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题名	银在H_2O_2—NH_4~+体系中氧化浸取动力学的研究
作者	谭爱国
学位类别	硕士
答辩日期	1987-06-30
授予单位	中国科学院研究生院
授予地点	北京
导师	柯爱骏
学位专业	化学工艺
中文摘要	探讨了用H_2O_2—(NH_4)_2SO_4浸取体系从废镀银层物料中回收银的新工艺。实验结果表明，能够在室温常压下进行选择性浸出，可消除传统的硝酸浸取体系的环境污染问题，具有较好的应用前景。采用此浸取体系时，初始(NH_4)_2SO_4浓度一般应选择适当（0.30M），初始H_2O_2浓度随所处理物料种类不同而改变。例如，处理成份比较单一的废次保温瓶的镀银玻璃片时，可选择低的H_2O_2浓度（0.012wt%）用浸泡方法进行浸出，浸取液用水合肼还原可直接得出高纯海绵银。如处理成人发比较复杂的废次镀银电子元件时，一般基体材料为铜合金，可选择较高的H_2O_2浓度（6wt%左右）进行快速浸出，使银优先浸出，而铜基体则基本上不被浸出，达到选择性浸取。用旋转圆盘法研究了Ag在H_2O_2—(NH_4)_2SO_4体系中浸取的动力学，考察了一些因素对Ag溶解速率的影响。实验结果表明，该反应的速率常...
英文摘要	A new method of recovering of metalic silver from the scrap silver materials has been developed in this paper. A H_2O_2-(NH_4)_2SO_4 aqueous solution was used as a leachant for the leaching of silver. The experimental results showed that silver can be leached selectively by this new method under atmospheric pressure and in ambient temperature. The environmental pollution resulting from the traditional process of leaching of silver by using HNO_3 as leachant was avoided. This method was of a promising prospect method for industry application. In this leach process, an appropriate initial concentration of (NH_4)_2SO_4 was required and the initial concentration of H_2O_2 can vary with the kinds of materials to be leached. For example, as leaching of silver-learing glass of waste thermos in which silver was of metallic form, a low concentration of H_2O_2(0.012 wt%) was available in the immerged leaching of thin silver layer and the leach solution of silver was reduced by N_2H_4·H_2O and a kind of pure sponge silver was obtained resultingly. As for the processing of silver-bearing electronic components in which there is a thin plating layer of silver on the surface and the basement was made of alloy of copper, a higher initial concentration of H_2O_2 (6 wt%) was required for leach silver fast enough. In this way, silver on the surface was leached preferentially and copper in the basement was not leached, therefore a selective leach silver was achieved. The kinetics of leaching of silver in H_2O_2-(NH_4)_2SO_4 system was investigated by using of a rotating disc method. The effect of some parameters on the dissolution rate on silver was studied. The experimental result showed that the constant of rate was proportional to the square root of the disc rotation speed and a first order dependence of dissolution rate on the initial concentration of H_2O_2 was observed. The effect of concentration of (NH_4)_2SO_4 maximized at 0.30 mol·1~(-1). An apparent activation energy of dissolution of silver was 5.5 kcal·mol~(-1) (23.1 kJ·mol~(-1) within the experimental temperature region of 12.3 to 42.8 ℃. It has been shown from the experimental results that this leaching reaction was controlled by the mass transfer in the aqueous solution. The reaction process of silver in H_2O_2-(NH_4)_2SO_4 aqueous solution was more complicated. It included the following reactions: H_2O_2 was decomposed by catalyzing of silver, silver itself was oxidized and dissolved into the solution and ammonium ionized in the solution. According to the experimental results and the theoretical analysis, silver dissolved into the solution in the form of Ag~+, Ag(NH_3)~+. Ag(NH_3)_2~+ under the experimental conditions. A reaction mechanism of the dissolution of silver in H_2O_2-(NH_4)_2SO_4 system was proposed as follows: H_2O_2 → (O) + H_2O (1) (O) + (O) → O_2 (2) NH_4~+ → NH_3 + H~+ (3) 2Ag + (O) + H_2O → 2Ag~+ + 2OH~- (4) Ag~+ + NH_3 → Ag(NH_3)~- (5) Ag~+ + 2NH_3 → Ag(NH_3)_2~+ (6)
语种	中文
公开日期	2013-09-28
页码	56
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/2159]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	谭爱国. 银在H_2O_2—NH_4~+体系中氧化浸取动力学的研究[D]. 北京. 中国科学院研究生院. 1987.

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