US799862A - Process of separating ferriferous zinc compounds. - Google Patents

Description

UNITED sTATEs PATENT OFFICE.

GUY L. MEAKER, OF EVANSTON, ILLINOIS, ASSIGNOR TO THE AMERICAN STEEL & WIRE COMPANY OF NEW JERSEY, A CORPORATION OF NEW JERSEY.

PROCESS OF SEPARATING FERRIFEROUS ZINC COMPOUNDS.

Specification of Letters Patent.

Patented Sept. 19, 1905.

Application filed February 1,1905. Serial No, 243,660.

To all who/1'1, it may concern: I

Be it known that I, GUY L. MEAKER, acitizen of the United States, residing at Evanston, county of Cook, State of Illinois, have'invented certain new and useful Improvements in Processes of Separating Ferriferous. Zinc Compounds, of which the following is aspecification.

My invention relates to a process for separating metallic zinc from compounds containing zinc in association with iron, such, for example, as the dross and skimmings from galvanizing-tanks in which zinc and iron are the principal elements. The same process is applicable to other ferriferous compounds of zinc, even when small amounts of other metals, such as lead and copper, are present.

My invention consists in dissolving the compound to be treated in an acid, such as hydrochloric or sulfuric, and then subjecting the solution to electrolytic action in such manner that the metallic zinc is deposited on the cathode, while the'iron is formed into an insoluble basic ferrous or ferric compound which appears as an ochreous powder suspended in the electrolyte and which may be screened or filtered therefrom at convenience or even left therein indefinitely, since by reason of its insolubility the iron in this form has no detrimental effect'on the deposition of the metallic zinc.

More particularly, I first dissolve the ferriferous compound in either sulfuric or hydrochloric acid, whereby the Zinc is formed into either a chlorid or sulfate of zinc and the iron,by the evolution of hydrogen, is converted into the ferrous condition. It is then desirable that to electrodeposit the metallic zinc from this solution some means must be devised to prevent the simultaneous deposition of the iron or its interference in other ways with the electrolytic action on the zinc. To this end I have conceived of the plan of converting this iron from its ferrous condition into some other condition in which it will be insoluble and consequently innocuous to the zinc deposition and at the same time to accomplish this conversion by means germane to the electrolyzing process itself.

The means I have devised are as follows: In the first place I have found that by establishing a certain ratio between the superficial area of the anode and cathode of the electrol lytic apparatus 1 may cause the iron to be changed from a ferrous to a ferric conditionthat is to say, if these two areas are the same there will be no change in the condition of the iron. If, however, the surface of the anode materially exceeds in area the surface of the cathode the ferrous will be changed to a ferric condition. On the other hand, if the area of the cathode exceeds that of the anode the iron is not only not oxidized from the ferrous to the ferric condition, but any ferric iron is reduced. success under the conditions to be further described an anode having a superficial areaseven times as great as that of the cathode. In the second place, having brought the iron to the ferric condition I provide that it shall take on oxygen, and thereby be converted into the basic condition-that is, in the sense that the base is in excess-having the base atomically greater than that of the acid or the related neutral salt. To this end I oxidize the solution, as by aeration, preferably causing it to circulate in a shallow receptacle with a considerable surface exposed to the atmosphere. In the event of the solution-being neutral on but slightly acid the iron will pass directly from the ferrous to the basic ferrous condition, the efliect on the main process remaining the same-namely, the elimination of the iron. In the third place, the proper performance of the two operations aforesaid requires that instead of an anode of zinc, serving both as a circuit-terminal and as a source of zinc for maintaining the solution, an insoluble anode, such as carbon, should be employed. Moreover, the solution is constantly regenerated by retaining therein after the electrolytic action takes. place the chlorin or other active agent and causing it to circulate through a regenerating-tank, where it passes through a mass of ferriferons zinc compound,

which is to be separated. From the regenerating tank or receptacle it passes to the depositing electrolytic cell and then back to the said tank, so that it circulates through the two in succession. In other words, the ferriferous compound itself may not be used as an anode, not only because it is not ordinarily in a mechanical state permitting it to be so used, but also because no definite size or character of anode-surface can be maintained, nor a certain and adequate replenishment of the In practice I have used with solution nor a sufiiciently low and definite resistance. Upon these features the success of my process is largely dependent, and I secure the results desired by employing an anode of hard graphitic carbon, together with the aforesaid external means of regeneration. In the fourth place,.it is required thata current density be employed greatly in excess of the density heretofore employed in any electrolytic process thatI am aware of. For example, in theHoepfner process of depositingzinc from the chlorid, a current density of one hundred amperes per square meter is employed, or less than ten amperes per square foot of cathode-surface, while in the Szirinay process of galvanizing Wire by electrodeposition from metallic zinc adensity of ten amperes per square foot of cathode-surface is employed. In my process I am now using about one thousand amperes per square foot of cathodesurface and do not expect that in any event a densityof less than four hundred or five hundred would be feasible. In the fifth place, it is important to the satisfactory character of the deposited zinc that the cathode be kept in motion. The precise reason for this I do now undertake to give, it apparently being independent of any washing or other effect produced by the relative movement of the cathode with respect to the solution and also independent of any intermittent exposure of the cathode to the atmosphere. The fact is as stated, however it may be explained. By these means I am enabled to maintain a continuous process of deposition in a thoroughly practical manner.

It is unnecessary to maintain any exact percentages of components in the electrolytic solution or to measure them with care. The ferriferous zinc compounds may be shoveled into the regenerating-tank from time to time with little regard to the precise amount, and acid may be added in almost the same way. It is desirable that the solution should not fall below 16 Baum, but above that point the density of the solution has no apparent influence on the process, (save in the reduction of cost.) Moreover, I am enabled to work With dross, skimmings, and scrap materials, which have hitherto been waste products. I may also work from roasted ores and similar materials, which it has heretofore been necessary to refine into metallic zinc before subjecting them to an electrolytic process. Finally, I am able to deposit the zinc with a rapidity far beyond what has been heretofore considered possible and to any desired thickness. The deposition of zinc in the mossy, spongy, or black-oxid form is Wholly eliminated, however rapidly or to whatever thickness the deposit is produced. I attribute the success of my process to the neutralization of the efiect of the iron in the manner described. As regards other metallic substances 1 rease which may be present in the ferriferous compounds the lead will not enter into the solu tion in the dilute acids used of a strength less than one to four. As regards copper, the amount to be found in these ferriferous zinc compounds is so small as to be negligible. Theoretically it would deposit along with the zinc, but I have been unable to detect its presence in any of the many analyses I have made of the deposited zinc.

What I claim as new, and desire to secure by Letters Patent, is-

1. In the process of separating ferriferous zinc compounds by rendering the iron component neutral to the electrolytic action the method of oxidizing the electrolytic solution which consists in giving the anode an active surface larger than that of the cathode.

2. The process of separating ferriferous zinc compounds which consists in dissolving the compound to form an electrolytic solution, converting the iron into a neutral form by oxidizing means, including the proportioning of the electrode-surfaces so that the anode-surface shall substanially exceed that of the cathode, and electrodepositing the zinc on the cathode. I

3. The process of separating ferriferous compounds of zinc, which consists in dissolving the compound into an electrolytic solution,

converting the iron from the ferrous to the ferric condition by proportioning the anode and cathode surfaces, converting it from the ferric condition to an insoluble basic ferric condition by oxidation and electrodepositing the zinc on the cathode.

4:. The process of separating ferriferous compounds of zinc, which consists in dissolving the compound into an electrolytic solution, transferring the solution from the point of formation to an anode of insoluble material adjacent to a cathode of smaller superficial area, passing an electric current from the anode to the cathode through the solution, and oxidizing the solution, whereby the zinc is deposited on the cathode and the iron is precipitated in an insoluble, basic, ferrous or ferric form.

5. The process of separating the iron from a ferriferous metallic compound which consists in dissolving the compound into an electrolytic solution, precipitating the iron in an insoluble form by passing an electric current through said solution from an anode to a cathode of smaller superficial area and by oxidizing the solution and simultaneously depositing the metal on the cathode.

6. The process of separating the iron from a ferriferous metallic compound which consists in dissolving the compound into an electrolytic solution, passing an electric current through said solution from an anode of insoluble material to a moving cathode of smaller superficial area, and oxidizing the solution,

whereby the iron is precipitated in an insoluble form and the metal is electrodeposited on the cathode.

7. Acontinuous process of separatinga ferriferous zinc compound which consists in circulating an acid solution through a receptacle containing the compound to be separated and through an electrolytic cell in succession, passing an electric current through the solution in said cell from an insoluble anode to a cathode of smaller superficial area and oxidizing the solution, whereby the iron is precipitated into the solution in an insoluble form and the zinc is electrodeposited on the cathode.

8. The process of electrodepositing zinc from a ferriferous compound thereof, which consists in dissolving the compound into an moving cathode by an electric current having a a density of atleast four hundred amperes per square foot of cathode-surface.

In witness whereof I have hereunto set my hand, before two subscribing witnesses, this 14th day of January, 1905.

GUY L. MEAKER.

Witnesses:

J. W. MEAKER, J12,

G. A. MASON.