Mixer for solids and liquids

May 22, 1956 e. pomerleau 2,746,728

MIXER FOR SOLIDS AND LIQUIDS

Filed July 20, 1953

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ATTORNEY

United States Patent Office

2,746,728

Patented May 22, 1956

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MIXER FOR SOLIDS AND LIQUIDS

Edward Pomerleau, Williamstown, Mass.

Application July 20,1953, Serial No. 368,996

Claims. (Cl. 259—4)

This invention relates to the mixing of solids and liquids, and particularly to the intimate mixing of various solids of finely dispersed nature, such as are used in certain animal feed mixtures, with acidic materials, such as phosphoric acid; or for the reaction of solids with liquids, such as the reaction of limestone with phosphoric acid; although not limited thereto.

In many manufacturing processes, it is necessary to mix a highly corrosive substance with a solid material, or a highly abrasive solid with a liquid. In such instances, the use of mixing devices with moving parts is quite difficult because of excessive wear, and extraordinary maintenance requirements of such equipment. Furthermore, many of the mixtures are quite pasty and would require large amounts of power and long periods of time in order to insure complete contact of each solid particle by the liquid with which it is to be admixed.

In the manufacture of certain animal feed mixtures, it has been necessary to add to the feeds acidic materials, such as phosphoric acid. With conventional mixing methods and apparatus, it is difficult to obtain a fine dispersion of acid in the feed mixture. In addition, the handling of small amounts of liquid with large quantities of feed tends to give compositions which are susceptible to caking.

In other instances, it is desirable to carry out a chemical reaction in addition to the normal mixing of two components: for example, in the manufacture of dicalcium phosphate, it is desirable to react solid calcium carbonate with phosphoric acid. Another example of a reaction contemplated by the teachings of the present invention is the hydration of lime.

In each of the aforementioned instances, it is necessary that a good distribution of the liquid and solid be secured in order that a uniform product will result, or in order that a chemical reaction will be driven toward completion. It is manifest that particle size of the solids fed to the mixing apparatus is important, and the finer the distribution of particle size, the more even will be the distribution, and the more quickly the chemical reaction will take place if such is contemplated.

The present invention has for one of its objects an improved apparatus for mixing solids and liquids, whereby predetermined quantities thereof may be intimately admixed, and in a constant ratio, if such is desired.

Another object is to provide an apparatus of the class described which is characterized by simplicity and inexpensiveness.

Another object is accuracy of control.

Still another object is the provision of an apparatus for mixing solids and liquids in the aforementioned manner which is characterized by great durability, utilizing in the mixing operation itself no moving parts whatever.

With the foregoing and other objects in view, the invention resides in apparatus embodying certain details of construction and arrangement of parts shown on the accompanying drawings. It is to be understood, however, that the present embodiments are shown for purposes of illustration only, and not for the purpose of limiting the invention, as various changes will occur to persons skilled in the art; and all such modifications within the scope of the appended claims are contemplated.

In the drawings:

Figure 1 is an elevational view of apparatus which has been constructed in accordance with the teachings of the present invention; and

Figure 2 is an enlarged fragmentary elevation, partly in section.

Referring more particularly to the drawings, the numeral 2 designates a vertically disposed solids supply pipe which is substantially cylindrical in cross-section and of substantially uniform diameter to a point indicated at 3 in Figure 2, whereat it is provided with a lower frusto15 conical or outwardly flared extension 4.

Disposed concentrically of the vertical pipe 2 is a larger air supply pipe 6 which is substantially cylindrical in cross-section and of substantially uniform diameter to a point indicated in Figure 2 at 7, from whence it merges 20 into an inverted frusto-conical portion 8.

It will be noted that the cylindrical portion of the outer pipe 6 terminates considerably above the cylindrical portion of the inner pipe 2.

As shown, the lower end of the inverted frusto-conical 25 portion 8 of the outer pipe 6 terminates at 9, at which point it merges into a depending cylindrical portion 10.

A substantially circular manifold 15 is shown as being horizontally disposed at a position which is intermediate the ends of the inverted frusto-conical portion 8 of the 30 outer pipe 6 and concentrically with respect to the latter. This circular manifold 15 is supplied with a suitable liquid through a pipe 16.

To the substantially circular manifold 15 there is connected a series of depending tubes 17, each of which 35 extends slightly below the lower end of the outwardly flared or frusto-conical extension 4 of the inner pipe 2 and carries a spray nozzle 18 which projects through the wall of the cylindrical portion 10 of the outer pipe 6 and adjacent the lower extremity thereof.

As shown, the spray nozzles 18 are inwardly directed in order that the liquid therefrom will impinge upon the solids falling from the inner pipe 2 and also the air from the outer air supply pipe 6.

A blower 20 is connected to the air supply pipe 6, the ⁴⁵ same being constructed and arranged to supply air at sufficient pressure to obtain a venturi effect between the outer pipe 6 and the inner pipe 2. It will also be noted that a similar effect is obtained within the solids supply pipe 2 because of its outwardly flared lower extension 4. ⁵⁰ From the foregoing description, it will be appreciated that, when solids to be mixed are introduced to the vertically disposed inner pipe 2 (as by means of a hopper, conveyor, etc.), it will freely flow until it emerges from the lower end of the outwardly flared lower extension 4, ⁵⁵ and that this action will be accelerated by air from the blower 20 as it moves past the lower end of the inverted frusto-conical portion 8 of the outer pipe 6, the flow of air continuing downwardly along the outside of the lower cylindrical portion 10 thereof, to be discharged therefrom at an elevation which is lower than the lower extremity of the outwardly flared lower extension 4 of the inner solids supply pipe 2.

It will also be appreciated that, in addition to the very _6g effective distribution of solids and liquids to obtain a uniform product, the apparatus is characterized by employing in the intermixing instrumentalities per se no moving parts whatever which, of course, greatly enhances durability.

Following are specific examples of a number of actual operations which were conducted with the apparatus of the present invention:

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Example 1

One hundred parts per minute of 86% phosphoric acid were fed into the liquid side of the apparatus through the manifold 15, depending tubes 17 and nozzles 18; and 124 parts of limestone (100% through 40 mesh) were fed into the solid side of the apparatus through the vertically disposed inner pipe 2. The resultant product was permitted to dry over-night at room temperature, and thereafter dried to 2% moisture in an oil fired kiln-type drier. The resultant product contained 18.5% phosphorous and was characterized by a pH of 5.5-6.

Example 2

One hundred parts per minute of 78% phosphoric acid was fed through the nozzles 18, and 45 parts of limestone (100% through 40 mesh) were fed through the solids feed pipe 2. The resultant product was permitted to dry in air over-night at room temperature. A considerable quantity of heat was evolved throughout the drying period. On crushing, the product was found to contain 22% phosphorous and less than 1% moisture.

Example 3

Fifty-six parts per minute of 78% phosphoric acid were fed through the liquid feeding nozzles, and 44 parts of Florida phosphate rock containing 72% bone phosphate of lime content ground to 80% through 200 mesh, were fed through the solids feed pipe 2. The mixture was aged for thirty days and dried at 150-180° C. and then ground so that 80% passed through a 40 mesh screen. The product contained 50% total available P2O5 of which 44% was available as water soluble phosphate.

Example 4

Thirty-three parts of water per minute were fed through the nozzles 18, and 100 parts of lime (100% through 40 mesh) were fed through the solids feed pipe 2. The resultant product was discharged and allowed to dry in the air. The hydrated lime produced was found to be well suited for both chemical and agricultural purposes.

Example 5

Five parts per minute of aqueous 40% phosphoric acid solution were fed through the nozzles 18; and through the solids feed pipe 2, there were fed 100 parts of an animal feed of the following composition:

Parts

Ground com 47.25

Ground oats25.00

Wheat bran 10.00

Soybean meal 16.75

Salt 1.00

Example 6

Thirty parts per minute of aqueous phosphoric acid solution were fed through the nozzles 18; and through the solids feed pipe 2, there were fed 100 parts of an animal feed of the following composition:

Parts

Ground corn 46.75

Ground oats24.50

Wheat bran 9.50

Soybean meal 16.25

Salt 1.00

Diammonium phosphate 2.00

In each of the foregoing actual Examples 5 and 6, the material produced was found to be very satisfactory as a feed for ruminants.

While, in the foregoing description and examples, air was supplied between the outer pipe 6 and the inner solids supply pipe 2, it will be well understood by those skilled in the art that other gases may be used as a dispersing agent. For example, if the solid material which is to take part in the mixing operation is subject to oxidation, the gaseous medium supplied through the outer pipe and the inner pipe 2 could acceptably be nitrogen. Moreover, the gas in the dispersion might be of such character that it could take place in the reaction itself, if such is deemed desirable, in which instance the dispersed gases could be recovered and recirculated. In certain instances, such as in the above-described Examples 1 and 2 (i. e., involving phosphoric acid in a reaction with calcium carbonate) carbon dioxide would be evolved; and this gas recovered for further use. In such instance, carbon dioxide might be used as the gas in the circulating system in order to ultimately obtain a gas containing a very high concentration of carbon dioxide. In the latter case, it would be necessary that the gas be dehydrated before use as carbon dioxide in the event a drying gas is desired, since water is also a product from the reaction.

The mixed material leaving the apparatus of the present invention may be dropped onto a suitable conveyor 21 and transferred to other processing and/or packaging operations, as desired.