Effects of grinding environment and lattice impurities on spodumene flotation

The effect of grinding on the spodumene flotation was investigated. The flotation response of spodumene ground by different mills was different, due to the variation of metal ions on spodumene surfaces caused by grinding environments and/or impurities. The samples were subjected to acid pickling treatment to remove most of the metal ions from the surfaces, and then all samples showed the same poor flotation response, which confirmed the significance of surface metal ions. Metal ion impurities may come from both grinding environments and lattice substitutions in spodumene. Density functional theory (DFT) calculation revealed that Fe and Ca could exist as lattice substitutions on the spodumene surface while Mg substitution is unlikely to occur. Furthermore, Fe is considered to be active site for the absorption of sodium oleate on the spodumene surface. Morphology analysis showed differences in particle size and shape for samples ground by different mills, resulting in different amounts of exposed surfaces. The particle size, cleavage characteristics caused by grinding environments, and metal ion impurities originated from grinding and isomorphous substitutions, play significant roles in the chemisorption of collector on the spodumene surface.

Effect of impurity ions on preparation of novel saponifier for rare earth extraction

Magnesium bicarbonate, prepared by the carbonation of magnesium hydroxide slurry, was used as a novel saponifier to eliminate the ammonia nitrogen pollution in the rare earth extraction separation process. The effect of impurity ions introduced by system on the carbonation reaction of magnesium hydroxide was studied in the work. The results showed that the presence of Ca2＋could lead to side reactions so as to reduce the conversion rate of magnesium hydroxide, and a small number of rare earth ions would have great influence on the carbonation reaction. What’s more, there was no influence on carbonation reaction with the low concen-tration of Na＋or Mg2＋, the conversion rate of magnesium hydroxide could reach above 96%. This paper showed a practical theory which could provide scientific guidance for the preparation of novel saponifier in rare earth extraction separation process.

Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum （CXRS） diagnostics tool built on the HL-2A toknmak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutrM beam injection （NBI） heating. Considering the edge effect of the line of CVI 529.06 nm （n= 8-7）, which contains three lines （active exciting spectral line （ACX）, passivity exciting spectral line （PCX） and electron exciting spectral line （ICE））, and using three Gaussian fitted curves, we obtain the following experimental results： the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m· s^-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

Studies on Dielectric Properties of Silicon Nitride at High Temperature

In this paper, the dielectric properties of silicon nitride are studied using the dielectric polarization theories. According to the developed dielectric models, the temperature dependence of dielectric constant and loss of silicon nitride is mainly analyzed. In addition, the impact of Li^＋, K^＋, Ca^2＋, Al^3＋ and Mg^2＋ doping on the dielectric properties of silicon nitride are also estimated.

Removal of impurities from scandium chloride solution using 732-type resin

The deep removal of Al, Fe（Ⅱ/Ⅲ）, Ca, Zr, Ti and Si from scandium chloride solution was carried out by using 732-type strong acid cation exchange resin. The effects of pH value, contact time and complexing agents（EDTA） on the purification process are investigated. The results indicate that the 732-type resin have a good scandium selectivity and the adsorption order is Sc 〉 Fe（Ⅲ）〉Al 〉 Ca 〉 Zr 〉 Ti 〉 Si in the pH range of 1-3. The separation of Sc and Zr, Si, Ti can be directly carried out because the resin have a good adsorption effect on Sc, AI and Fe（Ⅲ） but poor adsorption effect on Zr, Si and Ti under the condition of pH = 2.5 and contact time 180 min. The Fe（Ⅱ）, Ca and Al are selectively adsorbed on the resin by adding reducing agent ascorbic acid and EDTA into the solution for reducing Fe（Ⅲ） to Fe（Ⅱ） and complexing Sc.By using two-step ion exchange adsorption separation method, the removal rates of Fe（Ⅲ）, Ti, Al, Ca, Zr and Si are 95.5%,99.8%,100%,98.2%,98.6% and 100%,respectively.

Investigation of solution chemistry to enable efficient lithium recovery from low-concentration lithium-containing wastewater

In the production of lithium-ion batteries(LIBs)and recycling of spent LIBs,a large amount of low-concentration lithium-containing wastewater(LCW)is generated.The recovery of Li from this medium has attracted significant global attention from both the environmental and economic perspectives.To achieve effective Li recycling,the features of impurity removal and the interactions among different ions must be understood.However,it is generally dificult to ensure highly efficient removal of impurity ions while retaining Li in the solution for further recovery.In this study,the removal of typical impurity ions from LCW and the interactions between these species were systematically investigated from the thermodynamic and kinetics aspects.It was found that the main impurities(e.g.,Fe^+,AIP^+,Ca^2+,and Mg^2+)could be efficiently removed with high Li recovery by control-ling the ionic strength of the solution.The mechanisms of Fe^3+,Al^+,Ca^2+,and Mg^2+removal were investigated to identify the controlling steps and reaction kinetics.It was found that the precipitates are formed by a zero-order reaction,and the activation energies tend to be low with a sequence of fast chemical reactions that reach equilibrium very quickly.Moreover,this study focused on Li loss during removal of the impurities,and the corresponding removal rates of Fe^+,Al^+,Ca^2+,and Mg^2+were found to be 99.8%,99.5%,99%,and 99.7%,respectively.Conse-quently,high-purity LisPO4 was obtained via one-step precipitation.Thus,this research demonstrates a potential route for the effective recovery of Li from low-concentra-tion LCW and for the appropriate treatment of acidic LCW.