Page 57 - Hub Magazine Issue 56
P. 57

Washing &
Screening
the main issues is maintaining the optimum depth of the material for stratification to occur during all feed conditions. For example, if the feed quantity drops off, the float descends and the weir rises to increase the depth of material, and similarly if the feed rate increases the float rises and the weir descends, decreasing the depth to an optimal level. This can be manually adjusted through the Human User Interface (HUI) if required, but generally this is an automatic function.
“When commissioned it was set up so that the depth of material would be approx. 100mm from the bottom of the flume which maintains a safety zone.
“Each of the 4 jigs has a touch screen HUI for adjustments and monitoring historical feed conditions and settings for a period of up to three months. This allows trend monitoring and is a good tool in preventing lost time incidents.”
“Lignite at Newbold varies from 0-2% by weight, the lignite density which is unusually high.”
Carly Denton – Quarry Manager, further added, “As-dug material is very variable at Newbold and we are currently on phase 2 of our excavations which is mainly 70-75% sand, but the percentages can easily turn around! Our on-site laboratory periodically take samples, so we know what to expect from the area we are excavating.”
Due to the water PH values the machines installed at Newbold are of a fully galvanised finish as requested by AI.
In comparison to other machines in the market the ST jigs not only use significantly less water and are a lot quieter, but the main advantage over star wheel discharge compared to the ST dynamic weir, is wear.
Carly, summarised, “We are very happy with the installation, the jigs are removing the lignite very efficiently, we just have to keep an eye on the bed depths and adjust accordingly. The ST team looked after us very well at every stage of the commissioning and are readily available for any consultation.”
www.hub-4.com May/June 2019 - Issue 56
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