CN110541176A

CN110541176A - aluminum electrolytic cell production process control method

Info

Publication number: CN110541176A
Application number: CN201910931479.3A
Authority: CN
Inventors: 李国维; 程志强; 陈国强; 卢昌云; 张玉坤
Original assignee: Shanxi Chinalco China Resources Co Ltd
Current assignee: Shanxi Chinalco China Resources Co Ltd
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2019-12-06

Abstract

The invention belongs to the technical field of aluminum electrolysis production, and particularly relates to a method for controlling a production process of an aluminum electrolysis cell. The invention mainly solves the problems of short service life of the electrolytic cell, poor economic index and the like caused by non-uniform thinking in the aspect of process control of the electrolytic cell, large difference of control effects of enterprises in China. The control method of the invention divides the normal production period of the electrolytic cell into eight time periods according to the cell age, adjusts the voltage level, controls the electrolyte level, controls the aluminum level, controls the molecular ratio level and controls the cell temperature.

Description

Aluminum electrolytic cell production process control method

Technical Field

The invention belongs to the technical field of aluminum electrolysis production, and particularly relates to a method for controlling a production process of an aluminum electrolysis cell.

Background

At present, the thinking of the electrolytic cell process control in the domestic electrolytic aluminum industry is not uniform, the control effect difference of each enterprise is large, and the service life of the electrolytic cell is short and the economic index is poor. At present, the bottom of an electrolytic cell adopting a high-aluminum level control idea is cooled, the sediment of the bottom of the electrolytic cell is increased, and extending legs are enlarged, so that the problems of early damage of a cathode, furnace leakage at the side part and the like occur before the service life of the electrolytic cell, and the economic index obviously slides down; the electrolytic cell adopting the low-voltage control idea tends to be cold, the working intensity is higher, and the current efficiency is lower; the current efficiency of the electrolytic cell adopting the control idea of the polymer ratio is lower; the electrolytic bath furnace bottom adopting the low molecular ratio control idea has more sediment and larger working strength. The poor results caused by the above process control ideas basically violate the operation rule of the electrolytic cell. By referring to various technical control routes in the same industry, in order to avoid adverse consequences caused by improper technical routes, according to the design requirements of the electrolytic cell and years of working experience, the harm of the electrolytic cell for keeping high aluminum level is rather fatal, the heat income of the electrolytic cell is inevitably reduced when the electrolytic cell is operated at low voltage, the heat preservation management of the electrolytic cell is inevitably enhanced for keeping heat balance, so that the anode steel claw is deformed, the service life of the steel claw is shortened, and the labor intensity of workers is increased.

Disclosure of Invention

The invention provides a method for controlling a production process of an aluminum electrolytic cell, aiming at the problems of the control thought of the electrolytic cell.

In order to achieve the purpose, the invention adopts the following technical scheme:

A method for controlling the production process of an aluminum electrolytic cell comprises the following steps: the normal production period of the electrolytic cell is divided into eight time periods according to the cell age, and the voltage level, the electrolyte level, the aluminum level, the molecular ratio level and the cell temperature of each time period are respectively adjusted and controlled. The prebaked cell undergoes the processes of forming a hearth and gradually deteriorating the quality of the cathode carbon block until the cathode carbon block is scrapped in the using process, and in order to inhibit the deterioration speed of the cathode carbon block in the process, the process control is further refined, so that a firm hearth can be formed better and the cathode can be protected better.

the eight time periods are respectively as follows: the first time period is 1-90 days; the second time period is 91-120 days; the third time period is 121 days to 150 days; the fourth time period is 151 days to 1 year; the fifth time period is 1 to 2 years; the sixth time period is 3-4 years; the seventh time period is 5 years to 8 years; the eighth time period is more than 8 years.

And in the first time period of 1-90 days, the control and adjustment of the medium-high aluminum level and the medium-high voltage are adopted, so that the furnace wall of the electrolytic cell is naturally formed. Three months in the later stage of starting is the key period of forming a hearth by the electrolytic cell, a firm furnace wall can be formed only by high-temperature macromolecules during the period, the horizontal current of the electrolytic cell can be reduced by the good furnace wall, the vertical current is increased, and the stable and efficient operation of the electrolytic cell is ensured. The high voltage can increase the heat income of the electrolytic cell, the amplitude of the voltage adjustment from the start date of the electrolytic cell follows the principle of small slow drop, the low aluminum level can reduce the heat loss, meanwhile, the anode heat preservation work of the electrolytic cell is enhanced, the three measures are enough to ensure that the temperature of the electrolytic cell is slowly recovered to be normal from 980 ℃ in three months at the start later stage, and the thickness of the furnace wall reaches 14 cm.

The electrolytic cell runs in a medium and high aluminum level mode, the aluminum filling amount is strictly controlled after the electrolytic cell is started, the aluminum level is controlled within a specified range, the aluminum level under the electrode is measured every day by using the electrode changing time during normal production, whether deposition is generated at the furnace bottom or not is judged according to the change condition of the aluminum level, and after one-year tracking measurement, a result shows that a small amount of deposition is generated at the furnace bottom at the middle seam of the electrolytic cell, the leg stretching is not abnormal, and the electrolytic cell runs stably in a curve mode.

The control and adjustment of high voltage in 1 ~ 90 days of first time period specifically are: and within 1-90 days, adjusting the voltage from the high voltage of 6.5V to the normal voltage of 3.95V. The voltage mainly provides heat energy for the electrolytic cell, the furnace side is formed under different temperature gradients, practice proves that three months is the optimal time for forming a firm hearth, the voltage is adjusted from 6.5V at high voltage to 3.95V at normal voltage within 1-90 days, and the specific adjustment method is as follows:

Adjusting and controlling the electrolyte level, the aluminum level, the molecular ratio level and the bath temperature in the first time period of 1-90 days, wherein the specific adjusting method is as shown in the following table;

molecular ratio control requires no aluminum fluoride addition for three months from the end of start-up.

the condition that the high molecular ratio forms a firm hearth is the primary condition for ensuring that the high molecular ratio is not added, the molecular ratio is controlled by adding sufficient sodium carbonate after the start of the electrolytic cell, the molecular ratio is improved to 3.0 once, and the aluminum fluoride is not added in three months at the later stage. Adding aluminum fluoride after the macromolecule is kept for three months, preparing to calibrate the blanking amount of the aluminum fluoride according to the principle of 'precise control', accurately measuring and calculating the quality of liquid electrolysis in the cell, scientifically calculating the addition amount of the aluminum fluoride during the down-regulation of the molecular ratio, sampling every week, testing and tracking the change condition of the molecular ratio, ensuring that the molecular ratio is slowly adjusted to a specified range, and ensuring that the electrolytic cell does not have a long-shell head-pack phenomenon during the adjustment of the molecular ratio.

And adjusting and controlling the electrolyte level, the aluminum level, the molecular ratio level and the bath temperature of each time period from the second time period to the eighth time period, wherein the specific adjusting method is as follows:

Compared with the prior art, the invention has the following advantages:

The invention provides a control idea for operating an aluminum electrolytic cell by adopting medium-high aluminum level and medium-high voltage. The low aluminum level often causes the electrolysis trough unstable because of the magnetic field is bigger than normal in the trough, and the high aluminum level dispels the heat and often makes the electrolysis trough cold partially greatly, and the stove bottom deposits much, adopts well high aluminum level to avoid the harmful effects that low aluminum level and high aluminum level brought. The medium and high voltage is adopted to supplement the medium and high aluminum level, the voltage determines the heat income of the electrolytic cell, and the electrolysis temperature can be ensured by matching with the aluminum level.

The invention provides a control point for the formation of a furnace side. The control furnace side is mainly formed at the later stage of the start of the electrolytic cell, and the high cell temperature is naturally formed within 90 days through the control of high molecular ratio, low aluminum level and reinforced anode heat preservation.

The invention provides an aluminum cell operation molecular ratio control point. The molecular ratio plays a decisive role in the formation of the furnace side, the high molecular ratio is a necessary condition for forming a firm furnace side, and the formation of the furnace side requires 90 days, so the high molecular ratio must be ensured within 90 days for forming the furnace side, and the molecular ratio is stably and slowly reduced in an excessive period.

The current efficiency is improved by 1 percent, the direct current power consumption is reduced by 150kwt/tal, and the anode gross loss is reduced by 5 kg/tal; the production and operation cost is reduced, and the economic benefit is improved.

Detailed Description

the invention has the advantages that the bath condition is very stable, the furnace bottom is clean, the temperature of the side steel window, the cathode steel bar and the furnace bottom of the electrolytic bath can reach the design requirement, and the economic and technical indexes are stable and good after the 500KA series electrolytic bath in certain aluminum plant runs for one year.

Dividing the normal production period of the electrolytic cell into eight time periods according to the cell age, wherein the eight time periods are respectively as follows: the first time period is 1-90 days; the second time period is 91-120 days; the third time period is 121 days to 150 days; the fourth time period is 151 days to 1 year; the fifth time period is 1 to 2 years; the sixth time period is 3-4 years; the seventh time period is 5 years to 8 years; the eighth time period is more than 8 years;

The voltage level, electrolyte level, aluminum level, molecular ratio level and cell temperature for each time period were adjusted and controlled separately.

In the first time period of 1-90 days, the control and adjustment of the medium-high aluminum level and the medium-high voltage are adopted to naturally form the furnace wall of the electrolytic cell. The control and the adjustment of high voltage in 1 ~ 90 days of first time quantum specifically are: within 1-90 days, the voltage is adjusted from 6.5V of high voltage to 3.95V of normal voltage, and the specific adjustment method is as follows:

adjusting and controlling the electrolyte level, the aluminum level, the molecular ratio level and the bath temperature in a first time period of 1-90 days, wherein the specific adjusting method is as shown in the following table;

Claims

1. a method for controlling the production process of an aluminum electrolytic cell is characterized by comprising the following steps: the normal production period of the electrolytic cell is divided into eight time periods according to the cell age, and the voltage level, the electrolyte level, the aluminum level, the molecular ratio level and the cell temperature of each time period are respectively adjusted and controlled.

2. The aluminum electrolysis cell production process control method according to claim 1, characterized in that: the eight time periods are respectively as follows: the first time period is 1-90 days; the second time period is 91-120 days; the third time period is 121 days to 150 days; the fourth time period is 151 days to 1 year; the fifth time period is 1 to 2 years; the sixth time period is 3-4 years; the seventh time period is 5 years to 8 years; the eighth time period is more than 8 years.

3. The aluminum electrolysis cell production process control method according to claim 2, characterized in that: and in the first time period of 1-90 days, the control and adjustment of the medium-high aluminum level and the medium-high voltage are adopted, so that the furnace wall of the electrolytic cell is naturally formed.

4. The aluminum electrolysis cell production process control method according to claim 3, characterized in that: the control and adjustment of high voltage in 1 ~ 90 days of first time period specifically are: and within 1-90 days, adjusting the voltage from the high voltage of 6.5V to the normal voltage of 3.95V.

5. the aluminum electrolysis cell production process control method according to claim 4, characterized in that: within 1-90 days, the voltage is adjusted from 6.5V at high voltage to 3.95V at normal voltage, and the specific adjustment method is as follows:

6. The aluminum electrolysis cell production process control method according to claim 2, characterized in that: adjusting and controlling the electrolyte level, the aluminum level, the molecular ratio level and the bath temperature in the first time period of 1-90 days, wherein the specific adjusting method is as shown in the following table;

7. the aluminum electrolysis cell production process control method according to claim 2, characterized in that: and adjusting and controlling the electrolyte level, the aluminum level, the molecular ratio level and the bath temperature of each time period from the second time period to the eighth time period, wherein the specific adjusting method is as follows: