Aluminum oxide feeding and concentration controlling method for aluminum electrolysis cell

A technology of aluminum electrolytic cell and control method, which is applied in the field of aluminum electrolysis, can solve problems such as constant control of alumina concentration and pole distance, drift of alumina concentration, and increase of anode effect in super-large aluminum electrolytic cells, so as to prevent concentration drift, Reduce thermal shock and achieve precise control effects

Pending Publication Date: 2021-03-30
SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the control mode involved in the patent, as the electrolysis proceeds and the pole distance gradually decreases, the "concentration pressure drop" of the alumina in the electrolyte will continue to rise under the condition of only controlling the cell voltage, causing the alumina concentrat

Method used

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  • Aluminum oxide feeding and concentration controlling method for aluminum electrolysis cell
  • Aluminum oxide feeding and concentration controlling method for aluminum electrolysis cell
  • Aluminum oxide feeding and concentration controlling method for aluminum electrolysis cell

Examples

Experimental program
Comparison scheme
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Example Embodiment

[0042] Example 1

[0043] like figure 2 As shown in the figure, an aluminum electrolytic cell alumina blanking and concentration control method of the present invention includes a pole change period, and then enters an under-over blanking period after the pole change period ends, and the under-over blanking period includes an under-volume period and an excess The under-over-feeding period is a half-cycle, first the under-feed period and then the over-feed period. After the lower limit of the alumina concentration is determined during the under-over-feed period, the concentration in the tank reaches the target concentration and then enters the benchmark feeding period. At the beginning of the blanking period, the initial blanking rate is given, and the resistance pole distance is compensated for multiple times during the benchmark blanking period, and the blanking rate is adjusted in real time between the two pole distance compensations.

[0044] The alumina concentration in ...

Example Embodiment

[0054] Example 2

[0055] like image 3 As shown, an aluminum electrolytic cell alumina blanking and concentration control method, including a pole change period, after the end of the pole change period, enter the under-over blanking period, the under-over blanking period includes the under-quantity period and the excess period, The under-over-feeding period is the full cycle. The under-supply period is followed by the over-supply period. After determining the lower limit of the alumina concentration in the under-volume period, the upper limit of the alumina concentration is determined after an over-supply period, and the concentration is double calibrated. After a period of The time is insufficient to discharge the material, so that the concentration in the tank reaches the target concentration and then enters the benchmark blanking period. The initial blanking rate is given at the beginning of the benchmark blanking period, and the resistance pole distance is compensated for...

Example Embodiment

[0064] Example 3

[0065] like Figure 4 As shown, the under-over-feeding period in Example 1 is a half cycle, the upper limit of the alumina concentration is 2.7%, the lower limit of the alumina concentration is 1.8%, a cycle period is 6 hours, and the real-time adjustment of the reference feeding rate When the cell voltage is constant, the reference blanking rate is adjusted in real time according to the cell voltage change rate dV / dt: when (dV / dt)×Δt>σ, adjust NB to be NB-ΔNB; when (dV / dt)×Δt When <-σ, adjust NB to be NB+ΔNB, where Δt is the calculation time step taken, σ is the allowable voltage error, NB reference blanking time interval, and ΔNB fine-tuning amount for each time interval.

[0066] Take a 500kA electrolytic cell as an example to describe the real-time adjustment of the reference blanking rate in detail:

[0067] For example, the calculated time step Δt is 20 seconds, the allowable voltage error σ is 12 mV, the reference blanking time interval NB is 70.2 s...

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Abstract

The invention relates to an aluminum oxide feeding and concentration controlling method, in particular to an aluminum oxide feeding and concentration controlling method for an aluminum electrolysis cell and belongs to the field of aluminum electrolysis. After the lower limit of the concentration of the aluminum oxide is determined in the insufficient-excessive feeding period, the concentration inthe cell is made to reach the target concentration, and then a reference feeding period is executed; an initial feeding rate is given at the beginning of the reference feeding period, multiple times of electrode lifting compensation is conducted on the resistor electrode distance in the reference feeding period, and real-time adjustment of the feeding rate is conducted between two times of electrode distance compensation. The aluminum oxide feeding and concentration controlling method for the aluminum electrolysis cell has the advantages that the concentration change of the electrolysis cell is controlled within a required specified small range, and meanwhile the thermal shock of frequent excessive feeding and insufficient feeding on the electrolyte temperature and the superheat degree canbe effectively reduced; through the intermittent type insufficient-excessive feeding period, the concentration of aluminum oxide and the electrode distance are corrected, and concentration drifting is prevented; an electrode distance compensation means is provided to realize accurate control of the electrode distance balance of the electrolysis cell; and due to the fact that accurate control overthe aluminum oxide concentration and the electrode distance is achieved, the current efficiency can be improved beneficially, and the real-time efficiency of the electrolysis cell can be evaluated according to the reference feeding rate change curve of the whole day.

Description

technical field [0001] The invention relates to an alumina blanking and concentration control method, in particular to an alumina blanking and concentration control method for an aluminum electrolytic cell in the field of aluminum electrolysis. [0002] technical background [0003] In the production process of aluminum electrolysis, the feeding and concentration control of alumina is carried out in the form of alternating over and under, and the concentration of alumina in the whole tank is controlled between the upper limit and the lower limit for periodic changes, such as figure 1 As shown, the theoretical basis is the characteristic curve relationship between alumina concentration and tank resistance. This control method is widely used in aluminum electrolysis enterprises. In recent years, with the continuous increase of the capacity and size of the electrolytic cell, it is difficult to meet the ideal requirements for indicators such as current efficiency and DC power con...

Claims

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Application Information

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IPC IPC(8): C25C3/20C25C3/14
CPCC25C3/20C25C3/14
Inventor 杨晓东赵志彬陶绍虎王富强张钦菘
Owner SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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