SMOKE AND DUST ABATEMENT — COTTRELL. 679 



saving of values lost through waste gases began to claim general 

 interest, and at present a large number of precipitating plants arc 

 under construction and several are already operating in copper, lead, 

 and iron smelters, metal refineries, cement mills, and a varied set of 

 chemical industries. 



It is unnecessary here to describe any of these plants in great 

 detail as they represent essentially the same principles as those 

 already discussed, but the accompanying illustrations may serve to 

 give an idea of the present trend of the subject. 



Figures 34 and 35 show current on and off in an experimental unit 

 erected about the end of 1911 at the Garfield copper smelter in Utah 

 to treat the gases from basic lined converters handling a copper 

 matte carrying a small percentage of lead. Tn this case 5-inch steel 

 pipes carrying the gases acted also as grounded or collecting elec- 

 trodes, the discharge electrodes being wires stretched axially within 

 them. The deposited material was shaken down from time to time by 

 striking the pipes witli a system of hammers attached to the rocking 

 shafts seen in the picture passing behind the front row of pipes, A 

 pile of this deposit, consisting chiefly of basic lead sulphate, carrying 

 gold, silver, and other values is seen on the ground to the right. 

 This unit consisted of 24 pipes and was followed by another one of 

 COO pipes, which was successfully operated for about a month on 

 steady tests taking the wliole of the gas from one large basic con- 

 verter and part of the time a part of that from another one as well. 

 A part of this equipment was then moved to a point where gases from 

 the other departments — that is, blast furnaces, reverberatories, and 

 roasters — could also be secin^ed. and experiments continued on each 

 of these and on mixture of them. They Avere all found to be easily 

 handled. The others in faiH even more easily than the converter 

 gases shown above, but these latter contained the highest values. 

 This installation is seen in figure 36, the small building to the right 

 containing the transformer and rectifier, while one of the large 

 catenary flues appears in the backgTound. Having determined to 

 build a new flue system and dust chamber for the blast furnace and 

 converter gases at Garfield, it was decided to incorporate an electrical 

 precipitation plant for the treatment of all the converter fumes. 

 This entire project is now under construction, and in the planning of 

 this flue system provision has also been made for the installation of 

 an electrical precipitation plant for the treatment of blast fur- 

 nace gases, should it later be decided to do so. The precipitation 

 plant for the converter gases is expected to be in operation by fall of 

 this year.^ 



* " Electrical Fnnie rrecipitation at Garfield," by W. H. Howard. Taper presented at 

 Salt Lake mooting- Amer. Tnst. Min. Eiig. Aug. 11, 1914, and later tn appear in the 

 transactions. 



