US3286995A

US3286995A - Apparatus for mixing and gunning slurries

Info

Publication number: US3286995A
Application number: US470967A
Authority: US
Inventors: Donald C Burklo
Original assignee: Kaiser Aluminum and Chemical Corp
Current assignee: Kaiser Aluminum and Chemical Corp
Priority date: 1965-07-12
Filing date: 1965-07-12
Publication date: 1966-11-22
Anticipated expiration: 1983-11-22

Description

Nov. 22, 1966 D. c. BURKLO APPARATUS FOR MIXING AND GUNNING SLURRIES 2 Sheets-Sheet 1 Filed July 12, 1965 INVENTOR.

DONALD C BURKLO ATTORN Y Nov. 22, 1966 D. c. BURKLO APPARATUS FOR MIXING AND GUNNING SLURRIES Fild July 12. 1965 2 Sheets-Sheet 2 INVENTOR.

DONALD C BURKLO ATTQRNEY United States Patent 3,286,995 APPARATUS FOR MIXING AND GUNNING SLURRlES Donald C. Burklo, Columbiana, Ohio, assignor to Kaiser Aluminum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed July 12, 1965, Ser. No. 470,967 3 Claims. (Cl. 259169) This invention concerns apparatus for mixing and conveying slurries.

It is known to mix solid materials, for example cementitious materials, with a liquid, for example water, in a tank to form a slurry and then to convey this slurry through pipes or hoses to the point of use, for example to where it is sprayed onto the inside of an open-hearth steelrnaking furnace, in the case of a slurry made from refractory materials.

In the past, it has been the general practice to mix such cementitious refractory slurries in a tank by means of internal paddles turning on an externally driven shaft and then to convey the mixedslurry to the point of use by means of compressed air fed into the tank. This method of paddle mixing and high pressure conveying creates several problems. For one thing, the mixing tank must be able to withstand relatively high pressures and therefore is constructed of heavy gauge steel or the equivalent. Also, there is the problem of sealing the shaftbearing against these high pressures at the point where it passes through the pressurized tank. For these and other reasons,'the industry has been looking for a simpler, less expensive, and yet efiicient apparatus for mixing and conveying slurries.

According to this invention, there has now been discovered an apparatus for mixing and conveying slurries which does not require the use of internal paddles, high pressures, or sealed tanks. The presently contemplated best mode of construction of this apparatus is given in the following description. It will be understood, however, that this description is illustrative and not limiting of the scope of the invention, the limits of which are defined in the appended claims.

FIGURE 1 is a side elevation view of an apparatus according to this invention; and

FIGURE 2 is a plan view.

The apparatus comprises a tank, generally indicated by the numeral 11, which has a cylindrical or tubular side section 12, a flat bottom section 13 of lesser diameter than tubular portion or casing 12, and a conical bottom section 15 connecting flat bottom section 13 and cylindrical side section 12. Located in the flat bottom section 13 is an outlet opening 16.

Disposed externally of tank 11 is a pump 17. While any pump adapted to handle the slurry being mixed is suitable, an air-driven diaphragm pump, such as that made by Ingersoll-Rand Company, has been found particularly suitable. Since this is a commercially available device, the details are not shown. Pump 17 is connected to outlet opening 16 in tank 11 by conduit or pipe 19. Located in pipe 19 is shut off valve 20. This valve is not essential to the operation of the apparatus, but is included for emergency ,use in the event that pump 17 or some other part of theexternal piping system breaks when tank 11 is filled with slurry.

The outlet of pump 17 is connected, through second conduit or pipe 21, to two-way valve 23. Two-way valve 23 can be turned so that the slurry is directed either into a third or gunning conduit or pipe 24 or into a fourth or return conduit or pipe 25. Pipe 24 leads through shut-.

off valve 22 to nozzle 26 through which the slurry is projected at the point of application. Pipe 25 extends into the top of the tank and has a downwardly extending 3,286,995 Patented Nov. 22, 1966 ice portion 25' which is directed generally tangentially to casing 12 of tank 11 and which terminates in discharge opening 27. Preferably discharge outlet 27 is so disposed that a stream of slurry discharged from it is directed at conical bottom portion 15 of tank 11.

In this embodiment, the apparatus is suitably mounted on wheels 28 for movement from place to place and is provided with a steering and pulling lever 29.

Located within tank 11 and attached to flat bottom portion 13, is a central tube or cylinder 31. At the bottom of cylinder 31 are located openings or holes 32 which permit passage of the slurry from tank 11 to outlet opening 16.

In operating the apparatus of the present invention, tank 11 is filled with water to a point about half the height H of the tank or, in other words, to a point above the junction of conical bottom section 15 with cylindrical side section 12. Valve 23 is then turned to direct fluid through pipe 25 and thus recirculate it back to tank 11. Pump 17 is then turned on and the water circulated through holes 32, outlet opening 16, pipe 19, pump 17, pipe 21, valve 23, pipe 25, and discharge 'outlet 27 back into tank 11. The impingement of material discharged from outlet 27 on the surface of the water in the tank causes the water in the tank to move with a circular motion about central cylinder 31. Because of centrifugal force, the circulating water is forced to the outside of the tank and rises nearly to the top of the cylindrical wall section 12. Concurrently, the water level near the center of the tank drops. When the water is smoothly circulating, the refractory material to be slurried is dumped into tank 11 and the circulation continued until the refractory material is thoroughly mixed with the water. Generally, this requires only a minute or two.

When the slurry is completely. mixed, valve 23 is turned to direct the slurry flow into pipe 24, whence it is carried to the point of use.

While the dimensions of the apparatus can be varied as desired, it has been found preferable for most eifective mixing that certain dimensional relationships between the size of difierent parts by preserved. It is convenient to discuss the size of various parts as related to the diameter D of tank 11 itself.

In the first place, the diameter D of tank 11 can be any size desired, the maximum size depending in part upon the capacity of pump 17. It has been found that a pump with a capacity of gallons per minute at a total head of 50 p.s.i. is suitable for a tank of 42 inches diameter.

The height H of the tank should be at least as great as the diameter D. The diameter, c, of the flatbottom section 13 is preferably from about 0.2D to about 0.6D. The line of junction between the cylindrical side section 12 and the conical bottom section 15 preferably is at a distance of from about 0.2D to about 0.6D above the bottom of tank 11. The diameter, d, of central cylinder 31 is preferably from about 0.1D to about 0.5D. However, the diameter, d, of central cylinder 31 is no greater than the diameter, 0, of the flat bottom portion 13 so that, preferably, there will be a portion of the flat bottom outside the central cylinder.

It has been found that when these proportions are observed, good, thorough mixing action is obtained in the apparatus. While it is not desired to be bound by any theory, it is believed that the downwardly and tangentially directed stream of fluid from discharge outlet 27, upon striking the surface of the liquid in tank 11, not only causes a rotary or swirling motion about the vertical axis of the tank, but also, due to its downwardly directed component, causes rotation of the fluid in a vertical plane through the center of the tank. This combination of a vertical swirling motion, together with the rotation about the vertical axis of the tank, is believed to cause a spiral sure tanks.

motion within the fluid which results in exceptionally good mixing action.

While the height of central cylinder 31 can be varied as desired, it will conveniently be greater than the height to Which water is initially filled in the tank. In the pres ently described embodiment of this invention, it extends nearly to the topof or is of substantially the same height as tank 11. Central cylinder 31 is conveniently covered or closed at the top, as illustrated, so as to prevent par ticles of refractory material from falling into the interior of this cylinder. 7

Although the apparatus has been described as operating with a pump driven by compressed air, it will be understood that any other source of power can be used and that any pump capable of handling the slurry to be prepared can be used. Similarly,-the pipes used are of a size adequate to carry the slurry involved, 2-inch pipe being found quite adequate with a common, commercially available refractory slurrymix. Again, holes 32 in the bottom of central cylinder 31 are large enough to pass the largest solid particles contained in the slurry. Thus, four slots %-inch high x 8 inches long spaced equally about the bottom circumference of central cylinder 31 have been found to be effective.

Any suitable materials of construction, for example steel, can be used in making the tank and associated'parts.

It is an advantage of this apparatus that the tank can be made of a thinner gauge of metal than required for pres- Conveniently,

pipes

24 and 25 are of flexible material, for example rubber.

Having now described the invention, what is claimed is: 1. Apparatus for mixing and gunning a cementitious slurry comprising: a mixing tank having a tubular Wall section, a flat bottom section, a conical bottom section joining said fiat bottom section to said tubular wall section,a centrally disposed vertical tube attached to said fiat bottom section, and an outlet opening located in the bottom of the tank within said centrally disposed vertical tube, saidtube having apertures adjacent the. bottom of the tank to provide passageways from the tank to the outlet opening; first conduit means connecting said outlet opening to the inlet of a pump; second conduit means connecting the outlet of said pump to the inlet of a two-way valve having two outlets; third conduit means connecting "one outlet of said two-way valve to a discharge nozzle;

the tank, a conical bottom section joining said flat bottom portion to said cylindrical wall section, said conical section meeting said cylindrical section at a distance of from- 0.2 to 0.6 times the diameter of the tank above the bottom of the tank, the total height of the tank being-at least equal to the diameter of the tank, a centrally disposed, vertical cylinder having a diameter of from 0.1 to 0.5

times the diameter of the tank, said cylinder being attached to the fiat bottom portion of the tank, and an outlet open ing located within said vertical cylinder, said vertical cylinder having apertures adjacent the bottom of the tank to provide passageways from the tank to the outlet; first conduit means connecting said outlet to the inlet of'a pump; second conduit means connecting the outlet of said pump to the inlet to a two-way valve having two outlets; third conduit means connecting one outlet of said two-way valve to a nozzle; fourth conduit means con nected to the second outlet ofsaid two-way valve and terminating in an opening, said opening being directed downwardly and tangentially into said tank.

3. Apparatus according to claim 2 wherein said discharge opening is directed at a point on said conical bottom section.

References Cited by the Examiner UNITED STATES PATENTS 1,531,594 3/1925 Carozza 259-148 i 2,316,705 4/1943 'Morgan et a1. 259146 2,660,415 11/1953 Hawes 259- 2,664,277 12/1953 Davies 259-l6l WALTER A. SCHEEL, Primary Examiner. R; W. JENKINS, Assistant Examiner.

Claims

1. APPARATUS FOR MIXING AND GUNNING A CEMENTITIOUS SLURRY COMPRISING: A MIXING TANK HAVING A TUBULAR WALL SECTION, A FLAT BOTTOM SECTION, A CONICAL BOTTOM SECTION JOINING SAID FLAT BOTTOM SECTION TO SAID TUBULAR WALL SECTION, A CENTRALLY DISPOSED VERTICAL TUBE ATTACHED TO SAID FLAT BOTTOM SECTION, AND AN OUTLET OPENING LOCATED IN THE BOTTOM OF THE TANK WITHIN SAID CENTRALLY DISPOSED VERTICAL TUBE, SAID TUBE HAVING APERTURES ADJACENT THE BOTTOM OF THE TANK TO PROVIDE PASSAGEWAYS FROM THE TANK TO THE OUTLET OPENING; FIRST CONDUIT MEANS CONNECTING SAID OUTLET OPENING TO THE INLET OF A PUMP; SECOND CONDUIT MEANS CON-