US1496607A - Process for producing ferric oxide - Google Patents

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June 3 1924- H. F. SAUNDERS PROCESS FOR PRODUCING FERRIC OXIDE Filed Au 5, 1922 Mwdc Patented it... 3, 1924. a

UNITED STATES 7 1,496,607 PATENT OFFICE.

HAROLD F. SAUNDERS, O'F CLEVELAND, OHIO, ASSIGNOR TO THE CHEMICAL armour.-

TIES COMPANY, OF CLEVELAND,

OHIO, A CORPORATION OF OHIO.

PROCESS FOR PRODUCING FERRIC OXIDE.

Application filed August 3, 1922. Serial No. 579,360.

To all whom it may concern:

Be itknown that I, HAROLD F. SAUNDERS, a citizen of the United States, residing in the city of Cleveland, county of Cuyahoga, and State of Ohio, have invented certain new and useful Improvements'in Processes for Producing Ferric Oxide, of which the following is a specification.

This invention relates to the manufacture 10 of ferric oxide by an electrolytic process.

The principal aims of niy invention are to provide a process for producing, uickly and cheaply, ferric oxides having extreme fineness of particle, and which are particularly valuable as pigments, and having creased covering power.

When an electrolyte composed of an ionizable salt in solution is electrolyzed by a direct current in a cell consisting of an iron anode and a cathode of any conducting material, and the products of the reaction, consisting principally of ferrous hydroxide, are exposed to the air, there is a gradual oxidation to form both ferric and ferrosoferric oxide, the latter in considerable proportion. The ferroso-ferric oxide being relatively the more stable, it is difiicult to obtain a pure-ferric oxide by this means.

The oxides of iron obtained by electrolytic means possess certain physical characteristics, such as extreme fineness of particle,

which render them particularly valuable as pigments owing to the increased covering power obtained.

I have found that when an oxidizing agent such as air is so completely diffused in the electrolytic bath as to be in contact'with all the reacting agents, the product obtained consists entlrel of ferric oxide, and retains all the desirab e hys'ical characteristics of A the electrolytic oxides.

In orderthat a clearer understanding of my invention may be had, attention is hereby directed to the accompanying drawing illustrating, diagrammatically, one possible form of apparatus whereby my process may be carried out,the container being shown in vertical sectio Referring to the drawing and as anexample of my process, in a suitable container 1 there is placed a bath 2, which is composed of an ionizable salt in solution, and inwhich is placed a plate of iron 3 to serve as the anode, and a second plate 4 of any conducting material to serve as the cathode. At the in the form of fine bubbles 8, so as to perme- .ing to the following equations, assuming the use of sodium sulphate as the salt in the electrolyte The sodium sulphate is electrolyzed to sodium hydroxide and sulphuric acid. The sulphuric acid dissolves the iron at the anode forming sulphate of'iron, and this sulphate of iron combines with the sodium hydroxide formed at the anode and oxygen from the 80 introduced air with the direct formationof ferric oxide.

The sodium sulphate is thus regenerated and is separated from the ferric oxide by filtration and returned to the bath, thus rendering the rocess continuous. The ferric oxide is 'drie and appears as a reddish brown powder which is seen under the microscope to be in an extremely fine state of division, practically approaching col- 9o loidal condition. It is this fineness which gives to the product its intensity of covering power. This product is a pigment .of exceptionally high quality and commercial value.

Since many different salts may be used in the electrolyte and since -many different forms of iron may be used as anodic material, and as many other changes in operation may be employed without departing from 100 the scope of my invention, it is intended that all matter contained in the above description or illustrated in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What I claim is v 1. The process of producing ferric" oxide, which consists of electrolyzing an ionizable salt solution in thepresence of an iron anode and an oxidizing agent.

2. The process of producing ferric oxide, which consists of electrolyzing an ionizable salt solution in the presence of an iron anode and air. v

3. The process of producing ferric oxide, which consists of acting upon iron in the presence of air with the products of electrolysis of the solution of an ionizable salt.

4:. The process of'producing ferric oxide, which consists of electrolyzing sodium sulphate in solution in the presence of an iron anode and an oxidizing agent.

5. The process of producing ferric oxide, which consists of providing an electrolyte, consisting of an ionizable salt solution, providing an iron anode and a conducting cathode in said "electrolyte, and si1nultane ously establishing electrolysis, and permeating the bath with an oxidizing agent.

6. The process of producing a ferric pigment, which consists of producing hydrated ferric oxide in an electrolytic hath, remov- ,ing the hydrated ferric oxide so produced from said bath and drying said oxide.

as 7. The process of producing hydrated meegeor ferric oxide, which consists of electrolyzing sodium sulphate in solution in the presence of an iron anode and simultaneously con-' ducting air into the-lmth so asto ditfuse over the reacting surfaces.

8. The process of producing ferric oxide,

which consists of oxidizing ferrous hydrate with air at the oint and time of formation in an electrolytic bath, and removing said hydrate from the bath and drying.

9. The process of producing ferric oxide,

which consists in passingan electric current HAROLD F. SAUNDERS.

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