SU1599445A1 - Method and apparatus for spot loading of alumina - Google Patents

Abstract

The invention relates to the metallurgy of aluminum and can be used in the production of aluminum by the electrolysis of alumina-containing melts. In order to increase the current efficiency and reduce the specific energy consumption, gas is supplied to the electrolyte or cathode metal layer at a flow rate of 0.1-0.5 l / min. For the supply of gas and alumina, a movable element 8 is used, equipped with a gas supply nozzle 9 and made entirely or having only a tip 11 of a material that does not interact with the molten aluminum and the electrolyte. In the lower part of the movable element, holes 12 are made to exit the dust-gas mixture. 2 sec. f-ly, 2 ill., 1 tab.

Description

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The invention relates to aluminum metallurgy and can be used in the production of aluminum by electrolysis of alumina-containing melts. j

The aim of the invention is to increase the current output and decrease the effective consumption of electricity by eliminating the possibility of alumina to fill the bath.

Fig. 1 shows a device C1 for carrying out the method; 2 - (1 movable part of the pipeline, embodiments.

The method is carried out by the following 15 dBrases.

Alumina from the silo under its own weight is loaded into the distribution bunker, from where a certain portion of it is supplied with a special device, 20 for example, with a screw, is fed into the dosing unit. When the pipeline path is open, the mobile part of which is in the upper position, a high pressure line (3-5 atm) opens and a predetermined amount of alumina is loaded onto the electrolyte surface or its volume, which depends on the position of the lower section of the movable part of the pipeline. The pressure of the JQ laziness closes and the low pressure line opens, the value of which ensures the flow rate of the gas carrier in the range of 0.1-0.5 l / min. The movable portion of the conduit is lowered to the lower position. At higher and lower costs, the current efficiency is reduced.

The table shows the dependence of the current output on the flow rate to blow. 40

At low flow rates, the decrease in current efficiency is due to the low efficiency of the blown alumina dissolution rate, the formation of precipitation and the formation of deposits. At high flow rates, the current efficiency is reduced due to an increase in aluminum loss due to oxidation due to intense metal stirring. Bubbles blow in aluminum 50 and the electrolyte and create upward flows that prevent alumina particles from settling on the bottom of the bath and increase their dissolution rate by reducing the thickness of the diffusion layer. In addition, the formed circulation contours distribute the alumina particles over a large volume of melt. Both of these fak35

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the torus helps stabilize the process mode of the bath, increase the average alumina concentration in the electrolyte, reduce the overvoltages of the anodic and cathodic processes, the frequency of anodic effects (practically absent) and, thus, increase the current efficiency and reduce specific energy consumption (see table).

The device (Fig. 1) consists of a hopper 1, a loading mechanism 2 for loading a predetermined portion of alumina into the dispenser 3, having a nozzle 4 for the high pressure line. The dispenser 3 is connected to a fixed element 5 of the pipeline, embedded in the guide pipe 6, through which the moving part of the pipeline 7, which has a special device, for example, an electromagnet, oscillates. The movable part consists of a metal pipe 8, having a low pressure line pipe 9 and an opening U to communicate both parts of the pipeline when the pipe 8 is in the upper position. The pipe is equipped with a tip 11, made of a material that does not interact with aluminum and electrolyte, for example cream nitride; The tip 11 is plugged from below, so the holes 12 for the passage of dust-gas mixture are located at the bottom in its side wall. The whole pipe can be made of a plugged ceramic pipe.

The device works as follows.

The pipe 8 oscillates up and down with a given time period by means of a lifting mechanism. In the lower position of pipe 8 in aluminum there is only a tip 11 which does not interact with aluminum and electrolyte. A pipe 9 from the low-pressure blast line (air or inert gas) is blown through the melt. Then the pipe rises. When the opening 10 of the pipe 8 is aligned with the fixed element 5 of the pipeline 7, the low pressure line closes and the high pressure line opens. When the load is stopped, the line switching is reversed and the pipe 8 is lowered to the lower position.

Studies on the low-temperature model for the deposition of particles in a liquid showed that when the gas flow rate is blown into the metal, within 0.4 ± 0.5 l / min., The particles practically do not precipitate, i.e. the bottom sediment does not accumulate, and the dissolution rate in the bubbling zone increases by a factor of 2-3. Bubble frequency at a given flow rate of blowing is 1.5–7 bubbles per second, which even exceeds the frequency of gathering of bubbles from the subarms of modern electrolyzers, referred to the unit of perimeter length of the anode, in which the electrolyte freezing at the side faces of the anodes does not going on. Consequently, there will be no freezing of the electrolyte in the zone of entry of the loading tube, therefore, the punching operation is eliminated, which facilitates the loading of alumina.

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Claims (2)

The formula of the invention is 1. A method for the point loading of alumina, including the periodical introduction of alumina in the electrolyte by gas carrier, characterized in that, in order to increase the current output and reduce the specific energy consumption, between Into the electrolyte or cathode aluminum additionally supply gas carrier with a flow rate of 0.1-0.5 l / min. 2. A device for point loading, alumina, containing a bunker, a metering device and a pipeline, is necessary for the purpose of inducing, current efficiency and reducing the specific consumption, a metal pipe that can be installed inside the pipeline and made with a nozzle, the pipe having a tip of a material that does not interact with aluminum and electrolyte. Flow blowing, 0.08 0.1 0.25 0.5 0.6 l / min Current output,% 89.2 91.1 93.3 92.1 90.4