Study On Leaching Characteristics Of Ion-adsorbed Rare Earth Ore-water Interface And Its Enhanced Leaching Mechanism

Over the past 40 years,the research on the development and utilization of the ionadsorption type rare earth ore has been rapidly developed,which established the rare earth extracting method taking the in-situ leaching as the representative.However,rare earth extracting is so simple that most of the work concentrates on the optimization of leaching technology.Till now,the study of the leaching mechanism is insufficient.Moreover,the clay compositions of minerals(active site)are diversified with uneven distribution.Except that,the ultralow content of rare earth in ore makes it difficult to use modern spectrum to analyze.All of the above aspects bring greater difficulties to strengthen the research on the rare earth leaching mechanism from microcosmic level.On the basis of the relevant theories of the mineral-water interface chemistry,this thesis took the clay mineral component as the main research object,conducted the research and analysis on the leaching mechanism of ion-adsorption type rare earth ore,and provided the theoretical supports for the high-efficiency green development for green usage of the ion-adsorption type rare earth ore.At first,this thesis conducted the analysis and research on the static leaching characteristics of the ion-adsorption type rare earth ore on the basis of the ion exchange leaching theory.The results show as follows: according to the fact that the leaching agent in high concentration is usually applied in the leaching system of the rare earth,when evaluating the properties of the leaching agent as per the ion exchange equilibrium,the influence of the interaction between anion and cation on the effective concentration of the cation should also be taken into account in addition to considering the cationic exchange ability and the coordination of anions in the leaching agent.Except that,the initial p H value of the leaching system has produced a more complex effect on the leaching process of rare earth.It is preliminarily assumed that this effect is relevant to the physicochemical properties of the mineral surface.Then,the research results of the physicochemical properties on the mineral surface of the ion-adsorption type rare earth ore indicate as follows: the active reaction sites in minerals are mainly concentrated in kaolinite clays,whose surface have active groups,such as aluminol group(? Al OH),strong aluminol group(? Al2OH),which can influence the variable positive and negative charge on the surface of minerals in aqueous solution through the protonation or deprotonation reaction.The rare earth ions can produce specific adsorption at this group site;the permanent negative charge of minerals is concentrated on the clay's surface of the siloxane,which can adsorb the rare earth ions by the electrostatic interaction in the form of ion exchange.In addition,p H and ion concentration of the solution system are the main influencing factors of the variation of the charge density on the mineral surface.Both of them have abnormal effects on the charge properties of the mineral surface,which are difficult to explain by the existing theory of the electric double layer.It can be conducted that there are other external forces that have a function on it and this function may affect the ion exchange process of the rare earth on the mineral surface.The coordination adsorption of SO42-on the mineral surface obviously reduces the positive charge density on the mineral surface,which enables the ion adsorption behavior on the mineral surface to become more complicated.Subsequently,this thesis analyzes the effects of the mineral interaction effect on the rare earth's leaching through the accumulation regularity between the minerals.The research shows that p H and electrolyte concentration in the aqueous solution will affect the aggregation behavior of the mineral surface and then affect the leaching process of the rare earth.Usually,the leaching of the rare earth ions is conducted in the electrolyte solution of Medium or high concentration,so the apparent hydration force between the mineral surfaces will inhibit the leaching of the rare earth;On the basis of this,also the dissolution of H+ on the mineral surface structure of the aluminum element should to be considered;when the electrolyte concentration is very high,the electric double layer is strongly compressed,and the p H value is more than 4.5,we need to consider the surface aggregation on the mineral same charge as well as the inhibition of the electrostatic repulsion between ions adsorbed on mineral surfaces on the leaching of the rare earth ions.Finally,this thesis conducts the research on the enhancement leaching effects of the organic acid on the rare earth.The results display that the organic acid in very low concentration has obvious effects on the leaching process of the rare earth,and its enhancement effects are mainly reflected on the influence of the organic acids on the charge properties of the mineral surface as well as the weakening effects of the hydration on the mineral surface.In summary,the leaching mechanism of ion-adsorption rare earth is implemented a qualitative analysis in this research,which will provide relevant theoretical supports for the high-efficiency and green development of this resource.