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A .review of some aspects of shaft design

by G. W. HOLL, Pr. Eng., Associate of the Mine Managers Association of South Africa (Fellow)-and E. G. FAIRON, Pr. Eng., F.S.A.I.E.E., M.I. Cert. M.E.E., M.I.Mech. E., (Visitor) t

SYNOPSIS

The reasons for the choice of vertical shafts in preference to inclined shafts of comparable capacity are set out,and the conclusion that the former are superior in virtually all circumstances is substantiated.

The shapes of vertical shafts sunk during the past sixty years are recorded, and the shapes of those sunk duringthe past decade are analysed. From this analysis it is clear that circular and elliptical (and quasi-elliptical) shafts arethe shafts of the future and that the rectangular shape will conceivably become obsolete.

The determination of the size of shaft is discussed and it is forecast that shafts of a diameter of 13 metres and overwill probably be sunk without difficulty in the years to come.

The depth of the shaft is determined intrinsically by the Mines and Works Regulations applicable to factors pfsafety of winding ropes and the design of the winding system. The Blair winder is the most suitable winder forhoisting rock, men, and material from a depth of, say, 3000 metres on an economic basis. Tertiary shafts will, there-fore, be unnecessary in future deep-level mining projects at the limit of depth now envisaged.

A few other factors relating to shaft design are described.

SINOPSIS

Die redes vir die keuse van vertikale skagte in voorkeur tot skuinskagte van vergelykende kapasiteit word uit-eengesit en die gevolgtrekking dat die voormalige meerwaardig is in feitlike alle opsigte word bewys.

Die vorm van die vertikale skagte, wat oor die laaste sestig jare opgeteken is, asook die wat oor die afgelopedekade gesink is, word ontleed. Dit word duidelik afgelei van hierdie ontleding dat die sirkelvormige en eliptiese(en byna-eliptiese) skagte die vorms van skagte van die toekoms is en dat die reghoekige vorms desmoontlik uitgebruik sal gaan.

Die bepaling van die grootte van die skag word bespreek en dit word voorspel dat skagte van 'n deersnee van 13meter en meer moontlik sonder moeite in die toekomstige jare gesink sal word.

Die diepte van die skag word bepaal deur ingewikkelde Myn en Werks Regulasies wat toepaslik is op faktore vanveiligheid van wentoue asook die ontwerp van die hystoestelsisteem. Die Blair hysmasjien is mees geskik vir diedie hys van rots, mense en materiaal vanaf 'n diepte van ongeveer 3000 meters op 'n ekonomiese basis. Tersiereskagte sal desmoontlik onnodig word in die toekoms van diepvlak myn projekte tot op die diepte wat tans in sig is.

Sommige ander verwante faktore van skag ontwerp word ook beskrywe.

INTRODUCTION

In the past much has been writtenabout shaft-sinking operations, al-most invariably incorporating a des-cription of the design features of theparticular shaft as part and parcel ofthe general description of the works.Less literature is available on thebasic work of designing shafts ingeneral, though, as a general sourceof information, the Transactions ofthe Institute of Mining Engineers,London, those of the Mine ManagersAssociation of South Africa, andthose of this Institute may be con-sulted.

The authors of the present paperwill attempt to treat the subjectfrom the more basic aspects in thehope that some useful informationwill flow and that general discussionmay bring out further amplificationof the ideas mentioned in this paper.

Shafts have, in the past, generallybeen associated with mines, but

*Managing Director, Shaft Sinkers (Pty.)Ltd, and Mining and EngineeringTechnical Services (Pty.) Ltd.

t General Manager, Mining & Engin.eering Technical Services (Pty) Ltd.

more and more shafts are being sunkfor purposes other than to produceore from the earth's crust. Thesenon-mine shafts serve as means ofaccess to excavations used for the:

(i) diversion of river systems;(ii) production of hydro-electric

power;(iii) provision of underground road

and railway facilities;(iv) underground storage of water,

oil, and other commodities, e.g.atomic waste materials;

(v) foundation structures of high-rise buildings.

The excavations for high-risebuildings initially provide valuableinformation on the bearing charac-teristics of the soil and rock for-mations on which the building willbe constructed and, finally, whenfilled with concrete, form the mainfoundation support of the high-risebuilding.

It is generally true to say thateach shaft is tailor-made for thework envisaged during the life ofthe project it is to serve. In mining,the essential feature in determiningthe cross-section of the shaft is the

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

quantity of air to be supplied to theworkings, whereas, in civil-engineer-ing projects, it is the size of themachinery and the equipment to behandled in the shaft that determinesthe shaft area.

In the Republic of South Africa ashaft is defined as:"any tunnel having a cross-sectional

dimension of twelve feet and overand

(a) having an inclination to thehorizontal of fifteen degrees orover, or

(b) having an inclination to thehorizontal of less than 15degrees but more than 10degrees, where the speed oftraction may exceed fourhundred feet per minute [122metres per minute]".

This definition is designed todistinguish a shaft from a winze orinclined rope haulage, the regu-lations for which are much lessstringent. For the purpose of thispaper all tunnels having an incli-nation of more than 10 degrees fromthe horizontal will be treated asshafts.

MAY 1973 309

nc ma IOn 0 eng 0 ength of Percentageorebody vertical shaft incline shaft Increase in lengthdegrees metres metres %

15 1098 4085 272,020 1098 3110 183,225

I

1098 2531 130,535 1098 1890 72,145 1098 1555 41,655 1098 1341 22,265 1098 1220 11,175 1098 1159 5,6

SPECIFIC TYPES OF SHAFT

:For the purpose of this paperthere are only two types of shaft:(i) inclined shafts, and

(ii) vertical shafts.In the past, a large number of

inclined shafts were sunk for theexploitation of mines or sections ofmines, but this type of shaft hasnow become almost obsolete as amajor production unit. Mullins andHaggiel give the following infor-mation on the shafts serving 105mines in the Union of South Africaat 31st December, 1959:"Of these shafts 315 are vertical and

208 are inclined. There are nocompound shafts but several of theinclined shafts vary in inclinationalong their length. Of these shafts,395 are rectangular, 119 arecircular, and 8 are elliptical insection."

From this statement it is clearthat, at that date, no fewer than40 per cent of the shafts were in-clined, and the vast majority wererectangular.

Although the vertical shaft isgenerally favoured in mines undervirtually all conditions, the authorsare not aware of any literature thatclearly sets out the reasons for thispreference. The following argumentis an attempt to define as accuratelyas possible why, for a comparableoutput of ore, men, and material,vertical shafts are superior to in-clined shafts.

At present the use of the inclinedshaft is limited to:

(i) a prospecting operation;(ii) the provision of ingress to and

exit from workings associatedwith high-production tabular-ore deposits, particularly forlarge items of machinery and forthe conveyance of men andmaterial by high-capacity busesand lorries; (the ore producedfrom these mines is neverthelesshoisted through vertical shafts);

(iii) coal mines, where the deposit isshallow and a conveyor belt orendless-rope system is used forthe conveyance of coal; meninvariably walk into the mine,and the material is minimal inrelation to the mineral output.

In the first case, the inclined shaftsare of small size and seldom consistof more than three small compart-

310 MAY 1973

ments. These shafts are placed on orclose to the ore body and, at depth,are usually overmined almost im-mediately because of their extremevulnerability to the rock stressesthat develop as soon as stopingoperations begin. Several such shaftswould be required to cater for theoutput of the average mine becauseeach unit caters for only a limitedmining area.

In shafts used exclusively forthe movement of men and materials,the inclination is limited to at most14 degrees and, more usually, only10 degrees or less because of theeffect of steep gradients on the sizeof engine required for the busesconveying personnel and for thelorries transporting the materialsrequired underground. As the depthof the workings increases, these in-clines become extremely long, andcertainly at depth would become un-economical to maintain because oftheir size, which provides for twolanes of traffic.

Inclined shafts have a limitedlength, the longest known inclinesbeing of the order of 2043 metres.These shafts therefore cater for onlya limited depth, depending on theinclination of the ore body. At in-clinations of below 25 degrees, thelength of incline to reach the verylimited depth of 1000 metres be-comes virtually prohibitive, i.e. 2530metres at 25 degrees and 4085metres at 15 degrees. Finally, it isestimated that the cost of mainte-nance and power consumption ininclined shafts is at least 3t centsper tonne hoisted more than thatfor vertical shafts of equal capacity.

To illustrate the actual relationbetween the effectiveness of inclinedand vertical shafts, the followingmodel was studied.

On the assumption of a rate of

67 000 tonnes hoisted per monththrough a shaft, and of a moderatevertical depth of mining area of976 metres, a layout of the shaft andthe necessary tunnel for the exploi-tation of ore bodies of various in-clinations was prepared. To makethe comparison as accurate as pos-sible, the layout for the inclinedshaft incorporates tunnels into thefootwall so that only two mainhoisting points are established overtheir length as would be the case in avertical shaft. Further, the inclinedshaft is placed 90 metres, measuredin a horizontal plane, from theorebody to permit adequate storagespace on each station for materialsthat are to be transported to theworkings by locomotives, as well asto permit the transport of ore andwaste to the orepasses (see Fig. 1).

Using this model, a series oflayouts was prepared for incli-nations from the horizontal of theore body from 15 degrees to 75degrees in 10-degree steps. Thelength of the two types of shaft andthe horizontal tunnels applicable tothis model were thereafter measured.The results shown in Table I wereobtained (see also Graph I).

The cost of sinking, lining, andequipping an inclined shaft havingan output comparable with that of avertical shaft is at best approxi-mately identical. Therefore, on thebasis of shaft length only, inclinedshafts could not be considered as aserious competitor to vertical shafts.

The fundamental consideration,however, is the amount of horizontaldevelopment required to reach theore body and also to provide for atmost two loading points in the shaftsystem. The length of the ore-passsystems is then common to bothshaft systems. In the first instance, avertical shaft placed in such a

I r t th f

TABLE IComparison of lengths of shafts

Lf L


INCUNENORMAL VCRTICAL

ITEM VERTICAL SHAFT INSHAFT SHAFT FOOTWALL

LENG TH 6200 FT. 3600 FT.1600 FT..-,

LENGTH OF 6200 FT. 10000FT. 21,600 FT.CROSS CU TS

LENGTH OF 3000 FT. 3000 FT. 2BOO FT.ORE PASSESN? OF

COMPAR TMENTS 3 2 2

SIZE OF SKIPS /51 9.51 9-51

HP OF HOISTS 2500 2000 2000

"<

. FIG.1

~P 350111,00FT.-+--r--h I11 I1' I600 FT. I:..,-~~ \11

\

11

\1200FT.-r+ -

11 I11 I)' I

1600FT. 11--+-I1I

2000 FT. f---4t f -~- =~~-~~ =~ ~--- =~11

I11

I11

I21,00FT~- --- ~--~~~~~--~11 \11 \

2BOOFT.~_~~~ ~~~==~~~===~~~~

I' I1I /

3200FT.~ = --~11 I

~b

position as to pierce the orebody,thereby requiring a shaft pillar(termed a conventional verticalshaft) is considered and, in thesecond case, a vertical shaft placedin the footwall of the ore body(termed a footwall vertical shaft).Table Il and Graph Il show therelationship between the horizontaltunnel lengths required for the con-ventional vertical shaft as comparedwith the inclined shaft, and Table IIIand Graph III show the comparisonrelating to the footwall verticalshaft.

There is again nothing in favourof inclined shafts under these circum-stances, since the horizontal tunnelsare at most 30 per cent greater atthe flatter inclinations and thesteeper inclinations favour the ver-tical shaft. The average 25 per centincrease in horizontal tunnel lengthis easily offset by the increasedlength of the inclined shaft re-quired.

Under these circumstances, theadvantage of the inclined shaft isapparently well established on thebasis of the additional horizontaldevelopment required. However, forcomparative outputs, the overall

75

65

GRAPH1

GRAPH SHOWING RELATIONBETWEEN.

LENGTH OF SHAFT & INCLINATIONOF

ORE BODY

V)

!jjQ:

fBQ

55

INCLINED SHAFT

::...Q

2. '5~0lI..0

~ 350i:::

~::;~ I'

25

ERTIC~L SHAFT

15

1000 2000 3000 4000

LENGTH OF SHAFT -METRES

5000 6000

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MIN!NG AND MJ;TA~LI,IRGY MAY1973 ~H

Lengths of horizontal tunnel

I

Inclination of

I

Percentage increaseorebody Inclined shaft Vertical shaft over inclinedegrees metres metres

I

%

15 6066

I

7742 +27,6

20 4450 5791

I

+30,125 3672 I 4450 +22,735 2499

I

3048 I +22,045 1707 2225 I +30,355 1402 1646

I

+17,465 1219 1158 - 5,075 1219 853 -42,9

i I

TABLE IlComparison of horizontal tunnel lengths for inclined shaft versus conventional

vertical shaft

75

65

GRAPH.II.SHOWING RELA TION BETWEEN HORIZONTAL

DEVELOPMENT REQUIRED TO REACH THE

OREBODY. CONVENTIONAL VERSUS.

INCUNED SHAFT

V')

l1Jet

ffiClI

::...Cl0Q:)

~0IJ..0

<:0i::

~:::;u<:.....

55

45

35

25

INCLINED SHAFT

15

2000 3500 6500 60005000

HORIZONTAL TUNNEL LENGTH-METRES

TABLE IIIComparison of horizontal tunnel lengths for inclined shaft versus footwall vertical shaft

Inclination ofore body

Horizontal length of tunnel required

Inclined shaftI

Footwall verticalshaft

metres metres %

Percentageincrease

degrees

--------1520253545556575

60664450362724991707140212191219

193,9201,4195,5197,6228,5208,7165,1

90,0

1783113 41110790

7437.5608432832312316

312

.9500

costs of the shaft are approximatelyequal and, if it is accepted that theequipped inclined shaft is five timesas expensive as the fully equippeddevelopment, then the more accuratecomparison should be as shown inTable IV.

From Table IV it is obvious thatthe inclined shaft under these cir-cumstances should be consideredonly for inclinations of 30 degreesupwards, where the design andoperational difficulties are highest,and, even then, it has only a limitedadvantage of some 1711 metres ofdevelopment, which, on the basisconsidered here, is equivalent to342 metres of inclined-shaft length,or in monetary terms some R450 000.

However, the following additionalfactors require consideration.(a) In comparison with the con-

ventional vertical shaft, there isthe question of the loss of thefinancial return on the profits,over the life of the project, fromthe ore locked up in the shaftpillar required for the verticaltype of shaft, and the subse-quent problem of extractingthis ore at the end of theproject's life.

This aspect could be lookedat in two ways. Either the shaftpillar could be extracted at thebeginning of the mining opera-tions, when it is generally acomparatively simple operation,or, where this step is not ad-visable, e.g. in water-saturatedformations, a monetary valuecould be assigned to this factor.For the depth envisaged in theselected model, the shaft pillarwould not exceed a radius of300 metres and would contain,over a stope width of 2 metres,not more than, say, 153000tonnes of ore. At a profitmargin of R2 per tonne, the lossof interest on this profit over a30-year life of the project would,at 7t per cent per annum,amount to R2,7M.

(b) The cost of maintenance of theinclined shaft in comparisonwith that of the vertical shaftwill offset the above advantagecompletely over the same period.

It is estimated that thisdifference amounts to approxi-mately 3t cents per tonne

MAY 1973 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

~~--~~152609 13045 11 765 -1280

20 2012 10060 8961 - 109925 1433 7 165 7 163 235 792 3960 4938 + 97845 457 2285 3901 + 16165.5 243 1215 2926 + 171165 122 610 2012 + 140275 61 305 1097 + 792

Inclined shaft Footwallvertical shaft

months months

3,0 6,070,7 16,7

0,0 2,02,0 2,01,5 0,53,0 0,4 concurrent4,0 34,0

84,2 61,6

15,0 ton 9,5 ton2500 2000

hoisted. The monetary value ofthis factor over 30 years isassessed at R2,9M at 7! per centper annum, and this amountoffsets the first-mentioned con-sideration completely. In adi-dition, this aspect completelyanswers the question of theadditional development fromthe use of the footwall verticalshaft, when no shaft pillar isrequired, as compared with thatof the inclined shaft.

(c) The rate of exploitation of theore body should the project re-late to a new mine.(i) The average speed of sink-

ing, lining, station-cutting,and equipping an inclinedshaft is extremely low. Itis 22 metres per month ascompared with 66 metresper month for the similarlyequipped vertical shaft.

(ii) The average hoisting speedis 530 as against 915 metresper minute -1 to 1,7 infavour of the vertical shaft.The length of the wind is asillustrated in Table I.

Thus, Table V illustratesthe estimated time of comp-letion, the skip sizes, and thehorsepower requirements of thetwo types of shaft for an out-put of 75 000 tonnes per monthfrom an ore body dipping at 35degrees.

There is therefore much to besaid in favour of the verticalshaft if a new project is beingconsidered.

Often, however, it could bedesirable to complete half of theproject in order to expedite thedate of production, and there-after to deepen the shafts as asecondary operation while pro-duction continues. This aspect isoften cited as one where the in-clined shaft has an advantageover the vertical shaft. In such acase, the comparison shown inTable VI results.

In this case it is clear that thevertical shaft could be sunk andthe reef horizon reached in ap-proximately half the period re-quired for the inclined shaftduring the first stage. The in-creased amount of developmentis accentuated in the second

:2 55~Q:(!)

~

:>. 45Cl0ffi~~ 35<:0;::

~<J 25~

75

65

GRAPH 1!I.

SHOWINGRELATION BETWEEN HORIZONTALDEVELOPMENT REQUIRED 10 REACH THE

OREBODY - INCUNED SHAFT VERSUS

FOOTWALL VERTJCAL SHAFT

15

1000 .4000 7000 10000 13000 16000 19000

HORIZONTAL TUNNEL LENGTH-ME TRES

TABLE IVComparison of horizontal tunnel lengths (adjusted for inclined shaft length) for

inclined shaft versus vertical shaft

Additional length Value of thisof inclined shaft additional length

over that of of shaft ex-vertical shaft pressed as de-

velopmentmetres

Inclinationof orebody

Netadditional

developmentfor vertical

shaftsmetres

Additionalhorizontal

development

degrees metres metres

TABLE VConparison of lead times, skip size, and winders

OPERATIONElapsed time, months

1.2.3.4.5.6.7.

Prepare to sinkSinking timeEquipping . .Development from stations.Further development to orepassesOrepasses by raiseborerDevelopment

TOTAL:

Size of skips. .Horsepower of winder

MAY 197~ ~1~JOURNAL OF THE SOUTH AFRICAN INSTITlJTE; QF MINING AND METALLURGY

Stage of Inclined Footwallproject ITEM shaft vertical

shaftmetres metres

First Length of shaft 854 549

Length of horizontal development 854 1738

Second Length of shaft 854 549

Length of horizontal development 854 3750

... ESTIMATED COMPLETIONTIME

Elapsed time, months

Inclinerl Footwallshaft vertical shaft

3,0 6,0

38,8 8,0

0,0 1,0

2,0 2,0

1,5 0,5

3,0 0,4 con-current

2,0 6,0

50,3 23,9

eqmremen - - - - - -20 35 45 60 75 90

- - - - -Hoisting distance, metres 3029 1806 1465 1196 1073 1036

Persons per carriage 180 120 100 100 100 80

Capacity of skip, tonnes 25,5 15 12,5 10 9,75 9,5

Rope diameter, millimetres 47 47 47 47 47 46

R.M.S. horsepower of winder 3215 2500 2350 2160 2088 2000

TABLE VIComparison of completion times of shafts

Operation first stage

1. Prepare to sink

2.

3.

Sinking

Equipping

4.

5.

Development on stations

Development for orepasses

6. Orepasses .

7. Development to reef

TOTAL

stage. There is no great dif-ference in the problem of deep-ening vertical shafts as opposedto inclined shafts.

(d) For comparative outputs thehorsepower demands of thewinders required for the twotypes of shaft favour the ver-tical shaft. Design and opera-tional difficulties are encount-ered on the steeper ranges ofinclinations between 35 and75 degrees.

Table VII indicates the com-parison arrived at for shafts handling75000 tonnes per month, togetherwith the men and material require-ments for that rate of production.

With due consideration to allthese factors, the general conclusionreached is that, as a major pro-duction unit, the vertical shaft issuperior to the inclined shaft ofcomparable capacity under all cir.cumstances.

SHAPE OF SHAFTThe recognized shape of the exca-

vation for vertical shafts can beany of the following:(a) rectangular, narrow, wide or

square;

314 MAY 1973

(b) circular;(c) elliptical (or quasi-elliptical, i.e.

distended circular).Inclined shafts are excavated to

the following shapes:(a) rectangular with or without

arched roof;(b) elliptical (at great depth).

An analysis of the vertical shaftsthat were sunk or were being sunkover the period January 1961 toDecember 1971 is given in TableVIII.

For the purpose of comparison,Table IX was compiled from infor-mation supplied by Jamieson et aJ.2

The increased use of the circularand elliptical shapes is due to

development of mechanical cleaningin the first instance and, finally, tothe development of the principle ofconcurrent lining whilst sinking pro-ceeds. The circular shape is alsothe most efficient from the ventila-tion aspect. Great credit is due tothose who, through their tenacityof purpose, painstakingly developedthe methods to make possible theresults at present being achieved invertical-shaft sinking operations.

It is clear, therefore, that duringthe past decade the rectangularshape was used only for shafts withan area ofless than 30 square metres.For larger shafts, the circular orelliptical shapes were favoured.

The elliptical or distended shape isreturning to favour because it hasvirtually all the advantages of thecircular shape but provides for abetter utilization of space and,when required, a lesser length ofbrattice wall section. In some in-stances, therefore, the elliptical shapecould be preferred to the circular.

SIZE OF SHAFT

In the case of mines, the size ofshaft used is generally determinedby the volume of air required toventilate the prospective mine. Onlyin the case of small shafts is the sizedetermined by the equipment to befitted into it and/or handled throughit. On the other hand, in the case ofaccess to underground works of acivil nature, the size of the shaftsgenerally is determined by the sizeof the equipment to be handledthrough them.

Since, at the time the shaft orshafts for a new mine are being de-signed, the general layout of theworkings is largely one of conjecture,the volume of air is based on theestimated quantity of rock to bebroken in the mine.

TABLE VIIComparison of hoisting details

Inclination of orebody, degreesR t


Area of shaft in square metresType and function of shaft

Medium LargeVery small Smallup to 20 20 to 35 35 to 50 over 50 Total

(a) RECTANGULAR SHAFTSProduction 17 2 NIL NIL 19Service 9 NIL NIL NIL 9Coal service 2 NIL NIL NIL 2

TOTAL RECTANGULAR 28 2 NIL NIL 30

(b) CIRCULARProduction 12 5 22 8 47Service 10 6 8 3 27Sub-production 3 2 18 3 26Sub-service 12 3 NIL I 16Coal service 25 15 5 NIL 45

TOTAL CIRCULAR 62 31 53 15 161

(c) ELLIPTICALSub-production 2 2 I I 6Sub-service 5 NIL NIL I 6Coal service I NIL NIL NIL ISub-shafts production NIL NIL NIL 2 2

TOTAL ELLIPTICAL 8 2 I 4 15

GRAND TOTAL 98 35 54 19 206

Percentage 47,6 17,0 26,2 9,2 100,0

Percentage of each type

Rectangular Circular Elliptical Total

Very small 28,57 63,27 8,16 100Small 5,71 88,58 5,71 100Medium Nil 98,15 1,85 100Large Nil 78,95 21,05 100

All shapes, number 30 161 15 206Percentage 14,56 78,16 7,2 100%

Type of ShaftPeriod Totals

Rectangular Circular Elliptical

1910-1947Number 341 41 7 389Percentage 87,7 10,5 1,8 100



TABLE VIIIVertical shafts sunk 1961-1971

(based on information kindly supplied by the Government Engineer)

The figures of interest in the 1970report are as follows.(i) The quantity of air provided

per minute per tonne, brokeninto:

Average volume per mine =0,162 cubic metres

Maximum = 0,40 cubic metresMinimum = 0,052 cubic metres

(ii) The quantity of air providedunderground averages 5,094cubic metres per minute perperson underground.

From the results of the mineswhere the average virgin rocktemperature is below 37,7°Cand where ventilation conditionsare known to be reasonablygood, the average figure for thequantity of air per minute pertonne broken per month is0,15 cubic metres.

An average of selected valuesfor mines where the virgin rocktemperature is over 37,7°Cshows that a figure of 0,2cubic metres per minute pertonne broken is a more reason-able requirement.

The size of the shaft can be cal-culated from these two results,coupled with the knowledge that forcomfort the velocity in the downcastshaft should be 500 metres perminute and not exceed 600 metresper minute. An allowance of 15 percent is made for the obstructioncaused by the shaft steelwork andother fixed equipment.

perforce to allow for the best possible As stated previously, the velocitysolution having regard to the infor- of the return air in the up cast shaftmation available from other mines. is generally limited to not more thanFortunately, the Chamber of Mines 1200 metres per minute to ensureof South Africa provides, through its good fan efficiency in the shaft.Research Department, a wealth of The following calculations de.information relating to this subject termine the size of circular verticalin its Annual Ventilation Reports. shafts required for an output of

TABLE IXTypes of shafts sunk 1910-1971

SUMMARY

This state of affairs is no re-flection on the skill of the geologistin interpolating the possible strikeand dip of the deposit, nor the fault-ing, but is purely due to the factthat the borehole and reef inter-sections normally available to thesespecialists are not sufficient topermit even a reasonably accurateforecast. Because of this factor, theventilation engineer cannot with anydegree of accuracy calculate thevolume of air required for theprospective mine.

Further, it has been establishedthat the velocity of the air currentin downcast shafts is generallylimited to a figure of 500.600 metresper minute, whereas in the upcastshaft the limit approaches 1200metres per minute.

The mining engineer in designingthe size of the shafts has, therefore,

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY MAY 1973 315

(a3) 600 (a4) 500

5,98 (19,5) 6,34 (20,75)6,12 (20,0) 6,70 (22,0)7,07 (23,0) 7,74 (25,5)8,66 (28,5) 9,48 (31,0)9,96 (32,75) 10,94 (36,0)

1l,06 (36,0) 12,24 (40,0)12,24 (40,0) 13,40 (44,0)

(a) Downcast ShaftsQuantity, cubic metresper minute

(i) Area required with anair velocity of 600 mper minute

(ii) Area required with anair velocity of 500 mper minute

(iii) Adjustment of theseareas by 15 % for ob-struction gives theshaft areas required

(i) above(ii) above

Diameter of shaft(i) above

(ii) above

(b) Upcast ShaftsShaft area required

Diameter of shaft

Using a factor of 0,15cubic metres per minuteper tonne mined per

month

Using a factor of 0,20cubic metres per minuteper tonne mined per

month

67 OOO~ 0,15 = 10,050 67 000~0,20=13,400

10,050/600 = 16,75 m' 13,400/600 = 22,33 m'

10,500/500=20,10 m' 13,400/500 = 26,80 m'

19,70 m'23,64 m'

5,00~('=i6:4ft)I5,50 m (= 18,0 ft)

I10 050/1200=8,375 m' ,

I

26,2731,53

5,78 m (=19,0 ft)6,34 m (=20,8 ft)

13400/1 200=1l,167 m'

=3,76m(=12,3ft)=3,27 m (=10,7 ft)

TABLE XDiameter of downcast shafts, metres

Tonnesplanned

to bemined

Virgin rock temperatures

-37,8°CVelocity of air current

metres per minute

+37,8°CVelocity of air current

metres per minute----

(al)* 600

67 00075000

lOO 000150 000200000250000300000

5,00 (16,5)t5,30 (17,5)6,06 (20,0)7,50 (24,5)8,66 (28,5)9,67 (31,75)

10,60 (34,75)

---(a2) 500

5,48 (18,0)5,80 (19,0)6,70 (22,0)8,21 (27,0)9,57 (31,5)

10,60 (34,75)1l,61 (38,0)

*(al), (a2), (a3) and (a4) refer to curves on Graph IV

t Figures in brackets denote nearest convenient conversion to feet.

TABLE XIDiameter of upcast shafts, metres

Tonnesplanned

to bemined

Virgin rock temperatures

+37,7°C500 M (b2)

-37°C600 M (bl)*

67 00075000

100 000150000200000250 000300000

3,273,453,994,905,646,306,90

(ll,O)t(1l,5)(13,0)(16,0)(18,5)(20,5)(22,5)

3,763,994,605,646,547,287,98

(12,5)(13,0)(15,0)(18,5)(21,5)(24,0)(26,0)

* (bl) and (b2) refer to curves on Graph IV

t Figures in brackets denote nearest convenient conversion to feet.

316 MAY1973

67 000 tonnes broken per month.From similar calculations, Table

X and Graph IV have been com-piled, from which it is easy to de-termine the range of diameters of theshafts that would be required forplanned tonnages to be mined from67 000 up to 300 000 tonnes permonth.

Because of the large capital outlayrequired for shafts, it is conceivablethat shafts of larger diameter thanthose extremes indicated here couldwell be sunk in the future, particu-larly when the large base-metalmines that are now open-cast haveto mine underground in depth.

In a new mine it is generallyaccepted practice to sink twin verti-cal circular shafts in order to pro-vide for the second outlet, as re-quired by law, as soon as possible,and also to arrange for adequateventilation from the inception ofmining operations.

Where an additional shaft is re-quired for the expansion of pro-duction or for the mining of thedeeper levels, or where a new minecould establish a second outletthrough a neighbouring mine, thebratticed shaft provides a moreeconomical answer under certainconditions. In such a case the twoareas required for downcast and up-cast ventilation are calculated asbefore and, allowing for the areacovered by the brattice wall, the sumof the total area required is derivedand the overall diameter calculated.

Examples of such dual purposeshafts are:

Vaal Reefs South Bratticed Section-Two circles 8,53 metres indiameter, with centres spaced 0,6metre apart

Elsburg Gold Mining Company Lim-ited-Circular, 10,21 metres indiameter

President Steyn Number 4 Shaft-Two circles 10,21 metres in dia-meter and a straight section0,76 metre long joining these.Although these large shafts were

sunk through igneous and sedi-mentary rocks, as well as heavywater-bearing strata, no particulardifficulties were encountered. In thecase of another large downcast shaftsome difficulties arose where amajor steeply inclined fault wasintersected. The stress induced in


I/)

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15 of small sectional area but largecapacity because of their extendeddepth. In this manner shaft sizeshave been kept to a minimum, butthe output has increased signifi-cantly. In one case study, a shaft of7,93 metres diameter is handling anaverage of 227 423 tonnes per monthregularly (with a record month of239000 tonnes), plus all the person-nel and about 90 per cent of thematerial requirements. This shaftarea obviously cannot handle theventilation requirements for thisrate of production, but ventilation isaugmented through another shaft.

As an example of the use of shaftsin civil-engineering projects, theproposed St. Gotthard Railway Tun-nel may be cited.

A preliminary design has beenproposed for three vertical shafts tobe sunk enabling the construction ofthe new Gotthard Railway Tunnelbetween Erstfelt in Switzerland andthe new Biasca station in Italy. Thistunnel will be approximately 46kilometres long, and bored 10 metresin diameter.

The shaft design was based on the

GRAPH 1Y SHOWINGRELATION BETWEEN SHAFT DIAMETERS'

ANDPLANNED TONNAGE TOBE MILLEt:)

13

11

9

7

5

F/GURESIN( ) RELATE TO TABLE r

100 ]50 200 250 300

PLANNED TONNE TOBE MINED MONTHLY

the rocks by the fault, together withthe slickensiding, caused seriousoverbreak, but the shaft was com-pleted successfully.

The high cost of shafts calls for aminimum number per mine. Withsuch large-diameter shafts passingcorrespondingly large quantities ofair for ventilation purposes, theareas on strike and dip served bysuch shafts are considerably largerthan was thought possible a decadeago. In order to convey the volumeof air to the workings, twin, or eventreble, tunnels are necessary attimes. Further, the use of refrigera-tion enables the re-use of air, andin this manner the area served byshafts is capable of a further ex-tension or, conversely, the totalquantity can be reduced and therebythe size of shaft. This latter al-ternative holds particularly in deep-level mines where the air has to berefrigerated, in any event, sooner orlater, because of the rapid transferof heat from rock to air in its passagethrough the workings at high virgin-rock temperatures.

The bottom discharge skip hasmade it possible to fit in conveyances

AGGREGATE &SAND COLUNN

<1 > -l

- ~ --~------- . - .! -----

"I-~-

_..,t"' ~

--- -.

VENTILATION COLUMN

CABLES

Fig. 2-Permanentconfiguration

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY MA Y 1973 317

information supplied. The control-ling factors in the design were theconsiderable tonnages of rock pro-duced by the two tunnel-boringmachines in each shaft, which haveto be hoisted daily, and the loweringand raising of the largest componentof the tunnel-boring machines, whichis the bearing. This item is 5 metresin diameter, 3 metres wide, andweighs 30 tonnes. In addition, thelowering of the daily supplies for theconstruction of the tunnel, con-sisting of heavy precast-concretetunnel lining and draining seg-ments, as well as rails, sleepers,pipes, machine spares, and thelabour force, is to be catered for.

A service cage is provided topermit maintenance of temporaryelectrical cables, ventilation, ag-gregate, water, and air columns.Finally, on completion of the works,the shafts will be stripped and usedfor ventilation purposes and powersupply. The service cage will beretained for maintenance of thepower cables.

It was also necessary to allow forthe extremely low site temperaturesin winter, which could reach -30°C.

The proposed shaft configurationduring the tunnel-constructionperiod is shown in Fig. 2.

At the tunnel elevation, the rockwill be delivered from either sideof the shaft by means of a conveyorand delivered into a loading box;from this box the rock is to be dis-charged into two measuring flasksand hoisted direct to the surface.A suitable spillage arrangement isalso to be provided. (See Figs. 2 and3.)

A concrete headgear has beenproposed with tower-mounted Koepewinders to cater for the adverseclimatic conditions anticipated. Theminimum size for this shaft is foundto be 8,5 metres, largely because ofthe size of cage required to lowerthe main bearing of the boringmachine and because of the Koepewinders.

Should it be possible to revert tonormal double-drum winding withthe possibility of slinging the bearingunderneath the cage, the shaftdiameter could be reduced to 7metres, and this, because of thesaving in shaft space, is what mayfinally be done.

318 MAY 1973

T/NEL

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TUNI£L,

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FLASKS

LLAGE CHUTE:

SUMP

IPROPOSED SHAFT FOR Gr1(THARD RAlLItl4Y TUNNEL '/DlAGRliHNATfCI

FIG,3


QC.NorOR

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IN LINE WINDER

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DRIVERSPLATFORN0

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FIG. 4


THE DEPTH OF SHAFT

For many years the economicdepth for hoisting has been ac-cepted as about 1600 metres. Fromthis point in depth, a sub-shaft wasnecessary to reach the next stage ofsimilar depth, and finally even atertiary shaft to mine to the limitin depth - at present estimated atsome 3650 metres. This systemnecessitated the cutting of largeunderground hoist chambers, roperaises, and waste and ore transfers,which was both very expensive andtime-consuming. As the demand forthe hoisting of larger tonnages fromgreater depths increased, the double-drum winder with its single ropebecame uneconomic and it wasnecessary to provide a windingsystem using more than one rope.

At first the Koepe winder wasconsidered a solution to the prob-lem, mainly because it was the onlyknown method of operating a hoist-ing system with multi-ropes tohoist heavy pay loads. This systemof hoisting has operated success-fully but has certain disadvantages,such as the following.

(i) In a Koepe winder the stresspattern due to rope weight isreversed every winding cycle,and, with increased depth andrope weight, the rope life isreduced accordingly.

(ii) The installation of new or thechanging of old ropes is aproblem and requires an ad-ditionallarge winch.

(iii) An adjustment has to be madeat capel ends to compensate forrope stretch.

(iv) The cage must be made suffi-ciently large to cater for all themachinery and equipment to belowered inside it because, owingto the balance ropes, it is vir-tually impossible for anythingto be slung below the cage.

(v) Winding should take place fromone loading point only.

(vi) The shaft has to be deeper toprovide for the balance ropesand sheaves, if necessary, andthe added cost of the sophistica-ted spillage arrangements.

Finally, the Blair twin-rope, drum-type winding system was developedas a solution to the problem of

MAY 1973 319

Q

'<I:0-.JQ

.~ 200%lJ .

.~....'<I:lu(!)

~~lJ

~

400%

300%

100% '-

1000

GRAPH Y

RELATIONSHIP BETWEEN

HOISTING DEPTH ANDTYPE OF WINDER

2000 3000

SHAFT DEPTH - METRES

4000

winding from great depth. Theattachment of two ropes to eachconveyance means that the dia-meter of the ropes can be reduced,and, therefore, the diameter of thewinder drums and sheaves. Con-siderable development has been car-ried out on this winder, and thereare three variations in basic layout.

The In-Line Winder is the simplestand cheapest, but the relativelylarge spacing between the two setsof ropes can present design diffi-culties with fleeting angles whenthe winder is being positioned.

The Geared Winder does not pre-sent any positional problems. How-ever, because the combination of theout-of- balance loads from bothdrums has to be transmitted throughthe gear drive, a gear design prob-lem is created. Because generallyonly one clutch is provided, single-drum winding is not practicable inall cases.

320 MAY 1973

The Gearless Winder, althoughmore expensive, has no positionalproblems and requires no compli-cated gear train; there is no mech-anical coupling of the two drumassemblies, and the out-of-balanceload is transmitted electrically; de-clutching is simple and is performedelectrically. An additional advantageof this scheme is that a failure onone drum assembly will not preventsingle-drum hoisting to take placewith a reduced tonnage output. Asproposed by TindalP, the largedirect-coupled, direct-current motorsare more reliable than comparablehigh-speed alternating-currentmotors fitted to a gear train. (SeeFig. 4.)

The regulations of the Mines andWorks Act dictate the load to beattached to the winding ropes atdifferent depths and consequentlythe winding system to be used. Therope life and tread wear on a Koepe

winder operating at a depth below1830 metres become serious con-siderations.

A theoretical comparison betweena double-drum winder with a singlerope, a Koepe winder using a singleand multiple ropes, and a Blairtwin-rope drum winder based on thepresent-day regulations is shown inGraph V. The indications are thatthe most suitable winder for anydepth below 2094 metres is theBlair twin-rope drum winder. Thiswinder has proved itself a mostsuitable installation for hoistinglarge tonnages from deep shafts.

SHAFT LININGS

In South Africa unreinforced-concrete linings of from 0,23-0,30metre in thickness are generallyaccepted as sufficiently strong forvirtually all rock formations. Incertain cases where the rock for-mations are sufficiently strong, onlyconcrete rings of 1 metre depth areused at, say, 15 feet intervals tosupport the steelwork as well as theshaft walls. Where, over short dis-tances, the rock walls are suspect,the full lining is placed and there-after the spaced rings are revertedto.

Under certain conditions, how-ever, such as where salt water hasto be penetrated, or where the shaftwalls are very weak, different typesof lining are required. As an exampleof this method the case of theCleveland Potash Mine in NorthYorkshire, United Kingdom, maybe cited.

Two shafts are currently beingsunk for Cleveland Potash Limitedby the Mines Construction Con-sortium. These shafts, known as therock and man shafts, are 91,5 metresapart and will be sunk to a finaldepth of 1133 metres, with afinished lined diameter of 5,5 metres.Between 633 metres and 913 metres,one of the major aquafiers in GreatBritain, known as the Bunter Sand-stone, with its saturated brinesolution, representing a formidableobstacle to shaft sinking, is to bepenetrated.

Conventional methods were usedfor the sinking of both shafts downto the Bunter Sandstone. The rockshaft is being sunk through theBunter Sandstone inside a frozen


Photo A-Freezechamber showing part of brine ring intake and return pipes(insulated) and some individual freeze pipes with ice formation.

ice wall with a temporary concretelining and will be permanently linedwith a double steel welded lining re-inforced with high quality concrete.The steel-plate used for the shellsof the lining varies in thickness from16 to 48 mm to cater for the varyinghydrostatic pressure. (See Photo-graph A, which depicts the freezechamber that was constructed at adepth of 585 metres.)

The double steel lining will beinstalled in the shaft, on a concretefoundation, from a specially con-structed stage equipped with auto-matic welding machines.

The man shaft is being sunkthrough the Bunter Sandstone andlined with cast-iron tubbing of

varying thickness to cater for thehydraulic head. Two different gradesof cast iron were required, and be-hind these is a back-fill to the shaftwalls of high-quality concrete. Final.ly, cement back-grouting is appliedbetween the tubbing, concrete, andshaft walls to seal off the remainingwater. The groundwater is con-trolled by means of advanced andsophisticated methods of groutingtechniques with chemicals and/orcement, which are required to meetthe combination of high pressures ofthe brine solution and the low per-meability of the Bunter Sandstone.(See Photograph B depicting the in-stalled tubbing rings.)

Under certain conditions where


soft water-bearing strata have to bepenetrated and where ground move-ments are likely to occur whenmining takes place, it has beenfound necessary to use a double steel-welded lining similar to that des-cribed previously and reinforcedwith the necessary thickness of high.quality concrete between the twoshells. In addition to this, a liningof bitumen 0,13-0,15 metre in thick-ness is placed between the shaftwalls and the outer steel lining. Inthis manner the ground movementmay deform this softer lining beforebringing full pressure to bear on thedouble steel-welded concrete-reinforced lining4.

DEVELOPMENT IN THEUTILIZATION OF LASHING

GEAR

The lashing gear for the previouslymentioned Cleveland Potash Shaftshad to be designed to fit onto thebottom deck of the stage of the5,45-metre diameter shaft in whichtwo 5,4 tonne kibbles 1,52 metresin diameter also operated; this left1,25 metres clearance in which tofit a 20 h.p., 4,5 tonne capacityhoisting unit. The regulations inEngland also demanded that thehoisting unit itself is self-sustainingwith its full load, independent of thebraking system.

To comply with the above require-ments, it was necessary to design anew lashing gear.(a) The main driving motor was

mounted vertically, driving ahigh-ratio worm gearbox on endand then through a train ofgears driving the winch drum.

(b) The radial boom of the unit wasmade extensible, allowing thehoisting trolley to run out toany position selected for theparticular shaft diameter beingcleared. During construction,the excavated diameter of theshafts varied from 5,45 to 7,6metres. The boom is moved inand out by twin hydrauliccylinders, and the action of thedriver in returning his boom-extension lever to neutral auto-matically locks the boom in anyof the desired positions.

(c) The grab unit was also designedto be used in the installation ofthe individual segments of cast-

MA Y 1973 321

TABLE XII Comparison of bunton sections

Unit cost ApproximateType of bunton section percentage shaft

resistance

I 6" Beam 100 100

1 6" Mushroom I beam 120 64

fj) 6" Covered I beam 150 45

~6"AerofoiJ I beam 200 42

0 6" Wide flattened pipe section 130 45

0 6" Prismatic section 125 43

Q 6" Aerofoil section +350 40

0 4" Prismatic section 110 28

Q 4" Aerofoil section 300 25

Photo B-Tubbing installation showing "tubbing platform" in foreground.

iron tubbing, each weighingapproximately 6,25 tonnes. Forthis purpose it was necessaryto have a more sensitive controlthan that required for normalshaft-lashing duties. In orderto achieve this the followingmodifications were carried out.

The speed of the hoistingrope was reduced and con-trolled by adjusting the gov-ernor of the air motor drivingthe winch. A foot-operatedpedal brake was installed inthe driver's cab, the brakeacting on the first motionshaft of the worm gearbox.

A complete new air-volumecontrol valve was designed.This valve comprises threebalanced-spool valves opera-ted from a single controllever; the large-diametervalve controls the main sup-ply of air to the hoist motor,which is linked to the driver'shand lever, and movement ofthe hand lever directly con-trols the volume of air beingsupplied to the motor andconsequently its speed; also

coupled to the hand lever arethe two smaller auxiliaryvalves; one of these valvessupplies pilot air to the re-versing cylinder on the hoist-ing motor and the other tothe main winch brake cylin-der. The segments of cast-iron tubbing are lowereddown the shaft suspendedfrom the kibble rope. Theseare then transferred to thehoisting rope of the lashinggear and then finally posi-tioned by means of the hy-draulically controlled boom.(See Fig. 5.)

Extreme care must be ex-ercised in placing the tubbingso that the lead sealing gas-kets between adjoining sect-ions of tubbing are notdamaged.

SHAFT STEELWORK

Much work has been done tostreamline the shaft steelwork sothat the resistance to the airflow willbe reduced. The flattened pipesection, 15 cm wide and spaced at4, 6 or 8 metre intervals, is finding

322 MAY 1973 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

SINKING STAGE

I

i

J

J

J

J

J

j

j

LASHING GEAR

Fig. 5- Typical section through shaft

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY MA Y 1973 323

much favour at present.Table XII, extracted from a

paper by Van Wyks, shows theeffect of various sections of shaftsteelwork on resistance and alsothe related unit cost percentage,

CONCLUSION

It is not possible to deal with anybut the most important aspects ofshaft design within the scope of onepaper without making it too lengthy.The authors realize that the aspectsof fan-drift openings, ore-loadingfacilities, shaft spillage, and power,air, and water supplies, and variousother matters have not been dealtwith in this paper.

However, by utilization of theprinciples enumerated here, it ispossible to design tailor-made shaftsof minimum size, yet capable ofsupplying the ventilation require-ments, having the desired output,and handling the labour and ma-terials at a minimum capital outlay.

ACKNOWLEDGEMENTSThe authors wish to convey their

appreciation to those South African

mining and mechanical engineerswho, through their determinationand ingenuity, have contributed somuch to the development of im-proved shaft design during the pastthree decades. They are also gratefulto the Executive Committee ofShaft Sinkers (Proprietary) Limitedand Mining and Engineering Tech-nical Services (Proprietary) Limitedfor permission to publish this paper.

REFERENCES1. MULLINS, A. R. and HAGGlE, 1. S.

Winding rope problems in South Africa.Trans. 7th Commonwealth Min. Metall.Cong., Volume 111 (1961), 1235-6.

2. JAMIESON, D. M., PEARSE, M. P. andPLUMSTEAD,E. R. A. The evolution ofshaft design and sinking technique inSouth Africa. Trans. 7th Common-wealth Min. Metall. Cong., Volume 11(1961), 591.

3. TINDALL, R. B. L. Some interestingSouth African developments in thedesign and practice of mine winders.S.Afr. Instn. Meeh. Engrs., July, 1968.

4. WEEHUlZEN, J. M. New shafts for theDutch State Mines. Trans. Instn. Min.Engrs. Symposium on Shaft Sinking andTunnelling (1959).

5. VAN WYK, C. F. B. A review of pro-gress in the design of shaft equipmentaimed at a reduction in shaft resistance.Trans. S.Afr. Inst. Min. Metall., S.Afr.Instn. Meeh. Engrs., Mine Ventilation

Soc. S.Afr.-Symposium on mine shaJ1design and its effect on air flow, (Nov.1963).

AUTHORS' REPLY TO QUES-TIONS BY Dr. J. T. Mc INTYRE

Maintenance costs for inclinm~shafts are about 11 cents per tonnehoisted, as opposed to about 5 centsper tonne hoisted for vertical shafts,Both costs apply to concrete-linedshafts with steel furnishings.

Graph V indicates the types ofwinders suitable for hoisting dutiesat various depths of shafts. It isclear that hoisting should be donefrom the maximum depth in asingle lift, thereby avoiding the ad-ditional excavations required forsub-shafts, which consist of largerwinder chambers, headgears, sta-tions, access ways, and workshops,with the support steelwork andconcrete, at a cost of between twoand three million rand. Hoistingfrom greater depths depends on theavailability of engineering designand manufacturing facilities forlarge-diameter ropes and hoist drumsable to hoist at higher windingspeeds.

THE SOUTH AFRICAN CHEMICAL INSTITUTEDIE SUID-AFRIKAANSE CHEMIESE INSTITUUT

PRETORIA BRANCH

The Organization of Science

by

PRETORIA- T AK

The Organization of Science

PROFESSOR SIR DEREK BARTON, F.R.S. PROFESSOR SIR DEREK BARTON, F.R.S.

deur

CHAIRMAN: Dr S. M. Naude, the Scientific Adviserto the Prime Minister.

Venue: Van Der Bijl Hall, Chancellor's Building,University of Pretoria.

VOORSITTER: Dr S. M. Naude, die WetenskaplikeRaadgewer van die Eerste Minister.

PLEK: Van Der Bijl-Saal, Kanseliersgebou, Univer-siteit van Pretoria.DATUM: Woensdag, 18 Julie 1973 om 20 h 00.

Sir Derek Barton, die Nobel-pryswenner vir Chemiein 1969, besoek die Republiek op uitnodiging van dieSuid-Afrikaanse Chemiese Instituut. Hy is die Presidentvan The Chemical Society en het reeds in die Councilfor Scientific Policy van die Verenigde Koninkrykgedien. Sir Derek Barton is dus by uitstek bevoeg ommet gesag oor wetenskaplike beleid en organisasie tepraat.

DATE: Wednesday, 18th July, 1973 at 20 h 00.

Sir Derek Barton, the Nobel Laureate for Chemistryin 1969, is visiting the Republic at the invitation ofthe South African Chemical Institute. As President ofthe Chemical Society and having served on the Councilfor Scientific Policy of the United Kingdom, he is out-standingly qualified to speak on matters of scientificpolicy and organization.

324 MAY 1973 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

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