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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 Kirk Carlton

This paper deals with a group of subjects so familiar to all of us that we might question the need for discussion. Even so, nearly every day's business turns up expensive examples of differences in understanding, misdirected assumptions and incomplete technical purchase documents. As our international activities increase, so do these problem areas. Their expense in both money and embarrassment gives rise to this attempt to focus a little extra attention on technical criteria and specifications. The two terms ?criteria? and "specifications" are, we believe, worth separating with respect to meaning. They should not be used interchangeably, although they often are. Criteria are by definition "standards for judging", whereas specifications are "enumerations of particulars". In relation to plant or project engineering, the criteria are the general rules and data which apply to the whole project and the specifications are the further listing of detailed requirements for specific contractual items or pieces of equipment. We'll look a little more closely at specifications after we give another minute or two to this "criteria" subject,

Jan 1, 1973

By Jiang Su, Michal Uhrin

"The use of composite linings, consisting of permanent sprayed primary and secondary linings with a sandwiched spray applied waterproofing membrane is expected to improve efficiency and reduce lining thickness, but it also brings complex primary-secondary lining interaction. This issue is further complicated by the uncertainty regarding the long-term behavior and parameters of the sprayed concrete–sprayed membrane interface.This paper aims to address this issue by presentation of a series of numerical analyses of a typical shallow SCL tunnel in soft ground with a range of design assumptions on the interface behavior: (1) compression only; (2) compression and tension; and (3) compression, tension, and shear.The results demonstrate that the assumed interface behavior has a significant impact on the primary-secondary lining interactions. A design approach of ignoring the tension and shear bond at the interface may not be conservative particularly for serviceability. This paper explains the rationale behind these conclusions and discusses the implications for design.INTRODUCTIONSprayed Concrete Tunnel Lining SystemsSprayed concrete linings (SCL) have been used in conventional tunneling for decades. However, details of SCL systems may differ to a large extent depending on ground conditions and specific tunneling methodologies.In hard rock conditions, for example, drill and blast excavation is typically supported by rock bolts and sprayed concrete (NGI 2014). Such tunnels are usually designed fully drained and the above-mentioned support elements considered permanent without the need for a further inner liner. Therefore, there is no structural interaction between separate lining shells to consider.In conventional tunneling in the European Alps, a double shell lining is typically utilized, consisting of an outer (primary) sprayed concrete lining and an inner (secondary) cast-in-place concrete lining, separated by a waterproofing system. The primary lining normally includes rock bolts and may include other support elements. The waterproofing system is usually based on a plastic membrane and a geotextile fleece. The tunnel may be designed fully or partially drained or fully undrained. Although there are two structural lining shells interacting, investigation of such interaction is generally irrelevant to designers because the primary lining is considered only temporary (fully sacrificial in the long term). An overview of reasons for this assumption is given, for example, by Lemke (2014). The secondary lining is designed to resist all foreseeable loads on the tunnel. The primary lining may, in reality, interact structurally with the secondary lining during the life span of the tunnel. However, since the secondary lining design must cover all possible (extreme) scenarios, investigation of such interaction does not bring any value to the design."

Jan 1, 2016

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By A. Masutomi

Although great strides have been made during the past two decades in the reduction of the severity of accidents and injuries in underground coal mining, the number of accidents resulting in disabling injuries and lost time has continued to increase. Looking ahead to the 1990s, the reduction of accidents and incidents typically found in these latter categories should be emphasized in safety training for underground coal mining. Loss control is an approach which shows promise for applications in mine safety training since loss-control strategies focus on the pre-contact stages of an incident rather than on the incident, itself. Applied to safety training, the heightened awareness of personnel to workplace hazards at the pre-contact stages should result in a reduction of accidents and injuries. This paper explains the concept of loss control and shows how it can be applied in the development of the needs assessment for miner training programs. An example, based on research conducted at the continuous-miner worksite, is provided.

Jan 1, 1991

By K. Baba

Liberation of valuable minerals from a gangue matrix during size reduction of multiphase mineral particles is an important objective in mineral separation processes. A methodology for the prediction of volumetric grade distribution from one dimensional, linear intercept image analysis is being developed using a transformation function to describe the relations hi p between the linear and volumetric grade distributions. As part of this research effort it has been found that a transformation function, derived from Monte Carlo simulations of irregularly shaped particles, mainly depends on the volumetric grade and the dispersion density, i.e., the number of nuclei (or grains) per particle. A possible mathematical form for the transformation function is described in detail.

Jan 1, 1985

By E. A. Laurila

During last years many different types of X-ray fluorescence analysers have appeared in the market most of these instruments being designed for laboratory use. The instruments applied ins continuous processes are usually modifications of these laboratory types. The application of these instruments to the analysis of heavier elements seems to be quite satisfactory. By lighter elements difficulties are caused by the strong absorption of the characteristic fluorescence radiation, which sometimes makes the use of vacuum or helium chambers necessary. In the following an instrument of another type will be described. It has been developed exclusively for the analysis of titanium in ilmenite concentrate, where the content of Ti02 varies between 43 - 46%. Preliminary measurements have shown that in this interval absolute change of 1% in the Ti02 concentration causes a relative change of about 2% in the intensity. Because: the accuracy of 0.5 % Ti02 is sufficient, 1% relative accuracy should be, attained in intensity measurement. The problem is not very easy to solve due to the fact that Ti K radiation is rather soft and the requirement's for accuracy are rather high. Being applied to the analysis during a continuous process may statistically fluctuating variables in connection of sampling and disturbances of many kind set special requirements for the instrument design.

Jan 1, 1960

By K. A. Natarajan, K. Karthiga Devi

"A biodegradable flocculant was produced during growth of Bacillus megaterium. The major component of the bioflocculant was found to be a polysaccharide composed of some proteins. Fourier transform infrared (FTIR) spectra analysis revealed the presence of carboxyl and hydroxyl groups in the bioflocculant, and thermal characterization by differential scanning calorimetry (DSC) showed the transition and crystalline melting point at 90-105°C. The effects of bioflocculant dosage and pH on the flocculation of mineral suspensions were evaluated. The bioflocculant exhibited good flocculating capability on mineral suspensions and achieved flocculating efficiencies of 90 percent for kaolinite and 85 percent for hematite suspensions at a dosage of only 5 mL/L. The maximum arsenite removal was found to be 90 percent at a bioflocculant dosage of 2 g/L, which is better than traditional chemical flocculants. This study demonstrates that microbial bioflocculants have potential for application in environmental cleanup, such as in the flocculation of mineral fines and in the remediation of solutions that contain toxic heavy metals.IntroductionBioflocculants are biopolymers produced by microorganisms during their growths. The predominant components of a bioflocculant are extracellular polymeric substances such as glycoprotein, protein, cellulose and nucleic acid (Salehizadeh and Shojaosadati, 2001). Bioflocculants have gained much wider attention due to their biodegradability and safety. In recent years, the study of bioflocculants has attracted wide attention. Bioflocculants can be nontoxic, harmless and eco-friendly. Normally, they exhibit different functional properties, serving as stabilizer, dispersant or thickener. Among these properties, flocculation is of major interest. For example, Phormidium sp. strain J-1, isolated from a drainage channel, exhibited excellent flocculation activity for bentonite particles in liquid suspension (Fattom and Shilo, 1984). A protein bioflocculant produced by Rhodococcus erythropolis could efficiently flocculate suspended solids while losing their flocculating activity by enzymatic digestion (Kurane et al., 1994, Takeda et al., 1991). Klebsiella sp. strain S11 screened from activated sludge was unable to flocculate without the addition of calcium chloride (Dermlim et al., 1999)."

Jan 1, 2015

By M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas below natural groundwater elevations, necessitating dewatering and some method of disposal of the extracted water. These open pits extend well below the water table, with associated dewatering volumes greater than 10,000 gpm. Some mines, with large volumes of dewatering water to manage, have constructed re-infiltration basins to re-introduce dewatering water to the groundwater system some distance from the pits. This paper presents an overview of the state of the art of re-infiltration projects, including the permit process for such projects in Nevada, and the necessary engineering considerations.

Jan 1, 1996

By Kathleen Kreiss, A. James Ruttenber

INTRODUCTION Early in the morning of July 16, 1979, there was a breach in the earthen retaining dam of a tailings pond at the United Nuclear Corporation's (UNC's) Church Rock uranium mill. The acidified liquid and tailings slurry spilled through the damaged portion of the retaining wall into an arroyo that is a tributary to the Rio Puerco river system. The Rio Puerco runs through Gallup, New Mexico, and eventually crosses the New Mexico-Arizona border (Fig. 1). On its way to Gallup, the Rio Puerco and its tributaries pass through land with a checkerboard pattern of ownership, with portions owned or leased by the Navajos, individuals, the Bureau of Land Management, and the State. In terms of tailings liquid volume (3.6 x 108L; 94 million gal), the UNC spill ranks as one of the largest. The mass of solids released in the slurry (10.0 x 105 kg; 1 100 tons) appears to be close to the median for accidents of this kind, however [U.S. Nuclear Regulatory Commission (NRC), 1979]. The UNC first opened its Church Rock uranium mill in 1977 on land adjacent to acreage belonging to the Navajo tribe. The mill, which is next to the UNC Church Rock mine, is located approximately 16 km (10 miles) northeast of Gallup, New Mexico (Fig. 1). Gallup, a town of 18 000 people, is the closest population center. The region surrounding the plant site is sparsely populated by Navajos, at a density of approximately 5.8 persons/km2 (15 persons/sq mile). The UNC mill and mines employ approximately 650 persons, and the adjacent Kerr-McGee uranium mine employs about 300. The UNC mill normally processes 3.2 x 106kg/day (3 500 tons/day) of uranium ore, depositing the acidified tailings slurry in a series of three earthen holding ponds. The tailings ponds are located east of the pipeline arroyo that feeds into the Rio Puerco approximately 2.4 km (1.5 miles) from the southernmost tailings dam. The liquid portion of the tailings slurry evaporates in the ponds; hence, under normal conditions, there is no surface flow from the holding ponds to the arroyo. Both runoff from the plant site after heavy rains and possible seepage from the tailings ponds may deliver radionuclides to the arroyo-river system, however. The dam across the southernmost tailings pond was considered to be in keeping with the state of the art. However, the New Mexico Environmental Improvement Division (NMEID) had warned UNC about dangers of locating the pond over a heterogeneous geological formation. The state Engineer's Office approved of the site only after UNC agreed to strict design criteria. Others have pointed to dangers of constructing earthen dams for impoundment of uranium mill tailings (Carter, 1978). Causes of the dam break were multiple: the UNC mill filled the tailings pond to a level that exceeded permit criteria; the tailings pond was lined improperly; the dam was constructed using clay that was compacted excessively, resulting in cracking and subsequent seepage; and the unstable substrate beneath the dam permitted differential settling. The UNC Church Rock mine has continuously released dewatering effluent into the pipeline arroyo at a rate of 88.3 L/sec (1 400 gal/min) since 1968. Before 1975 this effluent was not treated; after 1975 it received precipitation treatment for removal of Ra-226. Radionuclides are also released into the river system through the dewatering of the Kerr-McGee uranium mine 1.6 km (1.0 mile) north of the UNC mill. During usual mining operations, approximately 227 L/sec (3 600 gal/min) are released into the pipeline arroyo and subsequently into the Rio Puerco. The Kerr-McGee mine began continuous release of dewatering effluent in January 1972. In 1974 Kerr-McGee began Ra-226 precipitation treatment of its dewatering releases, but NMEID data indicate that treatment has often been incomplete. The effluent from both mines has been responsible for transforming the downstream portion of the Rio Puerco from a sporadically dry riverbed into a continuously flowing stream and has contributed to the current levels of background radiation along the river system (Table 1). This paper will summarize the postspill monitoring efforts and relate the assessment of this spill to the general question of evaluating the health effects of nuclear fuel-cycle wastes. The data pertaining to the measurement of radionuclides in the Church Rock environment and the radionuclide concentrations in animals will appear in forthcoming reports. CHURCH ROCK HEALTH EFFECTS ASSESSMENT APPROACH The initial health effects evaluation involved identifying the radionuclides that were released into the river system from the tailings pond. Table 1 lists the State of New Mexico maximum permissible radionuclide concentrations for liquids released to unrestricted areas, the typical tailings liquid concentrations, and postspill river water concentrations. The tailings liquid contained comparatively high levels of Th-230, Ra-226, Pb-210, and Po-210--all of which, according to postspill river water samples, had exceeded the state maximum permissible concentrations (MPC) at one time or another. After the radionuclides in the tailings were identified, pathways through which humans could be exposed were clarified. Environmental monitoring data were then used to quantify the important pathways of human exposure. Water samples were collected from the river, from test wells dug near

Jan 1, 1981

By D. N. Madge

A survey is given of production scheduling systems currently in use or contemplated for future use in Cominco operations. Emphasis in this presentation is made on the chain of decisions that are made with the help of mathematical programming models. Some attention is devoted to the structural properties of the models.

Jan 1, 1966

By Sandeep Upadhya, Marc Morgan, Baljinder Bassi, James Fletcher, Mike Deevy, Nishant Nayan

"In order to protect public safety in the event of a deliberate fire attack, underground rail authorities are increasingly considering the need to design for arson-initiated fire scenarios. Where typical design fires for modern rolling stock mean a peak fire size is reached after 12 minutes, an arson-initiated fire reaches its peak within 2-3 minutes. We present the innovations required to successfully incorporate this requirement on a recent design-build project. In stations 3D modelling is used to optimise smoke reservoir designs, smoke chimneys, station boxes and tunnel geometry to allow coordination with structural requirements. In tunnels, novel coupling of one dimensional network modelling and 3D Computational Fluid Dynamics (CFD) is used to improve assessment of complex fire scenarios. Finally, the impact on tunnel structures is assessed through comparison with standard time-temperature curves and risk of explosive spalling. INTRODUCTION An increasing regulatory environment and the appreciable influence that terrorist incidents have had on public safety policy have motivated the need to protect against large arson fires, especially in civil structures and public transport systems. With a greater reliance of a growing urban population on underground subway systems, design of such infrastructure is continually being reassessed and developed worldwide. Underground rail authorities are paying increased consideration to the design of fires - with properties beyond the upper regions of growth and intensity - amongst arson fire studies. Use of fire hardened materials on modern rolling stock means fires caused accidentally can be expected to develop relative slowly. However, recent experiments involving large initiating fires (as would result from an arson attack) have shown rapid fire growth rates and flashover leading to greater maximum heat release rates, Hadjisophocleous (2012), White (2010), and Lönnermark, et al. (2015). This paper describes the challenges and innovations required to complete a detailed design to control smoke from such aggressive super-fast growing fires. Computational modelling is used to demonstrate the required smoke control design by configuring the mechanical exhaust system combined with careful coordination with the architectural and structural design. The design objectives are to provide tenable egress paths in accordance with NFPA 130 (2014) and fire-fighting access. Finally, analysis of the design fire is used to inform the tunnel lining design, reducing the risk of explosive spalling, protecting the asset in the event of a severe fire."

Jan 1, 2016

By Brij M. Moudgil, Shoulian Zhu, J. L. Pinault

A new technique, prompt neutron activation probe (PNAP), for analyzing phosphate rock slurry in-situ was evaluated both in the laboratory and at the plant. The technique yielded a high precision in the analysis of Ca, Si and H using 252Cf source. Low accuracy of the direct measurement of P using 241Am/Be in the laboratory tests was attributed to the interference of rare earth elements present in the samples, particularly Gadolinium. No significant effect of variables such as solids loading, particle size distribution, and flotation reagents was observed on the probe performance. The probe can detect the compositional changes of the feed, tailings and the concentrate streams in the plant.

Jan 1, 1993

By J. Gawler

In June 2005 the Minerals Council of Australia signed a Memorandum of Understanding (MoU) with the Australian Government which states an intention ?for mining companies and government to work together with Indigenous people to build sustainable, prosperous communities in which individuals can create and take up social, employment and business opportunities in mining regions?. Implementation of the MoU has begun with demonstration sites established across Australia. All sites are using a Regional Partnership Agreement (RPA) model as a framework for enabling local people to find local solutions to local issues in partnership with mining companies, governments and Indigenous communities. Mining and resources companies can provide important input into regional economic development and capacity building by working through local partnerships. Company benefits include gaining a social licence to operate, access to a reliable skilled workforce, better longterm relationships with Indigenous communities and sustainable regional communities. All levels of government, Australian, State and Local, are working collaboratively to address unemployment and other issues in remote Indigenous communities. The Australian Government has adopted RPAs as one mechanism for implementing its whole-of-government approach to Indigenous affairs. This leading edge work is unique to Australia and the model has applications and significant learning for other countries and industries.

Jan 1, 2007

By F. L. Pierson

Since the discovery of 'potash in the Carlsbad area in 1926 and the start of mining operations in 1931, "first mining," operations have been carried on. This is a room and pillar system in which approximately 62% of the total ore is removed. Or the basis of ore reserves and rates of extraction, the life of the mine in the early; days was estimated to be well over 50 years, however, even with an increase by additional ore reserves, it became increasingly apparent that the life of the mine was being shortened considerably by increased production. Further cause for the shortening of mine life was due to the exceptionally weak back over the northeast quadrant of the main orebody which had .caved in on first mining up to a height of 8 feet. Thus, in 1953 the decision was' made to begin pillar pulling, also called, second mining or final mining, and in December of 1953 this program was started after much discussion.

Jan 1, 1965

By Gerald P. Kelton

Over the past quarter of a century, the success of the hydrocyclone as a classifier in closed circuit grinding installations has permitted the introduction of the cyclone into virtually all fields of wet industrial processing. Research and experience gained in these applications have established the optimum cyclone sizes and designs necessary to provide the required performance. Although cyclones are used in widely diverse liquid-solid applications, their use for ultrafine separation clearly demonstrates the importance of a familiarity with previous case studies. Krebs Engineers is firmly dedicated to serving the process industry and has acquired the unsurpassed knowledge and experience to handle all types of separations and classification problems. Cyclones have been used for a number of applications to make what might be considered fine separations. A typical example is in an iron ore grinding circuit where a 381 mm diameter cyclone will classify an overflow product to 85% -44 micron. There is no question that this is a fine separation, but still finer separations are possible, and these are known as ultrafine separations.

Jan 1, 1983

By Vincent C. Grimshaw

High pressure fluid energy grinding, or jet milling, is a versatile method of continuously fracturing solids into fine particles to gain substantial increases in exposed surface area. Applications in the minerals industries include calcium carbonate, talc, barytes, mica, diatamaceous earth, bauxite, rutile, coal, kaolin, sepiolite, diamonds, etc. The basic principles can be extended to provide continuous drying and delivery of discrete particles from a wet process slurry. The main design and operational features of jet mills and dryers are described, relating energy consumption for both air and steam milling and hot air drying techniques. Mean particle sizes in the order of 1 micron are achieveable from pre-milled feeds, or maintained from similar slurries in the drying mode. Aspects of feed preparation and multi-stage processing are discussed.

Jan 1, 1983

By Paul Eimon

In the world of minerals exploration, computer-oriented data storage and retrieval methods are being talked about, studied and researched. The goal is to facilitate the recording, collating, indexing, recovery, and analysis of mineral deposit-prospect data. A survey has been made of the various report forms, suggested outlines, and computer coding forms that are currently used in mineral exploration to index and/or describe mineral deposits and prospects. These forms have a number of common characteristics: location, commodities, type of deposit, host rock, etc. Such basic mineral deposit-prospect "data units" are part of most exploration programs. "Data units" may be comprehensive bound published descriptions of mines or mining districts or 3x5 file cards or elaborate computer coding forms being developed in Canada. Initial attempts to develop computer-oriented information systems have run into the same roadblock: the lack of a body of organized, processible data describing the basic qualities of mineral deposits and prospects. To solve this problem, international committees are considering coding forms, world-wide semantics, and rules or standards for data collection and description. It appears that mistrust and lack of understanding of the computer; fear of loss of proprietary information; and disagreements over terminology are distorting the picture of what has to be done if the mining industry is to grow into more meaningful information systems for mineral exploration.

Jan 1, 1969

By Kevin Fitzpatrick, Carmen Scalise, Patrick Jensen

"The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) owns and operates the Tunnel and Reservoir Plan (TARP) system which was adopted in 1972. TARP is a network of 110 miles of deep tunnels and ultimately 3 large reservoirs to combat waterway pollution and flooding within a 350 square mile area served by combined sewers. The original TARP concept included additional tunnels to convey CSOs from the largest storms to the reservoirs. With the initial TARP tunnels complete and the reservoirs nearing completion, MWRDGC commissioned hydraulic and hydrologic modeling studies to analyze the benefits of additional conveyance tunnels. These updated studies optimized the configuration of additional tunnels considering integration with potential future local sewer system upgrades. The alternatives considered several routes of 25, 30, and 35 foot diameter tunnels, ranging from 10 to 18 miles. Alternatives were analyzed based on projected reductions to basement flooding compared to the relative costs. TUNNEL AND RESERVOIR PLAN After World War II the Chicagoland area underwent rapid growth and development. With the Metropolitan Water Reclamation District of Greater Chicago's (MWRDGC) service area becoming increasingly impervious, the flat Chicago landscape was increasingly at risk of significant flooding. In the mid and late 1950's, Chicago experienced multiple extreme storm events that had significant impacts on the city and generated the momentum necessary to initiate what would ultimately become one of the world's largest civil works undertakings. In 1957 a Flood Control Coordinating Committee was formed, consisting of representatives of the MWRDGC, Illinois Department of Public Works, Cook County, and the city of Chicago, to review various plans and develop recommendations for a course of action. With more than 50 alternative concepts being identified, the Tunnel and Reservoir Plan (TARP), which itself is a composite of various alternatives, was adopted the by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) in 1972. The need to adopt a long term plan was further influenced by the Clean Water Act, which was enacted only 8 days prior."

Jan 1, 2016

By R. L. Teseneer

Pyrite samples from twenty-one locations in the North Carolina Slate Belt were analyzed for cobalt, gold, mercury, and nickel by atomic absorption spectrophotometry. The geographic distribution of relatively high values of certain trace elements in pyrite suggests that, in addition to gold, cobalt and nickel metallogenetic provinces are possible in the slate belt. Northwest trends of province boundaries may be genetically related to subsurface features rather than to surface geology. Within province boundaries gold and nickel exploration programs should be concentrated in areas containing intermediate to mafic tuffs, while cobalt may be more concentrated in argillites and phyllites.

Jan 1, 1979