IMPROVEMENTS IN TREATING ORES. AND OTHER MINERALS, AND IN OBTAINING VARIOUS PRODUCTS THEREPROM, CERTAIN, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO THE MANUFACTURE OF ALKALI
Year: 1842

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
LONGMAID, of Plymouth, Accountant, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her.
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twentieth day of October, in the sixth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Longmaid, Her especial licence, full power, sole privilege and
authority, that I, the said William Longmaid, my exors, adñors, and assigns,
or such others as I, the said William Longmaid, my exors, admors, or assigns,
should at any time agree with, and no others, from time to time and at
all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN TREATING ORES.
AND OTHER MINERALS, AND IN OBTAINING VARIOUS PRODUCTS THEREPROM, CERTAIN,
PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO THE MANUFACTURE OF ALKALI;"
in which said Letters Patent is contained a proviso that I, the said William.
Longmaid, shall cause a particular description of the nature of my said
Invention, and in what manner the same is to be performed, to be inrolled
in Her said Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso; I, the said
William Longmaid, do hereby declare that the nature of my said Invention,

page_text: and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had
to the Drawing hereunto annexed, and. to the figures and letters marked
thereon (that is to say) :—
My Invention relates to the treating of such descriptions of ores and
minerals as contain sulphur; and my Invention has for its object the removal
of the sulphur from such ores and minerals, in order to render the subsequent
operations to which such ores are subjected more advantageous in obtaining
products therefrom. As the first part of the treatment of ores and other
minerals containing sulphur relates to a mode of using common salt for
the purpose of taking the sulphur from ores or minerals treated, it is desirable
in the outset to state, that I am aware that it has before been proposed
to mix common salt in small quantities (ten to twelve per cent. of the
ores treated,) with silver ores, in order to set free muriatic acid to dissolve the
silver therein, in which case the common salt so employed has been converted
into sulphate of soda; and I am also aware that in chemical works it has been
proposed to mix common salt in comparatively small quantities, with pyrites
containing about fifty-four per cent. of sulphur. In such case it has been pro-
posed to use about forty per cent. of common salt; but such means have not, so
far as I am informed, ever been carried into any practical use in England,
nor do I think that the same are of any practical value. And I mention
these matters in order to state, that I do not claim the using of common
salt generally as a means of taking up sulphur contained in ores or minerals,
for I have discovered, after much experiment, that the use of common salt
for such purposes can only be generally and practically useful as a manufac-
ture when the quantity of salt applied in respect to the ore or mineral treated
considerably exceeds the quantity of sulphur contained in the ore or mineral.
And I have found that when treating ores according to my Invention, with
common salt, I obtain metallic oxides in a condition fit for metallurgical
purposes; and by such means I am enabled more advantageously to obtain the
metallic products of the ores treated than when operating on similar ores
according to the means now practised, and with one great advantage, that in
so treating ores and minerals containing sulphur, I take up the larger portion
of the sulphur so contained in the ores or minerals, and convert common salt
into sulphate of soda. Hence it will be understood, that my Invention consists
of treating ores and minerals containing sulphur with such proportions of
common salt that the ores are deprived of their sulphur, or nearly so; and the
metallic products resulting from such process are rendered more suitable
for subsequent processes for obtaining the metals therefrom, and at the same

page_text: time the act of so treating the ores and the minerals will produce much larger
quantities of sulphate of soda than has heretofore been obtained.
And in order that my Invention may be most fully understood, and readily
carried into effect, I will proceed to describe the means pursued by me, at the
same time remarking that I do not confine myself to such means, provided the
quantities of common salt used exceeds the quantity of sulphur contained in any
ore or mineral, as herein described. And I may here remark that I have
found that any ore containing fifteen to twenty per cent. of sulphur, and in
some cases even less, may be usefully operated on according to my Invention;
and the treatment, according to my Invention, may be usefully applied either
before or after the ores have undergone any process of heat, provided a quantity
of sulphur remains equal to the per centage above mentioned. The ores and
minerals to be treated according to my Invention are those, as before stated,
containing sulphur, particularly mundics, or iron pyrites, copper ores, lead ores,
tin ores, zinc ores; mundics, or iron pyrites, containing sulphur combined with
copper or tin, or with both; copper ores, containing sulphur combined with
iron or tin, or with both; lead ores, containing sulphur combined with copper;
and tin ores containing sulphur combined with copper or iron, or with both.
The process of treatment, according to my Invention, is to be carried on in
suitable furnaces. The one which I prefer is a reverberatory furnace, having
four beds, each succeeding bed being on a somewhat higher level in proceeding
from the fire towards the end of the furnace. At the same time I do not confine
myself thereto, as the furnace employed may be varied without departing from
my Invention; and the ore or mineral, with salt, are to be introduced on the
bed of the furnace most distant from the fire, in order that the sulphur given
off at comparatively low temperature may be taken up by the salt; and as the
ores operated on progressively require more heat to separate the sulphur;
they will progressively be brought on to a hotter bed of the furnace.
The Drawing shews a longitudinal section and plan of a furnace, such as I
prefer to use in carrying out my Invention, and which I prefer to make about
sixty feet long, and ten feet from back to front in the clear, having several
openings to allow of the matters under process being turned or stirred from time
to time; and I find that the occasional admission of steam to the charge
nearest the fire is attended with beneficial effects, promoting the oxidation of
the minerals and the evolution of the muriatic aid, but the same is not
absolutely necessary.

page_text: should be dried previous to mixing with the mundics or other sulphur ores,
either by placing over a flue, so as to obtain the benefit of the otherwise
waste heat, or in any other more convenient manner. The object of this
drying is to prevent its caking in the furnace. The quantity of sulphur con-
tained in the ore having been ascertained by the analysis of a. carefully
prepared sample, a given quantity of salt, say one ton, having been weighed
out, a quantity of ore containing sulphur required for the conversion of the
salt into salt cake should be added and intimately mixed. The quantity of
sulphur required to convert a ton of salt into salt cake is, by calculation, about
five hundredweight one quarter and eleven pounds; but as all the sulphur
"cannot, I believe, even with the most careful manipulation, be taken by the
salt, it is proper to have the sulphur in excess above that quantity. And
.although a beneficial working may be obtained by employing a much less
quantity of salt in respect of the sulphur contained, yet I have found that in
all cases the common salt should considerably exceed the known weight of
sulphur contained in the ore or mineral under process; and I do not make
any claim to combining common salt with ores or minerals containing, sulphur,
where the salt used does not exceed the weight of sulphur contained in a pro-
portion at least of sixty of salt to forty of sulphur. The mixture of about two
thirds of the ore required for the salt used should be put upon the upper bed
of the furnace, that is, the bed farthest removed from the fire, and left until
beated throughout. It should then be turned over from-time to time, so as to
allow of the successive contact of the mixture with the atmospheric air passing
through the furnace. At about equal intervals and at several times during
the time the mixture remains on the upper bed, the remaining quantity of ore
should be added. By these means the rapidity and effectiveness of the opera-
tion is promoted, and some saving of fuel is produced. It is impossible to
fix the exact quantity of ore required, as it must vary according to the quan-
tity of sulphur contained in the ore employed, and depending, in some degree,
on the nature of the substances associated with it; but I generally apply a
quantity of ore, containing at least five hundred weight one quarter and eleven
pounds of sulphur, to each ton of common salt. The less arsenic contained
in the ore the better, although its presence is not an insurmountable objec-
tion, especially if associated with a small percentage of copper. A charge
being drawn about every twenty-four hours from the front bed, each one of
the three remaining charges will then be moved forward to the next lower
bed, and a fresh charge put into the upper bed, each one of the charges being
kept regularly raked in its turn. A brisk fire is to be kept up in the furnace
during the whole time, and a damper is applied to the chimney to obtain
regulation. As the decomposition of the salt and ore proceeds, the mix-

page_text: ture is gradually fitted to bear the increase of temperature obtained by
removal from the upper to the next lower bed, and so on; approaching the
fire. The operation appears to proceed best when on the bed nearest
the fire it has been brought to a semi-pasty condition, or when the mass
has a tendency to agglomerate, and seems to be moist on the surface. By
the increase of temperature to which it is here exposed, the charge soon begins
to dry up, so that it is eventually drawn in a granular condition. The sulphate
ash obtained contains sulphate of soda or salt cake, the chloride of sodium,
oxides of iron, a soluble salt of copper, and oxide of tin, if any tin was present
in the ore employed, provided the ores be mundic; and, if other ores are used,
other products will be obtained. The ash being lixiviated with water, affords
a solution containing the sulphate of soda, chloride of sodium, and salt of
copper, the insoluble residue containing the oxides of iron and tin. If oxide
of tin be contained in the ore employed, it may be separated from the residual
matters by washing, the greater specific gravity of the oxide of tin rendering
the separation comparatively easy. The copper may be separated from the
solution, either with iron, as-is well understood, or, as I prefer, by the addition
of lime slacked in water, forming a milk of lime. Iron precipitates the copper
in a metallic form; but the lime precipitates it as an oxide, associated with the
slight excess of lime necessarily employed, and some small portion of sulphate
of lime. This precipate, by filtration, having been separated from the refined
liquor, should be well washed, in order to the complete separation of sulphate
of soda and chloride of sodium, the liquors obtained being employed in the
lixiviation of fresh sulphate asb. This precipitate is bulky; but, by filtration
and drying, its volume is very much diminished, and it is then obtained in a
condition fit for reduction to the metallic state by the usual metallurgical pro-
cess. The solution from which the copper has been separated may, if required,
be concentrated by boiling, and set aside to crystallize in suitable vessels, very
fine crystals of the sulphate of soda being obtainable. The mother liquor may
be again concentrated, and set aside to crystallize, or, if required, be employed
for the manufacture of alkali by mixture with fresh lime in quantities bearing
the proper proportions observed in the manufacture of black ash. If the
salt cake be required only for the inanufacture of alkali, the solutions obtained
by lixiviation should be run off into a large tank, from which the quantity of
liquor containing the desired quantity of salt cake may be run on its equivalent
of newly burnt lime, previously weighed out, by which means the water of
solution is either solidified or expelled by the heat evolved in the course of
the slacking. But should the solution be so weak that the heat evolved from
the requisite quantity of lime would not be sufficient to expel the whole of the

page_text: water, the lime, after being treated with sufficient of the liquor for slacking
and converting into a very thick pasty condition, resembling a tough mortar,
might be thrown either upon a flue at the end of a black-ash furnace, by
means of which the benefit of spare heat may be obtained, or upon the third
bed of a black-ash furnace, where, as evaporation proceeds, the remainder of
the liquor required may be gradually added. By these means a more perfect
mixture of the salt cake, with its equivalent of lime, is obtained than is the case
by the usual process of mixing only the slacked lime and the dry sulphate of
soda or salt cake in powder. The mixture of soda and lime treated with its
requirements of carbonaceous matter previous to turning down to the lower
bed of the black-ash furnace is in the usual condition in which it is
employed.
Having thus described the nature of my Invention, and the best means I
am acquainted with for performing the same, I wish it to be understood that
the operation need not be confined to the precise details above explained, but
admits of being varied, provided the quantity of common salt be at least at the
rate of sixty by weight to forty of the ascertained quantity of sulphur contained
in the ores or minerals. But what I claim is, the mode of treating ores and
minerals containing sulphur, to obtain various products therefrom, by applying
common salt, in the proportions herein explained, to take up the sulphur, and
to manufacture alkali, as above described.
In witness whereof, I, the said William Longmaid, have hereunto set
my hand and seal,' this Twentieth day of April, in the year of our
Lord One thousand eight hundred and forty-three.
AND BE IT REMEMBERED, that on the Twentieth day of April, in the
year of our Lord 1843, the aforesaid William Longmaid, came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Enrolled the Twentieth day of April, in the year of our Lord One
thousand eight hundred and forty-three.