The Improvement Of Drop Volume Device And The Research Of LIX984 Interfacial Properties Change Law In Extraction Process

LIX984, one of hydroxamic extractants, shows excellent extraction performance during the copper extraction process of leaching – extraction – electrowinning and is used widely in copper industry. Researchers have studied on the extraction capacity and rate of LIX984 thoroughly and extensively since the 1970 s. However, there are few relative researches on LIX984 interfacial properties in the extraction process.The modified device of drop volume is used to measure the interfacial tension of LIX984-DT100/water system. The parameters such as Sz interfacial tension isotherms, surface excess isotherms, and interfacial adsorption characteristics parameter Cmin and AI are researched to determine the change law of extractant molecular interfacial activity. A lot of analyses and examination methods, such as SEM, XRD, IR and GC-MS are used to study the influence of solid particles in aqueous phase and degradation products in organic phase on interfacial property, the mechanism of the changes is investigated further.Based on existed drop volume device, the paper designs a casing with manifold and dropper with scales. The results reveal that the new drop volume device is accurate, reliable, reproducible and easy to operate compared with national standard, which can be used for experiments.The influences of extraction experimental conditions including pH values of aqueous phase, phase ratio(O/A), temperature are studied. The results show that LIX984 is a surfactant, and the effects of extraction conditions on the interfacial properties are significant. The interfacial tension of LIX984/DT100-water system increases with pH values increasing and O/A approaching to 1. Initial pH values of aqueous phase have obvious impact on Cmin. The interfacial activity of extractant is strong at higher pH. Temperature has a significant effect on AI. The chaos of system increase at higher temperature and the order degree of extractant molecules at the interface decreases. Based on the interface theory, the extraction is more favorable at high pH, O/A closing to 1 and roomtemperature within a certain range of process parameters.When the aqueous phase contains Fe2+, Al3+, Mg2+(concentration ≤ 2.0g/L) and Ca2+(concentration ≤ 0.5g/L), the interfacial tension LIX984 / DT100-water system reduces significantly and interfacial activity of extractant molecules increases while the extractant molecules order decreases, which is disadvantageous for extaction. Furthermore, the meter-based hydrolysates, complexes and polymers play as the nucleation center of emulsion droplets, and the products will promote emulsion formation and accumulation.The effects of solid particles such as SiO2 and degradation products in organic phase on liquid-liquid interfacial properties are researched. When particles are smaller and higher concentration in aqueous phase within certain ranges, the interfacial tension decreases more obviously, and the time reaching to adsorption equilibrium for extractant molecules is shorter, and the molecules are more random in arrangement. Solid particles can promote O/W type of interfacial emulsions formation which is heavily adverse for extraction. The tension between the long-term recirculating organic phase and aqueous phase is below the tension of fresh organic phase and aqueous phase. The main reason is that the organic phase long-term recirculating after the usage degrades partially. The polar degradation products such as amide, ketone, organic acid, alcohol are surfactants, the products are absorbed on the solid particles to stimulate interfacial emusions formation.