US2029524A - Process of making expanded vermiculite - Google Patents

Description

Feb. 4,1936. P. s. DENNING I PROCESS OF MAKING EXPANDED VERMICULITE Filed Jan. 21, 1932 give 72250 n PM .9. flea/u 726 j r MM 7 7 J .5.

7 M v I 4 3 275 v J Patented Feb. 4, 1936 PROCESS OF MAKING EXPANDED VERMICULITE Paul s. Denning, Joliet, 11].,assignor a r. E. Schundler & 00., Inc., a corporation of Illinois Applicationjanuary 21, 1932, Serial No. 587,959 6 Claims. (01.252-1) This invention relates to the process of and apparatus for exfoliating or expanding vermiculite and the like.

One of the objects of the invention is the provision of a new and improved process of expanding vermiculite in such a manner that the insulating product will be tough and more or less yielding.

Another object of the invention is the provision of a new and improved porous, tough, and yielding material which is well adapted for use where acoustical or thermal insulation is advantageous or desirable.

A further object of the invention is the provision of a new and improved apparatus for heat treating vermiculite for expanding the same without loss of weight during the expanding operation.

A still further object of the invention is the provision of a new and improved method of preparing vermiculite for insulating purposes which produces an excellent product, light in Weight, efficient as an insulating material that is not fragile, and which, as a consequence, may be handled without destroying its insulating prop erties.

Further objects and advantages of the invention will appear from the following description, taken in connection with the accompanying drawing, in which- Fig. 1 is a side elevation of the heating apparatus showing parts in section and parts broken away;

Fig. 2 is a section on broken line 22 of Fig. 1.

5 As heretofore practiced, the expanding of vermiculite has resulted in a product more or less fragile owing to the loss of moisture from the mineral during the exfoliating or expanding operation. During the expanding operation, the

40 mineral has been heated gradually, either in rotary converters, to its maximum temperature,

or by treating the same with hot gases which flow counter to the movement of the material.

In either case, a considerable amountof mois- 5 ture evaporates from the material, leaving it fragile or friable. Furthermore, the loss of moisture is of such a consequence in mass production as to constitute a substantial difference in the weight of large quantities of the mineral before 50 and after expansion.

This difference in weight is of suflicient im-,

portance to be taken into consideration as an item of loss in calculating the selling price of the finished product. The loss of the crushed mate-: rial owing to its fragility must also be considered PATENT .OFFlCE in the calculation of production cost of the insulating material.

The present invention seeks to remedy these objectionable features in the heat treatment of vermiculite and the like.

I have found'by experiment that if the raw material is suddenly subjected to a high temperature for a very short period, the expansion of the material is more perfect and a lighter, tougher product results. My experiments show that 10 the resulting product is from 5% to 20% lighter-and even more-per cubic foot than the product prepared by the former methods of gradually heating the material. The product also has more or less resiliency and is non-fragile, where- 15 as the products of the former methods are friable and have very little resiliency.

While it is not definitely known what causes this difference in properties, the following explanation is offered as a probable reason. 20

vermiculite is laminated; there undoubtedly is more or less moisture between the laminations.

In gradual heating, this moisture is evaporated somewhat during the operation, whereas when the material is subjected suddenly to a high 25 temperature for a brief period, the moisture is converted into steam causing miniature explosions in the manner of popping corn.

The material is subjected to this high temperature, which may be around 1500 Fahr., for 30 only a few seconds, and, consequently, there is no time for the moistureto evaporate. The time of exposure will vary with the size of the charge, but ordinarily only 'a few seconds. Usually an exposure of 5 to 20 seconds where the charge is continually agitated to get uniform exposure, gives satisfactory results.

It is necessary that the material be continually agitated in order to obtain uniform exposure to the heat. The material is a good non-conductor 40 and unless agitated the sides of the particles removed from the source of heat will receive far less heat than the exposed surfaces.

Any suitable mechanism may be employed for heat treating the material for expandingthe same. One form of apparatus, which is by way of example only, is shown on the drawing and comprises a vibrating hearth designated generally by the reference character Ill. The hearth I0 is shown'by way of example only as comprising a plate which is adapted to be supported on the body portion l5 of the vibrating hearth, designated generally by the reference character l3.

' The side members ll, l2 of the body portion iii are provided intermediate between their ends with bearings I6 and I! in which is journaled the shaft iii. The shaft I8 is provided with eccentric journals l9 and 2| which engage the bearings I 6 and IT for causing vibration of the body portion l5 during the operation of the device.

The shaft I8 is also provided with fiy wheels 22 and 23 adjacent the ends thereof, respectively, and also with a pulley 24 for operating the same in the usual manner.

Suitable means are supplied for adjusting the body portion l5 of the hearth. In the form of construction shown, the base, or support [4, of the device is provided with a concave seat 25 in which is adjustably mounted the adjusting member 26 which is furnished with a lower convex surface 21 for engaging the concave surface 25 of the base l4, whereby the adjusting member 26 may be moved angularly relative to the base I4. Parts are held in adjusted position by suitable clamping members 28. Adjusting member 28 is rigidly secured to a bar 29 having the ring members 3| and 32 on the ends thereof. The ring members 3| and 32 are adapted to receive the trunnions 33 and 34 which are, in turn, connected to the side members of the body portion l5, as clearly shown in Fig. l of the drawing. The trunnions 33 and 34 comprise the studs 36 and 31 rigidly connected to the sides of the body portion and the annular rubber blocks 38 and 39 which engage in the rings 3| and 32 and are mounted on the studs 36 and 31. The resiliency of the annular rubber blocks 38 and 39 is adapted to permit the vibration of the hearth relative to the support I4 during the operation of the device. Since the vibrating mechanism for the hearth is of the usual or well-known construction, .it is not thought necessary to further illustrate or describe the same.

A suitable arch 4| for cooperating with the hearth is provided to furnish a heating chamber 42. This arch may be of any suitable material, as fire brick or the like, for withstanding high temperatures.

Appropriate means are provided for heating the chamber 42. In the form of construction shown, which is by way of example only, means are afforded for heating the chamber by gas or oil burners. The sides 43 and 44 of the arch 4| are perforated at suitable intervals as at 45 and 46, for receiving nozzles 41 and 48 extending inwardly from the headers or supply pipes 49 and 5| at each side of the arch. Headers are furnished by the mains 52 from any suitable source of supply. The upper portion of the arch at one end thereof is provided with an opening 53 for receiving the material from the hopper 54. Suitable means are supplied for supporting the arch 4| above the hearth Hi. In the form of construction shown, threaded rods 55 and 56 at each side of the arch are employed for this purpose. These rods are adapted to extend through slots in the outer ends of the channel bars 51 and 58 which support the arch.

When the hearth is angularly adjusted, it is necessary that the arch likewise be angularly adjusted and this may be accomplished by adjusting the nuts on the ends of the rods supporting the arch.

In the operation of the device, the micaceous product is placed in the hopper 54, the material flowing through the opening 53 into the hearth l0, and, due to the vibration of the hearth, rapidly passes down the incline to be discharged at the lower end thereof.

The temperature of the chamber 42 is maintained around 1000 to 1800 degrees Fahrenheit and inclination of the hearth is such that the material will pass through the heating chamber in a very short time. It has been found that from five to fifteen seconds give good results, although this will depend upon the nature of the material and the amount that is being treated.

Immediately after the expansion, the material is suddenly discharged from the heated chamber into suitable containers exposed to atmospheric temperature where, by the particles of steam within, the cells of the material are condensed before they have time to escape, and, as a result. the expanded material does not lose in weight during the heat-treating operation.

If desired, the expanded material may be further expanded by a second heat treating process. This second expanding operation may be performed by different methods, but in any method employed moisture is added to the material for accomplishing the expansion.

One method comprises discharging the material from the first expanding operation directly into a vessel or receptacle containing water and thereafter centrifugalizing the material for driving off the excess moisture and then run the material through the expanding or heat treating chamber which further expands the material. Or, if desired, the excess moisture may be removed by running the material through a press and then heat-treating the same. Substantially, the same results as centrifugalizing the material are obtained.

What I claim, therefore, is:

l. A method of expanding vermiculite which consists of suddenly subjecting the material to a high temperature within an enclosed space for not over fifteen seconds, agitating the mass during exposure and then suddenly subjecting the mass to atmospheric temperature and submerging the same in water, removing the excess moisture and immediately thereafter exposing the mass to a high temperature within a closed space for not to exceed fifteen seconds and finally suddenly subjecting the mass again to atmospheric temperature.

2. A method of expanding vermiculite particles which comprises subjecting the material suddenly to a high temperature for a short period of time for expanding the particles, wetting the expanded particles, removing the excess moisture, and again subjecting the material suddenly to a high temperature for further expansion of the particles, and then cooling the particles.

3. A method of re-expanding expanded vermiculite which comprises moistening the expanded material and subjecting the moistened expanded material suddenly to a temperature far in excess of the boiling point of water for a brief period of time of just sufficient duration to convert the additional moisture within the mass into steam, and then discharging the re-expanded mass into the atmosphere.

4. A method of expanding vermiculite material which consists in suddenly introducing the same into an elongated passage, having heat applied thereto from a plurality of nozzles distributed along substantially the entire length of the passage and directed transversely to the flow of material, causing the material to pass along said passage and be heated from said nozzles and simultaneously causing the turning of the particles independently of the heat application for exposing all sides to the heat, and then substantially immediately cooling the expanded material.

5. A method of expanding vermiculite material which consists in suddenly introducing the same into an elongated passage, having heat applied thereto from sources distributed along the passage and directing heat rays onto the mass in a direction transversely to its movement, causing the material to pass along said passage, and substantially immediately cooling the expanded material.

6. The method of producing plastic expanded vermiculite which consists in causing a mass of vermiculite particles to flow down an incline and simultaneously subjecting the particles suddenly to heat rays from burners arranged transversely to the direction of movement of the particles at a temperature between 1200 and 1600" Fahr. for a period not to exceed twenty seconds, agitating the mass during the heating operation independently of the application of heat, and then suddenly exposing theexpanded particles to the atmosphere for cooling the same.

PAUL S. DENNING.

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