IMPROVEMENTS IN TREATING. CERTAIN ORES AND, ALLOYS, AND IN OBTAINING PRODUCTS THEREPROM
Year: 1854

page_text: LETTERS PATENT to William Henderson, of Cannon Street, in the City
of London, Manufacturing Chemist, for the Invention of "IMPROVEMENTS
IN TREATING. CERTAIN ORES AND, ALLOYS, AND IN OBTAINING PRODUCTS
THEREPROM."
Scaled the 3rd: April 1855; and dated the 25th October 1854..
PROVISIONAL SPECIFICATION left by the said William Henderson at
the Office of the Commissioners of Patents, with: his Petition, on the
25th October 1854.
I, WILLIAM HENDERSON, of Cannon: Street, in the City of London,
Manufacturing Chemist, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN TREATING CERTAIN. ORES AND ALLOYS, AND, IN OBTAINING
PRODUCTS THEBEPROM,'' to be as follows:-
These improvements refer to the more economical and certain separation of
the several metals contained in what are commonly called mixed ores, that is
to say, ores containing several metals, the separation and realization of cach or
all being desirable; also to the alloys of several metals, obtained sometimes. as
by-products, in the reduction, by methods: now in use, of copper, lead, tin, and
several other metals; and also to the separation of gold and silver, when they
occur as an alloy with copper, either as native copper, any of the ores of copper.
or in any of its stages of manufacture or finished state..

page_text: These improvements also refer to the special treatment of ores containing a
large proportion of zinc, arsenic, or other volatile metal, so as to obtain the
zinc with the other metal associated in the ore; and consist of,-
First, a means of separating silver and gold from copper and other ores
when they contain very little or no arsenic, zinc, or other volatile metal, by
first calcining the ore (if a sulphuret) in the usual or any other manner till it
is as free from sulphur as is practicable, and then adding to the calcined ore as
much silica, sand, "cobbing," or stiff ore (all free from sulphur and carbona-
ceous matter) as will be sufficient to form proto-silicates of all the oxides of
the metals and earths contained in the calcined ore or ores; I also add before
fusion a few pounds of nitrate of soda, peroxide of manganese, or other
oxidizing agent to every ton of the calcined ore. The charge of mixed ores is
then smelted in a common reverberatory furnace, by being brought to the
melting point gradually with a partially open fire. If the ores have been
absolutely free from sulphur, the result will be gold or silver at the bottom of
the furnace, and all the other metals as a slag or scoria on the top, which slag
is skimmed or tapped from the furnace. As sulphur is generally present,
however, the result will then be a small proportion of regulus containing all
the precious metals. This may be calcined and treated as before described,
and about 10 pounds of lead added for every estimated pound of precious
metals, the whole charge well stirred and allowed to settle, the slag skimmed
off, and the lead tapped into a pot, ladled into moulds, and refined in the usual
manner. Reguluses of copper or other metal containing gold or silver, or
both, are treated in the same way; carbonates or oxides of copper or other
ore require no calcination, but are mixed with silica, &c., and smelted at once.
Metallic copper, either as native rough, or finished copper, may be treated
two ways; either converted into a regulus, by melting with a sulphurct or
sulphur and iron, crushed, calcined, mixed with silica, &c., and otherwise treated
as above; or the copper may be melted and ladled into water, the shots
mixed with silica and oxidizing agent, placed in a reverberatory furnace, and
gradually brought to the melting point. The copper or other metal is after-
wards obtained from the slag by melting with a suitable flux and carbonaceous
matter, or as refinery slags are usually reduced in the ordinary process of
copper smelting.
Second, several methods of preparing the ores or alloys containing arsenic
or other volatile metal, so as to induce the partial or complete formation of
sulphates.
Third, a peculiar method of calcining the prepared ores and alloys with a
variable proportion of alkaline chlorides, and in some cases with a mixture of

page_text: chlorides and nitrates, or other oxidizing agent, so as to obtain a mixture'
containing all the valuable metals, even gold and silver, in a state so as to give
a clear solution in water, free from iron, and at the same time secure, if
necessary, the volatile chlorides free from smoke, by condensing with water
or steam.
Fourth, an improved means of separating the dissolved metals, by making
use of one precipitate to obtain another, such as the moist oxide or carbonate
of zinc to precipitate copper, silver, gold, &c.
Fifth, a means of separating from each other the deposited oxides of
arsenic and zinc, obtained as a by-product in the manufacture of sulphuric
acid, from mundics, copper, zinc, and other ores, and also in the calcination of.
these ores generally, by converting them into sulphates, if not already in that
state, and afterwards thoroughly drying them, and mixing with an alkaline
chloride, calcining the mixture in my patent furnace; the results being volatile
chloride of arsenic, which passes off and is condensed, and the chloride of
zinc and sulphate of alkali, which remain in the furnace, and are afterwards
separated by solution in water and crystallization or precipitation. This process
also applies to several alloys.
.
Sixth, the manufacture of chloride and oxide or carbonate of zinc, as above
described
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Henderson in the Great Seal Patent Office on the
25th April 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENDERSON, of Cannon Street, in the City of London, Manufacturing Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of October, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Henderson, Her special licence that I, the said William
Henderson, my executors, administrators, and assigns, or such others as I, the
said William Henderson, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,

page_text: the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN TREATING CERTAIN ORES AND ALLOYS, AND IN OBTAINING PRODUCTS THERE-
FROM," upon the condition (amongst others) that I, the said William
Henderson, by an instrument in writing under my hand and seal, -should
particularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months.next.and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Henderson, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
My improvements refer to the more economical and certain separation of
the several metals contained in what are commonly called mixed ores, that is
to say, ores containing several metals, the separation and realization of cach
or all being desirable; also to the treatment of the alloys of several metals,
obtained sometimes as by-products, in the manufacture or reduction, by
methods now in use, of copper, lead, tin, and several other metals; and also
to the separation of gold and silver, when they occur as an alloy with copper,
either as native copper, or any of the ores of copper, or in any of its stages of
manufacture or its finished state. My improvements also refer to the special
treatment of ores containing a large proportion of zinc, arsenic, or other
volatile metal, so as to obtain the zinc with the other metal or metals
associated in the ore.
My first improvement consists in a method of separating silver and gold
from copper and other ores when they contain very little or no arsenic, zinc,
or other volatile metal. I first calcine the ore in the usual or any other con-
venient manner until it is as free as is practicable from sulphur, and then ackl
to the calcined ore as much sand, silica, cobbing, or stiff ore (all free from
sulphur and carbonaceous matter) as will be required to form proto-silicates
of all the oxides of metals and earths contained in the calcined ore; I also add
before fusion from about 10 lbs. to 1.5 lbs. of nitrate of soda, or a proportionate
quantity of peroxide of manganese, or other oxidizing agent, to every ton of
the calcined ore. The charge of mixed ores and other matters is then smelted
In a common reverberatory furnace, in which it is gradually brought to the
melting point with a partially open fire. If the ore has been absolutely freed
from sulphur, the result will be gold or silver at the bottom of the furnace,
and all the other metals as a slag or scoria, which is skimmed or tapped from
tre furnace. A sulphur, however, is generally present, the result will then be

page_text: manner.
a small proportion of regulus containing all the precious metals. This may
be calcined and treated as before described, and about 10 lbs. of lead added
for every estimated pound of the precious metals, the whole charge well stirred
and allowed to settle, the slag skimmed off, and the lead tapped into a pot,
ladled out into moulds, and refined in the usual manner. Reguluses of copper
or other metal containing silver or gold, or both, are treated in the same
Carbonates or oxides of copper or other ore require no calcination,
but are mixed with silica, &c. as above directed, and smelted at once. Metallic
copper, either native, rough, or finished, may be treated in two ways; either
melted with a sulphuret or sulphur and iron, so as to convert it into a rich
regulus, which is crushed, calcined, mixed with silica, and otherwise treated as
above mentioned; or the copper may be melted and ladled into water, the
shots mixed with silica, and an oxidizing agent, as above directed, and gra-
dually brought to the melting point in a reverberatory furnace. The copper:
or other metal is afterwards obtained from the slag thus produced by melting
with a suitable flux, such as lime, fluor spar, or soda ash, and carbonaceous
matter, or in the same manner as refinery slags are usually reduced in the
ordinary process of copper smelting.
My second improvement relates to the treatment of ores containing a pro-
portion of zinc or arsenic of sufficient amount to be considered worth saving,
besides another metal or metals." In this case I proceed as follows:-I'
ascertain by analysis the composition of the ore, and if I find that it contains
a large proportion of sulphur I calcine it in the furnace, and in the manner
particularly described in the Specification of a Patent granted to me the 14th
day of July 1853, using a low heat, and withdrawing the ore from the'
furnace when the proportion of sulphur is reduced as nearly as possible to.
half the amount of all the metals contained in the ore, reckoning all except'
iron. When the ore is removed from the furnace it is thoroughly moistened.
with water, and well exposed to the air for a few days; it is then ground'
fine enough to pass through a sieve of at least 100 meshes to the square inch,
and is afterwards treated as will be presently described. When an ore of this
class is found to contain without preparation the proportion of sulphur indi-
cated above, it is at once reduced to powder without the previous calcination,
but when it is found to contain less than the requisite amount of sulphur,
sulphur must be added. This can be done by admixture with an ore richer
in sulphur, or by adding iron pyrites, or, preferably, by adding sulphuric acid to
the powdered ore. The ores prepared by any of the above methods are first
thoroughly dried and mixed intimately with a proportion of alkaline chloride,
preferably common salt, and when the ore has not been previously calcined, or

page_text: had sulphuric acid or a sulphate added to it, a proportion of nitrate of soda,
equal to 10 per cent. of the contained sulphur, must be added to the mixture.
Peroxide of iron, peroxide of manganese, and several other oxidizing agents,
if added in proportion, may be used, instead of the nitrate of soda, but I prefer
the latter. In all cases, however, where gold exists in the ore, the addition of
nitrate of soda is recommended. The proportion of alkaline chloride is very
variable, depending entirely upon the preponderance of any particular metal in
the ore. When a large quantity of lead exists in the ore, the proportion of
chloride necessary decreases. As a general rule I find a proportion varying
from 3 to 4 times the amount of sulphur in the ore to work very well, an
excess being preferable to a deficiency. When the mixture has been adjusted
as above described a charge of about 5 tons is placed upon the third bed of
the patent furnace, described in the Specification before mentioned, and calcined
as there directed. The mixture must be carefully and incessantly stirred,
especially on the bottom bed; from 12 to 18 hours on cach bed will, if
properly managed, be sufficient to decompose the ore. The result of the cal-
cination is as follows:-Arsenic and iron with a few other metals of rarer
occurrence pass off as chlorides in vapor, and, if necessary or desirable, may
be condensed by water or steam. All the other metals with the silica and
some oxide of iron remain in the furnace as chlorides and sulphates. The
calcination must be continued until all the iron and arsenic salts are either
decomposed or sublimed; when this has been accomplished, the ore is removed
from the furnace, and while still hot is put into a deep tank of boiling water.
The solution thus obtained is treated while hot with moist carbonate or oxide
of zinc, and well agitated; the carbonate or oxide of zinc is added until no
precipitate falls; the vessel is then covered over and allowed to settle, and the
clear liquor, which contains chlorides of zinc and alkali and sulphate of
alkali, is run into coolers, and the alkaline salts crystallised out, leaving the
chloride of zinc nearly pure as the mother liquor. The chloride of zinc may
be further purified by concentration, when any remaining alkaline salts will
drop to the bottom of the evaporator, as anhydrous crystals. Pure carbonate
or oxide of zinc may be obtained from the chloride by precipitating with
carbonate or hydrate of lime, or carbonate or hydrate of any of the earths or
alkalies. The insoluble matter left in the bottom of the vessel into which the
decomposed ore is put, consists of silica and oxide of iron, and if lead exists
in the ore, a proportion of sulphate of lead, which; if found in suflicient
quantity to warrant the expense, is calcined with a little carbonacous matter,
and smelted for lead in the usual manner. The precipitate produced by the
addition of the carbonate or oxide of zinc to the original solution may contain

page_text: copper, lead, silver, gold, and several other metals of rare occurrence. These
metals may be separated by several methods. That which I prefer is to
gradually raise the mixture to a low red heat in a small furnace, with constant
stirring, and then dissolve in sulphuric acid, of about 1.35 specific gravity, in
a vessel lined with lead and heated. by steam. The copper only is dissolved
and oxide of lead and a little sulphate of lead and metallic silver and gold
are left as a residue; this is smelted with carbonaceous matter, and about
20 lbs. of soda ash to the ton of mixture. The lead obtained is cupelled in
the usual manner.
When the ore to be treated does not contain sufficient
zinc or arsenic, but, on the other hand, contains a large proportion of silica
and iron, I calcine it for a few hours, and then smelt for regulus as is
usually done with copper ores. The regulus obtained is treated exactly as has
been described.
My third improvement consists in a means of separting from each other
the deposited oxides of arsenic and zinc, obtained as a by-product, in the
manufacture of sulphuric acid, from mundics and copper and zinc ores, and in
the calcination of such ores generally. I first convert the mixed oxides into
sulphates (if not already in that state), by means of sulphuric acid, and after-
wards carefully dry them, and mix with about twice their weight of common
salt or other alkaline chloride, and calcine them in the furnace and manner
already described, taking care that a low red heat is never exceeded. The
products are volatile chloride of arsenic, which passes off and is condensed,
and soluble chloride of zinc and sulphate of alkali, which remain in the
furnace, and are afterwards separated by solution and crystallization, as already
described. The oxides of arsenic and zinc can be obtained in great purity
from these solutions by precipitating with lime or alkali. This process is
also applicable to several alloys and mixtures of the oxides or salts of several
metals, such as tin and copper, lead and tin, and lead or copper and anti-
mony; the tin and antimony being volatilized as chlorides, while the copper
and lead as chlorides, with the sulphate of alkali, remain in the furnace.
Having now described the nature of my Invention, and the manner in
which the same is to be performed, I declare that I do not confine myself to
the precise details herein described, provided the peculiar character of any
part of my Invention is retained; but what I claim is,-
First, the separation of the precious metals, such as gold, silver, and
platinum, when one or more of them occur in the ores, reguluses, or alloys of
other metals, by converting the associated metals into oxides by the several
methods described, if such metals do not already exist in that state; and after-
wards by fusion with silica or matters containing silica, converting these metals

page_text: into silicates, whilst the precious metals, being reduced by heat alone, are
separated from the scoria or slag in a nearly pure state.
Second, the preparation of the ores of zinc and other volatile metals when
they contain an excess or deficiency of sulphur, as described..
Third, the use of a mixture of chlorides and nitrates of alkali, or other
oxidizing agents, for the purpose of decomposing ores in the process of
calcination.
Fourth, the means described for separating and obtaining arsenic, antimony,
tin, and several other metals, or the oxides or salts of arsenic, antimony, tin,
and several other metals, from zinc, copper, lead, silver, gold, and other metals
whose chlorides are not volatile at a low red heat..
And, fifth, the manufacture of chloride, oxide, or carbonate of zinc in the
manner described:
In witness whereof, I, the said William Henderson, have hereunto set
my hand and seal, this Twentieth day of April,. One thousand eight
hundred and fifty-five.