An Improved Refractory Substance to be Employed in the Construction of Apparatus for Use in Meatllurgical and other Chemical Onerations om Proces in hinh Plated
Year: 1884

page_text: An Improved Refractory Substance to be Employed in the
Construction of Apparatus for Use in Meatllurgical and other
Chemical Onerations om Proces
in
hinh
Plated
I JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of said Invention for "IMPROVEMENTS IN
THE CONSTRUCTION OF APPARATUS FOR USE IN METALLURGICAL AND OTHER
CHEMICAL OPERATIONS OR PROCESSES IN WHICH AN ELEVATED TEMPERATURE IS
EMPLOYED to be as follows:-
"
This Invention consists in the employment as hereinafter described of magnesia
or oxide of magnesium in the construction or manufacture of furnaces crucibles
retorts and other like articles or apparatus which are employed in metallurgical
and other chemical operations or processes and are required to withstand intense
heat.
In carrying out this Invention magnesia or oxide of magnesium free from
foreign matter such as silica, silicates, lime and the like is employed which may be
obtained by roasting or calcining native magnesia such as magnesite gisbertite
periclase or other minerals or compounds containing magnesia but it is preferred
to employ for the purposes of this Invention magnesia obtained from Sea water in
order to obtain a product chemically free from silica.
A suitable quantity of this magnesia is roasted as perfectly as possible by
subjecting the material preferably when made into cakes to the action of intense
heat and the product thus obtained is coarsely ground or divided. Another
quantity of the magnesia is maintained in a caustic condition and the two products
thus obtained are mixed together according to the purpose to which they are to be
applied in the proportion of from about sixty to ninety per cent of the roasted
magnesia and from about ten to forty per cent of the caustic magnesia. In certain
cases from about ten to ninety per cent of the roasted magnesia may be mixed
with from about ninety to ten per cent of the caustic magnesia the proportion
being regulated according to the purpose to which the product is to be applied.
ID 17

page_text: This mixture is moistened with water containing in solution, starch, flour, carbonate
of potash of commerce, or other binding material and is well rammed into moulds
whereby the required shape is imparted to the product. The articles or apparatus
thus obtained after being dried are ready for use but in some cases it is desirable
to expose them to the action of an elevated temperature preferably not less than
that of a Martin Siemens gas furnace whereby the surface is hardened forming a
species of crust presenting the requisite stiffness or rigidity.
The roasting or calcination may be performed by mixing about fifteen to
eighty five per cent of the coarsely divided magnesia with from eighty five to
fifteen per cent of the pulverised magnesia and working the materials into cakes
of suitable form which are exposed to an elevated temperature gradually increasing
in intensity so as to enable the materials to contract without prejudice or waste.
When the contraction has taken place which is usually the case when a white heat
is attained the fire is urged to the utmost degree possible. This operation is
preferably performed with the employment of continuous regenerating gas furnaces
which are preferable both on the score of economy or for obtaining an intense
heat. The fire proof or fire resisting articles or apparatus obtained by the
employment of pure magnesia exclusively as herein before described are practically
infusible and are cheaper and more durable than those heretofore employed.
Having now particularly described and ascertained the nature of the Baid
Invention and in what manner the same is to be performed I declare that what
I claim is :-
First The employment of magnesia in or for the construction of apparatus for
use in metallurgical and other chemical operations in which an elevated temperature
is employed substantially as herein before described.
Second The employment of a mixture of roasted or calcined and caustic
magnesia in or for the construction of apparatus for use in metallurgical and other
chemical operations in which an elevated temperature is employed substantially as
herein before described.
Third. The employment in or for the construction of apparatus for use in
metallurgical and other chemical operations in which an elevated temperaturo is
employed, of a refractory material composed of a mixture of roasted or calcined
and caustic magnesia prepared and treated substantially as hereinbefore described.
T1 1001