Coke–pitch interactions during anode preparation

Abstract

Highlights• Study of coke pitch interaction by XPS, FTIR and sessile-drop techniques.• Interactions of three cokes and two pitches were studied.• Studied calcined coke and coke-pitch by FTIR-DRIFT, not reported in published article.• Atomic wt% and functional groups present on coke and pitch surfaces analyzed by XPS.• Wetting was correlated with the functional groups and evidence of reaction found. AbstractThe information on the interactions between coke and pitch is of great value for the aluminum industry. This information can help choose the suitable coke and pitch pairs as well as the appropriate mixing parameters to be used during the production of anodes. In this study, the interaction mechanisms of pitch and coke at the mixing stage were studied by a sessile-drop test using two coal-tar pitches as the liquid and three petroleum cokes as the substrate. The results showed that the coke-pitch interactions are related to both pitch and coke chemical compositions. The contact angle of different coke-pitch systems decreased with increasing time and temperature. At high temperatures, decreasing the pitch viscosity facilitated the spreading of pitch and its penetration into the coke bed. The chemical behavior of petroleum cokes and coal tar pitches were studied using the FT-IR spectroscopy and XPS. The results showed that the wettability behavior of cokes by pitches depends on their physical properties as well as the presence of surface functional groups of coke and pitch which can form chemical bonds.

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

“…The dried coal dust samples were placed into ZrO 2 sampling tubes for future measurement. The test conditions were: a revolution speed of 5 kHz, the resonant frequency of a 13 C nucleus of 100.38 MHz, a sampling time of 0.0026 s, a delay time of 2 s and a scanning number of 10 240-20 480. The cross-polarization (CP) and Total Suppression of Sidebands (TOSS) techniques were applied.…”

“…To avoid the mineral materials affecting the test results, samples were treated using a deliming process to suppress the ash content below 1%. In order to comprehensively understand the information of the carbon skeleton, NUTS 98 soware was utilized to t and integrate the 13 C CP/ MAS NMR spectra of all the test samples, as seen in Fig. 1.…”

“…Based on the peak tting of the 13 C CP/MAS NMR spectra of the above samples ( Fig. 1), the carbon structural parameters of six kinds of coal dust are listed in Table 4.…”

Determination of halogens and sulfur in pitch from crude oil by plasma-based techniques after microwave-induced combustion

“…[2][3][4][5][6] The content of metals and non-metals in electrodes depends upon the level of these impurities contained in the respective raw materials (petroleum coke and/or recycled anode components).…”

“…Moreover, halogen determination in this matrix is still more difficult when considering the risks of losses and contamination during the sample preparation step. [2][3][4]10,14 Despite the fact that the determination of major elements, such as sulfur, in pitch can be carried out using elemental analyzers, 5,13,15,16 these instruments are not suitable for determination of other non-metals (e.g., Br and I). Moreover, there are no methods in the literature for pitch digestion for further simultaneous determination of halogens and sulfur.…”