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By Yadong Xue, Fei Wang, Hongwei Huang, Yan Sun

"Increasing attention to subway tunnel maintenance is being paid with the high speed development of urban rail transit system in China. A novel moving tunnel inspection equipment based on machine vision is developed in this paper. High resolution image acquisition system is proposed for tunnel crack and leakage inspection. The main components of this image acquisition system includes high speed CCD cameras, linear lights and high performance computer. To inspect the crack less than 0.3mm with a 3-5km/h speed in subway tunnel, we need to consider resolution and line rate of camera, pixels of cameras, range of inspection and illumination intensity of lights simultaneously. The optimization design is proposed to make the equipment more convenient for tunnel use. Entire tunnel situation can be detected and recorded in a single inspection process. This equipment has already been verified in Shanghai subway tunnel for defects inspection.1. INTRODUCTION In China, the quantity of subway tunnel has reached a large scale in recent years. Until 2014, there had been more than 2300km of subway tunnel in China which accounted for nearly three quarters of Chinese urban railway system (Zhang Chen,2015). In some metropolises like Beijing and Shanghai, most of the metro tunnels has already run over 20 years which within maintenance phase. This has brought about plenty of inspection work and maintenance work to guarantee the tunnel under the serviceability limit states. The increase of running mileage of subway tunnels in China has been displayed in Fig 1."

Jan 1, 2016

By M. Kul

In this study, the effects of various extraction and stripping parameters, such as equilibrium pH (7.0, 8.5 and 10), extractant concentration (5, 10 and 20 volume %), organic-to-aqueous (O/A) ratio and stripping agent type and concentration were studied on chromium (VI) recovery from chromium electroplating rinse bath wastewater using Aliquat 336. Results showed that these parameters all had significant effects on chromium (VI) recovery. A pregnant strip solution from a chromium electroplating rinse bath wastewater with 33.4 g/L chromium content, suitable for sodium dichromate production, was generated by 20 vol. % Aliquat 336 in commercial kerosene. The O/A ratio was 1/4 and the equilibrium pH value was 0.87, the as-received pH value. The wastewater was treated with a two-stage countercurrent extraction process to produce a loaded organic phase, which was later stripped at the O/A ratio of two with a 4-M NaOH solution in a two-stage countercurrent stripping process using Taguchi?s optimization technique.

Jan 1, 2010

By A. R. Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Nines Camchib Inc. It is characterized by very fine first generation gold and very coarse second generation electrum. Successful processing required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented.

Jan 1, 1989

By Renfeng Song, Shaoyan Wang, Zhiqiang Zhang, Ke Guo

Leaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

Jun 16, 2021

By K. L. Johnson

Networks of monitoring wells were established prior to mining at four longwall mine sites in the Appalachians to monitor the effect of mining on water levels, water quality and well yield. Two of the sites were located in stream valleys and the other two sites were located on hilltops. The depth to the mined seam ranged from 500-850 feet with the deeper cover being associated with the hilltop sites. Maximum declines in groundwater levels during and after mining were an order of magnitude less in the stream valley aquifers than in the hilltop aquifers. However, water levels in hilltop wells located outside the area immediately above the panel were unaffected. Water quality changes in wells as a result of longwall mining were negligible at all four sites. Increases in aquifer transmissivity and well yield were much more pronounced in the stream valley aquifers than in the hilltop aquifers. The significantly larger recharge area for the stream valley aquifers than that for the hilltop aquifers may partially account for the differing responses of these two classes of aquifers to longwall mining. These observations appear to be consistent with the stress-relief fracture model for Appalachian Plateau groundwater hydrology proposed by Wyrick and Borchers in 1981.

Jan 1, 1986

By A. T. Yu

There are compelling reasons for us to look to our Country's Western coal. Despite its inherent low BTU content, Western coal's low sulphur content provides a near-ideal answer to satisfy our in- dependent goals of clean air and self-sufficiency in energy. Vast reserves, thick seams and amenability to low-cost strip mining serve as a powerful economic basis for its viability as a primary and dependable source of energy for the coming decades. A major consideration, the solution of which may not be quite obvious, is transportation cost. These abundant deposits are remote from the utilities of the heavily populated eastern regions of the United States (Figure 1). A Western coal mine in Montana is likely 1500 miles or more from an eastern power plant. The comparable distance to an eastern coal mine may be only 200 miles. Thus, the question is: How can the haulage cost of our Western coal be substantially reduced to an acceptable level? If resolved, western reserves of coal will be one of the key solutions to satisfying our Nation's energy needs.

Jan 1, 1975

By David M. Abbott

This paper is a companion to, and amplification of, the ?History? section of the 2014 version of the SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (SME Guide). The need for the careful examination and evaluation of mineral deposits has long been recognized. In the book De Re Metallica, Georgius Agricola noted, ?Moreover, a prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him? (1556, p.29). Agricola further stated, ?Now a miner, before he begins to mine the veins, must consider seven things, namely: the situation, the conditions, the water, the roads, the climate, the right of ownership and the neighbors? (1556, p. 30). The elements of Agricola?s seven things, much expanded, are incorporated into the 2014 SME Guide. As reflected in this quotation, veins were the primary concern of mining until 20th century technology permitted bulk mining techniques. The need for standardization of reserve descriptions arose along with the development of western mining in the United States and the concurrent development of mining engineering and mining geology as professions. By the turn of the century, debate about terminology of various classes of reserves was in full swing. Herbert Hoover noted in 1909 (p. 16-17), ?The old terms ?ore in sight? and ?profit in sight? have been of late years subject to much malediction on the part of engineers because these expressions have been so badly abused by the charlatans of mining in attempts to cover the flights of their imaginations. A large part of Volume I of the Institution of Mining and Metallurgy has been devoted to heaping infamy on these terms, yet not only have they preserved their places in professional nomenclature, but nothing has been found to supersede them. ?Some general term is required in daily practice to cover the available field of visible ore, and if the phrase ?ore in sight? be defined, it will be easier to teach the layman its proper use than to abolish it. In fact, substitutes are becoming as badly abused as the originals ever were. All convincing expressions will be misused by somebody.? Hoover (1909) noted that the common terms at the time were: ? Positive ore or ore developed: Ore exposed on four sides in blocks of a prescribed size. ? Ore blocked out: Ore exposed on three sides within a reasonable distance of each other. ? Probable ore or ore developing: Ore exposed on two sides, ? Possible ore or ore expectant: Ore in whole or in part below or beyond the range of vision. Hoover stated that these, and similar terms, overlapped and had the difficulty of failing to account properly for geologic variation in metal distribution beyond the exposed face. Certainly assuming extension of values along a vein is reasonable, but how far? Also, these definitions are for vein deposits, not all types of deposits are in veins. Hoover (1909, p. 19), therefore, defined the following terms. ? Proved ore: Ore where there is practically no risk in failure of continuity. ? Probable ore: Ore where there is some risk, yet warrantable justification for assumption of continuity. ? Prospective ore: Ore that cannot be included in the above classes, nor definitely known or stated in any terms of tonnage.

Feb 1, 2014

By G. Simmons

Santa Fe Pacific Gold Corporation (SFPGC) conducted pressure oxidation pilot plant studies at Hazen Research, Inc. on the Twin Creeks refractory carbonaceous gold ores during 1993 and 1994. Previous laboratory investigations demonstrated very good gold recoveries of 90 to 95%, using CIL cyanidation after batch pressure oxidation. However, results from the pilot plant showed that several ore types responded very poorly, with gold extractions of only 45 to 75%. Since these poor recoveries were unexpected, pilot plant testing was suspended for approximately four months while extensive research activities were conducted to determine the cause(s) and identify potential solutions. This paper describes the batch and pilot plant test results, the research activities that eventually identified the cause of the gold recovery problem, and the final semicontinuous and continuous pilot plant operations that confirmed possible solutions.

Jan 1, 1997

By Tracy T. Morris

The current state of the mining community has made it imperative for operations to reduce costs and increase productivity in order to remain competitive. This has been done in Colorado with the installation of an Outokumpu flash flotation machine for the production of a gold/silver/lead concentrate.

Jan 1, 1987

By D. J. Miller

Environmental considerations are extremely important in planning and carrying out mergers, acquisitions and real estate transfers. It is not inconceivable that potential or actual environmental liabilities could exceed the targeted company's net worth or the book value of the real estate of interest. It is therefore essential that an environmental due diligence investigation (DDI) be performed to quantify environmental liabilities before sales, mergers or acquisitions. This paper will discuss general procedures used in environmental due diligence investigations. The emphasis will be placed on mergers and acquisitions. It should be pointed out that the procedures discussed in this paper are general and must be modified to fit each particular merger or acquisition under consideration.

Jan 1, 1988

By K. Johnson, B. Schiffer

Demonstrating aquifer restoration is an essential component of regulatory approval needed to mine uranium, copper, and other minerals by in-situ recovery (ISR). A PHREEQC geochemical model provided a useful means of forecasting the time for restoration and predicting future groundwater quality following low pH mining at Strata Energy’s Ross ISR Project in northeast Wyoming. The model simulated groundwater quality at three phases of the process: at the end of mining; during restoration; and post- restoration. The model utilized the one-dimensional reactive transport and dual porosity features of PHREEQC. Mineral surface ion-exchange, dissolution/precipitation reactions, and adsorption processes were simulated to estimate water quality as the pH was shifted from circumneutral to acidic during mining and back to neutral during restoration. The model results showed that cost-effective management of mine water could meet regulatory requirements. Additionally, the model was used to interpret results from a field trial and inform operational decisions. The predictive approach and geochemical understanding developed have application in assessing aquifer restoration for other ISR projects.

Mar 2, 2022

The first form of a surety bond was an honest handshake between two or more parties, agreeing to a decision and their personal guarantee of following through to completion. This has all changed. In 1895, the United States Treasury Department disclosed that $35 million worth of personal surety guarantees on file had become worthless. At that time, a law was passed, requiring all surety bonds, in favor of the United States, must be corporate surety bonds. Today, a surety bond is one of the nation's leading financial instruments used to guarantee the completion of an obligation.

Jan 1, 1989

By Daniel de la Rosa, Juan Manuel Mayoral, Damián Vital

"This paper presents a numerical study regarding the loads, and the corresponding damage, taken by the primary and secondary lining of a tunnel built in cemented fine-grained stiff soils. This study aims at establishing more rational design criteria that take into account explicity the lining performance. A 3.5 km long tunnel to be built in a densely populated northwest area of Mexico City, was considered as case study. Series of three-dimensional finite difference models, developed with FLAC3D, were used to simulate the tunnel construction, and to compute the ground settlements, internal forces, bending moments, and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams were used to study the lining performance. Several advancement lengths, and tunnel covers were considered to establish their impact on the loads transferred to the tunnel lining. A practice-oriented damage criterion for tunnels was proposed based on the interaction diagram analysis. INTRODUCTION Lining performance during conventional tunnelling, CT, as defined by the International Tunnel Association, ITA (ITA 2009) is strongly affected by the construction procedure. Special attention must be taken in cemented fine-grained materials, such as those found in the northeast portion of Mexico City, due to the potential of fragile failure (i.e. the soil fails suddenly without important deformation) that these soils may exhibit. During CT, it is assumed that the ground strength contributes to the stability of the excavation, as long as the lining is built correctly. It is common practice to consider two structures, which together form the tunnel support: 1) A primary lining, which is a flexible support, which allows excavation walls to deform to mobilize part of its shear strength, and thus contributes to the tunnel self-stability, and 2) A secondary lining. Commonly, the primary lining consists of several layers of shotcrete. In this case the installation method guarantees perfect contact between the lining and the excavation perimeter. The secondary lining, if required, is used to withstand the load conditions in the long term and also has an esthetic function. This paper presents a numerical study aimed at establishing a performance damage criterion for the primary and secondary lining design in cemented fine-grained stiff soils. Due to the lack of data, the strength and deformation parameters were established through empirically-derived relationships. Three-dimensional finite difference models were developed to simulate the tunnel construction, and compute ground settlements, internal forces, bending moments and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams, along with a damage criterion were used to study the lining performance. From the results gathered insight was gained regarding tunnel lining performance during CT."

Jan 1, 2016

By J. H. Mackey

"Where can I obtain a reclamation bond today?" "Who is writing your bonds?" These questions are common and heard frequently. The fact that the Society of Mining Engineers has determined that two of the five environmental topics reviewed at the 1989 Annual Meeting relate to reclamation bonding indicates to me that those who are involved in the coal industry, no matter what capacity, remain very cognizant of the reclamation bonding dilemma.

Jan 1, 1989

By Anthony Iannacchione, Tim Miller, Nicole Evanek

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone near Petersburg, OH. In February 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage was concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increased distance between crosscuts, arched crosscuts, cable-bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts.

By B. Fagerberg

Crushing and grinding practice in Sweden follows largely the international pattern. Certain special circumstances, however, have had an influence on the development. Most mines are worked underground in either quite small or in very large units. To utilize small sulphide ores, custom milling is rather common. Apart from the cement industry, the rock species treated are hard and abrasive. Another important factor is the increasingly strict requirements placed on the mechanical condition of different products, especially lump ores and coarse iron ore concentrates. A significant feature in the design and development of Swedish crushing and grinding practice has also been close cooperation between machinery manufacturers and the users. An account of these conditions and an outline of the crushing and grinding techniques employed in Sweden are presented in this paper with emphasis on the mining industry. For background purposes it may be mentioned that crude ore production in Sweden last year included 45 mill. tonsx) of iron ore, of which some 20 mill. tons from Kiruna alone, and 4 mill. tons of sulphide ore from 22 other mines, fig. 1. In addition 8 mill. tons of limestone were quarried for cement production and several million tons of stone and sand for roads, aerated concrete, etc.

Jan 1, 1968

By R. Jerez

This paper describes practical applications of lineal" programming techniques to help in the planning of production, transportation and shipments at different coal mines. The models are being used by Cyprus Coal Company in eastern and western operations to plan coal production, economic dispatching and blending over variable time horizons. In addition, where a preparation plant exists, the models establish the amount of washing required to meet specific coal sales qualities. The emphasis on this paper is on model development and implementation together with a system to track coal flow and qualities, either raw from the mines to the loading facilities 01" processed through a preparation plant.

Jan 1, 1991

By M. McPherson, P. Mousset-Jones, G. Danko

Calculation of the sensible heat transfer between the rock surface and the flowing air in an underground airway is still fraught with problems. There are only a few results available in the literature for the calculation of the convection in tunnels with naturally rough surfaces. Some of them are purely empirical, while others use a theoretical approach, based on the analogy between heat and momentum transfer, expressing the heat transfer coefficient as a function of the friction factor. A review and evaluation of these results are presented. The heat transfer equations obtained using the different assumptions, vary over a wide range, so that experimental results are needed to determine the formulae and constants applicable to mine airways. In situ measurements of the "physical" and "technical" heat transfer coefficient carried out in deep mines are described. The statistical distribution of the convective heat transfer coefficient on rough surfaces, as well as the regression between the Nusselt and Reynolds numbers in the turbulent flow region, are presented. Radiative heat transfer between the surface and the moist air flowing in a duct of relatively large hydraulic diameter has been taken into account during evaluation. The results will be a definite refinement of those calculations presently used in mine climate simulation models.

Jan 1, 1987

By Harry R. Dahlberg

Heap leaching is discussed as a unit process. Five factors are identified as the principal elements that can be measured and/or controlled. These are: 1. Material Size 2. Volume of solution 3. Tonnage of heap 4. Time 5. Solution concentretion. The Rate of Extraction Curves obtained from an actual heap or column tests describes the economic viability of the unit process. By analysis of these curves and the five factors end their inter-relationship it is possible to determine how the extraction rate can be increased. The practice of leach and rest used by many operators is analyzed and shown on a hypothetical rate of extraction curve. The influence of the driving force of the hydrogen ion and ferric Lon as Lixivants and its effect on the rate of extraction curve is discussed.

Jan 1, 1979

Mining was the first economic activity carried out in Cuba, by the colonial conquerous, i.e. gold extraction from rivers and use of asphalt to calk their ships; however, due to different historic reasons only a limited development took place in this field during the colonial domination. During the republican period beginning early in this century, other interests lead to a larger scale exploitation of some known deposits. From the beginning of the century up to the triumph of the Revolution in 1959, not less than the following figures were extracted of some Cuban minerals: Refractory Chromium 3,300,000t Manganese 7,650,000 t Copper 9,000,000 t Iron 22,000,000 t Nickel 150,000 t (Ni oxide and sulphide These productions were practically directed to cover the demands of the U.S., industry and some-times these Cuban ores were almost the sole suppliers of the market.

Jan 1, 1978