In Situ Monitoring of Pit Gas Composition During Baking of Anodes for Aluminum Electrolysis

Abstract

Carbon anodes, which are consumed in aluminum electrolysis, are fabricated in separate anode plants where coke and pitch are mixed and vibrocompacted to green anode blocks before being baked in anode baking furnaces. The chemical environment inside an anode baking furnace is found to play an important role in the degradation of the furnace refractory lining. In this work, the pit gas composition was recorded during anode baking by an FTIR spectrometer and a gas chromatograph. The temperature dependence of the concentration of gas species during baking were obtained based on three measurement campaigns., The concentrations of CO and CO2 were found to be very dependent on temperature, where the concentration of CO peaked around the maximum firing temperature. In addition to varying concentrations of CH4 and HF, water was found in large amounts in the first part of the baking cycle. The water is to some extent originating from the cooling of the green anodes after vibrocompaction and is potentially important with respect to the chemical stability of the refractory lining. The variations in pit gas composition is related to operational parameters and discussed in relation to refractory degradation phenomena.

Influence of Atmosphere and Temperature on Polycyclic Aromatic Hydrocarbon Emissions from Green Anode Paste Baking

“…During anode baking the levels of oxygen in the flue gas have been measured to be between 3 and 11% . Anodes are also reported to be reactive with air and CO 2 during the electrolysis process, at temperatures between 520 and 960 °C.…”

“…During anode baking the levels of oxygen in the flue gas have been measured to be between 3 and 11%. 7 Anodes are also reported to be reactive with air and CO 2 during the electrolysis process, at temperatures between 520 and 960 °C. This level of oxygen and thermal conditions may however not be enough to facilitate complete combustion of PAH.…”

Coadsorption of CO and CH4 on the Au doped SnO2 (110) surface: a first principles investigation

“…The exploitation of fossil fules has accelerated the development of global economy [1][2][3][4]. Now, the pit gas [5,6], natural gas [7,8] and biogas [9,10] have been widely used in the industrial and civilian fields, which mainly constitute with carbon monoxide (CO) and methane (CH 4 ) gases. The CO gas is a toxic, harmful, odorless, colorless gas, which can rapidly binding to hemoglobin to form carboxy-hemoglobin, limiting O 2 transport to tissues.…”