Show local man gets fagent on fc zinc lead fume NEWTON mass A ng bince lead fume invention of car los bardwell badwell tooele thoele recently was given a patent number by the united states patent office it was explained that in the blowing of lead blast furnace slag with air and powdered coal in a slag tie ti eating a tang furnace a powdery zinc oxide material is deposited by the condensation of fumes this substance commonly called fume generally contains about 65 per cent zinc and nine percent lead the lead fume of this fume has been removed heretofore by pass ing it through a brick lined rotary kiln for about 45 to 55 minutes the temperature between the feed en trance and the discharge end of the kiln progressively increasing I 1 from about 1100 to 2400 degrees fahrenheit however according to mr 1 r bard well the high maximum temp era ture required in this opera operation tion causes rapid deterioration of the brick lining in the kiln thus caus ing a frequent interruption of op orations erat ions with a consequent increase in cost moreover anen capacity by this method only fair lead elimination is ob tamed to eliminate the difficulties it recently has been found that the addition of a small amount of corn coin mon salt to the fume will result in improved operations but al though this process results rest its in bet ter de leading of large quantities of fume and a more continuous op aeration the chlorine n eless creates a destructive efant on flues and on the collecting bags which are made of wool it is the object of mr bardwell s invention to improve these hereto fore known practices of de leading crude zinc oxide fume aid d for this purpose he has disco ered that the addition of a small amount of ground coke to the fume promotes the volatilization or val va Driza tion 0 of atiq fillS lpyd Sd t d q and under properly co controlled arol ed conditions makes possible a selective removal from the fu fume of a large proportion of the lead he cites an actual test in which the de leaded zinc fume contained 05 0 5 to 1 percent lead and about 77 percent zinc while the lead fume produced thereby comprised about 50 percent lead and 10 per cent zinc moreover the kiln temperatures necessary for his process are not unduly detrimental to the brick lining and the coke which con fists considerably less than the common salt formerly used im parts no undesirable properties to the lead fume this patent has been assigned to the international smelting and he re fining co |