Works to Obtain Products therefrom.
Year: 1887

page_text: Date of Application, 30th Dec., 1887
Complete Specification Left, 29th Sept., 1888
Complete Specification Accepted, 23rd Nov., 1888
Works to Obtain Products therefrom.
I MICHEL NICHOLAS D'ANDRIA of West Egerton Street Salford in the County of
Lancaster Chemical Manufacturer do hereby declare the nature of this invention to be
as follows:
My invention relates to the treatment of liquid acid residues obtained as a bye
product in cleaning iron previous to galvanizing; such liquid residues consist
principally of a solution of free hydrochloric acid and chloride of iron. The object
is to separate the iron from solution and utilize the hydrochloric acid to form chloride
of magnesium.
My invention consists in adding to the liquid acid residues magnesia or a mixture
of magnesia and lime obtained from dolonite by calcination, until the acid is
neutralised and the iron precipitated. I then concentrate the resulting solution of
chlorides of magnesium and calcium together with the oxide of iron in suspension
until the oxide of iron becomes sufficiently dense to readily settle and admit of the
solution being decanted. (The solution of chlorides may with less efficiency be
separated from the oxide of iron without concentration.) 1 dissolve or dilute the
concentrated mass, allow the oxide of iron to settle and decant the chloride of
magnesium or chlorides of magnesium and calcium in a series of tanks.
decanted solution I add a solution of sulphate of magnesia to precipitate the lime as
sulphate; I then separate wash and dry the said sulphate and concentrate the chloride
of magnesium.
The oxide of iron obtained in the first operation is roasted to form pigment.
To the

page_text: COMPLETE SPECIFICATION.
Improvements in Treating Liquid Acid Residues from Galvanizing
Works to Obtain Products therefrom.
1 MICHEL NICHOLAS D'ANDRIA of West Egerton Street Salford in the County of
Lancaster Chemical Manufacturer do hereby declare the nature of this invention and
n what mannor the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention relates to the treatment of liquid acid residues obtained as a bye
product in cleaning iron previous to galvanizing. Such liquid residues consist
principally of a solution of free hydrochloric acid and chloride of iron. The object
is to separate the iron from solution and utilize the hydrochloric acid to form chloride
of magnesium.
My invention consists in adding to the said liquid acid residues magnesia or a
mixture of magnesia and lime obtained from dolomite by calcination until the said
acid is neutralised and the iron precipitated. Uncalcined carbonate of magnesia or
dolomite may be employed for neutralising the free acid, after which calcined magnesia
or magnesia and lime mixed with water to about the consistency of cream is employed
for precipitating the iron from solution. I concentrate in any convenient vessel or
furnace the resulting solution of chloride of magnesia or magnesia and calcium
together with the oxide of iron in suspension until the oxide of iron becomes
sufficiently dense to readily settle. The concentrated magnesia is then diluted by
adding water thereto so as to admit of the solution being decanted or otherwise
separated from the oxide of iron. I find the separation to be most conveniently
effected by means of a filter press or centrifugal machine.
In treating the liquid acid residues to subsequently enable the chlorides of magnesia
or magnesia and lime to be separated from the oxide of iron without concentration, I
neutralise the free acid as hercinbefore set forth then precipitate the iron by adding
milk of calcined magnesia or magnesia and lime to the neutralised solution in any
convenient vessel provided with pipes through which air is blown to agitate and mix
the solution during precipitation of the iron and to per oxidise the proto oxide of
iron. The solution of chlorides and the oxide of iron are separated and treated as
herein mentioned. To the solution of chlorides of magnesium and calcium obtained
as above set forth I add a solution of sulphate of magnesia to precipitate the lime as
sulphate from which I separate by means of a filter press or centrifugal machine
and afterwards concentrate the chloride of magnesium. The oxide of iron from the
first operation I roast to form pigment.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is
First. Treating liquid acid residues obtained as a bye product in cleaning iron
previous to galvanizing with meanasia or mansein and ſims and
1

page_text: iron, chloride of magnesium and when lime is employed, sulphate of lime therefrom
substantially as described.
Second. The joint employment in the treatment of liquid acid residues of a mixture
of magnesia and lime and the subsequent precipitation of the lime by means of
sulphate of magnesia substantially in the manner and for the purpose set forth.
Third. Concentrating chlorides of magnesium and calcium and oxide of iron
obtained in treating acid residues to facilitate the separation of oxide of iron therefrom
substantially as set forth.