著者

宮本 真之 北田 敦 安達 謙 深見 一弘 邑瀬 邦明

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.137, no.11, pp.103-109, 2021-11-30 (Released:2021-11-30)

参考文献数

25

被引用文献数

2

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CaCl2 is a low-toxic, inexpensive reagent that dissolves in large amounts in water to form highly concentrated aqueous solutions, or hydrate melts electrolyte. In this work, it was investigated that the concentrated CaCl2 aqueous solutions (aq) as novel lead (Pb) electrodeposition baths. While PbCl2 is poorly soluble in water at room temperature, PbCl2 dissolved up to 0.452 mol kg−1 ([Pb(II)] = 93.7 g kg−1) by the formation of PbCl42− complexes in the concentrated CaCl2 aq due to its high Cl− activity. Electrochemical measurements confirmed that the apparent exchange current density and the limiting current density of Pb electrodeposition decreased with increasing CaCl2 concentration. Since the diffusion of Pb(II) species was limited due to the high viscosity and ionic strength of the solution, agitation was effective in improving ion transport and electrodeposition rate. The presence of chloride ions in Pb electrolysis is usually detrimental due to the low solubility of PbCl2, however, the highly concentrated CaCl2 solution can be a potential candidate electrolyte for PbCl2-based electrolytic processes.

著者

糟野 貴史 北田 敦 下川 公博 邑瀬 邦明

出版者

一般社団法人 資源・素材学会

雑誌

日本鑛業會誌 (ISSN:18816118)

巻号頁・発行日

vol.130, no.2, pp.65-69, 2014

被引用文献数

6

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Electrolytic copper contains, on average, 10 ppm silver as impurity, which leads to a loss of silver as a cashcow product for copper smelters.Most of silver included in blister copper anodes passes into anode slime when electrolyzed, keeping the elemental state. However, once a part of elemental silver dissolves from the anode or from anode slime for some reason, then silver can co-deposit with electrolytic copper cathode, since silver is nobler than copper. In the present work, the dissolution behavior of silver from anode slime was examined by using granular silver as a model of the slime.We have shown that the silver dissolution is caused by dissolved oxygen in the electrolyte, and that thiourea and/or chloride ions as usual additives play a role to suppress the silver dissolution approximately to two thirds.Moreover, it was found that the dissolution of silver was suppressed to less than 1ppm by galvanic contacting of the granular silver with less noble metals (Pb or Cu) immersed in the same electrolyte. This indicates that the use of Pb or Cu lining at the bottom of electrolytic cells can suppress silver dissolution from the anode slime settled to the bottom, reducing the silver loss to electrolytic copper.

著者

安達 謙 仲井 雄哉 三野 翔平 宮本 真之 北田 敦 深見 一弘 邑瀬 邦明

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.136, no.2, pp.8-13, 2020-02-29 (Released:2020-02-28)

参考文献数

19

被引用文献数

3

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The mechanism of nodulation in copper electrorefining process was investigated by experimental method and simulation, in particular as for its growth in height. Due to the high current density at the tip, the nodule height increased as an exponential function of the time for electrolysis. Therefore, the growth behavior of nodules was strongly affected by the size of the nucleus and the existence of the threshold size to lead an electrical short circuit was suggested. Since some nodules obtained in the industrial process included mold releasing agent carried from anode-casting process, mold releasing agents are considered to be one of the main causes of the large nodule and need to be removed for the improvement in the current efficiency.