Improvements in the Production of Colloidal Tannates as Disincrus- tants, for Use in Land and Marine Boilers, and for other Purposes.
Year: 1898

page_text: Date of Application, 3rd Sept., 1898-Accepted, 10th Dec.,
1898
Improvements in the Production of Colloidal Tannates as Disincrus-
tants, for Use in Land and Marine Boilers, and for other Purposes.
I, THOMAS HENRY COBLEY, of 3, Regent Street, Dunstable, in the County of
Bedford, Chemist, 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 the production of colloidal tannates as disincrustants
for use in land and marine boilers and is carried out in such a way as to materially
reduce the cost of manufacture by the employment of certain natural products
and waste materials in their crudest forms, and at the same time effecting special
results in point of quality or properties for the intended purpose, and thus bringing
such disincrusting agents within the reach of all employers of steam.
In carrying out my invention I employ partly a hot and partly a cold process
according to the class of materials under treatment which I will now describe.
When treating crude natural products such as the root of the canaigre plant,
the leaf of the sumac plant or the bark of the mimosa tree or analogous sources of
tannin, the material is first comminuted by slicing, crushing or shredding and
is then placed in a steam jacketted boiler or vacuum pan having an agitator. A
sufficient quantity of an aqueous solution of an alkali such as soda carbonate or
sulphite is added and the whole submitted to heat and agitation.
The amount of alkali to be employed is regulated by the per-centage of tannin
present in the raw materials and this may be determined by ordinary tests.
Where the raw material also contains vegetable colloidal matter such as gluten,
saccharin or gum and the like it will be necessary to allow an additional amount
of alkali to form the colloidal alkaline combination. As a fair working proportion
the amount of alkali used should be about 35 per cent. of the tannic acid present
in the natural material.
The above treatment is continued for some time and the temperature is then
raised to about 150° Fahrenheit which is maintained until the tannin has been
extracted which can be ascertained by testing samples taken from time to time.
Where gluten, saccharine matter or gum is present the temperature may at the
close of the operation be raised for a short time to the boiling point.
The charge is now drawn and passed through rollers so as to separate out the
iquid portion, and when sufficient colloidal matter is not present in this alkaline
xtract it is added in proper proportion and the whole thoroughly mixed and if
ecessary heated and after this run into barrels ready for use.
The additional colloidal matter that may be required as above described I obtain
from various waste matters such as leather waste accompanied by tannin,
tarch waste and animal waste. I prefer to use leather waste from which to form
base for the so called colloidal tannate and my process for carrying this out
onsists in subjecting the leather waste after a preliminary disintegration to a
eries of cold steeps, in closed vessels with agitators, in an alkaline solution of
oda carbonate or sulphite in the proportion of about 25 per cent. of the soda salt

page_text: to the weight of the leather waste under treatment. When the liquor which
should consist of a cold drawn alkaline extract of tannin and gelatine is strong
enough which is a matter of practical judgment it is strained off and added in
proper proportions to the tannin compound formed in the first described process.
The proportions should be sufficient to neutralise the free alkali present in the
liquor and then the temperature is raised and a suitable combination of the whole
is formed. The temperature should not exceed 150° Fahrenheit.
In this secondary process a larger amount of tannin may be obtained accom-
panied by some colloidal matter if, after the principal yield of extract by means
of alkali has been obtained, a quantity of sour consisting of diluted sulphurous
acid is introduced and the leather residue again treated with this it will yield a
further quantity and the liquor so prepared may be used in the steeping operations
instead of plain water.
The disincrusting liquor thus produced may be employed in the ordinary way,
the proportions necessary for combatting the scale producing impurities in the
water used may be determined from time to time by experiment.
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:-
The herein described improvements in the production of colloidal tannates more
particularly for use as disincrustants for steam boilers.
THAN 1000