IMPROVEMENTS IN THE PROCESS OF PURIFYING SULPHURIC ACID, AND OF RECOVERING THEREFROM THE ARSENIO AND ANTIMONY CONTAINED " THEREIN
Year: 1884

page_text: [Communicated from abroad by George Thomson, of Dillonton, in the County of
Brome, and Province of Quebec, Canada, and William Kemp of Jarrow on
Tyne, in the County of Durham, England, both temporarily residents at
Elizabeth, in the County of Union and State of New Jersey, one of the United
States of America.]
PROVISIONAL SPECIFICATION.
I WILLIAM PHILLIPS THOMPSON Fel. Inst. P.A. of 6 Lord Street Liverpool in
the county of Lancaster Civil Engineer do hereby declare the nature of the said
invention for "IMPROVEMENTS IN THE PROCESS OF PURIFYING SULPHURIC ACID,
AND OF RECOVERING THEREFROM THE ARSENIO AND ANTIMONY CONTAINED
"
THEREIN (a communication from George Thomson, of Dillonton, in the county
of Brome, and province of Quebec, Canada, and William Kemp of Jarrow-on-
Tyne, in the county of Durham, England, both temporarily residents at Elizabeth,
in the county of Union, and State of New Jersey, one of the United States of
America) to be as follows:-
The invention consists in the elimination from sulphuric acid manufactured from
pyrites of the impurities contained therein such as oxides of nitrogen, arsenic,
antimony, etcetera.
This is performed by adding to the acid ammonium sulphide, and thoroughly
agitating the compound, thus precipitating the metals and other impurities.
The acid is then passed through a filter (which may be, although not necessarily,
of lead) the sulphides precipitated being collected on its top.
The acid is then concentrated by beat to expel the last traces of oxides of
nitrogen.

page_text: I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A., 6, Lord Street, Liverpool,
Lancashire, Civil Engineer, do hereby-declare the nature of the said invention for
" 'IMPROVEMENTS IN THE PROCESS OF PURIFYING SULPHURIC ACID, AND
RECOVERING THEREFROM THE ARSENIC AND ANTIMONY CONTAINED THEREIN
OF
"3
(A communication from abroad by George Thomson, Dillonton, Brome County,
Quebec, Canada, and William Kemp, Jarrow-on-Tyne, Durham, England, both
temporarily at Elizabeth, Union County, New Jersey, United States), and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:―
In sulphuric acid manufactured from pyrites are usually contained certain
impurities such as oxides of nitrogen, arsenic, antimony et cetera which render such
acid unfit for use in many manufacturing establishments; and to remove these and
produce an acid which shall be as nearly as possible chemically pure is the object
of this invention.
This may be briefly described as consisting, first:-in the precipitation of the
above impurities by the addition to the acid of ammonium sulphide; in the
separation from the acid of such precipitated metals et cetera by filtration and in
the expulsion therefrom of the final traces of oxide of nitrogen by concentration.
To carry out the above process on a manufacturing scale I proceed as follows:
The acid as it comes from the condensing chambers is run into lead lined tanks,
cach usually holding about (10) tons.
Ammonium sulphide is then added to the acid which must be well agitated
during the operation so as to bring the ammonium sulphide in contact with every
part of it, the result being the precipitation of the metals and other impurities
above mentioned contained in the acid.
The acid is then taken, and passed through a filter contained in a lead lined tank
with a perforated bottom or diaphragm.
This filter must be of a substance not acted upon by sulphuric acid, and it is
found that what will best answer the purpose is finely divided lead such as fine
.shot or lead filings which are placed on the bottom or diaphragm to a depth of
from six (6) to twelve (12) inches.
The sulphides precipitated with the ammonium sulphide are collected on the top
of the filter, and the clear acid runs through into any suitable receiver or into the
bottom of the filtering vessel.
The clear acid is then taken from the receiver to lead pans where it is con-
centrated by heat. By this the last traces of oxide of nitrogen are acted upon by
the ammonium sulphate formed during the operation, and are expelled, thus leaving
an almost chemically pure acid.
The commercial value of the acid is much enhanced by the above process, the
cost of which is very small and will be nearly covered by the value of the bye-
products.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:
1st. Precipitating the impurities contained in sulphuric acid by the addition
thereto of ammonium sulphide substantially as herein set forth.

page_text: 2nd. Precipitating the impurities contained in sulphuric acid and then removing
same from the acid by filtering it through lead finely divided, substantially as
herein set forth.
3rd. The expulsion of oxides of nitrogen from sulphuric acid treated with
ammonium sulphide, by concentrating same by heat, substantially as herein
set forth.
DL: Oil 1
L
2007
WP. THOMPSON & Co.,
Agents for the Applicant.