Charles George Warnford Lock.

Economic mining: a practical handbook for the miner, the metallurgist and ... online

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midden jerk given to the lamp parts a wire so weakened, and the
light goes out.

Another sonrce of trouble with the secondary battery lamp is that
if the plates are to give a current of a certain strength for the period
of a shift, and to repeat the operation for several months, they must
be made strong and heavy, and this renders the lamp heavier than
the collier cares to carry to and from his work. In addition to ^s
also, there is a strong element of uncertainty as to the duration of
the light given by the secondary battery lamp. A lamp may give
its full light for 10 or even 15 hours one day, and only for one hour
the next, though the charging current may have been passed through
it for the same time in each case. In the secondary battery, we have
really two batteries, one on each plate, which are constantly at work ;
and though the powerful charging and discharging currents mask,
so to speak, the smaller electro-chemical reactions which are present,
these occasionally make themselves felt, by perhaps short-circuiting
a pair of plates, or by introducing a high resistance between the
positive plate and its oxide, which cuts off the light perhaps for
nours, while this reaction is working itself out. It shoidd be men-
tioned, too, that the life of secondary battery plates is a most uncertain

Though it appears a simple matter to pass a current of electricity
through one or any number of lamps, having a dynamo ready to
fumi^ the current ; and though it is a simple matter — to a trained
electrical engineer — to arrange for charging a limited number of
lamps from any form of dynamo ; where the number of lamps is large,
as it would be at most collieries if secondary battery lamps were
generally adopted, it is by no means a simple affair, even to a trained
electrical engineer, unless he has his dynamo specially constructed
for this purpose, and his arrangements for connecting his lamps veiy
carefully planned indeed. If he has to use the ordinary 100 or 110
volt dynamo that is in use for the regular lighting of the colliery, or
a 800 volt dynamo that is doing both lighting and pumping, for say,
charging 500 lamps, he will be very fortunate indeed if he does not
have frequent cross connections, failures of the connections to indi-
vidual lamps, and other little things that will add to the cost of the
lamps by creating an element of uncertainty in their work.

The question, too, of the use of a switch with any miners' electric
safety lamp is very troublesome. If the lamps are charged before
the colliers are ready for them, their current is wasting unless it is
switched off, and this might be a serious matter where, as often
happens, colliers do not come to work when expected. If a switch is
provided with the lamp, it is almost certain to give trouble. It can-
not be strong, as it will then add too much to the weight of the com-
plete lamp, and if it is not strong, it will not only be broken, but
cause the lamp to give an intermittent light. The diffbulty may be
overcome by naving the secondary cells in batches, removed from
their cases while being charged, and only put in at the last minute.
But the question would naturally arise if tnere is time to do this in
the early morning, when hundreds of pitmen are clamouring at the
lamp-room window, and if, in the hurry attendant on followiBg this

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plan, some lamps will not be improperly connected, and so fail before
the end of the shift, perhaps before the face of the coal is reached.
The new switch introduced by the Edison-Swan Company, in which
tarning the light in or out is effected by tilting the lamp, is certainly
worth a fair trial.

It would appear, however, that the primary battery lamp is the
one which will eventually be adopted for mining work, as the opera-
tion of charging them more nearly resembles that of refilling the
ordinary lamp now in use. The connections also will be under
inspection each time the lamp is refilled, and can be cleaned then just
as the gauzes and glasses are now. Farther, the matter of connections
can be arranged in a very simple manner, and so that there need be
very little waste of power, while the lamp is not in use, the operation
of lighting the lamp and making the final connections being very
mnch like screwing the bottom of the Davy lamp on, as at present.

The working cost of electric lighting in mines is the chief point
of interest, and to give an idea of l£is the following example of
lighting a colliery is given, based on the estimates of John Davis h
Son^ Derby.

Lamps: Pit top, 2 x 100 c. p. and 2 x 16 c. p. Screens, 4 x 50
cp. Sorting belt, 12 x 30 c. p. Engine-rooms, 6 x 25 c. p. Boilers,
shops, ofiices, &c., 12 x 16 c. p. Underground — Pit bottom, 4 x 30
0. p. Main roads and stables, 20 x 16 c. p. Total equivalent to
ahout 100 x 16 c. p. lamps.

Taking the usual hours of working, and taking into account the
all-night lights, the expenses per annum will be as follows : —

Sorfaoe, 6 aji. to daylight and dusk to 5.30 pji.\ „. ^^ y^^^^x.^^^

=rSo hours X 60 x16 c. p. lamps /= 24,000 lamp-hours.

UndCTgroond, all day = 4000 hours per annum! _ mn t\t\e\

X25xl6c.p j - iuo,uw „

All night— surface, 6 x 16 o. p.; underground^ _ ^« ^^
4x I60. p. = 10x16 c. p. X 4000 hours ../ "" ^»^<^

164,000 „

£ f. d.

CoaL 164,000 lamp-hours, at 2«. 6(f. per ton, say 12 10

Beoewals of lamps 20

Depreciation at 5 per cent on 2001 10

Ofl, water, waste, and sundries 2 10


This is equivalent to a cost for gas of about 1«. per 1000 cub. ft.

In addition to the lighting, small fans, pumps, drills, &c., may be
driven by motors from the lighting wires, and will work without
attention, the working cost being merely the value of the coal used in
the boiler to drive the dynamo.

A specimen estimate of cost for the installation of 100 lamps of
16 c. p. is given by the same firm at 2002., the details being as
follows : —

Dynamo. One compound wound self-regulating dynamo, capable of
maintaining 110 x 16 c. p. lamps (or their eqniyalent)
complete, with oast-iron foundation rails and belt tighten-
ing screws, lubricators, belt pulleys, &c.

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Gables and wires. ATerage requirements, with lead-covered cable for

pit shaft.
Lamps. 100 X 16 candle power incandescent lamps.
Fittings. 60 Dayis' special dn8t-i>roof reflector fittings, of various types
as reonired, fitted with lampholders.
40 polished brass lampholders with shade-carriers.
40 enamelled steel conical reflectors.
12 X 10 light porcelain-base switches, combined with cnt-oot
8 X 30 Ught „ „

12 small poroelain-base cut-onts.
4 laree „ „

Switchboard. 8late switchboard, fitted with voltmeter and with main

switch, main double-pole cut-out, and voltmeter switch.
Sundries. Staples, screws, insulators, brackets, angle irons, spikes,
coach-screws, jointing materials, wood casing, &c.

An installation for 200 lamps would cost 3752. ; for 500, 850L ;
for 1000, 13701. ; by using larger lamps than 16 o. p. the cost is ap-
preciably lessened.

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Whkn a mine oan be worked by adits these are driven at sncli a
gradient that the mine water will automatically flow out. When
sinking is adopted the water will accumulate at the lowest point, and
Bome means of raising it is rendered neoessary.

The simplest of aU methods, but the usefulness of which is limited
to lifts of less tiian 33 ft, is the siphon, varying from a common
rabber hose in the smallest installations up to an 8-in. pipe*

At Byer Moor Colliery five siphons are in use, working over a
distance of 3557 yd. The greatest lift of any one is 21 ft. ; and this
siphon is 1275 ft. long, 4 in. diam., has three right-angle turns in it,
fiiils 27 ft, thus working under a 6 ft. head
riving a pressure of 2*59 lb. per sq. in., de-
Uvers 40 gaL a minute, and is set by an Evans
force pump. Another drains two sumps, re-
spectively 2766 and 1887 ft. from point of
delivery; it is 4 in. diam., lifts 14 ft, falls
35 ft, pressure 9 Ib^^per sq. in., discharge
35 gaL a minute. The longest has thiee
branches ; the main trunk is 996 ft. long and
8 in. diam., and the branches are 2310 and
1227 ft. long respectively and 4 in. diam., lift

At Chester South Moor Colliery a siphon
1800 ft. long and 6 in. diam. lifts 26 ft

An ingenious air valve* used at Byer
Moor is shown in Fig. 15 : a is the siphon
pipe; 5, a flat circular leather disc valve
attsdied to feed pipe c, surmounted by a pail d.
While the siphon is running, c and d are filled
with water, and keep the valve closed ; while
the siphon is being filled, the pressure of air
against the under side of the valve opens it,
and the accumulating air thus escapes.

Where the qucmtity of water to be raised
is nnall, and no fall is available for a siphon,
while a head of water can be obtained, a most
uaeful contrivance is the hydraulic ejector,
whidi depends on the principle of an induced current created by the
force and velocity of the falling stream. This simple and effective
method is much in vogue on the deep gravel mines in California,

* H. F. Bnlmftn in * Joom. Brit Soc. Min. Stadento,' Jan. 189S.

Fig. 15.^ Am Valve
rob Siphon.

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16. — Hydraulic

where a great head of water can be had, and entirely replaoes pumpfl
for limited duty, practically at no cost for either operation or repair.
The airangement is shown in Fig. 16, where a is the pressure-
pipe bringing water from the surface ; 6, the suction-pipe for drawing
water from the mine sump; c, the discharge-pipa The suction
created in h by the rush of water from a into c induces the water in 6
to flow upwards. The precautions neoessarr
are that the diameter of c shall be groat enough
to accommodate the flow from a and 6, but not
so great as to nearly counterbalance iJie pres-
sure (less the friction) in a ; that the nozzles in-
serted in the ends of the respective pipes united
in the T d shall be proportioned to each other
(say a |-in. pressure nozzle for a |-in. receiver),
and adjusted relatively so that the stream from
h is caught up before it can spread ; that valves
ef are inserted in a and c so as to shut off the
water in case of anything going wrong ; and that
bends be avoided as much as possible, especiaUy
after the pressure water encounters the suction
water. The effective power of the apparatus
is about 30 per cent, of the pressure water and
a lift of 200 ft. is easily accomplished.

When the foregoing methods are not avail-
able, and the quantity of water to be raised
does not demand a pumping plant, buckets or tanks may be empbyed
in oonnection with the ordinary hoisting appliances.

In vertical shafts buckets of various sizes and designs are used.
Where the shaft is provided with guides and the ore is hoisted in
cages, the baling tanks are rectangular in form and are made to run
upon these guides. These tanks are usually provided with safety
catches, similar in design to those used on the cages. A hinge valve
at the bottom of the tank permits the automatic discbarge of the
water in the launders at the surface. A more expeditious method is
to dump the tanks by the arrangement of the guides used with self-
dumping skips. The tanks have a capacity of 300 to 800 gal. Where
the hoisting is done through incline shafts, self-dumping skips are
used to raise the water. At the Utica Mine, California, 676 gal. of
water can be raised in 1 J minute, from a depth of 660 ft., through a
single compartment of the shaft.

Where the amount of water is too great to be handled by buckets,
tanks, or skips, which is often the case where the water and rock
must be raised through a single compartment of a shaft, a steam
pump is very serviceable. A pump of this character is espeoiailly to I
be recommended in the preliminary stages, when the developments
of the mine are not suflicient to justify the erection of the far more
costly system of the Cornish pumping plant. Steam pumps are also
a valuable adjunct to the Cornish or to any other system of pumping
plant, as they are very useful in emergencies. Li case of aociden^
disabling the Cornish pump, or in the event of the sudden influx oft
great volume of water, the auxiliary steam pump might prevent th^

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inimdation of the mine, or of the lower workings at least. Com-
pressed air is often nsed instead of steam. This is the case always
where the pump is remote from the boiler.

Compound steam pumps, although the most economical of all
types of steam pumps in the consumption of fuel, are seldom em-
ployed on account of their great first cost, preference being given to
the Cornish system, when t£e erection of a large plant is necessary.

Non-rotary pumps without flywheels are used in preference to
rotary pumps. Although the latter are more economical in power,
they are too expensive and too cumbersome as compared with the
non-rotary class to be advantageously employed.

Simple steam pumps are either horizontal or vertical. Both
classes are used. The vertical pump is especially useful for sinking,
on account of the facility with which it can be lowered or raised.
By fjBir the most important class of pumps is the Cornish plunger and
lift pump. For handling large volumes of water from great depths
this system is superior with respect to economy in the use of fuel to
pumps of any other design. The first cost of the plant is considerably
greater than that of the steam pump. The lift pump is used to raise
&e water from the bottom of the mine to the lowest of the set of
plungers. From the lowest plunger upwards, plunger pumps alone
are used. The motion of the plunger or piston is imparted to it by
the pump rods, which are placed in the shaft along the line of pump-
column through which the water is raised. The pump-rod is com-
posed of timbers 4 to 12 in. square, joined together so as to form a
ooDtinuous piece. This rod is connected with the balance-'* bob " at
the surface. Intermediate balance-bobs are likewise used at various
paints in the shafts. To the nose of this oscillating bob, the oipper
end of the pump-rod is attached. The oscillating motion is imparted
to the bob by a pitman, which connects the king-post of the bob with
the pump wheel. To one side of this wheel ^e pitman is attached
by means of a wrist-pin.

A reciprocating motion is thus given to the pitman, which in turn
actuates the bob, imparting to it, as before explained, its oscillatory
motion. The length of the stroke imparted to the rods and thence to
the plunger is regulated by the distance of the wrist-pin from the
centre of the wheeL The length of strokes varies from 3 to 8 ft., and
the number of strokes per minute varies from 3 to 10 or 12, depending
upon the duty required of the pump.

At the inner end of the bobs, counter weights are placed in boxes
tttaohed to the bob for that purpose, to prevent the too rapid descent
of the rods, and to equalise the work of the engine at either stroke.

The following figures are an average month's results from five
years' experience by J. T. Forgie of a pumping plant dealing with a
whole coalfield, and as actual working results they cannot fail to be

The engine is an old horizontal one, with cylinder 26 in. diam.,
stroke 4 ft., and geared 4 to 1 through tooth wheels. The tumbling
Clink sits right over the pit, and works directly on to one of the lifts
of pumps through a set of guides, from the crosshead of which are
two ponnecting rods driving the double-nosed bell-crank, which in its

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tnm driyes the seoond bell-crank ihroQgh radius bars, and this other
bell-orank works the seoond set of pumps. The whole arrangement
is oompact, but not desirable. To the engine was applied a simple
air-pump and oondenser, worked off the end of the engine shaft
There are four double-flued Lancashire boilers, 25 ft. long by 5 ft
9 in. diam., fired underneath the boiler, the flame being oondaoted
underneath, then back in the tubes, and again along tbe outside of
the boiler to the chimney-stack.

Stroke in pumps, 6 ft ; top lift, 16 in. plunger, 58 fathoms
4 ft. ; bottom lift, 15]^ in. plunger, 35 fathoms 2 ft. ; total depth,
94 fathoms.

The pumps went 261,485 strokes during the month. Total hours
in month, 758. Hours pumps were standing, 33. Actual hours
pumping, 725 — equal to 43,500 minutes.

261,485 -T- 43,500 = 6*01 strokes per minute when pumping.

Foot-pounds per stroke of top lift 180,224

Do. do. bottom lift 101,760

Total foot-pounds per stroke of pumps 281,984

Deduct 5 per cent 14,099

Foot-pounds per stroke 267,885

267,885 X 261,485 = 70,047,909,225 foot-pounds per month.

Coal consumed during the month, 125 tons. 261,485 -4- 126 =
2091*08 strokes per ton of coal. 125 tons are equal to 2979 bushels
of 94 lb. each. The duty of engine, or foot-pounds of actual work
performed per bushel of ooal consumed, was 70,047,909,225 -r- 2979
= 23,573,900.

The dross used during the month was coking coal dross, whioh is
very good in quality, but in comparing with Cornish pumping engines
duties of 90 to 100 million foot-pounds, we must remember that they
base their calculations on a bushel of the best quality of round screened

Horse-power exerted by engine in doing actual work, not counting
that exerted in overcoming firiction, &c. :— 70,047,909,225 -i- 43,500 =
1,610,297 foot-pounds per minute -7- 33,000 = 48-80 h.p.

Diagrams taken with speed at 6 strokes of pumps per minute,
showed an average pressure of 12*8 lb. of steam in piston, and a
vacuum of 9 * 2 lb. per sq. in., equal to a total working pressure of
22 lb. per sq. in. This pressure, and with the average strokes per
working minute per month (6*01) gives an indicated h.p. of 67*95.
The actual h.p. in work done was 48*80, leaving 19*15 h.p., or 28 '18
per cent, of the total indicated h.p. as that used in overcoming the
friction of the engine, gearing, pumps, &a In other words the
engine was giving 71*82 per cent, of useful effect. The steam
pressure in the boilers when the diagrams were taken was 40 lb.
per sq. in.

125 tons are 280,000 lb. weight of ooal~

280,000 -i- 725 = 386 lb. ooal consumed per hour.

886 -I- 48*80 = 7*91 lb. coal consumed per h.p. per hour of actual woA

386 -!- 67-95 = 5*68 lb. ooal consumed per indicated h.p. per hour.

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Actual Afihes made by Goal—
125 tona of coal gare 35 hutches of aahee, weighing 4 owt each, or in all 7 tons.
Asbe« from coal =: 5*6 per cent

For six months* contintious work, raising 845,981 tons of water,
the co>t was : —

Laboar: 732. I9c, or 4*06(2. per 100 million foot-pounds, or 5*18d. per

100 tons of water.
BepaiFi: 322. 18<. lOd., or 1*81(2. per 100 million foot-pounds, or 2*29c2. per

100 tons of water.
Fuel : 1382. 6#. 2(2., being 823 tons ordinary quah'ty dross at 3<. 4(2. per ton, or

7*5Sk2. per 100 million foot-pounds, or 9*59(2. per 100 tons of water.
Total: 2452. 4«., or 13*46(2. per 100 million foot-pounds, or 17*01(2. per

100 tons of water.

No allowance is made for depreciation of plant or interest on

Appended are results, also by Forgie, of pumping at an Ayrshire
pumping station with a compound condensing horizontal engine. The
fuel used was very much inferior to that used in the other case, and
the pumping machinery only worked 12 hours, necessitating the
boiler fires to be damped over night ; hence the reasons for the results
per 100 tons pumped 100 fathoms being so very little better with
the compound condensing than with the simple condensing engine.

High-pressure cylinder, 20 in. diam., 4 ft. 6 in. stroke.
Low-pressure cylinder, 34 in. diam., 4 ft 6 in. stroke.
Gearing 4 to 1. Stroke in pumps, 6 ft
Pompa— Top lift 40 fathoms 4 ft., two 14-in. plungers.
rt Bottom lift 31 fathoms 2 ft, two 14-m. plungers. '

Foot-pounds per stroke— Top lift 195.810

„ „ Bottom lift 150,870

Deduct 5 per cent 17,334

Foot-pounds per stroke 329,346

829,346 foot-pounds = 76*23 gal. of water raised 72 fathoms per stroke of

pumps. Water pumped in one year, 552,156 tons. Cost : —
Labour: 972. 8«. 114., or 4-36d. per 100 million foot-pounds, or 4*22d. per

100 tons of water, or 5*864. per 100 tons of water pumped 100 fiithoms.
B^Mtirs: 712. 14s. 6<i, or 3*22d. per 100 million foot-pounds, or 3*12d. per

100 tons of water, or 4*334. per 100 tons of water pumped 100 fathoms.
Fuel: 872. Is. 54., or 3*914. per 100 million foot-pounds, or 3*784. per 100 tons

of water, or 5*254. per 100 tons of water pumped 100 fathoms.
Total : 2552. ]9t. 104., or 11*494. per 100 nullion foot-pounds, or 11*124. per

100 tons of water, or 15*444. per 100 tons of water pumped 100 fathoms.

It would be impossible in the scope of the present work to even
enumerate the many forms of pump in the market, and only one or
two prominent examples can be mentioned.

The Worthington Pumping Engine Company have gained a world-
wide reputation, notably in connection with the gigantic operations
of the American oil pipe lines. In their hydraulic pressure pump, the
ordinary interior double-iusting plunger is replaced by two plungers
or rams having external adjustable packings, readily renewed, which
work into each end of a cylinder haying a central partition. The

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plnngerB are connected together by yokes and exterior rods in snch
a manner as to cause them to move together as one plunger, so that
while the one is drawing, the other is forcing the fluid, thus making
the pump double-acting. The valve boxes are also modified for the
purpose of subdividing them into separate small chambers, easily
accessible and capable of resisting very heavy pressures. The general
arrangement is subject to numerous idterations, to adapt the pump to
different requirements. The general characteristic of independent
plungers with exterior packing is, however, in all cases preserved, as
being not onl^ more accessible in case of leakage, but also as allowing
the use of different forms and material of packing. The severe
pressure to which these pumps are often subjected, not less in some
cases than 8000 lb. to the square inch, demands the most thorough
construction and the u$e of the very best material.

Not less renowned are the " sinking " pump and the " Lehigh "
pattern mine pump of the same firm, in which simplicity of action,
economy of power, facility of repair, and unvarying reliability are
kept in view.

The extensive character of the pumping operations in connection
with the sinking at the new Cadeby Colliery, Yorkshire, recently
completed, lends a special interest to the means employed. The
ground passed through was so insecure that it was decided to try
some kind of pump, capable of being suspended in the shafts, and
not so heavy as to necessitate the preparation of very strong founda-
tions, or to require staying from the sides, which were too unsafe to
stand any vibration, and too soft even to permit of holes being cut
through the wood lining.

The shafts being sunk through such loose and soft material,
frequently converted by the water into mud, had to be very carefully
spiled in sinking ; and were then lined by placing 9 in. by 3 in. wood
cribs about 2 ft. apart, backed with 7 in. by 2^ in. ^ttens close together
behind, the whole being bolted toother crib to crib, and suspended
from long cross-beams hiid on pac^ on the surface. Flat iron rods
were also run down inside the cribs from the top beams, and secured
thereto as an additional precaution to prevent slipping.

Choice fell upon the sinking pump made by W. H. Bailey & Co,
Salford. This pump, which has been called the '' Denaby," consists
of 3 hollow plungers ; the upper pair are stationary, and over them
slide barrels which are connected to the steam piston. From the
lower ends of these barrels the bottom plunger projects. This plunger
works into a third barrel, and is actuated together with the first two
barrels by means of the steam piston. The third barrel is secured,
together with the pair of stationary plungers, to the steam cylinder
by means of connecting-rods. Thus there are two small barrels in
connection with the large ram, moving between the smaller rams
and the large barrel, which also are connected. There is a system
of rubber disc-valves in the junction between the smaller barrels an 1

Online LibraryCharles George Warnford LockEconomic mining: a practical handbook for the miner, the metallurgist and ... → online text (page 9 of 76)