BELT CONVEYORS IN
MODERN MINE MECHANIZATION
LIBRARY COLORADO SCHOOL OF
GOLDEN,COLORADO
by
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A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Hines in partial
fulfillment of the requirements for the degree of Master of Mining Engineering
' r _ . l t-' Signed: Golden, Colorado Date: °'Vv^ A 4~ 1950 Approved:
<***=»+-Clifton If* Livingston v Golden, Colorado
TABLE OF CONTENTS
Introduction • • • • « • » • * ...* *
The Impact of Mechanisation Upon the Mineral ‘ Industry • • • « • • • • • • • « * • • • • • • 5 The Paint Beginnings of Mechanization • • • • • 5 The Necessity for Mechanization • * • • « • • • 7 The Cost Aspect in Mine Mechanization • * » • • 16 The Prerequisites for Successful Mine
Mechanization • • • • « • • « * • • • • • • • • 19 Evolution of Belt Conveyor Transportation « • « • • 25
*
The Practicability of Belt Conveyors • • • • • • • • 3&
The Belt Conveyor Structure « • * « • • • • • • • • 55 Components of the Conveyor Structure • . ♦ • • 56 Mining Belt Conveyors Classified by
Design Features • • • « • • « • • • • • • * • • 65 Slngle^pulley drive conveyor • • • * • • • 66 Snub-drive conveyor • • • • « • • • • • • 68 Tandem-drlve conveyor • • • • • • « • • • 68 Dual-*drive conveyor • • • • • « • • • • • 70 Mining Belt Conveyors Classified by
Operational Use ... * ... 71 Mining Belt Conveyor Control • • • • • • • * • 75 A Portfolio of Conveyor Structure Components • 78
Page
Elements in Conveyor Belting • • • • • • • » # • • 86 Duck and Cord Belting • • • » • • • ♦ • • # 87 Steel Wire Cable B e l t i n g ... 92
Mine Belt Horsepower Requirements 96
Conveyor Belt Tensions • • • * » < • • • • • • 100 Mine Belt Speeds # • • # • • « • • • * • • • 103 Mine Belt Capacities • * • • • • « • • • • # 10l|. Long Center «*- Fixed Length Mine Conveyors • • « • 108
Single Belt Flight Speed • • • # • » • # • • ^ 110 Single Belt Flight Horsepower • • # « • * # • 111 % Transfer Stations • • • • • # # # # • • • • 112 A Portfolio of Long Center Installations • • lllf. Steel Belt Conveyors • • • • # • • • # « • • * * ♦ 117
Sandvlk Stainless Steel Belt Conveyor • # • 118 Steel Belt Conveyor Pictorial Section « • • • 122 Case Studies of Mining Belt Conveyors • # • • # # 123
The D# 0* Clark Coal Mine, Superior*.
Wyoming# # • » • • # # • • • • • « • • * # # 123 The Climax Molybdenum Mine* Climax,
Colorado# • • • • • • • • • * * • • • • • * # 128 Conclusions • * • • « • • • • • « • • • • • • • # 138 Bibliography # # # # • * • • • « • » • • # • • • # 1I4.O
ILLUSTRATIONS
Frontispiece - A 36-In*-wide conveyor belt in operation at a gold mine in Canada* The belt is carrying mine-run gold ore from the mine ore bin to
a vibrating feeder and a picking belt.
Figure Page
1 Tower excavators and shaft cross-section
at Spruce Pit mine • • • • • • • Follows 31 2 Operational profile of belt system at
Spruce Pit mine * * • • « • • • Facing 32 3 Standard track haulage panel at Potash
mine • • * • * • « « • • • * • Follows 37
k Belt conveyor panel at Potash mine
• • • • • * * » • • • • • Facing 38
5 Gravity and horizontal take-ups • • • • • 60 6 Single pulley drive • * . • • * • • « * 67 7 Pneumatic pressure pulley drive • • • • * 68 8 Snub pulley drive . • * . « • * * • * • 68 9 Tandem pulley drive (1st Method) * . • • 69 10 Tandem pulley drive (2nd Method) • • • • 70 11 Dual pulley drive ... * * . 71 12 Methods used for driving mining belt
conveyors • • • • • * . • . * • Follows 71 13 Sectional mine belt conveyor for coal
and metal mine use * • • • * • • Follows 82 Uj. Tandem drive mining belt conveyor for
Figure 15 16 17 18 19 20 21 22 23 2k 25 26 27 28 29 30 31 32 33 Page Snub drive mining belt conveyor top
slicing operation • • • • • • • • Follows 82 Mining belt conveyor for block cav
ing operations • • • • • • • * • Follows 82 Tandem drive with balata-lagged
drive pulleys • • • • « • • • • Follows 82 Light coal-mine-type conveyor • • Follows 82 An intermediate section conveyor Follows 82 Intermediate section, showing Idler
design and location of middle
roller • * • * • • • • • • • • « Follows 82 Design features of mining belt conveyor
for undulating bottoms • • • « • Follows 82 Mine belt conveyor features for an
undulating bottom * » • • • • • • Follows 82 Short loading-station for a mining
belt conveyor ♦ • * • • • • • • Follows 82 Slidlng-type tail pulley • • . • Follows 82 Sliding tail end on side channel
framing • • • • • • • • • • • « • Follows 82 Mine belt conveyor with a boom dis
charge conveyor • • • « • • • • Follows 82 Boom discharge conveyor • # • • * Follows 82 A roller switch • • • • • • • * Follows 82 Sectional view of mine belt
idler • • • • » • • • • • • • • Follows 82 Mine belt conveyor idler unit • Follows 82 A low mounted, cantilever-type
carrier • • * • • • • • • • • « Follows 82 A rubber covered spiral return
idler * • • • # • • • • • • • • Follows 82 A pneumatic-tire impact idler
pag« Spacing of impact idler at loading
station • * • • • • • * • • • • Follows 82 Gravity and horizontal type
take-up • • • * * • • • • • # Follows 82 A type of stacker conveyor • • Follows 82 Typical mine belt cross
sections • * • • * * « • • • • Follows 91 Hawkins belt conveyor installa
tion • • • * « • • • • « * • * Follows 92 Profile of Hawkins belt conveyor Faces 93
Operational profile of Weirton mine
belt conveyor • » * • • • • * Follows 93 Basic belt tensions * • • • • • • • • • 100 Cross sectional loading « • • * . • • • • • 103 Conveyor line from Bedding, California,
to Carom dam site at Shasta . • . Follows 116 One of 26 flights looking toward Shasta
dam site • • • + * • • • • • » • Follows 116 The cement plant operation at Permanent©
Cement Company, San Jose, Calif* Follows 116 Perraanente Cement conveyor unit follow
ing terrain of land . * • • • • • Follows 116 Bull Shoals conveyor flight carrying
650 tphr of 6-in* miners rock • » Follows 116 Grand Coulee Dam flight conveyor carry
ing aggregate from gravel plant to
the dam site • • • • • * • • • • Follows 116 Anderson Ranch Dam 3-mile conveyor
carrying earth from pit to dam site
for building Coulee dam • • • • Follows 116 Sandvlk steel belt conveyor • • • Follows 122 Design types of a steel belt
Figure Page 52 Idler details of a steel belt
conveyor • • • • • * » » • • • • Follows 122 53 Idler set for a troughed Sandvik
belt • • • • • • • • • • • • • Facing 123
TABLES
Page muM Mh m i A Cost analyses on cave mining • 1jj6 B Top cover gauges « * • • • , • * • • « • 91 C Distribution of power in a belt conveyor • 100
system
D Materials conveyed by a steel belt • • • • 118 conveyor
E Carrying capacity of a steel belt • • • • 120 conveyor
P Estimated capital cost expenditures • • • • 131 G Analysis of operating costs and capital • • 132
ACKHOWIEDGHEHTS
The author wishes to, express his sincere apprecia tion to all those who assisted in the compilation of this thesist and particularly the following:
.t
Mr. E* W* Eewt'on, Manager, Engineering Sales, Barber Greene Company, Aurora#' Illinois.
Mr* J. W* Hardy, Sales Engineer, Goodman Manufactur ing Company, Blectri© Mining Machinery, Chicago, Illinois.
Mr. 17. H* Rolff, Construction Engineer# Robins Eng-* % Ineers, New York, N* Y.
Mr# M. S. Goodwin, Mechanical Goods Division, The Goodyear Tire & Rubber Company, $nc*, Akron, Ohio*
Mr* G. C. Crabtree, Manager, Belting Sales, United States Rubber Company, Hew York, U. Y*
Mr* J. H. Thompson, Manager, Belting, Industrial Products Sales, The B. P* Goodrich Company, Akron# Ohio.
Mr. A. P. Sinden, Chief Engineer, Stephens-Adamson Manufacturing Company, Aurora, Illinois*
Mr* W* J* Denelin, Manager, Conveyor Department, Sandvik Steel^ Inc*, Hew York, H* Y*
Mr* A. C. Lind, Manager, Conveyor & Process Equip ment Division, Chain Belt Company of Milwaukee, Milwaukee,
Mr* H. YU Cleveland, Advertising Department, New Departure, Division General Motors Corporation, Bristol, Connecticut*
Mr* J* Q* Berta, Superintendent, Superior Mine, Union Pacific Coal Company, Hock Springs* Wyoming*
Mr* He Nicholas, Chief Engineer, Climax Molybdenum Company, Climax, Colorado*
Hr* P. C* Roberts, Design Engineer, Climax Molybdenum Company, Climax, Colorado*
Hr. R* E* Harks, Design Engineer, Climax Molybdenum Company, Climax, Colorado*
Mr# L. M* Cooley, President, Edna Coal Company, Steam boat Springs, Colorado*
Professor C* W* Livingston, Head, Mining Department, Colorado School of Mines, Golden, Colorado*
Professor E* G* Fisher, English Department, Colorado School of Mines, Golden, Colorado*
Hr* Frank W* Vaughn, School Photographer, Colorado School of Mines, Golden, Colorado*
*
.The author wishes to express his sincere appreciation to the following companies for the various photographic
studies:
Figure 1, 2, 6, and 12 - Stephens-Adamson Manufactur ing Company, Aurora, Illinois*
Figures 13 to 29 - Goodman Manufacturing Company, Electric Mining Machinery, Chicago, Illinois*
Figure 30 and 31 ** New. Departure Division, General Motors Corporation, Bristol, C onnectiout*
Figure 32 and 3$ - Chain Belt Company of Milwaukee, Milwaukee, Wisconsin*
Figure 33,3^, 3&, k-3 to I4.9 - The Goodyear Tire and Rubber Company, Inc., Akron, . Ohio*
Figure 37 - The B* F* Goodrich Company, Akron, Ohio* Figure 38, 39, and Frontispiece - United States Rubber Company, Hew York, H* Y*
Frontispiece
1
BELT CONVEYORS
IN *
MODERN MINE MECHANIZATION
INTRODUCTION
In the past 30 Years the mineral Industry has diseov~ ered* and made use of* a machine which Castries and elevates materials* endlessly* quietly* efficiently* with little or
no attention* or under conditions approaching outright abuse*
This machine l3; the belt conveyor. It consists of a moving endless .belt which supports material and which* by
Its motion* carries the material from one locality to another* The belt is supported on both runs* going and coming* by rollers (idlers) and Is driven by a pulley* The belt Is a flexible jointless structure which runs quietly at any speed; It is not ordinarily harmed by the actual conveying of the material It carries* The ore may be put on the belt by hand* shovel* chute* or other means, and It
Is removed from the belt by being discharged over the end pulley or be being deflected at some point along the conveyor run*
2
Modern mechanization of today’s mines, whether they be coal, inetal, or nonmetal. Is radically changing the requirements for underground transportation. It has in
creased greatly, the need for reliability and belt conveyors are the most dependable means of moving ores away from thm place where they are mined*
$ Mining practice Is attaining a high degree of effi ciency as a result of years of experience and study on the part of capable mining men* From now on, however, the major
improvement In the mining industry, especially in saving of power and labor, and in greater profits, must come forth through the use of good mining machinery and well planned mechanized mine programs* Increased tonnage Production based on well planned, constructive, mechanized programs is essential to the progressive growth of the nation’s mineral Industry.
Belt conveyors have long had an important place in mining coal. The belt conveyor has been used extensively
as a main haulage unit in open pit iron mines of the Bake Superior district, especially on the. I.lesabi Range*
The average mine is a complex structure, composed of a variety of components* A rigid planning program Is not practicable and may defeat its own objectives and lead tb dislocation* Bach mine has its peculiar difficulties* The mechanized urogram should admit of a degree of flexibility
* In Its application*
3
conveyor has been very slov/* Pew ferrous or non-ferrous mines use the conveyors exclusively or extensively for tinder ground haulage* Mining officials are apt to be
conservative, waiting to see others succeed with new mechanical equipment# Because of the excellent success with which open pit operations have been carried out wlt^h belt•conveyors* a slow change in opinion is taking place in regard to underground operations*
It is generally conceded by those familiar with the
* ■
mineral industry, that prejudices and grievances on the part Of mining personnel against modern mining trends and ^ efficient operation die a slow death - more so* than with any other group of industrial workers*
Mine officials are inclined to be prejudiced against the planning and pre-planning of mechanised mine programs# They must ultimately be convinced that the Introduction of new mechanised methods In mining is an essential factor in the mine* s survival and the individual livelihood of the miner# The cooperation of miner and mine official is vital when considering the use of mechanical equipment* such as belt conveyors, the successful application of which requires utmost coordination of activities by the men who plan and direct mine operation®#
The use of belt conveyors (whether on the surface or underground) demands the continuous coordination of all mining operations* The success of any mechanized program
*>
entailing the use of belt conveyors depends on the thorough -handling of problems involved and the unification of basic
mine operations— transportation* loading* timbering* and breaking*
In scope this thesis covers the aspects of modern mechanisation* and dedla with sectional-type electrical ly driven belt conveyors as commonly used underground in non-metallic mines* metal mines* coal mines* and above ground in open pit mines* wherever the conveyor Is length ened or shortened as mining operations advance or retreat* This paper also deals with belt conveyors commonly used above ground having a fixed length for reasonably permanent installations hot requiring the feature of variable length*
5
THE IlC?ACT OF MECHANIZATION UPON THE MINERAL INDUSTRY
_...">"■ ... *•*» 111 i i ... iw «»'■
The mineral-mining industry of this country became conscious of the possibilities of modem, mechanised methods of transporting and handling ores only within
the past twenty-five years# There was available to the mining industry one of two methods of approach to meet the stepped-up demands of this century* s material civilisation# The increase in mass production could be attained only by an increase in human labor or by mechanized units* Mass production demanded faster output than human labor could supply; so mechanized units were chosen to meet the chal lenge#
The Faint Beginnings of Mechanization
Mechanization In mining probably began with the in vention of the lever and has developed continuously to the present# Explosives and rock drills probably enhances the exploitation of minerals to a great extent* Mechanical mucking machines and scrapers were developed at the end of
the nineteenth century but, because of unsuccessful applica tions and the opposition of labor in some districts, they were not much used until the 1920* s* The decade 1921 to
1931 v/itnessed the greatest increase in the use of mxeking and scraping machinery* Mechanization In the mineral in dustries has greatly improved the welfare of miners In
many ways# First, it has relieved them from much drudgery* First and most primitive method of underground haulage was carrying minerals in sacks, ‘baskets*, or other containers on the backs or heads of men and women* Later, as an im proved method of transportation, tubs on runners or wooden sleds were pulled by boys and even women in coal mines*
In l8i|-2 a British ©ouBaissIon reported that girls and
/Cutler* C# R#, Mechanization and Labor in the Mineral Industries8 Mines Magazine, p* 116, March 19if0_____ ' boys under ten years of age were working as draft animals In the low drifts of coal mines:
Chained, belted, harnessed like dogs in a go-cart, black, saturated with sweat, and more than half naked— crawling upon their hands and knees, and dragging their heavy
loads behind them— they present an appearance Indescribably disgusting and unnatural*
The introduction of the wheelbarrow make the work of hauling materials easier, but hauling In quantity and over extended distances could not be realized -until the four- wheeled buggy or cor running on a track had been developed*
Now mechanical scrapers, power shovels, and belt con veyor 37/s terns assume the backbreaking labor of getting the ore out of the ground#
7
their primitive mechanization; men working at headings where temperatures approached 120 P and the candles burned blue in the foul airs
By the compressed-air pipes, the five or six men at a heading receive fully 700
cu In. of air per minute*
Now with the application of electric fans and blowers
miners receive hundreds of cubic feet of "conditioned” air per minute*
Thus from the beginning, man has continually sought to relieve the drudgery inherent in mining operations and to increase the daily output of ores* He has come to re gard the use of machines as one of the main tools in this slow evolution*
t
The Necessity for Mechanization
It is an inescapable fact that as the surface of this terrestial planet is prospected and probed for available minerals, and as the maze of transport facilities is pushed nearer to completion, technology will be called upon to shoulder the increasing difficulties of mining the earthly ores of this planet*
The methods of mining tomorrow’s ores will be highly mechanized, striving for the mining engineer’s ideal opera
tion — a push button mine. The most radical and revolution ary changes brought about by mine mechanization will be in the field of transporting and handling of ores, though
changes will also take place in drawing, loading, excavating and drilling*
8
Present-day mining methods are based on classification of habitual practices of operation# Ho regard is given to the transportation method involved in bringing the ore to the ground surface# Transportation Is often the major cost Item In mining* and yet classification of mining methods disregards ore transportation methods#
In a discussion on ^Tomorrow’s Mining Methods#*1 M# A* Smith points out that the basic operations of mining are
~r /smith, II# A#, Tomorrow* s Llining Methods $ Engineering" and Mining Journal# p# 33# March 19hX>»
breaking and transporting ore* By being separated^ into their simplest elements# these operations can be critically examined and appraised* There are as many variations and combinations in the breaking and transporting methods as there are variations in orebodies, but employment of the appropriate means will result in the most economical method* The term stoping (from Middle English step* meaning ex traction of ore by steps) is unsatisfactory because it
coiobines the operation of breaking and transporting — al though the line of demarcation is not always sharp# For example* material is made to run directly into raises or slides v;hen broken by picking or blasting# Breaking and transporting# nevertheless, are distinct functions, and It is desirable that they be recognised as such# The three
fundamental methods of brooking ore or other materials
/Op* p. 33___________________________________ are (a) by drilling and blasting* (b) by mechanical or manual excavation* and (c) by caving# The transportation
of ore from the stope face to the surface may be regarded as one function requiring two or more stages* The stream lined methods of tomorrow* under ordinary conditions* will convey ore (a) by gravitational or mechanical conveyance from the stope face to the mining or stope conveyors* (b) , by mining or stope conveyors to the truck conveyor (main haulage conveyor)* and (c) by truck conveyor to the surface#
The timeliness of the preceding paragraphs is emphasized most sharply and vividly* in the problems that have arisen
in Great Britain in the mining of depleted iron ores* The mining Industry in America can well bear in mind the lessons brought out by the following discourse* which is an omen for our future operations#
Dr# Dm D* Howat* of the Koy&l Technical College*
/Howat* D# D*» Britain*s Iron Mines and Problems: Engineer*- log and Mining Journal, p» 7 k. May 19k9.____________ , . Glasgow, Scotland* speaks as follows on the decreased iron ore production in Great Britain:
Most Important of the metalliferous ore resources of Britain are the Jurassic iron ores* The iron^bearing measures of the Jhrassic system extend from the vicinity of the HIver Tees southwest to the Bristol Channel* The Ironstone Is generally phos phoric and of low iron content* rarely ex ceeding 3O to 33$* With almost half of the
10
burden composed of a 20$ Iron*-or©f blasts furnace practice at Frodingham is claimed to be the leanest ore-smelting practice in the world*
The Jurassic deposits* which were known In prehistoric times, became import
ant as large-scale sources of Iron about the middle of the 19th century* In the early stages of their development* th© Cleveland field was a determining factor in establishing the extensive iron in
dustry of the northeast of England* Later, the work Involved in building railways led to rediscovery of many of the deposits of the Midlands* As the overburden in the east Midlands was comparatively light In places, open-cut mining was introduced*
Methods of hand mining, originally employed, permitted the deposits to be worked selec tively, only weathered ore high enough in grade being extracted* During the past
US
to SO years, mechanized open-cut methods have been d eveloped* A striking example of the possibilities of those now In use Is the stripping of 80 ft of overburden to mine 8 ft of ore*In the Cleveland field where all the ore is mined by underground methods^ a Steady decline in output has been noted from 1913 to the present* Howat attributes this decline to the following elements: The lack of adequate mechanisation ■ ■! *|**I*|*WWW****W*^*—1*» I**|»»*I« II*>for mining and transporting the ores In the|KM I— iw^h* *1 ***—|W—**Wn**M* I«|lli* —I|»ln *■ ijjwTn I wi J ml i* i Wnn*n — ■*ni|<*i*i— !■**■i»«**uwij.— mu
mine* the approaching exhaustion of the most profitable seam, and the difficulty of securing necessary labor*
One of the major problems derives from the gradual
/op* clt», p* 75
exhaustion of the ore available for open-cut mining and the consequent necessity for developing underground work ings* It has been estimated that, in the Prod Ingham field,
at least two-thirds of the ore lies at a depth too. great to be recovered by open-cut working; in th© Northampton shire field, over one-half of th© reserves# Any increase in underground mining involves the difficulty of recruit ing labor for an industry already seriously undermanned and the provision of the up-to-date mechanized mining
I
equipment#
lYith the imminent need for underground mining, the wheel has come full circle in the. Northamptonshire fields ,
_ p« 75 ' ...' ... ...
where underground mining first began in 1870# These old shallow mines were abandoned when large excavators suitable for open-cut mining were introduced* After 50 years of open-cast work, the overburden is getting too deep for the modern excavator, and here also it is becoming necessary once more to engage in underground mining* Th© same con ditions apply in all the deposits except those of the
Cleveland field, where all operations are carried on under ground#
In one extensive test on the application of small scale mechanization to extracting Iron ore from a mine In the
Northamptonshire field (by the use of electric drilling, Eimco rock shovels, and electric battery locomotives), the total tonnage won during 19i|-7 was 100,*000 tons # The
12
average oiitput per manshift loaded into mine cars at the face was 17 tons* This rose to 19*71 tons for the last quarter of the year, compared with the figure of 8 tons per manshift obtained prior to mechanization*
Dr. How at concludes that any attempt to expand
cit.; P. 77
underground workings of the iron ore deposits by the methods formerly employed would be doomed to failure* There Is no prospect of attracting the necessary labor force to an
in-A
dustry, the successful prosecution of which depends largely upon physical stamina and manual skill. The only solution
lies in the application of extensive mechanization which will yield increased earnings and greater benefits for the
labor force* '
The mines of Great Britain have resisted the advance of mineral mechanization to a surprising degree* Sooner or
later, a nation is made to realize the advantages inherent in adopting mechanization programs for the continued survival of its mineral industry*
In the United States the trend has been to replace the hand labor q£ handling and conveying ores by machine labor
throughout the various phases of mining* This fact can be most clearly demonstrated by reference to the coal mines of
this nation*
At the close of World War I, the coal industry and
/llarshall* 'I* U*» Mechanl sat ion In Canadian Gold Hines: Canadian Hining Journal^ vol. 70* no* 7* p* 62* July 19^9*
13
particularly the coal mines of the centrfcl competitive field (Ohio, Illinois, Indiana) suffered from competition and labor problems.
Supplies and materials showed a marked increase in cost, and labor presented difficulties. Competition In coal had forced the same result as a government edict has now done with gold, namely, a reduced selling price for the product. At the beginning of the 1920*a many coal mine operators were discouraged, and exhibited feelings of apathy and frustra tion. The so-called MJacksonville Agreement" had imposed a wage scale arid labor condition for a period of ten years that operators felt was an almost insurmountable obstacle to prosperity. Hot only were supplies higher in cost but
— /op. ci't., p. 62 ' ■'
deliveries were uncertain. Coal mining felt the need for modernizing mining procedures. The coal mining Industry, under duress of taxes and rising wages, and in the face of competition from other fuels, were forced, for their own survival, to adopt better mining methods and more efficient equipment. The trad© and technical periodicals reflected/
/ i d e m . p V "Si : ' ; :
the Ills of the coal industry of that time* They also re cord the trend to mechanization to relieve those troubles and besetting conditions. Soon, technical papers were describing methods of mechanization adopted at various mines.
Hot until the early twenties did the industry* pay
/ Mechanization* Paper* Mining Congress Journal# p* 29, ~
July 1937, :__________X
any real attention to the cost of transportation within the mine itself; a variety of nondescript cars and track equip** ment was used* Slowly# as operators realized that more efficient haulage systems meant better eoonoroy# a period of modernization followed which resulted in material improve ments in this condition*
Y/hen belt conveyor haulage and mechanical mucking were first introduced* the two operations appeared to be diffi cult undertakings which might require expensive experimenta tion at the very front of operations* Y/hen the shortage of labor# especially of unskilled labor# at a time of maximum demand seriously affected production and it was fully real ized that the issue must be faced# the effectiveness of
*
mechanical conveying suddenly became a live and pressing question in several mining districts and an accomplished
fact in a .surprisingly short time* ^
Now, underground haulage is largely electrified,
/Cutler, Cm R*# Mechanisation and Labor in the Mineral vj Industries: Mines Magazine, p» 117, March 19ljfl«
and even in the gathering of single cars in rooms, the mule is rapidly yielding to the more coordinated mechanical
conveying systems* Use of the cutting machine has almost entirely displaced the old time hand methods by which the
15
miner undercut the seam* For the drilling of shot holes, portable electric drills are now being used* Until recently the backbreaking labor of shoveling the coal from the floor of the mine to the mine car resisted all efforts at mechaniza tion. This last stand of heavy labor is now yielding, and
/Op. olt.. p. 117
...- .... ' ...’ " - — " f ... . ...
machines in great variety — loading machines, power shovels, scrapers, and belt conveyors — are available for this task* The progress of mechanization underground is paralleled by advances in open pit mining on the surface, where huge power Shovels with a capacity of 32 yd to the bite now handle an overburden of 1±2 ft of dirt and rock to win an 18-In* seam of coal* Endless belt conveyor systems carry the coal from the bottom of the pit upward to the surface, to final pro cessing plants*
It is interesting to note that some <ff the older mines found it difficult to employ fully mechanized methods* The reasons are not difficult to understand* Apparently the Chief reason was that the system of mining had been long established* To mechanize meant a change in the system and this was not an easy task to accomplish* It was not very long before new mines and many of the older ones were or ganized on the basis of n100 per cent mechanization*** It Should be mentionedthat,r 100 p<er cent mechanization11 rarely, if ever, means just what it would indicate* To the purist
100 per cent means all, even In a land where the term is much abused* In coal mining the term f!100 per cent mechan
ization” probably includes 10 per cent that is handled by
Mechanization did not solve all the problems of the coal mining industry, but it did enable it to compete with gas and oil, and create new markets for its product.
Mechanization ha% benefited the mineral Industry of this country, and the miners, more than it ha3 the worker in most industries. A half a century ago, mine labor was back straining and very hazardous* With the adoption of new and improved machines, the mine worker*s Job has become
safer, easier, and better paid*
For the mining industry in general, a return to the hand labor methods of 75 years ago, with consequent reduc tion In worker productivity, would lead to the following; shrinkage of markets and lessening opportunities for employ ment and a considerable lowering in mine wages. Today* s mechanization program based on Increased tonnage production with the aid of improved haulage and conveying apparatus is preferable to the above conditions*
The Cost Aspect in Mine Mechanization
The effect of properly planned mechanization can
/Cutler. C* R., Mechanization and Labor In the Mineral Industries; Mines Magazine, p. 117* March 191-i-O*_____ methods that .in no way could be described as mechanized*
17
The tonnage-per-man curve shoots up and the cost curve drops sharply* The net result Is a widening of the definition of the ore* the inclusion of ore up to now unprofitable, and the expansion of mining operations*
In the main, mechanization, by widening the ore horizon, has made possible the extraction and exploita
tion of ores which were formerly too low grade to be worked profitably* It has and is making mineral production more rapid, and in ratio to the discovery of new ore bodies, is
*
rapidly depleting oui* known ore reserves*
In any review of mine mechanization, the essential
- - - ... - -- - r r r ' T- ‘ ■ - * - r - ■■■- - - - - ■ ■ , . . . . — - . - . - r ,
_/Young, L* E*, Mechanization for Greater Productivity and Lower Coats; Mining Congress Journal, p* l6,
January 1948* %
factors affecting costs are;
(1) the effective us© of men, machinery, and working places. It must be ©nqchasized that productivity of the drift, stope, or level during all of the shifts of the day is a factor that deserves most serious consideration*
(2) safety of workmen and charges incident to reduc ing any hazards growing out of mechanization;
(3) depreciation charges on equipment added to reduce the labor and Increase productivity;
(i^.) maintenance labor and supplies; (5) operating labor and power;
V/hile It Is assumed that first consideration must b© given to labor cost, it Is not recognised generally what the trends have been in the last 15 to 20 years In certain
or the other factors that enter Into mining cost, namely:
/Op. elt., P* 17________________________________ _ (1) the prevailing interest rate or cost of money to finance Mechanical improvements j
(2) cost of electricity per kwhr;
(3), cost of explosives per pound and per ton of ore broken;
r
(I4.) the increased rate of rock drilling, which may
be taken as an index of technologic advance.
While the hourly wage rate of miners has increased over 100 per cent in the last ten years, in contrast, dur ing the last 15 years the rat© of interest on industrial loans has decreased at least one-third and has thereby re duced somewhat the carrying charges on mine and plant im provements. The cost of electricity for industrial power has decreased from 5 to 10 per cent per kwhr* The cost per
potmd of explosives has increased in the last year, but ov<§r_
a period of years, because of the improvement in the quality of explosives, the cost of explosives per ton of ore or
rock broken has increased very little.
A recent survey of the use of electric power in
/Op. oit.. pp. 16 and 17
-- -■ i 1 .1 1 if - r— r-i.r nr- - t 1 — r —r - — r ~ tt—m .f—1 n tm 1 ; jt T ‘n t t r.r' .1 r r - -1 .1 1. • t r 1 1r .it- r i r i nr-fi
representative mining districts shows, in general, a
con-4
tinuous increase in power per man employed, per ton of or© produced, and per unit of product, after making due
allow-19
once for Increased depth or mining, increased length of
i 6
haulage, and greater power requirements for ventilation and pumping*
I'/here non-mechanized mines embark on mechanized
pro-9
grams, the magnitude of capital costs greatly increases* Per example, if a small crew of men who contract to drive laterals* drifts, ^ c r o s s c u t s are furnished with the necessary equipment to carry on the work efficiently,
/idem* p* 21
including drills, drill carriage, mucking machines, con veying equipment, fan and tools, this equipment usually, represents an Investment of from $j?,000 to $8,000 per man* In mechanized coal mines, the Investment per face employee for mechanical loading devices Is usually large* The same will hold true for metal mines undergoing mechanized reform,
and because of the varying physical conditions, will be
larger* In some of the completely mechanized mines in __ ■ stratified mineral deposits, the investment per employee
.
... ... .. *
mrnmmmmmmmm■—*—***— *—*w**^*i**w*— mw——i.«W—* ^—*—«*^*«— » m m m m m **—ni— nmn— ,* n«mi —*■***»
/idem* p* 21
<M*mI n * w M > * M i a i
for loading machines and all equipment on the section, exclusive of locomotives, mine cars, and track, is more than $7,000 (on the basis of single-shifting the equipment)*
The Prerequisites for Successful Mine Mechanization
producing property, because the mechanical equipment is ordered and eventually installed, because these and count less other details of the program ,are put into operation, the outcome does not necessarily mean quccess for either mine management or miner.
lie chanization is compounded of many factors, and the endpoint, net profit, is obtained only by careful, long- range planning. It would be highly advantageous to have
as much information on the ore body as possible before mine mechanization takes place* Exhaustive studies of all details
Involved should be mad© before development work is started. In belt conveyor mining especially, much attention should be given to the planning and developing of or ©bodies, and
little as possible should be left to chance. All aspects of the mechanized operation should be gauged and coordinated with strict attention to detail; questionable methods of operation should not be considered* Haturally there Is a limit to which mechanical programs can be applied to the
/Marshall, I* II*, Mechanization in Canadian Gold Mines;
Canadian Mining lournal* vol. 70, no. 7, P* 63, dhly 19ii-9* best technical advantage In any mine; still the maximum
benefits of mechanization will arise only through diligent analysis of operations and procedures* An example of this may be in the daily writing up and analysis of operation reports so that proper planning of moves can be made with minimum loss in tonnage output.
Every machine ^±n a mechanized program should be
/op. clt., p. 61*.
worked to the limit of capacity* To neglect to do so, Is to fail In appreciation of the full meaning of the term
M e c h a n i s a t i o n * !t
"it
It is essential that every •possible phase and factor, both from a mechanical and from a mining standpoint,
/Bigelow* R* S., Progress in Mechanical Loading! Canadian Mining and Metallurgy Bulletin, vol* 2ij., p* 822,
_ i93i._______ __________________________ ;_______ be carefully surveyed and considered in order that the most suitable type may be selected* In addition, and equally important, Is the projection and plan layout devised and resorted to for any particular machine* Many very clever layouts have been planned for concentrated and mechanical mining; quite a number of these have been failures because
of improper selection of equipment* On the other hand, a greater number of failures have, been recorded with
depend-9
able equipment which had not been supported by a suitable and workable plan of mining. Good loading machines and auxiliary devices are operating Inefficiently in mines which were originally projected and developed for hand- loading* It is extremely improbable that a mining plan
/0p« Clt., p, 83k
22
adaptable, without change, for profitable mechanical load ing. Likewise, as the, trend is now being manifested, ex traction with a lower percentage of recovery 1® proving more economical and practical from the standpoint of the
operator. humorous operations are now carrying on profit ably by concentrated methods, quick extraction, and resort ing to recovery of ^ ■ to 75 per cent# Wherever it is
logical and practical to coordinate transportation and load ing, concurrent or continuous mechanical operations should be put into effect*
The progress of successful mine mechanization can be
/MarshallB I. M., Mechanization in Canadian Gold Mines: Canadian Mining Journal, vol. 70, no. 7, P* 62, JUly 19lj-9» aided by the ability and desire of mining operators to
accept wide-reaching changes in today*s mining systems, taking into consideration the difficulties facing older mines with well-established practices.
It Is a well-known fact to those acquainted with the mining profession that the underground metal mining In dustry — of all industries — Is slowest to adopt the
/Smith, M. A*, Tomorrow*s Mining Methods: Engineering y' and Mining Journal, p. 33» March 191-j-O* ' new or unknown. Mining Is evolutdenary. Experience and personal preference, not analysis and logic, usually de
termine choice of the method. Many of the Improvements are forced upon Operators by necessity. The mechanization
23
of the coal mining industry is an example#
To make mechanical conveyor (transportation) mining one wit successful, the mining operators must coiablne practical mining experience with vision and skill#
Miner, as well as mine operator, must become more mechanical minded and must be convinced that machines
/Marshall# I# M#, Mechanization in Canadian Cold Mines: Canadian Mining Journal, vol# 70, no# 7» P« &2,
July 19it-9.__________________ ;____________________ or a system involving the use of mechanical devices will ultimately be to the workman’s advantage# Limited or re stricted output in effort or production has no place in mechanlzation#
In any mechanization program, one of the basic points to be kept in mind Is that upon the installation pf mecha nized equipment, especially conveying equipment like belt conveyors, great care should be taken in the choice and training of machine operators. The highest efficiency In machine operation can only be made possible by the training of the men who operate and supervise the equipment, and by detailed Instruction on the care and maintenance# In con* conveyor raining, It is most important that crev/s be tralned to work as a unit, and that the foreman be well indoctrln*. ated In fundamentals of belt control where belt systems are in operation* All this demands careful, intensive super vision on the part of management when instituting mechanized programs#
2 k
Complete mechanisation and modernization of mines
I
has, in many sections of the country, demonstrated that machinery is malting the mines much safer and is reducing man-hour losses to the minimum, which in turn effects a considerable saving in compensation* The elimination of raises, one of the big hazards of mining, and the improved
supervision owing to the centralization of operations ,
/Smith, M* A*, Tomorrow^ Mining Methods: Engineering and Mining Journal, p* 33, March 19ilQ«
will materially reduce accidents* The mining industry is beginning to realize the safety to men and property re sulting from mechanization* As more centralized, eoncen- trated supervision is exercised, and more mechanized
equipment is put into operation, safety should receive a still greater impetus from efficient supervision*
Finally, successful mine mechanization depends on the genuine desire of mine management to reduce the effort
/
of labor by so called '’labor-saving11 devices or gadgets (photoelectric cells, weighing machines) and to effec - tively use power wherever possible instead of manual labor*
Mechanical devices and innovations are a vital factor in the application of power and machines to mining.
EVOLUTION OF BELT CONVEYOR TRANSPORTATION
The earliest reference to the use of belt convenors
Hetzel, F* V#., and Albright, R# Km, Belt Conveyors and Belt Elevators, 3 rd# ed#, p* 6, New York, John Wiley p
& Sons, 19lll•_____ ________ *________________ ■
-published in Philadelphia in 1795* This describes and illustrates a flat belt receiving material on Its upper
... '" " ~ * d
over two pulleys in a case or trough# ,f These first crude belts engaged in carrying clay ores and grains# \7hen such
conveyors were used for hard and gritty substances, the belt did not last long# In clay conveyors, the clay studk to: the sides and bottom of the trough, hardened there,
and wore out the b " ‘ ' "ly*
In 1868, Lyster, an English engineer, described to
/Hudson, Wilbur <3>, Conveyors and Related Equipment,
2nd ed#, pp# 185-186, New York, John Wiley & Sons, 19k9» the British Engineers Society his work on conveying bulk materials by endless belts make of two plies of canvas with
Ing idlers and no doubt found,. It impossible to prevent the In American practice is in Oliver Evans’ filler’s Guide”
trough-26
belt from centering on one roll or the other* He devised and used the three-way tripper and the revolving cleaner brush; in fact, Lyster seems to have invented many or
t /Op. clt., p. 185
the features of the belt conveyor of today* In this country Webster carried on extended experiments with belt conveyors
for handling grains* In the early 1890 * s Edison, as a
/idem, p« l8ff
result of difficulties with flight conveyors handling ore, built several cotton—belt conveyors with continuous skirt boards along the carrying run to keep the load from rolling off the belt# Ihomas Robins, apparently independently of
/idem, p* I8g _______ ^ ^ __________________
Lyster, followed similar lines of investigation and elimin ated the difficulty Inherent in the two-pul ley troughlng idler by adding a horizontal pulley just back of each in clined pair* He followed this with the Invention of the three—in-llne-unit idler and prevented oil from the
bear-/idem, p* 186
Inga from leaking onto the belt by means ofdiollow roll shafts with grease cups on the outer ends and radial duets along the shaft, incidentally securing the advantage of exuded grease seals to prevent ingress of dirt into the
bearingi# Robins’s work in belting led him to construct bolts that had two or more plies with rubber covers# Then he reduced the thickness of the tinder side and increased
it on the carrying side to secure longer life* About 1896, he originated the atepped-ply belts, in which the
/idem, p* 186
plies stepped off toward the center with corresponding increasing thickness of rubber in the central zone#
Hudson, in tracing the development of belt conveyors
/Hudson, Wilbur (**, Conveyors and Related Equipment* ^ 2nd ed* , pp# 185-180» Hew York, John Wiley & Sons, 19k9♦ toward the end of the 1890*s states s
Bolt conveyors were increasingly used about this time, competing with the heavy double-strand flight conveyors then common# Five-pulley troughing idlers were tried and were abandoned when it was found that the additional cost was not accompanied by ad ditional life of belt* The manually pro pelled tripper was made self-propelled and self-reversing by Humphrey, the convenience of operation being greatly Improved thereby# Finally came the two great forward steps: anti-friction bearings with labyrinth grease seals, and vastly improved rubber-belt con struction*
Through the years numerous refinements were made on the conveying mechanism, and the application of a method for handling tremendous quantities of materials quickly, cheaply, and safely, and without noise or fuss started In the early 1920*s*
first multi-mile conveyor system at its Colonial Dock installation at East Roseoe, Pa# The conveying system has 3ip apron feeders taking coal from a 1250-ton bln and delivering It to a 60—in* belt which In turn discharges to a series of nineteen Jf8—In* belt conveyors run at 500 fpm and of lengths ranging from 321 to 2Hj39 ft* The total lift in the run of 22,930 ft is 357 ft* The conveyor was designed to carry 9000 tons of coal in 8 hr underground * to the loading station on the Monongahela River* In the first eleven years since 1921^, the conveyor system has carried 29 million tons* Careful mine records kept over a period of years have shown that, instead of taking more power than an equivalent electric haulage system, the belts take less, the depreciation is less, and the final cost of transferlng coal to the river Is below the original estimate.
The coal industry adopted conveyors as a major part of their mine mechanization program helping to make possible profitable recovery of low seam coal*
The iron ore Industry in Minnesota, being faced with rising costs for recovering ore from deepening open pits with locomotives and cars, changed to conveyors to get the
ore out economically* This has been demonstrated most con- vlncingly by the Oliver Iron Mining Company, which has
evolved and placed into operation a new method of open pit mining which enables them to mine the ore remaining in
their Spruce Pit Min© at Eveleth, Minnesota*
company was faced with the problem of laying the tu*aek from the mine floor to the surface ip such a manner that It doubled back on itself twice* (This was due to the pit’s irregular shape* ) In other words, the ore trains had to re verse their direction ("switchback”) two times before they reached the surface* Two switchbacks were bad enough, but
*
It was plain that a third switchback would be required If operations were to be carried deeper*
The new method of open-pit mining, based upon the use of belt conveyors, will make it possible to mine the large tonnages of ore tied up in the permanent railroad track
benches* The Inauguration of this new mining principle also discloses the economy of ^rhlch belt conveyors offer in re placing heavy railroad equipment at mines, requiring large expenditures for the long track system, and benches around the periphery of the pit, together with numerous cars and locomotives* A belt conveyor system, 00 ft long, conveys 750 long tons of ore per hour, 500 ft per minute at Spruce Min© over a not vertical lift of 386 ft, from the ore de posit in the pit, directly to rail shipping pockets 50 ft above ground level* Nine separate conveyors make up the , 1^500 ft river of ore, each conveying and elevating the ore to the next conveyor, until it is carried across the last drive pulley into the 500-ton, 50-ft-high shipping pocket,
. ^''
from where ore is drawn off into cars for rail shipment , to Lake Superior ore loading docks* Seventy per cent of
20 degrees permit an attendant to service the system with out undue strain* This underground portion of the belt conveyor system travels in an entry ^driven mostly in ore, following closely the bottom rock of the pit* The 30 per cent of the system above ground is completely housed in a steel gallery* The ore is fed tp the belt conveyor system through 120-ft-deep shafts* In the ore body now being mined, Oliver has sunk three shafts from the floor of the pit to the underground belt system* In two of these shafts, ore is scraped to the shafts with drag lines operating up to 700-ft radius from tower excavators (the first to be used in iron mining), which extend upward 100 ft above the top of the shafts* Ore is carried to the third shaft by 20-ton trucks, loaded by electric shovels* In the top of each of the three shafts, pan feeders regulate the flow of ore Into screen and crusher, where ore Is crushed to
3 l/2-in* maximum size* The sized ore drops upon the man ganese steel feeders just above the belt conveyors which start the ore in its river-like stream on the belt at re quired capacities*
The belt system, in combination with the excavating
r
towers0 shovels, and dump trucks, has resulted in more
economical removal of ore from the Spruce pit* At the same time, it means more Complete removal of ore* When ©re is moved from a mine by locomotives and cars, it Is necessary
to cut benches in the sides of the pit for the railroad
*
With the conveyor system there Is no need Tor benches along the edges of the mine* Because all the ore finds its way to the belt conveyor system, more complete extraction from the overlying ore body is possible* Figures 1 and 2 demon strate the use of belt conveyors in this particular instal lation*
^ i .. .Iir Jf
In open-pit mines on the Me sab 1 Iron Ranges in
/Holt* G* J*, Open-?it Mining on the Iron Ranges-19ij-9 * Mining Engineering, vol* X87, no* 1, pp* 48-50* January
„ : _______________________
there were only six belt conveyor Installations having a total length of 911$ ft* In 19l}-9 there were 26 conveyors, having an aggregate length of 3^,965 fb# transporting or©
from the pit floor to surface* , In addition,' in 19^9 there were two conveyor systems transporting stripping from the
*
-pits to the dumps, having an aggregate length of 13,851 ft* A summary of available data shows the following com**
Top* cit*V P* l\B — ... —
pariaons between working installations In 19I4X and 19l|*9 * Increase 19i|.9 19l|l 19i|9 over 19^1 Humber of con veyor installs- 6 28 h-33% tions Total length of Conveyors used 9110 lf.6,816 5 1 W
The application of conveyors in underground metal mines
**
has not been nearly so extensive as in coal mines* Coal mine conveyor systems have become more standardized, as coal
mine physical conditions and concentrated large tonnages are more or less similar, whereas they vary quite widely throughout the metal mines, for each mine presents a differ-ent problem* No common conveyor sysbera can be applied to a ‘group or mines existing in the same field, considering the
varied conditions*
As to the application of belt conveyor systems in metal mines, they are usually laid out with the mine offl«* cials to suit their particular conditions* These conditions vary from mine to mine and are determined by: mining system,
size of material to be transported, tonnage, capital, charges,
*
appropriation available, coordination with present haulage system, and other local factors* In evolving a mechanized belt conveyor system there is exceptionally close collab*** oration between mine officials and the field engineers of the conveyor companies*
An example of this is the Iron Range in Minnesota and Michigan* For the past two or three years field engineers have been working closely with the Iron mines in changing their mining systems from open pit to underground opera*** tlon* The depletion of the surface orebodies necessitates their going underground*
The underground mines on the Range are being opened generally with top slicing methods* Top slicing Is a por tion of the stoplng me'thod dealing with the mining of ore under the general classification of caving systems*
In top slicing the ore Is removed by excavating a series
/Jackson, C* F*, and Gardner, F* D*, Top Slicing, Miners1 Circular f>2: Bureau of Mines, pp» 22-23* 1914-5* _____ of timbered slices, one alongside the other, beginning at the top of the ore body and working progressively downward* The slices are caved by blasting out the supporting timbers, bringing the capping or overburden down on the bottoms of the slices which have previously been covered with a floor or mat of timber or wire fencing* The method is applicable to mining soft, weak ore that will stand unsupported for only a short time, even over spans of a few feet, and that is overlain by a capping that will break and cave as soon as the support Is removed, tightly filling the space former** ly occupied by the ore and leaving no open holes*
The ground Is heavy with narrow drifts* The ore varies from sticky, slimy paint-rock to hard lumpy magnetite* Dur ing this experimental stage, the mine operators and the con veyor field engineers must continually vary their plans and design to fit the needs of the transporting problem* Usual ly Individual conveyors, and not multiple conveyors form a system, where a single conveyor transfers ore from the scraper to an ore chute or a single conveyor pulling from ore ^chutes to a pocket where thy© ore is ear hauled*
Slowly, and in the face of continual opposition from both mine operator add miner, the belt conveyor principle in mineral mechanization has spread, being used In metal and non-metaliie haulage operations* The Potash Company
of 'Asterloa has taken a predominant stand in the mineral
/Haworth* R* G# , Edmunds# J* # Knill, R* R*, Belt Con*-Mayors for Gathering Haulage: Mining,Congress Journal# pp« 26*-39; 4l« October 19&9*
field In utilising belt conveyors as a logical and profit** able way of transporting underground ore* At one of their properties in Hew Mexico# a decision was made in 194-7 to
substitute belt conveyors for gathering locomotives and oars in one extraction panel* What factors prompted this kind of unorthodox thinking# leading to a more profitable
The potash-bearing bed being sained is situated at a
/op* 'citV#",pr*IT2 6 r r i r "" 11 r r " " ' *n'~
*
depth of 700 to 1100 ft below the surface* Several hundred feet of salt beds lie above and below the sylvinite bed which is an intergrowth of potassium chloride and sodium r chloride crystals* The commercial portion of this bed ex
tends over several square miles, requiring an extensive underground haulage system* Haulage entries are driven in the ore horizon# e xcept where main entries are regraded to maintain a grade of not over 3 per cent* Grades in cross entries and in extraction panels are as much as 12 per cent* As a room and pillar system is used, and all ore is blocked out in 1100 x 1800-ft panels between the chain and barrier pillars, haulage within the panel is necessarily up and down the grades created by nature*
Rough terrain was the first compelling factor
__7ldexn, p. S? _________________ _
suggesting that belts would be superior to locomotive haul age# They would eliminate over one mile of track in each pan©!* would travel up and down grade with no difficulty* and would not get off the track# Since some panels contain ed ore which was relatively thin* under 6 ft* it would have been necessary to brush (break down) salt from the back or
the bottom in order to maintain headroom for locomotives and loaded cars* Cost per panel for Installation of three
_i/ldsra, p. 38
g.MTBI'Jg'f. . - .. ---, - - _ - r... . r_,... ... t, , T r .
tracks with the grading and brushing required ranged from $20*000 to $30*000* not including the cost of supplies and labor for salvage and removal of the track when mining was completed*
Each belt is approximately 800 ft long and will be installed to discharge Into cars In one cross entry where much attention has been given to layout of the double track
and crossovers* Since the company was expanding the pro ductive capacity of the refinery and the mine in 191^8* it
*
was decided to substitute conveyor belt3 for the old type of gathering haulage in the new panel operation which would be needed to produce the additional ore*
After blasting* the ore is loaded by a caterpillar- mounted loading machine Into shuttle cars# The shuttle
36
cars are driven to one or three loading stations where _ /
they are discharged onto the belt* Ore is dumped from
the shuttle car by driving on a ramp to a point where the ore will Tall on an inclined plate, from whence the material slides onto the belt* The plate is hinged in order that it may be swung out of the way when any of the other loading
stations is being used* The loading station aprons are also hinged for the same purpose* Belt speed is a little over 300 fpm* This allows the shuttle car operator to discharge the load in approximately half a minute* It is relatively easy to alter the shuttle~car discharge speed by choice of the proper sprocket* so the operator does not have to start and stop the conveyor In the shuttle car in order to pre vent overloading of the belt#
At the belt head one motorman Is employed for operate Ing the belt and loading ore into mine car3* Remote con trol for a hoist or a locomotive Is installed near the belt discharge point* The capacity of the shuttle cars is
the same as that of the mine cars* so the motorman moves _ y
the trip slowly as the belt is discharging* When the car
/idem* p* 28
is. full and no more material is coming on the belt* he moves the next empty car under the belt head* Since there is a minimum of 30 seconds between discharge of one shuttle car
37
and th© succeeding one, there are few spills, and no divert ing or transfer chute is required at the belt head* Trips are loaded for the main line motor which hauls the ore to the dump at the shaft. The net result is that one man can operate the gathering haulage system vfriere four men were required before on two locomotives* Men replaced by this
equipment wore transferred to shuttle cars to^ provide
greater capacity on that end of the operation or were trans ferred to development*
Panel crew efficiency has been increased about 20 per
r'/idemV ;p*' III ' '
cent* Under the production bonus system, half of the in creased efficiency is translated into higher earnings for
the entire group participating in the bonus*
Figures 3 and if. show the contrast between a standard panel for track haulage and a model panel for belt conveyor
/idem* 2? and 28
mmmmM
T - 7- m r r tt ■»,- r - - - i . “ t t i» 11 r "nr-i^rr— a. - . , -r-.n r«r ,«j ..
haulage as brought out in the foregoing paragraphs*
In this case of applying belt conveyor to or© haulage, the belts have proved superior to locomotive haulage where steep grades are encountered* The belts are of great ad vantage where the potash or© Is less than 6 ft thick, since much handling of waste Is eliminated* To overcome the above conditions, belt haulage was adopted*
THE PRACTICABILITY OF BELT CONVEYORS
Mining In Its simplest form consists primarily of ex cavating, loading, and transporting ore, complicated local ly by various physical conditions of dispersion of mineral isation, character of hanging and footwall, and dip and width of lode* Each mine official must determine for him
self how his own particular mine can tise a mechanical aid such as a belt conveyor, utilizing' It to the best extent possible* By mechanisation and the use of belt conveyors,
a situation can result in a reduction in the number of workers for a given tonnage, or a greater tonnage for a
t
given number of miners*
Belt conveyor haulage can be used to advantage where proper conditions exist* Advantages are particularly
apparent when development can be planned sufficiently In advance of exploration to permit installation of belts as part of the development of program and where the systems
are extended to include haulage in stopes as well as main entries*
There has been.Increasing interest in haulage by belt conveyors from producing sections to the shaft bottom, and
f .
much attention has been given to the possibility of Install ing belts in slopes constructed as haulage ways*
In metal mining, as well as coal mining, there appear to be substantial economies in this 'latter type of installa tion where there is sufficient daily production and re serve tonnage to warrant the Investment* As a result of the Improvements made in driving slopes on a 15-to 18-degree pitch, with a corresponding^reduction In the cost of con struction, belt conveyors are being used instead of
/Young, L* E*, Mechanization for Greater Productivity and Lower Costs: Mining Congress Journal, p* 16,
January 19^8, i .
hoisting in vertical shafts or slopes*
In coal fields belt conveyors have been put to prac tical use where full seam mining is practiced. In certain bituminous coal mining districts, where there are impurities
in the coal seam or where th£re may be a stratum of pver- lying material that Is difficult to support, it has been found desirable to load the impurities with the coal, and remove the impurities and extraneous material in cleaning plants located on the surface# As much as 30 to 35
cent of the material that is loaded may be discarded In cleaning plants# Inasmuch as It is necessary to put the
i
coal through a cleaning plant in any event, It has been found economical to take full advantage of mass-production methods in mining and underground transportation, and build
a* larger cleaning plant than would be necessary when an effort is made to keep some of the refuse underground*
Mines with seams of coal I4. ft thick and more provide
/Robinson, C,, Underground Belt Transportation: Mines and Metallurgy, P« 535>* November I9l|l#
virtually an untapped field of application for belt conveyors In normal operation, every Item of cost, either capital or
4
operating, is reduced as the seam beeomes thicker# The de~
*
pendability of belts assures almost corslet© freedom from haulage delays, which is reflected directly, of course, In decreased cost, and indirectly In the improvement in morale, for haulage delays are among the most demoralizing delays around a mine# Also, once a belt is Installed, with a com petent overseer in charge, the higher management is free
, /op. Clt.. P.' 535
JLjfl ,'f . . - . .j ,.||f ■T .r -.rr^ 1 x f - ... , r . . - . .. _ _
to spend all of Its time on other phases of mining, instead of constantly cheeking and correcting the underground haul
age system* Belt conveyors are particularly adaptable to the principle of small loading crews with the main emphasis on tons per man, rather than the more common practice of large, crews with the main emphasis on tonnage per loading unit# Almost without exception, mines that have carried out this principle in Its entirety are producing the cheap est coal in their respective fields*
A valuable characteristic of belt conveyors is that
/idem. p. £36
k x
At a mine in southern West Virginia* where in one area there are grades of 20 per cent up* and down combined with tender roof and a variation in height of coal from 30 to 72 In** the overfall cost is essentially the same as in other sections of the same mine with excellent conditions and moderate uniform grades*
Economy of operation is only one of the many advantages of belt conveyor transportation* It has long been an ac- knowledged fact that belt conveyors provide the lowest-cost means for moving large volumes of bulk materials* but it wqe not until 1932 that belt conveyor engineers endeavored
to adapt their established methods to the particular needs of the metal mining industry*
Open pits once considered flworked-out" by previous roethods are being profitably developed with belt conveyors which require no spiraling ledge for transporting ore t© the plant* No roadway or road bed Is needed with belt conveyors* a feature which not only saves on maintenance but permits far deeper excavation befpre floor space becomes too limited for operation* And# whan belt conveyors are installed* all of the valuable ore* formerly required for the spiraling ledge# may be fully recovered without the necessity of re moving additional overburden* With the national accent on m&xirmlm tonnage — * quickly this gives belt conveyor handling a tremendous advantage that cannot be ignored*
