Efficient removal of Al(Ⅲ)and P507 from high concentration MgCl_(2)solution based on in-situ reaction strategy

For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.

Impact of volcanism on the formation and hydrocarbon generation of organic-rich shale in the Jiyang Depression, Bohai Bay Basin, China

Globally,most organic-rich shales are deposited with volcanic ash layers.Volcanic ash,a source for many sedimentary basins,can affect the sedimentary water environment,alter the primary productivity,and preserve the organic matter(OM)through physical,chemical,and biological reactions.With an increasing number of breakthroughs in shale oil exploration in the Bohai Bay Basin in recent years,less attention has been paid to the crucial role of volcanic impact especially its influence on the OM enrichment and hydrocarbon formation.Here,we studied the petrology,mineralogy,and geochemical characteristics of the organic-rich shale in the upper submember of the fourth member(Es_(4)^(1))and the lower submember of the third member(Es_(3)^(3))of the Shahejie Formation,aiming to better understand the volcanic impact on organic-rich shale formation.Our results show that total organic carbon is higher in the upper shale intervals rich in volcanic ash with enriched light rare earth elements and moderate Eu anomalies.This indicates that volcanism promoted OM formation before or after the eruption.The positive correlation between Eu/Eu*and Post-Archean Australian Shale indicates hydrothermal activity before the volcanic eruption.The plane graph of the hydrocarbon-generating intensity(S1+S2)suggests that the heat released by volcanism promoted hydrocarbon generation.Meanwhile,the nutrients carried by volcanic ash promoted biological blooms during Es_(4)^(1 )and Es_(3)^(3) deposition,yielding a high primary productivity.Biological blooms consume large amounts of oxygen and form anoxic environments conducive to the burial and preservation of OM.Therefore,this study helps to further understand the organic-inorganic interactions caused by typical geological events and provides a guide for the next step of shale oil exploration and development in other lacustrine basins in China.

硫酸镁溶液高效制备碳酸氢镁及皂化萃取分离稀土

为实现包头混合型稀土精矿冶炼分离过程中硫酸镁废水的循环利用,开展硫酸镁溶液碱转制备氢氧化镁、CO_(2)碳化制备碳酸氢镁溶液,以及硫酸稀土溶液的皂化HDEHP萃取分离转型技术研究。研究碳酸氢镁制备过程关键影响因素及碳化机理,以及碳酸氢镁皂化萃取过程中稀土、钙、镁元素的分布规律。结果表明,碳化过程中硫酸钙会抑制碳酸氢镁的转化,而提高硫酸镁浓度和降低碳化温度均会促进碳酸氢镁的转化。在优化的工艺条件下,实现碳酸氢镁溶液的稳定、高效制备,碳酸氢镁转化率大于95%,Fe、Al、Si等杂质含量低于15 mg/L;硫酸稀土溶液经过多级串级萃取,稀土萃取回收率大于99.5%,未出现硫酸钙结晶析出现象,萃余水相为硫酸镁溶液,循环用于制备碳酸氢镁溶液。

白云鄂博混合型稀土精矿在惰性气氛下的热分解行为

为了开发和应用白云鄂博混合型稀土精矿的先进冶炼技术,采用Kissinger公式、TGA-DSC和XRD等分析方法,研究在氮气氛下白云鄂博混合型稀土精矿的热分解行为,包括热分解动力学、物相变化规律、铈氧化效率以及物相变化对稀土浸出率的影响。结果表明:在500~550℃焙烧时,焙烧质量损失率约10%、热分解活化能(E_(a))为148 k J/mol。550℃焙烧2 h,白云鄂博混合型稀土精矿中氟碳铈矿完全分解,并转化为稀土氧化物和氟氧化物,铈氧化率最大值为0.58%。600℃焙烧2 h,稀土最大浸出率达49.1%。

Experimental study on the degree and damage-control mechanisms of fuzzy-ball-induced damage in single and multi-layer commingled tight reservoirs

Fuzzy-ball working fluids(FBWFs)have been successfully applied in different development phases of tight reservoirs.Field reports revealed that FBWFs satisfactorily met all the operational and reservoir damage control requirements during their application.However,the damage-control mechanisms and degree of formation damage caused by fuzzy-ball fluids have not been investigated in lab-scale studies so far.In this study,the degree of fuzzy-ball-induced damage in single-and double-layer reservoirs was evaluated through core flooding experiments that were based on permeability and flow rate indexes.Additionally,its damage mechanisms were observed via scanning electron microscope and energy-dispersive spectroscopy tests.The results show that:(1)For single-layer reservoirs,the FBWF induced weak damage on coals and medium-to-weak damage on sandstones,and the difference of the damage in permeability or flow rate index on coals and sandstones is below 1%.Moreover,the minimum permeability recovery rate was above 66%.(2)For double-layer commingled reservoirs,the flow rate index revealed weak damage and the overall damage in double-layer was lower than the single-layer reservoirs.(3)There is no significant alteration in the microscopic structure of fuzzy-ball saturated cores with no evidence of fines migration.The dissolution of lead and sulfur occurred in coal samples,while tellurium in sandstone,aluminum,and magnesium in carbonate.However,the precipitation of aluminum,magnesium,and sodium occurred in sandstone but no precipitates found in coal and carbonate.The temporal plugging and dispersion characteristics of the FBWFs enable the generation of reservoir protection layers that will minimize formation damage due to solid and fluid invasion.

Leaching behaviors of calcium and magnesium in ion-adsorption rare earth tailings with magnesium sulfate

The leaching behaviors of calcium and magnesium in the rare earth tailings leached with magnesium sulfate using deionized water,CaCl2 solution and lime water were investigated.Experimental data indicated that magnesium in the tailings was easy to be leached out since most of the magnesium was in the form of water-soluble phase.Most of calcium in the lime water was electrostatically adsorbed on the clay mineral of the tailings,and the water-soluble magnesium was also gradually converted into exchangeable phase because of back-adsorption of Mg2+on the clay mineral with increasing the pH values.When the liquid-to-solid ratio was 0.80,the contents of readily-available magnesium and calcium were 104.4−207.6 and 201.7−1426.3 mg/kg,respectively,which could meet the requirements for plants.These results suggest a promising route for the environmental remediation of ion-adsorption rare earth ore after in-situ leaching.

Dissolution behaviors of rare earth elements in phosphoric acid solutions

In order to provide practical fundamental data for rare-earth elements （REEs） recovery from phosphoric acid and to betterunderstand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with variousconcentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility andphosphoric acid concentration is built and the experimental data are found to fit it very well （R2〉0.94）. Hydrogen-ion concentration isfound to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs inphosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energyof the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevatedtemperature.

Influence of Al addition on microstructures of Cu-B alloys and Cu-ZrB2 composites

The influence of Al addition on the microstructure of Cu-B alloys and Cu-ZrB2 composites was investigated using scanning electron microscopy, X-ray diffraction and first-principles calculation. The results show that the eutectic B in Cu-B alloys can be modified by Al from coarse needles to fine fibrous structure and primary B will form in hypoeutectic Cu-B alloys. As for Cu-ZrB2 composites, Al can significantly refine and modify the morphology of ZrB2 as well as improve its distribution, which should be due to its selective adsorption on ZrB2 surfaces. The first-principles calculation results indicate that Al is preferentially adsobed on ZrB2■, then on ZrB2■, and finally on ZrB2(0001). As a result, smaller sized ZrB2 with a polyhedron-like, even nearly sphere-like morphology, can form. Due to Al addition, the hardness of Cu-ZrB2 composites is greatly enhanced, but the electrical conductivity of the composites is seriously reduced.

A novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite oxide with surface doping of Y and its application in Pd-only three-way catalyst

The ceria-zirconia compound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way catalyst.Moreover,the surface structure of CZ plays an important role in catalytic activity of Pd.However,how to regulate the surface structure of CZ and clarify the structure–activity relationship is still a challenge.In this paper,a strategy is proposed to develop high activity Pd@CZ nanocatalysts by tuning Y doping sites in CZ.The precipitate-deposition method is developed to prepare the novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite with surface doping of Y(CZ-Y-S).In addition,the Pd@CZ-Y-S(Pd supported on CZ-Y-S)exhibits superior catalytic activity for HC,CO,and NO oxide,wherein,for CO and C_(3)H_(6) oxidation,the low-temperature activity of Pd@CZ-Y-S is still 20%higher than that of Pd@CZ-Y-B(Y bulk doping)and commercial Pd@CZ after 1000℃/4 h aging.The effect mechanism is further studied by density functional theory(DFT)calculation.Compared with Pd@CZ-Y-B,Pd@CZ-Y-S shows the lower CO oxide reaction energy barriers due to the weaker adsorption strength of O2.The Y surface doping strategy could provide valuable insights for the development of highly efficient Pd@CZ catalyst with extensive applications.

Separation and purification of Yb_(2)O_(3) by ion exchange chromatography and preparation of ultra-high purity Yb_(2)O_(3)

Ultra-high purity Yb_(2)O_(3) is the critical material of many high-tech materials such as laser glass and fiber,in which impurities seriously affect the laser color quality,intensity and power.In order to reduce the influence of impurities on the properties of laser materials,the purification process of Yb_(2)O_(3) was studied by comparing two kinds of resins(RT-1 and RS-1)using improved ion-exchange chromatography(IEC)method.In this study,through the synergistic improvement of resin structure and eluting system,the environmental pollution caused by ammonia water in the traditional IEC method was reduced,and the requirements of high temperature and pressure were cut.The ion exchange behavior and impurity removal mechanism in the resin column during the loading and eluting process were compared and analyzed.The experimental results show that RS-1 resin is all superior to RT-1resin in elements selectivity,ion exchange capacity and impurities removal rate.After separation and purification by IEC with RS-1 resin,the total removal rate of rare earth impurities was 77.59%and that of non-rare earth impurities was 95.86%when Yb recovery was more than 70%,both higher than that of RT-1 resin(73.26%and 83.18%).This indicates that the improved IEC method is very effective in separating and removing different metal impurities from Yb_(2)O_(3).The pilot test results of IEC method separating and purifying Yb_(2)O_(3) with RS-1 resin show that the purity of Yb_(2)O_(3) can be increased from 99.9929%to 99.9997%by IEC method.It has exhibited huge potential of preparing ultra-high purity Yb_(2)O_(3),especially the deep removal of non-rare earth impurities.

Technology development for rare earth cleaner hydrometallurgy in China

China is the global leader in rare earth （RE） production using hydrometallurgical processes. Advantageous extraction techniques of rare earths from Baotou mixed rare earth minerals, bastnaesite, and ion-adsorption clays of rare earth deposits have been developed in China. The separation and purification technologies have also achieved rapid development. The industrial application processes for rare earth hydrometallurgy were summarized in the present paper. With the large demands and rapid development of rare earths, the issues of resources and environment are more prominent. This review gives an overview of the main processes that were developed in the past toward greener hydrometallurgy of rare earths in China. Based on the development of the rare earth industry, comprehensive utilization and cleaner production should still be focused on in the future, to support the sustainable development.

Leaching and mass transfer characteristics of elements from ion-adsorption type rare earth ore

The differences in the leaching and mass transfer characteristics of ion-adsorption type rare earth ore between rare earth and non-rare earth impurities were investigated. It is determined that the leaching kinetics of rare earths （REs）, Mg and Ca could be described by the shrinking-core model. The leaching rate is controlled by inner diffusion and is in the order of Mg 〉 Ca 〉 RE. The apparent activation energy is 8.48, 6.79 and 6.32 kJ·mol^-1, respectively. In leaching system of Al, the leaching efficiency decreases with the increase in temperature because of hydrolysis reactions. The leaching efficiency of aluminum increases firstly and then decreases with the passage of time when the temperature is higher than 35 ℃. Besides, there is a good consistency in leaching characteristics and mass transfer, and the order of the time-to- peak is Mg 〈 Ca 〈 RE 〈 Al. Therefore, rare earth and non-rare earth may be partly separated by expanding the separation coefficient. The research could provide a theoretic basis for the separation of rare earth and non-rare earth impurities. Furthermore, compound leaching with magnesium salt and calcium salt is innovatively proposed to solve the problem of calcium and magnesium nutrient loss in the soil as well as eliminate ammonia-nitrogen emissions from the source.