IMPROVEMENTS IN THE MANU- PACTURE OF PHOSPHORUS
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Charles Denton Abel at the
Office of the Commissioners of Patents, with his Petition, on the
1st June 1870.-A communication from abroad by Edouard Aubertin,
of No. 66, Boulevard de Strasbourg, Paris, France.
I, CHARLES DENTON ABEL, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, Patent Agent, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE MANU-
PACTURE OF PHOSPHORUS," to be as follows :---
This improved process is dependent on the principle of the decom-
position of phosphate of lime by silica at an elevated temperature, between
2192° and 2932° Fahrenheit, in the presence of carbon whether by cal-
cination in furnaces or retorts or by melting in a blast furnace.
Two methods of operating may be employed, the one by calcination the
other by fusion.
First Process. By Calcination.-The phosphate of lime is mixed with
an excess of silica and with carbon so as to form an infusible or not easily
fusible mixture; this mixture finely pulverized is placed in a furnace or
retort and is calcined at a temperature of from 2192° Fahrenheit to 2404°
Fahrenheit when there will be produced silicate of lime and phosphoric

page_text: acid. The phosphoric acid is reduced by the carbon, which thus liberates
the phosphorus. In order to collect this the vapours thereof which
escape from the furnace or retort are made to circulate in cooled recipients
containing water for condensing the vapours. The silicate of lime is then
removed from the furnace or retort and a fresh charge of the above
mixture is introduced and the operation is repeated.
It will be understood that the respective proportions of the substances
for forming the infusible mixture will vary according to the nature and
degree of purity of the phosphate of lime. By way of example it may
be stated that if the phosphate of lime is pure the infusible mixture may
be formed of about 1000 parts by weight of phosphate of lime with about
2750 parts by weight of silica and about 200 parts by weight of carbon
(charcoal). This mixture is pulverized before being introduced into the
furnace or retort. The charcoal serves as reducing agent.
Second Process. By Fusion.-The quantity of lime contained in the
phosphate to be employed is calculated, and silica is added in sufficient
quantity for forming a readily fusible mixture. It is possible to increase
the degree of fusibility within certain limits by adding other bases, as the
mutiple silicates are much more fusible than the simple silicates.
The following rules must however be observed,—
1st. Metallic oxides that are susceptible of being reduced must not be
employed as fluxes because metallic phosphides would be obtained and
the phosphorus would not be liberated.
2nd. An excess of silica should be retained in the fusible mixture, as
this alone allows of the elimination and reduction of the phosphoric acid
in the presence of carbon.
It will be understood that it is not possible to enter into the relative
details of the diverse combinations in the first and second processes, it
can only be generally said that,-
In the first process, in which the phosphoric acid is displaced and
reduced without forming fusible silicates it is necessary to have only a
simple silicate with the least possible foreign matter, bnt with a great
excess of silica.
In the second process, where the phosphoric acid is eliminated and
reduced by melting the whole of the mixture it is necessary to maintain the
silica in excess while approaching as nearly as possible to the silicates
represented generally by the formula Ca 02 Si0³ which may be combined

page_text: for accelerating the fusion with other silicates, such as those of soda,
potash, magnesia, alumina, &c. but these latter should at the same time
contain an excess of silica.
"
For the second process, by fusion, the phosphate of lime, silica, and the
carbon are introduced into a blast furnace and by preference into that
description of blast furnace known as Fluss-ofen," employed in Styria
and Carinthia. No pulverisation of the ingredients is requisite, and the
carbon acts as reducing and fusing agent. In this second process may
be used 1950 parts by weight of phosphate of lime and 3400 parts by
weight of silica, or 1000 parts of phosphate of lime with 1700 parts of
silica, and about 270 parts of dry clay. The respective proportions of the
substances depend however, as in the first process, upon the nature of the
phosphate of lime. When mineral phosphate of lime is used containing
silica this quantity of silica must be taken into account by adding propor-
tionately less to the mixture. The blast furnace being heated to a
temperature of between 2192° Fahrenheit and 2932° Fahrenheit the
mixture is fused and a double silicate of lime and alumina is formed, and
the phosphoric acid is eliminated and reduced by contact with the carbon.
The phosphoric vapours are directed, as in the first process, into recipients
containing water, where they are condensed.
The second process allows of phosphate of lime from all sources being
used, such as from bones, coprolites, apatites, phosphorites, and other
phosphates with earthy bases.