Elemental and proximate analysis of coal by x-ray fluorescence assisted laser-induced breakdown spectroscopy

Although laser-induced breakdown spectroscopy(LIBS),as a fast on-line analysis technology,has great potential and competitiveness in the analysis of chemical composition and proximate analysis results of coal in thermal power plants,the measurement repeatability of LIBS needs to be further improved due to the difficulty in controlling the stability of the generated plasmas at present.In this paper,we propose a novel x-ray fluorescence(XRF) assisted LIBS method for high repeatability analysis of coal quality,which not only inherits the ability of LIBS to directly analyze organic elements such as C and H in coal,but also uses XRF to make up for the lack of stability of LIBS in determining other inorganic ash-forming elements.With the combination of elemental lines in LIBS and XRF spectra,the principal component analysis and the partial least squares are used to establish the prediction model and perform multi-elemental and proximate analysis of coal.Quantitative analysis results show that the relative standard deviation(RSD) of C is 0.15%,the RSDs of other elements are less than 4%,and the standard deviations of calorific value,ash content,sulfur content and volatile matter are 0.11 MJ kg,0.17%,0.79% and 0.41%respectively,indicating that the method has good repeatability in determination of coal quality.This work is helpful to accelerate the development of LIBS in the field of rapid measurement of coal entering the power plant and on-line monitoring of coal entering the furnace.

Apply X-Ray Fluorescence and γ-Ray Spectroscopy to Analyze Igneous and Sedimentary Environmental Samples of Al-Atawilah (Al-Baha), Saudi Arabia

Igneous and sedimentary rocks contain an amount of natural radioactivity (NORM). U-238, Th-232 and their decay products, and K-40 are important sources of gamma-radiation. Knowledge of the radionuclide content of rocks is necessary to estimate the exposure of the population to the radiation. Many types of rocks are used in building and industries, thus the radiation detection is important, it provides a baseline map of levels of the radioactivity in the study region. The purpose of this study is to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) (if found) in thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The samples were collected and prepared during 2018/2019, and analyzed with a good experimental instrument (High energy resolution γ-ray spectroscopy with HPGe detector), also these rock samples were analyzed with X-ray fluorescence to subdivided these rocks based on the major oxides proportions contained of each sample. The mean activity concentrations of naturally radionuclides were found in the igneous rock samples varied depending on the type of the igneous rock. For sedimentary rock samples, the activity concentrations were found high for quartz sandstone sample, which may be due to its high proportion of SiO2 and K2O. The estimated mean values of absorbed dose rate are within the permissible limit value. The findings indicate high dose level values in granite (rhyolite) and most of diorite (andesite) igneous rock samples while gabbro (basalt) igneous rock samples (except for one sample) record low levels of dose rate. All sedimentary rock samples have low dose rate (except for the quartz sand-stone sample).

L-shell x-ray fluorescence relative intensities for elements with 62≤Z≤83 at 18 keV and 23 keV by synchrotron radiation

The relative intensities of L-subshell x-ray fluorescence(XRF)for elements with atomic numbers 62≤Z≤83 were measured at two excitation energies,18 keV and 23 keV,using a synchrotron radiation source at a beamline of the Synchrotron Light Center for Experimental Science and Applications in the Middle East(SESAME),Jordan.The experimentally measured results of the relative intensities were compared with the calculated results using the subshell fluorescence yield and the Coster-Kronig transition probabilities recommended by Campbell and the values based on the Dirac-Hartree-Slater model by Puri.The experimental and theoretical results are in agreement.In this work,L XRF relative intensities for the elements Sm,Gd,Tb,Er,Ta,W,Re,Hg,Pb and Bi at energies of 18 keV and 23 keV were measured.

X-RAY FLUORESCENCE SPECTRA ANALYSIS ON THE STRUCTURE AROUND Ti^(4+) OF BaO-SiO_2-B_2O_3-TiO_2 SYSTEM GLASSES

The structure around Ti^(4+) in Bao-SiO_2 -B_2O_3-TiO_2 had been studied by X-ray fluorescence spectra. The results show that the Ti^(4+) mainly exists in the [TiO_4] and enters the network of [SiO_4]. [TiO_4] has the tendency to change to [TiO_6] with the increase of TiO_2 con-tent. When the TiO_2 content increases to about 20mol% the tendency reaches its maximum.

应用FTIR-XRD-XRF分析测试技术研究新型仿制绿松石的矿物学特征

近年来绿松石及其仿制品的鉴定工作较多局限于应用傅里叶变换红外光谱对仿制品进行简单的筛选,前人报道的仿制绿松石的矿物组成主要为单一的矿物相(如异极矿、三水铝石、磷铝石、羟硅硼钙石、菱镁矿等)。本文应用傅里叶变换红外光谱(FTIR)、X射线粉晶衍射(XRD)与X射线荧光光谱(XRF)对当前珠宝市场上几种新型仿制绿松石进行了初步分类,并对不同类别的仿制绿松石的具体矿物组成、物相及晶型特征作了对比研究。结果表明,这些新型仿制绿松石可分为三大类:一类主要由硅酸盐(斜硅钙石)与碳酸盐(方解石)两种矿物组成;另一类为白云石与方解石两种碳酸盐矿物的混合相;第三类以硅酸盐类为主要矿物,并含有钡长石、辉石与石英。显然,新型仿制绿松石的矿物组成明显相异于传统仿制品,可见仿制绿松石的矿物组成日趋多样性、复杂化,该现状必然对新型仿制样品的物相鉴定提出了更高的要求。

NIRS-XRF联用的煤炭发热量高稳定检测

实时获知煤炭发热量对于及时调整电站锅炉风粉配比和提高煤炭燃烧效率具有重要意义,为了实现电力生产中发热量的稳定快速检测,提出了一种近红外光谱(Near Infrared Spectroscopy, NIRS)与X射线荧光光谱(X-ray Fluorescence, XRF)联用的煤炭发热量高稳定检测方法,它结合了NIRS能高稳定检测煤中与发热量正相关的有机基团的优势与XRF能高稳定检测与发热量负相关的成灰元素的特点,大大提高了对煤炭发热量的测量重复性。在光谱预处理中,先将两套光谱融合作为偏最小二乘回归的输入变量进行全谱初步建模,依据回归系数选择NIRS光谱中的有效波段,再将它与XRF光谱中的成灰元素谱线一并融合进行归一化处理。建模时将预处理后的融合光谱数据作为输入变量,利用偏最小二乘回归对煤炭发热量进行建模。实验结果表明,NIRS-XRF联用方法对定标集煤样发热量预测的线性相关度系数(R^(2))为0.995,对验证集煤样发热量预测的最小均方根误差、平均相对误差和标准偏差分别为0.24 MJ/kg,0.61%和0.05 MJ/kg,测量重复性满足小于0.12 MJ/kg的国家标准。NIRS-XRF联用的煤炭发热量高稳定检测方法有望推广应用于火力发电、煤化工、冶金、水泥和焦化等“高碳”行业,助力我国按期实现碳中和目标。

基于p-FTIR和p-XRF测试组合的大汶口文化蛇纹石质玉器无损检测及产地溯源分析

出土玉器溯源是探索华夏玉器文明起源与演化的关键所在,无损测试技术的进步推动了学术界对出土玉器产地溯源的研究,但至今为止,无损技术仍然是制约出土玉器溯源研究的瓶颈所在。利用便携红外光谱(portable Fourier transform infrared spectroscopy,p-FTIR,带漫反射附件)+便携X射线荧光光谱(portable X-ray flourescence,p-XRF)技术组合对山东省文物与考古研究院发掘的大汶口文化出土蛇纹石质玉器的物相和化学组成进行了无损测试以及出土玉器产地溯源的探索。测试结果显示,大汶口文化的蛇纹石玉存在两种成因类型,其中7件玉器(M1005:3,M1006:4,M1013:12,M20:30,M11,T333:2B①:2,M49:04)属于超基性岩型,Fe,Cr和Ni含量较高,含较多磁铁矿包体,磁性较强,Cr/Ni值小于1且多数小于0.7,与现代泰山玉的产地特征基本一致,最大可能就地取材于附近的泰山山麓,为泰山玉的使用时间提前到5500年前的大汶口文化时期提供了重要的科学依据。另外4件玉器(M2004:1、B型环、M25:26、M26)具有低Fe,Cr和Ni含量,为富镁碳酸盐接触交代变质类型,其来源有待进一步研究确认。上述研究结果确认p-FTIR和p-XRF结合能够实现对考古现场及馆藏多数未知玉器材料的快速鉴定,具有无需制样、矿物类型和元素组成可相互验证、无荧光干扰等优点,对部分特定类型的蛇纹石质出土玉器/材料可进行产地来源分析,是一种有优势的出土玉器无损测试技术组合。

A method for correcting characteristic X-ray net peak count from drifted shadow peak

To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.

Application of a Portable XRF Spectrometer for <i>In-Situ</i>and Nondestructive Investigation of Pigments in Two 15th Century Icons

A simple portable X-Ray Fluorescence (XRF) spectrometer was successfully used for in-situ and nondestructive identification of the painting materials in two 15th century icons from the Onufri Museum in Beart, Albania. The spectrometer is based on a low power X-ray tube, a thermoelectrically cooled Si PIN detector and the spectrum acquisition system. It was assembled and adjusted at our laboratory for the investigation of the icons. A small number of pigments were clearly identified by X-Ray Fluorescence (XRF) measurements in both icons. This includes Lead white for the white color, gold and yellow ochre for the yellow color, red lead, cinnabar and red ochre for the red color, as well as cooper based pigments for the green color. At the same time, the investigation raised some new questions that need further investigations by the use of additional analytical techniques. The results show that in both icons are used similar pigments, which are in accordance with the Byzantine icon painting tradition.

Soil Clay Mineralogical Phase Analysis of Ganges Floodplain Soils by XRD and XRF

Soil minerals study is vital in terms of investigating the major soil forming compounds and to find out the fate of minor and trace elements in soils. It is also essential for the soil-plant interaction purpose. To identify soil mineral phases especially clay minerals, X-ray diffraction (XRD) has been a popular technique. The clay mineralogical information of soils in Bangladesh is limited, especially in Ganges flood plain region (Agro Ecological Zone (AEZ) 12 and 13). Therefore, to overcome this limitation, in this study, we performed XRD analysis of <2 mm fractions soil samples of AEX 12 and 13. However, identifying mineralogical phases by XRD in <2 mm fractions soils is not so straight-forward due to many practical problems. We fully matched only two mineralogical phases in all the soil samples which is quartz and potassium-Aluminum-Silicate. However, the full XRD peaks indicate that more minerals are also present, but due to heterogeneity of soils samples, it is difficult to find other minerals phases by only XRD peak of <2 mm fractions. Therefore, to find more information about mineralogical phases, we performed XRF analysis that provides the elemental composition of minerals phase as oxide. XRF analysis indicated the presence of secondary minerals like illite and chlorite. The presence of high percentage Fe oxide not only indicated the iron mineral phase (goethite and ferrihydrite) but also indicated iron rich high charge smectite minerals (beidellite). The presence of iron rich smectite minerals in the Ganges sediments reported in several previous studies. Thus, we concluded that only XRD in <2 mm fractions of soils is not adequate to identify the mineralogical phases of soil samples. Others analyses like XRF, XRD in <2 μm fractions will be necessary to locate an entire image of soil mineralogical phases.

XRF Standardless Comparison of Mining Head and Tail Grades to Screen and Display Ore Processing Recoveries

Separation of target elements or minerals from their host rock or ore is essential to successful mining operation. The inevitable loss of a portion of the desired material that accompanies each step in the extraction process must be documented to develop the operational protocol. Superposition of the characteristic X-ray fluorescence spectra of head (crushed rock ore particles, pre-processing) and tail (post-processing particles) samples provides a direct visual comparison of relative peak sizes, and thereby the relative concentrations, of elements of interest. If the head and tail peaks are identical, none of the element was recovered in the extraction process. At the other extreme if the tail peak “flat lines”, i.e., there is no peak, there was 100% recovery of that element. Standardless visual comparison is valid if the same mass of identical starting material is incorporated into the head and tail sample analysis pucks, and XRF analytical conditions are identical. The considerable time and expense of acquiring and calibrating the standards associated with XRF analysis of 75 or more elements are avoided, a significant advantage during initial broad screening of an experimental extraction procedure. Full quantitation by XRF or an alternate technique can proceed at a later project stage, if desired. The approach retains and presents all features of the original data, thus eliminating questions about data quality, standards and their calibration, and data manipulation in processing from raw counts to concentrations in printout tables. This form of display is ideal for both the mining professional and such less technical groups as corporate staff, investors, regulators, and the public. Examples presented herein are for heap leaching;the protocol can be applied as well to any of the other traditional ore processing and beneficiation procedures, e.g., gravity concentration, magnetic and electrical separation, froth flotation, and ore sorting.

熔片制样-X射线荧光光谱法测定铜精矿中7种组分

铜精矿中硫化物重金属含量较高,样品需要充分氧化后才可熔片,否则熔融过程严重腐蚀铂-金坩埚。一般方法采用硝酸盐作为氧化剂,单一的硝酸盐难以完全氧化铜精矿样品,并且氧化反应剧烈容易发生样品喷溅。采用四硼酸锂-偏硼酸锂混合熔剂(m∶m=67∶33),样品和熔剂质量比为1∶35,通过考察氧化剂过氧化钡-硝酸钠-碳酸钠的氧化效果,以及脱模剂的用量和加入方式、预氧化和熔融条件等,样品在高温炉中预氧化后转移至熔样机熔融,可制成合格的玻璃样片。选用合适的铜精矿国家一级标准物质,以标准物质相互混合或向标准物质中添入纯氧化铜的方式扩大校准曲线含量范围,以熔片法制样,建立了波长色散X射线荧光光谱法测定铜精矿中的铜、硫、全铁、氧化钙、氧化镁、二氧化硅、三氧化二铝等7种组分含量的方法。各组分检出限在0.054%~0.22%,校准曲线相关系数(r)均在0.9998以上,选用的3个铜精矿矿石国家一级标准物质按建立的方法进行处理后,测定结果均在认定值的误差范围内,各组分测试结果的相对标准偏差(RSD,n=12)在0.28%~4.1%;选取3个铜精矿实际样品做方法比对实验,测定值与标准分析方法的测定值无明显差异。

微区X射线荧光光谱成像法分析历史文物建筑混凝土材料成分及工艺

历史文物建筑修复与保护的首要步骤是对建材构件进行成分解析。但成型的混凝土构件成分复杂,传统技术难以直接分析。微区X射线荧光光谱具有速度快、无需前处理、可获得大面积高分辨的元素成像等优势,可用于此类混合物的原位分析。采用束斑为20μm的微区X射线荧光光谱仪,扫描成型混凝土构件以获得混合成分的元素分布图,结合基本参数定量法,对典型历史建筑混凝土构件进行元素定量。分析结果有效地解析了混凝土构建中骨料和凝胶材料的成分和含量,鉴别了涂层成分,解析了拌混工艺,鉴别了局部污染元素和致劣元素并分析致劣原因,为历史建筑修复材料选配、拌混工艺选择、除污及保护性预防劣化提供了科学的数据支撑。

Analysis of nickel distribution by synchrotron radiation X-ray fluorescence in nickel-induced early- and late-phase allergic contact dermatitis in Hartley guinea pigs

Background: Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy. Methods: Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10%(sensitization-challenge;late phase group);10% NiSO4-group, 10% to 10%(sensitization-challenge;early-phase group);and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES). Results: In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (>200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni^2+ aqueous ionic state but in the nickel-binding protein. Conclusions: This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni^2+ aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.

X射线荧光光谱法测定铝合金中的元素含量

利用X射线荧光光谱特征峰强度与元素含量之间的关系,可确定铝合金中金属元素种类和含量。本试验测量了系列铝合金标准样品(已知金属元素成分含量)X射线荧光光谱(XRF),根据金属元素特征谱线绘制XRF特征峰值与元素含量线性关系曲线。结果表明,使用XRF法检测铝合金中的元素结果准确,灵敏度高,Cu元素质量分数检出限可达3×10^(-6),灵敏度相对低的Ti元素质量分数检出限也可达16×10^(-6);用XRF法检测了散热铝合金样品中各金属元素含量,其中Cu、Zn的测量结果与激光烧蚀火花诱导击穿光谱法所测结果一致。

波长色散X射线荧光光谱法测定硫精矿中铁、硫、砷、铅、锌

硫精矿作为硫铁矿烧渣的主要原料,铁、硫、铅、锌、砷等元素含量直接影响产品硫铁矿烧渣的质量。在对硫精矿多种元素进行同时分析过程中,传统化学分析存在一定滞后性,对指导生产存在一定的限制。为快速取得可靠结果,实验采用粉末压样,波长色散X射线荧光光谱法(WD-XRF)同时测定硫精矿中铁、硫、砷、铅、锌,根据样品中硫元素含量的差距建立三条工作曲线,采用经验系数法对各曲线进行基体效应校正,同时启用X荧光仪条件选择程序(APS),样品初测后,仪器根据硫的计数率自动选择适宜的工作曲线再测一次出具最终结果。实验发现,粒度74μm的样品在压力为40t、保压25s条件下制备的样片能有效改善粒度效应对荧光强度的影响。方法用于实际样品分析,铁、硫、砷、铅、锌的相对标准偏差(RSD,n=11)分别为0.18%~0.20%、0.24%~0.26%、2.0%~3.9%、4.3%~4.5%、1.8%~2.0%,分析结果和传统化学分析方法结果一致。

熔融制样—X射线荧光光谱法测定建盏中的常量元素含量

采用X射线荧光光谱法(XRF)测定建盏中的常量元素含量(SiO_(2)、Al_(2)O_(3)、Fe_(2)O_(3)、CaO、MgO、Na_(2)O、K_(2)O、TiO_(2)),系统研究了熔剂、稀释比、脱模剂、熔融温度与时间对测定结果的影响。结果表明,当选用四硼酸锂-偏硼酸锂(67:33)作为熔剂、硝酸铵作为氧化剂、溴化锂作为脱模剂、熔剂与样品的稀释比为10:1、熔样温度为1050℃、熔融时间为10 min时,实验可获得性能优异的熔片。根据熔样方法自行制备了一套参考标样,线性良好。在最优的仪器条件下,对不同标准物质进行精密度和准确度实验,相对标准偏差RSD<4%,测量结果与计算值的误差在化学分析允许差范围内。相较于传统分析方法,此方法快速、结果准确、对环境友好。

方法标准验证实验数据中离群值的识别

对方法标准验证实验中测量数据进行合格性审核,对于后续方法精密度计算是一个重要环节。文献中识别离群值的Grubbs法、Dixon法等经典方法有时不能满足要求。探讨了用稳健统计法识别离群值的可行性。基于2套文献数据和XRF方法标准验证实验精密度测量数据,对Grubbs法、Dixon法、Mandel h检验法、质控指标法和稳健统计法(四分位法、迭代法、合格数据范围判定法)进行了比较。结果表明:稳健统计法可有效识别离群值。但四分位法存在过度"检出"现象。综合考虑多种方法识别结果有利于提高离群值判定结论的可靠性。对于个别难以判断的情形,可借助质控指标、技术要求以及数据是否剔除对实验室间标准偏差的影响进行取舍。

5种丹参主要成分及微结构的检测及综合表征

利用X射线荧光(XRF)、粉末X射线衍射(PXRD)和傅里叶变换红外光谱(FTIR)分析技术,对安国栽培的5个不同种质丹参主要成分及微结构检测,对各样品中多种元素种类及含量、晶体及非晶体成分以一套综合特征图的方式对其表征;该谱将同种属不同种质丹参中的共有成分和细微差异之处给与直观地描述。3种技术共有制样简单,测定速度快,再现性和客观性好的特点;可用于药材优良品种的选育、中药材GAP种植条件的指导、药材产地特征、主要成分及微结构的检测及表征、质量稳定性的控制及真伪鉴别。

等离子体点火中止后回收发射药的X射线荧光光谱分析

利用中止燃烧装置,对单基药、双基药、太根药及硝胺药等不同种类发射药进行常规方式和等离子体点火的比较研究。燃烧中止后,回收得到残存发射药。对这些回收发射药表面进行X射线荧光光谱(XRF)分析,以检测发射药表面由于等离子体带来的金属含量。15/19单基药和硝胺药表面的Cu沉积很少;沉积在太根药样品表面的Cu元素,经估算后其含量约为Pb元素的20%左右;而等离子体点火双芳-3的XRF谱图中,Cu元素所处的峰的强度明显增强,经估算后其含量约为Pb元素的50%左右。Cu元素在不同配方发射药表面沉积的相对含量与金属蒸汽罩模型的观点存在不一致。试验结果表明:与常规点火方式相比,等离子体点火燃烧中止后回收得到的发射药表面有金属Cu离子或原子沉积。Cu在发射药表面沉积的相对含量与等离子体发射药能量转移方式、发射药的配方及燃烧状况相关。