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By Mauricio Coto

Three bidirectional static load tests (BDSLT) were executed on bored concrete piles, as part of the permanent foundations for two buildings sites located at the Sabana, San Jose, Costa Rica, separated at a relatively short distance of about 1 km. Unit skin friction values obtained for both sites, principally for the “Lahar” layer show that in general, friction pile capacity from the tests is higher than anticipated per static calculations from soil borings geotechnical parameters correlations. Results from the tests were also compared with dynamic load tests (DLT) executed at other two sites in the surrounding area, and with a Finite Element (FE) Analysis that model soil-pile interaction for one of the projects. On the other side, some construction issues were detected on one of the sites, which negatively affected the end bearing capacity, but being that pile friction was higher than anticipated, the required overall pile capacity was accomplished. The BDSLTs results of these tests help to better understand the geotechnical behavior of the soil layers in the Sabana. Moreover, they also show that is possible to optimize the design and construction of other bored pile supported buildings and structures on the zone.

By Adamiak Z. P

A study has been made of the influence of bentonite type on the wet strengths, dry strengths and drying rates of pressed iron ore pellets. Measurements of the influence of bentonite on the kinetics of growth of pellets are also reported. The results show that bentonite decreases the rate of growth of pellets and the drying rates of pellets while increases are observed in both wet and dry strengths. The results have been interpreted in terms of the physical and chemical charact- istics of the bentonite and the suitability of a given bentonite for particular pelletising operations has been discussed.

Jan 1, 1973

By D. R. Dance

The Resonant, or as it has more commonly come to be known the 'Sonic' Pile Driver, dates back to the early 1960's, when prototypes were produced by Charlie Guild, of Providence, Rhode Island, and A1 Bodine of Los Angeles, California, these were later to be developed into the unit known as the BRD 1000. Based on this initial work, the Shell Oil Companies of Sonico and The Resonant Pile Corporation, produced and operated 30 of these BRD 1000 machines, which were used throughout the U.S.A. and Canada on a wide range of foundation projects. Subsequent to this, Raymond International and G K N, of England, operated units on programs; the G K N units being of slightly modified configuration. In 1973 Hawker Siddeley Canada Ltd., acquired the license for the Pile Driver and related systems with the intent of promoting the use of the machines to install support pilings on the Alyaska Pipeline Project, but this did not materialize due to problems with the oscillator. After radical redesign and field testing of the oscillator system the unit was employed on a number of test projects principally in Northern Canada and Alaska.

Jan 1, 1987

By Ajoy K. Singh, B Mohanty, P K. Singh

A study was conducted to investigate the damage potential to underground multiseam openings caused due to vibration generated by open-pit coal mine blasting. The objective was to recommend optimal explosives weight per delay to be detonated in open-pit blasts to ensure the safety and stability of underground openings. Sixteen blasts with varying charge weights and initiation sequences were conducted at Samleshawari open-pit mine and eighty four blast vibration data were recorded in the Hingir Rampur underground colliery in India. Analysis of vibration data showed that roof of the underground openings vibrated with much higher amplitudes compared to those in pillars and floors. The amplifications of vibration in the roof at the junction were upto 4.3 times the pillar vibration. It was observed that coal chips detached from roof when the peak particle velocity reached 131 mm/s or higher. The vibration magnitude recorded was higher in upper-seam openings than in belowseam openings. Rapid attenuation of vibration was recorded in below-seam openings at similar locations. Appropriate particle velocity-charge weight-distance equations were established to calculate the safe explosive weight per delay to be detonated in open-pit mine for the safety of multi-seams workings of underground mine. The support for the galleries and junctions were further modified for the working seams to ensure greater safety.

Jan 1, 2011

By H. E. Lee, P. C. Feddersen

Greenockite is the only known cadmium mineral of importance. It occurs rather universally, in minor concentrations, as a secondary mineral in sphalerite deposits. The world's cadmium output is obtained through the processing of metallurgical by-products, largely from the treatment of residues from electrolytic zinc, retort zinc and lithopone plants. These sources are supplemented by the processing of fumes from lead and copper smelting operations. The development of modern selective flotation practice in the decade 1920-1930, which permitted the economical mining of complex lead-zinc ores, resulted in significant increases in the quantities of cadmium entering lead smelting systems. Being closely related to zinc as to occurrence, properties and production, most detailed description of cadmium recovery methods are to be found recorded in connection with zinc metallurgy. Other than occasional articles pertaining to particular operational procedures, literature offers but little in the nature of a balanced survey of lead smelter cadmium recovery practices. While many of the basic operations described for the recovery of cadmium from zinc by-products are applicable to the treatment of lead plant products, the inherent problems involved differ widely. In general the cadmium content of related by-products from routine lead smelting operations is present in lower concentrations, exists in a less soluble state and is associated with both a greater quantity and a greater variety of detrimental impurities. To cope with these problems, lead smelter practices are found to follow the general outline: Preparatory Processing 1. Concentration operations 2. Sulphation operations Cadmium Plant Processing 1. Leaching operations 2. Purification operations 3. Sponge precipitation operations 4. Metal recovery operations 5. Refining and casting operations As in the case of related zinc plant operations, cadmium recovery practices at lead smelters are not standardized. They not only vary as to type, but also extent. Depending upon prevailing conditions, lead smelter cadmium operations range from simple concentration campaigns, for the purpose of sufficiently "up-grading" products for shipment elsewhere, to complete processing steps for the production of refined metal. Preparatory Processing The cadmium content of lead smelter receipts is low and, as a rule, proportionate to the zinc content; the usual range of cadmium contained being of the order of 0.01-0.05 pct. Were it not for the low boiling point of cadmium, such small concentrations would, no doubt, be lost in the large tonnages of slag, metal and other smelter end products. However, the ready volatility of cadmium and its compounds at prevailing lead smelting temperatures results in its concentration in fractional portions of fume collected. This collected fume comprises a circulating load within the smelter system. Thus, the cadmium content of blast furnace fume* increases with each successive circulation until an equilibrium value is reached when the sum of the cadmium losses, due to handling and in slag, waste gases and other end products, becomes equal to the intake as ore. With ore receipts averaging, say 0.03 pct cadmium, the concentration value obtainable, through fume circulation in a routine manner, approaches 10-12 pct. In such operations, cadmium concentrations in blast furnace fume of from 3-5 pct are readily .attainable. However, the concentration gain beyond this range, with each additional circulation, is progressively decreased as a result of mounting losses occurring through handling and in end products. Therefore, to avoid excessive cadmium loss and to enhance the ultimate concentration anttainable, it is customary practice to isolate blast furnace fume at some intermediate cadmium content for special concentration procedure. The most common type cadmium concentration "campaign" involves special smelting operations wherein a relatively high portion of blast furnace fume at 3—6 pct cadmium is incorporated into the sinter charge. This type practice is roughly illustrated by the diagram on p. 111. Cadmium fume collected from lead blast furnace operations is not amen-

Jan 1, 1950

By M. Sheffield

This paper presents a technique lor predicting the flow of oil, gas and water through a petroleum reservoir. Gravitational, viscous arid capillary lorces are considered, and all fluids are considered to be slightly compressible. Some theoretical work concerning the fluid flow in one-, two- and three-space dimensions is given along with example performance predictions in one- and two-space dimensions. INTRODUCTION Since the introduction of high speed computing equipment, one of the goals of reservoir engineering research has been to develop more accurate methods of describing fluid movement through underground reservoirs. Various mathematical methods have been developed or used by reservoir engineers to predict reservoir performance, 193-5,7,8 The work reported in this paper extends previously published work on three-phase fluid flow (1) by including a rigorous treatment of capillary forces and (2) by showing certain theoretical mathematical results proving that these equations can be approximated by certain numerical techniques and that a unique solution exists. DISCUSSION The method of predicting three-phase compressible fluid flow. in a reservoir can be summarized briefly by the following steps. 1. The reservoir, or a section of a reservoir, is characterized by a series of mesh points with varying rock and fluid properties simulated at each mesh point. 2. Three partial differential equations are written to describe the movement at any point in the reservoir of each of the three compressible fluids. All forces influencing movement are considered in the equations. 3. At each mesh point, the partial differential equations are replaced by a system of analogous difference equations. 4. A numerical technique is used to solve the resulting system of difference equations. Capillary forces have been included in two-phase flow calculations.1,4,8 The literature, however, does not contain examples of prediction techniques for three-phase flow that include capillary forces. Where capillary forces are considered, each of the three partial differential equations previously discussed has a different dependent variable, namely pressure in one of the three fluid phases. Therefore, three difference equations must be solved at each point in the reservoir. Where large systems of equations must be solved simultaneously, an engineer might question whether a unique solution to this system of equations actually exists and, if so, what numerical techniques may be used to obtain a good approximation to the solution. It is shown in the Appendix that a unique solution to the three-phase flow problem, as formulated, always exists. It is also shown that several methods may be used to obtain a good approximation to the solution. The partial differential equations and differenceequations used are shown in the Appendix. Matrix notation has been used in developing the mathematical results. Two sample problems were solved on a CDC 1604. They illustrate the type of problems that can be solved using a three-phase prediction technique. SAMPLE ONE-DIMENSIONAL RESERVOIR PERFORMANCE PREDICTION A hypothetical reservoir was studied to provide an example of a one-dimensional problem that can be solved. Of the several techniques available, the direct method of solution as shown in the Appendix was used. The reservoir section studied was a truncated, wedge-shaped section, 2,400 ft long, with a 6' dip. (A schematic is shown in Fig. 1.) This section was represented by 49 mesh points, uniformly spaced at 50-ft intervals. The upper end of the wedge was 2 ft wide, and the lower end was 6 ft wide. The section

Jan 1, 1970

By Scott Dupont

Due to the scarcity of miners, and the necessity of decreasing the cost of mining, the Phelps-Dodge Corporation, Stag Canon Branch, at Dawson, [ ] New Mexico, decided to try, by various methods of mining, to increase the tonnage of coal mined per man, per day. With this in view, they first tried mining on a 250-foot face, maintaining the track at the face and using six to eight men shovel- [ ] ling. These men were able to aver age from ten to twelve tons each per, day when they were loading, but with

Jan 1, 1926

By Joanne G. Petrini

ISO 26000 Unique Process Unique Personality ?Almost 10 years in the making ?What type of standard is this? Different type of ISO Standard ISO 26000 Structure and Substance ?Principles ?Core Subjects ?Implementation Guidance ISO 26000 Impact ?Same old, same old? ?So Is there really anything NEW? ?Should I care??

May 1, 2011

[Adams, Dell H Consolidation Coal Co., 43 Denver Tech Center, Englewood, Colo. Adams, Douglas K General Electric Co., Box 2331, Denver, Colo. Adams, Kenneth L Peabody Coal Co., 33 Carnation Dr., Belleville, Ill. Aggen, Marshall J Marathon LeTourneau Co., Rt. 4, Box 1188, Henderson, Texas Ahlborg, William Joy Mfg. Co., 580 Denver Club Bldg., Denver, Colo. Albrechtsen, Ray H Mt. States Resources Corp., 2330 So. Main, Salt Lake City, Utah Alford, Eugene C Pittsburg & Midway Coal Mining Co., 2025 TenMain Center, Kansas City, Missouri Allen, Earl W Mine Safety Appliance Co., 5708 East 7th St., Tucson, Arizona Alston, George Mine Safety Appliances Co., 400 Penn Center Blvd., Pittsburgh, Pa. Amerman, Richard W Utah International, Inc., Box 155, Fruitland, New Mex. Anderson, G. A Walker Bank & Trust Co., Drawer M, Price, Utah Anderson, John S Utah International, Inc., 550 California St., San Francisco, Calif. Anderson, Robert Mine Safety Appliances Co., 1881 West North Temple, Salt Lake City, Utah]

Jan 1, 1973

By Avi Shonberg

With the advancement of offshore wind farm projects towards deeper waters and larger wind turbine generators, founda- tion solutions other than the monopile have received increasing attention over the past 5 years. Monopiles are the most commonly used foundation solution for offshore wind turbines, with 82% in European waters founded on monopile foundations (EWEA, 2019). However, 2018 saw a record number of suction bucket jacket (SBJ) structures, which consist of a three-legged jacket sup- ported by a suction bucket at each leg (Figure 1), installed for offshore wind. applications. SBJs have now been installed successfully at the Borkum Riffgrund 1, Borkum Riffgrund 2 and Aberdeen Bay offshore windfarms. Suction-installed foundations, referred to in this paper as suction buckets, suction caissons, suction piles or suction anchors, have been widely used in the offshore industry since the early 1980s for a range of offshore applications predominantly as anchors for floating offshore structures - where they are "the most widely used anchor types for deep-water mooring applications" (McCarron, 2011). Suction buckets, installed using pumps that generate suction forces by creating a pressure difference between the inside and outside of the bucket, allow for the installation to be undertaken with minimal noise and without the use of mechanical force. Therefore, a key difference between suction-installed foundations and other foundation types is that the installation design, which must consider the soil type, soil strength and installation specific risks (for example, soil stratification with significant differences in permeability) may have a direct influence on the dimensions of the foundation. While the number of SBJS installed for offshore wind applications has increased significantly in recent years, the installation process for SBJ struc- tures is yet to become standard practice and is considerably more complicated than the installation process for mon- opiles. This paper provides a brief

Jul 1, 2022

By Daojin Cao

The chemical components in the saturated aqueous solution of ammonium dimolybdate (ADM) were investigated at room temperature by comparative Raman spectroscopy. In order to explore the further detailed results, a new method of qualitative and half quantitative analyses, based on the main vibrant frequencies and the intensity ratio of the strongest peak to the second strongest peak recorded in Raman spectrum of saturated aqueous solution of ammonium heptamolybdate tetra hydrate (AHM), was put forward and attempted to analyze the chemical components of saturated aqueous solution of ADM. The results showed that there was obvious difference between Raman spectrum of saturated aqueous solution of ADM and that of ADM, but there were good relationships between Raman spectrum of saturated aqueous solution of ADM and Raman spectra of the three samples including AHM, the saturated aqueous solution of AHM and monomolybdate ion in aqueous solution. It was found that aggregated dimolybdate ion ({Mo2O72-}n)did not exist in the saturated aqueous solution, and was changed into heptamolybdate ion (Mo7O246-) and monomolybdate ion (MoO42-), which were in equilibrium each other, but the distribution ratio of heptamolybdate ion was larger than that of monomolybdate ion. In addition, Raman spectral pattern of saturated aqueous solution of ADM was reported.

Jan 1, 2006

By R. C. Ferguson, Harlowe Hardinge

Laboratory and plant data covering 12 different operations show that lower than "standard" ball mill speeds increase grinding efficiency. In the case of high pulp-level mills, the gain is so great that the increase in capital cost of the larger lower speed mill will pay for itself in less than a year's time. THE object of this paper is to show the economic advantage of operating ball mills at relatively slow speeds. Although many operators know that grinding costs are reduced by operating mills at low speeds, they seldom do so for a variety of reasons. When capital is limited, first cost is of primary importance, and installation of the less costly, highspeed mill is favored. When materials are in short supply, as during a war period, capacity rather than economy is the primary consideration. Existing mills are then speeded up to provide the desired increase in capacity, and new mills are purchased without consideration of maximum grinding efficiency. When the mill speed is increased to secure more production, the increase in grinding costs is often obscured by the total benefit derived from the additional output. This increase in grinding cost is seldom recognized as being sufficient to be worth correcting. For these reasons one may be lead to the erroneous conclusion that slow-speed operation is only occasionally applicable. The effect of mill speed on grinding efficiency has been studied in laboratory tests."! The results of some of these tests are given in tables I and I1 and fig. 1. In these tabulations, batch tests using ore charges of 125 to 200 lb were considered comparable to high pulp-level operation and charges of 50 to 100 lb comparable to low pulp-level operation. For the high pulp-level operation, these tests indicate the existence of a maximum in efficiency for operation at a speed of 50 pct of critical, both for the soft (dolomite) and hard (chert) ore. In low pulp-level operation, a decrease in speed increases the efficiency of grinding dolomite; no maximum of efficiency appears in the range of speeds tested. The results with chert were inconclusive. If the performance of large mills is indicated

Jan 1, 1951

By Harlowe Hardinge, R. C. Ferguson

Laboratory and plant data covering 12 different operations show that lower than "standard" ball mill speeds increase grinding efficiency. In the case of high pulp-level mills, the gain is so great that the increase in capital cost of the larger lower speed mill will pay for itself in less than a year's time. THE object of this paper is to show the economic advantage of operating ball mills at relatively slow speeds. Although many operators know that grinding costs are reduced by operating mills at low speeds, they seldom do so for a variety of reasons. When capital is limited, first cost is of primary importance, and installation of the less costly, highspeed mill is favored. When materials are in short supply, as during a war period, capacity rather than economy is the primary consideration. Existing mills are then speeded up to provide the desired increase in capacity, and new mills are purchased without consideration of maximum grinding efficiency. When the mill speed is increased to secure more production, the increase in grinding costs is often obscured by the total benefit derived from the additional output. This increase in grinding cost is seldom recognized as being sufficient to be worth correcting. For these reasons one may be lead to the erroneous conclusion that slow-speed operation is only occasionally applicable. The effect of mill speed on grinding efficiency has been studied in laboratory tests."! The results of some of these tests are given in tables I and I1 and fig. 1. In these tabulations, batch tests using ore charges of 125 to 200 lb were considered comparable to high pulp-level operation and charges of 50 to 100 lb comparable to low pulp-level operation. For the high pulp-level operation, these tests indicate the existence of a maximum in efficiency for operation at a speed of 50 pct of critical, both for the soft (dolomite) and hard (chert) ore. In low pulp-level operation, a decrease in speed increases the efficiency of grinding dolomite; no maximum of efficiency appears in the range of speeds tested. The results with chert were inconclusive. If the performance of large mills is indicated

Jan 1, 1951

By D. E. Sherwood

Recent developments in high torque hydraulic rotary rigs has lead to the construction of secant bored pile walls by rotary drilling methods in circumstances where earlier methods were difficult and in some cases impossible. The evolution of secant bored pile wall construction is described including classical, rotary drilled and continuous flight auger construction methods. The paper then details the restraints which have been created in recent inner city redevelopment, many of which were not relevant in the early days of the technique. Typical examples of walls are presented to show the adapatability and advantages of the secant bored pile wall method. A number of in-situ retaining wall construction techniques are then compared in detail with regard to relative cost, technical quality and practicality.

Jan 1, 1989

By Zbigniew Smieszek, Ryszard Chamer, Ryszard Prajsnar, Zygmunt Kurek

"Lead-containing wastes processed at the IMN’s Division in Legnica originate mainly from dry and wet dedusting installations of the technological lines for copper production. These are lead dusts and lead-zinc dusts characterised by the specific properties resulting from the chemical composition of the Polish copper concentrates. Besides lead, they contain many accompanying metals and impurities such as zinc, copper, sulfur, chlorine, potassium, sodium, and also bituminous substances. Processing of lead-containing dusts is conducted in the installations of rotary-rocking furnaces heated with gas-oxygen burners fitted with auxiliary systems for cleaning process gases and refining re-circulating dusts. The processing technology utilizes innovative process and technical solutions enabling disposal of lead-containing wastes from copper metallurgy and from non-ferrous metals industry according to the BAT recommendations and to the guidelines specified in integrated permission. In this paper, the main technological aspects of processing lead-containing dusts at the IMN’s Division in Legnica have been presented.IntroductionCrude lead is obtained in Polish lead metallurgy from various primary and secondary materials, such as Zn-Pb concentrates, lead-bearing dusts of copper metallurgy and battery scrap. In zinc smelter Miasteczko Slaskie S.A. crude lead is produced from sulfide and oxide Pb-Zn concentrates in ISP process. Orzel Bialy S.A. and Baterpol Ltd. produce crude lead in short rotary furnaces in the process of smelting products of mechanical battery scrap separation– desulfurised or not desulfurised paste and metallic fraction. KGHM Polska Miedz S.A. and IMN Divison in Legnica produce crude lead in rotary furnaces in the process of smelting of polymetallic dusts and slimes from copper production processes."

Jan 1, 2008

By Nicholas S. Lynn

Introduction Borne out of the need for reductions in capital expenditure and increased production, several new and innovative carbon systems have been developed for small precious metal heap leach operations throughout the United States. Perhaps the most important aspect of these systems is the carbon column. Though diverse in design, these columns can be categorized into three basic types. The first is known as the gravity flow type or Cortez type. As the name indicates, solution flows via gravity, throughout 4 to 6 columns which are arranged in a normally stepped con- figuration which is conventionally upflow in design. The second type, known as the vertical column, is an arrangement whereby flow is established through pressurization in an upward manner, throughout 4 to 6 columns in a vertically stacked configuration. This arrangement is typically intended for use with small portable heap leach operations and employs a semi-continuous mode thus preventing gravity from occurring. The third type and newest development in carbon columns is an arrangement whereby the solution flows throughout 4 to 6 columns placed in a side by side configuration and pressurized by a single feed pump (Figure 1). A unique aspect to the third type, is that the adsorb and desorb cycles are accomplished in the same column, due to a fixed carbon charge. An in-depth analysis is warranted due to numerous advantages of this arrangement, and is therefore the subject of this paper. Advantages and Variations One advantage to the third type of carbon column is the fact that initial capital expenditures and operating man- power requirements are reduced. Another advantage is that the system can be made fully portable up to a 0.0315 m3/s (500 gpm) capacity. Systems of this nature are operational at several sites. Above this flow rate, the system's portability is one which can be maintained, but disadvantages (i.e. larger diameter carbon column and greater weights) far outweigh the advantages. There are several variations in each of these systems which allow for unique operation. For example, carbon columns made highly portable, can be moved from unitized heap leach operations to central stripping facilities. Although this method has been used in Colorado, transportation of these units has been known to be quite cumbersome. If distances exceed 5 km (3.2 miles) then special front-end loaders are required. This limits heap locations to within 5 km (3.2 miles) of the central processing facility. Another example transports the carbon charge from the heap leach locations to a centralized processing facility; this method is quite effective. For the past 5 years one mine has employed this technique of transporting carbon in 907 kg (1 ton lots), in DOT containers, towed by company pick-ups. This operation uses a vertical column with a 907 kg (1 ton) carbon charge. A third example uses static carbon columns with fixed carbon charges. Carbon Adsorption System The carbon adsorption system (Figure 1) is fed by a single preg solution feed pump. This feed pump pushes the preg solution through all four to six fixed charged carbon columns, which are on line. The sequencing of the carbon columns is achieved using valves. Expansion of the carbon charge is dependent upon the carbon selected. The carbon typically used is a 6 x 12 mesh size, with a nominal flow rate of 0.00135 - 0.00138 m 3/s (22-25 gpm) per square foot of carbon, based on a 40% bed expansion. With 8 x 16 mesh size,

Jan 1, 1987

By Clayton V. Deutsch

Indicator Kriging (IK) is being commonly applied to mineral resource assessment problems. More recently, indicator simulation has also been used for sensitivity analysis and difficult change of support problems. The essential theory underlying indicator geostatistics has not changed since its introduction 10 years ago; however, the last decade has produced many important developments in its implementation. The objective of this paper is to consider some of the more important implementation details. Examples from the Porgera gold deposit in Papua New Guinea are used to illustrate the steps in an indicator geostatistical study and the importance of various implementation decisions. Specifically, in many precious metals deposits the continuity of the grades is typically quite anisotropic. This anisotropy varies in both magnitude and direction throughout the deposit. Building a model of this anisotropy can considerably improve the local kriged or simulated points. One approach to build this model is presented. In addition, there is typically more than one mineralization style and geological rock type; the spatial character of the mineralization can be quite different within each geological rock type. The rational treatment of anisotropy and geological subdivisions is common to all mineral resource assessment procedures; the importance of this qualitative geological information is not diminished with more sophisticated techniques such as indicator kriging. This paper presents an overdue comprehensive look at the practical aspects of indicator methodology. Many of the techniques and procedures documented in this paper have been developed during the course of detailed mine feasibility studies.

Jan 1, 1992

By Kenneth P. Neumann

The development of the Cyprus Thompson Creek Molybdenum Deposit near Challis, Idaho, began in 1967 when the first mining claims were staked on the intrusive rock outcrop. Exploration drilling continued for the next 14 years. During 1978, a decision was made to develop the deposit. In December, 1980, approval of the Environmental Impact Statement was received and construction of facilities and waste rock removal began. By the middle of 1983, 126 M metric tons of rock had been removed and all facilities were completed. The high work ethic of Cyprus Thompson Creek employees combined with innovation has made the mine one of the most efficient in the United States today.

Jan 1, 1983

By A. K. Sinha

Ever since electricity was introduced, electrical injuries and electrocutions have continued to occur regularly in coal mines. An analysis of the two hundred cases of electrocutions which occurred during 1956 to 1970 indicated that over 50 percent of the incidents were caused by the ineffectiveness or lack of electrical grounding. Research shows that various types of arbitrarily designed ground beds are in use and that the ground resistance and current are often very high and subject to wide seasonal variations. The results of a recent research are discussed in this paper.

Jan 1, 1980

1. Book reviews Geophysical and geochemical techniques for exploration of hydrocarbons and minerals, edited by M. Sittig. (Reviewer: J. Keenan) Separation procedures in inorganic analysis. A practical handbook, by Roland S. Young. Charles Griffin, 1980. £23.00. (Reviewer: R. Murray-Smith) 2. Historical reprints Theinin~rs dictionary, by William Hooson. £14. Discovery of subterraneal treasure, by Gabriel Plattes. £12. Fodinae Regales (The Mines Royal), by Sir John Pettus. 3. De Beers' booklets Amborite - a remarkable new cutting material, by De Beers Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Booklet, 14 pp., free of charge. Natural and synthetic micron powders, by De Becrs Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Leaflet, 5 pp., free of charge. 4. New books Nickel in the environment, edited by J. O. Nriagu. New York, Wiley, 1980.928 pp. $65. Underwater minerals, by D. S. Cronan. London, Academic Press, 1980. 364 pp. $57.50. Data conversion integrated circuits, edited by D. Dooley. New York, Wiley, 1980.298 pp. $26.95 (cloth), $17.50 (paper). 5. NIM reports Report 2057 A mineralogical study of the Rooibokkop- Boschhoek copper deposit in the Marble Hall area. Report 2069 A utomatic setting of the distance between sample and detector in gamma-ray spectroscopy. Report 2070 The prereduction of chromites from the UG-2 Reef. Report 2075 The optimization of some of the conditions for analysis by spark-source mass spectrometry. Report 2082 A survey of the literature on gravity separation.

Jan 1, 1981