IMPROVEMENTS IN. THE METHOD OF AND APPARATUS FOR SEPARATING FREE SULPHUR FROM SUBSTANCES CONTAINING IT
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Samuel Henry Johnson at the
Office of the Commissioners of Patents, with his Petition, on the
2nd September 1873.
I, SAMUEL HENRY JOHNSON, of Lea Bank Works, Warton Road,.
Stratford, Essex, Manufacturing Chemist, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN. THE METHOD OF AND APPARATUS
FOR SEPARATING FREE SULPHUR FROM SUBSTANCES CONTAINING IT," to be as
follows:-
My Invention consists in an improved method and apparatus for
soparating sulphur from mixtures containing it in the free state such as
sulphure ore or the material known as spent oxide of iron. For this
purpose any simple solvent may be used, but I prefer bisulphide of
carbon.
I effect the extraction in the following manner :-I put ja suitable
quantity of the material to be operated upon, which has previously been
brought to a suitable state of division into a receptacle, which herein-
after is called the extractor, provided with a filter near the bottom which

page_text: I then hermetically closc. Through a pipe in the bottom I then
introduce as much bi-sulphide of carbon as is necessary to dissolve all
the sulphur, taking care that an air cock on the top of the extractor is
open so as to permit the air to escape, I then licat the contents of the
extractor by means of a steam jacket or liquid bath up to and beyond_
the boiling point of bi-sulphide of carbon.
When a pressure of a few pounds to the square inch is indicated I
draw off the solution of sulphur by means of a cock placed at the bottom
of the extractor into an open cistern to avoid evaporation, from which a
few inches depth of water is always kept covering the solution and a
pipe from the cock delivers the sulphur solution beneath the level of the
water. This cistern supplies a still provided with a condenser and
suitable receiver. I next' introduce into the extractor sufficient bi-
sulphide of carbon to wash out the remainder of tho sulphur solution.
The sulphur solution is then evaporated in the still, being heated by
means of steam in a jacket on the bottom of the still until all or nearly
all the bi-sulphide of. carbon is removed.
:
The still is provided with blades or scrapers which are kept revolving
close to the bottom during the latter part of the distillation so as to
facilitate the evolution of the bi-sulphide of carbon by preventing tho
sulphur forming a mass at the bottom of the still.
In order completely to remove the bi-sulphide of carbon from the still
at the close of the process I inject steam directly into it so as to expel
all the bi-sulphide of carbon vapour. I then open the still and remove
the sulphur. The condensed bi-sulphide of carbon is available for a
fresh operation.
In order to recover the bi-sulphide of carbon which remains in the
residue in the extractor I inject steam at the top of the vessel so as to
permeate the material and evaporato it. The vapours pass into the
condenser of the still by means of a pipe and cock connected therewith;
from the bottom of the extractor.
When the whole of the bi-sulphide of carbon has been vaporized and
displaced by the steam, the extractor is opened and the residuum frec
from sulphur removed..
When bi-sulphide, of carbon vapour is mixed with atmosplicric air tho
tension of the former is so considerable at ordinary temperatures that"
"

page_text: a large quantity of the bi-sulphide of carbon becomes incondensible, and
is carried away with the air as it is expelled from the apparatus by tho
bi-sulphide of carbon vapour. Under these circumstances it is expedient
to permit as little air as possible to come in contact with the bi-sulphide
of carbon in the apparatus; it is with this object that I introduce the
bi-sulphide of carbon at the bottom of the extractor so as to float the
atmospheric air out of it through the air cock without admixture with the
bi-sulphide of carbon vapour, and with the same object I also perinit the
temperatature of the bi-sulphide of carbon in the extractor to be raised
beyond the boiling point so as to drive out the solution of sulphur
without permitting air to enter the apparatus. It is also apparent that
the subsequent washing will enter the apparatus without the necessity
of opening the air cock, for the bisulphide of carbon vapour will
condense on cooling, thus producing a partial vacuum sufficient for the
purpose. With the same object any incondensible vapours passing
through the condenser are conveyed by means of a pipe into an ordinary
gasholder, free communication with which is permitted to obtain through
the condenser during the distillation of the sulphur solution, but it
is closed at the termination before opening the still to remove the
sulphur.
At the commencement of each fresh operation of distillation after the
first one, and before charging the still from the supply cistern, the
incondensible mixture of bi-sulphide of carbon vapour and atmospheric
air is permitted to flow from the gasholder by means of a pipe passing
nearly to the bottom of the still in quantity sufficient to float out all tho
atmospheric air and replace it with air saturated with bi-sulphide of
carbon, the great density of the mixture permitting this to be done with
facility. When the distillation has commenced this saturated air finds
its way back again into the gasholder ready for another operation.
In order to raise the bisulphide of carbon from the receiver to the
extractor I close the receiver hermetically, which is always maintained
quite full of water'; a small overflow cock at the top permits the water to
flow out in proportion as it is displaced by the bi-sulphide of carbon.
A pipe for the passage of the bi-sulphide of carbon from the receiver
passes water-tight through the top of the receiver to nearly the bottom,
and at the upper end is connected with the extractor, the flow of
the bi-sulphide of carbon through which is controlled by means of
a cock.

page_text: Water can be admitted at the top of the vessel by means of a cock
attached to a water pipe conveying the water under sufficient pressuro to
force the bi-sulphide of carbon from the bottom of the receiver up the
pipe into the extractor, the water acting as a liquid piston; I thus force
the bi-sulphide of carbon to a higher level without any mechanical 5
appliances such as pumps, &c., in direct contact with the bi-sulphido of
carbon, and thus avoid loss by leakage and a complicity of joints which
is most desirable in working with bi-sulphide of carbon.