Study On The Phase Composition Of Rare Earth Tailings And Enrichment Technology Of Rare Earth In Mianning, Sichuan Province

Rare earth is known as the industrial “vitamin”, it is applied to the field of high-tech such as the electronic information, biotechnology, energy technology. At the time, it is also the national defense construction materials. With the increasing demand of rare earth elements?REEs? in international market and gradual depletion of rare earth ore resources at present, strengthen the comprehensive utilization of the rare earth mineral resources becomes particularly important. Rare earth tailings is an important rare earth based two mineral resources. Its recycling has been highly valued and become a focus by the state and research scholars.This study aims to enrich and recycle valuable elements from rare earth mud lixivium step by step. Based on the anlysis of rare earth tailing process mineralogy in Mianning, Nan Hema County. Adopting stepwise grafting polymerization method to prepare the good performance of Mn?II? ion imprinted material and salicylic acid type adsorption material, and using them as Fe³⁺, Mn²⁺ ions, and rare earth ions(RE³⁺) solid-phase extraction sorbent respectively, studied the target ions enrichment performance of the two kinds of materials in the slime leaching solution of rare earth in-depth, greatly improved the purity of rare earth ions, it has important scientific significance in dilute indigenous product purification. This major results of this paper obtained as follows:?1?Analyzing and characterizing the rare earth tailings process mineralogy by using X-ray diffraction?XRD?, inductively coupled plasma mass spectrometry?ICP-MS? techniques. The tailings contained 16 rare earth elements except Pm, the light rare earth element content of Ce, La, Nd, Pr was high and rare earth belonged to Ce₂O₃ > La₂O₃ > Nd₂O₃ ?Ce₂O₃ rich strong distribution type, the total amount ?Ce₂O₃ and ?Y₂O₃ were between 96.76%⁹7.60% and 2.40%³.31% respectively; tailings was mainly composed of bastnaesite, barite, fluorite, feldspar, phlogopite-2M1 and other gangue minerals and laueite which loaded rare earth, iron and manganese; rare earth elements in rare earth mineral phase were existed as independent mineral facies?mainly bastnaesite?, laueite adsorption phase and gangue minerals dispersed phase, the average content of REO were 74.07%, 3.69% and 0.36%, respectively.?2?Relying on the method of stepwise graft polymerization, ionic imprinted polymers of manganese ions?Mn-IIPs? were prepared with the silica gel particle?SiO₂? which activated with the 3-aminopropyltrimethoxysilane?AMPS? as coupling agent, hydrochloric acid as inorganic carrier, 3-aminopropyltrimethoxysilane?AMPS? as coupling agent, 2-hydroxyethyl methacrylate?HEMA? as functional monomer and 8-hydroxyquinoline?HQ? as functional group. The materials of salicylic acid-type chelating are prepared with coupling agent 3-?irimethoxysilyl? propyl methacrylate?MPS?, glycidyl methacrylate?GMA? as functional monomer and 5-aminosalicylic acid as functional group. Both materials were charactelized with infrared spectrum technique?FT-IR?, thermogravimetric-differential thermal analysis?TG-DTA? and scanning electron microscope?SEM?. The results indicated that the temperature was 50?, reaction time was 12 h, a redox initiating system was set up by the amino groups of NH₂-S₂O₈^2-. On this condition, the grafting degree of HEMA could get up to 14.13 g/100 g; Sodium bicarbonate as acid-acceptor, the bond rate of HQ group was 81.50% reacted for 6 h at 90?. The grafting degree of GMA was 13.52 g/100 g reacted for 20 h at 70?; the bond rate of SA group was 90.00% reacted for 36 h at 80? in alkaline solution. Both materials of surface had formed a loose polymer coating layer, and excellent thermal stability.?3?A large number of imprinted holes and HQ functional groups were distributed in the surface of the polymer layer on the Mn-IIPs, and showed specific selective recognition for Fe³⁺ and Mn²⁺. The single factor experiment results showed, when the rare earth leaching liquid dilution rate was 250 times, the adsorption rates of Fe³⁺ and Mn²⁺ were 90.90% and 89.30%; 95.52% and 91.71% respectively with the system temperature 30?; pH = 2.0, the adsorption of Mn²⁺ rate was 90.61%(Fe³⁺ hydrolysis had occurred); the amount of Mn-IIPs on the ceiling had little effect on the adsorption performance.The desorption rate of Fe³⁺, Mn²⁺ in a concentration of 0.25 mol·L-1 hydrochloric acid solution as the eluent were 96.42%, 95.72% respectively; the adsorption of Fe³⁺ and Mn²⁺ rate of 83.7% and 87.5%, a decrease of 2.89% and 0.24% when the imprinted material Mn-IIPs reused for 5 times, it embodied out the renewable and recycled performance of imprinted material Mn-IIPs.?4?Salicylic acid molecules, bond to the surface of the grafted particles PGMA/SiO₂, had bidentate coordination groups?hydroxyl and carboxyl? which will produce a strong coordination chelation for RE³⁺ ions and form some stably six-membered chelate rings in aqueous solutions. The results of dentate chelation and electrostatic interaction together brought a strong chemical adsorption behavior of the composite ASA-PGMA/SiO₂ to RE³⁺ ions. Temperature of the system was 50?, the adsorption rate for RE³⁺ ions was 94.56%; it was 75.35% in the reaction system of aqueous solutions of pH = 2.0; the dosage of chelating particles was 0.10 g, the adsorption rate was 96.99%. The results of orthogonal experiment were that the impact of each factor for the adsorption descending was media pH, dosage of chelating particles, temperature of the system, and the time of adsorption. The adsorption rate for RE³⁺ ions was 97.29% reacted 50? at 1 h in aqueous solutions of pH = 5.0; Binding sites on the surface of materials had given RE³⁺ ions easily eluted qualities, the desorption of RE³⁺ ions from the particles was effective while using 0.25 mol·L-1 of hydrochloric acid solution as the eluent. Adsorption-desorption experiments showed that the materials had a good repeat performance, and adsorption for RE³⁺ only decreased by 2.03%.