Year: 1899

page_text: Date of Application, 17th Apr., 1899
Complete Specification Left, 16th Jan., 1900-Accepted, 24th Feb., 1900
I, GUY DE BECHI, of 17, Boulevard de la Madeleine, Paris, in the Republic of
France, Chemical Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to the treatment of complex ores containing tin and
other metals.
.
Ores of this kind containing for instance tin, silver, iron and antimony, cannot
be treated in the ordinary.or dry way to recover the metals therefrom, by reason
of the compounds of the different metals inter-re-acting and so rendering the
treatment. inefficient, or necessitating very prolonged and expensive treatment.
Now the object of my invention is to economically separate the metals of com-
plex tin ores, the metals being recovered in the form of valuable compounds which
are capable of being readily reduced.
According to my invention, when applying the same for example to an ore con-
taining lead, silver, iron, tin, gold and antimony all in the form of sulphides
(which are practically insoluble in the commonly employed solvents), I convert
the ore into a condition convenient for the further treatment by subjecting it to
an oxidising roasting either alone or admixed with pyrites, common salt, or both,
according to the composition of the ore. During the roasting the greater portion
of the antimony is driven off in the form of fumes of antimonious oxide or chlor-
ide, and can be collected in suitable towers. I may also recover from the fumes
given off in the roasting, sulphuric acid, or hydrochloric acid or both, to be
utilized in subsequent steps of my process.
The roasted ore contains lead in the forms of sulphates and oxides, a small
quantity of antimonious oxide, and tin in the form of stannic acid. The tin can
therefore be readily separated since the oxides of lead and of antimony are basic
oxides while the compound of 'tin is acid
The roasted ore is heated with a quantity of hydrochloric acid (which may be
that recovered from the fumes given off by the ore and salt during the roasting)
to dissolve the antimony. The residue of this leaching is treated with a caustic
soda with which the stannic acid combines to form sodium stannate which is
soluble in water and can be separated.**
The residue now contains lead, silver, gold and the iron contained in, or added
in the form of pyrites to, the ore. This residue is treated in any well known
manner in a suitable smelting furnace and gives a lead bullion containing practi-
cally the whole of the lead, silver and gold.
"
The solution of sodium stannate can be treated in different ways. For example,
I may add to the heated solution sufficient milk of lime to form calcium stannate
and caustic soda. Or I may pass a current of carbonic anhydride through the
sodium stannate solution forming stannic hydrate and sodium carbonate. The
sodium carbonate is then treated with milk of lime to form caustic soda.
In this manner the soda can be used over and over again it being necessary to
add only a small quantity of fresh soda at each operation to replace the loss,

page_text: and caustic soda. Or I may pass a current of carbonic anhydride through the
sodium stannate solution forming stannic hydrate and sodium carbonate.
sodium carbonate is then treated with milk of lime to form caustic soda.
The
In this manner the soda can be used over and over again it being necessary to
add only a small quantity of fresh soda at each operation to replace the loss,
which does not amount to more than 10 per cent. or 15 per cent. of the quantity
required for converting the stannic acid into sodium stannate.
The calcium stannate or the stannic hydrate obtained in the process can be
converted into commercial salts of tin or reduced to metallic tin by any appropri-
ate method.
my
Having now particularly described and ascertained the nature of said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The method of treating complex tin ore which consists in subjecting said
ore to an oxidising roasting with or without sodium chloride and pyrites, leaching
the roasted ore with hydrochloric acid, treating the residue with caustic soda to
obtain sodium stannate solution, smelting the residue, and treating the sodium
stannate either with calcium hydrate or with carbonic anhydride, substantially
as and for the purpose specified.
2. The method of treating complex tin ore substantially as described for the
purpose specified.
Dated this 16th day of January 1900
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.