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By Jean E. Tilden

An investigation of several trace elements distributed among sulfide minerals from deposits located in the southeastern United States was conducted. The deposits investigated are distributed within both the Blue Ridge Province and the Piedmont Province, which are contiguous geographic provinces. Twenty five deposits were examined;' eleven in the Blue Ridge Province and fourteen in the Piedmont Province. Figure 1 shows the locations of deposits investigated. In the deposits investigated, the mineral phases examined were pyrite, pyrrhotite, chalcopyrite, and sphalerite. These phases were chosen because of their relatively widespread occurrence, although no pyrrhotite was seen in the Piedmont Province. A total of 116 polished surfaces of ores were prepared, and mineral phases were collected from these surfaces for analysis. Samples were analyzed for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. A total of 372 analyses were made. Trace elements were determined by atomic absorption spectrophotometry following standard procedures. In this study, trace elements are defined as those elements which are present in the mineral but which do not affect the chemical formula for that mineral. Lead is considered as a trace element only in ores where little or no lead sulfide could be identified as a distinct mineral phase.

Jan 1, 1972

By J. -M. Lopez-Cuesta, C. Petter, B. Otazaghine, M. Batistella, R. Sonnier

"Kaolinite is a dioctahedral aluminosilicate widely used as paper filler and coating pigment. At the best of our knowledge, kaolinite is not widely used in polymer industry. Therefore, in this study, the flame retardant effect of kaolinite in ethylene vinyl acetate copolymer (EVA) and polypropylene (PP) were studied and compared with an alumina trihydrate (ATH) and Talc. Cone calorimeter results shows that the weight percentage of ATH in EVA/ATH composites must be at least 50 wt. % in order to reach an improvement in fire retardancy in terms of pHRR. In the case of EVA/kaolinite, even with 35 wt. % the pHRR is largely reduced. Comparing PP/Talc and PP/kaolinite composites at 30 wt. %, both fillers leads to same reduction in pHRR with a slightly better performance for PP/kaolinite composites. In both cases an intumescent behavior of kaolinite composites was observed that could slow the rate of the rising degradation products, allowing radical recombination reactions. Also, it was observed that kaolinite forms a protective layer on the surface of the samples, which could insulate the material. These behaviors (intumescence and formation of a protective barrier) could reduce the transfer of the degradation products to the flame and explain the better performance of kaolinite composites. INTRODUCTION The use of mineral fillers as fire retardants in polymer matrix are well known and widely studied [1]–[10]. Aluminum and magnesium hydroxides (respectively ATH and MDH) are the most widely used inorganic fire retardants. To achieve fire retardancy with these mineral fillers, about 50-60% loading is required which decrease the physical properties of the composites. The fire behavior of composite EVA has been the subject of many studies [4], [7], [9]–[15]. EVA copolymers are commonly used in the cable industry, due to their high ductility, even at high loading rates. In such applications, the flame retardant systems should be introduced into the polymer to improve the fire reaction. Many flame retardant systems have been tested but the most used industrially relates to formulations based on hydrated mineral fillers (aluminum hydroxide and magnesium hydroxide). Their low cost and reduced fumes generation explains their success. However, to obtain good performance with this type of flame retardants, it is necessary to incorporate high levels (up to 65 wt %), which severely impact other properties such as processability and mechanical behavior. The main modes of action of these flame retardants are the dilution of the gas phase, the endothermic decomposition and a barrier effect created by the inorganic oxide residue which may be improved by the incorporation of other components such as montmorillonites, silicas or talcs."

Jan 1, 2015

By William P. Blacutt

This paper describes the strategy, the struggles, and the obstacles encountered during the last two years in the ongoing process to capitalize Vinto. The effort involves the offering of a vertically integrated business package composed of the tin and antimony smelters along with the two principal tin mines of the country. Capitalization: Bolivia's Innovative Approach for Privatization, the Vinto Case provides a summary of hard-earned lessons. These experiences can be success- fully implemented in other nations committed to transforming their state natural resource sector.

Jan 1, 1998

By Mollie Hunt, William Riley, Russ Downer, Kate Willa Brown Requist, Víctor O. Tenorio, Geoffrey Gill

One of the first activities after returning to the Moon will be finding sources of water and materials for the construction of human settlements and other infrastructure. There is evidence of the existence of deposits in the bottom of craters at the South Polar region and in flat areas around. Based on geological data from the Moon, a block model representing a deposit or icy regolith has been defined in the vicinities of Shackleton Crater, with unique characteristics of shape, thickness, and water contents. A mine plan utilizing surface mine modeling software for ore extraction from an open pit- type of excavation to a delivery point near a water processing facility is proposed, with monthly, quarterly, and yearly schedules. Production results, dashboard charts and progress of the topographic changes are also presented.

Feb 1, 2024

By G. Kazonich

The high costs and environmental problems associated with making iron and steel in the United states is driving the development of new technologies to replace the blast furnace. A prototype reactor incorporating rocket technology was designed and built. This rapid rate reactor was operated successfully and consistently made iron metal. Minus 32s-mesh magnetite particles could be reduced to iron metal in less than 50 ms in a high temperature flow through reactor. Iron product was recovered inside the reactor and in a downstream cyclonic separator. The results of typical operation and how parametric changes affected the reduction of iron ore concentrates are discussed.

Jan 1, 1993

By Yohan Cha, Eun-soo Hong, Gye-Chun Cho

"Rapid population growth and scarcity of space have led many developed cities to bury supply facilities. In line with this, utility tunnels have been employed in Korea since the 1970s. However, approximately 70% of structures were installed more than 20 years ago, in response to the issue of ageing, tunnel enlargement has been proposed. The aim of this study is to investigate geo-mechanical behavior due to tunnel enlargement. Tunnel enlargement methods have been researched to suggest a optimal method. A finite element analysis is conducted to evaluate ground behavior by the expansion of internal space. Vertical displacement and settlement trough width are investigated according to ground stiffness and different enlargement size. It was determined that displacement is affected by the enlargement size and ground stiffness. Based on the deformation results obtained from the numerical analysis, it is possible to predict ground behavior and stability upon tunnel enlargement. INTRODUCTION Various infrastructures such as electric lines, communication lines, gas pipes, and water pipes are jointly accommodated by utility tunnels. These utility tunnels improve the aesthetics of urban areas and help ensure stable supply. The first utility tunnel in Korea was adopted in 1978 and new tunnels are still being installed with the development of new suburb cities. Nevertheless, about 70% of the utility tunnels were installed over 20 years ago and they are still being used through ongoing repair. Moreover, 90% of utility tunnels were installed before 1995. With aging of the nation’s utility tunnels various problems such as concrete deterioration and scarcity of capacity have arisen. As solution, reconstruction has been considered. Reconstruction can enlarge space and improve the performance by replacing existing structures. For reconstruction, two routes have been proposed: underground excavation and cut and cover. In order to avoid traffic problems caused by road occupation and civil appeals during construction projects, underground excavation is the more attractive option. Tunnel enlargement methods have been classified (Seo et al., 2008; An et al 2013) and major considerations during tunnel enlargement have been outlined (Beak et al., 2007). Enlargement construction cases on road tunnels around the world were introduced (Kim et al., 2012) and the deformation curve during tunnel expansion was proposed to investigate the range of protection that should be offered (Kim et al., 2008; Beak et al., 2011). However, tunnel enlargement technology is limited to road tunnels and railway tunnels. Hence, a study on shallow box tunnel enlargement is required for practical application."

Jan 1, 2016

Coal has traditionally been an integral part of life in Kentucky. Coal mining produces a large part of revenue for the Commonwealth of Kentucky and provides a significant number of jobs to the residents of eastern (less in western) Kentucky. Recently, however, the coal industry of Kentucky has had to endure many hardships. The Clean Air Act set forth sulfur dioxide emission standards which have severely affected much of the coal mining industry in Kentucky, because much of the coal mined in Kentucky has a high sulfur content. In this paper, the background around the effects of Clean Air Act on the coal industry is introduced. The economic and social effects of the Clean Air Act on the Kentucky coal mining are addressed.

Jan 1, 1993

The paper describes a practical methodology based on numerical modelling for the prediction of progressive failure of underground mine stopes with cable bolt support. A case study of the 40-761 stope at Kidd Creek Mine, Timmins, Ontario is presented. The stope was mined by blasthole open stoping in 1986 as a lead stope within a mining block between 36-1 and 38-2 levels. Initially designed to peak at 38-2 level, the stope back caved upwards approximately 40m towards 36-1 level. Cable bolts were installed above the stope from 36-1 level after caving had begun. The stope eventually stopped to cave when the falling rock mass encountered a sufficiently high cable density. The paper provides details of the geomechanical data and modelling results of the case study. Numerical modelling is carried out using a finite element package known as e-z tools which has, among other things, a special cable/rockbolt simulation capability.

Jan 1, 1994

By Craig Smith

California is the nation's leading producer of diatomite products. The Lompoc Mining District in Santa Barbara County is the world's largest source of commercial marine diatomite. Grefco Inc. exploration has defined a large embayment of commercial grade freshwater diatomite in Shasta County. Exploitation of this massive deposit could substantially increase California's diatomite production.

Jan 1, 1980

By Robert M. Dreyer

Although lateritic deposits have long been a principal source of bauxite and are becoming an increasingly important source of nickel, the problems in the evaluation of such deposits are not generally understood. In the evaluation of lateritic bauxite and nickel deposits, there are many similarities, but there also. are significant differences. It has long been recognized that laterites with commercial concentrations of trivalent metals represent the ultimate in the intense leaching of tropical soils. Any factors which effect-the rate of soil leaching will effect the form of local lateritic concentrations. Although the most intense leaching generally occurs on somewhat elevated areas of gentle relief where there is a free downward flow of rain water, the- effect of local rock structures in effecting varia¬tions in soil metal concentrations has-not been well understood - primarily because the laterite forms a masking blanket over the rocks from which the laterites were derived. All of the-factors which facilitate downward movement of water may effect greater surficial concentrations of trivalent metals. Such features as zones of fracturing, zones of greater rock permeability, and areas of karst topography may, therefore, be responsible for greater leaching. The variations in rock structures and the vagaries of ground water flow pat¬terns impart, to the laterites, rapid lateral and vertical variations in thickness and metal concentrations. Because of such rapid

Jan 1, 1970

By John A. Folinsbee

Placer Dome Canada owns and operates the Campbell mine and mill at Balmertown, in the north western corner of Ontario. The mine operates at 1.3 kt/d (1,500 stpd). It produced more than 9.3 t/a (300,000 oz/year) of gold during the last three years. Changes to the gravity concentration circuit have resulted in a 10% to 15% increase in gravity recovery. The mill head grade at the Campbell Mill is relatively high, averaging 18.5 g/t (0.54 oz/st) over the total reserve tonnage. During the past several years, the head grade was averaging close to 20 g/t (0.6 oz/st). Before 1994, gravity concentration was achieved by using a combination of conventional mineral jigs and tables. Jig concentrates were upgraded on shaking tables to produce a concentrate, which was refined to bullion. In May 1994, management decided to buy two Knelson CD 760-mm (30-in.) concentrators. The objective was to replace the existing jigs and increase gravity gold recovery by up to 15%. Gravity recovery with jigs averaged between 30% to 35%. Gravity recovery was anticipated to increase to about 50% with the Knelsons.

Jan 1, 1997

By N. Sahin, M. Can, Z. Ekmekçi, Y. Öztürk, Ö. Biçak, I. B. Çelik, B. Kocabiyik

"In this paper, a case study from Çayeli Bakir Isletmeleri A.S. (Rize, Turkey) about the selective flotation of copper minerals from sphalerite is discussed. Çayeli Cu-Zn Sulfide Ore contains different ore types, such as yellow ore, clastic ore, bornite-clastic ore, bornite-yellow ore, and black ore. For some of these ore types, selective flotation of copper and zinc is very difficult presumably due to presence of secondary copper minerals such as bornite, chalcocite and covellite, and also surface oxidation. These factors affect Cu-Zn selectivity due to activation of sphalerite particles in the ore during the process. The main objective of this work was to improve Cu-Zn selectivity by optimization of the pulp chemistry for different ore types of Çayeli ore. After preliminary flotation tests investigating effects of different chemical conditions, a plant survey was performed to determine the plant performance and sources of the problems when problematic bornite-clastic ore is treated in the plant. Various chemical conditions are tested in the laboratory scale test for better depression of sphalerite in copper flotation circuit. Combination of Na2S+ZnSO4+MBS was found to be the most effective depressant scheme. INTRODUCTION Ore variability is one of the most important factors affecting performance of a process plant both in short and long term planning. The geometallurgical modelling becomes a common tool to determine ore variability problems and develop the most efficient solution during life of mine (1, 2). Flowsheet design and equipment selection and sizing are usually done based on the results of ore variability test works. However, in some cases ore variability may not be foreseen during the design stage and therefore the solutions should be developed based on the existing flowsheet and equipment in the plant. In this situation, ore characterisation, problem statement and diagnostic testing should be applied step by step. The problem could be due to changing feed grade, mineralogical characteristics, grindability and surface characteristics when flotation is involved. The variability in feed grade with fixed mineralogy can be handled with relatively simple modifications (i.e. adjusting throughput or equipment capacity) in the plant. Variability in ore mineralogy is the most complex and difficult problem to tackle. Because, mineralogical variations could bring variations in mineral composition, texture and liberation. These variations can potentially lead to the variations in grindability of the ore and flotation behaviour. Variations in grindability are usually managed by optimization of operational parameters in grinding circuit, as it would be costly to replace the existing equipment in the circuit (3). The variations in flotation behaviour are mainly due to variations in mineral types and distribution, texture and surface oxidation. One or all of these factors could be observed in a flotation operation. Therefore, a comprehensive investigation both in plant and lab scale should be conducted for definition of source of the problem. The testwork to solve the problem and retrieve the performance is planned and conducted depending on the source of the problem (4, 5)."

Jan 1, 2017

By H. P. Cole

A team of researchers at the University of Kentucky, working under a USBM contract, developed over 65 simulation exercises for teaching and testing problem-solving and decision-making skills to miners and mining engineers. These skills involve both improving judgment and decision making in mine emergencies and enhancing the learning of real-world engineering design principles. The exercises are ideally suited for either latent image format or for computer-aided instruction. Exercise features are summarized, the structure and field testing of typical exercises described, and sample frames of individual exercises presented. Empirical data are summarized that describe the effectiveness of using these short, time-efficient performance tasks that simulate real problems and that provide immediate corrective feedback for teaching and testing critical skills. I

Jan 1, 1991

By L. Sandbak

The TRJV Mine is located approximately 43 miles northeast of Winnemucca, along the east flank of the Osgood Mountains in the Potosi Mining District, Humboldt County, Northwest Nevada (see Figure 1). The Turquoise Ridge Mine is an underground mine, and is a 25% joint venture partner with Newmont Mining. The TRJV mine utilizes the underhand cut-and-fill mining method due to the relatively low rock quality in the ore zones and the relatively shallow dipping 25-45 degree ore body geometries. This paper defines a rehabilitation risk rating system (RRRS) for prioritizing rehabilitation of drifts damaged in the mining processes including long term development drifts providing access to the mining areas. The ultimate use is as a mine planning tool for the organized scheduling of rehab in a timely manner. A few case studies of the most needy rehab areas identified by the RRRS mapping system is presented, and the type of rehab completed design for these areas. Suggestions on improving the rehab risk mapping system include the use of support history and rock mass strength rating factors.

Feb 23, 2014

By Goran Mathisson

PLASMARED is a process in which one well established and one new advanced technology have been merged into a practical tool for production of high quality direct reduced iron at lowest energy consumption and costs. Before describing the process, we have to reiterate the simple fundamentals of making metallized iron from iron ores: The main components necessary are: - Iron oxide - Carbon and/or hydrogen - Heat

Jan 1, 1982

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 Michael Forbes, Rick Jeuken

The challenge of managing geological uncertainty in mine planning is central to optimizing resource extraction while minimizing risks and costs. This paper introduces a novel approach to coal mine planning by integrating chance-constrained programming to address the uncertainty inherent in mining operations. The main takeaway from this work is the demonstration that focusing on reducing the variance of high-quality coal blocks, rather than low-quality ones, can lead to better blending outcomes, higher profitability and more efficient resource utilization. The study presents a case study of a coal mining operation, using chance-constrained programming to manage the uncertainty surrounding coal property predictions, specifically the predicted coke strength after reaction (CSR).

Jan 1, 2025

By Norman F. Schulz

The Davis magnetic tube concentrator is a laboratory machine designed to separate a small sample of pulverized magnetic iron ore into magnetic and non-magnetic fractions. It was developed in 1921 by mechanization of a test previously performed manually. (1)(2)(3)(1) No significant changes have been made in the design of the apparatus since that time. The Davis magnetic tube test continues to serve as a practical basis for judging the amenability of an ore to magnetic separation and for controlling magnetic separation plant operations. The apparatus consists of an inclined cylindrical glass tube supported adjacent to closely spaced pointed poles of a powerful C-magnet. (Figure 1). To conduct a tube test, a sample of a suitably prepared ore is poured into the water-filled tube. With wash water flowing through, the tube is oscillated to gradually reject the weakly magnetic ore particles until the desired degree of separation is attained. Both the magnetic concentrate and the tailings may be recovered for examination.

Jan 1, 1963

By A. K. Bakshi

Slurry rheology affects autogenous grinding performance by changing the rock's breakage characteristics. In this study pilot scale batch autogenous grinding was carried out to observe the effect of viscosity on the breakage characteristics of the rocks (the media), and on the overall specific energy consumption. Clay/fines content, and temperature of the initial charge, were varied to alter the viscosity of the slurry. Results showed that at higher slurry viscosity, rocks became more difficult to break, resulting in an overall increase in the specific energy consumption of the mill. Also, it was observed that viscosity had a significant effect on the amount of critical size material present in the grinding circuit, where the critical size material is the material which is too large to be effectively ground in the mill, and too fine to act as grinding media.

Jan 1, 1996

By Ben W. Burdett

Since the late 19701s, the use of microcomputers in the minerals industry has grown to the point where today they can be found in virtually every plant within the industry. Their use in every aspect of instrumentation and control has increased the ease of operation and control of every phase of mineral processing. Their incorporation in sensors, transmitters, indicators, and controllers in addition to their use in distributed control and computer systems has provided operators with more timely accurate information than they have ever had before. This has led to an increase in the operator's effectiveness and an improvement in overall productivity. The ultimate aim of plant control is to maximize recovery in the mineral processing operation, and the microcomputer has spawned many tools that are now making this goal attainable. This paper discusses individual use of microcomputers in the areas previously mentioned as well as their collective use in overall control systems. The incorporation of local control systems in total plant control including the communication of information throughout all levels of plant management is also discussed. Finally the role the microcomputer is playing in today's plants is illustrated with numerous references to current examples.

Jan 1, 1985