In the caprolactam production process,ammonium sulfate grains inevitably entrain a small amount of amide oil,when the grains settle and separate in the gas-liquid-liquid-solid crystallization reactor.Amide oil entrainment causes waste of caprolactam and pollution of ammonium sulfate.By adding surfactants and changing experimental conditions,the entrainment of amide oil was reduced.The influence of surfactant,pH,temperature,and grain size on adsorption behavior of amide oil on the surface of ammonium sulfate crystal was evaluated from the adsorption equilibrium under shaking.The results show that cationic surfactant cetylpyridinium bromide(CPB),dodecyltrimethylammonium bromide(DTAB),non-ionic surfactant Tween 80,and the mixture of non-ionic surfactant Triton X-100 and DTAB reduce the caprolactam adsorption on the surface of ammonium sulfate crystals,while anionic surfactant sodium lauryl sulfate(SDS)and sodium dodecyl benzene sulfonate(SDBS)increase the caprolactam adsorption.In the range of 2—7,pH does not significantly affect the adsorption behavior.Between 50—80℃,amide oil adsorption on the surface of ammonium sulfate increases with temperature.With increasing ammonium sulfate particle size,the adsorption of amide oil decreases.
含砷难处理金矿的细菌氧化预处理法具有投资成本较低、反应易控制及适合中小型金矿等优点,但此法空气利用率较低,造成通气量很大,通气动力成本过高。本研究提出了新型的导流式搅拌槽,通过改善通气和搅拌方式,降低通气成本和动力消耗,提高浸出效率。以含砷难处理金精矿为研究对象,采用嗜酸性氧化亚铁硫杆菌(At.f)对其进行生物预氧化搅拌浸出实验。实验对比研究了采用普通搅拌槽和导流式搅拌槽对含砷金精矿生物浸出过程中矿浆p H值、氧化还原电位(Eh)、总铁和总砷浸出率的差异,并对导流式搅拌槽中浸渣进行XRD和SEM分析。结果发现,反应第二天开始导流式搅拌槽中Eh值迅速升高,且最大值为497 m V,脱砷率达到34.86%,浸渣硫脲法提金率为58%。
