The Study Of Low-cost Prebaked Anode For Electrolytic Aluminum

The demand of pre-baked anode increases with the rapid development of aluminum industry. The quality of pre-baked anode will have direct effects on production of aluminum electrolysis and indexes of economy and technology. How to decrease the cost of anode production and how to improve the quality of pre-baked anode have been become big challenges in the aluminum industry.At present the supply of bulk petroleum coke which adapts to produce prebaked anode （including other carbon materials） used for electrolytic aluminum becomes less and less and the price rises rapidly. So how to reduce the production cost of prebaked anode becomes one difficult problem of the aluminum industry. However fuel grade petroleum coke which does not apply to produce carbon material is easily available （more than 70 percent of the total output of petroleum coke）. The difference between the prices of two raw materials is about 1,000 Chinese yuan per ton.In this paper, we select low-cost fuel grade petroleum coke as the main raw material, adding special binder, and then through the high-temperature heat treatment, raw materials with high quality which suit for producing prebaked anode can be obtained. Mainly basing on these materials, coal tar pitch for the binder, with some of pre-conditioned anthracite, through the processing of kneading,forming, baking and so on, prebaked anode with low-cost and good performance used for electrolytic aluminum would be produced successfully. And then we did comprehensive test on its various physical and chemical indicators, such as bulk denstity, true density, ash content, specific resistance, compressive strength, permeability, air reactivity, CO2 reactivity, thermal analysis, SEM, and so on.The performance of prebaked anode samples which have been produced by using low-price and inferior coke fines as main materials for the first time: bulk density is 1.52g/cm³, true density is 2.03g/cm³, ash content is 0.64 percent, specific resistance is 59.0μΩ.m, compressive strength is 38.2MPa, permeability is 5.49nPm, air reactivity is 80.8 percent. These main indicators have reached the requirements of national announced new standard YS / T 285-2007.It’s the first effort to prepare pre-baked carbon by using parts of anthracites to replace petroleum coke materials. The bulk density of anode sample prepared with some anthracites is 1.50g/cm³, specific resistance is 72.3μΩ.m, compressive strength is 28MPa, air reactivity is 59.38%, CO₂ reactivity is 51.85%. The properties of anode samples prepared with some treated anthracites（the ash content of anthracites decreased to 0.87% from 2.27%）, such as bulk density, specific resistance, compressive strength, air reactivity and CO₂ reactivity, which are respectively 1.52g/cm³ã€68.7μΩ.m、37.3MPa、66.83%、81.78%, they all improved comparing with anode samples prepared with untreated anthracites.It can be learned from scanning electron microscopy photographs that prebaked anode which were prepared with low-cost fuel grade petroleum coke are uniformty and compaction. The pre-baked anodes prepared with marinated anthracites contain little ash, and are uniformty and compaction. Compared to the active production of prebaked anode in the international market, the output cost of prebaked anode manufactured by fines coke formation can be reduced by about 400 Chinese yuan per ton. With the present annual output of domestic prebaked anode 8 million tons, if the annual output of 20% prepared by this study were used in the anode production which would have 6.4 hundard million yuan of diect economic benefits; and prebaked anode manufactured by some treated anthracites also has potentially huge economic and social benefits.