US3521663A

US3521663A - Orifice for molten minerals

Info

Publication number: US3521663A
Authority: US
Inventors: Jack L Brinkerhoff; Lawrence B Horton; Chao Hsiao
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1966-12-27
Filing date: 1966-12-27
Publication date: 1970-07-28
Anticipated expiration: 1987-07-28

Description

s-tent Office 3,521,663 ORIFICE FOR MOLTEN MINERALS Jack L. Brinkerhoif, Lawrence B. Horton, and Chao Hsiao, Pocatello, Idaho, assignors to FMC Corporation, New York, N.Y., a corporation of Delaware Filed Dec. 27, 1966, Ser. No. 605,028

Int. Cl. F16k 49/00 US. Cl. 137-340 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The invention covers a novel, adjustable, orifice means for controlling the flow of molten slag to a fiberizing device at a uniform rate without plugging.

Description of the prior art Molten mineral slag, such as that obtained from phosphate furnaces wherein phosphate ores are reduced to elemental phosphorus, can be converted to mineral wool fibers. This can be achieved by feeding the molten slag from the furnace or cupola. onto a fiberizing apparatus, e.g. a fiberizing wheel, in a controlled, steady stream. A major difiiculty in the above process is keeping the molten slag flowing at a steady rate from either an orifice or a pouring lip in the furnace or cupola. Solidification of the molten slag in the pouring lip. or orifice and corrosion of the orifice by the slag commonly occur and make uniform slag flow difficult to maintain. As a result, there is a need for means which will permit the flow of molten slag at a steady rate without the above problems.

SUMMARY OF THE INVENTION It has been found that a controlled, steady flow of molten slag from a furnace onto a fiberizing device can be achieved by passing the slag through an orifice means which is defined by the ends of elongated, slideable metal elements radially disposed from said orifice and held in place by a support means; the elements can slide in their supports thereby increasing or decreasing the size of the orifice as desired. The size of the orifice can be maintained constant by moving the elongated metal elements towards the orifice as the ends of the metal elements are eroded away; the ends of the elongated, slideable metal elements that form the orifice thus can be constantly renewed.

BRIEF DESCRIPTION OF THE DRAWING In the drawing FIG. 1 illustratesa perspective 'view of the orifice means and the elements that form same, while FIG. 2 is a sectional view through one of the support means illustrated in FIG. 1.

DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS In theprocess of making mineral wool fibers from molten mineral slag, the slag is maintained in a molten state in a furnace and passed to a fiberizing apparatus to form the mineral wool fibers. One common example of a fiberizing apparatus is a fiberizing wheel in which a controlled stream of molten slag is poured onto a rotating wheel and the molten slag is thrown tangentially from the wheel. The tangentially thrown particles are then interrupted by a blast of a hot fluid gas, for example steam, and attenuated into fibers.

In such a process the quality of the mineral fibers produced is affected by the uniformity and control of the flow of molten slag onto the fiberizing wheel. Normally, this flow can be accomplished by simply controlling the slag temperature and static head above an orifice. However, because of the high temperatures of the molten mineral slag the orifice is subject to corrosive attack and its cross-sectional area changes with time, thereby changing the rate of flow and making flow control more difficult. In the case of certain slags such as molten phosphate slag obtained from the furnaces used to reduce phosphate ores to elemental phosphorus, corrosion of the orifice is so severe that specially designed orifices lined with molybdenum, tungsten or iridium have been utilized. However, these do not prevent corrosion, they merely reduce the rate of corrosion. Therefore, orifices lined with these metals eventually corrode and present the same flow control problem as the conventional metal orifices.

An additional difliculty in using molten mineral slag in forming mineral wool fibers is that mineral slag will only produce satisfactory fibers when the slag is within a relatively narrow temperature range. This presents a serious obstacle to producing acceptable mineral wool fibers because the slag which is removed from the furnace must contact the fiberizing apparatus within a very narrow temperature range. If there is a deviation in the flow rate or the time required for the molten slag to flow to the fiberizing apparatus, the mineral wool product which is obtained will not be acceptable. Thus, when making fibers from molten mineral slag, control of the flow rate is even more critical than, for example, when producing glass fibers since the temperature range for producing acceptable glass fiber is much wider.

The invention will now be described with reference to the appended drawings. In the drawings:

FIG. 1 is a perspective view of the orifice means, and

FIG. 2 is a sectional view through one of the support means illustrated in FIG. 1.

In FIG. 1, 2 represents a frame to which is attached support means 4. The support means 4 are rigidly attached to the frame 2 about an opening in the center of frame 2. In addition there is also attached to frame 2 guide means 6 which is located around and at the lip of the opening in frame 2. A plurality of metal elements 8 are held within support means 4 in a slideable relationship so that the metal elements 8 can slide in a radial direction towards or away from the opening in frame 2 a portion of the elements 8 contact guide means 6 and projects over the opening in frame 2. The ends of element 8 that contact each other then define an orifice 10 which is smaller than the opening in frame 2. The size of the orifice can be regulated by increasing or decreasing the amount that the metal elements 8 project beyond guide means '6 into the opening of the frame 2.

The support means 4 as illustrated in FIG. 2 are made up of an inner metal holder 24 surrounded by an outer metal jacket 22 and containing a hollow section therein. Water, or other cooling liquid is circulated between the inner and outer walls of the support means 4 to cool the elements 8 held within the support means 4. Water is introduced into one hollow support means 4 through water line 12 and then through the other support means ihrough lines 14, 1-6 and 18 and finally removed through ine 20.

In operation the orifice unit is fixed to the base of a furnace having an opening therein so that the orifice covers an opening in the furnace (not shown). The slag is then permitted to pass through the furnace opening, passed the orifice means, to the fiberizing apparatus.

The rate of flow of the molten slag through the orifice is regulated by the size of the orifice. The orifice size, in turn, is controlled by adjusting elements 8. As the molten slag flows through the orifice 10 there will be an unavoidable amount of corrosion erosion of the elements 8. As this occurs the elements are inserted further in their supports 4 so that the orifice 10 is maintained at a constant size. The cooling of the elements 8 has been found extremely effective in cutting down the amount of erosion. The cooling water circulated in the supports 4 cools the metal elements 8 to increase their resistance to corrosion by the molten slag, but they are not cooled sufficie-ntly so that molten slag solidifies in the orifice.

In the above description and drawing of the preferred embodiment of the orifice, four support means, each containing a number of metal elements, have been illustrated. However, it should be realized that any number of support means and metal elements can be used in the practice of this invention as long as they are positioned radially about the orifice. Further, the frame that holds supports 4 can be of any shape desired.

In the embodiment shown above, the metal elements 8 that make up the orifice have their ends reduced in thickness to obtain a thinner cross section about the orifice. However, it is obvious that the ends of the metal elements can be uniform throughout, if desired, to obtain a cross section about the orifice which is as thick as the metal elements 8.

The following example is given to illustrate the invention and is not deemed to be limiting thereof.

Example 1 An orifice means, having the structure as set forth in the drawing, was fixed onto an opening in the wall of a refractory container into which was flowed molten phosphate slag from an electric furnace. An overflow device on the container provided for a constant hydrostatic head of about 8 inches. The elongated elements used in the orifice means were inch by /2 inch by inches long and were constructed of (310) stainless steel. The orifice means was arranged with three elements per side so that the basic orifice opening was 2%. inches square.

The following test data was obtained:

Flow rate (lbs/hour) Observations Slag temperature, 2,620 F. Decreased orifice size. Slag temperature, 2,610 F.

Slag temperature, 2,620 F. Slag temperature, 2,630 F.

End of test The above results indicate that a desired rate of flow of the slag can be selected and maintained with the present orifice means and that the temperature of the molten slag remains substantially constant during slag flow.

Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art, such exemplification including what is considered to represent the best embodiment of the invention. However, it should be clearly understood that, within the scope of the appended claims, the invention may be practiced by those skilled in the art, and having the benefit of this disclosure otherwise than as specifically described and exemplified herein.

What is claimed is:

1. An adjustable orifice means for controlling the rate of fiow of a molten mineral comprising a frame having an opening therein, a plurality of supports fixed to said frame disposed about said opening, said supports holding in slideable relationship a plurality of elongated metal elements positioned radially from said opening, a portion of each of said metal elements extending over said opening in said frame and defining an orifice within said opening by one end of each of said metal elements contacting adjacent elements, said elongated metal elements being in substantially the same plane and independently slideably mounted whereby they can slide within said support members to maintain the size and shape of the orifice formed at a predetermined, fixed position by renewing the ends of said elongated metal elements as they are eroded away.

2. The orifice means of claim 1 wherein said elongated metal elements are cooled by cooling means that contain a cooling fluid in indirect contact with said elements.

3. The orifice means of claim 1 wherein said supports have a hollow section therein through which passes a cooling fluid to cool said metal elements located within said supports.

4. The orifice means of claim 1, wherein said molten mineral is mineral slag.

References Cited UNITED STATES PATENTS 497,903 5/1893 Woodward 251-212 X 3,101,736 8/1963 Egger 25l212 X 3,329,396 7/1967 Heaton et a1. 251-212 1,102,197 6/1914 Knox 137-340 2,875,725 3/1959 Lit et al. 118125 2,994,624 8/1961 Lit et a1. 118-125 X 3,287,158 11/1966 Whitfield 118-419 X JOHN P. MCINTOSH, Primary Examiner US. Cl. X.R. 251-212