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Publication numberUS2541901 A
Publication typeGrant
Publication dateFeb 13, 1951
Filing dateOct 26, 1944
Priority dateOct 26, 1944
Publication numberUS 2541901 A, US 2541901A, US-A-2541901, US2541901 A, US2541901A
InventorsClarke William W, Zademach Erich R
Original AssigneeMetalwash Machinery Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pickling of aluminum
US 2541901 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Feb- 13, 1951 E. R. zADEMAcH Erm. 2,541,901

PICKLING OF ALUMINUM Filed Oct. 26, 1944 y Patented Feb. 13, 1951 PICKLING F ALUMINUM Erich R. Zademach, Hillside, and William W. Clarke, Summit, N. J., assignors to Metalwash Machinery Company, Irvington, N. J a copartnership Application October 26, 1944, Serial No. 560,490

This invention relates to a novel method of pickling aluminum and its alloys. Aluminum sheet, when rolled, becomes work hardened and roughened upon the surface; and it may also become oxidized and have small particles of dirt or other foreign material rolled into the surface. In order to obtain a bright or so-called mirror finish, as for sheets intended for use in reiiectors, it is necessary to remove this surface prior to the iinish ro'ling of the material.

It is customary, moreover, to etch the surface of rods, bars, castings, forgings and extrusions to remove the surface layer and thus reveal any ssure or other flaws which may have been produced during the washing of the parts and which would otherwise be concealed by the deoxidized surface of the metal.

This has been done in the past by dipping the 1 Claim. (Cl. 134-3) aluminum sheets, bars, rods, etc. in a tank containing a 5 to 20% caustic solution at temperatures ranging from 160 .to 210 degrees F.. and allowing them to remain there for from 5 to 20 minutes. This dissolves from .001" to .008" of the surface and leaves the parts covered with a thick, black slime of sodium aluminate,

The parts are then rinsed in a tank of water and immersed in a tank of cold nitric acid ranging anywhere from to 50% in strength. The nitric acid dip removes the sodium aluminate and leaves the metal in a bright condition with a matte or etched surface, after which the parts are rinsed in a tank of warm water and allowed to dry from their own heat.

This treatment has not been completely satisfactory, particularly in the treatment of sheet material, as any water remaining on the sheet produced a stain, which stain is elongated in the subsequent rolling and mars the otherwise mirror finish of the piece.

In the present invention the caustic, the rinses and the nitric acid are sprayed on the aluminum. This produces a very uniform removal of the aluminum. Moreover, the force of the sprays prevents the formation .of a sodium aluminate coating on the sheet, thus exposing the surface of the metal continuously to the action of the solution, thus shortening the time required for the removal of a given' thickness of metal by a very substantial margin and making it possible, moreover, to use a much lower concentration of nitric acid, thus reducing the consumption thereof. After the'flnal water spray the aluminum sheet is subjected to cold and hot blasts of air, in succession, and thereupon emerges from the machine in a dry stain-free condition.

mately 160 to 200.

One object of the invention is to provide an improved method of pickling aluminum.

Another object of the invention is to provide an improved method of treatment of aluminum sheet.

Another object of the invention is to provide a method for pickling aluminum by which the nitric acid consumption will be reduced, and the time of operation will be substantially diminished.

Other and incidental objects of the invention will be apparent to those skilled in the art from a reading of the following specication and' an inspection of the accompanying drawings in which:

Figure l `is a schematic plan view of our im proved machine; and

Figure 2 is a schematic sectional elevation taken on the line 2-2 of the machine of Figure 1.

Figure 3 is a longitudinal section through the I2 on a track II through a, casing generally indicated at I0. Appropriate sprays I4 are located at both sides of the path of the material so that all surfaces of the material are uniformly treated. The aluminum rst enters thecompartment A where it is sprayed with a 10% solution of sodium hydroxide at a pressure at an average of about 20 to 25 pounds and a temperature of approxi- 'Ihis treatment removes approximately .001 inch per minute of the surface of the aluminum. The removal is almost as precise as a machine operation and, in addition, the

lforce of the sprays removes the sodium aluminate which is formed. From the compartment A the aluminum passes along the track into the compartments B and B' where it is sprayed with water to remove the caustic solution. The rst washing is done in compartment B and since this is the first rinse and accomplishes the preliminary removal of the sodium aluminate, this water is then discharged. The water in the rinse tank B is recirculated. The sheet then passes to the compartment C where it is sprayed with nitric acid in a concentration of between 10% and 15% at a temperature of about F. Then the sheet passes to compartments D and D' where it is given the nal cold water spray. The rinse section D is supplied with cold water recirculated by the pump F from the tank E, and a portion of this water is transmitted to the rinse section B to supply a, suicient quantity of water in that section. The rinse section D is supplied with fresh water from the supply line indicated, so that when the aluminum emerges it has been rinsed with fresh water. The water from the section D returns to the tank E and thereafter it is recirculated through the rinse section D.

The supply of water to section Dv can be regulated to equal approximately the quantity 'discharged into the sewer from section B. After the sheet emerges from the compartment D', the sheet passes into the dryers. The rst dryer I is a cold blast dryer where the air preferably at a pressure of 11/2 lbs. is blown into the sheet from the nozzle pipes 48 indicated in Figure 3. This air is supplied by the turbo-blower 45 and the pipes 48 are preferably located diagonally to the sheet so that they blow drops of water back and down rather than spreading the drops. The sheet then passes into the hot blast dryer J which is supplied with air by the turbo blower 46 and the heater 41 which removes the remaining water.

Due to the fact that the sodium hydroxide spray removes most of the sludge formed, the nitric acid spray is not required to be long continued and it does not require a high percentage of acid, thereby considerably decreasing the quantity of acid used as compared to the previous tank method.

A certain amount of sodium aluminate sludge accumulates in the caustic solution, and this sludge is removed and the caustic solution recovered as described in our concurrently led application Serial No, 560,491, led October 26, 1944, now abandoned.

We have described what we lbelieve to be the best embodiments of our invention. We do not wish, however, to be conned to the embodiments described, but what we desire to cover by Letters Patent is set forth in the appended claim.

We claim:

The method of pickling aluminum including the steps of spraying the aluminum with sodium hydroxide solution at a pressure suillcient to cause the reaction layer of sodium aluminate to be mechanically removed by said spray, treating said aluminum in succession with a rinsing water spray, a nitric acid spray, water spray and then with a cold air blast in a direction to mechanically remove substantially all the water on said aluminum followed by a hot air blast to prevent vapor condensation on said aluminum.


REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,355,074 Cleveland Oct. 5, 1920 1,421,055 Adams June 27, 1922 1,445,775 Lathrop Feb. 20, 1923 1,572,848 Porter Feb, 9, 1926 1,705,944 Siegmund Mar. 19, 1929 1,891,549 Lane Dec. 20, 1932 2,137,988 Hempel Nov. 22, 1938 2,235,978 Braucher Mar. 25, 1941 2,347,742 Keene May 2, 1944 2,359,088 Croft Sept, 26, 1944

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1355074 *Dec 30, 1919Oct 5, 1920Universal Paint Remover And MoProcess of removing surface finish
US1421055 *Jan 4, 1921Jun 27, 1922Rice & Adams CorpWashing machine
US1445775 *Mar 10, 1921Feb 20, 1923Lathrop Harry DBottle-washing machine
US1572848 *Aug 27, 1924Feb 9, 1926American Sheet & Tin PlateRemoval of oxids from ferrous metal
US1705944 *Sep 2, 1926Mar 19, 1929WesternElectrolytic device
US1891549 *Dec 3, 1930Dec 20, 1932Aluminum Co Of AmericaTreatment of aluminum alloys
US2137988 *Oct 21, 1936Nov 22, 1938Heresite & Chemical CompanyAdherent aluminum compound
US2235978 *Jan 30, 1939Mar 25, 1941Braucher Harvey MContinuous strip coating machine
US2347742 *Sep 18, 1939May 2, 1944Rustless Iron & Steel CorpPickling process
US2359088 *Feb 17, 1940Sep 26, 1944Blaw Knox CoTreating metal strip
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2633437 *Jul 31, 1951Mar 31, 1953Stoelting Bros CoMethod of washing aluminum kitchen utensils
US2698625 *Nov 14, 1949Jan 4, 1955Gen Mills IncCellulose products purification apparatus
US2725314 *Jan 29, 1952Nov 29, 1955Leslie E LancyIn line treatment of toxic carry-over of work pieces
US2750309 *Oct 28, 1953Jun 12, 1956British Aluminium Co LtdTreatment of the surfaces of aluminium or aluminium alloys
US2762150 *May 2, 1955Sep 11, 1956Turco Products IncApparatus and process for removing material from a work piece
US2872932 *Jan 20, 1956Feb 10, 1959Chas H Stehling CompanyApparatus for soaking pasting plates
US2919705 *Feb 6, 1956Jan 5, 1960American Can CoApparatus for treating articles
US2971826 *Nov 3, 1954Feb 14, 1961Cohn Charles CChemical polishing method
US3031362 *Jan 5, 1959Apr 24, 1962Hermann WeberMethod and means for producing explanatory texts on the pictures of films
US3055378 *Jan 7, 1957Sep 25, 1962Alford Emra LWasher unit
US3056414 *Dec 30, 1960Oct 2, 1962Metalwash Machinery CompanyArticle washing machine
US3073765 *Apr 18, 1960Jan 15, 1963Adams Ronald Alfred CharlesProcess for electrolytically graining aluminum lithographic plates
US3211571 *Apr 17, 1962Oct 12, 1965T Fal CorpMethod and apparatus for acid treating and coating metallic surfaces with plastic
US3410738 *Jan 18, 1965Nov 12, 1968Westinghouse Electric CorpMethod of making coils of electrical conductors
US3465715 *Nov 10, 1966Sep 9, 1969North American RockwellFilter cleaning and coating apparatus
US3718147 *Feb 16, 1971Feb 27, 1973AlusuisseInstallation for degreasing metal articles
US3906895 *Dec 26, 1972Sep 23, 1975Nippon Paint Co LtdSpray type apparatus for treatment of metal surface
US4319930 *Mar 28, 1980Mar 16, 1982Daiwa Can Company, LimitedMethod for multi-stage washing
US5340436 *Jan 31, 1992Aug 23, 1994Beckett Industries Inc.Demetallizing procedure
U.S. Classification216/92, 134/37, 134/60, 134/15, 134/3, 74/421.00R, 134/27, 216/103, 101/459
International ClassificationC23G1/00
Cooperative ClassificationC23G1/00
European ClassificationC23G1/00