TAILINGS
FLSmidth on a new innovation in paste thickening
An interesting white paper from Fred Schoenbrunn , Antonio Accioly and Craig Gilbert of FLSmidth ’ s Thickener Group along with Francisco Reyes , Regional Product Manager , FLSmidth in Chile , discuss a paste thickening project at a major copper concentrator in Kazakhstan . The operation was considering adding a second full concentrator plant to double capacity .
Their existing high compression tailings thickeners were designed based on 65 wt % underflow but were only capable of producing 61- 63 wt %. The TSF required earlier than planned expansion as a result . For the second plant , the customer requested 68 wt % underflow . Based on the design and performance of the existing thickeners , a design innovation was needed to ensure the Plant 2 thickeners would achieve the higher underflow densities . The paper reviews several projects that led to the development of the Inner Spiral Blade innovation , that provides the high raking capacity needed for high tonnage and high density paste thickening .
The authors state : “ Development of higher underflow densities from thickeners has long been a goal of thickener designers . The factors that limit the underflow density are the mud retention time and the raking capacity . At higher underflow densities the mud develops a yield stress or resistance to movement , and is limited in its ability to flow hydraulically to the underflow outlets . Designs for ‘ high density ’ thickeners have existed for decades . In general , for higher underflow densities incorporate higher torque capacity , greater depth and mud retention time , and improved rake designs . Multiple new installations and retrofit projects have shown the limitations of the various technologies .”
They add that high density and paste thickeners have a chequered history with many of them struggling to achieve the densities they
An FLS Deep Cone Thickener
are designed for . Deep Cone Thickeners ( DCTs ) have had good success at smaller sizes and tonnages , proving the technology is possible , but large scale high tonnage machines have been more problematic .
A high density retrofit on a 65 m gold tailings thickener was installed at a Canadian gold producer and started up in 2016 . This is a high tonnage thickener processing about 65,000 t / d . “ Prior to the retrofit , underflow densities of 60-61
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