IMPROVEMENTS IN THE PROCESS AND APPARATUS FOR CONCENTRATING SULPHURIC ACID
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Alfred Julius Boult at the Office of
the Commissioners of Patents on the 3rd October 1882. Communicated to
him from abroad by Junius Gridley of the City of Brooklyn in the County of
Kings and State of New York in the United States of America.
ALFRED JULIUS BOULT of the firm of W. P. Thompson & Boult of the Agency for
Foreign Patent Solicitors, of 323 High Holborn in the County of Middlesex and
6 Lord Street Liverpool in the County of Lancaster Engineer "IMPROVEMENTS IN
THE PROCESS AND APPARATUS FOR CONCENTRATING SULPHURIC ACID," a commu-
nication to me from abroad by Junius. Gridley of the city of Brooklyn in the
county of Kings and State of New York in the United States of America
My invention relates to certain new and useful improvements in the process and
Apparatus for concentrating Sulphuric acid.
The concentration of sulphuric acid is now and has heretofore been almost
exclusively carried on in retorts composed of either platinum or glass in various
forms for the reason that ordinary iron retorts were impracticable owing to the fact
that dilute sulphuric acid acts upon the iron forming a sulphate which tends to a
rapid destruction of the metal and an impure acid as a natural result.
As between the platinum and the glass as desirable materials for retorts, the former
is the most satisfactory but its great cost entails so serious an outlay that it has
given to manufacturers having the means to employ it almost a monopoly of the
manufacture of strong sulphuric acid.
Where glass retorts are used the results are to a considerable extent unsatisfactory
because of the large amount of fuel required, the frequent breakages and consequent
wear and tear and in addition to the disadvantages named the employees are
exposed to considerable danger.
The object of my invention is the concentration of dilute sulphuric acid in cast
iron vessels in such a manner that the iron is not acted upon by the acid thereby
rendering iron vessels for that purpose as effective as platinum
My invention. is based upon the fact that sulphuric acid of 66° Beaumé strength
at 60° Fahrenheit has little or no action on cast iron and my invention consists first
of the process of introducing a small stream of dilute acid from the evaporating
pans of the strength say of 60° Beaumé into a large quantity (say one ton or more)
Paine 9.77

page_text: of acid of the strength of 66° Beaumé contained in a concentrating pan or retort
charged originally with acid of 66° strength and kept thereafter at the boiling
point, The feed of dilute acid to be so regulated as not to reduce the acid in the
concentrating pan or retort below 65° Beaumé at the surface or acid line, at which
point and four inches below the surface the iron at the sides is protected from the
action of the acid.
The second part of my invention relates to the apparatus for carrying out my
invention and consists of a cast iron pan cast with an inwardly projecting flange
that supports the arch and ends.
I prefer to make this pan about four feet high, eight feet long, and one foot in depth
.with sides one and one-fourth inches thick and a bottom one and one-half inchies
thick At one corner of the pan I form a pocket about six inches by six inches and
of the depth of the pan, the bottom of which latter is connected with said pocket,
The arch that covers the pan I preferably construct of fire. brick set in fire clay
with a backing of asbestos retort cement between the bricks and the sides of the
pan above the support of the arch The ends of the latter are provided with
feed and vapor pipes, the feed being effected by means of a siphon that delivers
the liquid from an evaporating pan into a cup and thence by a pipe into the pan.
The pan is heated by a suitable furnace underneath of it and below the pocket
is arranged a cooler, The pan is also provided with a pipe for carrying off the
vapors.
I draw off the concentrated acid from the pocket into the cooler by means of a
siphon from which pocket it is then taken to the bottling tank. As the pan would
have a boiling surface of about twenty-four square feet, the heat that can be
practically brought to bear upon it will concentrate from seven to ten tons of acid
in twenty-four hours.
To those skilled in the art of concentrating sulphuric acid it will be understood
that the strongest acid is always at the bottom of the retort and the light acid at
the surface, so that in the practice of my process with my improved apparatus
supporting flange will always be below the weak acid line while the sides that
would otherwise be exposed to the action of the weaker acid are protected by the
fire brick of the arch and the Asbestos retort cement which is impervious to boiling
acid when confined between surfaces