US2235825A - Method of pickling and liming ferrous articles - Google Patents

Description

March 25, 1941. s p 2,235.825

' METHOD OF PICKLING AND LIMING FERROUS ARTICLES Original File d Sept. 23, 1937 3 SheetsSheet 1 INVENTOR fiaz'dneyl? fizzy 2 4: ATTORNEY Ma lCh 25, 1941. s. P. CARY nmaofi OFPICKLING AND LIMING 'FERRoUs ARTICLES 3 Sheets-Sheet 2 Original FilegL Sept. 25, 1937 INVENTOR idkqqfill'aly Z a I I ATTORNEY s. P; cARY METHOD OF PICKLING AND LIMING FERROUS ARTICLES 7 Original Filed Sept. 25, 1937 3 Sheets-Sheet 5 RC Y m mm w! m mm. A. s M a, v U

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Patented Mar. 25, 1941 warrior) or PIGKLING AND mama sermons narrows Sidney r. can,

North Tonawanda, N. Y., assignor to Builalo Bolt Company, North Tonawanda', N. Y., a corporation oi New York Original application September 23. 1937, Serial No. 165,268. Divided and this application April 24,1939, Serial No. 269,597

'1 Claims. (Cl. 91-70) The present invention concerns methods set forth in my application Ser. No. 165,268, filed Sept. 23, 1937, of which this is a division. They are disclosed in connection with pickling and lime-coating loosely coiled wire or rod material; or, more specifically, ordinary commercial bundle coils in which the wire or rod is iron, steel or ferrous alloy, but it will be obvious that certain features of the invention may be utilized for analogous purposes, in connection with specifically different articles, metals or coatings.

It is common practice to clean such articles, and where the metal is ferrous, free them from scale, by first submerging them in a hot acid or pickling solution to'remove the scale; then rins-,

ing in water to remove the acid; then treating it with hot liming solution and drying a coating of lime thereon, so as to neutralize acid that remains after the rinsing; and to prevent oxidation; and, in the case of wire or rod material, the lime coating is also utilized as a lubricant during further processing, as for instance drawing the wire or red through dies, or cold rolling it, to decrease its diameter, .or to chan e the shape of its cross-section. The liming solution referred to is a mixture in which relatively large quantities of hydrated lime are held in suspension in the water. The part of the lime that canbe actually in solution in the hot 'water is somewhat less than one per cent.

Commonly, the lime coating is applied-by submerging the metal in a hot liming solution long enough to heat the metal; then lifting it above the solution to expose it to the air until dry. This leaves the'metalwith alime coating 01' a definite thickness predetermined by the viscosity, cohesion and surface tension of the liming solution. One such coating is seldom suflicient, and such submerging and drying operation is repeated as many times as necessary to build up the coating to a desired thickness.

If the acid remaining after rinsing is not completely neutralized by the liming, there is always danser that it will cause brittleness in the steel; and in certain cases, this has led to liming methods which do not neutralize all the acid in the lime coated metal, the remnant of acid being neutralized by baking it in an oven, at low temperatures. This is troublesome and expensive; and one advantage of the present invention is that the last traces oi acid in the steel are eliminated in the liming tank where the coiled wire or rod material is heated to about 180 F.

-This treatment ex'pels the occluded hydrogen (due to the action of the acid) whose presence causes brittleness.

According to the old method, the coils were handled-by anoverhead crane which was kept busy supplying coils to the pickling tank, trans-. 5

ferring them to the rinsing tank and then to the liming tank. In such cases, the crane deposited the rinsed coils in the liming solution as expeditiously as possible, and, after the coils were heated, lifted them above the solution and held them suspended while drying. For some classes of work, the crane had to do this only two or three times; but on other classes, four or five times would be necessary. It was found that suchsubmerging, for the required length of time, hoisting and drying for the required length of time and again submerging took so much time, that it delayed the other work of the crane in transferring coils into and out of the pickling solution; and into and out of the rinsing tank, thus seriously decreasing the production rate.

The primary object of the present inventlon is to provide methods whereby the above described unbalance of the several operations is tion at a rate which will permit sensible heat irom the wire or rod, to absorb latent heat and evaporate the water in which the lime is suspended practically as fast as the coil emerges; that the conditions of the drying coating Just above the surface are so uniform throughout the emerging operation, that the coating will be substantially uniform, notwithstanding the fact that the lowermost part of the coil is submerged much longer than the upper part; that by thus drying the coating by heat derived from the metal, it becomes unnecessary to lift the coil out into the dry upper air; and that the wire dries. as last or faster, by reason of the fact that the small lengths of wire just above the surface of the solution are heated not only by heat stored up within the wire, but also by heat from ad- Jacent wire which is still submerged and is itself receiving heat from the solution.

It was also discovered that during the gradual submerglng and emerging oi the coil, heat flow from the solution into the wire and lengthwise in said wire is so rapid, that relatively short intervals of complete submergence and complete emergence, are sufficient for producing approximately uniform temperatures throughout the coil, by the time the top of the coil begins to emerge; and correspondingly uniform lower temperatures, by the time the bottom of the coil begins to be submerged.

To utilize the above described, somewhat paradoxical, method of progressively drying the wire by heat continuously derived from the solution, in addition to heat stored up in itself, the present invention contemplates leaving the coil suspended in the liming tank, and alternately submerging and exposing it, by lowering and raising the level of the solution.

So far as concerns practice of the/basic principles of the above method, it will be evident that approximately parallel temperature and drying efiects could be produced by raising and lowering the coil with respect to a constant-level surface for the lime solution. However, it will be evident that by keeping the coil stationary, at a low level in the hot tank during and after emergence, both maximum and minimum temperature for the coil will be higher for any given temperature of the solution, andthe temperature factor in neutralizing the acid will be correspondingly more effective.

Further important advantages result from employing a two-compartment liming tank, and

lowering the level and exposing the coils-in the other compartment. In a given case, and for. a given thickness of lime coating, the output may be doubled; or for a given output, the thickness of the coating may be doubled; or increased output may be combined with increased thickness of coating. The so-called solution carries much lime in suspension and the pumping keeps the mixture uniform in thi respect; and tend to keep the temperature uniform. The active discharge of the solution into the liming tank, during the submerging' period, creates convection currents forcing circulation of the hot solution to, through, and from, the convolutions in the coils; thereby washing them thoroughly, and greatly increasing the amount of heat that the solution can impart to the coils in a given time.

The above and other features of my invention may be more readily understood from the following description in connection with the accompanying drawings, in which Fig. 1 is a plan view of my improved pickling, rinsing and liming apparatus;

Fig. 2 is a vertical section transversely of the apparatus, showing the overhead crane, in its relation to any one of the tanks, in this case, one of the pickling tanks; 3

Fig. 3 is a plan view showing the two-compartment liming tank, and the pumping mechanism Fig. 4 is a vertical section on the line 6,-4. Fig. 3;

Fig. 5 is a vertical section on the line'55.

drainage and steam pipe arrangement for the two-compartment liming tank.

In Fig. l, the complete apparatus is shown as comprising a'line of end-to-end tanks includin two similar pickling tanks i, la; a rinsing tank 2 in which the rinsing spray nozzles 2a are more or less diagrammatically and incompletely indi-, cated; the liming tank 3, comprising two similar compartments A, B; and pumping mechanism for pumping the liming solution from one compartment to the other, said pumping mechanism including intake and discharge nozzles 41, da having intake and discharge openings at the bottoms of the respective compartments, A, B, pipes 55, 5a controlled by valves 6, 6a, connecting said nozzles with reversible centrifugal pump 1, driven by an electric motor la.

These aligned tanks are parallelled by rails 8, do. As shown in Fig. 2, these rails carry an overhead crane 8, operated by a motor 9a, diagrammatically indicated in dotted lines. The hoisting tackle 9b is adapted to be hooked to any one of a number of similar'coil carries. Each carrier includes a beam member 10, adapted to extend widthwise across and rest upon, the top walls of any one of the tanks. The beam has depending therefrom a rigid bracket IOa, formed with a horizontal hook-like support lob, adapted to hook through and support one or more wire or rod coils :c, preferably a batch of such coils, as shown. The beam I. of each coil carrier is equipped with suitable bail lie for hoisting, and a, handle "id for guiding it while suspended.

The acid pickling tanks I, la, are shown in cross-section in Fig. 2, and as indicated in Fig. 1, each of them is adapted to accommodate four of the above described coil carriers, each supporting a batch of coils, giving a pickling tank capacity of eight carriers. This large coil capacity is because of the relatively long time required for pickling, as compared with rinsing. The rinsing tank 2 accommodates only one'coil carrier at a time; and the liming compartments A and B, each accommodates one coil carrien These capacities give a fair working balance between the different kinds of work each requiring different lengths of time for completion.

Fig. 3, with the above reference characters applied thereto, gives the plan view relations and proportions of the liming compartments and reversing pump. Fig. 4 gives similar information with respect to the rear elevation of said parts. Further details necessary for explanation of my liming apparatus and methods are shown in Figs. 5 and 6.

Fig. 5 shows liming compartment, B; also, in dotted lines, the coils a: which are suspended therein, on the carrier l0, Ilia/lob; also a desirable low level of the solution is indicated by the dotted line a, at approximately the level of the upper edge of the flattened intake and discharge nozzle to; and a desirable high level is indicated by the dotted line, b.

An important feature of the invention is that proper uniform operation is best ensured by a uniform rate of emergence and-submergence of the coils. For this purpose, the rate of charge and discharge may be adjusted by regulating the speed of the pump motor Ia, or adjusting valves or 6a. A fixed rate of correlatively emptying and filling the respective compartments being thus established, it is desirable also to automatically regulate the pump reversals, and so that they will occur whenever the desired high and low levels are reached in the respective compartmerits. Since either one of the compartments will have the high and low levels that determine the time for reversal, it is convenient to gauge the reversal in accordance with the high and low levels in one of the compartments.

As shown in Figs. l and 5, compartment B happens to be selected for thispurpose, andthe mechanism employed is best shown in Figs. 5' and o. In' one corner of compartment B is a perforated partitionzl, which protects a. float 22, attached to chain it. Chain 23 runsover pulleys it, on support It; and down into pipe 28, where it is connected to, and tensioned by, counterweight ll.

0n chain it are two collars, one collar 28 a suitable distance above the float and the other collar it a suitable distance above the weight. As shown in Fla. b, float 22 is at its lowest level, and the collar it has pushed slidable tube I! up wards. and has raised one end of a tilting lever it, to a point where it has operated is pivoted switch member ll, moreor less diagrammatically indicated in big. ii. l'his switch has operated through ordinary electrical control mechanism, not shown, to reverse the motorwlo, thereby reversing the pump i. This reversal having occurred at a time of low level in tank B, the pump discharges into said ,tanlr, gradually raising the level thereof, and thereby raising float it; it will he obvious that when the float reaches the high level dotted line, b, the collar M will earn tact with the other end of the tilting lever lb, thereby operating the electrical control devices in the opposite direction and again reversing the pump motor. r r

The maintenance at standard high and low levels tor the liming solution is imrtant. steam is used to lreep the liming solution at the desired high temperature, and condensation oi this steam increases the total volume oi the solution. The desired heating oil the coil is to such a temperatln-e that the liquid will be uuichiy evaporated irorn the coil by the heat oi the coil when the liquid level is below the coil, it has been iound that a liming solution temperature oi about lad" it is satisiactory, but a higher temperature would not slows up the operation.

The low level a, is made more definite, and more suddenly arrived at, by having nozzles iilo flattened horinontaliy parallel with the bot tom of the compartment, with their upper edges horizontal, and near the level oi said low level line n. Thus arranged it will be obvious that when id is operating as an intalre lor the pump it will be iuily submerged and will be lowering the surface of thesolutlon at approrately uniform rate, until well alter the emerg coil has been fully euposed; and the coil in the other tanlr is correlntlvely submerged.

be objectionable, and a much lower temperature as concerns the lone-rung oi the pp nozzles, when acting discharge uomles, it will be noted that their side walls diverge horizontally, and their top and bottom walls converge vertically toward the discharge opening. do each nozzle dischmwes a list divergent stream directed along the bottom oi the compartment, thereby stirring up and mirdng inany lime that might a 7 an important effect as concerns rapidly heating otherwise tend to settleout oi the minturc. i ur thermore, as soon as a coil begins to'be submerged. the stream can circulate upward and actively penetrate the convolutions of the coil. This has the wire and rod material; also as concerns absorbing occluded hydrogen that as been freed from the steel by the heat.

While the above describedactionpi the stream liming solution is etl'ective for absorbing liberated hydrogen, my present method contemplates combining this withother rectors, the most important of which is heatlng the stcelto a temperature high enough to cause the hydrogen tobe expelled from the steel. When the solution is applied in accordance with my present invention, it heats the steel so oorly to its own temperature that solution temperatures substantially below boiling are effective; and in a particular case, solution temperatures of about mo" ll. were found to be sufflcient to free the steel from occluded hydrogen probably completely, and pertainly completely enough to eliminate all danger oi its making the steel too brittle.

It has been discovered that the most desirable way of applying the heat is by discharging live steam into the liquid, preierahly ncarthe bottom thereof, preferably distributing the discharge through separate nozzles located in the respective compartments. Preferably at least one nozzle in 4 each compartment is arranged in cooperative re lation with the stream of solution discharged through the pump nozzle.

In the preferred arrangement as shown in Figs.

' 'l and b, there is a steam nozzle it in the lower corner oi tank b discharging toward the edge oi" the stream of solution issuing lroni pump nozzle is. Preferably also there is another nozzle ii, in the diagonally opposite coruor discharging toward the streamer solution. Such loca. tions and directions for the steam nozzles contribute to preventing the suspendedfilime from settling out of the moisture.

it convenient way oi supporting the nozzle it, and supplying it with steam, is to have it at the lower end oi a vertical pipe lilo controlled by valve ilb supplied through pipe iliic, supplied by pipe ll leading from a suitable steam supply, and controlled by valve its.

Steam nozzle ll is similarly supported by vertical pipe lid controlled by valve illb supplied with steam through pipe lilib from supply pipelt.

The arrangement for compartment d is pref erably similar and symmetrical with respect to that oi compartment h, nozzle iilsheing supported by supply pipe lly controlled by valve lie, and supplied from pipe lite; the other nozzle list being supported by supply pipe lily communicating through control valve on with supply pipe lite.

by the above arrangement the solution may be kept at the desired high temperature notwithstanding-the great amount oi heat absorbed as latent heat, in evaporating the large ornounts of water which must be evaporated in order to dry the lime coating on the wire or red material. it is possible also that live steam thus discharged into the stream oi solution, and circulated through the cells, may he specifically beneficial in connection with removing or neutralizing occluded hydrogen.

@bviously thecondensste contributes water to replace that evaporated; but, in practice, the amount oi water so contributed, is greater than required tor this purpose. bone-currently the vol little of the solution gradually increases.

Such increase in volume does not ailect the high and low levels oi the compartment B, because these are fixed by having the control'float,

22, in said compartment; but any excess will operate to raise both the low level and the high till till

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level in compartment A. As shown in Figs. 7 and 8; such increasein volume is prevented by grav- 'i ty-overflow in excess solution through pipe 4 i which has intakes Ha, lib leading from the respective compartments, both intakes being at the same predetermined limit of high level for the solution.

For convenience, there is also a pipe 5| which can be closed by valve Ilia. This pipe has intakes Bib, Sic leading from the respective compartmen'ts at the level required for predetermining the proper level when the circulating pump is not in use and the coilsare being coated by the" old method, namely, using the crane to lift them out of the tank, and hold them suspended while the coat is drying. Pipes 4! and ii discharge through pipe 6! into sump D. There is also a gauge overflow pipe 13, controlled by valve 18a; which .discharges into sump E. This pipe is for use in charging the compartments with w the proper volume of liming solution required for" the preferred alternating pump operation. The overflow will gauge the volume so that, in operation, it will give the predetermined high and low levels indicated in Fig; 5. Such volumeis of course equal to the capacity of compartment B up to the low level line a; plus the volume in compartment A, which at that time is -up tothe high level line b.

The above described apparatus permits opera, tion in accordance with a'method affording a practically satisfactory approximation to perfect time balance for operation of the crane. In genm1, it may be said that the time required each of the operations is different for different diameters of wire or rod used; different conditions as to the grade of steel and the amount of scale or rust on the surfaces of the'metal; and

for diil'erent temperatures-and concentration of the solutions.

7% to 8% sulphuric acid and may be at a temperature of, say, 150 F. The acidity of the solution may be kept up by additions of sulphuric .acid, but it is preferable to let the acidity run.

down, becauseQas the acid dissolves the iron, the iron content of the solution increasesand when it reachesabout 9% or 10%, the solution must be dumped and a new solution made up. Consequently, it is better to let the acid decrease to a practically useful minimum, by the time the iron content has reached the practically permissible maximum. The acid minimum may be with such practice, and in an ordinary case. the pickling time for each coil may average about 40 minutes, and as the two tanks have a capacity of 8 coil carriers, it will be possible to have a carrier full'of coils ready for rinsing about every 5 minutes.

RinsiM.-The rinsing tank, which isonly diagrammatically indicated, is so effective that it I Making due allowance for these variables and without going too far as to these details, a fair idea of the time balance in a typical'average case, may be had from the following: v Ficlcliny-The pickling solution may have, say,

for properly coating a coil, the batch of coils in one compartment may be ready for removal in say, 5 or 8 minutes after submersion; or, for the two compartments, and allowing reasonable margins, onebatch every 4 or 4 /2 minutes. It takes time for the crane to lift out the completed coils and replace them by a rinsed coil, so it will be obvious that the above suggested 5-minute intervals between pickled coils, ready to be rinsed, will substantially balance the four or four and one-halfminute intervals between coated coils.

As before explained, the pump is a centrifugal pump, which is capable of allowing'variable slip,

to vary the discharge rate, by and in accordance with back pressure which may be regulated by adjusting the valves, 6, 6a. In this way, the time cycle of submergence and emergence may be varied to suit the material being operated upon,-as also to suit the time required for coil transference by the crane. v

For a given temperature of the solution the principal effect of increasing or decreasing the time cycle, is to increase or decrease the amount the pickling and liming of heat absorbed by a coil, between the time it cycle, the moreheat can be absorbed by the coil.

Consequently, the larger the diameter of the rod or wire, the longer the cycle should be for heating it to a givenhigh temperature.

In all ordinary practice of this method, the

thickness of the coating depends almost entirely on the number of times the coils are submerged and exposed. It is true that the lower half of each coil is. submerged nearly twiceas long as the upper part, but has only half as much time of exposure for drying; and as between the upper third and lower third, the contrast is even greater; but this does not make any'substantial difference in'the thickness of the lime coating. Ordinarily, the solution is hot enough to heat the metal hot enough so that when exposed, its internal heat will operate to evaporate the water from the liming solution film in a relatively short time; and substantially all the hypothetical difference in thickness of coating which one might expect to result from such widely difierent times of submergence and exposure; will be completely taken care of and the coating rendered uniform enough for all practicalpurposes. This may be more specifically explained as follows:

(1) -As soon as the rising liquid begins tosubmerge the lower portions of the coils, the heat absorbed by the wire, begins to be conducted upward through the wire so that by the time the upper portion has been submerged by rise to and fall from line b, all parts of the coil will have reached a substantially uniform maximum temperature.

(2) Then as the solution is drawn oil, a reverse process takes place. As soon as metal in the upper part of the coil is exposed, absorbed heat and heat conducted from below, becomes effective to evaporate all of the water from the him of water and line clinging to said exposed metal, within avery short'time.

3) This operation continues progressively downward, until the lowermost po'rtionof' the coil is exposed, and, at this point, the time it takes the liquid to fall away from the lowermost portion of the coil to the level indicated by the dotted line a, and then to rise up again to first contact with the bottom of the coil, is entirely sufficient for said bottom of the coil to dry out as effectively as all other portions have dried.

It is to be noted that conduction of heat from the submerged to the exposed portions of the wire or rod is an important factor of the uniform heating and drying, throughout all parts of the coil, including portions adjacent the top and bottom, as well as throughout the interme-' diate portions thereof. This shows that the functioning of the method will not be materially interfered with if the entire coil is inclined to the surface of the liming solution at a relatively acute angle; and that the functioning would be the same in principleythough less effective in degree, if the coils were horizontal. It follows also that while the functioning is best where the metal is elongated, and is of uniform cross-section, and a substantial part of it is at a high angle to the surface of the solution, nevertheless the method is capable of functioning, with varying degrees of efficiency, with respect toalmost any article, arranged so that the liming solution can drain off sufficiently from the exposed surface of the article.

- While I have explained the importanceof various phases of my invention such as balance of output as between the pickling, rinsing, liming and conveying elements of the combination; efliciency of the liming apparatus in heating the steel to temperatures closely approximating the temperatures of the liming solution: making said temperatures high enough to ensure freeing the steel from occluded hydrogen, etc.; it will be obvious that the lime coating apparatus, as well as many of its preferred details of construction and operation, will prove useful when employed separately, or when operated at temperatures too low to eliminate occluded hydrogen, or when operating on material that does not contain oceluded hydrogen. Similarly the lime coating methods, as concerns gradually and progressively submerging and exposing material to coat it with lime, is useful independently of whether or not advantage is taken of the possibility of operating to heatthe steel to temperatures higher than have heretofore been attained: and independentit; of whether or not these temperatures are high enough to ensure freeing the steel from the occluded hydrogen, and independently of whether or not the steel contains any such hydrogen.

This is of course without prejudice to the special novelties and advantages resulting from employing all of the novel features in combination; and it is a special merit of the methods of op ration at high temperatures. thatthey have a double utility, namely, greatly speeding up the rate of coating, and, at'the same time ensurinli expulsion of occluded hydrogen from the steel, if it contains any.

In the following claims, it is to be understood that "lime solution, liming solution and,colution are used for convenient commonpiace identification oi the, hereinbefore described mixture consisting of hydrated lime in suspension in water.

I claim:

1. A method of coating a coil of ferrous wire or rod material, which method includes suspending the coil in a receptacle, maintaining a liming solution at a temperature of about 180 F., raising the level of the hot liming solution in said receptacle to gradually and progressively submerge the coil and to progressively heat the coil; maintaining the solution above the top of said coil until the latter is heated to practically uniform high temperature approximately that of the solution; lowering the level of said solution to gradually expose the coil above the surface of the solution and progressively evaporate water therefrom and dry the lime coating on exposed portions of the coil adjacent said surface, by heat stored up therein and by heat conducted from adjacent submerged portions that are still receiving heat from the solution; and continuing to lower said level, to completely expose the bottom of the coil above the surface of the solution to allow it to drain, and to be dried by the heat stored up therein.

2. A method of coating a coil of ferrous wire 'or rod material, which method includes suspending the coil in a receptacle, raising the level of a hot liming solution in said receptacle to gradually andprogressively submerge the coil to progressively heat the wire or rod material; maintaining the solution above the top of said coil until heated to practically uniform high temperature; lowering the level of said solution to gradually expose the coil above the surface of the solution and progres ively dry the lime coating on exposedportio "of the coil adjacent said surface, by heat stored up therein and by heat conducted from adjacent submerged portions that are still. receiving heat from the solution; and continuing a to lower said level, until the bottom of the coil is exposed above the surface of the solution to allow it to drain, and to be dried by the heat stored ing coils in separate similar receptacles; pumping hot liming solution from near the bottom of one receptacle to near the bottom of the other alterup therein; repeating the above cycle of raising A0 nately in sufficient volume and at suitable rates for gradually and progressively submerging the coil in one receptacle to progressively heat the\ coil, from'the bottom upward; maintaining the level above the top of the coil 'until the coil is I heated to practically uniform high temperature; while correlatively lowering the level in the other receptacle, to gradually expose the coil therein above the surface of the solution and progressively dry the lime coating on exposed portions of the ,wire or rod adjacent said surface. by heat stored up therein and by heat conducted from adjacent submerged portions that are still receiving heat from the solution, said lowering the level of the solution being continued to completely expose the bottom of the coil above the surface of the solu-- tion to allow it to drain, and to be dried by the heat stored up therein, while the coil in the other receptacle is submerged and absorbing heat.

4. A. method of coating coils of ferrous wire or rod material, which method includes suspending coils in separate similar receptacles: pumping but liming solution from near the bottom of one receptacle to near the bottom of the other rates for gradually and progressively submerging heat stored up therein and by heat conducted from adjacent submerged portions that are still receiving heat from the solution; also correlatively lowering the level of the solution to completely expose the bottom of the coil above the surface of the solution to allow it to drain, and to be dried by the heat stored up therein. while the coil in the other receptacle is submerged and absorbing heat; and repeating the above cycle of submergence and emergence to add additional coatings until the material has been coated to adesired thickness.

5. A method of coating a coil of ferrous wire or rod material,.which includes suspending a coil in a receptacle, alternately forcing liming solution having a temperature of about 180 F. into the bottom of the receptacle and withdrawing it therefrom, the delivery of the solution to the receptacle being continued until the coil is completely submerged, and the withdrawing being continued until the liquid level is below the coil, the liquid level above the'coil being maintained until the coil has substantially reached the temperature of the solution, and the liquid level being maintained below the coil until the liquid on the coil surface has been substantially completely evaporated by the action of the heat absorbed in the coil by its previous submergence;

6. A method of treating a coil of ferrous rod or wire material whichhas been subjected to pickling in an acid solution and has occluded hydrogen on its surface, which method includes suspending the coil in a stationary position in a rea'asas'at alternately in suflicient volume and at suitable around and over the surfaceof the coil genceptacle, delivering receptacle in a substantially horizontal direction near the bottom of the receptacle until the level of the solution is above that of the coil and the coil has been heated by the solution to a temperat ure approaching that of the solution, ex-

1 milling the occluded hydrogen on the coil surface by the action of the eddy currents of solution erated by the action of the substantially horizontal delivery of the solution 'at the bottom of the receptacle, withdrawing the. solution from the bottom of the receptacle until the liquid level is below the coil, and maintaining the level below the coil until the heat absorbed by the coil during its submergence has evaporated the liquid from the surface of the coil. i

7. A method of treating a coil of ferrous rod or wirematerial which has been subjected to pickling in an acid solution and has occluded hy. drogen on its surface, which method includes suspending the coil in a stationary position in a receptacle, delivering hot liming solution into the receptacle in a substantially horizontal direction near the bottom of the receptacle until the level of the solution is above-that of the coil and the coil has been heated by the solution to a temperature approaching that of the solution, expelling the occluded hydrogen on the coil surface by the action of the eddy currents of solution around and over the surface of the coil generated by the action of the substantially horizontal delivery of the solution at the bottom of the receptacle, with drawing the solution from the bottom of the receptacle until the liquid level is below the coil, and maintaining the level below the coil until the heat absorbed by the coil during its sub-' mergence has evaporated the liquid from the surface of the coil, and repeating the delivery and the withdrawal steps until the occluded hydrogen has been expelled and lime coating of the desired thickness has been formed on'the surface of the material.

' SIDNEY P. CARY.

hot liming solution intc'thet

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