An Improved Process for the Dry Slaking of Lime and Apparatus therefor
Year: 1899

page_text: COMPLETE SPECIFICATION (AMENDED).
"An Improved Process for the Dry Slaking of Lime and Apparatus
therefor "
I, RICHARD JAEGER of 1 Bevernstrasse, Berlin in the Empire of Germany, 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 has for its object a process for the dry slaking of lime with total
exclusion of air and under a superpressure formed by the slaking.
The improved apparatus for carrying out this process is shown in the accompanying
drawings, Figure 1 being a side elevation partly in section, and Figure 2 a similar
view of a modification.
For this object a drum d of suitable strong sheet metal is revolubly mounted in a
frame on trunnions c, the interior of said drum being accessible through a manhole ↳
capable of being tightly closed.
The drum is also provided with an air tap 9, fitted if desired with safety valve
and nanométer h, and also with a water supply tap d, the latter being connected
with a measured water vesself by means of a pipe e.
The burnt lime is conveyed into the drum in suitable quantity through the
manhole b, and the latter is then closed so as to be steam tight. The air tap g and
the water tap d are then opened so that a definitely determined quantity of water
flows into the drum precisely sufficient to convert the burnt lime contained in the
drum completely into hydrate of lime. The tap d is then closed, and as soon as air
no longer escapes from the tap g but on the contrary steam begins to escape the said
tap is also closed.
The pipe e is then removed from the tap d and the drum set in
rotation. The burnt lime is thus moistened through, evenly and thoroughly by the
added water. The contents become strongly heated and the drum is filled by the
surplus steam as yet uncombined with the lime, said steam having a high temperature
and corresponding pressure. The already disintegrated and slaked lime is constantly
stirred up by the rotation of the drum in the hot steam filling the said drum and is
also constantly moved until even the particles of lime which are most difficult to
slake are converted into caustic lime by the absorption of water.
In this slaking process no further water can flow in nor steam escape so that the
lime is slaked with precisely the quantity of water necessary to form a thoroughly
dry hydrate of lime.
As with a very good quality of lime the heat evolved by the slaking may rise to a
verv great height, so that too great a pressure might result in the drum which would

page_text: endanger the safety of the operation if no safety valve were provided, in such cases a
portion of the necessary water for the dry slaking of lime is replaced by the insertion
in the drum of damp sand and thereby the temperature and pressure resulting in the
drum may be reduced according as may be desirable. If the water contents of the
added sand be exactly known then we shall know how much water has been added to
the lime to be slaked by the damp sand and how much must still be allowed to flow
as water directly into the drum.
The drum a may as shown in Figure 2 be provided with hollow trunnions which
carry at their ends a tap d, a tap g, a manometer h and the safety valve i.
Of course instead of a revoluble drum a fixed vessel may also be employed, which
in that case must be provided with a suitable stirring apparatus.
I wish it to be understood that I am aware that various processes have been heretofore
proposed for the dry slaking of lime and I make no claim to any such process or
apparatus therefor unless it combines the four elements hereinbefore described or means
therefor viz:-
1. The addition of the measured quantity of water required to convert the lime into
dry hydrate
2. A steam tight vessel capable of withstanding the pressure generated and preventing
escape of water.
3. High temperature and pressure
4. Thorough mechanical intermixture under such temperature.
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. A method for the dry slaking of burnt lime, characterised by the lime being
placed in a vessel or vessels capable of being closed so as to be steam tight, with a
ineasured quantity of water which remains unaltered or unchanged during the slaking,
and being thoroughly intermixed by at the high temperature produced in the
container substantially as hereinbefore set forth.
2. A modification of the process herein before described for the dry slaking of lime,
consisting in replacing the quantity of water necessary for a dry slaking of the lime
.either wholly or partially by means of damp sand substantially as and for the purpose
set forth.
3. An apparatus for carrying out the hereinbefore described process for the dry
slaking of lime consisting of a drum (a) revoluble on trunnions, and provided with a
manhole (6), water tap (d), and air venting tap (g) and adapted to receive the lime
to be slaked, substantially as described.
4. A modification of the apparatus herein before described for the dry slaking of
lime characterized by the drum (a) being fixed but provided with a suitable agitating
or stirring apparatus, substantially as described.
Dated this 18th day of February 1899
WM. P. THOMPSON & Co.
Of 6, Lord Street, Liverpool, Agents for the Applicant.