Emulsions continued field test

In some cases, minimal effort is required for the demulsification process. For example, in field tests, adequate separation of a bitumen emulsion could be achieved without the use of demulsifiers by raising the temperature of the emulsion to 190 T and providing 24 to 48 h of residence time in quiescent storage tanks. However, proper selection of demulsification chemicals is essential when treating the emulsions in conventional equipment on a continuous-flow basis. 

In Chapter 23, Nilsen et al. describe the field testing of an emulsion liquid membrane system for copper recovery from mine solutions. The small, pilot plant-scale, continuous circuit for the recovery of copper from mine waste waters and low-grade leach solutions was field tested at a copper mine. Formulation of the emulsion membranes was optimized to provide emulsions with good stability during extraction, but which could be easily broken in an electrical coalescer under mild conditions. Typical results from the tests were >90 percent copper recovery, while maintaining the membrane swelling in the range of 4-8 percent. Cost evaluations indicate the potential for cost-effective recovery of copper from such solutions. 

A simplified flow sheet for the LEM continuous circuit that was used in the field tests is shown in Figure 1. The technique used four main unit operations (emulsion generation, copper extraction, emulsion breaking, and metal recoveiy). 

The treatment of bilge water and emulsions resembles that of the treatment of oil field brines and produced water. Chen et al. [25], using ferric chloride and other chemicals to enhance the performance of Membralox 0.2, 0.5 and 0.8 pm membranes, describe permeate fluxes between 1400 and 34001/m h. Without pretreatment however severe fouling occurred as well as break-through of oil. Zaidi et al. [26] report about the continuation of this work. They quote fluxes between 800 and 12001/m h, but also mention substantial lower fluxes in long term pilot tests using 0.8 pm membranes. In addition they indicate a drop in permeate flux caused by conditions of low pH, the presence of sea water, corrosion inhibitor, oil slugs or flow variations. 

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