Study On The Adsorption Of Ammonium Nitrogen By Ionic Rare Earth Soil

Gannan region in Jiangxi Province has plenty of weathering crust strain amass-type rare earth ore which are currently mined by the in-situ leaching mining method using a large number of ammonium sulfate solution as the electrolyte and has caused serious pollution to the environment.So,it is very significant to explore the migration of ammonium nitrogen with rules and morphologic change in the soil.In this paper,an ion-absorbed rare earth mine soil in the south of China was selected as object and the soils between 60% to 90% are in hydration or carboxyl state adsorbed on kaolinite and mica.This is the chemical theoretical of in-situ leaching process of weathered crust elution-deposited rare earth ore.In this paper,taking static?dynamic experiment and indoor column simulation experiment method to explore ammonia-nitrogen adsorption ability in the soil firstly,and then study the morphology and migration characteristics under the control of different physical and chemical properties such as pH?ore leaching concentration?dripping leaching rate in the effect of intermittent natural leaching.The results show that:(1)It meets the adsorption of Langmuir equation and means that ammonia nitrogen adsorption on the rare earth soil is a single molecular layer,the adsorption is consistent with a pseudo-second-order kinetic equation,which means the adsorption is mainly a chemisorption rate controlling process.(2)The Ionic rare earth ammonia is mainly in the exchangeable form,the contents of clay-fixed ammonium and the proportion of soluble ammonium are less which can reach the adsorption saturation in a shorter time.Due to the contents of nitrate-nitrogen in rare earth soil are less,the adsorption of ammonia nitrogen is obvious while the nitrification effect can be neglected.(3)Differences of concentrations changed the adsorption equilibrium time and the leaching rate of RE.So,we can consider the leaching method with thick after the weak,it not only can prevent desorption process before low concentration but also can reduce leaching reagents and enhance the leaching rate effectivity.(4)Different speeds change little of ammonium nitrogen saturated time in the rare earth soil which can save ore leaching and improve the rare earth leaching rate.Therefore in the process of actual immersion can consider slow firstly,and then quick way of injection liquid.(5)pH value did not change the migration characteristics of ammonium nitrogen in the rare earth soil,but have a certain influence on rare earth leaching rate.Therefore in the process of the actual injection liquid can decrease the soil pH value or don't regulate because the ammonium sulfate solution pH value is between 5.5 and 6.By using SPSS software can better fitting ammonium nitrogen with depth change over time.(6)The soil mechanism of adsorption of ammonium nitrogen is similar with leaching process of rare earth which can be divided into five belts.