Binding and Adsorption Energies of Heavy Metal Ions with Hapli-Udic Argosol and Ferri-Udic Argosol Particles

Gibbs free binding energy and adsorption energy between cations and charged soil particles were used to evaluate the interactions between ions and soil particles.The distribution of Gibbs free adsorption energies could not be determined experimentally before the development of Wien effect measurements in dilute soil suspensions.In the current study,energy relationships between heavy metal ions and particles of Hapli-Udic Argosol(Alfisol)and Ferri-Udic Argosol were inferred from Wien effect measurements in dilute suspensions of homoionic soil particles(<2μm)of the two soils,which were saturated with ions of five heavy metals,in deionized water.The mean Gibbs free binding energies of the heavy metal ions with Hapli-Udic Argosol and Ferri-Udic Argosol particles diminished in the order of Pb^(2+)>Cd^(2+)>Cu^(2+)>Zn^(2+)>Cr^(3+),where the range of binding energies for Hapli-Udic Argosol(7.25-9.32 kJ mol^(-1))was similar to that for Ferri-Udic Argosol(7.43-9.35 kJ mol^(-1)).The electrical field-dependent mean Gibbs free adsorption energies of these heavy metal ions for Hapli-Udic Argosol and for Ferri-Udic Argosol descended in the order:Cu^(2+)≥Cd^(2+)≥Pb^(2+)>Zn^(2+)>Cr^(3+), and Cd^(2+)>Cu^(2+)>Pb^(2+)>Zn^(2+)>Cr^(3+),respectively.The mean Gibbs free adsorption energies of Cu^(2+),Zn^(2+),Cd^(2+), Pb^(2+),and Cr^(3+)at a field strength of 200 kV cm^(-1),for example,were in the range of 0.8-3.2 kJ mol^(-1)for the two soils.

细粒氯化钠对光卤石分解结晶过程的影响研究

以细粒高钠光卤石为原料,研究光卤石中的细粒氯化钠对氯化钾品位的影响,并探讨其原因。实验结果表明光卤石中含有的细粒NaCl会严重降低KCl品位,细粒NaCl浮选夹带不是导致KCl品位降低的主要原因。溶解速率实验结果表明,光卤石中的细粒NaCl溶解速度较快,溶液中NaCl浓度很快达到较高值,随溶液MgCl_(2)浓度不断升高,新生NaCl晶体析出量增加,NaCl和KCl之间的共生晶体数量增加,新生KCl和NaCl晶体之间的共生现象是导致KCl品位降低的主要因素。

盐湖“冷结晶—正浮选”工艺生产过程考察及探讨

冷结晶—正浮选工艺是生产氯化钾的成熟工艺之一,文章主要针对盐湖冷结晶—正浮选工艺,对分解结晶过程、浮选过程及洗涤过程进行实地考察,并和实验室结果进行对比探讨。结果发现分解液中高浓度氯化钠会严重降低氯化钾品质;精选过程对氯化钾品位的提升效果有限,浮选过程加入淡水能提高氯化钾品位,但是会降低浮选过程收率;洗涤水量在理论水量的基础上过量5%即可满足要求,洗涤效果不随洗涤时间延长而提升。

含钠光卤石分解-浮选过程中氯化钠对氯化钾的影响

目前,工业上广泛采用“分解-浮选”工艺生产KCl,但是在光卤石分解过程中NaCl对KCl晶体的影响尚不明确。在光卤石的分解结晶阶段,由于KCl和NaCl的明显聚集,使得两种颗粒在浮选阶段的分离效率较差。以NaCl掺杂光卤石为原料,开展了分解-浮选制备KCl实验。以NaCl的粒径和含量为变量,结合扫描电子显微镜-能谱仪(scanning electron microscope-energy dispersive spectrometer,SEM-EDS)图像,研究了NaCl的粒度和含量对精矿中KCl品位的影响。研究结果显示,掺杂的NaCl粒径对精矿中KCl的影响较大。当NaCl粒径在40~60目时,随着光卤石中NaCl含量的升高,浮选后精矿品位基本不变,K^(+)平均含量为44.39%;当NaCl粒径在60~80目和100目下时,随着光卤石中NaCl含量的升高,浮选后精矿中K^(+)含量明显降低,K^(+)含量分别降低至36.08%和35.48%,而Na+含量分别升高至6.27%和8.36%。此外,SEM和EDS结果表明精矿中的杂质NaCl是以黏附或者嵌入的方式生长在KCl晶体上,从而导致浮选KCl的同时NaCl一起选出,使得精矿中K^(+)含量降低。该研究结果成功揭示了盐田低钾光卤石矿生产钾肥过程中NaCl和KCl难分离的主要原因,为盐湖钾资源的高效利用提供了研究基础。

察尔汗盐湖卤水蒸发速度影响因素的量化研究

针对当前气象因素(辐照强度、风速、环境温度和相对湿度)与卤水因素(卤水温度和浓度)综合作用于卤水蒸发速度定量研究的数据缺乏等问题,采用室外蒸发装置及信号采集系统相结合的实验方法,开展了察尔汗盐湖卤水自然蒸发实验。借助多元线性回归分析方法对实验数据进行分析,建立了基于多因素共同作用下的卤水蒸发速度模型。实验结果表明,卤水蒸发速度随辐照强度、风速、环境温度和卤水温度的增加呈线性增加,而随相对湿度和浓度的增加呈线性减小。进一步得出各因素影响卤水蒸发速度的顺序为,辐照强度>风速>环境温度>卤水温度>相对湿度>浓度。

2015—2020年铜陵市流行性感冒监测结果分析

目的 了解铜陵市流行性感冒(简称流感)流行特征,为辖区流感防控提供科学依据。方法 通过中国流感监测信息系统收集2015—2020年铜陵市流感样病例(influenza-like illnesses,ILI)、病原学监测和ILI暴发疫情等监测数据,分析ILI的分布特征以及病毒阳性标本的人群、时间分布和分型等流行特征。结果 2015—2020年,铜陵市2家哨点医院报告ILI共计26 862例,其中5岁以下人群占比最高,为46.04%(12 367/26 862);流感样病例百分比(ILI%)为3.11%(26 862/862 671),各年度ILI%差异有统计学意义(χ~2=941.478,P<0.05);监测年度内共出现8次就诊高峰,主要发生在冬春季。共采集ILI标本8 490份,总阳性率为12.60%(1 082/8 490),男性和女性阳性率分别为14.44%(586/4 059)和11.19%(496/4 431);各年龄组中,5~14岁组阳性率较高,为22.41%(322/1 437);各年度中,以2017—2018年度阳性率较高,为20.63%(255/1 236);不同性别、年龄组、年度间阳性率差异均有统计学意义(χ~2=20.038、249.020、941.478,P均<0.05)。不同监测年度中,甲型H1N1、A(H3N2)流感在每个监测年度均有流行,B型流感Victoria系和Yamagata系则呈交替流行。共报告流感暴发疫情20起,均发生在中小学。结论 铜陵市流感流行季节主要为冬春季,5~14岁组儿童青少年为发病重点人群,需加强学生疫苗接种及重点场所流感监测。

Interactions of Heavy Metal Ions with Paddy Soils as Inferred from Wien Effect Measurements in Dilute Suspensions

Interactions of three heavy metal ions, Cu2+, Cd2+, and Pb2+, and, for comparison, Na+ with electrodialytic clay fractions (less than 2μm in diameter) of four paddy soils as well as a yellow-brown soil as a control soil were evaluated based on measurements of the Wien effect in dilute suspensions with a clay concentration of 10 g kg-1 in four nitrate solutions of 2×10-4/z mol L-1, where z is the cation valence, and a nitric acid solution of 3×10-5 mol L-1.Field strengths ranging from 15 to 230 kV cm-1 were applied for measuring the electrical conductivities (ECs) of the suspensions. The mean free binding energies between the various cations and all of the soils determined from exchange equilibrium increased in the order: Na+ < Cd2+ < Cu2+ < Pb2+. In general, the ECs of the suspensions in the sodium nitrate solution were smaller than those of the suspensions in the heavy metal solutions because of the lower electrophoretic mobility of sodium compared to the divalent cations. In terms of relative electrical conductivity-field strength relationships, relative electrical conductivity (REC) of suspensions containing various cations at field strengths larger than about 50 kV cm-1 were in the descending order: Na+ > Cu2+ > Cd2+ > Pb2+ for all tested soils. A characteristic parameter of the REC-field strength curves,△REG200, REG at a field strength of 200 kV cm-1 minus that at the local minimum of the concave segment of the REC-field strength curves, characterized the strength of adsorption of the cations stripped off by the applied strong electrical field, and for all soils the values of△REC200 were generally in the order: Na+ < Cu2+≤Cd2+≤Pb2+.

Wien Effect Characterization of Interactions Between Ions and Charged Sites on Clay Surfaces of Variable-Charge Soils

To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions,and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol,clay fractions smaller than 2 μm were separated from samples of the two variable-charge soils.Ferric oxides were removed from part of the clay fractions,which were then saturated with various chlorides(NaCl,KCl,CaCl2,CdCl2 or LaCl3).Electrical conductivities(EC) of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus,which enables measurement of the Wien effect at field strengths(E) from 14 to 250 kV cm-1.The Wien effect(EC-E) curves revealed EC increases of red soil suspensions between 14 and 200 kV cm-1,of 8.3,8.4,12.1,5.9,and 1.2 μS cm-1 for NaCl,KCl,CaCl2,CdCl2,and LaCl3,respectively,reflecting the differing interactions with the various cations and chloride.The EC increments with the iron-free red soil suspensions were higher,being 29.7,17.2,and 15.3 μS cm-1 for NaCl,CaCl2,and CdCl2,respectively.In the natural latosol suspensions the EC increments were practically zero,whereas in the iron-free fractions there were significant EC increments of 10.3,5.7,5.0,and 1.6 μS cm-1 for NaCl,CaCl2,CdCl2,and LaCl3,respectively.

老挝固体钾盐矿选矿设计的优化与创新——以开元500kt/a氯化钾项目为例

选矿厂设计是矿山建设中极其重要的关键环节。做好选矿厂设计工作,对于节省项目建设投资,确保工厂如期达产达标,取得良好的经济效益,具有决定性的作用。结合老挝开元500 kt/a氯化钾项目选矿厂生产过程中的技术改造与创新,对该类型选矿厂设计进行经验总结,并指明设计中仍需优化与创新的环节。选矿厂设计中工艺流程的选择应具有较强的生产兼容性,且工艺流程主要环节之间有灵活的可切换性,以适应井下开采过程中性质多变的原矿。工艺配置,设备选型和厂房设计既要兼顾原矿和产品性质,也要充分考虑当地的气候条件和自然环境。厂房和工艺设备的防腐,自动化技术的开发应用和工艺流程样品的自动采集与分析是未来仍需优化和创新的重要环节。该项研究可为今后同类选矿厂的设计提供有益的参考。