US 2756685 A
Description (OCR text may contain errors)
July 31, 1956 J. w. HOOGENDONK 2,756,685
TRANSPORT OF METALS IN LIQUID FORM Filed Feb. 14, 1951 Iva l 9 E 11 15 E 5 L 3 F GAS \NVENTOR JOHAN W. HOOGENDONK ATTORNEYS TRANSPORT F METALS IN LIQUID FORM Johan W. Hoogendonk, Geleen, Netherlands, assignor to Stamicarbon N. V., Heerlen, Netherlands Application February 14, B51, Serial No. 210,849
Claims priority, application Netherlands March 3, 1950 3 Claims. (Cl. 10326tl) The present invention relates to the transport of metals in liquid form. As one example, the invention may relate to the transport of mercury, where the marcury has to be transported between various sections of a reaction apparatus, which sections may be at different levels. As another example, the invention may be utilized in the transport of gallium, which is in liquid form above about 30 C.
In presently known practices for transporting metals of the above mentioned type, plunger or centrifugal pumps are usually employed. In the construction of these pumps, particular attention must be paid to the sealing elements such as stufiing boxes and similar parts, owing to the toxic properties of the metals. Special constructions are required for sealing against leakages, and during operation a constant check must be made to discover and immediately to remedy any leakages which may occur.
Another drawback of customary pumping arrangements is the excessive wear to which the pump parts, including the intermittently operating valves through which liquid metal flows are subjected, this wear being partly due to the relatively high specific gravity of the metal.
The primary object of my invention is to provide an improved method and apparatus for the transport of metals in liquid form such as mercury and gallium.
A further object of the present invention is to provide an improvement in methods and apparatus for elevating metal in liquid form such as mercury and gallium without involving heavy wear of mechanical parts and with reduced risk of leakage.
To this end the present invention comprises a method and apparatus for transporting liquid metals wherein the metal is introduced into a moving carrier liquid in such manner as to be divided into droplets, and the droplets are entrained by the carrier liquid and then separated from the carrier liquid.
The method according to the present invention may be carried out by causing a carrier liquid, e. g., water to move at high velocity through a tube and by feeding the metal into the said tube, for instance through small apertures in the wall thereof, or through a feed pipe with its discharge end arranged within the said tube. On entering the liquid the metal is immediately entrained by the fast flowing liquid in the form of small droplets, the formation of droplets being due to the relatively high surface tension of the metals. Mercury, for example has a very high surface tension and has a very marked tendency to form droplets. A settling tank or other separating .device may be positioned at a desired position and the liquid including the metal droplets may then be introduced into this separating device to separate the metal from the carrier liquid.
According to a preferred manner of carrying out the present invention the carrier liquid is pumped through a venturi from a nozzle around which the metal is fed under static pressure. By this arrangement the metal is introduced into the high velocity carrier liquid where the latter passes through the venturi, the result being that aired States Patent Patented July 31, 1956 the metal is divided by the liquid into droplets and then entrained by the liquid to the desired position through a tube connected with the venturi.
It has been found that during the transport of the entrained metal the droplets will refrain from uniting when the concentration of the metal in the liquid is not too high. For example good results are obtained if the concentration of mercury in a mercury-liquid m'nrture amounts to about 5% by volume, it being preferred however, to adjust the concentration to about 3%. At higher concentrations, difficulties tend to arise as a result of some of the mercury droplets in the carrier liquid uniting into larger drops which may have such a high settling rate as to gravitate against the liquid current and collect an increasing number of droplets during their descent. In that case the operating capacity of the apparatus decreases considerably. The amount of mercury, supplied to the carrier liquid, can be varied by regulating the static pressure of the mercury feed.
As an example, it is found that amounts of about 10001500 litres mercury per hour can be easily transported upwards over a height of more than 10 metres using a pump for the carrier liquid having a capacity of 35 cubic metres carrier liquid per hour.
After being freed of the entrained metal droplets, the carrier liquid can be returned to the suction pipe of the liquid pump and advantageously re-used because with this circulation method only a relatively small amount of energy is needed for pumping up the liquid.
The metal may be washed by the carrier liquid during its ascent and the impurities washed out of the metal may be removed from the circulating carrier liquid either continuously or periodically.
Distribution of the metal through the carrier liquid may be improved by introducing a gas, preferably air, into the carrier liquid, e. g., the gas may be introduced under pressure into the delivery pipe of the pump. Thus the gas is introduced at a point upstream of the point where the liquid metal is introduced into the carrier liquid. As a carrier liquid, water is preferably employed, preferably with the addition of emulsifying agents to improve the washing action. However, other liquids, e. g., organic liquids and preferably those which will dissolve the impurities may be used as a carrier liquid.
The invention will be further explained with reference to the accompanying drawing which illustrates a sample apparatus. However, it will be understood that the illustrated embodiment is not intended to limit the invention. The true scope of the invention is to be determined from the appended claims. In the following description the transport of mercury is set forth as an example, but it is not intended that the invention be confined to this metal.
In this drawing, 1 is a centrifugal pump operating to pump 45 cubic meters per hour of carrier liquid through a delivery tube 2 and then upwardly from a nozzle 3 through a venturi 4. The mercury is fed into a downward extension of the venturi tube and is fed axially into the venturi 4 around the nozzle 3 under a head of approximately 70 cm., of mercury in the vessel 11. The water will rush through the venturi 4 and the mercury will be divided into droplets. The mercury droplets formed are approximately 3 mm. in diameter their settling velocity is so low that they are entrained vertically upwards by the water, into a rising tube 6 having a diameter of 6 cm., over a distance of approximately 8 meters. At the raised level the rising tube 6 leads tangentially into a cyclone 7 or other suitable separating apparatus. Here, the mercury droplets are removed from the carrier liquid and are discharged through the goose-neck 8 which prevents any remaining water from being carried off with the separated mercury. The separated water returns to the pump 1 through the suction pipe 9.
In the illustrated example the mercury is supplied from a reservoir 10 to the vessel 11 which is in the form of a regulating tube in which the mercury level is controlled by means of an operative connection between a float 13 and and a valve 12. The amount of mercury supplied to the venturi device can be varied by adjusting the level in the regulating tube 11. In a pipe leading from vessel 11 a valve 14 has been arranged which remains open in operation of the apparatus and is closed when the pump is stopped, in order to prevent the mercury from flowing into the nozzle 3.
Fresh carrier liquid may be supplied through the pipe 15. The aforementioned gas under pressure may be introduced through pipe 16 and may be controlled or cut-off by valve 17.
It will be understood that the temperature of the carrier liquid may be controlled so that the droplets of liquid metal will not solidify unless such result is desired.
From the foregoing description, it will be apparent that the invention makes it possible to transport liquid metal upwards over a height of many metres by entraining the metal in a carrier liquid, and this is accomplished without possibility of leakages or undue wear of parts of the apparatus. Moreover, but for the use of a carrier liquid in accordance with the present method, it would not be possible to transport liquid metal upwards over such a vertical distance by means of a low-powered pump.
1. Apparatus for transporting liquid metal comprising, a tube, the tube including a venturi section, means for supplying liquid metal to the tube in the venturi section, means for moving a carrier liquid through said tube and venturi section so that the liquid entrains the liquid metal in droplet form at the venturi section, and means for receiving the carrier liquid with the entrained liquid metal therein and for separating the entrained metal from the carrier liquid.
2. Apparatus according to claim 1, wherein the means for supplying liquid metal to the tube in the venturi section includes a regulating tube for adjusting the liquid metal level in relation to the venturi section.
3. Apparatus as in claim 1 and further including means for introducing gas into the carrier liquid in the tube before said carrier liquid passes into the venturi section.
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