Improvements in and relating to the Preparation of Sand and like Substances to be used in Making Moulds and Cores for Casting.
Year: 1898

page_text: .Date of Application, 25th May, 1898
Complete Specification Left, 25th Feb., 1899-Accepted, 25th May, 1899
Improvements in and relating to the Preparation of Sand and like
Substances to be used in Making Moulds and Cores for Casting.
We, JOHN HARGREAVES, of Widnes, in the County of Lancaster, Chemist, and
ANDREW l'OULSON, of 63, Frederick Street, Widnes, in the County of Lancaster,
Foreman Moulder, do hereby declare the nature of this invention to be as
follows:-
This invention relates mainly to sand or like substances which have been used
for making moulds or cores for casting metals, but is also applicable to some
extent to fresh sand or other like substances used for making moulds or cores.
Our invention has for its objects, to economically impart cohesiveness to sand or
like substances more particularly to sand or like substances which have been
used or burnt, known as spent sand so as to render the spent sand suitable for
re-use in making moulds or cores for casting; to obtain or prepare the treated
sand in such a condition that the mould or core shall be more easily rendered
porous, so as to readily allow escape of gases evolved, and that a smooth or
finished surface shall be formed on the metal castings; and to provide means for
producing economically some of the materials employed in preparing the sand.
For these purposes, we, to impart cohesiveness to sand or like substances, incor-
porate therewith in a suitable manner, such as by means of edge runners, a dis-
integrator, or by grinding, a mixture of water and a hydrate of silica or alumina
in a gelatinous condition in which may be contained a salt of sodium. Or, for
use in making dry sand or loam moulds or cores, a solution of bicarbonate of soda,
or other like suitable salt, may be mixed with the sand or like substance.
To economically obtain a mixture of water and a hydrate of silica in a suit-
able gelatinous condition for incorporation with sand and like substances, we
prefer to employ and treat, suitable aqueous solutions of a silicate of soda by one
of the following or equivalent methods.
T
We intimately mix together, in a suitable vessel a solution of a silicate pre-
ferably supersilicate of soda with a solution of sesqui or, and preferably, bicarbonate
of soda; said solutions being preferably mixed together in the cold, being of
suitable density and in proportions of about the proper chemical equivalents to
decompose said silicate of soda so as to form a jelly or like mass of water and
hydrate of silica containing the soda liberated from the silicate of soda and also
the said added soda; in form of mono or it may be sesqui carbonate of soda.
The reactions between the said silicate of soda and sesqui or bicarbonate of soda
may be hastened, if desired, by injection of steam into, or by otherwise heating
the said mixed solutions; or by adding said solution of sesqui or bicarbonate of
soda to a hot solution of silicate of soda.
Instead of employing a sesqui or bicarbonate of soda to supply the carbonic acid
necessary to react upon the silicate of soda to form a jelly or like mass of water
and hydrate of silica and to obtain as a carbonate of soda, the soda resulting from

page_text: the decomposition of the silicate of soda, we by any convenient means, inject into
and amongst the said solution of silicate of soda, carbonic acid gas as in the cooled
products of combustion of coke. Or carbonic acid gas from other suitable source
may be employed. We preferably stop injection of carbonic acid gas into the
said solution of silicate of soda, when said solution becomes viscid and before a
semi-solid jelly like mass is formed.
It is not advantageous to have a relatively large amount of mono carbonate of
soda present in the gelatinous mass of water and hydrate of silica and therefore
when in excess, part of said mono carbonate of soda may be removed and recovered
by washing the said mass with water before incorporating with the sand or like
substances.
When bicarbonate of soda is employed for mixing with the sand or like sub-
stances, we prefer to moisten the sand or like substances with a strong and pre-
ferably concentrated solution of bicarbonate of soda; or said solution may be
formed by mixing bicarbonate of soda with moist sand.
Instead of using silicate of soda a solution of aluminate of soda may be treated
by the methods herein before described, to obtain a gelatinous mass of water and
hydrate of alumina which may be used in place of a gelatinous mass of water and
hydrate of silica.
To ensure that castings will have a smooth or finished surface and to facilitate
efficient re-use of the sand or like substances, we incorporate with the sand or like
substances, either fresh or spent, in any convenient way suitable and preferably
fusible carbonaceous material which admit of being finely ground and intimately
mixed with the sand or like substances and which, when heated will permeate
the sand or like substances and readily evolve reducing gases during the pouring
or casting of the metals and which after use shall leave only a relatively small
amount of cinder or residue deleterious to the re-use of sand or like substances.
We for this purpose preferably employ suitable bituminous materials of low cost,
such as coal tar pitch, asphalt, or the like.
The bituminous materials employed, may have a small quantity of sand or
like material mixed with it or them to facilitate grinding of the said bituminous
material, such as pitch, to a fine powder in which condition such powder may
be mixed in suitable proportions either direct with the moulding sand or like
material or with the mixture of water and hydrate of silica or alumina when in
the viscid condition before mentioned.
Dated this Twenty third day of Nov 1808
JOHN HARGREAVES.
ANDREW POULSON.
Improvements in and relating to the Preparation of Sand and like
Substances to be used in Making Moulds and Cores for Casting.
We, JOHN HARGREAVES, of Widnes, in the County of Lancaster, Chemist, and
ANDREW POULSON, of 63, Frederick Street, Widnes, in the County of Lancaster,
Foreman Moulder, 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:―
This invention relates mainly to the treatment of sand or like substances which
have been used for making moulds or cores for casting metals, so as to enable such
sand to be re-used for making moulds or cores, but is also applicable to some

page_text: extent in treating fresh sand or other like substances used in making moulds or
cores such as the relatively pure silica used in making moulds and cores for cast-
ing steel which silica lacks to a large extent the necessary cohesive properties
to enable moulds or cores to be formed.
Our invention has for its objects to economically impart cohesiveness to sand or
like substances, more particularly to sand or like substances which have been used
or burnt, and thereby having lost to a large extent their cohesive properties are
known as spent sand, so as to render such spent sand suitable for re-use in making
moulds or cores for casting; to obtain or prepare the treated sand in such a con-
dition that the mould or core shall be easily rendered sufficiently porous so as to
readily allow escape of gases evolved, and that a smooth or finished surface shall
be formed on the metal castings; and also to provide means for producing
economically some of the materials employed in preparing the sand for use.
For these purposes, we, to impart cohesiveness to sand or like substances and to
enable the moulds to be rendered porous, incorporate with such sand in any suit-
able manner, such as by means of edge runners, a disintegrator, or by grinding,
a mixture of water and a hydrate of silica in a gelatinous condition, in which
may be contained a salt of sodium. We find that an efficient method of incorporat-
ing the said gelatinous mixture of water and hydrate of silica with sand is by the
use of edge runners and a revolving pan, scrapers being provided for mixing the
materials and also suitable arrangements for lifting the runners above the materials
in the pan. Dry sand and bituminous materials as hereinafter mentioned are
first mixed together by means of stationary scrapers projecting into the revolving
pan, then the runners are lowered and sufficient of the said gelatinous mixture is
added which is by the action of the runners squeezed into the interstices of the
mass of sand. The said gelatinous mixture may be added to the sand
in varying proportions according to the dryness of the sand to be
treated; about one and a half hundredweight being required to treat one ton of
thoroughly dry, hard, burnt sand. When a mould is formed the drying of the
gelatinous mixture increases the porosity of the mould so as to readily allow
escape of gases.
In making dry sand or loam moulds or cores, instead of the said gelatinous
mixture, a solution of bicarbonate of soda may be mixed with the sand or like
substance, together with which we may and preferably do incorporate bituminous
materials as hereinafter described.
To economically obtain a mixture of water and a hydrate of silica in a suitable
gelatinous condition for incorporation with sand and like substances we prefer to
employ and treat, suitable aqueous solutions of a silicate of soda, hereinafter more
particularly described, by one of the following or equivalent methods.
"
We intimately mix together in any suitable vessel, a solution of silicate of soda
with a solution of sesqui, or, and preferably, bicarbonate of soda. For the reasons
hereinafter described we find it to be more advantageous, as far as may be
practicable, to employ a solution of silicate of soda which does not contain more
alkali than is necessary to render the silica soluble, and whilst the ordinary silicate
of soda of commerce may be used we prefer to use silicate of soda containing a
relatively smaller proportion of alkali, such as the silicate of soda known as
neutral
or supersilicate." We prefer to use bircarbonate of soda because a
maller quantity of bicarbonate of soda is necessary than of sesqui carbonate of
oda, of which latter about two equivalents of soda are required to supply the
amount of carbonic acid necessary to decompose the silicate of soda so as to form
carbonate of soda and hydrate of silica: and also because with bicarbonate the
elatinous mixture produced contains a smaller relative proportion of carbonate of
oda than is contained when sesquicarbonate of soda is employed. The said
solutions are preferably mixed together in the cold which facilitates an intimate
isture being obtained before the mass becomes viscid, the solutions being of
uitable density and in proportions, such as hereinafter more particularly described,
f about their proper chemical equivalents to decompose the said silicate of soda,

page_text: so as to form a jelly or like mass of water and hydrate of silica, containing the
soda liberated from the silicate of soda, and also the said added soda, in form of
mono, or, if, which is undesirable, excess of bicarbonate be added, it may be sesqui-
carbonate of soda. To more clearly describe the method of putting this part of our
invention into practice, we instance the following, which gives good results, as
typical means of obtaining a mixture of water and hydrate of silica in a suitable
jelly or like mass of medium strength and containing a carbonate of soda, which
jelly like mass will impart a moderate degree of cohesiveness to sand when mixed
with such sand. Twenty five pounds of bicarbonate of soda are dissolved in one
hundred gallons of water to which is subsequently added and intimately mixed
therewith seven gallons of a solution of silicate of soda of a density of about 75
degrees Twaddle, containing as silicate about nine per cent. of Na₂O.
A stronger jelly or like mass to impart greater cohesiveness to sand may be
obtained by employing a smaller proportion of water in the preparation of the
said jelly or like mass, or, and as we find to be more advantageous, the jelly of
medium strength may be converted into a stronger jelly by allowing part of the
water of gelatinization to drain from the said jelly or like mass of medium strength.
The draining is accomplished by placing the said jelly or like mass upon a porous
brick floor, or in any other suitable manner.
The bicarbonate of soda employed in the preparation of the said jelly or like
mass may be such as that obtained by bicarbonating the soda contained in the soda
mother liquors obtained in the Leblanc alkali process, or suitable bicarbonate of
soda from other convenient source may be employed.
Instead of employing a sesqui or bicarbonate of soda to supply the carbonic acid
gas necessary to react upon the silicate of soda to form a jelly or like mass of
water and hydrate of silica, and to obtain as a carbonate of soda,, the soda result-
ing from the decomposition of the silicate of soda we by any convenient means, say
by blowing through perforated pipes, inject into and amongst a solution of silicate
of soda of suitable density, carbonic acid gas, preferably undilute when such can
be economically obtained, or it may be dilute as in the cooled products of com-
bustion of coke. Or carbonic acid gas from other suitable source, such as the
exhaust from a gas engine may be employed. When undilute carbonic acid gas
is employed the density of the solution of silicate of soda may be of about five
degrees Twaddle, but when dilute carbonic acid gas is employed a denser solution
of silicate of soda is employed and may be of about ten degrees Twaddle. We
preferably stop the injection of carbonic acid gas into the said solution of silicate
of soda when said solution becomes viscid which indicates that the silicate of soda
has become decomposed. Any excess of water may be separated from the said
jelly or like mass by draining as herein before described.
It is not advantageous to have a relatively large amount of mono or sesqui
carbonate of soda present in the gelatinous mass of water and hydrate of silica
because of the liability of part of such soda crystallizing on the face of the mould
when drying. For general use in treating spent sand for re-use for moulding
purposes we find that good results are obtained when the said jelly or like mass con-
tains about three per cent. of mono carbonate of soda. Any carbonate of soda in
excess of amount desired may be removed before incorporating the said mass
with the sand or like substances, by washing the said mass with water, or, and
preferably, by using excess of water when preparing the said mass and subsequently
draining away part of the water as hereinbefore described, which drained water
washes away with it in solution a portion of the soda. The soda washed away may
be recovered and employed as desired.
Any soda present in that part of the sand which becomes sufficiently heated
during the process of casting will combine with the sand and form therewith an
insoluble silicate of soda, and any soda remaining soluble may if desired, after
repeated re-use of sand, be eliminated by washing the sand with water.
When bicarbonate of soda is employed for mixing with sand or like substances,

page_text: for use in
making dry sand moulds or cores, we prefer to moisten the sand, after
the fusible bituminous materials as hereinafter described are added to such sand
in a dry state, with a strong and preferably concentrated solution of bicarbonate
of soda.
To ensure that castings will have a smooth or finished surface we incorporate
with the sand or like substances either fresh or spent in any convenient way suit-
able fusible carbonaceous materials which admit of being finely ground and
intimately mixed with the sand or like substances; and which when heated will
permeate the sand or like substances and readily evolve reducing gases during
the pouring or casting of the metals and which when mixed with sand used in
making dry sand moulds or cores shall after drying of the said moulds or cores
leave them hard, porous, and, after casting, readily separable from the metal;
and which after use shall not leave a residue deleterious to the re-use of the sand
or like substances. We for this purpose preferably employ fusible bituminous
materials of low cost such as coal tar pitch, asphalt, or the like. In practice we
find hard coal tar pitch to be suitable for this purpose.
The bituminous material or materials employed, when not sufficiently hard and
brittle may have a small quantity of sand or like material mixed with it or them
to facilitate grinding of the said bituminous material to a fine powder, of which
we prefer that the whole or greater part shall be sufficiently pulverized to pass
through a sieve of at least 30 meshes per linear inch in which condition such
powder is mixed in suitable proportion with the moulding sand preferably before
adding the jelly or bicarbonate of soda before described. The said proportion
is varied according to the class of castings to be made in the sand. There may
be added to the sand from about 2% by weight of the bituminous material for
making moulds for light castings, to about 7% for making "green sand" moulds
for heavy castings or for dry sand moulds or cores.
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 :-
First. The method of obtaining a mixture of water and hydrate of silica in a
gelatinous condition and containing a carbonate of soda, by employing silicate of
soda and sesquicarbonate or bicarbonate of soda in the manner, conditions, and
proportions substantially as described and for the purpose set forth.
Second. The method of removing any excess of soda from a mixture of water
and hydrate of silica in a gelatinous condition and containing carbonate of soda,
by washing or equivalent means substantially as and for the purpose set forth.
Third. The incorporation with sand or like substances to be used in making
moulds or cores for casting metals of a mixture of water and hydrate of silica in
a gelatinous or jelly like condition and containing a carbonate of soda substantially
as and for the purposes set forth.
Fourth. In making moulds or cores for casting metals, the combination with
the sand or other substances of a mixture of water and hydrate of silica in a
gelatinous condition and containing carbonate of soda substantially as and for
the purposes set forth.
Fifth. The incorporation with sand or like substances to be used in making
moulds or cores for casting metals, of fusible bituminous materials and a mixture
of water and hydrate of silica in a gelatinous condition and containing a carbonate
of soda, substantially as and for the purposes set forth.
Sixth. The combination with sand or like substances to be used in making loam
r dry sand moulds or cores of fusible bituminous materials and bicarbonate of
oda substantially as and for the purposes set forth.
Seventh. The process of preparing spent sand for re-use in making moulds or
ores for casting metals consisting in preparing fusible bituminous materials and
mixture of water and hydrate of silica in a gelatinous condition containing a

page_text: salt of sodium, in the manner conditions and proportions described and incor-
porating the same with the said sand in the manner and proportions substantially
as set forth.
Dated this Twenty fourth day of February 1899.
JOHN HARGREAVES.
ANDREW POULSON.