath and mounted at the top edge of the wall parting the bath being heated into two parts insulated galvanically from each other, the electric potential difference being applied to the heated bath on both sides of the partition wall.
The heating element can also be made in a shape of a tube and partly dipped in the bath being heated and an electrode mounted inside the said acts simultaneously as the contact materials.
The heating elements are preferably made of sintered materials of resistivity at working temperatures below lOOQ~ preferably within the limits from 0.001 to 2.5 Q~ and porosity from 0 up to 30 per cent. The electrodes are made of materials of a resistivity at least 10 ~ten) times lower than the resistivily of the material of the heating elements.
Contact materials are current conducting materials with resistivity below 200Q~. The heating elements in the shape of a vessel or partitions have an arbitrary cross section, and the height of the said heating elements is up to 2 metres, the wall thickness of the vessels or partitions up to 0.2 ,.
1~5806 metres, and the electrically active area up to 2 sq.m.
The heating elements are made of a homogenous material as a single shape or several shapes permanently combined together. The faces of the said heating elements can also be partly covered with a material resistant to the chemical action of the charge, or the contact materials, the advan-tageous thickness of the said covering layer is within 0.1 up to 3 mm.
The heating elements can also be saturated with substances dimini-shing the porosity of the material of the heating elements.
The heating element having the shape of a vessel can also freely float in the bath being heated.
The heating element can also float in the bath being heated with a forced immersion caused by a weight. The external weight of the heating element can also be adapted for introduction of protective gas to the inside of the said heating element. It can also be provided with an auxiliary resistance heater mounted in direct proximity to the edges of the heating elements projecting from the bath and included in the electric circuit of the heating element.
The heating element can also be immersed in the bath being heated and fastened to a movable suspension enabling a steady immersion depth of the heating elements at varying level of the bath being heated.
The heating element can also be partly dipped in the bath being heated and permanently fastened to the structure of the heating installation, preferably a tiltable one.
Electrodes connected by means of current supply means to one pole of a current source are immersed in the heated bath whereas electrodes connected by means of current supply means to the second pole of the current source are partly dipped in contact materials in the heating element.
`"` 1145806 Supply voltage for the heating elements is adjustable and the bath being heated is grounded, starting the heating installation from a cold state and using the charge in solid state is performed either by an additional heater kept operating until the first portion of the charge is melted, or by means of the main heating elements supported on the solid charge, while the surfaces of the heating elements are in contact with the charge and electrode via some additional contact materials, preferably having a paste consistency.
Advantages of the invention, besides others, are the following:
a wide range of application, particularly for heating molten metals, salts and sol.utions as well as melting the metals and salts, a large load-carrying capacity of the heating elements due to application in the given process engineering the adequately shaped and suitably manufactured heating elements, the correct immersion of heating elements in the heated bath, the series-parallel or series connection of contact materials with the circuit of the heating elementJ heating of edges of heating elements protruding out of the heated bath, materials suitable for the given process engineering used for manu-facturing the heating elements and contact materialsJ increased electrically active area of heating elements by placing one heating element inside another heating element and adequate current source for the used process, long service-life of electrodes and current supply means as a result of using adequate materials or protective atmospheres, elimination of upper current supply means as a result of application of heating elements in the shape of a double vessel, startability of installation from a cold state due to improvement of contacts of ~eating elements with the solid charge by additional contact materials preferably of a paste-like consistency and simple design and operation of installation as a result of applying many methods of installing the heating elements, electrodes and current supply . ., means, easy replacement of heating elements without switching off the install-ation operations.
The invention will now be further described in conjunction with the accompanying drawings, in which:
Figure 1 is a cross-sectional view of an installation according to the invention, Figures 2to 8 illustrate the shapes and manufacturing methods of the heating elements, and Figures 9 to 14 are diagrams illustrating the methods of installing the heating elements and electrodes in the heated bath.
An example of an embodiment of the equipment according to the invention, shown in Figure 1, consists of ceramic walls 1 which, together with the bottom 2, form chamber 3 of the installation. Wall 4 divides chamber 3 into a settling chamber and melting chamber. Chamber 3 is partly filled with metal 5 in a molten state.
In metal 5 there are two heating elements 7 suspended on a float ; 6 having the shape of vessels partly filled with molten metal 8 and molten salt 9, serving as contact materials between the iron electrode 10 dipped in the molten salt 9 and one surface of the heating element 7. In the bottom 2 of the chamber 3 there is a gr~phite electrode 11 installed in such a way that one of its ends is connected to the structure of the installation whereas the second one is in contact with the second surface of the heating element 7.
Electric current flows from electrode 10 through the molten salt 9, molten metal 8, walls of the heating element 7, and metal 5 to the electrode 11 under the influence of the voltage differences applied via a current supplier to electrode 10 and current supplier 13 to electrode 11.
A ring 14 made of aluminosilicate is mounted by means of sintering to the upper edges of the heating element 7. The heating element 7 is made of a nitrided silicon carbide. The outer and inner faces of the heating element 7 are covered with a thin layer 15 of a carbon paste, Metals 8 and 5 are aluminium, salt 9 is a mixture of ca-lcium chloride and sodium chloride and the float 6 is made of light kaolin.
The installation according to above described embodiment of the invention operates in the following way. Upon preheating of chamber 3 of the installation by means of an additional heater and filling the chamber partly with molten metal 5, heating elements 7 filled with molten metal 8 and molten salt 9 are immersed in the metal bath 5, installing simultaneously electrodes 10 and current suppliers 12. To a current supply means 12 and 13 is applied a three-phase alternating voltage and the R-phase voltage is appiied to the first heating element 7, whereas the S-phase is supplied to the second heating element 7.
As a result of the applied voltages, the electric current flowing through the walls of the heating element 7 and the layer of melted salt 9 generates heat transmitted to the metal bath 5. A solid charge to be melted is introduccd to the said metal bath 5.
On completion of the metal melting process and its settling the installation is emptied partly by being tilted, or by being pumped or, finally, by tapping the metal through a tap hole situatcd either in the bottom, or in the wall of the chamber 3.
The start-up of the installation from a cold state in case of a solid ch3rgo is performcd hy mcalls of all addition~l hc3tor opcrating until thc first batcll of cllarge is moltcn, or by mcans o~ llc~tinu clcmcllts 7, placcd on the solid ch~rge, the surfaces of he~ting elcmcnts 7 hereby adhcr-~145806 ing to the charge 5 and metal 8 by means of a carbon paste, electrodc 10 con-tacts metal 8 through salt 9 and electrode 11 the charge 5.
Figures 2 to 8 illustrate the shapes and manufacture of the heating elements 7 of the installation according to the invention. Figures 2 to 5 are drawings presenting the heating elements 7 made of a homogcnous material as uniform shape.
Figure 6 shows a heating element 7 to the top edge of which a ring 14 made of aluminosilicate is fixed by sintering.
The drawing on Figure 7 shows the heating element 7 made of two shapes 16 and 17 connected together by sintering, wherein the electric con-ductivity of the material of shape 17 is lower than of shape 16.
Figure 8 illustrates a heating element 7 made from three shapes connected together by sintering.
In Figures 9 to 14 are presented various locations o the heating elements 7 of the installation, according to this invention.
Figure 9 presents two heating elements in the shape of a vessel floating due to a forced immersion caused by the weight 18, in metal 5 where-by one heating element 7 is placed in the second heating element 7 and the space between the heating elements 7 and the inside of the first heating element 7 is filled partly with metal 8.
Metals 8 and 5 are zinc, electrodes 10 and 11 are made of graphite, weight 18 is made of a cement-fireclay material reinforced with iron bars and the heating elements 7 are made of nitridedsilicon carbide.
Figure 10 shows four heating elements 7 in the form of a rectangular prism floating freely in metal 5 in a limiting ring 19 covered with a layer of meltcd salt 9.
In consequence of a potential diffcrence applied to the elcctrodes ,~
11~$8()6 10 and 11, electric current flows from the electrode 10 in parallel through the salt 9 and heating elements 7 to metal 5, and then to electrode 11.
Metal 5 is a zine and aluminium alloy, salt 9 is a mixture of calcium chloride and sodium chloride, electrode 10 is made of iron, electrode 11 is made of graphite, limiting ring 1 is made of fireclay, whereas the heating element 7 is made of nitrided silicon carbide.
The start-up of the installation from a cold state is carried out by means of the heating elements 7 placed on the solid charge 5, the surfaces of the heating elements 7 adhering to the charge 5 and to electrode 10 by means of a carbon paste and the electrode 11 being in contact with the charge 5. During the start-up nitrogen is metered to the chamber 3 in order to pTOteCt the carbon paste against oxidation. After the charge 5 is molten contact material 9 is introduced to the limiting ring 19.
Figure 11 shows three heating elements 7, in the shape of a rectangular prism floating freely in metal 5 in the limiting ring 19. The heating elements 7 are covered with a layer of metal 9 separated from the free surface of metal 5 by a layer of molten salt 8 whereby the layer of the molten salt 8 is below the upper edges of the heating elements 7.
In consequence of a potentiai difference applied to electrodes 10 and 11, electric current flows from electrode 10 through metal 9 in parallel through salt 8 and heating elements 7 to metal 5, and therefrom to electrode 11. Metal 9 is an aluminium alloy, metal 5 is aluminium bronze, electrodes 10 and 11 are made of graphite coated with silicon carbide brought from gaseous phase, salt 8 is a mixture of sodium carbonate and sodium chloride, heating elements 7 are made of nitrided silicon carbide and the limiting ring 1 is made of a fireclay material.
Figure 12 illustrates a heating element 7 in the shape of a 11~5806 tapered tube movably suspended in the molten salt 5 by means of a grip 20 and cable 21 to the body of the installation so as to obtain a steady draft of the heating element 7 independently of the level of the salt bath 5.
Electrode 10 connected to the current supply means 12 is in direct contact with one surface of the said heating element 7. The tapered portion of the said electrode 10 serves simultaneously as contact material. The outer sur-face of the heating element 7 is coated with a thin layer of material 15.
Because of the potential difference applied to the electrodes 10 and 11, the electric current flows from electrode 10 parallel to the heating element 7 and electrode 10 to salt 5 and therefrom to electrode 11. Salt 5 is a mixture of barium chloride and calcium chloride, material lS is silicon carbide obtained from the gaseous phase, electrode 10 is made of sintered silicon carbide by reaction and electrode 11 is made of graphite coated with a thin layer of silicon carbide obtained from the gaseous phase, the grip 20 and cable 21 are made of alloy steel, and the heating element 7 is made of nitrided silicon carbide.
Figure 13 shows a heating element 7 in the shape of a vessel immers-ed in a water solution 5 of sulphuric acid and suspende~ on a float 6, the inside of the said heating element 7 being filled with a metal 8. The external faces-of the said heating element 7 are coated with a thin layer of material 15. Metal 8 is a Wood alloy, the float 6 is made of polyethylene, electrode 10 is made of graphite, electrode 11 is made of acid resistant steel, float 22 is made of graphite, and the heating element 7 is made of sintered material on a graphite base, layer 15 is silicon carbide obtained from the gaseous phase.
Figure 14 shows a heating element 7 in the shape of double vessel partly dipped in metal 5 and partly filled with metal 8; the wall 23 divides 11~5806 the bath 5 into two equal parts insulated from each other. Electric current flows from electrode 10 through metal 5,,walls of the heating element 7, and metal 5 to electrode 11 under the effect of the potential difference applied to the electrode 10 connected to the current supply means 12 and to electrode 11 connected by the current supply means 13. The heating element 7 is made of a sintered material on the basis of zirconium oxide, metals 8 and 5 are molten steel, electrodes 10 and 11 are made of graphite and wall 23 is made of a material on the basis of corundum.
The heating element can also be made in the - shape of a solid or solids located in the limiting ring, preferably made of a ceramic materiaIs, the said solid or soIids being partly dipped in the bath being heated and covered with a layer of contact material, preferabLy melted salt of a-density not exceeding the density of the bath being heated and the heating element.
The said /
/ .
' - 2a -~ .
11'~5806 heating element can also be made in the shape of a solid or solids situated in a limiting ring, preferably made of a ceramic material, the said solid or solids being partly dipped in the bath being heated and covered with a layer of contact material, preferably the molten metal separated from the level of the bath being heated by another layer of contact material, preferably melted salt.
The heating element in a shape of a tube can also be partly dipped in the bath being heated, one end of the tube being tightly fixed in the bottom of the chamber of the heated bath of a preferably tiltable arrangement.
The heating element can also have the shape of a double vessel consisting of two single heating elements, connected in a series partly dipped in the heated bath and mounted at the top edge of the wall parting the bath being heated into two parts insulated galvanically from each other, the electric potential difference being applied to the heated bath on both sides of the partition wall.
The heating element can also be made in a shape of a tube and partly dipped in the bath being heated and an electrode mounted inside the said acts simultaneously as the contact materials.
The heating elements are preferably made of sintered materials of resistivity at working temperatures below lOOQ~ preferably within the limits from 0.001 to 2.5 Q~ and porosity from 0 up to 30 per cent. The electrodes are made of materials of a resistivity at least 10 ~ten) times lower than the resistivily of the material of the heating elements.
Contact materials are current conducting materials with resistivity below 200Q~. The heating elements in the shape of a vessel or partitions have an arbitrary cross section, and the height of the said heating elements is up to 2 metres, the wall thickness of the vessels or partitions up to 0.2 ,.
1~5806 metres, and the electrically active area up to 2 sq.m.
The heating elements are made of a homogenous material as a single shape or several shapes permanently combined together. The faces of the said heating elements can also be partly covered with a material resistant to the chemical action of the charge, or the contact materials, the advan-tageous thickness of the said covering layer is within 0.1 up to 3 mm.
The heating elements can also be saturated with substances dimini-shing the porosity of the material of the heating elements.
The heating element having the shape of a vessel can also freely float in the bath being heated.
The heating element can also float in the bath being heated with a forced immersion caused by a weight. The external weight of the heating element can also be adapted for introduction of protective gas to the inside of the said heating element. It can also be provided with an auxiliary resistance heater mounted in direct proximity to the edges of the heating elements projecting from the bath and included in the electric circuit of the heating element.
The heating element can also be immersed in the bath being heated and fastened to a movable suspension enabling a steady immersion depth of the heating elements at varying level of the bath being heated.
The heating element can also be partly dipped in the bath being heated and permanently fastened to the structure of the heating installation, preferably a tiltable one.
Electrodes connected by means of current supply means to one pole of a current source are immersed in the heated bath whereas electrodes connected by means of current supply means to the second pole of the current source are partly dipped in contact materials in the heating element.
`"` 1145806 Supply voltage for the heating elements is adjustable and the bath being heated is grounded, starting the heating installation from a cold state and using the charge in solid state is performed either by an additional heater kept operating until the first portion of the charge is melted, or by means of the main heating elements supported on the solid charge, while the surfaces of the heating elements are in contact with the charge and electrode via some additional contact materials, preferably having a paste consistency.
Advantages of the invention, besides others, are the following:
a wide range of application, particularly for heating molten metals, salts and sol.utions as well as melting the metals and salts, a large load-carrying capacity of the heating elements due to application in the given process engineering the adequately shaped and suitably manufactured heating elements, the correct immersion of heating elements in the heated bath, the series-parallel or series connection of contact materials with the circuit of the heating elementJ heating of edges of heating elements protruding out of the heated bath, materials suitable for the given process engineering used for manu-facturing the heating elements and contact materialsJ increased electrically active area of heating elements by placing one heating element inside another heating element and adequate current source for the used process, long service-life of electrodes and current supply means as a result of using adequate materials or protective atmospheres, elimination of upper current supply means as a result of application of heating elements in the shape of a double vessel, startability of installation from a cold state due to improvement of contacts of ~eating elements with the solid charge by additional contact materials preferably of a paste-like consistency and simple design and operation of installation as a result of applying many methods of installing the heating elements, electrodes and current supply . ., means, easy replacement of heating elements without switching off the install-ation operations.
The invention will now be further described in conjunction with the accompanying drawings, in which:
Figure 1 is a cross-sectional view of an installation according to the invention, Figures 2to 8 illustrate the shapes and manufacturing methods of the heating elements, and Figures 9 to 14 are diagrams illustrating the methods of installing the heating elements and electrodes in the heated bath.
An example of an embodiment of the equipment according to the invention, shown in Figure 1, consists of ceramic walls 1 which, together with the bottom 2, form chamber 3 of the installation. Wall 4 divides chamber 3 into a settling chamber and melting chamber. Chamber 3 is partly filled with metal 5 in a molten state.
In metal 5 there are two heating elements 7 suspended on a float ; 6 having the shape of vessels partly filled with molten metal 8 and molten salt 9, serving as contact materials between the iron electrode 10 dipped in the molten salt 9 and one surface of the heating element 7. In the bottom 2 of the chamber 3 there is a gr~phite electrode 11 installed in such a way that one of its ends is connected to the structure of the installation whereas the second one is in contact with the second surface of the heating element 7.
Electric current flows from electrode 10 through the molten salt 9, molten metal 8, walls of the heating element 7, and metal 5 to the electrode 11 under the influence of the voltage differences applied via a current supplier to electrode 10 and current supplier 13 to electrode 11.
A ring 14 made of aluminosilicate is mounted by means of sintering to the upper edges of the heating element 7. The heating element 7 is made of a nitrided silicon carbide. The outer and inner faces of the heating element 7 are covered with a thin layer 15 of a carbon paste, Metals 8 and 5 are aluminium, salt 9 is a mixture of ca-lcium chloride and sodium chloride and the float 6 is made of light kaolin.
The installation according to above described embodiment of the invention operates in the following way. Upon preheating of chamber 3 of the installation by means of an additional heater and filling the chamber partly with molten metal 5, heating elements 7 filled with molten metal 8 and molten salt 9 are immersed in the metal bath 5, installing simultaneously electrodes 10 and current suppliers 12. To a current supply means 12 and 13 is applied a three-phase alternating voltage and the R-phase voltage is appiied to the first heating element 7, whereas the S-phase is supplied to the second heating element 7.
As a result of the applied voltages, the electric current flowing through the walls of the heating element 7 and the layer of melted salt 9 generates heat transmitted to the metal bath 5. A solid charge to be melted is introduccd to the said metal bath 5.
On completion of the metal melting process and its settling the installation is emptied partly by being tilted, or by being pumped or, finally, by tapping the metal through a tap hole situatcd either in the bottom, or in the wall of the chamber 3.
The start-up of the installation from a cold state in case of a solid ch3rgo is performcd hy mcalls of all addition~l hc3tor opcrating until thc first batcll of cllarge is moltcn, or by mcans o~ llc~tinu clcmcllts 7, placcd on the solid ch~rge, the surfaces of he~ting elcmcnts 7 hereby adhcr-~145806 ing to the charge 5 and metal 8 by means of a carbon paste, electrodc 10 con-tacts metal 8 through salt 9 and electrode 11 the charge 5.
Figures 2 to 8 illustrate the shapes and manufacture of the heating elements 7 of the installation according to the invention. Figures 2 to 5 are drawings presenting the heating elements 7 made of a homogcnous material as uniform shape.
Figure 6 shows a heating element 7 to the top edge of which a ring 14 made of aluminosilicate is fixed by sintering.
The drawing on Figure 7 shows the heating element 7 made of two shapes 16 and 17 connected together by sintering, wherein the electric con-ductivity of the material of shape 17 is lower than of shape 16.
Figure 8 illustrates a heating element 7 made from three shapes connected together by sintering.
In Figures 9 to 14 are presented various locations o the heating elements 7 of the installation, according to this invention.
Figure 9 presents two heating elements in the shape of a vessel floating due to a forced immersion caused by the weight 18, in metal 5 where-by one heating element 7 is placed in the second heating element 7 and the space between the heating elements 7 and the inside of the first heating element 7 is filled partly with metal 8.
Metals 8 and 5 are zinc, electrodes 10 and 11 are made of graphite, weight 18 is made of a cement-fireclay material reinforced with iron bars and the heating elements 7 are made of nitridedsilicon carbide.
Figure 10 shows four heating elements 7 in the form of a rectangular prism floating freely in metal 5 in a limiting ring 19 covered with a layer of meltcd salt 9.
In consequence of a potential diffcrence applied to the elcctrodes ,~
11~$8()6 10 and 11, electric current flows from the electrode 10 in parallel through the salt 9 and heating elements 7 to metal 5, and then to electrode 11.
Metal 5 is a zine and aluminium alloy, salt 9 is a mixture of calcium chloride and sodium chloride, electrode 10 is made of iron, electrode 11 is made of graphite, limiting ring 1 is made of fireclay, whereas the heating element 7 is made of nitrided silicon carbide.
The start-up of the installation from a cold state is carried out by means of the heating elements 7 placed on the solid charge 5, the surfaces of the heating elements 7 adhering to the charge 5 and to electrode 10 by means of a carbon paste and the electrode 11 being in contact with the charge 5. During the start-up nitrogen is metered to the chamber 3 in order to pTOteCt the carbon paste against oxidation. After the charge 5 is molten contact material 9 is introduced to the limiting ring 19.
Figure 11 shows three heating elements 7, in the shape of a rectangular prism floating freely in metal 5 in the limiting ring 19. The heating elements 7 are covered with a layer of metal 9 separated from the free surface of metal 5 by a layer of molten salt 8 whereby the layer of the molten salt 8 is below the upper edges of the heating elements 7.
In consequence of a potentiai difference applied to electrodes 10 and 11, electric current flows from electrode 10 through metal 9 in parallel through salt 8 and heating elements 7 to metal 5, and therefrom to electrode 11. Metal 9 is an aluminium alloy, metal 5 is aluminium bronze, electrodes 10 and 11 are made of graphite coated with silicon carbide brought from gaseous phase, salt 8 is a mixture of sodium carbonate and sodium chloride, heating elements 7 are made of nitrided silicon carbide and the limiting ring 1 is made of a fireclay material.
Figure 12 illustrates a heating element 7 in the shape of a 11~5806 tapered tube movably suspended in the molten salt 5 by means of a grip 20 and cable 21 to the body of the installation so as to obtain a steady draft of the heating element 7 independently of the level of the salt bath 5.
Electrode 10 connected to the current supply means 12 is in direct contact with one surface of the said heating element 7. The tapered portion of the said electrode 10 serves simultaneously as contact material. The outer sur-face of the heating element 7 is coated with a thin layer of material 15.
Because of the potential difference applied to the electrodes 10 and 11, the electric current flows from electrode 10 parallel to the heating element 7 and electrode 10 to salt 5 and therefrom to electrode 11. Salt 5 is a mixture of barium chloride and calcium chloride, material lS is silicon carbide obtained from the gaseous phase, electrode 10 is made of sintered silicon carbide by reaction and electrode 11 is made of graphite coated with a thin layer of silicon carbide obtained from the gaseous phase, the grip 20 and cable 21 are made of alloy steel, and the heating element 7 is made of nitrided silicon carbide.
Figure 13 shows a heating element 7 in the shape of a vessel immers-ed in a water solution 5 of sulphuric acid and suspende~ on a float 6, the inside of the said heating element 7 being filled with a metal 8. The external faces-of the said heating element 7 are coated with a thin layer of material 15. Metal 8 is a Wood alloy, the float 6 is made of polyethylene, electrode 10 is made of graphite, electrode 11 is made of acid resistant steel, float 22 is made of graphite, and the heating element 7 is made of sintered material on a graphite base, layer 15 is silicon carbide obtained from the gaseous phase.
Figure 14 shows a heating element 7 in the shape of double vessel partly dipped in metal 5 and partly filled with metal 8; the wall 23 divides 11~5806 the bath 5 into two equal parts insulated from each other. Electric current flows from electrode 10 through metal 5,,walls of the heating element 7, and metal 5 to electrode 11 under the effect of the potential difference applied to the electrode 10 connected to the current supply means 12 and to electrode 11 connected by the current supply means 13. The heating element 7 is made of a sintered material on the basis of zirconium oxide, metals 8 and 5 are molten steel, electrodes 10 and 11 are made of graphite and wall 23 is made of a material on the basis of corundum.
Claims (26)
1. Electric installation for direct heating of a charge, such as a bath of metals and/or salts in melted state and solutions, comprising: at least one heating element for heating the charge, each heating element being in the form of a vessel or partition made of at least two parts of different physico-chemical properties, said parts being firmly joined to each other and having a portion immersed in the heated bath, contact materials being in contact with a first surface of said heating element, a first electrode dipped at least partially into said contact materials, means for applying an electric potential differ-ence between said electrode and a second electrode located at least partially in the bath, an electric circuit connected to said heating element and including current supply means to said electrodes, said bath being in contact with a second surface of said heating element, said contact materials being included in said electric circuit of said heating element.
2. Electric installation according to claim 1, wherein the heating element comprises two vessels and is partly immersed in the heated bath, one vessel being located inside the other and the space between both vessels, as well as the inside of said one vessel being partly filled with said contact materials.
3. Electric installation according to claim 1, wherein said heating element is in the shape of solid blocks situated in a limiting ring and is partly immersed in the heated bath, said solid block being covered with a layer of contact material of a density smaller than that of the heated bath and the heating element.
4. Electric installation according to claim 1, wherein said heating element is in the shape of a solid block situated in a limiting ring and is partly immersed in the heated bath and covered with a layer of contact material separated from the free surface of the bath by another layer of contact material.
5. Electric installation according to claim 1, wherein said heating element is in the shape of a tube partly immersed in the heated bath and wherein one end of said tube is tightly fixed to the bottom of a chamber con-fining the heated bath.
6. Electric installation according to claim 1, wherein said heating element is in the shape of a double vessel forming a series connection of two individual heating elements, is partly immersed in the heated bath, and is mounted to the upper edge of a wall dividing the heated bath into two parts isolated from each other, said electric potential difference applying means being operatively connected to the heated bath on both sides of the dividing wall.
7. Electric installation according to claim 1, wherein the heating element is in the shape of a tube partly immersed in the heated bath, one of said electrodes being located inside said tube and serving as contact materials.
8. Electric installation according to claim 1, wherein the heating element is made of a material of a resistivity at working temperature of the heated bath below 100.OMEGA.m.
9. Electric installation according to claim 1, 4 or 6, wherein said electrodes are made of materials of a resistivity at least ten times lower than the resistivity of the material of which said heating element is made.
10. Electric installation according to claim 1, 2 or 7, wherein said contact materials are current conduct-ing materials of a resistivity below 200.OMEGA.m.
11. Electric installation according to claim 1, wherein said heating element is in the shape of a vessel of an arbitrary cross section, the height of said heating element being up to 5 meters, the wall thickness of a wall confining the bath up to 0.2 meters, and the surfaces of said heating element being in size up to-2 square meters.
12. Electric installation according to claim 1, wherein the heating element is in the shape of a partition of an arbitrary cross section, the thickness of the said heating element being up to 0.2 meters and the surfaces up to 2 square meters.
13. Electric installation according to claim 1, wherein the heating element is made of a homogonous material and is a unitary element.
14. Electric installation according to claim 1, wherein the surfaces of the heating element are partly covered with layers of material resistant to chemical action of the charge and contact materials.
15. Electric installation according to claim 1, wherein the heating element is saturated with materials diminishing the porosity of the material of the heating element.
16. Electric installation according to claim 1, wherein the heating element is arranged in the heated bath so as to freely float therein.
17. Electric installation according to claim 1, wherein the heating element is arranged in the heated bath so as to float therein, a weight being provided to keep the heating element in a forced immersion.
18. Electric installation according to claim 17, wherein the weight of the heating element is adapted to introduce a protective gas into said heating element.
19. Electric installation according to claim 17, wherein the weight of the heating element is provided with an additional resistance heater mounted in direct proximity to the edges of the heating element protruding from the bath and included in the electric circuit of the heating element.
20. Electric installation according to claim 1, wherein the heating element is partly immersed in the bath and mounted to a movable suspension for maintaining a steady immersion depth of said heating element at the varying level of the bath.
21. Electric installation according to claim 1, wherein the heating element is partly immersed in the bath and fixedly mounted to a support element.
22. Electric installation according to claim 1, 4 or 6, wherein said second electrode is connected to one pole of a current source by means of said current supply means, and said first electrode is connected to the other pole of a current source by means of said current supply means.
23. Electric installation according to claim 1, 4 or 6, wherein the supply voltage of the heating element is adjustable and the bath is earthed.
24. Electric installation according to claim 1, comprising an additional heater for starting said installa-tion from its cold state when the charge is in solid form.
25. Electric installation according to claim 1, 2 or 7, wherein the start from the cold state of the installation, when the charge is in solid form, is per-formed by said heating element placed on the charge, the surfaces of said heating element being in contact with the charge and electrodes by means of additional contact materials.
26. Electric installation according to claim 1, wherein the surfaces of said heating element are partly covered with layers of material of high electrical and thermal conductivity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000355138A CA1145806A (en) | 1980-06-30 | 1980-06-30 | Electric installation for heating of molten metals and/or salts and solutions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000355138A CA1145806A (en) | 1980-06-30 | 1980-06-30 | Electric installation for heating of molten metals and/or salts and solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145806A true CA1145806A (en) | 1983-05-03 |
Family
ID=4117313
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000355138A Expired CA1145806A (en) | 1980-06-30 | 1980-06-30 | Electric installation for heating of molten metals and/or salts and solutions |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1145806A (en) |
-
1980
- 1980-06-30 CA CA000355138A patent/CA1145806A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2101392C1 (en) | Aluminum-producing electrolyzer, anode pack of electrolyzer, method of rearranging electrolyzer, and method of aluminum production | |
| US4071420A (en) | Electrolytic production of metal | |
| EP0852267B1 (en) | Fluorine cell | |
| US3930967A (en) | Process for the electrolysis of a molten charge using inconsumable bi-polar electrodes | |
| US4098651A (en) | Continuous measurement of electrolyte parameters in a cell for the electrolysis of a molten charge | |
| Palumbo et al. | High temperature solar electrothermal processing—III. Zinc from zinc oxide at 1200–1675K using a non-consumable anode | |
| US4247381A (en) | Facility for conducting electrical power to electrodes | |
| US4351057A (en) | Electric installation for heating of molten metals and/or salts and solutions | |
| Qingfeng et al. | Electrochemical Deposition of Aluminum from NaCl‐AlCl3 Melts | |
| RU2499085C1 (en) | Electrolysis unit for aluminium manufacture | |
| CA1145806A (en) | Electric installation for heating of molten metals and/or salts and solutions | |
| RU2679224C1 (en) | Thermochemical resistant anode for electrolysis of aluminum | |
| RU2553132C1 (en) | Design of current taps of cathode of aluminium electrolyser | |
| US4903277A (en) | Electric melting furnace with partitioned melting cavity for solidifying highly radioactive waste in glass | |
| GB1046705A (en) | Improvements in or relating to the operation of electrolytic reduction cells for theproduction of aluminium | |
| FI58977C (en) | FOERFARANDE FOER ATT SKYDDA FOER SMAELTUGNAR AVSEDDA METALLUPPHETTNINGSELEKTRODER UNDER ANVAENDNING AV LIKSTROEM OCH ANORDNING FOER TILLAEMPNING AV DETTA FOERFARANDE | |
| JPS5920484A (en) | Electrolytic tank for producing aluminum containing conductive float screen | |
| Li et al. | Electrochemical deposition of aluminum from NaCl-AlCl3 melts | |
| US3465085A (en) | Smelting electric furnace apparatus | |
| JPS5741393A (en) | Electrolytic furnace for production of aluminum | |
| CA1078902A (en) | Electric resistance furnace | |
| CS228131B2 (en) | Electric instalation for direct heating of melted metals and/or melted salts and solutions | |
| US2959527A (en) | Self-restoring anode in multi-cell furnaces particularly for the electrolytic production of aluminum | |
| US2062340A (en) | Means for and method of producing aluminum | |
| US3251754A (en) | Process and apparatus for improving the resistance of porous refractory materials to corrosive action |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |