Английски език
Quarrying and all other branches of surface mining rather than diminishing in importance have become of more and more consequence economically, industrially and particularly with the depletion of high-grade deep-mined mineral reserves. Low-grade minerals require low cost extraction and this in many cases necessitates very expensive mechanized equipment with the cost of individual units running into millions of pounds in the case of large scale operations with high productivity. There has been, and there still is, a tendency for the smaller single quarries to be amalgamated into groups with large financial resources and therefore with the ability to purchase these expensive machines so necessary to make operations viable. This in turn requires wider administrative and technical knowledge in executives of these groups and as these often handle a wide range of products from widely differing systems of working, this technical knowledge should embrace the exploitation of many different types of deposits. There is, at present, a great dearth throughout the world of such qualified executives as is apparent from advertisements of vacancies in the technical press. It would appear that these industries offer an attractive career to the widely qualified and experienced technologist in these fields. This book deals with methods of working in the surface extractive indus tries, quarry management and power supply-but does not deal with related ancillary processes except where these affect quarrying operations.
