Baseline Testing of a Filter Press and Solid-Bowl Centrifuge for Dewatering Coal Thickener Underflow Slurry

Abstract

Laboratory testing was conducted to evaluate the performance of a plate-and-frame filter press and solid-bowl centrifuge for dewatering a bituminous coal refuse slurry. Filter press testing was conducted using a pilot-scale Technicas Hidraulicas (TH) filter press, which contains a single set of plates. The unit is also equipped with an air-blow system to remove additional moisture from the filter cake voids. Testing was conducted to evaluate the effects of filter time on filtrate flow and solids content, cake moisture, solids recovery, and unit capacity. Product moistures ranged from 27.3% to 29.6%. Filtrate solids contents were less than 0.6% with solids recoveries over 98%. The unit capacities ranged from 73 kg=hr=m 2 to 131 kg=hr=m 2 , with the lower values corresponding to the lower cake moistures.Centrifuge testing was conducted using a Sharples P660 solid-bowl centrifuge. Testing was conducted at several slurry feed rates at one dam setting with another test at a second dam setting. Product moistures ranged from 24.2% to 36.4%. Centrate solids ranged from 0.5% to 11.0% with solids recoveries from 65.2% to 98.4%. The solids feed rates ranged from 89 kg=hr to 338 kg=hr. Lower product moistures were associated with higher solids feed rates but at lower solids recoveries.

Dewatering effect of fine coal slurry and filter cake structure based on particle characteristics

“…Yang [13] studied the dewatering effects of a hyperbaric filter for different graded material, and reduced the cake moisture through modified filter support system or added nonionic flocculant. Alternatively, changing the way of dewatering or improving filter filtration equipment efficiency, and optimizing the operating parameters is another approach to improve dewatering [14,15]. However, there is no evidence in the literature of any work done in the area of split-size filtration and microstructure of filter cake.…”

A Model–Based Parametric Study of Centrifugal Dewatering of Mineral Slurries

“…Several investigations [1][2][3] have confirmed that a higher bowl rotating speed led to a higher solids recovery. Other studies [1,2,4,5] consistently confirmed that increasing the feed flowrate can increase unit throughput and reduce solids recovery. It has been suggested that thickening the feed slurry (i.e., increasing the feed solids concentration) can also improve the unit throughput of the SBC, but this practice will lead to a larger solids loss in the effluent stream [5][6][7].…”

“…Probably for confidential reasons, the detailed geometries, especially the pitch and weir radius of a commercial-scale SBC cannot be found in the public domain. The available geometrical information of the SBC was often from the literature, where pilot-scale SBC units with diameters ranging from 0.08 m [3] to 0.15 m [4,13], were used. Pedro [12] used an SBC with a diameter of 0.35 m to test the drilling mud dewatering.…”

“…Pedro [12] used an SBC with a diameter of 0.35 m to test the drilling mud dewatering. As the present study aims to explain the conflicting findings from [4,12], the diameter of the hypothetical SBC was set to 0.2 m. The pitch length, bowl length and blade thickness were obtained from an SBC manufacturer that match a 0.2 m diameter SBC. The geometries of the hypothetical SBC are summarized in Table 1 with the BSFC constant and the friction coefficient between the blades and sediments being set as 2.0 and 0.3, respectively.…”

“…Conflicting results were, however, reported in terms of the effect of the weir height and the differential speed on the solids recovery in solid bowl centrifugation. Experimental results from some studies [1,2,4] suggested that the solids recovery can be increased by adjusting the weir setting to a higher position, while other studies [11,12] reported a decline in the solids recovery when increasing the weir height. The effect of the differential speed on the solids recovery showed opposing trends depending on the feed rates [13].…”