Process for the Elimination and Recovery of Arsenic from Copper Precipitates.
Year: 1893

page_text: Date of Application, 9th Dec., 1893
Complete Specification Left, 6th Sept., 1894-Accepted, 20th Oct., 1894
:
PROVISIONAL SPECIFICATION.
Process for the Elimination and Recovery of Arsenic from Copper
Precipitates.
I, EDWIN GORDON NIVEN NORTH, of 15 Bella Vista, Minas de Rio-Tinto,
Huelva, Spain, Chemist, do hereby declare the nature of this invention to be as
follows:-
The invention has for its object the freeing of copper precipitates from arsenic,
and the recovery of said arsenic in a thorough and economical way by ordinary
condensation plant, and the consequent enrichment of such precipitates in copper
contents.
The invention consists of two operations :-
1. The washing and preparation of the material under treatment, and slow and
thorough drying of the same.
2. The subjection of the prepared material to a temperature somewhat below
redness, with or without stirring, in a sealed vessel of clay or iron provided with a
small outlet pipe for the escape of the arsenical fumes.
The process is carried into effect somewhat as follows:
The precipitate is taken from the precipitating tanks and washed and classified
in any usual way, say, by means of water and inclined revolving perforated
cylinders, jiggers and buddles, thereby effecting a separation into poorer and richer
classes and removal of the major portion of the graphite.
The poorer classes in copper contents usually contain most arsenic.
The product, washed and freed from the major part of the graphite, after
draining, is transferred to the drying bed, which may be the firebrick arches
forming the tops of the upper flues of the muffle furnaces, under which the heated
flue gases pass on their way over the muffles on to the stack in the usual manner,
by which means I avoid the use of a special furnace for the drying operation,
thereby effecting an economy of fuel. During drying the precipitate is preferably
frequently stirred and kept in a pulverulent condition; when quite dry it is charged
into the muffles by means of hoppers, which deposit it at the entrance to the muffles
behind the charging doors in a space allotted for that purpose, from whence it is
pushed into the interior of the muffle by means of rakes. The entrance is then
closed by a nicely adjusted fireclay slab luted to maintain the apparatus airtight,
and the iron charging door is also closed. The muffles are constructed of well
fitting rebated fireclay or iron slabs securely set, and are provided with outlets
running along the tops of the muffles built in the main flues and passing the furnace
wall into ordinary condensing chambers or flues with the usual stop partitions
opening on alternate sides.
To facilitate the stirring the following arrangement may be used.
Sliding doors with a perforated small hole for the introduction of the poker or
tirrer may be provided. Lateral movement is obtained by means of the laterally
liding doors, and vertical movement is obtained by a small sliding plate let into the
liding door in vertical grooves. The whole is arranged so as to enable the poker
o be used without the admittance of air.
The heat is maintained by combustion of coke or coal or pyrites, the build of the
re bars being suited accordingly as the one or the other is to be used.

page_text: The arsenic is removed from the condensing chambers as "white arsenic."
Dated this 9th day of December 1893.
E. GORDON N. NORTH,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.
Process for the Elimination and Recovery of Arsenic from Copper
Precipitates.
I, EDWIN GORDON NIVEN NORTH, of 15 Bella Vista, Minas de Rio-Tinto,
Huelva, Spain, Chemist, do hereby declare the nature of my invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
The invention has for its object the freeing of copper precipitates from arsenic,
and the recovery of said arsenic in a thorough and economical way by ordinary
condensation plant, and the consequent enrichment of such precipitates.
The invention consists of two operations
1. The preparation of the washed and classified product by drying and stirring
the same.
2. The subjection of the prepared material to a temperature somewhat below
redness, preferably with stirring, in a sealed vessel of clay or iron provided with a
small outlet pipe for the escape of the arsenical fumes.
The process is carried into effect somewhat as follows:-
The precipitate is taken from the precipitating tanks and washed and classified
in any usual way, say, by means of water and inclined revolving perforated
cylinders, jiggers and buddles, thereby effecting a separation into poorer and richer
classes and removal of the major portion of the graphite, slimes, &c. &c.
Of the classified products, those chosen for treatment are transferred to the
drying bed, which may be the firebrick arches forming the tops of the upper flues
of the muffle furnaces, under which the heated flue gases pass on their way over
the muffles on to the stack in the usual manner, by which means I avoid the use of
a special furnace for the drying operation, thereby effecting an economy of fuel.
During drying the precipitate is frequently stirred and kept in a pulverulent
condition. When quite dry it is charged into the muffles by means of hoppers,
which deposit it at the mouth of the muffles, whence it is distributed over the
interior of the muffle by means of rakes. The entrance is then closed by a nicely
adjusted fireclay slab, luted to maintain the apparatus airtight, and the iron
charging door is also closed. The muffles are constructed of well fitting rebated
fireclay or iron slabs securely set, and are provided with outlets running along the
tops of the muffles, built in the main flues and passing the furnace wall into
ordinary condensing chambers or flucs with the usual stop partitions opening on
alternate sides to facilitate condensation.
For the purpose of stirring the contents of the furnace any suitable stirring
apparatus may be provided.
The heat is maintained by combustion of coke or coal or pyrites, the build of the
fire bars being suited accordingly as the one or the other is to be used.
The arsenic is removed from the condensing chambers as "white arsenic."
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what
I claim is :-
1. The improved process herein described for the elimination and recovery of
arsenic from copper precipitates.

page_text: 2. The treatment of copper precipitates by the process herein described and for
the purpose stated.
Dated Sontember 6th 1001
E. G. N. NORTH,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.