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By Malcolm D. Flavel

Recent research into the mechanisms of crushing processes has led to the establishment of new criteria for the effective design and operation of comminution plants. This paper reviews this work and gives examples of the productivity gains and cost benefits that have been achieved in the practical application of these findings.

Jan 1, 1988

By Sergio Godoy P.

The Los Bronces porphyry copper deposit is located in the high Andes of Central Chile. Ore is mined from several tourmaline breccias and from an earlier porphyry. After years of experience in the geostatistical estimation of reserves in different zones of the ore body, we believe that success lies in considering the evaluation as an integrated process beginning with the analyses of the drilling density and sampling methodology, ending with the critically important reconciliation between the estimated and the actually extracted ore, in general, when errors or differences occur, focus is centered in the calculation stages of geostatistics. However, this paper demonstrates that all the evaluation stages are equally important and require the direct and continuous geologic input to ensure the best possible estimate within the frame of the geologic constraints.

Jan 1, 1992

By S. P. Lucido, I. Iwasaki

The potential of controlling heavy metal ions in effluents from discontinued mining operations and waste rock piles has been investigated. A fresh water green alga, Cyanidium caldarium, was found to have the potential to remove Cut' from solutions while exhibiting high tolerance to acid conditions which are commonly encountered in copper-nickel mine drainage. The process has the potential for application as a low maintenance metal decontamination system. The growth requirements and copper removal characteristics of this microorganism are described.

Jan 1, 1991

By M. Phillip Jameson, Paul Sennett

The beneficiation of kaolin by flotation has been practiced on an industrial level since 1961. A brief history of industrial kaolin flotation is given, with a description of the various processing schemes used by the companies that practice kaolin flotation. Some of the areas where improvements could be made in the beneficiation of kaolin are given.

Jan 1, 1989

By J. Dorsey

In 1910, Colonel Boyce Thompson, who owned Inspiration (now Cyprus Miami) and various other mining interests, formed the Magma Copper Company and leased the Silver Queen claims around Superior, Arizona. At the same time, he purchased other claims around the Silver Queen claims from what was then called the Magma Mine. The mine continued to operate until 1982 when Newmont Mining Company, who owned Magma Copper Company, shut down the operations due to high costs and low copper prices. When Magma was spun off by Newmont as an independent company in 1987, new studies of Superior were started. It was clear from these studies that the mine had been shutdown and over 1400 employees laid off for two basic reasons: first, as a resu1t of a mine plan that was technically flawed and second, be-cause of very high production costs mainly due to the low productivity from a very high cost work force. During 1989 a plan was formulated to re-open Superior with the determination to over-come the problems that resulted in closure. A new mine plan was developed and a management style developed that promotes team work and high productivity.

Jan 1, 1992

By A. V. Glembotsky, N. A. Greshnova, V. P. Seregin, V. A. Glinkin

Based on a new alternative depressant of zinc sulphide - dimethyldithiocarbamate- modern technology has been developed for the treatment of complex polymetallic ores. In addition to its general function (depression of sphalerite and iron sulphides to some extent), this double-acting reagent is a promoter for galena and silver minerals. Laboratory and plant tests, as well as industrial experience have all shown consistently higher silver recovery to the lead concentrate as compared with sodium cyanide, resulting in less pollution and a safer environment

Jan 1, 1995

By J. Owens

The methodology of quarrying changed significantly in the Indiana Limestone industry in the sixty years between September 11, 1941, the date of the Pentagon groundbreaking ceremony and September 11, 2001 when the building was damaged by American Airlines Flight 77. So too, though to a lesser degree, did the machinery and methods used to fabricate the stone. The rededication ceremony on September 11, 2002 marked the end of the Phoenix Project, as the rebuilding effort was named. The story of this remarkable project illustrates what the American construction (and Indiana Limestone) industry can accomplish when working toward a common goal.

Jan 1, 2004

By CADEN VITTI, Barbara J. Arnold

Mine tailings, the byproduct of mining and mineral processing, are increasingly mass produced as a result of increased demand for metals and minerals as well as the advancement in technology that allows for the exploitation of lower-grade ores. Lower grades can increase the volume of tailings that may contain new gangue minerals that should be evaluated for the presence of critical minerals and other valuable metals. The practice of reprocessing, while relatively new, is crucial to reducing environmental damages, obtaining valuable critical minerals from waste, and contributing to more sustainable repurposing and disposal methods. With the increase in tailings dam failures in recent years, there is a large motivating factor in remining and removing the potential hazard to benefit the safety of potentially impacted communities. In analyzing the perspectives of various domestic and international studies, this literature review will determine the feasibility of reprocessing and reutilizing mine tailings waste for a more sustainable future while exploring current practices that have benefitted ecosystems and communities.

Jan 1, 2022

By CADEN VITTI, Barbara J. Arnold

Mine tailings, the byproduct of mining and mineral processing, are increasingly mass-produced as a result of increased demand for metals and minerals as well as the advancement in technology that allows for the exploitation of lower-grade ores. Lower grades can increase the volume of tailings that may contain new gangue minerals that should be evaluated for the presence of critical minerals and other valuable metals. The practice of reprocessing, while relatively new, is crucial to reducing environmental damages, obtaining valuable critical minerals from waste, and contributing to more sustainable repurposing and disposal methods. With the increase in tailings dam failures in recent years, there is a large motivating factor in remining and removing the potential hazard to benefit the safety of potentially impacted communities. In analyzing the perspectives of various domestic and international studies, this literature review will determine the feasibility of reprocessing and reutilizing mine tailings waste for a more sustainable future while exploring current practices that have benefitted ecosystems and communities.

By Gh. Crutu

The handling of radioactive waste deposits from factories that produce chemical fertilizers is a difficult problem, but has a great significance for soil quality and for the environment. The Romanian legislation has produced law and normative acts concordant with EU regulations for prevention and protection, and also for environmental contamination control with radionuclides. The soils and agricultural plants in the vicinity of phosphogypsum deposits are radioactively contaminated; the annual variability of the respective radioactivity values is demonstrated by annual records. Residual radioactivity monitoring determines the presence of radioactive ions in the soil and cultivated plants: wheat, maize, sunflower, as well as the spontaneous flora. The results obtained lead to the conclusion that ecological restoration works must be executed for degraded soils due to impacts of radioactive materials.

Jan 1, 2007

By Malcolm J. McPherson

Mine shafts that are used as primary ventilation routes are different in their airflow characteristics to other subsurface openings because of the aerodynamic effects of guide rails, buntons, pipes, cables, ropes, and shape, size and velocity of conveyances. As many shafts contribute heavily to the overall resistance of a mine ventilation circuit, it is important to be able to predict the resistance of a planned shaft with reasonable accuracy. This paper describes part of a study on the ventilation characteristics of hoisting shafts, conducted for the Basalt (Nuclear) Waste Isolation Program (BWIP). Methods of quantifying each of the four components of shaft resistance are developed; namely the shaft walls, fittings (buntons, pipes, etc.), the skips or conveyances, including the dynamic effects of their motion, and shaft stations. Practical guidance is given on ways of reducing the shaft resistance. The paper concludes by giving a step by step procedure for the ventilation aspects involved in the design of combined hoisting/ventilation shafts.

Jan 1, 1987

By Clarice L. Amaral, Ricardo Melamed

Clay-coating has been used as an environmental technology tool for the immobilization of toxic elements. The mechanisms of arsenate retention in clays suggest that not only the system pH is of fundamental importance in the process but also the character of metals and ligands that compose the electrolyte system. The goal of this study was to investigate the interactions between system pH and electrolyte ions on the retention of arsenate in an Oxisol soil. The sorption of arsenate decreases with the increase in system pH, reflecting the competitive sorption of arsenate with OH groups. Solutions containing Ca tend to favour the immobilization of arsenate in a relatively broad pH range.

Jan 1, 1998

By Roland W. Rammler

In recent years, the crude oil reserves of the world have increased at the same rate as the consumption. A Consideration of the global figures suggests that adequate supplies of petroleum will be available during the next decades. On the other hand, it in a fast of economic and political significance that the reserves in the industrialized countries increase much more slowly than in the developing countries. In Western Europe the reserves have even decreased. At the present time, about 70 % of the petroleum reserves of the world are in the Middle East and in Africa in regions in which political arises are prevalent or impending. For the industrialized countries, the discrepancies between the consumption and reserves in various regions of the world are a strong urge to investigate whether oil can be recovered from other sources. The situation will probably not be changed to a large extent by the discovery of oil in the north of Alaska. The main starting materials for the production of synthetic crude oil are coal, oil shale and tar sand. In North America, where the consumption of petroleum increases more rapidly than the reserves, there are enormous deposits of each of the three materials. This fact is another incentive toward the utilization of these unconventional oil reserves, which provide a reliable basis for a supple of energy for a long time to come.

Jan 1, 1970

By Robert E. Ennis

The somewhat misnomered "continuous" face section is in most mines today still far from perfect continuity. Achieving uninterrupted flow of coal from the mining machine to the outside has been a long sought for goal. Clearly, the largest problem to be solved in continuous mining today is one of increasing the cutting time of the miner. Full machine utilization can never be achieved with the new high capacity miners, as long as their performance is tied to that of the shuttle car. Figure No. I illustrates the point at which shuttle car haulage distance determines unit productivity rather than the productive capacity of the miner. Continuous mining is never realized. A recent development has proven, however, that truly continuous mining and haulage is possible. The Bell & Zoller Coal Company working with the Research and Development Department of Hewitt-Robins Inc. developed and perfected a new mining system which offers advantages in terms of increased productivity at reduced mining costs and enhances the safety of personnel at the face. This new system involves the use of two pieces of equipment that form a unbroken link, at all times, between the mining machine and the mine belt haulage system. These pieces are a Mobile Bridge Conveyor, and an extensible panel conveyor. The following areas of discussion will be covered during the review of this development. I. The design and operating features of the new system. 2. Its application in underground mining 3. The performance of the system to date 4. Operation and maintenance cost considerations 5. Safety features of the system

Jan 1, 1965

By R. E. Scheffel

Most supergene copper heap leach operations today employ forced-aeration, irrespective of ore grade. Unfortunately, there is little published quantification of its benefit. There is a natural desire to strive for the ideal chemical kinetics. The reality, however, is that physical mechanisms control the commercial extraction rate. This paper presents the performance of a number of operations, their operating conditions and physical ore characteristics, which contribute to non-ideal solution distribution and variable extraction rate. Regardless whether one uses forced-aeration, commercial experience to date suggests it is prudent to design for longer leach cycle times to ensure the production target is met.

Jan 1, 2006

By S. Zhou

Since the hypothesis of coal and methane outburst mechanism based on elastic mechanics gives no consideration to time, it can not give a satisfactory explanation to the outburst occurrence and its development. A creep mathematical model of coal containing gas has been set up through creep tests and analysis under the condition of tri-axial compression. And the model can explain the phenomena of coal and methane outburst successfully. The tests proved that there is no essential difference between the rheological properties of prone outburst coal and non-prone outburst coal. Outburst can take place in any kind of coal if the rheological conditions of coal containing gas are met. The creep mathematical model provides a basis for establishing a comprehensive index of coal and methane outburst possibility.

Jan 1, 1991

By Laszlo Valentyik

Heavy media separation (HMS) is one of the most widely used gravity methods in the mineral industry. The feed is separated, according to the specific gravities, into two products; float (light) and sink (heavy) particles. The universal acceptance of the process is due to simplicity, efficiency and robustness for ease of control. However, if optimum separation is desired during the operation of heavy media plants, a delicate balance of a number of variables is essential. Among the variables, the two which are generally the most frequently checked and controlled are specific gravity and consistency of the medium. The latter is a function of the settling rate of the media. The medium is generally made up of finely ground ferrosilicon, magnetite, galena, shale, quartz sand, clay contaminants and water. The frequently present clay in the medium acts as a stabilizing agent, since the coarse heavy medium solids (called media) would quickly settle if they were mixed only in water. Clay concentration of the medium varies between 3-7% by height (1,2). Although clay is essential for reasonable media stability, clay concentration greater than 7-8% imparts too high a viscosity to the medium, and the feed cannot accurately stratify and therefore separate into the required products. To be on the safe side, plant operators clean the medium from most of the clays, and would rather work at a lower stability than have a very viscous medium on their hands. The most recent advance in the area of consistency control rlas made by the introduction of atomized (spherical) ferrosilicon (3). This extended the upper limit of the use of ground ferrosilicon from 3.3 to approximately 3.6, broadening the range of the optimum operating conditions. A viscosity control method was also worked out by the use of low cost additives which lower viscosity while retaining a favorable low setting rate (4). Recently (5) polymers have been successfully used in oil well drilling muds then the requirements were mainly to suspend and transport cuttings during the periodic shutdowns and dril1ings respectively. The rheological properties of these polymer suspensions are such that they present an infinite viscosity to

Jan 1, 1971

By Gordon R. Wicker, Peter V. Avotins, Steven S. Ahlschlager

Laterite ore slurries exhibit Bingham plastic behavior and can be characterized by the magnitude of their yield point and Bingham viscosity. These two parameters are affected by ore composition, solids concentration, and temperature and are used to predict the pressure drop in pipelines and heat transfer coefficients in shell-and-tube heat exchangers. In cycloning of laterite slurries, the calculated cut size is corrected by factors obtained from the rheological parameters.

Jan 1, 1979

By Timothy J. L. Haley

The population of the Rhondda underwent a spectacular rise as energy requirements increased in the mid-nineteenth century. The rapid expansion in the demand for coal transformed the population from a few hundred sheep farmers in the eighteenth century, into a thriving coal-based economy of some 168,000 inhabitants in 1924. Cochrane (1958) put forward the idea that the differential migration of more healthy men from the Rhondda Fach during the period since the peak of population in 1924, had resulted in a respiratorily-impaired residual population. This idea was used to explain the reduced survival of miners & ex-miners aged 55-64 years from this valley as compared with a similar group from Leigh in England. Using the proportional hazards regression model of Cox (1972), a comparison is presented of the exact twenty-year mortality of migrant and non-migrant miners & ex-miners and non-miners from the Rhondda Fach. The analysis makes allowance for the pattern of migration throughout the twenty-year period and adjusts for the confounding influence of variables such as age, occupation, and category of Simple Pneumoconiosis. The results indicate that contrary to expectation, any effect of migration upon mortality is manifest only at higher ages. Furthermore, for these men, the migrants have worse survival than the non-migrants. Also, contrary to expectation in the light of work by the British Coal Board (Soutar et al, 1982) there is no evidence of increased mortality amongst men with category I simple pneumoconiosis. INTRODUCTION [The Background] In September 1950, the Medical Research Council's Pneumoconiosis Research Unit at Penarth in South Wales initiated a study of lung disease in the smaller of the two Rhondda Valleys - the Rhondda Fach. At that time, the primary interest was in assessing the possible role of pulmonary tuberculosis in the aetiology of the serious (complicated) form of coal-workers' pneumoconiosis, i.e. Progressive Massive Fibrosis. The Rhondda Fach is situated in South Wales, some 25 km north-west of Cardiff. It is a narrow winding river valley about 12 km long, and approximately 1 km wide. The name means Little Rhondda; there is a corresponding Big Rhondda - the Rhondda Fawr. Together, these valleys make-up most of the Rhondda Municipal Borough. Following the initial survey in 1950-51, there have been several follow-up studies of this population. In addition, amongst numerous other investigations to unravel the aetiology of coal-workers' pneumoconiosis, Medical Research Council teams studied various other (sample) population groups, particularly in the industrial areas of the adjacent Aberdare Valley, and in Staveley and Leigh in England. The agricultural areas of the Vale of Glamorgan in South Wales, and Annandale in Scotland were also studied.

Jan 1, 1993

By Bengt L. Stillborg

INTRODUCTION This paper summarizes the result of a two and a half year research program. The objective of the research was to develop a fundamental understanding of the Rib-in-Roc method. Through the development of a new model technology, namely three-dimensional physical models which powerfully exploit the results of dimensional analysis Stillborg, Stephansson and Swan (1), it has been possible to establish the contribution to both permanent and immediate stabilization of a large underground opening pre-reinforced by the Rib-in-Roc method. Using the results from these physical models and earlier work by Stillborg and Stephansson (2) and Åkesson (3), a conceptual synthesis is given in this paper so demonstrating the Rib-in-Roc method to be a practical working system of pre-reinforcement. DESCRIPTION OF THE RIB-IN-ROC METHOD To give the reader an idea of how this method of pre-reinforcement is performed, a short description will be given, Figure 1. Before any full-scale excavation takes place an entry is made in the host rock and rib raises are driven around the proposed opening. These raises are made at a spacing that is dependent upon rock quality; an opening in poor rock needs more ribs per length of opening. As the ribs are driven they are used as a site from which very competent rock bolting can be done. As a rib is excavated it is filled with reinforced concrete. Finally after having in this way reinforced the zone around the proposed opening, (a reinforced arch is formed) the displacements are automatically controlled as the opening is being excavated. Using this method openings with a span of 50-60 meters (160-200 ft) and a height of 60-80 meters (200-260 ft) are likely to be realised.

Jan 1, 1979