Caliche" ог tube's
Year: 1886

page_text: MARLBOROUGH ROBERT PRYOR of Weston Manor, Stevenage, Herts Merchant and
ALEXANDER CHALMERS JAMESON of 152 Belsize Road, Hampstead London N.W.
Engineer, 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 :―
The nature and object of this Invention is the economical extraction of Nitrate
of Soda or other salts from their native earths by a continuous process and by the
agency of water either hot or cold. In the following description the apparatus will
be described as applied to the extraction of Nitrate of Soda from the
earths containing it. Nitrate of Soda will be called simply nitrate.
Caliche"
ог
tube's
The apparatus for effecting the extraction when cold water is employed and
when a large quantity of nitrate is not required to be produced consists of an
Archimedian screw fixed inside an inclined tube. This tube is caused to rotate
with the screw while a stream of cold water flows into it at or near the higher end.
The lower end of the tube is so arranged that at each revolution it takes up a
portion of caliche which is slowly worked up the tube by means of the
rotation and passed out at the higher end leaving the nitrate originally contained
in it in the water, which enters in a continuous stream at the higher end and
passes out at the lower end. The water charged with nitrate, as it leaves the
lower end of the tube is received in a tank of sufficient size or sectional area to
permit only a very slow current thereby allowing the fine sediment to be deposited:
the clear solution then flows out of the tank to such place as may be provided for
the crystallisation of the nitrate contained therein, while the refuse is delivered
into a hutch or wagon and deposited on the heap or bank. By this means the
refuse delivered from the higher end of the tube is washed with fresh water con-
taining little or no nitrate in solution and passes out containing only a very small
percentage of nitrate with it while the water flowing down the tube passes
progressively over richer and richer caliche. Though we consider this the best
design the screw may be made to turn inside the tube-the tube being stationary,
or the tube may be open on the top forming a long trough with the screw revolving
in it. Also although we have used the term cold water heat may be advantageously
supplied to the water sufficient to replace the latent heat of liquifaction of the
nitrate

page_text: This apparatus with the necessary modifications in detail may be used for
extracting nitrate by the agency of hot water but is not mechanically convenient
when large quantities are required owing to the number of working parts.
In order to diminish the number of working parts when large quantities of
nitrate are required to be produced a cylindrical vertical vessel is made having 5
a hopper for the reception of caliche at the top. This vessel or retort is provided
with a number of tubes passing down through it and steam is admitted so as to
surround the tubes and heat the caliche and liquid contained in them.
A passage
is provided in the centre of the retort or at one side in which a Jacob's ladder or
dredger works to remove the refuse from the bottom of the retort after it has 1
passed down through the tubes. This dredger is arranged so as to be easily with-
drawn for repairs. The water for extracting the nitrate flows in at the top of this
passage and over and through the refuse contained in the buckets of the dredger
passing down the dredger passage and up through the tubes (down which the
caliche passes) and out of the retort into a settling tank from which it flows to the
crystallising tanks; by this means the progressive impoverishment of the caliche
combined with the progressive enrichment of the water in nitrate is attained.
The hopper for caliche at the top is kept full so that the steam rising from the
heated solution below is absorbed by the caliche and carried down with it into the
nitrate solution by this means and by the small area of hot solution exposed to 2
the air compared with the method of extraction in use now, a large saving of fuel
is obtained.
The crystallisation of the nitrate is carried out in an elongated tank having a
double bottom and open on the top so as to expose a large area of surface to the
air. The nitrate solution flows in at one end of the tank and out at the other 2
depositing the nitrate as it cools partly by evaporation partly by radiation and
partly by the contact of the weakened solution returning in the double bottom
which weakened solution is returned to the retort near the top of the Jacob's
ladder or dredger carrying back to the retort a considerable portion of the heat
originally in the crystallising solution. The expanse of surface for evaporation is
required because the nitrate in crystallising out of the water gives up its latent
heat which heat the returning weakened solution has not capacity to take up.
The water required to be added to replace that carried off by the refuse being
colder and containing less nitrate than that returned from the crystallising tank is
added as the final operation is washing the refuse either at the top of the dredger
in the same manner as that returned from the crystalling tank but higher up or
is run over & through the refuse in the wagon or hutch into which the refuse is
delivered by the dredger whence it is drained into the dredger passage; by this
means the utmost possible amount of nitrate and heat are removed from the
refuse. This water may however if desired be added at the cool end of the crys-
tallising tank. Through this apparatus has been described in its application to hot
water, the retort is equally adapted for cold water the steam casing being then
unnecessary and the tubes of larger diameter.
Fig. 1 shows the apparatus particularly adapted for cold water a b is the
rotating tube containing the archimedian screw, c the crusher d the caliche which
is passed up the tube a b.
The water enters at e and passes down the hollow
spindle to where it passes through the holes there shown and comes in contact
with the caliche and passes down through the tube a b into the tank g depositing
there the fine silt and passes out by the pipe h. i is the wagon or hutch into
which the refuse is delivered and the wagon or hutch which brings the caliche
to the crusher : the screw is made a slack fit in the tube at the higher end b and
may be perforated.
Fig. 2. shows this apparatus modified for the use of hot water. a b is the tube
in which an archimedian screw rotates. I is a stream jacket surrounding the tube
to supply heat to its contents d the hopper into which the crushed caliche is
introduced m the dredger or Jacobs ladder which removes the refuse n the pipe
by which the water enters o a stand pipe of sufficient area to permit only a very

page_text: slow current and allow the silt to fall to the bottom p the pipe by which the
The introduction of the water
nitrate solution runs to the crystallisation tanks.
and removal of the refuse at the higher end of the tube b may be arranged as
shown in Fig. 1.
Fig. 3. shows the arrangement best adapted for the extraction of nitrate by the
hot process in large quantities. d is the hopper for the previously crushed caliche
999 the tubes down which it passes, rrr an annular casing into which steam is
introduced surrounding the tubes q qq, ss a space into which the refuse falls to be
removed by the dredger m m, the water enters by the pipe t washing the refuse as
it comes up in the dredger buckets and passes down the dredger passage to the
thence
space s s and up the tubes qq and out by the pipe u into the settling tank
by the pipe v into the crystallisation tank w w (Fig. 4.) depositing there much of
the nitrate held in solution; the poor solution then flows back by the passage xx
and by the pipe y to the tank z whence it is pumped by pump a through the
pipe tt to the top of the dredger passage to be used again for the extraction of
nitrate in the retort.
The arrows in figs. 3 and 4 show the direction of the liquor. In any manu-
factory there is always at least one more crystallising tank that there are retorts
to allow time for the removal of nitrate from the crystallisation tank without
stopping the action of the retort. All the crystallisation tanks communicate with
the tank z by the pipe 8; the pipe y is for the purpose of running off the surplus
water from the tank w w when it is desired to remove the crystallised nitrate.
Fig. 5 is a plan and Fig. 6 a section of the crystallisation tank. The drawings
Figs. 2 and show heating by means of steam jackets-the condensed steam
returning to the boiler but the heating may be managed by the direct contact of
the gases from a furnace or where water is plentiful and free from impurities by
direct injection into the caliche by well known means.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:
1. The application to the extraction of Nitrate of Soda or other salt, from the
earths containing it, of a continuous process in which a current of water and a
current of the earths containing the salt are caused to move in opposite directions
through each other substantially as described.
2. The placing and maintaining of a body or mass of earths containing the
Nitrate of Soda or other salt above the hot liquor in the retort so that the steam
arising therefrom may be condensed in the body or mass of earths and returned
with it to the hot liquor.
3. For the purpose of producing Nitrate of Soda a crystallisation tank, in which
the heat of the hot liquor is partly dissipated and partly returned to the retort by
causing the liquor after having deposited most of the salts held in solution to flow
back in a contrary direction to that in which it flowed through the crystallisation
tank in contact with it and thereby possess itself of some of the heat of the
original solution.