Abstract
Cyanide is one of the main reagents used in gold mining that can be recovered to reduce operational costs. Gas membrane technology is an attractive method for intensifying both the stripping and absorption processes of valuable compounds, such as cyanide. However, scaling-up this technology from laboratory to industry is an unsolved challenge because it requires the improvement of the experimental methodologies that replicate lab-scale results at a larger scale. With this purpose in mind, this study compares the performance of three different hollow fiber membrane contactor modules (1.7 × 5.5 Mini Module, 1.7 × 10 Mini Module, and 2.5 × 8 Extra Flow). These are used for recovering cyanide from aqueous solutions at laboratory scale, using identical operational conditions. For each experimental set-up, mass-transfer correlations at the ranges of feed flows assayed were determined. The modules with the smallest and largest area of mass transfer reached similar cyanide recoveries (>95% at 60 min), which demonstrate the impact of module configuration on their operating performance. The results obtained here are limited for scaling-up the membrane module performance only because operating modules with the largest area results in a low Re number. This fact limits the extrapolation of results from the mass-transfer correlation.
Highlights
The gas membrane process or gas-filled membrane absorption (GFMA) process has been widely studied for recovering or removing volatile elements contained in different sources
The only exception was cyanide recovery at the lowest feed flow operated in the 2.5 × 8 Extra Flow module, which had a value of 93%
We can assert that the 1.7 × 5.5 Mini Module and 2.5 × 8 Extra Flow modules are very attractive alternatives, since in both systems cyanide recoveries higher than 90% can be achieved at 30 min of operation for all feed flows tested
Summary
The gas membrane process or gas-filled membrane absorption (GFMA) process has been widely studied for recovering or removing volatile elements contained in different sources. The GFMA process has been used to recover ammonia [1], CO2 [2,3], H2 S [4], HCN [5] or to separate CH4 and CO2 [6] The interest in this process resides in the high specific area (contact area per equipment volume) provided by membrane contactor modules [7], and the possibility to conduct the stripping and absorption steps in the same equipment in comparison with traditional equipment (packed beds, spray columns, bubble columns, venturi scrubbers, etc.). The GFMA process has an additional advantage with respect to the AVR technology, related to safety management
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