Muck bar still contains too much cinder and is too lacking in homogeneity for use.

Fig. 22. - Re-heating Furnace used in Making Wrought Iron.

When cold, it is cut into lengths of about 3 1/2 feet. Bundles measuring about 20 inches wide by 20 inches high are then made up of muck-bar lengths and wrought-iron scrap. Each bundle, called a pile, is held together by a wrapping of heavy wire or thin iron bands. A number of these piles are shown on the right in Fig. 22, ready for wrapping. These piles are placed in a re-heating furnace of the general type shown in Fig. 22, heated about three hours until they reach welding heat and are then taken out one at a time, and quickly passed through heavy rolls adjacent to the furnace.

A few passes back and forth through these rolls, called the roughing rolls, squeeze out a great amount of the remaining slag with much explosion and noise and thoroughly weld together the several pieces composing the pile. The rolls then work the mass down to approximate shape as plates or bars and it is then conveyed along the roller table to the finishing rolls by which it is shaped into sheets, bars, or rods as may be required.

For rapidity and economy of handling piles there are several re-heating furnaces and at least one set of roughing rolls placed along the arc of a circle, at the center of which is a heavy electrically operated crane so mounted with a horizontal arm that piles may be transferred from the furnaces to the roller table with a minimum loss of time.