Grinding, cost

E. Goodrich have burned a 10% tire chip mixture with coal (11—13). Tire grinding size reduction problems and deflvery costs have stymied projects based on combined tire and coal fuel. Transportation of tire scrap can cost 0.05 /kg, exclusive of grinding costs, thus tire-fired boilers are limited to areas with sample scrap tire suppHes, eg, large cities or tire manufacturers. The cost of burning one metric ton of tires per hour in an incinerator was ca 0.20—0.40 per tire in 1974, which increased to 0.35—0.70 per tire in 1987 (14). 

Whole tires have been pyrolyzed in an experimental semifluidized-bed reactor (27). The tires are pyrolyzed on a grate that tilts to discharge the steel belt and bead wire. The pyrolysis of whole tires eliminates shredding and grinding costs. 

Aluminium and magnesium hydroxides are difficult to produce directly in any useable form from their natural ores. Filler grade calcium carbonate is widely produced from natural sources, but grinding costs appear to become prohibitive when ultra-fine particles are required and precipitation procedures then become competitive. Further details of precipitation procedures will be found under the specific filler types. 

Grinding cost increases with the reduction in size Coal rank... 

Adipic acid-enhanced limestone scrubbing has lower projected capital and operating costs than unenhanced limestone or MgP-enhanced limestone scrubbing. This is due primarily to the reduced limestone consumption at the lower operating pH, the reduced grinding cost, and the reduced quantity of waste sludge generated. 

Sorbent particle size is also important. Removal efficiencies increased with decreasing mean particle size. The finest material tested had a mean particle diameter of 32 pm. Whether finer grinding is warranted in industrial applications would depend on an economic analysis taking into consideration both increased sorbent utilization and increased grinding costs with finer grinding. 

For Snj = 0.45, uJVqj i = 7.7, which is a much lower ratio than for fine particles. This may be a slight disadvantage to the use of coarse particles in a fluidized bed, but the optimum particle size generally depends on other factors such as grinding cost, heat- and mass-transfer rates, and desired gas velocity,... 

The particle size analyzer reduces grinding costs in Pit and Quarry, September 1977 — News article. 

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