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By Y. A. Topkaya

The placer gold occurrences at Sart Çayl, Manisa, Turkey, the legendary River Pactolus of King Croessus, were evaluated in this study to determine if this deposit contains sufficient recoverable value to justify development and exploitation. The gold occurs both in the upper Neogene conglomerates and the alluvium derived from these conglomerates. The total reserve in the whole region is estimated to be 500 million cubic metres. Samples were taken of the upper conglomerate and in the alluvium in an attempt to determine the amount and the physical nature of the gold. The gold in samples was recovered by screening out barren oversize followed by washing the sand and gravel through riffled sluices. The resulting sluice concentrate was later panned and amalgamated at site. Laboratory cyanidation testing of some samples for control purposes was also done. The average calculated free gold was found to be about 90-100mg/m3 and the size of gold flakes found was quite small. The field as well as laboratory testing of the samples of Sart Çay1 indicated that the potential reserves in this region could only be developed as a sand and gravel operation and the gold could be recovered together with the heavy minerals as a byproduct.

Jan 1, 1984

By Huang Daguang, Paulo Couceiro, Juan Navarro

Mining is typically conducted through a set of interdependent unit-operations, which commonly include drilling, blasting, digging and hauling, in order to deliver the required ore material into the comminution circuit and to remove waste rock with minimum impact in the operation. In such complex environment, the identification of critical paths, and respective interfaces between different unit-operations, are necessary to determine a sustainable long-term operational program. Facing this challenge, adaptive cost optimization strategies are required to increase productivity and revenue while minimizing potential environmental impacts. Since the overall mining efficiency can be strongly impacted by blasting outcomes, an operating method based on the searching of the ideal blast design is required in order to minimize the mine total cost of ownership. The implementation of a consistent continuous improvement program requires specific care in terms of design, control and execution of the different stages of blasting. For that, the application of the most advanced technologies for rock characterization, based on drill monitoring systems, and smart explosive products, allows the improvement and control of blast results by adapting the explosive energy distribution to the rock condition, so as to optimize the performance of downstream stages such as digging, hauling and comminution. This paper describes the application of a heuristic optimization approach, where blast parameters are used as decision variables to evaluate the potential impact of several blasting scenarios on subsequent unit operations, under the continuous ability of modelling, measuring and calibrating operational performances along of the mine cycle.

Feb 6, 2023

By Joseph C. Milbourne

The selection of a suitable nitrate removal process depends on a variety of site-specific chemical and environmental issues. The dominant technologies for nitrate removal include biological denitrification and continuous countercurrent ion exchange. The decision to apply either of these technologies, or both together, depends on the nature of the waste water to be treated. Factors that affect the selection of the biological system include the feed composition and feed temperature. Ion exchange nitrate removal systems are less sensitive to the feed composition but require disposal or destruction of the concentrated pregnant eluate. The paper discusses Tetra's continuous countercurrent ion exchange technology (CCIXTM) and fixed film biological reactor, Denite°. The treatment of the ion exchange pregnant eluant is also discussed.

Jan 1, 1994

A newly developed damage model was used in the study of rock fragmentation mechanisms involved in crater blasting. Simulations show that at the detonation of the explosive charge, a crushed zone around the explosive charge is formed due to compressive failure and then a strong pressure wave is sent out forming a pressurized ring that propagates at the dilatation wave velocity. As the pressurized ring leaves the crushed zone, two tensile stress components perpendicular to the radial stress are developed in response to the action of the radial pressure, causing tensile failure and forming a damage zone around the charge. The formation of this damage zone is quite independent of the depth of the explosive charge provided there is no interference by the reflection from the free face. When the pressurized ring reaches the free face, it is reflected there and causes rock failure on the ground surface that forms another damage zone. Under the simulation conditions, it is revealed that the depth of charge is a factor controlling the relationship between the two damage zones. At a depth smaller than the optimum, the two damage zones coalesce into one and there is excessive rock breakage; otherwise, the two damage zones tend to isolate from each other with the increase in the depth of charge. Calculations of fragmentation indicate that the average fragment size increases and the uniformity of fragments decreases when the depth of charge increases as observed in practical blasting.

Jan 1, 1998

Longwall mining operations have been in place in Australia since the early 1960s. This mining method is currently used to extract the bulk of coal obtained from underground mines in Australia (CSIRO, 2010). Despite the high tonnages extracted the expected utilisation of much equipment remains relatively low. To some extent this level of utilisation is influenced by the variability in conditions inherent in the mining process. This variability in production rates presents challenges to those attempting to design a coal clearance system. The difficulty is to design a system that has sufficient capacity to support production, without over capitalising or incurring high operating costs. The need to allow for a series of largely unplanned events in the design of a coal clearance system makes simulation modelling an ideal technology to employ. Simulation modelling is a methodology that allows a system with interacting components to be modelled over time, while explicitly taking into account unplanned events that may disrupt operations.This paper discusses how dynamic simulation models have been used to assist in the design of coal clearance systems. Typically this type of modelling has been used to look at the likely profile of production rates from the Longwall shearer and to determine how well various proposed combinations of belts, bins and stockpiles would support production.

Sep 26, 2011

By H. H. Gardner

INTRODUCTION THE problem of mechanization is one of the most vital in the minds of Alberta coal operators today. In these times of constantly increasing operating costs, any way of decreasing the cost of a ton of coal must be explored to the limit. There seems no better field for such effort than the successful application of power to the mining and loading of coal. We are fortunate in having neighbours to the south who have made .remarkable progress in recent times along these lines. Higher tonnages per man have resulted in higher wages to the employee and lower cost to the employer. It might seem that our problems could be solved merely by imitating our neighbours. Unfortunately, neither practice nor experience substantiate this conclusion. It is with the purpose of reviewing our accomplishments, as compared with practice in the United States, and at the request of the Prgoramme Committee for this meeting, that this paper is written. The Committee believes that such a general discussion and comparison may well lead to further advances in our mining methods. SUMMARY OF PRACTICE IN THE UNITED STATES A visit to the highly mechanized coal mines of the United States is always most instructive and encouraging.

Jan 1, 1951

By OÆBrien D, Priddle D

In order to avoid costly moisture penalties on coal shipments and to minimise rail freight costs, screen bowl centrifuges were selected and installed in the Mount Thorley Coal Preparation Plant for dewatering fine coal product. The Mount Thorley fine coal circuit consists of desliming the -0.5 mm (ww) fine coal in two stages of classifying cyclones prior to recovery by froth flotation. Provision has been made to bypass the flotation circuit with the classified flotation feed reporting directly to product and the centrifuge dewatering circuit has been designed to handle either flotation feed or flotation product. Major mechanical failures of the gearboxes and the ceramic tiling occurred early in the operation life of the machines which led to design changes being made to achieve satisfactory operation. This paper discusses the operating experience at Mount Thorley with respect to both mechanical and metallurgical performance of the screen bowl centrifuges since their installation in 1985.

Jan 1, 1989

By C. Webb, M. A. Tuck

This paper describes the application of a cable disc elevator to continuous lift ore vertically from underground mines. Application of this system requires the tensions developed within the cable must remain within the carrying capacity of the cable including applicable safety margins. A critical element occurs at starting the system when it is fully loaded which requires the force developed by the system to exceed the static friction forces. This paper describes the laboratory rig developed to investigate the static friction forces. Details of the results of tests on three different ores for both dry and wet conditions are given. These results are discussed.

Nov 19, 2020

By Adam Powell, Salvador Barriga, Matthew Earlam

"The inert anode is a key enabling technology for dramatic energy and emissions reduction in extractive metallurgy. In molten salts, the materials challenge is nearly insurmountable: the anode must conduct electrons at high temperature in a pure oxygen and molten salt environment. A solid electrolyte, e.g. zirconia, between the salt and anode removes the molten salt stability constraint, and can act as a container for a liquid metal anode. This can be liquid silver for oxygen-generating inert anodes, or several metals for natural gas-fueled anodes; it is possible to switch between these modes. The solid electrolyte brings several other benefits: it eliminates molten salt contamination of the anode gas, creates a reducing environment enabling low-cost steel vessels, increases current efficiency, and eliminates carbon contamination of the product. New developments presented here, including current collector and low-cost anode designs, amplify these benefits for producing aluminum, magnesium, rare-earths, and other metals.IntroductionReactive metals such as magnesium, aluminum and rare-earths play increasing roles in efficient transportation and clean energy. In response to new fuel economy standards, automotive OEMs are planning large increases in use of aluminum and magnesium to reduce vehicle weight. Rareearth permanent magnet motors and generators exhibit better power-to-weight and efficiency than induction motors and other designs, making this today's primary motor technology for hybrid and electric vehicles, and for wind turbines. Nickel metal hydride (NiMH) batteries with lanthanum are dominant in hybrids. In 2011, transportation comprised 28.6 out of 103.1 EJ of US energy consumption [1] and 1,845 out of 5,471 million metric tonnes (MMT = 109 kg) CO2e of US greenhouse gas (GHG) emissions [1], creating big targets for economy-wide reductions.Unfortunately processes for making reactive metals for these applications are very inefficient and heavily-polluting. In primary aluminum production, Hall-Heroult cell electricity use [2] is more than double the reaction enthalpy due to heat losses through frozen cryolite side-walls and anode gases, graphite anode plants add significant energy use and GHG emissions [2] (see Table 1). Magnesium is even worse: silicothermic reduction by the Pidgeon process in China produces about 85% of the world's magnesium using coal or coke gas [3]. Chloride electrolysis begins with high-purity MgO and requires carbochlorination or hydrochlorination and costly chloride dehydration [4]—rendered unnecessary for aluminum by the Hall-Heroult cell. Production of neodymium and lanthanum with graphite anodes leads to inconsistent carbon content: small cells make 1 kg batches for analysis, sorting and sale by carbon content, with very high labor and analysis costs. And vertical electrodes give no incentive to reduce anode effect: some reports indicate that China's rare-earth metal industry emits more CF4 and C2F6—with global warming potential (GWP) 6500 and 9200 times CO2 respectively—than China's aluminum industry [5]."

Jan 1, 2014

During operations, mining and metallurgical processes may generate effluents such as tailings water, acid mine drainage (AMD) and seepage and process acid streams. Depending on the type of ore and the metallurgical process, these effluents may contain one or more toxic compounds (eg acidity or alkalinity, cyanide, ammonia and/or nitrate, heavy metals, total suspended solids (TSS), sulfate) in elevated concentrations requiring treatment before their discharge to the environment or recycle/reuse in the process. Natural oxidation of sulfide minerals present in mining wastes (eg tailings and waste rock) at mining sites may generate AMD, which is characterised as a low pH, high acidity effluent containing heavy metals and sulfate. If generation of AMD cannot be controlled and/or prevented, AMD needs to be collected and treated for neutralisation of acidity and reduction of metals and TSS to meet regulated water quality standards. It is important to note that some of these compounds may persist in run-off from mine sites, even after the mine and processing facilities are decommissioned. Treatment of mining and metallurgical process effluents can be accomplished by means of various physical, chemical and/or biological methods. The mode of process application may vary from the use of either specifically designed, controlled and automated facilities or passive systems. Lime neutralisation and precipitation is the most common method used in the mining industry to treat AMD. To reduce the problems associated with disposal and long-term storage of the resulting sludge, the use of a high-density sludge process (HDS) has become a preferred option. The use of other chemical reagents, waste or by-products from other industries, and biological sulfate reduction methods can also be considered as viable options for site-specific situations. Recently, several passive treatment systems have been designed and successfully operated, even in the cold North American climate. This paper will discuss available options and provide insights for selecting a suitable method for a given situation using case studies from projects conducted by Golder Associates around the world over the last decade.

Jan 1, 2006

By D. Saramak, T. Gawenda, A. Stempkowska, Z. Naziemiec

The aim of the paper is to discuss the possibility of producing aggregates with an increased content of regular particles, as well as to present a method of aggregate production which has not previously been used in the industry. Traditional aggregate production circuits require the application of three or four grinding stages (depending on the particle size of the feed), but for fine particle fractions of aggregates, irregular grains occur on average with a content of 10%. The innovative technological circuit can produce the aggregates with the content below 3%, even in a single- or two-stage crushing circuit. Downstream jig beneficiation of such prepared material results in higher separation sharpness, lower probable error index (Ep) and imperfection (I). Keywords: Aggregate production, jig beneficiation, mineral processing, raw materials

Jan 1, 2020

By C. Zhou, J. Srednicki

Electronic systems have been increasingly used in underground mines to improve mine safety. These electronic systems emit electromagnetic (EM) energy which can adversely impact the performance of other electronic systems nearby and thus should be characterized. Researchers at the National Institute for Occupational Safety and Health (NIOSH) characterized the magnetic fields emitted from devices that can potentially interfere with the performance of proximity detection systems (PDSs) and compared the emission levels of these devices to the susceptibility of PDSs. In this paper, we present our measurement results pertaining to this effort. Particularly, magnetic fields emitted from the different orientations of a powered air purifying respirator (PAPR) and two lite trackers are evaluated based on the RE101 protocol specified in the MIL-STD-461G standard. The results show that both devices emit strong magnetic fields which strongly depend on the orientation of the devices. At some frequencies, the maximum emission levels from the two devices exceed both the emission limit given in MIL-STD-461G and the maximum magnetic fields that a PDS can withstand without a failure. The results and findings in this paper can help the mining industry better understand electromagnetic interference (EMI) underground and provide critical scientific data that support mining-specific recommendations to address EMI-related challenges.

Feb 1, 2023

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and mediumterm activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter, and ventilation constraints in order to create more realistic schedules and enhance miners’ health and safety.

Sep 6, 2023

Halide media are considered as suitable alternatives to cyanide for extracting gold and have received much attention lately. The extraction of gold by iodide-iodine mixture has been patented and briefly studied without much attention given to the fundamental aspects of this process. This paper reports recent studies on the kinetics of gold extraction in iodide media, using hypochlorite, iodine and hydrogen peroxide oxidants. The kinetics of dissolution was found to be dependent on the solution pH, reagent concentration and most importantly the iodide- oxidant molar ratio. Without proper control, the gold surface can be passivated due to the formation of solid products. Thermodynamic modelling was carried out to determine the equilibria governing the dissolution process. The formation of AuI solid was also identified as a possible product during the dissolution.

Jan 1, 1992

By Parviz F. Rad

The increased use of tunnel boring machines (TBM) has stimulated laboratory research to optimize the cutting parameters of these machines with the objective of increasing machine efficiency and penetration rate. Laboratory-scale rock cutting experiments have succeeded in identifying many of the important parameters involved in rock-cutter interaction. Although scaling factors may be required to apply the results directly, the concepts developed can be used qualitatively as design guidelines for boring machines. The Bureau of Mines Twin Cities Mining Research Center has recently developed a large-scale rock cutting device (RCD) that will simulate many of the operating parameters of the tunnel boring machines in the laboratory under a controlled environment. The results of the experiments with this device will be directly applicable to the design of TBM's.

Jan 1, 1973

By A. S. Azman

In collaboration with Kennametal Inc. and corry rubber corporation, the U.S. National Institute for Occupational Safety and Health (NIOSH) developed a drill bit isolator to address noise overexposures associated with roof bolting machines in underground coal mines. NIOSH laboratory studies confirmed that the drill bit isolator reduces noise during drilling. Field studies were needed to confirm that a noise reduction could be obtained under working conditions and that the device was sufficiently durable. This paper reports results of field tests of the device conducted at five underground coal mines. Noise reduction was assessed by comparing the operator?s noise exposure during drilling with and without the drill bit isolator. Durability was assessed by recording the number of holes and total feet drilled with each bit isolator until either the test period ended or the device failed. The results from these tests showed that the device is an effective noise control in a mine environment. The field-tested drill bit isolators provided a noise reduction of 3-5 db(A). Of nine devices tested for durability, five exceeded 610 m (2,000 ft) drilled and two exceeded 762 m (2,500 ft) drilled before failure. Durability issues found in the field tests led to final production optimizations that have resulted in a commercially available product for drilling with 35-mm- (1.3-in.-) diameter roof bits and hexagonal drill steels.

Jan 1, 2012

By Marvin L. Kay

In the spring of 1950, just two years after the inauguration of the domestic uranium program by the U. S. Atomic Energy Commission, the company entered the uranium mining and milling business through a newly formed subsidiary, Climax Uranium Co. This was the first venture into a new field of mining for Climax, which became the first old-time mining company, other than the vanadium producers, to become active in the embryo uranium industry. Twenty-five years earlier, Arthur Bunker, president of Climax Molybdenum, organized and operated the U. S. Vanadium Co. at Rifle, Colo. With this background, he viewed the budding industry of the Colorado Plateau with much interest. Upon its formation, the new subsidiary entered into a con- tract with the U. S. Government and the potential uranium-vanadium properties of Minerals Engineering Co. were assigned to Climax Uranium Co. Funds for the construction of a processing plant and working capital were advanced by Climax Molybdenum Co. The old sugar mill building of the Holly Sugar Co. in Grand Junction was leased to house the extractive plant. Construction of facilities, which were based upon a new process developed for the treatment of both uranium and vanadium ores, was completed and the mill was placed in operation early in 1951. Subsequent to that time several alterations were made and the capacity of the plant increased. In terms of recoveries, the plant has proved to be one of the most efficient on the Colorado Plateau

Aug 1, 1955

By H. C. Ray

ABOUT the beginning of 1930, coal preparation had reached the stage where the cleaning of coal by liquid or air had become the order of the day. Since that time many new preparation plants have been installed in spite of the years of depression in the coal industry, and this is indicative of a trend wherein the coal producer found it expedient to manufacture a cleaner product in order to compete with other fuels. It was also about 1930 that, because of the difficulties encountered with fine coal in cleaning plants, dust collectors came into use. Both cleaning plants and dust collectors, therefore, were much discussed at the engineering meetings of the early 1930's. During these meetings the many advantages to be gained through the use of dust- collecting systems were pointed out by Hebley,1 Appleyard2 and others. The great possibilities of new markets for this product were emphasized and discussed at the same time; however, the disposal of the collected dust remained a problem. Since the purpose of dust collecting is to improve the preparation and, consequently, the salability of the coal, it seems illogical to return the collected dust to any of the coal being prepared for market use, as is done in preparation plants that include dust-collecting systems. The logical thing is to dispose of the dust in some useful and practical manner outside of the tipple. As a practical matter, this can be done in one or both of two ways; either by consuming the dust at the mine's own power plant or by marketing the dust direct to the consumer. The latter method not only offers the greatest opportunities, but is the most important, because of inequalities that may exist between the quantity of dust collected and the consuming capacity of the mine's power plant. In considering the more important marketing possibilities, we are confronted immediately with the problems connected with the handling and transportation of so fine a material. It is this problem, rather than the problem of finding new markets, that has been responsible for the lack of progress in the matter of dust disposal. It is the purpose of this paper to point out again some of the potential market out- lets, and also to describe an existing system of handling and transporting coal dust. To the best of the writer's knowledge, this is the first and only operation in this country that has handled fine-mesh coal in bulk so-ton lots direct to the consumer. POTENTIAL MARKETS FOR FINE- MESH COAL DUST In general, the potential market outlets would include any operation of which the pulverization of coal is a necessary part. To be more specific, a few of the better known operations of this type must include: colloidal-fuel plants, briquetting plants, “sea coal” distributing plants, water-purification plants and obviously, pow-

Jan 1, 1944

By C. Y. Wang

China now leads the world in antimony production, having contributed during recent years something over 60 per cent. of the world's production. The history of the antimony industry of China dates back to 1897 when the Tai Shing Co. was formed, under contract with the Hunan Bureau of Mines, for the smelting of the ore to crude; and in 1908 the Wah Chang Mining & Smelting Co. was formed for the smelting and refining of the ore and crude to regulus. The writer was then asked to take charge of the erection and control of this first plant for regulus production in China and has, since then, been more or less connected with the antimony industry in this country. This paper contains the results of many years' experience in connection with the Wah Chang Mining & Smelting Co., Changsha; the Pao Tai Mining & Smelting Co., Wuchow; the Loong Kee Smelting Works and the To-Cheng Smelting Works, Hankow; as well as information gathered from various other small smelters, scattered in different parts of the Provinces of Hunan, Hupeh, Kwangsi, and Kwangtung. An idea of the growing importance of regulus production in this country can be gleaned from the fact that, within a period of about 8 years, the export of regulus from Hunan alone jumped from 3 tons in 1908 to about 6000 tons in 1915; that a production of about 23,000 tons of regulus per year could easily be effected from all the smelters, as tabulated below, most of which were erected a year or two ago under the stimulus of the war booms, if the price at Hankow were to stay somewhere about $900 (Mexican) per ton, half of what it was at its height, thus enabling the utilization of ores from the hinterlands of the provinces; and even under the present ruling of prices and the closing of the less favored smelters, the production of regulus should not be less than 12,000 tons per year.

Jan 1, 1919

By Richard Keith Corbin

INTRODUCTION The purpose of this paper is to assist explorationists and entrepreneurs in deciding whether to invest in gold mining concessions in lesser developed countries (LDCs) and, if so, in deciding which LDCs provide the best opportunity. The first decision is difficult in the face of common notions that foreigners are not welcome - only their money; that the best gold deposits were worked out long ago; that even if you survive the mal- aria, and in spite of 51% control by a national partner, you manage to profit from a new discovery, they will tax your operation to death, or worse yet, nationalize it. Close scrutiny of what happened to foreign investors in LDCs during the “Mexicanizationt” of the 1930's through the "Zambianization" of the 1970's shows that many of these concerns are well-founded historically. But the trend of knowledgeable writers over the past decade seems to be away from this gloomy foreboding, and towards a cautious optimism, based on recently perceptible metamorphoses in certain LDCs' conditions and attitudes. If the explorationist or entrepreneur decides to seize on this apparent opportunity, the second decision -- which of these certain LDCs to invest in -- is doubly difficult, because of the formidable tasks of coming up with a rating system to provide rational comparison, and then gathering enough current, reliable information to apply. To assist in these tasks, a suggested rating system and case studies, respectively, follow a brief review of recent writings on the subject

Jan 1, 1987