US2139378A - Vermiculite expansion method - Google Patents

Description

J. B. MYERS ET AL VERMICULITE EXPANSION METHOD Dec. 6, 1938.

Filed Deo. 24, 1937 @lfm Patented Dec. 6, 1938 UNITED STATES PATENT OFFICEA 2,139,318 i vEnMrcULrrE EXPANSION Mn'rnon John B. Myers, Libby, Mont., and Glenn Sucetti, Chicago, Ill., assignors to Universal Insulation Company, Chicago, Ill., a corporation of Illinois Application December 24, 1937, Serial No. 181,658

6 Claims. (Cl. 252-1) The present invention pertains to the exfoliaoperated by an electric-motor I5, or by any other tion or expansion of pieces of the mineral verapproved driving means, such elevator delivering miculite under the action of heat for use as a the ore into an inclined, rotary screen l6`which heat-insulator or for other purposes, feeds the larger particles incapable of passing Heretofore, diii'iculty has been experienced inV through the meshes of the screen through a chute 5 heat swelling or distension of such vermiculite il and rotary Vane feeder l into the interior particles in a furnace, in th'at to secure ample of the top of the furnace, characterized as a expansion of the larger particles, the pieces of whole i9, the smaller particles whichpassthrough smaller size have been unduly raised in temperathe revoluble screen passing by gravity through ture producing undesired friable small particles, the hopper-shaped bottom 2| of the casing 22 10 and, if less heat were employed to save such housing the screen and through an inclined consrnaller pieces from over-heating, the larger pieces duit 23 and rotary vane feeder 24 into the furwere not fully exfoliated or puffed. nace at a lower level than the entrance there- One outstanding or leading object or aim of the into of the larger particles. present invention is to provide a process or meth- Such screen and the two feeders referred to od for expanding vermiculite ore particles of may be rotated by any suitable means not shown various sizes in such manner that thel large and in detail. the small particles are given separately controlled The furnace, which may be rectangular in heat treatment, whereas by the old methods no horizontal cross-section. 1S provided in two of attempt has been made to perform the procedure its Opposite vertical Iwalls with a number of 20 by selecting heat treatment of the ore pieces of sloping gas or other suitable burners 25, 26, 21, different; sizes, 2t, 28 and 3|, each having directly above it a As a result of such earlier processes, the smaller downwardly-inclined, refractory-tile baille 32 supparticles were invariably over-expanded, pro ported at its inner end, near the Center of the ducing brittle or frangible small particles, or, if upright furnace heating-Chamber 33, 0n Suitable 25 less heat treatment were resorted to, the larger blocks 34 and at its Outer end at the wall. pieces of ore were not fully or thoroughly swelled The dome top 35 of the furnace has a disor enlarged. charge or outlet port connected to a delivery flue Accordingly, in order to overcome the dlsad- 36 for the escape of the products of combustion vantages incident to the practice of the prior and the bOttOm heS an Outlet 31 thIOugh Which 30 art processes, the novel and improved method the exfoliated vermiculite is delivered being of providing a uniformly expanded product conguided thereto by the sloping Walle 38, 38- sists in separating the large and small particles In additOn, the furnace iS equipped With a by screening prior to their introduction into the numer of peep- holes 39, 39 through which the expansion-chamber of the heated furnace, adoperation of the furnace may be readily observed. 35 mitting the larger vermiculite particles into one AS Will be readily understood, the larger Verportion of the furnace wherein they will receive miculite particles entering the furnee through the maximum heat treatment and admitting the upper inlet passage 4I and the smaller parthe smaller particles into another portion of the ticles admitted into the furnace through the furnace wherein they will receive a separatelylower admission conduit 42 slide down the upper 40 controlled heat treatment of lesser or lower desurfaces of the opposed, inclined baffles by gravity grec than the larger particles, whereby all of the and descend in a zig-zag or tortuo-us course down mineral particles treated are given approximateto the bottom of the furnace without coming too ly the same degree of expansion thereby aording directly in contact with the burners or their substantial uniformity in the final product. ames by reason of the shielding action of the 45 Furnaces of various types and styles may be baiiles, such descent of the vermiculite being in employed for practicing the new and beneflcial opposition to the upward travel of the heated procedure, but, by way of example only, one such. products of combustion in the furnace. appliance is illustrated inV the accompanying The gas-burners in the upper section of the drawing, in which the single View is a substanheating-chamber are adjusted for the expansion tially-central vertical-section through the furof the larger particles and the burners in thek nace or ore-heating apparatus. lower portion of the expansion-chamber below In this appliance, vermiculite ore from a hopthe entrance point of the finer particles are reguper ll is fed by a vibratory-feeder I2 to the lated for the correct and desired exfoliation of buckets i3 of an upright, endless elevator lt the nner particles oi ore, it being apparent that, 55

by reason of the upright relation of the furnace,

the heat developed by the lower burners assist in heating the larger particles in the upper part of the heating-chamber, thus aifording a conservation of the developed heat.

'Ihe stream of coarser and smaller particles oi' exfoliated vermiculite descend by gravity to the bottom of the expansion-chamber from which they may be removed by a screw-conveyor or they maybe allowed to slide down the incline to an elevator-boot, neither of which structures it is necessaryy to illustrate as they constitute no part of the present invention except that, of course, it is essential to convey the expanded vermiculite away in some appropriate manner and preferably to a hopper and associated dust-collector.

It has been found that a current of air is desirable for the specined purpose of elevation since vermiculite particles are more plastic and do not shrink after bagging when conveyed by an air stream, and the rock impurities, if any.y accompanying the expanded material being too heavy to be raised by the air, drop as the lighter expanded material is elevated and carried away, thereby affording ythe elimination of the rock impurities.

The number of burners employed in the furnace iand the regulation or adjustment of the heat developed thereby are such that practically all of the vermiculite particles, regardless of their differences in size, are expanded in approximately the same degree in a reducing atmosphere.

Some of the outstanding features of and prominent benefits accruing from the employment of the new procedure may be mentioned as follows:

"(a) the screening process inserted in the crude ore flow which permits a division of the ore as to size thus allowing-separate heat treatment;

(b) a method of treatment whereby the larger ore particles are expanded under greater heat and/or a longer heat period than the finer particles:

(c) a mode of procedure by which the smaller ore particles are expanded under less heat and a shorter cycle than the coarser particles;

(d) a treating method by virtue of which the smaller ore particles can be made to have substantially the same measure or standard of plasticity as the larger ore pieces through dinerent heat intensity and diilerent time through a manual control of heat and air under reducing furnace atmospheric conditions; and

(e) a method of treatment which permits preexpansion under lower heat of large and small' ore particles with-a final expansion with greater heat and complete expansion in a concluding heat application.

From what precedes, it will be understood that by modification of the action of the various burners substantial differences in the process of expansion may be had, in ,that the larger particles may be exfollated quickly under a high degree of heat or more slowly under a lesser amount of heat applied for a longer period and the action of the heat on the smaller particles as to time and intensity is subject to adjustment and change.

The exfoliation of the larger ore pieces/may be effected vvery suddenly so that during the latter portion of their gravity descent,`they may not be materially ail'ected by the lesser heat which is expanding the finer or smaller pieces, or they may be more slowly acted upon so that their complete expansion is not fully accomplished until they reach the lower portion of the furnace.

The invention as defined by the appended claims is not limited to all of the details herein set forth and various changes may be resorted to without departure from the heart and essence of the invention and without loss of any of its material benefits and advantages.

It may be desirable to obtain a greater range of selective heat treatment than is afforded by dividing the stream of particles into two sizes as illustrated by the above design. This is accomplished by screening the mixture of sizes over a multi-deck screen which would divide the mixture into three or more sizes. Each size could be given its correct heat treatment by introducing them at various points or levels of the heating cycle.

We claim:

1. In the process of heat-expanding vermiculite ore, the steps of introducing the larger vermiculite ore particles into a heated expansion furnace at a point to receive maximum heat treatment therein, introducing thesmaller vermiculite ore particles into the furnace at another point to receive less heat treatment therein than that to which said larger ore particles are subjected. and removing the heat-expandedparticles from the furnace; whereby to obtain approximately the same degree of expansion for al1 of the ore particles treated thus tending to uniformity of the product resulting from the treatment of various sizes of .ore particles.

2. 'I'he process set forth in claim 1 in which said larger and smaller ore particles are substantially simultaneously introduced into the furnace and substantially simultaneously acted upon by the heat in the furnace.

3. 'I'he process set forth in claim 1 in which said furnace is substantially-upright and said furnace and substantially simultaneously acted upon by the' heat in the furnace and in which the furnace is substantially-upright and said smaller particles are introduced thereinto at a lower level than the point of introduction of said larger particles. f

5. The process set forth in claim 1 in which said oreA particles are caused to travel downwardly in a zig-zag path by gr'avitv while undergoing the expansion.

6. In the process of heat-expanding vermiculite ore, the steps of size-grading the ore stream to a heated expansion furnace, introducing the larger graded ore particles into the furnace at a point to receive therein the maximum heat treatment, substantially simultaneously introducing the smaller graded ore particles into the furnace at another point to receive less heat treatment than that oi', but substantiallysimultaneously with that of, said larger ore particles. and removing the expanded particles fromv the furnace, whereby to obtain approximately vthe same degree of expansion for all of the orev particles treated, thus tending to uniformity of the product resulting from the treatment ,of various sizes of ore particles.

JOHN B. MYERS. GLENN SUCETTI.

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