Improvements in and connected with the Manufacture of Magnesium Hydrate.
Year: 1893

page_text: Date of Application, 21st Dec., 1893
Complete Specification Left, 21st Sept., 1894-Accepted, 15th Dec., 1894
PROVISIONAL SPECIFICATION.
Improvements in and connected with the Manufacture of Magnesium
Hydrate.
1 MICHEL NICHOLAS D'ANDRIA of 6 Frogmore Terrace Chester Road
Stretford in the County of Lancaster Manufacturing Chemist do hereby declare
the nature of this invention to be as follows:-
. My invention is based on the fact that lime is soluble in water, whilst magnesia
is practically insoluble in it, and also on the fact that lime will precipitate magnesia
from a neutral or alkaline solution the acid contained in the magnesium salt of such
solution combining with lime to form a soluble lime salt.
My object is to treat burnt or calcined dolomite which contains something like
40 per cent. of magnesia or thereabouts and something like 58 to 60 per cent. or
thereabouts of lime and separate the latter from the former chiefly first by means
of water which will dissolve the lime and leave the magnesia practically undissolved.
In as much however as an enormous quantity of water would be required for this
purpose, and since also I have ascertained that lime is more soluble in water
containing salt, than in ordinary water I propose to effect this washing at the sea-
shore or in brackish or in tidal waters in such a manner as to avail myself of the
tides and thus not only have a vast quantity of water at my disposal, but also save
a great deal of pumping and manual labour.
To effect this object, I place large tanks (preferably of iron) of a convenient
height for stirring and fitted with outlets near the bottom, at the sea-shore or in
communication with tidal waters in such a manner as to allow them to be filled by
the incoming tides.
. I first place in these tanks a convenient quantity of burnt or calcined dolomite
and after they have been filled by the tidal waters, and the tide has receded, I stir
the dolomite so as to mix it with the water in the tanks, I then allow the sediment
to settle which it does in a few minutes, open the outlets at the bottom, so as to
run off the supernatant water, close the outlets and wait the next incoming tide. I
repeat this operation until the whole or the bulk of the lime has been washed away,
the sediment at the end of these operations consisting mainly of magnesium
hydrate.
Should there however still remain in it some lime which I wish to remove, I
may treat this sediment with a little hydrochloric acid (preferably diluted with
water) or with some other acid which would form a soluble lime salt, and heat and
stir the whole. By this means any lime present enters into solution and can be
removed by decantation or filtration, and by allowing, if I so choose, a little
magnesia also to be in solution I make sure that practically the last traces of lime
have been removed. The sediment which now consists mainly of magnesia can be
washed, dried and placed on the market.
Dated this 19th day of December 1893.

page_text: COMPLETE SPECIFICATION.
Improvements in and connected with the Manufacture of Magnesium.
Hydrate.
I, MICHEL NICHOLAS D'ANDRIA of 6 Frogmore Terrace Chester Road
Stretford in the County of Lancaster, Manufacturing Chemist, do hereby declare
the nature of this invention, and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
My present invention, which relates to the manufacture or production of
magnesium hydrate, is based upon the facts that lime is soluble in water whilst
magnesia is practically insoluble, and that lime will precipitate magnesia from a
neutral or alkaline solution.
My object is to reduce the cost of the magnesia and for this purpose I employ
as the source or as one of the sources of magnesia, dolomite and preferably such
dolomite as is richest in magnesia and which is found generally to contain about
40 per cent. of magnesia and 60 per cent. of lime. The separation of the magnesia
is effected by copious treatment with water which will dissolve out the lime and
leave the magnesia practically undissolved. But, since relatively enormous
quantities of water would thus be required and since this water would often require
to be pumped, I employ the natural flow of water and prefer to proceed in the
following manner, which enables me to take advantage of the tides and provides
also an additional source of magnesia.
At any suitable point at or near the sea shore or in a tidal estuary, I construct
or arrange large tanks or a large tank into which the tide can flow if permitted
and from which the water can escape upon the ebb of the tide through suitable
outlets.
The dolomite is first calcined' and is then slaked, preferably with fresh water,
Land is placed in the tank or tanks. The water is then permitted to flow into the
tank and after the turn of the tide, the dolomite is well stirred up and allowed to
subside. The supernatant water is then allowed to flow off through the outlets,
carrying with it some of the lime in solution. This is repeated until all or nearly
all the hydrate of lime is dissolved out, when the sediment will consist mainly of
magnesium hydrate. The dolomite may obviously be supplied to the tanks as a
“milk" produced by slakeing the calcined dolomite with an excess of water,
through suitable conduits, in a continuous stream, intermittently, or in measured
quantities.
.
In either case, owing to the before mentioned fact that the magnesium base
contained in the sea or other water is precipitated by the dolomitic line, I obtain
this magnesia as an addition to the magnesia from the dolomite.
Where tidal water is not available, and sufficient supplies can be had under
sufficient head to avoid the necessity for pumping, I may make use of fresh water
in substantially the same manner as described for tidal water.
If it be desired to finally remove any lime which may still be found in the
sediment at the close of the operation, there may be added a sufficiency of diluted
bydrochloric acid to combine with the lime. The sediment is then heated and
agitated to produce the complete conversion of the lime into a soluble chloride
which may be removed by decantation or filtration. If at the same time some of
the magnesia is brought into solution or a solution of a magnesium salt be added,
the reaction is made more certain.
If, owing to the presence of bicarbonate of lime or of carbonic dioxide in the
water, carbonate of lime should be found in the sediment, this may be prevented
by submitting the water to a preliminary treatment with milk of lime in a separate
tank.

page_text: The ultimate residue consisting wholly or mainly of magnesium hydrate may be
washed and dried and packed or used in the usual manner.
When the process is carried out with water containing magnesium salts in
solution, such as sea water, the hydrate of magnesium from the water becomes.
mixed with and carried down by the heavier dolomitic magnesia and it is this fact
which renders my process of great value and especially applicable for use with
waters containing magnesium salts.
I desire it to be understood that I do not limit myself to the precise herein-
before described means and processes for the production of magnesium hydrate, as
it is obvious that they may be varied to suit local conditions and circumstances.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I'
claim is :-
1. The herein before described process for and method of manufacture or pro-
duction of magnesium hydrate and which consists in treating slaked calcined
dolomite with the natural flow of a large quantity of water substantially as and by
the means set forth.
2. The method of or process for obtaining magnesium hydrate from sea water by
means of calcined dolomite, substantially as and by the means hereinbefore
described.
Dated this 20th day of September AD 1804
WILLIAM E. HEYS,
Agent for the Applicant.