McKenna Process Company
Plant formerly located in Joliet, Illinois - ca. 1920.

West End of rolling mill as seen ca. March 1900
Overall image - digitally enhanced to improve contrast in shadows. 

The waste-heat boilers are visible at far right.  Worn rails, their ragged heads casting uneven shadows, are neatly arranged in the foreground.
Enhanced image from Railway Age March 2000 article
Both images on this page appear with written permission (March 8, 2007) from the publisher of Railway Age Magazine.
The March 2000 issue of Railway Age reprinted an article first published in The Railway Age of March 1900, entitled, "Re-Newed Rails for Improved Service."  It is an account of a visit to the McKenna plant during the first annual convention of the American Railway Engineering and Maintenance of Way Association

Already in 1900 there were 80,000 tons of the renewed rails in service at about a dozen railroads (i.e., McKenna's only customers - George, III). 

Alas, the article goes on to repeat the early claim that the extra hot working, involved in lengthening the rails sufficiently to enable the battered ends to be cropped off, actually improved the steel.  More properly, the additional hot working broke the rails that were already cracked from prior fatigue or hydrogen damage (George, Jr., personal communication).  The McKenna company didn't get credit for the extra effort that this breakage caused in the mill.  Their customers paid only a service charge per ton for the successfully re-rolled rails and were additionally given credit for the tonnage of scrapped rails and cropped ends.

Another image of the same area, taken somewhat later after more clutter accumulated, is here.
Detail scanned from the right center of the image above, showing at least three and possibly several more men at work. 

Detail showing several men at work

The rail furnace opening is approximately in the center, and rails are fed into the furnace here, to be taken out at the opposite end inside the building when they are hot enough to be rolled.
Almost 100 years later, the truth be told. 

Defence Estates, an Executive Agency of the [British] Ministry of Defence
had this to say about re-rolled rails in July, 1997:

Used rail may be factory re-rolled to restore its profile. The new weight will be less than the original and this must be taken into account when determining maximum axle loadings and sleeper spacing. Re-rolled rail cannot be regarded as equal in quality to that of new rail but will be acceptable for most narrow gauge work. It should not be used in standard gauge running line.