SMOKE AND DUST ABATEMENT — COTTEELL. 675 



front of the bag house in the picture. There are 40 of these pipes, 

 each 4 feet in diameter and averaging about 200 feet in length. They 

 represent a very large part of the cost of the installation. It was 

 expected that they would be sufficient to cool the entire gases of the 

 plant to a safe temperature to protect the $30,000 worth of woolen 

 bags with which the house is filled, but upon starting up with the 

 gases passing through all the pipes in parallel it was found that only 

 a little over half the full capacity of the plant could thus be treated 

 with safety and operations were accordingly restricted to this. In 

 the cold weather of winter a considerably larger tonnage can be 

 Iiandled with safety than during the hot summer. Subsequently by 

 rearranging the pipe connections so as to have eight groups in par- 

 allel, each consisting of five pipes in series, the company succeeded 

 in greatly increasing their efficiency as coolers, and thus materially 

 increased the plant capacity over that first obtained. Provision was 

 also made to supplement the pipe cooling by the blowing in of out- 

 door air when necessar3^ The fan power necessary to move all this 

 vast weight of air and furnace gases through the bags and pipe sys- 

 tem is of course considerable, reaching at times well up toward the 

 1,000-horsepower mark. Notwithstanding this, however, the bag 

 house is to be considered a decided success, at least for the particular 

 conditions met with at this plant ^ and the management deserves great 

 credit for the courage and skill with which it has carried through 

 this new and after all largely experimental undertaking, represent- 

 ing as it does the expenditure of over a quarter of a million dollars. 



In the case of the Balaldala Smelter, of which figure 20 is a general 

 view, the use of a bag house was also considered, and in fact a small 

 experimental unit containing a few bags was run for some months 

 in comparison with tests both by the electrical process here de- 

 scribed and also a centrifugal apparatus in which the gases passed 

 through a rapidly-rotating cylindrical shell equipped with radial 

 baffles to insure the gas being raised to full velocity. As a result of 

 these tests the electrical process was adopted for the full-sized in- 

 stallation. 



The smelter was treatmg from 700 to 1,000 tons of 2| to 3 per 

 cent ore carrying over 30 per cent of sulphur with considerable but 

 varying amounts of zinc, the greater proportion of this being handled 

 in blast furnaces, but the fines including everything under an inch 

 and amounting to less than 10 per cent of the whole going through 

 MacDougal roasters and an oil-fired reverberatory. The plant has 

 also two converter stands. The gases from all these departments 

 passed into a common flue 18 by 20 feet in cross section, an interior 

 view of which at the main by-pass damper is shown in figure 21. 

 The volume of gases passing through this flue varied with operating 

 conditions from a quarter to half a million cubic feet a minute, whioh 



