Coal Age

JUN 2016

Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.

Issue link: https://coal.epubxp.com/i/695160

Contents of this Issue

Navigation

Page 41 of 67

40 www.coalage.com June 2016 fine coal recovery continued Case Study Two: Metallurgical Coal Treatment of screen drain material with the SCI unit at a metallurgical coal plant resulted in a SCI product total moisture averaging 21.1%. This testing processed up to 170 gallons per minute (gpm) of screen drain slurry. The slurry averaged 16.7% solids by weight and generated as much as 9 tph of product that was recovered by the SCI unit. The average tonnage generated with the SCI unit was 7 tph. Additional data reviewed during this test included thickener feed samples. These were collected with the SCI unit running (SCI ON) and with the SCI unit offline (SCI OFF). Based on materials bal- ance calculations of comparative thicken- er feed from the on/off test sets, approxi- mately 1/2 (4 tph) of this SCI product was additionally recovered fine coal. Summa- ry results from this test are displayed in Table 2. Also, the removal of the recirculating material for processing by the SCI unit caused the particle size distribution of the screen bowl feed to become coarser. Therefore, screen bowl product yield in- creased and cake moisture decreased. An additional tell-tale of the improvement: the ash content of the thickener feed sol- ids increased when the SCI unit processed screen drain material. This provides fur- ther evidence that the SCI unit recovered low-ash clean coal previously being lost to the thickener. Dewatered cake produced from a 1:1 mixture by volume of screen bowl drain and bowl effluent averaged 23% total mois- ture content at this site. This treatment yielded about 5 tph of newly recovered fine coal with nearly the same ash content as the cake produced from screen drain feed. Installation and Results Extended testing of the Sub325 system at a 500-tph metallurgical coal plant resulted in 14 tph of SCI product at 19.7% moisture with 6.8% ash 0.92% sulfur and 11,545 Btu/ lb. This product was of higher quality than the targeted plant product. It also repre- sented a large recirculation of clean coal re- moved from the fine coal circuits. The sec- ondary benefits at this plant were dramatic. With the extended testing, the plant managers were able to review and use ac- tual process data to tune the plant. They were able to increase the recovery in the entire fine coal circuit and increase recov- ery in other circuits as well. The net effect was a plant yield increase of about 1.5-2% of ROM feed with no discernable increase in the percentage of fines in the total plant product. At some locations, this yield im- Table 2 — Metallurgical Coal Case Study

Articles in this issue

Links on this page

Archives of this issue

view archives of Coal Age - JUN 2016