Buffalo Paper - A Note upon a Modification of the Reducing Process Used by the Carbon Iron Company

In a paper written for the Boston meeting of February, 1888 (Trans., xvi., 693), on "Some Recent Improvements in OpenHearth Steel Practice," the writer described the reducing agent used by the Carbon Iron Company as "a peculiar graphite from Cranston, near Providence, R. I." Upon an application pending at that time, a patent has since been issued as number 259,795, to Mr. Matthew Graff, for the use of solid carbonaceous matter in the form of coke, charcoal, gas carbon, bituminous or anthracite coal, ground to the size of coarse sand and then coated with a mash of lime, magnesia, clay, or other material of a like character, as an agent to reduce metallic oxides. An amount of this prepared carbonaceous matter equal to from 25 to 30 per cent. of the weight of the ore treated is required to perform the complete reduction. The idea is that the carbonaceous matter is protected against rapid combustion by a suitable coating of some inert material, so that, in effect, its action as a reducing agent will be similar to that of the Cranston graphite previously used, allowing the solid carbon to remain without combustion in intimate mixture with the iron oxide at a temperature sufficiently high to reduce the ore and in some cases to melt the matrix in which the iron is held. In the present practice of the Carbon Iron Company, the use of graphite, except for the formation of bottoms of the reverberatory furnaces in which the reduction is performed, has been entirely abandoned, and " retarded coke," as it is called at the works, has taken its place. Five hundred and fifty pounds of Connellsville coke is ground in a pan to 16-mesh fineness, or is taken in the form of ordinary coke-dust, and made into a hollow basin on the mixingfloor ; and seven bucketfuls of a wash composed of equal parts of lime and fire-clay, mixed in water to the consistency of thin cream,