X射线荧光光谱法分析萤石中的CaF2

采用X射线荧光光谱仪及熔融玻璃片法,分析了萤石中的CaF2.在制样时利用低温熔融成玻璃片,克服了样品中的F高温挥发,获得了满意的结果.     

熔融制样X-荧光光谱法测定萤石中CaF2、SiO2、S的研究

研究了萤石熔融制样条件与真空度对测定F元素的影响。采用Li2B4O7 33％＋LiBO2 67％混合熔剂,硝酸锂为氧化剂,溴化锂脱模剂,试样与熔剂质量比3：10熔融制得玻璃样片,通过测定F元素获得氟化钙含量。方法操作简单．能满足检测需要。     

萤石检验中取样和化验方法的改进

萤石有多种颜色,一批萤石中不同颜色的块矿CaF2含量相差较大,小批量散装萤石检验中存在不均匀的问题。为此,结合张钢实际情况,提出了目测法与实际取样相结合的方法,同时改进萤石CaF2化验方法,利用硼酸-盐酸混合酸加热溶解并测定钙量,利用钙指示剂取代钙黄绿素、百里香酚酞和无水硫酸钾混合指示剂,结果快速准确,分析时间约为0.5 h。     

X射线荧光光谱法测定萤石中CaF_2含量不确定度的评定

采用X射线荧光光谱法测定萤石中CaF2含量,分析了分析结果不确定度产生的原因,并建立了数学模型。对测量重复性、标准物质、校准曲线回归、检测条件、试样称量和熔剂中杂质引起的不确定度分量进行评定,计算了合成标准不确定度和扩展不确定度,并给出萤石中CaF2含量测定结果的报告。评定结果表明,校准曲线回归引起的不确定度对总不确定度影响最大。所以,在测定中应特别注意校准曲线的校正和绘制校准曲线所用标准样品的选择。     

X射线荧光光谱法测定萤石中CaF2、SiO2、P和S

采用熔融法制样，通过条件实验找出最佳熔融条件和测定条件，采用标准样品和合成标样绘制校准曲线，用X射线荧光光谱法测定萤石中CaF2、SiO2、P和S的含量。测量结果与标样标准值、未知试样化学分析值相符，CaF2、SiO2、P和S的相对标准偏差分别为0．19％、0．49％、7．55％和3．18％。     

酸碱中和滴定法测定萤石中碳酸盐量

本方法在气体发生装置中用盐酸处理试料,Ba（OH）2溶液吸收产生的CO2,过量的碱用盐酸中和,加一定体积过量的盐酸标准滴定溶液以溶解BdCO3沉淀,再以甲基橙为指示剂,用NaOH标准滴定溶液返滴定测量碳酸盐量。通过进行氮气流量、氟离子干扰、硫离子干扰、盐酸对测量的干扰、BaCl2用量、标准物质回收等试验,确定最佳分析条件。该方法可直接反映萤石样品中碳酸盐的量,测量精度较好,可用于日常分析。     

电位滴定法测定萤石中的氟含量

本方法通过控制温度在高氯酸存在下将氟蒸馏而与样品分离,用自动电位滴定仪以硝酸镧溶液滴定蒸馏液中的氟.进行了六次甲基四胺缓冲溶液的试验,考察了滴定条件和蒸馏条件的影响,确定了适合的试验条件.采用此方法其测量对象为氟,直接反映了萤石样品中的氟量,测量精度较好,可用于日常分析.     

在透明CaF2衬底上生长的ZnSe—ZnS应变超晶格的光学性质

利用常压ＭＯＣＶＤ系统在透明衬底ＣａＦ２上生长了ＺｎＳｅ－ＺｎＳ应变超晶格，研究了低密度激发下该结构在不同温度下的光学性质，对光谱中出现的多个发光体进行了分析。     

Behavior Analysis of CaF2 in Magnesia Carbothermic Reduction Process in Vacuum

Magnesium production by carbothermic reduction of magnesia with CaF₂ in vacuum was investigated experimentally by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and thermodynamic analysis. Thermodynamic calculations indicate that magnesium was generated by a carbothermic reduction among MgO-C system, which should be above 1500 K (1227 °C) (50 Pa). According to the carbothermic reduction analysis, the CaF₂ does not participate in the carbothermic process. The experimental results demonstrated that the mass loss increased along with increasing CaF₂. The percentage was up to 92 pct with 5 pct CaF₂.The reduction degree increased with CaF₂ more than it without CaF₂ obviously. Considering the reduction degree and economic benefit, 5 pct CaF₂ was the optimal choice. The purity of metal magnesium reached 95.59 wt pct, which has perfect crystallization and lamellar structure. CaF₂ did not participate in magnesia carbothermic reduction in vacuum; instead, it played a catalytic role during the process.     

Effect of CaF2 and SiO2 modification on phosphorus utilisation in P-bearing slag

Abstract

In order to recycle phosphorus in P-bearing converter slag for slag phosphate fertiliser, the effect of CaF₂ and SiO₂ modification on P-bearing steelmaking slag on phosphorus-bearing phases, P₂O₅ solubility and magnetic separation behaviour has been researched. The results show that the phosphorus-rich phase is mainly n2CaO·SiO₂–3CaO·P₂O₅ (nC₂S–C₃P for short) and exists along with fluorapatite phase [Ca₅(PO₄)₃F] after the addition of CaF₂. The fluorapatite cannot be dissolved in 2% citric acid solution, which decreases the P₂O₅ solubility in slag. Although adding CaF₂ can increase the P₂O₅ content of phosphorus-rich phase, it can improve its metallisation and magnetisation of RO phase, increase the amount of recovered magnetic substances, and separate incompletely phosphorus and iron, therefore it is adverse to the phosphorus recovery from P-bearing slag by magnetic separation. P₂O₅ content of phosphorus-rich phase is more than 31% and P₂O₅ solubility of slag is increased to 96% in fluorine-free modified slag, which can meet the requirement of P₂O₅ content and P₂O₅ solubility of the phosphate fertiliser. Meanwhile, 87.1% of the phosphorus in the fluorine-free modified slag is contained in non-magnetic substance, and most of the phosphorus was recycled.     

Cao—SiO2—CaF2三元渣系的挥发率

通过质量损失法对ＣａＯ－ＳｉＯ２－ＣａＦ２三元渣系挥发率与温度、渣组成的关系进行了研究。结果表明：在渣完全熔化之前有一临界温度，其值大小因渣而异，即酸性渣具有低温临界点；碱性渣具有高温临界点；中性渣则两个临界点均存在；当渣的碱度过高（Ｒ≥１．４）或ＣａＦ２含量减少（≤１０％）时，这两个临界点均不存在。临界温度对渣的挥发率有明显影响；在渣完全熔化之后，挥发率将随碱度的降低及ＣａＦ２含量的增加而提高。     

采用Si-Ca-Ba合金+CaF_2进行钢液脱砷的因素分析

为了充分利用含砷铁矿资源,在实验室条件下,采用Si-Ca-Ba合金+Ca F2对钢液进行了脱砷研究。分析了Si-Ca-Ba合金比例、试验温度、脱砷剂加入量以及初始硫质量分数对脱砷反应的影响。研究表明,Si-Ca-Ba合金比例在65%~75%范围内脱砷效果最明显。在相同试验操作条件下,提高钢液温度、增加脱砷剂加入量和降低钢液中初始硫质量分数可以增大脱砷率。     

Nitrogen solubilities in CaO—CaF2 melts

Nitrogen solubilities in the CaO—CaF₂ system were determined under controlled oxygen partial pressures as well as at carbon saturation. Nitrogen contents (as N^3?) were shown to strongly depend on oxygen partial pressure from 10^?11 to 10^?13 atm. At carbon saturation both nitride and cyanide contents are also dependent on oxygen partial pressure, i.e. CO partial pressure. The dependence of nitride and cyanide contents on nitrogen partial pressure was found to be compatible with the theory and is described by the equations proposed in this paper. The results are also discussed in terms of nitride and cyanide capacities for a better understanding of the dissolution of nitrogen in slags of different composition. The temperature dependence of nitride content showed an increase in nitride content with increasing temperature.     

萤石中碳酸钙的测定及其讨论

本文对国内外有关方法进行了研讨，提出：在乙酸介质中，室温浸取萤石试样，于浸取液中，用ＡＡＳ法或ＥＤＴＡ法测定钙量，用Ｚｒ－ＸＯ光度法测定氟量；或在含钙乙酸介质中，热浸取萤石试样，用去碳酸钙萤石样作空白。确立了萤石中碳酸钙的测定方法。此法已用于萤石一级标准物质中碳酸钙的测定。结果证明，该法准确可靠。