Mechanism of the impact of hydrogen/oxygen bubbles in the separation and hydrogen production of coal macerals electroflotation
Electroflotation technology is an effective way to achieve efficient separation of coal macerals and it is also a hydrogen and oxygen production technology with significant advantages.Electrolytic bubbles in electroflotation are carriers for flotation separation and are also effective hydrogen/oxygen products.This study explored the impact mechanism of electrolytic bubbles on the separation efficiency of macerals in high-inertinite coal electroflotation.Induced timer,infrared spectroscopy,contact angle measurement,and gas chromatography were used to investigate the selectivity of hydrogen and oxygen bubbles for coal macerals,and the impact of electrochemical reaction on coal structure,flotability and gas product composition.The results showed that the yield and vitrinite content of the concentrates obtained by electrolytic hydrogen bubble flotation were higher than those with oxygen bubbles,and the corresponding vitrinite recovery rate was also higher than that with oxygen bubbles.The electrolytic action during the electroflotation process improved the surface structure of coal macerals,causing changes in wettability.The cathode region of electroflotation had an electrochemical reduction effect on coal,which could reduce the hydrophilic functional groups such as—OH,—COOH,and C==O in coal,thereby increasing the contact angle of coal samples and reducing the induction time of hydrogen bubbles on coal,thus increasing the floatability of coal.And the anode region had the opposite effect.In the electroflotation process of coal slurry,hydrogen gas with a purity of>94%and oxygen gas with a purity of>96%were obtained,and the purity of the gas products using vitrinite as electrolyte was higher than that with inertinite,but the inertinite could achieve a higher gas production rate.The two-stage series process was used for the electroflotation of coal macerals,and it had a maximum comprehensive efficiency of 83.7%for flotation separation.The recovery rate of vitrinite in the concentrates was 86.7%,and the recovery rates of the two sink products were 41.6%and 54.9%,respectively,while the hydrogen production rate reached 6.49mL/(min∙cm2).
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