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By Roger J. Hornberger, Paul F. Ziemkiewicz, Dirk J. A. vanZyl, Gene E. Krueger, Harry H. Posey, Kim A. Lapakko, Charles H. Buckmam

The Acid Drainage Technology Initiative (ADTI) was initiated in 1995 by federal agencies, the National Mining Association and the Interstate Mining Compact Commission to identify, evaluate and develop cost- effective and practical acid drainage technologies. In 1999 ADTI was expanded through the addition of the metal mining sector group, which began organization efforts in 1998. ADTI addresses drainage quality issues involving metal mining and related metallurgical operations and acid drainage from coal mines, for abandoned, active, and future mines. ADTI is a technology development program. It is not a regulatory or policy development program. The guiding principle of ADTI is to build a consensus among industry, federal and state regulatory agencies. ADTI is focusing these efforts on technology development and technology transfer in the areas of mine drainage sampling/monitoring, prediction, avoidance/remediation and modeling.

Jan 1, 2000

By André Vervoort

The roof behaviour in room and pillar panels during the development of roadways and the subsequent pillar extraction was monitored underground and numerical simulations were conducted. For several underground sites, a satisfactory, correlation was found between underground measurements and three-dimensional numerical simulations using a boundary element code in the linear elastic domain. However, to simulate bed separation, and roof block collapses more complex models were required, of which examples are presented.

Jan 1, 1992

By W. R. Ernst

A method for the removal of nickel and vanadium contaminants from spent HDS catalysts involves pretreating the catalyst with H2S followed by the extraction of the metals with an acidic solution of ferric ion. The ferric ion solution alone removes significant amounts of active ingredients cobalt and molybdenum; however, after pretreating the catalyst with H2S, the extraction becomes more selective for the removal of Ni and V.

Jan 1, 1986

By George E. Aiken, B. R. Jr. Waples

INTRODUCTION In this paper the author will attempt to bridge from the paper work of design and engineering to the reality of implementation. Certain facets of construction are constant to a successful project, no matter the level of technical complexity. Basic to timely, low cost construction are the people assigned to the project. Construction is not accomplished by robots, computers, or speeches; but rather by people. People do however require the avail- ability of equipment and communications to properly complete the work. ORGANIZATION Good organization is the basic requirement of a well implemented construction project. For this paper the author will suggest an organization chart as well as an activity listing that together support the construction activities. There is little difference in the activities or functions needed to construct a small plant or a large one. It is a matter of how much time an individual has to spend on an activity that determines the structure of an organization. The difference between a large and small plant construction job is often described as the multiple hat versus the single hat philosophy. As an example, a resident construction manager on a small job might be the manager, the field engineer, the scheduler, the estimator, and the procurement manager. At some time during a construction

Jan 1, 1986

By D. Y. Geng

Longwall mining is a relatively new mining method in the United States. Early trials in the eastern and central coal fields were not successful, mainly because, among others, the face supports did not have sufficient capacity. It was not until in the late 1960's, when the high- capacity self-advancing powered supports became available, that longwall mining was successfully reintroduced. Since then the number of mines employing the longwall method has been steadily increasing. It has reached approximately 7.5% in 1981. Currently longwall mining is used mainly in the Appalachian coal field. The seam depth ranges from 150 to 2500 ft. but mostly between 300 and 1400 ft. The seam thickness ranges from 32 to 144 inches with the majority between 40 and 100 inches. Nearly all longwall mining are in flat or nearly flat seams extracting in single slice, although one inclined and one thick seam longwall mining have been either operated or initiated in Colorado.

Jan 1, 1983

By J. M. Schisler

In the last five years Eldorado Resources Ltd. (ERL) has undergone a major expansion and modernization of its uranium refining and conversion plants. A new refinery for processing yellow cake to UO3 was constructed at Blind River in northern Ontario and started up in 1985. Its rated capacity is 18,000 t/a uranium as UO3. At Port Hope, Ontario, ERL's new UF6 conversion plant has been constructed. This plant started up in 1984. It utilizes the novel, wet-way process to produce UF4 and gives the company a UF6 production capacity of 14,500 t/a U. Also at Port Hope is Eldorado's ceramic UO2 powder production facility, commissioned in late 1980. It has a capacity of 1700 t/a uranium as UO8. With the completion of these capital projects, Eldorado has the largest and most up-to-date refining and conversion facilities in the western world. This paper reviews the refining process and process design. The methodology used to start up the Blind River plant is described as are some startup difficulties, solutions that were developed, and the resultant current operation.

Jan 1, 1987

By E. V. Manlapig, B. K. Gorain, N. W. Johnson, K. Ward

A flotation model developed at the Julius Kruttschnitt Mineral Research Centre was used to predict the performance of copper rougher and scavenger circuits at the copper concentrator at Mount Isa Mines. The model describes the kinetic response of an ore in a flotation cell in terms of ore floatability, cell characteristics and froth recovery. The floatability parameters of the rougher feed ore were obtained directly from a detailed plant survey. Flotation analysis was carried out for twenty different size-by-liberation classes to account for the effects of particle size and liberation on flotation. This paper investigates the capability of the model to predict the flotation behavior of 20 different size-by liberation classes in the rougher and the scavenger banks.

Jan 1, 2000

By D. M. Smith, M. J. Meulendyke, P. J. Moroz

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1988

By Henry T. Miller

INTRODUCTION The basic purpose of this paper is to suggest procedures and practices to insure that no employee working in a uranium milling operation receives exposure to radioactive, toxic, or other materials or agents that might produce a permanent, deleterious effect upon his physical health and well-being. This program is also designed to insure that each employee can carry out his assigned duties without risk to his health or to that of his fellow workers. The assumptions underlying this program are by necessity, conservative, with emphasis being placed upon prevention rather than correction or reaction to an undesirable situation. The limits specified-either as Threshold Limit Values (TLVs), Maximum Permissible Concentrations (MPCs), or Radiation Protection Guides (RPGs)--represent both standards of best practice and those of law and regulation. The total program is envisioned as a balanced combination of occupational hygiene and radiation monitoring. This includes surveying, air sampling, personnel dosimetry, bioassay, medical surveillance, epidemiology, and training--all backed by a thoroughly tested and evaluated set of emergency procedures. The program, as presented, is keyed to the results of monitoring, surveying, air sampling, medical surveillance, and epidemiology--it being obvious that no problem can result when no hazard can be identified. The lack of an identified hazard, however, does not negate the need for such a program and prudence suggests the need for routine surveillance programs in the best-designed facility. [The Model Mill] The model mill used in this paper is that presented by the U. S. Environmental Protection Agency in its study of the uranium fuel cycle1. The model mill processes 600,000 metric tons of ore per year into 1,140 metric tons of U308 as yellowcake per year using an acid leach process. Other characteristics of the mill such as location, tailings dam design, number of light water reactors supported, and geographical location are not pertinent to this paper. The usual remote western location of these facilities produce some difficulties in delivering the required occupational medical services and is not within the scope of this paper. The operating lifetime of most mills is commonly estimated as from 12 to 15 years in actual practice; however, the U. S. Environmental Protection Agency estimated a 20-year lifetime for its model. The principal steps in the acid leach process include :2 (a) Ore is blended and crushed to pass through a 2.5 cm (one inch) screen. The crushed ore is then wet ground in a rod or ball mill and is transferred as a slurry to leaching tanks. (b) The ore is contacted with sulfuric acid solution and an oxidizing reagent to leach uranium from the ore. The product liquor is pumped to the solvent-extraction circuit while the washed residues (tailings) are sent to the tailings pond or pile. (c) Solvent extraction is used to purify and concentrate the uranium. (d) The uranium is precipitated with ammonia and transferred as a slurry. (e) Thickening and centrifuging are used to separate the uranium concentrate from residual liquids. (f) The concentrate is calcined and pulverized. (g) The concentrate or yellowcake is packaged in 208 liter drums for shipment. This process is illustrated in Figure 1.3

Jan 1, 1981

By Diana Diaz, Rakshith Shetty, Vitaly Proschenko, Mike Mooney

Cohesive clay soil poses a significant risk to earth pressure balance tunnel boring machines (EPBM) due to unstable face pressure, clogging potential, high cutterhead torque, poor muck flow, low advance rate, etc. This paper details the performance measures desired when EPBM tunneling in clay soil, and the scientifically-supported conditioning methods to transform in-situ clay to a muck with such characteristics, giving particular attention to ground conditions. The paper then examines TBM data from multiple clay soil projects in the context of these performance measures to demonstrate the influence of cohesive soil conditioning on EPBM performance.

Jun 13, 2023

By O. M. Arafat, J. A. Finch

Since its development, the functional performance equation for ball milling (McIvor, 1988) has facilitated a new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the functional performance mill grinding rate at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining selection rate and breakage size distribution functions. The much simpler ball mill model has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this business-friendly ball mill model with optimization criteria from functional performance analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/ material provider and circuit designer.

Jan 11, 2017

By W. R. Reed, G. W. Luxbacher

As directed by the MINER act of 2006, the NIOSH Office of Mine Health & Safety Research (OMSHR) has annually awarded contracts to enhance mine safety and health. OMSHR has a history of research that focuses on both respirable coal mine dust and respirable crystalline silica (or quartz) dust, and contracts have been awarded since 2010 in support of our intramural research efforts. In 2018, a National Academies of Science consensus study report recommended expansion of respirable dust research. As a result, beginning in 2018 through 2021, eighteen contracts were awarded focusing on this area. These contracts can be grouped in three topic areas: characterization of coal/dust, development of real time monitors, and improvement of respirable dust controls. This paper summarizes the outcomes of completed contracts and the progress of current contracts.

Mar 2, 2022

By Alan English

This paper reviews the process control systems used in early commercial pelletizing plants, traces the development of these systems into present day practice, and briefly outlines advanced automation concepts being considered for future installations. It deals specifically with controls for the balling circuit, pelletizing machines, and related material handling and combustion equipment. The importance of instruments for visual observation and data logging is discussed, and the potential use of computer control is evaluated.

Jan 1, 1965

By Mark S. Dunsbier, Steven J. Schatzel

Large roof outbursts began occurring in November 1986 at Domtar's Sifto Salt Mine in Goderich, Ontario, Canada, working the bedded Salina A-2 Salt unit. The outbursts, measuring about 13-20 m in diameter, released high concentrations of methane from cavities that extended into carbonate roof units. Spontaneous ignitions of methane gas during an outburst seriously burned a mine technician. The Canadian Ministry of Labour contacted the U.S. Bureau of Mines for technical assistance to aid in mine managements1 efforts in alleviating the problem. Initial gas content determinations of salt samples from the outbursts by acoustic test methodology revealed no methane enrichment. In- mine core drilling and subsequent methane content testing indicates the main source of methane in overlying roof units. Drilling the roof units demonstrated the potential of draining methane from areas showing signs of impending outbursting and alleviating the danger. Three mechanisms are considered the most likely means by which methane was introduced to the mine environment. These are (1) hydrocarbon gases released from brines, (2) gas transport along horizontal bedding planes or gas accumulations in bedding separations, and (3) mining-induced fracturing. The abundance of higher hydrocarbons in gas yielded by non-evaporite rock samples from the Goderich mine may be indicative of a former association with liquid petroleum.

Jan 1, 1989

By G. Whitney, J. Steiner

Introduction The Summitville Mine located in southwestern Colorado is an example of the potential impact that natural weathering and mining activities can have on environmental quality. Acid rock drainage and metals leaching from active and historic mine districts are a major environmental problem facing the mining industry today. Sulfide ore exposed naturally or during mining operations has the potential to produce leachates that contain high concentrations of dissolved metals. These leachates can affect the quality of plant and animal health in surface water used for agriculture, recreation and human consumption. Pintail Systems has developed biological processes for detoxification of cyanide in heap-leached spent ore and process solutions. During application of spent ore cyanide bio-detox processes we have also observed a substantial reduction in many of the leachable metals in biotreatment solutions. These field observations of soluble metal reduction led us to propose that metal bio-mineralization should be a secondary treatment goal of spent ore detox in Focused Feasibility Studies (FFS) for the Summitville Mine. In the FFS (described in a companion paper) for Summitville, spent ore from the heap leach pile (HLP) was loaded into PVC test columns (six inch X ten foot) and was leached with bacteria/nutrient solutions. Two treatment designs were studied: a standard percolation leach (aerobic) and a saturated leach design where the ore was saturated with the heap leach solution to which bacteria and nutrients were applied in a continuous biotreat leach. The bacteria for all column treatment tests were isolated from the spent ore at depth through the Heap Leach Pile (HLP) in the saturated and unsaturated zones. Bacteria isolated from the heap material were tested for cyanide oxidation capacity and were submitted to a bioaugmentation program to improve reaction kinetics and metals tolerance. The final treatment population consisted of several distinct species including aerobic heterotrophs, facultative anaerobes and sulfate-reducing bacteria. The remineralization of soluble metals was observed through a decrease in copper in column leachate solutions and the formation of observable mineral products on ore surfaces in the columns. Several of the tests were run in clear PVC columns to facilitate observation of mineral formation. The column ore contents were photographed before, during and after the biotreatment process which ranged from 10 to 20 days for each test column. Ores were collected from each column after the treatment was complete and were submitted for SEM and TEM study at two laboratories - the USGS SEM Laboratory in Denver, Colorado and the City College of New York SEM laboratory. Treatment Process Description Numerous species of bacteria, fungi and yeasts are capable of accumulating many times their weight in soluble metals. Both living and dead biomass are effective in removing soluble metals from waste streams containing gold, silver, chromium, cadmium, copper, lead, zinc, cobalt and others. Soluble metals may also be immobilized in soils by natural or engineered biomineralization reactions. Several commercial processes using biological reactions are being applied on an industrial scale for metal remediation. Bacteria found in natural and extreme environments have developed a wide variety of metabolic functions to adapt to these environments. These natural microbial functions contribute to global mineral cycling that continuously forms, transforms and degrades minerals and metals in the environment. Biomineralization is described as a surface process associated with microorganism cell walls where the remineralization occurs. The biogeochemical activities initiated by microorganisms in ores, soils, surface and groundwater environments can dominate the formation and transformation of those mineral environments.

Jan 1, 1995

By Werner Wenzel

Methods to increase the gas penetration through sinter layers. In the field of agglomeration, sintering has gained importance, specially in Europe; in Best-Europe this trend will continue till the year 1980, since it is quite probable that in the blast furnace burdens with 50-60 sinter, 10-20 % pellets and 20-25 % ore lumps will be employed. In order to meet this demand for sinter, new sinter bands with reaction areas between 300-400 m2 will be constructed. Chemical and physical phenomena during the Suction-Draught-sinter process. Iron ore sintering is generally considered as a burning process where the material contains 90-95 % ash i.e. non-combustible ingredients. Sintering represents a heterogeneous exothermic reaction in which the chemical phenomena as combustion, calcination, hydration, reduction and oxydation are superposed by physical phenomena. The physical phenomena are devided into material transport and simultaniously occurring heat transport processes. The velocity of these combined physico-chemical reactions i.e. the change in the reaction site per unit time determine the efficiency of the sinter process. The gas permeability as an important criterion of heat transport during the Suction-Draught sinter process.

Jan 1, 1971

By J. A. Pagliero, R. T. Quiroz, S. H. Castro

Selected voltammograms in tetraborate buffer solutions in the presence of ethyl xanthate or isopropyl xanthate at pH 9.3, for chalcocite, covellite, chalcopyrite, and enargite mineral electrodes, are presented. The concept of critical Eh of dixanthogen condensation (Ehc) is introduced, and the line of Ehc is thermodynamically defined in plots of log [X i] vs Eh, for methyl, ethyl, propyl, and butyl xanthates. A reaction scheme of xanthate oxidation in four steps, involving the dixanthogen condensation step, is proposed. A first attempt to interpret mineral flotation from a more general point of view is made. The electrochemical mechanism of dixanthogen formation and condensation is considered as a particular case of a more general and relevant phenomenon, which is the decomposition of the collector giving hydrophobic colloidal forms, whose associative behavior in bulk solution and at the mineral/solution interface is governed by colloid chemistry.

Jan 1, 1989

By S. Bahrampour

One of the basic requirements for designing an optimized rock support for an underground opening is having reasonably enough geological information. It is often financially impractical to obtain detailed geological information about the rock surrounding the excavations. The geological and geotechnical information which are obtained during the construction phase are also usually inadequate and need periodic operation stoppage. Penn State University- J.H. Fletcher & Co. joint venture is to improve the existing instrumented roofbolter so that the 3D geological and geotechnical map of the rock mass surrounding the underground working can be generated real-time as the data is being collected. This information will also be used to design appropriate support for different sections of mines. In this paper, recent results in improving the performance of the measurement while drilling system will be discussed. Moreover, updates related to borehole probing methods for estimating the properties of the rock masses will be presented.

Feb 23, 2014

By F. Milton Lewis

Several alternatives are available for treating lover grade gold ores averaging 0.04 to 0.10 ounce per ton. These include heap, vat and agitation leaching and may involve conventional zinc precipitation or carbon adsorption-electrowinning systems. Each of these processes have their inherent economic and operating advantages and disadvantages and the selection of the optimum method for a given gold ore is solely based on economic evaluation of the applicable processes. In this paper an effort is made to provide engineering feasibility estimates for the above processes under varying operational conditions such as ore grade and price of gold.

Jan 1, 1974

By A. Leppala

Scope of the Courier 300 System The fact that reliable on-stream analysis is a prerequisite for effective flotation control is hardly disputed today. Nevertheless, up to now no system has been available that includes all the equipment necessary for successful analysis. However essential an on-stream analyser is in itself, reliable and accurate assaying can only be assured after techniques for sampling, handling the slurries and computing the X-ray data have been developed for the purpose. The Outokumpu Company's Courier 300 System is a complete package that can be installed and handed over with the key. It includes the equipment needed for sampling and handling the slurries. It has been developed from the start to meet industrial demands. Obviously an on-line system must comply with far stricter standards than one designed for a laboratory. Assays are computed by an Outokumpu 316 digital data processor, which is an integral part of the system and controls its entire performance. The computer software is programmed as a standard package, including a highly advanced new model for assay computation. Analysis output is available for a process computer, report typewriter:, and recorders. The package also includes calibration for slurry assays at our pilot installation before delivery. A complete Courier System can analyse up to 4Z slurries and six elements in each slurry. Thanks to its modular design, it can be dimensioned initially to the customer's requirements and is easy to expand later at low cost. Being a mining company itself, Outokumpu has been able to utilize its own long experience in non-ferrous metallurgy - an important factor contributing to the success of the Courier system. History of the project and present installations The first on-stream analyser was installed at Outokumpu'a Pyhasalmi Con¬centrator at the end of 1967, after several years' development. Since then,

Jan 1, 1971