Weathering Crust Of Low-grade Rare Earth Ore Leaching Mass Transfer Process Optimization

Weathered crust elution-deposited rare earth ore was under40years of extensively andoverload mined, the richer and more accessible deposits of this rare earth resource gradually getmined in priority. With prolonged production period, this rare earth resource becoming more andmore dilution and appeared a lot of low grade Weathered crust elution-deposited rare earth ore(the rare earth grade is lower than0.08%), which is a refractory rare earth ores and hard to getfully used in the practical production process. So, in order to slove this problem, this paper slovethe Longnan weathered crust elution-deposited rare earth ore as research subjects, make stdutyand optimizing on it mass transfer process, to offer thory to support its fully used.This paper were frist study the mass transfer of the leaching process of Weathered crustelution-deposited rare earth ore, the result shows that when the leaching flow-rate at the low level,the longitudinal diffusion coefficient is the main factor influence the mass transfer effect. When theleaching flow-rate at the high level, the mass transfer impedance is the main factor influence the masstransfer effect. And also make study on the influence fators, such as leaching flow-rate, lixiviantconcentration, the ratio of liquid to solid and packed ore high. The result shows that the leachingwill get a optimal leaching mass transfer under the condition of leaching flow-rate0.38mL/min,lixiviant concentration4%, the ratio of liquid to solid is1:2.And in order to further more optimizing the mass transfer of the leaching process, thesesbania gum, a natural macromolecule compound, were taken as leaching aid agant to optimizethe leaching mass transfer. The result shows that the sesbania gum can effectly enhance the masstransfer of leaching process of weathered crust elution-deposited rare earth ore by reduce the masstransfer impedance coefficient. And under the effect of the sesbania gum, the lixiviant concentrationcan be cut down (from4%to3%), the leaching flow-rate can be rised (from0.38mL/min to0.42mL/min), reduce the ratio of liquid to solid (from1:2to2:5).By means of taking chemical modification on the sesbania gum to further more raise it poweron enhancing the leaching process. By comparison, the carboxymethyl sesbania gum is betterthan monoester phosphate sesbania gum. And under the effect of the carboxymethyl sesbaniagum, the lixiviant concentration can be cut down (from3%to2.5%), the leaching flow-rate canbe rised (from0.42mL/min to0.45mL/min), but has insignificant effect on cut down the ratio ofliquid to solid.By means of qualitative measures the contact angle and IR spectrum, the study on themechanism of carboxymethyl sesbania gum and sesbania gum on enhance the leaching processwere carried out. The results shows that the carboxymethyl sesbania gum and sesbania gum werevia absorb on the surface of Weathered crust elution-deposited rare earth ore to improving thehydrophilia of the ore, so that the leaching process will get a better mass transfer effect. The adsorb style of sesbania gum on the weathered crust elution-deposited rare earth ore is thephysical adsorption. And the adsorb style of carboxymethyl sesbania gum is chemisorption.