Sept ., I 9 I 7
T H E J O l - R - Y d L O F I N D U S T R I A L A N D EiYGIiVEERING C H E M I S T R Y
the simplicity of its operations and the low cost of plant construction; and that a furnace which I believe I see in embryo can be developed which will be much more efficient than either of those now used. The process is so promising that I recommend I-That active experimentation on a large scale be conducted. 2-That a sum not to exceed $zoo,ooo be set aside for this purpose. With this amount available I feel confident that this process can be put upon a commercial basis; that it will become a real competitor in the production of ammonia for nitric acid and of nitrogenous material for fertilizer. I believe this investigation should begin without delay and that as soon as practicable a small experimental plant be erected a t Saltville, Va., where a large supply of nitrogen, soda, and coal is available. The present plant of the Xitrogen Products Company can probably be utilized in connection therewith. S U M M A R Y OF R E C O M M E N D A T I O N S
I-That S3,j00,000 be made available to build an initial plant which will produce 60,000 pounds of ammonia per day by the synthetic ammonia process, as offered by the General Chemical Company. 11-That the offer of the General Chemical Company be accepted with some subsidiary arrangement whereby a maximum royalty per ton of nitrogen, when the product is to be used for commercial purposes, shall be inserted. 111-That the construction of the initial plant be started at once at some point to be selected by the War Department in southwest Virginia or adjoining territory in West Virginia, reasonably near to the sulfur, sulfuric acid, and coal supplies of that region. The plant should be so situated that it is near
84 I
to plenty of good water and that the land is available for the later erection of an ammonia oxidation and nitric acid concentration plant. It should be so located that a powder plant may be later erected near-by. ITr-That a sum not to exceed ~ 2 0 0 , 0 0 0be set aside for active experimentation on a large scale on the Cyanide process. V-That experimentation on the Cyanide process be conducted a t Saltville, \-a,, where nitrogen, soda, and coal are available and where the present plant of the Nitrogen Products Company may be studied and utilized. E S T I M A T E S ON C O N S T R U C T I O N AND O P E R A T I N G COSTS
In order that the recommendations made above may be considered in comparison with the older processes now operating on a large scale, I beg to submit herewith a table summarizing confidential data obtained from books of many companies bearing upon the cost of nitrogen production. DATA PER T O N O F NITROGEN-BY THE ARC, C Y A K A M I D . HABER GENERALCHEMIC.4L C O M P A N Y PROCESSES PRODL-CT ...... ... .... Power required.. . . . . , Investment.. , . , , , . . , , Operating. costss. . . . . PKomcr.. . . , , . . . , . . . Power., . . . . , , , , . . . . . Investment 3 . , , . , . . . Operating costsP.. . . . . .
.
.
AND
CYAKAMID HABERGEN. C H E M . ~ 3 NH3 NHs XH3 10.5 2.2 0.2 0.2 S1410(a) $540 $300 $440(a) I70 150(b) 119 97 96% H X O ~ 96%'HN03 967,HXOa 9 6 % H N 0 3 IO. 8 2.3 0.3 0.3 S 1550 ;$io $570 $530 220 10 239 217
ARC 35% " 0
1 Estimates on General Chemical Co. process are based on present war time construction costs. All others on normal prices. 2 Amortization for cyanamid a s charged by operating companies. Amortization for Haber 20Y0 of plant cost for repairs. interest. depreciation, Amortization for Arc and Modified Haber 121/%%interest and depreciation. $5.00 per ton of product for repairs. 3 Except for Arc process, includes ammonia plant a5 given A , power additional $10, oxidation and absorption S140; concentration $40, steam plant, $40. 4 Except for Arc process. includes ammonia costs a s given; oxidation $50; concentration $70. No allowance made for unoxidized ammonia. ( a ) Power plant investment reckoned a t $100 per horse power. ( b ) Cyanamid production $122, ammonia from cyanamid $28. total $150.
ORIGINAL PAPERS THE INFLUENCE OF SUPERIMPOSED ALTERNATING CURRENT ON THE ELECTRODEPOSITION OF NICKEL By S. A. TUCKER A N D H. GEORGEL o E s c ~ Received June 2, 1917
T h e electrolyte generally used for nickel-plating is a solution of nickel ammonium sulfate, neutral or slightly acid with a weak acid such as boric, tartaric or citric; i t may also contain alkali salts of these acids. Nickel deposits formed in nickel ammonium sulfate electrolytes are harder, smoother a n d more durable t h a n those from chloride electrolytes.1 Since t h e solubility of nickel ammonium sulfate (soluble in 1 2 parts of water a t z o o C. a n d in j parts water a t 50' C.) limits t h e concentration of nickel in t h e electrolyte and prevents t h e use of high current density, rapid plating solutions have been introduced which, on account of their greater concentration of nickel salt, can be worked a t a higher current density. T h e solution of 0. P. W a t t s , 2 consisting of 1 2 parts of nickel sulfate, I p a r t nickel chloride and I p a r t of boric acid, can be worked a t a density of 2 0 0 t o 300 amp. per sq. f t . a t 7 0 ' C. Hogaboom, in t h e discussion of this paper, says t h a t what is known as white nickel deposit cannot be obtained in h o t solu1
E. F. Kern a n d F . P. Fabian. School of Mines Quarterly. No. 4,29,343.
f
Trans. A m . Eleclrochem. SOC.,1 9 (1916), 395.
tions, as t h e white in t h e deep parts has a tendency t o t u r n yellow, and t h a t fast nickel-plating is not entirely satisfactory, since the solution becomes alkaline so rapidly t h a t i t gives a dull deposit. As soon as t h e solution becomes alkaline, t h e deposit becomes dull, while if t h e solution is on t h e acid side, t h e deposit is usually brittle and does not adhere. T h e use of nickel ammonium sulfate as t h e electrolyte necessitates t h e use of impure anodes, for anodes of pure nickel do not corrode properly b u t become passive, causing changes in t h e composition of t h e b a t h a n d t h e addition of nickel in t h e form of a soluble nickel salt t o bring u p t h e concentration of nickel in t h e depleted bath. 0. W. Brown1 has shown t h a t in nickel ammonium sulfate electrolyte, electrolytic nickel anodes dissolve very poorly and rolled anodes are no better t h a n electrolytic anodes; cast anodes dissolve with higher current efficiency, a n d smooth cast anodes dissolve with poorer efficiency t h a n cast anodes roughened in acid; t h e presence of copper in a nickel anode, rather t h a n being a detriment, seems t o be advantageous in allowing a higher anode current density t o be used. T o cause good anode corrosion, commercial nickel anodes may contain iron, t i n a n d carbon. Calhane 1
Trans. A m . Electrochem. Soc.. 1(1903), 86.
84 2
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Vol. 9, No. g
a n d Gammagel analyzed commercial anodes from two carbon a n d iron. The electrolytic nickel contained different sources and found 7 . 5 7 and 7 . 5 2 per cent iron g g . 8 per cent nickel. T h e effective anode area was in t h e m with 9 2 per cent nickel; t h e metal deposited 5 t o 6 sq. in. f r o m these anodes contained from 0.07 t o 0 . 7 5 per Copper cathodes were used ( 5 sq. in. effective area) : cent iron. Mathers2 gives t h e following composi- these were cleaned in nitric acid, washed in hot a n d tion of commercial anodes: Ni 95, Sn 2. 5, Fe 1.0, then cold water, dipped in alcohol a n d dried over a impurities I . 5 per cent. flame, cooled and weighed. After t h e completion of T h e objections t o t h e use of commercial cast nickel a run t h e cathodes a n d t h e anodes were washed i n anodes have been well summarized b y Mathers. hot a n d then cold water, dipped in alcohol, dried over I n t h e ordinary nickel b a t h , iron is deposited on t h e a flame, cooled and weighed. cathode along with nickel a n d p a r t of it is oxidized A neutral solution of C. P. nickel a m m o n i u m sulb y t h e air t o a basic salt which goes into t h e sludge. fate, 7 5 g. per liter, was used as t h e electrolyte. A Ammonium citrate prevents sludge formation. The fresh sample of electrolyte was used in each experianalysis of dried sludge (using ferro-nickel anodes) ment. T h e electrodes w e r e suspended in t h e b a t h gave 39 per cent Fez08 a n d 8 per cent sulfate. If I in. apart. t h e cathode reaches into this sludge, t h e finished plate I-DIRECT CURRENT ALONE has a frosted appearance similar t o a deposit on imT h e cells (300 t o 3 5 0 cc. capacity) containing t h e properly cleaned work. M a n y commercial deposits different anodes were connected in series in a circuit contain 3 per cent or more of iron, when t h e anodes contain 6 t o 8 per cent Fe.a T h e rest of t h e iron containing an ammeter, copper coulombmeter, a n d goes into t h e sludge. Ammonium citrate keeps all variable resistance. T h e anode a n d cathode efficient h e iron in solution and, therefore, gives a deposit cies a t different current densities were determined. containing approximately as much iron as was in t h e T h e results are given in Table I. TABLEI-RESULTS WITH DIRECTCURRENTALONE anode; e. g., from a n anode with 6.49 per cent iron a Current Densities given in Amperes per sq. ft. deposit containing 6 . 2 3 per cent iron was obtained Time of Run, 1 hour. Efficiencies in Percentages CURRENT when citrate was in t h e b a t h , a n d when no citrate DENSITY EFFICIENCYCHARACTER was present t h e deposit contained. only 3.3 I per cent. NICKELANODE Run No. Anode Cathode Anode Cathode OF DEPOSIT T h e presence of iron in t h e deposit is one of t h e chief Roughened Cast .... 1 5.76 3.60 102.43 98.92 Good 2 11.50 9.60 94.76 99.38 Good causes of t h e d a r k or bluish color. 3 17.10 14.30 82.50 95.04 Slightly burned 19.00 86.00 97.45 Burned Obviously t h e use of p u r e nickel anodes is desira- Smooth C a s t . , . . .. 41 19.00 5.76 3.60 57.51 95.61 Good 2 11.50 9.60 62.23 91.55 Good ble, provided they could be made t o corrode properly. 3 17.10 14.30 42.30 83.98 Good W i t h pure anodes better color of deposit is obtained, 4 19.00 19.00 53.70 79.67 Slightly burned 3.60 3.60 5.01 87.30 Good greater range of conditions without dark or bad deposi- Rolled .......... , , 21 7.80 9.60 1.76 76.70 Good 3 10.80 14.30 3.55 69.70 Good . tion is possible a n d t h e composition of t h e b a t h is 4 19.00 19.00 1.38 75.00 Good more easily maintained constant. Baths using pure Electrolytic: Sand.blasted.... 1 8.90 8.90 27.40 92.90 Good nickel anodes a n d a chloride such as nickel chloride 8.92 70.30 Good 2 16.40 16.40 8.90 50.60 99.60 Good Smooth-ground. 1 8 .90 t o secure anode corrosion has been tried out a n d 2 16.40 16.40 26.50 69.20 Good ad~ocated.~ It was thought b y t h e authors of this paper t h a t ROUGHENED CAST NICKEL ANODE-This anode was pure nickel anodes could be made t o corrode properly roughened in nitric acid (I : I) a n d washed in h o t in ammonium sulfate solution without t h e addition a n d t h e n cold water. At 5 . 7 6 amp. per sq. ft. t h e of other chemicals b y superimposing an alternating corrosion is 102.43 per cent: t h e excess over IOO per current on t h e direct current during electrolysis. cent is due t o t h e mechanical separation of anode T h e corrosion of nickel anodes in nickel ammonium particles during t h e corrosion. At 17. I a m p . per sulfate solution was studied: (I) when D. C. alone, ( 2 ) sq. f t . t h e anode efficiency dropped t o 8 2 . 5 0 per cent when both D. C. a n d A. C., (3) when A. C. alone a n d a t 19 amp. per sq. f t . rose t o 86.00 per cent; t h i s passed through t h e solution. T h e current efficiencies increase in efficiency of R u n 4 over R u n 3 may be a t anode a n d cathode were determined in each case a t t r i b u t e d t o mechanical disintegration of t h e anode, b y t h e loss in weight of anode a n d t h e gain in weight since corrosion of nickel anode decreases with increase Considerable sludge formed of cathode, respectively, a copper coulombmeter in of current density. during each run. t h e circuit measuring t h e coulombs used. SMOOTH CAST NICKEL ANODE-This anode Was T h e nickel anodes used were: roughened cast nickel, smooth cast nickel, rolled nickel, a n d electrolytic ground smooth on a carborundum wheel. T h e slight nickel (courtesy of International Nickel Company). increase in anode efficiency in R u n 2 over R u n I is Analysis of t h e commercial case anodes showed t h e due perhaps t o increased surface caused b y previous following composition: nickel 91.87, iron 6 . IO, and corrosion in R u n I. T h e anode was re-smoothed on carbon I. 63 per cent. T h e rolled nickel, tested quali- a carborundum wheel a n d R u n 3 was made, resulting tatively, showed t h e presence of a small amount of in anode corrosion of 4 2 . 3 0 per cent. I n R u n 4, t h e efficiency rose again. Sludge formed in each run. 1 J . A m . Chem. Soc., 49 (1907). 1268. 2 Trans. Am. Electrochem. Soc., 49 (1916), 383. ROLLED NICKEL ANoDE-In R u n I t h e rolled nickel a Bancroft, I b i d . , 9 (1906), 217. had a smooth surface. At t h e low D. C. of 3.6 amp. 4 See Mathers, LOG.cit.; Bancroft, LOG.cif.; L. D. Hammond, Trans. per sq. ft. t h e corrosion was very poor, only 5.01 A m . Electrochem. SOC..September, 1916.
Sept., 1917
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
p e r cent. I n R u n 2 t h e anode efficiency decreased. T h e anode was t h e n dipped i n nitric acid (I : I ) , washed with hot a n d t h e n cold water, a n d used i n R u n 3, this t r e a t m e n t causing t h e anode efficiency t o rise. I n R u n 4 t h e efficiency dropped again. T h e solution after each r u n was clear a n d acid t o litmus paper. It is t o be noticed t h a t t h e effect of using rolled anodes is t o decrease t h e cathode current efficiency. E L E C T R O L Y T I C N I C K E L ANODE-The Corrosion Of electrolytic nickel when sand-blasted a n d when ground s m o o t h was studied under t h e influence of t h e continuous current. After each r u n t h e anodes were brown, t h e solutions clear, a n d t h e deposits good. R a p i d gassing occurred at both anodes, more so i n R u n 2 t h a n i n R u n I. There was slight gassing at t h e cathodes in R u n I , which increased considerab l y i n Run 2 . Curiously, t h e sand-blasted anode gave much lower efficiency t h a n t h e smooth anode, which is cont r a r y t o what one would expect, since t h e sand-blasted anode exposes actually a greater surface t h a n t h e s m o o t h anode. 11-EFFECT
O F SUPERPOSITION
OF
A. C. ON D. C.
T h e a p p a r a t u s arrangement shown i n Fig. I was used a t first. T h e A. C. used throughout was t a k e n f r o m a I I O volt lighting main of 60 cycles per second. a.CAmn,of.r
R V
843
t h e circuit only t o a certain extent, beyond which t h e value of t h e D. C. would rise t o a current density unsuitable for nickel-plating. After a few runs were made with this arrangement, i t was abandoned a n d t h e flexible set u p shown i n Fig. I1 was used, t h e A. C. a n d t h e D. C. being connected i n multiple. By this arrangement t h e alternating curr e n t could be regulated b y resistance R,, without affecting t h e direct current. B y means of resistance Rz t h e continuous current of proper density was obtained. T h e voltage across t h e cells was t a k e n ( I ) with a D. C. voltmeter when both A. C. a n d D. C. were flowing; ( 2 ) with t h e D. C. voltmeter when D. C . alone flowed i n t h e circuit; a n d (3) with a n A. C. voltmeter when t h e A. C. alone flowed. T h e voltage readings are b u t indicative a n d not accurate, due t o variations caused b y anode impurities, anode idiosyncrasies a n d changes in distance between electrodes. T h e current density of t h e continuous current i n all t h e runs was kept at or a b o u t 8 . 7 0 a m p . per sq. ft. while t h e density of t h e alternating current was varied. The results are given in Table 11. TABLE 11-RESULTS
WITH ALTERNATING CURRENTSUPERPOSED ON DIRECT CURRENT Current Densities Given in Amperes per sq. f t . Time of R u n , 1 hr., except those marked which were 2 hrs. CURRENT -VOLTS--PER CENT Run DENSITY A.C. D.C. A.C. EFFICIENCY NICKELANODENo. D.C. A.C. 8rD.C. ( a ) (b) Anode Cathode Roughened Cast 1 8.70 4.35 2.52 2 . 5 7 1.17 108.20 105.00 2 8.10 8.70 2.49 2.60 1 . 2 2 112.00 102.60 3 8 . 7 0 14.40 2.25 2.40 1.25 107.40 102.50 4 8 . 7 0 20.80 2.33 2.72 1.55 111.20 101.50 5 14.40 44.64 2.30 2.90 3.10 123.30 100.20 6 14.40 66.25 0.95 1.50 4.00 121.00 102.70 Smooth Cast. 1 9.95 7.33 1.50 1 . 7 0 0 . 5 0 84.33 96.73 2 9.50 91.50 7.85 1.50 1.65 0.55 93.00 3 8.70 14.40 2.40 2.60 1.25 99.80 102.90 4 8.70 28.80 2.40 2.50 1.85 101.20 98.00 5 14.40 44.64 2.60 3.05 3.10 103.30 101.00 6 14.40 66.25 1.00 1.50 4.00 118.00 100.50 1 Rolled.. 9.95 7.33 2.95 3.05 0.75 2.83 76.00 8.78 3.10 3.20 0 . 8 5 3.59 75.50 2 10.30 9.05 88.20 3 12.00 17.30 3.10 3.20 1.30 8.70 20.80 2.70 3.11 1.60 84.00 4 22.10 88.30 8.70 24.50 2.65 3 . 0 0 1.60 98.70 5 8 . 7 0 28.80 2 . 3 0 2.90 2.10 97.20 6 94.50 8 . 7 0 28.80 2.20 2.92 1 . 9 7 7 98,OO 100.70 8 14.40 44.64 2.50 3.15 2.90 101.20 100.80 9 14.40 66.25 1.00 3 . 1 0 4.00 105.40 101.00 8.70 41.80 1.72 2.85 2.52 100.50 101.50 10 Elcclrolytic: 1 Sand-blasted. 8.93 52.4 1.50 2.85 3.10 104.50 99.60 2* 8 . 9 3 5 0 . 4 0 . 9 0 1.40 4.10 109.60 Smooth-ground 1 8.93 52.4 1.67 2.72 2.60 105.00 99.40 2* 8.93 5 0 . 4 0.80 1.20 2.60 110.80
*
.
ACAmrrutor
.... .. .
A.C.
'R
...
....
....
ANODE-A comparison of t h e results with this anode a n d those i n Table I shows plainly t h a t t h e A. C. superimposed on t h e D. C. R O U G H E N E D CAST NICKEL
FI G . ~ I
Ly
ms.
In t h e diagram only t h e A. C. flows through t h e circuit when switches T a n d N are closed a n d M a n d S a r e open. When M a n d S are closed a n d T a n d N open, only D. C. flows. With S a n d T closed a n d M a n d N open, both A. C. a n d D. C. flow through t h e circuit. Any change i n resistance obtained b y means of R a n d Rv affects t h e value of both t h e D. C. a n d t h e A. C. at t h e same time. T h u s t h e alternating current a n d therefore t h e A. C. voltage drop across each cell could be increased b y decreasing t h e resistance i n
causes increased corrosion which is more pronounced t h e higher t h e density of t h e A. C. a n d hence t h e higher t h e A. C. voltage across t h e cell. I n all t h e runs there was slight gassing a t both electrodes. Considerable sludge formed during a run. S M O O T H CAST N I C K E L ANODE-Here t h e increase i n corrosion of t h e anode due t o superimposing A. C. on D. C. is marked. With D. C. alone (see Table I) a t a density of 1 1 . j o a m p . per sq. ft. t h e corrosion was 62. 23 per cent. With both A. C. a n d D. C. t h e corrosion rises quite rapidly with increase of t h e density of t h e A. C. till a t 66.25 amp. per sq. f t . t h e corrosion is 118.00per cent. T h e surface of t h e anode, however, becomes rougher after each r u n a n d adds its effect also. There was slight gassing a t b o t h electrodes during each run, a n d t h e greater t h e corro-
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
844
CURREXT USEDAND TIME:
[
.
CURRENT amperes per sq. f t .
TABLE111-RESULTS WITH ALTERNATING CURRENT ALOxE A : 1 . 3 0 amperes and 1 hour B: 0 . 2 5 amperes and 1 hr. 3 min. CELL 1 CELL 2 CELL 3 CELL 1 CELL 2 CELL3 Electrolytic Nickel Rolled Nickel Copper Coulombmeter Electrolytic Nickel Rolled Nickel Copper Coulombmeter . . . . . . . . . . 22:5 Rough Smooth 37. Rough Smooth 5 5 22:s 37. sqm. sq. in. 5 sq. in. 5 sq. in. sq. in. sq. in. sq. in. sq. an. 37.4 37.4 37.4 37.4 8.32 5.06 7.2 7.2 7.2 7.2
,
..............700gallons. If t h e sewage and sludge flowed through all parts of Survey a t t h e University of Illinois. t h e settling chamber i t would have a retention period COKSTRUCTION A S D OPERATIOS OF COKTINUOUS-FLOW of 24, 31 and 37 minutes, with a flow through t h e PLAKT In aeration chamber of 4 j j and 6 hrs., respectively. T h e continuous-flow plant which was p u t in opera- order t o assist t h e settling of t h e sludge t h e liquid tion during t h e summer of 1916 was expected t o handle passes down into t h e center and u p around t h e edge of a 2 0 0 , 0 0 0 gallons of sewage a n d sludge per d a y and TTas hollow frustrum of a pyramid and overflom-s into built in a septic t a n k designed b y Prof. A. N. Talbot drains which entirely surround t h e settling chamber. in 1897 for t h e City of Champaign. T h e t a n k was reFrom t h e settling chamber t h e effluent flows over a constructed for t h e activated-sludge process. T h e weir and is either returned t o t h e sewer or discharged plant contains a screen chamber a n d pumping p i t , a into a pond, formed by t w o dams thrown across t h e grit chamber, a n aerating chamber, a settling chamber, abandoned bed of a stream. This pond covers about a blower room and a laboratory containing sludge- o I of an acre and has a maximum depth of 3 ft. drying apparatus (see Fig. I ) . A sludge-drying bed T h e sludge is withdrawn from the settling chamber a n d a pond into which t h e effluent from t h e process by an air-lift and can be discharged a t t h e place where may be discharged are also provided. T h e sewage is t h e raw sewage enters t h e aeration chamber or be drawn from t h e main outlet sewer from t h e City of diverted for experimental purposes or discharged into Champaign. T h e daily flow is estimated t o be from t h e sewer. Air is supplied for aeration a n d for t h e I , O O O , O O O t o I , joo,ooo gallons, though in wet weather, air-lift b y a rotary positive pressure blower, having owing t o seepage into t h e sewers, t h e amount of flow a rated capacity of 300 cu. ft. per minute, driven by is greatly increased. T h e manhole nearest t h e septic a 15-H. P. electric motor. T h e air is filtered through t a n k was modified t o serve as a screen chamber and cheesecloth spread over a box having sides of wire 1 Read at the Buffalo Meeting of the American Institute of Chemical netting, and is measured through a lTenturi meter. Engineers, June 20, 1917 The plant was operated from M a y 2 5 t o June 1 1 , 2 THISJOURNAL, 7 11915). 3 1 8 , 8 (1916), 15, 1 7 , and 646.
111-The increased corrosion a t t h e anode raises t h e current efficiency a t t h e cathode, particularly with rolled nickel anodes. IY-Corrosion in general with direct current or with superimposed A. C. is markedly affected b y t h e mechanical nature of t h e metal. V-Alternating current alone has b u t slight corrosive effect a t the anode.
