本文選題：稀土　切入點(diǎn)：銨態(tài)氮　出處：《江西理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：江西贛南地區(qū)有著十分豐富的的風(fēng)化殼淋積型稀土礦,近年來普及應(yīng)用的原地浸礦工藝中硫酸銨溶液的大量使用對環(huán)境造成了嚴(yán)重的污染。因此,探究銨態(tài)氮在土壤中的遷移規(guī)律及其形態(tài)變化具有非常重要的意義。本實(shí)驗選取了龍南足洞稀土礦土壤,該原礦土壤中的稀土60%-90%為水合或羧基水合離子狀態(tài)吸附于高嶺石及云母中,是風(fēng)化殼淋積型稀土礦的原地浸礦的化學(xué)浸取基礎(chǔ)。文章采用靜態(tài)、動態(tài)與土柱實(shí)驗結(jié)合的方式,先探究土壤吸附銨態(tài)氮的性能,然后在間歇式淋濾作用下探究銨在土壤中的形態(tài)與遷移特征,控制不同理化性質(zhì)如pH、浸礦劑濃度、滴浸速度探究土壤中銨態(tài)氮的遷移規(guī)律。結(jié)果表明:(1)離子型稀土土壤吸附銨態(tài)氮滿足Langmuir模型,動力學(xué)滿足準(zhǔn)二級動力學(xué)方程,說明土壤吸附銨態(tài)氮是單分子層吸附,以及以化學(xué)吸附過程控制為主。(2)離子型稀土銨態(tài)氮形態(tài)主要以交換態(tài)銨為主,水溶態(tài)銨與固定態(tài)銨的含量較少且達(dá)到吸附飽和的時間較短,土壤中硝態(tài)氮含量極少,土壤柱中發(fā)生硝化反應(yīng)可以忽略,土壤中主要以吸附銨態(tài)氮交換稀土為主。(3)濃度不同改變了土壤中銨態(tài)氮吸附平衡的時間與稀土回收率,在實(shí)際的浸液過程中可以考慮“先淡后濃”的注液方法,不僅可以防止在達(dá)到注入低濃度前的解吸過程,且節(jié)約浸礦劑,提高稀土回收率。(4)速度不同幾乎不改變土壤中的銨態(tài)氮達(dá)到飽和的時間,但是對稀土回收率有較大影響,因此在實(shí)際的浸液過程中可以考慮先慢后快的注液方式。(5)pH值沒有改變銨態(tài)氮在土壤中的遷移特征,但是對稀土回收率有一定的影響,由于硫酸銨溶液本身的pH值在5.5-6之間,因此在實(shí)際的注液過程中,可以適當(dāng)降低溶液pH值或者不調(diào)節(jié)就能提高稀土回收率。利用SPSS軟件可以較好的擬合銨態(tài)氮隨深度隨時間的變化。(6)銨態(tài)氮的遷移可以分為5個帶,與稀土浸出機(jī)理一致。
[Abstract]:There are abundant weathered crust leaching rare earth ores in south Jiangxi province. The extensive use of ammonium sulfate solution in the in-situ leaching process, which has been widely used in recent years, has caused serious pollution to the environment. It is of great significance to study the migration and speciation of ammonium nitrogen in soil. 60-90% of the rare earth in the soil of the ore is adsorbed in kaolinite and mica by hydration or carboxyl hydration ion state, which is the basis of chemical leaching of weathered crust leaching rare earth ore. The static, dynamic and soil column experiments are adopted in this paper. In order to control different physical and chemical properties, such as pH, concentration of leaching agent, the properties of ammonium adsorption in soil were investigated firstly, then the characteristics of ammonium morphology and migration in soil were studied under intermittent leaching. The migration of ammonium nitrogen in soil was investigated by drip leaching rate. The results showed that the adsorbed ammonium nitrogen in the ion type of rare earth soil met the Langmuir model, and the kinetics satisfied the quasi second-order kinetic equation, which indicated that the adsorbed ammonium nitrogen in the soil was monolayer adsorbed. The ion type of rare earth ammonium nitrogen was mainly exchangeable ammonium, the content of water-soluble ammonium and fixed ammonium was less and the time to reach adsorption saturation was shorter, and the nitrate nitrogen content in soil was very little. The nitrification reaction in soil column can be neglected. The concentration of adsorbed ammonium nitrogen exchange rare earth in soil changed the time of adsorption equilibrium of ammonium nitrogen and the recovery rate of rare earth. In the actual leaching process, the liquid injection method of "light first and then concentrated" can not only prevent the desorption process before the injection of low concentration, but also save the leaching agent. The rate of increasing the recovery rate of rare earth elements almost does not change the time of saturation of ammonium nitrogen in soil, but it has great influence on the recovery rate of rare earth elements. Therefore, in the actual leaching process, the pH value of slow injection and then quick injection can not change the migration characteristics of ammonium nitrogen in soil, but it has a certain effect on the recovery of rare earth, because the pH value of ammonium sulfate solution itself is between 5.5-6. Therefore, in the actual liquid injection process, the pH value of the solution can be reduced properly or the recovery rate of rare earth can be improved if the solution pH value is not adjusted. The transfer of ammonium nitrogen can be divided into 5 bands by using SPSS software to fit the change of ammonium nitrogen with depth with time. It is consistent with the mechanism of rare earth leaching.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X753;X53;O647.3

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