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By J. D. Kennedy

The alchemists of old are remembered well for their tireless efforts in attempting to convert various common metals, such as lead, into gold. Not so well known generally, but no less intense, have been the efforts of certain individuals who attempted to manufacture diamonds over the last 100 years. Diamond, the most glamorous and permanent of gems and the hardest industrial abrasive, is carbon in a high-density unique crystalline form with a cubic structure and a density of 3.5. This contrasts with graphite at a theoretical density of 2.2 and possessing a hexagonal structure. Diamond is the hardest natural, material known and until very recently had no close competitor, natural or otherwise, with respect to hardness. The hardness of diamond exceeds that of any other industrial abrasive by a factor of approximately five. The early theories of diamond synthesis were rather vague. Since diamonds occurred in nature, man then looked to nature for clues as to how this might be accomplished. The original known diamond deposits of India are alluvial in character and provided little insight as to how diamond had been formed by nature, for in, these locales the diamonds have been washed by streams or carried by the glaciers long distances from the areas in which they occurred originally in the earth's crust. As a matter of fact, we are told that even today the locations of the mother ground for the Indian alluvial deposits are not known.

Jan 1, 1959

By J. C. Monette

Stripping of gold and silver from carbon is effected by means of two main processes (AARL and ZADRA ). The main rate-enhancing parameter in the stripping of gold and silver is temperature. A secondary rate-enhancing parameter is ionic strength. (1) Stripping is usually conducted within a solution containing sodium cyanide (0.1 -0.5% ) and caustic ( 1 -3%). The development of a chemistry that increases the rate of gold and silver stripping from carbon in a manner proportional to its concentration is described. Its use in atmospheric and pressure strips is also outlined.

Jan 1, 1992

By Christopher Mark

Horizontal stresses are caused by global plate tectonic forces. During 1995 alone, they were largely responsible for closing two U.S. longwall mines. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky, and Alabama. In each case history, a mine encountered roof falls or difficult ground conditions in the headgate, caused by horizontal stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble-free. The paper also discusses detailed measurements made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel with the maximum horizontal stress, as previously thought, but rather 20° in the stress shadow of the gob. Other stress control techniques, including artificial support, are briefly discussed.

Jan 1, 1997

By James E. Brewer

Procedure for approval by the U. S. Army Corps of Engineers of a new source of aggregate is in three phases. Phase 1 consists of an investigation of a quarry or proposed quarry by district geologist and laboratory geologist and/or petrographer. The quarry face or suitable outcrop is logged in detail or, if exposures are poor, cores may be taken to determine whether further investigations are warranted. Phase 2 consists of thorough laboratory testing. Cores and crushed material are subjected to a number of acceptance and quality tests for soundness, absorption, abrasion, reactivity, and other properties. Petrographic analysis is also made. Phase 3 is a physical and economic study of the site and involves determining quantity of stone avail- available, amount-and character of overburden, condition of haul roads and distance to rail shipping point, plant flow sheets and capacity, aggregate sizes produced, and approximate price of material at plant.

Jan 1, 1966

By C. H. McGuirk

Computerized Preventive Maintenance is important in maintaining consistent and efficient operation in any industry utilizing sophisticated and expensive equipment on a continuous basis. At today's large bulk materials handling facilities, the problems of continuous operation of complex machines with their thousands of components exposed to abrasion, dirt, dust and the elements, are intensified and multiplied. Effective preventive maintenance can increase profits. Yet, the number of tasks to be performed is so staggering that it is beyond error-free human capacity. The computer must be an essential ele¬ment in any efficient and economical preventive maintenance system. Computerized preventive maintenance techniques have been successfully used in many fields, usually involving highly skilled and specialized personnel working under favorable and controlled conditions. Now, The Pittsburgh & Conneaut Dock Company has developed and is applying a computerized preventive maintenance system that is applicable to the bulk materials handling industry. The "system" has taken many years of intensive effort to develop and has been time-tested and proven during the past years on equipment handling materials with rugged physical characteristics and corrosive and abrasive qualities, under some of the most adverse weather conditions on the Great Lakes.

Jan 1, 1976

By S. D. Hill

State-of-the art precious metal recovery practice uses cyanide leach solutions to extract the valuable constituents from ores, wastes, and tailings. Activated carbon is then used as an adsorbent in either a carbon-in-pulp system or counter-current flow columns to concentrate and recover the precious metals. Existing techniques for recovering precious metals from carbon prior to the precipitation or electrowinning of the metal involve either the use of dilute aqueous hydroxide solutions at elevated temperature and pressure or, as in a more recent method, the use of a strong cyanide soak followed by a water strip solution at an elevated temperature. Despite past Bureau efforts in the area of precious metal recovery, the ex- traction of gold from pregnant leach solutions remains the most serious drawback in carbon-in- pulp and heap leach processing of low-grade ores containing precious metal values. A second disadvantage in the current practice is the interference in adsorption and desorption that occurs due to the presence of other heavy metal cations in cyanide leach solutions. Specific objectives of current Salt Lake City Research Center precious metals research are to develop less energy intensive and more economic methods for recovering gold, silver, and by- product metals from low-grade resources. To meet these objectives, we are investigating noncyanide leaching reagents, ion exchange resins, solvent extractants, and novel electrowinnlng procedures.

Jan 1, 1984

By A. K. Ghose

The increasing application of roadheading machines in the coal industry has prompted the development of an appropriate selection methodology for such machine applications in specific locales. Accurate geological sections and comprehensive rock testing are required for all machine tunneling. Using suitable geotechnical parameters and index tests, sensitive both to excavability and standability of the strata, a classification scheme has evolved to help evaluate the rock mass vis-a-vis application of a given weight-class of roadheading machine. The classification parameters include point load index, brittleness, abrasiveness, average crack density, and ground water, which with assigned numerical ratings, lead to a quantitative global rating of the rock mass. For each rock mass class, the selection of an appropriate roadheading machine is recommended. The paper illustrates the application of the rock mass rating system and also describes simple index tests for evaluating the classification parameters for brittleness and abrasiveness. Manuscript not received in time for publication.

Jan 1, 1983

By Fabian Laumen, Sunny Schoone, Felix Leaman, ELISABETH CLAUSEN

The paper evaluates the attenuation behavior of acoustic emission (AE) signals in four different materials used in marine environments. The study aims to identify materials with the highest and lowest AE signal attenuation, providing insights into wave propagation and structural monitoring in deep-sea mining applications.

Dec 1, 2023

By Dongxu Jia, Chen Cao, Shuangwen Ma, Jun Han, Huibin Ma

Coal bump, or coal burst, is one of the catastrophic disasters in underground coalmine. Among them, approximate 80% of recorded destructive burst events were occurred in mining roadway. The bump panel is often formed by hard coal seam and hard main roof; however, the cause and course of the bump events are not understood yet. This study provides a fundamental theory for the causality and progress of a coal bump event occurred in longwall roadway. Considering hard roof condition commonly existed in bump panels, we think that the abutment pressure induced by suspended roof behind the working face is the trigger of a coal bump event occurred in the roadway. Once high abutment pressure is concentrated on the hard coal seam around the working face, the roof and the coal around the working face form a seesaw-like structure, which leads the roof in front of the working face moving upwards. The movement of roof uplifting in front of the working face is a well evidenced phenomenon in practice, namely, roof rebounding, which causes unloading of the normal stress on the roof-coal interface around the roadway. A rib coal block bump mechanical model has been developed to establish the critical equilibrium equation of the coal block. Result shows that, the force source of coal bump is the horizontal ground stress perpendicular to the rib surface; and the slippage of the coal block is caused by the unloading of the normal stress acting on the roof-coal interface. Based on the causality and consequence theory of coal bump developed in the paper, several new prediction and prevention measures have been developed, including roadway design and in-tunnel reinforcing methods. The commonly used prevention measures in present have also been discussed. This paper presents a comprehensive explanation of coal bumps occurred in longwall roadways, from abutment pressure at working face forming seesaw structure to roof rebounding leading slippage of the rib coal mass into roadway, which provides a fundamental theory for coal bump causality mechanism and prediction and prevention technology.

Apr 26, 2022

By L. C. Atkinson, E. A. Azrag, T. M. Hanna

The results of using a simple analytical solution and a relatively complex numerical model to estimate ground water inflow to an open pit mine are compared. The analytical solution assumes lateral, radial flow to a fully penetrating pit in an idealized confined aquifer, whereas the numerical model simulates fully three-dimensional flow to a partially penetrating pit from a water table aquifer. The latter is a more realistic simulation of the problem, but the former method is significantly easier to use. Comparison of the results obtained with the two methods for some typical hydrogeologic conditions encountered in mining yields ratios between them in the range of 0.2 to 0.6. These values can be used as a coefficient in the Pit Flow analytical solution to produce reasonable estimates of in-flow even when there are significant differences from the idealized conditions implicit in its application.

Jan 1, 1995

By Frederico J. Price

This paper describes the production of a specific iron oxide pellet that has given very good and consistent results as feedstock for HYL-Process Direct Reduction Plants. The sponge iron originated from these pellets has been used for the economic making of almost 15 million tons of low carbon steel via electric arc furnace meltshops. An overview of mining, benefication, pelletizing direct reduction and steelmaking for this case is given with emphasis on the characteristics of the self-fluxing oxide pellets. HYL Operator and management training is described.

Jan 1, 1979

By D. K. Marjaniemi

The U.S. Bureau of Mines inventoried and characterized mineral sites and production plants within 200 km of the border in both the U.S. and Mexico. Sources of information included the USBM Minerals Availability System, the USBM Automated Mineral Information System, the USGS Mineral Resources Data System, the Mine Safety and Health Administration Address/Employment File, and the literature. Three hundred seventy-eight major construction material and industrial mineral properties were identified and characterized in the U.S. and Mexican parts of the Borderlands. Sixty-six major metallic mineral properties were identified and characterized in the Mexican part of the Borderlands.

Jan 1, 1996

By J. B. Cabezas

The metallurgical processes that are frequently applied today use strong solutions and are of alkaline, acidic, or organic nature. These play a very important part in recovery of values from many ores. These solutions are of such a chemical nature that they are generally corrosive, flammable, and contaminating. In most cases, they are highly dangerous to the environment. Within the extractive metallurgical industry, it is also very common to have to deal with the handling of contaminating solutions with a high content of cyanide, arsenic, mercury, lead, copper kerosene, acid and many other components whose temporary or permanent confinement within the process must be adequate and absolute.

Jan 1, 1986

By Kambhampati C. Rao, Cecil Lue-Hing, Nabih P. Kelada, William B. Willborn

improvements in the analytical techniques for cyanide speciation can furnish useful information about the behavior of the different cyanide species in the receiving environment. This could be of help to the environmentally concerned public and the regulatory agencies in the assessment of cyanide limits for effluents, stream quality, and land disposal of cyanide bearing wastes. In addition the ability to distinguish the free cyanide and the weakly bound cyanide from the strong ULTRAVIOLET IRRADIATION UNIT (LAMP, COIU3' HOUSING) FIGURE 1 complexes, as well as transformation to thiocyanate is also needed by different industries, such as mining and metal finishing, etc., to evaluate the efficiency of several processes. Cyanide has been used for the recovery of gold since the late 19th century. Although cyanide leach solutions are mostly recovered and used again, a large quantity of cyanide bearing wastewater becomes unfit for use and has to be treated before it can be released into natural waterways.

Jan 1, 1992

By E. De Souza, J. F. Archibald

"Many underground mines use cemented backfill to mitigate environmental effects associated with tailings disposal. The large energy needs associated with mine backfilling and cement production operations create significant CO2 and Greenhouse Gas Emissions. This paper introduces post-consumer glass as an alternate, equally effective and lower cost binder agent strategy for cement in backfill that may be implemented to assist in reducing solid waste production, lowering energy costs, and restricting Greenhouse Gas Emissions. Extensive engineering testing, consisting of pipe flow loop tests and strength tests, has been implemented in order to demonstrate the technical feasibility of process integration within industry. An economic analysis has demonstrated that glass is competitive in cost relative to cement and a socioeconomic study has further indicated that the utilization of glass in mine backfill would create a new market for waste glass that requires less processing and reduces costs."

Jan 1, 2005

By Greg Blerie

The requirements placed on belt conveyors grow increasingly complicated No longer is it sufficient for the conveyors to merely move material from "Point A" to "Point B. " Now these systems must be able to produce a specified flow, guaranteeing a plant can operate as scheduled without peaks and valleys in material flow and production rate. In addition, the conveying system must provide effective control, to minimize the problems and costs associated with the escape of fugitive material these problems include unscheduled shutdowns, premature equipment failures, regulatory headaches, poor neighbor relations, and health and safety issues. The key to accomplishing these goals is the loading and discharge of the conveyor belts. Fortunately, new designs for the chutes that accomplish conveyor loading and discharge can move material efficiently, without blockages and while minimizing the amount of dust generated This innovation is the development of engineered flow chutes

Jan 1, 2004

By M. B. Díaz Aguado

Traditionally, the practical evaluation of a mining project for a potential investment has been made considering mainly technical aspects. But the concept of sustainable development has introduced significant changes in the factors analyzed to make the final decision. This paper proposes an empirical evaluation of a project considering not only technical, economic and financial parameters, but also associated risks and other intangible aspects, such as political considerations, stability in the legal frame, social factors and environmental issues. The proposed methodology is practical and easy to apply for project management. Among its main advantages, the following could be quoted: using this evaluation two different projects or locations of a same project can be compared, future behaviors could be predicted, the index incorporates a new approach to specific mining projects and this perspective could also be applied to other projects with environmental and social impact, such as civil works or industrial projects.

Jan 1, 2007

By Pierre Mousset-Jones, Felipe Calizaya, Malcolm J. McPherson

The algorithm presented in this study determines the combination of fans that provide all working districts of a mine with predefined airflows at the minimum operating cost. It is based on an existing ventilation simulator, VNETPC, and a set of linear equations associating fan pressures and the added resistance of regulators. Two assumptions are undertaken: (1) fan locations are predetermined and (2) the number of working districts is equal to or greater than the number of fans. By means of this algorithm, the optimal solution to an n fan ventilation system may be found after n + 1 simulation runs.

Jan 1, 1987

By L. E. Krys, K. D. Harrison, S. M. Nordwick, C. G. Anderson

Since 1984, nitrogen-species catalyzed pressure leaching has been utilized at the Sunshine Mining and Refining Company for the recovery of precious metals from a refractory sulfide concentrate, The process operates without the use of cyanide. The plant is now the only industrial-scale commercial application of this technology. Since the inception of the process, changes have been implemented to improve efficiencies and throughputs. Two of these changes, the replacement of nitric acid by sodium nitrite and a concentrate regrind, have recently been implemented. This paper will discuss the outcomes of these recently patented plant-process changes. In particular, a comparison between the previously used method and the new leach method is made. Also discussed is the potential applicability of the process to other materials. A companion publication (Anderson, Harrison and Keys, 1996) indicates possible mechanisms responsible for the success of these process changes.

Jan 1, 1997

By J. D. Miller, Jon J. Kellar

Researchers in flotation chemistry have long sought to describe collector adsorption phenomena in greater detail including kinetics, orientation and interactions between adsorbed species. Now a quantitative description can be made in-situ using FTIR internal reflection spectroscopy. Details of the adsorption process at the surface of mineral crystals, machined into internal reflection elements, can be described from first principles, provided the refractive indices, incident angle, and wavelength of light are known. Collector orientation can be established based on spectral characteristics of plane polarized and perpendicular polarized light. Examples of the use of in-situ FTIR internal reflection spectroscopy are given for the sapphire-sodium dodecyl sulfate system and for the fluorite-sodium oleate system. It is expected that quantitative in-situ analysis of collector adsorption reactions by FTIR internal reflection spectro-scopy will continue to grow in importance and will provide an important new dimension in our understanding of flotation chemistry.

Jan 1, 1989