US1223350A - Method of deflocculating solid materials. - Google Patents

Description

'5. G. ACHESON.

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E'. G. ACHESON. MAETHQD 0F DEFLOCGULATING sono MATERqALs.

APPLICATION FILED IAN. 11| 1917.

' Patented Apr. 24, 1917 2 SHEETS-SHEET 2.

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EDWARD UNITED srn'rns PATEN'r .gornion To all whom z't mag/concern.' Y Be it known that I, EDWARD GooDRIoH AC1-nasen, a citizen of the United States, re-

siding at New York, in the county of New York, and State of New York, have invented certain new and useful Improvements in Methods of Deocculating Solid Materials, of which the following is a specification.

This invention relates to methods of deflocculating solid materials, such as graphite, lampblack, amorphous pigments or the like. It is now well understood in the art that such materials, when rubbed, ound, or subjected to a process of attrition 1n presence of so-called delocculating agents are ultimately reduced to a state of extreme subdivision, as a result of which a -greater or less proportion of the particles become permanently suspensible in water and capable of diffusing therethrough, and may by appropriate treatment be transferred to and suspended in vehicles other than water, for 'example mineral oils, etc. The delocculating agents above referred to comprise tannin and tannin-like substances, and other organic bodies or products having similar effects. Certain methods of deiiocculating amorphous bodies and utilizing the deiocculated product are disclosed in my prior United States Patents Nos. 7 22,7 91; 843,426; 844,989; 875,881; 895,068; 911,858; 981,882; 964,478; 966,686; 986,798; 1,080,872; 1,082,386; 1,201,994. i

According to the present invention, the deocculation of amorphous bodies is accomplished by a novel method, the essential fea.- ture of said method being that the amorphous substance, mixed with the deflocculating agent or an aqueous solution thereof, is subjectedV to a number of distinct and separate rubbing operations during which the particles of the mass are subjected to attrif' tion, with'intermediate periods which may be defined as periods of relative rest, in the sense that during such intermediate periods the individual particles of the charge are not subjected to an active or intensive attrition or rubbing. Y

The invention may be carried out in apparatus of various types, and may be operated either according to the so-called batch system, or continuously or semi-continuously in the sense that the charge is introduced into the mill and is discharged'therefrom either continuously or from time to time.

GooDRIcH AcnEsoN, or NEW- Yonxjmyanssenon Tomlinson couronne rIoN, or NEW YORK, N. kY., AconronATIoN oF DELAWARE. Y

nin'rnon or DEFLoocuLn'rINe s011113` MATERIALS;

Patented lAnwalt24, i'.

Application nled January 17, 1917. Serial No. 142,361.

Certain types of apparatus which may be used for carrying the invention into effec-t are diagrammatically illustrated in the accompanying drawings.

Referring to said drawings,-

Figure l represents in vertical section a simple form of mill capable of being operated in accordance with the invention;

F ig. 2 is a similar view of a modified form of mill capable of continuous operation; and

Fig. 3 is a similar view of a further modification, the mill being of the vertical type capable of continuous operation.

Referring to Fig. 1, 1 represents a driven roll, which may be` of iron or steel covered externally with canvas or other suitable fabric 2.` This roll'is mounted parallel to but out of actual contact with the base plate 3, a suitable clearance', (sayonesixteenth` to oneeighth inch or somewhat more) being provided between the roll and the plate. The roll is preferably mounted in a hopper-like receptacle indicated at 4, is carried upon a shaft extending through the end Walls of the hopper, and is arranged to be driven by application of any suitable power at moderate speeds, say ten to sixty revolutions per minute. The roll and its mounting should be sufficiently rigid to withstand the heavy pressures involved in the operation. In practice the graphite or other material to be deflocculated is mixed with the proper proportion of the deiocculating agent in aqueous or ammoniacal solution, the mixture forming a stiff paste of the character disclosed in my prior patentsabove referred to."

In the case ofgraphite a suitable paste Will contain approximately 34 to 38 per cent. of total moisture. rIhis paste, indicated at 6, is charged into the hopper at Aone side of the roll, and by the revolution of the latter in the proper direction' is transferred beneath the roll to the other side of theV hopper. After a suitable time interval the directionI of rotation of the roll is reversed, and the material is again transferred beneath the same, this operation being repeated as often as may be required to secure the desired degree or percentage of deliocculation. For example, it was found in one specific instance that passages of the charge beneath the roll, a four-minute interval being permitted between the completion of one passage a-nd the beginning of the next, suced to deflocculate approximately ve per cent.

of the graphite-in the charge. lThe deocculated material may if 4desired be removed in` aqueous suspension, and the residue retreated, as fully explained in the prior patents above mentioned; o`r for certain a plications such separation may be omit A rolls-being preferably so mounted as to pro- 20 vide a sli ht clearance from the lowerplate 9 but awiping contact with the upper plate 8. 10 represents the charging hopper. -The rolls driven bysuitable gearing (not shown) in the direction indicated by the arrows, subject the charge to a series of rubbings orperiods of intense attrition, alternating with periods of relative rest during which the charge remains between the rolls. By vadthe spacing between the rolls the justiong peri -of relative rest may of course be varied as desired. By mounting the rolls in wipingl contact with the upper casing plate any tendency of the paste to follow the rolls toward the charging end of the mill is easily overcome.

A further modification of a vertical type is illustrated in Fig. 3. In this figure the casing is-constructed with plane sides 11, with which the two sets of rolls, 1 and 1, are mounted in wiping contact and in superposed series. Inasmuch as the attrition occurs in this case between two moving surfaces, instead of between a moving and a stationary surface as in the constructions previously described, it is desirable that the two sets'of rolls should be driven at differing peripheral speeds in order to intensify the rubbing action. For example, the rolls 1 may be driven at about 15-20 revolutions per minute, and the rolls 1a vat a somewhat higher rate, say 20-30 revolutions per minute, these figures being given however merely by way of example. In this construction it is referred to provide above each set of ro @except the uppermostor feeding rolls a rid w ich may comprise a number vo sti iron rods 12, say three-eighths inch in diameterand lying parallel to each other at two to three inch intervals, said rods extending between the side plates of removable iron frames 13, which 1n turn rest upon angle-bars or equivalent supports 14. The

purpose of these gridsv is to retain the paste" 1n the spaces intermediate the rolls for theof intense attrition may be necessary to.

aord time for a certain penetration of the defiocculating agent into the substance of the minute masses which are to be deflocculated, the surface portions of these minute masses being rubbed ofor removed during the ensuing period ofattrition. Whatever the explanation maybe, the fact has been clearly demonstrated that the deflocculationproceeds most rapidly when the operation is subdivided as described above into more or less definite and distinct periods of attrition and relative rest, irrespective ofthe means employed for accomplishing such subdivision of the operation.

A method of defiocculating solid ma# terials, consisting in subjecting said mal terials, mixed with a delocculating agent and in paste form, to alternate periods of attrition and relative rest, until the desired percentage of deflocculation is attained.

- In testimon whereof I affix my signature in presence o two witnesses.

EDWARD GOODRIGH ACHESON.

Witnesses:

LELIA M. TINSLEY, A. GoLDm GOLDMAN.

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