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By J. A. Finch, Zhenghe Xu, Z. A. Zhou

A particle-bubble collision model was used to investigate the minimum recovery zone height, H(r,min) required for flotation columns. The criterion used to define H(r,min) is that height which gives unit collision probability. It is shown that H(r,min) is determined by particle and bubble size, gas hold-up and bubble-bubble interaction. Under typical operating conditions, for flotation of particles less that 10 micrometres in size H(r,min) is greater than 10 m, but it reduces to less than 1 m for particles greater than 100 micrometres

Aug 1, 1995

During the last 20 years, more than 80 km (50 miles) of tunnels have been constructed in the Los Angeles, CA area. Recent projects include The East Central Interceptor Sewer (ECIS), completed in 2004. It spans more than 18 km (11 miles). The Northeast Interceptor Sewer (NEIS), completed in 2005, spans 11 km (7 miles). And the 2-km (1.3-mile) Metropolitan Transportation Authority?s Gold Line Eastside Extension (MCGLEE) was completed in 2006. All of the tunnel routes lay beneath heavily populated urban environments so minimizing ground surface settlement was critical to the success of the projects. Previous tunneling efforts in the Los Angeles area using open shield methods resulted in significant settlement that damaged roads, utilities, buildings and other structures. Earth pressure balance (EPB), or slurry machines, were specified for these projects to reduce subsidence risk. The contractors chose EPB tunnel boring machines (TBM) for the work. The closed and pressured face of the EPB TBM reduces loss of ground at the tunnel face and, when the machines are used in combination with gasketed pre-cast tunnel liners and backfill grout behind the installed segments, losses from over-cut of the excavated surface are also reduced.

Jan 1, 2008

By Caio Moreira, Saulo De Rezende, Nelly Ruíz

The present project sought alternatives for this material through the Mining Lab Beginnings program, which was developed by Nexa in partnership with Escalab to find solutions for the company's highly complex challenges. Through the program, several solutions were evaluated, with additives for the construction market being the most prominent. Tests were conducted to confirm the efficiency of jarosite in the mixture that composes this material. With successful laboratory tests, the technology was tested on an industrial scale, where it also demonstrated its technical and economic viability. The project is now moving into the operational phase, demonstrating that circular economy is the best solution for disposed tailings.

Sep 29, 2023

Failure of rock materials is a process of crack propagation. Crack initiation takes place when the crack tip stress intensity K reaches a critical value called fracture toughness, K1C. The rock fracture toughness is known to be affected by the surrounding environment such as temperature, confining pressure and humidity. In order to examine the effect of humidity, a series of semi-circular bend tests were performed under various water vapour pressures in a rock material that is known to be anisotropic. Water vapour promotes stress corrosion of rock and therefore the fracture toughness was found to have a decreasing trend with increasing water vapour pressure. The rate of decreasing the fracture toughness depends on the microcrack density that promotes the migration of water vapour into the rock. Also in an anisotropic rock, the fracture toughness depends on the direction of crack in relation to the anisotropy of the rock material.

Dec 6, 2010

By Steve Kral

Improved metals and other commodity prices have caused the mining industry to open new mines, re-evaluate development opportunities at potential mines and increase production at existing ones. This sense of renewed optimism is being seen at operations and development projects around the world. Except in the United States. The regulatory structure there has not allowed the domestic industry to share much in mining’s resurgence. It can still take up to 10 years to permit a new mine. And, while Clinton-era regulations regarding mill sites have been put on hold, existing mines that wish to expand operations still face significant regulatory and environmental hurdles. But things may begin to improve in the United States.

Jan 1, 2005

By R. England

"This paper describes the objectives and design parameters for the operation of a computerized In-The-Hole (I. T.H.) Drill. The principal objective is to add computer control to an Inco 00-60 I. T.H. (CMS-CD-90) drill in order to drill holes with greater accuracy. The computer provides control of the angle of the hole by maintaining the orientation of the drill head, and optimizes the straightness of the hole by maintaining a constant force on the drill bit.The second objective is to provide the greatest degree of operational automation, so the objective outlined above can be accomplished with a minimum of operator intervention.In order to provide full operational automation it was necessary to also provide the capability for the computer to add and remove drill rods. To accomplish this, a rod-handling mechanism consisting of a rod storage rack and rod manipulator arms was used.IntroductionMining machinery that lacks automatic control has been found to show a high degree of variation in work output and performance quality when operated by different personnel. Differences in operator attitude, judgment, and skill are reflected directly by production statistics. The addition of automated control has the potential for considerable improvement in machine life and performance. Even with a more acceptable mine environment and much safer conditions than ever before, situations still exist where it is preferable to remove personnel for reasons of safety as well as productivity. Typical advantages of such situations are automated skip loading and hoisting, and the use of remote control load-haul-dump units exposed to open stopes.Other cases arise where heavy work is required under conditions where lighting is poor, floors are slippery, noise levels are high and dust and oil mist exist in the atmosphere. I.T.H. drilling is carried out under such conditions and is one operation where automation can easily be justified."

Jan 1, 1987

By M. Kumaran, A. Vetriselvan, A. Purantharan

"This paper presents a case history of evaluating the stability of a distressed earth bund and rectification measures carried out. A 5.45 km long, 7m high earth bund for drinking water storage was constructed in Andhra Pradesh. During construction of the bund following were observed – (a) a longitudinal crack at the downstream side (b) Bund on the downstream side along the crack settled to a max of 700 mm and (c) downstream rock toe level area raised by heave up to 175 mm. Investigation of the events made important contributions to the fundamental understanding of the behaviour of large earthworks of this type. It was found that the variation in subsoil strata was not addressed during the execution.After careful evaluation, stone columns were recommended as a suitable ground improvement technique. Stone columns were used as a reinforcement to improve the shearing resistance of foundation and in turn ensure stability. By using and applying advanced geotechnical engineering analysis tools and modelling techniques, earth bund and its foundation was analysed and examined against failure by slope instability. Stone column design was carried out using in-house computer program GEOSTONECOL and stability of earth bund was analysed using TALREN software. Earth bund construction was completed after ground improvement and is performing satisfactorily.INTRODUCTIONIn order to supply water during summer season, Government of Andhra Pradesh decided to construct a 7m high and 5.45km long earth bund summer storage tank. It was one of the largest earth bund summer storage tanks in whole of South India at the time of its construction. During construction, the earth bund has undergone sudden distresses. Investigation of the series of events occurred during construction has made important contributions to the fundamental understanding of the behaviour of large earthworks of this type. This paper presents the reasons for earth bund failure, slope stability assessment of the distressed earth bund and recommendation of stone column as a suitable ground improvement remediation technique.DESCRIPTION OF STUDY SITEThe characteristics of the original construction are briefly described as follows. A shallow cut-off trench was excavated below existing ground level at the centreline of bund as shown in Fig. 1. Below the base of the trench a cut-off grout curtain was installed. Upstream and downstream shell earth filling was carried out using Clayey Sand ‘SC’ type soil. At some locations, bottom of cut-off trench has reached as deep as 12m from the existing ground level."

Jan 1, 2017

By Hans Treichl

1. INTRODUCTION For Europe the Arlberg road tunnel signifies the elimination of the largest traffic barrier between Bucharest and Paris in the east-west transversal. Apart from that the tunnel will serve the feeder system to the two north-south links Ulm - Milano, and the Brenner motorway, and links the Inntal and the Rheintal motorways closer together.. Thus, the supraregional road system carrying traffic through the Tyrol and Vorarlberg will considerably be emproved by the Arlberg road tunnel. 2. THE PROJECT The 16.1 km contract section of expressway S 16 includes a ramp section of approximately 2.6 km, the access points at St.Anton and at Langen, and the main 13.98 km section of the road tunnel. This section cuts the link between St.Anton and Langen by 3.7 km, and saves 475 m in altitude. The Arlberg road tunnel is planned to have two tubes with two lanes each. In the first stage the southern tube was under construction. Its traffic capacity is 1,800 car units per hour. The tunnel has a cross section of 9o to 103 m2. The sloping gradients are by 1.3o and 1.67 per cent. Fresh air is supplied and used air removed through a ventilation system, fed at the portals and through two vertical ventilation shafts. One of them, at Maienwasen, is 222 m deep, its cross section 66.5 m2. The diameter in clear is 8.32 m. The vertical shaft Albona is 736 m deep, the diameter in clear is 7.37 m. The tunnels is 9,4o m wide, providing for a 7.5o m roadway plus o.95 m sidewalks on each side of it. 4.7o m above the traffic area the conduits for fresh and used air. A transverse ventilation system with reduced exhaust air has

Jan 1, 1979

By J. F. Burr, D. P. Snyder, G. W. Luxbacher

"The Mine Improvement and New Emergency Response Act (MINER Act) of 2006 (PL 109-236, 2006) established the Office of Mine Safety and Health, functioning as the Office of Mine Safety and Health Research (OMSHR) within the National Institute for Occupational Safety and Health (NIOSH) and provided authority for awarding contracts related to the development and implementation of new mine technology and equipment. The OMSHR external contracts program was formed in accordance with the MINER Act and has since issued more than 150 contracts focused on worker health and safety. Initial funding for this program was provided by the United States Congress through two emergency supplemental appropriations and was focused on emergency oxygen supply, communications and tracking, and refuge chambers (also referred to as refuge alternatives). Since the MINER Act, Congress has continued to fund the program through the annual NIOSH mining appropriation. The program was supplemented starting in 2009 with an academic capacity building program directed toward developing university tenure-track faculty and facilities and supporting graduate students in the area of mine ventilation. Ground control was added as an additional focus area in 2011. A short synopsis of each contract is published on the NIOSH Mining website (www.cdc.gov/niosh/ mining/researchprogram/contracts/index.html) and final reports are available in digital form on request. A summary of the progress OMSHR has made over the 10-year period since the Act was published previously (Snyder et al., 2016).External contracts are broadly classified by the following areas:• Communications and tracking.• Emergency response.o Self-escape and breathing air supply.o Refuge alternatives.o Escape and rescue.• Equipment safety.• Fires and explosions.• Ground control.• Mine environmental systems (mine ventilation and atmospheric monitoring).• Worker/workplace health and safety.Contracts are issued under a request for proposal (RFP), through a broad agency announcement (BAA) or under an interagency agreement (IAA). An RFP solicitation includes a specific problem description and a well-defined scope of work to guide the offeror in preparing a bid to conduct the research. Under the BAA several problem areas are described and the offeror develops the scope of work and deliverables for the proposed research. An IAA is very similar to an RFP except it is a contract between two federal government agencies."

Jan 10, 2018

By MAHESH SHRIWAS, CHRISTOPHER PRITCHARD

Ventilation monitoring and control in mines are becoming an integral part of day-to-day activity for maintaining health and safety of miners. The authors evaluate potential real-time monitoring solutions for detecting and reducing diesel particulatematter, mine fires, and dust in situ, and examined the state-of-the-art use of ventilation monitoring and control in underground mines for detecting and reducing air contaminants to acceptable regulatory limit. Authors review relevant documents, including research papers, trade publications, and manufacturers’ website-based information, to identify research gaps. The authors also evaluate contemporary sensors (airflow, gas, dust, silica), control system and software technologies, data transport systems, Industrial Internet of Things, ventilation network simulators, and control devices to identify potential health and safety research gaps. In this study, examples of some mines from Canada, Australia, and the USA are included where ventilation monitoring and controls have been applied. Overall, this review identifies multiple challenges and research gaps in applying mine monitoring and control systems that could be the focus of future research, offering potential improvements to miner safety and health and financial benefits.

May 12, 2020

By AIME AIME

QUALITY and size do not ordinarily go hand in hand, but there is good evidence that both these attributes reached a new peak at the Annual Meeting of the Institute in New York just concluded. Certainly, the total attendance of 2500 was far above any yet attained, as might be expected with the recent rapid growth of Institute member- ship. General comment indicates that the quality of the papers also was notable, though not measurable by so definite a yardstick as attendance. During the meeting 49 technical sessions were held, at which more than 250 formal papers were presented. In addition, there were some thirty special meetings of committees, Divisions, and other Institute groups. In reporting the Annual Meeting eleven years ago the statement was made that "unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger," and "the fifth floor, where a buffet lunch is served each day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size." Unfortunately the angel to succeed Andrew Carnegie, who financed the building of the present home of the Institute 35 years ago, has not yet ' appeared. Even if some one would merely build another elevator or two in the present building it would help. Fortunately, the modern auditorium of the American Radiator & Standard

Jan 1, 1940

The ready solubility of gold in dilute aqueous solutions of the cyanides of the alkalies or alkaline earths provides a convenient method for the separation of the precious metal -from the large surplus of associated materia1. The finely ground ore is pulped with a weak solution of cyanide, agitated to dissolve the gold, filtered and washed. The lowgrade filtrate is then clarified and the gold precipitated by some electronegative agent, the most usual being finely divided zinc or zinc dust. The slight precipitate is collectedon some form of filter coated with a filter aid, the filter cake being then known as "gold slime".A typical analysis of this slime is given in Table 1.

Jan 1, 1956

By Erdal Ünal

The computer program introduced in this paper is based on design guidelines developed for selection of support systems used in mine roadways. The support types considered include rock bolts as well as rigid and yieldable steel arches. Using the computer program, the design engineer can select the type, pattern and specifications of the support systems suitable for various roof conditions. The concepts utilized, assumptions made, support selection criteria and description of the computer program, developed for the PC, are included.

Jan 1, 1989

By L. O’Connor, E. Tarshizi

The objective of this work is to provide a detailed review and a list of references in chronological order, comprising 80 recent technical papers, on the use of discrete-event simulation (DES) modeling in mining engineering. In this article, the review papers of published mine simulation projects through 2007 are summarized, and then a comprehensive review of individual articles published from 2008 to 2015 is presented. This survey work also includes analyses of the simulation tools used in the published projects, mining types and applications in order to assess these key features and evaluate the recent state of research in mine DES simulation. In addition, an interactive map visualization for the locations of the simulated projects is made available on a website to benefit current and prospective scholars in the field. The results of this investigation revealed that the most common application of DES in mining had been mining equipment selection and analysis, while ore processing and risk management projects were less frequently reported. The results also showed that modeling surface mines were in the majority, but the trend of publications for underground mine simulations had also increased. According to the results, ARENA was the most popular simulation software package, but several simulation tools that were only used once or twice in the mining projects are also included in this review.

Jan 1, 2018

By L. O’Connor, E. Tarshizi

The objective of this work is to provide a detailed review and a list of references in chronological order, comprising 80 recent technical papers, on the use of discrete-event simulation (DES) modeling in mining engineering. In this article, the review papers of published mine simulation projects through 2007 are summarized, and then a comprehensive review of individual articles published from 2008 to 2015 is presented. This survey work also includes analyses of the simulation tools used in the published projects, mining types and applications in order to assess these key features and evaluate the recent state of research in mine DES simulation. In addition, an interactive map visualization for the locations of the simulated projects is made available on a website to benefit current and prospective scholars in the field. The results of this investigation revealed that the most common application of DES in mining had been mining equipment selection and analysis, while ore processing and risk management projects were less frequently reported. The results also showed that modeling surface mines were in the majority, but the trend of publications for underground mine simulations had also increased. According to the results, ARENA was the most popular simulation software package, but several simulation tools that were only used once or twice in the mining projects are also included in this review.

Jan 1, 2017

By D. C. Lynch

While a sizable amount of data exist as to the activity and distribution of minor elements between matte and metal, there has been no unifying theory presented delineating the form of dissolution of these elements in molten sulfides. In order to alleviate that deficiency the literature concerning the behavior of As, Sb, Bi and Pb in mattes is reviewed. Models present in the literature, regarding the thermochemical behavior of minor elements, are tested, and new models are presented and evaluated using thermodynamic theory. The results of those analyses are used to predict optimum conditions for the volatilization of minor elements. The dearth of data on the behavior of minor elements in nickel mattes requires that this review focus on copper- iron mattes. An effort is made, however, to utilize basic knowledge regarding nickel sulfides and the interaction of nickel with the minor elements to predict the behavior of those elements in nickel-copper and nickel-iron mattes.

Jan 1, 1993

By C. E. Armantrout, H. Kato, M. I. Copeland, M. Krug

The investigation of the nickel - gadolinium phase diagram was undertaken to determine the alloying behavior of these two metals . The data from meltingpoint determinations , thermal analyses , metallographic examinations , and X- ray diffraction analyses revealed a phase diagram with three eutectic points and seven intermetallic compounds . Very limited solubility of the phases in each other was observed . The five phases , Ni Gd , Ni , Gd , Ni Gd , Ni, Gd , and NiGd¸ , melted incongruently at about 1,300 ° , 1,270 ° , 1,180 ° , 1,070 ° , and 775 ° C , respectively . Ni Gd and NiGd melted congruently at approximately 1,550 ° and 980 ° C , respectively . Four of the compounds were determined to crystallize in the hexagonal system : Ni Gd , Ni Gd , Ni , Gd , and Ni Gd . Ni Gd was determined to be cubic and NiGd , orthorhombic . The crystal system of NiGd was not determined . The eutectic points occurred at 13 , 67 , and 85 wt pct gadolinium , and the isotherms at 1,290 ° , 890 ° , and 700 ° C , respectively .

Jan 1, 1964

By R. L. Bruening, N. E. Izatt, S. R. Izatt

"Rare earth elements (REE) are essential and unique components of many high-technology products without which functioning of modern society would be greatly impaired. Commercial deposits of REE are limited to a few geographical locations. Largely untapped sources of REE are available in endof- life (EOL) magnets, rechargeable batteries, and electronics. Presently, < 1% of REE in EOL wastes is recycled. Conversion of EOL wastes to liquid streams allows use of IBC’s Molecular Recognition Technology (MRT) process to selectively recover, separate, and purify target REE and associated metals at g/L to mg/L or lower concentration levels. The MRT process together with its applications to separations of REE and associated metals in recycling as well as in mining are described. Economic and environmental advantages of MRT are presented. INTRODUCTIONRare earth elements (REE) include the lanthanide series (La-Lu), Y, and Sc. These elements are not rare, but concentrated minable deposits are scarce (Cordier 2012; Haxel, Hedrick, & Orris, 2002). Over 95 % of the world’s supply of REE is controlled by China (Hanson, 2011a) where they are mined, processed, and the pure elements incorporated into a growing number of consumer and military products. The consumer products are marketed worldwide. Since REE are vitally important in consumer and military products, this situation has caused other nations to scramble to develop the capability to produce their own supply (Cordier, 2012).In the U. S., Molycorp has reopened the Mountain Pass REE mine in California and production has begun (Goldenberg, 2010). Development of a reliable internal source of REE is of high national priority in the U.S. (Hanson, 2011b; Hess, 2012: “Obama Announces”, 2012). These elements have in recent decades been incorporated into new consumer and military products that are essential to our economy and defense. These products range from wind turbines, high performance magnets, hybrid car rechargeable batteries, energy efficient lighting electronics, flat screen televisions, and smart phones to advanced weapons systems (Haxel et al., 2002; Levkowitz & Beauchamp-Mustafaga, 2010)."

Jan 1, 2012

This field guide is designed for use in planning pollution control and reclamation activities on small sand and gravel operations. Its purpose is to assist operators in selecting environmentally desirable pollution control and reclamation procedures based upon their particular mining situation. The guide includes information on interpreting physical and cultural factors that must be considered in planning and implementing a mining and reclamation program, achieving environmental protection objectives, and improving community/industry cooperation. Included as appendices are a summary of state laws and a list of additional readings on the subject.

Jan 1, 1981

By Dean, R. S.

THE numerous theories of hardening which have been advanced in recent years are all satisfactory in accounting for some of the phenomena observed in hardening metals, but none so far presented account for all of the facts observed. Some years ago one of the authors, R. S. Dean,&apos; presented a theory to account for some of the properties accompanying work hardening. The present paper develops this theory further in the light of recent experimental work and extends it to other forms of hardening. Many of the ideas included have come from the writings and personally communicated thoughts of others. We have attempted to give proper credit in every case, but it is possible that we have not always done so. As an historical basis it is desirable here to review very briefly the hardening theories which have been current. The first comprehensive theory of work-hardening phenomena was due to Sir George Beilby.2 He contributed the idea that with cold work part of the structure of the metal was rendered amorphous and that-it was to this amorphous material that the cold-worked metal owed its difference in properties. According to Beilby&apos;s theory this amorphous material was a supercooled liquid and, therefore, had the characteristics of a vitreous material. That such a theory is not capable of explaining the property changes in metals has been repeatedly pointed out. This theory also allowed a slip to take place only once on a given plane, which, as has been pointed out by Jeffries and Archer13 is not consistent with the observed length of an, individual slip and the amount of elongation which can be obtained by wire drawing. The modifications, which have been proposed to this hypothesis to make it coincide with the experimental facts, have to a considerable extent robbed the theory of its clean-cut characteristics. The commonest of these modifications replaces the amorphous phase with an

Jan 1, 1927