RU2485216C1 - Electrolysis unit for aluminium manufacture - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: electrolysis unit includes steel casing, heat-insulating brick masonry, carbon lining, busbars, cathode and anode units; at that, anode unit consists of baked carbon blocks, in which vertical holes are made in the form of flattened cones, the lower diameter of which is larger than the upper one by 1.9÷2.1 times and comprises 80÷100 mm, and number of holes in the anode unit is 8÷10 pcs.

EFFECT: providing the possibility of quicker and more qualitative removal of anode gases, reducing resistance and voltage on the bath, reducing voltage in anode-to-cathode distance, which will lead to reduction of power consumption.

1 dwg, 1 tbl

Description

The invention relates to ferrous metallurgy, in particular to the electrolytic production of aluminum, namely to the anode device of aluminum electrolysis cells.

A known cell for producing aluminum by melt electrolysis, containing a system of continuous anodes using prebaked anode blocks (RU 2041975, class C25C 3/12, publ. 08.20.1995), this design reduces the specific consumption of electrical energy.

The closest in technical essence to the present invention is the invention of an electrolytic cell for the production of aluminum, containing carbon anodes with channels and a cathode device comprising a layer of liquid aluminum on the bottom, the cathode collector rods are made of insoluble materials in aluminum, and their upper part protruding from liquid aluminum , made in the form corresponding to the shape of the opposite channels in the anode, and is located in the channels of the anodes at a distance of 1.0-6.0 cm parallel to the side surfaces of the channel scarlet. The channels in the carbon anodes and the upper part of the cathode collector rods protruding above the surface of liquid aluminum, have a triangular cross-section (RU 2282680 class. C25C, publ. 08.27.2006). The main advantage of such anodes is the reduction of specific energy consumption. Since the gas-bubble layer decreases, the resistance in the electrolyte decreases and, as a result, the voltage in the bath decreases.

Despite this, these anodes have a significant drawback. The production of such an anode requires high accuracy and very laborious work, since:

- when removing it from the vibrating press, the anode crumbles and breaks around the edges;

- when firing, the grooves stick together.

A serious drawback is the formation of irregularities on the working surface and higher foaming. The main disadvantage of such an anode block is the fact that is already apparent during operation of the anode. During electrolysis, the anode is not completely immersed in the electrolyte, i.e. cut grooves stick out above the electrolyte to release anode gases. Over time, these grooves become clogged with coal foam. Further, also with time, the anode burns from below, respectively, the height of the grooves decreases, as the height of the anode decreases, therefore, the grooves either simply sink completely in the electrolyte, or it is necessary to remove the anodes and grind the height of the grooves each time, which is impractical. Over time, all the advantages of these anodes disappear.

The task of the invention is to reduce energy consumption.

This is achieved by the fact that in the calcined anode of the aluminum electrolyzer it is proposed to make not channels, but holes in the form of a truncated cone, the ratio of the upper diameter to the lower diameter is 1.9 ÷ 2.1, the lower diameter of the cone is 80 ÷ 100 mm, the number of holes in the anode is 8 ÷ 10. These holes will reduce the path of exhaust gases and reduce the thickness of the gas layer and, as a result, reduce the resistance in the electrolyte and the voltage on the bath, which will lead to a decrease in energy consumption.

To prevent filling the holes with carbon foam, the latter are made in the form of a cone. This leads to an increase in the gas velocity in the holes in the direction from the bottom up and the removal of carbon foam on the surface of the anode.

The number of holes in the anode 8 ÷ 10 is explained by the fact that if there are more than 10 holes, the anode will be brittle and may collapse, and if the number of holes is less than 8, the decrease in the gas gap will be insignificant.

Also, this invention completely eliminates another problem that arose in the manufacture of anodes with channels. Due to the fact that the holes in the anodes are in the form of a truncated cone, this ensures unhindered extraction of the anodes from the vibropress. The exhaust gases will bubble the melt, which will lead to an increase in the solubility of alumina in the electrolyte and a decrease in the ohmic resistance of the bubble layer of gases accumulated on the sole of the blocks.

An example of the operation of the invention. The electrolysis was carried out in a laboratory setup at a cathode direct current density of 0.62 A / cm ² . During the experiments, identical electrochemical cells with different anode designs were used. The results are shown in figure 1.

Table 1 The results obtained after experiments and calculations U, B ΔU _N.R. , AT Δ _email , AT MPR, cm S _en , cm ² I, A ρ _beats Ohm cm Experience 1 2.88 1,53 1.35 6 12.56 6.2 0.456 Experience 2 2.81 1,53 1.28 6 12.56 6.2 0.434 Experience 3 2.76 1,53 1.23 6 12.56 6.2 0.415

The results of laboratory tests showed that the decrease in resistance in the MPR can be 9%, which will reduce the energy consumption by 1200-1500 kWh / t of aluminum.

Claims (1)

An electrolyzer containing a steel casing, heat-insulating brickwork, coal lining, busbar, cathode and anode devices, characterized in that the anode device consists of calcined coal blocks in which vertical holes are made in the form of truncated cones, the lower diameter of which is larger than the upper one, 1 9 ÷ 2.1 times and is 80 ÷ 100 mm, and the number of holes in the anode device is 8 ÷ 10 pcs.