Electrolysis cell cathode
SUBSTANCE: cathode's top is turned towards the electrolytic bath, and the bottom has contacts for current input. Top and bottom parts, at least, on some sections are connected to each other in disconnectable manner using the protective interlayer.
EFFECT: lowering of the cathode cost and optimisation of the cathode operation.
10 cl, 5 dwg
The invention relates to a cathode for a cell of the electrolyzer to produce aluminium by electrolysis of molten environments.
For industrial production of aluminium from its oxide is currently used so-called way of the Hall-Heroult. In this case we are talking about the method of electrolysis, in which an aluminum oxide (Al2O3) is dissolved in molten cryolite (Na3[AlFe]), and the resulting mixture is used as a liquid electrolyte in the cell of the electrolyzer. The basic design of such a single cell of the cell to perform the method of Hall-Heroult schematically shown in figa-1C, figa shows a cross-section of normal cells, while at fig.1b cell is shown at the outside of the side view. On figs cell of the electrolyzer shown in isometric projection.
Reference position 1 is the cathode, which may be performed, for example, of graphite, anthracite coal, or a mixture thereof. As an alternative solution, you can also use graphite cathodes based on coke. The cathode 1 is usually mounted in a frame 2 made of steel and/or refractory material or the like. The cathode 1 can be implemented as a whole and of the individual cathode blocks.
The length of the cell in the cathode 1 is entered several current-carrying rods 3, in cross-section on figa is provided only a single current-carrying rod 3. On figs shown that each cathode unit can be provided, for example, two current-carrying rod 3. The current-carrying terminals are used to supply the cell current required for the electrolysis process. Opposite the cathode is several anodes 4, usually having the shape of a rectangular parallelepiped, with figs schematically shows two anode 4. Figure 1 shows in detail the arrangement of the anodes in the cell of the electrolyzer. When executing the method by application of voltage between the cathode 1 and the anode 4 aluminium oxide dissolved in cryolite, is decomposed by an electric current of ions of aluminum and oxygen, with the aluminum ions move to the molten aluminum from the electrochemical point of view to the cathode, with the purpose of reception of electrons. Due to the higher density aluminum 5 is collected in the liquid phase under a molten mixture of 6 consisting of alumina and cryolite. Oxygen ions are regenerated at the anode in the oxygen, which reacts with the carbon anodes.
Reference positions 7 and 8 schematically indicated by a negative, respectively, positive pole of a voltage source to provide the necessary in the process of electrolysis voltage, the value of which lies between about 3.5 and 5 Century
As shown in the side view on fig.1b, the frame 2 and thus all achak the electrolytic cell has an elongated shape, through the side walls of the frame 2 are perpendicular to numerous current-carrying rods 3. Typically, the longitudinal length of the currently used cell lies between about 8 and 15 m, while the width is approximately 3 to 4 meters of the Cathode, such as shown in figa, disclosed, for example, in EP 1845174.
In conventional cathode blocks essentially all components are made of just one material. However, this contradicts the fact that different parts of the cathode according to the method of electrolysis of molten environments have different requirements. So, in the area of the electrolytic bath or in the part of the cathode, which is in the specified way comes in contact with molten aluminum, loss of material due to wear of the cathode material, in particular, by chemical and mechanical processes during the electrolysis process, such as, for example, flow. So from time to time you need to update the cathode, that is, in this case, replace the entire lining cells of the electrolyzer. Typically, such a replacement perform every 1500-3000 days. In addition, the ratio of the optimal performance of separate components need to compromise, because the requirement of individual constituent parts of the partially compatible with each other. In addition, because of the frequent replacement of the entire material,as, for example, cathode blocks, the weight for stuffing, side framing and insulating material, it is necessary to renounce the use of high quality materials to prevent excessive increase in the cost of aluminium production.
Therefore the task of the invention is to provide a cathode for the cell electrolytic cell for obtaining aluminium, which can be overcome the above mentioned shortcomings of the prior art, with which, in particular, it is possible to reduce the cost of material and at the same time optimization of the cathode relative to the performance of its functions.
This task is solved according to the invention, by using a cathode with signs of paragraph 1 of the claims. Preferred embodiments of the specified in the dependent claims.
The cathode for the cell of the electrolyzer to produce aluminium from its oxide in an electrolytic bath has: (a) the upper part facing the electrolytic bath and (b) the lower part of which is provided with contacts for supplying current. In accordance with the invention, the upper part and the lower part at least in some areas Rethimno are connected to each other through the intermediate layer. The upper part is the tray, which, when used, is in direct contact with the electrolytic bath.
what he notion of "cathode" in the framework of the present invention is denoted by the upper part in connection with the lower part. According to the invention the term "cathode" refers collectively. This may be the case, for example, but not necessarily, about the so-called cathode bottom, which is made from a variety of cathode blocks, so that the main aspects of the invention, namely above the run from the upper part in connection with the lower part, is implemented in General this cathode bottom. However, the concept of the cathode extends to form the cathode bottom partial patterns, such as cathode blocks. All essential for the implementation of the invention, the attributes associated with the "cathode", also apply to the "cathode block, without mention of this in future.
On the basis of the execution of the cathode of the two parts, you can perform an optimization of the various functional areas in manufacturing. Thus, the upper part according to this method serves for receiving the liquid electrolyte, as well as the final product, namely molten aluminium.
The upper zone, which is called also spent part of the cathode should be relative to its design, perhaps more resistant to wear, such as wear due to mechanical, thermal and/or chemical load. On the grounds that top area in any case due to the consumption of the cathode material by electrolytic reaction must occasionally be replaced with aImost material for the upper part should be small. In contrast, the lower part of the cathode must be optimal relative to the supply voltage and current distribution. Based on this division into two parts, which is a sign of the present invention, it is possible both parts (top and bottom) to produce separately from each other, and then connected together by an intermediate layer. Thus, it is possible to optimize every part regarding its functioning, without having a negative impact on the functioning of the respective other part. For example, the lower part can be manufactured from better, more expensive, but less durable material, because it is not affected by wear, respectively, due to wear, replace the top. In General this results in a considerable saving of material cost, since in any case the replacement of the entire cathode, respectively, not all of the cathode blocks.
Another advantage of the invention is that the lower part can be protected by using the intermediate layer from the chemical effects of electrolytic baths. Thus, the intermediate layer not only provides the ability to separate the execution of the cathode of the lower part and upper part, but also helps to preserve the advantages of running the lower part of the high is chestvennogo material fact, what prevents the passage of corrosive fluids, penetrating down to the bottom, or gases such as, for example, molten aluminum or components of the electrolyte.
The intermediate layer, which connects the upper part with the lower part, can be manufactured, for example, from graphite film, in particular, may be a graphite film. Graphite film are particularly well suited to eliminate or at least maximize the prevention of the penetration of liquid and/or gaseous constituents of the bath, such as molten aluminum or components of the electrolyte in the inner part, while the function of the entire cathode does not change significantly. Graphite film as an intermediate layer has electrical properties similar to the properties of the constituent parts of the cathode, in particular the lower part. Graphite film, which is produced by at least partial sealing of the expanded graphite is based on its anisotropy in the film surface, and thus a very small permeability perpendicular to the film, especially suitable to perform the function of the separation layer relative to the chemical effects of the electrolytic bath. In addition, the graphite film compensates for differences in surface structure between the top is th part and a lower part, and also the movement of thermal expansion and contraction, in particular, the upper part. The graphite film has a low electrical contact resistance with other carbon-containing materials and very good electrical conductivity. Although the electrical resistivity perpendicular to the graphite film more than the film surface, it is possible on the basis of the very small thickness of the graphite film to achieve a very small absolute electrical resistance.
In case the cathode of a separate cathode blocks intermediate layer is preferably provided in accordance with the size of the cathode blocks, and preferably covers a greater surface than the corresponding lower part of the cathode blocks. The intermediate layer may preferably have a size that matches the size of the entire cathode.
The intermediate layer can perform very small thickness. For example, the layer may be only a single graphite film. It was found that a suitable film thickness is a thickness in the range between 1 mm and 5 mm, This thickness is sufficient to perform these functions, and, on the other hand, is thin enough to exclude a significant negative impact properties of the film on the functionality of the entire cathode.
Maybe t is the train the preferred use of multiple layered over each other graphite sheet or graphite films larger thickness. The intermediate layer can be performed at the request or, if necessary, with the corresponding specific electric conductivity and/or electrical contact resistance. This may be provided by the coating on the intermediate layer, which reduces the contact resistance. You can also purposefully to increase electrical conductivity of the graphite film in the thickness direction using known measures.
Suitable current supply inside the cathode is used, according to the prior art, to maintain possibly more uniform loss of material on the surface of the cathode within the cathode baths. Because in versions of the invention can be targeted to realize the optimization of a supply current to the lower part, the construction and accordingly manufacture the upper part can be simplified.
At the cathode according to the invention, the upper part can be manufactured as a single whole with the side wall of the cell of the electrolyzer. This means that the bottom wall and the side walls are designed as a single whole. Due to this excludes the problems of sealing and joining between the bottom wall and side walls.
Because the lower part of the cathode for use in a method of electrolysis of molten media does not come into contact with the liquid electrolyte, with the responsibility molten aluminum, the resistance relative to mechanical or chemical wear for this part is not the determining criterion. Thus, this part needs a little or even no maintenance and should not be replaced at regular intervals as is necessary for the upper part. Therefore, for the lower part, you can use higher quality materials. Such material is, for example, having a high conductivity graphite as a significant disadvantage of graphite, namely its very low resistance to mechanical wear, for this application it does not matter.
According to another variant implementation, the lower part can be manufactured, for example, using needle coke as source material. As you know, needle coke is a high-grade petroleum coke, respectively, pitch coke, while its name is determined by its needle-like structure. Needle coke has, among other things, its low coefficient of thermal expansion, as well as their small electrical resistivity after gravitywave in the longitudinal direction of the needle structure. It is preferred, in particular, in the lower part of the cathode, through which currents of high density. Due to appropriate the designs can provide the orientation of needle coke particles in a vertical position. The decrease in electrical resistivity leads to a smaller voltage drop across the cathode and thereby achieve improved energy efficiency in the electrolysis of molten environments. As the cost of energy is a big part of the overall cost of the process, due to this, you can achieve significant savings.
The upper part of the cathode may be made of any known suitable for use as cathode materials. In particular, as the source materials you can use, calcined anthracite, coke or graphite. The source material is crushed and sorted by particle size. Given the mixture of fractions of grains mixed with pitch and then form the upper part. Then perform one or more processing steps at elevated temperatures, on the basis of the temperature of heat treatment and source materials distinguish between graphite, graphite and amorphous cathode material.
Preferably, the cathode has a vertical current supply. This refers to the vertical input current below the bottom of the cathode. Due to this, preferably excluded uneven distribution of current in the cathode unlike conventional horizontal supply current.
According to one variant of implementation of the cathode, according to the image the structure, the lower part may be provided with vertical pins as the supply current. These pins can be made in the form of threaded pins, while the lower part has a threaded hole as contacts for receiving the threaded pins. In the screw holes you can screw provided with an external thread pins vertically or approximately vertically in the lower part of the cathode. Thus, in the framework of the electrolysis of molten environments, you can enter the current in the cathode approximately vertically. Thus the supply current can be kept selenagomeznet by matching the number and diameter of the pins with the cathode geometry.
The geometry of the pins may preferably be the same as the geometry of the threaded nipple for graphite electrodes for making elektrostali. Regarding the current distribution, mechanical strength and the possibility of screwing this geometry has proven particularly well. Relatively large cross-section of the pins causes a large leakage of electric current, and the length provides a sufficiently large distance of the cathode and thus the cells of the cell from the current-carrying rods, which provides the possibility of strong cooling.
According to a preferred variant implementation, the pins are made of graphite. This achieves a particularly you who Oka thermal stability of pins, as well as small electrical resistance, which leads to lowering the unit cost of energy when performing electrolysis of molten environments.
Additionally, for a homogeneous supply current, it is expedient when the lower side of the cathode is made in the form of a narrowing down of the trapezoid body. Thus, the input is perpendicular or approximately perpendicular to the current is homogeneous and evenly distributed in the upper part of the cathode. Preferably, in case the cathode of a separate cathode blocks, at least some of cathode cathode blocks have such a narrowing down of the trapezoid body, however, they are preferably parallel to each other. Trapezoid body can be, for example, in the longitudinal direction of the cathode or perpendicular to it.
It should be noted that in the framework of this invention, the expression "approximately vertical" includes all the directions that form an angle less than 20 ° with the vertical. However, in the broadest sense "vertically" covers all vertical carts, which are not, as usual, horizontally.
Below is a more detailed explanation of the invention based on the non-exhaustive nature of the exemplary embodiment with reference to the accompanying drawings, which depict:
figa - cross the cut cell electrolyzer to produce aluminium from aluminium oxide according to the prior art;
fig.1b - cell electrolyzer according figa, on the side view from the outside;
figs is a partial section of a cell of the electrolyzer to produce aluminium from aluminium oxide according to the prior art, in isometric projection;
figa - cathode unit according to one variant of carrying out the invention in isometric projection; and
fig.2b - cathode unit according figa, in isometric projection is rotated 90º.
In the figures the same reference positions denoted by identical or corresponding to each other elements.
On figa and 2b shows the cell electrolytic cell with a cathode 1 according to a variant implementation of the invention, in two different isometric projections. Shows the cathode 1 is suitable for use in obtaining aluminum from aluminum oxide in accordance with the method of Hall-Heroult. Cell electrolyzer is supplied in this case, two side walls 1A1, which together with a bottom wall 1A2 form the electrolytic bath. In the shown case, the side walls 1A1 pass along a longitudinal side of the cathode 1. The side wall 1A1 made of separate blocks a side wall. Bottom wall 1A2 is the top or first part 1A of the cathode 1. The cathode 1 in this exemplary embodiment is made of a separate cathode units 11.
The lower part 1b of the cathode 1 contains in the example shown the implementation of the multiple contacts 1b1, which are made in the lower area of the trapezoid bodies 1b2, tapering V-shape down. Contacts 1b1 can be performed, for example, in the form of an internal thread (not shown), for receiving the corresponding pin 9 with a corresponding external thread for supplying a current to the cathode 1. Several of the pins 9 on its opposite contacts 1b1 sides are connected with the current-carrying rods 3, which lead to cumulative current-carrying busbars 10, for the purpose of connecting the cathode 1 with the corresponding pole of the voltage source.
The upper part 1A and a lower part 1b are connected to each other through an intermediate layer 1C, which may be, for example, a graphite film. It provides the ability to remove the upper part of the cathode without damaging the bottom. Simultaneously graphite film prevents penetration of liquid aluminum or electrolyte to the bottom and thereby functions as a separation layer. While graphite film, despite the worst electrical conductivity perpendicular to the plane of the film compared with the conductivity within the plane of the film, because of its small thickness, component, for example, a few millimeters, has a very small absolute electrical resistance and provides a very good electrical contact between the upper part and lower part, so that the functioning of the social opportunities cathode saved. In addition, the intermediate layer compensates for the expansion of the two parts 1A, 1b, for example, due to thermal fluctuations.
Because the upper part 1A and a lower part 1b are performed separately from each other, both parts can be made of different materials and have different properties with respect to thermal expansion and electrical resistivity. In particular, the upper part 1A can be made so that it is the most well-can withstand the wear and tear, for example, caused by mechanical abrasion, as well as uneven electrochemical decomposition.
In contrast, the lower part 1b should be performed taking into account possible homogeneous supply current and the highest possible energy efficiency. To do this, it can be optimized for the used materials, as relatively fast wear of the upper part 1A, which must be replaced more often performed separately from the lower part 1b. Thus, you can choose more expensive materials, such as, for example, needle coke, to optimize with a long service life of the lower part 1b with respect to the desired homogeneous distribution of the current.
As suitable materials for the current-carrying rods 3 are suitable, in particular, copper and aluminum because of its low specific electric is practical resistance. Because the supply current rods distant pins 9 from the cathode 1, then they are very cool, and so there is no need to run them from stable to high temperature steel. On the basis of minor electrical resistivity of the above-mentioned metals for current-carrying rods 3 less energy is converted to thermal losses, and could significantly increase the energy efficiency of electrolysis of molten environments. Shows narrowing 1d trapezoidal bodies also contribute to the increase of the distance between the upper part 1A of the cathode 1 and the current-carrying terminals 3 and thereby cooling the current-carrying rods 3.
As materials for the cathode 1, you can use all well-known specialists in the field of engineering materials suitable for electrolysis of aluminum from its oxide. Suitable materials are indicated, for example, in DE 10261745, the content of which in this part is included in this description. Pins 9 can be manufactured, in particular, of the same materials as the cathode 1. Especially preferred in this regard is graphite on the basis of its thermal resistance, as well as on the basis of its small electrical resistivity.
The list of reference position:
1a the Upper part of the
1A1 Lateral wall
1A2 Bottom wall
A Block is the iron wall
1b the lower part of the
1b2 Trapezoid body
1c Intermediate layer
3 current-carrying terminal, current-carrying bus
4 the Anode
6 a Mixture of electrolytic baths (alumina, cryolite)
7 the Negative pole of the voltage source
8 the Positive pole of the voltage source
10 Team conductive bus
11 of the Cathode block.
1. The cathode (1) for the cell of the electrolyzer to produce aluminium from its oxide in an electrolytic bath containing the upper part (1A), addressed to the electrolytic bath, and the lower part (1b), which is provided with contacts (1b1) to supply current, characterized in that the upper part (1A) and lower part (1b), at least in some sections are connected to each other Rethimno protective intermediate layer (1C).
2. The cathode (1) according to claim 1, characterized in that the intermediate layer (1C) is made from graphite.
3. The cathode (1) according to any one of claim 1 or 2, characterized in that the intermediate layer (1C) is a graphite film.
4. The cathode (1) according to claim 3, characterized in that the lower part (1b) is made using needle coke as source material.
5. The cathode (1) according to claim 4, characterized in that the lower part (1b) has a vertical supply current.
6. The cathode (1) according to claim 5, characterized in that the lower part (1b) is provided with rezinovy and holes as contacts (1b1) to receive threaded pins.
7. The cathode (1) according to claim 6, characterized in that the upper part (1A) is fabricated using anthracite, coke or graphite.
8. The cathode (1) according to claim 7, characterized in that the lower part (1b) is made in the form of narrowed down the trapezoid body (1b2).
9. The cathode (1) according to claim 8, characterized in that the cathode (1) contains several cathode blocks (11), in particular, is made of several cathode blocks (11), while the cathode blocks (11) are fulfilled, in particular, geometrically or structurally identical or identically functioning and/or are, in particular, adjacent to each other from the sides.
10. Cell electrolyzer to produce aluminium from its oxide, characterized in that it contains a cathode (1) according to any one of claims 1 to 9.
SUBSTANCE: partitions and/or grids, and/or aluminium-moistened open-pore cellular structures from material lass electrically conductive than aluminium are placed under each anode on the bottom surface, perpendicular and/or at angle 45-90° to bottom plane, perpendicular and/or at angle 45-90° to longitudinal axis of cathode rods, which completely of partially prevent horizontal components of cathode current from flowing in aluminium layer.
EFFECT: reduction of horizontal components of currents in melt layer, uniform distribution of current, reduction of inter-pole distance and reduction of electric energy consumption for aluminium production or increase of output by current.
15 cl, 8 dwg
SUBSTANCE: method involves immersing mounted samples of silicon carbide blocks into an electrolyte at aluminium electrolysis temperature and bubbling the electrolyte with carbon dioxide, air or a mixture thereof, moving the samples and comparing the obtained samples with the original samples. After immersion, the samples are held in the electrolyte which is in contact with aluminium at electrolysis temperature, with the controlled area of the sample in the electrolyte. The samples are then raised and held with the controlled area of the sample in a gas phase for not more than 20 minutes. The samples are then moved in the vertical plane while alternately holding the controlled area in the electrolyte and in the gas phase for not more than 10 minutes and the degree of wear thereof is determined from change in the volume of the samples.
EFFECT: shorter time for testing samples of blocks and obtaining visible reduction in cross dimensions of samples of said blocks owing to intensification of the wear process by increasing the rate of wear.
3 cl, 3 dwg, 2 ex, 2 tbl
SUBSTANCE: method involves introduction of carbon-bearing substrate material to a mould and application onto it of a layer of composite heat-resistant material containing metal boride, sealing of the contents of the mould in the form of a cathode block and annealing of the cathode block; as material of carbon-bearing substrate and the layer of composite heat-resistant material there used are materials having close coefficients of thermal linear expansion and values of sodium expansion and the following particle size distribution: content of fractions in carbon-bearing substrate (-10+0.071) mm - 76±10 wt % and (-0.071+0) mm - 24±10 wt %, content of fractions in the layer of composite heat-resistant material (-10+0.071) mm - 50±30 wt % and (-0.071+0) mm - 30±50 wt %; with that, material of the carbon-bearing substrate is added to a mould pre-heated to the material temperature. The composite heat-resistant material layer in a sealed state is maximum 8.0% of height of the cathode block and contains 20.0-80.0 wt % of metal diboride. Sealing of the cathode block is performed by vibration moulding, and annealing is performed at 1100°C during 5 hours.
EFFECT: improving quality and service life.
3 cl, 3 dwg, 1 tbl
SUBSTANCE: invention relates to a design of a cathode section of an aluminium electrolyser. The cathode section includes a cathode carbon unit, a cathode current-carrying rod with an electrically conducting part from material with high specific electric conductivity, which is installed in an internal cavity of the cathode carbon unit and fixed in it by means of a cast iron cast. The electrically conducting part of the rod is made in the form of an insert of individual elements attached to each other with a gap, which is installed on one or more outer surfaces of the cathode current-carrying rod through a cast iron casting layer. The individual elements of the insert can be of round or rectangular shape or any other type of cross section. Inserts can be installed throughout the length from 10% to 100% of length of the cathode current-carrying rod.
EFFECT: reduction of voltage drop in a cathode unit and low electric contact resistance between a cathode current-carrying rod and an electrically conducting insert with high specific electric conductivity throughout the length of the cathode current-carrying rod.
3 cl, 3 dwg
SUBSTANCE: on hearth surface placed are baffles and/or grates, and/or open-pore cellular structures wetted by aluminium made of material with lower electric conductivity compared with that of aluminium perpendicular and/or at 45°-90° to heart surface, perpendicular and/or at 45°-90° to lengthwise axis of cathode rods preventing partially or completely the flow of horizontal components of cathode currents in aluminium layer along the hearth. Electrolytic cell can operate with consumable or nonconsumable anodes, that is, "inert" anodes.
EFFECT: uniform current distribution, smaller electrode gap, lower power consumption, higher yield.
15 cl, 5 dwg
SUBSTANCE: electrolysis unit includes a cathode device containing a bath provided with a coal bottom and composed of coal blocks enclosed in a metal housing, with refractory and heat-insulating materials arranged between the metal housing, an anode assembly containing coal anodes connected to anode sludge, arranged in upper part of the bath and submerged into molten electrolyte; at the coal bottom, under each of the anodes there located are floats with higher specific electric conductivity in comparison to that of electrolyte, stable to destruction in cryolite-alumina melts and liquid aluminium; with that, upper surface of the float projects above the level of cathode aluminium and the floats can be moved and/or replaced to reduce inter-pole gap between anode and cathode. The floats are made from carbon, or from silicon carbide, or from a mixture of titanium diboride and carbon based on high-temperature binding substance and are covered with titanium diboride. Upper surface of the float is flat, or convex, or concave, or inclined to horizon and has capillaries and/or channels, and/or planes attaching the upper surface of a pedestal to cathode metal.
EFFECT: reduction of specific power consumption.
15 cl, 4 dwg
SUBSTANCE: composite has composition defined by formula (C-N-B-MR)x(Al-MR)y(R)z, where MR is one or several carbides, nitrides or borides of one or more heat-resiatant metals of IV, V, VI groups, C-N-B-MR is one or several carbides, nitrides or borides of one or more heat-resistant metals of IV, V or VI groups, Al-MR is one or several aluminides of one or several aforesaid heat-resistant metals. Note here that if MR=Nb, Ta, Hf, Zr, Ti, V, then Al-MR=Al3MR; is MR-W, Cr, then Al-MR=Al4MR; if MR=Mo, then Al-MR=Al8Mo3 or Al17Mo4. Note here that the condition should be satisfied whereat if C-N-B-MR=TiB2, Al-MR is not Al3Ti; R is residual component other than carbon containing one or several phases from Al4C3, AlN, AlB2, Al1·67B22, MRtAlu(C-N-B)v, where t, u, v are numbers larger than or equl to zeto; x, y, z are volume fractions of appropriate components. Note here that x>y; x+y>0.5; x+y+z=1 and 0.01<y<0.5.
EFFECT: composite features good wettability due to decreased grain size and higher density of interface surface to allow using said composite as coating of components wetted by liquid aluminium.
12 cl, 15 dwg
SUBSTANCE: proposed cathode comprises jacket and lining with base made of heat-insulation and refractory materials, side lining, bottom of hearth sections with cathode rods and cathode downleads. The latter are made from the stack of flexible aluminium tapes, contact plate and steel adapter to be welded as-assembled to cathode rod and plugged to cathode bus. Cathode downleads are assembled in installing the lining by welding them to cathode rods and bolting downlead contact plates to the bracket. After disassembly of side lining, cathode rods with their downleads are extracted from cathode jacket, cleaned and transferred to cutting bay. Cutting is performed along the line or in zone of joint between rod and downlead metal adapter. After skinning the metal adapter end, cathode downlead is transferred for reassembly.
EFFECT: higher reliability due to larger number of aluminium tapes.
2 cl, 1 dwg
FIELD: electrical engineering.
SUBSTANCE: cathode device of an aluminium electrolytic cell with an embossed hearth contains a lined cathode shell ad a hearth composed of higher bottom blocks with projections and lower bottom blocks. The lower bottom blocks are installed at the cathode device hearth butt ends. The lower bottom blocks alternate with higher bottom blocks with projections or are installed in the projection centre of the electrolytic cell anode array, with at least two higher bottom blocks with projections, alternating with lower bottom blocks, installed at the both ends of the electrolytic cell anode array. The bottom block projection height is equal to 0.1÷0.6 of that of the smaller bottom block. The top parts of higher bottom blocks have level edges. The bottom blocks projections are made of a refractory non-carbon material, resistant to hot melt effect.
EFFECT: reduction of hot melt circulation rate and decrease of metal slant due to projecting barriers in the metal layer; decrease of heat and mass transfer inside the aluminium layer which reduces loss of heat from the electrolytic cell surface and enables work at a lower voltage.
4 cl, 5 dwg
SUBSTANCE: method for electrolytic production of metal in an electrolysis cell, having a cathode, an anode and collectors of impurities dissolved in the electrolyte, involves passing cathodic current through the cathode to obtain metal at the cathode and deposit impurities on the collector. The collector, which is placed between the anode the cathode, is a bipolar porous collector electrode which is a cellular matrix which is inert to the metal deposited at the cathode and the electrolyte. The bipolar porous collector electrode is in form of an open porous structure having internal pores or capillaries, or channels, or cavities, which are particularly V-shaped and/or W-shaped and/or S-shaped and are filled with the metal which is deposited at the cathode. The method employs a bipolar porous collector electrode, wherein the internal pores or capillaries, or channels or cavities are wettable by metal, and have dimensions, particularly diameter and length, which are sufficient for them to hold the metal and prevent spontaneous flow of metal from them due to surface tension forces of the metal.
EFFECT: efficient separation of cathode and anode process products, high current output, lower ohmic resistance of the pole gap and specific power consumption, and removing impurities from the cathode metal.
11 cl, 4 dwg
FIELD: metallurgy; graphitic cathodes for production of aluminum.
SUBSTANCE: the invention presents a graphitic cathode for electrolysis of aluminum and is dealt with the field of metallurgy, in particular, with the graphitic cathodes used in production of aluminum by an electrolysis. The graphitic cathode for electrolysis of the aluminum is produced by graphitization of the cathodic block from a carbonaceous material. At that the cathode is made as the entire block with different specific electrical resistance along its longitudinal axis. At that the specific electrical resistance in the end areas of the cathode is more, than in its central area. The technical result - increased service life of the graphitic cathode at the expense of increased erosion resistance in the end areas of the cathode.
EFFECT: the invention ensures increased service life of the graphitic cathode at the expense of increased erosion resistance in the end areas of the cathode.
6 cl, 7 dwg, 1 tbl
FIELD: metallurgy; production of graphitic cathodes.
SUBSTANCE: the invention presents an impregnated graphitic cathode for production of aluminum by electrolysis and is pertinent to the field of metallurgy, in particular, to production of the graphitic cathodes used in production of aluminum by electrolysis. The invention offers an impregnated graphitic cathode for electrolysis of aluminum and a method of its production. The cathode contains in its pores an impregnating product heat-treated. At that in the capacity of the impregnating product the cathode contains a carboniferous product heat treated under the temperature of no less than 1600°С to provide resistance to erosion at the expense of protection by the formed graphitized binding substance. The method includes production of the graphitic cathode, its impregnation by dipping into the impregnating product in vacuum and a thermal treatment. At that the graphitic cathode is produced from coke, with graphite or without it, and also from a pitch, and before impregnation it is exposed to calcination at the temperature exceeding 2400 °С. The impregnation is realized by a carboniferous product at the temperature of its viscous state and the thermal treatment of the impregnated cathode is conducted at the temperature of less than 1600 °С, but sufficient for hardening and-or sintering of the impregnating product and formation of the non-graphitized coal layer for protection of graphitizing binding substance against erosion. The technical result is an increase of service life of the graphitic cathode.
EFFECT: the invention ensures an increase of service life of the graphitic cathode.
4 cl, 2 dwg, 1 ex
FIELD: nonferrous metallurgy; production of aluminum by electrolysis of fused salts.
SUBSTANCE: the invention I pertinent to nonferrous metallurgy and may be used in a design of electrolyzers for production of aluminum by electrolysis of fused salts. The technical result of the invention is hardening of a hearth, a decrease of thickness of a metal layer on the hearth and an interpolar space, a decrease of speeds of circulatory flows of cathodic metal, a decrease of losses of current. The cathodic device contains a lined cathodic housing and a hearth made out of from carbonaceous blocks with channels of a rectangular cross section. On the surface of the hearth there is a wetted with aluminum cover and the channels have the length equal to the width of the stack of the cathodic device, and with a width equal 1,1-2,2 well of the carbonaceous block, depth, equal to 0.2-0.4 of height of the carbonaceous block and thy are formed by the lateral longitudinal surfaces of the carbonaceous blocks and the carbonaceous blocks of the lateral cathodic lining. The electro-conductive cover wetted with aluminum is made out of titanium diboride.
EFFECT: hardening of a hearth, a decrease of thickness of a metal layer on the hearth and an interpolar space, a decrease of speeds of circulatory flows of cathodic metal, a decrease of losses of current.
2 cl, 2 dwg
FIELD: major repair of aluminum cells.
SUBSTANCE: cathode casing of aluminum cell includes lengthwise walls with windows for outlet of cathode rods, end walls, bottom and ring frames rigidly joined with walls and bottom. In order to lower labor consumption, simplify mounting and dismounting operations. Ring frames adjacent at least to one of lengthwise walls (except boundary ring frames) from their upper part till inner edge in range of height of windows for outlet of cathode rods are freely adjoined to said lengthwise wall. According to other variant of invention at least one lengthwise wall is detachable. Parting places of said wall are arranged between boundary ring frames in range of height of windows for outlet of cathode rods. In parting places members providing rigid joint of detachable wall with fixed portion of casing wall are mounted.
EFFECT: improved design, simplified works at major repair.
FIELD: formation of protective coatings for carbon containing components of electrolytic cell at aluminum production.
SUBSTANCE: method comprises steps of preparing liquid suspension of refractory material dispersed in solution of lignosulfonate binder; applying suspension as coating on surface of carbon containing component; drying coating.
EFFECT: improved resistance of carbon containing component against rupture at operation of electrolysis cell.
34 cl, 1 dwg, 4 tbl, 7 ex
FIELD: non-ferrous metallurgy; electrolytic production of aluminum; cathode units of aluminum electrolyzers.
SUBSTANCE: proposed side lining includes interconnected members - plates and blocks made from non-metallic refractory compounds possessing high resistance and interconnected by means of end faces in form of inversed symmetrical projections and recesses and adhesive or cementing mix. Plates and blocks are made from silicon carbide. Angular blocks are made in form of strip, 70 mm thick and 600-800 mm long which is bent at center around longitudinal axis at angle of 90° relative to vertical whose end faces are inclined at angle of 18° relative to vertical and are narrowing downward by 219 mm each. End faces are made in form of inversed symmetrical projections and recesses at radius of 14-15 mm which are parallel to vertical axis of walls of aluminum electrolyzer.
EFFECT: increased service life; enhanced strength and reliability; saving of lining material; increased useful volume of electrolyzer; increased yield of aluminum.
FIELD: aluminum cells, namely cathode facing for them.
SUBSTANCE: cathode facing includes carbon blocks, heat insulation layer and refractory part having two protection layers, upper layer adjoining to carbon blocks and lower layer made of powder materials. Upper protection layer includes alumosilicate composition resistant against action of electrolyte components containing 27 -35% of Al2 O3 with fraction size no more than 2.5 mm and with thickness consisting 10 - 50% of height of refractory part. Lower protection layer is made at least of one sealed metallic vessel filled with refractory material including carbon-containing composition resistant against action of melt aluminum and electrolyte components and having heat conductivity factor no more than 0.1 Wt/(mK). In lower protection layer vessels are filled with carbon black; thickness of said layer consists 50 - 90% of height of refractory part.
EFFECT: increased useful life period, improved operational characteristics of cell.
3 cl, 7 dwg, 1 tbl
FIELD: aluminum production electrolyzers of all types.
SUBSTANCE: proposed method includes mounting the heat-insulating and refractory components of electrolyzer and applying protective material on base of covalent nitrides to surface of side lining. Used as protective material is boron nitride-based material which ensures reduction of after-start period, increases electrolyzer service life, enhances aluminum grade, increases yield by current and daily productivity of electrolyzer; protective material is applied flush with top in continuous layer. Lower boundary of coat is located below "electrolyte-metal" interface. Thickness of coat is maintained within 0.1-1 mm. Open surface porosity is maintained within 2-3%. Consistency of material of coat changes from fluid to viscous-flow state. Application of coat is performed by spraying, painting or concrete-spraying method.
EFFECT: increased service life of electrolyzer; increased daily productivity of electrolyzer.
4 cl, 2 dwg, 1 tbl
FIELD: installation of aluminum electrolyzer hearth.
SUBSTANCE: proposed method includes preliminary estimation of quality of hearth modules by proximate ultrasonic inspection, mounting of complete set of hearth modules and forming of hearth; electrolyzer is equipped with hearth modules at inhomogeneity index not exceeding 0.65 relative units according to ultrasonic inspection; inhomogeneity index is determined by the following formula Iinhom = (tmax/tmin-1), where Iinhom is inhomogeneity index according to ultrasonic inspection; tmax is maximum magnitude of index of ultrasonic inspection for definite electrolyzer; tmin is minimum magnitude of index of ultrasonic inspection for definite electrolyzer; hearth is formed in such way that adjacent modules with close indices of ultrasonic inspection are mounted in longitudinal and transversal directions; modules with minimum indices of ultrasonic inspection are mounted in center of hearth at smooth increase of this index toward end faces of electrolysis bath.
EFFECT: increased service life of hearth; reduced yield of low-grade metal; reduced power requirements.
3 dwg, 1 ex
FIELD: mounting aluminum electrolyzers at major repair or in capital construction.
SUBSTANCE: current-supply metal rod is placed in slot of carbon block on layer of carbon-containing conducting material. Surface of carbon block slot is preliminarily coated with carbon-based surfactant and layer of carbon-containing conducting material is compacted by vibration applied on current-supply metal rod, thus ensuring reliable electromechanical "conducting rod-carbon block" contact and reducing probability of penetration of aluminum melt into hearth body. At application of vibration in local zone on side of flush area, maximum reduction of voltage drop is ensured in contact layer between rod and block slot. Maximum thickness of layer of carbon-containing conducting material before vibration is equal to optimal magnitude determined by definite formula.
EFFECT: enhanced efficiency.
4 cl, 4 dwg, 1 tbl