J. S. Atr. Inst. Min. Metal/., vol. 86, no. 9.Sep. 1986. pp. 377-392.

(Presidential Address) by H. WAGNER*

The challenge of deep-level miningin South Africa

SYNOPSISThe discovery of the gold-rich Main Reef Group of reefs on the farm Langlaagte in 1886 marked the opening ofthe richest and most extensive goldfield in history. Mining of the narrow reefs progressed from the outcrops tomore than 3,5 km, and has made South Africa the foremost mining country in the world.

Changes in the political and socio-economic climate create a new challenge to the gold-mining industry. Themost significant of these is the emergence of Black trade unions, with their demands for higher wages, improvedsafety, job advancement, and abolition of discriminatory legislation. Industrial conflicts on gold mines have risensignificantly in the past ten years, and are likely to continue in the future, although the causes of these conflictsmay change. Events largely outside the control of the gold-mining industry, such as the improved dollar price forgold and the depreciation of the value of the rand relative to major currencies, have enabled the industry to meetthe demands for higher wages and to narrow the wage gap. However, labour productivities have improved insignificant-ly and are a cause of major concern for the future development of the industry.

Continued pressure in the industrial-relations area, the inflation of working costs, and the extension of miningoperations to greater depths and more difficult areas create major challenges to mine managements and miningengineers. Significant improvements in mining technology, environmental control, and safety will have to be madeto ensure the long-term survival of the industry. The unavoidable introduction in deep gold mines of mechanizationon a larger scale to meet the requirements of higher labour productivities and a better and safer underground environ-ment will have a major impact on the cost and management structure of these mines.

Engineering will assum& a more important role on deep gold mil1es, and management styles and structures willhave to be adapted to accommodate these changes. The supply of suitably qualified engineers, technicians, andartisans will be a crucial factor controlling the rate of technological change.

The industry is well-geared through its Group system to meet these challenges, and to benefit from the experiencegained in the operation of highly mechanized mines. However, changes take time to implement and there is verylittle time left.

SAMEV ATTINGtDie ontdekking van die goudryke Hoofrifgroep riwwe op die plaas Langlaagte in 1886 het die ontsluiting van dierykste en omvangrykste goudveld in die geskiedenis ingelui. Die ontginning van die smal riwwe het gevorder vandie dagsome tot meer as 3,5 km en het Suid-Afrika die belangrikste mynbouland in die w&reld gemaak.

Veranderinge in die politieke en sosiaal-ekonomiese klimaat het 'n nuwe uitdaging vir die goudmynbedryf geskep.Die belangrikste van hierdie veranderinge is die opkoms van Swart vakunies met hul eise om hoer lone, groterveiligheid, vordering in die werk, en die,afskaffing van diskriminerende wetgewing. Industriele botsings by die goud-myne het die afgelope tien jaar beduidend toegeneem en sal waarskynlik in die toekoms voortduur, hoewel dieoorsake van hierdie botsings moontlik kan verander. Gebeurtenisse wat grotendeels buite die beheer van die goud-mynbedryf is, seos die hoer dollarprys vir goud en die daling in die waarde van die rand teenoor die vernaamstegeldeenhede, het die bedryf in staat gestel om aan die eise om hoer lone te voldoen en die loongaping te vernou.Daar was egter 'n onbeduidende verbetering in arbeidsproduktiwiteit wat groot kommer wek oor die toekomstigeontwikkeling van die bedryf.

Voortgesette druk op die gebied van arbeidsverhoudinge, die inflasie van bedryfskoste en die uitbreiding vanmynbedrywighede na groter dieptes en moeiliker gebiede, skep 'n ernstige uitdaging vir mynbesture en mynbou-ingenieurs. Daar sal groot verbeterings in mynboutegnologie, omgewingsbeheer en veiligheid aangebring moetword om te verseker dat die bedryf op die lange duur oorleef. Die onvermydelike invoering van grootskaalsemeganisasie in diep goudmyne om aan die vereistes vir hoer arbeidsproduktiwiteit en 'n beter en veiliger ondergrondseomgewing te voldoen, sal 'n belangrike uitwerking op die koste- en bestuurstruktuur van hierdie myne h&.

Ingenieurswese sal 'n belangriker rol in diep goudmyne speel en bestuurstyle en -strukture sal aangepas moatword om hierdie veranderinge te akkommodeer. Die voorsiening van behoorlike gekwalifiseerdeingenieurs,tegnicien vakmanne sal 'n deurslaggewende faktor wees wat die tempo van tegnologiese verandering sal bepaal.

Die bedryf is deur sy groepstelsel goad daarop ingestel om hierdie uitdagings die hoof te bled en te baat bydie ondervinding wat opgedoen is deur die bedryf van hoogs gemeganiseerde myna. Dit neem egter tyd om veran-deringe te implementeer, en ons het bitter min tyd.

. Director General, Research Organization, Chamber of Mines of

South Africa, p.~. Box 91230, Auckland Park, 2006 Transvaal.t Die volledige presidentsrede is in Afrikaans beskikbaar. Afskrifte

is op aanvraag verkrygbaar by die Sekretaresse, SAIMM, Posbus'61019, Marshalltown, 2107 Transvaal.

@ The South African Institute for Mining and Metallurgy, 1986. SAISSN oo38-223X/$3.00 + 0.00. Address presented 20th August,1986.

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 377

IntroductionThe discovery of the gold-rich Main Reef Group of

reefs on the farm Langlaagte in 1886 marked the birthof what was to become the richest and most extensivegoldfield in history. This discovery proved to be of greateconomic and political significance not only for the regionbut for Southern Africa as a whole.

As a mining engineer who is closely concerned withgold mining, I could not resist the temptation of takingthe centenary of the proclamation of the Witwatersrandgoldfields as the base on which to build my PresidentialAddress. However, I have resisted the temptation ofgiving a historic overview of the development of miningon the Witwatersrand. Furthermore, I have resisted thetemptation of forecasting the future economic role of goldmining. Too often have such forecasts been provedwrong. Instead, I shall attempt to address certain aspectsof the gold-mining industry that, in my opinion, arecrucial for the future well-being of the industry and thecountry as a whole. In doing this, I shall confine myself,as far as possible, to areas in which I consider myself tobe knowledgeable. Also, wherever appropriate, I shalldraw from the wealth of experience that has accumulatedover the past one-hundred years.

Traditionally, the President-elect is permitted to lookinto the future and speculate with a certain amount ofimpunity. In this respect, I propose to join the ranks ofmy distinguished predecessors. I hope that, in doing so,I shall provoke some debate with regard to the future ofour mines and in this way make a positive contribution.There is no doubt in my mind that not all my ideas andthoughts will enjoy general acceptance.

Gold Mining in a Changing Political and Socio-economicClimate

South Africa, unlike many other countries, has enjoyeda relatively stable political and economic climate since theAnglo-Boer war. As a result of this, the economy of thecountry expanded at an average rate of about 5 per centper annum!. This steady growth in economy, togetherwith virtually no inflation, is reflected in Fig. 1, which,for the period 1902 to 1985, shows the tons of ore treatedby South African gold mines, the average working costsper ton of ore treated, and the rand value per kilogramof fine gold. Several important observations can be made.Firstly, the tons of ore treated have gradually increasedsince the early days of gold mining. Secondly, for a periodof nearly fifty years, 1902-1948, the working costs of goldmines remained virtually unchanged. From 1948 to 1971working costs increased gradually, and from then on in-creased rapidly. Thirdly, since the demonetization of goldin 1971, the working costs have increased rapidly. Recent-ly, the increase in the price of gold in rand terms waslargely due to the drop in the rand-dollar exchange rate.

A close examination of the working costs on gold minessince 1972 shows that these costs have increased at a verymuch faster rate than, for example, the consumer priceindex (CPl). During the period 1972 to 1984, the increasein gold-mine working costs was more than 50 per centhigher than the increase in CPI (Fig. 2). As gold miningis a highly labour-intensive industry, labour being respon-sible for about half of the total working costs, it is verysensitive to wage increases. In the early 1970s the industry

16 000

15000

14000 WW I World War IWW TI World War TIMS Miner's strike

Tons treatedWorking cost AltonA/kg of fine gold

160

150

140

130000

120000

110 ~-"tJQ)

1000;~

90 :;c:0

80 ~c:tU

70 c:.8

60 a:w0

50 0

'"c:40 :>:

030 3:

20

10

'84 '86

13000

12000

11 000

10000

"tJ

"0 9 000

'"Q)

~ 8 000 II

! I! II I,

I! II I

!"I I

i/,.../o_o-;::.:.-;::-..:..JJ---0 0

1900 1910 1920 193019401950196019701980 1990Year

0

'"7 000

-'"a: 6 000

5 000

4 000

3 000

2 000

Fig. 1-Summary of ore production, working costs, and goldprice for South African gold producers since 1900

8

7

6

378 SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

5

4"""""""",' \'"",...

...'"'" C.,

d... onsumer price In ex

3

2

'70 '72 '76 '82'78 '80Year

Fig. 2-lncrease In gold-mine working costs In comparison withthe increase in consumer price index

'74

embarked on a programme of reform to substantially im-prove the conditions of employment of its Black workforce. The results of this policy are shown in Fig. 3.

The cost of Black labour has increased at a rate thatis more than three times higher than that of the labour

20

18Black labour

CO\

16

14

12

10

8 SEIFSA-I~r:r

cost

./'/." \'".4,"'"

,if111"~"" White labour cost,""' .'~,~......

6

4

2

0'70 '72 '78 '80 '82 '84

Year'74 '86'76 '88 '90

Fig. 3-Change In labour costs on the gold mines in comparisonwith that in other Industries (after SEIFSA)

index issued by SEIFSA (Steel Engineering IndustriesFederation of South Africa). However, this exceptionalincrease in the cost of labour was not matched by an in-crease in overall labour productivity. Labour producti-vities increased from 189 t of ore treated per man per yearin 1970 to 222 t in 1984, or by 17,5 per cent.

The exceptional economic performance that the gold-mining industry has achieved since the early 1970s wasmade possible by a tenfold increase in the dollar priceof gold. At the same time, high cost inflation and politicalpressure on South Africa resulted in a very marked de-preciation in the value of the rand, which benefited thegold-mining industry.

The prosperity enjoyed by the industry in recent yearsis, therefore, largely due to external factors, rather thanthe result of improved technical and cost performance.However, continued economic strength can be maintainedonly if the industry frees itself of its almost completedependence on external factors. This can be achieved onlyby a determined and sustained effort to control costs andto improve productivities. A prerequisite for this is stabili-ty in the work situation and industrial peace.

Since the early 1970s, significant changes have takenplace in industrial relations. The most obvious indicatorof these is the increase in industrial conflicts (Fig. 4). Abreakdown of the conflicts into major causes highlightsthe complexity of industrial relations on gold mines (Fig.5). Hostel conditions, which tended to be an importantcause of industrial conflict in the 1970s, have accountedfor relatively few incidents in recent years. Wages andbonuses, social conditions, and solidarity issues havebecome more frequent causes of conflict.

The high incidence in wage-related conflicts followingthe exceptional wage increases in the early 1970s is initial-ly surprising, but can be explained by changes in thedistribution of income among the different sections ofthe work force on the mines. This was aggravated by

°~50 47

~ 40

enuu.5?;;: :u 30Co.

8~- Q) 200",:u.DE::>Z

10

'73 '75 '77 '79Year

'81 '83 '85

Fig. 4-Numbers of industrial conflicts on gold mines per two-year period

raised expectations of continued high increases after aninitial increase of more than 60 per cent in 1973.

The emergence of Black trade unions and the recogni-tion of some of these by industry are without doubt themost significant developments in the gold-mining industryin recent years. While the first few years of union develop-ment were characterized by their struggle for recognitionby the mines and for support by the heterogeneous workforce that exists on mines, it is predicted that this trendwill change and that typical trade union issues will becomemore important.

Already there are certain patterns emerging in industrialrelations, and it is reasonable to assume that questionsconcerning conditions of employment (including wagesand bonuses), job advancement, and safety andenviron-mental conditions on the mines will become major issues.In the longer term, this picture will become more com-plicated by the polarization of different unions repre-senting White and Black members of the industry, andthe increase in politicization of separate unions.

Industry will have to give much attention to thesechanges in industrial relations and to their impact onmanagement and mining practice on the mines.

As a result ofthese changes, the gold-mining industry,to ensure its long-term well-being, will have to intensifyits efforts to improve the productivity per capita, tofurther improve environmental conditions and safety inits mines, and to create opportunities for job advance-ment. In the short term, improvements can be achievedprimarily through better mine management, supervision,and training. However, with the generally competent levelof management already in existence on the mines, thescope for improvement is limited. In the longer term, realimprovement can be brought about only by better miningmethods and new technologies.

In my address I shall deal with these issues in somedetail, and shall attempt to give some direction and toidentify some of the areas that, in my opinion, requireurgent attention. I shall do this under three main head-ings: mining, engineering, and human.

The Mining ChaUengeGold on the Witwatersrand occurs in generally narrow

tabular reefs that extend over many kilometres on strikeand dip. The reefs vary from near-horizontal to near-vertical, but the majority have an angle of dip rangingfrom 10 to 30 degrees. The depth at which these reefs

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 379

5050

40

30

20

10

0

50

~40Q; 30a.

~20

'" ~100 0;;

Q;a.VJ 30Q)

~20

" 10

'"0 0

'0

C 30Q)

~20

~10

0

70

60

50

40

30

20

10

0

'71

Other

Hostel Conditions

13,7

2,6

Conditions of Service

25,727,8

Misunder-standingSocial cond.Solidarity

5,1FoodAccommodationEnvironment

16,4

Underground Conditions

29,S

14,8

Fig. 5-Summary of major underlyingcauses for industrial conflict on gold

mines

4,8

HoistingTreatmentAccidentsSafety

Wages and bonuses

61,9

'73 '77 '79Year

'81'75

are being mined ranges from near-surface to well in ex-cess of 3 km. The average rock-breaking depth has re-mained relatively constant at about 1600 m in recentyears, but will increase in future when many of the low-grade areas on existing gold mines, which were previouslyunpayable, have been extracted (Fig. 6).

The tabular nature of the hard, abrasive gold-bearingreefs, the irregular distribution of gold in the reefs, andthe great depth at which most of the reefs are situatedaffect mining in many ways. Firstly, the geometry of thereef bodies and their depth are very unfavourable fromthe point of view of rock stresses and heat flow. Highstresses occur in the rock ahead of the working faces.These cause extensive rock fracturing, and result in dif-ficult and hazardous mining conditions, and the need forelaborate support measures. The tabular shape of theorebody facilitates heat flow from the rock into theworkings, thereby creating an unfavourable thermalenvironment and the need for extensive mine cooling.Secondly, the restricted mining height in the stopes,together with the hard and abrasive nature of the rock

'83

LevelsDifferentialsBonusAdmin.

'85

that has to be mined, and the hot and humid environmen-tal conditions that exist in stopes, have prevented large-scale mechanization ofstoping operations. Thirdly, thedepth at which the reefs are situated and the irregulardistribution of gold in the reefs make mine planning andgrade control difficult and favour mining methods thathave a high degree of flexibility. Fourthly, a concentra-tion of mining operation is difficult to achieve in tabulardeposits of variable ore grade. Fifthly, transport and com-

.munication lines increase with qepth, resulting in highcost, loss of effective working time, and difficult control.

Against this background it is not surprising that deep-level gold mining uses a relatively low level of mechaniza-tion, a low degree of face utilization, and very labour-intensive methods.

In my opinion, these are the features that have to bechanged if the gold-mining industry is to meet the chal-lenges resulting from the changing socio-economic andpolitical environment. After having said this, I must pointout that there is no doubt in my mind whatsoever that,as far as the mining of deep tabular hard-rock orebodies

380 SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

- ~-----

Fig. 6-Average rock-breakingdepth and virgin rocktemperature (VAT)on SouthAfrican gold mines

:§ 2 000

.r.Q. 1 900ID

"00> 1800

,S

~ 1 700ID~

~ 1 600u0~ 1 500t1JIDE 1 400

39~

<..>

VAT ""'38 ~-_/ "' ID/--,' ~

--" 37 .2/ t1J

/'~

/ 36 ~,/ E

, 35 2/ ~

/ u,.- 34 2

"/"0

~ 1 3000>

~ 1 200'62 '65

is concerned, the South African gold-mining industry isthe leader in the field, and can justifiably look with prideon its achievements. However, there is no time for com-placency, and the industry must make serious attemptsto change the level of its technology. In this regard, I haveto record that the need for significant improvements inmining technology was recognized by leaders in the in-dustry as long ago as 1974, when the industry embarkedon a long-term research-and-development programme.Details of this programme were presented to this Instituteby Professor M.D.G. Salamon in his PresidentialAddress2 in 1976. Progress in most of the areas address-ed by him has been satisfactory, but the changes that havetaken place since then have emphasized the need for theindustry to introduce the developments that have alreadybeen made and to increase its efforts to accelerate pro-gress in the other areas.

ProductivityThe key to many of the problems in deep-level gold

mining is productivity. In this context, I define produc-tivity as the output obtained from a production resource,be it a mine worker, a production machine, or a portionof a working face. Since the various production resourcesare interdependent, it follows that an assessment of pro-ducitivity has to take all factors into account. Ultimate-ly, the most productive system is one that optimizesprofits; that is, one that allows for costs as well asrevenue.

Labour productivity is seen by many as the key to costcontrol in deep-level gold mining. As pointed out earlier,there are a number of factors that support this view: first,nearly 50 per cent of working costs are labour-related;second, demands for higher wages can be met in the longterm only by. a higher output per worker; thirdly, as in-dicated by historical evidence, the social and economicimprovements for the work force that are needed to en-sure long-term industrial peace can be realized only if theoutput per worker is increased.

Historical evidence in the gold-mining industry showsa steady increase in overall labour productivity, expressedin tons of ore treated per employee per year, since theturn of the century (Fig. 7). Three periods of significantimprovements in labour productivities can be identified.The first of these is the period 1905 to 1915, which co-incides with the introduction of the light reciprocating

40

c33 '§

>'70

32'85'75 '80

Year

rock drills that replaced the earlier hammer drills. Thesecond period of marked improvement in labour produc-tivities, namely the period 1930 to 1940, is linked to theintroduction of scrapers in stopes and stope gullies. Thethird period started in the early 1960s and coincided withthe introduction of sequential firing of shot-holes in gold-mine stopes, which made the concentration of stopingoperations possible. Since then various other develop-ments have been introduced, including improved methodsof transporting materials into stopes, better support ofunderground workings, and mechanized methods of de-veloping raises and boxholes. The combined effect ofthese has been a general increase in productivity in re-cent years.

The significant feature of this historical evaluation isthat, in each case, a marked improvement in labour pro-ductivity was brought about by a change in mining tech-nology. From this point of view, gold mining does notdiffer from other mining industries. However, this situa-tion does not imply that the industry should not continuewith its efforts to improve productivity through bettermanagement, organization, planning, training, and moti-vation. Important benefits could be derived in the shortterm from attention to these aspects.

Stoping has been identified as the most obvious areafor improvement. Nearly half of the total undergroundlabour force is employed in stoping, the level of mechan-ization in stopes is very low, and the most significantchange took place more than fifty years ago when facescrapers were introduced to replace lashing.

A convenient measure of assessing the level of mechan-ization in tabular deposits is the output per unit lengthof face per year. Fig. 8 shows the total length of stopeface mined annually and the annual production per metreof stope face for the gold-mining industry for the period1972 to 1984. During this period, which was marked bythe demonetization of gold, the total length of facedecreased from more than 400 km in 1972 to about280 km in 1984, while the tons produced per metre of faceper year increased from about 170 t in 1972 to nearly 400 tin 1984. Much of this improvement in face productionwas due to an increase in the number of stope workersper metre of stope face, rather than to an increase in stopelabour productivity (Fig. 9).

A comparison of stope-face productivities with typicalcoal- face productivities is given in Table I. A comparison

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 381

-;;; 200c:

~ 180>-.~ 160-():J 140

"00

C. 120...

~ 100.c~

~-0I-

320

300

280

----

80

Fig. 7- Total labour producti-vity in the gold-miningIndustry

60 ;~~1l~~} Introduction of light reciprocating rock drills""""!..*O.'\

20

E=E=::=j Introduction of scrapers in stopes

~:!!::::!!!'j ~n~~~~~~:~~~dO~t~~~Ugentialfiring,

40

01900 1910 1930 1940 1950

Year1920

400

E... .:L~ ~ID

"0>- IDQ; g 300Co ~

ID .~g ~- IDID

()

Co ~0 -m ~ 200- 00 -mID; '0IDE :S

0>Q; g 100Co -:g ~0 -I- (:.

Fig. 8- Total length of stopeface worked on South Africangold mines, and annual pro-duction per metre of stopeface

0

1960 1970 1980 1990

" .......\

\\

\\

\

Tons per metre of stope face\r

year

-----'---r

- ---,--Total length of stope face advanced (km)

'70 '72Year

of the annual production per metre of stope face showsthat the output from 1 m of coal face is between 5 and15 times more than from 1 m of gold-mine stope. Stopelabour productivities on coal mines are ? to 30 timeshigher, depending on the level of mechanization, thanthose achieved in gold mines. Interestingly, the dif-ferences in stope labour density, expressed in the numberof stope workers per metre of stope face, are small.However, as expected, there are significant differencesin terms of the cost of stoping equipment per metre of

382 SEPTEMBER 1986

'74 '76 '78 '80 '82 '84

stope face. In the case of gold-mine stopes, the cost ofscrapers, scraper winches, pneumatic rock drills, andhydraulic props per metre of stope face is about R30oo.The cost of equipment per metre of production face incoal mines varies between about RI? 000 and Rloo 000,depending on the degree of face mechanization. Finally,the revenue per metre of production face on coal minesvaries from about 0,5 to 2 times that earned by 1 m ofgold-mine stope face.

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

Equipment RevenuetOutput per Output per No. of men cost. per per metre of

metre of face man per metre metre of face stope faceType of mining t/a t/a of face R R/a

Witwatersrand gold-mine stoping:j: 350-4oo 7oo 0,5 15OO-3ooo 50000

Coal mines

Conventional board and pillar 38oo 85oo 0,4-0,5 17 000 76 000Conventional pillar extraction 23oo 45oo 0,5 17000 46 000Continuous miner-bord and pillar 3300 14000 0,25 22 000 66 000Continuous miner-pillar extraction 3100 75oo 0,4 22 000 62 000Continuous miner-rib pillar extraction 33oo 95oo 0,3-0,4 185oo 66 000LongwalI mining-narrow seam (1 m) 1150 45oo 0,25-0,5 40 000 23 000LongwalI mining-wide seam (3 m) 4 5OO-6 000 10 000-20 000 0,3-0,4 + lOO000 90 000-120 000

. 1985 rands t Calculated on basis of 1 kg of gold = R20 000 and 1 t of coal = R20 :j: Industry average

1,0

0,9Q)()

'"- 0,8Q)Co.8 0 7(j) ,

1 000~~

900 ~'"~

800 ~to

'"700 E....(j)

to600 ~

'"500 .'!::.~0

400 .g~

300 ::-::>0

200 ~

, ----.;/' ' _..------.; ....--

'" --0Q) 0,6~

Fig. 9-Stope workers per ~ 0,5metre of stope face, and ~stope labour productivity, on <l>

South African mines ::- 0,4

<l>~(; 0,3~

~ 0,20ii)

0,1

-- - Stope labour productivity (tons/man per year)- Stope workers/metre of stope face <l>

100g.

Cl)

0 0'70 '71 '72 '73 '74 '75 '76 '77 '78 '79 '80 '81 '82 '83 '84 '85

Year

TABLE I

COMPARISON OF TYPICAL STOPING FIGURES FOR COAL AND GOLD MINES IN SOUTH AFRICA

It follows from this comparison that the three maindifferences between the production faces in coal and goldmines are the tons produced per metre of stope face, theamount of capital equipment installed per metre of stopeface, and the tons produced per face worker. Any discus-sion of gold-mine stope productivities must address theseaspects. A first estimate' of the amount of capital thatcan be spent in stope mechanization can be obtained fromformula (1), which is based on a comparison of stopingcosts before and after mechanization and takes into ac-count all cost ch~nges resulting from the introduction ofmechanization. the comparison is based on the assump-tion that the tonnage mined, the gold grade, and the goldprice remain unchanged. The equipment cost per metreof stope face per month, k, is given by the followini,4;

v' W . AP ..::lv (t!.F

)k = 0 + I - - v - -..::lb - r (1)

Po + AP0

Vo A '...

where

v is the rate of face advance per month (m),..::lvis the change in rate of face advance (m),

w" is the stope labour cost prior to mechanization(Rlm2),

10 is the cost per metre of face per month prior tomechanization (R),

~ is the stope labour productivity per man per monthprior to mechanization (m2),

AP is the change in stope labour productivity per manper month (m2),

t!.F is the change in fixed cost per month (R),..::lbis the change in other stoping costs (Rlm2), andr is the monthly cost of maintenance (RIm).

Based on the 1986 stoping costs of R300 per squaremetre and allowing 15 per cent per annum for capitalcharges, the maximum permissible investment per metreof stope face can be determined from the nomogram

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 383

shown in Fig. 10. The results obtained from this modelindicate that, provided the current productivity of the facelabour can be increased, significant investments per metreof stope face can be made in gold-mine stopes, even atrelatively modest improvements in the rate of faceadvance. The incentive for the mechanization of stopingoperations in gold mines is even more obvious if the exist-ing trend of labour costs, Le. a faster rate of increase thanthat of other costs, continues.

It should be noted that these conclusions are not new,but are an amplification of observations made by Profes-sor Salamon2 in his Presidential Address to this Institutein 1976. What is new, however, is the rapid change inthe political and socio-economic field that has taken placesince then. The need to press ahead with a determinedeffort to mechanize the central activity of gold mining-stoping-is greater now than ever before.

In the light of these findings, the question arises as towhy the gold-mining industry has not succeeded in in-troducing more highly mechanized methods of stoping.Many arguments have been put forward to explain this.

One argument maintains that great lengths of face haveto be available at any moment to ensure consistent pro-duction and grade of ore mined. However, this argumentis correct only if tonnage and grade are the main controlparameters. Furthermore, if total revenue and total work-ing costs are considered, the logic of the argument fallsaway. For example, the cost of refrigeration, ventilation,and maintenance is closely linked to the length of stopeface that has to be maintained to ensure a certain levelof production.

Another argument is based on the claim that labour-intensive methods of mining are required to solve themassive unemployment problem. It is my contention that,in the present socio-economic climate, this approachwould be correct only if labour costs were a small pro-portion of total costs. Once labour costs become themajor cost component, the economic viability of minesbecomes highly dependent on wages, and wage demandsand working places may indeed be lost as a result of suchdemands.

Yet another argument is based on the belief thatmechanized methods are uneconomic because of the highcost of the equipment and the high cost of running andmaintaining it. However, the economics of a miningsystem cannot be judged solely on the capital, running,and maintenance costs of equipment. Instead, the costof mechanization has to be judged against the outputachieved and the resultant savings in other cost areas.

It is sometimes argued that mechanization requires amore highly skilled labour force, but highly mechanizedmethods of mining have been introduced successfully inlocal underground coal and base-metal mines, where thelevels of skills are not significantly higher than in goldmining. The essential factor for the successful introduc-tion of these methods is rather that they should have ahigh production output.

A factual argument against mechanized stoping in deephard-rock mines is that the harsh environmental condi-tions are not conducive to mechanized methods. In par-ticular, the introduction of mechanization is adversely af-fected by the corrosion resulting from the hot, humid en-vironment and the high proportion of dissolved solids inthe mine water, the abrasion caused by the hardness ofthe rocks, the rock-breaking difficulties arising from thegreat strength of the rocks being mined, and the rockfallsand rockbursts caused by the high rock pressures thatexist in deep mines.

It follows from the above that there are no factors otherthan the environmental conditions in deep-level stopesto prevent the use of mechanization in stoping operations.However, there are a number of areas that will have tobe addressed. The first ofthese concerns the developmentof mining equipment for use under the specific conditionsin gold mines; the second concerns the man-power andmanagement infrastructures on the mines; and the thirdconcerns the cost infrastructure on the mines. In thecourse of my address, I shall return to these points.

EnvironmentAny real progress in the productivity of gold-mining

operations will depend not only on mechanization but on

Capital expenditure K(R/m)

800 W =R50/m2fo =R 1OO/m/monthVo =10 m/month

700 Po =15 m2/stoper/monthr =0,2 k

:2 600

'E0

~ 500~S~ 400u;0

~ 300

'"CoJ 200

0(\\"

'11({\~(\I

({\

'0({\

~o '::;"100

00 5 10 2015 0 2

Life of equipment n(years)

4 6 8 10

.1.V (m/month)

Pj=15%

Fig. 10-Relatlonshlp between Im-provements In labour productivity andrate of face advance, and the costs thatcan be Incurred In mechanization

(based on 1986 stoping costs)

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY384 SEPTEMBER 1986

improvements in the underground environment in whichminers and equipment will have to operate. I havedeliberately added the term mining equipment sinceenvironmental engineering on gold mines is traditionallyconcerned with the physiological aspects of the under-ground environment. As I pointed out earlier, one of themotivations for mechanization is the creation of moreskilled jobs in the mining industry so as to provide a basisfor the establishment of a more stable professional workforce. It stands to reason that, as the level of skills re-quired to perform a certain task increases, so will thedemands for an improved working environment. Further-more, reliable operation of even custom-designed miningequipment will depend to some extent on the environ-mental conditions. Another important factor in mechan-ized mining is that uncontrolled changes in excavationgeometry due to rock bursts or rockfaHs have a far greaterimpact on mining performance than in conventionalmining. Consequently, the demands for improved stratacontrol will increase in the future.

By far the most important environmental problemfacing deep-level gold mines is that resulting from heatflow into the workings. Fig. 6 shows the increase in theaverage rock-breaking depth and virgin rock temperaturefor the period 1962 to 1985. In an examination of thistrend, it should be remembered that, with the de-monetization of gold in the early 1970s, many low-gradereserves on existing gold mines became payable, and con-sequently the rate of increase in mining depths and rocktemperatures flattened considerably in the 1970s. How-ever, this is only a temporary phenomenon and, oncethese reserves have been exploited, the rate of increasein rock-breaking depths and virgin rock temperature willagain steepen. Fig. 11 gives a summary of the installedand predicted rated refrigeration capacity on SouthAfrican gold mines. The rapid increase in refrigerationcapacity since 1976 is an indication of the industry's com-mitment to solving the heat problem.

The long-term strategy is to ensure a wet-bulb tem-perature below 28°C in all working places so as toeliminate the need for heat acclimatization'. Fig. 12gives an estimate of the refrigeration requirements for theachievement of this goal in deeper mines. These require-ments are based on current mining practice and rates offace advance, and have been calculated for a rock pro-duction of 1000 kt per month. From this information, it

2 500

2 000

Fig. 11-lnstalled and predicted refri-geration capacity on South African

gold mines

a:1 500

::::::E

1 000

500

01970

is obvious that the approach to the cooling of very deepmines will have to be examined critically.

It is of particular significance that the thermal problemin deep mines is closely related to the total length of work-ing faces and to the heat flow that is allowed from theworked-out areas. An effective means of controlling thethermal environment in deep mines is to reduce the totallength of face worked and to minimize the heat flow fromworked-out areas by the filling in of these areas6. Thelatter not only helps to improve the thermal environmentbut, even more important, has far-reaching consequencesin terms of improving strata control. The benefits thatare likely to result from high rates of face advance andback filling are very substantial, as shown in Fig. 13. A50 per cent reduction in heat per ton per month appearsto be quite feasible in the case of deeper mines as a resultof an increase in the average monthly rate of face ad-vance from 5 to 20 m and of the introduction of backfill.In the case of mines in which the rates of face advanceare already high, the only means of reducing heat loadsin deep stopes is through the backfilling of mined-outareas.

An important conclusion that follows from thisexample is that the objectives of face mechanization andenvironmental control are complementary. A further con-clusion is that the solution to the thermal problem in deep-level gold mines lies in overall mine design and miningmethod, and not through the provision of additional re-frigeration capacity. This aspect was ignored in the pastand requires much attention.

Mechanization of any kind requires that optimal con-ditions for the operation of the equipment should beestablished and maintained. Strata control and stope-width control are therefore essential prerequisites for suc-cessful stope-face mechanization. Indeed, many attemptsto mechanize face operations have failed because of poorstrata control. Production delays due to rockfalls anddamage to mining equipment due to rock bursts assumefar more serious proportions in highly mechanized stopesthan in conventional stopes. Consequently, there is anurgent need for radical improvement in strata control indeep-level gold mines. A first step in this direction wasthe introduction of rapid-yielding hydraulic props in gold-mine stopes in the 1970s. Several hundred thousand ofthese props have now been purchased by the industry(Fig. 14), but even this large number is insufficient to

Installed refrigeration capacity

//

/Predicted /

//

/,,/

,,/

1975 1980 1985 1990

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 385

,...,

S 360~~;; 320-(}rog- 280(}

c:.2 240~...Cl)

.!2I 200...-Cl)..."'C 160Cl)...:JC" 120Cl)a:

480.

440 28°C

3000

equip all of the 280 km of stope face. Again, the low levelof face utilization as characterized by the low produc-tion per metre of stope face is the major stumbling blockfor significant progress in this area.

Where there is large-scale mechanization, rapid-yielding hydraulic props on their own are insufficient toprovide the degree of strata control required. Of all themethods of strata control available at present, backfillappears to be most suitable since it not only providesregional support but also improves local strata controlin the face area. In this connection, it should be pointedout that successful mechanization of deep-level stopingoperations is possible only if the rockburst problem iseliminated. This statement is based on two observations.First, most rockbursts occur within a few hours of theblast; that is, when the mine has been evacuated. Second,as shown in Table I, virtually none of the equipment in-stalled in stopes can be damaged as a result of rockbursts.In highly mechanized stope faces, mining is likely to takeplace around the clock, particularly if non-explosivemethods of mining are employed. Consequently, everyrockburst that occurs constitutes a danger to life andlimb. Furthermore, the cost of the equipment installedin stope faces is many times greater than that used in con-ventional stoping. Effective rockburst control is thereforea prerequisite for successful and meaningful stope-facemechanization.

Only two known methods have shown promise inachieving effective rockburst control: the use of stabi-lizing pillars, and the use of backfill. Of these methods,stabilizing pillars are more easily introduced but sufferfrom the disadvantage that valuable ore reserves are lostin the pillars and that local strata-control problems arecreated in areas where the pillars form tight corners withthe stope faces. From these points of view, backfill ismore attractive since it does not suffer from these dis-advantages. However, back{ill of the highest quality andinstalled close to the stope face is required to ensure ef-fective rockburst control. Backfill, because of its excellentlocal support characteristics and its environmental ad-

400

Fig. 12-Effect of depth of mining on total refrigeration re.qulrements to ensure an average stope wet-bulb temperature

of 28°C (monthly rock production 1000 kt)

:2C 1200EQ;0. 100c:0

§80

c:.~u.g 600

C.

~ 40I

386

,"

".

'., No backfill

" /" (

"

~._.- '-'-~ "'"

}Distance

10 m of backfillfrom stope

Stope width 1 m 5 m faceVirgin rock temperature 50°CWet-bulb temperature 28°CDry-bulb temperature 29,5°C

80

40

00 1 000 2 000

Average rock breaking depth (m)

160

140

20

00 5 10 15

Rate of face advance (m/month)

Fig. 13-Effect of backflll and rate offace advance on heat production in

stopes

20

SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

400

0g 300

~.....

'"C-o~ 200

-,-,....-'/'

//,-('

,:;.' \No, of props in use

'0~Q)

.Dg 100z , ,

-'----0 --'70 '75 'so

Year

Fig. 14-lntroductlon of rapid-yielding hydraulic props in deep-level gold mines

vantages, is the obvious preference when mechanizedmining is practised.

From this discussion of the environmental aspects ofdeep-level mining, three important conclusions emerge:firstly, high rates of face advance result in a morefavourable thermal environment and should be aimed for;secondly, backfill should be seriously considered as amethod of supporting deep-level stopes since not onlydoes it provide good regional and local support but itgreatly facilitates the cooling of deep mines; and thirdly,the environmental requirements of mechanization shouldlead to a very much safer mining environment.

SafetyMuch has been said in recent years about safety on

South African mines in general and deep-level gold minesin particular. The mining industry has been accused byunions of a lack of concern for the safety of its workers.In turn, the industry has pointed out the steady improve-ment in safety records over the years, and this is borneout by statistics (Fig. 15). Much of this improvement hasbeen due to managerial attention to safety matters anda concerted drive to increase general safety awareness onthe mines. The introduction of a loss control programmeand an international safety-rating scheme in the late 1970shave contributed much to the improved safety situationin recent years. However, there is no doubt that muchmore will have to be done in the progress along the pathtowards safer deep-level mining.

Safety, particularly in mining, is a complex problemthat has many facets. First and foremost is the humanaspect, constituting an area in which much benefit canbe gained from closer contact between management andworkers. Clearly, both parties have the same overall ob-jective, namely the elimination of accidents on the mines.There is a need to create a forum where worker andmanagement can meet to address safety matters. Second,there is the management aspect of safety. Much progresshas been made in this area in recent years, and many ofthe safety achievements can be attributed to bettermanagement. However, it should be realized that eventhe best management cannot compensate for an unsafeenvironment. Thirdly, there is the aspect of safetyengineering. In essence, safety engineering aims at theachievement of a safer environment. Fourthly, there is

3,6

3,2

0;~ 2,8:;;<>~ 2,4"'"0a.E 2,0

"00

~ 1,6

'".:!!~ 1,2

'ss -c;;

:§0,80f--

0,4

'00 '20 '40 '50 '70 '80 '90'60'10 '30Year

Fig. 1S-Annual fatalities per 1000 employees on gold minessince 1900

the aspect of protection of workers, which should not beseen as a primary safety strategy but as an additional safe-ty measure.

In this address, I shall concentrate on the aspect of safe-ty engineering, which I regard as the most powerful ap-proach to improved safety on deep-level mines. Forexample, the approach adopted by the industry before1960 to protect workers against the effects of heat washeat acclimatization and the identification of heat-intolerant workers. The success of this approach is evi-dent from Fig. 16, which shows the annual fatalities dueto heat stroke for the period 1930 to 1985, together withthe population at risk as a result of increases in labourforce and in the average depth of mining. During thisperiod, the incidence of fatalities due to heat strokedeclined considerably, despite an equally significant in-crease in the labour force. However, there is a limit tothis approach and, as the depth of mining increases, theonly feasible means of protection is extensive minecooling. The extent to which this approach is followedby the industry is apparent from Fig. 12. The benefitsto be gained from mine cooling are shown in Fig. 17,which gives the predicted incidence of heat-stroke fatali-ties as a function of wet-bulb temperature. According tothis relationship, the problem of heat stroke can beeliminated for all practical purposes if the wet-bulbtemperature in all working places is reduced to about28°C. Ways in which this objective can best be achievedin deep-level gold mines have been outlined.

The most serious safety hazard in deep-level mining isthat related to rock pressure. According to the most recentsafety statistics, falls of ground and rockbursts accountedfor 53 per cent of all fat~lities and 27 per cent of all in-juries on gold mines. Furthermore, in relative terms ac-cidents caused by rockbursts and rock falls have increasedin recent years, indicating that the rate of progress made

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 387

1 000,00

0 100,0000

~'C 10,0

'"E

""1,0

uc

'"'0u 0,1c

~::J0,01c

cet:

30

~ 20

~ ..~

II

I 300 ~

I 0I g

II

I -I

//

/.....

...'".. .....", .~-

;;.'"10<i~ --

~--~-,

01930 '35 '40

0

'75 '80 '85'45 '50 '55 '60 '65 '70Years

Fig. 16-Annual heat stroke fatalities and population at risk

Mortality rate

0,00126 27 28 29 30 31 32 33 34 35 36

Wet-bulb temperature (QC)

Fig. 17-Predlcted incidence of heat stroke as a function of wet-bulb temperature

in the reduction of safety hazards related to rockfalls androck bursts was slower than that in other areas. There arefour main reasons for this: firstly, despite the general andsignificant improvement in the understanding of the rock-pressure problem in deep-level gold mines, there are stillseveral open questions concerning rockbursts; secondly,regional stabilization measures take considerable timebefore they become fully effective; thirdly, whereas theaverage depth of mining has not increased in recent years,the extent has. In addition, previously unpay remnantsof reef that are highly stressed have been extracted as aresult of the improved price of gold; and fourthly, thelength of stope face that has to be supported, althoughsignificantly reduced over the past decade, is still ex-cessively long.

Significant improvements in accidents related, to rockpressure can be made only if the question of regionalstabilization measures is rigorously addressed and if thelength of working places that have to be supported andmade safe on a daily basis are reduced. At present, morethan 1,5 km2 of hangingwall have to be made safe dailyin stopes alone if it is considered that all stoping activitiestake place within 6 m of the stope face. A doubling ofthe rate of face advance would reduce t/,le working areato half this figure. At the same time, the density of facesupport in the form of hydraulic props would double,

388 SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

--------

300

14

c

000

12

200 ~200o:i 10

a.0g 8

;;c0;;

100 ~"-

-.Q)-co....

..,..1/.

,/,{

-.rJ)a.0

100 cl:6

>-.....::. 4c

2

0'84

Props in use

0'74 '76 '78 '80

Year'82

Fig. 18-lntroductlon of rapid-yielding hydraulic props In gold-mine stopes, and fall-of-ground Injuries per 1000 employees per

year

and hence the quality of face support would improvesignificantly. This is illustrated by Fig. 18, which showsthe effect of rapid-yielding hydraulic props on safety.

While there is room for improvement in the rate of faceadvance through better organization and management,I believe that, in the long term, substantial increases inthe rate of face advance will result only from changes inmining technology. In this connection, I refer to ex-periences in the British coal-mining industry (Fig. 19). In1955 more than 140 persons were killed by falls of groundat the coal face in British collieries. This was at a timewhen face operations were largely labour-intensive hand-filling systems and strata control was achieved by hand-set steel props and bars, and by hand-erected pack-and-waste systems. The introduction of hydraulic props,hydraulic chocks, and ultimately fully mechanized self-advancing hydraulic support systems reduced this numberto 3 in 1983. At the same time, significant improvementsin productivity were brought about by the changed miningtechnology. In his Presidential Address to the NorthStaffordshire Branch of the Institute of MiningEngineers, W.L. Pugh7 concluded: 'the man-power-intensive mining systems which remained largely un-changed from the 1920' s to the early 1940"s also sustainedan annual fatality level of the order of 1000 deaths peryear. The technical stagnation of the industry during thisperiod was, in my opinion, the main inhibiting factormitigating against any real improvement in safety'. I canonly concur with this conclusion.

The major challenges of deep-level mining-to achievehigh labour productivities, to establish a better andhealthier environment, and to improve safety on ourmines-can be met only by improved mining technology,particularly stoping technology, and by increased outputper metre of stope face. Any development that is aimedpurely at better labour productivity without an accom-

~2001

;: 180 l"'1:> 160c::J00, 140

'0!!!. 120 .a;

.8 100Q)

:J1:>rn 80

CQ)

~ 60()

CI1

................

....

a;

"'

40

'0ciz 0 3

'55 '58 '61 '64 '67 '70 '73 '76 '79 '82 '85Year

Fig. 19-Fatal accidents due to falls of ground at the face com-pared with face labour productivity (O.M.S.) in British collieries

from 1955 to 1984 (after Pugh1)

panying improvement in production per unit length offace will fall short of achieving the goals of the industry.

The Engineering ChallengeIn discussing the mining challenges to the industry, I

have mentioned some of the factors that have preventedthe large-scale mechanization of gold-mining operations.Among these, the most important are the strength, hard-ness, and abrasivity of the quartzites and reef con-glomerates. Next come the constraints imposed on miningequipment by the narrow channel width of most reefs andby the absence of well-developed continuous partingplanes that could be utilized to form smooth hangingwallsand footwalls in the stopes. The similarity in strength ofthe reef body and the surrounding strata is another factorthat makes face mechanization difficult if blasting isemployed as a method of rock breaking. Finally, the hot,humid environment and the high acidity of the mine watercreate an environment for corrosion that is far worse eventhan a marine environments.

The lack of success in the mechanization of stopingoperations using traditional engineering approaches high-lights the need for the development of new technology.

MaterialsCorrosion and abrasion are the major factors limiting

the life of mining equipment in deep-level gold mines.For example, the wearing parts of face conveyors em-ployed on longwall faces in coal mines are designed tohave a life of 1,5 to 2 Mt of coal before they have to bereplaced. Similar conveyors used in gold mines wear outafter only a few thousand tons of reef have been movedfrom the face.

Two approaches to overcome the materials problemare being followed by the Research Organization of theChamber of Mines: to reduce the agressiveness of theenvironment by treating the mine water, and to developmaterials that are both corrosion-resistant and abrasion-

10

resistant. The use of 8 to 12 per cent chromium steels withmicrostructures designed to provide hardness, toughness,and strength shows good promise in this regard. Forspecial applications where extreme hardness and resist-ance to flow erosion are required, engineering ceramicshave been identified as a possible solution.

g

8 PowerThe provision of power in a suitable form is one of

the greatest obstacles to the development of equipmentfor use in narrow stoping excavations. The great strengthof the rock that is being mined requires stoping machinesthat can generate large forces and torques in a confinedspace.

Traditionally, compressed air and electricity have beenused to power stoping equipment. Compressed air hasthe advantage that it can be used readily in stopes withoutthe need for skilled labour, and it also provides a smalldegree of cooling. However, because of the generally lowair pressures, large forces cannot be generated in thelimited space available. Furthermore, compressed air isan inefficient and very costly form of power. Electricityis generally accepted as an excellent form of power foruse in mines. It can be readily distributed but requiresextensive safety precautions and controls, which can makethe overall system expensive. Apart from safety con-siderations, the single largest factor mitigating against theuse of electrical power in stopes is that it is totally un-suitable for generating high forces. Further disadvantagesare the need for skilled labour and the fact that all theelectrical energy used is converted into heat, therebyadding to the environmental problem in deep mines.

Hydraulic power has the major advantage in that largeforces and torques can be generated by compact linearand rotary actuators. It is therefore ideally suited for usein compact equipment. However, hydraulic power is notfree of problems. The most serious of these is caused bythe loss of hydraulic fluid through leakages. If oil is usedas the fluid, these leakages are not only very costly butalso result in pollution of the environment. Because ofdifficulties in preventing leakages in the rigorous miningenvironment, the industry worldwide has been workingon the development of equipment that uses oil-in-wateremulsions. Following the successful introduction of thistechnology, the next obvious step is the development ofhydraulic equipment that can operate on water alone. Indeep-level mining, this approach is particularly attractivesince the hydraulic head of chilled water brought intomines for cooling purposes is sufficiently high to powerhydraulic stoping equipment. The attractions of a com-bined cooling and powering system are so great that theindustry, through its Research Organization, has em-barked on the development of the hydropower system.Already there is one section of a mine making use of thehydropower concept to cool stope faces and to operatewater-jetting equipment. Also a hydraulically poweredscraper winch has been built and operated successfully,and hydraulic transformers to power emulsion l:1ydraulicrockdrills using the hydropower concept have been de-veloped and tested.

A vai/abi/itySystem availability is the key issue to successful

mechanization. To achieve high levels of availability, it

-;;;Q)

7 ~0

.:::

6 ~::;0

5 ~CI1

LL

4

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 389

;;; '0c. ;;;~..0

:::;: E

'"z0

/'/'~

'./.

/.-'m3/s/environmentalofficer -r--- - --....1 .,," . '..

"" ./- ..../

",/'

,-,-,-,-'-'-""""\MW per environmental officer per year

is essential that mechanized mining systems should haveas few components as possible and that the equipmentitself should be as simple as possible. It is in this regardthat hydropower is most attractive. Operating experiencesat Kloof Gold Mine have been impressive, with virtuallyno breakdown of the hydropower system over a periodof one year. This has resulted in the total acceptance ofwater-jetting as a means of stope cleaning. On the con-trary, despite many attempts, the introduction of water-jet stope cleaning on other mines not using hydropowerhas not been successful because ofthe unreliability of thepumps required to supply water in sufficient quantitiesat the right pressure.

A further factor governing the availability of mechan-ized mining systems is the provision of an adequateengineering infrastructure on mines. This applies under-ground as well as on surface. Artisans and artisan aidswill have to be provided in sufficient numbers, and plan-ned maintenance schemes will have to be introduced forunderground equipment. Furthermore, the role of theminer will have to change, emphasis being placed on theoperation and maintenance of equipment, rather than onmining aspects. In this regard, I should like to mentionthat, in highly mechanized coal mines, the traditionalminer has been replaced by a miner-fitter. Similardevelopments will have to take place locally if mechaniza-tion is to succeed.

The Human ChallengeThere can be no doubt that the introduction of new

technology in deep-level gold mines will have far-reachingconsequences in the human area. New technology requiresnew skills. This observation relates not only to the workerbut also to management. Communication of the changeswill have to be carefully planned to avoid otherwise in-evitable industrial conflicts. The need for more highlyskilled workers can be met only by a change from a migra-tory to a permanent work force. This, in turn, may re-quire changes in housing policies and can lead to fric-tion between permanent and rural workers. In particular,the latter may feel deprived of certain rights and privi-leges, which may have to be given to permanent workers,who will tend to live with their families on the mine

400~en

'"uEC>c:

3 'r: 300~

No. of environ1ental officers

.:.

'"0u'0C)

0 .S:

(ij 2 -g 200

~ ~g ~~ '".~ -;;

'"1 :;; 100

'70 '72 '74 '76 '78Year

property. Careful considerations will have to be given toall these questions so that the fruits of new technologycan be reaped to the full.

StaffAs I have already pointed out, major changes have

taken place in the industry during the past fifteen years.Considerable benefits can be gained from a closer exam-ination of some of these changes. When discussing theneed to improve the environment, I showed that, duringthe past fifteen years, the industry increased the installedrefrigeration capacity on its deep-level mines from lessthan 200 MW to more than loo0MW. Over the sameperiod, the amount of air that is pumped into the minesto ventilate working faces and to distribute cooling in-creased from about 24000 to 36000 m3Is. However, thenumber of qualified environmental staff on the mines in-creased from 312 in 1970 to 380 in 1985 (Fig. 20). Overthis period the installed refrigeration capacity per en-vironmental officer increased from less than 0,5 MW tomore than 3 MW, while the quantity of downcast air perenvironmental officer increased from 78,5 m3/s to about100 m3Is. These figures suggest that the capital invest-ment by the industry to improve environmental controlhas not been matched by a comparable increase inenvironmental staff. Similarly, the consumption of elec-tricity in the gold-mining industry has risen at a faster.rate than the number of electricians employed in the in-dustry, as indicated by the number of kilowatt-hours peryear that are supported by an electrician (Fig. 21). Thisincreased from 43 million kilowatt-hours in 1970 to 55million in 1985, or by more than 27 per cent.

In contrast to these trends, the number of managerialstaff on the mines has increased in direct proportion tothe ore production (Fig. 22). It is noteworthy that the tonsproduced and the number of underground workers permember of managerial staff remained virtually un-changed over the period.

These trends indicate that the mining industry has re-mained largely production-oriented, and that the staffingof some of the essential service functions has fallen some-what behind. This trend will have to be reversed if theindustry is to succeed in implementing new technology.

120 ~

'".~100:S

(ij80 ~

Ec:60 ::

';;c:

40'";;;c.

20 ~ME

Fig. 20-Environmental staffin the gold-mining industry(environmental officers andhigher)

0'80 '82 '84

390 SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY

400

Electricity consumption billion KWh per year

300:;;

'">-c;c.

70 ~

01Q)

>-60 ~Q)

c.

50 .~0

40 ~Q)

Q;

Fig. 21-Annual electricityconsumption, and number ofkilowatt-hours supported byone electrician

;:: 200~c:

~

~~------------i:D

100

0

"70 '72

400

Million KWh per electrician per year

30 ~Q)

c.

20 ~~

10~~

'74 '76 '82 '84'78 '80

Year

1 000 tons per year per managerial staff r-..../' ,,/', // "/ ' '/""'-

/ \ / -.\"" "--~/" ,-_/, -""'"

300

200

2

rig- 22 II8n8geria&stIdf Inthe yoIkkDning Industry (in-cIuc8ng gr8duaIe min8IgengIneeIs)

'-'-. -'-, '-'-. -' ,--,-,-' --'-'-"1 000 U/G workers per managerial staff

0

'70 '76 '78Year

'84'72 '74

A determined effort is required to attract artisans andspecialist. staff to the mines to epsure that maximumbenefit is obtained from major capital investments, andthat a solid basis is created for the introduction of newtechnology.

ManagementIn the management area, I foresee a need for a change

from the existing hierarchical system to a fully integratedsystem that promotes participation in the decision-makingprocess by all the disciplines involved in the operationof a mine. New management structures will have to beintroduced to ensure that the full benefits are being ob-tained from new technology. For example, I foresee dif-

'80 '82

ficulties if the management of a hydropower system isbased on the same principles as that of the compressed- .

air and refrigeration systems, where two, and sometimeseven three, different departments are responsible for cer-tain aspects of the system. As the level of mechanizationof mining operations increases, the contribution that theservices, particularly the engineering department, canmake to the performance of a mine will increase. Thischange in emphasis will have to be addressed by minemanagement, who will need to have much greater ex-perience in the engineering aspects of mine operationsthan exists at present. In order to attract the best engineersto the mines, engineering must be seen as one of the routesto top management.

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY SEPTEMBER 1986 391

Similarly, the role of mining engineering will have toincrease to ensure that mine designs take into account allthe implications of new technology. Highly mechanizedDining operations tend to be less flexible, and thereforerequire more planning and management attention, thanlabour-intensive methods of mining.

CostsClosely linked to the management system on many

mines is the cost control system. Traditionally, cost ac-counting and control are done on a responsibility basis,each mining official being responsible for the costs oflabour and stores. Capital costs are usually written off,rather than being amortized over the lifetime of the equip-ment. The costs of the infrastructure for services suchas compressed air, ventilation, refrigeration, and waterhandling are generally not allocated at the level at whichthey occur, but at a higher level. Consequently, it is dif-ficult, if not impossible, to establish true productioncosts. A responsibility costing system has many advan-tages in situations where there are no changes (or onlyminor changes) in technology. However, the traditionalresponsibility, accounting, and costing systems are totallyunsuited to the assessment of the costs involved in newtechnology. These can be assessed only by a truly func-tional costing system that accounts for all changes.

I am of the opinion that mines should give serious con-sideration to supplementing the traditional responsbilitycosting system with a functional costing system, and soprovide a basis for the assessment of the economic per-formance of new technology.

ConclusionsI have attempted to analyse the effects of a changing

socio-economic and political climate on deep-level miningoperations. While many of my observations are specificto deep-level mining, some also apply to mining ingeneral. I have come to the following conclusions.

(i) The continuing pressure for higher wages and im-proved conditions of employment on the mines canbe met in the longer term only by an increase inlabour productivities. The substantial improve-ments in wages paid to the largely unskilled workforce on the gold mines was made possible onlyby the increase in the price of gold in rand terms,and were not the result of improved labour pro-ductivity.

(ii) Safety and environmental conditions on deep-levelmines can be improved in the longer term only ifthe production per metre of stope face, that is therate of face advance, is increased.

(iii) Improvements in labour productivity and in therate of face advance are restricted largely by thetechnology employed in deep-level stopes. Signifi-cant improvements in deep-level mining efficien-cies can result only from the mechanization ofstoping operations.

(iv) The harsh environmental conditions in deep-levelgold mines and the confined working space instopes severely restrict the application of miningtechnology developed elsewhere, and require thedevelopment of special stoping equipment to suitlocal conditions.

(v) The successful introduction of new technology indeep-level mines will depend largely on the avail-ability of skilled workers. The shortage of artisansand other skilled workers in the gold-mining indus-try is of great concern. Novel ways of solving thispressing problem will have to be investigated.

(vi) The role ofthe engineering and service departmentson deep-level mines will increase as a result of thechange from labour-intensive to more capital-intensive methods of mining. Due considerationwill have to be given to this shift in emphasis toensure the full participation of these departmentsin management decisions.

(vii) The cost thinking as it exists at present on mostdeep-level mines will have to change to account forthe envisaged change from labour-intensivemethods of mining.

(viii) The introduction of higher-level mining technologyin deep-level mines has the potential for consider-able job advancement and improved conditions ofemployment for all workers.

The South African Institute of Mining and Metallurgyhas an important role to play in advancing science andtechnology in the minerals industry. This is achieved bythe publication of a monthly journal and technical books,the organization of symposia and colloquia, and theholding of schools and workshops. In addition, the Insti-tute promotes the formation of working-interest groupsin areas of importance to the industry. I foresee that therole of the Institute in this area will have to increase tomeet the requirements of the industry.

AcknowledgementsIn preparing this address, I drew freely on ideas

(sometimes written, sometimes expressed verbally) of mycolleagues in the industry and in the Chamber's ResearchOrganization. I wish to thank them for the many fruit-ful and inspiring discussions. I gratefully acknowledgethe assistance given to me by many units of the ResearchOrganization and Head Office of the Chamber of Minesin collecting the data on which this address is based.

Finally, the foresight and courage of the leaders of themining industry to embark on a structured long-term pro-gramme of research

'and development to change deep-

level mining technology have to be applauded.

ReferencesI. WORRALL, D. South Africa: Government and politics. Pretoria,

J.L. van Schaik, 1975. 168 pp.2. SALAMON, M.D.G. The role of research and development in the

South African gold-mining industry. J. S. Afr. Inst. Min. Metal/.,vol. 77, no. 3. Oct. 1976. pp. 64-75.

3. SALAMON, M.D.G. Private communication, 1977.4. BERGER, E. Techno-economic evaluation of South African gold

mines. Ph.D. thesis, Leoben (Austria), 1978.5. BURTON, R.C., KIELBLOCK, A.J., SHEER, T.J., and BLUHM, S.J.

Paper to be presented at GOLD lOO, Johannesburg, Sep. 1986.6. BLUHM, S.J., VasT, K., and STEWART, J.M. Effect of back fill on

heat pick-up in a stope. Chamber of Mines of South Africa, ResearchOrganization, Research Report 3/84.

7. PUGH, W.L. Efficiency and safety-the link. Min. Engr, Feb. 1986.pp. 343-346.

8. JOUGHIN, N.C. Developments in stoping technology in deep narrow-reef gold mining. Paper to be presented at GOLD lOO, Johannesburg,Sep. 1986.

392 SEPTEMBER 1986 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY