A World First To Cap Them All
( Coal gold + base minerals of Southern Africa 1981)
This article written by C J Taylor A.R.I.C. Chlorides
Technical Director takes an in-depth look at an important development in the
cap lamp industry. The article was sent
to us by Colin Priddle (Pope) who lives in
The South African mining industry is the largest user of cap
lamps in the Western World. Our mines
requirements run to some 570,000 lamps - 3% of the western world total - while
The history of the cap lamp dates back to candles and subsequently the break-through of the Davy lamps which allowed naked flames for lighting without fear of methane fires. This was followed in the early 1930s with the first electric miners lamp incorporating a battery encased in a metal cylinder worn on the miners belt. It was not until 1950 that lead acid accumulators replaced the old alkaline battery and introduced for the first time the advantages of a self-service operation in the storage frames.
Since then, the mining industry has been growing at a fast
clip world wide, but the miners cap lamp market has been relatively
static. Increased mechanisation and
longer shifts offset what would otherwise have been a proportionate market
growth. This situation has now changed
as the traditional miners cap lamp nears the end of its capacity for use in a
rapidly changing mining industry.
Though the 1950-based cap lamps have served the industry
well, certain disadvantages became of increasing importance in a rapidly
developing mining industry which was gravitating towards longer shifts and
deeper level mining. These factors were
particularly important in the South African mining sector following the boom in
metal prices in the late seventies. As
new mining plans were announced the need for an advanced miners cap lamp led to
a focus on the traditional products disadvantages. These were:
a) Limited
ampere-hour capacity which does not allow for longer shifts.
b) Inadequate
light output for industrys future needs.
c) The
accumulators need constant topping up which means removing each filler plug for
inspection.
d) Charging
time was considered too long as the industry moved towards longer shifts. A 1:1
charging to light availability ratio was regarded as Optimal.
e) Liquid
filled batteries incorporated a spill danger which caused minor accidents such
as acid burns; and
f) The mass of lamp unit was considered somewhat high in relation to output.
In order to meet the needs of the mining industry world wide
and the South African market in particular, Chloride pursued the development of
a new miners cap lamp and accumulator. The technological objectives of the research programme demanded a
product that would incorporate:
a) A
maintenance free accumulator
b) Shorter
charging time.
c) Higher
ampere-hour capacity
d) Improved
light source and output! and
e) Reduced
mass
Consequently, Chloride Technical in the
The new Chloride accumulator is the hub of the
development. Being maintenance free it
should contribute to improved cost effectiveness while its power specification
promises a much improved power: mass ratio, thereby fulfilling two of the major
criticisms levelled at the traditional units.
In normal batteries oxygen and hydrogen are released from
the electrolyte bring the charging process and this requires the units to be
topped up with water. However, Chlorides
work on recombination technology has resulted in the manufacture of a battery
which never needs to be refilled and thus can be completely sealed. In fact though the battery is a lead acid
type, the electrolyte is contained within the plates and the separators, so
even in the event of damage to the battery case; there is no liquid to
spill. Thus, allied to maintenance free
operation, Chlorides product should contribute to improved safety by avoiding
minor accidents related to acid spilling.
Incorporated with the maintenance advantage the new mining
accumulator is claimed to provide 61% more power, having a discharge cycle of
16 hours compared with 12 hours previously. At the same time the exterior casing has been cast in a plastic which
showed nine times greater resistance to abrasion and impact than a hard rubber
case.
This result should be particularly important in developing the export potential of the new miners lamp, as South African quartzites have in the past proved far more damaging to the battery cases than conditions pertaining in other parts of the world.
TECHNICAL CHARACTERISTICS OF LAMP BATTERIES
|
OLD
|
NEW
|
Voltage/Capacity
No. of Plates
Volume (m/)
Mass (filled with cover (kg)
Cycle Life
Container material
FL
Duration (0.9A)
Operational voltage range (V)
|
4V/10-ah
3(2 negative 1 positive)
41 x 150 x 187
1150
2.24
750 cycles (70% depth of discharge)
Resin Rubber
10 hours
4.00 to 3.70
|
4V/16-ah
3(3 negative 4 positive)
40 x 125 x 187
935
1.96
500-70 cycles (70% depth of discharge)
Abrasion resistant Rubber
16 hours
4.00 to 3.70
|
The, new accumulator is completely compatible with existing
charging systems in the mining industry. But for full potential a new rack and charger has been developed which
reduce the charge time through higher charge rating. Incorporated in the accumulator is a fail
safe feature in the form of an inner seal which allows gas to be released in
the event of a serious over charge.
Though the significant breakthrough is in the development
of. a maintenance free accumulator, Chloride has built into the unit certain
other advances. The plastic not only
conforms to fire resistant specifications laid down by the mining industry, but
is tamper proof and offers greater comfort to the user. An integrated belt loop and the leak proof
advantage make the unit more comfortable to wear, particularly in the narrow
confines of a stope. In addition the
cable joining the accumulator and the battery has been redesigned with a new
cable lock to prevent disconnection. Chlorides tests show that the cable lock can withstand forces of up to
670N at the headpiece and 1300N at the battery before becoming disengaged.
Allied to these efficiency and improved safety improvements
the refined headpiece promises to fulfil the rest of the industrys
requirements. In a mining environment
the need for safety is paramount, and insufficient light at work stations
contributes to minor accidents and a resulting fall in labour efficiency. By incorporating a new-headpiece using a 4V
1A halogen bulb with a larger reflector, Chloride claims the new lamp boosts
lumen output by six times. (The
introduction of a miniature halogen bulb is the result of extensive development
by the major lighting companies in Europe and
The impressive specifications of the new accumulator and
headpiece have been sustained in local testing underground and have led to a
very favourable reaction from a mining industry committed to enhanced safety
and improved cost control. In April last
year 200 lamps were placed in both Vaal Reefs and Doornfontein and during the testing
there was a notable decrease in the incidence of minor accidents. In fact, the new product is probably
technologically ahead of current mining industry needs, but should offer
lighting to keep abreast of development in mining methods.
Though the maintenance free miners accumulator and improved
cap lamp has a rival in new European nickel cadmium units, price and power
capability suggest the lead acid system will be far more popular. Not only does the maintenance free system
offer significantly higher light availability, which makes it particularly
suitable to South Africas longer shifts, but it is also priced some 7%
lower. This pricing difference stems
from the cost of the metallic constituents in the NiCd Battery and the longer
production runs possible in
MANUFACTURE
Not only will the launch of the maintenance free accumulator
and improved headpiece be a world first for
In order to cater for local demands Chloride has invested
some R1 million at its Benoni factory. Recently, Chloride SA managing director, Don Searle, said production
would be geared to satisfying South African demand. But as the South African Company will be the
only Chloride operation worldwide manufacturing the new accumulator and
headpiece export potential is huge.
EXPORTS
The total cap lamp market outside the Soviet Union and
The introduction of a world first maintenance free battery
in the cap lamp market and the development of export potential could have far
reaching effects in an industry constantly aware of the need for containing
increases in mining costs. Beyond that,
the development could well pave the way to maintenance free, motive power
batteries for underground and surface use which will help the industry in the
constant battle to contain costs.
FEATURES OF THE NEW MINERS CAP LAMP
a) Completely sealed.
b) Maintenance free.
c) 60% more capacity in accumulator.
d) Under test conditions battery case offered nine
times more resistance to abrasion and impact than the old unit.
e) Fits all existing charging units but for
complete technical compatibility the new charger and frame are recommended.
f) Extra burning time and even illumination.
g) Leak proof even if container is damaged.
h) Re-sealable safety - the inner seal allows gas
to be released if battery is seriously over charged.
i) New cable lock which prevents cable from being
pulled out of lamp or battery unless force exceeds 670N at the headpiece.
j) Flame resistant container for underground
application.
k) Tamper proof - special tool needed to take off
lid.
l) Stainless steel shoe available for hard-rock
mines.
m) New lamp fits onto any standard helmet.
n) Six times greater lamp output.
o) Charging rack designed to take 10 lamps or
multiples thereof with features which make it easier to handle and offer longer
life.
Colin Priddles note: "Ive got two of them cost £16 each (R32) Charger (R30). They are superb, Terrific beam, 16 hours
light".