US1679055A - Crystallization apparatus - Google Patents

Description

July 31, 1928. 1,679,055

v w. SEIDEL v CRYSTALLIZATION APPARATUS Filed May 16. 1927 Patented Jul 31, 1928.

1,619,055 .,UNITED STATES PATENT OFFICE.

'WALTER SEIDEL, OF LEVERKUSEN, GERMANY, ASSIGNOB TO I. G. FARBENINDUS'I'BII AKTIENGESELISCHAIFT, OF FRANKFORT-ON-EEHE-MAIN, GERMANY.

'CRYSTALLIZATIQN AIEIPARATUS. I

Application filed m 16, 1927, Serial No. 191,860, and in Germany June a9, 1026.

The present invention relates to an improved form of crystallization apparatus. ..With the crystallization apparatus and processes available at present it is difiicult to produce crystals of large size if the crystals formed have arela'tively high specific gravity compared to the mother liquor and consequently tend to settle into a compact mass at the bottom of the crystallizing vessel. Under present practice it has been found to be fairly easy to produce large crystals of substances such as sugar, potassium ferrocyanide,'sodium thiosulfate, and the like, which may be maintained in suspension in the mother liquor with little difficult but these same methods are impracticable or the production of large crystals of substances such as potassium bichromate and barium chloride and the like which are of relatively high specific gravity compared; to these mother liquors. v

The principal object ofth'e present invention is the provision of a'ri'a paratus capable of producing large crystals rom solutions of substances which form crystals of relatively highspecific ravity. The invention is, however, .not lim ted to the production of crystals of this character, and may be advantageously applied to the production of all kinds of crystals. A

The preferred form of apparatus embodyingmy invention-is shown in the accompanyvinodrawings, 0f which:

talli zing vessel and of means for imparting a rocking motion thereto;

Fig. 2 is a perspective view of the crystallizing vessel; 4

Fig. 3 is a cross-sectional view of the crystallizing vessel;

Fig. .4 is a similar view illustrating the' I operation of the device in the extreme tilted or rocked position; and

Fig. 5 is a cross-sectional view of a modified form of the crystallizing vessel.

The crystallizing vessel illustrated in Figs. 2, 3 and 4 is generally trough shapedand may be of any suitable length and comprises the end walls 1. 1, outwardly curved s1de walls 2, 2, and the upwardly arched bottom 3, these elements defining a central longitudinally extending ridge 4 dividing the vessel into the two lateral longitudinally extending chambers 5, 5. As is evident the crystallizing vessel may be constructed of ig. -1 is,a vertical end view-of the crystom 3 and side walls 2, 2, being made of a single suitably shaped piece of material as shown, these parts may bebuilt up, for instance, of wood. It is noted moreover that the s de walls 2, 2, need not be of the substantially semi-circular cross-sectional shape lllustrated and that the ridge 4 may be provided otherwise than by arching the bottom 3 and may vary in shape and height wlthout departure from my invention. In operation the crystallizing vessel is rocked from side to side,-cradlewise, preferably on an axis lying in a vertical plane passing through the peak of the ridge 4 and in or near to the peak of the ridge 4.

u A suitable apparatus for imparting a rockmg movement to the crystallization vessel is shown in, Fig. 1. The apparatus comprises supporting rods 6 pivotally secured to the crystallization vesseland to cross-arms 7 whlch are fixedly secured to the revoluble axle 8 mounted on support 15. 'Axle- 8 is provlded'with' an arm 9 which is connected by a 'pivoted link 10 to a cam device for imparting an oscillating movement thereto. The cam device shown consists of a rotatable shaft 13, a cam 12 secured to said shaft, and a shell 11 enclosing cam 12 and attached to link 10. .By rotation of shaft "13 a reciprocating movement of link 10 is produced which in turn acting through arm 9 and axle 8 produces a rocking movement of crossarms 7 and the crystallization vessel suspended therefrom by rods 6.' The particular means shown for producing. arocking move ment of thecrystallization vessel forms no vices may be substituted for it for this purpose without departing from my invention. The modification of the crystallizing vessel illustrated in Fig. 5 differs from the crystallizing vessel of Figs. 1, 2 and 3 only in that the bottom 3 is provided with a plurality of ridges 4 defining the chambers 5. 5, and intermediate chambers 5.

The principle involved in the construction of the apparatus and in its operation is that as the crystallizing vessel is rocked from side to side the mother liquor flows from side to side carrying small crystals which have been formed in suspension while the larger crystals remain in the chambers 5, -5. At each rocking of the vessel, the crystals in the higher chamber 5 are drained while the rush of mother liquor from the higher chamber 5 into the lower chamber 5- agitates the deposit of crystals therein and brings about an intimate contact between the crystals and the mother liquor. As will be apparent the continuous or repeated rocking of the vessel from side to side will alternately drain the mother liquor from the deposit of crystals in one of the chambers 5'and agitate and mix it with the deposit of crystals in the other chamber 5. The side walls 2, 2, of the vessel are shaped to prevent the mother liquor from spilling out while the bottom 3 is so shaped as to hold the deposited crystals in the chambers 5, 5, while permitting substantially all of the mother liquor to drain from side to side as the vessel is rocked from side to side. With this understanding ofthe principles involved it will be apparent that the helght and shape of the ridge 4 may vary considerably. The shape and relative height illustrated has been found to give excellent resalts with a variety of solutions. One point to be considered in shaping the ridge 4 is the agitation of the deposits of crystals in the chambers 5, 5, by the flow of the mother liquor. Fig. 3 shows the crystallizing vessel in horizontal position with a deposit of crystals in each of the chambers 5, 5, and the level of the mother liquor while Fig. 4 shows the crystallizing vessel in tilted position with the crystalsin the upper chamber completely drained. The operation of the apparatus illustrated in Fig. 5 is the same as that of the apparatus illustrated in Figs. 2, 3 and 4 excepting that each ofthe chambers 5' also holds a deposit of crystals and each of the end chambers 5, 5, must be sufliciently large to hold all of the mother liquor.

The process may be carried out upon batches ofsolution. but preferably is applied to a continuous flow, the crystallizing vessel being suitably inclined from end to end and the crystallizing solution being supplied at one end and discharged at the other end when its supersaturation is exhausted. The crystals deposited in the chambers 5,, 5, will show a tendency to move toward the lower chambers, comprises end of the crystallizing vessel with the solu- The above apparatus has been found to be especially well adapted to the production of crystals of potassium bichromate and barium chloride.

I claim: 1. Crystallization apparatus, comprising a vessel adapted to have a rocking movement imparted thereto, means dividing said vessel into two lateral chambers, said means being disposed so as to permit drainage of sub-- stantially all the liquid from the higher chamber to the lower chamber in each extreme rocked position of the vessel and to' prevent the movement of the bulk of the crystals from one chambcrto the other.

2. Apparatus as in claim .1, wherein the means for dividing the vessel into two lateral chambers, comprises a ridge-like member disposed along the bottom of said vessel.

3. Apparatus as in claim 1, wherein the means for dividing the vessel into two lateral an inwardly arched portion forming an integral part of the bottom of said vessel.

4. Crystallization apparatus, comprisinga rectangularly shaped vessel of relatively great length adapted to have a rocking motion imparted thereto, a ridge-like longitudinal member dividing said vessel into twO. lateral chambers, said ridge-like member being disposed so as to permit drainage of substantially all the liquid from the higher chamber to the lower chamber in each e;-

-treme rocked position of the vessel and to prevent the movement of the bulk of the crystals from one chamber to the other.

In testimony whereof,I affix my signa-.

ture.

WALTER SEIDEL.

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