Improvements in the Reduction of Zinc and Tin from their Ores.......
Year: 1889

page_text: Date of Application, 14th-Jan.; 1889
Complete Specification Left; 12th July, 1889-Accepted, 17th-Aug., 1889
PROVISIONAL SPECIFICATION:
Improvements in the Reduction of Zinc and Tin from their Ores…….
I CHARLES ANTHONY BURGHARDT of 35 Fountain Street; in the City of Manchester
County of Lancaster, Analytical Chemist, do hereby declare the nature of this'
Invention to be as follows:-
My said Invention relates to the reduction of zinc and tin from their ores by an
improved method which enables me to obtain these metals expeditiously and in a
state of great purity. In carrying my invention into effect I add to the roasted zinc
or tin ore that is to say, to the oxides thus, formed a suitable quantity of carbonaceous
matter such for example as powdered coal or charcoal. The quantity. of the said
carbonaceous addition will vary according to the nature of the ore but, I. consider that
in most cases a suitable proportion would be from 10 to 25 per cent. of 'carbon by
weight. I then place a quantity of caustic soda or potash in a suitable vessel and
melt the soda or potashi, thereafter adding the mixture of roasted ore or 'oxides,
whether of zinc or of tin, and carbon and subject the vessel and its contents to
heat: The gases driven off by.this process are chiefly carbon monoxide and carbon
di-oxide the former of which ignites and burns as it comes to the surface. The heating.
process may be discontinued when these gases cease to be given off. If the tin ore
should prove to be free from arsenic, antimony or sulphur the roasting may. be
dispensed with and the ore simply crushed and mixed with its due proportion of
carbonaceous matter, before being, placed in the melted caustic soda or potash. In
the process of melting the oxide of zinc or the oxide of tin is reiluced momentarily to
the inetallic state but the metal thus formed is at once dissolved in the melted caustic
soda or potash, forming, in the case of zinc ores, sodium zincate and in the case. of
tin ores as far as I have at present ascertained stannate of sodium, or in any case the"
tin is combined with the melted soda or potash. The contents of the vessel are thien
allowed to cool and the solid mass so formed is broken up and dissolved in a suitable
proportion of water. This solution is placed in a bath provided with the necessary
anodes and cathodes and is subjected to an electric current of the requisite density,
generated by a dynamo-electric machine or battery. The zinc or tin present in the solu-
tion is thus thrown down or, deposited in a state of absolute purity and may therefore be
removed. The requisite addition of carbon may be made by stirring or agitating the
mixture of melted soda or potash and ore or oxide with poles, stirers or agitaters inade
of a material that will give off carbon when subjected to the heat of the mixture such
for example as wooden poles or the like. By means of my invention I can utilise
ores containing large percentages of copper, iron, manganese and other constituents as
these become separated in the bath by the electric current and being insoluble aro
precipitated as oxides.
The aforesaid addition of carbon to the mixture of the ore or melted soda or potash
might be used to expedite the production of zinc according to an invention for which
I have made application for Her Majesty's Letters Patent on the 12th day of
September 1888 No. 13182..
Dated this 10th day of Januar- 1000
DUTTON & FULTON,
1, St. James Square, Manchester, Agents:

page_text: COMPLETE SPECIFICATION.
Improvements in the Reduction of 'Zinc and Tin from their Ores.
I CHARLES ANTHONY BURGHARDT of 35 Fountain Street, in the City of Manchester,
County of Lancaster, Analytical 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, that is to say :-
11.
My said invention relates to the reduction of zinc and tin from their ores by an
improved method which enables me to obtain these metals expeditiously and in a state
of great purity. In carrying my invention into effect I grind crush or disintegrate the
roasted zinc or tin, ore so as to reduce it to a powder and I add thereto a suitable
quantity of carbonaceous matter such for example as powdered coal or 'charcoal: "The
quantity of the said 'carbonaceous matter added would vary according to the nature
or quality of the ore but I consider that' in most cases a suitable proportion would be
about three to seven per cent. 'of' carbon by weight that is to say I should add about
5 pounds of powdered charcoal or other suitable carbonaceous" matter to each
100 pounds of the ore powder., I fuse a quantity of caustic soda 'or potash in a heated
pot or vessel without the addition of water and I'add to the fused caustic alkali the
mixture of ore and carbon. In practice I have obtained good results by the employ-
ment of caustic alkali in the proportion of a little over twice the weight of the metal
actually present in the ore. I thoroughly mix the contents of the pot keeping up the
heat with agitation or stirring of the said contents until the 'ore has become dissolved
by or, entered into chemical combination with the caustic alkali. The gases driven off
by this process are chiefly carbon monoxide and carbon dioxide. I increase the heat
until the carbon monoxide ignites and 'burns as it comes to the 'surface. The heating
process may be discontinued when these gases cease to be given off. If the tin oro
should prove to be free from arsenic antimony or "sulphur the" roasting may be
dispensed with and the ore be simply crushed and mixed with its due proportion of
carbonaceous matter before being placed in the fused caustic soda or potash. In place of
adding powdered carbonaceous' matter to the ore such matter might be mixed with the
fused caustic alkali before the addition thereto of the ore powder or the addition of
carbon may be made by stirring or agitating the mixture of melted soda or potash
and ore or oxide with poles, stirrers or agitators made of a material that will give off
carbon when subjected to the heat of the mixture as for 'example wooden poles might
be used for the purpose. In the process of melting, the oxide of zinc or the oxide of
tin is reduced momentarily to the metallic state but the metal thus formed is at once
dissolved in the melted caustic soda or potash, forming in the 'case of zinc ores when
caustic soda is used sodium zincate and in the case of tin ores stannate of sodium: - In the
cases of roasted ores containing, bismuth or lead I add a sufficient quantity of sulphur
to convert the oxide, into a sulphide of bismuth or lead as the case may be. In the
cases of ores of tin containing antimony of arsenic I add a proportion of grain tin to
the contents of the pot. The nascent hydrogen liberated by the re-action between the
caustic alkali and the tin combines with the antimony or arsenic and is driven off-as
antimonated or arseniated hydrogen as the case may be. The combination of the ore
and the caustic alkali having taken place the contents of the vessel are poured or
raked out to cool and the resulting mass or slab is broken up and dissolvedor
lixiviated in a suitable proportion of water. This solution I use as a bathi' from which
the zinc or tin is obtained by electro deposition. The process' for the electro deposition
of the metal may be conducted in accordance with the specification of a former
Invention for which I have made application for Letters Patent number 13182 of the
year 1888 the solution, obtained as aforesaid being used as a bath and the pure metal
being deposited upon suitable cathodes or the operation for the electro deposition of
the pure metal from the solution so obtained may be conducted in any suitable
manner. In the recovery of zinc a part of the reduced metal is thrown down as a
powder which does not adhere to the cathode but this powder can be readily converted
into melted zine by compressing the powder into blocks and entirely immersing such
1

page_text: blocks in melted zinc. I have found it most convenient to apply catch trays or
troughs below the cathodes to receive the zinc deposit in order to keep it separate
from the foreign matters which become precipitated at the bottom of the cistern. By
means of my invention I can utilise ores containing large percentages of copper,
iron, manganese, lead, bismuth and other constituents as some of these become
separated in the bath by the action of the caustic alkali and being insoluble are
precipitated as oxides and others may be eliminated in the manner hereinbefore set
forth. After the metal has been obtained from the solution I run off the latter and
concentrate it to obtain the caustic alkali which I use in the treatment of a further
quantity of ore. As the solution will contain some sodium or potassium silicate due
to the action of the caustic alkali upon the silica in the ore it is advisable to remove
such silicate. This removal I effect by boiling the solution with a proportion of lime
before concentration. This treatment also has the effect of converting any free
carbonate of sodium or potassium which may have been formed into caustic alkali.
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 :-
(1) The process for the reduction of zinc or tin from its ore and for the obtainment
of the metal in a state of purity substantially as set forth.
(2) The process for the recovery of zinc or tin from its ores consisting in the
heating of the crushed or powdered ore in admixture with fused caustic soda or
potash in company with carbon or carbonaceous matter until a chemical combination
has resulted, the lixiviation of the resultant and the using of the obtained solution as
a bath from which the pure metal is obtained by electro deposition substantially as
set forth.
(3) In the reduction of zinc or tin from its ores adding carbon or carbonaceous matter
to the crushed ground or powdered roasted ore adding the mixture to fused caustic
soda or potash, heating the mixture until a chemical combination of zinc or tin and
sodium or potassium is obtained, lixiviating the resultant and using the solution as a
bath from which the pure metal is obtained by electro deposition substantially as set
forth.
Dated this 10th day of July 1889
DUTTON & FULTON,
1, St. James Square, Manchester, Agents.