Models of Blast Furnaces 3 



The charging platform is connected with the top 

 of the elevator tower by a bridge. Over this bridge the 

 charge of ore, coke and limestone is wheeled in bar- 

 rows or small cars. The top or THROAT of the fur- 

 nace opens at the center of the charging floor. This 

 opening is ordinarily closed by the BELL, a conical 

 valve opening do^vnwards. The barrows or cars which 

 bring the charge are dumped on top of the bell. The 

 bell is then momentarily depressed and the charge 

 falls into the furnace. When the bell is opened the 

 furnace fumes come through to the charging floor so 

 a short smokestack is provided by which they may 

 escape. The bell is closed nearly all the time and the 

 products of combustion cannot escape through the top. 

 They then pass through an opening in the furnace wall 

 immediately below the bell to the DOWN-COMER, a 

 large brick-lined pipe which passes downward out- 

 side the furnace. Through the down-comer the gases 

 pass to underground conduits which conduct them to 

 the places where they are used. THE GAS BLOW- 

 OFF is a smokestack connected with the down-comer 

 and closed at the top by a valve. By opening this valve 

 any surplus gas may be allowed to escape. The gases 

 from the furnace carry with them dust from the ore 

 and fuel in the furnace. Much of this dust settles in 

 the DUST-CATCHER, a chamber connected with the 

 down-comer. From time to time the dust is drawn off 

 through a gate in the bottom of the dust-catcher, and 

 after suitable treatment, fed back to the furnace. The 

 shaft of the furnace gradually widens downward for 

 more than half its length to the place where it is widest 

 which is called the BOSH. From the bosh it nar- 

 rows gradually to the hearth at the bottom. This 

 tapering part from the bosh down to the hearth is 

 called the BOSHES. In this area the heat is so in- 

 tense that the fire-brick walls would either melt or be 



[15] 



