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Dear JOM Editor,
Regarding the article in the June 2014 issue of JOM titled "Moving Towards Better Recycling Options for Electric Arc Furnace Dust" by T. Suetens, Karel Van Acker, Bart Blanpain, Brajendra Mishra, and Diran Apelian,1 I would like to make some comments on the contents related to "in-process separation" in the article, particularly the following paragraph: "Recently, N. Ma proposed a radical new approach, the in-process separation (IPS) technology,[31,32] in which zinc is removed from the EAF off-gas before it can react with iron-containing particles to form the ZnFe2O4 phase in the combustion chamber (Fig. 2). The dust collected in the baghouse filter can then be sent directly to the CZO treatment plant as it will no longer contain Fe. Depending on the atmospheric conditions in the off-gas treatment system, iron or iron oxide particles can be returned to the EAF." As the author of the work cited pertaining to in-process separation, I would like to offer some clarification.
First, in-process separation is not a specific technology solely for recycling of EAF dust. Instead, it is a general strategy which might be applied to recycling of any waste streams. The generalization of inprocess separation was discussed in detail in my paper in EPD Congress 2014.2
Second, in-process separation is not "a radical new approach" at all. Instead, it is an evolutionary recycling strategy. In the TMS EPD Congress 2014 paper,2 I wrote "In-process separation is to separate undesired components from solid wastes in production processes where the solid wastes are being generated. Unlike before-process separation and post-process separation, in-process separation has not been very well established. In 1996, US EPA called for research proposals of 'novel cost-effective methods for the highly efficient in-process separation of useful materials from the components of process waste stream'[1] and continued the call till 2003.[2] The American Iron and Steel Institute recommended using an in-process separation strategy to separate useful materials from waste refractory stream.[3] Though technologies...