MINERÍA la mejor puerta de acceso al sector minero MINERÍA / SEPTIEMBRE 2022 / EDICIÓN 540 30 Después del incremento de tamaño de 30 a 40-45% en la fracción +3/8", la decrepitación disminuyó en casi un 50% como se muestra en la Figura 22, que es bastante menor que los registros que se tenían a valores menores del P80. Este incremento en el P80 se logró abriendo el circuito de zarandeo terciario, y el control del tamaño de partícula se realizó utilizando un sistema de muestreo automático en la faja final que alimenta al pad de lixiviación. Otra conclusión importante es que la decrepitación en el mineral se inicia entre la aglomeración y el apilamiento debido principalmente a la adición de ácido en el aglomerado y el trasporte por fajas. Es menor este efecto en el mineral ya depositado en la pila. La Figura 23 muestra que el efecto principal de decrepitación ocurre en las primeras etapas del ciclo de lixiviación, y las muestras obtenidas a mayores ciclos no se ven afectadas significativamente. Figura 18. Permeabilidad a diferentes contenidos finos y presión de compactación. Figura 19. Efecto del contenido de S Clay en la permeabilidad. Figura 20. Pad 4B, ratio de decrepitación (1/2). Decrepitation Follow-Up During the leaching cycle, due to acid attack, ore decrepitates, i.e., fine content increases at a variable rate, depending on the mineralogy, accessibility, porosity in the ore. It was observed in pad 4B that the decrepitation rate is almost 100% in the fines fraction (-100 and -200 M), which means that, for example, if at the beginning of the Leach Cycle the -200 M is 9%, after completing the first Leach Cycle, the fines content in this screen is in the range of 18 to 20%. Figure 20 shows the decrepitation rate comparing the particle size distribution at zero days and after 240 days of leaching. Several auger samplings on the heap showed that the fines content, -200 M (-74 microns) after the first leaching cycle, almost doubles. The same effect was also verified for the -100M (-150 microns) fraction, and for the coarser screens, 3/8" for example, a decrease between 20-30 % was observed. For Cerro Verde's leaching operations, the KPI for -200M size is 9.5% at the beginning of the leaching cycle. After the size increase from 30 to 40-45% at fraction +3/8", the decrepitation decreased by almost 50% as shown in Figure 22, which is quite lower than the records at lower values of P80. This increase in P80 was achieved by opening the tertiary screening circuit, and particle size control was performed using an automatic sampling system in the final conveyor that feeds the leach pad. Another important conclusion is that decrepitation in the ore starts between the agglomeration and stacking process, mainly due to the addition of acid in the agglomerate and the transport by conveyor belts. This effect is lower in the ore already deposited in the heap. Figure 23 shows that the main decrepitation effect occurs in the early stages of the leaching cycle, and
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