162 Miitfrialx and Their Handling 



hoisted into the blast furnaces. From there the 

 molten pig iron is conveyed by cars to the con- 

 verters or furnaces to be made into steel and cast 

 into ingots. These are carried by cars to the 

 blooming and rolling mills, located in another 

 building, where the ingots will be rolled to the 

 required shapes. From there, they go into stock 

 or are shipped. The movement of the material 

 in this process is from one end of the plant, 

 through a succession of buildings, and out at the 

 further end. 



Steel Mill Develops into a By-Prod net Indus- 

 try. The steel mill was originally like the cotton 

 mill without by-products. In recent years, a 

 large by-product industry has grown up by utiliz- 

 ing the slag, which was formerly discarded, for 

 the manufacture of cement. The coke used in 

 making steel used to be a separate, single-product 

 industry. Now coke is often made on the grounds 

 of the steel plant in "by-product" ovens; and the 

 coal from which it is made produces, in addition 

 to the coke, three valuable by-products: gas, tar, 

 and ammonia. The gas is collected, purified, and 

 used throughout the plant for heating and power 

 purposes. The tar is sold to be worked up into 

 aniline, creosote, and pitch. The ammonia is in 

 the form of a sulphate, which after further treat- 

 ment may be used as a fertilizer. 



Sugar Refining A Non-By-Product Industry. 

 Sugar refining is an industry of the non-by-product 

 type, handling solids and liquids. The largest re- 

 fineries are located at the seaports, as the main 



