Improvements in the Preparation of Pigments and in the Manufacture and Treatment of By-products therefrom.
Year: 1887

page_text: Date of Application, 23rd Mar., 1887.
Specification Accepted, 26th Apr., 1887.
Improvements in the Preparation of Pigments and in the
Manufacture and Treatment of By-products therefrom.
I THOMAS KENYON of 16 Tib Street Manchester in the County of Lancaster
Manufacturing Chemist 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 :-
The first part of my invention relates to the treatment of certain zinc solutions to
fit them for the preparation of pigments therefrom.
First in treating solutions of flux-skimmings or other waste zine products con-
taining ammonia iron and other impurities, and the object of my invention is to
effect the oxidation of the iron and other impurities with decomposition of the
ammonia salts present, previously to or at the time of their separation by
precipitation.
For this purpose I provide any suitable arrangement whereby a stream of air
(superheated or otherwise) either by itself or mixed with steam is blown into the
solution aforesaid, preferably through perforated pipes, either under the ordinary
pressure or under increased pressure in closed boilers."
The iron, manganese, or other impurities being thus oxidised I precipitate by the
use of an alkaline solution or by carbonates or hydrates of the alkaline earths.
Secondly in the treatment of the liquors obtained after the precipitation of sulphide
of zinc froin the above zinc liquors by means of sulphide of barium (chloride of barium
being left as a by-product) I add to this solution sulphate of ammonia by which means
sulphate of barium is produced, and the ammonia is recovered in the more valuable
form of chloride.
The sulphate of barium so produced may be mixed with the sulphide of zinc in any
suitable proportions to produce a pigment.
Or the precipitation of the sulphate of barium may be effected in the presence of
the precipitated sulphide of zinc, in which case the mixed pigment is produced from
which the chloride of ammonium may be separated by filtration.
Thirdly I recover the chloride of ammonium so produced, either by boiling down
and crystallization or I take the liquor so produced and I distil it with the vat waste

page_text: from alkali works to produce sulphide of ammonium to be afterwards used in the
preparation of pure sulphide of zinc.
By the use of the sulphide of ammonium so produced and solution of chloride of
zinc I prepare sulphide of zinc, and again recover the chloride of ammonium to be
repeatedly used for the reproduction of sulphide.
Fourthly I provide for the recovery of the chloride of ammonium adhering to the
precipitated sulphide, by an arrangement of condensers connected to the furnace in
which the pigment is roasted, to convey the gases from the furnace through a closed
boiler, or a condensing chamber of brickwork, by which means the escaping ammonia
salts are condensed.
Having now particularly described and ascertained the nature of my said invention
together with the manner in which the same is to be performed I declare that what I
claim is:-
First. The oxidation of iron and other impurities in zinc solutions (either con-
taining ammonia salts or not) by means of air blown through the said solutions either
with or without steam at the ordinary pressure, or in closed boilers which can be
submitted to greater pressure.
Secondly. The precipitation of sulphate of barium by means of sulphate of ammonia
either from the liquors left after precipitation of the sulphide of zinc by means of
sulphide of barium, or at the same time as the sulphide of zinc is precipitated and
together with it; in either case producing a solution of chloride of ammonium of
greater relative value than the sulphate of ammonia used.
Thirdly. The combination of the sulphide of ammonium produced by the distillation
of the recovered chloride of ammonium with vat waste from alkali works, for the
preparation of sulphide of zinc from zine solutions as described.
Fourthly. The combination with the furnace in which the sulphite of zinc pigment
is roasted, of an iron, brick, or other condenser for the purpose of recovering any
chlorido of ammonium which may be left adhering to it, and which would otherwiso
be lost.
DL: 00
1
1 1007
GEORGE DAVIES,
4, St. Ann's Square, Manchester,
Agent for the Applicant.