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By William J. Shampine

The Floridan aquifer, which underlies all of Florida, yields water with a hardness of less than 180 pmts per million (ppm) in the northwestern part and throughout much of the center of the Slate. In most of the rest of the Stale, the aquifer yields water having a hardness greater than 180 ppm and as much is 1,900 ppm. Hardness of ground water is caused by dissolved salts from the geologic formations through which the water passes or by direct pollution. Sometimes pollution may indirectly increase the hardness of ground water by increasing the acid content and thus increasing the solution of calcium and magnesium salts. Water from deep zones of the aquifer lend to he harder than water from more shallow zones. Only the hardness of water from the upper part of the aquifer is shown.

Jan 1, 1966

By S. K. Kawatra, T. C. Eisele

Although column flotation is known to be more effective than conventional flotation for cleaning fine coal, little attention has been paid to the considerable sulfur removal potential of this process. Whereas conventional flotation can only with difficulty remove pyritic sulfur from coal, flotation columns can make this separation readily due to their greater selectivity. This project has used a modified flotation column to remove pyrite from fine coal. This column has been shown to be capable of removing 70 to 85 percent of the pyritic sulfur from coal while recovering 80 to 85 percent of the total calorific value. However, the remaining pyrite is too finely disseminated to be readily removed by physical means. Currently, experimentation is in progress using bacterially-catalyzed dissolution of pyrite in acid solution to remove ultrafine pyrite and aid in the removal of coarser pyrite inclusions.

Jan 1, 1988

By E. S. Peterson, M. K. Harrup, K. A. Dolbeare, J. E. Wey

Efficient methods for the removal of copper from heap-leach solutions without mobile organic phases are a current mining industry need. To satisfy this need, a selective, high-capacity, durable solid material is required. The Idaho National Engineering and Environmental Laboratory (INEEL) developed a set of materials based on current solvent-extraction chelates that provide selective copper concentration in the presence of high concentrations of iron. In contrast to conventional solvent extractions, the author's strategy anchors the chelators to a nonpolymeric solid substrate through the use of a custom-designed linker molecule. The fundamental synthetic routes to these materials have already been established, and attachment to the solid surfaces have been achieved in an efficient manner. The author's continuing research is focused on the optimization of the synthetic pathways to these solid materials and the evaluation of their copper-capturing capabilities.

Jan 1, 2003

By L. J. Prosser, A. T. Iannacchione

From 1991 through 1995, 44 miners out of a total workforce of less than 2,000 were fatally injured in the stone industry. Of these, 12 occurred at underground mining operations with nine deaths resulting from roof or rib falls. A safer environment can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground-control strategies. Roof and rib conditions were observed and assessed in 33 underground stone mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania and West Virginia (Fig. 1). Hazard assessment indicated that the ground failures that occurred under moderate to substantial overburden, i.e., >30 m (100 ft), were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine-layout decisions

Jan 1, 1999

By John T. Bartlett

During the last decade, the increasing price of gold has renewed interest in the various metallurgical techniques for recovering precious metals. Much of the recent technology advance has been aimed at low grade deposits resulting in more complex processes and the necessity of tighter economic control. These factors along with more stringent environmental constraints have made it necessary to optimize each process to minimize energy and raw material consumption and reduce waste discharge. In most cases, detailed process analysis is required to detect inefficiencies and provide alternative solutions for process improvement. Also during this same period, the computer has become widely accepted and computerized mathematical modeling has been applied to an increasingly broader range of problems. Microcomputer based process modeling and simulation systems are routinely used to analyze and improve communition, hydrometallurgical, and pyrometallurgical processes for the recovery of precious metals.

Jan 1, 1987

By L. J. Dahl, S. E. Paulson, H. L. Kuhlman

To provide basic information on the processes occurring during in situ leaching, the US Bureau of Mines developed a geologic characterization research program. This includes laboratory experiments wing leaching apparatus that can accommodate whole core samples. Whole core experiments result in a higher proportion of ore mineral contact by the leach solution than packed column experiments. They also allow for the assessment of permeability changes taking place as the result of mineral dissolution, precipitation, and clay swelling within the flow channels of the rock. The leaching apparatus developed can be wed for either constant-pressure or constant- flow rate experiments and allows for the control of flow rate, pressure, and temperature during the experiments. Details of the experimental apparatus are presented, as well as preliminary results from the first series of experiments on an oxide copper ore from the Casa Grade, AZ area.

Jan 1, 1988

By K. Hajmrle

The production of nickel coated mica composite powder by hydrogen reduction of a nickel ammine sulphate solution, followed by the production of molded plastic samples containing Ni/Mica is described. Sample preparation by injection or compression molding is outlined and the better results in compression molding are explained by the combination of better particle-to-particle contact, less particle breakage during processing, and more random particle distribution in the plastic. Three volume resistivity measurement techniques are described and compared. Two of them (conductive paint and silver-rubber electrodes) are found reliable and are used throughout the work. The influence of nickel content and particle size of Ni/Mica on volume resistivity is evaluated and the optimum product defined. One of the most important assets of Ni/Mica, its ease of injection molding, is demonstrated by the good electrical properties obtained with little optimization of the injection molding process. Surface roughness of molded plastics with and without Ni/Mica is briefly discussed. Shielding effectiveness of Ni/Mica in four plastics (PP, ABS, PBT and PC) is presented and correlated to volume resistivity data for the same materials. The addition of 15 to 50 weight % Ni/Mica (3 to 16 volume %) to plastics and subsequent injection or compression molding produces composite materials having low volume resistivities (0.03 to 1 ohm.cm) and high shielding effectiveness (40 to 70 dB).

Jan 1, 1988

By Barrie C. Butt

The opportunity for an exploration geologist to follow a successful exploration project through the feasibility, financing, construction, development and exploitation phase is rare. In addition, it is not often that the exploration geologist can be present during the mining of a deposit to explain why certain actions were taken or interpretations made and to find out how these interpretations turned out in actuality. At the Woodsreef chrysotile asbestos mine in New South Wales, Australia, mining has been in progress for six years and the writer has been intimately associated with the project during the five years of exploration and the six years of exploitation. The industry is possibly aware of the fact that the Woodsreef Mine has had major production problems, the majority of which have stemmed from the unique characteristics of the ore body and of the fibre. Because of these unique features, a large volume of research has been undertaken by Woodsreef and by other scientific organisations in Australia, England and Canada on the Woodsreef fibre. The answers to some of the problems have negated some semi-sacred concepts of asbestos ore milling and led to the development of new techniques, such as the adoption of microscopic fibre counts as a routine procedure; the modification of accepted evaluation procedures; the development of new machines for dedusting fibres, and to the recognition of a fibre with a unique milling behaviour pattern and, possibly, properties. The problems experienced can be divided broadly into those associated with the geology and those associated with the physical properties of the fibre. It is possible that the same features may manifest themselves in other deposits around the world, and if they can be recognised during the exploration stages a feasibility evaluation may be just that little closer to the actual.

Jan 1, 1978

By Yucheng Li, De Huang, Yonghong Liu

Mine frictional resistance is one of the essential parameters of mine ventilation systems, and it is of considerable significance for the prevention and control of mine risks and accident hazards. Frictional resistance requires a lot of resources and time and has errors. To reduce the errors of frictional resistance, a regression model of frictional resistance is proposed based on the correlation analysis of the affecting factors. Through the comparative test analysis of seven regression methods, it is found that the classification and regression tree method for solving the proposed regression model has better performance than other methods. The least square error criterion is used to calculate and rank the importance of the factors affecting frictional resistance. The results show that the cross-sectional area of the tunnel, the support method, and the presence or absence of devices or pedestrian ladders have the most considerable influence on the prediction accuracy of frictional resistance. The support methods and cross-sectional areas are essential input variables. Through the combination test analysis of the influencing factors, the results show that the regression model does not have predictive ability when the number of input variables is less than 3 and the best predictive performance cannot be obtained using all the influencing factors. The best prediction model of resistance is to combine the shape of the tunnel, the support method, the presence or absence of devices or pedestrian ladders, and the cross-sectional area. The method proposed in this paper does not require a lot of resources and time investment, and the frictional resistance error is small. At the same time, it solves the problem of resistance prediction with incomplete data of influencing factors and provides a compelling new method for obtaining frictional resistance parameters.

Jan 28, 2022

By E. D. Goddard

There are similarities, and differences, in the surfactants used in cosmetics and detergents. In both applications anionic surfactants constitute the major category. Their main function is to clean, i.e. remove grease and particulate matter from fibrous or hard surface substrates. Cationic surfactants are used for conditioning substrates. Nonionic surfactants can function as a substrate cleanser but are seldom used as such in cosmetics; however, selected non-ionics are often employed as a primary emulsifier. Several specialized nonionic surfactants are used as a secondary surfactant in formulations to promote foaming and emulsification. Specific examples and modes of action of surfactants will be presented.

Jan 1, 1988

By L. A. Taylor

The production of oxygen on the Moon utilizing indigenous materials is paramount to a successful lunar colonization. And several processes have been put forth to accomplish this. The LLOX generation schemes which have received the most study to date are those involving?: 1) the reduction of ilmenite (FeTi03) by H2, C, CO, CH4, CO-CI2, & Cl2 plasma, 2) magma electrolysis, both unadulterated and fluoride-fluxed, and 3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reductions of ilmenite and magma electrolysis processes have received the most study to date. They are both feasible schemes with various pros and cons, including their feedstock requirements. However, all processes should be addressed at least at the onset of our considerations. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and this paper reviews several of the most studied and feasible processes for winning oxygen from lunar materials.

Jan 1, 1991

By Carlos Andrade

An engineering endeavor involves the creation of an expansive, environmentally conscious reinforced sloped MSE wall system. The objective is to enlarge a flat mining work area. Situated in southern Arizona, this mine is dedicated to extracting essential resources such as Manganese, zinc, silver, and lead, crucial for advancing clean and renewable energy initiatives. The project necessitates the implementation of a Mechanically Stabilized Earth retention system. This system aims to both expand the mine’s working area and facilitate access to underground tunnels. The expansion pad must be robust enough to endure the substantial loads exerted by heavy mining machinery. The wall’s reinforcement components are strategically designed to counteract the challenges posed by aggressive soil conditions with low resistivity. Furthermore, they must be resilient against potential damage during installation. The system’s ease of transportation is crucial due to challenging access conditions, and its design must allow for efficient drainage. A significant consideration is the integration of a face system that fosters vegetation growth and seamlessly merges with the existing flora of the area. In addition, plans include the construction of an access road downslope from the wall. The chosen solution involves a reinforced sloped system with a 70-degree incline. The wall’s surface is adorned with an erosion control mat, intended to promote the proliferation of vegetation. For added durability, the wire basket units are equipped with galvanized wire featuring a polymer coating. High tensile strip bonded geogrids, featuring a robust polyester core, provide essential reinforcement. The completed wall is an impressive feat, spanning 1500 feet in length and soaring to a height of 45 feet. It stands as a testament to innovative engineering in harmony with environmental and functional considerations.

Feb 1, 2024

By J. Wiedenroth

Since the end of the 1970s Pipe Conveyors have become increasingly important for conveying bulk materials because they have some specific advantages over conventional troughed belt conveyors. FLSmidth KOCH Pipe Conveyor represent the marked-leading know how of the former KOCH Transporttechnik GmbH, which belongs to the FLSmidth Group since January 2007. Pipe Conveyors from FLSmidth KOCH are already being used successfully at more than 260 locations around the world. Their special properties, their extreme flexibility, the horizontal and vertical changes in direction without transfer points, the small space requirement, the low-noise running and their optimum protection of environment and material without any additional casing mean that Pipe Conveyors can provide transport solutions that are often far superior to other conveying systems. The utilization of these many advantages will be illustrated in the following example of the world?s longest Pipe Conveyor at Cementos Lima, the Peruvian cement producer.

Jan 1, 2010

By D. D. Xu

A novel system for the depression of pyrite and the ash-forming minerals has been developed. A metal ion, including but not restricted to Fe+2, is added to form a hydroxide coating on the pyrite or ash-forming mineral. A polymeric depressant is then added to attach to this re-surfaced mineral. Nearly 200 flotation tests with a 11 different coals indicate the effectiveness of this system. Many of the important process variables such as the coal source, frother-collector system, grind size and procedure, pH, metal ion, and depressant type and concentration have been studied.

Jan 1, 1994

During the past 20 years, FKC-Lake Shore, located in southern Indiana, has been working with Contitech, the German conveyor company, to push vertical conveyor technology to new depths and open up additional opportunities for underground mine owners. Historically, the underground mining industry has largely been unable to realize the benefits of these efficient systems due to the design limitations in maximum depth and capacity. Until recently, only relatively shallow depth mines with low production rates have been a ?t for a vertical conveyor system. This, however, is changing with technical advancements in the Pocketlift system. With each milestone, a new vertical conveyor record is set for depth and capacity. For instance, in 2002, FKC-Lake Shore set one such record with the installation of a Pocketlift system at a mine in the Illinois coal basin with a lift height of 273 m (896 ft) and a production rate of 1.8 kt/h (2,000 stph). Although it was unthinkable at that time, today?s vertical conveyors are capable of reaching lift heights up to 700 m (2,300 ft) with an average production rate of 450 t/h (500 stph). These new lift heights and production rates are opening the technology to more potential mine owners and shifting the way people look at moving material in the future.

By Terrence D. Chatwin, James Hendrix

Based on the findings within their report to Congress, the US Environmental Protection Agency (EPA) announced that it had decided not to regulate mining wastes under the hazardous waste regulatory program. However, they found that some mining wastes are hazardous and may be causing environmental damage. Cyanide wastes from heap leach operations were included in this group. In evaluating the effects of cyanide use in mining one finds a significant lack of information on the fate of cyanide in soils. Cyanide attenuation and degradation of soils is important, because ground water is a major potential pathway for cyanide contamination. There is a strong potential for cyanide to be removed from solutions as it migrates through soils· by volatilization, chemical reaction, adsorption, oxidation and biological processes, but no definitive investigation has defined these mechanisms adequately to be able to predict the fate of cyanide in soils.

Jan 1, 1998

By S. Ripke

Between 2002 and 2004, the performance of a six million ton per year iron ore beneficiation plant dropped significantly. In a classic case of “who done it,” was it the mine, the concentrator, an ore change, or something else? While average annual final product grade decreased 8% (indicated by an increase in silicate gangue from 2.76% to 2.99%), the weight recovery also decreased by 8% (from 37.92% to 34.79%). This represents a loss of 832,000 tons of iron ore worth about $16 million for the two year period! The concentrator had been optimized to produce a high grade wet concentrate as feed to the dry side of the plant. But, did optimizing an individual unit operation’s grade give the best overall plant performance? In this paper, the investigation and solution to this mystery will be revealed.

Jan 1, 2007

By M. Poulton, J. A. Botín, C. Gatica

"The Chilean minerals industry faces a shortage of 27.000 new skilled professional by 2023. Enhancing the integration of women into the workforce is a possible solution. This study analyzes the state of women in the mining workforce over the past decade. Several key indicators are presented: percent in the workforce, salaries, career profiles, presence at management level, and participation in academia are studied. The study also analyzes the strategies used by government, industry, and universities to recruit and retain women for the minerals industry. The main results show that women represent 7.4% of the mining workforce in Chile and less than 1% of senior positions with a salary gap of approximately 30%. Systematically, women prefer professional programs in geology, chemistry, and environmental areas. The Chilean statistics are compared to data from the United States mining industry. INTRODUCTION The Chilean mining industry faces a significant shortage of professionals for the next decade which compromises competitiveness and productivity. The demand for human capital in mining depends on several factors. First, the age structure of workforce, which determines future retirement needs. Second, minerals market considerations, determining the amount and size of mining projects entering production in the coming years. Third, the evolution, positive or negative, of productivity, mainly driven by technology and innovation, and negatively affected by the declining ore grades. Finally, negative trends in lead times to production of mining projects, due to social opposition, changing regulations and other project contingencies, negatively affecting the demand for human capital. Regarding the supply of human capital, the fast increase in the technology level of the minerals industry and hence, the increase of technical qualification requirements of the human capital generates a rise in the time required for trade and university education of mining professionals, which may cause imbalances in the labor market. According to (Consejo Minero, 2014) human capital gap in Chile by 2023 will be around 27.000 workers for extractive, processing and maintenance jobs, which represents 14% of the current workforce (Figure 1)."

Jan 1, 2016

By İbrahim Alp, Emine Yoğurtcuoğlu

This article includes the application of roasting pretreatment by assisting the cyanidation process in the recovery of Au–Ag from Bolkardağ Gossan refractory ore and the characterization studies of the ore, roasting sample, and postcyanidation waste sample. While ore contained many metals along with gold and silver, the environment in which these metals were found was carbonate, sulfated, silicated, and iron oxide-containing deposits that have undergone oxidation. In mineralogical studies, there were Fe oxy/oxyhydroxides, Pb/Zn carbonates, and jarosite-bearing structures such as beudantite, calcite, dolomite, clay, and quartz in the ore. The sample used in the experiments was d80 = 29.6 μm, and the test parameters were determined by examining the TG analysis made to the ore. Preroasting experiments were carried out at a roasting temperature range of 200–800 °C, during a roasting period of 10.0 min. Three different samples were characterized by TG for temperature changes, FT-IR for bond structures and permeability, SEM/EDX for visual inspection of structural changes, and XRD Rietveld’s analysis for mineral % content differences. As a result of the cyanidation experiments carried out after the pretreatment, gold was recovered with 80–90% yields and silver with 40–48% yields, respectively.

Aug 21, 2023

By I. E. Odom

The rare magnesium-lithium clay mineral hectorite occurs at many places in the McDermitt caldera of Nevada-Oregon. Commercial development of several high purity deposits began in 1986. The hectorite was precipitated in a lake environment formed after collapse of the McDermitt caldera. Hectorite beds and lenses are associated with volcaniclastic sediments, limestones, dolomites, zeolites and locally sandy bentonites. The high purity deposits appear to be associated with hydrothermal areas. The hectorite consists of extremely small flake-shaped crystals, and Ca is the predominant exchangeable ion. Its color ranges from white to light green. Commercial uses developed to date include high brightness magnesium aluminum silicate products, organophilic clays, pulp retention, and ceramics. The MAS is used as a suspending agent, binder, stabilizer and thixotrope in aqueous solutions for cosmetics, household cleaners, pharmaceuticals and miscellaneous industrial applications. Organoclays are used in printing inks and paints.

Jan 1, 1992