The pre-baked anode block is made of petroleum coke and pitch coke as aggregates and coal tar pitch as the binder. It is used as the anode material for the pre-baked aluminum electrolytic cell. This kind of carbon block has been roasted and has a stable geometric shape, so it is also called a pre-baked anode carbon block, which is also called a carbon anode for aluminum electrolysis. The aluminum electrolytic cell that uses the pre-baked anode carbon block as the anode is called the pre-baked anode electrolytic cell, referred to as the pre-baked cell, which is a modern large-scale aluminum electrolytic cell.
The pre-baked anode electrolyzer and anode carbon block were born almost at the same time as modern aluminum smelting methods. In 1880, Hall of the United States and Heroult of France simultaneously proposed the cryolite-alumina melting aluminum smelting method. In 1888, the Pittsburgh Electrolysis Plant applied this aluminum smelting method to industrial production and built the world’s earliest pre-baked anode electrolysis cell. The anode carbon block used was made of charcoal as raw material and produced by the molding method. The cross-sectional area of a single anode was only 8-10cm2, its quality indicator is relatively backward. Since then, several countries including Switzerland, France, the United Kingdom, and Germany have used similar pre-baked anodes to produce aluminum by electrolysis.
The pre-baked carbon anode is usually installed in the upper part of the electrolytic cell, and a strong direct current of 60-300ka is passed through the carbon anode and introduced into the electrolyte. The resistivity of the carbon anode is 50-70 μΩ.m, plus the lead and contact resistance, the voltage drop on the carbon anode consumed during normal aluminum electrolysis production is 300-500mV, which accounts for 10%-15 of the electrolytic cell voltage drop %. At the part where the bottom of the carbon anode contacts the molten electrolyte, a complex electrochemical reaction (anode reaction) that decomposes alumina occurs. With the participation of carbon, the final products of the anode are CO and CO2. In aluminum electrolysis production, the average daily consumption of carbon anodes is 1-2CM. Regularly add new anode paste to the upper part of the electrolytic cell (for self-baked anode electrolyzers) or regularly replace pre-baked anodes (for pre-baked anode electrolyzers) as anode work The main content to keep the anode working continuously and normally.