Preparation Of Coal-based Electrode Material And Application In Leaching Gold Tail Solution

Low rank coal in Northern Shaanxi and direct coal liquefaction residue wereadopted as the raw materials for preparation of the electrode material by coldbriquetting process. And it was applied in the electro-adsorption process of the tail goldcyanide solution, which laid a foundation for the comprehensive utilization of thecyanide waste water.In the preparation experiments of carbonized material used as coal-based electrodematerial, the effects of the added liquefaction residue proportion, briquetting pressureand added water proportion, dwell time, carbonization temperature and holding time onthe carbonized material yield, compressive strength and iodine adsorption value weremainly investigated. The results showed the compressive strength, yield, iodineadsorption value can reach0.298MPa,73.37%,40.56mg·g-1separately with the addedliquefaction residue proportion of20%, forming pressure of8MPa, added waterproportion of10%, carbonization temperature of800℃and holding time of90min.Carbonized material was activated by steam and modified by nitric acid. Influencesof steam flow, activation temperature and activation time and the modifying conditions,including nitric acid concentration, processing time, temperature on the carbonizedmaterial yield, compressive strength and iodine adsorption value were mainlyinvestigated. The carbonized material was characterized by N2adsorption-desorption,SEM, FT-IR, XRD. The results showed that when the activation temperature of thesteam is800℃, activation time is1.5h, the iodine adsorption value, yield, compressivestrength, specific surface area and total pore volume of the produced coal-basedelectrode material can reach820mg·g-1,36.63%,0.0768MPa,509m2·g-1,0.35cm3·g-1separately. When the nitric acid concentration is40%, the modified time is8h, the strength of the produced coal-based electrode material, iodine value, yield, specificsurface area,total pore volume can reach0.234MPa, reaches301.72mg·g-1,67.64%,256m2·g-1,0.127cm3·g-1and0.234MPa separately.Application experiments of the electrode material in leaching gold tail solutionfocused on the effects of the electrode types, voltage and concentration, results showedthat Cu ion and CN-removal rate can reach90.62%and75.5%separately in afterprecipitation solution, Cu removal rate of90.62%, CN-removal rate of75.5%.analyingthe adsorption mechanism of Cu by kinetics and thermodynamics. Cu adsorptionprocess conformed to the second-order kinetic model and adsorption capacity is134mg·g-1. Thermodynamic results showed that Cu adsorption process conformed toFreundlich the isothermal model. If n＞1, there exist a stong affinity between the Cuand electrode. The adsorption thermodynamic parameters ΔG0<0, ΔH0<0, ΔS0<0indicated that the liquid process from the disordered state to an ordered state transitionwith spontaneous and exothermic.