US1291751A - Process for making alkaline permanganates, chlorates, and hydrogen. - Google Patents

Description

hing Alkallne Penna nganates,

mas orrica THEODORE J. BREWSTEE, OF NEW YORIL'N. Y.

No Drawing.

To all whom it may concern:

Be it known that I, THEODORE J. Bnnws'rnn, a citizen of the Unit-ed States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Processes for Mali Chlorates, and Hydrogen, of which the following is a specication. o

The object of my invention is to so im prove the present known manner at making permanganates of the alkaline metals, and to provide a method ofmaking; them so that commercial use may result of the process.

Alkaline permanganates hr .e previously been made by heating manganese ore with an alkali, sometimes with the addition of an oxidizing agent to increase the yield, thus forming the mangauate of the metal in question. This manganate would then be ordized to permanganate either by boiling, with Water which causes a precipitation of manganese dioxid, or by oxidation by means of the electric current. Uther means of converting manganates to permanganatcs include treatment with chlorin. These various processes for making the manganates and permanganates are open to the obj ectio r into the chemical l1l(lLl$-" that they do not fit trial conditions Well enough so that a cheap product can be made. I

My invention provides for the utilization of cheap raw materials, and provides for the return to the process of all products intermediate to the production of pei'nuinganates and the product-ion of valuable by-prialucts as Well, so that permanganate of potash or soda. may be made economicall The process starts with muriate of pot-ash, which is available in large quantities, or with common salt, in the case that the permanganate of soda is Wanted; The chlorid of the alkali metal is dissolved in Water and subjected to the action of electricity in the Well known manner, whereby chlorin and the hydroxid of the alkali metal is formed. I then evaporate the product of the electrolytic action Which consists of a caustic alkali containing some undecomposed chlorid,

whereby the most of the chlorid separates out from solution and is returned to the process. The caustic solution, which may be caustic soda or potash is then mixed with oxide of manganese, preferably Well ground to a fine Specification of Letters Patent.

Patented Jan. 21, 1919.

Application filed Qctober .7, 1917. Serial IZo, 19?,01'7.

powder, and I then heat the mixture until dry.

As the material forms some lumps in this proc ss. I grind the product to as fine a powder as pi sible, then heat it to atemperature best suited for the reactitai, which usually above 360 degrees but under a red heat, allowing air to he in contact with the powder, so that oxidation to the manganate an ta he place to the best advantage. Mixing While calcining is heenlieial. I calcine until a sample taken from time to time and analyzed shears that there is being formed 1U) lllk'li"? llliliill illliiif'.

The L rill-r is then cooled, and leached with. Water. i." solution consists of the caustic alkali and maugauate ther with a small amount of chlorid. "T solution is then treated with an excess of chlorin in such a vay that the chloi'in is in excess continually, and the solution is preferably hot. This manner of treating results in the production of little or no hyptuwhlorite, but on the cont ary the it'lllsl'lc alkali is converted into chlorid and chlorate, and the manganateis converted into permanganate.

The re: ctions are practicall quantitative i hlioth cases. For example, one molecule of alkaline manganate reacts with one atom of ,chlorin forming one molecule of alkaline chlorid and one molecule of alkaline permanganate. In the case of the caustic alkali, siX molecules of this react with six atoms of chlorin, forming five molecules of alkaline chlorid and one oif' alkaliue chlorate. hen the chlorination is complete, the solution contains-ran alkaline ch orid. chlorate, and permanganate besides a trace oi ohlorin.

The latter is boiled off or posed of, and the solution is concentrated and the separation into its constituents made by means oii' fractional crystallization by Well known methods. The alkaline chlorid returned to the process, the alkaline chlorate and permanganate are ready for sale.

All of the manganese oxids are not consumed in the calcining operation with the formation of manganate, but remain after the calcined powder has been leached with Water. These oxide are returned to the therwise distain manganese in sutiicient quantity to make the operation pay.

\Vhen oxids of a lower degree of oxidation than the dioxid are used, it usually requires a longer period of calcining to obtain a good result, but otherwise the operation is the same as when the dioxid 1s used. Practically the .whole oithe manganese can be converted into permanganates,

The electrolysis of the alkaline chlorid produces hydrogen as well as ehlorin. This hydrogen can be used for many purposes, such as the h 'drogi. nation of oils, ketones, manufacture of ammonia, cfyanamid, etc. It is produced in more or less high purity according to the type of electrolytic cell used, and the care in the process. Usually it can be had ninetysve per cent. (95%) pure or better.

The following example shovvs how the processmay be Worked: Ten parts of muriate ot' potash is dissolved in thirty parts water, and it the muriate of potash contains any lime, enough carbonate of potash is added to precipitate the lime as carbonate, and the solution is filtered and ted into an electrolytic cell at the best speed suitable for the operation of the cell. The action of the electrolytic current is to decomposethe n'uiriate of potash into .the alkali metal and ClllOl'lH. In a well constructed cell, it is possible tOTGlI'lOVB the chlorin as it forms ninety (90) to ninety-eight per cent. (98%) pure, and from the cathode, the al- -kali metal unites with Water as soon as formed with the forn'iation of caustic alkali and hydrogen.

The latter escapes also ninety (-90) to ninety-nine per cent. (Qty/ lpine, according t'othe conditions. In this case, caustic potash is formed and is removed in the solution that'flows'from the cell. This solution Will contain some undecomposed chlorid, as it is not customary to operate the cell in a manner that. all of the chlorid is converted into caustic. The solution may have the follow ing composition, for example SlX parts caustic potash, two parts chlorid o1" potash, and

thirty parts water.

This is evaporated until there remains six parts water, whereupon practlcallyall of the chlorid separates out during the oper ation, and is returned to the process.

. The strong potassium hydroxid solution containing sixparts caustic potash is mixed with nine parts of finely ground oxids of Any lumps are broken up during the drying, and when the Whole is dry, the product is ground as finely as possible in a mill, and then heated'wlnle bemgexposed to the action of air unt11'a,sample Withdrawn from time to time and analyzed shows that no more manganate of potash is being made.

The heating usually of one to four hours is enough, and the temperature usually chlorate of potash.

for re-use.

'The solution is then treated with chlorin in a manner that there is continually an excess of chlorin, thereby avoidingtheformatlon of hy'pochlorites. The chlorination of the solution results in the formation of permanganate of potash, chlorid of potash, and Any excess chlorin which -may be dissolved in the solution is removed by boiling or other means, and the potash salts are-separated from each other by means of fractional crystallization, the methods of which are Well known. The chlorate ofpotash and permanganate are now finished products, While the chlorid of potash is returned to the process.

In some cases it is desirablet o form the permanganate with a minimum amount of chlorate, since the separation of these products presents some diiiiculties. In this case,

the manga'nate solution which contains also a caustic alkali is treated Withonly the amount of chlorin'necessary tooxidize to the permanganate. This is easily done on'a manufacturing scale by measuring the chlorin by passing it through a meter into an analyzed solution of the manganate, Where it is absorbed. In this reaction, a portlon o f the chlorin reacts With the. caustic alkali torming a hypochlorite, While the-balance oxidizes directly the manganate to' the per-' manganate. If this solution is then care. fully neutralized with hydrochloric acid, the hy 'iochlorite is decomposed With liberation ofchlorin and the unoxidized manganate is then converted into permanganate without appreciable amounts of chlorates being formed. The resulting solution will contain practically nothing but the chlorid and permanganate of the alkali metal, the separation of which is easily performed by.

means of fractional crystallization by known methods. I

There are cases where gin the process with a caustic alkali instead of an alkaline chlorid, and in this case" it is desirable to recover the excess caustic alkali To accomplish this result,itis desirable to usecaustic potash insteadof caustic soda, and to prepare the manganate in the manner given. The manganate solution, which contains caustic alkali, may be converted into the permanganate form by either of two methods, the choice of which is made according to local conditions. v v

' The first method consists of diluting the manganate solution to about five (5) to'ten per cent. (10%) strength and boiling, where- Well it is desirable to'be v answer by the manganate is converted into perman ganate according to the following reaction:

' roduct substaniiallv as described.

The manganese dioxid is filtered oh and re turned to the process, and the permanganate starting the operation is advisable.

solution is evaporated and cryst-allized in the regular manner. The mother liquor of the crystallization contains much caustic alkali and is returned to the process to be used in place of fresh materials iii-the preparation of the calcined product.

Thei'seoon'd method of conversion of man-- ganate to permanganate consists of sub3ectlng'the manganate to the action of the electric current in an electrolytic cell. In this operation practically the Whole of the man ganate can be converted into permanganate according tothe reaction: I

2K MnO +H O+Ux=2KMnO +2l0H.

reducing action is minimized. The addition of a small amount of permanganate before The electrolysis may thus beperformedina simple cell without the use of a diaphragm. The product of the electrolytic action consisting of an alkaline solution of 'p erinanganate is concentrated iind' crystallized in the regular way, the rriother' liquor of the crystallization being returned to the process. Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A process of making alkaline manganates conslstmg of mixing oxide of mariganese with an alkali solution, evaporating name to this specification in the to dryness, grindingcalcining. in presence of air or oxygen, and leaching the calcined 2. A process of making alkalinepermanganates consisiing of mixing OXldS of mananese with a solution containin an alkali '3 7 evaporating: to dryness, grinding, calcining inthe presence or air or oxygen, the product with Water, and. treating the solution with chlorin, substantially as described.

3. A process of making alkaline permanganate-s and chlorates consisting of mixing oxide of manganese with a solutwn contaim ingren alkali, evaporating to dryness, grinding, calcining in the presence of air or oxygen, leaching the product with w ter, and treating the solution with chlorin, substantially as described.

A process oi? making alkaline penned zanates consisting of mixing a solution of a caustic alkali with manganese oxide, evaporating to dryness, grinding, calcining in the presence of air or oxygen, leaching the calcined product; with water, treating the solution with chlorin and hydrochloric acid, substantially as described.

A process of making alkaline perinan '"anates consisting of mixing onids of inananese with an alkali solution, evaporating o dryness, grinding, calcining in the presnce of air or oxygen, leaching; the calcined product with Water, boiling the Solution, and crystalizing, substantially as described.

6. A process of making alkaline pennanganate consisting of mixing: oxide oi" inanganese "with an alkali solution, evaporating to dryness, grinding, calcining in the presence of air or oxygen, leaching the calcined product with water, subjecting the resultingsolution to electrolysis, boiling the solution and crystallizing, substantially as described.

In testimony whereof I have signed my iresence of two subscribing witnesses.

THEODORE J. BREWSTER.

leaching