678 ANNUAL EEPOET SMITHSONIAN INSTITUTION, Um. 



after completioi). Figures 30 and 3i are photographs of the iiiaiu 

 stack taken a feM^ minutes apart, with the electric current respectively 

 off and on. 



Filtration tests upon the gases before and after the electrical treat- 

 ment throughout the nine months of operation showed that this plant 

 under favorable working conditions precipitated between 80 and 90 

 per cent of the suspended matter in the gas, the average over the 

 whole period of operation being somewhat less, while after intro- 

 ducing improvements in detail of construction on one of the units 

 shortly before the final shutdown of the plant the efficiencj^ of this 

 unit was carried well up into the nineties. Under average operating 

 conditions at the smelter some C to 8 tons of precipitate were col- 

 lected per 24 hours. Figiu'e 32 shows this steady stream of precipi- 

 tated smoke as it flowed night and day from the end of the conveyoi- 

 coming from the imits, and figure 33 shows the stock pile of several 

 hundred tons of this as it collected below the discharge. 



The gas-treating plant as a whole, including flues, fans, motors, and 

 electrical apparatus, cost, up to the time it was first put in operation, 

 a little less than $110,000. .Vlthough many minor changes were later 

 made, none of the larger or more expensive elements of construction 

 were greatly altered. 



The total average power consumption for the precipitation plant 

 was in the neighborhood of 120 kw. One man could readily control 

 the whole operation in the rectifier house, although as a matter of 

 precaution for a new plant under the high tension here used, two 

 were usually on duty. Two laborers and a foreman were employed 

 on the precipitating units and dust-handling system, although this 

 could have been reduced somcAvhat by automatic shaking devices, as 

 in the Riverside Plant described below. 



The volume of gases treated varied considerably with the condi- 

 tions at the furnaces, but may fairly be taken as averaging betAveen 

 200,000 and 300,000 cubic feet per minute, and entering the units at 

 from 100" to 150° C. 



WORK AT OTHER WESTERN SMELTERS. 



This plant, Avhile not able to save the Balaklala smelter from an 

 eventual shutdown, formed a very important link in the develop- 

 ment of the processes to their present status. The interest of the 

 smelter companies up to this point depended almost entirely on the 

 hope of eliminating smoke as a nuisance and its attendant litigation 

 with their neighbors; and had it not been for the life or death 

 struggle that this meant to them, it is probable that the success of 

 the electrical processes might have been delayed many years longer. 

 Once brought, however, under this powerful stimulus to the state of 

 doA^elopment aboA^e described, the importance of these processes foi* the 



