Improvements in and relating to the Manufacture of Zinc Oxide.
Year: 1893

page_text: Date of Application, 28th Feb., 1893
Complete Specification Left. 28th Dec., 1893-Accepted, 24th Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Manufacture of Zinc Oxide.
I ANDREW GRAY of 555 Govan Street, Glasgow, Lanarkshire, Chemical
Manufacturer, do hereby declare the nature of my said invention to be as
follows:
This invention has reference to and comprises improvements in the manufacture
of oxide of zinc from refuse or by-products of zinc or spelter, such as old or new
zinc scraps and cuttings, galvanizer's hard spelter, zinc ashes, flux skimmings or
any crude oxide of the metal, aud in the apparatus for producing the oxide from
these. The improved apparatus and process producing the oxide of zinc in a more
economical manner and in a better condition for use in the manufacture of paints
than by the processes at present in use.
According to the improvements of this invention, scraps or cuttings of zinc or
spelter, or hard spelter as made by galvanizers are first prepared for treatment by
putting them into a convenient form it may be by breaking them up or otherwise,
or zinc ashes, skimmings or any crude oxides made in the melting down or working
of either old or new zinc or spelter are prepared for treatment by grinding to a
suitable fineness. Flux skimmings as taken off the surface of a galvanized dipping
bath are successively treated with water either hot or cold in tanks for the
extraction of all the soluble chlorides then dried in a reverberatory or any
convenient form of furnace or oven to drive off any hydrochloric acid that may
remain and then complete the preparation by grinding.
After preliminary treatment any or all of these products are burnt on the surface
of the coke in a coke furnace preferably of a type to be described in which the heat
is maintained to a temperature sufficient to volatilize the zinc and burn the vapour
over the incandescent fuel thus converting the metal at once into oxide of zinc in a
finely divided or powdered state which can be drawn off along with the other
products of combustion as will be described.
The furnace would preferably be of the ordinary blast or cupola type but instead
of having a close or solid bottom it might be fitted with a grating of either solid or
hollow furnace bars, up through which a blast of air or steam or both combined
would be maintained sufficient to secure the combustion not only of the fuel but
also of the volatilized zinc vapours produced over the fire, and this blast of air
might be supplied by jets of compressed air blowing up through the fuel, or a
closed ashpit might be used into which the compressed air would be led by a pipe
from the air compressor or fan, or if steam was employed, by a suitable arrangement
of nozzles this could be made to carry in the desired quantity of air. The furnace
would be fitted with a closing door for the introduction of the fuel and the zinc or
zinc products to be-treated. and have doors for the removal of the ashes, it would
also have an opening at the back by which to lead off the products of combustion
carrying the finely powdered oxide of zinc; and these would be led off by means
of a system of flues preferably horizontal to partially cool. Within this system of
flues a fau or air propeller might be placed to induce a strong current through the
furnace and flues. After passing through the flues the vapours carrying the oxide
of zinc would be finally condensed either in a large chamber, by the aid of a spray
of cold water or by steam, or in a tower within which water would be rained down
on the ascending gases, or by forcing them through a body of water in any
convenient receptacle. Otherwise the vapours and oxide of zinc might be led by a
pipe or pipes down into water contained in a close tank above which a vacuum was
maintained by. any suitable means. From any of these forms of condensing

page_text: appliances the wet oxide of zinc could be extracted for utilization either as a wet.
pigment or dried for use in the preparation of oil paint.
Dated 27th February 1893:
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Zinc Oxide.
I, ANDREW GRAY, of 555 Govan Street, Glasgow, Lanarkshire Chemical
Manufacturer, 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 in writing, reference being had to the accompanying
drawings:
My invention has reference to and comprises improvements in the manufacture
of oxide of zinc from refuse or by-products of zine or spelter, such as old or new
zinc scraps and cuttings, galvanizers' hard spelter, zinc ashes, flux skimmings or
any crude oxide of the metal, and in the apparatus for producing the oxide from
these. The improved apparatus and process producing the oxide of zinc in a more
economical manner and in a better condition for use in the manufacture of paints
than by the processes at present in use.
According to the improvements of my invention scraps or cuttings of zinc or
spelter, or hard spelter as made by galvanizers are first prepared for treatment
by putting them into a convenient form, it may be by breaking them up or other-
wise; or zinc ashes, skimmings or any crude oxides made in the melting down
or working of either old or new zinc or spelter are prepared for treatment
by grinding to a suitable fineness. Flux skimmings as taken off the surface of
a galvanizers dipping bath are successively treated with water either hot or cold
in tanks for the extraction of all the soluble chlorides, then dried in a
reverberatory or any convenient form of furnace or oven to idrive off any hydro-
chloric acid that may remain and then the preparation is completed by grinding.
After preliminary treatment any or all of these products are burnt on the surface
of the coke in a coke furnace preferably of a type to be described, in which the
heat is maintained to a temperature sufficient to volatilize the zinc and burn the
vapour over the incandescent fuel, thus converting the metal at once into oxide of
zinc in a finely divided or powdered state, which can be drawn off along with the
other products of combustion as will be described.
.
The furnace used is of the ordinary blast or cupola type, but preferably such as
is, shown in the drawings, but instead of having a close or solid bottom it might be
fitted with a grating of either solid or hollow furnace bars, up through which a blast
of air or steam or both combined would be maintained sufficient to secure the
combustion not only of the fuel but also of the volatilized zinc vapours produced
over the fire, and this blast of air might be supplied by jets of compressed air
blowing up through the fuel, or a closed ashpit might be used unto which the com-
pressed air would be led by a pipe from the air compressor or fan, or if steam was
employed, by a suitable arrangement of nozzles this could be made to carry in the
desired quantity of air. The furnace would be fitted with a closing door for the
introduction of the fuel and the zine or zinc products to be treated and have doors
for the removal of the ashes, it would also have an opening at the back by which to
lead off the products of combustion carrying the finely powdered oxide of zinc ;
and these would be led off by means of a system of flues preferably horizontal to
partially cool. Within this system of flues a fan or air propeller might be placed
to induce a strong current through the furnace and flues. After passing through
the flues the vapours-carrying the oxide of zinc would be. finally condensed, either

page_text: in a large chamber by the aid of a spray of cold water or by steam, or in a tower
within which water would be rained down on the ascending gases, or by forcing
them through a body of water in any convenient receptacle. Otherwise the
vapours and oxide of zinc might be led by a pipe or pipes down into water
coutained in a close tank above which a vacuum was maintained by any suitable
means. From any of these forms of condensing appliances the wet oxide of zine
could be extracted for utilization either as a wet pigment or dry for use in the
preparation of oil paint.
And in order that my said invention and the manner of carrying the same into
effect or practice may be properly understood I have hereunto appended an
explanatory sheet of drawings, in which
Figure I is a sectional elevation, partly broken away, of one form of apparatus
as constructed in accordance with my improvements, and
Figure 2 is a plan view of the hollow coil which may be used for supplying
steain and air to the under part of the fire in the furnace.
The furnace A is constructed of an outer iron shell a, and has an inner lining a
of firebrick, ganister, or such like refractory material, furnace bars a which may
be of any ordinary construction, furnace door a³ preferably hinged to open upwards,.
one or more closely fitting manhole or other ashpit doors a and chimney fitted'
with a damper a. The furnace would also be fitted with small close fitting doors a¹t
for the purpose of allowing access to clean the upper surface of the furnace bars;.
and in some cases compressed air from any air compressing apparatus would be led
into the close ash pit by a nozzle as indicated at a. The products of combustion.
consisting of oxide of zinc in a pulvurous form and gases formed within the
furnace A are conveyed through a pipe or duct B which may be of any desirable
length fitted with damper, as shown, or it might be a sliding damper and with a
nozzle for projecting a jet of stean, brought from a steam boiler, to assist in
drawing off the products of combustion through.said pipe B and causing them to.
enter a chamber or tower C. Instead of using one steam jet in the duct B two or
more may be used, or in some cases an annular steam jet may be employed. This.
tower C may be formed as a cylindrical iron shell with close bottom preferably
galvanized or otherwise coated to resist oxidisation, but it may be constructed of
other material such as firebrick or wood which may have an inuer lining of any
suitable nature. The upper part of this tower C is formed as a water tank c having
a perforated botton c' and fitted with any ordinary construction of tap or valve c
actuated by a ball float for regulating the supply and the height of water within
the tánk .". The water falling through the perforated bottom cl would collect in
the lower part of the chamber and escape by the syphon overflow pipe c³ into any
convenient trough or receptacle.. A. manhole or other water-tight door may also
be fitted at the bottom of chamber C for clearing out any precipitated oxide of
zinc. The products of combustion now partially cooled and deprived of a portion
of the oxide of zinc would pass from the chamber C by one, two or more pipes D
or passages, shown as broken away, which might be iron pipes or built of firebrick
and have close fitting doors d'for the purpose of cleaning out or removing any
deposited oxide of zinc, into another chamber or tower E somewhat similar to
the chamber C. This chamber E instead of having a water tank at top part is
fitted with a perforated pipe e to lead in steam at a low pressure to mingle with the
products of combustion and the condensed steam collecting at the bottom will
escape over the syphon overflow pipe el. From the chamber E the products of
combustion pass into a pipe F from which they are forced by a jet of steam from
a nozzle down through a trumpet mouthed nozzle f' contracted towards its lower
end and perforated with numerous small holes, into water contained in a tank G
having a partition carried from the upper part to near the bottom and overflow
pipe g pipe 9 for the escape of the insoluble gaseous products of combustion and
one or more manhole doors g' for removing the oxide of zinc precipitated to the
bottom of the tank. One or more of these nozzle apparatus may be employed, or
instead of or in combination with them a fan or other air propeller may be
。

page_text: employed to force the products of combustion into the water in the tank Gor
through the passages of the apparatus.
Instead of employing compressed air in a close ashpit by an alternative method
a perforated coiled tube indicated in Figure 1 at a and shown in plan in Figure 2.
may be placed beneath the furnace bars or may be used to support the fuel instead
of solid furnace bars into which a current of air would be forced by a jet of steam,
which might be previously superheated, from a nozzle a Figure 2 fitted at its outer
open end, so as to supply the fuel with a current of mixed steam and air.
The steam, compressed air, and water pipe connections are of any ordinary kind,
and are not shown in the drawings.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
First. The process of manufacturing oxide of zinc from refuse or by-products of
zinc or spelter all substantially as herein described.
Second. The process of manufacturing oxide of zinc from refuse or by-products
of zinc or spelter and the use of the apparatus for that purpose. all substantially as
herein described and by way of example shown in the accompanying drawings.
Third. The construction or arrangement and combination of the parts of
apparatus for the manufacture of oxide of zinc from refuse or by-products of zinc
or spelter all substantially as herein described and by way of example shown in the
accompanying drawings.
Fourth. The construction or arrangement and combination of the parts of a
furnace for use in the manufacture of oxide of zinc all substantially as herein
described and shown in the accompanying drawings.
Fifth. In a furnace as herein described for the manufacture of oxide of zinc the
use below the furnace bars or in place of the furnace bars of a coiled perforated
pipe for the supplying of steam and air to the burning fuel all substantially as
herein described and shown in the accompanying drawings.
Sixth. In an apparatus for the manufacture of oxide of zinc by the herein
described process the use of a perforated trumpet mouthed nozzle and steam jet
for discharging the products of combustion all substantially as herein described
and shown in the accompanying drawings.
Dated the 27th December 1893.
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents..