MINERÍA la mejor puerta de acceso al sector minero MINERÍA / SEPTIEMBRE 2023 / EDICIÓN 552 46 de 2 kilogramos y se almacenó bajo refrigeración hasta que se requirió para el programa de pruebas. Se tomó una porción representativa para análisis de cabeza y estudio mineralógico. La muestra es esencialmente un mineral de cobre de alta ley, con un contenido de 2.07% Cu, 0.008% Pb, 0.006% Zn, 10.3% Fe, 0.006% Mo, 20 g/t Ag y 0.34 g/t Au. El cobre soluble en ácido en la muestra fue 0.23%, lo que indica que los niveles de óxidos de cobre probablemente serían una restricción para obtener una recuperación alta. Esta es una muestra de bajo óxido, 11% respecto del cobre total[17], pero puede afectar la recuperación de cobre. Los minerales cupríferos detectados incluyeron los sulfuros de cobre bornita, chalcocita y chalcopirita. No se detectó cobre nativo en la muestra analizada; sin embargo, este suele tener una ocurrencia en forma de hojuelas. El mineral de silicato de cobre detectado fue crisocola (solo un pequeño contenido). Se esperaba Figura 8. Efecto del tamaño de partícula y liberación en la flotación de chalcopirita[14]. Figure 8. Effect of Particle Size and Liberation on Chalcopyrite Flotation[14]. not well performed, some losses of valuable mineral and dilution of the concentrate grade will have an impact on the recovery process. Coarse particles of economic minerals and gangue can be reported in the rougher concentrate and may increase the recovery, but reduce the rougher concentrate grade. Try to reject these particles is an alternative, but the recovery is affected, although the overall concentrate grade could remain almost stable[12]. Figure 9 illustrates the causes of low recovery and concentrate grade. By determining the appropriate grind and possible size of liberation, we can know if there might be any mechanical entrainment issues of gangue minerals in the froth. There are several factors that influence mechanical entrainment, one of them being particle size. This is usually evaluated using a recovery curve at different sizes, and comparing the results with the average particle size evaluated. In the analysis, the particles reported by mechanical entrainment show a greater displacement when the particle size is reduced[15]. The flotation at a coarse size can partially reduce the presence of gangue in the concentrate, but particles with very little liberation can also be reported in the froth, which can complicate the design and/or operation of the regrind and cleaning circuit. The presence of large particles is an indication that high-grade concentrates can be produced if the valuable particles have a appropriate degree of liberation and it is possible to produce a good concentrate with high separation efficiency if the degree of liberation of the particles is closed to 80% or more[16]. Other point to consider is the slurry density because the K80 values of the concentrates obtained from the flotation test with a slurry density of 30% w/w are greater than the K80 values of the concentrates obtained from the flotation test with a slurry density of 25% w/w. In both flotation tests, as time passes, the K80 value decreases[16]. Figure 10 shows a downward trend in the particle size of chalcopyrite from the first concentrate to the final concentrate. Figure 11 displays the rougher concentrate collected after 20 seconds. Experimental Work A copper ore sample was used to perform the metallurgical testing program. The composite was crushed to -10 mesh and thoroughly homogenized. The composite was split into 2-kilogram subsamples and stored in a freezer until required for testing program. A representative portion was taken for head assay analysis and mineralogical study.
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