In pyrometallurgical processes refining copper, the main source of loss in the conversion stage is from slag. This paper reports on research work treating converter slag containing high percentages of copper (36 wt%) using ammonium hydroxide at room temperature. Variables analyzed are solution pH, agitation, temperature, NH₄OH concentration and particle size. Results showed that the hydronium ion resulting from ammonium hydroxide dissociation was the main oxidant of copper compounds in slag, such as CuO, Cu₂O and Cu, with the exception of CuFeO₂. The particles contain a large amount of microcracks (porosity) in their refractory structure (analyzed by compositional image capture (BSE)). Thus, the diffusion of the leaching solution through the microcracks making contact with the copper oxides would be allowed. Leaching mechanisms were corroborated by X-ray diffraction and scanning electron microscopy analysis. Increasing temperature and NH₄OH concentration while decreasing particle size obtained higher copper recoveries, reaching values of 84.8%. Under the same conditions, the main impurity (iron) was minimal (<2%). Solution pH also affected slag leaching. Agitation of the solution positively affected the rate of copper extraction. Leaching kinetics of the leaching solution through the porosity formed in the slag was analyzed under the intraparticle diffusion model. The reaction order was 1.2 with respect to the concentration of ammonium hydroxide and the model was inversely proportional to the square of the particle radius. The activation energy obtained was 42.3 kJ/mol for temperature range 283 to 333 K.

中文翻译：

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从转炉渣中浸出铜的氨系统机理

在火法冶炼铜中，转化阶段损失的主要来源是炉渣。本文报道了在室温下使用氢氧化铵处理含高百分比铜（36 wt％）的转炉渣的研究工作。分析的变量是溶液的pH值，搅拌，温度，NH ₄ OH浓度和粒径。结果表明，氢氧化铵离解产生的水合氢离子是矿渣中铜化合物（如CuO，Cu ₂ O和Cu ）的主要氧化剂，但CuFeO ₂除外。。颗粒的耐火结构中含有大量微裂纹（孔隙）（通过成分图像捕获（BSE）分析）。因此，将允许浸出溶液扩散通过与铜氧化物接触的微裂纹。X射线衍射和扫描电子显微镜分析证实了其浸出机理。温度升高和NH ₄OH浓度降低时，获得的铜回收率更高，达到84.8％。在相同条件下，主要杂质（铁）极少（<2％）。溶液的pH值也影响炉渣的浸出。溶液的搅拌对铜的萃取速度有积极的影响。在颗粒内扩散模型下，分析了通过渣中孔隙形成的浸出液的浸出动力学。相对于氢氧化铵浓度，反应阶数为1.2，并且模型与颗粒半径的平方成反比。在283至333 K的温度范围内，获得的活化能为42.3 kJ / mol。