REVISTA MINERÍA 540 | EDICIÓN SEPTIEMBRE 2022

MINERÍA la mejor puerta de acceso al sector minero MINERÍA / SEPTIEMBRE 2022 / EDICIÓN 540 52 A principios de los años 80, la empresa finlandesa Outokumpu introdujo las celdas de flotación flash denominadas SkimAir. Se realizaron pruebas en la planta concentradora de Hammaslathi. La idea fue colocar una celda de flotación mecánica en el circuito molienda-clasificación, su alimentación era la descarga gruesa del clasificador, la cual podría tener partículas libres que podían ser flotadas y evitar su remolienda innecesaria[22]. El relave de la celda OK se remuele, y el resultado obtenido era un concentrado final. Su aplicación permitió mejorar la recuperación del mineral valioso, perfeccionar la cinética de flotación, reducir el volumen de equipo en el circuito, evitar pérdidas por generación de lamas y facilitar la filtración del concentrado para reducir el contenido de humedad. La Figura 15 muestra un arreglo típico de una celda flash en un circuito de molienda. La principal diferencia de diseño entre la celda de flotación flash SkimAir y las convencionales es la descarga cónica. La descarga inferior y el punto de ingreso de la pulpa están diseñadas para manejar una alimentación gruesa como la descarga inferior de un hidrociclón. Este material grueso entra en corto circuito en la descarga inferior, con lo cual se evita que el material interfiera con la flotación, donde podría conducir a una mayor densidad de pulpa en la celda y evitar que las partículas suben a la superficie. La parte superior tiene una densidad de pulpa más baja de 40–50% de sólidos en comparación con la descarga inferior con una densidad de 60–70 % de sólidos, y alThe unit cell has demonstrated that it can operate at high pulp densities and is specially designed to operate under this condition, so it is practical to use the unit cell in almost any grinding circuit and in almost all cases, it is necessary to supply water to the discharge of the unit cell to obtain the desired dilution at the classifier overflow. This means that the unit cell can be installed in the grinding circuit without altering the mill control or drastically changing the grinding area layout. Figure 12 shows a more detailed arrangement of the unit flotation cell in the grinding-classification circuit. One of the variations adopted by operations was to install two mechanical cells in the primary grinding mill discharge to effect rapid flotation at coarse size based on unit cell operation. The Lake Dufault copper-zinc operation used this design some time ago and the rod mill discharge at 37% minus 200 mesh size was diluted to 57.5% to feed two 100 cubic foot Denver mechanical cells [20]. In this circuit, about 30% of the copper was recovered with a grade of 24%. The flotation time was 6 minutes. The concentrate obtained by the unit flotation cell is a final concentrate that can be sent to the thickening and filtration circuit. The tailings from the unit flotation cell can be sent to the classifier, either a spiral or a hydrocyclone. It is important to indicate that laboratory evaluations are important to estimate recoveries and behavior of a mechanical cell to evaluate the kinetics of coarse flotation. This idea is of considerable importance if processing a polymetallic ore such as lead-zinc, since, if lead flotation is done to coarse size, the zinc circuit should be processed to coarse size as well. For example, a feed with a K80 of 390 µm was evaluated in the laboratory, and the results indicated that a size range of -300+150 µm could recover zinc by about 90% [21], but it was necessary to add an adequate amount of collector since coarse particles require a higher dosage of collector than fine particles. See Figure 14. In the early 1980’s, the Finnish Company Outokumpu introduced the Flash Flotation Cell called SkimAir. Tests were performed at Hammaslathi concentrator. The idea was to place a mechanical flotation cell in the grindingclassification circuit, its feed was the coarse discharge of the classifier, which could have free particles that could be floated and avoid unnecessary regrinding [22]. The tailings from the OK cell were reground, and the concentrate obtained was a final concentrate. Its application allowed to improve the recovery of the valuable minerals, improve the flotation kinetics, reduce the volume of equipment in the flotation circuit, avoid losses due to the generation of slimes, and facilitate the filtration of the concentrate to reduce the moisture content. Figure 15 shows a typical arrangement of a flash cell in a grinding circuit. Figura 15. Diagrama de flujo típico de una celda flash[23].

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