Improvements in Treating Certain Waste Materials to Produce Valuable Products, such as Plaster or Stiffening, Weighting, and Whitening Materials therefrom.
Year: 1895

page_text: Date of Application, 14th Aug., 1895
Complete Specification Left, 13th May, 1896-Accepted, 13th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Treating Certain Waste Materials to Produce
Valuable Products, such as Plaster or Stiffening, Weighting, and
Whitening Materials therefrom.
We, JOSEPH HENRY LESTER, M. Sc. F.I.C., of Arcade Chambers, Manchester,
in the County of Lancaster, Analytical and Consulting Chemist, and THOMAS
EDWARD THOMLINSON, of Walmersley Road, Bury, in the said county, Manu-
facturer, do hereby declare the nature of this invention to be as follows :-
-
This invention relates to further improvements in the treatment of waste products
or materials containing sulphate of lime carbonate of lime or hydrate of lime such
as produced in the manufacture of ammonia carbonate of ammonia or other salts
of ammonia when slaked lime is treated with sulphate of ammonia for the purpose
of producing a valuable product suitable for use in the arts.
In the Specification of our former Patent No. 13198 of 1894 we have described
the treatment of this waste material by sulphuric acid and we now find that by
first treating it with bydrochloric acid that a finer and superior quality of material
is produced.
The invention consists essentially in treating the waste material after being
reduced to a creamy consistency with a sufficient quantity of hydrochloric acid to
combine with the lime or carbonate of lime present and then treating the resulting
liquor with sulphuric acid to precipitate sulphate of lime therefrom.
In carrying out the invention we take the waste material in a creamy state
capable of passing through a sieve and to this we add a quantity of hydrochloric
acid sufficient to combine with all the lime present except the sulphate to form a
chloride in solution.
The mass is suitably agitated to allow of the mixture of the hydrochloric acid
with all the particles of it and then allowed to stand to allow sulphate of lime to
settle out.
The clear liquor is then run off into another tank and to it is added a quantity
of sulphuric acid which combines with the lime in the solution precipitating it.
This is then allowed to settle and the liquor run off. The precipitate thus obtained
consists of a pure sulphate of much finer quality than that previously obtained by
the use of sulphuric acid alone. The liquor run off at this stage of the process
contains dilute hydrochloric acid and may be used to mix with the crude material
in the first instance to reduce it to the required consistency and thus also reduce
the quantity of hydrochloric acid required to be added thereto.
The deposit obtained after the mixture of hydrochloric acid and the precipitate
subsequently obtained from the solution are separately treated in either of the ways
described in the Specification of our previous Patent No. 13198 of 1894 or in
other suitable way to produce plaster of Paris or a stiffening weighting whitening
or polishing material for textile fabrics yarns paper or the like.
Dated this 13th day of August 1895.

page_text: Improvements in Treating Certain Waste Materials to Produce
Valuable Products, such as Plaster or Stiffening, Weighting, and
Whitening Materials therefrom.
We, JOSEPH HENRY LESTER, M. S., F.I.C., of Arcade Chambers, Manchester,
in the County of Lancaster, Analytical and Consulting Chemist, and THOMAS
EDWARD THOMLINSON, of Walmersley Road, Bury, in the said county, Manu-
facturer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
and
or
This invention relates to further improvements in the treatment of waste products
or materials containing sulphate of lime with carbonate of lime hydrate of
lime such as produced in the manufacture of ammonia carbonate of ammonia or
: other salts of ammonia when slaked lime is treated with sulphate of ammonia for
the purpose of producing a valuable product suitable for use in the arts.
In the Specification of our former Patent No. 13198 of 1894 we have described
the treatment of this waste material by sulphuric acid and we now find that by
first treating it with hydrochloric acid that a finer and superior quality of material
is produced.
The invention consists. essentially in treating the waste material after being
reduced to a creamy consistency with a sufficient quantity of hydrochloric acid to
combine with the lime or carbonate of lime present and then treating the resulting
liquor with sulphuric acid to precipitate sulphate of line therefrom.
In carrying out the invention we reduce the waste material to a creamy state
capable of passing through a sieve and to this we add a quantity of hydrochloric
acid sufficient to combine with all the lime present except the sulphate to form a
: chloride in solution.
The material is treated in a vessel or tank of any convenient size and stirred or
agitated by suitable appliances to thoroughly mix the hydrochloric acid and bring
it into contact with all the particles therein. The hydrochloric acid is run in in
sufficient quantity to convert all the lime or carbonate of lime into calcium
chloride (CaCl). The quantity of acid required may be determined by testing
the liquor from time to time until a neutral solution is obtained.
The chloride solution. is then separated in a settling tank or filter or by means
of a filter press hydro-extractor or other mechanical means leaving a residue or
deposit of calcium sulphate (CaSO4).
The clear liquor is then run into another tank and to it is added a quantity of
sulphuric acid which combines with the lime in the solution precipitating it. The
precipitate thus obtained consists of a pure sulphate of much finer quality than
that previously obtained under our former Patent by the use of sulphuric acid
alone. I find by experiment that 112 lbs. of sulphuric acid (H.2 S4) of 80% strength
added to 100 gallons of calcium chloride solution of 10% strength are suitable
proportions to produce the fine precipitate of pure sulphate of lime (CaSO).
The precipitate is.separated in a settling tank or filter or by means of a filter
press hydro-extractor or other means. Any small amount of acid remaining in
the precipitate when separated may be removed or neutralized by washing with
lime water.
The liquor separated from the sulphate of lime at this stage of the process
contains dilute hydrochloric acid and may be used to mix with the crude material
in the first instance to reduce it to the required consistency and thus also reduce
the quantity of hydrochloric acid required to be added thereto.
The deposit of sulphate of lime obtained after the admixture of hydrochloric

page_text: acid and the precipitate of sulphate of lime subsequently obtained from the solution
are separately treated in either of the ways described in the Specification of our
previous Patent No. 13198 of 1894 or in other suitable way to produce plaster of
Paris or a stiffening weighting whitening or polishing material for textile fabrics
yarns paper or the like.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we now declare that what
we claim is.
or
1. The process of producing or recovering sulphate of lime from waste products
or materials containing sulphate of lime with carbonate of lime and hydrate of lime
which consists in first treating the material when of a creamy consistency with
hydrochloric acid (HCI) to reduce the carbonate and hydrate to a chloride (CaCl,).
then separating the sulphate from the chloride solution and subsequently treating
the chloride solution with sulphuric acid (H,SO.) to precipitate fine pure calcium
sulphate (CaSO) therefrom substantially as described.
2. The process of treating waste products or material containing sulphate of
lime with carbonate of lime and hydrate of lime to produce valuable products
therefrom substantially as herein described.
ог
Dated this 11th day of May 1896
WM. P. THOMPSON & Co.,
Manchester, Liverpool, and London, Patent Agents.
WM. P. THOMPSON & Co.,
Manchester, Liverpool, and London, Patent Agents.