LIX63 stability in the presence of Versatic 10 under proposed commercial extract and strip conditions, part III: effect of manganese and cobalt loading on oxime stability at 30 degrees C.

The effect of Mn and Co loading on LIX63 (syn/anti-5,8-diethyl-7-hydroxydodecan-6-oxime) stability was studied in the presence of the carboxylic acid, Versatic 10, when mixed for 12 weeks at 30 degrees C under extract and strip conditions suitable for application at the proposed El Boleo, Mexico copper/cobalt project for direct separation of Co and Zn from Mn, Mg and Ca. Increased Mn loading from 0.2 to 2.5 g/l was obtained on increasing the pH from 4.5 to 6.0, resulting in increased rates of oxime degradation and irreversible loading of Co. The Co could be reductively stripped using Zn metal. Zn loading, Co loading and pH changes between 4.5 and 6.0, excluding the resulting impact on Mn loading, did not appear to have an adverse effect on the oxime stability. The presence of Mn facilitated rapid inter-conversion of the syn oxime isomer into the anti form, which was shown to occur by two different mechanisms, namely a rapid process facilitated by Mn complexing, and a slower, temperature-based isomer re-equilibration process which took place in the absence of Mn. This inter-conversion process resulted in increased Mn and Zn loading occurring relative to fresh organic (Co already being fully loaded) and opened up the possibility of decreasing the amount of LIX63 required in the El Boleo process.
The effect of Mn and Co loading on LIX63 (syn/anti-5,8-diethyl-7-hydroxydodecan-6-oxime) stability was studied in the presence of the carboxylic acid, Versatic 10, when mixed for 12 weeks at 30 degrees C under extract and strip conditions suitable for application at the proposed El Boleo, Mexico copper/cobalt project for direct separation of Co and Zn from Mn, Mg and Ca. Increased Mn loading from 0.2 to 2.5 g/l was obtained on increasing the pH from 4.5 to 6.0, resulting in increased rates of oxime degradation and irreversible loading of Co. The Co could be reductively stripped using Zn metal. Zn loading, Co loading and pH changes between 4.5 and 6.0, excluding the resulting impact on Mn loading, did not appear to have an adverse effect on the oxime stability. The presence of Mn facilitated rapid inter-conversion of the syn oxime isomer into the anti form, which was shown to occur by two different mechanisms, namely a rapid process facilitated by Mn complexing, and a slower, temperature-based isomer re-equilibration process which took place in the absence of Mn. This inter-conversion process resulted in increased Mn and Zn loading occurring relative to fresh organic (Co already being fully loaded) and opened up the possibility of decreasing the amount of LIX63 required in the El Boleo process.