Preparation Of Expanded Graphite And Its Adsorption On Collectors

Graphite intercalation compounds can be obtained by oxidative intercalation using natural flake graphite through chemical or electrochemical methods.With high temperature calcination,the volume of graphite intercalation compounds increase by tens to hundreds of times,due to the instantaneous impetus of the inserts between the graphite layers;and therefore porous worm materials are produced.Expanded graph-ite,known as the most promising new materials in the 21st century,is widely used in many industries,because of its excellent characteristics.Flotation wastewater contains a large number of flotation agents,which are more difficult to process.If disinterested,serious pollution may be caused,and thus could not meet the requirements of environmentally-friendly of mines production.At pre-sent,the expanded graphite is mostly used for the adsorption of oil,and as for ad-sorbents of other pharmaceutical contaminants are also increasingly valued.However,studies on adsorption of modified expanded graphite to treat the collectors in wastewater of mineral processing have not been reported.Hydrogen peroxide,sulfuric acid and ammonium nitrate are used to prepare ex-panded graphite.The process of preparing the optimum expanded volume(255mL/g)was obtained by controlling the conditional experiments of single variable.And the expanded graphite was characterized by scanning electron microscopy to deeply un-derstand the pore structure of expanded graphite.The modified expanded graphite was obtained by the modified process using FeCl3 under the said optimum conditions.In this paper,the adsorptions of modified expanded graphite on the flotation collec-tors of GYB(benzoic hydroxamic acid)and xanthate are studied.The adsorption behavior of modified expanded graphite on benzohydroxamic acid and xanthate was studied under different experimental conditions.The results showed that the adsorption equilibrium time of GYB was 5.5h,the maximum adsorp-tion capacity was 16.31mg/g,and the GYB removal rate was 70.7%.The adsorption of xanthate showed that the adsorption equilibrium time was 60min,the maximum adsorption capacity was 18.87mg/g,and the max removal rate of xanthate was 94.24%.The adsorption kinetic was simulated by first-order kinetic model and second-order kinetic model.The results show that the second-order kinetic model is more suitable for expression of the adsorption process of the expanded graphite.In addition,the adsorption thermodynamics shows that the adsorption of benzoic hydroxamic acid on the expanded graphite was in accordance with the Freundlich adsorption model,while the adsorption of xanthate was in accordance with the Langmuir adsorption model.