February, 1925
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
a hard mass. The treatment with sodium hydroxide involving 7 pounds (3.2 kg.) of flake material was more promising, producing an alkalinity that should be satisfactory in inhibiting corrosion, but much less than the theoretical. The average temperature of the brine was about 18" F. (-8" C.), at which a brine with a gravity of 1.1 could reach an alkalinity of 2.5 per cent normal. It is unfortunate that this case could not be studied to a final conclusion. The data obtained may be taken to indicate a commercial possibility with sodium hydroxide, however. A second commercial case coming under observation involved the treatment of a brine that had become slightly acid. Quicklime in the amount of 10 pounds per 1000 gallons (1.2 kg. per 1000 liters) of brine was put in a bag and hung in the tank. Several weeks later the brine showed an alkalinity of only 0.15 per cent normal. Another case has afforded valuable data. The brine, initially quite weak and about neutral, was strengthened by adding fresh calcium chloride. This was followed by treatments with quicklime in accordance with the data in Table 11. Table 11-Effect of Adding Fresh CaCla Followed by Lime Treatment Time Ah;;t& Days Gravity N o treatment 0 1.07 0.10 15 Fresh chloride added 0.25 1.12 31 0.20 1.12 37 Treated with lime slurry, 10 pounds per 1000 gallons (1.2 k g . per 1000 liters) after taking above sample 1.12 1.85 38 1.12 1.90 39 1.12 1.90 40 1.12 2.00 41 1.10 1.70 43 1.70 1.10 44 1.50 1.10 45 Fresh chloride added 1.70 1.11 46 1.70 1.11 47 1.70 1.11 48 1.40 1.11 53 Treated with lime slurry, 5 pounds per 1000 gallons (0.6 kg. per 1000 liters) 2.50 54 1.11 2.50 55 1.11 2.30 1.11 57 2.30 1.11 59 2.30 61 1.11 1.90 75 1.11 1.40 93 1.10 1.00 95 1.10 Treated with lime slurry, 5 pounds per 1000 gallons (0.6 kg. per 1000 liters) ; bag of lime i n tank 96 1.10 2.50 97 1.10 2.30 107 1.09 2.40 114 1.09 2.10 Fresh chlortdc added 121 1.13 1.50
The theoretical maximum alkalinity for the brine involved is 2.5 per cent normal. The rather impure commercial quicklime initially added did not bring the maximum results, and so another treatment involving half the previous amount of lime was made. The brine responded to this promptly, but after a few days the alkalinity dropped off. When it had reached 1.0 per cent normal, another treatment was made and, in addition, a bag of lime was hung in the tar$. The alkalinity again came up to the maximum, but it dropped off in substantially the same manner as previous to the use of the bag of lime. These studies indicate that the desired alkalinity can be reached by the use of lime as a slurry, but that the treatment with the bag of lime will not even maintain previously established alkalinity, to say nothing of producing alkalinity. SODIUMCHLORIDE BRINE-several cases involving sodium chloride brine have been noted. I n the first the brine was initially practically neutral. Lime hung in bags over the side of the tank produced only a very slight alkalinity. I n another case brine with a gravity of 1.16 was treated by
133
direct addition of slaked lime in water suspensioh. An alkalinity of 3.5 per cent normal resulted, approaching the theoretical for the brine involved. It was found impossible to maintain this alkalinity by means of lime in a bag hung in the tank, but direct additions made from time to time accomplished the desired results. The cases that have been cited are typical of a larger number on record. The conclusions to be drawn from the various studies are substantiated by all the data at hand. The data in the tables are presented graphically in Figure 2.
0
10
20
30
-40
60
60
70
80
90
100
110
Time D c ~ Figure 2-Commercial T r e a t m e n t of Calcium Chloride Brine I-Data from Table I: 0-Freshly prepared brine 2-Bag of slaked lime hung in tank 90-Bag of flake sodium hydroxide hung in tank 11-Data from Table 11: 0-Initial weak brine 15-Fresh chloride added 37-Treated with lime slurry, 10 lbs./1000 gals. 45-Fresh chloride added 53-Treated with lime slurry 5 lbs./IOOO gals. 9 k T r e a t e d with lime slurry' 5 lbs./1000 gals., and bag of lime hung in tank
*
Recommendations The author's present knowledge concerning the prevention of corrosion by brine, based in part on previously published work not included herein, leads to certain very definite statements. 1-For making calcium chloride brine, a chloride free from magnesium chloride should be used. 2-The gravity of the brine should be kept in the neighborhood of 1.20. 3-Either calcium or sodium chloride brine should be treated with pure quicklime on the basis of 10 pounds of lime per 1000 gallons (1.2 kg. per 1000 liters) of brine, or with sodium hydroxide on the basis of 13 pounds per 1000 gallons (1.6 kg. per 1000 liters). 4-The reagents should be added as a slurry or solution at a point of rapid brine circulation, though the introduction of sodium hydroxide in a bag is reasonably effective. 5-Additional reagent should be added from time to time by the foregoing method as may be necessary to maintain an alkalinity approaching the maximum for the brine involved as indicated in Figure 1. 6-Undue contact between brine and air should be avoided.
Acknowledgment The author wishes to acknowledge the valuable criticisms and suggestions made by J. H. Kaiser, Technical Service Dept., The Solvay Process Co., Syracuse, N. Y.; F. N. Speller, Metallurgical Engineer, The National Tube Co., Pittsburgh, Pa.; and A. C. White, Technical Research Dept., Dow Chemical Co., Midland, Mich.
Cotton Textile Mill to Be Built in Brazil A concession has been awarded for the erection of a textile mill in a city in Brazil which will use cotton waste and other cotton residue as raw materials. The concession includes the exemption from all state taxes for a period of five years and a 60 per cent reduction in the state export tax.
