Document 6BMm830rZr7nq5MRzVaB40Emd
2 PRODUCED IN MATTER OF KEYS V. MIDALCQ NO 1161 OF 1967
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PRODUCED IN MATTER OF BARROW V, MIDALCO NO 1141 OF 1*7
REPORT on
INSPECTION OF CAPE BLUE ASBESTOS LTD. UNION OF SOUTH AFRICA
*Prodiuc&lin Asbestos Persona) InjuryCases: Abrams lead and
copied toRichard F. Scruggs
I1
PRODUCED IN MATTER OF HEYS V. MIDALCO
NO 2161 OF 2967
produced in matter of
EiARROW V. MIDALCO NO JJ48 0F J967
CAPE
ESTPB-iaD
INDEX
INTRODUCTION fSUMKARY
FEftggITO GENERAL
1 '1
3
4
mp,ms
,,
Production Data - Table T
5
5
MINING METHOpS
Z
Koeeap - Stope Layout
.6
Ventilation
7
Water
6
Lighting
6
Production
8
Ore Handling
8
Mine Statistics- Table II
S
Fibre Length
9
Labour Force
10
Cost of Production -Table IV 10
Stores Costs - Table V
11
Rates of Pay
11
Produced in Asbestos Pen*"*'
FRQOUCEDJN MATTER OF HEYS V. M1DALCO NO H61 OF 1967
Index (continued)
PirODUCED tN MATTEROF EARRQW V. M1DALCO NO 1148 OF 1967
i
i
xi
"H
DETAILS OF MIMIHQ OPpR^ONS
12
ftoepap
12
Weilbach
UU ~ Haum
Westerberp ffo. 2 Section
12
13 13 13
Westerbere No.A Section
15
Wegterberp yo.. 8. Section
16
UlfPVlz
16
UXI&I2&
General ffesterbepg Mill - Details
r 17 18
Plant Capacity
19
Mill Building
20
Labour
20
Koegas mil - Tailings Treatment
20
Net; Koegas Plant
0
pLEAffF?0 PLATTT - PRIESKA
S Grade
- General
22
- Blending
22
- Feeding
22
Hammer Mill
23
Bagging
23
Retreatment
23
Dust Collecting
24
Power
24
Buildings
25
Labour
25
Plant Capacity
25
Testing
25
Produced
`njury Cares:
"0*5 Personal
'\s i*a and
oocied tojHjclwc
PRODUCED IN MATTER OF KEYS V. MIDALCO NO 1161 OF 1967
Index (continued)
produced in MATTER of barrow V. MIDALCO NO IKg OF 1967
Tailings -TTrreatment Plant
Long-Fibre
General Plant
5 6 6
Sketch Map Shoving Distribution of Asbestos Occurrences in South Africa
1
Typical Seans of "Northern Section of Blue Asbestos Deposits, South Africa
Stope, Koegas Mine
3
Vesterberg Hill-
4
Koegas Tailings Treatment
,5
New Koegas Mill
3
Prleska S Plant
?
Estimated Flow Sheet, S Crade Cleaning
Plant, Prleska
8
Banner Mill, Prleska
9
Prieslta X Plant
10
PHOTOGRAPHS
Page
Panoramic view of Koegas hills
1
Panoramic view of T/esterberg Valley
S
Looking south into '.Vesterberg Valley
3
West side of Vesterberg Valley
3
West side of '.Vesterberg Valley showing
sorting dumps
3
West side of V/esterberg Valley showing
sorting dumps
4
Natives sorting ore, V/esterberg Valley 4
Band screening tailings dunps
5
Miners' houses in V/esterberg Valley
5
Asbestos Fibre bearing strata, Kllphuls 6
Drive entry, Kliphuis
6
Hand cobbing station, Kliphuis
6
Produced in Asbestos Persona! Injury Cases: Abrams `-trs and
copicfCTtb Richard
PRODUCED IN MATTER OF
HEYS V. M1DALCO
NO U610FJ967
Index (continued)
^owv.*22^
NO 1148 OF 1987
Page
Hand Cobbing long fibre
7
Native women band cobbing long fibre
7
2he town of Prieska
a
Cleaning plant, Prieska with dust collecting rooms
8
Cleaning plant, Prieska with short fibre recovery plant*
8
Cleaning plant, Prieska showing bagging
of long fibre
,9
Loading
timber .at Prieska
9
Produced inAsbestos Persona! Injury Cases: AUams Joed and copied to Richard F. Scrubs
*t~ *
PRODUCED IN MATTER OF HEYS V. MJDALCO NO 1161 OF 1987
13th September, 1349*
PRODUCEDIN MATTER OF BARROW V. MIDALCO NO 1148 OF 1987
HTTP ODUCTI ON*
Arrangements to visit the Cape Blue Asbestos Limited
mines near Kimberley were made by Ur* C.V/.R. Powell in
London with Ur. dies Hewton, Managing Director of Cape Blue
Asbestos Company* In South Africa arrangements were made
through Colonel E. Riley/ Director of Cape Blue Asbestos in
<
charge of asbestos mining in South Africa, whose headquarters
are in Johannesburg*
The arrangement were to travel by train overnight from
Johannesburg to Kimberley, a distance of approximately 400
miles, then fly by-charter plane from Kimberley to Prleska, a
distance of approximately 130 miles* After looking through -
the blue asbestos cleaning plant located at Prleska which is
the railhead for despatch of asbestos to Cape Town the reaaindc
of the journey to the main mining centre at Koegas was made by
car, a distance of approximately 50 miles*
Produced in A d xrto c Pcrconnl
Injury Cusad: Al.rar.^s lead and copied lo Richar F. Scrupgs
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SUMMARY*
The main asbestos deposits of the Cape Blue Asbestos Company are located on the Orange River at Koegas in British Bechuanaland approximately 150 miles west of Kimberley* . Asbestos ore has been extracted from outcrops scattered over a: area of about twenty square miles during the past forty years* Until recently there has been no systematic mining and all wor Including drilling was done by hand with native labour* Host of the fibre seams dip steeply and only the fibre bearing ore is extracted* Ho waste rock is broken and support is provide by means of timber posts*
There is no mechanisation underground either for handll ore or .for 'tramming* Inmost of the stopes the ore gravitate to the loading points but elsewhere ore is shovelled by hand into mine cars* There is no mechanical underground haulage, tramming being by hand*
Ihe extracted ore is hand picked J?y native women and cl
hK'jUUCED IN MAJ'ifcK uHEYS V. MIDALCO
NO 1161 OF 1987
"^vw0 ^0 1148 OF 17
at each drive entry, the barren rock being left to form a.
dump and the fibre-bearing ore taken to the mill for treatment
long fibre is hand cobbed at the mine entry and receives no
further treatment at the mine*
Only small amounts of asbestos are produced from each
working section, there being about a dozen such places in the
r
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t **
*> _
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Koegas-Westerberg area, each with its own waste dump* Each working point only produces two or three tons of fibre per day on*one shift*
Xoegas is the mine township on the north side of the river and there are several working "areas north and south of 11 Westerberg is the name of a valley on the south side of the *i\ in which there are about eight working areas* All of these-' mining sections are under the control of the Manager at'Koegas.
Formerly Koegas and ffesterberg each operated a small a!3
* which treated the hand picked asbestos bearing ore, producing fibre containing approximately 20% of rock and dust* The Soec
mill has now been converted to retreat-mill tailings dumps froc
previous years1 operations to recover short or X grade fibre.
v V
The Westerberg mill which was rebuilt about two years ago trea`
all the ore produced at Koegas, Westerberg and the surrounding
areas* A new mill is in course of construction at Koegas to
treat all the fibre produced from both Koegas and V/esterberg
areas when the underground output'is increased in the course o
the next few years*
All the fibre from the various areas is brought to Prle
# far cleaning, blending and grading before despatch* A, B, C
D grade fibre are the long hand cobbed grades a:id these are bl
CJ CwA and picked over by hand to remove stone* The S grades, whlct the mill products from Koegas and V.'esterberg, are blended, cl<
mechanically and bagged ready for despatch* S grade is rougi
PrOvluC'-iri in AiOv
equivalent to lYittenooa Jo, Z grade but is more open and bett<
*2
cleaned* aWJ x_ 7. grade fibre from Koegas together with the tailings f: w*n cril the S grade cleaning plant are treated to produce the finishes
8 X grade which is about equivalent to the proposed No. 4 grade
HEYS v. MIDALCO
p!lObuciD in matter of
NO 1161 OF 1967
BARROW V MIDALCO
NO 1"W148WOIF 1197807/ Vittenoom. The bagged fibre is fchendespatehed by rail 600 ml
to Cape Town or 400 ailes to Port Elizabeth for shipment overs
Production is about 800 tons of fibre per month from al
sources and the cost of production is froa 35 to 40 stg. per
short ton equivalent to 453 per long ton*
.. -*
PRODUCED in matter of keys V. MIOALCO No 1161 OP 1967
3
barrow v midalco
NO 2146 OF 1987
PERSONNEL*
Johannesburg - Director
Colonel R* Riley
General Agent Mr* N* Biskett
Kimberley
General Mgr* Mr* Hodgson
Assistant
Baker
Koegas
t Prleska
Manager
Hr* Sinclair
Mine Manager
Lewis
Assistant
Todd
Surveyor
Isaacs
Chf Engineer Campbell
Accountant
Sawkes
Manager
Mr* Van der Veldt
Messrs. Lewis* Todd and Campbell have only been with Cape Bine Asbestos for one to two years* Prior to their engagement Mr* Sinclair was the only technically quelified person employed and was responsible for layout and '"operation of both the mining and the milling activities* Mess; Lewis and Todd were trained on the Johannesburg goldfields and Mr* Campbell is a retired Railways maintenance engineer so that none of these officers are very well versed in blue asbestos production problems*
Unfortunately* Mr* Sinclair was absent on leave at the time the mine was visited*
The Sales and Executive Office was formerly at Kimberley under Mr* Bodgson but Colonel Riley was in process of transferring these to Johannesburg* It is understood that Colonel Riley was appointed resident Director because of the inability of the existing organisation in South Africa to cope with demands for increased output*
The lack of trained technical staff at Xoegas and Prleska was most apparent* The Manager of the Prleska cleaning plant had no training of any kind and had been promote from the position of despatch clerk. - ^ *
PRODUCED IN MATTER OF HEYS V. MIDALCO NO 2J6] OF 1987
GENERAL.
rV.ODLC.'lL i\ MATTtn CF BARROW V MIDALCO NO IJ48 OF 1987
Prieska is a township of only a few hundred
people which serves as a railhead for some pastoral Interests
In surrounding areas In addition to handling blue asbestos*
The surrounding country Is sandy desert azri the summer temper-
atures reach about 120F. The Orange River passes within half
a alle of the town. Zoegas is also on the Orange River, a township
consisting only of people working on the blue asbestos leases*
.. There are approximately fifty white people at Zoegas, the greater part of the labour force being nomadic natives of the
Bushman tribe. The country around Zoegas and Resterberg, Ale
are the two main mining sites and are on opposite banks, of the
Orange River, is broken up by Irregular steep r<idges rising fro -* i /* v. 500 ft. to 1000 ft. above the surrounding plains. The veget
ation consists of a dry grass (not as great a nuisance as Spini
and stunted salt bush and other shrubs. The general colour of
the country is not as red as at Wlttenoom but Is more of a brow
colour. In the mined areas at least this appears to be due to
greater '-..--ithering having taken place. The rainfall Is very 1
but Irrigation from wells which abound In the district or by
pumping from the river enables good garden crops to be grown* c Telephone communication is available between
Zoegas and Westerberg, Prieska, Zlitorley and other points* There is so district power supply at Zoegas so
i that all power is generated on the site by diesel units. Supplies are carried Into and out from Zoegas
by road mostly to Prleska. Approximately 20 miles of road at
the Zoegas 6nd is owned by Cape Blue Asbestos.
The leases held by Cape Blue Asbestos cover a
considerable area totalling some hundreds of square miles and
scattered over a wide area*
1-
f^OOUCED IN MATTER OF HEVS V. MfOALCO
WO 1262 OF 6?
imniTG AREAS.
5*
>U;UDiNMAnL/U/F
HAHHOW V M1DAIC0
NO 1148 OF 198?
Owing to the disturbed nature of the country1'
in which the blue asbestos occurs, asbestos seams or "reefs"
(as they are called locally) lie at all angles from horizontal
to vertical. There are three well defined seams known as the
Inner, Main and Outer Reefs, which occur throughout the deposit.
The main production centre is Westerberg, in
which the fibre outcrops round the rim of a *Un shaped valley,
the arms of the "TJ" running north to the OrAxige River. The
fibre seams dip from all sides towards the centre of the valley
and there is every indication that the fibre is also under the
valley floor being continuous from one aide to the other. '.The
seams on the vest side of the valley appear to continue across '
the Orange River in the Koegas region. So far there has sot t . .
been any record of the asbestos seams In the eastern wall of the
valley continuing on the north side of the river.
Other areas worked are at Kuruman and Black Ridge
about 100 miles north of Koegas and Naauwpoort, Rllphuls and
Engeldewilgebocafonteln which -are approximately 30 miles east of
Koegas. Approximately half the output of fibre comes from the
Westerberg area, one-third from Koegas and the remainder from
the outlying areas.
Production Data - Table I
Average 22 shifts operated per month.
30 short tons fibre per shift.
600 * month.
S-o
i?fl %
#!?J
AJp
4?5i e b.o
s<5
'if
Vesterberg No. 2 Drive
4
Koegas
6*
7 7/eilbach Big Hill kill Hill
Black Ridge
Kuruman, Haauwpoort )
Kliphuis, etc.
)
5 tons
4
3 3
3
3
5 "3Q~ short tons
..
i'Kssl
itriUt
HEYS V. M1DALCO
NO U610F 1987
g,
, 4i,, .4>%, /r
: V MiDAlCO NO i l<iB OF 1987
MIKING, METHODS* Koeeas. In the Xoegas-V/esterberg area, mining
is carried on at about twelve locations over a distance of
several miles* A portable compressor is used to serve each
two or three locations* There is a white shift boss in chare
of each area controlling groups of twelve natives each group
being in charge of a native ganger (certificated by the Vines
Inspector) who inspects the stope face after firing and makes
4*
it safe, marks holes for drilling by the machine men, charges
the holes and fires them* It should be noted that the practl
of permitting natives to handle explosives is only permitted 1
outlying areas such as Xoegas, and is not allowed anywhere on
the main mining centres round Johannesburg*
100JC extraction is carried out in the s'topes,
the hanging wall being supported by mine timbers* Australia!
eucalypts of various species are most used for mine timber, be
grown round the Kimberley area and transported to the mine*
The average stope height is about 42n -but as the stopes are
inclined to the horizontal, head ^oom is not a problem* The
men use the timbers as a ladd-^rway for climbing through the
stopes*
Drilling is done by means of Jackhanaers of
about 40 lbs* weight* Pressure is applied to the drill by t
feet, the native driller bracing his back against the mine
timber*
Stone Layout* In an average stope the ore
body has a dip of say 50 ani would be worked at several lev
commencing from the top, the stope face being about 100* in
length measured down the dip* The stope face is usually ~~
inclined to the dip at such an angle that ore will rill dowr
to the loading point at the lower end of the stope face, the
is to say, in & steep stope, the top of the stope face lead;
the bottom by perhaps SO or 30 ft* whereas in a stope with i
flat dip the stope face would be either parallel to the dip with the lower eni of the stope face slightly in advance of
upper*
PRODUCED IN MATTER OF HEYS V. MIDALCO NO 1161 OF 1987
" 'CC:X>J.\MA7TLaCF brtKKOW V MIDALCO
NO 1148 OF 1987
Haulage drifts are advanced v/lth the slope fact
Instead of being developed beforehand as is the common practice
elsewhere. The development end for the haulage drift is kept
a few feet ahead of the stops face always.
The inclined stope face is drilled in a series
of.benches with holes about 3* apart near the, footwall and the
hanglngwall. The holes are drilled at an acute angle to the
stope face9 usually about 30 so that a 3* hole has a burden
of 12* to 18* at the bottom of the hole. By adopting this
practice (which is almost universal on'the goldfields) each hole
when firing acts Independently and a misfire only affects one shot and not a large part of a face. The advance per round
with this system is only about 1 ft. and an average stope face
is about 80* long, and 42" high, so that about 290 cu.ft. of
rock is broken per round (25 tons). This on an average yields
one ton of asbestos.
Usually one machine man and a helper drill a
stope face each shift, there being from 30 to 35 holes in a
face and the actual drilling time about six hours. The holes
average 3* deep so that approximately 100 of drilling is
done per machine shift.
if" bits are used, generally of the P. it U.
detachable type bit which have a life of about 3.5 ft.
Tungsten carbide bits made by Cemented Carbides in Johannesburg
were Just coming into use and cases were on record of one bit
having drilled several thousand feet. In addition to costing
less per foot drilled, tungsten carbide drills faster and saves
time taken up in frequent bit changes with P. & it. type. The
cost of P. & U. bits Is 3d. each at Soegas (cost at Johannesburg
ld*) The cost of a tungsten carbide bit and 4* steel is
2.15. 0.
Ventilation. As the mining to date has been
mostly above the general ground level, natural ventilation has
been provided by air passing in through haulage ways inside to
the reaches, passing up through stope face and out to atmosphere
ODUCED IN MATTER OF KEYS V MIDALCO NO 1161 OF 198?
8.
NO 1 OF 7<2?
where the asbestos originally outcropped.
',
Water* Water is carried to each mining
place and fed to the working places from a head tank at a <
venient high point.
Lighting. Carbide lamps are used exclusi^
for lighting within the mine.
Production. A group of four Jackhammers i
operated off one portable 300 c.f.m. compressor, the pressu
at the drills being about 60 p.s.i. The actual production
asbestos from four gangs- (four machine shifts) la 3 tons of
recoverable asbestos fibre.
u)g>*^A--f
As noted above, 25 tons of rock is broken a
c each group of four faces making 100 tons of rock per. shift.
This is concentrated by hand picking and cobbing at the ent
to the mine from 100 tons to about 15 tons which is then se
the mill. The quantity of recoverable fibre In the
1
therefore ranges from 20 to S0.
Each native gang numbering twelve sen cons;
a ganger or boss boy, one machine man and a helper, two me:
timbering, two men hauling trucks, the remainder of the fa
cleaning out the stope, laying track and drawing ore at th
holes.
c
Ore Handling. As-most of the stopes are
steep slope, the ore as fired, collects at the bottom of th
stope and is drawn off through timbered box holes into smc
mine cars of about 1 ton capacity. A native gang sweeps
the stope face in preparation for the next round of drill;
Generally each gang of twelve sen works two stope faces*-
drilling and blasting each face on alternate days. This
is common Wltwatersrand practice although where it is nee
for safety to advance a stope face rapidly drilling, bias
and cleaning are completed in one day by overlapping shlf
This latter method also reduces the amount of development
required for a given output.
Produced In Asbestos Pt
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produced in matter of
keys V. MIDALCO
NO 1161 OF 1987
9#
- v.LLi IN MATTER Cf uaKKOWV MIDALCO
NO 1146 OF 198?
Trucks of ore are pushed by hand to the mine entrance, usually a distance of a few hundred feet* The ore is tipped sideways on to a dump where native women and children hand sort the ore containing fibre and reject waste
rock. The contract rate for this work is one penny per 60 lb. drum of picked ore. Pieces of rock containing long fibre are put aside and hand cobbed on the site using a short handled maul weighing about 3 lbs. with a piece of rock as an.anvil. This work Is mostly done by native women. Contract rates of pay are 1/9 per drum of 60 lbs.'or 3/6 per bag of 100 lbs. of cobbed fibre. Native pickers and cobbers work in the open usually without cover.
The piles of waste rock extend outwards as'mining continues, the underground rail track being formed in a loop on the top of the pile.
The fibre bearing ore is loaded on to a 3 ton
lorry for delivery to the mill where it Is dumped in Open heaps
on the ground. Ore from the various mines is kept in separate
dumps and mixed by the operator feeding the mill.
Mine Statistics. Table II
Feet drilled per ton rock broken ... - 6
Tons rock broken per white man employed 15
Native boys per ton rock trammed ... 1.2
Pounds powder per short ton of rock broken 1.25
* Fibre in rock mined
5.5
% Fibre in ore to the mill
... 35
fibre (and rock), recovered from milled . 'i. ore 38* 4
l$This is reduced to about 30/* when allowance is made for the rock arti dust removed In the cleaning plant at
Prieska.
Cost of drill repairs per hundred ft. drilled 3/6 TABLE TIT
Fibre Length. The proportions of fibre in the
various grades are as followss-
Grsde A
s Long fibre 6%
Length. to 2"
" B, C & D :
-- 4# +lj to
S &X
:
90* i" to
,1 in U 0S :.
Injury
copteH* HI: , -rJ r
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PRODUCED IN MATTER OF HEYS V. MIDALCO NO 1J61 OF 1967
.CCD IN MATTER OF tv\RROWV MIDALCO
NO 1145 OF 1987 '
Trucks of ore ere pushed by hand to the mine
entrance, usually a distance of a few hundred feet* The ore
Is tipped sideways on to a dump where native women and children hand sort the ore containing fibre and reject waste rock* The contract rate for this work is one penny per 60 lb drum of picked ore* Pieces of rock containing long fibre are put aside and hand cobbed on the site using a short handled aaweighing about 3 lbs* with a piece of rock as an anvil* This
work is mostly done by native women* Contract rates of pay a; 1/9 per drum of 60 lbs*'or 3/6 per bag of 100 lbs* of cobbed fibre* Native pickers and cobbers work in the open usually without cover*
The piles of waste rock extend outwards as mini
continues, the underground rail track being formed in a loop or the top of the pile*
The fibre bearing ore is loaded on to a 3 ton lorry for delivery to the mill where It Is dumped In Open heaps on the ground* Ore from the various mines Is kept In separate
dumps and mixed by the operator feeding the mill*
Mine Statistics* Table II
Feet drilled per ton rock broken - 8
Tons rock broken per white man employed 15
Native boys per ton rock trammed
1*2
Pounds powder per short ton of rock broken 1*2
Fibre In rock mined
5*5
~. u
Fibre In ore to the mill
35
Fibre (and rock), recovered from milled ore 38*'
ffchls is reduced to about 30 when allowance
is made for the rock anl dust removed in the cleaning plant &1
Prleska*
Cost of drill repairs per hundred ft. drilled TABTI? ttt
Fibre Length*- The proportions of fibre in tl
various grades are as follows
Grade A * B, C & D
n * *.
Length* t Long fibre 6 to
'4+ii"to$*1
fsr-ff 3 *.l*i
PRODUCED IN MATTER OF HEYS V. M1DALCO NO 1161 OF 1967
10,
r tiv ivim i 1 ;.i\ i ;r
barrow v midalco
NO 1148 OF 1987
X Grade fibre is very short and has only been
recovered recently. It is recovered at Prleska from the S gr
tailings and at Xoegas and Westerberg from re-treatment of the
mill tailings dumps*
Although some of the faces examined in the
TTesterberg drives carried a total of 4n to 5n of fibre with a
maximum fibre length of 1", the overall mine average appeared
to be about 2jfl total fibre in an average stope height of 42".
Labour Force.' The total number of operators
employed at Xoegas and Westerberg is as follows:
Europeans
- 25
Natives underground
- 320
Natives on surface
- 280
Native women & Children
i
Contract workers
- 150
Natives employed elsewhere - 150
Total Cost of Production of Fibre - Table TV
fstr. per short ton
Salaries & Wages, Mine & Hill Labour
17
Asbestos charges (made up of working expenses for motor vehicles etc.)
Transport Koeges to Prleska 6d. per ton mile contract rate
1.4
Maintenance materials
3
Stores (fuel, explosives, drill steel, timber)
Cleaning at Prleska
2
Plant depreciation
3
Administration Expenses
3
Compensation, taxes, socialservices Freight from Prleska to Cape Town _2_
Total s
2_3 <
Stores Includes a cost of 1.5 per ton for s< For the eleven months ending November, 1948 ; total cost per ton excluding freight from Prleska to the Por
was 35 stg. per short ton.
m
ikff
ftUttXbb IN MA flfcK O KEYS V. MIDALCO NO 1161 OF 1987
,10
..............
NO 1 SB OF 19b7
X Grad fibre is very short and has only been
recovered recently* It Is recovered at Prieska froa the S grao
tailings and at Xoegus and Westerberg from re-treatment of the
alll tailings dumps* Although some of the faces examined in the
TTesterberg drives carried a total of 4* to 5n of fibre with a
maximum fibre length of l|B, the overall mine average appeared
to be about 2jM total fibre In an average stope height of 42ff*
Labour Force* The total number of operators employed at Koegas and Westerberg is as follows:
Europeans Natives underground
* 25 - 520
Natives on surface
- 260
Native women & children
Contract workers
- 150,
Natives employed elsewhere - 150
Total Cost of Production of Fibre - Table TV
CC
gC*CtoJ
53oto>>
.
ggW ts jLL Si*
*S<0>S&
pf
0
=iT.S0?.
^8
teVi, res, shaft, tea
Salaries fc Wages, Nine & hill Labour
17
Asbestos charges (made up of working expenses for motor vehicles etc*)
2
Transport Koegas to Prieska 6d* per ton mile contract rate
1*4
Maintenance materials
3
Stores (fuel, explosives, drill steel, timber)
6 29*'
Cleaning at Prieska
Plant depreciation
Administration Sbcpenses
. Compensation! taxes, social services 2 10*
Freight from Prieska to Cape Town _ 2
2*
Total :
41,
Stores includes a cost of 1*5 per ton for aaei For the eleven months ending November, 1948 a
total cost per ton excluding freight from Prieska to the Port
was 55 stg* per short ton.
|J^ . m,OALC0 1161 OF 1987
.11
PRODUCED IN MATTER OF BARROW V MIDALCO NO 1148 OF 1987
The cost dissections given above are as
detailed as the records kept at Koegas and it will :be observed
that a much more complete dissection is required to enable an
adequate check to be kept of the cost of individual operations
Until recently the supply of cheap labour has been such that
there has been no Incentive to keep accurate cost records.
Stores Costs - Table V
Explosives per 501b. case 4* X dia. or 4" x 1" dia. 34/6
Drill Steel per lb.
7d
Drill steel per ton
65.
Bails per ton
22-..
Ralls per yard
16.
Fuel oil per gallon
1/6
Fuel oil per ton
16.
Timber per 14 ft. pole 6n dia. 3/6
Timber per ton landed Koegas 4.
....... -
Timber Cost Dissection -
Material cost per ton
1.2
Rail transport cost
1.7
Hoad transport cost
;.-Q
< 4 3.9
Salaries and Charges per month and per year.
per month per annum
sterling sterling
Shift boss
25 to 30 360
kine Foreman
40 460
Ulne Surveyor
60 720
` A house, water, fuel and light are supplied
free to such employees.
Hatlve Rates of Pay.
lline boy
5/- per day
Boss boy
6/- per day
There are no organised compounds and messes at
Koegae or Westerberg and the natives find their own food and
^SyM,ALCO iWi OF jjgy
11
PKODUCtD IN MATTER Of BARROW V. MIOALCO NO 1148 OF 1967
The cost dissections given above are as
detailed as the records kept at Koegas and it will be observed
that a much more complete dissection is required to enable an
adequate check to be kept of the cost or individual operations
Until recently the supply of cheap labour has been such that
there has been no Incentive to keep accurate cost records*
Stores Costs - Table V
^Sterl IrL?
Explosives per 501b. case 4" x in dia* or 4n x 1" dla. 34/6
Drill Steel per lb*
7d.
Drill steel per ton
65*
Sails per ton
22*
Sails per yard Fuel oil per gallon Fuel oil per ton
16*
*
1/6
16,
Timber per 14 ft* pole 6n dla* 3/6
Timber per ton landed Koegas 4*
Timber Cost Dissection *
Material cost per ton
1*2
Bail transport cost
1.7
Boad transport cost
3.9
Salaries and Charges per month and per year*
per month per annum
sterling
sterling
Shift boss
25 to 30 360
Mine Foreman
40 480
Mine Surveyor
60 720
k house, water, fuel and light are supplied
free to such employees*
Native Bates of Pay*
Mine boy
5/- per hay
Boss boy
6/- per day
There are no organised compounds and messes at
Koegas or Westerberg and the natives find their own food and
HEYS V. MIDALCO
NO 1161 OF 1987
12
------lu iiS MATTER OF HARROW V. MJDALCO NO 1148 OF 1987
accommodation* On the Witwatersrand mines the natives are
paid at the rate of 5/- per day ot which 2/6 Is taken out to
pay for food and accommodation In the compound*
pSTATLS OF MIMING OPERATIONS*
Koegas. Mining operations are carried on at
three points north of the Orange River spread over a distance
of several miles* All three operations are underground and art
on different parts of the same seam or reef* The seam has bee:
worked out in earlier operations wherever it outcrops over the
greater part of a length of two to three miles* The areas
rc
which have been chosen for underground working are in small Isolated hills where the ore body is well above the surrounding ground level so that there is no need for hoisting ore from
underground operations*
Wellbach* This area is about three miles north
of the Orange River* The ore body being worked dips at about 55 flattening out somewhat about 200* below the outcrop* The
-ire body proved is about 750* long by 500' deep on dip* Baula,
levels are established at approximately 50* vertical Intervals
which gives a stope face approximately B0* to 100* long, on dip*
< Eaulageways are continued until they break through to an entran on the side of the hill and a sorting dump is then established the entrance* A road connects the several sorting dumps so tb A ore can be removed by lorry* Most of the ore has been removed
from the top three levels*
A European shift boss is in charge of the area
and there are four gangs of twelve men each with one jackhammer
The daily production from this area is about 15 tons of picked
ore equivalent to about three tons of fibre from the mill*
native women hand sort ore which is minus 6%
and native boys spall any ore greater in size than 6". All o
sent to the mill is minus 6n* Compressed air is supplied from a portable
compressor of 500 c.f*m. capacity locate^ at the bottom of the
4
rRODUCED IN MATTER OF HEYS V. M1DALCO NO 1161 OF 1987
12.
accommodation. On the Witwatersrand nines the natives are
paid at the rate of 5/- per day of which 2/6 is taken out to
pay for food and accommodation in the compound*
DETAILS OF MXKTffP OPERA?IONS.
Koeeas. Mining operations are carried on at three points north of the Orange Elver spread over a distance of -several miles* All three operations are underground and are on different parts of the same seam or reef* The seam has beer worked out in earlier operations wherever it outcrops over the greater part of a length of two to three miles* The areas which have been chosen for underground working are in small Isolated hills where the ore body is well above the surrounding ground level so that there is no need for hoisting ore from underground operations*
Wellbach. This area is about three miles north of the Orange River* The ore body being worked dips at about 55 flattening 'out somewhat about 200* below the outcrop* The ore body proved is about 750* long by 500* deep on dip* Eaula levels are established at approximately 50* vertical Intervals which gives a stope face approximately 80* to 100* long.on dip* Baulageways are continued until they break through to an entrai on the side of the hill and a sorting dump Is then established the entrance* A road connects the several sorting dumps so 13 ore can be removed by lorry* Most of the ore has been remove from the top three levels*
A European shift boss is in charge of the ares and there are four gangs of twelve men each with one Jaekhammc The dally production from this area is about 15 tons of picket ore equivalent to about three tons of fibre from the mill*
native women hand sort ore which is minus 5*, and native boys spall any ore greater in size than 6". All sent to the mill is minus 6B*
Compressed air is supplied from a portable compressor of 300 c.f*m. capacity located at' the bottom of tb
Its
6a
fSf
O.o 5 ^co w|iL JS.Q 2 <
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I"I m
PRODUCED IN MATTER OF HEYS V MIDAtCO NO 1162 OF 1987
03.
r- `'^CEDINMATIEROP
v MIDALCO NO {/48 OF 1987
hill in which the ore body is situated. Water is carted by
truck to a tank at the top of the hill. Maintenance is
carried out by a "flying squad" who travel to the various
mining centres from the workshop at Koegas as required.
Big Hill. This area, the most southerly of
the Koegas workings, is located close to the Orange River
immediately facing the Westerberg workings of which it appears
to,be a continuation. The ore body is 7 shaped in end elev
ation, approximately 1,000 ft* long and 200 ft. deep with the
outcrops at the tops of. the arms of the 7 about 100 ft. apart.
The seam forming one arm of the 7 is practically vertical,
while the seam forming the other arm dips at an angle of 45
to 60 to the horizontal* In some areas the seam .has been --
stoped out completely leaving a V shaped section of barren rocl
entirely supported on mine timbers*
In the vertical arm of the seam, the stope fact
Is stepped so that it lies at an angle of approximately 450 to
the horizontal, in order to provide safe working. The pro
duction from Big Bill is approximately nine tons of picked ore
per shift equivalent vo about three tons of asbestos per day*
Most of the stopes have been followed down fro
an outcrop rather than worked from below as is common
practice elsewhere. The latter method is coming into use on
'new'developments in the Westerberg area.
Mill Hill*. This ore body is somewhat similar
Big Bill measuring approximately 500* long by 150* deep. ?h<
fibre from this area is a more steely blue and is more like c:
shingle fibre in the way it breaks up into short sticks of fil
In parts of the workings where there are two
close together on a comparatively fist dip the hanging wall 1
supported by packing waste rock. Westerberg No. 2 Section. This area is bett
laid out ai*l mined on more orthodox principles than the older
Koegas underground workings. There are three seams of asbes
being mined referred to as the Main, Inner and Outer Reefs.
r'hOl'-.CED IN MATTER OF
HEYS V. MIDALCO
NO 2261 OF 2967
la
dip is approximately 80.
.... IN MATTER OF BARROW V MIDALCO, NO 1148 OF 1987
There is approximately 6* of barren
rock between the Main and Inner Beefs and after complete
extraction of the ore this membrane of rock is supported entirel:
by mine timbers. In places the footv;all of the Inner Reef is
punctured by the pressure from mine timbers supporting the
hanging wall in the Main Reef. The puncturing only arises
usually from failure to use headboards on the timber supports.
The stope face is benched in steps about 4* high
and stepping back 4' each time. Approximately three holes 3'
long are drilled in the horizontal step of each bench at an
angle of 60 to the vertical with the bottom of the hole towards
the stope face. (See Figure No. ) A stope drive about
100 ft. below the top of the stope collects the broken re which
is then drawn through a box hole to a haulage way about 12 ft.
below the stope drive. The ore is then hand trammed out to the
sorting dump. The method of using a stope drive is safer than
having a haulageway at the bottom of the stope. With the
latter arrangement there is a danger of tramming boys being
struck by ore rilling dorm the stope face. The stope drive act;
as a buffer storage for the broken ore.
It was estimated that the average for all of the
faces examined in Weeterberg Ho. 2 area was a total of 4" of
fibre* the mining width being about 48". She average face
would contain from eight to twelve veins from 1/10" 'to 1" in
fibre length.
At the south end of a development drift on the
Outer Reef approximately 200 ft. below the surface* there was a
total of 6" of fibre in a 48" seam over a length of approximate:
50 ft. along the strike. In only a few places was much fibre
seen over 1" in length.
Approximately five tons of asbestos per shift 1
produced from v/esterberg No. 2 area from four Jackhammers and
there was difficulty in providing sufficient labour for picking
on the sorting dumps because of the high production.
At Westerberg No. 2 there were approximately 8(
PRODUCED IN MATTER OF HEYS V. MIDALCO NO 1161 OF 2987
15.
PRODUCED IN MATTER OF BARROW V MIDALCO
NO 1146 OF 1987 -
n&tive women and children hand sorting to cope with the output
from four jackhammers.
The ore from this area was very Triable and
broke to minus 4" in the mine. The ore was discoloured with
yellow ochre dust from weathered ironstone.
It was estimated by the Underground Manager that there was probably a 10% loss of fibre on the sorting dumps. No system of screening has been evolved to prevent this loss of
fibre. Some attempt was being made to recover fibre trot
the sorting dump by feeding the stone over hand operated shaker
screens about 41 long by 2' wide having an upper deck of 1/2* mesh and a lower deck of 1/10" mesh, ttie material remaining on the top deck was discarded and the overs from'the lower deck
were sent to the mill. ffe^teybere No._4 Section. This part of the mint
is on the Main Seam south from No. 2 Section at the point where the reef begins to swing round to the east. The dip in this section is flatter than farther north, being approximately 30.
In this section there are small patches of fibre
approximately 2" long, this being a 0 grade fibre. In development work in this section a form of
burn cut Is used, referred to locally as a "diamond11 cut. Four holes 5' long are drilled, spaced in the form of a square at the face, the four holes running together at the bottom so that they form the edges of a square pyramid of 18" base and
5* height. A total of eighteen holes is drilled in a round,
the other fourteen holes being spread rourri the diamond cut which is fired first. An advance of l rounds or approximate!:
8 ft. is made per shift. 1-3/8" dl pwot-er
4 U. detachable bits are use
and these drill for 3r to 6* before being discarded. The explosive used is 7/6" or 1" diameter by 4"
long plugs of 40% ammonia-dynamite with a count of 400 sticks
per 50 lb. case.
.. +** $ '
PRODUCED IN MATTER OF
f'HUDL'CED IN MATTER OF BARROW V MlDALCO
HEYS V. MlDALCO
e
NO 1148 0F 1987
NO 1161 OF 1987
The minimum water pressure permissible it the
jackhammers In order to allay dust Is IB p*s.i* The air
consumption per jackhammer averages about 70 c*f*m*
Westerberg No* 8_ Sectl.op* This section Is on
the east side of the Westerberg Valley almost directly opposite
to Section No* 4* The dip here is also comparatively flat*
/II the upper levels in the slope above the valley floor have
been worked out art a shaft was being put into operation to
hoist ore recovered from seams below the valley floor*
4
The shaft was sunk about fourteen years ago but
work was subsequently abandoned In the area art the shaft was
never used*
( No core drilling has been oarrled out to deterai to what depth below the valley floor the seam dips, nor Is It
known definitely that the seam Is continuous with the seam on th
west side of the valley although It appears highly probable*
The fibre from No* 6 area Is dark steel blue in colour and the
rock Is also blue/black and shaley in appearance* This may be
due to the fact that weathering and oxidation have not taken
place to the same extent as on the west side of the vail*;/ where
there are many small fissures throughout the ore body*
c Sllphuis. Xliphuis is a small settlement about 40 miles east of koegas and also on the north side of the
Orange River* It was Inspected mainly because It was thought
to resemble the Wlttenoom deposit more .closely, so that the
mining system under such conditions could be observed* Wherea
the asbestos seams or reefs in the Koegas area are mostly steep
inclined and headroom Is therefore not a problem, at kliphuls
the seams are comparatively flat*
For the most part, mining In this area has
been carried out by contractors who have not worked to any
system art a start was being made at the time the mine was
Inspected to adopt a systematic layout* There is about 2*000 ft* of driving divided
between several drives and crosscuts, the height generally bei
only about 4 ft* to 5 ft*
: HARROW V M1DALCO
PRODUCED IN MATTER OF
NO l Ua OF 1987
HEYS V. M1DALCO
17.
NO 1161 OF 1987
0
The dip is about 5 Into the hill from the mine
entrance. The first drives made were across the dip to avoid
hauling up hill and in consequence are unnecessarily long. It
is now proposed to have a main haulage on dip and develop by
the stoping method used elsewhere*.
Ventilation is obtained by natural circulation
from an open ended crosscut up through the main haulage drift*
^ Fran examination of the faces at a number of
points the area appeared to average about 2" total length of
fibre. In places the total length of fibre in a face was as
much as 5n aslthe longest individual fibres seen were about 1}"
in length*
yiLLIW-G* General. The milling is a comparatively simple
process as the ore contains approximately 30 to 403 fibre and there is thus comparatively little rock to get rid of. The general circuit in both the Westerberg and Koegas mills consists of a primary jaw crusher followed by a trommel and picking belt, a shaker screen to remove fines, then a stage of roll crushing again followed by a trommel to remove fines and oversize. The middlings product from the trommel is then passed through a disintegrator and after further trommel screening to remove fines and short fibre, the milling is complete and the fibre coming from, the last trommel is bagged. However, this product is further treated at Prieska where approximately 20.1 of dust and stone is removed.
Attention is dravm to the fact that at no stage in the milling Is an aspirating process used for separating rod 'from stone or for cleaning fibre. This work is done exclusive: by reducing the rock to dust by roll crushers and disintegrator: and removing the dust by means of a trommel screen.
This process results in a much more open or teased fibre than is produced by the mill at ?/ittenoom
**'
(
c
\
PRODUCED IN MATTER OF HEYS V MIDALCO
13.
NO U62 0F1967 V/esterberg ?T11T.
H%U>UCll IN MATTER CP
HARROW V MiDAlCO NO l MS OF 1987 ,
Details. The ore is brou;
to the mill by road from the areas in Xoegas and V/esterberg Vai:
and also from Kuruwan, Black Bidge and other outlying centres.
Ore from each area is dumped in separate stock piles so that it
may be treated separately. The maximum size of ore handled is
about 6".
The ore is wheeled in barrow loads from the
various dumps and tipped on a steel plate for convenient
shovelling, above a small jaw crusher. The crusher is about
14" x 6n and is fed by hand shovelling. The ore from various
working places differs considerably in its appearance and each
ore is milled separately in order to keep a check on thevtonnage
produced and the yield*
The ore from the Westerberg area is" considers^
weathered and contains a lot of yellow ochre which tends to
discolour the fibre. On the other hand ore from the Black Rid*
area is of a dark blue colour and has a flaky fracture like sh
From the Jaw crusher which has a minus 2"
product, the ore passes through a tapered trommel 6fHong, 4ft.d
of 1/2" mesh revolving at 16 r.p.rc. Oversize goes to a pickln
belt about 40 ft. long running at approximately 30 ft. per aim
where six native women remove approximately lCtf of waste rock*
The ore then passes .through a second Jaw crusher being reduced
-minus 3/4, and discharges together with the throughs from.the
trommel on to a 1/16n mesh-10 ft. x 3 ft. shaker screen driven
approximately 600 strokes per minute to remove fines which go i
waste.
The overs from the shaking screen are furthe:
reduced by a pair of rolls 24" diameter, 12" face, running at
approximately 100 r.p.ra. and then pass through a 1/16" mesh tr
driven at about 12 r.p.ra. The throughs from this trommel go
waste and the overs, approximately 1/4" in size, pass to a
disintegrator running at 1800 r.p.m. The machine is made by
Christy and Norris and has four quickly detachable arms with
separate beater heads (xex `drawings and sketches Fig: & )
c
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Si*
HtVS V. MiDALCO NO U6i OF 1967
19.
ri.'JUUOb IN MATTER OF faARROW V MIDALCO NOJNfiOF|9g7 .
It is possible to change the disintegrator beaters in about
three minutes plus approximately five minutes lost milling time
The beater arms are changed every four hours.
The crushing roll surfaces are ground by hand
each week to remove ridges and about every six weeks are turned
in the lathe. The life of a set of roll shells is about 18
reeks* in which time about 7000 tons of ore would.be crushed.
It was estimated from a visual examination
that the throughs from the 1/16" mesh trommel contained approxi
mately 10.3 of fibre of 1/8" and less In length.
The disintegrator opens out the fibre to
approximately the condition in which it Is used in an asbestos
cement plant. The fibre from the disintegrator is passed throu<
a trommel 9 ft* long* 4 ft* dia., 12 r.p.m.* the first h&if of
which is covered with 3/16" screen and the rest with 3/8" screen The throughs from the first section are sent to an adjoining
tailings treatment plant for recovery of X grade fibre* the
throughs from the 3/8" section* consisting mainly of stone and
small bundles of unopened fibre* are returned to the disintegrat
and the overs are bugged as S grade fibre to be sent to Prieska
for cleaning*
The fibre discharging from the trommel drops
on to a grid of inclined bars which further assist in removal of
stone from the fibre* short sticks of fibre and stone dropping
through the bars are shovelled up and returned to the dlslntegrz
The fibre is picked up on forks and filled into bags of 100 lb*
ileuvy hand ramming is necessary to get the quantity of fibre In
the bag. Jute bags of a similar quality to those at Wittenoom
are used*
There was a considerable dust nuisance in the
plant although some attempt was made at the shaking screen and
'the disintegrator to house over the units causing dust. There
v/ere no exhaust fans used for removing dust.
Plant Capacity. It was claimed that all ore
to produce 25 tons of fibre per day was treated in the Westerbe
mill. This requires a throughput of 6039ns Of ore per day
H<ODUCD IN MATTER OF HEYS V. MiDALCO NO 1161 OF 1967
.20
i i .`jUuuLD IN MATTER C'
BARROW V MIDALCO NO 1148 OF 1987
assuming that 20* stone and dust remains in the fibre. The
average hourly rate is thus about 6 tons per hour through the
jaw crusher and about 4 tons per hour through the disintegrator.
Mill Building. The plant is arranged on the
side of a small hill to obtain gravity flow where possible. The
building is timber framed with corrugated iron covering, about
0 ft. wide by 60 ft. long. See photograph, page- <
Labour. One European and eighteen natives per
shift produce 24 tons of Asbestos Fibre per day on one 12 hour
shift. The European acts as Mill Foreman and Maintenance Fitter
Koegas MiH. Tailings Treatment. Originally the Koegas Mill was similar to the Y/esterberg Mill but since extensive re-treatment of tailings dumps has been undertaken, the Koegas Mill has been used exclusively for this purpose. A new mill is in course of construction at Eoegas and is described late
The tailings are reclaimed from dumps around th Mill and fed through a Christy & Morris disintegrator. 2he mate lal discharged from the disintegrator is passed through a trommel having 1/Bn screen from which the oversize material is bagged as X grade fibre. Throughs are fed to a trommel having l/16n scree opening, the oversize from this trommel being returned to the disintegrator and the throughs discarded as tailings. The X gr* fibre from this plant still contains a considerable amount of du. and stone and the fibre is given further trommel treatment at th cleaning plant in Prieska. See sketch of mill circuit. Fig.
phe New Koeeas Plant. The new Koegas Plant w designed primarily by Ur. Sinclair and follows the general prlnc used in the other Cape Asbestos Mills, depending on trommel sere for cleaning arid separation of the fibre from the rock.
The plant is arranged on the side of a slope : that for the most part gravity feed is obtained through the pro cess. The plant is driven by line shafting from an engine hou in a dustproof building alongside the mill.
Ore will be fed by hand from a steel "lashing plate into a Jaw crusher set to about ljn discharge. The
PRODUCED JN MATTER OF HEYS V. MIDALCO . NO U6JOFJ967
.21
maximum size of ore is about 6" The jaw crusher discharges tc
a trommel having 1/2" openings from which oversize passes on to
a horizontal picking belt about 30 ft* long which discharges to
second jaw crusher* Undersize also drops on to a belt conveyor
The fines from the belt conveyor and the
throughs from the jaw crusher discharge on to a shaking screen
of 1/6" mesh, the throughs from which go to the tailings treatme.
plant* Oversize from the shaker screen Is elevated in an
Inclined bucket elevator to a set of crushing rolls about 16*
diameter by 12* face set to 1/4** ft second pair of rolls In
series follows set to 1/8"*
The discharge from the second set of ro'tls pas;
through a trommel, the first part of Milch is covered with 1/16"
mesh and the second part covered with 1/2 mesh* Throughs from
t
the first section go to waste and oversize from the second sectlc
is returned to the second set of rolls* Throughs from the secoi
section are fed to a disintegrator which discharges to a 1/16"
trommel*
Throughs from this trommel go to waste and ove
size goes to another trommel, the first section of which Is
covered with 3/16" mesh and the second section with 5/16" mesh*
Throughs from the first section go to tailings treatment plant
and throughs from the second section are returned to the dis
integrator* The oversize product from this trommel is the
finished fibre*
As this plant was not working it was not
possible to determine the speeds of the various units or the mi:
capacity* It was anticipated,* however, that this mill would
have at least 50* more capacity than the V/esterberg Mill*
. *'*' *
PRODUCED IN MATTER OF HEYS V. MIDALCO NO 1161 OF 1987
.22
l-LCED IN MATTER OF BARROW V MIDALCO
NO 114$ OF 1987
CLEA'iriO_PLAHT - .PRIESKA
General. Fibre is received at Prieska from
all tbe mining areas at Xoegas, Westerberg, Kuruman and
Kliphuis* The fibre has already been milled and roughly
graded into X, S, A, B, C or D grades and tbe treatment at
Prieska is to blend, open and remove stone from the fibre in
order to obtain a cleaner and more uniform product*
There are large storage warehouses at Prieska
sufficient for several thousand tons of fibre* Prieska also
serves as a base for the receipt'and. despatch of stores to the
various mining areas* The total operating labour employed at
Prieska numbers 130 natives and there are 10 Europeans Including
clerical staff*
,
Power Is generated as required from oil engine
Blending* S grade fibre is put through the
cleaning plant in batches of 1200 bags (60 short tons)*
She number of bags in each batch from each of
the different areas is roughly proportional to the production fs
the area and a constant "formula" for this blending is worked t(
Ihis is necessary because fibre from different areas varies in
colour and texture and a fixed proportion oust be maintained to
give a uniform product* She fibre Is emptied from the bags in
a large open bln on the floor, the fibre from different areas
being placed in layers right across the whole area* The bln
measures approximately 60 ft* x 50 ft*
Feeding. The fibre is fed by hand using a
multi pronged fork to shovel the fibre into the boot of an
inclined open bucket elevator, the tall pulley of which is abo'
3 ft* below the floor level* There are three feed points and
three parallel lines of similar cleaning plant*
From the three feed points the bucket elevat
travelling at ISO ft* per minute, deliver to three trommels Is
parallel, the trommels being 9 ft* long, tapering from 3 ft* t
5 ft* diameter, revolving at 16 r*p.m* and covered with 3/16"
screen. 3fce throughs from the trommels drop on to a belt
i ____
ri7'LA^LD IN MAl'ILK^iF
WODUCED IN MATTER OF
uaKKCAV V MlDALCO
HEYS V. MlDALCO
o-x
NO 1J4 OF 17
NQMlQflW
conveyor and ere delivered to a disintegrator Tor further
treatment* The oversize from the trommels drops into a second
inclined elevator consisting of slats attached to a rubber belt
conveyor* This elevator delivers to a hammer mill running at
1200 r.p.m.
Hammer Mill* The hammer mill is locally
designed and built in Johannesburg and consists of. a light mild steel casing with a serrated wear plate covering an arc of
approximately 45 of the circumference* The plate is spring
loaded and has a screw adjustment for taking up as it wears* Tk life of the plate Is from two to three weeks. The hammer rotor is approximately 18tt diameter and has four beaters -attached by two radial arms to the rotor, the beater blades being 10* wide and 2" x 1* cross section. (See drawings and Figure Ho*
*
The beaters are reversed after two shifts1 running and have a
total life of three days* The hammer mills discharge to a third inclined
elevator which feeds the fibre into a cleaning trommel similar tc the first trommels and covered with 5/16n mesh. The through: fr^z the three cleaning trommels drop on to a belt conveyor and are returned for further processing. The fibre .discharged from the trommel is filled into bags as the finished S grade'product*
Bagging. At each bagging station there Is a native shovelling fibre Into the bag, a second native stamping
dorm the fibre using two heavy wooden clubs and a third man carrying bags away for sewing and stacking. Natives working around the discharge from the trommels wear gauze pads strapped across their mouths*
ftetreatment. The throughs from the three
cleaning trommels are returned to a fourth trommel of 3/16n
mesh in line with the first set of trommels. Oversize materia from this trommel which should be all fibre, is conveyed back t tiie blending bin and passed through the cleaning circuit to be recovered as S grade fibre. The throughs from the trommel joi the throughs from the three other primary trommels and are ele%
to a fourth hammer mill arranged in line >Vth the other three*
w
Produced tn Asbestos Personal
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PRODUCED IN MATTER OF HEYS V. MIDALCO
4.
.. _ DLCrX) IN MATTER OF UARROWV MIDALCO
NO 2262 OF 2987
NO 1146 OF 1987 -
The product from the hammer mill which Is
driven at 1800 rp*m* as compared to 1200 r*p*ra for the other
three, Is elevated to a trommel In line with the three S grade
cleaning trommels* The first half of this trommel Is covered
v/itb 1/6" mesh screen and the rest with 5/16n mesh screen* The
throughs from the first section are collected on a belt conveyoj
and delivered into a 3/4 ton mine car for delivery to the edjoii
tailings treatment or X grade plant* The throughs from the
second section of the trommel join the through's from the cleanir
trommels and go through the return circuit* Overs from the
trommel are bagged as S grade fibre*
Dust Collecting* All trommels and the.elevat
between the hammer mills and cleaning trommels are enclosed aai
connected to a dust collecting system* There are four fans, oi
located alongside each hammer mill* Each fan draws through a 5
duct from each of the two trommels and a 6" duct from the hamme:
mill discharge chute on each of the four parallel lines of tree
plant*
The fans are approximately 24" diameter ruxrnl
at 1800 r*p*?u* and have 14" diameter delivery ducts* It Is
estimated that each fan has a capacity of approximately 4000 c
The fans deliver to a dust room, a brlolc building 40 ft; long a
20 ft* wide x 12 ft* high alongside the mill building* The a:
enters the dust room through the ceiling at one end, passes un
a central baffle and is discharged through two stacks 3 ft*
diameter, 20 ft* high* The discharge from the dust room appe
as a fine ha2e*
There are two cleaning doors in the wall of
building (see. photograph, page ) and the dust is shovelled
bags at the end of the treatment of each batch* Approximate:
20 bags or 1 ton of dust and short fibre Is recovered from eat
batch of 60 short tons* This material is sent-to Cape Asbes
Insulation plant at Benoni near Johannesburg* The maximum 1
of fibre in the shorts is X/16n
Power* All of the above plant is driven by
42 h*p National oil engines through a series of counter sh&f
belt drlyes.
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M :ODUCD IN MATTER OF
PRODUCED IN MATTER OF HEYS V. MJDALCO
25.
BARROW V MIDALCO NO 1148 OF 1987
NO 1161 OF 1967 Buildings* The main mill building Is approxi
mately 180 ft* x 75 ft* wide x 20 ft. high. The walls and roof
of the building are covered with corrugated Iron and the frame
work is of steel sections. An area of the building 50 ft. x
75 ft. is used for the storage and blending of fibre. The
cleaning plant takes up approximately 80 ft. x 75 ft. ani the
remaining 50 ft. x 75 ft. Is used for sewing and stacking clean
fibre.
There are two storage warehouses, approximately
400 ft. long x 40 ft. span with a rail track between.
Labour; The operating crew for the cleaning
plant consists of 50 natives and 3 Europeans, the latter being-
responsible for maintenance and running of the plant. The plant
operates for approximately tea hours per day. ------------
~
The natives are paid 5/- per day with a maximum
of 6/- per day for boss boys. Quarters are provided for the
natives but they provide and cook their own food. Of the 5/-
per day, 2/6 is intended to represent living allowance.
Plant Capacity. The plant treats fibre at the
rate of about 100 bags (6 short tons) per hour and a batch is pu*
through in from 1 to 1& shifts.
20;1 to 25 stone and dust is eliminated from t:
feed. The bagged fibre contains an average of stone and
should not contain more than 5JC.
Of the material screened out of the S grade
fibre, approximately 16 is recovered from the tailings treataec
plant as X grade fibre so that the overall recovery from the S
grade fibre fed to the cleaning plant is from 8D,T to 83$.
Testing. The Prieska Manager (Plant Super
intendent) checks the amount of stone in the fibre by hand pick
through a 40 oz. sample each day.
Tailings Treatment Plant. General. The
tailings treatment plant has been built as an annexe to the
main plant (see photographs page ), and is being operated on
two shifts at present to cope with the output from the Koegas
tailings treatment plant in addition to the handling of the ^a '
nOt .CCD IN MATTER OF KEYS V. MIDALCO NO 1161 OF 2987
26.
PRODUCED IN MATTER OF BARROW V MIDALCO NO 1146 OF 196?
tailings from the Prieska S grade cleaning plant.
Plant. The tailings from the S grade plant
are elevuted on an inclined conveyor and fed Into a Christy &
Norris disintegrator running at 1800 r.p.m. The product from
the disintegrator is discharged into a trommel 9 ft. long,
tapering from 4 ft. to 6 ft. diameter, and driven at 8 r.p.m.
The first half of the trommel is covered with il6R mesh and the
throughs from this section go to waste. She rest of the trommel
is covered with 1/8" mesh screen and the throughs from this -
section are returned to a 1/16B mesh 6 ft. x 3 ft. Bummer vibrat
ing screen driven at 1200 r.p.m. by a lj lew H.G. set. The over:
from the trommel are bagged as X grade fibre.
The Bummer screen is mounted on twelve flat
springs set at an angle of approximately 45 to the vertical,
Throughs from the Hummer screen go to waste and the oversize jol
the feed to the disintegrator.
There Is a second trommel 9 ft. long, tape] ini
4 ft. to 6 ft. diameter, covered with 1/16" mesh through which
the X grade fibre from Koegas Is passed for a final cleaning^
The oversize product from tills trommel is mix
in the proportion of tv/o parts to one with .the product from the
Prieska X grade fibre and bagged as the finished X grade* produc
The whole of the above plant including the V.
set is driven by a 27 h.p. Ruston engine.
Eighteen men and one European per shift are
employed in the plant and it is operated for two shifts.
The output of X grade fibre is approximately
short tons per day.
Long Fibre. Band cobbed fibre which is sold
as A, B, C or D grade is sorted, blended and cleaned by hand a
Prieska. Several bags of fibre are tipped out on to a concre
platform approximately 10 ft. square and picked over by hand
(see photographs page ), to remove any discoloured fibre o:
fibre which is of a higher or lower length grade.
There is a considerable proportion of what :
PRODUCED (N MATTER OF
PRODUCED IN MATTER OF
BARROW V MfDAECO
HEYS V. MIDALCO
27*
NO 2248 OF 1987
NO 1161 OF 1987
referred to locally as "discoloured" fibre, which is sooev/hat
similar to the material knovm at iVittenoom as dead fibre* 'The
fibre is of a reddish colour and somewhat more brittle than
good quality blue fibre and appears to have suffered some ozidat:
from weathering* Apparently the fibre has a market value but i'
presence in blue fibre is a serious defect*
Differences in colour and texture of fibre froi
the different areas are most apparent in the longer grades*
After the sorting and cleaning, fibre is baggec
again by hand*
The total of A, B, C and D grades represents
10 of the total output*
Including the variations of A, 3, C and D grad<
which Include discoloured grades and different quality fibres of
r
the same grading, there is a total of approximately SO grades of
fibre*
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V ODUCED IN MATTER OF JARROW V. MIDALCO
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West side of Westerberg Valley showing a large
c sorting dump In the centre foreground*
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West side of Westerberg Valley showing sorting dumps In the foreground and centre and vertical stopes in the hill in the background*
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Cleaning plant at Prleska showing short fibre recovery plants*...
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