Means of Metallic Chlorides.
Year: 1885

page_text: from Alkali Waste by Means of Metallic Chlorides.
We PETER ALFRED MAWDSLEY of the Firm of Smith and Mawdsley of Pentre
Alkali Works Flint North Wales Chemical Manufacturer and THOMAS MACFARLANE
of Montreal Province of Quebec in the Dominion of Canada at present residing at
Pentre aforesaid Chemist do hereby declare the nature of said Invention to be as
follows:-
The refuse product known as alkali soda or tank waste is exposed to the action
of the atmosphere in loose heaps on watertight floors until it is carbonated and
oxidized to such an extent as to yield on lixiviation the solutions known as yellow
liquors which contain Hydro-Sulphide and Polysulphides of Calcium. The heaps
must be kept cool by drenching with water and loss of sulphur by their taking fire
and burning thus prevented. The waste thus prepared is placed in lixiviating vats
of the same construction as are used in the Soda manufacture and lixiviated when
it yields yellow liquor of a density of about 20° Twaddell. The yellow liquor
thus obtained or that derived from the spontaneous oxidation and natural lixivea-
tion of Tank waste heaps in situ is next treated with a solution of Chloride of Iron
which may be obtained as a waste product from various manufactures such as
extracting Copper ores galvanizing and tinning Iron &c. A black precipitate is thus
formed consisting of Protosulphide of Iron and free sulphur and a slight excess of
the ferrous Chloride solution is used in order to precipitate all the sulphur. The
supernatant liquid which contains chiefly Chloride of Calcium is filtered off from
the precipitate and the latter washed upon filter cloths placed upon perforated
bottoms in filter boxes. The washing may also be done previous to the filtering by
subsidence and decantation. The precipitate in a pulpy state is then placed upon
the floor of a drying kiln constructed of fire clay tiles about 24 inches square with
flues underneath and carefully dried at as low a temperature as possible-The
result is a coarse black powder containing about 70% hydrated protosulphide of
iron and 30% free Sulphur-In order to the recovery of the latter the dried
precipitate is introduced into a small furnace heated to low redness constructed on
the same principle as the "blind roaster" used in manufacturing Salt Cake. This
small furnace has only two charging doors which after the precipitate has been
introduced are shut and luted as close as possible. The heat being continued the
free sulphur is sublimed and carried over into a condensing chamber where it is

page_text: either deposited as flour of sulphur or by increasing the beat melted and run off
into moulds forming roll sulphur. After the free sulphur has been driven off air
is allowed to have access to the furnace, by the working doors or otherwise, when
the sulphur of the protosulphide of iron ignites and burns forming sulphurous acid
which may be carried into the leaden chamber and used for producing sulphuric
acid. After this calcination is completed, the residue consists chiefly of peroxide
of iron in a very fine state of division and well suited for use as a pigment.
Results entirely analogous to the foregoing may be obtained by the use of
chloride of zinc, chloride of manganese and other metallic chlorides, so that we do
not confine ourselves to the use of chloride of iron only, nor to the use only of the
apparatus above described, because the latter may be much modified and yet
produce similar results. We may state that we are aware that it has been proposed
to use chloride of manganese for recovering sulphur from yellow liquor but the
manganous sulphide and free sulphide produced was not subjected to sublimation
nor the free sulphur separated from it as such.. It was simply calcined in the usual
manner and the sulphur converted into sulphurous acid. But what we claim and
desire to secure by Letters Patent is―
1. The production of flour or roll sulphur by sublimation from the precipitates
produced on treating metallic chlorides by yellow liquor as above described.
2. The production of ferric oxide in a fine state of division for use as a pigment
from calcining precipitated protosulphide of iron as above described.
Dabad thin 70th J
2
1005

page_text: from Alkali Waste by Means of Metallic Chlorides.
:
We, PETER ALFRED MAWDSLEY of the firm of Smith and Mawdsley of
Pentre Alkali Works, Flint, North Wales Chemical Manufacturer and THOMAS..
MACFARLANE of Montreal, Province of Quebec in the Dominion of Canada, 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:—
:
According to this Invention we take the refuse product known as Alkali soda
or tank waste and obtain from it what is known as yellow liquor which may be
effected by exposing it to the action of the atmosphere in loose heaps on water-
tight floors or otherwise until it is carbonated and oxidized to such an extent as
to yield on lixiviation the solutions known as yellow liquors which contain hydro-
sulphide and polysulphides of Calcium. The heaps must be kept cool by drenching
with water, and loss of sulphur by their taking fire and burning, thus prevented.
The waste thus prepared is placed in lixiviating vats of the same construction as
are used in the soda manufacture, and lixiviated when it yields yellow liquor of a
density of about 20° Twaddell. The yellow liquor thus obtained or that obtained
from the spontaneous oxidation and natural lixiviation of tank waste heaps in situ,
is next treated with a solution of chloride of iron, which may be obtained as a
waste product from various manufactures, such for example as extracting copper
from ores, or galvanizing and tinning iron. A black precipitate is thus formed
consisting of protosulphide of iron and free sulphur, and a slight excess of the
ferrous chloride solution is used in order to ensure the precipitation of all the
sulphur. The supernatant liquid which contains chiefly chloride of calcium is
filtered off from the precipitate and the latter is then washed upon filter cloths
placed upon perforated bottoms in filter boxes. The washing may also be done
previous to the filtering by subsidence and decantation. The precipitate in a pulpy
state is then placed upon the floor of a drying kiln constructed of fire clay tiles
about 24 inches square with flues underneath and the said precipitate is thereon
carefully dried at as low a temperature as possible. The result is a coarse black
powder containing about 70 per cent of hydrated protosulphide of iron and 30 per
cent of free sulphur. In order to recover the latter the dried precipitate is
introduced into a small furnace, heated to low redness, and constructed on the same
principle as the "blind roaster" used in manufacturing salt cake. This small
furnace has only two charging doors which, after the precipitate has been
introduced, are shut and luted as closely as possible. The heat being continued the
free sulphur is sublimed and carried over into a condensing chamber where it is
either deposited as flowers of sulphur or by increasing the heat it may be melted
and run off into moulds to form roll sulphur. After the free sulphur has been
driven off air is allowed to have access to the furnace by the working doors or
otherwise when the sulphur of the protosulphide of iron ignites and burns forming
sulphurous acid which may be carried into a leaden chamber and used for pro-
ducing sulphuric acid in the ordinary way. After this calcination is completed

page_text: the residue consists chiefly of ferric oxide in a very fine state of division and
well-suited for use as a pigment.
Results entirely analogous. to the foregoing may be obtained by the use of
chloride of zinc, or chloride of manganese or other metallic chlorides so that we do
not confine ourselves to the use of chloride of iron only nor do we limit ourselves
to the use of the apparatus above described because the latter may be much
modified and yet produce similar results-We may state that we are aware that it
has been proposed to use chloride of manganese for recovering sulphur from yellow
liquor but the manganese sulphur and free sulphide produced was not subjected to
sublimation nor the free sulphur separated from it as such. It was simply calcined
in the usual manner and the sulphur converted into sulphurous acid.
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 manufacture of flowers of sulphur or roll sulphur by sublimation
.from the precipitates produced by treating the yellow liquor of alkali waste with
metallic chloride as hereinbefore described.
Second. The manufacture of ferric oxide in a fine state of division by calcining
precipitated protosulphide of iron produced from the yellow liquor of alkali waste
as hercinbefore described,