Improvements in Dissolving and Drying Phosphates and other Substances.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Dissolving and Drying Phosphates and other
Substances.
I. JOHN MILNE, of 1, St. Mary's Place, Inverurie, in the County of Aberdeen,.
Scotland, Merchant, do hereby declare the nature of this invention to be as
follows:-
This invention relates to dissolving and drying phosphatic manures, and other
substances (or for drying the same only) by means of an improved apparatus as is
hereinafter more particularly described.
Hitherto the practice has been that after the ground phosphates are mixed with
acid in any suitable apparatus, they are projected into a den or pit, where after
lying for some time, they are dug out and wheeled in a comparatively moist state
to a heap where they usually lie for several weeks before being broken up, bagged
and shipped.
According to my invention the phosphates are mixed with acid in any suitable
mixer, and are then discharged upon the upper part of an apparatus which consists
of one or more, preferably five, double rows of plates fixed to traction chains,.
arranged as an endless apron and moved by slow driving gear. The substance to
be dissolved or dried travels along with the upper plates and falls upon the second
row, and so on until it falls into a screw conveyor or other means for discharging
it. It is then in a thoroughly dried condition so that it can be powdered by any
machine and elevated ready to be stored in bags or in bulk. The apparatus can.
be used for drying dissolved manures or other substances from which it is desired.
to extract moisture.
My apparatus may be heated from a special furnace, or in the case of manure
drying, by gases from boiler furnace flues, blown into it by a fan; and the gases
from the dissolving machine and dryer are collected, washed, and discharged by
another fan; as much cold air is let into the flue propelled by the first fan as will
cool the gases entering the apparatus to a temperature that does not act
injuriously upon those substances being dried which are partly volatile at high
temperatures.
By the use of my apparatus the phosphate of bones, coprolites, mineral, rock
and other phosphates can be dissolved more thoroughly than by the means hitherto
practised, as a sufficient quantity of acid for dissolving every atom of phosphate
of lime can be used and the heat of the mixture within the apparatus increases the
dissolving action of the acid. In practice I have found that the dissolved
phosphate can be dried until less than four per cent. of uncombined moisture
remains, and the phosphate is discharged in such a desiccated state that it can be
subjected to any process of pulverizing without becoming reduced to pulp, while
superphosphate made by the ordinary process hitherto practised is always damp,
and cannot be reduced to a fine powder, or sown on the land by a machine without
getting into a wet pulp, and damp superphosphate soon destroys the bags that
carry it.
By using the spent products of combustion from the boiler flues practically no

page_text: expense is incurred for fuel; and the workmen are not subjected to the injurious
gases inhaled in digging superphosphate from pits.
In the process herein described, from nine to thirteen per cent. of water is
expelled, and thus the cost of bags, freight, carting, and application is corre
spondingly reduced.
When damp superphosphate is mixed with sulphate of ammonia, or potash salts,
a hardening process begins requiring the mixture to be twice put through a
grinding machine at a cost of from six to ten shillings per ton. Superphosphate
made in my apparatus does not harden when mixed with these salts, the cost of
grinding is saved, and the mixture is left in far finer powder.
Dated this 10th day of June 1896.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in Dissolving and Drying Phosphates and other
Substances.
1, JOHN MILNE, of 1, St. Mary's Place, Inverurie, in the County of Aberdeen,
Scotland, Merchant, do hereby declare the nature of this invention 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 dissolving and drying phosphatic manures and other
substances in one operation by means of an improved apparatus as is hereinafter
more particularly described.
Hitherto the practice has been that after the ground phosphates are mixed with
acid in any suitable apparatus, they are projected into a den or pit, where after
lying for some time, they are dug out and wheeled in a comparatively moist state
to a heap where they usually lie for several weeks before being broken up, bagged
and shipped.
According to my invention the phosphates are mixed with acid in any suitable
mixer, and are then discharged upon the upper part of an apparatus which consists
of one or more, preferably five, double rows of plates, fixed to traction chains,
arranged as an endless apron and moved by slow driving gear. The substance
to be dissolved and dried travels along with the upper plates and falls upon the
second row, and so on until it falls into a screw conveyer or other means for
discharging it.
It is then in a thoroughly dried condition so that it can be powdered by any
machine and elevated ready to be stored in bags or in bulk.
My apparatus may be heated from a special furnace, or by gases from boiler
furnace flues, blown into it by a fan; and the gases from the dissolving machine
and dryer are collected, washed, and discharged by another fan; as much cold air
is propelled by the first fau into the flue as will cool the gases entering the
apparatus to a temperature that does not act injuriously upon those substances
being dried which are partly volatile at high temperatures.
In the accompanying drawing,-
Figure 1 is a longitudinal section of my improved apparatus:
Figure 2 is a horizontal section of the same; and,
Figure 3 is a vertical section on the line 3-3, Figure 1.
a, a are the walls of my improved apparatus, the said walls being preferably of
brick, and b, b are the endless aprous arranged in the same. In the drawing five
of these aprons, are arranged one above the other, but any suitable number of such

page_text: aprons can be employed. c, c are the plates forming the aprons, and d, d the..
traction chains to which they are secured, the said chains passing over chain
wheels e, e mounted on shafts f, f passing through the lateral walls of the apparatus.
as shewn clearly in the drawing. The shafts fare provided outside the apparatus.
with worm wheels g which gear with worns h on a vertical shaft i which is actuated
through the medium of bevel gear j, j.
kis the spiral conveyer arranged at the bottom of the apparatus and designed
to receive the dried or dissolved material and convey it to the exterior of the
apparatus, the said conveyer being driven by the pulley . m is the flue through
which the hot air or gases from the special furnace or from the boiler furnace.
enters or enter the vertical shaft n. o, o are openings from the shaft n into the-
apparatus and
p,p are openings by which the gases after they have passed through
the apparatus escape into a shaft 7 in communication with a fluer leading to a
chimney. The openings o, o and p, p are provided with shutters s, s for regulating.
the flow of the hot air or gases through the apparatus. As above described
sufficient cold air is admitted to reduce the temperature of the hot air or gases to.
a point at which no injurious effect is produced on the substance to be dissolved.
or dried.
t is a hopper into which the material which may be liquid, semi-liquid or solidi
is emptied and from which it drops on to the topmost apron and is carried along.
by the said apron in the direction of the arrow Figure 1. When it reaches the
end of the apron it drops on to the second apron and so on as shewn by the arrows.
until it finally reaches the conveyer k from which it is removed from the apparatus..
The topmost apron is provided with lateral plates or sides u, u to prevent the semi-
liquid, such as mixed acid and phosphate, material from dropping from the said
apron, and inclined plates or guides r, v are secured to the walls of the apparatus to.
guide the material from one apron to the other.
The hot air or the gases of combustion may be caused to circulate through the
apparatus by means of fans.
By the use of my apparatus the phosphate of bones, coprolites, mineral, rock and
other phosphates can be dissolved more thoroughly than by the means hitherto.
practised, as a sufficient quantity of acid for dissolving every atom of phosphate
of lime can be used and the heat of the mixture within the apparatus increases the.
dissolving action of the acid. In practice I have found that the dissolved phosphate
can be dried until less than four per cent. of uncombined moisture remains, and the
phosphate is discharged in such a desiccated state that it can be subjected to any
process of pulverizing without becoming reduced to pulp, while superphosphate
made by the ordinary process hitherto practised is always danp, and cannot be
reduced to a fine powder, or sown on the land by a machine without getting into a.
wet pulp, and damp superphosphate soon destroys the bags that carry it.
It will be obvious that with my apparatus the substance treated, chiefly mineral
phosphate, is mechanically and chemically changed during its passage through the
same that is to say, it is changed from a semi-liquid material to a dry powder or
from tribasic phosphate of lime and sulphuric acid to monobasic phosphate of lime
and calcium sulphate. It will thus be seen that I effect in one operation what has
hitherto required two operations.
By using the spent products of combustion from the boiler flues practically no.
expense is incurred for fuel; and the workmen are not subjected to the inhalation
of injurious gases in digging superphosphate from pits.
In the process herein described, from nine to thirteen per cent. of water is.
expelled, and thus the cost of bags, freight, carting, and application is corre--
spondingly reduced.
When damp superphosphate is mixed with sulphate of ammonia, or potash salts,
a hardening process begins requiring the mixture to be twice put through a
grinding machine at a cost of from six to ten shillings per ton. Superphosphate-
made in my apparatus does not barden so much when mixed with these salts, the.
cost of grinding is saved, and the mixture is left in far finer powder.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The described improvements in dissolving and drying phosphates and other
substances in one operation such improvements consisting in mixing the phosphate
or other substance with acid and in then causing it to pass through an apparatus in
which it is subjected to heat obtained from hot air or spent gases of combustion
from a furnace, sufficient cold air being admitted into the apparatus to cool the
said hot gases to a temperature which does not injuriously act upon the phosphate
or other substances, substantially as described and illustrated in the accompanying
drawing.
2. The improved apparatus for dissolving and drying phosphates and other
substances in one operation herein before described and illustrated in the accom-
panying drawing.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.