Improvements in the Treatment, Application, or Use of Waste Sand from Glass Grinding or Polishing or certain other Sand or Minerals containing Iron.
Year: 1899

page_text: Date of Application, 25th Apr., 1899
Complete Specification Left, 25th Jan., 1900-Accepted, 3rd Mar., 1900
PROVISIONAL SPECIFICATION.
Improvements in the Treatment, Application, or Use of Waste Sand
from Glass Grinding or Polishing or certain other Sand or Minerals
containing Iron.
We, WILLIAM WINDLE PILKINGTON, J.P., of The Hazles, Prescot, in the County
of Lancaster, Glass Manufacturer, and WILLIAM REGINALD ORMANDY, D. Sc., of
142, Windeleshaw Road, St. Helens, in the same County, Chemist, do hereby
declare the nature of this invention to be as follows:
-
This invention has for its object an improvement in the process of treating
waste sand of glass works by drying it, reducing the iron in it by heating it
with fuel, separating the major part of the iron by magnetic appliances, oxidizing
the remaining iron and treating it in a furnace with chloride of ammonium
and hydrochloric acid whereby the iron is separated as a chloride.
We have found that the sand after having passed through the reducing furnace
and the magnetic separators can now be freed from its remaining iron in the cold
or hot by acid, preferably hydrochloric. Also that quite weak acid can be
used for this purpose when the iron is in the metallic state. By the operation
too of deoxidizing, the slimy or organic matter in the sand is burnt out, and the
sand becomes denser and therefore much more easily separates from the acid,
and can be more easily washed free from acid.
The furnace for reducing the iron in the sand is preferably formed in three
parts alongside each other, or one over the other. In the central one the iron
is reduced in a tube or retort having a worm passing through it.
This worm
is preferably composed of a hollow cast-iron pipe having ribs cast thereon. The
exhaust steam from the engine is passed through the central tube to keep it
cool, and this steam, superheated in this tube, can afterwards be added to the
products of combustion. These are passed over and under the bed of the drying
furnace, and assist in drying the sand. The sand from the middle furnace passes
to a third furnace or chamber through which a producer gas passes in the reverse
direction. The sand is then cooled and the gases heated for combustion in the
middle furnace. Between the drying furnace and the reducing furnace we place
a coarse filter consisting of a plate perforated with numerous holes down which
the sand runs to the middle furnace. Any lumps too big to pass through the
perforations pass out at the end. The sand which has been cooled is now passed
through a crushing machine to destroy any agglomerations which may have taken
place. This crushing machine is preferably a sort of conical chamber in which
a much more obtuse cone revolves at the bottom leaving a space of only about
one-hundredth of an inch all round at which the sand can exit. The sand is
now passed alone or mixed with water to the magnetic machines where the iron
is separated. The remaining sand is then passed to acid tanks hereinafter men.
tioned, or is treated in the manner already set forth in the preamble or the dried
sand still hot is pressed into shapes and is baked into bricks or other objects.
In carrying out the operation therefore, we mix the sand and reduced iron

page_text: with water and pass them through the separating machines as a sort of soupy
liquid. This is then run still as a thick liquid into the tanks and at once treated
with hydrochloric acid, and when the action has ceased the sand is allowed to
subside, the spent acid run off, and fresh water added, and mixed up with the
sand, and the water afterwards run off. This operation is repeated as often as is
necessary, or in place of this, the sand can be placed in a filtering device or in
a centrifugal machine and washed by this means, fresh water being run in during
the operation.
This invention is also applicable for purifying sea and other sand Kaolin alumina
clay and other mineral substances containing iron.
Dated the 24th day of April 1899.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicants.
Improvements in the Treatment, Application, or Use of Waste Sand
from Glass Grinding or Polishing or certain other Sand or Minerals
containing Iron.
We, WILLIAM WINDLE PILKINGTON, J.P., of The Hazles, Prescot, in the County
of Lancaster, Glass Manufacturer, and WILLIAM REGINALD ORMANDY, D. Sc., of
142, Windleshaw Road, St. Helens, in the same County, Chemist, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
This invention has for its object an improvement in treating waste sand of
glass works. It has long been known theoretically that oxide of iron can be
eliminated from finely divided powdered silica by very long heating with strong
acids, but this is merely a laboratory process carried on in glass, porcelain or
platinum vessels and is too expensive for industrial operations.
Now we have found that if we heat this very finely divided ferruginous sand
with fuel to a certain temperature varying with the nature of the substance from
dull to cherry red and out of contact of air, the iron is reduced to the metallic
state, and it is then easily taken up by strong mineral acids even when con-
siderably diluted with water, but in the presence of much iron the cost of this
operation is almost prohibitory. If however when the iron is reduced the greater
part is separated magnetically by magnetic separators, the remaining iron is very
easily and cheaply eliminated from the sand by converting it into a chloride
either in the dry or wet way. If in the wet way the quantity of acid required
is comparatively little, and the dissolving very quickly effected in the cold even
with rather dilute acid, while if it be done in the dry way at a red heat the
vapours of chloride of ammonium and still better a mixture of the vapours of
chloride of ammonium and hydrochloric acid very quickly withdraw the iron as
anhydrous gaseous chloride, which can be separated from the ammoniacal gases
by careful fractional condensation, and the ammoniacal gases used over again
with more hydrochloric acid for cleaning a fresh batch. The chloride of iron
thus obtained is a valuable by-product.
Now our invention is based on these facts. It is only effective however when
the material is in a very finely pulverized condition as in the case of this waste
glass works sand. Our process will purify finely pulverized silica, alumina and
various silicates from ion, all of which however will be spoken of hereafter under
the ordinary generic word sand."
"
,

page_text: We carry out our invention therefore by heating this sand to the requisite degree of
redness with gaseous fuel till the iron is all reduced, and then separating most of
this iron by magnetic separators. If the heat be too great silicate of iron is formed
and this cannot be reduced to iron, nor can the iron in it be dissolved in dilute
acid.
The
If the heat be too little the resulting powder does not subside rapidly
enough to allow of washing by decantation when the wet process is used.
remaining iron we now separate from the sand as chloride either in the dry or
the wet way. In the dry way we pass the sand, after oxidation of remaining
iron by heating in the air, down a tower with shelves projecting beyond the centre
line of the tower from each side so that the sand gradually trickles from shelf to
shelf till it reaches the bottom from whence it is removed automatically by its
own weight on a counterweighted valve. Up this tower we pass chloride of
ammonium and hydrochloric acid vapours, the whole being heated to a bright
red heat. The result is that the entire residual iron passes away as anhydrous
chloride of iron and is condensed by careful fractional condensation while the
chloride of ammonium vapour and the remaining hydrochloric acid or ammonia
is passed back again to be re-applied for the chloridation of the iron with an
additional supply of hydrochloric acid. The plan however which we prefer most
is simply to run the sand after it has been deoxidized and cooled out of contact
with air into a large tank by means of a stream of water. Up and down the
entire length and breadth of this tank large groups of pendent magnets are moved,
thus forcing each granule of the sand to its disseminated condition in the water
to pass within an almost imperceptible distance of the magnets. From time to
time the magnets are moved over a partition where they are de-magnetized and
the iron allowed to fall. They are then brought back for fresh work, or any
other well known continuous or intermittent magneto electric separator devised
When the sand
for parting magnetic substances from a fine gangue can be used.
is sufficiently clear of iron it is preferably run into a lower tank made of acid
proof ware, where the water is allowed to drain off and then the sand treated with
hydrochloric acid and gentle stirring with or without warming according to degree
of purity required. The iron free sand is now separated from the solution of
iron by washing by decantation, by means of filter presses or hydro extractors.
In this way the sand is freed to any desired extent from the trace of iron left in
it. Where however the sand is treated in the dry way we use ordinary revolving
magnetic separators while the sand is still in a warm dry state, re-oxidize the
remaining iron and then pass the sand direct into the chloridizing furnace.
In order that our invention may be more clearly understood, we append the
following drawings of the reducing plant.
In these:
Figure 1 is a longitudinal section of our drying and reducing apparatus;
Figure 2 a horizontal section through same:
Figure 3 end view of same, and
Figure 4 a transverse vertical section.
narrow
In these a is a cylinder made of boiler plate into which the sand is fed through
a spout b. This cylinder is fixed in a flue c surrounding the same, except at
the bottom where the cylinder is protected from direct action of the flame of
combustion chamber d by the firebrick coating e. f is the cold or hot air supply
and the
9 gas supply. These enter the combustion chamber d by the openings h.
passages connecting the combustion chamber d with the flue c.
j. Figure 3, is a pipe taking gas from the cylinder a to a gas flue g. k tubular
shaft passing through stuffing boxes through the ends of cylinder a and sup-
This shaft is driven by wheel o from
ported on drums m on friction rollers n.
any required source of power. is a steam jet brought from any supply of
steam, or the waste steam of an engine can be passed in at this point. This
is the escape for
steam passes through the shaft
the waste gases from the flue c. It passes into a spacer and from thence to the
chimneys through opening t. Above this spacer is a sloping tray u on which
and helps to keep it cool.

page_text: the sand is dried by the refuse heat passing from the flue c. is an opening into
the flue a, projecting up above the bottom of the flue for some distance. This
opening is for the sand to escape and fall down into the space w, and also for
gas to enter the flue a from the gas opening a. The space w is kept full of a
reducing gas in which the sand cools, but as the sand accumulates it can be
drawn out from the bottom by a door not shown. Where a continuous cooler
is desired the sand can pass into an iron tube inclined and revolving up which
the cold producer gas passes on its way to the furnace thus cooling the sand
and warming the gas; or in place of a revolving tube, a tube provided with a
moving screw or scraper can be used. y are a series of archimedian beaters tend-
ing to force the sand from the opening to the opening. These are supplied
with angle iron scrapers as shown.
The mode of action is as follows:
The sand being dried in the tray is passed down the spout from a suitable
hopper and feeder, (not shown in Figure 1 but shown at Figure 3) into the
cylinder a. The shaft being in constant motion, the beaters y pass the sand
gradually forwards until at length it arrives at the opening . During this time
it is exposed to an atmosphere of producer or other reducing gas which enters
at and escapes down the pipe into the gas flues. This gas, together with
other gas if necessary supplied to the flue g, enters the combustion chamber,
and thus produces a sufficient heat to heat the cylinder a to a certain redness.
The sand passing along the cylinder a is itself heated to redness, and being
exposed to the reducing gas, the iron in it is reduced to the metallic state. The
iron in the sand having thus been fully reduced to the metallic state, the sand
is cooled in a reducing atmosphere and passed when it is so cool that the iron
will not oxydize rapidly in the air, for magnetic treatment, to the tanks already
mentioned. As the sand when it arrives from the deoxydizing furnace is often
rather lumpy, we prefer to pass it through a crushing machine to destroy any
lumps which may have been formed. This crushing machine is preferably a sort of
conical chamber in which a much more acute cone revolves at the bottom,
leaving a space of only about one-twentieth of an inch all round at which the sand
can exit. The sand is now passed along alone or mixed with water to the
magnetic machines where the iron is separated.
Having now particularly described and ascertained the nature of our said in-
vention, and in what manner the same is to be performed, we declare that
what we claim is:-
1. The process of purifying the waste sand of glass works and other finely
divided mineral sand containing oxide of iron which consists in heating the
mixture in a finely pulverized form with fuel, preferably gaseous, between certain
temperatures, until the iron is reduced to the metallic state, separating the
greater portion of the iron by magnetic separators and the remainder by chemical
means in the dry or wet way as a chloride of iron.
2. The improved apparatus for deoxidizing fine granular material substantially
as herein described and illustrated.
3. The improvement in the process of purifying sand from iron which con-
sists in heating it to a red heat with chloride of ammonium vapour with or with-
out hydrochloric acid whereby a valuable by-product, anhydrous chloride of
iron, is obtained.
ated
this 24th day of January 1900.
WM. P. THOMPSON & Co.,
Patent Agents, of Liverpool, Manchester, Birmingham, & London.
WM. P. THOMPSON & Co.,
Patent Agents, of Liverpool, Manchester, Birmingham, & London.