Improvements in Purifying or Treating Coal Gas and other Gaseous or Liquid Products of Destructive Distillation, and in Part Applicable in the Alkali Manufacture.
Year: 1888

page_text: Improvements in Purifying or Treating Coal Gas and other Gaseous
or Liquid Products of Destructive Distillation, and in Part
Applicable in the Alkali Manufacture.
We, ARCHIBALD (AMPBELL, of 42 Whittaker Road, Upton Park, in the (County of
Essex, Chemist, and WILLIAM BOYD of 90 Regent Terrace, Stirling Road, Glasgow,
in the County of Lanark, Chemist, do hereby declare the nature of this Invention to
be as follows that is to say :-
Our said Invention which relates principally to the purification or treatment of coal
gas and other gaseous or liquid products of destructive distillation, has for its
objects,-1, the more complete removal of sulphureted hydrogen or polysulphides,
2, the more complete removal of all other volatile sulphur compounds, 3, the removal
of carbonic acid entirely or to a considerable extent, 4, the separation of the whole of
the volatile ammonia as carbonate or sulphate or both and 5, the separation of the
fixed ammonia in a concentrated form and chiefly as sulphocyanide.
.
In carrying out our Invention in the case of coal gas we cause it after leaving the
condenser to pass through a tar separator, a vertical scrubber or a mechanical washer
supplied with condenser liquor and the water from the hydraulic main, in order to
remove as completely as possible all tarry matters present in the gas in a vesicular
condition. The water is continually returned until it acquires a considerable density
and after removal is treated as hereinafter described.
The gas is next passed through one or more scrubbers or washers down which are
passing streams of a mixture of the watery liquor previously separated and artificial
peroxide of manganese in a state of very fine division. The peroxide of manganese
will separate sulphureted hydrogen or polysulphides from the gas but it must in
practice be considerably in excess of the quantity theoretically required for that
purpose. When the peroxide of manganese is in sufficient excess little or no
carbonate of manganese is formed and the mud produced readily absorbs oxygen from
the air

page_text: The manganese mud which has acted on the gas is run into a close well in which it
may settle. The settled mud or the whole of the muddy liquor is next pumped into
an oxidiser or oxidisers which may be such as are used in the Weldon manganese
regenerating process; and a stream of air is continuously pumped through the
mixture and reoxidises the manganese which has been reduced by the sulphureted
hydrogen. The supply of the mixture may be continuous, it being maintained at a
constant level in the oxidisers and a stream equal to the supply running out
continuously from them. The oxidising process is conducted at a temperature of
from 120 to 140 degrees Fahrenheit and during its operation considerable quantities
of ammonia and carbonic acid are expelled, the acid being usually in the proportion of
four equivalents of it to one of the ammonia. These gases are either conveyed to a
scrubber or washer in which a solution of carbonate of ammonia is obtained, or they
may be passed at once into a solution of sulphate of manganese, sulphate of ammonia
and carbonate of manganese being produced. After separating the carbonate of
manganese which is precipitated the solution may be concentrated, and being by
preference slightly acidified will yield a very pure sulphate of ammonia; whilst the
carbonate of manganese on being heated in a current of heated air will be more or
less completely converted into peroxide of manganese.
If the manganese mud is separated from the liquid before oxidising it, we heat the
liquid to a temperature between 140 and 180 degrees Fahrenheit, in a closed vessel,
with mechanical agitation or, as we prefer with agitation by a current of air from the
oxidisers. This treatment splits up the carbonate of ammonia in solution and the
carbonic acid escapes along with a small proportion of the ammonia. The ammonia
remaining in the solution is to a large extent in the free state and after cooling again
is available for removing carbonic acid from the gas. The processes can be arranged
so that most of the carbonic acid can be removed from the gas by means of ammonia
whilst any remaining traces may be got rid of by passing the gas finally through lime
purifiers.
By a modification of our processes we remove carbonic acid from the gas by means.
of what is known a soda waste or alkali waste. This compound which consists chiefly
of sulphide of calcium we grind and make into a cream with water or with the watery
liquid from the tar scrubbers; and we pass it through one or more scrubbers through
which the gas passes immediately after leaving the tar scrubbers. The carbonic acid
in the gas is rapidly absorbed by the lime compounds in the waste setting free
sulphureted hydrogen which passes with the gas into the peroxide of manganese
scrubbers, the sulphur being there separated along with that previously in the gas.
The carbonate of lime formed is removed periodically, boiled to expel volatile
ammonia, settled, filtered, pressed, and washed, or otherwise treated for separating
soluble ammoniacal compounds from the carbonate of lime which may be used again
in the soda process or for making Portland cement.
By using the process last hereinbefore described in combination with certain
processes for obtaining chlorine described in a Provisional Specification accompanying
an application by us for Letters Patent to be filed at the same time as the present
application nearly all the sulphur and carbonate of lime used in the Leblanc alkali
process can be regenerated and used over again repeatedly.
The reoxidised manganese mud after being cooled is again run through the gas
purifying scrubbers to effect the removal of further quantities of sulphur. The mud
becomes highly charged with sulphur in a state of fine division, and as is well known
free sulphur in a solution of ammonia exercises a powerful influence in removing
bisulphide of carbon from coal gas. The result is that the bisulphide of carbon is
very completely removed in the form of sulphocarbonates and sulphocyanides of
ammonium. By the described processes all sulphur compounds are very completely
removed from the gas.
The sulphur when sufficiently accumulated in the manganese mud may be separated
' in various ways. According to one plan the mixture is run into a closed vessel and
is boiled to expel free ammonia. When all the animonia has been expelled the steam
outlets are closed and the mixture is subjected to a pressure of between 30 and

page_text: 40 pounds per square inch, the temperature being high enough to melt the sulphur.
When the proportion of sulphur present is not enough for it to run together when
melted, the boiled mixture may be pressed into cakes and the manganese may be
dissolved out with acid leaving the sulphur as a nearly pure mud which may
be readily and completely melted in a closed vessel. Or the pressed cakes may be
immersed in a solution of chloride of calcium or other suitable salt boiling at a higher
temperature than that at which sulphur melts. In such a solution the sulphur will
freely melt and run together and can be drawn off at intervals. The manganese mud
is afterwards washed free from the salt and then reintroduced into the cycle of
operations.
.
The liquid associated with the manganese mud and which continuously circulates
through the various parts of the apparatus, will gradually increase in density by the
accumulation of fixed salts of ammonium chiefly the sulphocyanide; and for the
purpose of obtaining such salts portions of the liquid are periodically taken out of
circulation. It will generally be found that the quantity of water in circulation
increases but if any requires to be added we prefer it to be in the form of steam or
water condensed from steam in order to keep the liquid as free as possible from
sulphates chlorides and other objectionable salts, and so that a solution will be
obtained containing almost exclusively pure sulphocyanide of ammonium. We believe
it to be practically possible by our process to obtain from gas liquors at once and
directly the valuable salt sulphocyanide of ammonium, by filtration, evaporation and
crystallisation.
In dealing with ammoniacal liquor as at present obtained from gas works coke
ovens. blast furnaces, shale works, and similar sources, we mix the ammoniacal liquor
with peroxide of manganese to remove sulphureted hydrogen, or we distil it and pass
the ammonia and steam into a scrubber through which peroxide of manganese is
passed; and then if sulphate of ammonia is to be made pass it into a solution of
sulphate of manganese. The incondensible gases which are at present burned under
retorts or in furnaces, may be treated in a manganese scrubber to remove sulphur and
other impurities as in the herein before described treatment of coal gas, and any
ammonia in such gases and which is now lost may also be collected.
Dated this Twelfth day of July 1888.
EDMUND HUNT,
Applicants' Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in Purifying or Treating Coal Gas and other Gaseous
or Liquid Products of Destructive Distillation, and in Part
Applicable in the Alkali Manufacture..
We, ARCHIBALD CAMPBELL, of 42 Whittaker Road, Upton Park, in the County
of Essex, Chemist, and WILLIAM BOYD, of 90 Regent Terrace, Stirling Road,
Glasgow, in the County of Lanark, 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, that is to say :-
Our said Invention which relates principally to the purification or treatment of coal
gas and other gaseous or liquid products of destructive distillation, has for its objects,
1, the more complete removal of sulphureted hydrogen or polysulphides, 2, the more
complete removal of all other volatile sulphur compounds, 3, the removal of carbonic
acid entirely or to a considerable extent, 4, the separation of the whole of the volatile
ammonia as carbonate or sulphate or both; and 5, the separation of the fixed
ammonia in a concentrated form and chiefly as sulphocyanide.
In carrying out our Invention in the case of coal gas we cause it after leaving
the condenser to pass through a tar separator, a vertical scrubber, or a mechanical
washer supplied with condenser liquor and the water from the hydraulic main, in
order to remove as completely as possible all tarry matters present in the gas in a
vesicular condition. The water is continually returned until it acquires a considerable
density, and after removal is treated as hereinafter described.
The gas is next passed through one or more scrubbers or washers down which are
passing streams of a mixture of the watery liquor previously separated and artificial
peroxide of manganese in a state of very fine division. The peroxide of manganese
will separate sulphureted hydrogen or polysulphides from the gas, but it must in
practice be considerably in excess of the quantity theoretically required for that
purpose. When the peroxide of manganese is in sufficient excess little or no
carbonate of manganese is formed, and the mud produced readily absorbs oxygen
from the air.
The manganese mud which has acted on the gas is run into a close well in which
it may settle. The settled mud or the whole of the muddy liquor is next pumped
into an oxidiser or oxidisers which may be such as are used in the Weldon manganese
regenerating process; and a stream of air is continuously pumped through the
mixture and reoxidises the manganèse which has been reduced by the sulphureted
hydrogen. The supply of the mixture may be continuous, it being maintained at a
constant level in the oxidisers and a stream equal to the supply running out
continuously from them. The oxidising process is conducted at a temperature of
from 120 to 140 degrees Fahrenheit and during its operation considerable quantities
of ammonia and carbonic acid are expelled, the acid being usually in the proportion
of four equivalents of it to one of the ammonia. These gases are either conveyed
to a scrubber or washer in which a solution of carbonate of ammonia is obtained, or

page_text: they may be passed at once into a solution of sulphate of manganese, sulphate of
ammonia and carbonate of manganese being produced. After separating the
carbonate of manganese which is precipitated the solution may be concentrated, and
being by preference slightly acidified will yield a very pure sulphate of ammonia ;
whilst the carbonate of manganese on being heated in a current of heated air will be
more or less completely converted into peroxide of manganese.
If the manganese inud is separated from the liquid, before oxidising it, we heat the
liquid to a temperature between 140 and 180 degrees Fahrenheit, in a closed vessel,
with mechanical agitation, or as we prefer with agitation by a current of air from
the oxidisers. This treatment splits up the carbonate of ammonia in solution and
the carbonic acid escapes along with a small portion of the ammonia. The ammonia
remaining in the solution is to a large extent in the free state and after cooling
again is available for removing carbonic acid from the gas. The processes can be
arranged so that most of the carbonic acid can be removed from the gas by means of
ammonia whilst any remaining traces may be got rid of by passing the gas finally
through lime purifiers.
or
By a modification of our processes we remove carbonic acid from the gas by means
of what is known as soda waste or alkali waste. This compound which consists
chiefly of sulphide of calcium we grind and inake it into a cream with water or with
the watery liquid from the tar scrubbers; and we pass it through one
more scrubbers through which the gas passes immediately after leaving the tar
scrubbers. The carbonic acid in the gas is rapidly absorbed by the lime compounds
in the waste setting free sulphureted hydrogen, which passes with the gas into the
peroxide of manganese scrubbers, the sulphur being there separated along with that
previously in the gas. The carbonate of lime formed is removed periodically, boiled
to expel volatile ammonia, settled, filtered, pressed, and washed, or otherwise treating
for separating soluble ammoniacal compounds from the carbonate of lime which
may be used again in the soda process or for making Portland cement.
By using the process last herein before described in combination with certain
processes for obtaining chlorine described in our Complete Specification No. 10187
of 1888, nearly all the sulphur and carbonate of lime used in the Leblanc alkali
process can be regenerated and used over again repeatedly.
The reoxidised manganese mud after being cooled is again run through the gas
purifying scrubbers to effect the removal of further quantities of sulphur. The mud
becomes highly charged with sulphur in a state of fine division, and as is well
known free sulphur in a solution of ammonia exercises a powerful influence in
removing bisulphide of carbon from coal gas. The result is that the bisulphide of
carbon is very completely removed in the form of sulphocarbonates and sulpho-
cyanides of ammonium. By the described processes all sulphur compounds are very
completely removed from the gas.
The sulphur when sufficiently accumulated in the inanganese mud may be separated
in various ways. According to one plan the mixture is run into a closed vessel and
is boiled to expel free ammonia. When all the aminonia has been expelled the
steam outlets are closed and the mixture is subjected to a pressure of between
30 and 40 pounds per square inch, the temperature being high enough to melt the
sulphur. When the proportion of sulphur present is not enough for it to run
together when melted; the boiled mixture may be pressed into cakes and the
manganese may be dissolved out with acid leaving the sulphur as a nearly pure mud
which may be readily and completely melted in a closed vessel. Or the pressed
cakes may be immersed in a solution of chloride of calcium or other suitable salt
boiling at a higher temperature than that at which sulphur melts. In such a solution
the sulphur will freely melt and run together and can be drawn off at intervals. The
manganese mud is afterwards washed free from the salt and then reintroduced into
the cycle of operations.
The liquid associated with the manganese mud and which continuously circulates
through the various parts of the apparatus, will gradually increase in density by the
accumulation of fixed salts of ammonium, chiefly the sulphocyanide, and for the

page_text: purpose of obtaining such salts portions of the liquid are periodically taken out of
circulation. It will generally be found that the quantity of water in circulation
increases but if any requires to be added we prefer it to be in the form of steam or
water condensed from steam in order to keep the liquid as free as possible from
sulphates, chlorides, and other objectionable salts, and so that a solution will be
obtained containing almost exclusively pure sulphocyanide of ammonium. We
believe it to be practically possible by our process to obtain from gas liquors at
once and directly, the valuable salt sulphocyanide of ammonium, by filtration,
evaporation, and crystallisation.
In dealing with ammoniacal liquor as at present obtained from gas works, coke
ovens, blast furnaces, shale works, and similar sources, we mix the ammoniacal
liquor with peroxide of manganese to remove sulphureted hydrogen, or we distil
it and pass the ammonia and steam into a scrubber through which peroxide of
manganese is passed; and then if sulphate of ammonia is to be made pass it into
a solution of sulphate of manganese. The incondensible gases which are at present
burned under retorts or in furnaces, may be treated in a manganese scrubber to
remove sulphur and other impurities as in the hereinbefore described treatment of
coal gas, and any ammonia in such gases and which is now lost may also be
collected.
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 :-
1. The process for removing sulphureted hydrogen or polysulphides from coal or
other gas in which peroxide of manganese is used, substantially in the manner herein-
before described.
2. The simultaneous oxidation of the mixture of manganese mud and ammoniacal
liquor and the expulsion therefrom of ammonia and carbonic acid with the aid of heat
substantially as hereinbefore described.
3. The treatment of the carbonate of ammonia with sulphate of manganese and
the separation, concentration, and crystallisation of the resulting sulphate of ammonia,
substantially as and for the special purposes herein before described.
4. The treatment of the ainmoniacal liquor when separated from the manganese
mud with heat and with agitation by air or otherwise to expel carbonic acid, combined
with the application of the ammonia remaining in the liquor to separate carbonic
acid from fresh portions of gas substantially as herein before described.
5. The removal of carbonic acid from coal or other gas. by means of sulphide of
calcium or alkali waste, combined with the removal of the resulting sulphureted
hydrogen by means of peroxide of manganese substantially as and for the purposes
hereinbefore described.
6. The reconversion of the lime of the alkali waste to carbonate combined with the
separation of the sulphur from the manganese mud in the manner and for the purpose
of being used over again in the alkali manufacture substantially as hereinbefore
described.
7. The separation of sulphocyanide of ammonium from the gas liquor substantially
in the manner herein before described.
8. The complete combination or cycle of processes for treating coal or other
gases whether ammonia or alkali waste be used for removing carbonic acid substan-
tially as herein before described.
Dated this Eleventh day of April 1889.
EDMUND HUNT,
Applicants' Agent.