RESEARCH ON SMELTING LOW-CARBON FERROCHROME IN A PLASMA FURNACE

By a non-transformed arc plasma torch whose gas is nitrogen,scrap of high-carbon ferrochrome was heated and melted in a sealed furnace. When the liquid bath was at 1600℃,top blowing of oxygen began to decrease the bath's carbon without stopping plasma operation for its temperature addition and maintennace of at least 1750 ℃. The liquid bath was agitated by bottom-blowning nitrogen. In the experiments low carbon Fe-Cr have been obtained whose composition respectively was 0.45% carbon,50.75% chrome and 0.42% carbon, 70.25% chrome. Loss of chrome could be less than 5%.

Effects of Heat-treatment on Crystallization and Wear Property of Plasma Sprayed Fe-based Amorphous Coatings

The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous- nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.

Dual Torch Plasma Arc Furnace for Medical Waste Treatment

In this paper, characteristics of a treatment and operated at atmospheric pressure dual torch plasma arc used for hazardous waste are studied, and also compared with those of the multi-torch plasma arc and the single torch plasma arc. The dual torch plasma arc is generated between the cathode and anode with argon as the working gas. The temperature distributions of the plasma arc are measured using a spectroscope and line pair method with the assumption of local thermodynamic equilibrium （LTE） for the DC arc current I=100 A and argon flow rate Q = 15 slpm. The measurements show that the temperatures of the dual torch arc plasma in the regions near the cathode, the anode and the center point are 10,000 K, 11,000 K and 9,000 K, respectively. And the high temperature region of the multi torch plasma arc is of double or much wider size than that of a conventional dual torch plasma arc and single plasma torch. Based on the preceding studies, a dual torch plasma arc furnace is developed in this study. The measured gas temperature at the center region of the argon arc is about 11,000 K for the case of I=200 A and Q=30 slpm operated in atmosphere.

3D Numerical Analysis of the Arc Plasma Behavior in a Submerged DC Electric Arc Furnace for the Production of Fused MgO

A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.

Behavior of an indigenously fabricated transferred arc plasma furnace for smelting studies

The utilization of industrial solid waste for metal recovery requires high-temperature tools due to the presence of silica and alumina, which is reducible at high temperature. In a plasma arc furnace, transferred arc plasma furnace（TAP） can meet all requirements, but the disadvantage of this technology is the high cost. For performing experiments in the laboratory, the TAP was fabricated indigenously in a laboratory based on the different inputs provided in the literature for the furnace design and fabrication. The observed parameters such as arc length, energy consumption, graphite electrode consumption, noise level as well as lining erosion were characterized for this fabricated furnace. The nitrogen plasma increased by around 200 K（200 ℃） melt temperature and noise levels decreased by ~10 d B compared to a normal arc.Hydrogen plasma offered 100 K（100 ℃） higher melt temperature with ~5 d B higher sound level than nitrogen plasma. Nitrogen plasma arc melting showed lower electrode and energy consumption than normal arc melting, whereas hydrogen plasma showed lower energy consumption and higher electrode consumption in comparison to nitrogen plasma. The higher plasma arc temperature resulted in a shorter meltdown time than normal arc with smoother arcing. Hydrogen plasma permitted more heats, reduced meltdown time, and lower energy consumption, but with increased graphite consumption and crucible wear. The present study showed that the fabricated arc plasma is better than the normal arc furnace with respect to temperature generation, energy consumption, and environmental friendliness. Therefore, it could be used effectively for smelting-reduction studies.

纺织品及附件铅释放量的测定

文章建立以人工睡液为萃取介质,测定纺织品及纺织品附件中铅释放量的试验方法,优化样品前处理条件和测试仪器参数。试验结果表明:采用电感耦合等离子体发射光谱法测定的定量限为0.02μg/(cm^(2)·h),在低、中、高3个加标浓度下的回收率在93.26%~107.65%,相对标准偏差为1.03%~5.99%(n=7);采用石墨炉原子吸收光谱法测定的定量限为0.01μg/(cm^(2)·h),在低、中、高3个加标浓度下的回收率在82.65%~110.32%,相对标准偏差为1.08%~4.61%(n=7)。该方法前处理步骤简单,检测流程短,结果准确度高,适用于可放入婴幼儿和儿童口中的纺织品及其附件的检测。

Research on Refining Technology of Clean Steel in a Plasma Ladle Furnace

The clean steel refining tests carried out in a 100 kg plasma ladle furnace(PLF)were to show the metallurgical effects of the different plasma gases such as Ar-H_2 and Ar-CO_2.The variations of carbon,nitrogen contents in steels and the mechanism of denitrogenation were studied.Compared with the conventional ladle furnace,when the plasma gases were injected into the ladle furnace,there was a decarburization process,the carburetion rates were reduced obviously. The carburetion rate is 3.6×10^(-6) per minute for the steel heated by conventional LF,and is 2.20 and 1.35 times of the heats blown 85%Ar-15%H_2 and 85%Ar-15%CO_2,respectively.When the plasma ladle furnace operated with Ar-H_2 plasma gas, the denitrogenation of the molten steel occurs.The lowest denitrogenation rate is 0.30×10^(-6)per minute when Ar-H_2 gas mixtures were used.The main reactant gas is monatomic hydrogen and the main product of denitrogenation is NH_3 for Ar-H_2 injection.

L型等离子体熔融炉预热升温数值模拟及优化研究

L型等离子体熔融炉因其具有热解气化效率高、抑制核素挥发等特点,在低中放射性废物处理方面具有独特优势。由于炉内等离子体炬的高温特性,在预热阶段采用等离子体炬升温存在温度不可控的问题,从而可能造成炉内温度分布均匀性差,严重时甚至会造成炉内局部耐火材料的损伤甚至失效。文章针对L型等离子体熔融炉搭建了有限元数值模拟模型,探究了热风进口分布位置及等离子体炬安装位置对预热效果的影响。结果表明,对称式送风布置形成热风对冲区导致炉内热量传递受阻,而采用单侧热风进口布置可避免上部竖炉和下部炉膛的交界拐角处的低温区,使炉内温度梯度较小。通过试验对比,开启3个单侧送风口,进风总流量为200 m^(3)/h、热风温度为200℃、等离子体炬(76 kW)相对位置布置夹角为40°时,炉内整体温度分布均匀性较优。文章结论可为L型等离子体高温熔融炉的设计及运行提供实际指导,提升设备可靠性及安全性。

ICP-MS法和GF-AAS法检测乳粉中铬元素的测量系统评价

铬元素是食品质量安全重点监测项目,GB 5009.123—2023《食品安全国家标准食品中铬的测定》中规定了食品中铬的2种常用检验方法:石墨炉原子吸收光谱(graphite furnace atomic absorption spectrometry,GF-AAS)法和电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法。使用Minitab统计分析工具,运用控制图法、独立样件法、t检验法及方差分析法对上述2种常用检验方法测量系统的稳定性、偏倚、线性、重复性与再现性进行分析。结果表明:2种检测方法测量系统极差图和均值图均无异常点,组内误差处于统计受控状态,稳定性良好;量具线性和偏倚分析结果均不存在显著偏倚和显著线性误差;量具R&R报告分析结果表明,ICP-MS法和GF-AAS法测量系统重复性和再现性良好;双因子方差分析表明,样品是唯一显著影响测量误差的因子;研究变异分析表明,测量系统误差可以接受。ICP-MS法和GF-AAS法不仅能有效保障乳粉中铬元素含量检测数据的可靠性和可重复性,为实验室进行测量系统的误差分析与控制提供科学依据,同时也为乳制品中其他重金属检测及其他食品中重金属检测的测量系统评价提供一定参考。

火焰原子吸收光谱法、石墨炉原子吸收光谱法和电感耦合等离子体发射光谱法测定地表水样中铜的研究方法对比

采用火焰原子吸收光谱法(FAAS)、石墨炉原子吸收光谱法(GF-AAS)和电感耦合等离子体发射光谱法(ICP-OES)分别测定地表水中的铜,对检出限、精密度、正确度、低浓度环境样品测试等指标进行对比。实验结果表明,三种方法对于测定地表水中铜,测试结果无显著差异;与FAAS和ICP-OES法相比,GF-AAS法具有较低的检出限、较高灵敏度,对于测定低浓度环境样品具有较高的准确性。

等离子炉碳（氮）化处理高钛高炉渣

用氮等离子体对高钛渣进行碳（氮）化处理，在１７００℃下停留１ｈ，可使渣中钛的碳（氮）化转化率达９２％，大于２０μｍ的Ｔｉ（Ｃ，Ｎ）晶粒约４０％。用重选方法选别碳化渣可得到含Ｔｉ（Ｃ，Ｎ）５０％以上的精矿，钛的回收率可达９０％以上。

利用滑动弧放电脱除烟气中多环芳烃和碳黑颗粒

由于PAH和碳黑颗粒对环境和人体健康的危害已经引起各国的重视,成为国内外学者的研究重点。从PAH和碳黑颗粒的控制方法来看,低温等离子体法可以同时脱除这两种污染物。该文用管式沉降炉焚烧聚乙烯(PE)和聚氯乙烯(PVC)生成含有多环芳烃和碳黑颗粒的烟气,研究了利用滑动弧放电同时脱除烟气中多环芳烃(PAH)和炭黑颗粒的方法。研究发现:降低烟气温度有利于PAH和碳黑颗粒的脱除;PAH最高脱除率达到74.4722%,碳黑颗粒最高脱除率为89.391%。实验结果表明,此项技术可有效同时脱出PAH和碳黑颗粒。

石墨炉原子吸收法测定人体血浆和尿中锗

研究了口服有机锗（Ｇｅ－１３２）后人体血浆及尿中锗的测定方法。以５％三氯乙酸溶液沉淀血蛋白，离心分离后，取上清液测定。以钯和硝酸镍混合溶液做基体改进剂，提高灰化温度至１４００℃，消除了样品中大量基体对测定锗的干扰。方法特征量为３１ｐｇ，检出限为２８ｐｇ（３σ），样品加标准回收率为：血浆９１．４％～９７．０％，尿９７．２％～１０５％。

石墨炉电热蒸发进样与ICP-AES联用技术研究——仪器装置及其分析性能

将石墨炉作为蒸发器与ICP-AES联用,改善其检出限并赋予微量体积样品分析的能力。用自己组装的仪器,选择了等离子体和石墨炉各自最佳操作参数。结果表明,取样量为10μL时,大多数元素的检出限达μg/L级;相对标准偏差5％;线性范围达4个数量级。

大管回流消解ICP-MS测定植物样品中的Hg及其他痕量元素

针对易挥发元素Hg提出了大试管和红外加热的多孔控温消解炉的简单装置消解植物样品的大管回流法。该方法结合ICP-MS测定Hg,指出在0.18%L-半胱氨酸加入内标做清洗液消除汞的记忆效应,校准曲线有一个更好的相关系数r=0.9993,Hg的测定限可达0.012μg/g(10σ,DF=100);并比较了原子荧光测定Hg的测定限0.0013μg/g(10σ,DF=100)和测定结果。该方法经标准物质GSV-3、GSV-4、GSB-1、GSB-6、GSB-10和GSB-4验证,测定值与标准值基本吻合。实验结果表明,该消解方法中Hg基本没有损失,而且ICP-MS的测定Hg的同时可以测定Li、B、Cr、Mn、Co、Ni、Cu、Zn、As、Sr、Mo、Cd、Ba和Pb等痕量元素。

直流电弧炉电弧等离子体射流的数值模拟

数值模拟是研究直流电弧炉中电弧等离子体射流特性的有效方法,它可为理解和优化电弧炉冶炼过程提供参考依据。本文对直流电弧炉冶炼过程建立了电弧等离子体的二维稳态轴对称磁流体力学模型,采用大型商业软件PHOENICS对电弧流场和温度场进行了计算,仿真结果与文献报导的实际测量结果吻合良好。

电感耦合等离子体原子发射光谱法测定高炉渣中硼

采用电感耦合等离子体原子发射光谱法测定高炉渣中硼，优选了适宜的仪器测定参数和分析谱线，研究了基体效应、共存元素间干扰及校正。实验结果表明，采用H2SO4-H2PO4-H2O2混合酸体系分解试样，可使样品溶解完全。通过对基体及共存元素干扰测定的考察，选择出208．959nm，249．678nm两条谱线做为硼的分析线。其中，共存元素Fe谱线（249．653nm）对B线（249．678nm）的干扰，Mo谱线（208．952nm）对B线（208．959nm）的干扰可分别采用离峰单背景扣除及干扰系数校正法进行校准，基体元素Ca，Al，Mg对B谱线的影响，可通过基体匹配的方法消除。在选定的条件下，硼量在0．001％～1．0％范围内线性关系良好，相关系数大于0．9990，方法检出限可达到0．0020μg／mL，所建立的方法应用于高炉渣中硼的测定，回收率在97．0％～108．0％之间，相对标准偏差小于10％。

电感耦合等离子体原子发射光谱法测定钒钛高炉渣中钡

冶炼钒钛磁铁矿时加入一种作为示踪剂的碳酸钡以标定出铁过程中铁水所夹带的高炉渣.为准确测定钡的含量,在试验的基础上,建立了用电感耦合等离子体原子发射光谱法（ICP-AES）测定钒钛高炉渣中钡含量的方法.以氢氟酸、盐酸、硝酸混合试剂消解样品,冒高氯酸烟驱赶残余氢氟酸等试剂,盐酸溶解盐类后直接采用ICP-AES测定钡的含量.系统考察了钒钛高炉渣复杂共存体系所导致的基体效应、光谱干扰、背景噪音等干扰因素的影响,优选了灵敏度适宜的钡分析谱线（Ba 230.424 nm、233.527 nm、413.066 nm、455.403 nm、493.409nm）、检测积分与背景校正区域以及ICP光谱仪工作参数.试验结果表明,在分析线扫描窗口内,钒、钛、铁、钙、镁、铝等主要共存基体元素均不产生谱峰,并且与试剂空白信号基线重叠一致,表明钒钛高渣炉中基体组分对测定钡不产生基体效应、光谱干扰等影响,因此实验方法未采用基体匹配校正措施,直接以钡元素标准溶液绘制校准曲线.对于Ba 230.424 nm、233.527 nm、413.066 nm、455.403 nm、493.409 nm分析线,方法的测定下限在0.000 2％～0.001 0％范围,背景等效浓度在0.000 3％～0.000 5％范围,相对标准偏差（RSD）小于2.5％,加标回收率在93％～102％之间.方法适用于质量分数为0.005％～2.50％钡的测定.

电感耦合等离子体原子发射光谱法测定高炉炉料中氧化钾、氧化钠、氧化锌

采用电感耦合等离子体原子发射光谱法(ICP-AES)同时测定高炉炉料中氧化钾、氧化钠和氧化锌的含量。样品采用盐酸、氢氟酸、硝酸、高氯酸溶解,在0.6mol/L的盐酸介质中进行测定。对样品中的共存元素铁、钙、镁等的干扰进行了试验,为适应不同系列炉料的分析,分别建立了含铁和不含铁校准曲线,对铁干扰元素进行了校正。方法测定氧化钾、氧化钠和氧化锌的检出限均小于0.2mg/L,背景等效浓度均小于6.0mg/L。该方法用于同时测定高炉炉料中氧化钾、氧化钠和氧化锌的含量,相对标准偏差值均小于2%,回收率在98%～104%之间。

直流电弧炉电弧速度场和温度场的数值计算

为了揭示直流电弧炉内电弧等离子体的流动及传热规律,为直流电弧炉的设计和最佳工艺操作提供理论依据,采用涡量 流函数法和k ε双方程湍流模型对I=2160A、I=50kA、I=100kA下不同电弧长度的直流电弧等离子体的速度场和温度场进行了数值计算,并与I=2160A条件下实验测定的速度场和温度场进行了比较。结果表明,计算结果与实验测定结果基本吻合。另外,还计算了50kA电弧等离子体的热平衡及不同电流强度、不同电弧长度下电弧对钢水的冲击力。计算结果表明,电弧等离子体主要以对流换热方式将能量传给钢水和四周环境,因此在熔化期应采用大电流长电弧操作;在熔池平稳期,应采用泡沫渣下大电流长电弧操作。