AN IM- *PROVED PROCESS AND APPARATUS FOR THE EXTRACTION AND RECOVERY OF ARSENIC FROM THE RESIDUE OBTAINED IN THE MANUFACTURE OF MAGENTA COLOUR
Year: 1878

page_text: LETTERS PATENT to August Samuel Leopold Leonhardt, of Mainkur, in the
Empire of Germany, Chemical Manufacturer, for the Invention of "AN IM-
*PROVED PROCESS AND APPARATUS FOR THE EXTRACTION AND RECOVERY OF
ARSENIC FROM THE RESIDUE OBTAINED IN THE MANUFACTURE OF MAGENTA
COLOUR."
Sealed the 6th August 1878, and dated the 8th February 1878.
PROVISIONAL SPECIFICATION left by the said August Samuel Leopold
Leonhardt at the Office of the Commissioners of Patents on the 8th February
1878.
AUGUST SAMUEL LEOPOLD LEONHARDT, of Mainkur, in the Empire of Germany,
Chemical Manufacturer. AN IMPROVED PROCESS AND APPARATUS FOR THE
EXTRACTION AND RECOVERY OF ARSENIC FROM THE RESIDUE OBTAINED IN THE
MANUFACTURE OF MAGENTA COLOUR."
This Invention relates to an improved process and apparatus for the extraction
and recovery of arsenic from the residue obtained in the manufacture of magenta
colour, whereby in addition to the advantage of recovering the arsenic, simple and
effectual means are provided for obviating the difficulty which has heretofore existed
in disposing of the said residue with safety.
The residuum resulting from the manufacture of magenta colour consists,―
First. Of a solid material composed principally of organic resinous substances
and some arsenic.
And, Secondly. Of a liquid containing chiefly arsenic and other mineral impurities,
and more or less of organic substances.
In carrying my said Invention into practice I employ as plant for my said process
an ordinary reverberatory furnace, to the end of which one or more covered shallow
evaporating pans are attached, over the surface of which the waste heat from the
furnace is caused to pass.

page_text: My said process may be said to be a continuous operation, but in order that it
may be clearly understood I will describe it as divided into four distinct operations
as follows, that is to say :-
First. The combustion of the aforesaid solid resinous residuum. This is effected
upon the grate of the reverberatory furnace, by which combustion the arsenic
contained in the said residuum is sublimed, and at the same time the necessary
heat for effecting the further operations of the process is generated.
Secondly. The aforesaid fluid residuum is caused to evaporate to a high state
of concentration by means of the heat generated by the combustion of the solid
resinous residuum on the grate of the furnace, as above described.
Thirdly. The arsenic contained in the desiccated or concentrated contents of the
aforesaid evaporating pans after evaporation is sublimed in the body, or on the bed
of the reverberatory furnace by means of the heat generated as herein-before
described.
Fourthly. The arsenic sublimed as herein-before described is condensed in flues
or chambers of the usual construction situated at the end of the said apparatus.
In commencing my said process the solid resinous residuum obtained from the
magenta colour is placed upon the grate of the furnace, and the liquid portion of
the residuum is poured into the aforesaid pans. As the combustion of the solid
resinous residuum proceeds, the arsenic contained therein is sublimed, and the heat
resulting from the said combustion passes over the liquid residuum and evaporates
it. The solid matter remaining in the pans after this evaporation is then removed
to the body or bed of the furnace, and the arsenic contained therein is sublimed
by means of the heat passing over it. It will therefore be seen that the whole
of the arsenic existing both in the solid and liquid portions of the residuum is.
recovered in a simple and effectual manner, and the heat required throughout the
process is supplied by the combustion of the residuum itself.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said August Samuel Leopold Leonhardt in the Great Seal Patent Office on
the 8th August 1878.
AUGUST SAMUEL LEOPOLD LEONHARDT, of Mainkur, in the Empire of Germany,
Chemical Manufacturer. "AN IMPROVED PROCESS AND APPARATUS. FOR THE
EXTRACTION AND RECOVERY OF ARSENIC FROM THE RESIDUE OBTAINED IN THE
MANUFACTURE OF MAGENTA COLOUR."
This Invention relates to an improved process and apparatus for the extraction
and recovery of arsenic from the residue obtained in the manufacture of magenta
colour, whereby in addition to the advantage of recovering the arsenic, simple and
effectual means are provided for obviating the difficulty which has heretofore existed
in disposing of the said residue with safety.
The arsenic employed for the production of the colouring matter called "Magenta,"
in the form of arsenic acid, is nearly all found in the solid and liquid refuse of the
manufacture.
The solid arsenical residues contain principally highly combustible resinous
matter, mixed, according to the mode of manufacture, with more or less of insoluble
compounds of lime, and with arsenic and arsenious acids.
The liquid arsenical residues contain chiefly the arsenic in the form of arsenical
and arsenious acids mixed with their respective lime and soda salts, but contaminated
with considerable quantities of common salt. This liquid residuum requires to be
evaporated to dryness before the recovery of arsenic from the same can be pro-
ceeded with.
In practising my Invention I employ apparatus which I have shown in the
accompanying Drawing.
Figure 1 is a longitudinal vertical section, and Figure 2 is a horizontal section of
the same.
My improved process of recovering the arsenic from these residues is as follows,
that is to say:-The solid residuum containing large quantities of organic matter
is burned upon the grate or part a of the reverberatory furnace A. The heat
resulting from this combustion is used for heating the bed b of the reverberatory
furnace A. The heated gases after leaving this furnace A, serve for the evaporation
of the liquid arsenical residue by being made to pass over the surface of the boiling-
down pans c filled with the arsenical refuse liquid. The desiccated contents of the
boiling down pans is subjected on the bed b of the reverberatory furnace in a
suitable manner to a process of roasting and sublimation. The sublimed arsenic,
together with the arsenic escaping during the combustion of the resinous solid residue
in tlie part a of the furnace, and the heated gases (that is to say the products of
combustion) pass over the evaporating pans c into condensing chambers placed
beyond the pan or pans c where they are condensed into arsenic. The greater part
of the steam and the products of combustion pass away after leaving the condensing
chambers up the chimney. The arsenical vapors issuing from the furnace being
cooled down by the steam arising from the boiling-down pans, deposit the arsenic
with an extraordinary facility and completeness, so that with even comparatively
small condensing chambers no arsenic passes into and up the said chimney:
d is a tube or funnel, furnished on the top with suitable lutes to prevent the
escape of arsenical vapours during charging. This tube serves for charging the
furnace with the organic arsenical residuum; e is a door through which the charge
can be raked and turned about if required; f is an aperture through which the slag
or clinker is dropped into the ash-pit: g are air channels in the furnace bridge, and
communicating with the air channel i through which the air is admitted, its
admission being regulated according to requirement by dampers or slides. The
bed of the reverberatory furnace A, is heated by the furnace gases from the
urnace grate a.

page_text: d' represents the feeding pipe. It is also furnishel with means for preventing
the escape of arsenical vapours. Through it the bed of the furnace is supplied with
the desiccated liquid arsenic waste taken from the boiling-down pans; e' is the
working door of the said furnace; j is an aperture for dropping into the space k
below the bed of the furnace, the nou-arsenical residuum consisting of common salt
carbonate and a small quantity of arseniate of lime after the arsenic has all been
volatilized therefrom; h', are air channels supplying the necessary air for the
combustion of volatile substances and the oxidation of the arsenic vapours. The
air is conveyed to them through the channel ¹, and its quantity is regulated by a
sliding door.
The
The surface evaporating pans c are attached to the reverberatory furnace; the
number and size of these pans depend upon the extent of the manufacture.
said pans are constructed of fire-clay slabs placed upon railway metals resting ou
brick pillars, or are placed upon a brick arch. Behind these evaporating pans are
the arsenic flues or condensing chambers. They are of the usual construction, and
a flue extends therefrom to the ordinary chimney stack.
The working is commenced by first heating the parts a, b, of the furnace with
ordinary fuel and filling the boiling-down pans.
When the furnace has attained a heat sufficient for the sublimation of arsenic,
it is charged with the desiccated contents of the boiling-down pans, and the furnace
grate a is now only fired with the above-named resinous arsenic waste.
The arsenious and arsenic acid contained in the charges of both parts a, b, of the
furnace are reduced by the heat, and in the presence of the organic and carbonaceous
matter, into metallic arsenic, which becomes volatilized, and is subsequently oxidized
by the excess of air admitted through the air channels h, h¹, into arsenious acid or
arsenic. In this form it is carried away by the draft of the chimney over the
boiling-down pans, and being mixed with steam from the latter, it is readily
deposited in the condensing chambers or flues behind the pans. It is obvious that
coal may also be used as fuel or be mixed with the residuum.
The working of this process is continued in the same manner as above described,
that is to say, the resinous residuum is continually charged into the part a of the
furnace, while the dry contents of the pans c are charged into the part b thereof,
and so on.
When an accumulation of inert matter, such as slag, on the furnace bed b has
taken place, the same is removed, the clinkers or slag being also removed from the
part a. The pans c are kept filled from a supply cistern with liquor to a suitable
level, so that the sublimation of arsenic and desiccation of liquid proceed in the
same ratio..
The operations are not interrupted until it is required to empty the condensing
chambers of the arsenic deposited therein, or the boiling-down pans are full of dry
residuum requiring to be removed. The furnaces are then allowed to cool down,
and both flues and pans are emptied of the material accumulated therein. The
arsenic obtained from the condensing chambers has to be refined in the ordinary
manner before being re-used.
The slag removed from the bed or part b of the furnace consists, if little or no
lime, has been used in the manufacture principally of common salt, which may be
used again for the precipitation of the coloring matter.
Having thus fully described the said Invention, and the manner of performing
the same, I wish it understood that I claim in my improved process for extracting
and recovering arsenic from the above residues,―
First. The use as fuel of the solid resinous arsenical waste or refuse resulting
from the manufacture of aniline colours, and the utilization of the heat produced by
its combustion for the sublimation of arsenic from the desiccated liquid waste, and
for the boiling down of the latter, while at the same time the arsenic contained in
the same is also sublimed and utilized.
Second. The passing of the arsenious vapours over liquids for the purpose of
facilitating the condensation and deposition of the arsenious acid, as above set forth.

page_text: Third. The apparatus consisting of the furnace, the evaporating pans, and other
parts, constructed and arranged as above described, and as shown in the Drawing.
In witness whereof, I, the said August Samuel Leopold Leonhardt, have here-
unto set my hand and seal, this Second day of August, in the year of our
Lord One thousand eight hundred and seventy-eight.
AUGUST SAM. LEOP. LEONHARDT. (L.S.)