It takes
up the oxides of iron formed by the contact of the oxidizing flame
with the exposed portion of the metal bath, and at the same time the
carbon of the iron, coming in contact with the under surface of the
cinder covering, where it is protected from oxidizing influences,
reduces these oxides from the cinder and restores them to the bath in
metallic form. This alternate oxidation of exposed metal, and its
reduction by the carbon of the cast iron, continues till the carbon is
nearly exhausted, when the iron assumes a pasty condition, or "comes
to nature," as the puddlers call this change. The charge is then
worked up into balls, and removed for treatment in the squeezer, and
then hammered or rolled. In the Wilson process the conditions which we
have noted in the puddling operation are very closely approximated.
Iron ore reduced to a coarse sand is mixed with the proper proportion
of charcoal or coke dust, and the mixture fed into upright retorts
placed in the chimney of the puddling furnace. By exposure for 24
hours to the heat of the waste gases from the furnace, in the presence
of solid carbon, a considerable portion of the oxygen of the ore is
removed, but little or no metallic iron is formed. The ore is then
drawn from the deoxidizer into the rear or second hearth of the
puddling furnace, situated below it, where it is exposed for 20
minutes to a much higher temperature than that of the deoxidizer.
Pages:
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139