752

THE COLLIERY GUARDIAN.

April 9, 1915.

The exciter generator has an output of about 15 kw.
In addition ito the necessary excitation energy at 220
volts required by the winding motor and variable voltage
generator, the exciter generator also supplies current
for the air compressor motor and emergency brake
magnet, etc. The above three machines forming the
converter set are mounted on a common bedplate, and
run at a full load speed of about 786 revolutions per
minute.

For supplying the necessary compressed air for the
working brakes, a small continuous current 7 b.h.p.
motor-driven air 'compressor, with receiver, is installed
in the basement below the floor of the winding engine
house. The working of the compressor is automatically
controlled by the pressure of the air in the receiver. The
switchboard is situated near the converter set, and con-
sists of two black enamelled slate panels, on which are
mounted the various instruments and apparatus for
operating the complete plant. All high-tension appa-
ratus is arranged in a stone built cell at the back of the
board, so that only low-tension apparatus is on the front
of the panels.

The complete control of the winder is effected by a
three-lever control frame, mounted on the driver’s plat-
form, which is directly behind the drum, and elevated to
enable the driver to obtain a clear view of the cages at
the decking level. At Lumley Pit the driver’s platform
has been boxed in, thus forming a separate cabin, in
which are all signals, etc., as well as a “ Karlick ” tacho-
graph, so that the driver iis not disturbed by any noise
due to the running of the generator set.

The Ward-Leonard system of control is, of course, the
only system which gives absolute control and that
degree of safety which is so essential for colliery work,
and on this account it has largely been adopted in a
number of winding plants in this country and abroad.
The most important feature of the control is that it
enables the speed and direction of rotation of the wind-
ing motor to be determined entirely by the position of
the driver’s control lever; and this holds good whatever
may be the load, or whether this is being raised or
lowered. Further, a strong electrical braking effect is
obtained by moving the control lever towards the “ off ”
position, the motor acting as a generator, and returning
energy through the converter set to the line; in fact, in
actual practice a skilled driver will seldom make use of
the ordinary mechanical brakes, as, of course, the action
and effect are exactly the same as “reversing” in the case
of a steam engine, with the important difference that in
the latter the energy is wasted, whereas in the former the
energy is utilised by returning it to the line through the
converter set. The slow speed required for rope and
shaft inspection purposes is readily obtained by moving
the control lever only slightly from the “ off ” position.
As the controller has only to deal with the ‘ ‘ exciting ’ ’
current of the generator, it may be made small and
simply constructed, and, therefore, is easily operated by
the control lever without the use of auxiliary gear.

In front of the driver’s platform is placed a Siemens
patent depth indicator, with overwind gear, which is
provided with accelerating and retarding devices to
prevent too rapid acceleration or over-running at the end
of the wind. The depth indicator and the control lever
are interlocked in such a way that it is impossible for
the driver to accelerate too rapidly, and, further, the
control lever is brought automatically to the “ off ” posi-
tion, and the brakes are applied at the end of the wind,
should the driver omit to do so. In addition, suitably
arranged emergency and safety devices are provided to
apply the brakes automatically and cut oft the power,
in addition to the usual emergency lever on the driver’s
platform.

The electrical portion of the plant was supplied by
Messrs. Siemens Brothers Dynamo Works Limited, to
whom we are indebted for the illustrations and particu-
lars, whilst the mechanical portion was supplied by
Messrs. Robey and Company Limited, of Lincoln.

Partnerships Dissolved.—The London Gazette announces
the dissolution of the following partnerships :—E. P. Sells
the elder, J. Charrington the elder, E. P. Sells the younger,
J. Charrington the younger, and H. B. Dale, coal merchants,
at Charringtons’ Wharf, Broad-street, Ratcliff, and at Gray’s
Inn-road, London, and elsewhere, under the style of Char-
rington, Sells, Dale and Company, so far as concerns E. P.
Sells the elder; E. S. Wells and A. W. Woolley, electro-
plate manufacturers, at Saint Paul’s-square, Birmingham, .-
under the style of Wells and Company.

Institution of Mining and Metallurgy.—The sixth general
meeting of the 24th session of the Institution of Mining and
Metallurgy will be held at the Rooms of the Geological
Society, Burlington House, Piccadilly, London, W., on
Thursday, April 15, 1915, at 8 p.m. The following papers
will be discussed :—“ The Precipitating Action of Carbon
in Contact with Auriferous Cyanide Solutions,” by Mr. W.
R. Feldtmann; “ Cyaniding of Gold-Silver Ores at Waihi
Grand Junction,” by Mr. Noel Carlesis; “The Effect of
Mineralised Waters in Cyanide Plants,” by Messrs. Thos.
B. Stevens and W. S. Bradley. The final general meeting
of the session will be held on Thursday May 20, 1915.

Manchester Geological and Mining Society.—The ordinary
meeting of the members will be held in the Geological
Lecture Theatre, Beyer Building, at the Manchester Univer-
sity, on Tuesday, April 13, at 6 p.m. The following paper
will be read :—“ The Drift Deposits of Prestwich and
Neighbourhood,” by Mr. J. E. Wynfield Rhodes, B.Sc.; and
the following papers will be open for discussion “ Some
Notes on Supporting the Roof in Coal Mines,” by Mr.
Frank Noel Siddall, H.M. inspector of mines; “Some
Remarks on Mining Education,” by Mr. Noah T. Williams,
B.Sc. The council will meet on the same day at 3 p.m.
at the rooms of the -society.

RIVER POLLUTION IN COLLIERY
DISTRICTS.

The Royal Commission on Sewage Disposal'have just
issued a final report, in which they present a general
summary of the conclusions and recommendations con-
tained in the nine reports already submitted. The
enquiry has extended over a period of 16 years, and three
of the reports deal with the discharge of manufacturing
effluents (3rd, 6th, and 9th reports).

The third report, published in 1903, dealt with the
relations between local authorities and manufacturers,
and it was urged that the duty of providing sewers for
trade effluents should be thrown upon the local authori-
ties, that standards of preliminary treatment by the
manufacturer should be drawn up, and that a central
authority should be appointed to settle differences that
may arise. The Commission further recommended that
rivers boards should be appointed, with authority to
appear before Parliamentary Committees in regard to
any schemes affecting waters in their districts. It was
also recommended that the central authority might, with
the aid of the rivers boards, very properly collect such
information as is available in regard to waste of water
by pumping from mines, etc.

The ninth report is published simultaneously with the
final report, and deals mainly with the discharge of
manufacturing wastes, which for any reason could not
be taken into sewers. It has been found that efficient
means of purification were available in the case of some,
but not all trade liquids. Many wastes, the impurities
of which were mainly in solution, could be considerably
improved by clarification, but could not, in the present
state of knowledge, be thoroughly purified. Hence the
requirement of the existing law that trade wastes should
(subject to certain exceptions) be rendered “ harmless ”
was in many cases impracticable, and the authorities
charged with the duty of administering the law had to
exercise their own discretion in regard to the degree of
purification to be demanded of manufacturers. The
Commission considered therefore that, as in the case of
sewage effluents, there should be prescribed for trade
effluents a standard of purity which should at once be a
guide to the administrative authorities and a security to
the manufacturers in regard to the extent of their obli-
gations. They found, further, that owing to the wide
differences in the character of the various trade wastes,
both as regards their effect upon steam and as regards
the difficulty and expense of treating them, it would be
necessary to consider each kind of trade waste separately
with a view to suggesting an appropriate standard. It
was not regarded as desirable or necessary to prescribe
a graduated system of standards, but that a single
standard for each trade would suffice, provision being
made for raising or lowering the standard where shown
to be necessary in exceptional cases.

Standards of Treatment.

For the purpose of suggesting standards for the
different trade wastes, it has been found convenient to
classify the wastes as follows :—“ (a) Those for which
efficient purification is practicable; (b) those for which
efficient purification is not in the present state of know-
ledge practicable.” In class (a) are included (i.) cases
in which adequate reduction of solids in suspension may
be regarded as efficient purification (e.g., coal washing,
stone quarrying, etc.); and (ii.) cases in which dis-
solved impurities should also be removed (e.g., tin
plating, galvanising, wire drawing, shale oil distillation,
etc.). In class (b) are included, inter alia, waste liquors
resulting from gas and coke production. Gas liquor has
been placed in a separate subdivision because the Com-
mission are not aware of any method of so treating it
that the effluents could properly be discharged direct
into streams.

As regards the standards to be prescribed, the Com-
mission think it impossible to lay down, for each
trade, such a standard as would ensure the complete
purification of rivers, since, in the present state of know-
ledge, the attainment of such a standard would it many
cases be financially impracticable, and therefore useless.
They have thought it useful, however, to suggest limits
of impurity which they believe to.be now practicable,
and which are based upon careful consideration of the
data. These figures, although provisional, and based
upon the present condition of knowledge, should, if pre-
scribed, remain in force for a definite period. At the
und of this period they would be subject to revision,
since admittedly they are inadequate to prevent pollu-
tion of streams, and improved methods of treatment
may meanwhile have been discovered. In the case of
those trades where a standard involving expensive plant
is prescribed, the period might be longer than in those
where only partial means of purification are as yet
known. In the latter case the period could, of course,
be extended if in the meantime no improved methods of
treatment had been discovered.

In regard to coal washing, the Commission thinks that
the effluent should not contain more than four parts of
suspended solids per 100,000. In a number of cases
this standard might have to be relaxed. In the case of
quarries, etc., they suggest provisionally a standard of
six parts suspended solids per 100,000. If it can be
shown, e.g., in the case of small streams near to the sea,
which are not used for fishing, for navigation, for water-
ing. cattle, or for manufacturing purposes, that no
damage is caused by the discharge of waste waters
without treatment, the standard might be relaxed or
wholly dispensed with.

Tin plating, galvanising and wiredrawing wastes are
strongly acid from mineral acid,, and contain much iron
in solution. The stronger liquids should not in any
circumstances be allowed to discharge into streams. The
wash waters should be neutralised and settled. The.
standard for these wash Waters should be six parts per
100,000 suspended solids. .Even after compliance with
this standard, a somewhat yelloW and colloidal liquid
might result. It might possibly have to be softened

before discharge, but the Commission do not think it
necessary'at present to suggest -any standard of hard-
ness. In the case of shale oil distillation, the standards
they suggest are four parts per 100,000 suspended solids
and four parts per 100,000 dissolved oxygen absorption
in five days.

As already stated, the Commission are unable to
suggest a limit of purification for gas liquor. In no
circumstances should the liquor be discharged untreated
into a stream. In some cases purification by percola-
tion through “ bings ” may be sufficient to permit the
discharge of an effluent, but no general pronouncement
can be made on the point. Where no bings exist,
biological treatment on the lines suggested by Dr.
Fowler will lessen very materially the polluting power of
the liquor. Evaporation appears to be the only other
practicable alternative at the present time.

In the case of some trade wastes, additional standards
may have to be imposed. Some further investigation
may be required before such standards — or some of
them—can properly be laid down. These standards
should be looked upon for the most part as special
standards, applicable only to certain rivers or reaches
of rivers where local circumstances call for them. It is
important, however, that the necessity for imposing
them in special cases should be borne in mind when the
general standard is being considered, for in some cases
the special standard may be required more urgently than
the general standard. Several manufacturers have, for
instance, urged that the “ softness ” of a river water is
of greater moment to them than its organic purity. It
will be necessary, also, to have special regard to the
protection of drinking waters against mineral poisons.

In regard to the alterations of the law which would be
necessary to give effect to the proposals, the Commission
have made a number of recommendations. Reference
is also made to the exemption which is conferred by the
Rivers Pollution Prevention Act, 1876, in regard to
waters proceeding from any mine “ in the same condi-
tion as that in which it has been drained or raised from
such mine.” The Commission are not aware of the
circumstances to which this exemption was due. They
have received some evidence of the pollution caused by
some mine waters of this character, which, in many
cases, continues (after the mine has ceased to be worked.
But the evidence is not sufficient to enable them to make
any general recommendation in regard to preventing this
form of pollution. Under the system suggested, it
would be open to a sanitary authority to demand puri-
fication of such waters subject to appeal to the central
authority, who would be able to consider each case on
its merits.

The ninth report contains also a mass of valuable
data in regard to the particular industries investigated,
from which we make some extracts :—

Coal Washing.

In this case the water, after use, is black and opaque,
with much very fine coal, shale, and dirt in suspension.
It contains some dissolved matter over and above that
originally present, but this consists mainly of soluble
inorganic salts, and is usually small in amount. In a
few instances where the coal contains much pyrites,
however, some arsenic may be present in the wash
water. (Cf. Fifth Report Rivers Pollution Commission,
1868, vol. 1, pp. 8 and 9.)

The discharge of this liquid into a stream is attended
with several objectionable effects. The water of the
stream is discoloured, and rendered unfit for many
secondary purposes, the bed of the stream is silted up,
and its banks are blackened. If the discharge bears a
large proportion to the volume of the stream fish are
destroyed, and aquatic vegetation is detrimentally
affected. If the stream overflows its banks, much black
suspended matter may be deposited upon agricultural
land.

The discharge of coal washing water.was a subject of
enquiry by the Commission of 1868. They considered
it a liquid liable to cause pollution of a. very serious
character (Fifth Report, vol. I., p. 9), and recommended
quiescent settlement as a fairly effective remedy
(pp. 43 and 44). The Commission now state that their
own observation and the consideration of the evidence
which has been given lead to the same general conclu-
sions. Since the publication of that Report settling
tanks have been constructed at many collieries for the
removal of Small coal and other impurities from coal
washing water, and in a number of cases the clarified
water is sent back to the washer for re-use. As showing
the kind of result obtained, some average figures are
given which have been collated from a report by Dr. H.
Maclean Wilson to the West Riding Rivers Board,
dated December 14, 1900 :—

Parts per 10° JOO.		
Solids in solution:— Volatile on ignition... Non-volatile 		(  Crude coal- washing water.*  29*25  329-25	Purified coal- washing water after settlement in tanks.f  40-3 290-4
Total 		358’50 .	330-7
Solids in suspension : — Volatile on ignition... Non-volatile 		4,383’8  1,013-9		about 0'8  	about 1’5
Total 			5,397’7	2’6 (range 1’1—4'1)

* Average of 23 analyses of chance samples drawn from
23 different plants.	,	.

f Average of 6 analyses of chance samples drawn from
5 different plants.

The figures are not strictly comparable, but they serve
to show how effective settlement may be in removing
the matter in suspension. The effluents included in
the above average are classed. as good or fair by Dr.
Wilson. Other effluents classed as unsatisfactory con-
tained from 4-8 to 10-0 parts of suspended matter per