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By Louis Stott

IT is well known that the oxide of beryllium was identified as a new "earth" in 17971 and the metal first isolated in 18272. The history of the many difficulties encountered by early investigators, the laboratory achievements of Lebeau3, Fichter4 and Oesterheld5, and the eventual development of methods for commercial production are well covered in the literature, particularly in the authoritative published work of Siemens and Halske6 reviewing their comprehensive investigation of the element. Accordingly it has seemed desirable to restrict this paper to the properties and uses of beryllium and its alloys.

Jan 1, 1936

Merritt: Karl, you are a native New Englander, having been born in St. Albans, Vermont, in 1885. How did you decide on becoming a mining engineer? Twitchell: While I was attending St. Albans High School, my uncle, who had been the American Consul in Kingston, Ontario, for many years, told me of the excellent mining school there. He also introduced me to a Canadian mining engineer who sparked my interest in mining by noting the possibility of achieving personal success without always being under salary. Well, that appealed to me, so I applied to the Kingston School of Mines at Queen's University.

Jan 9, 1965

By AIME AIME

A new Index of the Transactions, Volumes I. to XXXV., is now being prepared, and will probably be ready for distribution during the coming summer. The Index will be about the size of the average volume of the Transactions, and will be bound in cloth and in half morocco. The price of the cloth-bound copy is $5, expressage prepaid. Half morocco binding will cost $1 extra. It is very desirable that all who wish to purchase this Index will notify the Secretary's office promptly, sending a check, money-order or draft, made payable to the American Institute of Mining Engineers.

May 1, 1907

By Theodore M. Barry

Work measurement is the most common of many titles given to determining the amount of human work required to do any job. A new technique-like most modern management tools-it still needs years of constructive research. Yet despite known imperfections, it is probably the most enthusiastically used tool of cost control developed in the last hundred years. Over 85 pct of all companies employing more than 100 workers in one of the major industrial areas use work measurement. For a good reason, however, this has not been true in the mining industry until very recently. The facts make an interesting story.

Nov 1, 1955

By Chi-Yuen Wang, Chaw-Long Chu

The time-dependent volumetric constitutive relation for a San Andreas fault gouge and a consolidated kaolinite are experimentally determined at confining pressures to 200 Mpa, under creep condition and at ultrasonic frequency. At any given pressure, the bulk modulus determined at 1 Mhz frequency is identical to the "elastic" modulus determined at a stepwise change of pressure. After the pressure change, there occur a time-dependent change of volume and thus the effective bulk modulus. The constitutive relations may be modeled by a standard linear viscoelastic medium with pressure-dependent moduli and viscosity. For the San Andreas fault gouge, viscosity increases from 2x10 13 poise, at 17 Mpa, and 10 14 poise, at 100 Mpa. For kaolinite sample, the corresponding values are 3x10 12 poise and 10 13 poise. These results imply that both stress and pore pressure in fault zones may show time-dependent variations in response to a change of state of stress, such as that occurring after an earthquake.

Jan 1, 1982

By C. C. Harris

The Gaudin-Meloyl equation for the size distribution of fragments resulting from single fracture is where y is the mass fraction of material smaller than size x, and x, and r are parameters to be determined from the experimental data. In physical terms, r is associated with the number of active flaws in a particle of characteristic dimension xo . The special attribute of this equation is its emphasis on the coarse size region of a distribution. There are various procedures2-5 for obtaining the parameters in Eq. 1, but a simple graphical method is awaited. This situation contrasts sharply with that in the cases of the familiar Gates-Gaudin-Schuhmann and Rosin-Rammler equations.6 The purpose of this note is to present a method based on a procedure7 which has been successful in several other applications.8-13

Jan 1, 1967

The University of Idaho Mining Society held a meeting on Oct. 23, and elected the following officers: President, Sam Bloom; Vice-President, Lloyd McDougall; Secty Treas, Jess W. Wade. Regular meetings are held on the first and third .Tuesdays of each month, for informal lectures and reports on technical subjects. The Mining Club of the University of Wisconsin has held four recent meetings On Oct. 17, sixteen new members were inducted, and a committee was appointed to buy a Liberty Bond. The second meeting, Oct. 31, was devoted to general entertainment, at the home of Professor McCaffery.

Jan 1, 1918

By L. C. Noakes

Despite a long history of mining. Australia had no Commonwealth organization dealing specifically with the mineral industry until 1946, when the Australian Bureau of Mineral Resources, Geology and Geophysics was established. Once formed, this new organization quickly expanded to include a Mineral Economics Section, which was established in 1947. Australia's slowness to develop a Federal bureau for the mineral industry can best be explained in the light of her political history. From a group of British crown colonies, Australia evolved into six sovereign states which had no unified federal government until they formed the present Commonwealth in 1901.

Jan 1, 1970

By F. L. Robertson, C. H. Bacon, J. W. Till

A description is given of the development of a process for making low sulphur steel on furnaces fired with 2 1/2 pet sulphur oil. Slag and metal are analyzed at melt. Slag weight is estimated. A simple method for calculating necessary lime additions for making 0.025 and 0.035 pct sulphur steel is given. DURING the last 15 years John Summers & Sons have been confronted increasingly by the problem of producing a low sulphur steel from high sulphur materials. The principles adopted, the processes used, the data collected on a furnace specially set aside to study this problem, and speculation on future developments are dealt with in this paper. This study is limited to two melting shops which make sheet steel only, of the following analysis: C, 0.06 pct; Mn, 0.33; S, 0.04, 0.035, 0.03, and 0.025; and P, 0.02 and 0.015. All the processes described have reference to the manufacturing of this steel and are not necessarily applicable, without modification, to other steels. The raw materials used are given in Table I. Development of Process About 1934, Schenck's work on phosphorus was applied to frame quantitative rules for the removal of phosphorus, with great success. We could however, neither in our own work nor in the voluminous literature, find any assistance to frame quantitative furnace rules to remove sulphur. Perhaps, we should have persevered with Schenck's outstanding chapter on sulphur in The Physical Chemistry of Steelmaking, but we missed the importance of one (Ss) sentence on p. 478. "Evidently this ratio -------- is [S] the important quantity to be considered from the point of view of chemical reaction; it is clear that the sulphur content of the steel alone, as frequently given in the literature cannot suffice for judging the success of the reaction unless special details are given regarding the sulphur charge and the amount of slag."' We were not however very successful in getting values for Schenck's "n" that agreed with (S) arrived at by our direct analysis. [S] In addition to Schenck's work much attention was given to V value. The formula selected for V was: (SCaO) — 1.57 (2 P2O5) (S SiO2) After plotting many charges a curve was obtained, based upon the relationship between the percentage sulphur in the finished steel and V value, Fig. 1. For a long time this was used as standard with about a 60 to 70 pct success on producer-gas fired furnaces, if all uprising scrap was used and no bought scrap used. An inspection of this curve shows clearly that it is not a quantitative manufacturing process, and that it was not sure enough to go to the trouble and expense of doing stage analysis for P,O,,

Jan 1, 1952

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period Mar. 10 to Apr. 10, 1915: Oscar Lachmund, Greenwood, B. C. Harvey B. Small, Mangaugue, Colombia. S. W. Ough, Pachuca, Mexico. M. F. Sayre, Schenectady, N. Y. B. W. Vallat, Detroit, Mich. James W. Hambleton, Parral, Mexico. Charles Mentzel, New York, N. I . Philip L. Gill, Woodmere, L. I., N. 1. M. K. Rodgers, San Francisco, Cal. John T. Fuller is President of the F. Shepherd Mining Co., operating at Rush Mountain, Ark.

Jan 5, 1915

By J. C. Crampton

Gradual shifts in the center of ore production have dictated three moves for the Pend Oreille Mines & Metals Co. plant. Capacity has grown from 300 tpd to the present 2400 tpd, and the gravity process used at the original Josephine mill has long since given way to improved flotation practice. The Josephine mill, operated in World War I and converted to flotation in 1927, treated 200,000 tons of ore rating as high as 16 pct Zn. By 1935 extra ore handling warranted construction of a new mill on a lower level, and capacity was raised from 300 to 800 tpd.

Sep 1, 1955

By R. A. Matuszak

Throughout the history of power excavating machines, engineers have continuously tried to shape the main drive speed- torque characteristics to provide an optimum from each main motion. Selection of prime mover for the various motions has been the subject of many engineering studies and most forms of energy conversion have been tried. A new form of electrical power conversion looms on the horizon as the most optimum yet. Controlled frequency operation of a squirrel cage induction motor increases the reliability of the most reliable form of energy conversion (electrical) found thus far, and improves the performance characteristics.

Jan 1, 1979

By L. R. Velho, N. A. D. Parlee, J. Gani

THE unsteady-state type of gas-liquid metal diffusion cell1 has found considerable application.2"4 Cells of this general design can function as steady-state cells if allowed to operate long enough to reach steady state. This report tells of some success in the adaption of this type of cell for steady-state work, using the 0-Ag system in which the mass transfer of the gas "species" is basically controlled by diffusion in the liquid. The gas, e.g-., O2, is maintained in the cell tube'-3 at 1 atm pressure, Fig. 1, by buret and sensitive oil manometer. The gas, after diffusing through the stagnant metal, escapes at the annular metal surface around the tube at a lower constant partial pressure, in this case that of O2 in slowly flowing air, 1 atm.

Jan 1, 1970

By Eugene A. Stephenson, Leon J. Pepperberg

The natural gas industry is essentially a byproduct of the oil industry. When first discovered the gas was usually regarded as a nuisance, and even when found immediately associated with oil, or suspected to be so, it was customary to blow it freely into the air, in the hope that gas would shortly be replaced by a flow of oil. The early methods of production,' transportation, and utilization were neither economical nor efficient; the chief value of gas was based on its use as a fuel, with no regard to (1) its effect. upon the oil with which it was associated, (2) its importance as a lifting agent, or (3) to its possibilities for the manufacture of byproducts. The spread of scientific research among major gas and oil companies, manufacturers, and academic groups, has gradually brought recognition of the fact that many of the technical problems bearing on production, transportation and utilization are common to both the gas and the oil industry. A few of the problems that have received serious study, and from which highly gratifying results have been obtained, are: (1) gas measurement, (2) oil well and gas well capacity tests, (3) elimination of field waste, (4) design of pipe lines and compressor stations, (5) extraction of constituents which might interfere with the normal flow of gas through the line, (6) control of reservoir pressure, (7) estimation of reserves of both oil and gas, (8) control of water encroachment, (9) measurement of factors which influence fluid movement through sands, (10) solubility of gases in oils, (11) effect of dissolved gases upon the properties of the solution. These investigations have demonstrated that almost every problem relating to oil production also involves some phase of natural gas engineering. During the past 15 years the use of experimental methods for the discovery and measurement of obscure, influencing factors, which cannot be determined purely by hydrodynamic or thermodynamic analyses, have contributed much towards the progress made in solving the problems of the oil and gas industries. Most of the experimental work on

Jan 1, 1934

By D. F. Botkin, B. H. Sage, W. N. Lacey

Joule-THomson coefficients for two natural gases were determined at pressures up to 600 lb. per sq. in. throughout the temperature interval between 70" and 310°F. From these primary data and available information relating to the isobaric heat capacities of the components at infinite volume, the heat capacities of these gases were computed throughout the above-mentioned range of pressures and temperatures. The enthalpies of the gases were computed as a function of state and the results compared with values obtained by several methods of prediction currently available. Table i .—Composition of Gas Samples Components Gas A Gas B Carbon dioxide................ 0.0090a 0 .042 0 Methane...................... 0.8255 0.8385 Ethane.......................0.0901 0 .0637 Propane....................... 0.0462 0.0374 Isobutane..................... 0.0074 0.0039 n-butane................ ...... 0. 0126 0 .0095 Isopentane.................... 0.0032 0.0016 n-pentane..................... 0.0022 0.0011 Hexanes and Heavier........... 0.003& 0.0023 Experimentally determined Joule-Thom. son coefficients for natural gases afford a satisfactory means of checking the accuracy of prediction of their thermodynamic properties from the behavior of the components in the pure state and in binary mixtures. Relatively small samples of these natural gases were available, together with their analyses, and the Joule-Thomson coeffi- The Joule-Thomson coefficients were determined by measuring the change in temperature resulting from the passage of the gas through a porous thimble with a known pressure difference and under such conditions that the process was substantially isonthalpic. The details of the apparatus employed for this purpose have been described.' It is believed that the changes in temperature and pressure were ascertained with an uncertainty of not more than 0.3 per cent. However, as a result of deviations from steady flow, it is probable that uncertainties as large as 2 per cent may exist in the measured Joule-Thomson coefficient. The gases utilized in this work were taken from high-pressure separators and were dried prior to use by passage over calcium chloride at pressures in excess of 300 lb. per sq. in. The gases were subjected to the conventional fractionation and Orsat analyses. The results are recorded in Table I. The composition is typical of gases from such sources, with the possible exception of the presence of significant quantities of carbon dioxide in each of the samples. The experimental results obtained for the two natural gases are graphically Portrayed in Figs. I and 2. The experimental

Jan 1, 1943

By W. N. Lacey, D. F. Botkin, B. H. Sage

Joule-THomson coefficients for two natural gases were determined at pressures up to 600 lb. per sq. in. throughout the temperature interval between 70" and 310°F. From these primary data and available information relating to the isobaric heat capacities of the components at infinite volume, the heat capacities of these gases were computed throughout the above-mentioned range of pressures and temperatures. The enthalpies of the gases were computed as a function of state and the results compared with values obtained by several methods of prediction currently available. Table i .—Composition of Gas Samples Components Gas A Gas B Carbon dioxide................ 0.0090a 0 .042 0 Methane...................... 0.8255 0.8385 Ethane.......................0.0901 0 .0637 Propane....................... 0.0462 0.0374 Isobutane..................... 0.0074 0.0039 n-butane................ ...... 0. 0126 0 .0095 Isopentane.................... 0.0032 0.0016 n-pentane..................... 0.0022 0.0011 Hexanes and Heavier........... 0.003& 0.0023 Experimentally determined Joule-Thom. son coefficients for natural gases afford a satisfactory means of checking the accuracy of prediction of their thermodynamic properties from the behavior of the components in the pure state and in binary mixtures. Relatively small samples of these natural gases were available, together with their analyses, and the Joule-Thomson coeffi- The Joule-Thomson coefficients were determined by measuring the change in temperature resulting from the passage of the gas through a porous thimble with a known pressure difference and under such conditions that the process was substantially isonthalpic. The details of the apparatus employed for this purpose have been described.' It is believed that the changes in temperature and pressure were ascertained with an uncertainty of not more than 0.3 per cent. However, as a result of deviations from steady flow, it is probable that uncertainties as large as 2 per cent may exist in the measured Joule-Thomson coefficient. The gases utilized in this work were taken from high-pressure separators and were dried prior to use by passage over calcium chloride at pressures in excess of 300 lb. per sq. in. The gases were subjected to the conventional fractionation and Orsat analyses. The results are recorded in Table I. The composition is typical of gases from such sources, with the possible exception of the presence of significant quantities of carbon dioxide in each of the samples. The experimental results obtained for the two natural gases are graphically Portrayed in Figs. I and 2. The experimental

Jan 1, 1943

By A. W. Schlechten, Ernest J. Breton Jr.

Experiments on the separation of copper and zinc ions by selective action of ion exchange resins showed the carboxylic type to be more effective than the sulphonic resins. The latter demonstrated a greater capacity over a wider pH range. Data show the effectiveness of resins as a means of concentration. IN recent years the restrictions of stream pollution laws and the high price of metals have created an interest in ion exchange as a means for metal recovery. Some applications have proved successful. In Germany during World War 11, 17 tons of copper per day were recovered from rayon mill wastes by means of ion exchange resins;' and for some time in this country a large ion exchange unit has been in operation for the recovery of copper from rayon waste water. The possibilities of applying ion exchange to the recovery of metals occurring in plating rinse water is particularly promising. In most of these applications only the metal being recovered occurs in the waste. The ion exchange resins act merely as a means of concentrating the metals to a point where they can be recirculated. It would be highly desirable to use ion exchange as a means of not only concentrating but also of separating metals. With the exception of the impressive separations accomplished in connection with the atomic energy program, very little has been done on metal separations.' Therefore, an investigation was undertaken at the Missouri School of Mines and Metallurgy to determine if either of the two main types of ion exchange resins could be used to separate metal ions in solution. The selective removal of copper ions from a mixture of copper and zinc on carboxylic and sulphonic-type resins was investigated as a function of flow rate, pH, copper-zinc ratio, and concentration. It was shown that zinc can be separated from copper and that very large ratios of concentration can be obtained using ion exchange resins. Since ion exchange is relatively new to the field of metallurgy, a brief review of the subject will be included. Theory of Ion Exchange A comprehensive theory for ion exchange has not been developed as yet, but the mechanisms are analogous to metathetical reactions: R Na + Cu++ *=? K(SO3)2 Cu + 2Na+ R is the designation for the ion exchange resin. If a copper solution is passed over a resin bed in the sodium form, two ions of sodium will be released for every ion of copper removed. For the most part this reaction follows the laws of mass action and of electrical neutrality. Consequently, if an excess of sodium ions is passed over a bed containing copper, the reactions will be reversed, and the resin will be regenerated to its original form. A few empirical rules governing the exchange reaction have been set forth: 1—In general ions with a high valence will replace ions with a lower valence. 2—Ions having higher activity coefficients have a higher replacement potential. 3—In a series of mono-valent ions, those with the smallest radii of hydra-tion will tend to replace those having larger radii of hydration. 4—Where ions are similar in most respects, those with the higher atomic weight sometimes will take precedence. This last rule is not as definite as some of the others. These rules apply to rather dilute solutions at moderate temperatures and assume all ions to be present in about equal concentrations. Higher concentrations and temperatures may in some cases reverse the normal exchange reactions. Ion exchange materials are unique in that their efficiency increases as the concentration of the solution decreases. For many exchangers, most efficient operation is obtained at concentrations in the order of one thousandths of a percent. Most applications, though, are made in solutions containing considerably higher concentrations than this. Coste9 as shown that ion exchange resins will remove aluminum and iron effectively' from solutions of up to 10 pct chromic acid. Ion Exchange Resins Ion exchange resins are insoluble, porous, resinous structures to which active groups have been attached. Active groups such as (—SO,,)- and (COO)- pick up cations; hence structures saturated with groups such as these are called cation exchangers. Structures saturated with groups such as (—NH,)' which pick up anions, are referred to as anion exchangers. The resinous structure of necessity is resistant to strong acids, bases, oxidizing, and reducing agents, and most of the common organic solvents. An idea of the stability can be gaged from the fact that resins last for many years under constant use without detectable chemical or physical breakdown. The ion exchange reaction is not confined to the surface of these synthetic resins. Its porous structure permits active groups in the center of a particle as well as those on the surface to remove ions. A high capacity resin such as Amberlite IR-120 will remove up to 3.3 lb Cu per cu ft of resin. In this investigation several approaches to the problem of separating copper from zinc by ion exchange were considered. First, if a reagent could be found which would complex one of these metals and not the other, then by passing this reagent through a bed of exchanger containing copper and zinc, the

Jan 1, 1952

By Denis G. Maxwell

INTRODUCTION It is my intention in this paper to deal with gold, uranium, diamonds, platinum, manganese, chrome, vanadium and heavy mineral sands. These are the most important strategic minerals produced by the Republic of South Africa which are not covered in other sessions of this program. In each case I have high- lighted the statistics and peculiar advantages which combine to make South Africa a vital source of these minerals. Before proceeding to give individual attention to these minerals I believe it would be useful to define what I mean by 'strategic'. The Concise Oxford Dictionary defines strategic in the context of materials as 'essential for war'. However it is commonly used in a much broader sense than this (often, in fact, very loosely) and I prefer to define it as 'concerned with the acquisition and maintenance of power, whether economic, political or military.' A VITAL SOURCE In dealing with the individual minerals I have quoted statistics which are contained in Tables 1, 2 and 3. Table 1 clearly shows the absolute size of the South African mineral industry. However, it can also be used to demonstrate the importance of the industry to the South African economy if compared with the GNP in 1980 of about R60 billion. Table 4 illustrates clearly how important South Africa is as a supplier of these minerals to most of the important industrialized countries of the Western World. Gold If anyone had any doubts about the inclusion of gold in a list of strategic minerals I am sure that the above definition of 'strategic' will convince them that it certainly belongs there. Similarly no one is likely to have any doubt about the fact that South Africa is a vital source of supply. Tables 2 and 3 show that in 1980 we had 51% of the world's reserves and accounted for 55% of world production. The figures for the Western World are considerably higher. The only other major producer, of course, is Russia, with small but significant production in the Pacific Rim area coming from Australia, Canada, Latin America, Papua New Guinea, Philippines and the U.S. All South African mine gold production is shipped in bullion form containing about 88% gold and 9% silver to the Rand Refinery which is a modern refinery with large scale units capable of refining half a ton of bullion at a time. The Refinery is equipped to produce standard 'good delivery' gold as well as 9999 gold and 999 silver. The Refinery also produces the 22 karat blanks which are, used by the South African Mint to produce Kruger Rands. It goes without saying that the South African gold mining industry leads the world in all aspects of deep-level, narrow-reef mining technology. The industry's metallurgists, too, have a record of tenacious and continuing efforts to improve extraction to the level of the present finely honed efficient process used on all the modern mines. Uranium In 1980 South Africa had 14% of the uranium reserves of the Western World and accounted for 14% of production. In view of the paucity of data I am not in a position to estimate figures for the total world. All the other major sources of uranium in the Western World are situated around the Pacific Rim, with the U.S. and Canada already being major suppliers and accounting for 38% and 17% of Western World production in 1980. Australian production at the time was small but they have very large reserves and production is already rising rapidly. The U.S., Canada and Australia account respectively for 22%, 19% and 29% of the uranium reserves of the Western World. South Africa has been a major producer continuously for 30 years. Nearly all the uranium produced, amounting to about 115 000 tons up to the end of 1981, was a by-product or co-product of gold extraction. During that time the industry has frequently led the world in technological innovation, and has established a reputation as a reliable producer of a consistent, high-grade product. In the latter respect, it is helped by the fact that production is marketed by one company, Nuclear Fuels Corporation, which also blends, dries and calcines the product from the individual mines and samples and assays it before shipping. Diamonds Diamonds are the rock on which the South African mineral industry is founded. The discovery of diamonds in 1866 gave rise to the first major mineral industry in the country and the profits from diamond mining helped to finance the gold mining industry 20 years later. Although now overshadowed by gold, diamonds are still very important in the overall picture of mineral production and exports, as can be seen in Table 1. There are really three separate diamond markets - gem, natural industrial, and synthetic - and, to be meaningful, statistics should be provided separately. Unfortunately separate figures are not available. The figures in Tables 2 and 3 show that, for gem and natural industrial together, South Africa ranks third in the world in production and second in reserves. South Africa is a major producer of synthetics and probably ranks second in the world after the U.S. Recently, of course, Australia was the scene of a major diamond discovery and will soon become the only

Jan 1, 1982

By Behram H. Wadia, Robert S. Lehto

A new metallurgical treatment for capturing as much of the values as possible from zinc refinery feed has been devised by personnel in Cerro de Pasco's Peruvian operation at La Oroya. Results from a pilot test illustrate that 50 metric tons of throughput can be maintained whereby substantially all the silver and copper report in the sponge iron while zinc and lead with indium and cadmium volatilize in the fume. This new technique named the Zileret (zinc leach residue treatment) process complements the electrolytic system used in the refinery so that all values in a zinc concentrate are economically recovered. In the system, dried zinc leach residue is pelletized with soluble zinc sulfate which already exists in the leach residue and a finely divided reducing agent such as anthracite coal. Upon heat addition, the loose anthracite in the charge maintains a reducing atmosphere while the free space above the charge has an oxidizing nature. When the charge reaches the reaction zone at about 1100°C, metals such as zinc, lead, cadmium and indium volatilize from the pellets, are oxidized in the upper kiln atmosphere, and are then carried in suspension as an oxide fume to the cooler and baghouse. The copper and silver content in their reduced forms, along with the iron, discharge from the kiln as a calcined product which is then cooled to below 130°C before being exposed to the air.

Jan 9, 1969

By J. C. Konopka, S. A. G. Poppen, E. K. Roesner

Many shafts have experienced stability problems during shaft sinking because the designer failed to fully appreciate the conditions he would encounter. Some shafts have failed during construction because the ground supports provided to compensate for the expected conditions were inadequate despite the most careful investigations and analyses. To design a ground support which is ultimately safe to achieve stability during shaft sinking would be too costly and impractical and, therefore, many shafts would simply not be constructed. The design of a ground support for shaft sinking based on an intimate understanding of the expected ground behaviour and stress development during excavation combines the art of mining with the science of geotechnical engineering. Where no historical design data is available, the designer of the ground support must: 1. classify the rocks and soils and assess their behavioural characteristics; 2. calculate the primary and secondary stresses; 3. design and/or select a ground support system which will ensure stability of the excavation during shaft sinking.

Jan 1, 1983