Experimental Study on Bubble Size Measurement for Development of Seafloor Massive Sulfides
Experimental Study on Bubble Size Measurement for Development of Seafloor Massive Sulfides
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海底块状硫化物开发气泡尺寸测量实验研究
DOI：
10.1115/omae2019-95186
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
M.
中科院分区：
文献类型：
--
作者：
Imai;S.;Nakajima;Y.;Murai;M.
海底块状硫化物被认为是未来的矿产资源。为促进海底块状硫化物的开发，提出了一种利用浮选从深海海底矿石中提取有价值矿物的方法，以降低从海底到海面的矿石提升成本。为了将浮选应用于海底矿物处理，需要适用于深海条件的气泡尺寸的测量方法，因为需要在深海海底的压力条件下产生适合于浮选的细小气泡。在此基础上，作者对图像分析法测量气泡尺寸进行了研究，以期在深海条件下得到应用。在本研究的第一阶段，区分了适合气泡图像分析的摄影条件。在矩形截面鼓泡塔中，采用多孔喷嘴在一定的空气流量下产生气泡。采用高速摄像机和低帧频摄像机对气泡进行摄像。通过对气泡的视频图像进行二值化来测量气泡尺寸。在最佳摄影条件下，气泡尺寸不仅从高速摄像机，而且从视频摄像机获得;并且两个尺寸数据相对较好地一致，这意味着通过使用图像分析测量气泡尺寸将适用于深海条件。在第二阶段，在高达2.4 MPa的高压条件下进行实验。利用数字显微镜观察了在带有观察窗的小型压力室中使用毛细管喷嘴产生的单个气泡。通过在第一阶段建立的程序，通过图像分析进行气泡尺寸测量。高压下气泡的生成过程与常压下相似，但气泡尺寸随压力的升高而减小。结果表明，压力和气泡尺寸之间存在很强的相关性。
Seafloor Massive Sulfides have been expected to be future mineral resources. To promote the development of Seafloor Massive Sulfides, Seafloor Mineral Processing, a method of extracting valuable minerals from the ores on deep seafloor using flotation to reduce the lifting cost of ores from the seafloor to the sea surface, was proposed. To apply flotation for the seafloor mineral processing, a measurement method of bubble size applicable to deep-sea conditions has been desired because it is necessary to generate fine air bubbles suitable to flotation under pressure conditions on deep seafloor. Then, the authors have studied on bubble size measurement by image analysis, which is expected to be applicable to deep-sea conditions. At the first phase of this study, photographic conditions suitable to image analysis of air bubbles were distinguished. Air bubbles were generated by using a porous nozzle at some air flow rates in a bubble column with a rectangular cross-section. Video images of air bubbles were taken by using both high-speed camera and video camera with a low frame rate. Bubble size was measured by binarizing the video images of bubbles. Under optimal photographic conditions, bubble size was obtained from not only the high-speed camera but also the video camera; and both size data agreed relatively well, which implies that bubble size measurement by using image analysis would be applicable to deep-sea conditions. At the second phase, experiments were carried out under high-pressure conditions up to 2.4 MPa. Single bubble generation by using a capillary nozzle in a small pressure chamber with a sight glass was observed by using a digital microscope. Bubble size measurement by image analysis was carried out by the procedure established at the first phase. While the process of bubble generation at the high pressures was similar to that at the atmospheric pressure, the bubble size was decreased as the pressure rose. The result implies there is a strong correlation between the pressure and the bubble size.