Improvements in the Purification of Liquidės.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Purification of Liquidės.
I, HUGH MCPHAIL, of The Towers, Wakefield, in the County of York, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to the purification of liquids by the removal therefrom
of such objectionable ingredients as will chemically or mechanically associate
therewith or precipitate or filter out with the agent or agents used, and the said
invention i: applicable for the purification of, and for obtaining glycerine from,
such liquids as soap makers spent lyes, and other extracts obtained from animal
or vegetable matter. The invention is also applicable for the purification of dis-
tillates and of solutions of the residuum from stills in glycerine distillation.
In carrying out my invention I treat the liquid first with sulphurous acid, and
afterwards with a solution of sesquisulphate of iron, or I reverse this order of
treatment, or I treat the liquid with only one of these agents as may be desirable.
According to one method sufficient sulphurous acid is mixed with the liquid
to make it nearly neutral or slightly acid as may be necessary or desirable, and
then the liquid is neutralized or made slightly alkaline. Or according to another
method the liquid is allowed to flow by gravity down a tower or similar arrange-
ment containing lime stone or chalk while sulphurous fumes are passed upwards
through the tower, the fumes being regulated in quantity to nearly neutralize
or slightly acidify the liquid as required, and then the liquid is neutralized or
made slightly alkaline.
T next treat the liquid with a solution of sesquiaulphate of iron sufficient
to make it slightly acid and I afterwards neutralize or make the same slightly
alkaline. The treatment with sesquisulphate of iron as above described is
especially valuable if the liquid contains arsenic.
With the sesquisulphate solution I sometimes uso a small quantity of hydro-
chloric acid, or I use a solution of the sesquichloride of iron for coagulating the
albuminous matter, and sometimes I use a small quantity of organic acid for the
same purpose and for assisting the change from the alkaline condition.
I procure the sesquisulphate of iron in the following known manner, viz.: by
mixing with a solution of the protosulphate of iron exactly half as much sulphuric
acid as that salt contains and adding to the mixture in a boiling state successive
portions of nitric acid until nitrous fumes cease to appear. The solution is then
evaporated to dryness to expel the excess of nitric acid and the sesquisul-
phate remains as a powder. In some instances the mother-liquor of the protosulphate
may be used instead of the solution of the protosulphate. The sesquisulphate
may with advantage be obtained from iron turnings or borings or from the
Resquioxide or other compounds of iron with the proper proportion of sulphuric
acid, and boiling while adding successive portions of nitric acid as described
above.
In treating the liquid to be purified I may use either or both of the methods
described under the two main steps as may be necessary or desirable and the

page_text: operations may be repeated. After treatment as above stated and either before
or after but preferably before neutralizing the liquid it is of advantage to heat
or boil the liquid, I sometimes filter the liquid during and after the aforesaid
process, before evaporating or before distilling. A suitable filtering medium
Is metallic or red or brown hacmatite iron.
5
Improvements in the Purification of Liquids.
I, HUGH MCPHAIL, of Manygates House, Wakefield, in the County of York,
Engineer, late of The Towers, Wakefield, aforesaid, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement:-
This invention relates to the purification of soap-makers spent lyes, the weak
distallates in the production of glycerine, and other like liquids, by the removal
therefrom of objectionable ingredients such as albuminous and organic matters
and particularly arsenical compounds with which they are in many cases impreg-
nated.
The main object of the said invention is to render such lyes and other like
products obtained from animal or vegetable matters sufficiently pure to enable
practically pure glycerine to be obtained from them by the well known means.
In applying my invention, say to the treatment of soap lyes, which are in an
alkaline condition and which contain amongst other impurities, albuminous
matters and arsenical compounds, I first of all add to the said lyes a suitable weak
acid, for instance sulphurous acid, until the lyes are neutral or only very faintly
alkaline, and afterwards a solution of sesquisulphate of iron to neutralize or make
slightly acid, or I reverse this order of treatment, or I treat the liquid with only
one of these agents. as may be desirable and after such treatment I allow the
liquid to precipitate the separated impurities, or I filter, before evaporating.
The treatment with sulphurous acid may be effected say by mixing sufficient
sulphurous acid solution with the liquid, or sulphurous fumes may be injected
into the liquid with a steam jet or otherwise. Or according to another method
the liquid to bo neutralized may be allowed to flow by gravity down a tower or
similar arrangement containing lime stone or chalk while sulphurous fumes are
passed upward through the tower in sufficient quantity to nearly neutralize the
liquid. I then heat or boil the faintly alkaline lyes at the same time agitating
them by any suitable means, say by injecting steam into them which steam may
be superheated to avoid the unnecessary dilution by condensation that occurs
when saturated steam is used. At the same time or before boiling I add to the
lyes in only sufficient quantity to make them slightly acid and as already des-
cribed, a solution containing sesquisulphate of iron, that is to say Fe, (804) 3 which
may be produced in the manner hereinafter described.
The effect of this addition of the sesqui-sulphate of iron in the manner afore-
said, is that the albuminous matters or a great part of them, are caused during the
change from alkalinity to acidity to separate out as a flocculent precipitate, 80
that they can be removed by filtration or otherwise, and at the same time the
whole or greater part of the arsenical compounds will form an insoluble iron
compound and will be removed in such filtration.
If after these operations it is still necessary to further purify the lyes, I add

page_text: thereto any suitable non-caustic alkali, such for example as bi-carbonate of soda,
in quantity sufficient to just produce slight alkalinity, and during this chango
from acidity to alkalinity a further precipitation similar to that proviously referred
to, takes place and the precipitated matters may be removed by filtration as
before.
This operation of changing from an alkaline to an acid state and vice versa,
alternating with filtering or analogous operations, may be repeated as many times
as necessary, but I prefer by making preliminary trials with samples of the
lyes to add sufficient sesqui-sulphate of iron in the first instance to ensure the
purification, at least so far as the arsenical compounds are concerned, at one
operation.
In some cases where the lyes contain sulphate of soda I prefer to employ first
weak acid distillates, (referred to hereafter), hydrochloric acid, or a solution of
per-chloride of iron, and then, if necessary, a solution of the sesqui-sulphate of
iron, but as the latter of course tends by its combination with the alkali to increase
the percentage of sulphates, and it is therefore desirable to use as little as possible
in the lyes. Or I may use a sesqui-sulphate solution to which hydrochloric acid
has been added.
Although I have previously referred to the use of sulphurous acid for neutral-
izing the lyes in the first instance, yet I may employ other acids or the weak
distillates from crude glycerine which contains organic acids produced in the
distillation, the acidity of which may be increased by the oxidising action of air
blown through the said distillates. In this case the purification of the weak
<listillates is effected simultaneously with that of the lyes.
The purified lyes are then ready to be evaporated down to produce crude
glycerine in the ordinary way, which crude glycerine only requires to be distilled
and treated as usual in order to produce pure glycerine free from the impurities
in question.
In dealing with weak distillates by themselves for the purpose of freeing them
from arsenical compounds and other impurities I first render them neutral or
very slightly alkaline, in any suitable way and then treat them with sesqui-
sulphate of iron for the purpose of purifying them as above stated.
The sesqui-sulphate of iron may be produced in the following well-known
manner, viz. by mixing with a solution of the proto-sulphate of iron, exactly
half as much sulphuric acid as it contains, and adding nitric acid to the mixture
while the latter is in a boiling state, until nitrous fumes cease to appear. The
solution is then evaporated to dryness to expel the excess of nitric acid and the
sesqui-sulphate remains as a powder. In some instances the mother-liquor from
which proto-sulphate of iron has been obtained may be used instead of the solution
of proto-sulphate. Or the sesqui-sulphate may with advantage be obtained from
iron turnings or borings or from the sesqui-oxide or other compound of iron by
using the proper proportion of sulphuric acid, and boiling the same while adding
the nitric acid thereto as above described and finally evaporating the mixture
to dryness so as to expel any residual nitric acid.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. The method of purifying lyes and other liquids containing glycerine by
rendering them faintly alkaline or almost neutral and then adding to them sesqui-
sulphate of iron to render them slightly acid and to separate impurities, removing
such impurities by filtration or otherwise and repeating these operations as often
as necessary, substantially as and for the purposes described.
2. In the aforesaid method of purifying yes and other liquids containing
glycerine the employment of sulphurous acid or other weak acid to reduce their
alkalinity

page_text: 3. The use of the weak distillates to reduce the alkalinity of the lyes sub-
stantially as described.
4. The method of purifying weak distillates (obtained in glycerino distillation)
simultaneously with the lyes by mixing the weak distillates with the lyes before
their purification, thus enabling the glycerine in the weak distillates to be recovered
along with that in the lyes, substantially as described.
bruary Love.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.