Study On The Oxidation Characteristics And Raw Materials Characteristics Of Anthracite-based Carbon Anode

Due to the shortage of oil resourses, the cost of carbon anode increases. Ourcountry is rich in anthracite, so anthracite carbon anode is prepared by the way inwhich calcined anthracite replaced some petroleum coke. Not only werephysicalstructure and gasification reactivity of high temperature calcination low ash anthracitestudied, but also effects of anthracite on properties of coal pitch were researched. Inorder to reduce the consumption of carbon anode in aluminum electrolysis process,two kinds of additives (B2O3, B2O3+Al2O3) were selected to add to the anode. Themain research results are as follows:As the calcinated temperature increased, surface areas and pore volumes ofanthracite presented a decresing tendency and gasification reactivity decreased.Increasing calcinated temperature resulted in the more ordered carbon crystallinestructure, especially above1500℃. To achieve the same degree graphitization aspetroleum coke, anthracite required higher calcinations temperature. Consideringreducing the consumption of carbon anode,1700℃calcinations anthracite with lowgasification reactivity was recommended to replace pitch coke.Anthracite changed pyolysis condensation behavior of coal tar pitch, resulting inthe enhancement of coking value. Because of addition of anthracite, the layer spacingof carbon tar pitch decreased and the layer stack height increased, resulting in moreorderd carbon crystalline structure. So addition of anthracite was in favour of reducingthe consumption of coal pitch, and then reducing the consumption of carbon anode.B2O3was not only an inhibitor but also a catalyst of carbon oxidation. AlthoughB2O3with2%improved CO2reaction activity of petroleum coke and anthracite, CO2reaction activity difference between anthracite, petroleum coke and pitch coke shrank.B2O3+Al2O3with2%decreased CO2reaction activity of pitch coke and petroleumcoke and shrank CO2reaction activity difference between anthracite, petroleum cokeand pitch coke.CO2oxidation of coal-based carbon anodes proved additives of B2O3and B2O3+Al2O3decreased slough degree and consumption. Of all the doping B2O3anodes, ability of CO2oxidation resistance of1%was strongest. Of all theB2O3+Al2O3anodes, ability of CO2oxidation resistance of1.5%B2O3+Al2O3wasstrongest. Because of addition of additives, CO2reaction activity difference betweenanthracite, petroleum coke and pitch coke shrank, resulting in reducing carbon anodeconsumption. The influence of additives on carbon anode CO2reactivity mechanism can bedescribed as: from the perspective of physical effect, the gap of carbon anode and CO2reaction channel were blocked, reducing surface area and lowering consumption.Chemical action existed in effect of additives on carbon anode. The redistribution of πelectrons in the presence of additives inhibited oxidation of carbon anode or shrankCO2reaction activity difference between anthracite, petroleum coke and pitch coke,resulting in reducing carbon anode consumption.