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By D. Einarson, B. Strickland

The decision to accelerate development of Stillwater Mining’s East Boulder Mine was made in March of 1998. It required the completion of conceptual designs by July of 1998. This was accomplished through teamwork and close cooperation of mine personnel, engineering firms and vendors, all working toward the common goal of developing an efficient and workable design. Early in the project, representatives of Stillwater Mining, Kilborn International, Parsons Brinckerhoff Transit and RailSystems, Continental Conveyor, and H.A. Simons met to develop methods to bring the mine into production at a highly accelerated rate and to solve potential bottlenecks, including the movement of personnel, materials, and muck through a 5.6 km(3-1/2 mile) adit. This interaction, including companies not normally associated with the mining industry, led to innovative approaches and designs produced by Kilborn Engineering and Stillwater Mining.

Jan 1, 1999

By Corale L. Brierley

The effect of hydrogen peroxide (H2O2) on growth and respiration of Thiobacillus, thiooxidans, and Thiobacillus ferrooxidans, organisms involved in acid leaching of copper sulfide minerals and uranium oxides, was examined. Oxygen uptake and growth by T. thiooxidans were inhibited after contact with 0.82 mM H2O2. Inhibition of oxygen uptake by T. ferrooxidans occurred at 8.24 mM H2O2, and growth was inhibited after 6 hours exposure to 2.06 mM H2O2. Higher concentrations of H2O2 can be used without detriment to thiobacilli if it is dissipated prior to reaching the oxidation pond or dump surface. INTRODUCTION In recent years, hydrometallurgical processes for recovery of metal values from low-grade ore minerals have played an increasingly important role. Dump leaching of low-grade copper waste materials in the western United States now yields 11.5% of the total U. S. copper production. Although scavenger operations in uranium leaching have been successful, the state-of-the-art of in-situ

Jan 1, 1977

By Kent Phillips, Meredith Scaggs-Witte, Emily Sarver, Cigden Keles

"After nearly four decades of decline, the prevalence of coal workers’ pneumoconiosis (CWP, or black lung) in the United States has been on the rise since the mid-1990s (Laney et al., 2014; Laney et al., 2010; Suarthana et al., 2011; Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016). Particularly alarming is the number of cases of rapidly progressive disease such as progressive massive fibrosis (PMF) (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016; Laney et al., 2017). A recent study by Laney et al. (2017) observed 192 U.S. coal miners participating in the Coal Workers’ Health Surveillance Program (CWHSP) who had been diagnosed with PMF since 2000. Of the 163 (85 percent) that had a normal radiograph on file to use as a baseline, 27 (17 percent) of these individuals had progressed from a normal radiograph to PMF diagnosis in less than 10 years. Moreover, 162 (84 percent) of the individuals in that study worked in Kentucky, West Virginia or Virginia, and 169 (88 percent) had only ever mined underground. Blackley et al. (2016) also reported on a group of 60 PMF cases that were discovered by a single black lung clinic in eastern Kentucky. Since seeking care at such clinics and participation in the CWHSP are voluntary, and could be influenced by a number of factors, there has been some concern that these reports may overestimate the degree of resurgence in severe disease (i.e., versus disease that was previously under-reported). Even so, they highlight a critical need to better understand the cause(s) of disease development and progression — such that effective interventions can be devised.The notable uptick in CWP and PMF rates among miners in central Appalachia has led to this region being called a hot spot for disease (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2014; Laney et al., 2017). While the geographic clustering has been well documented (Pollock et al., 2010; Antao et al., 2005; Wade et al., 2011; Wang et al., 2013), the root cause is still unknown. Leading hypotheses have focused on the relative amount of rock being cut along with coal in many central Appalachian mines, as there has been a tendency to mine increasingly thinner coal seams over the past couple of decades (Laney et al., 2010; Schatzel, 2009). This shift has likely been accompanied by changes in specific dust exposure factors, such as increased abundance of particularly harmful dust constituents (e.g., silica or silicates) or increased frequency of harmful exposures (e.g., due to work in more risky environments) (Pollock et al., 2010; Blackley et al., 2016; Cohen et al., 2016; Douglas et al., 1986)."

Jan 5, 2018

By Z. T. Bieniawski

The efficient and safe design of room-and-pillar coal mines still remains as one of the pressing problems facing the mining industry in the United States. Although much research has been directed to stability of mine roofs and coal pillars, no generally-accepted design method has been formulated. This paper presents a concise procedure for an improved design of room-and-pillar coal mines. Developed as a result of a three-year research effort, the methodology includes essentially three aspects: (i) determination of stable roof spans; (ii) determination of the strength of coal pillars; and (iii) determination of safety factors for room-and pillar coal mining in the United States. It is shown that the presented approach will lead to a greater recovery of coal by a more economical, yet safe, mining operation. Design charts and tables are presented and a step-by-step design procedure for practical mining engineers is explained. Several examples are included demonstrating the use of the proposed design procedure for room-and-pillar coal mines.

Jan 1, 1983

By Omar A. Muhtadi

6.1 INTRODUCTION The three most critical factors in successful heap leaching operations are: • The methods employed to pretreat ore (i.e, crushing and agglomeration); • Placement of ore on the leach pad (heap building techniques); and • Wetting of the ore with cyanide (solution application techniques). Improper execution of any of these initial steps may result in a substantial sacrifice of total metal extraction or, in the worst case, in project failure. Ore preparation in terms of crushing and agglomeration was discussed in Chapter 5; this chapter therefore focuses on commonly employed techniques for heap construction and solution application. The main objective of heap construction is to obtain the most homogeneous heap possible. "Channeling" of leachate in heaps with preferential seepage paths leads to preferential leachate distribution and uneven/incomplete extraction. The two main contributing causes of channeling are inadequate attention to heap construction and uneven solution application. These pitfall s can best be avoided through a knowledge of the various techniques available and the applicability and success of these techniques with various ore types and site conditions. The remainder of this chapter provides a discussion on these two subjects. 6.2 HEAP BUILDING TECHNIQUES Successful heap building techniques vary with the type of ore and, since no two orebodies are exactly alike, some slight modifications are usually necessary for each specific project. However, it is possible to generalize in terms of the appropriate techniques to be used with ores having similar characteristics. This section discusses the three most commonly used methods of heap construction and provides some guidelines with regard to ore types, construction constraints, and lift height parameters for each of the three. 6.2.1 Run-of-Mine Dumping and Dozing The run-of-mine method of heap building can only be used with ore of a highly silicious nature (i.e., ore which will not generate a large amount of

Jan 1, 1988

By Raymond E. Zimmerman

The use of standard dense-media cyclones is well known, as they have been in use for many years. They are especially well suited for operating at low separating densities and for treating difficult coals containing a high percentage of near-gravity at the point of separation. Very few modifications of the basic design have ever been made. The author recently, however, has been interested in the development of a new type of dense-media cyclone that has been produced in Japan. He has observed the testing of this unit and has collected much data which he feels should be of considerable interest to coal preparation engineers. He feels that this unit, called the Swirl Cyclone, may be of substantial value as an alternate to the standard cyclones. It is certainly worthy of further investigation. There has been relatively little written in English-language publications on the Swirl Cyclone. It was briefly described at the Fifth International Coal Preparation Congress. I It has been described in a general manner by the author in two prior publications. 2, 3 This paper proposes to describe this device in more detail and at the same time submit technical data illustrating its wide characteristics.

Jan 1, 1977

By R. Mohr

Storm water runoff from mine facilities such as haul roads, waste disposal sites and ore bodies have become recognized as the primary facilities associated with non-point source drainage. Depending on the ore body, facility design and geographical setting, nonpoint source drainage can cause pollution impacts to local surface and ground water resources. Non-point source impacts from surface mine drainage have become an important regulatory issue for the mining industry. Implementing non-point source drainage control plans that prevent impacts to water resources can be accomplished cost-effectively with moderate labor requirements. Design considerations for plan development must incorporate parameters including contributing drainage area size, slope, flow velocity, vegetation characteristics and soil scour velocities. The success of non-point source drainage and erosion stabilization planning is based on implementing control measures that dissect drainage patterns, reduce flow velocities and disperse runoff towards sediment control sites. Interim and long-range drainage control measures should begin during exploration activities. Regulatory legislation addressing non-point source pollution sources was enacted as amendments to the Clean Water Act (CWA) in February 1987. The legislation required states to initiate non-point source pollution control programs.

Jan 1, 1991

By Robert L. Sundeen, Richard V. Wenberg

INTRODUCTION Shotcrete can be defined as spray-applied concrete with a maximum size aggregate in excess of 9.5 mm (0.375 in.). The concept evolved from guniting, which uses smaller aggregate and generally produces concrete with poorer physical properties. The larger aggregate used in shotcrete requires less water in the mix, while offering larger bonding surfaces, thus imparting greater tensile and compressive strengths. TYPES OF MACHINES Two basic designs of shotcrete machines in general use are the wet or prehydrated zero slump and low slump type, and the dry or nozzle hydrated machines. Fig. 1 shows a typical zero-slump machine in a con¬figuration commonly used for small-volume require¬ments. The prehydrated zero-slump machine mixes exactly proportioned batches in a sealed pressurized chamber. "Slugs" of hydrated shotcrete mix and com¬pressed air are sent through a distribution hose to the nozzle where the wet mix emerges as a spray. The spray is directed onto the rock surface by the nozzle operator. The low-slump machine is similar, except that a thick slurry mix of aggregate is delivered throughout the distribution hose to the nozzle. Fig. 2 shows a typical low-slump shotcrete machine used in moderate-volume applications. The nozzle-hydrated shotcrete machine accepts a premixed "dry" (4 to 6% moisture) batch of aggregate and cement. A constant feed of this mix is directed by compressed air through the distribution hose to the nozzle. At the nozzle, water for hydration is introduced into the emerging spray. The hydrated mixture is di¬rected onto the rock surface by the nozzle operator. Fig. 3 shows a typical dry-mix machine. The major difference between the two basic machine designs is the consistency of the shotcrete quality. Pre¬hydrated machines have high degrees of consistency and produce high-strength concrete, resulting from their ability to produce exact mixtures of zero or low-slump concrete within the machine. Nozzle-hydrated machines tend to produce poorer quality concrete because of the difficulty in controlling the water content at the nozzle. Water input essentially is an art. As such it is not precise, and the shotcrete produced is of variable quality. MATERIALS HANDLING Materials handling presents a problem to either type of shotcrete machine. At times considerable quantities

Jan 1, 1982

By Poltak Sinaga

PT Kaltim Prima Coal's 13.1 km overland conveyor was commissioned in 1991. It is of conventional 3 roller 350 troughed belt type. Cost and performance optimisation during initial design ended up with 5.4m/s belt speed, 1,000mm belt width to convey 1,350tph, and 7mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1,100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30mtpa. Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4200tph satisfactorily.

Jan 1, 2008

By D. Castillo

The effectiveness of a flotation column is due principally to the addition of wash water to the froth phase. The wash water flow rate can be significant, especially so for systems yielding a high weight recovery of fine solids, e.g. zinc sulfide flotation. Therefore, it is critical to recognize and assess the impact of the water addition upon upstream separation stages. This paper examines column flotation circuit configurations using data from a portable 2 t/day pilot plant. The objective is to provide an improved basis for column design, either as a retrofit or as part of a new circuit.

Jan 1, 1990

By Donald I. Bleiwas

The U.S. Bureau of nines evaluated the potential availability of tungsten from 57 tungsten mines and deposits in 19 market economy countries (1). The 38 properties that were producing at the time this study was performed contain approximately 375,000 tons1 of W03 (tungsten trioxide). The total estimated recoverable resource from all properties studied, both producers and nonproducers, was 1.2 million tons W03 (demonstrated level). Approximately 143,000 tons of W03 is recoverable from producing properties with costs at or below the January 1983 market prices. The study indicates that by 1990 production from currently operating mines in market economy countries will decrease as their demonstrated resources become exhausted. Some of this potential decline may be offset by lower than anticipated levels of market demand, discoveries of additional resources at producing mines, development of other known deposits, and/or discoveries of new deposits. Development of new tungsten resources in market economy countries will likely result in costs higher than exist at currently producing properties. The People's Republic of China has been steadily increasing production and export of tungsten in various form and currently supplies about 25 pct of U.S. imports. China's tungsten mines are large, high-grade operations capable of producing at relatively low cost. These factors, coupled with China's apparent need for foreign exchange, could lead to further expansions of production and exports from China, with a consequent increased dependence by market economy countries on China for tungsten requirements and a threat to the survival of the market economy countries' tungsten industries.

Jan 1, 1984

By L. C. Morales

During my College days in Mexico City, my Mineralogy Professor used to say "Mexico is the Horn of Plenty, rich in minerals, and it is easier to say which minerals are not found instead of stating all that exist. He said that the only ones missing are bauxite, diamonds and titanium ores." Today, twenty years later, a rutile mine in Oaxaca is in successful operation. Mexico has an area of approximately two million square kilometers, with volcanic activity, large shores and mountainous areas reaching as high as 6,000 meters above sea level. These conditions are favourable for most mineral deposits, some -of commercial value and others as a source of mineral samples only. (fig. No.1) In addition to vast mineral wealth, Mexico has -another valuable asset in .his people. Even before the discovery of America, natives were successfully mining metals, and during the Colonial --days, the mineral deposits were mined to increase the wealth of Spain, and it increased the --knowledge of mining. All this experience was passed along from generation to generation, and created a tradition of mining and minerals processing engineers, that currently account for approximately 182,000 persons supported by mining related activities.

Jan 1, 1994

By Mohammed Laraba, Rodrigo Alvarez Garcia, Juan Maria Menendez-Aguado, Roula Abdelmalek

The aim of this research is the study of the WHIMS parameters on the improving process of a local (DD: Djebel Debbagh, East of Algeria) kaolin. The obtained results of performed XRF, SEM, and XRD characterization showed that this local material is an alumino-silicate containing kaolinite and halloysite with MnO and Fe2O3 impurities (respectively 39.30% and 34.67% alumina and 38.18% and 39.70% silica in both samples (DD2 and DD3). After homogenization, crushing, and milling, a multiparameters factorial experimentation (grain sizes, intensity, and dimension of matrix balls) showed that WHIMS is an effective process to improve the quality of this kaolin, mainly: removing their impurities. Dimensions of matrix balls (Db) = 2 cm, intensity of the applied magnetic field (I) = 1.5 T, and grain sizes (Dp) = > 100 < 250 μm) are the optimal values to reach 91.06% for manganese and 93.45% for iron as removing yield. The statistical analysis of these results sorted the investigation parameters and showed that Db has the highest and most significant influence on the recovery of iron and manganese particles. The magnetic field intensity (I) has a less important influence while the grain size has an average influence (positive on the iron recovery but a negative one on the recovery of manganese).

Jun 11, 2022

By C. O. Petter

This paper, in its first part, compares the profile and economic weight in the extraction of industrial minerals and aggregates to the so called conventional mining activities (metals, coal, gas and oil extraction) in Brazil. In its second part, a descriptive analysis of the present situation of the education in Brazil is made, emphasizing the graduation and post-graduation formation especially in engineering. The curricular structure of the schools that prepare the mining workforce is discussed and the presence of specific subjects in industrial minerals is evaluated. Finally, considerations are made on the actions being taken in the main universities and companies, aiming to improve the formation of the specialized workforce. The Brazilian mining production, comparing 2010 to 2011 showed an expansion of more than 3% (IBGE, 2012). Not bad, but nothing to do with the 13% growth between 2010 and 2009 (influenced by a recovery effect from the 2008 commodities? nightmare). The commodities that had a rising behavior were titanium, gypsum, nickel, graphite, bauxite, phosphate, chrome and chrysotile. All of them were eclipsed by the impressive growth of iron ore production. Some decreases could be noticed, eg. in zinc, kaolin, magnesite and salt production (DNPM, 2012). In fact, the mining activities followed the positive growth of the country these last 5 years. The commercial balance (exports against imports) was not spectacular (positive in US$ 30 billion in 2010). It is important to notice that the mineral commodities balance was US$ 35 billion, representing 27.4% of the total exports and 15.6% of the total imports of Brazil (DNPM, 2012). In this positive environment, the workforce in Brazil showed progress in number of formal jobs and average revenues.

Feb 23, 2014

By T. J. Toy

The topography reconstructed following land disturbance is the foundation for all other reclamation practices. As the manufactured drainage basins, hillslopes, and stream channels approach a steady-state condition, the amount of adjustment of these landforms by geomorphic processes following reclamation decreases. As the adjustment required to establish a steady-state condition decreases, the prospect of reclamation success increases while the prospect of site maintenance decreases. Careful topographic reconstruction is a good investment.

Jan 1, 2002

By James E. Lawver

The agriculture industry has made great strides during the past decade to increase agriculture yields through increased use of fertilizers. Increased use of fertilizers may prevent or at least delay mass starvation due to the alarming increase in world population. Phosphate was added to soil as a plant nutrient in the forms of calcined bones at least 2 000 years ago, (1) and man has used phosphate minerals as a source of fertilizers in one form or another for at least 100 years. During 1977 the world produced about 116 million metric tons of phosphate rock, with about 86% used for fertilizers and another 4% for animal feed supplements. More than three-fourths of the total production comes from the United States, Morocco, and the Soviet Union. From a mineral beneficiation point of view, the major sources of phosphate rock and the methods of beneficiation can be classified as follows. Marine deposits not containing appreciable carbonate minerals, marine deposits requiring a francolite carbonate mineral separation, igneous deposits not containing appreciable carbonate minerals, and igneous deposits, requiring an apatite carbonate mineral separation.

Jan 1, 1978

By Steven Johnson

The regulatory landscape has changed considerably since the first passage of Oklahoma&apos;s land-reclamation requirements in 1968 (Open Cut Reclamation Act of 1968). The Oklahoma Legislature revised the reclamation requirements in 1971 with passage of the Mining Lands Reclamation Act. With the passage of this Act, the Legislature empowered the Oklahoma Department of Mines with jurisdiction for permitting and regulatory authority over non-coal (industrial-minerals) mining operations. This act required all operators to file with the State, through the Department of Mines, a written application for a permit to engage in non-coal mining. Each application consisted of a mining plan, which included location maps of the proposed mining area along with a reclamation plan for the area to be covered. Additionally, a reclamation bond is required prior to issuance of a permit to ensure that the site would be reclaimed. Since 1971, the Act has been amended to include public notification and public participation in the review process of any application. Also, the operator can request that the Department review the mining plan based on the Life Expectancy of the mine, instead of the original one-year plan (HB 1409 in 1993). Even though the operator is granted a mining plan tied to the "Life Expectancy" of the site, the permit is reviewed annually for compliance as required by law.

Jan 1, 1999

By M. S. Basich, J. S. Scope1, J. H. Raeder

During 1983, The Youghiogheny and Ohio Coal Company&apos;s lost-time-incidence rate was 8.1, equal to the average for underground bituminous operators. How- ever, one half of all lost-time injuries were low back, back and neck related. In reviewing these results, we determined that substantial improvement could be made. We investigated existing back schools and the possibility of opening an in-house clinic. In September 1984, we began The Youghiogheny and Ohio Coal Company&apos;s Back Care Program. The objectives of the program are to reduce the number of back injuries incurred at the work site, hasten recovery time, decrease medical and workers&apos; compensation costs and provide the employee with a thorough understanding of his problem. A state-of-the-art clinic capable of treating injuries to the spine and extremities has been established at the work site. The clinic is staffed by a licensed physical therapist and is offered to all employees on a voluntary basis under physician referral. The approach to treatment is multi-phasic. For the typical patient, the initial goal is to reduce pain and correct dysfunction. Treatment modalities such as auto-traction, extension exercises, ultra sound and moist heat are frequently used. During this period the patient is given extensive education regarding his problem. As soon as more vigorous activity can be tolerated, a work-hardening pro- gram consisting of job simulation activities designed to improve flexibility, strength and functional capability is begun.

Jan 1, 1986

By K. J. Shoop

This study investigates the use of a horizontally-baffled column (7.6 cm inside diameter by 344.2 cm high) to reduce the ash content of a high ash bituminous coal. Tests were carried out to determine how the baffled column responded to changes in feed rate, reagent dosage, and feed quality, and to compare its performance with a conventional column installation in an operating plant. In this paper, the results of this investigation will be reviewed and discussed.

Jan 1, 1997

By T. Gouri Charan

Indian coals, which are of Gondwana origin, contain high amounts of mineral matter, wherein the extraneous material was intimately mixed in the coal matrix during the formation stage, causing a high level of impurity in the run-of-mine (ROM) material. These coals possess difficult to very difficult washability characteristics. Beneficiation of high-ash non-coking coals of India has become the prerequisite for improving the overall economics and efficiency of power generation. The use of dry cleaning systems in India for beneficiation of non-coking coals has gaining renewed interest recently. The benefit of the dry beneficiation process is to exploit the given resources while providing a more reliable and consistent quality fuel with a low operating cost. M/S Allmineral has introduced a technique for the dry beneficiation of coal, which is being tried in India for the treatment of high-ash non-coking coals. The first commercial air jig of 50 t/hr capacity was installed and commissioned to beneficiate high-ash coals of 40 x 5 mm feed with an ash content of 40%; a clean coal product of 33% ash was produced and is being used for a sponge iron plant.

Jan 1, 2011