US2045581A

US2045581A - Electrolytic pickling apparatus

Info

Publication number: US2045581A
Application number: US694028A
Authority: US
Inventors: Allan E Chester
Original assignee: Ferro Enamel Corp
Current assignee: Ferro Corp
Priority date: 1933-10-18
Filing date: 1933-10-18
Publication date: 1936-06-30
Anticipated expiration: 1953-06-30

Description

June 30, 1936. A. E. CHESTER 2,045,581

ELECTROLYTIC PICKLING APPARATUS Filed Oct. is, 1933 2 Sheets-Sheet 1 m NvEkTOR ATTORNEY June 30, 1936. A. E. CHESTER ELECTROLYTIC PICKLING APPARATUS Filed Oct. 18, 1953 2 Sheets-Sheet 2 ATTORNEY Patented June 30, 1936 UNITED STATES ELECTROLYTIC PICKLING APPARATUS Allan E. Chester, Brooklyn, N. Y., 'assignor, by direct and mesne assignments, to Ferro Enamel Corporation, Cleveland, Ohio, a corporation of Ohio Application October 18, 1933, Serial No. 694,028

2 Claims. 31. 204-5) The present invention relates to the cleaning and pickling of iron and steel generally including, for example, high carbon steel, low carbon steel, such, for example, as enamellerssteel, alloy 5 steel and iron, wrought iron, cast' iron, cast'steel, malleable iron, semi-steel, and drop forgings of various compositions.

An object of the invention is to provide an improved pickling bath which accomplishes the pickling operation in less time than is required by the baths now commonly in use and at the same time inhibits attack by the bath on the base metal itself, in contradistinction to hitherto known baths employing an inhibitor which slows the action of the bath.

. Another object of the invention is to provide an electric pickling system that isneither impractical nor too costly to be used by steel manufacturers and fabricators, the system being one capable of handling large quantities of work, for example, quantities as large as are at present cleansed in non-electric pickling systems, as distinguished from prior proposed electric pickling systems that have been either impractical or too costly for the pickling of large quantities of work commercially.

Another object of the invention is the provision of an electric pickling system in which the abovementioned improved pickling bath is used as an electrolyte, the present process providing an electrolyte of greater chemical efficiency than the prior known pickling baths and having the advantages of producing electrically the evolution of gas in'large quantities and causing ionization of the electrolyte which results in a greater flow of ferric, ferrous, and other ions from the work I and consequently in a higher combined chemical and electrical eiiiciency. I

Another object of the invention is the provision 40 of a method and apparatus for employing alternating current in an electrolytic pickling cell whereby the work to be cleansed is automatically brought into contact with the electrical circuit without external or internal racking, clamping 45 or connecting individual pieces of work in the circuit.

Another object of the invention is the provision of anelectric picklingsystem which utilizes, low current densities to facilitate the removal of 50 oxides including magnetic oxides. By low current densities is meant current densities of the order of 1 to 15 .amperes per square foot of work surface, as distinguished, for example, from relatively high current densities of 50 or more am- 5 'peres per square .foot' of work surface.

Other objects of the invention include the provision of an electric pickling system in which the circuit is complete at all times, including permanent electrodes in the cell, the word com-f plete as here used having reference to the presence at all times of all necessary parts of the circuit for functioning, whether the circuit be open or closed, the placing of the work in the bath merely bringing it in physical and electrical contact with a permanent electrode already present in the bath, there being no necessity for using the work itself as either electrode and there being therefore no necessity for clamping or otherwise attaching or securing the workin the electric circuit; and to provide such a system in which the work, in large quantities if preferred, may be placed in a suitable metal basket or container, which is then merely placed in the bath to rest upon an electrode provided to receive it, the container and all the individual pieces of work therein being thus included-in the electric circuit by the mere act of depositing the work in the bath. I

Further objects are the provision of a novel pickling system accomplishing the foregoing obtem in which additional or external heating ap-. paratus orheating energy, such as steam, are frequently not required. For example, in many cases the operation may be started with the bath at room temperature the temperature of the bath rising as the pickling process continues,

.and in which the process of the present invention may be efficiently carried out.

In the drawings: i

Fig. 1 is a perspective view of i a pickling tank embodying constructional features of the invention; 1 A

Fig. 2 is a top plan view of the tank of Fig. 1 on a reduced scale;

Fig. 3 is. a side elevation showing one form 25 jects and advantages at low cost in actual comv mercial pickling practice; and to provide a sysof work-holding basket in the tank of Fig. 1, and

Fig. 4 is an end view of said basket.

Referring to the composition of pickling baths prepared in accordance with the invention, the amount of water used depends, of course, on the size of the tank, and in commercial installations may vary, for example, from gallons to 5,000 gallons and more.

The amount of sulphuric acid may vary widely with reference to the amount of water and may be present in amounts from of 1% to 15% by weight of water in the bath.

In accordance with the present invention, an ingredient is added to such baths as the foregoing, the added ingredient being d-gluconic acid, a substance having apparently contradictory properties in that it functions in the bath not only as an inhibitor, but also as a stimulator.

The following is an example of pickling bath made up in accordance with the invention:

Water 100 parts by weight Sulphuric acid 3 to 10 parts by weight d-gluconic acid part to 10 parts by weight The sulphuric acid used may, for example, be 66 B. commercial sulphuric acid.

The d-gluconic acid used is preferably that obtained by oxidizing commercial glucose, the latter consisting of maltose, dextrose and dextrine. The d-gluconic acid as used in the above formula is a 50% solution. The term d-gluconic acid in the claims is meant to cover d-gluconic acid whether solely or as the d-gluconic acid in (d+l) -g1uconic acid.

In addition to the foregoing ingredients, other substances may, if desired, be included in the bath. For example, a wetting agent such as licorice may be used in amounts varying from 1/25 of 1% to 1% by weight of total acid used. Also, isopropyl alcohol or a sulphonated fatty alcohol may be used in amounts varying from 1% to 25% by volume of water used. The alcohol aids in removing certain insoluble soap micelles, such as insoluble calcium and magnesium soap micelles, from the pores of steel, apt to be present therein after the steel has been cleaned in an alkaline bath and prior to the pickling operation.

The bath given in the foregoing example may be used in the present pickling process at a temperature varying from F. to 180 F., and has been found suitable for pickling high and low carbon steel wire, such as nickel-chromium alloy wire annealed and normalized, the current being 60 cycle A. 0., current density varying from 1 ampere per square foot of work surface to 10 amperes per square foot of work surface.

Pickling baths prepared as above have also demonstrated greatly increased efficiency in the pickling of low carbon enamellers steel, the temperature range being from 90 F. to F. and the current density varying from 0.25 ampere to 10 amperes per square foot of work surface.

The d-gluconic acid present in the bath prevents the formation of iron oxide slime on the work. It also assists in wetting the surface of the steel to be pickled. It is in itself an effective solvent for the lower oxides of iron, and, finally,

it serves not only as an inhibitor, but also stimulates to a great extent the attack of the pickling solution upon the sub-oxides of iron.

Referring to the construction of the tank shown in the drawings, the tank may be rectangular, as indicated in Fig. 1, and provided with an interior lining H of lead or wood. Extending longitudinally along one side of the tank is a bus bar [3 to which a plurality of any suitable inert electrodes l5, l1, l9 and 2| are connecmd. As shown, these electrodes extend over the side of the tank and thence downwardly thereinto near the adjacent tank wall, these vertical portions being preferably enclosed by some, insulating materia1 23, such as bakelite. Each of these electrodes near the bottom of the tank is formed with a horizontally extending work supporting portion 25. These work supporting portions are insulated from the tank lining by suitable supports of insulating material, such as Wooden 2 x 4s or 4 x 4s. These electrodes are referred to as permanent electrodes because they are not disconnected or removed therefrom for successive pickling operations, but form a part of the construction of the electrolytic pickling cell, the word permanent not being intended to imply that the electrodes can not under any circumstances be removed.

Cooperatingwith the work supporting electrodes I5, l1, l9 and 2| are a plurality of

plate electrodes

21, 29, 3| and 33, which extend downwardly into the tank near the opposite side wall thereof, beingsupported in the tank at their bottom edges by any suitable form of wooden or other supporting means, such as the wooden supports 35 shown in the drawings. The

electrodes

21, 29, 3| and 33 are connected to a bus bar 39 extending longitudinally along the upper outside of their adjacent tank wall.

Steam pipes 4| may be provided for the purpose of heating the pickling electrolyte when desired, which may be merely at the outset of the pickling operation or may be throughout the operation.

The tank is provided with a bottom outlet for draining and may, of course, be provided with any suitable water inlet.

Large quantities of work may be pickled in accordance'with the present invention, for example, quantities as large as are at present ordinarily pickled at one time in the usual sulphuric acid pickling baths, without any electric current. For this purpose the basket shown in Figs. 3 and 4 may be used, thebasket or baskets used being of a convenient size to fit in the tank efiiciently when containing work to be pickled and deposited in the tank to rest upon the horizontally extending portions 25 of the work supporting electrodes I 5, l1, l9 and 2|.

The bus bars are connected in an A. C. circuit in obvious manner, the commonly used GO-cycle current being entirely suitable.

It will be understood that many variations may be made in the size and shape of the electrodes without departing from the invention; and it will also be noted that the invention provides an electric pickling system in which onlyvery low current densities are required, so that, although providing for the pickling of large quantities of work, the expense for current is relatively small and well overbalanced by very considerable saving in time as well as saving of heating expense and increased pickling efiiciency due not only to the may be simply deposited in'the bath upon the electrodes, thus'becoming a part of the alternating current circuit through the basket or baskets, when such arev used, and without requiring any external or internal racking, clamping or connecting of individual pieces of work in the circuit.

What is claimed is:-

1. Electrolytic pickling apparatus comprising in combination a pickling solution tank. set of electrodes overlying the bottom of said tank and so arranged as to provide a supporting bed for a work basket, another set of electrodes extending into said tank along the wall thereof to below the normal liquid level therein, and an electrically conductive work basket adapted to rest on said first named electrodes. a

2. Electrolytic pickling apparatus comprising in combination a pickling solution tank, a work 5 basket in which the work articles may be loosely piled, two sets of electrodes fixed in said tank below the normal liquid level therein and so arranged as to permit saidzwork basket to be freely moved into and out of said tank without 10 disturbing said electrodes and one set of said electrodes s'o arranged as to provide a supporting bed for said work basket.

v ALLAN E. CHESTER.