IMPROVE- MENTS IN THE MANUFACTURE OF CAUSTIC SODA AND POTASH, CARBONATES AND BI-CARBONATES OF SODA AND POTASH, PHOSPHATES OF SODA AND POTASH, MURIATIC ACID AND CHLORINE."
Year: 1871

page_text: LETTERS PATENT to John James Knight, of Penketh, near War-
rington, in the County of Lancaster, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF CAUSTIC SODA AND POTASH, CARBONATES AND
BI-CARBONATES OF SODA AND POTASH, PHOSPHATES OF SODA AND POTASH,
MURIATIC ACID AND CHLORINE."
PROVISIONAL SPECIFICATION left by the said John James Knight
at the Office of the Commissioners of Patents, with his Petition,
on the 2nd December 1871.
I, JOHN JAMES KNIGHT, of Penketh, near Warrington, in the
County of Lancaster, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC SODA AND POTASH, CAR-
BONATES AND BI-CARBONATES OF SODA AND POTASH, PHOSPHATES OF SODA AND
POTASH, MURIATIC ACID AND CHLORINE," to be as follows:-
My Invention consists principally in the use for such manufactures of
phosphates of lime (such as bone ash or any of the mineral phosphates)
in the manner herein-after described.

page_text: Firstly. I treat bone ash (or other phosphate of lime) with sulphuric
acid (SO,H) in the proportion of one equivalent of acid to one of phos-
phate of lime (3 CaO, PO,) in order to convert the whole or the greater
part of the phosphate into monophosphate of lime, which is perfectly
soluble in water. The mass is then lixiviated with hot or cold water and
the sulphate of lime allowed to settle to the bottom of the vessel. This
sulphate of lime forms a valuable manure. The clear solution of soluble
phosphate is then run off into evaporating pans and an equal quantity of
bone ash (or other phosphate of lime) previously ground to a fine powder
is added, and this mixture is boiled down or evaporated to dryness at a
temperature not exceeding 350° Fahrenheit. The mass now consists
principally of a compound of the formula 2 CaO, HO, PO,, or a bibasic
phosphate of lime. A mixture is now made of this compound with
common salt (if salts of soda are required) or with muriate of potash (if
salts of potash are required), and exposed to a bright red heat (either
with or without the admission of steam) in a furnace commonly known
as a blind furnace," and it is to be frequently stirred with an iron
rake for about three hours.
"
The chemical change which takes place is represented by the following
formula: 2CaO, HO,PO,+NaCl=2CaO, NaO, PO„,+HCl, that is to
say, muriatic acid gas is given off, which is condensed in the usual way.
The residue consists of a nearly insoluble double phosphate of lime and
soda or potash, which is then ground to powder and boiled (preferably
by means of steam in a wooden tank) with a solution of the soluble or
monophosphate of lime above named. By this treatment the soda or
potash is extracted in the form of phosphate of soda or potash (soluble
in water), leaving the phosphate of lime as an insoluble powder, which
may be used over again without treatment by sulphuric acid.
The solution of phosphate of soda or potash is then evaporated, and
crystals of common phosphate of soda or potash may thus be obtained,
or if caustic or carbonated alkalies be required the solution is treated
and boiled with caustic lime, which precipitates all the phosphoric acid
as triphosphate of lime, leaving caustic soda or potash in solution,
which is to be evaporated down in order to obtain solid caustic, or
charged with carbonic acid to convert it into carbonate. The resulting
triphosphate of lime is converted by treatment with sulphuric acid into
the soluble or monophosphate of lime and used over again as before.

page_text: Secondly. Instead of drying the mixture of the soluble or mono-
phosphate or triphosphate of lime at a temperature not exceeding 350°
Fahrenheit it is dried at a temperature of 500° or more, by which all the
water is driven off, leaving a residue composed of the formula 2 CaO, PO̟,
which may be termed "pyrophosphate of lime." A mixture of this pro-
duct and dry common salt (muriate of soda) or salts of potash is exposed
to a bright red heat in a "blind furnace," and a supply of oxygen or air
(previously superheated by pipes or other suitable arrangement) is then
admitted for some hours. Chlorine gas along with volatilised salt,
which is condensed in an intermediate chamber, is then evolved, and
after being cooled in passing through pipes is admitted into chambers
for the manufacture of bleaching powder or for other manufacturing
purposes wherein chlorine gas is employed. The residue of double
phosphate of lime and soda or potash (2 CaO, NaO, PO,, or 2 CaO, KO,
PO) is then to be treated in the manner previously described in the
first part of this Specification to extract the soda or potash therefrom,
and the residue of bibasic phosphate of lime is to be used over again
according to the second part of this Specification.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John James Knight in the Great Seal Patent
Office on the 1st June 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
JAMES KNIGHT, of Penketh, near Warrington, in the County of
Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of December, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John James Knight,
Her special license that I, the said John James Knight, my
executors, administrators, and assigns, or such others as I, the said
John James Knight, my executors, administrators, and assigns,

page_text: 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 THE MANUFACTURE OF CAUSTIC
SODA AND POTASH, CARBONATES AND BI-CARBONATES OF SODA AND POTASH, PHOS-
PHATES OF SODA AND POTASH, MURIATIC ACID AND CHLORINE," upon the condition
(amongst others) that I, the said John James Knight, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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 John James Knight, do hereby
declare the nature of the 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):-
The object of my said Invention is to diminish the heavy expense to
which the chemical manufacturer is put, firstly, in the cost of the
plant necessary for the manufactures of caustic soda and potash, their
carbonates, bi-carbonates, and phosphates, muriatic acid, and chlorine;
and, secondly, in the cost of manufacturing the said chemicals by the
use of ever recurring materials, which may be used over and over
again; and lastly, in the great cost he incurs for depositing the tank
waste or refuse which is produced in the present mode of working, but
which in one part of my Invention is replaced by sulphate of lime or
gypsum. (This is a valuable manure for land, has not any smell, the
weight produced will not be more than two-thirds that of the ordinary
tank waste, and it can be sold to a pròfit without any difficulty.)
My Invention consists principally in the use for such manufactures of
phosphates of lime (such as bone ash or any of the mineral phosphates)
in the manner herein-after described.
f lineal with.

page_text: phate of lime (3 CaO, PO,) in order to convert the whole or the greater
part of the phosphate into a monophosphate of lime, which is perfectly
soluble in water. The mass is then lixiviated with hot or cold water and
the sulphate of lime allowed to settle to the bottom of the vessel. This
sulphate of lime forms a valuable manure. The clear solution of soluble
phosphate is then run off into evaporating pans, and an equal quantity of
bone ash (or other phosphate of lime) previously ground to a fine powder
is added, and this mixture is boiled down or evaporated to dryness at a
temperature not exceeding 350° Fahrenheit. The mass now consists
principally of a compound of the formula 2 CaO, HO, PO,, or a bibasic
phosphate of lime. A mixture is now made of this compound with
common salt (if salts of soda are required) or with muriate of potash (if
salts of potash are required) and exposed to a bright red heat (either
with or without the admission of steam) in a furnace commonly known
as a "blind furnace," and it is to be frequently stirred with an iron rake
for about three hours.
=
The chemical change which takes place when steam is used is repre-
sented by the following formula:-2 CaO, HO, PO, + NaCl
2 CaO,
NaO, PO,+HCI, that is to say, muriatic acid gas is given off, which is
condensed in the usual way. The residue consists of a nearly insoluble
double phosphate of lime and soda or potash, which is then ground to
powder and boiled (preferably by means of steam in a wooden tank) with
a solution of the soluble or monophosphate of lime above named, in the
proportion of four equivalents of the double phosphate to one of the
monophosphate. By this treatment the soda or potash is extracted in
the form of phosphate of soda or potash (soluble in water), leaving the
phosphate of lime as an insoluble powder, which may be used over again
by treatment with sulphuric acid, as firstly above described.
The solution of phosphate of soda or potash is then evaporated, and
crystals of common phosphate of soda or potash may thus be obtained;
or if caustic or carbonated alkalies be required the solution is treated and
boiled with caustic lime, which precipitates all the phosphoric acid, as
triphosphate of lime, leaving caustic soda or potash in solution, which is
to be evaporated down in order to obtain solid caustic, or charged with
carbonic acid to convert it into.carbonate or bi-carbonate. The resulting
triphosphate of lime is converted by treatment with sulphuric acid into
the soluble or monophosphate of lime, and used over again as before.

page_text: Secondly. Instead of drying the mixture of the soluble, or monophos-
phate, or triphosphate of lime at a temperature not exceeding 350°
Fahrenheit, it is dried at a temperature of 500° or more, by which all the
water is driven off, leaving a residue composed of the formula 2 CaO, POб,
which may be termed pyrophosphate of lime. A mixture of this product
and dry common salt (muriate of soda), or salts of potash, in equivalent
quantities, is exposed to a bright red heat in a "blind furnace," and a
supply of oxygen or air (previously superheated by pipes or other
suitable arrangement of mechanism) is then admitted for some hours.
Chlorine gas (along with volatilized salt which is condensed in an
intermediate chamber) is then evolved, and after being cooled in passing
"through pipes is admitted into chambers for the manufacture of bleaching
powder, or for other manufacturing purposes wherein chlorine gas is
employed. The residue of double phosphate of lime and soda or potash.
(2 CaO, NaO, PO,, or 2 CaO, KO, PO,) is then to be treated in the
manner previously described in the first part of this Specification, to
extract the soda or potash therefrom, and the residue of triphosphate of
lime is to be used over again, as previously described.
5
Another way is to take one equivalent of triphosphate of lime and
treat it with one equivalent of sulphuric acid; a dry or pasty mass is
thus formed which is then heated with one equivalent of muriatic acid,
to dissolve out the bibasic phosphate of lime. The solution is then run
off, leaving a residue of gypsum or sulphate of lime, which must be
washed with hot or cold water. These washings can be used over again
to wash more gypsum, and will in time become as strong as the original
liquor, and thus no waste of the bibasic phosphate will take place. I
then take one equivalent of the solution of bibasic phosphate thus
formed and mix it with one equivalent of chloride of sodium (common
salt) or patassium and boil them together till they become a pasty mass,
after which this mass is pushed forward on to the bed of a
" blind
furnace" and heated to a bright red heat, when steam is admitted which
sets free the muriatic acid and produces a double compound of phosphate
of lime and soda or potash, which (as well as the muriatic acid evolved)
is to be treated as before described.

page_text: boiled down to dryness and heated to 500 degrees Fahrenheit, or more,
which throws off the muriatic acid leaving pyrophosphate of lime, which
may then be ground to a powder with one equivalent of pyrophosphate
to one equivalent of chloride of sodium, and this mixture put into the
bed of a "blind furnace" and heated to a bright red heat which will
produce the before-named double phosphate of lime and soda or potaşlı,
at the same time liberating chlorine gas, which may be treated as before

page_text: compound of phosphate of magnesia and soda or potash (2 MgO, NaO,
PO,). This double compound must be ground to a powder, mixed with
bibasic phosphate of magnesia in the proportion of two equivalents of the
former to one of the latter, and boiled by steam or otherwise until the
whole or greater part of the soda or potash is in solution, thus converting
it into common phosphate of magnesia (3 MgO, PO,). I then boil the
whole with caustic magnesia, in order to precipitate the whole of the
phosphoric acid from the phosphate of soda as tribasic phosphate of
magnesia. The remainder being a solution of caustic soda or potash I
treat one equivalent of bibasic phosphate of magnesia thus obtained
with one equivalent of muriatic acid, which is well mixed together with
the addition of a small quantity of water, and gently heated at a tem-
perature not exceeding 300°. It is then allowed to be at rest until quite
cold, and on treating a small portion with water, and filtering, little or
no phosphoric acid is found in the solution. When this operation is
complete the whole mass is lixiviated with cold water, in the manner
usually practised in alkali works, until there is little or no chloride of
magnesium in the wash liquors, leaving a bibasic phosphate of magnesia
(2 MgO, HO, PO,). The wash liquors are evaporated to dryness,
and the residue placed in a blind furnace and roasted until the whole or
greater part of the chlorine is given off in the state of muriatic acid gas
and chlorine gas, and caustic magnesia remains, which may be used over
again to precipitate the phosphoric acid, as above described.
I mix the bibasic phosphate of magnesia produced as above (which
contains also a little of the tribasic phosphate) with chloride of sodium
or chloride of potassium in the proportion of one equivalent of bibasic
phosphate of magnesia to one equivalent of the chloride, and roast it in
a blind furnace for several hours until the whole or greater part of the
chloride of sodium or potash is decomposed, with the admission of steam
or air as in the previously described process, producing muriatic acid gas
only or a mixture of muriatic acid gas and chlorine gas; the residue
consisting of the double compound of phosphate of magnesia and soda
or potash. If the bibasic phosphate is dried at a temperature of 500°
or more it produces a pyrophosphate of magnesia, which if ground and
mixed with chloride of sodium or potassium in the same proportions as
just previously described and roasted with the admission of air will
evolve chlorine gas only, leaving the same double compound as a residue.

page_text: The residue I then treat in the following manner :-I boil it with bibasic
phosphate of magnesia in the proportion of two equivalents of the double
compound contained in the residue to one equivalent of the bibasic
phosphate until the whole or greater part of the soda is dissolved, and
the resulting product can be treated with caustic magnesia as above
described; or the solution may be separated from the precipitate (tribasic
phosphate of magnesia) and when cold well agitated with caustic
magnesia in the proportion of one equivalent of phosphate of soda
contained in the solution to two equivalents of magnesia, thus producing
caustic soda or potash in solution, and precipitating the whole of the
phosphoric acid as bibasic phosphate of magnesia, which is used over
again either for boiling with the double compound, as above described,
or for decomposing more chloride of sodium or potassium. The
precipitate (tribasic phosphate of magnesia) which is left after the
separation of the phosphate of soda or potash solution is again
treated with muriatic acid as before, and thus the process goes on
.

page_text: I claim as my Invention, the manufacture of caustic soda and potash,
carbonates and bicarbonates of soda and potash, phosphates of soda and
potash, muriatic acid and chlorine by any of the processes above detailed
or by a combination of any two or more of such processes.
In witness whereof, I, the said John James Knight, have hereunto
set my hand and seal, this Thirtieth day of May, in the year of
our Lord One thousand eight hundred and seventy-two.
Witnessed by
GEORGE DAVIES, C.E.,
Patent Office,
Manchester.
JNO. JAS. KNIGHT. (L.S.)