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to replace metallurgical coke. The process generates poten-


tial energy savings of 3% (Table 3), not including the energy available in the sold byproducts, and greenhouse gases are reduced 2.8%. Criteria pollutant and VOC emissions also improve dra- matically due to the closed nature of the process. Overall costs are reduced 20.6%, with the increase in labor costs offset by reduced material and energy costs. Income from the sale of the byproduct materials (shown in “other costs”) is substantial, making the net payback approximately two years.


Tune-Up: Advanced Oxidation With Hydroacoustics


A U.S.-based company has


devised an advanced oxidation system that applies ozone, hydrogen peroxide and sonication to a water


Te most significant cost, energy and material savings


occur when facilities adopt a combination of innovative technologies.


slurry known as “blackwater” to reprocess baghouse waste dust. Te baghouse dust slurry is treated with advanced oxidation and replaces the conventional water source for the green sand molds. Research indicates the process, currently in


use at 50 iron casting facilities, uses 27-60% less clay and coal, 20-37% less silica sand and pro- duces 19-70% less VOCs during pouring, cooling and shakeout. An upgrade of this process


includes hydroacoustics, cavita- tion, recirculation and virtual cyclone (AO-HAC), which has been installed in 10 U.S. facili- ties. This process acoustically dislodges the hydrophobic car- bonaceous coating that forms when volatiles are pyrolyzed from the coal and binders near molten iron. The VOCs then migrate into the cooler


green sand mold and recondense. Advanced oxidation dislodges the condensed volatiles from the clay and sand surfaces, restores the hydrophilic binding propensity of the clay, and prevents them from re-volatilizing as VOCs during


March 2014 MODERN CASTING | 49


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