IMPROVEMENTS IN TREATING CERTAIN ORES, AND IN OBTAINING PRODUCTS THEREFROM
Year: 1859

page_text: LETTERS PATENT to William Henderson, of Alderley Edge, in the.
County of Chester, Chemist, for the Invention of "IMPROVEMENTS IN
Sealed the 29th September 1859, and dated the 8th April 1859.
PROVISIONAL SPECIFICATION left by the said William Henderson at
the Office of the Commissioners of Patents, with his Petition, on the
8th April 1859.
I, WILLIAM HENDERSON, of Alderley Edge, in the County of Chester,
Chemist, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN TREATING CERTAIN ORES, AND IN OBTAINING PRODUCTS THEREFROM," to be, as
follows:-
These improvements relate, first, to the treatment of zinc ores, or other ores
containing zinc; secondly, to the treatment of ores of antimony that contain
lead and other metals; thirdly, to the treatment of copper ores; fourthly, to
the treatment of ores or products containing cobalt; fifthly, to the treatment
of gold and silver ores and. auriferous quartz; and, lastly, to the dressing of
lead and other ores.
The first class of ores, viz. those containing zinc, I treat in the following
manner-If they contain sulphur they are first calcined in the usual or any
other manner, the sulphurets so calcined, or the carbonates, as the case may

page_text: be, are then roughly crushed to pass through a sieve of about eight holes to
the inch, & placed in vats with false bottoms similar to those described in the
Specification of Letters Patent granted to me, the 30th September, 1857,
No. 2517, & the ore is then covered with dilute muriatic acid of, say, 15°
Twaddle's bydrometer; the vats are worked exactly as described for copper
ores in the aforesaid Specification.
The orc must be treated with further quantities of acid until the whole of
the zinc has been extracted. The saturated solution thus obtained may be
treated with milk of lime at once, if it contain no other metal than zinc. If
the ore contains much lead, it is advisable to use very weak muriatic acid for
dissolving the zinc, & thereby most of the lead is left insoluble in the vats.
If the solution contains lead or copper, or both, they may be precipitated by
scrap iron or sulpuretted hydrogen, or the lead may be precipitated by
sulphuric acid as sulphate, and the zinc may then be precipitated as carbonate
by continuous boiling with carbonate of lime. The iron, after separation of
the zinc, is then precipitated by caustic lime as hydrated oxide of iron, which
may be used for purifying gas and, other purposes. The acid may be recovered
from the chlorido of calcium, as described in my before-mentioned Specifi-
cation. The oxide or carbonate of zinc thus obtained is reduced to the metallic
state in the usual manner.
The second class of ores, viz., the ores of antimony containing lead, silver,
copper, and other metals, I treat in the following manner:-When the ore is
a sulphuret I reduce it to fine powder, & mix it with a variable proportion of
common salt, also finely ground; the mixture is then calcined at a low heat in
retorts or a close calcining furnace, and the vapours condensed in close
chambers, or in a tower filled with coke or pebbles, with a small stream of
water trickling downwards. When the calcination has been properly con-
ducted, the whole of the antimony will have been sublimed as chloride of
antimony, and the lead, copper, silver, and several other metals will remain in
the furnace. When the ore contains no sulphur, the whole of the metal
should be converted into chlorides by muriatic acid, evaporated to dryness and
calcined; the antimony will be sublimed as chloride, as in the case of the
sulphurets, and the other metals will remain in the furnace. The antimony is
obtained from the chloride by precipitation.
The third class of ores referred to are specially the poor sulphuret ores of
copper, but ores of any degree of richness may be treated in the same way;
these ores are first calcined either in heaps, kilns, or furnaces, as may be most
convenient. The oro is then roughly crushed, placed in vats, treated with
muriatic acid, the copper precipitated with scrap iron or sulphuretted bydrogen,

page_text: and the whole of the dissolved iron are then precipitated with caustic lime as
bydrated oxide, and the acid, if desirable, may be afterwards produced from
the chloride of calcium solution, as described in the before-mentioned
Specification.
The treatment of ores or products containing cobalt consists in the sepa-
ration of cobalt from chlorides of iron liquors by evaporating them to dryness,
and decomposing the chlorides of iron by heat and steam from the residual
oxides of iron; the undecomposed chloride of cobalt may be dissolved out with
water, and so separated from iron, &c.
I treat gold ores in the following manner :-I divide them into two classes;
the first class consists of gold ores, properly so called, viz., iron and copper
pyrites and ores containing a large proportion of other metals, oxides, and
earths; and the second, of auriferous quartz, with small proportions of oxides,
earths, and other metals and ores of the first class containing zinc, arsenic, or
other metal that woul volatilizo in or during the process of smelting. The
ores of the first class, when calcined, should fuse easily by themselves, without
the addition of flux; if not, they belong to the second class.
!
The first class of ores I calcine sufficiently to form; when smelted with'
copper ore (if necessary), a regulus or matt of from 30 to 40 ° of copper, as
is well understood. About 56 lbs. of such regulus should be produced from
every ton of ore; when a charge of this regulus has been obtained I fuse it.
To the melted regulus I add a mixture of two parts anhydrous sulphate of
soda (salt cake) and one part of coal or other carbonaceous matter. When
the regulus is poor in gold, say, containing not more than 40 ounces gold per
ton, one cwt. of the above mixture may be added and thoroughly incorporated
with the melted regulus. The charge is then tapped into sand moulds, and
when set plunged into a tank or pan containing water, which will speedily
boil, the pigs of metal disintegrate, the sulphuret of sodium dissolves out, and
holds in solution the sulphuret of gold. To obtain the gold from this solution,
it is only necessary to neutralize the alkaline solution with an acid, and the.
sulphuret of gold is precipitated, collected, washed, and heated to redness, it
is reduced to metallic gold. The residual copper regulus may still contain a
trace of gold, but as it is used over again, or added to fresh copper ore, it is of
no consequence. Sulphuric acid should be used to neutralize the sulphuret
of sodium, as it can be evaporated to dryness, and the sulphate of soda
reproduced:
.
If silver exists in the ore it will remain with the copper regulus, and when,
by repeated operations, has become sufficiently rich, the regulus may be
calcined, and the iron, copper, &c., separated by sulphuric or muriatic acid.

page_text: The auriferous quartz and gold ores of the second class I treat as follows:-
If sulphur exists in the ore it must be calcined; before or after calcination it
should be reduced to fine powder; I prefer that the pulverisation of the ore
be effected without wetting it, when practicable. Tho crushed ore is then
digested in muriatic acid entirely free from chlorine. By this treatment all
metals, oxides, and earths soluble in muriatic acid are removed, and the pure:
quartz and gold remain; the residue must be washed with water till tasteless..
The wet auriferous quartz is then treated with chlorine either in the gaseous.
state in a close vessel, or in the state of aqueous solution; I prefer the latter.
In a few hours the whole of the gold will be dissolved; the ore is then well
washed with water, and the chloride of gold solution is boiled by a jet of
steam so as to liberate all free chlorine, and which may be collected. To the
boiling solution is then added sulphate of the protoxide of iron, oxalic acid,
or other precipitant for gold. When the gold contained in quartz is alloyed
with silver, I wash the quartz with a hot saturated solution of common salt
immediately after the treatment with muriatic acid, and before the treatment
with chlorine. The chloride of silver is thus dissolved, and the silver is
obtained from the salt solution by copper plates, or in any other manner.
The dressing of lead and other orcs has heretofore been effected by crushing
and then by the agency of water and several contrivances; the different ores
have been separated from their matrices by the difference in their specific
gravity. So far as I am aware this principle has been adhered to in all pro-
cesses now in use for dressing or cleaning ores. My improvement is as follows:
-I crush the ore dry, and prefer rolls for this part of the operation; the
degree of fineness depends entirely upon the grain of the ore in the matrix.
The object to be kept in view is simply to crush the rough ore as near as pos-
sible just as fine (and no finer) as will liberate cach particle of ore from the
matrix, so that none of the particles of ore be left encased in the matrix. This
I find can be best effected by crushing the ore a little coarser, and using a sieve
just the exact size, the coarser particles being returned to the rolls; when this
has been nicely effected, the crushing, properly so called, should cease. .I then
proceed in the following manner :-It is a well-known fact, that if particles of
a harder and softer nature are rubbed together, that the softer particles are
very soon reduced to powder. Acting upon this principle, I deliver the
crushed ore, prepared as above described, to a machine constructed on the
principle of common millstones for grinding corn. Indeed, a pair of .old
millstones, with the cutting edges-worn off, answer the purpose very well;
they must be carefully set so; as not to grind the ore, but simply rub the
particles together. The orc is then delivered to a set of revolving sieves of

page_text: different sizes; the first one should be very fine, and from which ore of first-
rate quality will be obtained; another one slightly coarser produces ore of a
second quality, and a third may sometimes be used; but I have found that
with lead ores and a quartz sandstone or limestone matrix, the refuse as
discharged from even the first sieve does not yield above per cent., whilst the
ore obtained produces 75% of lead.
'
"
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Henderson in the Great Seal Patent Office on the
8th October 1859:
.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENDERSON, of Alderley Edge, in the County of Chester, Chemist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighth day of April, in the year of our Lord Ono
thousand eight hundred and fifty-nine, in the twenty-second 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 thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
TREATING CERTAIN ORES, AND IN OBTAINING PRODUCTS THEREFROM,"
upon the
condition (amongst others) that I, the said William Henderson, my executors.
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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 follow-
ing statement thereof, that is to say :-
These improvements relate, first, to the treatment' of zinc ores or other os

page_text: containing zinc; secondly, to the treatment of ores of antimony that contain
lead and several other metals; thirdly, to the treatment of copper ores;
fourthly, to the treatment of ores or products containing cobalt; fifthly, to the
treatment of gold and silver ores and auriferous quartz; and, lastly, to the
dressing or concentrating of lead and other ores.
The first class of ores, viz., those containing zinc, I treat 'in the following
manner: If they contain sulphur they must be calcined in the usual or any
other manner; if they contain a large proportion of iron, five per cent. of
common salt must be added to the ore in the calcining furnace about the
time that it is estimated that one-half to two-thirds of the sulphur has been
sublimed. The salt is well mixed with the charge in the furnace, and the
calcination is finished at as low a degree of heat as is practicable. The
sulphurets so calcined, or the oxidės and carbonates, as the caso may be, are
then roughly crushed to pass through a sieve of eight holes to the inch, and
placed in vats with false bottoms, similar to those described in the Specification
of Letters Patent granted to me, the 30th September 1857, Number 2517,
and the ore is then covered with dilute muriatic acid of, say, 15° Twaddle's
hydrometer; the vats are worked exactly as described for copper ores in the
aforesaid Specification. When the ore contains a large proportion of iron,
lead, or other metal which would remain insoluble in the weak acid, it will
be found more desirable to effect the solution of the zinc, copper, &c., in round
tubs or cisterns, which may be made of wood or built of stone, bricks, or
other material that will withstand the action of the weak acid and metallic
solutions. In the centre of these round cisterns is fitted an upright spindle, to
which are attached two or more arms; the spindle is made to revolve, carry-
ing the arms with it. With this apparatus it is necessary to add the acid
first, set the agitator in motion, and then gradually add the ore until the acid
is completely saturated; the arms of the agitator are then raised, the motion
stopped, the contents of the tub or cistern allowed to settle; the clear
solution is then run into another vessel, to be treated as shall be described
presently, and the residue is well washed by agitating with successive portions
"of water, which when clear are added to the first liquor obtained from the ore
The ore must be treated with further quantities of acid until the whole of the
zinc has been dissolved. The saturated solution thus obtained may be treated
with milk of lime at once if it contain no other metal than zinc. When the
ore contains much lead, it is advisable to use very weak muriatic acid fo
dissolving the zinc, and thereby most of the lead is left insoluble in the vats
If the solution contains lead or copper, or both, they may be precipitated by

page_text: scrap iron or sulphuretted hydrogen, .or the lead may be precipitated by
sulphuric acid as sulphate, and the zinc then be precipitated as carbonate by
continuous boiling with carbonate of lime, and the iron may after separation
of the zinc be precipitated by caustic lime, as hydrated oxide of iron, which
may be used for purifying gas and other purposes. The acid may be recovered
from the chloride of calcium solutions, as described in my before-mentioned
Specification. The oxide or carbonate of zinc, obtained as has been described,
is reduced to the metallic state in the usual manner.
The second class of ores, viz., the ores of antimony, containing lead, silver,'
copper, and several other metals. of more rare occurrence, I treat in the
following manner:-When the ore is a sulphuret, I reduce it to fine powder,
and mix it with a variable proportion of common salt, also finely ground.
When the ore contains 50% of antimony, equal weights of salt and ore must
generally be used. When only 25% of antimony exists in the ore, 50 per
cent. of salt will be enough, and so on in proportion; an excess of salt is
preferable in all cases. The ore and salt, intimately mixed, are then calcined
in retorts or close calcining furnaces with free, admittance of air and repeated
stirring; the heat, must be very low at first, and gradually increased. to dull
redness. It will be found that the whole of the antimony, with some arsenic,
iron, sulphur, and other metals distil over in the state of chlorides, which are
condensed in flues or chambers, or by passing up a tower filled with coke or
pebbles with a small stream of water trickling downwards; I prefer the latter.
It will be found desirable, in order to obtain the oxide of antimony in a high
state of oxidation, to convey the sublimed chlorides through a tube or chamber.
sustained at a red heat immediately they leave the furnace. Into the same
end of this tube or chamber I introduce a small steam jet. By this means
the sublimed chloride of antimony is converted into oxide of antimony and
hydrochloric acid, which pass on to the tower and are condensed; the acid'
being retained by the water and the white oxide of antimony, is collected in
settlers properly arranged at the base of the tower. When the calcination has
been properly managed, the whole of the antimony will have been sublimed as
chloride of antimony, and the lead, copper, silver, and several other metals
and oxides, together with undecomposed salt and sulphate of soda, will remain
in the retort or furnace, and may be separated and reduced by any known
When the ore contains no sulphur, the metals should be converted
into chlorides by muriatic acid, and then evaporated to dryness, and calcined;
the antimony will be sublimed as chloride, as in the case of the sulphuret, and
the lead, copper, and other metals will remain in the retort or furnace. The
oxide of antimony, obtained as has been described, is well washed with water,
means.

page_text: dried, and reduced in a reverberatory furnace, with charcoal or other re-
ducing flux.
The ores referred to as of the third class are especially the poor sulphurets
of, copper, but ores of any degree of richness may be treated in the same
manner. These ores are first calcined in heaps, kilns, or furnaces, as may be
most convenient; all the sulphur must be removed whichever plan may be
adopted. The roughly crushed ore is then placed in vats treated with muriatic
acid until exhausted. The copper is precipitated from the solutions with iron
or sulphuretted hydrogen; after separation of the copper, the whole of the
dissolved iron is then precipitated in a separate vessel by caustic lime as
hydrated oxide, and the acid, if desirable, may be afterwards produced from
the chloride of calcium solutions, as described in the before-mentioned
Specification.
:
The treatment of ores or products containing cobalt consists in the separation
of cobalt from chloride of iron liquors by evaporating the neutral solutions to
dryness, and decomposing the residue by heat and steam, or jets of water.
The chlorides of iron are thereby converted into oxides, whilst the chloride of
cobalt remains undecomposed, and is dissolved out by boiling water. Chloride
of zinc and several of the earths and alkalis also remain undecomposed if they
existed in the original solution, and will be consequently dissolved with the
cobalt. To obtain the pure oxide of cobalt entirely free from these impurities,
I boil the cobalt solution with a strong solution of bleaching powder, and then
wash the resulting black precipitate of oxide of cobalt with very dilute.sul-
phuric acid, which will dissolve all impurities and leave the cobalt quite pure.
Gold ores I treat in the following manner :-I divide them into two classes;
the first class consists of gold ores, properly so called, viz., iron and copper
pyrites, and ores containing large proportion of other metals, oxides, and
earths; and the second of auriferous quartz, with sometimes small proportions
of oxides, earths, and other metals, and ores of the first class that contain
zinc, arsenic, or other metal that would volatilize in or during the process of
smelting. The ores of the first class when calcined should when properly
mixed, fuse by themselves or with the addition of very little flux. If very
refractory, they belong to the second class.
F
H
The first class of ores I calcine sufficiently to form, when smelted with
copper ore (if necessary), a regulus or matt of from 80 to 40 per cent. copper,
as is well understood. About 56 lbs. of such regulus should be produced for
every ton of ore. When a charge of 2 to 3 tons (according to size of
furnace) of this regulus has been-obtained, I fuse it. To the melted regulus
I add a mixture of two parts anhydrous sulphate of soda (salt cake), and one

page_text: part of coal or other carbonaceous matter. When the regulus is poor in gold,
say, containing not more than 40 ounces of gold per ton, one cwt. of the above
mixture may be added and thoroughly incorporated, by stirring with the
melted matt or regulus. After the mixture has been added, the doors of the
furnace are closed, and the heat continued for an hour or an hour and half;
the slag is then skimmed off, and the melted regulus tapped into sand moulds
in the manner usually practised in copper smelting. When the pigs of metal
have set, but whilst still hot, they are thrown into a tank or pan containing
water, which will speedily boil, the pigs of metal will disintegrate like quick-
lime, and the sulphuret of sodium will dissolve out, holding in solution the
sulphuret of gold. To obtain the gold from this solution, sulphuric, muriatic,
or other mineral acids may be added to the. sulphuret solution. The acid
must be added in excess, when the sulphuret of gold will be precipitated; it
is allowed to settle until the supernatant liquor is quite clear; it is then
syphoned or tapped off, and the precipitated gold collected, washed, dried, and
heated to redness, when pure gold will be left in the crucible or furnace. For
the purpose of saturating and decomposing the sulphuret of sodium solution
containing the gold, I prefer to use sulphuric acid, because the resulting
solution of sulphate of soda, when evaporated to dryness can be mixed with
fresh coal and used over again. I have only mentioned sulphate of soda, but
do not confine myself to its use, as carbonate or caustic soda, or sulphuret of
sodium, and even common salt, and also the corresponding salts of potash may
be used instead; but I prefer sulphate of soda. The residual copper regulus in
a fine state of division, and which was insoluble in the sulphuret of sodium liquor,
may still contain traces of gold; but as it is used over again with fresh gold
ore, or added to the copper ores used, it is of no consequence. If silver
exists in the original ore, it will remain with the copper regulus; and when by
repeated operations it has become sufficiently rich, the silver may be separated
by calcining the regulus in the fine state of division in such a manner as to
form. partially sulphates of copper with all the silver as sulphate, when
the silver is separated by dissolving in boiling water, and precipitating by
copper plates, as is well understood. The silver may also be separated
by calcining with common salt, or by any other means. The auriferous
quartz and gold ores of the second class I treat as follows:-If sulphur exists
in the ore, it must be first calcined. This may often be done in heaps
or kilns; but if it cannot be completely deprived of its sulphur by these
means, it must be calcined in furnaces. Before or after calcination, it should
be reduced to powder. I prefer that the pulverization of the ore be effected
without wetting it, when practicable. The ore is then placed in stone or

page_text: other suitable vats with false bottoms (as particularly described in my before-
mentioned Specification, treating of copper ores); the depth of the vats must
be regulated by the quality of the orc.
For a hard clean quartz the vats may
be 3 feet deep, and the powdered ore resting on the false bottom may be
2 feet 4 inches in thickness. When the ore, however, contains much clay or
other plastic material, it will be necessary to reduce the depth of the vats, so
as to allow the acid or liquors used to penetrate entirely through the whole
body of ore in about half an hour. When the ores are very soft and friable,
it is necessary to work them in round agitators. I prefer, however, to work
these ores in vats with false bottoms when at .all practicable. A vat having
been filled with the powdered ore, I cover the whole surface of the ore with
muriatic acid of about. 15° Twaddle's hydrometer, and allow it to penetrate
through the body of .ore. The acid must not contain any free chlorine.
When the whole of the ore has been wetted with muriatic acid, it is allowed
to rest for a few hours. The liquor.is then washed out with water until
perfectly steless. By this.means I separate all oxides and earths.soluble in
muriatic acid; if these are of any value, they may be separated from
the solution as previously described. The quartz thus prepared is now covered
with aqueous solution of chlorine, and the solution of the gold at once
takes place. A gentle heat much facilitates the solution. The liquor during
the process of solution should be repeatedly pumped to the top of the ore, and
allowed to penetrate under the false bottom, leaving the top of the ore dry;
and as soon as this occurs, it must be all pumped to the top again, so as to
keep up a constant circulation. If these directions are carefully attended to,
the whole of the gold will be dissolved out from even rich quartz in 24 hours.
The chloride of gold is then removed to another vessel, and a sample of the
ore tested for gold; if any remains undissolved, a further quantity of solution
of chlorine is added until the ore is exhausted. It is then washed thoroughly
clean, and the washings added to the original solution. The solution of gold
thus obtained is then boiled by a jet of steam to liberate the free chlorine. If
this is done in a close vessel, the chlorine gas may be again condensed by
passing it through cold water. When the boiling solution smells no longer of
chlorine, the gold is then precipitated by protosulphate of iron, oxalic acid, or
any other precipitant. If silver existed in the quartz, it will remain in
the ore, from which it may be separated by a boiling concentrated solution of
common salt, or by a warm solution of hyposulphite of soda from either
of these solutions; it is afterwards separated by plates of copper or other
suitable metal. If the quartz contained peroxide of manganese, peroxide of
cobalt, or even peroxide of iron,. in such a state as to be soluble or de-

page_text: composable by the weak muriatic acid, with which the ore was first washed,
small quantities of gold, and always more or less silver, will be dissolved.
Before throwing away this solution, I always boil it first with serap iron or
zine, which will precipitate all the precious metals; when this has been accom-
plished, and the liquor has settled clear, it may then with safety be run away.
In some varieties of gold quartz, the gold is only partially dissolved,
sometimes not at all, by aqueous solution of chlorine, nor by chlorine in the
gaseous state. These ores I treat in the following manner:-I take the ore
either before or after the washing with weak muriatic acid; if the latter I dry
it, and then intimately mix it with from 1 to 5 per cent. of good peroxide of
manganese (or other oxide capable of liberating chlorine from muriatic acid)
in fine powder. I then moisten this mixture with strong muriatic acid of at
least 1125 sp. gr., turning over the heap so as to ensure that every part has
been moistened. The heap is then gathered closely together, and allowed to
heat of its own accord in a dry place for 24 hours. At the end of that time
it should be transferred to the vats with false bottoms, and the vats filled.
Steam of a high pressure (say 60 pounds) is then slowly introduced under the
false bottom, from which it will gradually penetrate upward through the
whole mass of ore, dissolving the chlorides of gold and manganese, which are
drawn off from under the false bottom into' another vessel, and the ore
may then be entirely exhausted by washing with hot water. The gold will be
readily obtained from this solution by boiling with protosulphate or proto-
chloride of iron; I prefer the former. A mixture of common salt and oxide
of manganese may be mixed with the ore, and then the mixture moistened
with concentrated sulphuric acid, may be substituted for the oxide of
manganese and muriatic acid; but I prefer the latter as simpler and
cheaper.
When much silver, exists in the quartz, I treat the quartz' with hot
saturated solution of common salt, immediately after the washing with dilute
acid, and before the treatment with chlorine. The dressing of lead and other
ores has heretofore been effected by crushing or stamping, and then by the
agency of water and several apparatus and contrivances, the different ores
have been separated from their matrices by the difference of their specific
gravities. So far as I am aware, this principle has been adhered to in all
processes now in use for dressing or cleaning ores.
My improvement is as follows:-I crush the ore dry, and prefer rolls for
this part of the operation. The degree of fineness depends entirely upon the
grain of the ore in the matrix. The object to be kept in view is simply to
crush the rough ore as near as possible, just as fine (and no finer) as

page_text: F
will liberate cach particle of ore from the matrix, so that none of the particles
of ore remain encased in the matrix. This I find can be best effected
by crushing the ore a little coarser, and using a sieve the exact size, the
coarser particles being returned to the rolls. When this has been nicely
effected, the crushing, properly so called, should cease. I then proceed in tho
following manner:-It is a well-known fact, that when particles of a harder
and softer nature are rubbed together, the softer particles are very soon
reduced to powder. Acting upon this principle, I deliver the crushed ore
prepared as above described to a machine, constructed upon the principle of
common millstones for grinding corn, which answer the purpose very well.
They must be carefully set so as not to grind the ore, but simply rub
the particles together. The ore as it leaves the millstones is delivered to sets
of sieves, either revolving or shaking, as found most convenient, of different
degrees of fineness, and working in separato compartments. The first one
should be very fine, and from which ore of first quality will be obtained;
another one slightly coarser produces ore of second quality, and a third may
sometimes be used; but I have found that the matrix generally leaves
the second siove so poor as to produce ore of no value in a third sieve:
When practicable, I prefer that these sieves should be worked dry; but if any
difficulty prevents the ore being dried, the sieves should be worked with
as little water as will keep them clean, and discharge the matrix at the tail of
the sieves perfectly free from slimes.
And having now described the nature of my said Invention and in what
manner the same is to be performned, I declare that I claim,―
First, the method or methods herein-before described for separating and
obtaining zinc and other metals from zine ores and other ores containing zinc.
Second, the extraction of antimony from poor and mixed ores,. by the
means and in the manuer herein-before described.
Thirdly, the separation of lead, silver, and copper from antimony, by the
means and in the manner herein-before described.
Fourthly, the method herein-before described of treating copper ores.
Fifthly, the manufacture of hydrated oxide of iron as described.
Sixthly, the separation and extraction of oxide of cobalt from orcs and
products, by the means and in the manner hercin-before described.
Seventhly, the several methods described for separating and extracting gold
and silver from their ores and auriferous and argentiferous quartz, and the
use of alkaline salts or compounds and peroxide of manganeso and conimion
salt, with muriatic acid and sulphuric acid, for the purposes herein-before
described.

page_text: Eighthly, the preliminary treatment of gold ores and quartz with weak acid.
And, lastly, the method herein-before described of dressing lead and
other ores.
In witness whereof, I, the said William Henderson, have hereunto set
my hand and seal, this Sixth day of October, One thousand eight
hundred and fifty-nine.