不锈钢等离子切割颗粒物及氧化物排放特性研究。

Department of Occupational and Environmental Health, College of Public Health, University of Oklahoma Health Sciences Center, 801 NE 13th St Room 425, Oklahoma City, OK 73104, USA.

Ann Work Expo Health. 2017 Apr 1;61(3):311-320. doi: 10.1093/annweh/wxw031.

Plasma cutting is a metal fabrication process that employs an electrically conductive plasma arc to cut metals. The metal fume emitted from stainless steel plasma cutting may consist of hexavalent chromium (Cr6+), which is a carcinogen, and other toxicants. Overexposure to plasma cutting fume may cause pulmonary toxicity and other health effects. This study was to evaluate the effects of operation parameters (arc current and arc time) on the fume formation rates, Cr6+ and other oxides concentrations, particle size distributions (PSD), and particle morphology. A fume chamber and high-volume pump were used to collect fume produced from cutting ER308L stainless steel plates with arc currents varying between 20 and 50 A. The amount of fume collected on glass fiber filters was gravimetrically determined and normalized to arc time. Cr6+ and other oxides in the fume were analyzed using ion chromatography. PSD of the fume was examined using a scanning mobility particle sizer and an aerodynamic particle sizer for fine and coarse fractions, respectively. The particle morphology was imaged through a transmission electron microscope (TEM). Total fume generation rate increased with arc current and ranged from 16.5 mg min-1 at 20 A to 119.0 mg min-1 at 50 A. Cr6+ emissions (219.8-480.0 µg min-1) from the plasma cutting were higher than welding fume in a previous study. Nitrogen oxides level can be an indicator of oxidation level and Cr6+ formation (R = 0.93). Both PSD measurement and TEM images confirmed a multimodal size distribution. A high concentration of a fine fraction of particles with geometric mean sizes from 96 to 235 nm was observed. Higher arc current yielded more particles, while lower arc current was not able to penetrate the metal plates. Hence, the worker should optimize the arc current to balance cut performance and fume emission. The findings indicated that arc current was the dominant factor in fume emission from plasma cutting. Appropriate ventilation and respiratory protection should be used to reduce workers' exposure.

等离子切割是一种金属制造工艺，它采用导电等离子电弧来切割金属。从不锈钢等离子切割中排放的金属烟雾可能含有六价铬（Cr6+），这是一种致癌物质，以及其他有毒物质。过度暴露于等离子切割烟雾中可能会导致肺毒性和其他健康影响。本研究旨在评估操作参数（电弧电流和电弧时间）对烟雾形成速率、Cr6+和其他氧化物浓度、粒径分布（PSD）和颗粒形态的影响。使用烟雾室和大容量泵收集在 20 至 50 A 电弧电流下切割 ER308L 不锈钢板产生的烟雾。通过重量法确定收集在玻璃纤维滤纸上的烟雾量，并将其归一化为电弧时间。使用离子色谱法分析烟雾中的 Cr6+和其他氧化物。使用扫描迁移率颗粒计数器和空气动力学颗粒计数器分别对细颗粒和粗颗粒的烟雾 PSD 进行检测。通过透射电子显微镜（TEM）对颗粒形态进行成像。总烟雾生成率随电弧电流的增加而增加，范围从 20 A 时的 16.5 mg min-1 到 50 A 时的 119.0 mg min-1。与之前研究中的焊接烟雾相比，等离子切割产生的 Cr6+排放（219.8-480.0 µg min-1）更高。氮氧化物水平可以作为氧化水平和 Cr6+形成的指标（R = 0.93）。PSD 测量和 TEM 图像都证实了多模态尺寸分布。观察到具有 96 至 235 nm 几何平均粒径的细颗粒高浓度。较高的电弧电流产生更多的颗粒，而较低的电弧电流则无法穿透金属板。因此，工人应优化电弧电流以平衡切割性能和烟雾排放。研究结果表明，电弧电流是等离子切割烟雾排放的主要因素。应使用适当的通风和呼吸保护措施来减少工人的暴露。