Method for controlling stability and uniformity of aluminum oxide concentration in aluminum electrolysis cell

Abstract

The invention discloses a method for controlling stability and uniformity of aluminum oxide concentration in an aluminum electrolysis cell. The method comprises the following steps of: firstly, setting the aluminum oxide concentration control target at a low resistance concentration area, and performing two main control processes, namely long-term 'blanking as required' and short-term 'concentration check', to realize feeding as required in time in the aluminum electrolysis cell and stable operation in the low resistance concentration area; secondly, performing online measurement of current distribution on each anode of the electrolysis cell, and adjusting the blanking proportion of each blanking point according to the consumption rate of aluminum oxide of the anode around each blanking point to realize uniform distribution of the aluminum oxide concentration in the space; and thirdly, improving a blanking device and a blanking manner to reduce aluminum oxide sediment generated by accumulation at the blanking port. The method is favorable for stable, efficient, low-voltage, low-power consumption and low-discharge production operation of the aluminum electrolysis cell.

Description

technical field [0001] The invention relates to the field of aluminum electrolysis, in particular to a method for controlling the concentration of alumina in an aluminum electrolytic cell to be stable and uniform. Background technique [0002] In the process of aluminum electrolysis production, the control of alumina concentration is extremely important. When the concentration of alumina is too low, it is easy to cause the anode effect, which will lead to the increase of power consumption, the rise of the tank temperature, and the increase of greenhouse gas emissions. Unstable conditions such as swinging and cold troughs. At present, the control of alumina concentration in large-scale aluminum electrolytic prebaking tanks is mainly based on the alumina concentration-resistance control curve. The characteristic resistance curve of alumina concentration is divided into several concentration areas according to the concentration from low to high: effect area, sensitive area, I...

AI Technical Summary

Problems solved by technology

Due to the inconsistency of alumina consumption throughout the electrolytic cell due to the uneven current distribution, and the existence of a concentration diffusion gradient from the feeding point to the surroundings, the distribution of alumina concentration in the cell is not uniform

Alumina accumulation is easy to form at the bottom of the furnace corresponding to the current feeding device, and it is easy to form precipitation in the tank over a long period of time, which affects the stability of the electrolytic cell

The current control system has no solution for the uneven concentration of alumina in the space of the electrolytic cell

[0003] With the implementation of national energy conservation and emission reduction policies, it has become a general trend to reduce consumption through low-voltage operation in the electrolytic aluminum production process with high energy consumption. While the traditional control system controls the alumina concentration in the sensitive area, it also controls the electrolytic cell at a relatively low temperature. The high-resistance area corresponding to the concentration is not conducive to the further reduction of the cell voltage; and the continuous switching of a large number of excessive and under-feeding cycles makes the electrolytic cell always run in a periodic fluctuating state; when the electrolytic cell concentration When fluctuating to a relatively low level, due to the inhomogeneity and unequal consumption of the alumina concentration in the electrolytic cell, the local alumina concentration will be too low; Electrolytic production has many very negative effects