The addition of a high content niobium (Nb) in IN718 alloy leads to the precipitation of a large number of niobium-containing phases. The morphology, area fraction, quantity and shape of these niobium-containing phases are main factors affecting the properties of IN718 alloy. Therefore, the quantitative characterization of niobium-containing phases is of great significance for the study of the structure-activity relationship of the alloy. In this paper, the images of niobium-containing phases in the large field of view of IN718 alloy were efficiently acquired using high-throughput field emission scanning electron microscope based on its characteristics such as high imaging flux, fast automatic scanning speed and strong data processing ability. The image segmentation, recognition and statistical analysis module of niobium-containing phases were established by MIPAR image processing software, realizing the high efficiency extraction and quantitative statistical distribution characterization of niobium-containing phases in large size range of alloys. 1 225 backscattered electron (BSE) images were collected for each sample. These images were rapidly processed in batch using the established image processing module of niobium-containing phases. The information such as morphology and area fraction of niobium-containing phases in different regions of the cross section of IN718 alloy forged bar was obtained. It was found that the niobium phases in the core mostly had the shape of needles and long strips, and the area fraction was relatively high. However, there were more short-rod and round granular precipitated phases at the edge of the forgings. These data would provide guidance for the improvement of forging process and performance.

When glow-discharge mass spectrometry (GDMS) is used to determine trace cadmium in nickel-based superalloy,it is interfered by ¹¹⁴Sn⁺ and MoO⁺ polyatomic ions. After pre-correction with standard relative sensitivity factor(RSF_Std), the mass spectral interferences of multi-atomic ions including ¹¹⁴Sn⁺ and MoO⁺ were corrected by interference correction equation. Thus, a method for determination of trace cadmium in nickel-based superalloy was realized by GDMS at high-resolution mode with ¹¹⁴Cd as analytical isotope. The instrument parameters were optimized as follows:the discharge current was 48 mA; the flow rate of discharge gas was 450 mL/min; the pre-sputtering time was 20 min. The certified reference materials of nickel-based wrought superalloy with Cd certified value less than 0.1 μg/g and Mo mass fraction of 3% were used as blank samples and determined for 11 times consecutively. The limit of election and limit of quantifiation, which were calculated according to three-fold and ten-fold of standard deviation of blank sample, were 0.081 μg/g and 0.27 μg/g, respectively. The content of cadmium in certified reference material or reference material of nickel-based superalloy were determined according to the proposed method, and the results were in good agreement with the certified value/standard value. The relative standard deviations(RSD,n=6) were less than 12%. The contents of cadmium in 3 nickel-based superalloy samples were determined according to the proposed method as well as inductively coupled plasma tandem mass spectrometry (ICP-MS/MS),respectively. The results showed that the results of the above two methods were basically consistent.

Platinum and palladium are precious metal elements with high price. The contents of platinum and palladium in crude selenium is an important indicator for trade settlement, so it is of great significance to accurately determine the contents of platinum and palladium in crude selenium. In this study, a method for the determination of platinum and palladium in crude selenium by inductively coupled plasma atomic emission spectrometry (ICP-AES) after selenium volatilization with perchloric acid was established. The samples were dissolved in aqua regia. The interference of selenium matrix was eliminated by perchloric acid smoke to volatilize the selenium. Pt 265.945 nm and Pd 360.955 nm were used as the analytical lines for the determination in the medium of 10% aqua regia. The results showed that 1.0 g of sample could be completely dissolved by adding 15 mL of aqua regia. Most of the selenium matrix could be removed by adding 10 mL of perchloric acid for volatilization at high temperature. A small amount of residual selenium matrix and other coexisting elements had no interference with the measurement. The weighing method was adopted during whole test to reduce the personal error and measurement instrument error caused by volume calculation method. The content of platinum and palladium in range of 0.02-15.0 μg/g was linear to the corresponding intensity. The correlation coefficients were 0.999 93 and 0.999 98, respectively. The limits of detection for platinum and palladium were 0.000 094% and 0.000 11%, and the limits of quantification were 0.000 31% and 0.000 33%, respectively. The experimental method was used to determine platinum and palladium in crude selenium, the relative standard deviations (RSD, n=7) were less than 5%. The measured results were consistent with those obtained by oxidizing roasting-lead fire assay-ICP-AES. The precision and trueness were superior to the conventional volume calculation method. The recoveries of platinum and palladium in crude selenium sample were 98%-105% and 99%-104%, respectively.

Selenium (Se) is an amphoteric non-metallic element. As one of the essential trace elements for human body, the insufficient or excessive intake of Se will be harmful to human health. As the material basis for human survival, soil is the most fundamental source for people to obtain Se from the outside world. Therefore, it is of great practical significance to establish a highly sensitive and accurate method for the detection of Se in soil and stream sediments. Due to the characteristics of simple analysis operation, high sensitivity, fast analysis speed and low operating cost, the hydride generation-atomic fluorescence spectrometry (HG-AFS) is widely used for the determination of Se. However, the pretreatment method, light source and coexisting elements may interfere with the determination of Se, affecting the test results. In this paper, the sources and causes of the interference of Se in soil and stream sediments by atomic fluorescence spectrometry were focused on. The research and application progress of Se interference elimination were summarized and discussed. Moreover, the future development direction of hydride generation-atomic fluorescence spectrometry in the determination of Se in soil and stream sediments were prospected.

A method for analysing and characterizing the three-dimensional morphology and three-dimensional structural characteristic parameters of inclusions in steel was developed based on X-ray microscopy. Three different types of steels were selected to analyse the three-dimensional structural characteristic parameters and three-dimensional spatial distribution of inclusions, including the volume fraction, equivalent diameter, shape factor, diameter and volume distribution, sphericity and orientation. The results showed that the X-ray microscope could accurately characterize the inclusions with size of 1-500 μm in steel. It could also distinguish the high-density phase, non-metallic inclusions and micro-porosity based on the difference of contrast or grey. When the deformation of stainless steel reached 50%, the three-dimensional morphology of plastic inclusions evolved from spherical to flat, and the shape factor decreased from 0.67 to 0.57, and the spatial orientation angle (Phi) increased from 63.48° to 77.40°. For the steel treated with Te, the element of Te was wrapped outside the MnS to form a composite inclusion, which improved the corrosion resistance of the steel. According to the three-dimensional structural characteristic parameters of MnS inclusions, the three-dimensional grain boundaries of sulphur-containing steel were divided, and the relationship between the precipitation process of grain boundary inclusions and solidification selective crystallization was explained. A new method for characterizing the three-dimensional morphology and structural of inclusions in steels was established instead of synchrotron radiation, which was to promote the research of controlling the inclusions modification evolution of characterizing inclusions using X-ray microscopy. The proposed method provided more accurate and reliable analytical and testing approaches for the control of inclusions.

Q690D steel has excellent properties in strength and toughness. The inclusion in the steel is an important factor affecting the strength and toughness. The modification of inclusions is an important measure to improve the product performance. In order to investigate the modification effect of magnesium on inclusions in Q690D steel for construction machinery, the distribution pattern and size of inclusions in the steel before and after magnesium treatment were compared and analyzed using metallurgical microscopy, scanning electron microscopy, inclusion three-dimensional etcher and FactSage thermodynamic software. The results showed that the inclusions in Q690D steel after calcium treatment were mainly composed of CaO-Al₂O₃, and some of them were wrapped by CaS. The inclusions in magnesium treated steel were mainly composed of MgO·Al₂O₃ or MgO, and some of them were wrapped by MgS. Magnesium could make Al₂O₃ finer and more uniformly distributed, and the average equivalent diameter of inclusions was reduced. The number density and area fraction of inclusions in the magnesium treated rolling stock were 65 mm² and 0.031%, respectively, which were lower than those after treatment by calcium, i.e., 96 mm² and 0.050%, respectively. Magnesium treatment showed better effect to purity the molten steel and improve the size and distribution of inclusions.

In recent years,the integration of modern spectroscopic analysis technologies with development characteristics of the times (such as artificial intelligence,big data,cloud computing and the internet of things) is closer and closer,and it has been widely used in various fields including agriculture,food,petrochemicals,petrochemical engineering,metallurgy and geology.Some large-scale application achievements have been obtained in several fields,which makes a contribution to the development of technology and economy.This paper mainly introduces the constitution and characteristics of modern spectroscopic analysis technologies integrated with chemometrics,and summarizes the chemometric methodologies and advancements employed for quantitative and qualitative analysis in spectroscopy.Based on some representative instances,the application status of modern spectroscopic analysis technologies in various fields were introduced according to the application scenarios,for example,the laboratory high-throughput analysis scenarios such as rapid crude oil evaluation,grain sorting and port iron ore classification;on-site rapid analysis scenarios such as soil detection,mineral exploration,fruit picking assessment,and forensic identification;the industrial on-line analysis scenarios such as gasoline blending,smelting process material analysis,on-line coal quality analysis,and waste plastic classification.In the future,grounded in the miniaturization of spectrometers,in-depth exploration of new spectroscopic theories,and the profound amalgamation of deep learning algorithms with spectroscopic technology,the rapid developments in precision agriculture,smart factories,precision medicine,and intelligent environmental protection will offer robust impetus for the progressive evolution of modern spectroscopic analysis technologies,thus heralding further innovations and advancements.

The presence of oxygen and nitrogen impurities will seriously affect the performance of high purity copper. In this study, the sample surface was treated with lathe finishing followed by acid corrosion. Under the condition without flux, a method for the determination of trace oxygen and nitrogen in high purity copper by inert gas fusion-infrared absorption/thermal conductivity was established. The analytical power was 4 500 W. The effect of three surface treatment methods, including acid corrosion, lathe finishing, and lathe finishing followed by acid corrosion, on the determination of oxygen and nitrogen was investigated. The results showed that the influence of three surface treatment methods on the determination of nitrogen could be ignored. However, for the determination of oxygen, the determination results of lathe finishing followed by acid corrosion were much lower than those obtained by other two methods, indicating that the method of lathe finishing followed by acid corrosion could effectively remove the oxygen on sample surface. The certified reference materials of copper with low mass fraction as possible were selected to calibrate the analyzer for the determination of oxygen and nitrogen. The limits of quantification were 0.17 μg/g and 0.31μg/g for oxygen and nitrogen, respectively. The contents of oxygen and nitrogen in high purity copper sample were determined for seven times according to the experimental method. The results showed that the standard deviation (SD, n=7) of oxygen measurement values was 0.13-0.19 μg/g, and the SD (n=7) of nitrogen measurement values was 0.062-0.070 μg/g. The content of oxygen was also determined by glow discharge mass spectrometry (GD-MS) for method comparison. The measurement results of two methods were basically consistent. The high purity copper sample was selected and determined according to the experimental method. In addition, the certified reference material of copper was added for the spiked recovery test. The results showed that the recoveries of oxygen and nitrogen were between 80% and 120%.

The accurate determination of iron content in lanthanum cerium carbonate is of great significance for quality control and subsequent application of its products. The content of iron in lanthanum cerium carbonate is commonly measured by spectrophotometry. However, when the iron content was low (below 0.3%), the color change was not obvious in the determination. Moreover, the coloring process is very easily affected by other impurity ions. In this study, the sample was dissolved with hydrochloric acid, and its acidity in solution was controlled at 2%. Fe 259.939 nm was selected as the analytical line for iron. The calibration curve was prepared by standard addition method to eliminate the influence of factors such as lanthanum cerium carbonate matrix on the determination results. The content of iron in lanthanum cerium carbonate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The linear correlation coefficient of calibration curve was 0.999 9. The limit of detection of the method was 0.001%. The content of iron in lanthanum cerium carbonate was determined according to the experimental method. The relative standard deviations (RSD, n=11) of the measurement results were between 1.3% and 3.3%, and the spiked recoveries were between 98% and 103%.

A special zinc sulfate solution has appeared in the raw material procurement market for wet zinc smelting. Such zinc sulfate solution contains high contents of manganese and aluminum, which will cause interference with the determination of zinc content, seriously affecting the determination results. In this study, the zinc sulfate solution containing high content of manganese and aluminum were treated for precipitation separation of manganese in solution. Then, excessive EDTA was added to complex zinc and aluminum in acetate-sodium acetate buffer solution. The excess EDTA was titrated with zinc standard solution to obtain the total amount of EDTA that was used to complex zinc and aluminum. The Al-EDTA complex was then decomposed with ammonium fluoride, and the released EDTA was titrated with zinc standard solution. The content of zinc in zinc sulfate solution could be indirectly measured by subtracting the amount of Al-EDTA complex released EDTA from the total amount of EDTA. The contents of zinc in three high-manganese and high-aluminum zinc sulfate solution samples were determined according to the experimental method. The relative standard deviations (RSD,n=11) of measurement results were between 0.27% and 0.29%, which was less than the 0.30% required in general titration operations. The recoveries were between 95% and 101%.

The contents of Se,Ce,Zr,Ta and Te in nickel-based alloy will affect its processability, thermoplasticity, fatigue performance and creeping property. Therefore, their determination is of great significance. The sample was dissolved with hydrochloric acid, hydrogen peroxide and hydrofluoric acid. ⁷⁸Se, ¹⁴⁰Ce, ⁹⁰Zr, ¹⁸¹Ta and ¹²⁵Te were selected as test isotopes. The calibration curve was prepared by standard addition method to overcome the matrix effect. ¹⁰³Rh was used to correct ⁷⁸Se and ⁹⁰Zr, while ¹¹⁵In was used to correct ¹⁴⁰Ce, ¹⁸¹Ta and ¹²⁵Te. Consequently, a method for simultaneous determination of trace Se, Ce, Zr, Ta and Te (mass fraction below 0.005%) in nickel-based alloy N06625 was established by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the correlation coefficients of calibration curves of elements were all higher than 0.999 0. The limits of detection and limits of quantification were 0.004 5-0.38 μg/g and 0.015-1.28 μg/g, respectively. The samples of nickel-based alloy N06625 were determined according to the proposed method. The relative standard deviations (RSD, n=11) of determination results of 5 elements were between 0.87% and 9.9%, and the recoveries were between 92% and 107%. The proposed method was applied for determination of trace Se, Ce, Zr, Ta and Te in sample of nickel-based alloy N06625. The results of Se and Te were basically consistent with those obtained by hydride generation atomic fluorescence spectrometry(HG-AFS), and the results of Ce and Zr were basically consistent with those obtained by inductively coupled plasma atomic emission spectrometry(ICP-AES).

As an advanced means of micro and nano processing, the focused ion beam technology has a wide application prospect in the steel industry. In this paper, 82A cord steel billets and 55SiCr spring steel billets were selected as the test materials. A series of slicing and three-dimensional (3D) reconstruction of the composite inclusions were performed using the focused ion beam(FIB). It was found that there were some factors having adverse effects on the results in the 3D reconstruction process, such as method calibration and phase contrast differences. The results showed that the problems of distortion of reconstructed morphology and large deviation of size determination could be solved by introducing the offset calculation formula. Moreover, the reconstruction possibility of phases with insignificant differences in phase contrasts was realized by introducing energy dispersive spectroscopy mapping analysis in the series slicing process, which effectively solved the difficulties encountered in the current 3D reconstruction process and made the reconstruction results better support the project of research and development.

The solid waste resource regeneration is crucial for achieving the goals of "carbon peaking and carbon neutrality" and "zero-waste city construction", and it is also a key link in comprehensively promoting the achievement of a beautiful China. Zinc oxide concentrate (ZnO-C) is a mixture mainly containing ZnO obtained by pyrometallurgical volatilization and enrichment of Zn-containing solid waste. The impurities include metallic elements (such as iron, aluminum and calcium) and nonmetallic elements (such as fluorine, chlorine, silicon and sulfur). ZnO-C is powder-like with color of grey and black, and it is a typical waste resource utilization product. The quality of ZnO enrichment by pyrometallurgical method is different due to the difference of raw material components and technology level. In this study, the typical regeneration ZnO-C enriched material was focused on. The raw material components, enrichment process and technical parameters of pyrometallurgical enrichment were investigated. The production process and main physicochemical characteristics of ZnO-C were systematically discussed. Given that the composition of ZnO-C was crucial for subsequent processing and utilization, the content of ZnO phase as well as the composition and content of other phases in typical ZnO-C were also paid attention to. The accurately analysis and identification of ZnO-C was the key to port supervision of imported renewable resources and a prerequisite for achieving resource utilization.

The content of CaF₂ in cassiterite and lead zinc sulfide co/associated fluorite is in range of 1%-50% (mass fraction, the same below). However, the current industry standard method is applicable for fluorite samples with CaF₂ content higher than 3%. There is an empirical correction coefficient of 0.30% in industry standard methods, so the accuracy of CaF₂ determination results below 10% is not high. In this study, acetic acid (1+9) was used to separate and remove calcium containing impurities such as CaCO₃ and CaSO₄ that are easily soluble in acetic acid. Then the content of F^- which was slightly soluble in the filtrate was determined by ion selective electrode method. The residue was extracted using AlCl₃, and In was selected as the internal standard element. The content of Ca in the extraction solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of two methods were converted into CaF₂ and then added together to obtain the CaF₂ content in fluorite. Therefore, a method for the determination of calcium fluoride in cassiterite and lead zinc sulfide co/associated fluorite by ion selective electrode combined with ICP-AES was established. The effects of AlCl₃ solution mass concentration, AlCl₃ solution extraction time, and the selection of Ca and its internal standard element spectral lines on the determination of Ca were investigated. The limit of detection of CaF₂ in the method was 0.010%, and the limit of quantification was 0.040%. The contents of CaF₂ in actual samples of cassiterite, lead zinc sulfide, and fluorite certified reference material were determined according to the experimental method. The relative deviations (RSD, n=6) of the measurement results were between 0.22% and 0.90%, and the relative errors (RE) were between 0.08% and 0.63%. The method solved the problem of empirical correction coefficient in the CaF₂ determination process. The internal standard method was employed in ICP-AES to eliminate the impact of instrument drift caused by environmental temperature fluctuations and changes in electronic component performance on the analysis results. The measurement range of the proposed method was effectively improved, and it could be used for the determination of CaF₂ in cassiterite and lead zinc sulfide co/associated fluorite.

The accurate determination of iron in copper concentrate will affect the pricing and transaction of copper concentrate, the regulation of slag pattern in melting process, and the heat effect of smelting furnace. In this study, the sample was decomposed by hydrochloric acid, nitric acid, bromine, and sulfuric acid. Matrix copper in sample was converted into copper (Ⅱ), which was used as the reduction end-point indicator of iron (Ⅲ) as well as the catalyst of iron (Ⅲ) reduction. Iron (Ⅲ) was reduced to iron (Ⅱ) with potassium borohydride in sulfuric acid medium. Then the method for determination of iron content in copper concentrate by potassium dichromate titration was established using sodium diphenylamine sulfonate as the indicator. In experiments, 0.20 g of sample was dissolved with 0.1 g of ammonium bifluoride, 10 mL of hydrochloric acid, 5 mL of nitric acid, 0.5 mL of bromine, and 10 mL of sulfuric acid (1+1). After sulfuric acid smoke until the volume of solution was 1 mL, the acidity of potassium borohydride reduction process could be ensured. Copper (Ⅱ) in test solution had a catalytic effect on the reduction of iron (Ⅲ) by potassium borohydride, and it had no interference with the determination of iron. When the concentration of potassium borohydride was 20 g/L, iron (Ⅲ) could be effectively reduced to iron (Ⅱ), and meanwhile, it did not affect the determination of iron. The titration endpoint was clear when the amount of sulfuric acid and phosphoric acid mixture was 15 mL. The interference tests indicated that the interference of coexisting elements in sample with the determination of iron could be ignored. The copper concentrate reference materials and actual samples with different contents of copper were selected, and the content of iron was determined according to the experimental method. The relative standard deviations (RSD, n=7) of the determination results were between 0.20% and 0.55%. The national standard method GB/T 3884.15-2014 was used for method comparison,the t-test was conducted on the measurement results of the two methods, and the results showed that there was no significant difference between the two methods.The proposed method could be used for the rapid analysis and determination of iron content in copper concentrate in large quantities in smelting enterprises.

The content of lithium oxide in lithium ore is the key factor affecting the price of lithium ore. The atmospheric decomposition method is commonly adopted for the determination of lithium oxide in lithium ore, but it has some problems such as complicated operation and large consumption of acid. The sample was treated with 1.5 mL of sulfuric acid and 2.0 mL of hydrofluoric acid by super microwave digestion at 280 ℃. After digestion, the solution was continuously heated until sulfuric acid fuming to remove silicon and excessive hydrofluoric acid. The salts were redissolved with 1.0 mL of sulfuric acid and 25 mL of water by heating, and lithium in the test solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) with Li 610.365 nm as analytical line and emission power as 0.95 kW. Consequently, a method for determination of lithium oxide in lithium ore was established by ICP-AES after super microwave digestion. The mass concentration of lithium in range of 0.50-50.0 mg/L showed good linear relationship with its corresponding emission intensity. The correlation coefficient (r) was 0.999 7. The limit of detection of this method was 1.5 mg/kg for lithium oxide. The contents of lithium oxide in three lithium ore samples were determined according to the proposed method, and the relative standard deviations (RSD, n=8) of determination results were between 0.92% and 2.0%. The proposed method was applied for determination of two certified refence materials of lithium ore, and the results were consistent with the certified values. Two assay laboratories were selected for determination of the contents of lithium oxide in lithium ore samples according to the proposed method, and the results were consistent. Compared with the current standard methods of GB/T 509.1-2008 and GB/T 17413.1-2010, this method could save 80% of hydrofluoric acid dosage during digestion, and it is suitable for rapid inspection and clearance of imported and exported lithium ore.

The accurate determination of calcium fluoride content in low-grade fluorite tailings is of great significance for the evaluation and improvement of comprehensive recycling process.The semi-quantitative component analysis of low-grade fluorite tailings sample was first conducted by wavelength dispersion X-ray fluorescence spectrophotometer (WDXRF) and X-ray diffractometer (XRD). It was found that fluorine mainly existed in the form of calcium fluoride, and the sample mainly contained silicon, aluminum, iron, calcium, magnesium, potassium, sodium, sulfur and manganese. 4.0 g of potassium hydroxide and 0.35 g of potassium nitrate were used as flux. The sample was melted at 650 ℃ for 8 min and then leached with hot water. IC-Na pretreatment column was used to separate alkaline earth and transition metal cations such as aluminum, iron, calcium, magnesium and manganese. Thus, a method for determination of calcium fluoride in low-grade fluorite tailings was established by alkali fusion-ion chromatography. The results showed that the mass concentrations of cations such as aluminum, iron, calcium, magnesium and manganese in test solution were all lower than 0.1 μg/mL after separation with IC-Na pretreatment column. Therefore, the interference of these elements with the determination could be ignored. The calibration curve was drawn with the mass concentration of fluorine ion as x-axis and its corresponding peak area response as y-axis. The results indicated that its correlation coefficient was 0.999 6 with calcium fluoride in range of 1-30 μg/mL. Two fluorite tailings samples and one reference material of fluorite ore were determined according to the proposed method. Meanwhile, different amounts of high-grade fluorite ore certified reference material were added for recovery tests. The recoveries were between 96% and 104%. The proposed method was applied for determination of calcium fluoride in low-grade fluorite tailings samples and fluorite ore reference materials. The relative standard deviations (RSD, n=7) were between 0.54% and 1.5%. The results were consistent with those obtained by ion selective electrode method or the standard values. The proposed method was applicable for determination of calcium fluoride in low-grade fluorite tailings samples with mass fraction in range of 5%-60%.

The test of alkaline value can be used to evaluate the content of alkaline additives in engine oil, and it is one of important indicators for evaluating the performance of engine oil. In this study, the dissociation constants of 20 types of engine oils were introduced into the Henderson-Hasselbalch equation. By combining with the Nernst equation, the theoretical endpoint pH values of different engine oils were calculated. The statistical analysis was conducted using the robust statistical algorithm A in statistics, and it was found that the endpoint pH value applicable for all engine oils was -4.5. A method for determining the alkaline value of engine oil by pH potentiometric titration was established using the mixture of acetic acid and chlorobenzene as the solvent and using the mixture of perchloric acid and acetic acid as the titrant. The limit of detection of this method was 0.004 1 mg KOH/g. The standard substance of alkaline engine oil was diluted with base oil that contained no alkaline substances. After well mixing, the blank spiked samples with alkaline content of 2, 5, and 20 mg KOH/g were prepared and determined according to the experimental method. The relative standard deviations (RSD, n=6) of the measurement results were between 0.60% and 1.2%, and the recoveries of blank spiked samples were between 99% and 102%. Various engine oil Petroleum Product Alkalinity Determination Method (Perchlorate Potentiometric Titration Method) was used for method comparison. The results showed that the difference between the two methods was within the repeatability limit required by the industry standard SH/T 0251-1993. Four standard substances of engine oil with different alkaline levels were selected and determined according to the experimental method. The test results were within the range of standard deviation, and the RSDs (n=6) were between 0.37% and 0.81%. The proposed method was applied for the determination of five types of engine oil samples, and the RSDs (n=10) of measurement results were less than 1%.

Silicon carbide deoxidizer is a kind of high-performance complex deoxidizer. The determination of titanium content can trace the elemental introduction and loss in smelting process, thus more effectively improving the properties of steel. The composition of silicon carbide deoxidizer is complicated. In this study, the sample was treated by melting at high temperature. Sodium carbonate and sodium peroxide were used as mixed flux. The nickel crucible containing sample and mixed flux was heated in high-temperature furnace at 400 ℃. Then the temperature was increased to 900 ℃ and kept for 30 min to melt the sample. After complete fusion, the sample was leached with hot water and acidified with hydrochloric acid. After dilution to the mark, the solution was filtered. Ti 334.941 nm was selected as the analytical line for titanium. The calibration curve was plotted by matrix matching method. The content of titanium in filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Consequently, the determination of titanium in silicon carbide deoxidizer was established. The linear correlation coefficient of calibration curve for titanium was above 0.999 9. The limit of detection was 0.000 5% (mass fraction). The content of titanium in silicon carbide deoxidizer sample was determined according to the experimental method, and the relative standard deviation (RSD, n=7) of measurement results was 2.0%. The spiked recoveries were between 98% and 102%. The contents of titanium in seven silicon carbide deoxidizer samples were determined according to the experimental method and spectrophotometry in national standard GB/T 16555-2017. The results were consistent.

With the increasing application of magnesium and magnesium alloy, there are more and more requirements for the determination of harmful element arsenic. The sample was dissolved in nitric acid in batches by heating at low temperature. Then the acidity was adjusted with hydrochloric acid followed by adding 10 mL of thiourea-ascorbic acid solution in order to reduce As(Ⅴ) to As(Ⅲ). Thus, a method for determination of trace arsenic in magnesium and magnesium alloy was established by hydride generation atomic fluorescence spectrometry (HG-AFS). Since there are many product types and groups of magnesium and magnesium alloy, such as magnesium-aluminum series, magnesium-zinc series, magnesium-manganese series, magnesium-lithium series and magnesium-rare earth series, the effects of magnesium matrix as well as the maximum content of aluminum, zinc, manganese, copper, nickel, lithium, lanthanum, cerium, praseodymium, neodymium, gadolinium, yttrium, erbium and dysprosium in magnesium alloy on the determination of arsenic were investigated. The results showed that the interference of magnesium matrix and major alloying elements in magnesium alloy with the determination of arsenic could be ignored. It was found that the mass concentration of arsenic in range of 1.00-10.00 μg/L had linear relationship with its corresponding fluorescence intensity. The correlation coefficient of calibration curve was 0.999 7. The limit of detection of method was 0.001 4 μg/g, and the limit of quantification was 0.004 2 μg/g. Three magnesium alloy samples were determined according to the proposed method, and arsenic standard solution was added for recovery test. The relative standard deviations (RSD, n=6) of determination results were between 2.4% and 5.3%, and the recoveries were between 98% and 106%. The method comparison tests indicated that the determination results of the proposed method were basically consistent with those obtained by inductively coupled plasma mass spectrometry (ICP-MS).

To enhance the development and utilization of metal materials, the precise control of physical properties and mechanical performance of metal materials is crucial, wherein the hydrogen plays a particularly key role in influencing these aspects. In this paper, the impact and hazards of hydrogen on the performance of metal materials were summarized. The methods for determining hydrogen content in metal materials in recent years were introduced, mainly including physicochemical method, tube furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-mass spectrometry method, thermal desorption-mass spectrometry method, etc. The corresponding analysis principles, instrument structures, and technical characteristics were summarized. The review of applicable detection objects, analysis range, detection limits, and other specifications could enable the technicians in relevant fields to have a comprehensive understanding of hydrogen content detection in metal materials.

Calcium, magnesium, iron, silicon, aluminum, manganese, beryllium and phosphorus in spodumene are determined by the series of methods 3, 4, 5, 6, 7, 8 and 10 in industrial standard YS/T 509-2008 of Methods for chemical analysis of spodumene and lepidolite concentrates. The results are accurate, but there are many kinds of reagents used and the process is complicated. After the spodumene sample was treated by alkali fusion with sodium hydroxide at 630 ℃ for 15 min, it was acidified and leached with hydrochloric acid (1+3). By selecting the optimal analytical lines of elements, the contents of calcium, magnesium, iron, silicon, aluminum, manganese, beryllium and phosphorus in spodumene were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The calibration curve was drawn by matrix matching method to eliminate the influence of matrix effect. The linear correlation coefficients of calibration curves for elements were all higher than 0.999 7. The limits of quantification of elements were between 0.061 5 μg/g and 123.9 μg/g. The contents of calcium, magnesium, iron, silicon, aluminum, manganese, beryllium and phosphorus in two spodumene samples were determined according to the proposed method, and the relative standard deviations (RSD, n=7 or n=8) of determination results were all less than 2.5%. The contents of calcium, magnesium, iron, silicon, aluminum, manganese, beryllium and phosphorus in certified reference material of spodumene were determined according to the proposed method. The relative errors (RE) of determination results were between -5.00% and 7.31%.

The content of platinum is usually determined by inductively coupled plasma mass spectrometry (ICP-MS) after enrichment by fire assay. The assay button should be dissolved for determination, so the operation is complicated and there is solution dilution effect. In this study, ¹⁹⁴Pt isotope diluent was added into the sample, and platinum was separated and enriched by antimony fire assay. The antimony composite granule was obtained after cupellation and then polished to antimony slice with smooth surface. The isotope ratio (¹⁹⁵Pt/¹⁹⁴Pt) was determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The content of platinum was quantified according to the formula of isotope dilution method. Thus, a determination method of trace platinum in geochemical samples was established with direct solid sampling after fire assay enrichment. The experiments showed that when self-purified antimony oxide was used as collector agent and high purity quartz crucible was used instead of traditional fire assay clay crucible, the blank value of platinum in antimony fire assay process could be reduced to 0.52 ng, which broke the bottleneck of high blank value for platinum in fire assay process. LA-ICP-MS planar imaging results showed that the distribution of ¹⁹⁴Pt and ¹⁹⁵Pt in antimony slice was not uniform, but the rules were similar for the trend of uneven distribution. LA-ICP-MS was used for the further multipoint ablation of ¹⁹⁴Pt and ¹⁹⁵Pt in antimony slice. The results showed that the relative standard deviations (RSDs,n=6) of mass spectral intensity of ¹⁹⁴Pt and ¹⁹⁵Pt were 14.7% and 14.1%,respectively. However, for the mass spectral intensity ratio of ¹⁹⁵Pt and ¹⁹⁴Pt, the RSD was 2.5%, indicating that platinum in isotope diluent had been fully exchanged with that in geochemical samples. The proposed method was applied for determination of platinum in geochemical certifeid reference materials, and the results were basically consistent with the certified values. The RSDs (n=6) of determination results were between 2.0% and 5.1%. The proposed method realized the determination of platinum in geochemical samples by solid-solid combined analysis technique (solid high temperature melting enrichment-laser ablation direct solid sampling) and isotope dilution.

The ARL3460 spark discharge atomic emission spectrometer was used to determine the iron content in pure aluminum. As the detection time increased, the determination results of iron gradually decreased. The characteristic parameters of stability of analytical instrument were evaluated by mathematical statistics, which could not meet the stability requirements. Based on the detection principle of spark discharge atomic emission spectrometer, the cause of this malfunction was analyzed. It may be attributed to the excitation system, optical system, and photometric system. The instrument was maintained from the hardware aspect, including the maintenance of counter electrode, argon system and auxiliary electrode, the cleaning of lens, the tracing of slit, and the replacement of pipeline and photomultiplier. The stability test was conducted again after maintenance and repairment. The results showed that the stability could meet the requirements, and the stability time was improved from 0.5 h to 4 h. The hardware treatment method was more effective than the commonly used drift correction by analysis software. This method could enable the instrument to meet quality control requirements for a long time, and also provide reference for other laboratories using the same type of instrument.

In recent years,some intelligent sorting technologies for scrap metals based on algorithms and material composition have gradually emerged,including machine vision,X-ray fluorescence spectrometry(XRF),X-ray diffraction topography(XRT) and laser-induced breakdown spectroscopy(LIBS).The latest progress of these technologies in classification of scrap metals were reviewed.It indicated that the machine vision had achieved industrial application demonstration with a high level of automation,but further improvements were needed to address its sensitivity to the environmental conditions.The elemental identification capabilities of XRF/XRT were strong,but limited to specific metal types.Currently,the commercial instruments for sorting metals,plastics,and ores are quite mature in the market.LIBS technology,with its wide elemental detection range that theoretically covers the entire periodic table,suffers from low detection efficiency and is still under research and development.Each technology above has its advantages and disadvantages,requiring integration and innovation to optimize the sorting results.In the future,the combination use of multiple technologies should be explored to enhance sorting capabilities,customized to meet market demands,and independent research and development should be strengthened to enhance core competitiveness.Full-process automation will improve efficiency,and the integration of artificial intelligence(AI),blockchain,and cloud computing technologies will push the scrap metal intelligent sorting industry to a new level.

The accurate determination of silicon content in chromium carbide is of great significance for the quality control of products. The sample was fused with sodium peroxide. After leaching with hot water and acidification, chromium was removed by volatilization with hydrochloric acid. Under certain acidity conditions, silicon could react with ammonium molybdate to form silicon molybdenum yellow. The mixture of oxalic acid and sulfuric acid was added to eliminate the interference of phosphorus and iron, and ascorbic acid was added to reduce silicon molybdenum yellow to silicon molybdenum blue for spectrophotometric determination at 810 nm. Thus, a method for determination of silicon in chromium carbide was established by silicon molybdenum blue spectrophotometry with alkali fusion. The results showed that the mass concentration of silicon in range of 0.05-1.20 μg/mL showed good linear relationship with its corresponding absorbance with correlation coefficient of 0.999 9. The apparent molar absorptivity was ε=22.41×10³ L·mol^-1·cm^-1. The limit of detection and limit of quantification for this method were 0.001 7% and 0.005 2%, respectively. The interference tests of coexisting ions showed that the residual chromium in test solution as well as phosphorus and iron in sample had no interference with the determination of silicon. The contents of silicon in three chromium carbide samples were determined according to the proposed method, and the relative standard deviations (RSD, n=9) were between 0.51% and 5.8%. Two chromium carbide samples were conducted for standard addition recovery tests, and the recoveries were between 97% and 102%.

At present, the detection methods of zinc concentrate are mainly wet chemical methods. However, the sample preparation of these methods is complicated and the operation is cumbersome. Therefore, it is of great significance to find an accurate and rapid detection method for zinc concentrate to improve the detection efficiency. In this study, the handheld X-ray fluorescence spectrometer was employed for the rapid detection of five major and minor components in zinc concentrate, including Zn, S, Fe, Ca and Pb. The samples were prepared by grinding and tableting. Different drying periods were set to explore the effect of moisture content. It was found that the higher the moisture content, the greater the relative error (RE) of the determination results. The relative error of Pb with lower content in the sample was up to 39.02% when the moisture content was the largest. Different ball milling time was also set to explore the influence of particle size, and it was found that the change of particle size had the greatest impact on S and Fe. The relative error reached 10.43% and 19.68% when the ball milling time was 3 h, respectively. Moreover, more accurate measurement results could be obtained for the sample with smaller particle size, the ball milling time of 9 h was determined. Different compression time was also investigated to explore the effect of tablet thickness, and the holding time of 60 s was determined in experiments. Four zinc concentrate samples were detected according to the experimental method. The relative standard deviations (RSD, n=5) of Zn,S,Fe and Ca were all less than 1.5%, and the RSD of Pb with lower element content was also less than 3%. The measured values of inductively coupled plasma optical emission spectrometry (ICP-OES) were used as reference values, and the measured values of the experimental methods were compared with the reference values. It was found that the relative errors of the detection results of all five elements was less than 10%, which could meet the requirements of routine analysis and detection. The proposed method had important reference value for the rapid detection of minerals.

The determination of rare earth elements in graphite ore is of great significance in evaluating resource value, protecting the environment, and scientific research. In experiments, the samples were treated by high-temperature microwave digestion in HNO₃-HF-HClO₄-H₂SO₄ system. The collision mode was used with helium (He) flow rate of 4-5 mL/min. ⁴⁵Sc, ⁸⁹Y, ¹³⁹La, ¹⁴⁰Ce, ¹⁴¹Pr, ¹⁴⁶Nd, ¹⁴⁷Sm, ¹⁵³Eu, ¹⁵⁷Gd, ¹⁵⁹Tb, ¹⁶³Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ¹⁷²Yb, and ¹⁷⁵Lu were selected as the isotopes to be measured. Sc, Y, La, Ce and Pr were corrected using Rh, and Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were corrected using Re. The multi-atomic ion interference of ¹⁵⁷Gd, ¹⁵³Eu, ¹⁵⁹Tb and ¹⁶⁹Tm was corrected by the interference correction equation. The method for the determination of 16 rare earth elements in graphite ore by electrical coupled plasma mass spectrometry (ICP-MS) with microwave digestion was established. Under the optimized experimental conditions, the linear correlation coefficients of calibration curves of rare earth elements were between 0.999 7 and 1.000 0. The limits of detection were between 0.002 6 and 0.065 μg/g, and the limits of quantification were between 0.008 7 and 0.22 μg/g. The contents of 16 rare earth elements in graphite ore standard substances for composition analysis were determined according to the experimental method for 15 times in parallel. The relative standard deviations (RSD, n=15) of determination results were all less than 3.5%. The mixed standard working solution of rare earth elements were added based on 0.5-2 fold of element content for the spiked recovery tests, and the recoveries were between 90% and 105%. 16 rare earths in graphite ore sample were analyzed according to the experimental method, and the measurement results were basically consistent with those obtained by ashing-mixed acid dissolution-ICP-MS method.

Effect of heat treatment temperature and time on phase variation characteristic of decomposition product of crystalline aluminum chloride was investigated. The composition and microtopography of crystalline aluminum chloride were analyzed and discussed by inductively coupled plasma atomic emission spectrometer (ICP-AES) and metallographic microscope. The results showed that the purity of crystalline aluminum chloride was relatively high. It contained trace impurity elements such as sodium and calcium, and it belonged to orthorhombic structure. While, aluminum oxide showed irregular elliptic with particle size of 100-210 μm. The phase change characteristics of decomposition product were investigated with thermal gravimetric analyzer and X-ray diffractometer (XRD). The results showed that the crystalline aluminum chloride lost small amount of free water under heat treatment at 80-100 ℃. The decomposition rate after 120 min was 6.95%, and the phase was still crystalline aluminum chloride. The decomposition rate was 35.84% after heat treatment at 150 ℃ for 120 min. The decomposition rate was 87.31% after heat treatment at 200 ℃ for 120 min. The decomposition velocity at 600-1 200 ℃ was very fast, and the sample could be completely decomposed within 5 min. The decomposition rate of crystalline aluminum chloride was in direct proportion to heat treatment temperature and time, and heat temperature was the dominant factor. When the heat treatment temperature was 200-700 ℃, the decomposition product phase was ρ-type or amorphous aluminum oxide. When the heat treatment temperature was 800-1 000 ℃, the decomposition product phase was mainly in γ-type, δ-type and or η-type aluminum oxide. Wherein, a small amount of α-type aluminum oxide was observed in decomposition product at 1 000 ℃. When the heat treatment temperature reached 1 200 ℃, all phases were converted into α-type aluminum oxide with most stable energy. This study provided data basis for the theoretical research and pilot equipment selection in heat treatment of crystalline aluminum chloride in the laboratory. It also provided data support for the process parameter optimization in heat treatment of crystalline aluminum chloride.

Manganese could enhance the toughness of ferroboron. The accurate determination of manganese is helpful for the production of high-quality ferroboron alloy materials. The sample was dissolved in aqua regia at low temperature and digested by perchloric acid fuming. Manganese was oxidized to septivalent with sodium periodate in sulfuric acid-phosphoric acid medium and then determined at 530 nm by spectrophotometry. Thus, a method for determination of manganese in ferroboron was established by periodate sodium oxidization spectrophotometry. The samples were treated by three methods, i.e., perchloric acid fuming in presence of sulfuric acid and phosphoric acid, perchloric acid fuming followed by adding sulfuric acid-phosphoric acid, and slag dissolution with acid. The results showed that the determination results of manganese in ferroboron samples were basically consistent by the three methods above. The determination results of manganese in certified reference materials/reference material of ferroboron were consistent with the certified values/standard value. Wherein, the operation of perchloric acid fuming followed by adding sulfuric acid-phosphoric acid was the most simple. The determination range of method was 0.050%-1.00% (mass fraction, the same below). The correlation coefficient of calibration curve was 0.999 99. The apparent molar absorptivity was 2.3×10³ L·mol^-1·cm^-1. The limits of detection and limits of quantification for this method were 0.004% and 0.012%, respectively. The contents of manganese in certified reference material and actual samples of ferroboron were determined according to the proposed methods. The relative standard deviations (RSD, n=11) of determination results were between 0.25% and 0.46%. The contents of manganese in three certified reference materials/reference material and two actual samples of ferroboron were determined according to the proposed methods. The determination results of certified reference materials/reference material were consistent with the certified values/standard value, and the determination results of actual samples were consistent with those obtained by slag dissolution with acid-inductively coupled plasma atomic emission spectrometry (ICP-AES).

In standard method of GB/T 14840-2010, the silicate minerals in limestone are dissolved with hot phosphoric acid to separate free silica, then the content of free silica is determined by gravimetry. However, the operations are cumbersome and time-consuming. In this paper, free silica in limestone was separated from limestone by means of the property that hot phosphoric acid could dissolve silicate minerals but hardly dissolve free silica. Then, the dissolved silicic acid was depolymerized with fluoroboric acid. After filtration with dense filter paper, free silica could be fully separated from other minerals. Then the precipitates were washed with hot water for three times followed by ashing in silver crucible. After fusion with 1.5 g of sodium hydroxide and leaching with hydrochloric acid, the content of silica in sample solution was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES) with Si 251.611 nm as analytical line. Consequently, a method for determination of free silica in limestone was established. The linear correlation coefficient of silica calibration curve was 0.999 9, and the linear range was 0.024%-10.0%. The limit of detection and the limit of quantification were 0.008% and 0.024%, respectively. The contents of free silica in 4 certified reference materials of limestone were determined according to the proposed method, and the relative errors between the determination results and certified values were in range of -0.18%-0.48%. The relative standard deviations (RSD, n=12) were between 1.2% and 1.9%. The proposed method and the gravimetric method in standard method of GB/T 14840-2010 were applied in determination of 4 limestone samples for method comparison, and the determination results of the two methods were basically consistent.

Lithium ore is an important national strategic resource. The accurate determination of lithium content in lithium ore is of great directive significance for the mining and processing of lithium ores. The sample cannot be fully digested in acid mixture system in open environment or there is loss for lithium in digestion process, which cannot meet the requirements of accurate determination. In this study, the sample could be digested completely with nitric acid-hydrofluoric acid system in a high-pressure closed system at 190 ℃.Thus,a method for determination of lithium in lithium ore by inductively coupled plasma atomic emission spectrometry(ICP-AES) was established with Li 670.784 nm as analytical line. The standard solution series were prepared by matrix matching method to eliminate the influence of matrix effect on the determination. The coexisting elements such as calcium, sodium, potassium, magnesium, iron, manganese and phosphorus had no influence on the determination. The mass concentration of lithium in range of 0.50-50 μg/mL showed good linear relationship with its corresponding emission intensity, and the linear correlation coefficient of calibration curve was 0.999 8. The limit of detection of method was 0.003%. The proposed method was applied for determination of certified reference materials and samples of lithium ore. For certified reference materials, the results were basically consistent with the certified values, and the relative standard deviations (RSD, n=12) of determination results were between 0.84% and 1.4%, then the relative errors (RE, n=12) were between -1.24% and 0.51%. For lithium ore samples, the RSDs (n=12) of determination results were between 1.6% and 2.0%, and the recoveries were between 98% and 104%.

It is of great significance for ecological environment protection to determine accurately and efficiently volatile phenol content in sediment. The liquid-solid ratio was controlled at 15∶1. Volatile phenol in the sample was extracted with 10 g/L sodium hydroxide solution after oscillation at 180 r/min for 15 min. Meanwhile, 3.0 g of copper sulfate was added to remove the interference of sulfides in the sample. Thus, the determination of volatile phenol in sediment was realized by flow injection analyzer. The results showed that the mass concentration of volatile phenol in range of 0.02-1.0 mg/L exhibited linear relationship to its corresponding peak area with correlation coefficient of 0.999 9. The limit of detection and lower limit of determination for this method were 0.08 mg/kg and 0.32 mg/kg, respectively. Three sediment samples with different concentrations of volatile phenol content in sediment were determined according to the proposed method, and the relative standard deviations (RSD, n=6) of determination results were between 0.83% and 1.4%. Two types of sediment sample were selected for recovery tests with three content levels, respectively. The recoveries were between 93% and 104%. The contents of volatile phenol in six sediment samples were determined according to the proposed method as well as 4-ampyrone spectrophotometry in standard method of HJ 998-2018. The results of the two above methods were basically consistent.

The determination uncertainty could intuitively reflect the quality control level of determination process. With the issue and implementation of standards such as GB/T 22553, Top-down method has attracted more and more attention. The determination uncertainty of niobium content in IN718 nickel-based superalloy was evaluated and compared based on Top-down method and GUM method. It was found that the uncertainty evaluated by reproducibility standard deviation (s_R) in Top-down method was much higher than that in GUM method. The related references about the uncertainty evaluation of metal materials in recent years were analyzed. The simplified Top-down method was used. The ratio (U(R_w)/U(w)) of the uncertainty evaluated by intermediate precision to the uncertainty evaluated by GUM method was treated by robust statistical method. It was found that the robust mean value was 1.20, and the robust standard deviation was 0.48, indicating that the evaluation results of the two above methods were in good agreement. Compared to GUM method, the simplified Top-down method did not require to identify the components of weighing, certified reference material and repeatability. Moreover, the complicated calculation and combination were not necessary. The evaluation process was simple and easily conducted. The proposed method could help the laboratories evaluate the uncertainty conveniently and rapidly, which could promote the improvement of laboratory quality control level.

Laser-induced breakdown spectroscopy (LIBS) is an atomic spectroscopy technique, and it has shown great potential in the field of metal failure detection.As one of the important indicators to measure metal aging,the detection of grain size grade by LIBS is of great significance for the prediction of failure characteristics.In this study,12Cr1MoV steel,which is widely used in industry,was selected and the grain size grade of the metal was evaluated using a portable LIBS device.Firstly,principal component analysis(PCA),linear discriminant analysis(LDA),recursive feature elimination(RFE)-LDA were used to reduce the dimensionality of the spectral data.Then the metal grain size grade evaluation model was established based on the data after dimensionality reduction using the support vector machine(SVM) and multilayer perceptron(MLP) classification algorithms.The influence of the remaining features on the classification performance of the model after the preliminary RFE screening of the data was explored.The results showed that the combination of RFE and LDA could improve the classification accuracy of the evaluation model,and it was found that the model constructed by further combination with MLP classification algorithm had the highest classification accuracy,which reached 94.05%.The proposed modeling scheme could effectively realize the evaluation of grain size grade of 12Cr1MoV steel based on portable LIBS equipment.

In order to improve the flexible analysis capability of laser-induced breakdown spectroscopy(LIBS) under various extreme environments, the miniaturization design of remote LIBS instrument was realized in this study. The instrument adopted modular design, and the tripod head was used as base support. It was applicable for the flexible detection and analysis of remote targets. 8 certified reference materials of alloy steel were used as the experimental subject. The spectral acquisition was carried out under the condition of 2 m. 3 elements in certified reference materials, including Si, Mo and Cr, were quantitatively analyzed. The quantitative models of 3 elements were established by random forest (RF) algorithm, and the coefficients of determination were 0.999 8, 0.998 8 and 0.999 1, respectively. During the model validation, the minimum relative errors of predicted contents of 3 elements (Si, Mo and Cr) in validation samples were 14.6%, 12.9% and 11.6%, respectively. The developed miniaturized remote laser-induced breakdown spectroscopy instrument showed good remote quantitative detection capability.

Accurate and rapid determination of boron and impurities in ferroboron is of great importance for the scientific guidance of ironmaking and steelmaking production as well as ensuring the quality of high value-added steel. In this study, the sample was prepared by powder pressed pellet. The calibration sample series, which had a certain gradient and a certain content span covering the content ranges of elements in the sample, were prepared with 2 ferroboron certified reference materials and ferroboron samples determined by national standard method to overcome the matrix effect. Thus, the determination of B, Al, Si, P, S, Ti and Mn in ferroboron was realized by X-ray fluorescence spectrometry(XRF). The sample preparation conditions were optimized: 1.50 g of sample with particle size of 53 μm (screened with 280 mesh) was edged with boric acid and then pressed at 44 MPa for 40 s. The matrix effect of boron was corrected by concentration correction with empirical coefficient method. The limits of detection were listed as below: 0.085% for B, 0.000 99% for Al, 0.001 9% for Si, 0.000 72% for P, 0.000 41% for S, 0.003 4% for Ti, and 0.003 9% for Mn. The proposed method was applied for the determination of 6 different pellets which were parallelly prepared with ferroboron samples. The relative standard deviations (RSD) of determination results of elements were all less than 2.0%. The ferroboron samples were determined according to the proposed method, and the results were basically consistent with those obtained by other methods: B was determined by alkalimetry in GB/T 3653.1-1988; Al was determined by EDTA titration method in GB/T 3653.4-1988; Si was determined by perchloric acid dehydration gravimetry in GB/T 3653.3-1988; P was determined by antimony phosphomolybdenum blue spectrophotometry in GB/T 3653.6-1988; S was determined by infrared absorption method in GB/T 3653.7-2020; Ti and Mn were determined by inductively coupled plasma-atomic emission spectrometry in GB/T 6730.63-2006.

The chemical composition, metallographic structure, macro and micro morphology of fracture splitting, and mechanical properties of C70S6 material connecting rod were detected and analyzed by spark discharge atomic emission spectrometer, metallographic microscope, scanning electron microscope (SEM) and universal tensile testing machine. The fracture splitting drop-dregs cause and mechanism of connecting rod big head hole were analyzed. The results showed that the fracture splitting drop-dregs position was mainly near billet parting plane, and the grain size at the parting plane of drop-dregs connecting rod was Grade 6.5. The content of ferrite was 7.0% (mass fraction, the same below), and the grain size difference of the whole fracture splitting surface was Grade 3.5. The edge of dropped steel slag showed obvious characteristics of ductile fracture. The grain size at the parting plane of no drop-dregs connecting rod was Grade 5, and the ferrite content was 5.0%. The grain size difference of fracture splitting surface was Grade 0.5, and the microstructure uniformity was good. The microstructure showed the characteristics of brittle cleavage. The comprehensive analysis showed that the microstructure of connecting rod billet was not uniform, the local grains were fine, and the overall grade difference was large, resulting in the high local plasticity of billet material, which was the root cause of the chip loss. By adjusting the production and heat treatment process of the bar for forging connecting rod, the grain size of microstructure was coarsened, the grain size difference and ferrite content was reduced. Consequently, the problem of drop-dregs loss was completely eliminated.

Accurate determination and control of carbon content in praseodymium neodymium fluoride-lithium fluoride electrolytes is of great significance for the monitoring of praseodymium neodymium alloy production process and the quality of finished products. A method for the determination of carbon content in praseodymium neodymium fluoride-lithium fluoride electrolyte by high-frequency combustion infrared absorption was established. The analytical time was controlled at 35 s, and the sampling mass was 0.20-0.30 g. The standard sample of steel was used for the preparation of single-point calibration curve. Tungsten, tin, and iron were selected as the flux. An orthogonal experiment with four factors and three levels was designed, and the investigation factors includes the mass of tungsten, the mass of tin, the mass of iron, and the adding sequence of flux and sample. Through the experiments, the adding sequence of flux and sample was pure iron + sample + tungsten and tin. The dosage of flux was 0.60 g of iron, 1.20 g of tungsten, and 0.40 g of tin. The limit of detection of method was 0.000 255% (mass fraction, the same below), and the limit of quantification was 0.000 85%. Three different batches of praseodymium neodymium fluoride-lithium fluoride electrolyte samples were measured according to the experimental method, and the relative standard deviations (RSD, n=11) of determination results were between 2.8% and 3.3%. The Grubbs outlier judgment method was used to identify the outliers. The Grubbs G_Max of measurement results of three batches was 1.463, 1.503, and 1.335, and the G_Min was 1.704, 1.639, and 1.669, respectively. They were all less than the Grubbs critical value G_(0.05,11)=2.234 (significant level α=0.05), indicating that there were no abnormal values in the measurement results. The standard steel sample was used into the sample for spiked recovery tests, and the recoveries were between 96% and 105%.

Solid wastes identification were conducted on a batch of samples declared as “lead ore” with high content of arsenic and iron. Through the feature detection and analysis including elemental content, phase composition, microtopography, particle size distribution and pH of leaching solution, it was found that the main phases of this sample were jarosite and scorodite. The main elements included S, Fe, Si, As, Al and Ca, while the content of Pb was low, which was not consistent with the characteristic of common lead ores. Several solid wastes with similar composition were compared to infer the sample source. Several possibilities of sample source were excluded: jarosite slag in traditional zinc hydrometallurgy, oxygen pressure leaching slag of zinc concentrate, arsenic slag of flue gas cleaning in lead-zinc smelting, or arsenic deposition slag of mineralized arsenic fixation of metallurgical waste water. Finally, it was inferred that the sample was possible the lead-zinc ore tailings which was exposed to the earth′s surface. The refused ore mainly containing scorodite and jarosite was formed after long-term oxidization. According to GB 34330-2017, the sample was identified as solid waste.