It is a well-known fact that the value of the Bond work index (wi) for a given ore varies along with the grinding size. In this study, a variability bysis is carried out with the Bond standard grindability tests on different critical metal ores (W, Ta), ranging from coarse grinding (rod mills) to fine grinding (ball mills). The relationship between wiand grinding size did not show a clear correlation, while the grindability index (gpr) and the grinding size showed a robust correlation, fitting in all cases to a quadratic curve with a very high regression coefficient. This result suggests that, when performing correlation studies among ore grindability and rock mechanics parameters, it is advised to use the grindability index instead of the Bond work index.
There is no doubt about the practical interest of Fred Bond’s methodology in the field of comminution, not only in tumbling mills design and operation but also in mineral raw materials grindability characterization. Increasing energy efficiency in comminution operations globally is considered a significant challenge involving several Sustainable Development Goals (SDGs). In particular, the Bond work index (wi) is considered a critical parameter at an industrial scale, provided that power consumption in comminution operations accounts for up to 40% of operational costs. Despite this, the variability of wi when performing the ball mill Bond’s standard test is not always understood enough. This study shows the results of a variability analysis (a 33 factorial design) performed to elucidate the influence on wi of several parameters obtained from the particle size distribution (PSD) in feed and product. Results showed a clear variability in the work and grindability indexes with some of the variables considered.
Over the years, alternative procedures to the Bond grindability test have been proposed aiming to avoid the need for the standard mill or to reduce and simplify the grinding procedure. Some of them use the standard mill, while others are based on a non-standard mill or computation techniques. Therefore, papers targeting to propose a better alternative claim to improve validity, to reduce test duration, or to propose simpler and faster alternative methods for determining the Bond work index (wi). In this review paper, a compilation and critical analysis of selected proposals is performed, concluding that some of the short procedures could be useful for control purposes, while the simulation-based procedures could be interesting within a process digitalisation strategy.
Introducción: La segmentectomía lateral izquierda es el procedimiento más empleado para la cirugía del donante en trasplante hepático con donante vivo adulto-pediátrico (THDVA-P), y ha demostrado ser seguro y reproducible. Sin embargo, la información aún es escasa respecto al abordaje laparoscópico. El objetivo de este artículo es dar a conocer los resultados postoperatorios de la segmentectomía lateral izquierda laparoscópica (SLI-L) para THDVA-P. Materiales y método: Realizamos un estudio retrospectivo, observacional, de un solo centro, Hospital del Salvador; con vasta experiencia en trasplante hepático y en resecciones hepáticas laparoscópicas. Se ofreció realizar el procedimiento de SLI-L para la cirugía del donante vivo. Se describe la técnica quirúrgica y los resultados postoperatorios de los donantes. Resultados: Entre abril 2015 y enero 2021, 36 pacientes, 25 de ellos hombres, fueron sometidos a SLI-L. El 86% eran madre o padre del receptor, con una mediana de 30 años (19-45). Mediana de tiempo operatorio de 360 min (240-480). Hubo conversión en un caso debido a sangrado venoso de difícil manejo y en dos oportunidades se utilizó técnica mano asistida por la misma causa. Morbilidad Clavien-Dindo III en un paciente debido a fuga biliar precoz, manejada con colangiopancreatografía retrógrada endoscópica exitosamente. La mediana de hospitalización fue de 4 días (3-12) y no hubo mortalidad. Conclusión: La SLI-L ha evolucionado, desde un procedimiento innovador hasta convertirse en el actual procedimiento estándar para THDVA-P. Los buenos resultados en términos de morbimortalidad sugieren que podría ser una técnica segura y reproducible en contextos similares al del centro.
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