Improvements in the Treatment of Lime Refuse from Alkali Works, to Render it Suitable for the Manufacture of Cement, and in Apparatus Employed therein.
Year: 1889

page_text: Date of Application, 3rd Jan., 1889
Complete Specification Left, 3rd Oct., 1889-Accepted, 3rd Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Lime Refuse from Alkali Works,
to Render it Suitable for the Manufacture of Cement, and in
Apparatus Employed therein.
We, JAMES HARGREAVES. Chemist, THOMAS ROBINSON, Ironfounder, and JOHN
HARGREAVES, Chemist, all of Widnes, in the County of Lancaster, do hereby declare
the nature of this invention to be as follows:-
Our invention relates to improvements in the treatment of Lime refuse from the
manufacture of alkali to render it suitable in the production of cement. It also relates
as aforesaid to apparatus.
Carbonate of lime resulting from the treatment of alkali waste with carbonic acid
gas to eliminate sulphur therefrom, usually contains sulphur or sulphur and alkali
which must be eliminated previous to its employment in the manufacture of high
class cement. The sulphur for the greater part exists as free sulphur, sulphide of
iron and insoluble oxy-sulphur salts of lime.
First. When carbonated alkali waste is mixed with sufficient water to form a
magma or thin paste, we oxidise the sulphur compounds when contained in a tank or
like, vessel by blowing air through the magma or alternatively we mix with the
magna at suitable temperature, oxidising agents such as chlorine, bleaching powder,
manganate of soda or lime which takes the place of air.
Second. To oxidise the sulphur compounds in moist or semi-dry carbonated alkali
waste we blow air through the mass when in heaps open to the atmosphere, by means
of air pipes placed near the bottom of the said heaps or masses.
Third. By oxidation of the sulphur compounds an amount of free sulphur is
liberated in addition to that originally contained in the carbonated alkali waste
which free sulphur we by means of lime or lime sludge from caustic soda manufacturé
or from other source enable the water to take into solution the said sulphur which we
eliminate by washing.
Fourth. To jointly eliminate sulphur and alkali contained in lime sludge from
caustic soda we oxidise the sulphides by means of air or oxidising agents herein-
before described under the first and second parts and render soluble and take into
solution the resulting free sulphur or oxides of sulphur by means of the alkali
invariably present in such lime sludge and jointly eliminate the alkali and dissolved
sulphur by washing with water.
Fifth. To render more efficient the continuous filter described in the specification
under Patent No. 17363 Nov. 29, 1888, we fix one or more internal discs, blocks
tubes or plates in the interior of the outer tube or vessel forming the continuous filter
and avoid direct passage of imperfectly filtered material through the centre of said
outer tube or vessel. The said inner disc, block; tube or plate may be perforated,
covered with filter cloth which is suitably protected, such as by means of wire gauze
and the perforations serve conjointly with or may be substituted for perforations in
the outer tube or vessel as outlets for water expressed from the materials to be
employed in the manufacture of cement.
To obtain from the said continuous filter a regular outlet of semi-dried slurry, a
pump or the equivalent is emploved to cause the pressure on the slurry to pulsate of
be measured upon its entrance into the filier; the outlet is also regulated and when
desired to obtain the semi-dried slurry in small pieces it is passed through a perforated
block at the exit end of the filter.
Sixth. At one operation to intimately mix clay with, and render capable of joint
elimination by washing with water the sulphur and soluble alkali contained in
carbonated alkali waste, lime sludge from caustic soda or a mixture of the two, we

page_text: employ apparatus for mixing slurry described under the first part of our specification
No. 17363 Nov. 29, 1888 and use perforated pipes for forcing air through the slurry
so as to oxidise the sulphur compounds whilst sufficient carbonate of soda caustic
soda or caustic lime is present in the slurry to dissolve the sulphur. We hasten the
processes by heating the slurry to about 100 deg. Fah. The alkali and sulphur in
solution is eliminated by means of a filter and the slurry dried, roasted, and ground
to form cement.
Dated this Second day of January 1889
Per pro J. T. KING,
*J. Johnson,
Agent.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Lime Refuse from Alkali Works,
to Render it Suitable for the Manufacture of Cement, and in
Apparatus Employed therein.
We JAMES HARGREAVES, Chemist, THOMAS ROBINSON, Ironfounder, and JOHN
HARGREAVES, Chemist all of Widnes in the county of Lancaster 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 :-
Our invention relates to improvements in the treatment of lime refuse from the
manufacture of alkali to render it suitable in the production of cement. It also relates
as aforesaid to apparatus.
Carbonate of lime resulting from the treatment of alkali waste with carbonic acid
to eliminate sulphur therefrom usually contains sulphur or sulphur and alkali which
must be eliminated previous to its employment in the manufacture of high class
cement. The sulphur for the greater part exists as free sulphur sulphide of iron and
insoluble oxysulphur salts of lime.
First. When carbonated alkali waste is mixed with sufficient water to form a
magma or other paste we oxidise the sulphur compounds when the magma or paste is
contained in a tank or like vessel as hereinafter described by blowing air through the
magma or alternately we mix with the magma at suitable temperature, oxidising
agents such as chlorine, bleaching powder, manganates of soda or lime which take
the place of air.
In carrying the said first part of our invention into effect, when oxidising by means
of air, we place a sufficient depth of magma (not less than five feet) direct from the
carbonator whilst hot in the tank or like vessel-with such a depth sufficient pressure
of air must be injected from the bottom upwards through the magma to dissolve
oxygen and ensure oxidation of sulphur compounds by which free sulphur is liberated
and iron oxidised.
As hereinafter described under the sixth head and in views Figs. 1 and 2 of the
drawings herewith air is injected through perforated pipes to more thoroughly dis-
seminate the air through the magma which is preferably kept warm by means of steam
injected amongst the mass.
When oxidising agents other than air are employed we inject chlorine add bleaching
powder or other hypochlorite to the magma when warm or cool or when manganates
are used a higher temperature may be employed.
Figure 1 is a vertical section and Fig. 2 a horizontal plan of apparatus under this
part of our invention a. tank b. air pipe c. perforated pipes d. injector e. withdrawal
valve or sluice f. doors to admit of easy cleaning of the air pipes. Instead of an
injector a pump may be used..
Second. To oxidise the sulphur compounds in moist or semi dry carbonated alkali
waste we blow air through the mass when in heaps open to the atmosphere by means
of air pipes placed near the bottom of the said heaps or masses.
The pipes are perforated and the air preferably warm. The action on the mass is

page_text: such that the gelatinous silica present is rendered pulverulant and subsequent washing
and filtration are facilitated.
Third. By oxidation of the sulphur compounds as herein before described an amount
of free sulphur is liberated which free sulphur in addition to that originally contained
in the carbonated alkali waste we by means of lime or lime sludge from caustic soda
manufacture or from other source enable the water to take into solution the said
sulphur which we eliminate by washing.
The lime sludge is preferably added after the carbonate of soda present in the
carbonated alkali waste has been causticised. Another convenient source of lime as a
sulphur solvent is the hydrosulphide obtained by the well known method of steaming
alkali waste under pressure which added to the oxidised carbonated alkali waste
dissolves free sulphur forming poly sulphide of calcium. Or again and by preference,
the soda sulphur solvents described under the following sixth head may be used.
After addition of solvent to the magma the mass is heated with steam and agitated
to dissolve sulphur which is eliminated along with the alkali by washing and filtering,
then mixed with clay and made into cement in the ordinary way.
Fourth. To jointly eliminate sulphur and alkali contained in lime sludge from
caustic soda manufacture wo oxidise the sulphides by means of air or oxidising agents
bereinbefore described under the first or second parts and render soluble and take
into solution the resulting free sulphur or oxides of sulphur by means of the alkali
invariably present in such lime sludge and jointly eliminate the alkali and dissolved
sulphur by washing with water.
Oxidation of lime sludge by means of air is the well known Gossage-Hargreaves
system. When such system is used we employ the vessel with perforated pipes shewn
by Figs. 1 and 2 of the drawings.
When the sulphur present in lime sludge is combined with zinc it is necessary to
employ the oxidising agents herein before named the most suitable being bleaching
powder, as addition of chloride of calcium in any convenient form in quantity
insufficient to precipitate sulphate of lime by reaction upon sulphate of soda present,
greatly facilitates the elimination of alkali by washing and filtering as also by
volatilisation as chloride of sodium when roasting to form cement.
Fifth. To render more efficient the continuous filter described in the specification
under Patent No. 17363 Nov. 29/88' we fix one or more internal disc, block tube or
plate in the interior of the outer tube or vessel and avoid direct passage of imperfect
filtered material through the centre of the said outer tube or vessel. The said inner
disc, block tube or plate may be perforated, covered with filter cloth which is suitably
protected such as by means of wire gauze and the perforations serve conjointly with
or be substituted for perforations in the outer tube or vessel as outlets for water
expressed from the materials to be employed in the manufacture of cement.
To obtain from the said continuous filter a regular outlet of semi-dry slurry or
slurry material a pump or the equivalent is employed to give pulsatory pressure on
the slurry or slurry material. The quantity of slurry or material admitted is so
regulated that with the assistance of the block the slurry or material is prevented
from rushing out at the delivery end. The outlet is also regulated, and when desired
to obtain the semi dry slurry in small pieces is passed through a perforated block
at the exit end of the filter. An important feature under this head consists of a
filter with perforated concentric walls adapted to allow of expression of water
exteriorly and interiorly.
Fig. 3 is a longitudinal section and Fig. 4 a transverse section of a continuous filter
under our invention shewing the improvements on our patent filter and also by dotted
lines what we designate an internal filter-1. is a perforated casing 2 filtering surface
composed of a layer of filter cloth between two layers of wire gauze 3 shaft block
or tube fixed at or near the centre of the casing to prevent escape of imperfectly
filtered material along the centre. A perforated tube covered with filtered cloth may
be placed over the tube 3 to give additional filtering surface as shown by the dotted
line 4 the liquid escaping through the tube 3. The slurry is forced into the casing 1

page_text: through the inlet 5 and gradually passes along to the outlet
the liquid separated
escaping through the perforations in the casing, 7 slide for regulating the outlet,
8 band for conveying away the filtered material."
When internal filtration is not desired the internal perforated tube is.dispensed with.
The outlet of filtered material may be regulated by means of a contractable door way
or sluice.
Sixth. At one operation in one vessel to intimately mix clay, preferably added in
the form of slip, with carbonated alkali waste or lime sludge and render capable of
joint elimination by washing with water the sulphur and soluble alkali contained in
the said carbonated alkali waste, lime sludge from caustic soda, manufacture or a
mixture of the two, we employ the apparatus described under the first part of our
specification No. 17,363 November 29th 1888 and use perforated pipes for forcing air
through the slurry so as to oxidise the sulphur compounds. Sufficient carbonate of
soda caustic soda or caustic lime (soda being preferred) is present or added, to the
slurry to dissolve the sulphur or the soda or lime solvent of sulphur described under
the third head may be used. We hasten the process by heating the slurry to 100 deg.
Fah. or it may be higher which greatly facilitates subsequent filtration and renders
the filtered semi dry slurry more compact and better suited for being roasted into
cement. The alkali and sulphur in solution are eliminated whilst hot by means of a
filter and the slurry dried, roasted and ground to form cement by any usual or known
method. The apparatus employed is preferably such as is described in Figs. Nos. 1
and 2 on the drawings herewith perforated pipes marked c being used.
In some cases sufficient soda is left in the alkali waste before carbonating and such
soda is causticized in the usual way by the addition of lime. And again the soda
sulphur solvent may be obtained by steaming and washing the contents of a nearly
spent black ash vat, such solution consists mainly of some caustic soda admixed
largely with mono-sulphide of sodium.
Gelatinous silica in carbonated alkali waste is dissolved by soda sulphur solvents,
or is rendered pulverulent with lime thus facilitating subsequent washing and filtration.
of carbonated alkali waste.
The means employed for eliminating sulphur and alkali described under the
several heads in this specification are hastened by steaming agitating and heating the
inass.
On account of the large amount of gritty matter present in carbonated alkali
waste, and to allow such grit to settle and be separated we find it necessary when
cement is to be made to add more water than is usually the case and make the slurry
more fluid.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
I. Oxidising sulphur compounds in carbonated alkali waste when the latter is mixed
with water and contained in a tank or tanks by blowing air through perforated pipes
amongst the mass for the purpose described under the first head.
11. Oxidising sulphur compounds in carbonated alkali waste or lime sludge by
means of oxidising agents such as chlorine hypochlorites or manganates of lime or
soda for the purpose described under the first head.
III. Oxidising sulphur compounds in moist or semi-dry carbonated alkali waste by
blowing air through heaps of such waste when open to the atmosphere substantially
as described under the second head.
IV. Oxidising sulphur compounds in carbonated alkali waste afterwards or during
oxidation dissolving free sulphur by means of lime or lime sludge and subsequently
eliminating the dissolved sulphur with the water substantially as described and for the
purpose set forth under the third head.
V. Oxidising sulphur compounds in lime sludge by means of oxidising agents for
purpose substantially as described under the fourth head.

page_text: VI. To facilitate the elimination of alkali from lime sludge by chlorinizing the
alkali present for the purpose described under the fourth head; by chlorinizing we
mean forming a chloride of the alkali.
VII. The improvements herein described in filters substantially as described under
the fifth head..
VIII. Giving pulsatory motion to slurry or cement materials when entering a con-
tinuous filter by means of pumps substantially as and for the purpose set forth under
the fifth head.
IX. Regulating the outlet of pressed cement material from continuous filters sub-
stantially as described under the fifth head.
X. At one operation intimately mixing carbonated alkali waste, lime sludge or a
mixture of the two with clay and dissolving sulphur by means of sulphur solvent
substantially as and for the purpose described under the sixth head.
XI. Dissolving and eliminating sulphur from carbonated alkali waste by means of
soda sulphur solvents substantially as set forth under the sixth head.
XII. The combination of the processes herein described of oxidising dissolving and
eliminating sulphur and sulphur compounds all substantially as herein described."
XIII. The combination of the several improvements herein described and claimed
as a whole for the purpose set forth.
Dated the 2nd October 1889
Per pro J. T. KING,
J. Johnson,
Agent.