IMPROVEMENTS IN THE MANUFACTURE OF MAGNESIA
Year: 1879

page_text: LETTERS PATENT to Alfred Julius Boult, of the Firm of Wm. P. Thompson
& Co., of 323, High Holborn, in the County of Middlesex, and 6, Lord
Street, Liverpool, in the County of Lancaster, International Patent Agent,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF MAGNESIA."
A communication from abroad by Monsieur Jean Baptiste Marie Prosper
Closson. of Paris, in the Republic of France, Civil Engineer.
Sealed the 16th March 1880, and dated the 20th October 1879.
PROVISIONAL SPECIFICATION left by the said Alfred Julius Boult at the
Office of the Commissioners of Patents on the 20th October 1879.
ALFRED JULIUS BOULT, of the Firm of Wm. P. Thompson & Co., of 323,
High Holborn, in the County of Middlesex, and 6, Lord Street, Liverpool, in the
" IMPROVEMENTS IN THE MANU-
County of Lancaster, International Patent Agent.
FACTURE OF MAGNESIA." A communication from abroad by Monsieur Jean Baptiste
Marie Prosper Closson, of Paris, in the Republic of France, Civil Engineer.
The processes described below relate to the economic manufacture of magnesia
by means of calcined dolomite, and the precipitation by the lime of the calcined
dolomite of the magnesia in magnesian salts dissolved in water, residues of manu-
factures, notably those of chlorine, those where cupreous pyrites are treated in the
wet way.
For instance,
The inventor obtains magnesia economically by employing calcined dolomite in
place of chalk to precipitate the metals of certain salts dissolved in water. The
magnesia obtained proceeds from the decomposition of the dolomite, resulting from
the dissolving of the lime in the water, 1 kilogram 33 per cubic metre, and above
all by the employment of the lime of this dolomite to precipitate the magnesia; and
also from the precipitation of the magnesia in the magnesian salts.
in the fabrication of chlorine by the ordinary process instead of adding chloride of
magnesia in the desired proportion, I treat it with calcined dolomite, or by mag-
nesia, in the proportion required to precipitate the manganese. In the first case I
form chloride of magnesium and chloride of calcium, and, treating then with
calcined dolomite in suitable proportion, I precipitate the magnesia, at the same
time I add to it the magnesia formed by the decomposition of the dolomite. In
fine I produce chloride of calcium as a residue to be thrown away. If it be the
magnesia that I make use of I form chloride of magnesia in precipitating the

page_text: manganese; I then treat this chloride of magnesia by the calcined dolomite. I
precipitate the magnesia, and obtain chloride of calcium as a residue, the magnesia
of the decomposed dolomite adding a further quantity to the magnesia precipitated.
In the two cases one employs the same quantity of dolomite and produces the
same quantity of magnesia. In works where the Weldon process for the regeneration
of the binoxide of manganese is employed I equally replace the lime by calcined
dolomite, in the end so as to produce chloride of magnesia precipitate, the man-
ganese, etcetera. In fine, the series of operations above described. In this case
the magnesia is obtained at the mere costs of labour and magnesia in the raw
material from the richness of the dolomite in carbonate of magnesia, the lime
having always its use in industrial employment. It is not the same in the ordinary
process, and, above all, if in place of chloride of manganese one wishes to utilize, by
the formation of chloride of magnesium, the hydrochloric acid considered as a
residue. In this last case, above all, where one has not by-products it is to the
interest of the manufacturer to employ dolomites very rich, or of impure car-
bonates of magnesia, when one has it hand. One equally obtains magnesia by
simple decomposition of the dolomite by prolonged washing, the magnesia being
nearly insoluble in water, which on the other hand dissolves lime somewhat readily.
One is thus led to operate upon very great masses, but one can much reduce the
mass of water employed by making use of sea water, which contains chloride of
magnesium and sulphate of magnesia. In this case one absorbs the lime not solely
by dissolving, but still more in making it to serve as a précipitant of the magnesia,
and of the magnesian salts dissolved I indicate further on the precautions to take
upon this subject. The proportion of magnesia produced by the decomposition of
the dolomite finds itself thus strongly reinforced. The precipitated magnesia is
added to the total quantity obtained. It is necessary to take the precaution to
previously transform the sulphate of magnesia into chloride of magnesium, without
that one precipitates sulphate of lime with the magnesia. For that, in a first
operation, one treats the water with chloride of calcium, and precipitates by that
means sulphate of lime; and the resulting water (not containing any other salts of
magnesium than the chloride) is treated with calcined dolomite in the form of
powder. This chloride of calcium need not enter into an estimate of cost, as, after
the first operation, it is obtained as a waste product. One ought solely to dilute
each time the fresh supply of water with a quantity of the residual water from the
last operation in such quantity that it shall contain the requisite amount of chloride
of calcium; moreover, the solubility of the sulphate of lime in the resulting water
taking place in very large proportion in presence of divers alkaline salts, and
notably chloride of sodium, one can also omit the preliminary operation above
mentioned for ordinary sea water; but this cannot be safely done in the case of the
sea water of salines treated in this fashion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Julius Boult in the Great Seal Patent Office on the 19th
April 1880.
"
ALFRED JULIUS BOULT, of the Firm of Wm. P. Thompson and Co., of 323, High
Holborn, in the County of Middlesex, and 6, Lord Street, Liverpool, in the
County of Lancaster, International Patent Agent. IMPROVEMENTS IN THE MANU-
FACTURE OF MAGNESIA." A communication from abroad by Monsieur Jean Baptiste
Marie Prosper Closson, of Paris, in the Republic of France, Civil Engineer.
The processes described in the following Specification are relative to the economic
manufacture of magnesia, and the utilization of manufacturers' residues, whether
waste products, such as chloride of lime, and, in certain cases, chloride of manganese,
the waste acids of sulphate of soda and of chlorine manufacture, or the residues
already undergoing a transformation, and which are employed in my process, as it
were, in transit without injury to their final transformation, such for instance as
the chloride of manganese in the fabrication of chlorine, where the manganese is
regenerated, or the chlorhydrate of ammonia in soda manufacture.
They consist essentially in the employment of calcined dolomite in place of lime
to precipitate the metals from their various chlorides in order to form chloride of
magnesium mixed with chloride of calcium. This latter is a new industrial appli-
cation to obtain economically the chloride of magnesium from which to precipitate
in turn the magnesia, treating it with a new quantity of calcined dolomite. The
magnesia of this new dolomite is added to the final product.
The treatment is carried on in appropriate basins or reservoirs, where one pro-
ceeds by energetic and repeated mixing to bring the matters into intimate contact.
It is desirable where it can be done to arrange a central reservoir where a
mechanical mixer operates, and from thence the matters are sent to the depositing
basins. When lime is utilized in the industry where one employs a residue (as is
the case in chlorine works where the Weldon process is established for the making
of soda from common salt and the ammoniacal carbonates) the richness of the
dolomite in magnesia has within certain limits only an accessory importance. When
on the contrary one makes use of chloride of manganese one is interested in
employing rich dolomites, and still more so when one utilizes the acid waters which
do not give place to any bye product, whilst the oxide of manganese precipitated
has yet a certain value.
If the dolomite is argillaceous one can separate the clay at the end of the first
part of the operation, but for the precipitation it is necessary to procure the pure
dolomite. It can be found widely distributed, especially in land producing phos-
phoric iron ores, and which are most favourable for establishments for the manu-
facture under discussion; it is not then generally difficult to get it. In extreme
cases one can employ pure lime instead of pure dolomite for the second part of the
operation. This is an extremity that ought to be as much as possible avoided, as
one thus diminishes by one half the quantity of magnesia obtained with the same
amount of chloride. In this case I still operate in the following manner:-
:-The
double chloride of calcium and magnesium once obtained and separated from the
clay, I bring the residue to a solid state either by concentration, by supersaturation,
or by the two means united according to circumstances. (It is evident that this
process is only applicable when one can operate upon the liquor already sufficiently
concentrated, as is the case in soda making.)
By an appropriate heating I then effect the decomposition of the chlorhydrate of
magnesia into hydrochloric acid and magnesia. Again treated with water the
chloride of calcium is dissolved and the magnesia deposited.
One can even in this case, if one desires to have the chloride of calcium solid,
easily obtain this result by supersaturation by employing hot solutions.
The decomposition of chlorbydrate of magnesia is obtained very easily and very
completely in this state; it is done so yet more easily if to the double chloride

page_text: reduced to a powder one adds a little of the chloride already treated, that is to say,
containing the magnesia also in powder. The hard and solid pellets thus obtained
give rise to a very rapid decomposition into hydrochloric acid and magnesia. This
is a new industrial result, for the decomposition of chloride of magnesia is always
incomplete and difficult. One obtains the same result by adding to the double
chloride a little magnesia obtained from a previous operation (magnésia which is
regained after each operation).
When one operates with pure products one can equally make use of magnesia in
place of dolomite for the first operation. The chloride of magnesium obtained ought
then to be treated with dolomite to precipitate the magnesia. This magnesia
serving at the first operation as the carrier, one can consider it as a constant, always
the same.
When one employs hydrochloric acid, or the chloride of iron, one can make use
of the crude dolomite for what is here always called the first operation.
I apply equally the same process of precipitation by calcined dolomite to the
mother liquors of salines and to sea-water. These waters, besides the alkaline salts
which do not concern me, contain chloride of magnesium and sulphate of magnesia.
I treat them at first with chloride of calcium to transform the sulphate of magnesia
into chloride. This chloride of calcium does not enter into the question of expense;
one operation furnishes it for the next. One has only then to treat with calcined
dolomite in the form of powder.
The reactions are very simple with sea-water; the inconvenience of its employ-
ment arises solely from the fact that it is necessary to operate upon great masses.
In this case the preliminary treatment by chloride of calcium is not necessary when
one does not want a perfect purity, the solubility of sulphate of lime being greatly
increased in presence of alkaline salts. One ought also in this case to take account of
the quantity of lime dissolved by the water and which is liberated by the magnesia.
Having now described the different modes of operating my Invention, I claim
particularly,
First. The means herein set forth (new industrial result) of procuring in each
case economically chloride of magnesium, mixed it is true with chloride of calcium
(but that matters little to the succeeding operations), by the employment of dolomite
and of divers chlorides above mentioned.
Second. The substitution of dolomite for lime in the treatment of certain
chlorides for the purpose of forming chloride of magnesium, (regeneration of ammonia
in soda works, et cetera).
Third. The precipitation by the calcined dolomite of the magnesia of the
chloride of magnesium so as to add to the product obtained the magnesia resulting
from the decomposition of the dolomite.
Fourth. The substitution of magnesia for lime in certain cases, for example, in
the process of the regeneration of ammonia and of manganese, the chloride of
magnesia formed being then treated with the calcined dolomite. This part of the
process is susceptible of special applications, conditionally on one having pure
dolomite.
Fifth. The application of the same processes of precipitation by dolomite to sea-
water and to the mother liquors of salines with the precautions indicated.
Sixth. In fine, the new utilization of manufacturers' residues, and the economical
production of the magnesia, substantially as herein described.
In witness whereof, I, the said Alfred Julius Boult, have hereunto set my
hand and seal, this Seventeenth day of April, in the year of our Lord
One thousand eight hundred and eighty.
ומחזי
TITT TTIN POUL