Location of Sorbents for Desulphurization Processes in Coal Combustion Applications

The separator handled fine coal and produced a 28 MJ/kg product, but its measured separation efficiency was lower than that of conventional dense medium cyclones and it was harder to operate. Two efficiency tests produced no evidence that the unit outperforms cyclones on fine coal, so cyclones were recommended when the plant was rebuilt at its next site.

South African underground sections average about 60 000 t a month, against 130 000 to 160 000 t for single pass bolter miner units on continuous haulage, while the better sections target 1.4 to 1.6 Mt a year. Australian longwalls deliver 5 to 7 Mt a year from one face, compared with 3 to 5 Mt at the two local wall operations.

Heat exchanger material governs how fast ice scale forms during eutectic freeze crystallisation of dilute brine. Induction time fell as thermal conductivity rose, so copper scaled first, while aluminium gave the lowest scaling rate because its low surface energy pushed ice crystallisation into the bulk. Stainless steel delayed onset but scaled heavily once nucleation started.

Practical guidance for opencast operations covers early detection with low cost thermal cameras, prevention, and the treatment methods in current use: water sprays and cannons, sand cladding of highwalls and stockpiles, removal of burning coal by dragline, tipping into water ponds and the treatment of sinkhole areas. A three month full scale trial of sprayed fly ash as an antioxidant is reported.