Heap leaching is a well-established extractive metallurgical technology enabling the economical processing of various kinds of low-grade ores, which could not otherwise be exploited. However, despite much progress since it was first applied in recent times, the process remains limited by low recoveries and long extraction times. It is becoming increasingly clear that the choice of heap leaching as a suitable technology to process a particular mineral resource, which is both environmentally sound and economically viable, very much depends on having a comprehensive understanding of the underlying fundamental mechanisms of the processes and how they interact with the particular mineralogy of the ore body under consideration. This paper provides an introduction to the theoretical background of various heap leach processes, offers a scientific and patent literature overview on technology developments in commercial heap leaching operations around the world, identifies factors that drive the selection of...

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Heap Leaching Technology—Current State, Innovations, and Future Directions: A Review

Membrane technology was in its infancy about about 50 years, In 2010, Howeever the global market crossed 12.5 billion US dollar for only desalination. In future the membrane technology is focusing the water scarcity , energy crisis and food security. Over one billion people, many in developing countries, currently lack access to drinking water and food security is threatneneing sue to expected world population increases by 40% to 50%. Therefore, enegineers and membranologists are seeking new ways for the efficient and sustainable production of water and food using less energy. The sustainable alternative is to use membrane contactors ia to explore the untouched sources. Hollow fibre membrane contactors have made tremendous development during the past few years as an emerging technology for value industry. The effluent from the manufacturing processes in food, agriculture and pharmaceutical industries contain the value added products which one side, threatens thee aquatic media by producing the odour and toxixity on the other side, these compounds can be used as a flavorants, if recovered. Value added products are becoming backbone to boost the economy due to their vast application among the society. In Pakistan where food is found in rich quality, value added products need more attention to elaborate them as a key role in country economy. Food industry to grow efficiently, the extraction process components of these compunds should be compact, economical and fast in consent of quality and hygiene. Although membrane contactors have been studided for a variety of application, however limited work is available on the process intensification and integration for a particular application. Moreover, the theoretical study is inevitable to design a boost, compact and efficient membrane contactor for the scale up food industry.

HOLLOW FIBER MEMBRANE CONTACTORS: AN EMERGING TECHNOLOGY FOR VALUE ADDED INDUSTRY-Invited Talk

Gold leaching in cyanide-starved copper solutions in the presence of glycine

Separation of butanol from ABE mixtures by sweep gas pervaporation using a supported gelled ionic liquid membrane: Analysis of transport phenomena and selectivity

A 2D mathematical model was developed to study liquid extraction by membrane contactors. The extraction system included a hollow-fiber membrane extractor, an aqueous solution of ethanol and acetone...

Near-Critical Extraction of the Fermentation Products by Membrane Contactors: A Mass Transfer Simulation

Metal sulfide precipitation coupled with membrane filtration process for recovering copper from acid mine drainage

A novel process based on gas filled membrane absorption to recover cyanide in gold mining

Designing the SART process – A review

Modeling and simulation of mass transfer in near-critical extraction using a hollow fiber membrane contactor

In recent years, lithium production has been increasing as a result of the growing market demand. Salt-lake brines are one of the main sources of raw lithium, which can be concentrated and purified by natural evaporation. This time-consuming production causes a loss of around 85–95 % of the water contained in the extracted brine. In this context, new technologies could replace the current process with the aim to improve the water management by recognizing the evaporated water as a critical resource. This study proposes a novel fractionation method, based on a membrane distillation-crystallization process, for concentrating and purifying the lithium brine while recovering fresh water. Synthetic brines containing the major components present in Li-rich brines were assessed at different temperatures, reaching a water flux higher than 3.0 kg/m2h at 50 °C. The process was continuously protracted achieving the fractionation of Na and K salts by controlling the supersaturation of the brine and crystallization. Subsequently, the observed water flux for Mg brine was 0.22 kg/m2h as a result of the water activity decline at high brine concentration (>7.0 mol/kgH2O). Moreover, thermodynamic speciation simulation supported the potentialities of this process, showing the capacity to recover around 95 % of the water contained in real brines from salt-lakes after three stages of separation. Overall, a conceptual flow-sheet of a new membrane-based fractional crystallization method was proposed for: i) the intensification of the brine concentration; ii) the recovery of water (up to 95 %); iii) the brine purification from in presence of major ions (i.e. Li, Na, K and Mg).

Humberto Estay

Papers

Metal sulfide precipitation coupled with membrane filtration process for recovering copper from acid mine drainage

A novel process based on gas filled membrane absorption to recover cyanide in gold mining

Designing the SART process – A review

Modeling and simulation of mass transfer in near-critical extraction using a hollow fiber membrane contactor

Recovering water from lithium-rich brines by a fractionation process based on membrane distillation-crystallization