| In order to optimize the performance of copper bioleaching- solvent Extraction-electrowinning process (BL-SX-EW) at DeXing Copper Mine in Jiangxi Province, the bacteriostasis of organic phase entrained in the aqueous raffinate and the aspects of interfacial emulsions (also called interfacial crud) in copper-SX circuit, such as causes and mechanisms of stable emulsion formation and methods used to prevent emulsification are studied systematically.The entrainment of organic phase in the aqueous raffinate of copper-SX results in pollution in bioleaching system through circle performance. The activity and leaching ability of bacteria is deteriorated seriously because there are more kinds of bactericides and surfactants in organic phases, such as phenol and naphthalene. As a result, growing period of bacteria is delayed by 4 days and leaching copper concentration in 24 days decreased by 20%. The concentration of bacteria declines constantly as a result of collection by interfacial emulsion. Some effective ways to enhance bioleaching efficiency are suggested.A lot of analyze and examination results, such as GOMS, XRD, SEM and AAS reveal that impurities and surfactants in organic phase and solid particles in copper-SX system can be mostly related to 0/W type of interfacial emulsions formation. Many kinds of amphiphiles containing such hydrophilic group as carbonyl, carboxyl, hydroxyl or acylamine produced in the reagent degradations and dense-aromatic impurities originated from diluent are accumulated in organic phase, being as one kind of emulsifying agent stabilizing droplets. The effective compositions of Lix84 and nonylphenol are degraded almost completely after long term circulation by Beckmann rearrange, hydrolyzing, oxidizing and sulfonating reactions, so they are less stable then the effective compositions of Lix860N. Another kind of emulsifying agent is the solid particles that consist of mineral particles suspended in the aqueous feed (for example silicate or quartzparticles), Fe(OH)3 and Si02 colloids in the aqueous feed and sulfate precipitated in the extraction operation.The effects of Lix984N, diluent, circulating organic phase, solid particles on disengagement properties and interfacial emulsion performance are studied respectively. With increase of Lix984N concentration, the viscosity of organic phase increases and interfacial tension and density difference between two immiscible liquids decreases. The relationship between adhesion force of two equal droplets separated by a distance h() and physical properties of system can be described as, which is deduced from Shinner theory. Thisequation infers that the changes of physical properties of organic phase with Lix984N concentration make the disengagement of two phases slower and the resistance to droplets coalescence stronger. The HLB value of Lix984N calculated by Davies' incremental approach is 1.29 in favor of the stability of W/0 type emulsion. Lix984N play a cooperating role during 0/W type interfacial emulsion formation in copper-SX. Interfacial emulsion tends to transform type from 0/W to W/0 when the volume factor of Lix984N is at about 5% under our experimental conditions.Among two kinds of: the emulsifying agents, solid particles in the system are believed to be the predominating one for emulsion formation and stability. Experimental results show that the higher of solid particle content in aqueous feed the more interfacial emulsion come into being with smaller diameter and narrower distribution of droplets, as a result interfacial emulsion becomes more stable. In addition to forming compact solid skins stabilizing emulsion droplets, the particle floccules will fill spaces between droplets so that droplets are separated and protected against moving and coalescence.According to experimental results we believe the interfacial emulsion stability depends on three primary factors: one is the repulsion effect of electrostatic and hydration forces, the second-is the mechanical barrier of three-dimensional network structure in...
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