Improvements in the Process of Drying and Disintegrating Clay and similar materials.
Year: 1892

page_text: Date of Application, 17th Oct., 1892-Accepted, 19th Nov., 1892
COMPLETE SPECIFICATION.
Improvements in the Process of Drying and Disintegrating Clay and
similar materials.
HERBERT JOHN HADDAN of the firm of Herbert & Co. Patent Agents of
18 Buckingham Street Strand W.C. London, Civil Engineer do hereby declare
the nature of this invention a communication to me from abroad by Franklin
David Cummer Manufacturer of Cleveland, State of Ohio, United States of
America and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to a new process of drying and disintegrating clay and
similar material and it consists in the steps hereinafter described and claimed.
As is well known, the clay for manufacturing porcelain, china, and the finer
goods generally, is treated in a filter press, but such treatment is too expensive for
manufacturing pressed brick, flower pots, and other coarser goods, and for such
coarser goods it is desirable to dry the clay if it can be done cheaply, because
among other reasons, the clay when dry can be screened to remove small stones
and other impurities which could not well be removed by the wet process.
It is generally understood that potters' clay cannot be heated above 250 degrees
Fahrenheit without injuring its adhesive qualities thus rendering it unfit for pressed
brick and pottery purposes. On the other hand the process of drying clay exposed
to a temperature less than 250 degrees Fahrenheit would be so slow and expensive
that it would usually be considered impracticable. Besides, such slow process
would be likely to bake the material into hard masses difficult to reduce so as to be
fit for usc.
I have found means for drying clay quickly and cheaply, and at the
end of the process the clay or other material is in condition slaked or disintegrated
and mellow, like an ash heap, and consequently ready for screening or further
reduction.
In preparing clay for treatment by this improved process substantially the same
means may be employed as in preparing the clay for the wet process, to wit; the
clay as it comes from the clay bank is passed between clay crushing rollers, where
the large stones are removed and the smaller stones are likely broken in passing
the rolls. The clay issues from the rolls in the form of a sheet, and this sheet of
clay by means of pickers or whippers is preferably broken into small pieces, say
In such condition the clay is
the size of the end of a person's finger and smaller.
subjected to my process, which is as follows.
The first stage of the process comprises the roasting of the clay, that is to say,
subjecting the clay to a high degree of heat, meantime preferably stirring the clay
constantly and thoroughly. The best means that I know of for this purpose is an
inclined rotating cylinder the material being fed into the upper end of the cylinder
and being discharged at the other end, the cylinder being provided with such
internal ribs projections or depressions as will carry up the material with the
ascending side of the cylinder and scatter the materials down as evenly as may be
across the diameter of the cylinder. The firing is done under the upper end of the
cylinder, and the products of combustion after passing rearward along the under
section of the cylinder, between the side walls of the setting is returned through the
cylinder where it comes in contact with the material. The cylinder may be heated
red hot without injuring the clay, so long as there is any considerable moisture i
the clay that is being evaporated and such escaping vapours will carry off the
surplus heat in excess of the evaporating point, say 212 degrees Fahrenheit.
When, however, the clay becomes partially dry so that but little vapour escapes
therefrom, care must be taken not to overheat the clay, and at such point the clay
should be discharged from the cylinder, and to this end the cylinder may be

page_text: revolved slower or faster, and also the clay may be fed slower or faster, for it is
evident that if a large amount of clay be passing the cylinder during a given time
it will not become heated to so high a degree as if the quantity was small. The
object sought is to dry the clay, so far as may be, in the cylinder, without injuring
it and at the same time to heat the clay enough so that after it is discharged from
the cylinder and placed in piles or bins in large quantities the aggregate heat in
the mass will be sufficient to evaporate the remaining moisture and complete the
drying process. The heated material, after it has been placed in large piles or in bins,
is left for a time to cool down. The moisture expelled during the cooling down
stage renders the material exceedingly friable and the slaking or disintegrating of
the clay during the cooling stage will leave a large share of the clay mellow, like
an ash pit, ready for screening or for other separation into different grades of
fineness suitable for use in making different qualities of ware. In passing the
material over screens, the small stones and similar impurities are readily removed
and if there should remain some lumps of clay that have not been thoroughly
slaked, these are easily pulverized by tumbling or other means so that with little
trouble the clay, freed from all impurities may be pulverized and made ready for
In the screening process of course, screens of different fineness may be used
to assort the material, and if in connection with more especially the fine screens, an
air current be employed to carry off the dust, such dust will be found to be sub-
stantially as fine as the product from the same material had through a filtering
press.
use.
Another advantage of the dry process conducted as aforesaid is that many
impurities found in the clay, such for instance as sulphur, arsenic &c. are volatilized
and thus disposed of in heating or roasting the clay, such volatile matter of course
passing off with the vapour from the drying clay.
In the accompanying drawings is shown suitable means for carrying out this
improved process although I do not wish to limit myself to any particular
mechanism, for the reason that any mechanical drier that will keep the material
thoroughly and constantly stirred during the drying process in the machine will
answer the purpose.
Fig. 1 is a view in perspective of a drying apparatus.
Fig. 2 is a view in perspective of a pile of material supposed to have been passed
through the drier and left for cooling.
The material is fed into a hopper or spout A. and from thence passes into the
inclined rotating cylinder B, the material being discharged at the rear end through
the spout D. The firing is done under the front end of the cylinder and the
products of combustion pass rearward under the cylinder between the side walls of
the setting and from thence return through the cylinder, of course in the opposite
direction from that taken by the material, the gases and vapour from the material
passing off through chimney C.
As aforesaid I do not wish to limit myself in this process to any particular form
of drier. After the material is discharged from the roasting or drying apparatus,
it may be handled by means of any suitable conveying mechanism whereby it can
be piled upon the ground or stored in the bin; but as bins are employed for
storing the material such bins should be provided with means for ventilation at the
sides as well as at the top, so that the vapour escaping from the mass of material
can pass cff freely.
Sometimes the clay or other material is of such a wet sticky nature that it will
adhere to the heated cylinder as soon as it comes in contact therewith. In such
case I provide a small elevator of some kind for instance as at H. This clevator
takes up a small quantity of the heated material discharged from spout D and
discharges it into hopper A where it mixes with the raw material and serves
the same purpose as sprinkling flour over dough in the culinary department,
that is to say it renders it less sticky, also there may be placed a thermometer I
in such position that it is impinged by the hot material being discharged into
the hopper, and by watching the thermometer the operator can tell whether the

page_text: material discharged from the drier is or is not at the proper temperature and can
regulate his fire, feed &c. accordingly. Where this returning of material to mix
with the raw material is not required, I may add that in regard to the precise
condition of the partly dried material where it should be discharged from the
machine, a little practice will enable a person of intelligence to determine this by
observing the amount of vapour passing from the material at or near the point of
discharge, and so long as any considerable amount of vapour is seen passing off
from the material no fears may be had that the material is being overheated, but
when little vapour is seen escaping from the material it may be assumed that there
is enough heat in the material to complete the drying after the material has been
piled. As a matter of fact I will state that I find no difficulty in running ten tons
of material per hour through a drier, such material being discharged from the
drier in such heated and partially dried condition that the drying is completed in
the piles of material from which it will be understood that this improved process is
comparatively cheap.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. The process herein described of drying clay and similar material and con-
sisting essentially, first, in heating and stirring the material until it is partially
dried, and second, piling the heated and partially dried material, whereby the
drying process is completed by means of the aggregate heat in the pile of material
substantially as set forth.
2. The process herein described of drying clay and similar material comprising
first, heating, stirring and partially drying the material in any suitable mechanical
drier, second, returning a portion of the heated material and mixing it with the
green material to be heated, and third piling the heated and partially dried material
to evaporate the same to dryness by means of the accumulated heat in such pile
of material substantially as set forth.
3. The process of drying clay and similar material substantially as herein
described.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.