Improvements in Processes for the Manufacture of Sulphate of Lead and Apparatus therefor.
Year: 1890

page_text: Date of Application, 13th Oct., 1890
Complete Specification Left, 13th July, 1891-Accepted, 10th Oct., 189/
PROVISIONAL SPECIFICATION.
Improvements in Processes for the Manufacture of Sulphate of Lead
and Apparatus therefor.
I, HENRY CLAY BULL, of 12, Trafalgar Road, Old Kent Road, London, S.E.
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has mainly for its object to produce sulphate of lead direct from
the ore-sulphide of lead or gallena.
According to this invention the gallena is first vapourized by heat and the
vapour from the gallena is mixed with air or air and steam and burnt, thereby
producing sulphite of lead. Subsequently it is mixed with nitric acid fumes pro-
duced as hereinafter described. The air or air and steam is or are supplied in
excess to that required to burn the gallena vapour, and it or they together with
the nitric acid fumes and steam is or are used to further oxidize the sulphite of
lead and convert it to sulphate. The sulphate is collected and the by-products
treated and recovered as hereafter described.
:-
The apparatus used and the mode of conducting the process are as follows:-
A Siemens or like regenerative gas furnace is used and serves to heat the com-
bustion chamber having within it a plurality of retorts, in these retorts charges
of gallena broken into suitable sized pieces are vapourized by the heat of the gases
of the furnace which surrounds them; the retorts are provided with suitable covers
such as are used on gas retorts. The vapour produced in the retorts is drawn off
by a steam jet or other suitable exhausting and forcing apparatus and delivered,
mingled with the air, into a chamber which I call the combustion chamber, the
result of the mixture is that combustion takes place, the oxygen of the air
oxidizing the sulphur, and the lead converts the same into sulphite of lead; these
actions may take place at the upper part of the combustion chamber whilst at
the bottom part the fuming nitric acid above specified is mixed with these gases.
The effect of the nitric acid in conjunction with the air supplied to the combustion
chamber and the steam, is that the sulphite is in turn oxidized and converted into
sulphate.
This last mentioned action may be adapted to take place in a suitable passage
of or connected with the combustion chamber, of suitable length to cause the
sulphite of lead to be entirely converted to the sulphate by the action and
reaction of the air and steam, such actions and reactions being the same as those
which take place in the "leaden chamber" when sulphuric acid is being formed
in the usual way. The sulphate of lead may be removed from the apparatus
through a water seal under which a rake may be passed to effect the withdrawal,
thus the sulphate is removed as soon as it is formed and without making any
opening in the apparatus. The waste gases consisting of nitric acid, steam, and
nitrogen are passed through a condenser and are caused to pass through such
condenser by a jet or other exhauster, and are delivered into a hydraulic main
through dip pipes. The nitric acid coming from the hydraulic main will be
recovered in the usual way now practised in sulphuric acid making and used over
again. When nearly all the sulphide of lead is vapourized in the retorts the
residuum is removed through suitable doorways therein, this residuum will contain
all the foreign substances in the gallena which in some cases will be zinc, tin,
copper, silver, and in rare cases gold and any of these valuable metals can be
recovered by after treatment.
As regards the production of nitric acid fumes, this may be done by using
nitrate of soda and allowing sulphuric acid to gradually fall onto it; such mixture

page_text: to take place in a suitable boat or other shaped porcelain vessel.
Any suitable
known forms of vessel and apparatus for supplying sulphuric acid may be used, as
in the ordinary "leaden chamber."
The retorts are charged and discharged alternately, by this means a continuous
charge of vapour mingled with air and steam is always undergoing combustion in
the combustion chamber, and the further conversion above referred to is going on
continuously within the chamber or passage before specified.
The production of sulphate of lead is thus a continuous process and may be
carried on night and day without intermission, whilst the sulphate on being dried
becomes a valuable commercial pigment known as "improved white lead."
It is to be understood that the particular forms and construction of parts above
specified may be varied as may be desirable or found expedient.
Dated this 11th day of October 1890.
CHEESBROUGH & ROYSTON,
15, Water Street, Liverpool, Applicant's Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Processes for the Manufacture of Sulphate of Lead
and Apparatus therefor.
I, HENRY CLAY BULL, of 12, Trafalgar Road, Old Kent Road, London, S.E.,
Engineer, 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 :-
This invention has mainly for its object to produce sulphate of lead direct from
the ore sulphide of lead or galena.
According to this invention, the galena is first volatilized or vapourized by heat
and the vapour from the galena is mixed with air, or air and steam, and burnt,
thereby producing sulphite of lead. Subsequently it is mixed with nitric acid
fumes produced as hereinafter described. The air or air and steam is or are
supplied in excess to that required to burn the galena vapour, and it or they
together with the nitric acid fumes and steam is or are used to further oxidize the
sulphite of lead and convert it to sulphate. The sulphate is collected and the bye-
products treated and recovered as hereinafter described.
The apparatus used and the mode of conducting the process are as follows :-
A Siemens or like regenerative gas furnace is used and serves to heat the com-
bustion chamber having within it a plurality of retorts, in these retorts charges of
galena broken. into suitable sized pieces (say about two inch cubes) are volatilized
by the heat of the gases of the furnace which surrounds them, the retorts are
provided with suitable covers such as are used on gas retorts.
The vapour
produced in the retorts is drawn off by a steam jet or other suitable exhausting
and forcing apparatus and delivered, mingled with air, into a chamber which I
call the combustion chamber. The result of the mixture is that combustion takes
place, the oxygen of the air oxidizing the sulphur and the lead, converts the same
into sulphite of lead. These actions may take place at the upper part of the
combustion chamber, whilst at the bottom part the fumming nitric acid above
specified is mixed with these gases. The effect of the nitric acid in conjunction
with the air supplied to the combustion chamber, and the steam, is, that the sulphite
is in turn oxidized and converted into sulphate.
This last mentioned action may be adapted to take place in a suitable passage
on or connected with the combustion chamber and of suitable length to cause the
sulphite of lead to be entirely converted to the sulphate by the action and reaction
of the air and steam, such actions and reactions being the same as those which
take place in the "leaden chamber when sulphuric acid is being formed in the
nsual way. The sulphate of lead may be removed from the apparatus through a

page_text: water seal under which a rake may be passed to effect the withdrawal, thus the
sulphate is removed as soon as it is formed and without making any opening in
the apparatus. The waste gases consisting of nitric acid, steam and nitrogen are
passed through a condenser and are caused to pass through such condenser by a
jet or other exhauster and are delivered into a hydraulic main through dip pipes.
The nitric acid coming from the hydraulic main will be recovered in the usual
way now practiced in sulphuric acid making, and used over again. When nearly
all the sulphite of lead is vapourized in the retorts, the residuum is removed
through suitable doorways therein; this residuum will contain all the foreign
substances in the galena which in some cases will be zinc, tin, copper, silver,
and, in rare cases, gold, and all these valuable metals can be recovered by after
treatment.
As regards the production of nitric acid fumes, this may be done by using
nitrate of soda and allowing sulphuric acid to gradually fall onto it, such mixture
to take place in a suitable boat or other shaped porcelain vessel. Any suitable
known forms of vessel and apparatus for supplying sulphuric acid may be used, as
in the ordinary "leaden chamber."
The retorts are charged and discharged alternately; by this means a continuous
charge of vapour mingled with air and steam is always undergoing combustion
in the combustion chamber and the further conversion above referred to is going
on continually within the chamber or passage before specified.
The production of sulphate of lead is thus a continuous process and may be
carried on night and day without intermission whilst the sulphate on being dried
becomes the valuable commercial pigment known as "improved white lead.'
It is to be understood that the particular forms and constructions of parts
herein specified may be varied as may be desirable or found expedient.
Apparatus of the kind above mentioned are illustrated in the accompanying
drawings which constitute kinds of apparatus by which the invention may be
carried into effect, but the invention is in no way confined to these forms of
apparatus. In the figures of these drawings the same letters and figures of reference
are used to denote the same or like parts wherever they occur.
Figure 1 is a sectional elevation of one form of the apparatus.
Figure 2 is a plan of same; and
Figure 3 is a sectional longitudinal elevation of the retorts and their chamber
whereby the galena is vaporized.
Figure 4 is a sectional elevation of an alternative arrangement of the apparatus
shown in Figure 1.
Figure 5 is a plan, partly in section, of the apparatus shewn in Figure 4.
Figure 6 is a sectional elevation of an arrangement of parts for supplying
sulphuric acid and containing the nitrate of soda, and forming the water seal.
The
With reference to the drawings, A are the galena distilling retorts set in a
chamber A' whereinto heated air and gas are introduced and burned, and heat
externally the galena retorts A. A² are air and gas generators of the well known
Siemen's regenerative type, and therefore need no further description.
retorts A have upper and lower doors a and a' respectively, by which they may be
charged with galena and discharged of the residuum resulting after the vaporization
of the galena.
B is the chamber-which I call the combustion chamber-into which the
volatilized or vaporized galena is introduced. C are the pipes by which the
vaporous galena is conveyed to said chamber. D are steam pipes connected to a
main D by which steam is delivered into the chamber B, and D2 are coned
nozzles around the delivery ends of the steam pipes D through which air is drawn
in and forced into the chamber B by the action of the steam jets.
E is a boat shaped porcelain vessel in which nitrate of soda is held, and
El represents a device or pipe by which sulphuric acid is allowed to drip into the
vessel E. Any of the well known forms of vessel and means for supplying the

page_text: sulphuric acid that are used in the manufacture of sulphuric acid in the ordinary.
'leaden chamber" will serve for this purpose. B is a continuation of the
chamber B, wherein the production of sulphate of lead goes on or is completed.
Fis a water seal trough at the end of the chamber or passage B', and F is a.
plate dipping into the water therein and making the seal.
H is a condenser connected with the passage or chamber 13 through which the
waste gases consisting mainly of steam, nitric acid, and nitrogen, are passed.. 1. is
a hydraulic main into which the pipe 1', which conveys the uncondensed gases
passing away from the condenser H, dips. This hydraulic main I is maintained
at a pressure below that of the atmosphere, whereby the gases are caused to pass
through the condenser. The condenser may be of a well known kind in which
blocks of material are employed and water allowed to trickle down over them.
In operation, the retorts A are alternately charged with galena so as to produce
a continuous flow of vapour, the galena being vaporized by the heat of combustion
of the hot air and gas supplied to the chamber A from the regenerator A². These
vapours are caused to pass by the pipes C into the chamber B (which is common
to all the retorts A) by the action of the steam jets supplied through the steam
pipes D, and combustion resulting from the admixture of air introduced by the
stenm jet, the steam, and the volatilized or vaporous galena (sulphide of lead)
taking place, resulting in the conversion of the sulphide into sulphite of lead.
Then, at the lower part of the chamber B, the gases become mixed with the fuming.
nitric acid produced from the sulphuric acid and nitrate of soda from the vessel E,
the effect of which is that the sulphite is converted into sulphate of lead as it
passes along the passage or chamber B. The sulphate is removed from the
passage B' through the water seal F by a rake which is passed under the
plate F; and this may be done as soon as it is formed and without making any
opening in the apparatus.
The nitric acid which is recovered in the hydraulic main will be recovered in
the usual way practised in sulphuric acid making, and used over again.
The arrangement shewn in Figures 4, 5 and 6 is a slight modification of that.
shewn in Figures 1 and 2, that is to say, the condenser H is of duplex form, as
shewn, and nitrate of soda burners E are disposed at the lower part of both
portions of the condenser H. By this arrangement, any unconverted sulphite in
the second portion of the condenser H is converted to sulphate of lead with the
fuming nitric acid produced in the vessel E at the bottom of same, before it passes
into the main I by the pipe 1. The conduit B in this case serves as the com-
bustion chamber, steam or steam and air being introduced into it by the steam
pipe D in an equivalent manner to that set forth with reference to Figures 1
and 2 of the drawings, so that the combustion commences at the end of the
conduit Bat which the air and steam are introduced, and is continued along the
conduit until the sulphide from A is converted to sulphite of lead.
In other respects than these, with reference to Figures 4, 5, and 6, the modifi-
cation shewn therein does not differ in any substantial respect from that set forth
with reference to Figures 1, 2, and 3.
By this process the sulphide of lead can be charged into the retorts A, and its
volatilization can be regulated to any degree required, and it does not require
continuous watching or careful watching, which is not the case with other direct
or similar processes; and moreover the lead will be pure, as it is volatilized, out
of contact with the fuel. The amount of the fuel also will be relatively small for
the volatilization of the galena.
The formation of the sulphate by the action of the nitric acid used will be very
rapid.
It is to be understood that this invention herein described may be employed as
a whole, or it may be employed in part in connection with other processes of
making sulphate of lead or white lead, differing from the complete process herein
set forth.

page_text: Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improvements in the manufacture of sulphate of lead, whereby the
sulphide of lead (galena) is volatilized and burned and converted to sulphate of
lead substantially as herein described.
2. In processes for producing sulphate of lead, wherein the material, prior to
its being converted to sulphate, is in a volatilized or vaporous state, the employ-
ment of and admixture with such vapours or gases, of nitric acid fumes: for the
purposes set forth.
3. The particular mode of producing sulphate of lead direct from sulphide of
lead (galena) herein set forth with reference to the drawings.
4. In the apparatus herein shewn and described, the galena retorts A, the
chamber B and passage or chamber B¹, and their respective parts connected with
them, constructed or arranged and adapted to operate substantially as described
and illustrated for the purposes specified.
Dated this 11th day of July 1891
CHEESBROUGH & ROYSTON,
15, Water Street, Liverpool, Applicant's Patent Agents.