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By Paul L. Russell, R. G. K. Morrison

9.1-CLASSIFICATION OF MINERAL DEPOSITS AND ROCK MATERIALS After a mineral deposit has been discovered, delineated and evaluated, the next step is to select a mining method that is physically, economically and environ- mentally adaptable to recovering the mineral from the deposit. The term "mineral deposit" is used to denote a concentration of mineral (including rock and coal). Even where there is considerable past experience available, many of the critical design criteria must be determined utilizing only information obtained from an examination of exploratory drill core specimens. The factors that affect this selection are as follows: (1) the spatial characteristics of the deposit (size, shape, attitude and depth); (2) the physical (or mechanical) properties of the mineral deposit and surrounding rock; (3) ground water and hydraulic conditions; (4) economic factors, including grade of the ore. comparative mining costs and desired production rates; and (5) environmental factors, such as the preservation of the surface overlying the mine, and the prevention of air and water pollutants. Of these factors, the spatial characteristics of the deposit and the physical (or mechanical) properties of the mineral and surrounding rock limit the methods that can be employed to mine it. Six types of mineral deposits are recognized, as follows: 1. Massive-A deposit of considerable lateral and vertical extent in which mineralization (or ore) is relatively uniformly distributed. Disseminated copper ores are typical deposits. Dome salt also is included in this classification. 2. Bedded or Tabular-A mineral deposit that parallels the stratification, most often in sedimentary rock, usually laterally extensive, and of limited thickness. Most coal measures and some evaporite mineral deposits (e.g., potash) fall in this class. 3. Narrow Vein-A zone or belt of mineralization (ore) typically long, narrow (less than 10 ft), often dipping steeply, and usually lying within boundaries separating it from neigh- boring rock. Many gold and other metallic minerals occur in narrow veins. 4. Wide Vein-As defined under narrow vein except that the vein thickness is greater than 10 ft. 5. Lentictclar or Pocket-An isolated ore body, or an enrichment of limited vertical and horizontal extent in a massive, bedded or vein deposit. Lead, zinc and iron ores often occur in this type of deposit. 6. Placer-A surface or near-surface deposit, usually tabular and may be of consider- able areal extent, containing mineral particles (e.g., gold, platinum) in detritus (e.g., sand, gravel). The rock materials associated with mineral deposits are classified as follows: 1. Detritus-Sediments and other accumulations of solid particles produced by the mechanical and/or chemical disintegration of rocks, and usually having a low cohesive strength and very low compressive strength (e.g.. soil, sand, gravel, alluvium, playa). 2. Jointed and Fractured-Unbonded-A rock mass, often occurring on or near the surface or in fault zones, in which the joints or fractures contain alteration or decomposition

Jan 1, 1973

By M. Tirmarche, J. Brenot, J. W. Piechowski

INTRODUCTION Statistical analysis of results obtained by workers survey is very often limited to the determination of the collective dose and mean annual values. This information is not sufficent by itself for radiation protection purposes since the cumulative exposure of a worker during his working life is not taken into account. A more complete analysis would be obtained by considering both: [ ] These two notions are different. The former depends on the evolution of the protection with time and is related to annual limits (ICRP, 1977 and ICRP,1977 a). The second depends mainly on the works performed during the period of survey, the interference of protection evolution is weakened. So it is useful to foresee how the individual average annual doses would be when considering survey periods of 5, 10 years, or more. STUDIED POPULATION In order to analyse the two previously mentionned notions it is necessary to follow up a well defined population of workers which is continuously exposed to the radiological hazards on a long enough period. The selected population is that of the workers of the French uranium mines always present during the 1971-1979 period (9 years). The number of individuals is 937. The radiological hazards are: 1. exposure to radon and short-lived daughters 2. exposure to long-lived ore dust 3. external irradiation. The workers of the uranium mines are exposed to these radiological risks in different ways according to the work performed. It is therefore necessary to subdivide the population into more homogeneous groups with respect to the radiological risks. Three groups are considered: - Group 1 : 227 individuals whose radon and dust exposures are always nil - Group 2 : 449 individuals whose radon and (or) dust exposures are different from 0 every year - Group 3 : 261 individuals represent a mixed category. Some features of these groups are given in table 1. [ ] The 937 followed individuals represent approximatively the half of the whole population of the French uranium mines. Taking into account the procedure adopted to select the studied population, it appears clearly that this population is not representative of the whole miner population. DOSIMETRIC RECORDS Three risk indicators are considered .Individual annual exposures to radon and its shortlived daughters. They are determined by ambient monitoring based on radon concentration measurements and recording of the times elapsed in the various workplaces. For each worker the annual exposure is represented by the mean annual air concentration and is expressed as a fraction of the maximum annual concentration (MAC). Given the administrative arrangements and the effective state of equilibrium between radon and its daughters, the maximum annual concentration is practically equivalent to 1 Working Level = 2.08 x 10- 5 jm-3. (UNSCEAR, 1977). . Individual annual exposures to long-lived ore dust which are also expressed in fraction of the maximum annual concentration. . Individual annual doses of external irradiation (X and [y] rays) expressed in mSv (= 10-3 Sievert). Irradiation monitoring is based on use of individual film badges.

Jan 1, 1981

By Peter J. Szabo

Many mining engineers tend to think of the economic analysis of mining ventures and projects on an f.o.b. mine basis. This is especially true of mines that are operated in an established domestic mining district. Here, transportation costs are many times smaller in comparison to overall delivered prices. One has only to consider the development economics of taconite mines in Minnesota with production destined for lower lake ports to see the truism of this statement. In the international arena, however, with consumers such as Japan and Europe located thousands of miles from source countries such as Brazil and Australia, the situation is different because mineral transportation is often a critical factor in determining project viability. This article is being presented to provide a basic understanding of the factors that govern ocean transportation of the three largest bulk mineral commodities shipped around the world: iron ore, coal, and phosphate. The major dry bulk commodity trades as a percentage of volume shipped are iron ore, 45%; grain, 25%; coal, 20%; phosphate rock, 5%; and bauxite and aluminum, 5%. Most of these commodities are carried by bulk carriers rather than tankers. These are vessels that have cargo, usually in solid form, loaded directly into the hold of a vessel by shore-side materials handling facilities or, in the case of a geared bulk carrier by the vessel's cranes and derricks. Gearless bulk carriers are used in most cases for iron ore and coal. Geared bulk vessels are mainly used for minor dry bulk trades such as ore concentrates (copper, lead, zinc, etc.), fertilizers (phosphate, potash, etc.), cement, petroleum, and coke. There has been, however, a trend toward using more self-unloading ships in both iron ore and coal ocean transport. And large vessels, such as the Universe Kure of Japan, have been designed with a cargo capability of 157 kt (155,000 dwt (deadweight tons)). Trade patterns of major bulk commodities are influenced by the Panama and Suez canals. Both of these canals have draft limitations that prohibit large, deep-draft, ocean-going vessels from using them for shorter trade routes used by Panamax and Suex vessels. The shipping industry has developed two widely used vessel classes; the Panamax and Suex vessels. The former is the maximum size vessel that can pass through the Panama Canal, usually 51-61 kt (50,000 - 60,000 dwt), depending on the season and draft of the vessel. The Panama Canal is usually 0.6-0.9 m (2-3 ft) deeper in the winter than in the summer. Thus, less cargo can be carried by the same size ship in the summer through the canal than in the winter. The Suex vessel is in the 71-81 kt (70,000-80,000 dwt) class. This larger vessel is able to transit the Suez since Egypt deepened the canal following the Seven Days War. Recently, the Suez Canal has been deepened to accommodate vessels with drafts as deep as 152 kt (150,000 dwt).

Jan 10, 1982

By Gerald W. Cormick

In a complex society such as ours, the range of "negotiating" relationships is constantly increasing. These negotiating relationships have emerged as a direct result of the diffusion of power or influence to new sectors and emerging concerns. Even within organizations, the myth of the authority-based heirarchical structure has given way to the reality of constant negotiations between superior and subordinate and with peers in the organizational structure. In the broader context, the corporate organization finds it necessary to reckon and often negotiate with organized employees, suppliers, buyers, government agencies and a range of organized private interests ranging from minority groups to environmental organizations. In response to this diffusion of power and the conflicts which it has engendered, a variety of conflict avoidance, conflict managing or conflict resolution techniques has developed. The purpose of this paper is to attempt to differentiate between some of the conflict intervention approaches which have appeared "on the market", and to suggest three bases for selecting among them: 1. The "role" of the conflict intervenor; 2. How far the conflict has developed; and 3. The breadth and impact of the issues involved.

Jan 1, 1979

By W. Irwin

As a consequence of the oil crisis of the 70?s, the commercial value of coal increased very sharply and an upward trend in coal prices although now less pronounced, continues today. The graph shown in figure 1 illustrates the trend in the F.O.B. price of U.S. metallurgical coal. This trend occurs during a time when mechanized mining is firmly established as a means of production throughout the coal mining world. With modem methods of mining, mechanical cleaning is a necessity and quality control is no longer entirely dependant upon coal face practice. The efficiency of fine coal recovery is of vital economic importance to present day operations and good practice in this field contributes significantly to improving profitability. Numerous processes are available for the duty and this paper discusses one such system, namely the practice of froth flotation.

Jan 1, 1980

By Boghani. A. B.

A computer program has been developed to simulate evacuation of a mine in various configurations. The simulation input variables include characteristics of the mine, expressed, in the form of a network of passages, properties of hoists and hoisting strategies, initial miner positions, ventilation and compressed air velocities, stench warning system and self rescuer capabilities. The simulation can be carried out for cases in which there is no fire, i. e. , fire drill simulation, or for cases in which there is a fire at any arbitrary location. The fire is assumed to generate gases which impede movement of miners in the gaseous region. However, the thermal effects of the fire are not considered. The simulation output include the evacuation time for each miner, movement of the hoists, propagation of smoke through the mine passages and smoke exposure of the miners. Several illustrative simulations have been carried out to verify validity of the program and to demonstrate its capabilities. The computer program has been able to predict evacuation time, within 5 percent, for an actual fire drill. It is believed that this program can be used to evaluate evacuation performance of a mine, identify problem areas and demonstrate improvements due to the recommended corrective actions.

Jan 1, 1977

By E. C. Roper

Landusky Mining, Inc. and Zortman Mining, Inc. are two registered Montana Corporations wholly owned by Pegasus Gold, Ltd. of Vancouver, B.C. The Zortman and Landusky Mines are located in the Little Rockies District of central Montana. The Zortman-Landusky mines produced 2,100 kg gold in 1982. A total of 3,250,000 t of ore per year are mined during the period March 1, to September 15, at an average grade of 1.04 gm/t (0.03 oz/t) gold and 13.4 gm/t (0.385 oz/t) silver at a cutoff grade of 0.35 grams of gold/ton (0.01 oz of Au/t) of ore. The stripping ratio during 1983 is anticipated to be 0.75/1 waste to ore. Combined average plant capacity of the two Merrill-Crowe plants is 9,840 lpm (2,600 gpm). The combined heap spray capacity of the two plants approaches 18,900 lpm (5,000 gpm). The mine employs approximately 200 people, about half of these work for the mining companies and the other half for the mining contractor, N. A. Degerstrom of Spokane, Washington. Net profit in 1982 for Zortman and Landusky Mining, Inc. approximated $4,900,000 at an average gold price of $11.40/gm.

Jan 1, 1983

By E. M. Haynsworth

The disposal of phosphatic clays has presented a problem to the phosphate industry since the mining of phosphate rock first began. As the flotation process was introduced in the late 1920's, the problem of clay disposal was increased significantly since clay is present in proportionally greater quantities in reserves yielding flotation concentrates. Because of their physical character and the tremendous surface area per unit volume, these clays have the characteristic of retaining large volumes of water as they are slurried during processing. The phosphatic clays with which we are dealing consist primarily of apatite, wavellite and montmorillonite. In the beneficiation process, we remove the -150 mesh material as waste. However, the particles are essentially smaller than -325 mesh, and more than 70% are smaller than three microns. The disposal of clay and the recovery of a portion of the water require settling areas with a capacity ranging up to 2 cubic feet for each cubic foot of phosphate matrix mined. According to a recent study by the Bureau of Mines, the average cost for disposal of these wastes is 24.5 cents per ton of, product (U. S. Bureau of Mines Circular 8404). This is a major cost of phosphate rock production.

Jan 1, 1970

By S. Tyson

The American Coal Ash Association, Inc. (ACAA) is an organization of producers and marketers of coal combustion byproducts. Since 1968, the goal of ACAA has been to gain recognition and acceptance of ccbs as an engineering material on par with competing virgin, processed and manufactured materials by advancing ccb uses that are technically sound, commercially competitive and environmentally safe. The use of ccbs is affected by local and regional factors including production rates, processing and handling costs, transportation costs, availability of competing materials, seasonal adjustments, and the experience of materials specifiers, design engineers, purchasing agents, contractors, legislators, regulators, and other professionals. An annual, survey of coal-burning electric utilities is conducted by ACAA to determine the quantities of ccbs produced and used in the USA. In 1993 approximately 88.5 million tons of ccbs were produced in the form of fly ash, bottom ash, boiler slag and byproduct from flue gas desulfurization (FGD). Approximately twenty-two percent of the combined production of these byproducts was used, while the remaining portion was deposited in disposal areas. The major markets for ccbs include cement and concrete products, structural fills, road-base layers, mineral filler in asphalt, grit for snow and ice control, blasting grit and roofing granules, grouting, coal mining applications, and waste solidification and stabilization.

Jan 1, 1995

By Michael E. Salovich

The U. S. Department of Interior, Bureau of Mines (Bureau) has developed a prototype version of a computer application that combines hydrologic analysis with object-oriented graphics. This software is unique in that it presents analytic element analysis within an object-oriented CAD environment. Its user interface employs mouse handling, scrolling windows, dialog boxes, palettes, and pulldown menus. It can import scanned images of maps and overlay these images within the same window. This application was developed using object-oriented programming techniques. Several programming issues concerning graphics had to be resolved during development of this system. These include (1) how to represent hydrologic elements as graphical objects, (2) how to translate screen coordinates to map coordinates, (3) how to implement ?zooming? (changing the magnification level of a window), (4) how to overlay layers of images, and (5) how to import scanned images of maps. An object library was used to implement graphical user interface features such as scrolling windows and pull-down menus. Algorithms for CAD features such as map coordinate translation, zooming, and the layering of images were developed by Bureau researchers. The application has a modular source code structure and can be modified for use in other research applications.

Jan 1, 1992

By G. R. Tostengard

Gold plant performance during the start-up period, which extends until capacity production is sustained, has a major impact on the internal rate of return and the net present value of gold projects regardless of mining and processing configurations. The start-up period experiences substandard production, extra expenses, and sometimes reduced recovery. This results in lost profits, a portion of which are recouped at the end of the life of the mine. Poor start-up performance can put projects into financial jeopardy. The gold mining industry regularly experiences start-ups ranging from good to poor. Problem areas, which affect start-up performance, include shortcomings in ore reserve sampling and testing, equipment design and installation, untrained plant operators, inability to cope with problems which arise, and organization of the maintenance program. An investment, equal to 0.5% to 1.0% of plant capital cost, in programs to prepare for start-up, in advance, is recommended. Investment in such a program will make a good start-up possible. Without it the best result which can normally be expected is a fair start-up. Developers of new gold mines are urged to compare the cost of this investment with the anticipated increase in project net present value. Funds for this investment should be included in feasibility studies.

Jan 1, 1988

By C. H. Lee, F. Concha, L. G. Austin, P. T. Luckie

The Concha-Almendra batch-settling treatment for concentrated suspensions of single-diameter spheres has been modified. This modified version is used in the differential equations of simple batch settling of a particle size range of different density materials. The equations have been programmed for a finite difference solution, and a number of test cases have been analyzed. By cutting the settling column at a fixed fractional height, the material below this height can be treated as underflow and the material above as overflow. The predicted partition curves obtained from treating the settling in this way have Sharpness Indices in the range of 0.5 to 0.6, in the absence of dispersion effects. The Sharpness Indices decrease as dispersion increases. When the feed size distributions are of the Rosin-Rammler form, the partition curves (corrected for the bypass fraction) fit the Rosin-Rammler equation with reasonable accuracy. The predicted Sharpness Index of a component of a mixture of two materials of different densities was unchanged from that of the same materials settled alone. However, for the same, feed size distribution and volume fraction of solids in the feed, the heavier material settled faster, and the lighter settled slower, than when settled alone.

Jan 1, 1993

By V. C. Kelessidis

Demand for multifunctional drilling fluids continuously increases. In the quest for more hydrocarbons, drilling has extended to deep water areas (now in excess of 2.000 m) and to very deep wells (now in excess of 6.000 m). In these extreme conditions, low temperatures, as low as 1-5°C on the sea bed, high temperatures, in excess of 200°C, and high pressures, more than 1.000 bars, in the bottom of the well, are frequently encountered. In these harsh environments, synthetic oil and oil based drilling fluids are used, but the former are expensive while strict environmental requirements have limited the use of the latter. Thus, drilling industry has turned back to water based drilling fluids which use bentonite as primary viscosifier and as a fluid loss control additive. However, in conditions of high temperatures, bentonite suspensions gel and loose their exceptional low temperatures properties, thus, additives are needed to overcome such problems. In this article we review these challenging drilling environments and establish the requirements for the multifunctional drilling fluids. Our research indicates that demand for continuing use of bentonite by drilling fluid industry is strong. Furthermore, we bring forward the opportunities for new additive development which can expand the operational ranges of bentonite suspensions.

Jan 1, 2007

By P. D. Roa, O. Noirot, H. Owens, D. E. Walsh, J. R. Mokka

Over a period of eight years (1989 through 1997) the Mineral Industry Research Laboratory (MIRL) at the University of Alaska, Fairbanks, AK, has investigated the effects of temperature, residence time and particle size on the degree of low-rank coal (LRC) upgrading for a nonevaporative, hydrothermal drying process, also known as hot water drying (HWD). The following three Alaskan LRCs were used in this study: Usibelli coal (Seam No. 4) from the Nenana Coal Field, Little Tonzona coal from near McGrath, and Beluga coal from the Beluga-Yentna field on the west side of Cook Inlet. Replicated factorial tests were conducted. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10 to 20 min of residence time. Thereafter, the upgrading process slows down, and more than 100 min of additional residence time is required to produce percentage increases equivalent to what was achieved in the first 10 to 20 min. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, equilibrium moisture levels and Hardgrove gindabilities all appear to change linearly with temperature within the 275°C to 325°C (525°F to 61 5 OF) range.

Jan 1, 2000

By Thomas R. Yanske, Jonathan E. Carmack, Lyndon M. Clark

In order to maximize the extraction of high grade pillars at The Doe Run Company, artificial pillars are created using cemented rock fill (CRF). CRF pillars aid extraction of pillars in two ways. One is to offer back support for the immediate area where pillars are being extracted. The second is to increase the post failure residual strength of pillars surrounded by backfill. The CRF is produced using a combination of minus 1.0 m run of mine (ROM) rock and minus 5 cm crushed rock. Depending on the operation the CRF slurry is either produced in an underground or a surface batch plant. The slurry and rock are transported to the fill area by truck where they are mixed and placed in 1 m lifts. To reduce the amount of CRF needed, fill fences are constructed around the perimeter of the CRF pillar. Within these fences ROM CRF is placed in lifts until within 0.6 m of the back after which minus five centimeter CRF is slung tight to the back utilizing slinger trucks. In constructing these artificial pillars a number of set procedures have been established to ensure that the work is done both properly and safely.

Jan 1, 2001

By R. J. Sawyer

*An earlier version of this paper was presented at the IMM meeting, "Use of Cultivated Carbon in Extraction of Gold and Other Metals," held in London in January, 1983, and was subsequently published in Trans. IMM (Sect. C: Mineral Process. Extr. Metall.) in December, 1983. Reprinted with permission of The Institution of Mining and Metallurgy, London. INTRODUCTION This paper describes the development of the processing route for the Alligator Ridge Mine which commenced operation in 1980. It also reviews the modifications which have been made to improve operating efficiency during the three years that the mine has been in production. Alligator Ridge is located 70 miles Northwest of Ely, Nevada. The mine is a joint venture between Amselco and Nerco with Amselco acting as operator. The deposit consists of micron sized disseminated gold imbedded in siltstone. Although definitive conclusions have yet to be drawn as to the age and origin of the deposit, it is probable that it is young by geological standards, perhaps only 5 million years old. It is likely that the gold was brought to the surface by hot springs. As the superheated solutions rose through the porous siltstone, they redeposited minerals in the rock, forming the present ore bodies.

Jan 1, 1984

By John A. Dearinger, Fred D. Wright, Robert C. Howell

INTRODUCTION The rock mechanics study of the shortwall mining system at Beth-Elkhorn corporation's Hendrix No. 22 Mine is being conducted under contract with the U.S. Bureau of Mines. The objective of the study is to obtain data on surface subsidence over a portion of the mined area, strata subsidence in the mined area, and underground stress changes and displacements in and near natural support elements of the mining system. This study is currently in progress, and only a portion of the results are being presented at this time. The Hendrix No. 22 Mine is located in the moderately rough mountainous terrain of Letcher County in eastern Kentucky. The nearest mine workings to the shortwall area are approximately 1,900 feet distant. The depth of cover over the mined shortwall area varies from 770 feet at Panel 1 to 170 feet at Panel 5 (Figure 1). The strata in the shortwall area is summarized in the three core logs shown in Figure 2. Hole no. 2 is located in approximately the center of the mined shortwall area (Panel 3, Line C, Figure 1). The coal seam in the shortwall area is approximately 4 feet thick and horizontal, although one major ‘roll’ intersects all panels.

Jan 1, 1977

By J. A. Organiscak

Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 µg/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. These two sample sets were termed Group A operations and Group B operations, respectively. This data was compared to identify causes of high occupational silica dust exposures. Analyses of dust-control parameters and geologies revealed only minor differences between these two groups. However, subsequent comparisons of face ventilation design showed considerable differences in silica exposure and silica content between Group A and Group B at the continuous mining machine and roof bolter operator occupations. These differences were minimal when using exhaust curtain ventilation with a dust scrubber. This face ventilation system can benefit operations having difficulty controlling silica dust exposure and silica dust content. The collected data also showed that occupational samples from Group B operations possessed generally higher silica exposures and silica content than similar samples from Group A. The single head roof bolter (helper) possessed among the highest silica exposures and silica contents in both groups.

Jan 1, 2002

By Christopher J. Pritchard

Federal mine safety regulations prohibit the recirculation of face air In a gassy Class III metal-non metal mine. Tg Soda Ash, Inc, operates a 2.0M ton/yr (2.2 million st/yr) underground gassy Class III trona mine In southwest Wyoming, currently liberating approximately 5,700 m3/day (200,000 ft3/day) of methane. Because of the low methane emissions and the incombustibllity of trona, it was decided that Tg would be an excellent environment to test recirculation at a U. S. gassy mine, for possible future use by Industry. A research program was begun with the cooperation of MSHA, the U.S. Bureau of Mines, the University of Utah, and Tg. Initial testing centered around re-using shop air under¬ground. Next, conduct a continuous miner section recirculation test to see how the face contamination was affected by 305m (1,000 ft) and 610m (2,000 ft) recirculation distances. A district test followed to examine the effects of the critical parameter - respirable dust. Finally, a long-term program to study respirable trona dust transportation and deposition in mine airways to plan for district fan siting and effects on face air dust levels.

Jan 1, 1995

By Z. T. Bieniawsk, C. A. F. F. Santos

The effects of artificial weathering on the mechanical properties of the Loyalhanna sandstone have been investigated. Weathering was simulated in the laboratory by subjecting cylin- drical specimens of rock to alternate cycles of wetting and drying (in distilled water at 2O0C 2 5OC and in an electric oven at 105OC t 1°C, respectively). The total number of cycles was 100 and the geomechanical characteristics of the altered material were determined through uniaxial compressive and indirect tensile ("Brazilian") tests, with the determination of axial and trans- verse strains and monitoring of acoustic emission activity (rate and total event count). Moisture content and weight loss data were collected after each cycle and the mechanical parameters (unconfined strength, indirect tensile strength, young's modulus, Poisson's ratio, permanent set and AE/MS activity) were determined for unweathered specimens and after 10, 20, 50 and 100 cycles of wetting and drying. Hypotheses for the effect of weathering on the geomechanical properties of the Loyalhanna sandstone are proposed as reinforced by petrographic analyses carried out for the different stages of artificial weathering. A methodology for assessing the degree of physical weathering of rocks is proposed based on the number of wetting and drying cycles.

Jan 1, 1986