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By P. Kim Carroll, D. Nick Tiffany, Doyl M. Fritz

Thunder Basin Coal Company received the 1987 Wyoming Excellence in Surface Mining Award for construction of the State's first major sediment control reservoir to be designed using the new settleable sol ids standard. Use of this standard resulted in construction cost savings of more than $250,000; reduced water quality monitoring; enhanced downstream channel stability because of more natural sediment loading; allowed simultaneous establishment of permanent waterfowl and fisheries habitat; and provided a quality recreational site. This article will address factors associated with the design and construction of that sediment reservoir and the benefits that were realized. (Note: This paper was originally published in the proceedings for the 1988 National Symposium on Mining, Hydro1ogy, Sedimentology and Reclamation held in Reno, Nevada, December 5-9, 1988.)

Jan 1, 1989

By Yingbao Yang, Jinyue Liu, Yonggang Wei, Bo Li

Due to the depletion of copper ore with high-grade and low impurity contents, the raw materials for copper smelting exhibit low copper contents and high impurities. High-impurity elements lead to the poor performance of the final copper product; thus, the removal of impurity elements during the oxygen-enriched copper smelting process is crucial. In this study, based on the production of high-grade matte, the occurrence states of impurity elements (such as As, Pb, and Zn) are analyzed in the input and output materials of the oxygen-enriched smelting process, and the phase transformation mechanisms of impurity elements are revealed during the oxygen-enriched smelting process. The effects of temperature, Fe/SiO2 ratio and oxygen concentration on the distribution behaviors of impurity elements in dust, slag and matte and the removal rates of impurity elements in matte are clarified. The results show that the impurity elements mainly exist as As4, As4S4, As2O3, Pb, PbS, PbO, Zn and ZnS in dust, as FeAsO4, As2O3, FeAsS, PbSiO3, Zn2SiO4 and ZnFe2O4 in slag, and as As, FeAsS, PbS, PbO and ZnS in matte. High smelting temperature, low Fe/SiO2 ratio and low oxygen concentration are beneficial for improving the matte grade and the removal rates of impurity elements Pb and Zn in matte. Low smelting temperature, low Fe/SiO2 ratio and high oxygen concentration are beneficial for removing impurity element As in matte.

Aug 8, 2023

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979

By Swades Kumar Chaulya, Vikash Kumar, Sushma Kumari, Naresh Kumar, Girendra Mohan Prasad, Monika Choudhary

Opencast mines are vulnerable to inclement weather conditions as it disrupts the day-to-day activities at these mines. To address the problem, a perceptive driving assistant system (PDAS) has been developed to increase the visibility of real-time video of the road in front of the vehicle for operators of heavy earth-moving machinery (HEMM) at opencast mines in harsh weather conditions.

Apr 1, 2023

By Isabel F. Barton, MarkD. Barton, Christian A. Rathkopf

Molybdenite is the world’s principal source of rhenium (Re), a critical element in multiple high-tech applications. However, the Re contents in molybdenite vary by orders of magnitude on scales ranging from single grains to whole deposits. In order to better understand the systematics of this variation and what geochemical factors control molybdenite Re concentration, and hence overall Re resources, we examine global patterns in molybdenite Re contents through a compilation of > 3000 measurements of Re in molybdenite from > 700 mainly ore-bearing moderate- to high-temperature hydrothermal systems of different types. Our results are similar to but expand on those of earlier studies. Rhenium concentration in molybdenite has a lognormal distribution and varies systematically with type of geologic system, intrusive lithology, and Mo grade. The lowest-Re molybdenite occurs in greisens (geometric mean 1 ppm ± a multiplicative standard deviation of 9), quartz vein-hosted W-Sn deposits (2 ± 5 ppm), unmineralized granites and granodiorites (12 ± 8 ppm), intrusion-related deposits (24 ± 8 ppm), and porphyry W-Sn deposits (16 ± 11 ppm). Rhenium is most enriched in molybdenites from volcanic sublimates (23,800 ± 5 ppm), with skarn Fe and Au (560 ± 5 ppm and 540 ± 3 ppm respectively) and porphyry Cu and Cu-Au deposits next (470 ± 4 and 430 ± 7 ppm respectively). Among porphyries, skarns, and quartz vein-hosted deposits, Re is most highly concentrated in molybdenites from Cu and Au systems and its concentration decreases systematically through Cu-Mo, Mo, Sn, and W deposits. In nearly all cases, molybdenites from systems associated with intermediate igneous rocks contain more Re than molybdenites from systems of the same type with more felsic rock associations. The disparity between Re contents of molybdenite in felsic and intermediate systems is largest for porphyries, quartz vein-hosted, and skarn deposits and is near zero for subeconomic or barren granite and granodiorite Mo systems; felsic intrusion-related deposits have slightly higher molybdenite Re than their equivalents associated with intermediate intrusions. In most systems, molybdenite Re content does not correlate with metal grade, but may have an inverse correlation with Au grade in intrusion-related deposits (based on a small number of data points) and does exhibit a strong inverse correlation with deposit Mo grade. Dilution of Re through larger amounts (higher deposit grades) of molybdenite explains about 40% of this correlation, but the relative enrichment of Re in molybdenite from low-Mo deposits must also reflect some selective enrichment of Re/Mo in porphyry Cu systems compared to porphyry Mo systems. We found no evidence for secular increase or other systematic temporal variation in molybdenite Re content. The data regarding the use of molybdenite Re content as a proxy for mantle influence are ambiguous. Nearly all observed empirical correlations can be traced back to differences in redox state and sulfide concentration, the two geochemical factors identified here and by previous experimental work as the controlling influences on Re mobility under hydrothermal conditions. Hydrothermal systems with reducing conditions (W- and Sn-rich) tend to have low molybdenite Re even though compiled whole-rock data indicate that their source rocks have as much or more Re as those of more oxidized systems (e.g., Cu-rich). Vapor-phase exsolution, crustal assimilation, and mixing with external fluids may all enrich molybdenite Re concentrations in individual deposits and deposit types, but their extent and importance in overall hydrothermal concentration of Re is uncertain. Thus, it appears that the available molybdenite Re resource in an ore deposit largely depends on how the deposit’s redox and sulfidation conditions have varied over time and space during the timespan of hydrothermal activity. Oxidized, high-sulfide conditions tend to concentrate Re in molybdenite, whereas reducing conditions tend to leave Re dispersed at low concentrations in the bulk rock.

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Amilton Barbosa Botelho Junior

A new step in the Bayer process has been used to recover NaOH and to reduce its content in red mud. After digestion, the residue is separated from the Bayer liquor and goes through press filters, which enables the recovery of NaOH and decreases the moisture content. It is well known that red mud is one of the most important sources of scandium. For this reason, the goal of this work was to characterize a Brazilian red mud (BRM) for scandium recovery. The sample was collected after the press filter system process. Analysis of energy-dispersive X-ray fluorescence (EDXRF), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray diffraction (XRD) was performed. Microwave digestion using an acid mixture was carried out to determine the concentration of the main elements. Fe2O3 represented 40% of the BRM, and the Sc concentration was 43 mg/kg. The SiO2 content was 24%, which is the highest value found in the literature, whereas the sodium concentration was the lowest. A literature review was carried out to compare results with BRM, as well as the current studies for recovery of scandium by the leaching/ion-exchange process. Scandium recovery using a leaching/ion exchange process may be possible with efficiency higher than 90%. The greatest challenge is the occurrence of silica gel formation during leaching.

Oct 19, 2020

By J. D. Miller, C. L. Lin, J. Dong

Nano clay mineral particles such as kaolinite — with primary particles typically smaller than 2 μm in size — can cause significant problems in flotation processes and tailings disposal, including the processing of Florida phosphate rock and Canadian oil sands. In this study, the consolidated state of flocculated kaolinite sediment was examined, and high-resolution X-ray microtomography (HRXMT) was applied to describe the structure of the consolidated sediment. Using this tomographic information, the complex geometry of the channel network structure for the consolidated flocs was established for the first time. With the establishment of the experimental channel network structure, permeabilities were estimated by flow simulation using the Lattice Boltzmann method. Results for kaolinite sediment with and without polymer are compared and discussed. Results for flocculated kaolinite sediment in a gravitational field are also presented and discussed. The results show that as polymer dosage increases, the permeability of flocculated kaolinite sediment increases, and as suspension pH increases, the permeability of flocculated kaolinite sediment decreases.

By J. R. Riding

In situ solution mining of uranium has environ- mental advantages over conventional mining. The leaching of uranium, however, alters the groundwater quality in the aquifer where the mining occurs. Currently, regulations require that the groundwater be restored to approximately its original condition. This paper, a summary of a study funded by the Bureau of Mines, reviews the state of the art in restoring groundwater quality after in situ uranium leaching. Current restoration practices discussed include disposal of liquid wastes in deep disposal wells and evaporation ponds, producing from all wells during restoration, and recirculating water purified in surface plants. Methods for predicting the effectiveness and cost of current techniques are presented. Possible alternative techniques are also described. Two restoration operations are discussed.

Jan 1, 1979

By G. A. Munoz

Gold leaching of an auriferous pyrite ore from the Portovelo deposit in Ecuador indicates that noncyanide leaching systems, such as thiocyanate and thiourea, are not as effective as the traditional cyanide system. For example, whereas approximately 95% of the gold can be leached from the ore with cyanide, only about 50% gold dissolution can be achieved with a thiocyanate leaching system. Electrochemical measurements indicate that gold is not cathodically protected by pyrite in these systems. Based on the results of preliminary diagnostic experiments, it appears that gold dissolution in thiocyanate and thiourea systems is limited by passivation due to the formation of either elemental sulfur or sulfur compounds on the gold surface.

Jan 1, 1999

By E. Krist

The newest addition to the Anamax Mining Company's Twin Buttes copper producing complex is a by-product uranium extraction plant which was placed into service in February 1980. The plant is unusual in that it is placed internal to the copper countercurrent decantation, solvent extraction, and electrowinning plant. The plant reached full production within a month and, to date, has produced continually above design rates.

Jan 1, 1981

By Sah Rameshwar, T. Umadevi, K. S. SRIDHARA

In the magnetite iron ore pelletization process, oxidation of magnetite followed by sintering of the oxidized magnetite (hematite) is desirable. Optimum preheating time & temperature and roasting time & temperature is required to get the desired properties of the pellets with magnetite, hematite, and hematite–magnetite blend. In order to utilize the magnetite resources in a current induration furnace, which is designed for hematite resources, detailed pelletization studies have been carried out to optimize the firing cycle for magnetite concentrate as well as magnetite with hematite concentrate. Under optimum conditions, such as preheating temperature 1000–1150 °C, preheating time 10 min, roasting temperature 1250 °C and roasting time 7.5 min, the cold compression strength (CCS) of magnetite roasted pellets was 325 kg/p, and this was due to recrystallization of secondary hematite particles, and development of the strong slag bond between primary and secondary hematite particles. The strength of hematite concentrate pellets was 260 kg/p. From laboratory studies, it was found that without disturbing the induration furnace firing cycle, which is designed for hematite ore ~5%, magnetite concentrate can be used along with hematite concentrate in pellet blend and the strength of the pellets was 270 kg/p. As the magnetite concentrate increases in the blend beyond 5%, the preheating zone residence time should be increased or a supply of extra oxygen is required. Laboratory as well as plant investigation has shown that the addition of magnetite to the hematite mix blend improved the strength of the pellets compared to hematite pellet alone.

Oct 26, 2020

By H. L. Lovall

Huge banks of preparation plant refuse and other non¬saleable materials have accumulated over the years in all major United States coal producing areas. These banks, esthetically and commercially undesirable, can cause air and water pollution and land reclamation and mineral conservation problems for the industry and nearby communities Although some refuse banks have been reworked to recover saleable coal, all remain and accumulation continues. Even those previously processed continue as potential hazards. Among the several problems created by refuse banks, in situ combustion is most treacherous. Of the millions of tons of major accumulations, there are at least 450 refuse banks on, fire at this time Attempts to extinguish such fires are costly, impractical and generally unfruitful. Studies are in progress to evaluate the potential of processing such materials to eliminate the combustion capability and to yield usable fuel and nonfuel products. Aspects of the study now in. development for coal refuse include: (a) evaluation of characteristics (size, sink-float, ash, sulfur and calorific value) of the coal refuse materials which are known to be highly variable, (b) development of an ignition test having significance for in situ conditions, (c) study of processing capabilities (comminution for liberation, pilot plant washing tests), and (d) investigation of potentially significant properties of fuel and nonfuel products which could be altered to enhance their market potential.. Among the latter products are lightweight aggregate, fill for mine slushing operations, construction, etc: Plans are to extend the studies to include the design, erection, and test processing of refuse with a transportable plant,; which could provide basic economic and product utilization data from several locations

Jan 1, 1964

By T. Dombrowski

Acid-activated montmorillonite is used worldwide as a catalyst and as a sorbent for the enhancement and purification of petroleum products as well as vegetable and animal-based fats. The solid-acid character of the activated montmorillonite is imparted by the manufacturing process, giving it unique properties that are exploited in these industries. Several international companies and a multitude of local clay producers are focusing on improving the efficiency of their standard and specialized products. This paper will describe the use of acid-activated montmorillonite in traditional sorbent applications, as a solid acid catalyst, and other new uses.

Jan 1, 1997

By Howard Lum, Sergio Valles, John Bednarski, Gordon Enas, Jay Arabshahi

"Water drawn from the Sacramento-San Joaquin Delta provides water supply to 66 percent of California’s population and supports the state’s agriculture industry. The existing through-Delta water system is outdated and unreliable with environmental risk to some fish and wildlife species. The Bay-Delta Conservation Plan (BDCP) has been established to environmentally retrofit and modernize California’s water delivery system through the Delta by restoring habitats, constructing new diversion points in the north Delta and providing a means to transport water supplies under the Delta, rather than through sensitive natural channels.Under BDCP, the Delta Habitat Conservation and Conveyance Program (DHCCP) has developed several alternatives to convey water from the Sacramento River in the north to the existing pumping facilities in the south Delta through an isolated conveyance system. The new conveyance system would become an integral part of the State Water Project (SWP) and the federal Central Valley Project (CVP) by transporting water to the export pumping plants for each of these projects. The DHCCP is managed by the California Department of Water Resources (DWR), while state and federal water contractors provide technical support to the program.The initial conceptual study efforts on the overall program commenced in 2007 and examined various options for the proposed conveyance system. Several conveyance alternatives were analyzed at that time. The Conceptual Engineering Report published on Oct. 1, 2013 identified the modified pipeline/tunnel option (MPTO) as the preferred alternative to be included in the BDCP environmental documents. MPTO includes three river intakes and pump stations along the Sacramento River, various sizes of pipelines and tunnels, junction structures and two forebays that are capable of delivering up to 4 million gpm (9,000 cfs) from the Sacramento River to the SWP and CVP. The river intakes are located near Hood in Sacramento County approximately 64 km (40 miles) from Clifton Court Forebay (CCF) in Contra Costa County. This route would cross portions of Sacramento, San Joaquin and Contra Costa counties. Figure 1 depicts the configuration of the MPTO alternative."

Apr 1, 2016

By Peter G. Chamberlain

Domestic mining will not produce a significant portion of the manganese consumed in the United States unless new mining and processing techniques are implemented that will enable domestic lean ores to economically compete with rich foreign ores. One mining-processing technique that appears promising for certain deposits is in situ and/or heap leaching with aqueous SO2. Since leaching offers economic advantages of low capital costs, low operating costs, and short start-up times as well as environmental and safety improvements over conventional mining-processing, the Bureau of Mines studied the leachability of manganese deposits from several districts. Manganese oxides, hydroxides, and carbonates were leached to 80 to 90 pct recovery in 7 to 40 days of leaching with a solution containing 5 pct SO2 in column leaching tests. Preliminary cost analyses of surface mining-heap leaching, block caving-in situ leaching, and shrinkage stoping-in situ leaching indicate that the products of manganese leaching may be economically produced for the chemical and electrolytic manganese industries. The easiest marketable product to obtain would be a manganese sulfate commonly used as a fertilizer amendment. Manganese carbonates and hydroxides could also be precipitated from the pregnant leach solutions.

Jan 1, 1983

By Charles H. Wells

This paper describes a commercial installation of a sophisticated instrumentation and control system designed to maximize the performance of heavy medium cyclones. Samples of plant feed and its products were collected and analyzed for ash content so that measures of efficiency could be determined for plant operation under (1) manual control and (2) automatic (computer) control. The heavy medium cyclone control strategy and its digital computer implementation are discussed in detail. The sample results are analyzed and the economic benefits of automatic control are discussed. Results from the initial data sets quantify the economic benefits of automatic closed-loop control; viz, increased recovery and reduced clean coal variability have been clearly demonstrated.

Jan 1, 1981

By Zachary D. Jones

"Construction projects involve a great many risks. The risk that material prices will increase during construction or that the work under construction will be destroyed by fire, storm or some other act of God are just a few examples. In tunneling or other underground projects, one of the most significant risks is that the subsurface conditions encountered during construction will differ from what is expected. Each of these risks must be accounted for, managed and, ultimately, the duty of one party or the other to bear. The primary tool used to allocate the risks among the parties is the construction contract.How construction contracts allocate the risk that subsurface conditions will differ have changed substantially over the past century. Today, construction contracts typically allocate the risk through a series of provisions. The first is the differing site condition or changed condition clause. That clause, when included, typically provides that the owner bears the risk that the subsurface conditions will differ from what is indicated in the contract documents or what is reasonably expected. The second clause is one that provides that the contractor must conduct a reasonable site investigation and bear the risk of any conditions that such an investigation would reveal. The third provision includes disclaimers that are often included in geotechnical data provided by the owner (or the owner’s engineer) to the contractor which attempts to limit the information on which the contractor can rely. Because these risk-allocating devices seem to be somewhat conflicting, a brief discussion of each provides critical insight in understanding how the modern construction contract allocates the risk of differing site conditions.At the start of the 20th century, construction contracts looked substantially different than they do today. For example, one contract for the construction of a public water tunnel in Chicago, IL, drafted around 1895 contained the following clause:The contractor must take the work entirely at his own risk. No extra allowance will be made for quicksand, hardpan or boulders."

Jan 1, 2014

By O. Tsuge, G. Hoffman

ITmk3®(Iron Technology Mark III) is an innovative new ironmaking technology whereby high quality iron nuggets are produced directly from iron ore fines and coal in a rotary hearthfurnace1). The reaction mechanism has been investigated in detail through fundamental laboratory research2)3), and the ITmk3 process has progressed from the laboratory to commercialization by the success of the pilot plant tests initiated at Midrex’ Technical Center and at the Kakogawa Bench Plant (KBP) located at Kobe Steel Ltd. Kakogawa Steel Works4)5). Pilot operations have demonstrated rapid production of the iron nuggets with complete metal/slag separation at a relatively low operating temperature. The Kakogawa Bench Plant (KBP) in Japan has logged 21 days continuous operation during which high quality iron nuggets were produced directly from fine ore and coal. The operation technology and the engineering data obtained from these pilot tests were instrumental for the scale-up of the ITmk3 process for the Mesabi Nugget Corp. pilot demonstration plant, which is located at Cleveland Cliffs Inc. Northshore Mining iron ore pellet plant in Silver Bay, MN. The ITmk3 process is an ideally suited technology for siting at the iron ore mine, as it allows the economical production of a value-added merchant iron product.

Jan 1, 2003

By Vas Choudhry

INTRODUCTION Traditionally mineral processing equipment has been procured based on (equipment) specifications prepared by the engineers. As newer materials of construction are being used for equipment manufacture and plant control systems become more sophisticated, the need for thorough and detailed specifications is greater than ever. For example, it is not uncommon to find plants looking at grinding circuits consisting of semiautogenous mills with variable speed, gearless, drives of large horsepower. Technical specifications for the mill, wrap- around motor and control system must, therefore, be carefully prepared to ensure that the respective equipment supplied by vendors meets overall grinding needs. Various engineering and design companies have expended considerable time and effort in developing the specification format. Equipment manufacturers have also given significant effort to developing data sheets aimed at collecting information regarding not only the duty of the equipment, but also the conditions under which it will be operated. As engineers moved from one company to another, the specification format became cross-fertilized and further developed. As a result, specifications on file with various engineers have improved considerably over a period of time. Equipment specifications from earlier projects are commonly used as a basis for tailoring new ones. To keep equipment specifications short, general technical considerations are often compiled as separate specifications. For example, general considerations applicable to the design, manufacture and supply of the mechanical equipment are consolidated under "Standard Requirements for Mechanical Equipment” and included along with that specified for purchase. As the economic feasibility of the project has been established during earlier studies, purchase-related activities can be initiated following completion of the specifications. Procurement itself is a major activity, however, in this chapter only those activities directly related to the purchase of equipment will be discussed. PREPARING EQUIPMENT SPECIFICTION Specification for process equipment or machinery is written in such a way as to define exactly what is required of the equipment. Generally, mechanical

Jan 1, 1986

By BERND SCHÖNHERR, JÖRG DEHNERT, PETER WINDISCH, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposure of miners in Germany, especially during remediation work in old mines. The QESS is a lightweight, modular and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil and expanding foam. It is designed to seal off radon-rich parts of galleries within minutes. Originally, the QESS was developed to protect miners against radon exposure. Then, the QESS found the attention of several mine rescue teams at a German mining conference. Some mine rescue drills by The Student Mine Rescue of the Technical University Bergakademie Freiberg, Wismut Mine Rescue and Front Range Mine Rescue helped to improve the system and highlighted its potential for mine rescue operations. Now, the QESS is well-suited for small-scale mining. The QESS can be used to both protect miners from radon exposure and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.