SU765403A1 - Method of thermal preparation of amuminium electrolyzer to its start up - Google Patents

Description

The invention relates to the field of aluminum production by the electrolytic method and is aimed at improving the technological operation of preparation for starting any type 5 aluminum electrolysis cell for electrolysis.

Known and widely used is the method of thermal preparation by burning "on metal". The molten aluminum is poured into the cell of the electrolyzer, the anode is partially immersed in it, and the electrolyzer is included in the network circuit (1].

Heating, the electrolyzer is carried out due to the heat released in the anode and cathode. The relatively low electrical resistance of the electrolyzer during firing on metal does not allow it to be heated to the optimum temperature, which enhances the processes of destruction of the lining during commissioning and during operation.

Known methods for improving 20 heat treatment of an aluminum electrolysis cell do not sufficiently eliminate these drawbacks.

A known method of thermal preparation for starting an aluminum electrolyzer, including heating the hearth at a given speed and pouring the electrolyte. For this, after heating the hearth to a temperature of 600–700 ° С, molten electrolyte is poured onto it and kept at a temperature for 3–10 hours [2] ..

The disadvantage of this method is the relatively long preparation of the cell for start-up.

In order to reduce the duration of preparation and increase the useful use of equipment, the heating of the bottom of the cell and coking of the seams is carried out at a speed of 150-1000 deg / h, preferably 250-500 deg / h.

According to this invention, the hearth is heated by the organized burning of liquid fuel (e.g. diesel fuel, fuel oil) inside a confined space formed by the cathode lining, the lower surface of the anode and the temporary covers between the anode (or bell-type gas collectors) and the sides of the cell.

7ό5403

Achieving operational temperature; In combination with a high heating rate, it eliminates the main causes of premature destruction of the cathode device, shortens the service life, and ensures the possibility of starting electrolyzers after major repairs on the electrolyte. The range of these speeds provides a good mechanical connection between the interlock seams · with the hearth blocks. According to recent studies, such a rapid increase in the heating of the hearth provides the maximum yield of coke from the binder, and, accordingly, the minimum porosity of the upper part of the weld. The indicated rates of temperature rise are also explained by the possibility of heating 15 devices (nozzles) for supplying and burning fuel inside the cell. Thus, using these speeds, it is possible to heat-treat an aluminum electrolyzer for G-6 hours, depending on the specific state of the electrolyzer (installation quality and carbon materials used during installation).

P r m m After its overhaul in order to form a working space 25 where the fuel will be burned, the anode is placed at a distance of 150-200 mm from the bottom and the periphery of the shaft is carefully covered with removable metal covers .. The nozzles are installed at the corners of the shaft of the electrolyzer. The mode of operation of the nozzles is set on the first cell so as to ensure that the temperature of the hearth rises with speed. 15 ° C / h. Heat treating the electrolyzer passes for 6.5 h, and achieved opti- mally ₃₅ final temperature of 950 ° C. After that, starting raw materials are loaded into the bath and the electrolyte is poured, i.e. carry out the subsequent technological operation for electrolysis.

Subsequent electrolyzers undergo thermal preparation with heating rates of 300 ° C / h, 600 ° C / h and 1000 ° C / h. The results in all cases were positive. Electrolyzers reach the grade faster than usual by 7 days and work in a stable way; technological mode. During the test, the heat treatment according to the proposed method is carried out on 10 powerful aluminum electrolysis cells.

Sets of heating devices for supplying and burning fuel must be used repeatedly and the total amount that they need to have at each plant is determined by the number of simultaneously fired electrolyzers, i.e. 2-7 sets, which does not require significant costs.

The technical and economic effect of the application of the proposed method for the thermal preparation of an aluminum electrolysis cell is obtained by increasing the service life of the cell between overhauls (by 3 months) as a result of optimization of the conditions for heating the hearth; due to the saving of electricity spent on heating and firing electrolysers using known methods; reduction of downtime for firing for 72 hours; improving the quality of raw aluminum.

Claims (2)

The invention relates to the field of aluminum production by an electrolytic method and is aimed at improving the technological operation of preparing to start up any type of aluminum electrolyzer for electrolysis. The method of thermal preparation by roasting on metal is known and widely applied. The molten aluminum is poured into the cell of the electrolyzer, the anode is partially immersed in it, and the electrolyzer is connected to the circuit of the network 1 Heating, the electrolyzer is carried out by the heat released in the anode and cathode. The relatively low electrical resistance of the electrolyzer during firing on the metal does not allow it to be heated to the optimum temperature, which enhances the processes of destruction of the lining during the start-up for electrolysis and during operation. The known methods for improving the heat treatment of an aluminum electrolyzer do not sufficiently eliminate these drawbacks. The known method of thermal preparation for the launch of an aluminum electrolysis cell, including heating the bottom with a given speed and filling the electrolyte. To do this, after heating up to 1 ° C to a temperature of 600-700 ° C, molten electrolyte is poured onto it and kept at a temperature of 3-10 hours. 2 .. The disadvantage of this method is the relatively long preparation of the electrolyzer for start-up. In order to shorten the preparation time and increase the useful use of the equipment, the bottom of the electrolysis cell is heated and the seams are coked at a speed of 150-1000 degrees / hour, preferably 250-500 degrees / hour. According to the present invention, the bottom heating is carried out by organized combustion of liquid fuel (e.g., salt, fuel oil) inside a closed space formed by the cathode lining, the bottom surface of the anode, and temporary lids between the anode (or bell type gas collectors) and the sides of the electrolyzer. Achieving operational temeregur. in combination with a high heating rate, it will eliminate the main causes of the premature destruction of the cathode device, shorten the service life and ensure the possibility of starting the electrolyzers after the repair of the electrolyte. The range of speeds indicated provides a good iviexaHHtfecKyro connection of interblock joints with hearth blocks. According to recent studies, such heating rates of the hearth provide the maximum coke yield from the binder, and, accordingly, the minimum porosity of the upper part of the seam. The indicated rates of rise are also explained by the possibilities of heating devices (nozzles) for supplying and burning fuel inside the electrolyzer. Thus, using such speeds, it is possible to perform heat treatment of the aluminum electrolysis cell for i-6 hours, depending on the specific state of the electrolyzer (quality of installation and carbon materials used during installation). PRI m e, p. In the electrolyzer, after its overhaul, to form a working space where fuel will be burned, the anode is located 150-200 mm from the bottom, and the periphery of the shaft is carefully covered with removable metal covers. Nozzles are installed at the corners of the electrolyzer shaft. The mode of operation of the nozzles is set on the first electrolyzer such that: to ensure the rise of the temperature of the bottom with speed. 150 ° C / h The heat treatment of the electrolyzer takes 6.5 hours, and an optimum final temperature of 950 ° C is reached. After that, the starting raw material is loaded into the bath and the electrolyte is poured, i.e. perform the subsequent electrolysis process operation. Subsequent electrolysis cells undergo thermal preparation with heating rates of 300 ° C / h, 600 ° C / h and 1000 ° C / h. The results in all cases are positive. The electrolysis cells are 7 times faster than usual for 7 days and work in a stable way; technological mode. During the test, the heat treatment according to the proposed method is carried out on 10 high-power aluminum electrolyzers. The heating devices for the supply and combustion of fuel must be used many times and the total amount that must be at each plant is determined by the number of simultaneously fired electrolyzers, i.e. 2-7 sets, which does not require significant costs. The technical and economic effect from the application of the proposed method of thermal preparation of an aluminum electrolysis cell is obtained by increasing the service life of the electrolysis cell between capital repairs (by 3 months) as a result of optimization of the bottom heating conditions; by saving energy, spent on heating and burning of electrolyzers using known methods; simply reducing firing for 72 hours; improving the quality of aluminum-fiber. The invention The method of thermal preparation for the start-up of an aluminum electrolysis cell, including heating the bottom at a predetermined speed, filling the electrolyte, characterized in that, in order to reduce the duration of preparation and increase the equipment utilization, heating the bottom and coking the seams at a speed of 150-1000 degrees / h, preferably 250-500 degrees / h. Sources of information taken into account in the examination 1, Reference metallurgist on nonferrous metals. Production of aluminum, M., metallurgi, 1971, p. 257-259. 2, USSR Author's Certificate N 549510, cl. C 25 C 3/06, 1974.