Application of P507 and isooctanol extraction system in recovery of scandium from simulated red mud leach solution

The current recovery technique of Sc was complicated and the chemical consumption was high,This was due to the low content of Sc in resources and the difficulty of stripping.In this research,the isooctanol was added into the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester(P507)extraction system to reduce the extraction and improve the stripping of Sc.The maximum stripping ratio of Sc from loaded organic phase by sulfuric acid can increase from 10%(without isooctanol)to 99%(with 15 vol%isooctanol).In the extraction test of the simulated red mud leaching liquor,the separation factors between Sc and Zr,Sc and Ti are 36 and 350,separately.At the same time,other metals are almost not extracted.The high selectivity and stripping of Sc suggest that the P507 with isooctanol extraction system can be applied in the practical Sc recovery process.

Thermodynamic and application study of complicated extraction system Ce(Ⅳ)-HF-H_(3)BO_(3)-H_(2)SO_(4) using Cyanex 923

This article aims to reduce the environmental pollution while maximizing the recovery of REEs as well as associate resource-fluorine(F)from bastnaesite.This paper investigates the extraction equilibrium process and mechanism of Ce(Ⅳ)-HF-H_(3)BO_(3)-H_(2)SO_(4)system using Cyanex 923.Extraction equilibrium process of different systems,including HF-H_(2)SO_(4),H_(3)BO_(3)-HF-H_(2)SO_(4),and Ce(Ⅳ)-HF-H_(2)SO_(4),were studied in detail and the corresponding extraction mechanisms were also determined.It is noteworthy that a synergistic effect between B-F and an antagonistic effect between Ce(Ⅳ)-F were discovered first in the extraction process by Cyanex 923.Besides,H_(3)BO_(3)is found to be able to promote the extraction of F in quantitation by Cyanex 923.FTIR and^(11)B and^(19)F NMR were adopted to characterize the different loaded organic phase.Based on these results,the extraction mechanism of complicated system Ce(Ⅳ)-HF-H_(3)BO_(3)-H_(2)SO_(4)was further determined.Besides,the effect of H_(3)BO_(3)on the extraction and stripping of Ce(Ⅳ)in complicated system was studied.Moreover,it shows that the addition of H_(3)BO_(3)has nothing to do with the purity of obtained CeF_(3)particle from bastneasite liquor in the practical system.Adding H_(3)BO_(3)into bastnaesite leach liquor,on the one hand,will be beneficial for the recovery yield of Ce and F.On the other hand,it can avoid from environmental pollution caused by emission of F-containing waste water as well as reducing the waste residue.

A New Hybrid Machine Learning Model for Short-Term Climate Prediction by Performing Classification Prediction and Regression Prediction Simultaneously

Machine learning methods are effective tools for improving short-term climate prediction.However,commonly used methods often carry out classification and regression prediction modeling separately and independently.Such a single modeling approach may obtain inconsistent prediction results in classification and regression and thus may not meet the needs of practical applications well.To address this issue,this study proposes a selective Naive Bayes ensemble model(SENB-EM)by introducing causal effect and voting strategy on Naive Bayes.The new model can not only screen effective predictors but also perform classification and regression prediction simultaneously.After being applied to the area prediction of summer western North Pacific subtropical high(WNPSH)from 2008 to 2021,it is found that the accuracy classification score(a metric to assess the overall classification prediction accuracy)and the time correlation coefficient(TCC)of SENB-EM can reach 1.0 and 0.81,respectively.After integrating the results of different models[including multiple linear regression ensemble model(MLR-EM),SENB-EM,and Chinese Multimodel Ensemble Prediction System(CMME)used by National Climate Center(NCC)]for 2017-2021,the TCC of the ensemble results of SENB-EM and CMME can reach 0.92(the highest result among them).This indicates that the prediction results of the summer WNPSH area provided by SENB-EM have a high reference value for the real-time prediction.It is worth noting that,except for the numerical prediction results,the SENB-EM model can also give the range of numerical prediction intervals and predictions for anomalous degrees of the WNPSH area,thus providing more reference information for meteorological forecasters.Overall,as a new hybrid machine learning model,the SENB-EM has a good prediction ability;the approach of performing classification prediction and regression prediction simultaneously through integration is informative to short-term climate prediction.

Development course of separating rare earths with acid phosphorus extractants: A critical review

This paper reviews the development course of separating rare earths with acid phosphorus extractants,including extraction chemistry(thermodynamics and kinetics), separation process and industrial application, the loss/degradation of extractants, etc.

Kinetics of nitric acid leaching of cerium from oxidation roasted Baotou mixed rare earth concentrate

The kinetics of nitric acid leaching of cerium was investigated for the oxidation roasted Baotou mixed rare earth concentrate. The effects of leaching temperature, HNO_3 concentration, liquidesolid ratio(L/S)and stirring rate on rare earth extraction were studied. The XRD and SEM mapping analysis of the samples before and after acid leaching shows that the roasted bastnaesite is completely leached. Besides,the decomposition process of oxidizing roasting was also obtained by TGe MS and XRD. Different kinetics models were applied in this leaching process. The results of dynamic fitting show that the leaching process can be described by a new variant of the shrinking-core model. And the leaching rate is controlled by both the interfacial transfer and diffusion through the product layer. The apparent activation energy is calculated as 76.78 kJ/mol and the reaction orders with respect to HNO_3 concentrations and liquidesolid ratio are determined to be 7.609 and 2.516, respectively. Besides, an empirical rate equation is obtained to describe the process.

Thermal decomposition mechanism of low-content-fluorite Bayan Obo rare earth concentrate roasted with sodium carbonate and its consequent separation study

Thermal decomposition and phase transformation for the mixture of Bayan Obo rare earth concentrate(BORC)and sodium carbonate(Na2CO3)roasted at different temperatures with weight ratio of 100:20 were studied in detail in our study.The aim of our study is to reveal the nature of roasting reaction between BORC and Na2CO3 and thus providing a new method for processing BORC.The results indicate that BORC can be decomposed completely with Na2CO3 at around 600℃after 3 h.During the calcination process,Ce0.5Nd0.5O1.75,NaF,Na3PO4,and a rare earth double phosphate phase Na3RE(PO4)2 are formed after the decomposition of BORC with Na2CO3.In addition,the thermal decomposition mechanism is determined in the paper.Based on these facts,a clean technique processing BORC was developed.And a CeF3 powder,whose composition was measured and stability was also evaluated,was obtained for some potential application from the new technique.This research is of significance in terms of the Na2CO3-roasting BORC solid reaction study and sheds a light on a potential clean technique for BORC.

A review on solvent extraction of scandium

This review article on the development course of scandium solvent extraction covers:(i)neutral phosphorus extractants;(ii)acid phosphorus extractants;(iii)carboxylic acid extractants;(iv)amine extractants;(v)chelating extractants;(vi)synergistic extractants.Those extractants are of valuable reference for developing new separation process of scandium from red mud,titanium dioride and other rare earth resources.