Year: 1886

page_text: ALFRED HENRY ALLEN, Consulting Chemist, of Surrey Street, Sheffield, in the
County of York, and BENJAMIN NICKELS, Consulting Chemist, of 104, Leadenhall
Street, London; do hereby declare the nature of this invention to be as follows:-
Our Invention relates first to the treatment of soapmakers' leys, crude glycerine,
and similar liquids, with a view to the removal of the objectionable impurities
which interfere with the recovery of a good quality of glycerine.
The spent ley from soap-making is essentially a dilute aqueous solution of
glycerine, containing a considerable quantity of common salt, together with very
variable quantities of alkaline sulphates, sulphites, hyposulphites, sulphides, sulpho-
cyanides, ferrocyanides, cyanides, cyanates, formates, and other salts of a more or
less objectionable character, besides fatty, resinous, albuminous, and colouring and
undefined organic matters.
To effect the purification of the crude leys, we add to the liquid a solution of
sulphate of copper as long as a precipitate continues to be produced. If the ley is
very alkaline, we prefer to neutralise the liquid first of all with sulphuric, hydro-
chloric, or other suitable acid, but if the alkalinity is not excessive, or if the solution
of copper employed contain much free acid, this step can be wholly or partially
omitted at discretion; but when the precipitation is complete the liquid should be
neutral or somewhat acid rather than alkaline.
We ascertain the completeness of the precipitation by testing a portion of the
filtered liquid with a few drops of the copper solution and a soluble sulphite, and
we then prefer to add a further quantity of copper solution to the liquid to effect
the decomposition of certain impurities which are not actually precipitated by the
copper solution.
The addition of the copper solution causes the formation of a precipitate con-
taining all the sulphides, cyanides, sulphocyanides, and ferrocyanides contained in
the original leys, together with the fatty, resinous, albuminous, colouring and.
undefined organic matters. By reaction with the copper solution, other objection-
able impurities, such as sulphites, hyposulphites, formates, etc., are oxidised to
harmless matters, without undergoing actual precipitation. When these impurities
are present in considerable quantity we prefer to heat the liquid to boiling, but this
treatment is not essential.
The precipitation having been ascertained to be complete, and a moderate excess
of copper solution having been added, we remove the precipitate by subsidence,

page_text: decantation, filtration, or other suitable means, but preferably by means of a
filter-press.
The filtered liquid is then treated for the removal of the excess of copper. This
can be done in any known way, such as by the addition of a soluble carbonate,
sulphide, ferrocyanide, sulphocyanide, etc, or by the aid of a current of electricity.
In most cases we prefer to precipitate the copper by the introduction of sul-
phuretted hydrogen gas, employed in the least possible excess, whereby a black
precipitate of copper sulphide is produced which can be removed by subsidence,
filtration, or in other suitable way. When iron is present, either in the ley or the
copper solution employed, the addition of a soluble ferrocyanide in the faintest
possible excess may be substituted for the treatment with sulphuretted hydrogen,
when the precipitate produced will contain every trace of the iron and copper
present in the liquid.
The clear liquid separated from the precipitate of copper sulphide, ferrocyanide,
or other compound or compounds into which the excess of copper and iron may
have been converted, is then neutralised or rendered slightly alkaline by addition
of soda-ash or similar substance, and is then ready for concentration in the usual
manner, when the resultant glycerine is obtained of a very pale colour and of far
superior quality to that ordinarily obtained from similar leys.
Crude glycerine, preferably after being somewhat diluted with water, can be
purified by treatment in a manner similar to that already described for the
purification of spent leys.
Although we use by preference a solution of sulphate of copper for the pre-
cipitation of the impurities, we do not restrict ourselves to the use of that reagent,
but may use the chloride or other salt or compound of copper, either alone or in
conjunction with the sulphate of copper, or with the sulphates, chlorides, or other
compounds of other metal or metals, or we may use a current of electricity and
an anode of copper or copper-alloy as a means of obtaining the copper necessary for
the reaction.
In some cases, as when the ley is very rich in ferrocyanides, we prefer to precede
the treatment with copper by the addition of a solution of persulphate of iron, or
other soluble iron salt other than the chloride, removing the resultant precipitate
by filtration or other convenient means.
When the locality in which the process is conducted allows of the advantageous
adaption of such a plan, we employ the cupreous liquors obtained in the wet
process of extracting copper from cupreous pyrites for effecting the purification of
the glycerine.
Our Invention relates secondly to the treatment of the precipitates obtained in
the foregoing operations, for the recovery of copper and other valuable products
therefrom.
As a rule, we prefer to treat the precipitates containing copper by roasting them
at a red heat in a reverberatory furnace, whereby we obtain a residue consisting
chiefly of oxide of copper. This we treat with sulphuric acid or other suitable
acid, and thus obtain a solution of sulphate or other salt of copper, which we
employ for treating a further quantity of spent leys or crude glycerine. In the
case of precipitates rich in ferrocyanides, we boil them with a solution of caustic-
soda, soda-ash, or other suitable reagent, and remove the oxides of iron and copper
produced. The solution of alkaline ferrocyanide obtained we concentrate for the
production of solid ferrocyanides, or we employ it for removing the iron and copper
from another portion of the leys. Precipitates consisting essentially of ferrocyanide
of iron have at once a marketable value.
1
Aument 1006
ALFRED H. ALLEN.
BENJAMIN NICKELS.

page_text: ALFRED HENRY ALLEN, Consulting Chemist, of Surrey Street, Sheffield, in the
County of York, and BENJAMIN NICKELS, Consulting Chemist, of 104, Leadenhall
Street, London, do hereby declare the nature of our invention for THE TREATMENT
OF SOAP LEYS, CRUDE GLYCERINE, &C, FOR THE REMOVAL OF IMPURITIES, &C.
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
Our Invention relates first to the treatment of soapmakers' leys, crude glycerine,
and similar liquids, with a view to the removal of the objectionable impurities
which interfere with the recovery of a good quality of glycerine.
The spent ley from soap-making is essentially a dilute aqueous solution of
glycerine, containing a considerable quantity of common salt; together with more
or less free alkali and very variable quantities of alkaline sulphates, sulphites,
hyposulphites or thiosulphates, sulphides, sulphocyanides or thiocyanates, ferro-
cyanides, cyanides, cyanates, carbonates, silicates, and other salts and compounds of
a more or less objectionable character; besides fatty, resinous, albuminous, and
colouring and undefined organic matters.
To effect the purification of the crude leys we take advantage mainly of the
reaction of the various impurities with soluble salts of copper, by which means
invaluable precipitates are formed containing many of the impurities, whilst others
are oxidised and destroyed by the same treatment. We modify the exact mode of
employing the copper compounds according to the impurities to be removed, and
the facilities for dealing with the secondary products.
As a rule, before proceeding to the treatment with copper, we prefer to neutralise
the free alkali of the leys by adding hydrochloric or other suitable acid, and in
most cases we continue this addition until the liquid has a distinctly acid reaction
to litmus paper. If the leys contain ferrocyanides, and traces of iron compounds
be also present, either in the leys or the crude hydrochloric acid added, the point
of acidification is indicated by the precipitate assuming a distinct bluish tint, from
the formation of Prussian blue. The addition of hydrochloric acid in slight excess
results in the neutralization of the free alkali and the decomposition of the
carbonates, cyanides, and cyanates which may be present. The precipitate is often
of a very complex nature, containing more or less fatty acids, resin, albunin and
ferrocyanide of albumin, ferrocyanide of iron, silica, colouring matters, &c. It may
be removed by subsidence, filtration, or in other convenient known manner. The
employment of acid as a preliminary stage of the treatment of crude soap leys is in
no way novel, and we make no claim with respect to the method of conducting the
process.

page_text: In the case of the product known as "Lancashire leys," and in other cases where
ferrocyanides are present in notable quantity, we prefer next to treat the acidified
leys with a solution of iron, as long as a precipitate continues to be formed, and
we then remove the precipitate by subsidence, filtration, or other suitable means.
In some cases, we substitute for the solution of iron one of zinc, tin, or other metal
forming an insoluble ferrocyanide. The solution may be one of any suitable
soluble salt of iron or other metal required, provided it be not one employed by
any previous Patentee; but we make no claim to the treatment with a solution of
iron or other metal except in connection with the use of copper in some form.
In some cases, we add the iron or other metallic solution without previously
separating the precipitate produced on acidifying the leys, and if the iron or other
metallic solution be very acid the previous treatment of the leys with acid may be
wholly or partially omitted at discretion; but before filtering from the mixed
precipitate the solution should be distinctly acid in its reaction.
We must proceed to treat the filtered liquid with a solution of copper. This
may be any soluble salt or compound of copper, and either cuprous or cupric salts
are available. We employ by preference a solution of the sulphate or chloride of
copper, or a mixture of the two; but we do not restrict ourselves to the use of
these only, but may employ any other salt or compound of copper, either alone or
in conjunction with the sulphate or chloride of copper, or with the sulphates,
chlorides, or other compounds of other metal or metals. When the locality in
which the process is conducted allows of the advantageous adoption of such a plan,
we employ the cupreous liquors obtained in the wet process of extracting copper
from cupreous pyrites for effecting the purification of the glycerine solution.
The addition of the copper solution causes the formation of a precipitate
containing all the sulphocyanides present in the leys, together with traces of other
matters not removed by the previous treatment. If a solution of a cupric salt be
employed, the precipitation of the sulphocyanides is accompanied by a simultaneous
oxidation to sulphate of an equivalent amount of any sulphites and hyposulphites
present in the solution. If the previous treatment with iron solution has been
omitted, the precipitate produced by the copper solution will contain any
ferrocyanides present in the liquid, together with fatty, resinous, albuminous,
and colouring matters.
In many cases we find it convenient to omit, not only the treatment with iron
solution, but also the separation of the liquid from the precipitate produced on
acidifying the leys, and to add the copper solution directly to the liquid containing
this precipitate in suspension. If the copper solution contain much free acid, the
previous treatment of the leys with acid may be wholly or partially omitted at
discretion, the amount of acid employed being adjusted so that, after the addition
of the full amount of copper solution intended to be employed, the liquid shall be
distinctly but not extremely acid in reaction.
The quantity of copper solution which it is requisite to add to the leys or crude
glycerine solution necessarily depends on the nature and proportion of the
impurities to be removed. The copper solution may either be added in quantity
just sufficient to effect complete precipitation of all precipitable matter, or it may
be employed in decided excess. In the first case, the amount required may be
previously ascertained by a laboratory assay, or the copper solution may be added
gradually, in small quantities, allowing time for the complete formation and
subsidence of the precipitate. In the case of leys containing sulphocyanides, the
completeness of the reaction may be conveniently ascertained by testing a portion
of the filtered liquid with a few drops of the copper solution and a soluble sulphite,
which will produceļa white precipitate if sulphocyanides still remain unprecipitated.
Similarly, the presence of an excess of copper in the solution will be indicated by
the formation of a white precipitate on adding a solution of a soluble sulphite
mixed with that of a soluble sulphocyanide.
The copper solution having been added in proper quantity, we, in some cases,
heat the liquid to boiling, but this treatment is not essential. Ample time is then

page_text: allowed for the complete formation and subsidence of the precipitate, which is
then removed by decantation, filtration, or other suitable means, but preferably by
the aid of a filter-press.
The mode of treatment of the liquid separated from the copper precipitate
depends on the employment of the copper solution in exact quantity or in excess.
If the liquid be practically free from copper it may possibly contain hyposulphites,
if these were originally present in quantity more than equivalent to the sulpho-
cyanides. They may be destroyed by any suitable means, that preferred by us
being their oxidation to sulphates by adding to the liquid a solution of a soluble
hypochlorite in exactly the requisite amount, as previously ascertained by a
laboratory experiment. We make no claim for the use of hypochlorite solution
for destroying the hyposulphites, and in many cases this stage of the process is
unnecessary.
If the copper solution has been employed in excess, and in quantity as to give
the filtered liquid a distinct blue tinge, all sulphites and hyposulphites will have
undergone oxidation to sulphates, and the treatment with a hypochlorite solution
is unnecessary. On the other hand, the filtered liquid must be treated for the
removal of the copper. This can be done in any known way, such as by the
addition of a soluble carbonate, sulphide, ferrocyanide, sulphocyanide, &c, or by
the aid of a current of electricity. In most cases, we prefer to precipitate the
copper by the introduction of sulphuretted hydrogen gas, employed in the least
possible excess, whereby a black precipitate of copper sulphide is produced, which
can be removed by subsidence, filtration, or in other suitable way. When iron is
present, either in the ley or in the copper solution employed, the addition of
a soluble ferrocyanide in the faintest possible excess, or in the exact quantity
necessary to effect complete precipitation, may be advantageously substituted for
the treatment with sulphuretted hydrogen.
The clear liquid resulting from the preceding operations is next neutralised or
rendered slightly alkaline by addition of soda-ash or similar substance, and is then
ready for concentration in the usual manner, when the resultant glycerine is
obtained of a very pale colour and of far superior quality to that ordinarily
obtained from similar leys.
In some cases, we find a still paler product is obtainable by considerably
concentrating the neutralised liquid before separating the excess of copper, any
further precipitate being removed by filtration. The addition of a solution of
a small proportion of the chloride or other soluble salt of lead is occasionally useful
for removing the last traces of colouring matter; but such treatment is not
essential and forms no part of our invention.
We have found that, when desired, the solutions of iron and copper we usually
employ may be replaced by passing a current of electricity through the leys, an
anode of iron or iron-alloy, copper or copper-alloy, being used as a means of
conducting the current. With an electromotive force equal to about two of
Grove's cells, or even less, an iron anode effects the complete removal of the
ferrocyanides, while the byposulphites are broken up and destroyed with precipi-
tation of sulphide of iron. The use of a copper-anode effects in addition the
complete precipitation of the sulphocyanides, while albuminous and other organic
impurities also undergo precipitation or destruction.
Although usually preferring to perform our operations, or the majority of them,
on the original leys, untreated by concentration or other means except filtration
from particles of soap and other suspended matter, in some cases we find it
desirable to concentrate the liquid before proceeding with the purification by
chemical treatment.
Crude glycerine, preferably after being somewhat diluted with water, can be
purified by treatment in a manner similar to that already described for the
purification of spent leys.
Our Invention relates secondly to the treatment of the precipitates obtained in
the foregoing operations, for the recovery of copper and other valuable products

page_text: therefrom. As a rule, we prefer to treat the precipitates containing copper by
roasting them at a red heat in a reverberatory furnace, whereby we obtain a residue
consisting chiefly of oxide of copper. This we treat with sulphuric acid, or other
suitable acid, and thus obtain a solution of the sulphate or other salt of copper,
which we employ for treating a further quantity of the leys or crude glycerine.
An alternative method consists in treating the precipitate with water and caustic
soda or other strong base, whereby an oxide of copper is obtained and a soluble
ferrocyanide or sulphocyanide simultaneously produced; or a soluble sulphide may
be employed to decompose the precipitate. Such methods are not well suited for
the treatment of precipitates containing much albumin or other organic matter.
The precipitate produced by the addition of iron solution consists chiefly of
ferrocyanide of iron, but usually contains more or less sulphur, silica, albuminous
matter, and other impurities, which prevent its direct employment as a blue
pigment. When not too impure we utilize it by treating it with a caustic alkali
or other strong base, or an equivalent or otherwise suitable reagent, so as to obtain
the iron in an insoluble form together with a soluble ferrocyanide.
The solutions of soluble sulphocyanides and ferrocyanides obtained as above
described may be concentrated for the production of the solid salts, or may be
employed for the precipitation of iron, copper, or other heavy metals which may be
present in the leys, or may have been introduced in the treatment.
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 employment of metallic copper, or of a sulphate, chloride, or other
suitable salt or compound of copper, for the purpose of removing impurities from
spent soap-leys and other solutions containing glycerine.
2. The employment of a current of electricity and an anode of copper, copper
alloy, or other metal or metallic alloy, as a means of purifying soap-leys and other
solutions containing glycerine.
3. The preparation of glycerine by concentration, distillation, or other known
methods, from soap-leys and other crude glycerine solutions which have been
treated by one or more of the processes herein claimed.