I/EC
Corrosion
Reinforced Resin Defeats by AI Calderone,
Carborundum
Metals Co.
W h e n p o l y e s t e r - b o n d e d glass w a s u s e d i n s t e a d of l i n e d steel in v e n t i l a t i n g e q u i p m e n t f o r a z i r c o n i u m process • Total cost was less than for the original installation • Total weight was only 2 5 % as much. Thus, installation required no r i g g i n g equipment or other mechanical help • Corrosion-resistance performance was satisfactory, where that of steel was not
M
IODERN METALLURGY poses new corrosion problems as it solves enduse problems. Take the case of producing zirconium. This element was first made commercially at the Akron, Ν. Υ., plant of Carborundum Metals Co., a division of Carbo rundum Co. Processing the zircon ore demands unconventional chemi cal methods. These form extremely corrosive vapors which attack both the insides and outsides of processing equipment and buildings, if not properly exhausted. The special processing techniques, initially developed by the U. S. Bureau of Mines, were improved and commercialized by Carborundum. Initial step in the recovery operation involves putting a mixture of petro leum coke and zirconium-sand con centrate into a arc furnace. This produces zirconium carbonitride, a crude form of ZrC, which reacts exothermically with gaseous chlorine in a water-jacketed vessel to form crude zirconium tetrachloride. This ZrCh feeds into a liquid-liquid ex traction operation (in an aqueous mixture of hydrochloric acid and hydrothiocyanic acid) followed by haf nium extraction in methyl isobutyl ketone. Sulfuric acid addition pre cipitates the zirconium from solution as pentazirconyl sulfate. Calcining then gives hafnium-free zirconium oxide. Lampblack added to the zirconia forms a mix for briqueting; the briquets undergo a second chlorina64 A
tion, not exothermic, where heated vessels raise the temperature to 900° C. to produce purified ZrCU. This undergoes a Kroll-type reduction with metallic magnesium. Vacuum distillation removes the resulting magnesium chloride, leaving purified zirconium sponge ready for crushing, inspection, and packaging. Corrosion Inside a n d O u t
When design work started back in 1952 for the initial Carborundum Metals plant in Akron, problems of both internal and external corrosion were foreseen from several sources in the process. For one thing, some chlorine unavoidably escapes during the two chlorination operations and the necessary mechanical handling of crude zirconium salts. T o combat this, off-gases from the chlorinations pass through a wet scrubber. This minimizes atmospheric pollution by effectively removing most of the chlorine from exhaust fumes; also it salvages traces of zirconium. Greatest source of corrosive fumes, though, is the ZrCli itself. Hygro scopic, it hydrolyzes rapidly when exposed to air-borne moisture. Dense fumes of hydrochloric acid form to attack buildings and equip ment as well as to create a personnel
Resin-bonded glass f i b e r is used in the l a b o r a t o r y h o o d system a t C a r b o rundum's A k r o n , Ν. Υ., plant
INDUSTRIAL AND ENGINEERING CHEMISTRY
hazard. T o counter this, an elab orate induced-draft system was planned for general building ventila tion. Nine years ago, Carborundum considered reinforced plastics for the ventilating equipment for this process. But then they were new as materials of construction—and ex pensive. At that time, a premium price put this product on a par with glass-coated metal. So the firm decided to use a ventilating system made mostly of mild steel, protec tively coated inside and out with bituminous paint. Wood was used successfully for some hood con struction. Carborundum's engineers had considered other materials, in cluding stainless steel, and a number of plastics for the plant, but found them uneconomic or inadequate on the basis of mechanical strength or corrosion resistance. After start-up, however, corrosion difficulties—chiefly from HC1—soon
Corrosive Fumes became apparent. Internal surfaces of process equipment were attacked most, but the outsides suffered too, and even the building structure rusted. Alter 11 months of operation the bad news was decisive : Lined steel is unsatisfactory for ventilating equip ment in this process. Λ large duct had disintegrated almost completely. Fan housings and wheels were in very bad shape. Steel supports to the ductwork as well as fastenings, ties, and rings, for the ductwork— had corroded. Reinforced Polyester Tests Best
Then, in 1954, test elbows and pipe sections of polyester-bonded glass fiber replaced deteriorated coatcd-metal pieces in a particularly troublesome section near the chlo rination operations. Almost at once the new material proved its supe riority. Essentially homogeneous, the
reinforced resin could stand up equally well to corrosive attack from the outside as well as the inside of flues and housings. And, very im portant, the price of this type of material had dropped considerably from its level of a year or so before. As replacement had become ur gent, anyhow, Carborundum Metals found it economical to use the re inforced resin for replacing most of the ventilating ductwork, hoods, and fans. The resin material then found its way into ventilating equipment in other areas which had suffered slower corrosive attack, including the laboratory hood system. By this time the price of resinbonded glass fiber had dropped con siderably, so that the replacements actually cost less than the original installation. All of these replacement items have withstood the severe corrosion damage of the plant opera tion. And equipment of the roofs of processing buildings has resisted the
Fan and duct at Akron, Ν. Υ., are shown (above). Fume scrubber (below) handles chlorine-containing off-gases at Parkersburg, W. Va., plant
Chlorination section presents a difficult corrosion problem, solved by using reinforced polyester material for flues and housings "ψ
VOL. 53, NO. 3
·
MARCH 1961
65 A
316 STAINLESS STEEL Welded
BOURDON TUBE Incorporated In This New Series
MERCOID PRESSURE CONTROLS
S E R I E S D - 4 1 , 2 4 3 , 541 316 stainless steel Bourdon tube and pressure connection. All parts in contact with pressure media are of 316 stainless steel. Has outside adjustments. V i s i ble calibrated dial, and hermet ically sealed mercury contact. Internal mechanism is nickel plated. Available in operating ranges from 30" vac.-75 psig. up to 100-1000 psig., with varying dif ferentials and electrical capac ities to meet your application.
CORROSION added effects of weather and direct sunlight. L i g h t w e i g h t Ducts f o r N e w P l a n t , Too
Though not as resistant to me chanical shock as metal or wood, and restricted to maximum operat ing temperatures of about 120° C. in this application, resin-bonded glass fiber does show other advantages. Its light weight and its availability in prefabricated sections are valuable "plus factors." Weighing only 2 5 % as much as the lined steel they replaced, many of the units could be installed without need for rigging equipment or other mechanical help. Where the original supporting steel could be used, maintenance men merely lifted the units into place by hand, closed the flange joints, and tightened the hangers. Where necessary, they performed simple field "welding" to join prefabricated sections together. The light weight of the glass-fiber reinforced material permitted re duction in size and number of the supporting members. A coating of plain resin solution, to reduce further corrosion of the steel members and tie bolts, has greatly cut down re placement of these support structures. This polyester solution also greatly extends the life of wooden hoods. When Carborundum Metals de cided to build another zirconiumhafnium production plant at Parkersburg, W. Va., the same high level of corrosion threatened. Glass-fiberreinforced polyester resin—mostly from du Verre, Inc. (Arcade, Ν. Υ.), which had helped Carborundum solve its earlier corrosion problems— was specified for the entire initial ventilation system in this new plant. The service history here, as at Akron, continues to emphasize the benefits of resin-bonded glass fiber for this severe type of corrosive environment.
THE MERCOID CORPORATION 4209 BELMONT AVE., CHICAGO 41, ILL
Semi-Commercial {Pilot Plant Quantities)
METHYLETHANOLAMINE 2178 CH3NHC2H4OH
Mol. Wt. 7 5 . 1
Sp. gr. @ 2 0 ° C . — 0 . 9 4 9 5 % distills between 155-165°C.
METHYLDIETHANOLAMINE 2146 CH 3 N(C 2 H40H) 2
Mol. Wt. 119.1
Sp. gr. @ 2 0 ° C . — 1 . 0 4 9 5 % distills between 2 4 0 - 2 5 5 ° C .
ETHYLETHANOLAMINE 1111 C 2 H s NHC 2 H 4 0H
Mol. Wt. 89.1
Sp. gr. @ 2 0 ° C . — 0 . 9 1 IBP 1 6 0 ° C ; FBP 1 7 0 ° C .
ETHYLDIETHANOLAMINE 1108 C2HÎN(C2H4OH)2
Mol. Wt.
133.1
Sp. gr. @ 2 0 ° C . — 1 . 0 1 IBP 2 4 6 ° C ; FBP 2 6 0 , , C .
1-DIMETHYLAMIN0-2-PR0PAN0L 2445 (CH 3 ) 2 NCH 2 CHOHCH 3 Mol. Wt. 103.2 Sp. gr. @ 2 0 ° C . — 0 . 8 5 9 5 % distills between 121-127°C.
Technical liferafure and samples available on request.
PENNSALT CHEMICALS CORPORATION Three Penn Center · Philadelphia 2, Pa.
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ALKYL ALKANOL AMINES
Market Development Dept. · Industrial Chemicals Division
Three case styles: General Pur pose N E M A 1 ; Weather-Proof N E M A 1A, 2, 3, 4; ExplosionProof Class 1 Group C , & D; Class 2 Group E, F, G , N E M A 7, 9, 9 A . W R I T E FOR B U L L E T I N 019
PENNSALT
INDUSTRIAL AND ENGINEERING CHEMISTRY
Pennsalt Chemicals ESTABLISHED 1850 Circle No. 29 on Readers' Service Card
