IMPROVEMENTS IN PURIFYING LIQUIDS. IN OBTAINING OR PREPARING THE PURIFYING AGENTS, IN RECOVERING, TREATING, AND UTILIZING MATTERS CONTAINED INT BUCH LIQUIDS, AS WELL AB OTHER WASTE OR BYE-PRODUCTS OF MANUFACTURES, AND IN MEANS OR APPARATUS EMPLOYED THEREFOR
Year: 1875

page_text: LETTERS, PATENT to George Mackay, of Edinburgh, in the County
of Mid Lothian, North Britain, Manufacturing Chemist, for the
Invention of "IMPROVEMENTS IN PURIFYING LIQUIDS. IN OBTAINING OR
PREPARING THE PURIFYING AGENTS, IN RECOVERING, TREATING, AND UTILIZING
MATTERS CONTAINED INT BUCH LIQUIDS, AS WELL AB OTHER WASTE OR
BYE-PRODUCTS OF MANUFACTURES, AND IN MEANS OR APPARATUS EMPLOYED
THEREFOR."
Scaled the 6th July 1875, and dated the 11th January 1875.
PROVISIONAL SPECIFICATION left by the said Robert Mackay at the
Office of the Commissioners of Patents, with his Petition, on the
11th January 1875.
I, GEORGE MACKAY, of Edinburgh, in the County of Mid Lothian,
North Britain, Manufacturing Chemist, do hereby declare the nature
of the said Invention of "IMPROVEMENTS IN PURIFYING LIQUIDS, IN OBTAINING
OR PREPARING THE PURIFYING AGENTS, IN RECOVERING, TREATING, AND UTILIZING
MATTERS CONTAINED IN SUCH LIQUIDS, AS WELL AS OTHER WASTE OR BYE-PRODUCTS
OF MANUFACTURES, AND IN MEANS OR APPARATUS EMPLOYED THEREFOR," to be as
follows, that is to say:—
'
This Invention relates, urst, to the purnying or water, sewage, and
[Price 8d.]
1

page_text: other liquids effluent from paper pulp and fibre mills; from bleaching,
dyeing, scouring, and finishing works; from cotton, woolen, and linen
manufactories; from gas, tar, oil, glue, gelatine, and size works; from
tanners', skinners', and curriers' yards; and from works, manufactories,
or other situations generally, from which there is an efflux of impure 5
water or other liquid, and to recovering, treating, and utilizing the
matters or "sludge," whether animal, vegetable, or mineral, contained
in such water or other liquids.
The Invention relates in the second place to the obtaining or preparing
of the chemical or other agents employed in such purification and
recovery of the matters or "sludge," and to the recovery, treatment, and
utilization of the waste or bye-products of manufacture in obtaining or
preparing such agents, or for other purposes.
In purifying water or other liquids in accordance with this Invention
an admixture in equal or other suitable proportions of per-chloride of 1
iron, commonly called sesqui-chloride or per-muriate, with per-sulphate
or other suitable per-salt of iron, is employed. The said admixture need
not be chemically or commercially pure, and it may or may not be
further admixed or combined with any suitable sub-salt of iron, the
sub-salts obtained from alum, alkali, and galvanizing works being 20
preferably employed. The water or other liquid to be treated is placed
in a tank or receptacle, and the salt solution added thereto. These are
then agitated or stirred together with the liquid for such length of time
as is requisite to effect combination of the solution with the vegetable,
animal, or mineral matters or "sludge contained in the liquid. The 25
duration of agitation in great measure depends on the amount of
impurities or matters present, as well as on the nature of the liquid
itself. When the combination of the salts with the matters has been
effected a quantity of alkali or alkaline earth, lime being preferably
used, is added, and the stirring or agitating continued until combination 30
or chemical union thereof with the salts is effected. The liquid is then
allowed to settle, when the matters or "sludge " held in suspension are
precipitated, and may thereafter be removed from the tank or receptacle
as desired; or the supernatant and purified liquid may be decanted, and
the precipitate or "sludge " allowed to remain in the receptacle.
The proportion of the iron-salt solution relatively with the impure
liquid may be from 1 to 10 parts of the solution to 10,000 (ten thousand)
parts of the liquid operated on, and a similar or other proportion of
35

page_text: alkali or alkaline earth may be used, the total amount of such alkali or
alkaline earth being sufficient to decompose all the free chloride and
other salts of iron used. It is to be here understood that the Invention
is not limited to the proportions herein given.
The greater number of precipitates obtained by the process herein.
before described lose their affinity for water, and are thus easily dried by
any ordinary means and reutilised. This is especially the case with the
precipitate or "sludge " obtained from the effluent water of paper pulp
and fibre mills, and to the utilization of such sludge this Invention is
particularly applicable.
The said precipitate when obtained is dried in a centrifugal machine
in a vacuum apparatus, or in any suitable arrangement of pressing or
drying machine, and it may thereafter be returned into the paper engine
either alone or in combination with fresh pulp or "strong stuff," such as
old canvas, ropes, or other similar material and converted into paper; or
it may be employed as a size in substitution for china clay in paper
making, or for other purposes, such as manure or artificial fuel.
The deposit or "sludge" obtained by natural gravitation may be
reutilized either by adding sufficient water to enable it to be agitated
with the combined or admixed per-salts of iron, or a per-oxide of iron
may be intimately blended therewith in the proportion of from 2 to 10
per cent. of the per-oxide, or in other suitable proportion when the
admixture, either dried or not, may be utilized as previously described.
The per-chloride of iron employed in purifying the liquids may be
obtained in any of the customary modes, or in accordance with the
second part of this Invention. It may be obtained by digesting from
3 to 5 parts of that form of the hydrated per-oxide of iron known as
bog ore or ochre with 1 to 2 parts of muriate or hydrochloric acid, and
with or without the aid of heat. The digestion is continued for 48 hours
or thereby, or until a saturated solution is obtained, which solution may
be concentrated to any desired degree by placing it in a suitable vessel
provided with condensing apparatus, and applying heat thereto when the
free hydrochloric acid and water pass off and are condensed for further
use.

page_text: lime, tanners' lime, soap lime, and varies according to the nature of the
work at which it is produced.
The second part of this Invention further relates to the recovery and
utilization of such lime which has a great affinity for water. To deprive
it of its affinity and to render it available for building as a cement for
. employment in the purification of gas for glass making, and for agri-
cultural and other similar purposes, the refuse lime is mixed with from
10 to 20 parts of coal dust or other slack, and with a similar amount of
soda liquor derived from the boiling of esparto grass or rags in the
manufacture of paper; or other suitable spent alkaline liquor may be
used in lieu thereof. The mixture is effected by any suitable mechanical
means and allowed to stand until of such consistency that when pierced
with a rod the aperture remains when the rod is withdrawn. The
mixture is then placed in a calcining kiln of suitable construction,
preferably consisting of a cone, whose height is about double the base.
The cone rests on or is provided with a fire-grate, under which an ash-
pit is situated. A fire is first kindled on the grate, and the lime mixture
laid thereon and pierced with numerous apertures over its surface down
to the live coal. A powerful draught is thereby caused in the kiln,
whilst at the same time the products of combustion are allowed to pass
upwards, and these are followed by the flame, which first dries the lime
mixture and then consumes the coal dust or slack, the heat produced
by the combustion of which converts the lime from carbonate into
caustic lime, which being effected the caustic lime gradually falls
through the grate bars into the ash-pit, and is from thence removed.
The kiln may be provided with a pipe at its upper end, through
which the waste heat may be conducted and utilized, or the pipe may
be connected to a chimney. The kiln may or may not also be formed
with holes around its base for the purpose of stoking.
As the combustion proceeds fresh quantities of the lime mixture are ;
added, so that the process is continuous.
The addition of soda liquor or ley to the lime compound as herein-
before described may in some cases be dispensed with
1

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Mackay in the Great Seal Patent Office on
the 10th July 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, GEORGE
MACKAY, of Edinburgh, in the County of Mid Lothian, North Britain,
Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of January, in the
year of our Lord One thousand eight hundred and seventy-five, in
the 38th year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said George Mackay, Her special
license that I, the said George Mackay, my executors, administrators,
and assigns, or such others as I, the said George Mackay, my executors,
administrators, or assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN PURIFYING LIQUIDS, IN OBTAINING OR PREPARING THE PUBIFYING AGENTS, IN
RECOVERING, TREATING, AND UTILIZING MATTERS CONTAINED IN SUCH LIQUIDS,
AS WELL AS OTHER WASTE OR BYE-PRODUCTS OF MANUFACTURES, AND IN MEANS OF
APPARATUS EMPLOYED THEREFOR," upon the condition (amongst others) that
I, the said George Mackay, by an instrument in writing under my hand
and seal, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said George Mackay, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, that is to say:-
My said Invention relates, first, to the purifying of wafer, sewage,
and other liquids effluent from paper pulp and fibre mills, from bleaching,
dyeing, scouring, and finishing works; from cotton, woollen, and linen
manufactories; from gas, tar, oil, glue, gelatine, and size works; from

page_text: tanners', skinners', and curriers' yards; and from works, manufactories,
or other situations generally, from which there is an efflux of impure.
,water or other liquid; and to recovering, treating, and utilizing the
matters or "sludge," whether animal, vegetable, or mineral, contained
in such water or other liquids.
The Invention relates in the second place to obtaining or-preparing
the chemical or other agents employed in such purification of the liquids
and recovery of the matters or "sludge" contained therein; and also
to the recovery, treatment, and utilization of the waste or bye-products
of manufacture in obtaining or preparing such agents, or for other
purposes.
In purifying water or other liquids in accordance with the first part
of my said Invention an admixture in equal or other suitable proportions
of per-chloride of iron, commonly called sesqui-chloride or per-muriate,
with per-sulphate or other suitable per-salt of iron is employed. The
said admixture need not be chemically or commercially pure, and it
may or may not be further admixed or combined with any suitable
sub-salt of iron, the sub-salts obtained from alum, alkali, and galvanizing
works being preferably employed. The water or other liquid to be
treated is placed in a tank or receptacle and the salt solution added
thereto, and agitated or stirred with the liquid for such length of time
ȧs is requisite to effect combination of the solution with the vegetable,
animal, or mineral matters or "sludge" contained in the liquid. The
duration of agitation in a great measure depends on the amount of
impurities or matters present as well as on the nature of the liquid
itself. When the combination of the salts with the matters has been
effected a quantity of alkali or alkaline earth (lime being preferably
used) is added, and the stirring or agitating continued until combination
or chemical union of the alkali or alkaline earth with the salts is effected.
The liquid is then allowed to settle, when the matters or "sludge” 3
held in suspension are precipitated and may thereafter be removed from
the tank or receptacle as desired, or the supernatant and purified liquid
may be decanted, and the precipitate or." sludge " allowed to remain in
the receptacle.
The proportion of the iron-salt solution relatively with the impure s
liquid may be from 1 to 10 parts of the solution to 10,000 (ten thousand)
nents of the liquid amounted on

page_text: alkali or alkaline earth may be used, the total amount of such alkali or
alkaline earth being sufficient to decompose all the free chloride and
other salts of iron used. It is to be here understood that although I
have obtained good results with the proportions herein-before stated the
Invention is not limited to such proportions.
The greater number of precipitates obtained by the process herein-
before described lose their affinity for water, and are thus easily dried
by any ordinary means and rendered capable of being reutilized. This
is especially the case with the precipitate or "sludge" obtained from
the effluent water of paper pulp and fibre mills, and to the utilization of
such “sludge” this Invention is particularly applicable.
The said precipitate when obtained is dried in a centrifugal machine
in a vacuum apparatus, or in any equivalent arrangement of pressing or
drying machine, and it may thereafter be returned into the paper engine
either alone or in combination with fresh pulp or "strong stuff," such
as old canvas, ropes, jute, jute waste, esparto grass, straw, or other
paper making material, and converted into paper, millboard, pasteboard.
or cardboard, or it may be employed as a size in substitution for china
clay in paper-making, or for other purposes such as manure or artificial
fuel.
The deposit or "sludge" obtained by natural gravitation, that is
to say, the matter which is precipitated from the water whilst flowing
through a course or channel may be reutilized either by adding sufficient
water to enable it to be agitated with the combined or admixed per-salts
of iron, or a per-oxide of iron may be intimately blended with the said
matter in the proportion of from 2 to 10 parts of the per-oxide to 100
(one hundred) parts of the matter or "sludge," or in other suitable pro-
portion when the admixture, either dried or not, may be utilized as
previously described.
The per-chloride of iron employed in purifying the liquids may be
obtained in any of the customary modes, or in accordance with the
second part of my said Invention it may be obtained by digesting from
3 to 5 parts of that form of the hydrated per-oxide of iron known as
bog ore or ochre, with 1 to 2 parts of muriatic or hydrochloric acid and
with or without the aid of heat. The digestion is continued for 48 hours,
or until a saturated solution is obtained, which solution may be concen-
rated to any desired degree by placing it in a suitable vessel provided

page_text: with condensing apparatus and applying heat thereto, when the free
hydrochloric acid and water pass off and are condensed for further use
leaving a concentrated solution of per-chloride of iron in the vessel.
Another deposit or bye-product in connection with paper mills and
other works is waste lime, variously called spent bleach, soda lime, gas G
lime, tanner's lime, soap lime, according to the nature of the work at
which it is produced.
The second part of this Invention further relates to the recovery and
utilization of such lime which has a great affinity for water.. To deprive
it of its affinity and to render it available as a cement for building, for 1
employment in the purification of gas, for glass making, and for
agricultural and other similar purposes the refuse lime is mixed with
from 10 to 20 parts of coal dust or other slack to 100 (one hundred) parts
of lime, and with a similar amount of soda liquor derived from the boiling
of esparto grass or rags in the manufacture of paper, or other suitable 1
spent alkaline liquor may be used in lieu thereof. The mixture is effected
by any suitable mechanical means and allowed to stand until of such con-
sistency that when pierced with a rod the aperture remains after the rod
is withdrawn. The mixture is then placed in a calcining kiln of suitable
construction, preferably consisting of a cone whose height is about 2
double the base. The cone rests on or is provided with a fire-grate
under which an ash-pit is situated. A fire is first kindled on the grate
and the lime mixture laid thereon and pierced with numerous apertures
over its surface down to the live coal. A powerful draught is thereby
created in the kiln, whilst at the same time the products of combustion 2
are allowed to pass upwards, and these are followed by the flame which
first dries the lime mixture and then consumes the coal dust or slack, the
heat produced by the combustion of which converts the lime from car-
bonate of lime into caustic lime which gradually falls through the grate
bars into the ash pit, and is from thence removed.
The kiln may be provided with a pipe at its upper end through which
the waste heat may be conducted and utilized, or the pipe may bo
connected to a chimney. The kiln may or may not also be formed with
holes around its base for the purpose of stoking.
3
As the combustion proceeds fresh quantities of the lime mixture are 3

page_text: The addition of soda liquor or "ley" to the lime compound, as herein-
before described, may in some cases be dispensed with, and sawdust,
spent bark, or other refuse may be used instead of coal dust.
The waste bleach lime, either before or after being calcined, as herein-
before described, may, in addition to being employed for the various
purposes herein-before set forth, also be used as a substitute for alum in
the manufacture of paper, in the method of sizing known as engine
sizing or sizing in the pulp. For this purpose the lime is mixed in any
suitable vessel with twice or three times its weight of water, so as to
obtain a smooth and uniform cream of lime, which is then strained
through a wire sieve. After standing for one or two hours any clear
water which may rise to the surface is decanted or drawn off, and the
lime deposit is then agitated with commercial, muriatic, or hydrochloric
acid. The agitation is continued until effervesence ceases, and the liquid
shews neutral to test paper. The liquid is then left at rest until it is
perfectly clear, or in lieu of leaving it at rest it may be filtered through
flannel or other suitable cloth. The liquid obtained by this means gives
on an average a strength of 34 degrees of Twaddle's hydrometer, which
is the strength preferred. If, however, the liquid is required to be
transported to a distance it may be boiled down to any desired strength,
or even to a solid or comparatively solid condition, and when required
for use reduced to the necessary strength by the addition of water.
It is to be understood that I have adopted 34 degrees of Twaddle's
hydrometer as a standard strength, not on account of any peculiar action
or virtue pertaining to the liquor at such strength, but because it is
found in practice to be the most concentrated solution which will readily
clear without filtration, and still sufficiently dilute to mix with a rosin
soap, as herein-after more particularly referred to.
The liquor having been prepared, as herein-before set forth, a quantity
thereof is added to each engine of pulp in a similar manner to that in
which a solution of alum has been hitherto added, but in a lesser
quantity. There being great diversity in the strength of rosin size
employed by paper makers under different circumstances, it is difficult
to accurately define a suitable proportion of admixture of the lime liquor
with a given quantity of the solution of rosin soap. I will therefore
take dry rosin as the unit of comparative proportion, and without
reference to the quantity of water or soda with which the rosin is

page_text: admixed to form the solution. Under these circumstances it is found
that the addition of from 8 to 10 ounces, imperial measure, of the lime
liquor at 34 degrees of Twaddle's hydrometer to each imperial pound of
dry rosin is a good proportion of admixture. If the liquor is weaker or
stronger the quantity is increased or diminished according to its strength, 5
and the quantity of lime liquor is also increased when the water with
which the dry rosin is admixed to form the size is hard or contains much
matter in solution, such additional quantity of the lime liquor being
determined by experiment with the different waters used.
When it is desired to produce a hard or crackling paper a proportion 1
of alum is or may be added to the materials contained in the pulp engine
after the rosin, size, and lime liquor have been mixed with the said
materials, such quantity of alum depending on the stiffness of paper
required.
In the manufacture of coloured or inferior qualities of paper the solid
matter deposited during the filtration of the lime liquor, as aforesaid,
may be used in lieu of the said clear liquor, and in the proportions
herein-before given, on in other suitable proportions.
By the employment of lime liquor, or the solid matter deposited
during the filtration of the said liquor in lieu of alum, the cost of 2
making paper is diminished, the said liquor or solid matter being cheaper
than alum, and at the same time a paper more smooth and pliable for
printing purposes is produced than when alum is used, which latter
substance is injurious to the type and other printing machinery. In
addition to these advantages the paper thus made takes on the ink 2
quicker and in a more uniform manner without blotting or blurring, and
without requiring to be damped.
Having now described and particularly ascertained the nature of my
said Invention, and the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, I would observe 3
in conclusion that what I consider to be novel and original, and therefore
claim as the Invention secured to me by the herein-before in part recited
Letters Patent is,―
First. The purification of water, sewage, and other liquids effluent.
from works, manufactories, towns, and other situations generally by 3:
treating the same, first, with an admixture in equal or other suitable
proportions of per-chloride of iron, and per-sulphate or other suitable

page_text: per-salt of iron, with which admixture any suitable sub-salt of iron may
be combined; and second, with a quantity of alkali or alkaline earth,
substantially as herein-before described.
Second. Obtaining per-chloride of iron by digesting from 3 to 5 parts
of hydrated per-oxide of iron, otherwise known as bog ore or ochre, with
1 or 2 parts of muriatic or hydrochloric acid and with or without the aid
of heat, substantially as herein-before described.
Third. Recovering, treating, and utilizing the matters or "sludge,"
whether animal, vegetable, or mineral contained in impure water or
other liquids by treating the said water or liquids with per-salts of iron.
(combined or not with sub-salts) and with alkali or alkaline earth, sub-
stantially as herein-before described.
Fourth. The recovery and utilization of the matters or "sludge'
deposited from impure liquids by natural gravitation by admixing the
said matters with a sufficient quantity of water to enable them to be
agitated with the combined or admixed per-salts of iron, or by blending
the said matters or "sludge " without admixture of water with a per-
oxide of iron, substantially as herein-before described.
Fifth. The recovery and utilization of the waste lime from paper mills
and other works by admixing it with a proportion of coal dust, sawdust,
spent bark, or other suitable refuse, to which a proportion of soda liquor
or "ley" is or may be added, and the arrangement or construction of
kiln wherein the waste lime so admixed is calcined or burned and con-
verted from carbonate of lime into caustic lime, substantially as herein-
before described.
Sixth. Utilizing the waste bleach lime, either before or after being
burned, as a substitute for or in conjunction with alum in the manu-
facture of paper by treating the said lime in the manner herein-before
described.
In witness whereof, I, the said George Mackay, have hereunto set
my hand and seal, this Ninth day of July, One thousand eight