413
SP. m., 0.500
Sp. gr., 0.400 FiCare i7-~-Marshmsllow Air Cells.
Considerablemore work will be required to get the relations between jelly test, viscosity, and concentration better established; but it seems clear that for marshmallow creams, or
Sp. zr., 0.350 X 64
any product requiring the illcorporation of air by agitation, the resultant viscosity of the gelatin concentration constitutes the most important single factor.
A New Colloid Mill Otto Auspitzer uiii O ~ i i n a s r cC ~ r 6 w ~ s c xWERXB c A. G., N K u ODIIRBIIKC, CZRCAOSLOYAEIA
T
HE use uf colloid mills for highly dispersing solid suhstances in liquid media or two immiscible liquids in each other has been known for Several years. The I’lauson mill in particular has found widespread application in Europe. TVhen Plauson gave publicity to it great importance was predicted for the invention. Nevertheless tho colloid mill could not gain the distribution anticipated, because the excessively high power requirement of mills of that type n-tis generally an obstacle to economical employment.
Description and Operation
a successful lrlethod Thjs is schematically represented in ~i~~~ 1, the oderherg design the material to be milled is conducted tangentially past the beaters. The Elill with the except,ion of the beating point, is empty, so *hat, in contradistinction to other typesof cofioid mills, there is no rotation of the material within the housing, pigure 2 shows the course of the material to be processed. This is pre-mixed in the tank, 6, whicli should be equipped with a stirrer. Depending on the size of this mixing tank (in a mill already set up the capacity was raised to 12,000 liters), an almost continuous mode of operation can be attained. Wlere a perfectly continuous process is necessary, the connection of several mills in series is recommended. The pre-mixed material is conducted into the mill, 1, through the pump, 5 ; from there passes a t very low velocity bet m e n the rapidly rotating beating apparatus and the ba5es or anvils (9, 10, Figure I); and then returns to the mixing bank through the connection 4. The design of this connection has been proved to be of primary importance in relation i ~ ~ : , . i , ,?-.-ioivi: ~; !* bc6icrs; io--bamer uliviii to the power consumption. If the counection is perfectly horizontal the ponrer Pigure 1~~Cormfrurtional Diagram of Oderbcrg M i l l consumption rises, beIn the course of the last six years a series of colloid mills causethefrictionfrom was constructed on the fundamental Plauson principles t h e i n t e r i o r of tlie and appreciable improvement.s were introduced. However, housing is transferred until recently tho power consumption was still very consider- to the Upper wall of able. The Oderberg Chemisehe Werke Aktiengeselischaft, the but if 3 a t Neu Oderberg, Czechoslovakia, who were using a series the connect’ion is so of Plauson mills in their operations, ascertained, through that it enobservation of the corrosion occurring on the mill housing, closes t h e p a t h in which the m a t e r i a l that a large part of the applied power was not available for would escape into the the actual work of dispersion, but was dissipated through open if no pipe were ~i~~~~ 2-magram of complete Installation the friction between the material to be ground and the sides present, the power the housing. A method Of reducing this friction to as consumption drops appreciably. Careful parallel experiments small an amount as possible was then sought,. have demonstrated that the colloid mill on the Oderberg system, with equal performance, requires only about one-seventh I Received October 27, 1927. Translated by PAULR. DIVSON. futile
of construotioll was devised.
I'VD LTST111.4L A S D ENGSNEERSNG CIIEXISTRY
414
Figure 3-Cumplete
lnsfallafiOn of Coltold Mi11
of the power necessary in the case of the I'lauson mill; in other words, in a colloid mill in which the material to he beaten is carried along the sides of the housing, six-sevenths of the applied power is wasted in internal friction. The new mill has still another advantage. I n a Plauson mill, in spite of the eccentric arrangement of the shaft, the material being processed goes through a rotary motion, the more rapid the higher the rate of revolution of the rotor. Hence only the difference between the beater velocity and the velocity of the material is effective for the actual work of beating. In the Oderberg system the material passes through the mill so slowly that the full rotation velocity of the beater arms can be made available. Figure 3 shows a cornpleied installation in which it was important that the beating he carried out nt as low a ternperature as possible; h e n c e t h e mixing tank, a$ well as portions of the pipe conveyers, is provided wit.h water cooling . C o o l i n g of tho mill itself is unnccessnry, since the material to be disintegrated remains in the mill for :in cxt.remcly s h o r t time and the bcatcrs Figure 4 E f f e c f ~of DwBLion and R a t e of and anvils are cooled Beafine upon a Procesacd Material by the contimionsly flowing matcrinl itself. The beating effect is dependent on both the rate of rot,ation and the duration of besting. Figure 4 shoivs thc influence of these factors upon the sedimentation volumc of a processed material of very high specific gravity and 50 per cent dry content, after standing 24 hours.
Vol. 20, No. 4
terials after beating in !lit! colloid inill. In the case of niinium the covering power increased proportionately with the loose volume; while 179 grams of the material ground in the ball mill were required to cover evenly a square meter of smooth sheet iron, only 76 grams af the minium beaten in the colloid mill were needed. Through processing in the colloid mill kaolin acquires properties completely lacking in the ordinary material. Thus, JXtmarz has cited the high adsorptive power of such a kaolin, making it possible to utilize such highly dispersed material in place of lycopodium for ,dusting purposes in the rubber industry. A further application of t.his mill is in the product.ion of colloidal solutions through mechanical dispersion. Plauson originally had this in view, hut it, could be accomplished only incompletely with his apparatus. Figure 6 shows photomicrographs of a sulfur dispersion prii(liiea1 iii :in (Zlerberg colloid mill, compared with the raw sulfur used. Such a preparation f o r com bating plant pests is alr e a d y on tho market under the name "Sulikoll." The new mill is also being used for the production of arsenate s o l u t i o n s , colloidal graphite, and for many similar purposes. There are numerous cases where a material can be dispersed almost to the degree of irirc colloidal s o l u t i o n s through use of the colloid mill. By varying l - ~ ~ w n i uground rn i n hati 2the duration of beating al,d the
