US1814568A - Process for volatilizing phosphorus and potash and for producing potashbearing phosphoric acid - Google Patents

Description

Patented July 14, 1931 ROBERT D. PIKE, or OAKLAND, CALIEQRNIA m ra s 9 ee -seam PH BH N POEASH N FOR a r-WW ere Barents "rnosrnoaic Adria No Drawing.

This invention relates to the production of a potash bearing phosphoric acid and a. method of producing the same, preferably from phosphaterock and VVyomingite rock. i In southeastern Ida hooccur large quantities of phosphate rock, and in southwestern 'Wyoming, about'twdhun'dred miles distant occurs a" large tonnage of a"hig h'- grade Leucite rock containing about eleven per cent. (11%) ofKOfaridknown as w oniingite. These materials can be cheaply assembled at one point, and my present nvention has for its object to provide a cheap process for producing from these a potashr rich phosphoric acidby volatilizatio'nin a coke-fired blast furnace. WVlie'reas myinvention is particularly adapted to the treatment of Wyomingite and? phosphate rock, it will be understood that it nay equally well suited for use of other, similar finateri als.

It is a well-known fact that it is ossible 'to volatilize"potash and phosphorus from mixes of phosphate rock, a potash-bearing silicate and coke, in the electricfu'rnace. It has also been proposed (United States Patent Number 1,592,757), that a'colre-fire'd blast furnace be used for this purpose, using a mixture of one partlphosphate rock and about two parts of lVyoiningite,'with coke; but lit was found necessary, according to this patent, inorder to volatilize the potash from such a highly siliceous mixture, to inject salt or calcium chlorid at the tuyeres.

There are several important objections to the last-named procedure, some of which are:

l. The formation of hydrochloric acid which passes over with the top gas from the'furnace;

2. The relatively large amount of slag which is formed per unit of valuable plant food volatilize dy' I 8. The highly siliceous nature of the slag,

my discovery A one part phosphate rock and seven tenths Application filed ldfovember 14, 1927. Serial No. 233,325.

ence is objectionable in a potassium" ph'os- '1:

phate which will'u's'uallybe'sold on a chlorine-free basis. i

My invention consists in the substantially complete volatilization of phosphorus'and potash from mixtures of phosphate rock andlvyom'ingite' or similar'materials in'a coke-fired 'blast'furnacewith 'a basic fiiii'd and with the production of afume Wlllbll will yield after oxidation and humidification a which -is liquid under the usualco'nditions of precipitation Cottre'll 'precipi eator. "The present process 'is preferably carried out in connection with my processfor volatilizing phosphorus, concurrently filed, be-

ingYSe rial Number 238,323, in which abla'st furnaceis employed which uses'a' blast of air enriched with oxygen, and is based on that if I charge a mixtureof to eight-tenths part vWVyomingite into such a furnace, together with from seventy to -eigh typoun'dsof coke to every one hundred pounds of phosphate rock so charged, I can 5 effect a substantially complete volatilization' of both the phosphorus and potash i n the charge withoutthe addition of'any chemicalsto promote volatilizationof the latter.

As a result of such volatilizat'ion, the "fume which is collected'in'tlie Cott'rell tor orby th rsuitable" means contains from .2' to .3 pounds -K per pound P 0 and is liquid as collected," and will flowout of 'thefcollector' or precipitator.

' The residual in the presence 'potash bearing phosphoric precipitagas is free from injurious corrosive substances, and may be employed as a fuel gas. I have found that if the ratio of K 0 to P 0 goes much over .3 to 1, the viscosity of the acid rapidly increases, so as to finally become unmanageable at ordinary temperatures of collection. The phosphoric acid collected by my process, containing as it does from .2 to .3 pounds K 0 per pound of P 0 is very valuable for preparing fertilizer com ounds, and my method of making it is so 0 cap as to constitute a revolution in the art of producing phosphoric acid.

7 I have found that for the successful carrying out of my process in the coke-fired blast furnace, the following general conditions have to be observed:

1. The conditions in the hearth and bosh of the furnace must be strongly reducing;

2. The charge should be so proportioned as to give in the slag after complete elimination of K 0 and P 0 an excess of molecules of bases over molecules of acids of from ten to thirty per cent. (considering alumina as an acid) 3. The temperature of the slag should be from 1450 to 1500 (1;

4. The slag should remain in the hearth of the furnace not less than two hours (and preferably over four hours), so as to give time for complete elimination of both the potash and phosphorus.

As a specific example of carrying out my process, I charge a blast furnace with one part of phosphate rock and with eighttenths parts of \Vyomingite and .7 parts coke, giving a slag of about the following analysis:

Per cent S10 39. 7 A1 0 11. 9 CaO 43. 0 MgO 5. 4:

The furnace is blown with an oxygenated blast at 650 C. containing 30% of oxygen by weight. The slag is flushed every three to six hours. The eliminations of phosphoric acid and potash are both above 85%, or substantially complete, and the ratio of K 0 to P 0 in the acid which is collected from the top gas is about (after oxidation and humidification), .29 to 1., which insures 'a good fluidity of the acid at the temperature of collection. It will be understood that the top gases as they issue from the top of the furnace, contain fumes of K 0 and P 0 and of phosphorus. The latter has to be burned to P 0 in any suitable manner by the admission of air. The air so admitted to burn the phosphorus will usually contain enough moisture for the formation of ortho phosphoric acid with the P 0 present; but if the air happens to be so dry as to be deficient in moisture for this purpose,

. the deficiency must be made up by introducing moisture into the gases before they enter the precipitator.

It will be understood that many of the details concerning proportions, temperatures, etc., are subject to considerable variation without departing from the spirit of my invention, as disclosed in the appended clalms.

Although I have specified the use of Wyomingite, it will be obvious that any potashbearing silicate may be employed, and that if necessary the composition of the slag can be controlled by addition of other fluxing materials, as, for example, lime stone or dolomite.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. The process for the substantially complete volatilization of phosphorus and potash from phosphate rock and \Vyomingite, which consists in charging into a coke-fired blast furnace one part of phosphate rock with not more than eight-tenths part of \Vyomingite, together with the necessary amount of coke for furnishing heat and a strongly reducing condition in the hearth and bosh of the furnace, flushing the slag from the furnace after a sufiicient time of residence to insure the substantially complete volatilization of phosphorus and potash, adding air to the furnace top gases to oxidize all the phosphorus they contain to P 0 and sufficient moisture to convert P 0 to ortho phosphoric acid, and collecting the phosphoric acid and potash.

2. The process of extracting potassium and phosphorus from potassium-bearing and phosphorus-bearing rocks, which consists in volatilizing the potassium and the phosphorus compounds by smelting the rocks under reducing conditions in a coke fired blast furnace, the charge being so proportioned that the slag contains an excess of basic molecules over acid molecules, treating the gases produced by the smelting op eration to cause the formation of an acid compound of phosphorus and potassium, and thereafter recovering such compound from the gases in liquid form.

3. The process of extracting potassium and phosphorus from potassium-bearing and phosphorus-bearing rocks, which consists in volatilizing the potassium and the prosphorus compounds by smelting the rocks under reducing conditions in a coke fired blast furnace, the charge being so proportioned that the slag contains an excess of basic molecules over acid molecules, oxidizing and humidifying the gases to form ortho phosphoric acid and potassium phosphate, and simultaneously collecting these compounds.

4t. The process for the substantially complete volatilization of phosphorus and potash from phosphate rock and a potash-bearwhich consists in charging into a coke-fired blast furnace one part of phosphate rock with not more than eight-tenths part of potash-bearing silicate, together with the necessary amount of coke for furnishingheat and a strongly reducing condition in the hearth and bosh of the furnace, flushing the slag from the furnace after a sufficient time of residence to insure the substantially complete volatilization of phosphorus and potash, and recovering said phosphorus and potash.

5. The process for the substantially complete volatilization of phosphorus and potash from phosphate rock and vVyomingite, which consists in charging into a blast furnace fired with solid carbonaceous fuel, one part of phosphate rock with not more than eight-tenths part of Vyomingite, together with the necessary amount of solid carbonaceous fuel, for furnishing heat and a strongly reducing condition in the hearth and bosh of the furnace, flushing the slag from the furnace after a sufficient time of residence to insure the substantially complete volatilization of phosphorus and potash, adding air to the furnace top gases to oxidize all the phosphorus they contain to P 0 and sufiicient moisture to convert P 0 to ortho phosphoric acid, and collecting the phosphoric acid and potash.

6. The process of extracting potassium and phosphorus from potassium-bearing and phosphorus-bearing rocks, which consists in volatilizing the potassium and the phosphorus compounds by smelting the rocks under reducing conditions in a blast furnace fired with solid carbonaceous fuel, the charge being so proportioned that the slag contains an excess of basic molecules over acid molecules, treating the gases produced by the smelting operation to cause the formation of an acid compound of phosphorus and potassium, and thereafter recovering such compound from the gases in liquid form.

7. The process of extracting potassium and phosphorus from potassium-bearing and phosphorus-bearing rocks, which consists in volatilizing the potassium and the phosphorus compounds by smelting the rocks under reducing conditions in a blast furnace fired with solid carbonaceous fuel, the charge being so proportioned that the slag contains an excess of basic molecules over acid molecules, oxidizing and humidifying the gases to form ortho phosphoric acid and potassium phosphate, and simultaneous- 1y collecting these compounds 8. The process for the substantially complete volatilization of phosphorus and potash from phosphate rock, and a potashbearing silicate, which consists in charging into a blast furnace fired with solid caring silicate,

bonaceous fuels one part of phosphate rock v with not more than eight-tenths part of potash-bearing silicate, together with the necessary amount of solid carbonaceous fuel for furnishing heat and a strongly reducing condition in the hearth and bosh of the furnace, flushing the slag from the furnace after a suflicient time of residence to insure the substantially complete volatilization of phosphorus and potash, and recovering said phosphorus and potash.

ROBERT D. PIKE.