Recovery of iron from Baotou rare earth tailings by magnetizing roast

The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant,which leads to a great difficulty in separation of minerals.In this article,the process of magnetizing roast and low-intensity magnetic separation was used to recover iron.Effect of calcination temperature,holding time and carbon/oxygen ratio on roasting efficiency was investigated.The parameters evaluating magnetizing roast efficiency and theoretical value were determined.X-ray diffraction(XRD)analysis was used to investigate the conversion of Fe phase after roasting.The results show that the best magnetizing roast conditions are calcination temperature of 650℃,holding time of 2.5 h,and carbon/oxygen molar ratio of 3.85.The best magnetization rate is 2.36,which is close to the theoretical value of 2.33.Based on experiments of low-intensity magnetic separation under different intensities,the best current intensity is 2.0 A to obtain the best separation results.Under the best condition,the concentrate grade of iron is 45.45% and the recovery of iron is 68.36%.Most of rare earth,fluorine,and phosphorus are enriched in the magnetic separation tailings.The XRD analysis shows that Fe exists in Fe2O3 before roasting and exists in Fe3O4after roasting.

Separation of Kaolinite from Ion-Adsorption Rare Earth Tailings in Southern China and Iron Removal Treatment

Several hundred million tons of ion-adsorption rare earth tailings exist in Ganzhou, Southern China, which is a severe environmental hazard. To reduce and reutilize the tailing, kaolinite has been separated from the tailings by mechanical separation in laboratory scale and pilot scale. The results show that the tailing is mainly composed of fine kaolinite and coarse quart. Quartz and kaolinite can be separated by sieves, shaker, spiral chute or hydrocyclone, which has the similar results in laboratory scale and pilot scale. 30.2% of the tailings can be re-sourced and applied in ceramic industries. 41.7% of kaolinite can be obtained after sorting and iron removal by magnetic separator in pilot scale, which can be applied in ceramic industries according to the Chinese national standard (TC-3). The results give a progressive solution to re-source the tailings economically.

Anti-adsorption mechanism of ion-adsorption type rare earth tailings

To investigate the process of RE^(3+)anti-adsorption on ion-adsorption type rare earth tailings,the thermodynamics,adsorption kinetics and infrared spectroscopy of these materials were investigated.The results indicate that the initial reaction rate of anti-adsorption of rare earth tailings is fast,but it reaches a balance in 6 min.The formula 1-2a/3-(1-a)2/3=k_2t(k represents rate constant of the reaction,a represents anti-adsorption rate of rare earth ore,t represents anti-adsorption time)of internal diffusion can be used to predict the kinetics of anti-adsorption in IATRE tailings.BecauseΔH<0,ΔG<0,ΔS>0(ΔH,ΔG,ΔS represent change of enthalpy,Gibbs free energy and entropy,respectively),the anti-adsorption of RE^(3+)on ion-adsorption type RE tailings is a spontaneous physical adsorption process.The effects of ligand exchange and strong chemical bond are not found in this process.Because the anti-adsorption process is exothermic,heating will inhibit the reaction and decrease the anti-adsorption performance.According to the infrared spectrum analysis,there are no significant changes in the mineral surface after anti-adsorption.Based on these findings,the anti-adsorption of rare earth tailings is physical adsorption.

Coupling relationship between multicomponent recovery of rare earth tailings

About 90 % rare earth minerals and many other valuable minerals are heaped as iron tailings without comprehensive utilization. In order to comprehensively recover these valuable minerals, in a view of the valuable ore type of Baotou Steel tailing and embedded features, valuable components flow and their respective recovery coupling relationship in beneficiation flowsheet were ana- lyzed; process flows and parameters which could give consideration to four kinds of components were deter- mined. TFe, rare earth oxide （REO）, niobium and fluorite recoveries could reach 72.70 %, 81.84 %, 78.58 % and 60.18 % in low-intensity/high-intensity magnetic separa- tion, respectively. High-intensity magnetic concentration was treated by REO direct flotation; the recovery is 75.43 %, on the base of which Fe could be separated completely from Nb. The underflow was treated by reduction roasting-low-intensity magnetic separation. And the relationship between the recoveries of these valuable components was also discussed.

Roasting decomposition of mixed rare earth tailings by CaO in reducing atmosphere

In Baotou rare earth tailings ore, the grade of rare earth is close to that of the raw ore nearly. The rare earths are discarded in tailings dam caused by a serious waste of resources. First of all, the decomposition products of bastnaesite-and monazite-mixed rare earth tailings in CaO in reducing atmosphere were studied by means of X-ray diffraction（XRD）. The results show that the normal products are CeO2, Ce2O3, Ca5F（PO4）3, and Ce（0.75）Nd（0.25）O（1.875）, and there are no REPO4 and REFCO3.Secondly, the roasted product was extracted in HCl, and the relationship among roasting time,roasting temperature,CaO addition, and extraction temperature was studied by the quadratic regression-orthogonal analysis. Through analysis, the optimum process conditions of mixed rare earth tailings extracted are obtained as follows： roasting time of 60 min, roasting temperature of 800℃, CaO addition of 30%, extraction temperature of 80℃, and extraction ratio of 99.18%.

Iron recovery and rare earths enrichment from Bayan Obo tailings using Coal-Ca(OH)2-NaOH roasting followed by magnetic separation

The recovery of iron and enrichment of rare earths from Bayan Obo railings were investigated using Coal Ca（OH） 2 NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, coal content, milling time, Ca（OH）2 dosage and NaOH dosage on the iron and rare earths recovery were explored. The results showed that the magnetic concentrate containing 70.01 wt. % Fe with the iron recovery of 94.34G and the tailings of magnetic separation containing 11.46 wt. % rare earth oxides （REO） with the REO recovery of 98. 19% were obtained under the optimum conditions （i. e. , roasting temperature of 650℃, roasting time of 60 min, coal content of 2.0%, milling time of 5 min, and NaOH dosage of 2.0%）. The Ca（OH）2 dosage had no effect on the separation of iron and rare earths. According to the mineralogical and morphologic analysis, the iron and rare earths of Bayan Obo tailings could be utilized in subsequent ironmaking process and hydrometallurgy process.