Scale-up in froth flotation: A state-of-the-art review

Abstract

Froth flotation has been one of the most important and widely used methods to concentrate minerals since its introduction over a hundred years ago. Over the last few decades, in order to process more mineral while reducing capital costs, flotation equipment has become exponentially larger. The increase in tank volume, however, has brought new challenges in the operation and design of industrial flotation tanks. This review analyses the literature on flotation tank scale-up for the first time, contrasting several techniques and approaches used in both historical and state-ofthe-art research. The study of flotation scale-up is crucial for the optimisation of industrial plant performance and the maximisation of laboratory-scale research impact. While important advances in our understanding of flotation have been achieved, large flotation tank design and scale-up has, to a large extent, remained in-house know-how of manufacturing companies. This review of the literature relevant to flotation tank scale-up has resulted in a new classification, dividing the scale-up literature into two main areas of study, namely "Kinetic scale-up" and "Machine design scale-up".This review indicates that current scale-up rules governing the design of flotation tanks focus mainly on pulp zone kinetic parameters and neglect the effects on the froth zone, despite the importance of froth stability and mobility in determining flotation performance. Froth stability and mobility are closely linked to the distance the froth needs to travel, which increases with tank diameter. Although including internal elements, such as launders and crowders, has been the industrial solution for enhancing froth transport and recovery in larger tanks, the design and scale-up of these elements have not been thoroughly studied. Gaps in our knowledge of flotation are discussed in the context of addressing the scale-up problem, considering froth transport and froth stability. Addressing these gaps will pave the way for the design and operation of large flotation tanks of enhanced performance.

Effect of Particle Size on the Rising Behavior of Particle-Laden Bubbles

“…Froth flotation is also one of the most widely used methods in mineral processing 5,6 , and relies on the collection of hydrophobic particles by bubbles. More specifically, bubbles rise through a slurry of water and a mix of valuable and non-valuable mineral particles, known as the pulp phase; target mineral particles are selectively captured by bubbles, forming bubble-particle aggregates that reach the top of the pulp phase and form a mineral-rich froth which then overflows the flotation tank.…”

Bubble Size Distribution Characteristics of a Jet-Stirring Coupling Flotation Device

“…Flotation devices are considered to be effective for fine coal slime separation processes [1,2], and the research and development of flotation equipment are focused on achieving a large-scale, high-efficiency, energy-saving, and environmentally friendly separation [3,4]. To date, three main types of flotation machines have been widely used in different flotation process of minerals: mechanical flotation machine [5], Jameson cell [6], and flotation column [7].…”

“…The center line of the nozzles is in the same horizontal plane as that of the driving impeller. Figure 2 shows the structural schematic of the double cosine self-aspirated nozzle, the most important part of the flotation device, which mainly comprises three components: (1) an ejector pipe for jetting high-speed slurry and injecting air flow, (2) a suction pipe for drawing in air from the atmosphere, and (3) an outer nozzle for forming the suction and mixing zones between the ejector for jetting high-speed slurry and injecting air flow, (2) a suction pipe for drawing in air from the atmosphere, and (3) an outer nozzle for forming the suction and mixing zones between the ejector pipe and outer nozzle. The cone angle of the cosine section of the ejector pipe and that of outer nozzle were both designed to be 28…”

Tracking of Particles in Froth Using Neutron Imaging

“…The conditioned pulp is introduced into large mechanical flotation cells. The size of these cells is permanently increased and can range up to 600 m 3 , even though upscaling causes several technological difficulties . Near the bottom of the flotation cell, small gas bubbles are introduced by turbulent mixing.…”