The effect of residence time and aeration on coal recovery within the high density zone of a flotation machine

The high intensity zone within the Jameson Cell is the downcomer. It is largely external and separated from the flotation tank. This, together with operation of the downcomer under vacuum, rather than at elevated pressure and the absence of moving parts, allows ready access to the high intensity zone for measurement and analysis. Experimentation was conducted allowing measurements of recovery for residence times of between 20 milliseconds and ten seconds within the downcomer of a Jameson Cell. The affect of aeration rate on the recovery of different particle sizes was also studied

Recent advances in jameson flotation cell technology

The development of the Jameson flotation cell has provided a new and radical approach to flotation technology. Characterised by rapid flotation kinetic rates and the ability to produce high grade concentrates the Jameson cell is finding wide acceptance in the minerals industry. From an initial installation in lead slimes cleaning the Jameson Cell is now in operation treating coal, nickel, zinc, copper, leached oxides, antimony and for removal of organics from electrolyte solution. Operations are conducted across a wide range of particle sizes and pulp densities, in cleaning, roughing, scavenging and flash flotation roles

Improving the recovery of coarse coal particles in a Jameson cell

It has been observed in several Jameson cell installation where the source for flotation feed is deslime screens, that the recovery of coal particles greater than 0.5 mm is not as great as that of finer material. Consequently, a research project was undertaken at a CHPP in the Bowen Basin Queensland to assess the possibility of increasing the recovery of coarser particles (+0.5 mm) within the downcomer of the Jameson cell. The effect of decreasing turbulence and agitation in a commercial-scale downcomer was investigated to assess the effect oil the recovery of both coarse and fine coal particles. This paper details the findings of the test work, summarising the results relating to differences in the operating parameters within the downcomer. (C) 2005 Elsevier Ltd. All rights reserved

Improving the recovery of coarse coal particles in a Jameson Cell

It has been observed in several Jameson cell installations where the source for flotation feed is deslime screens, that the recovery of coal particles greater than 0.5 m is not as great as that of finer material. Consequently, a research project was undertaken at a CHPP in the Bowen Basin, Queensland, to assess the possibility of increasing the recovery of coarser particles (+0.5 mm) within the downcomer of the Jameson Cell. The effect of decreasing turbulence and agitation in a commercial-scale downcomer was investigated to assess the effect on the recovery of both coarse and fine coal particles. This paper details the findings of the testwork, summarising the results relating to differences in the operating parameters within the downcomer

CW and pulse EPR of cytochrome P450 to determine structure and function

Cytochromes P450 (P450s) are a diverse class of biological monooxy-genases found in a wide variety of organisms, known for their chemical versatility and reaction specificity. While an array of chemical techniques are available to study P450s, continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopies provide unique insight into the structure and function of the protein by probing various paramagnetic states. In this review we will demonstrate how EPR techniques are used to reveal information about the arrangement and conformation of P450 electron-transport protein complexes, characterise the active site oxidation state and the interactions with substrates and inhibitors. In addition, when combined with sample preparation using cryoreduction and freeze-quench techniques, EPR can be used to characterise short-lived intermediates formed during the catalytic cycle

Root-Secreted Coumarins and the Microbiota Interact to Improve Iron Nutrition in Arabidopsis

Plants benefit from associations with a diverse community of root-colonizing microbes. Deciphering the mechanisms underpinning these beneficial services are of interest for improving plant productivity. We report a plant-beneficial interaction between Arabidopsis thaliana and the root microbiota under iron deprivation that is dependent on the secretion of plant-derived coumarins. Disrupting this pathway alters the microbiota and impairs plant growth in iron-limiting soil. Furthermore, the microbiota improves ironlimiting plant performance via a mechanism dependent on plant iron import and secretion of the coumarin fraxetin. This beneficial trait is strain specific yet functionally redundant across phylogenetic lineages of the microbiota. Transcriptomic and elemental analyses revealed that this interaction between commensals and coumarins promotes growth by relieving iron starvation. These results show that coumarins improve plant performance by eliciting microbe-assisted iron nutrition. We propose that the bacterial root microbiota, stimulated by secreted coumarins, is an integral mediator of plant adaptation to ironlimiting soils