xt7v6w96916t https://exploreuk.uky.edu/dips/xt7v6w96916t/data/mets.xml  Leong, Yau Sing, 1899- 1940 Other contributors: National Research Project on Reemployment Opportunities and Recent Changes in Industrial Techniques (U.S.); United States. Bureau of Mines. xvi, 260 p. : ill., 1 map ; 26 cm. Mineral technology and output per man studies ; report no. E-12. UK holds archival copy for ASERL Collaborative Federal Depository Program libraries. Call number FW 4.7:E-12. books  English Philadelphia, Pa. : Work Projects Administration, National Research Project in cooperation with Dept. of the Interior, Bureau of Mines This digital resource may be freely searched and displayed in accordance with U. S. copyright laws. Maryland Works Progress Administration Publications Technology, Employment, and Output Per Man in Copper Mining by Y.S. Leong [et al.] text Technology, Employment, and Output Per Man in Copper Mining by Y.S. Leong [et al.] 1940 1940 2015 true xt7v6w96916t section xt7v6w96916t M;      3 I   I w  I 
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FEDERAL WORKS AGENCY E
WORK PROJECTS ADMINISTRATION Q
F. C. HARRINGTON CORRINGTON GILL ji
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NATIONAL RESEARCH PROJECT g
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Reemployment Opportunities and Recent Changes
in Industrial Techniques _  
DAVID WEINTRAUB i
Director  
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UNITED STATES DEPARTMENT OF THE INTERIOR E
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  ‘ MINING COPPER ORE WITH A POWER SHOVEI. AT BINGHAM CANYON, UJAH {_
5_ t_The exploitation of larg;2—j:0nnage, _l<>w-grade ore deposits and the evolu- Ip
Y _ Iorgho ow—cost surface mInI_ng techmques have been Impo_rtant developments  
I IU e copper Industry durIng the past 30 year_s. RaIlroad—type steam  
r . shovels runnnng on tracks were fIrst used to strIp overburden and to load
,. ore,tbut they have been superseded by full—revolvIng, caterpIllar—mounted
Ii I e QCIFIC shovels. Power shovels have_ been Important IH lowernng labor
  requI_reme_nts per ton of copper ore mlned. The shovel itself has been
I5_ steadIly Improved and now requIres much less labor for maintenance than
It I formerly. At underground mnnes there has_been an _IncreasIng tendency to
II; adopt smaller, specIal—type shovels as an aId to effIcIency.
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. TECHNOLOGY, EMPLOYMENT, AND OUTPUT PER MAN  
A IN coppma MINING  
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by 5
  Y. S. Leong, Emil Erdreich, J. C. Burritt,  
 § O. E. Kiessling, C. E. Nighman, and  
  George C. Heikes {
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' wOm< PROJECTS ADMINISTRATION, NATIONAL RESEARCH PROJECT  
In cooperation with  
DEPARTMENT Or Tm INTERIOR, BUREAU OT- MINES  
Report No. E—12  
` PhzladeL¢>hia, Perznsylvama  
February 1940  
 
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  THE WPA NATIONAL RESEARCH PROJECT ;
  ON REEMPLOYMENT OPPORTUNITIES AND RECENT CHANGES V
§ V IN INDUSTRIAL TECHNIQUES  
  Under the authority grantedby the President In the Execu-
  tive Order which created the Works Progress Administration,
  Administrator Harry L. Hopkins authorized the establishment
I- V of a research program for the purpose of collecting and ana- ;
}i lyzlng data bearing on problems of employment, unemployment,
§V' and relief. Accordingly, the National Research Program was _‘
  established In October 1935 under the supervision of Corrington  
  Gill, Assistant Administrator of the wPA, who appointed the  
  directors of the lndivldual studies or projects.  
i The Project on Reemployment Opportunities andRecent Changes A
c~ in Industrial Techniques was organized In December 1935 to
V 1nqulre,with the cooperation of Industry, labor, and govern-
i i mentaland private agencies, Intothe extentof recent changes
` In industrial techniques and to evaluate the effects of these
  I changes on the volume of employment and unemployment. David
Ei. Weintraub and Irving Kaplan, members of the research staff
  of the Divlsionof Research, Statistics, and Financewere ap-
  pointed, respectively, Dlrectorand Associate Directorof the
  Project. The task set for them was to assemble and organize
  the existing data which bear on the problem and to augment
iQ" these data by field surveys and analyses.  
  To this end, many governmental agencies whlchare the col-
¥ lectors and repositories of pertinent lnformatlonwere Invited
  to cooperate. The cooperating agencies of the United States
  Government include the Department of Agriculture, the Bureau
qi of Mines of the Department of the Interior, the Bureau of
  Labor Statistics of the Department of Labor, the Railroad  
  Retirement Board, the Social Security Board, the Bureau of J;
I l Internal Revenue of the Department of the Treasury, the De- A
  partment of Commerce, the Federal Trade Commission, and the A
  Tariff Commission. »
? , The following private agencies joined with the National
  Research Project In conducting special studies: the Indus-
ii » trial Research Department of the University of Pennsylvania,
{Q the National Bureau of Economic Research, Inc., the Employ-
i'- ment Stabilization Research Institute of the University of
  Minnesota, and the Agricultural Economics Departments In the
  Agricultural Experiment Stations of California, Illinois,
  Iowa, and New York.
  Since September 1, 1939, the Project has been sponsored
g by the National Resources Planning Board, Executive Office ’
  of the President, washington, D. C.
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I FEDERAL WORKS AGENCY  
I WORK PROJECTS ADMINISTRATION  
{ 1734 New voRr< Avenue Nw.  
, wAsHrNGroN,¤.c. I
5 e.c.HARR¤NGroN I
COMMISSIONER OF WORK PROJECTS  
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` February 20, 1940 g
I Colonel P. C. Harrington 1
_; Commissioner of Work Projects i
é Sir: I
Q I
° There is transmitted herewith the report entitled {
_ Technology, Employment, and Output per Man ln Copper E
Mining. Although the copper-mining industry employed I
fewer than 18,000 workers in 1938, its product is an g
essential, widely used industrial raw material and an I
indispensable war material. The industry*s history »
affords, moreover, an exceptional picture of the im- _
pact of changing production methods on labor produc- I
tivity and employment opportunity. 1
` In terms of ore produced per man-shift, produc- I
g tivity increased from 0.6 ton in 1880 to 6.3 tons in Q
1928 and to 8.8 tons in 1936. Because the quantity of g
copper yielded per ton of ore has declined over the I
decades as poorer ore deposits have been tapped, the é
rise of productivity appears somewhat less rapid when §
measured in terms of recoverable copper. é
F Thus productivity has increased steadily despite I
growing natural handicaps. These productivity in- I
li creases were made possible by technological advances §
I in mining practice and in ore dressing. Production, I
however, has not kept pace, and employment has there- é
fore declined. In 1929 the copper output was at prac- §
tically the same level as in 1916, but only 37,000 men Q
were employed as against 61,000 in the earlier year. I
In 1936 copper production was about 60 percent but I
'I
employment was only about 38 percent of 1929. Q
y The industry's developmenthas involved the shift- I .
ing of production centers in response, on the one §
hand, to depletion of deposits in the older producing §
’ areas and, on the other hand, to new mining and ore- g
concentration methods that made possible the exploi- I
tation of low-grade deposits in the West. Thus in I
Michigan, which once was the leading copper-producing §
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Q State, the output of a group of large mines declined Y
E from 225 million pounds in 1917 to 186 million in
§ 1929 and to 96 million in 1936. Employment fell off
{ even more rapidly, from 11,886 men in 1917 to 6,660
§ in 1929 and to 1,838 in 1936. In Arizona, now the
§ largest copper producer, the 1929 production of 819
if million pounds was 35 percent above its 1917 level,
i and 1929 employment was slightly lower than in 1917 -
i. an average of 11,246 as against 11,909 men. In 1936, i
{T however, employment totaled only 3,696 men, for pro-
Q duction was about half as great as in 1929 and produc- V
§ tivity meanwhile had been greatly increased. g
g Something of what shifting centers of produc- l
Q tion have meant to the older centers can be seen in Q
4: the familiar problem area of northern Michigan where
= copper resources have recently reached a point of
Q_ serious depletion. In two such counties in the Lake
{ Superior region population declined by almost 40 per- ’
E_ cent between 1910 and 1930. The migration has can-
tinued since then; yet it was estimated that in 1936
§ as many as 3,000 copper miners and their families were I
ii stranded in these two counties with little opportunity
i` for reemployment. They have constituted an important
? relief problem. _
L The outlook for increased employment in copper if
,_ mining, as in most mineral industries, is not bright.
Y Intensification of the European war would be expected
Q to increase our copper exports, and this country's
g4 armament program will call for an increased amount of
$4 copper. Output for other than armament purposes is
ii not expected to be much above the 1936-37 level in the
J` next 2 or 3 years. Over a 10-year period, however,
_ the growth of population, the development of new uses
1} for copper, and further growth of the electrical in-
5 dustries [which now account for about one-half of do-
ii mestic consumption) point to some increase in copper I
i· production. However, productivity appears certain 6
i, to increase further with continued adoption of im-
{ proved techniques and with continuation of the shift
;. in production to deposits having a higher output per
g`. man-hour.
fl.
gi Respectfully yours, y
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g Corrington Gill
E Assistant Commissioner ·
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C O N T E N T S é
Chapter Page g
PREFACE ...................... xiii g
ACKNOWLEDGMENTS .................. xv Q
I. INTRODUCTION ................... 1 g
E
II. MAJOR TRENDS IN THE COPPER—MINING INDUSTRY, g
1880-1936 .................. 5 ;
_ Changes in production, employment, and output 4
g per worker ................. 5 E
T Technologie advances .............. 8 L
. Progress in safety ............... 15 §
Geographic shifts in production ......... 16 E
Integration of the industry ...... . .... 20 {
III. OPEN—CUT MINING .................. 22 i
Description of operations. ........... 24 A
Growth of open—cut mining ............ 26 ‘
Growth in production ............. 27
Changes in employment ............. 29 5
Rise in the output per worker ......... 31
Technologie advances .............. 32 i
Drilling and blasting ............. 33 —
{ Drilling .................. 33 f
Blasting .................. sv  
Loading .................... 38 Q
Transportation ................ 48 n
Planning . ................... 57 Vg
Increasing difficulties of open—cut mining . . . 62 5
Changes in physical conditions ........ 62 §
Changes in the grade of ore .......... 63 Q
IV. UNDERGROUND MINES ................. 68 i
Production, employment, and output per man . . . 68 é
Relative importance of mining methods ...... 76 {
Increasing mining difficulties ......... 81 }
Yield of ore ................. 82 g
Increasing depth .......... . .... 83 §
Improvements in the art of mining ........ 85 1
Selection of mining methods ....... . . . 85 Q
Advances in mining methods .......... 88 g
Open stoping ................ 88 E
l Shrinkage stoping .............. 91 Q
Cut-and-fill stoping ............ 93 i
Square-setting ............... 96 E
Caving ................... 97 j
Summary ................... 105 E
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  vi i i CONTE NT S °
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i Progress in mechanization ............ 105
f. Drilling and blasting ............. 105
Q Drilling .................. 106
Q ° Blasting ......... . . . . . . . . . 112
i· Mucking and loading .............. 114
ip Transportation ................ 121
i- Haulage ................... 121
{ Hoisting . . . . . . . . . . . . . . . . . . 133
¥* Mine drainage ................. 140
§ Mine supports ................. 146
i Ventilation .................. 150
Q Summary and conclusions ............. 159
5.
E V. ORE DRESSING ................... 167
i VI. SOME EFFECTS OF TECHNOLOGIC CHANGES ON THE MINERS 179
< Number and location of employment opportunities 179
Skill and age requirements ........... 181
in Wages and hours ................. 183
Employment tenure and economic security ..... 185
J · Safe ty ..................... iav
` Workmen's compensation ............ 192
&}_ VII. FUTURE OUTLOOK .................. 194
{ Copper reserves ............... . . 194 i
` Technologie advances .............. 197
L Output per man ................. 200
1 Production . . . . ............... 202
y Foreign markets and foreign competition .... 202
Y Secondary copper ............... 203
1 Consumption requirements ........... 204
f_ Employment opportunities ............ 210
1. Appendix Q
+1  
y TABLES ...................... 214 S?
I, Z"
{ i MAP, CHARTS, DIAGRAME, AND ILLUSTRATIONS
{Z` Figure
i_ Mining copper ore with a power shovel at ·
i Bingham Canyon, Utah ........... Frmwispwce
Q, 1. Production, employment, and output per worker at _
Qj copper mines, 1880-1936 ............. 7 t
gi 2. Copper production classified by mining method,
g 1880-1936 .................... 1O
g 3. Progress in mechanization of copper mines,
§· 1880-1929 .................... ii
i 4. Production and yield of direct-smelting and mill-
E ing copper ores, 1880-1936 ........... 17
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CONTENTS ix jg
MAP, CHARTS, DIAGRAMS, AND ILLUSTRATIONS-Continued i
Figure Page j
5. Copper production classified by major producing Q
States, 1880-1936 ................ 18 ,
A
6. Copper production classified by principal mining j
district, 1880-1936 ............... 19 .§
7. Large-scale operations by companies that smelt 3
copper ores and fabricate copper products are g
characteristic of the copper industry ...... 21 I
8. 0pen—cut copper mine at Bingham Canyon, Utah . . . 23 E
9. A shift from surface to underground mining is L
sometimes advisable ............... 26 i
10. Growth of open-cut copper mining, 1910-36 ..... 28 {
11. Production, employment, and output per worker at é
open-cut copper mines, 1914-36 ......... 30 E
12. Stripping ratio and output per worker at open-cut §
copper mines, 1914-36 ....... . ...... 31 Q
13. Drilling at open-cut copper mines ......... 35 é '
14. A remodeled shovel loading ore at an open-cut cop-
per mine .................... 39 ¥
15. Relatives of shovel performance and output per man
at one open-cut copper mine, 1924-33 ...... 48 V
‘ 16. Trans orting waste at an o en-cut co er mine with E
g P P PP _
a combination trolley storage-battery locomotive 49 ‘
‘ 1
17. Truck haulage in an open-cut copper mine ..... 57 §
18. Yield of ore at open-cut copper mines, 1910-36 . . 64 §
19. Copper content of ore concentrated at mills of g ‘
Utah copper mine, 1911-35 ............ 66 g
20. Ore, men, and materials move through the shaft at §
an underground mine ............... 69 Q
· 21. Production, employment, and output per worker at Q
_ underground copper mines, 1914-36 ........ 70 Q
A 22. Production of ore and output per worker at under- Q
ground copper mines, by mining method, `
1917-36 ..................... 72  
23. Production of copper and output per worker at g
underground copper mines, by mining method, 5
· 1917-36 ..................... 73 ,
24. Employment at underground copper mines, by mining é
method, 1917-36 ................. 74 Q
Q 25. Distribution of copper produced at underground 3
copper mines, by mining method, 1917-36 ..... 76 {
26. Percentage distribution of copper production, by i
mining method, 1917-36 ............. 78 E
27. Production and output per man at Michigan copper g
mines, 1917-36 ................. 80 Q
28. Yield of ore at underground copper mines, 1917-36 62 E
E
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  r
  x CONTENTS
Q ,
Q MAP, CHARTS, DIAGRAMS, AND ILLUSTRATIONS-Continued .
§ Figure Page ,
g` 29. 0pen—stope methods of copper mining ........ 89 ;
i 30. Shrinkage method of copper mining ......... 92
i‘ 31. Cut-and-fill methods of copper mining ....... 94
i 32. Square-set methods of copper mining ........ 98 ,
i 39. Caving methods of copper mining ...... . . . . 102 5
i` 34. An important ste in metal roductionis the break- A
1 P P
{ ing of ore by drilling and blasting ....... 107
T 2
5 35. Development work underground ........... 111 j
i 36. The use of mechanical loading machines in under- 5
; ground mines has increased ........... 116 l
· 37. A scraper loader in a western copper mine ..... 120
E 38. Efficient underground transportation requires that
  `
@~ cars be unloaded quickly ............ 128
`_ 39. Moving large tonnages to the surface requires
Yp efficient hoisting plants and techniques . . . . 139 ‘
j 40. Increased use of mechanical ventilation devices
%~ was necessary with the expansion of operations
P" at underground mines .............. 155
§; 41. Modern concentration methods require that ore be _
{‘j crushed and ground until the largest particles
{ resemble fine sand ............... 168
_ 42. Typical large copper concentrating mills use flo-
i tation cells .................. 172
% 43. Percentage of copper content of ore recovered at
y. typical concentrators, 1911-35 ......... 174
i 44. Concentrates must be dehydrated .......... 177
Y 45. Barring down loose rocks in underground working
‘ . places ..................... 190
. 46. Accident rate at copper mines, 1911-36 ...... 191
F 47. Estimated copper reserves and quantity of copper §
i extracted through 1936, by district ....... 195 6
§_ 48. Estimated use of copper in the United States, by
% principal use, 1919-37 ............. 206
{ 49. Miners "rustling" jobs at a copper mine in Montana 210
i. n
E TEXT TABLES ‘
g Table
g` 1. Power shovels at open—cut copper mines, 1935 . . . 46 i
s
`§ 2. Locomotives at cpen—cut copper mines ....... 54
i 3. Average output, 1925-29, of ore and copper per
§. man-shift, by type of deposit and underground
Q mining method .................. 75
Q
E 4. Depth of shafts in underground mines in Michigan,
Q Montana, and Arizona, 1905-35 .......... B4
E
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CONTENTS xi jg
TEXT TABLES-Continued §
Table Page j
5. Production, employment, man-shifts, and unit labor Q
requirements in copper mining, 1914-36 ..... 180 ,
8. Total copper consumption and secondary copper pro- 5
duction, 1919-37 ................ 205 g
4
é
»_ APPENDIX TABLES
A-1. Production, employment, and output per worker at E
~ copper mines, 1880-1938 ............. 214 Q
[ A-2. Production of copper ore and copper, by mining i
method, 1880-1938 ........... . .... 218 {
A-3. Production of copper, by principal district, é
1880-1938 .................... 218 Q
A-4. Production and yield of direct-smelting and mill- N
ing copper ores, 1880-1938 ........... 220 ·
A—5. Production of copper, by principal producing ,
State, 1880-1938 ................ 221
A-8. Production of copper ore, by principal producing
State, 1880-1938 ................ 223 {
. A-7. Production of ore, copper, and copper equivalent, ,
yield of ore, employment, and productivity in
the copper-mining industry, by mining method, i
1917-ae ..................... 224 Q
A-8. Production of ore, copper, and copper equivalent, 3
yield of ore, employment, and productivity in g
the copper-mining industry, by State, 1917-38. . 238 Q -
A—9. Production, employment, and output per man-shift i
at open-cut copper mines, 1914-38 ........ 252 5
2
A-10. Production and employment at underground copper i
mines, 1914-38 ................. 253 g
I ‘ A-11. Pounds of copper per ton of ore, by mining method, §
V 1910-38 ..................... 254 i
A-12. Production and output per man-hour at Michigan Q
copper mines, 1917-38 .............. 255 é
A-13. Production of copper ore and copper at copper %
mines, by mining method, 1917-38 ........ 258 i
A-14. Number of wage earners and horsepower at copper g
mines, 1880-1929 ................ 257 §
A-15. Trends in copper content of concentrator heads and é
; copper recoveries at typical concentrators, j
1911-35 ..................... 257 {
A-18. Accident rate at copper mines, 1911-38 ...... 258 E
. a
A-17. Estimated use of copper in the United States, by Q
principal use, 1919-37 ............. 259 i
A-19. Estimated copper reserves, by State, district, 3
and mine .................... 280 i
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PREFACE  
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The history of copper mining in this country affords a striking ex-  
ample of the manner in which the Nation's growing needs for important  
raw materials have in many instances been satisfied with a continually  
lcwer expenditure of labor per unit of output as well as with a declining  
’ total volume of employment. Many factors have contributed to these de-  
velopments; the most important appear to have been changes in methods of A
mining copper, improvements in mechanical equipment, and increased appli- f
cation of mechanical power in mines and in ore—dressing plants.  
‘ The twentieth century has seen the rise of the open-cut method of min-  
ing copper. From less than 2 percent in 1907, the copper output of open- Q
cut mines has grown to over two-fifths of the total. Large open-cut  
operations use mass-production methods of breaking, loading, and hauling  
ore that cannot be used in underground vein mines. In consequence, out-  
put of ore per man-hour is four or five titres as great in Open-Cut oper- ’*
ations as at underground vein mines, and copper output per man—hour is § `
more than twice as great. j,
The rise of open-cut copper mining depended upon two principal tech-  
nological developments: mechanical methods of handling large volumes .
of materials and improvements in ore-dressing techniques. The open-cut {
method of mining with power shovels and other large-scale mechanical  
equipment was borrowed from the iron-mining industry. Improvements in  
gravity concentration and the development of the flotation process of ore  
dressing have made commercially possible the recovery of copper from low-   `
grade disseminated ores that no years ago were considered worthless    
most engineers. It is these deposits that are now being worked by the  
open-cut method.  
At underground mines, too, there have been significant advances in min-  
ing methods. Most important of these is the development of modern under-  
cut caving methods that give to underground mines some of the advantages  
accruing to open-cut operations through mass-production methods of han-  
dling ore. _!
Over the several decades covered by this study, the most important in-  
fluence on employment opportunity in copper mining has been the rising  
output per worker that has resulted from these changes in mining methods  
1 and from mechanical innovation and improvement of equipment and power  
utilization. Associated with these technological changes, which require  
large capital outlays for development work and for operating equipment,  
has been the trend toward a greater concentration of control in the hands  
xiii §
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  xiv Pnnricn
 
{ of large producers and toward fewer and larger operating units. In 1922
Q the three largest producers accounted for about one—third of the copper
Q production; in 1936 they produced about three—fourths of the total.
gp Centers of production have shifted as a result of depletion in some of
é the older areas and the increasing exploitation of low—grade ores in the
E. newer western regions. Thus Michigan and Montana have declined in both
i_ absolute and relative importance while Arizona and Utah have become the
% most important copper-producing States. Since by and large the newer
ig areas are those where labor productivity is highest, the growing relative
QL importance of these areas has in itself served to decrease unit labor re-
Q quirements in the industry as a whole. In addition, the southwestward
» nngration of the industry, the shift to surface operation, and changes in i
. V underground methods have altered the character of ccpper-mining occupa-
t` tions and the locations of employnent opportunity and thus have created
g.» adjustment problem  for many of the copper miners.
E This report is one of a series of studies conducted by the National
it Research Project in cooperation with the United States Bureau of Pdnes
§` under the direction of O. B. Kiessling. It was prepared by Y. S. leong,
pl who was loaned for this study by the Central Statistical Board: Emil
i Brdreich, J. C. Burritt, C. B. Nighman, and George C. Beikes ot ine Ter
1 tional Research Project: and O. E. Kiessling of the Bureau of Hines. lhe
{ manuscript was edited and prepared for publication under the direction of
%_ Edmund J. Stone.
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ACKNOWLEDGMENTS 3
SE
Acknowledgment is made of important aid given in the preparation of g
this report by officials of the United States Bureau of Mines. Data Q
on ore production, yield, and depth of mines were supplied by Chas. W. {
` Henderson, Supervising Engineer of the western field offices of the ri
Mineral Production Division, and by J. P. Dunlop, C. W. Merrill, and i
T. H. Miller, respectively in charge of field offices of the same division é
at Joplin, Mo.; San Francisco, Calif.; and Salt lake City, Utah. C. N. j
Gerry, Supervising Statistician of the last—named field office, also sup-  
plied valuable information and suggestions. Employment data utilized in Q
l this survey were node available by W. W. Adans, Supervising Statistician, 2
Employment Statistics Section; M. E. Kolhos of the sane section gave ine Q
portant help in the use of this material. C. F. Jackson, Supervising Q
Engineer, and C. E. Julihn, Principal Mining Engineer, of the Mining i
Division, and E. D. Gardner, Supervising Engineer of the Tucson (Arizona) 3
office of the sane division, gave important aid in the classification of § ·
mining methods and in supplying information on mine ventilation. J. W. .
Furness, Chief Engineer; E. W. Pehrson, Asst. Chief Engineer; and H. M. i
Meyer, Senior Clerk, all of the staff of the Metal Economics Division,
supplied valuable information and suggestions. The writings and sugges- j
tions of Daniel Harrington, Chief of the Health and Safety Branch, have R
been heavily drawn upon in preparing sections of the discussion concerned §
with the health and safety of miners; F. S. Crawford, District Engineer 5
of the Duluth (Minnesota) office of the same branch, aided in the classi— é
fication of mining methods. The preliminary examination of statistical Q
data was conducted under the supervision of R. J. Lund, formerly Mineral g
Economist of the Bureau and now Editor of The Mining Congress Journal. i
Grateful acknowledgment is also made to WTA National Research Project E
staff members who carried out major tasks in the conduct of the study. g
Responsibility for the accuracy of the statistical compilations fell é
chiefly upon Sidney Ginsburg and M. B. McIntyre, who also made important §
suggestions for improvement of the report. D. C. Athanas, E. M. Steuart, %
and P. J. Wester carried out special assignments in the preparation Q
of the manuscript. Cooke Settle was responsible for the lay—out of the E
charts and furnished valuable aid in writing the technical sections of E
the report. R. E. Good, H. Cowles, and H. Tilford assisted in organ- E
izing and preparing the statistical material. W. S. Stanley prepared Q
preliminary sketches of the illustrations of mining methods.
(
xv E
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  xvi ACKNOWLEDGMENTS
 
  Valuable information on mining methods was supplied by John Norton
  and D. R. Rait, Mining Engineers in the Mining Section, Reconstruction
  Finance Corporation. Special thanks are also expressed to I. Alleman
  who completed the drawings presented in figures gg to 33, inclusive,
  through the courtesy of Howard B. Myers, Director of the Division of
1 .
Q Research, and E. G. Millison, Chief of the Graphic Section, Work Projects
Aix Administration.
  Special data or photographs presented in this report were kindly sup-
1:
  plied by the following concerns: Anaconda Copper Mining Company, 25
  Broadway, New York City, N. Y.; Utah Copper Company, Kearns Building,
  Salt Lake City, Utah; Ingersoll-Rand Company, 1; Broadway, New York City,
·· N. Y.; Gardner—Denver Company, Quincy, Ill.; Eimco Corporation, 634-666
K, South Fourth West St., Salt Lake City, Utah; and Worthin ton Pump and
8
% Machinery Corporation, Harrison, N. J. Thanks are also expressed for
g ‘ photographic material that was courteously furnished for use in this re-·
{ port by the United States Bureau of Mines.
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CHAPTER I  
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INTRODUCTION1  
The present study attempts to analyze the effect of changes in tech-  
nology and in mining conditions on employment opportunities in one of the  
most important mineral industries - copper mining — and to determine the  
prospects it offers for employm