IMPROVEMENTS IN THE MANUFACTURE OR CHROMIC ACID AND CHROMATES
Year: 1864

page_text: LETTERS PATENT to Frederick Oldfield Ward, of 6, Hertford Street, May
Fair, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OR CHROMIC ACID AND CHROMATES"
Sealed the 22nd November 1864, and dated the 1st June 1864.
PROVISIONAL SPECIFICATION left by the said Frederick Oldfield Ward
at the Office of the Commissioners of Patents, with his Petition, on the
1st June 1864.
I, FREDERICK OLDFIELD WARD, of 6, Hertford Street, May Fair, in the
County of Middlesex, do hereby declare the nature of the said Invention,
for "IMPROVEMENTS IN THE MANUFACTURE OF CHROMIC ACID AND CHROMATES," to
be as follows:-
This Invention has for its object to reduce the temperature requisite when
treating chrome ore in the furnace for the purpose of developing therefrom
chromic acid or chromates by any of the modes in use for the said purposes.
The advantage arrived at in reducing the temperature is, first, to diminish the
wear and tear of the furnaces; and, secondly, to obviate the volatilisation of
alkali in that class of chrome processes in which an alkali is furnished along
with the chrome ore.
The method I employ for the reduction of the temperature consists in the
introduction of a proportion of fluorine in the form of a fluoride, preferably
calcic fluoride, along with the chrome ore under treatment in the furnace.

page_text: My claim is for treating chrome ore in the furnace in conjunction with
fluorine in the form of a fluoride, preferably calcic fluoride, when operating
upon the said ore for the purpose of developing therefrom chromic acid or
chromates.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frederick Oldfield Ward in the Great Seal Patent Office
on the 1st December 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
OLDFIELD WARD, of 6, Hertford Street, May Fair, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of June, in the year of our Lord One
thousand eight hundred and sixty-four, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Frederick Oldfield Ward, Her special licence that I, the said Frederick
Oldfield Ward, my executors, administrators, and assigns, or such others
as I, the said Frederick Oldfield Ward, 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 THE MANUFACTURE OF CHROMIC ACID AND
CHROMATES," upon the condition (amongst others) that I, the said Frederick
Oldfield Ward, 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 Frederick Oldfield Ward, do hereby
declare the nature of my said Invention, and in what manner the same
to be performed, to be particularly described and ascertained in and by
the following statement, that is to say :-
This Invention has for its object to reduce the temperature requisite. when
treating chrome ore in the furnace for the purpose of developing therefrom
chromic acid or chromates by any of the modes in use for the said purposes.
The advantage aimed at in reducing the temperature.is, (1), to diminish the

page_text: .
wear and tear of the furnaces, and (2), to obviate the volatilisation of alkali
in that class of chrome processes in which an alkali is furnaced along with
the chrome ore.
The method I employ for the reduction of the temperature consists in the
introduction of a proportion of fluorine, in the form of a fluoride, preferably
calcic fluoride, along with the chrome ore under treatment in the furnace.
'
My claim is for treating chrome ore in the furnace in conjunction with
fluorine, in the form of a fluoride, preferably calcic fluoride, when operating
upon the said ore for the purpose of developing therefrom chromic acid or
chromates.
This Invention is applicable in the treatment of chrome ore, whether by the
old process, in which nitrate of potash was used as the oxidising agent, or by
the more modern processes, in which the oxygen of the air is employed to
convert the sesquioxide of chromium in the ore into chromic acid, an alkali or
alkaline earth being at the same time employed to combine with this acid as
fast as it is formed.
This Invention is also applicable when chrome ore is first freed of iron (by
igniting the ore with a carbonaceous material to reduce the iron oxide to the
metallic state, and by then treating it with sulphuric acid to dissolve out the
iron) and afterwards oxidised in the furnace by one or other of the above-
mentioned modes. In short, as all the chrome processes known are
characterised by their requiring a more or less strong and protracted ignition
of the ore in the furnace, so in all of them this Invention is available for the
reduction, in a greater or less degree, of the time and temperature of such
ignition.
In performing my said Invention, the fluoride employed, preferably fluor
spar, should be reduced to fine powder, and intimately blended with the
pulverized chrome ore and with the other ingredients of the mixture to be
furnaced, in each case (according to the particular chrome process adopted.)
The fluorine thus introduced into the mixture acts as a flux, promoting and
accelerating the reaction of the materials, and reducing the temperature of the
operation. The furnace product thus obtained may be lixiviated in the usual
way, and the product of lixiviation may go through the usual processes of
purification, crystallization, and so forth, to fit it for the market.
The proportion of the fluoride to be employed varies in each case according
to the quality of the chrome ore treated. Some samples of chrome ore are of
a much more refractory and infusible character than others; some present a
much more crystalline texture; others are amorphous, and in several cases I
have found these latter more fusible than the crystalline varieties. These

page_text: variations make it impossible to lay down a fixed rule for the quantity of
fluoride to be employed in carrying out my Invention. The plan I adopt is
to make, in the case of each quality of chrome ore, a few preliminary crucible
trials, beginning, by adding to the chrome ore one-twentieth of its weight of
good soft fluor spar, and varying this. proportion up and down till I see, by
comparing the results of the trials, which proportion accomplishes the most
considerable reduction of temperature, coupled with the most complete and
rapid conversion of the chromic sesquioxide into chromic acid. In such trials,
of course, the basic ingredients employed to take up the chromic acid as fast
as it is produced are to be added as usual, according to the chrome process in
each case adopted, whether the basic material be lime, potash, soda, or any of
the respective salts thereof. The various stages of the several processes are
in each case performed in the usual way, my improvement being confined to
the lowering of the temperature as above stated.
I expressly disclaim, as forming no part of my present Invention, but
belonging to an Invention separately patented by me, the ignition of ground
chrome or in admixture with ground felspar, chalk, and fluor spar or other
fluoride for the purpose of simultaneously liberating the acid and alkaline
ingredients of potassic chromate; but with this exception, I claim as of my
Invention the association of fluor spar or other fluoride with chrome ore,
during the ignition thereof, together with a basic ingredient, earthy or alkaline,
and an oxygen source, solid, fluid, or gaseous, in order to develope chromic
acid or chromates, substantially as herein set forth.
Having thus set forth the nature of my Invention, and the best means I am
acquainted with for carrying it advantageously into effect, regard being had to
the varying qualities of chrome ores, I would observe that I do not confine
myself to any particular mode of working chrome ore for the production of
chromic acid or chromates, nor to any particular kinds or proportions of the
ingredients used in such process, the essential character of my Invention con-
sisting in the addition of fluorine, in the form of a fluoride, preferably fluor
spar, in the manner and for the purpose above explained.
In witness whereof, I, the said Frederick Oldfield Ward, have hereunto
set my hand and seal, this First day of December, in the year of our
Lord 1864.
FREDERICK OLDFIELD WARD. (L.S.)