IMPROVEMENTS IN TREATING WASTE LIME IN ORDER TO SEPARATE SULPHUR COMPOUNDS THEREFROM
Year: 1882

page_text: LETTERS PATENT to George Robertson Hislop, of Paisley, in the County of
Renfrew, North Britain, Gas Manager, for an invention of "IMPROVEMENTS
IN TREATING WASTE LIME IN ORDER TO SEPARATE SULPHUR COMPOUNDS
THEREFROM"
PROVISIONAL SPECIFICATION left by the said George Robertson Hislop
at the Office of the Commissioners of Patents on the 10th June 1882.
GEORGE ROBERTSON HISLOP of Paisley in the County of Renfrew North Britain
Gas Manager "IMPROVEMENTS IN TREATING WASTE LIME IN ORDER TO SEPARATE
SULPHUR COMPOUNDS THEREFROM"
This Invention has for its object the treatment of Lime for the separation of the
Sulphur Compounds which become combined therewith in connection more
especially with the purification of Coal gas and for the recovery of the Sulphur and
the Lime.
In recovering the Spent Lime of gas Works as described in the Specifications
filed in pursuance of Letters Patent granted to the said George Robertson Hislop
No 1542 dated 20th April 1877 and in the Specification filed in pursuance of
Letters Patent granted to the said George Robertson Hislop and William Young
No 1591 dated 20th April 1878 it is found that the proportion of Sulphate of
Lime gradually although it may be slowly increases impairing its efficacy as a
purifying agent and ultimately rendering it unfit for further use for the purification
of gas and my present Invention is to remedy this defect and render the Lime
available ad-infinitum as a purifying Agent or for any other purpose to which
Lime is applied.
I mix the Lime so charged with Sulphate with certain proportions of any
Carbonaceous matter or matters such as Coal tar, oil pitch, Coal or Coke; I
preferably. use Coke or Breeze when the spent Lime of gas Works is being recovered
these being always at hand I preferably first reduce such solid matter by grinding
or other means to about the size of Peas and mix the same with the Lime
containing Sulphate of Lime in the proportion of from one fifth to one tenth by
measure of Lime before treatment by heat in regenerating Chambers and under
Dinn 4.1

page_text: such treatment in the presence of Carbonaceous matter I wholly effect the decom-
position of the Sulphate of Lime present in the quantity of Lime operated on
converting the same into the condition of Sulphide of Calcium-The Carbonic
Acid of the Calcium Carbonate having also been driven off Calcium and Calcium
Sulphide are obtained After slaking with water while hot and preparing by water
in the usual way I employ the Lime containing the Calcium Sulphide for the
purification of gas from bisulphide of Carbon and the reduction of the Sulphur
Compounds in illuminating or other gas or when not required for the removal of
the Sulphur Compounds in particular I rank the purifier containing such Sulphide
of Calcium as 1st or 2nd purifier of the series and decompose the Calcium Sulphide
by the Carbonic Acid in the foul gas and drive the Sulphuretted Hydrogen thereby
liberated into Oxide of Iron in the usual way; when the said Lime has been
sufficiently Carbonated and the Sulphur expelled the spent Lime is removed from
the Purifiers and recovered by my processes described in the aforesaid Specifications
over and over again until the Sulphate has been found to increase to some extent
when its decomposition and removal may be effected as described
The method of treatment is also applicable to Gypsum, Alkali Waste or any
similar waste in which the Sulphur has been Oxidized and combined therewith as
Sulphate and for the application of such Gypsum Alkali or other wastes after such
treatment for the purification of illuminating or other Gas and for the recovery of
the Sulphur and the Lime as described The Lime recovered from such Compounds
may either be further employed in the purification of Gas or disposed of for Building
or agricultural purposes the same having (preferably) been previously ground while
hot in a pan-mill or otherwise-Instead of discharging the Calcium Sulphide by
Carbonic Acid in the process of gas purification it may be done by furnace gases or
by the Carbonate Acid Gas from Lime Kilns

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Robertson Hislop in the Great Seal Patent Office on the
9th December 1882.
GEORGE ROBERTSON HISLOP, of Paisley in the County of Renfrew, North Britain,
Gas Manager.
"IMPROVEMENTS IN TREATING WASTE LIME IN ORDER TO SEPARATE
SULPHUR COMPOUNDS THEREFROM
"
My said Invention has for its object the treatment of lime for the decomposition.
of the sulphur compounds which become combined therewith in connection more
especially with the purification of coal gas and for the recovery of the sulphur and
the Lime.
In recovering the spent Lime of Gas Works as described in the Specification
filed in pursuance of Letters Patent granted to me the said George Robertson
Hislop, No. 1542, dated 20th April, A.Ď. 1877, and also in the Specification filed
in pursuance of Letters Patent granted to me the said George Robertson Hislop
and William Young No 1591, dated 20th April, A.D. 1878, it is found, that the
proportion of Sulphate of Lime gradually, although it may be slowly, increases
thus impairing its efficiency as a purifying Agent and ultimately rendering it unfit
for further use for the purification of Gas. In order to remedy this defect and
render the Lime continuously available as a purifying agent or for any other
purpose to which Lime is applied, I mix the Lime so charged with Sulphate with
varying proportions of any carbonaceous matter, or matters, such as Coal Tar, Oil,
Pitch, Coal, Coke, or other carbonaceous matter, I preferably use Coke or "Breeze,"
when the spent Lime of Gas Works is being recovered these being always at hand.
- I preferably first reduce such solid matters by grinding or other means to such a
size as will pass through a half inch mesh riddle or thereby and I mix such
carbonaceous matter with the Lime containing Sulphate of Lime in the proportion
of from one fifth to one thirtieth or less by measure of Lime before treatment by
heat in the regenerating chambers depending on the quantity of Sulphate to be
decomposed and under such treatment in the presence of carbonaceous matter I
wholly effect the decomposition of the Sulphate of Lime present in the quantity of
Lime operated on, converting the same into the condition of Calcium Sulphide.
The Carbonic Acid of the Calcium Carbonate having also been driven off, Calcium.
and Calcium Sulphide are obtained. After Slaking with water while hot and
subsequently further preparing by water in the usual way. The Lime may be
employed for the purification of Gas from Bisulphide of Carbon and the reduction
of the Sulphur compounds in illuminating or other gas, or if containing a small
proportion of the Sulphide it may be employed for general purification and in the
usual manner.
But when the Sulphide present is large in quantity I preferably
rank the purifier containing such Sulphide as first or second Purifier of the series
and decompose the Calcium Sulphide by the Carbonic acid in the foul gas and
drive the Sulphuretted hydrogen thereby liberated forward into oxide of Iron in
the usual way and collect the Sulphur; and when the said Lime has been
sufficiently carbonated and the Sulphur discharged the spent Lime is removed from
the Purifiers and recovered by any of the processes described in the aforesaid
Specifications No 1542, A.D. 1877, and No 1591, A.D. 1878, over and over again
until the accumulation of Sulphate again renders its decomposition and removal
necessary.
The method of treatment is also applicable to native Sulphate of Lime commonly
known as Gypsum, to Alkali waste, or to any similar substance in which the
Sulphur has been oxidized and combined therewith as Sulphate, and for the

page_text: application of such Gypsum, Alkali, or other waste after such treatment for the
purification of Gas or otherwise and for the recovery of the Sulphur and the Lime
as described, and these wastes may either be treated separately or in combination
with each other or with spent Gas Lime. The Lime recovered from such
compounds may either be further employed in the purification of Gas or disposed
of for building or agricultural purposes, the same having (preferably) been pre-
viously ground after treatment and while hot in a Pan-mill or otherwise. Instead
of discharging the Sulphur from the Calcium Sulphide by Carbonic acid in the
process of Gas purification it may be effected by furnace Gases or by the Carbonic
Acid gas from Lime Kilns or other sources.
Having now described and particularly ascertained the nature of my said
Invention and the system mode or manner in or under which the same is or may
be used, or practically carried into effect, I would observe in conclusion that what
I consider to be novel and original and therefore claim as the Invention secured to
me by the hereinbefore in part recited Letters Patent is :-
First. The use of carbonaceous matter to effect decomposition of Sulphate of
Lime as herein before particularly described.
Second. The treatment for the recovery of Sulphur and Lime as hereinbefore
described.
Third. The treatment of other Sulphur. Wastes and Gypsum for the recovery of
the Sulphur and the application of the Lime all as hereinbefore particularly
described.
In witness whereof I the said George Robertson Hislop, have hereunto set
my hand and seal this Seventh day of December in the year of Our Lord
One thousand eight hundred and eighty two.