This volume is a condensation of a series of lectures delivered in part at Stanford and in part at Columbia Universities. It is intended neither for those wholly ignorant of mining, nor for those long experienced in the profession.
The bulk of the material presented is the common heritage of the profession, and if any one may think there is insufficient reference to previous writers, let him endeavor to find to whom the origin of our methods should be credited. The science has grown by small contributions of experience since, or before, those unnamed Egyptian engineers, whose works prove their knowledge of many fundamentals of mine engineering six thousand eight hundred years ago. If I have contributed one sentence to the accumulated knowledge of a thousand generations of engineers, or have thrown one new ray of light on the work, I shall have done my share.
I therefore must acknowledge my obligations to all those who have gone before, to all that has been written that I have read, to those engineers with whom I have been associated for many years, and in particular to many friends for kindly reply to inquiry upon points herein discussed.
CONTENTS.
| [CHAPTER 1.] |
| Valuation of Copper, Gold, Lead, Silver, Tin, and Zinc Lode Mines |
| Determination of average metal content; sampling, assay plans, calculations of averages, percentage of errors in estimate from sampling. |
| [CHAPTER II.] |
| Mine Valuation (Continued) |
| Calculation of quantities of ore, and classification of ore in sight. |
| [CHAPTER III.] |
| Mine Valuation (Continued) |
| Prospective value. Extension in depth; origin and structural character of the deposit; secondary enrichment; development in neighboring mines; depth of exhaustion. |
| [CHAPTER IV.] |
| Mine Valuation (Continued) |
| Recoverable percentage of the gross assay value; price of metals; cost of production. |
| [CHAPTER V.] |
| Mine Valuation (Continued) |
| Redemption or amortization of capital and interest. |
| [CHAPTER VI.] |
| Mine Valuation (Continued) |
| Valuation of mines with little or no ore in sight; valuations on second-hand data; general conduct of examinations; reports. |
| [CHAPTER VII.] |
| Development of Mines |
| Entry to the mine; tunnels; vertical, inclined, and combined shafts; location and number of shafts. |
| [CHAPTER VIII.] |
| Development of Mines (Continued) |
| Shape and size of shafts; speed of sinking; tunnels. |
| [CHAPTER IX.] |
| Development of Mines (Continued) |
| Subsidiary development: stations; crosscuts; levels; interval between levels; protection of levels; winzes and rises. Development in the prospecting stage; drilling. |
| [CHAPTER X.] |
| Stoping |
| Methods of ore-breaking; underhand stopes; overhand stopes; combined stope. Valuing ore in course of breaking. |
| [CHAPTER XI.] |
| Methods of Supporting Excavation |
| Timbering; filling with waste; filling with broken ore; pillars of ore; artificial pillars; caving system. |
| [CHAPTER XII.] |
| Mechanical Equipment |
| Conditions bearing on mine equipment; winding appliances; haulage equipment in shafts; lateral underground transport; transport in stopes. |
| [CHAPTER XIII.] |
| Mechanical Equipment (Continued) |
| Drainage: controlling factors; volume and head of water; flexibility; reliability; power conditions; mechanical efficiency; capital outlay. Systems of drainage,—steam pumps, compressed-air pumps, electrical pumps, rod-driven pumps, bailing; comparative value of various systems. |
| [CHAPTER XIV.] |
| Mechanical Equipment (Concluded) |
| Machine drilling: power transmission; compressed air vs. electricity; air drills; machine vs. hand drilling. Workshops. Improvement in equipment. |
| [CHAPTER XV.] |
| Ratio of Output to the Mine |
| Determination of possible maximum; limiting factors; cost of equipment; life of the mine; mechanical inefficiency of patchwork plant; overproduction of base metal; security of investment. |
| [CHAPTER XVI.] |
| Administration |
| Labor efficiency; skill; intelligence; application coördination; contract work; labor unions; real basis of wages. |
| [CHAPTER XVII.] |
| Administration (Continued) |
| Accounts and technical data and reports; working costs; division of expenditure; inherent limitations in accuracy of working costs; working cost sheets. General technical data; labor, supplies, power, surveys, sampling, and assaying. |
| [CHAPTER XVIII.] |
| Administration (Concluded) |
| Administrative reports. |
| [CHAPTER XIX.] |
| The Amount of Risk in Mining Investments |
| Risk in valuation of mines; in mines as compared with other commercial enterprises. |
| [CHAPTER XX.] |
| The Character, Training, and Obligations of the Mining Engineering Profession |
| [Index] |
CHAPTER I.
Valuation of Copper, Gold, Lead, Silver, Tin, and Zinc Lode Mines.
| DETERMINATION OF AVERAGE METAL CONTENT; SAMPLING, ASSAY PLANS, CALCULATIONS OF AVERAGES, PERCENTAGE OF ERRORS IN ESTIMATE FROM SAMPLING. |
The following discussion is limited to in situ deposits of copper, gold, lead, silver, tin, and zinc. The valuation of alluvial deposits, iron, coal, and other mines is each a special science to itself and cannot be adequately discussed in common with the type of deposits mentioned above.