高温热水解-离子色谱法测定铬矿中氟含量

建立了一种快速、准确的离子色谱法测定铬矿中氟含量的方法,将铬矿与石英砂混合,控制氧气和水蒸气的流量,于1 100℃高温下热水解30min,水解液经吸收后,选用Dionex AS11-HC阴离子分析柱,以KOH(20mmol/L)作淋洗液,自动再生抑制型电导检测器检测,离子色谱法测定铬矿中氟的含量。方法的检出限为0.022μg/mL,定量限为0.073μg/mL,方法的检测范围为0.0015%~0.20%,加标回收率在92%~101%。应用于实际样品的测定结果表明,铬矿中氟含量的测定值与标准方法的测定值一致。方法简单快速、检出限低、精密度高、准确度好。能满足铬矿中氟含量的快速准确检测要求。     

重铬酸钾容量法测定铁矿石中全铁的方法改进

选用三氯化钛-重铬酸钾-中性红指示剂容量法,通过对方法的改进,对温度、溶样酸、酸介质、指示剂及共存离子消除的不同条件实验的对比研究,优化了无汞测定全铁的分析方法,实验表明,方法的相对标准偏差(RSD)为0.16%,对国家标准物质测定结果与推荐值基本一致,参加中实国金比对Z比分数小于2,测定结果满意。     

重铬酸钾容量法测定铁矿石中亚铁含量方法的改进

建立了以邻菲罗啉(Phen)、氢氟酸(HF)和硫酸(H2 SO4)为溶剂溶解试样,用重铬酸钾滴定法测定铁矿中亚铁含量的新方法.在强酸(H2 SO4)介质中,Fe2与邻菲罗啉和氟离子形成稳定的络合物,有效地防止了亚铁离子的氧化.在硼酸、硫磷混酸溶液中,以重铬酸钾溶液滴定,并对溶样过程以及滴定过程中的一些条件进行了优化.方法用于铁矿中氧化亚铁的测定,经过国家标准样品以及单位管理样品分析数据对比,方法的重现性较好,相对标准偏差(RSD)＜1％,方法无需在铂金坩埚进行熔样,具有准确度高、重现性好、简单、快速、经济等优点,在实际应用中得到满意的结果.     

装运铁矿石取样的最佳实践

商业交易的装运铁矿石取样应当按照ISO 3082进行。尽管近年来合规性已有所改善,但在一些方面仍存在明显问题,包括:1)大流量样品截取器的设计和操作;2)在二级取样阶段对一级增量样品的划分;3)缩分之前用于减小样品粒度的破碎机的破碎性能;4)在每个取样阶段保留的样品质量;5)样品缩分。取样是测量过程开始的地方,因此如果样品不具有代表性,整个过程在开始时就被破坏了。正确取样的“金规则”是“被取样物料的所有部分都必须有相等的概率被收集到并成为最终分析样品的一部分”。如果不遵守这一规则,那么就很容易引入偏差。例如,在实践中不可能从库存料堆或船舶现场采集到具有代表性的样品。必须在构建堆料或分解堆料时,或在船舶的装载或卸载时取样。在满足“正确取样的金规则”后,取样站设计还应符合以下要求:1)采集的样品质量必须足够大,以考虑粒度大小的影响,将基本误差、分组误差和离析误差降低到可接受的水平;2)需要采取足够数量的增量样品,以将长期质量波动误差降低到可接受的水平;3)应正确地选择取样位置,以避免由于诸如斗轮取料机和离心泵等设备存在的质量周期性变化所造成的影响;4)附加错误诸如样品污染、样品溢出、颗粒降解和操作员失误等,需要从一开始就加以消除。因此为了消除不良的取样做法,确保取样能够兑现应有的承诺,需要通过改进工作人员的培训和提高认识来确保所取样品没有重大偏差,确保样品的总体精度满足所需的任务要求。     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铬矿砂及再生铬矿砂中二氧化硅

铬矿砂及再生铬矿砂经1 000℃灼烧,研磨,以过氧化钠为熔剂,经高温熔融,热水洗涤,盐酸、硝酸酸化前处理样品,直接用电感耦合等离子体原子发射光谱法测定铬矿砂中的二氧化硅。研究了熔融试样时引入的基体元素钠对被测元素的干扰情况,结果表明,过氧化钠加入为1.5g对检测干扰影响小。采用加基体铬、铁有效克服了基体效应对测定的结果影响。硅的检出限为0.004 9mg/L,二氧化硅测定范围为0.010%~6.0%。对铬矿砂标准物质进行测定,结果与标准值一致,方法相对标准偏差(RSD,n=10)小于1%,克服了常规重量法步骤繁琐、耗时长、工作量大的不足,大大提高了检测效率,满足生产需要。     

空气-乙炔火焰原子吸收法测定硫铁矿中的砷

研究了空气-乙炔火焰原子吸收法测定硫铁矿中砷的方法,讨论了其测试条件和共存元素的干扰,样品采用酸浸溶解、直接上机测定。结果表明,该法具有操作简单、快速、火焰温度较高等优点,线性回归方程及相关系数分别为:A=0.003 20 C 0.009 77,r=0.999 3。     

微波消解-原子吸收光谱法测定矿石中的铁

应用微波消解-原子吸收光谱法测定矿石中全铁含量,利用HCl、HNO3、HF混合酸,在800 W的微波功率,利用二步消解程序,终温150 ℃并维持10 min即可将矿石消解完全。与传统消解方式及化学法进行了比较,其测定结果基本一致,相对标准偏差均小于1.3%。节约分析成本、提高工作效率,同时还可减少分析产生的废液等三废造成的环境污染问题。     

Development of a Statistical Model for Selective Flocculation of Iron Ore Slimes

In this study, an attempt has been made to identify the significant factors that affect the selective flocculation of iron ore slimes using full factorial design. For this purpose, three factors pH, pulp density, and the flocculant dose were investigated. A 2³ factorial design was employed and the results were analyzed statistically. The result indicated that the pH, pulp density, and their interactions significantly affect the grade of the concentrate. Regression model using the design matrix showed that the predicted values are in well agreement with experimental values for grade and recovery. From the studies, it was possible to enhance the grade to 62.78% Fe with a recovery of 84.23% at pH 10, pulp density 1% and a flocculant dose of 0.03 mg/g.     

高氯酸镁吸收重量法测定铁矿石中结晶水的含量

建立了铁矿石中结晶水含量的测定方法.利用铁矿石中结晶水高温分解的特性,采用高纯氩气为载气,试样在1 000℃管式炉中加热,结晶水随载气逸出,由装有无水高氯酸镁的吸收管吸收后称量,计算出铁矿石中结晶水的含量.测定结果的相对标准偏差(RSD)小于3％(n=6),加标回收率在95％～ 104％之间.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定大理石岩型石墨矿中的酸溶铁

试样经过盐酸溶解,过滤后用电感耦合等离子体原子发射光谱(ICP-AES)法测定大理岩型石墨矿中的酸溶铁。实验表明,加标回收率为99.1%,相对标准偏差(RSD)为1.0%,检出限为5μg/g,经过与标准方法分析结果对比,得到了国家标准方法一致的测定结果,但更加适用于批量样品的测定。     

Excited-State Kinetics of an Air-Stable Cyclometalated Iron(II) Complex

The complex class [Fe(N^N^C)(N^N^N)]⁺ with an Earth-abundant metal ion has been repeatedly suggested as a chromophore and potential photosensitizer on the basis of quantum chemical calculations. Synthesis and photophysical properties of the parent complex [Fe(pbpy)(tpy)]⁺ (Hpbpy=6-phenyl-2,2′-bipyridine and tpy=2,2′:6′,2′′-terpyridine) of this new chromophore class are now reported. Ground-state characterization by X-ray diffraction, electrochemistry, spectroelectrochemistry, UV/Vis, and X-ray spectroscopy in combination with DFT calculations proves the high impact of the cyclometalating ligand on the electronic structure. The photophysical properties are significantly improved compared to the prototypical [Fe(tpy)₂]²⁺ complex. In particular, the metal-to-ligand absorption extends into the near-IR and the ³MLCT lifetime increases by 5.5, whereas the metal-centered excited triplet state is very short-lived.     

增感效应火焰原子吸收光谱法测定 铁矿石中的微量铬

提出了增感效应火焰原子吸收光谱测定铁矿石中微量铬的新方法。研究了表面活性剂十二烷基硫酸钠(SDS)对铬的增感效果。增感效应可使火焰原子吸收光谱的灵敏度提高 27倍。本法已用于测定铁矿石中的微量铬,检测限为 7.0μg/L ,回收率为 91.1%～115.9%,RSD为 4.0%。     

电感耦合等离子体原子发射光谱测定铬矿中的铅、锌、镍、钛、磷

提出了电感耦合等离子体原子原子发射光谱测定铬矿中的铅、锌、镍、钛、磷含量的方法,选择各元素的分析谱线,采用正交试验的方法确定仪器的工作参数,方法的检出限0.22 ~1.50ug·L-1 ,方法的回收率在89%~112%,测定值的相对标准偏差（n=5）小于1.45%,方法用于铬矿杂元素的分析结果与现有的国标检验方法测定值一致。填补无铬矿中铅、锌、钛元素检测方法的空白。     

Kinetics of isothermal thermogravimetrical degradation of PVC/ABS blends

The PVC/ABS blends were degradated by means of isothermal thermogravimetry at temperatures at 210...240°C in nitrogen. Applying the stationary point method to the data obtained from thermogravimetric curves, apparent activation energy, preexponential factor and compensation parameter for each blend were calculated. The constancy of compensation parameters points to an unchanged mechanism of poly (vinyl-chloride) (PVC) thermal degradation in the presence of acrylonitrile butadiene-styrene (ABS). Upon increasing the fraction of ABS in the blend up to 50% only the kinetics of the process is changed.     

Fluoride Technology for Obtaining Magnetic Materials Based on Nd-Fe-B. Kinetics of Fluorination Processes of Neodymium and Iron Oxides

In the devices, where the interaction of magnetic field sources is used, it is effective to replace the electric power of a magnetic field with a permanent magnet. Rare earth permanent magnets based on neodymium-iron-boron are the most promising, since they have higher magnetic and mechanical characteristics, they are cheaper and more available. The article discusses a fundamentally new fluoride technology for obtaining fluoride materials, the data on the kinetics of fluorination processes of oxides of neodymium, iron and their mixtures are given.     

与铬鞣有关的胶原化学研究进展

本文在回顾与制革有关的生皮胶原结构的基础上, 概述了铬鞣过程胶原与铬(?) 之间的作用, 并对近年来利用胶原计算机模型探讨鞣制反应和以提高铬鞣有效性为目的的胶原修饰化学的研究状况及其发展前景作简要论述。     

Kinetics of the non-isothermal decomposition of Cu-and Co-itaconato complexes

The kinetics of the thermal decomposition of Cu- and Co-itaconato complexes were studied using dynamic thermogravimetric techniques. The dehydration process was found to proceed in a one-stage reaction, while the thermal decomposition of the anhydrous salts was followed a two-stage reaction. The first stage is the decomposition of the complex to metal carbonate, whereas the second stage is the decomposition of the formed carbonate to the oxide. Kinetic analysis of the dynamic TG curves were discussed with reference to a composite integral method on comparison with the integral methods of Coats and Redfern and Ozawa. The activation parameters were calculated and discussed for each decomposition step.     

火焰原子吸收法快速测定铁矿石中金属铁

探讨了火焰原子吸收法(FAAS法)快速测定铁矿石中金属铁的分析条件。对试样的溶解方法、元素分析线、共存元素干扰、仪器分析最佳条件等进行了试验。金属铁含量在0.2%~2.0%范围与吸光度呈良好的线性,线性方程为y=22.924x–0.8458,相关系数r=0.9991。将该法用于铁精粉样品中金属铁的测定,测定结果的相对标准偏差为1.10%~2.98%(n=6),加标回收率为98.0%~103.0%。     

Study of the Kinetics of the Combustion Reaction on Shuangya Mountain Coal Dust by TG

The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction can be obtained from isothermal TG data. The regressions of g(), an integral function of vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.This revised version was published online in November 2005 with corrections to the Cover Date.