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By Mike Harrington, Tung Vu

The Regional Connector Transit Project is a 1.9-mile-long underground light rail system that will connect LA Metro’s A (Blue), E (Expo), and L (Gold) Lines in downtown Los Angeles. This $1.75-billion design-build project is scheduled for revenue service in Spring 2023. The project consists of 21-foot diameter twin-bored tunnels, a 300-footlong crossover SEM cavern, three new underground stations (at 1st Street/Central Avenue, 2nd Street/ Broadway Avenue, and 2nd/Hope Streets), and cut-and-cover tunnels along South Flower, Alameda, and 1st Streets. This paper, which is the continuation of our previous paper presented in RETC 2019—LA Metro Regional Connector Transit Project: Successful Halfway-Through Completion, will provide insight regarding the construction of major components, and the system integration and testing work undertaken for this complex transit project.

Jun 13, 2023

By Perry M. Jones

An important operational and environ-mental concern associated with in situ leaching activity is the balance between solution injection and recovery. Solution balance is an important indicator of the capability of a particular in situ hydrologic design to efficiently and effectively control and distribute leach solution within the target ore zone. The Bureau of Mines is investigating the factors that affect solution balance in an unsaturated ore deposit, as part of ongoing in situ leaching hydrologic investigations at the Cyprus Casa Grande Mine. Flow conditions in 58 injection and recovery wells at the Casa Grande In Situ Leaching Test Facility were monitored daily over an 18 month period. Changes in the balance between injection and recovery occurring during this period were evaluated using analytical and statistical methods. The results permit estimation of solution distribution and the volume of solution stored in microfractures and interstitial pore spaces within the deposit following 18 months of leaching. Approximately half of the difference between well injection and well recovery can be accounted for by solution movement through macrofractures into nearby drifts. Estimates of solution storage within the ore deposit at the end of 18 months of leaching range from 3.5 to 6.9 pet. of injected solution. These results also suggest that 13 to 26 pet. of the fracture/interstitial pore space in the deposit was saturated with solution after 18 months of leaching.

Jan 1, 1991

By Randall Morris

After years of steadily declining employment and production, the U.S. coal industry is having a moment. In 2016, when Donald Trump was running for U.S. President, he cast a spotlight on coal mining in his campaign speeches, promising to end the “War on Coal.” Fast forward to 2025. On the first day of his second term, President Trump signed the National Energy Emergency Act, which emphasizes domestic energy production as a matter of national security and focuses on incentivizing domestic energy resources. Then on April 8, President Trump issued an executive order opening federal land to coal mining to reinvigorate “America’s beautiful clean coal industry.” As the nation seeks to identify reliable solutions to meet its ever-growing energy needs, the administration is going all in on proven, reliable and readily available natural resources, including coal. This means the coal industry is positioned to play a pivotal role in the administration’s stated energy policy, and highwall mining could be an integral factor in helping the industry optimize the extraction of ore to make the most of this moment. The White House noted in a statement that the United States’ “abundance of energy and natural resources … have historically powered our Nation’s economic prosperity” and vowed to remove regulations that have hindered developing these resources — regulations that resulted in job reductions and higher energy costs for U.S. consumers, while weakening national security. “There has been an increase in electricity prices in the United States of over 30 percent in the past four years,” said Rich Nolan, president and chief executive officer of the National Mining Association (NMA). “This administration wants to focus on that, inflation and on increasing electricity availability to help lower the price over time by incentivizing energy policy. Coal is definitely a high priority for this administration.” Part of the White House’s strategy is to facilitate investment in coal-fired plants. The shift comes at a time when the reliance of coal-powered energy plants has been waning. According to the U.S. Energy Information Administration, 7.5 GW of electrical capacity from coal-fired plants was retired in 2024, following the retirement of 22.3 GW of electric generating power the two years prior.

Jun 1, 2025

By Tuncel M. Yegulalp

This article summarizes some of the results of the continuing research activity at the Henry Krumb School of Mines, Columbia University, directed towards a better understanding of the stochastic behavior of slurry flows in underground coal-slurry pipeline systems. The slurry system under consideration here replaces all conventional haulage systems between the coal face and the coal preparation plant on the surface. At the beginning of the pipeline system, flow rate and frequency of coal slurry is very closely related to the activities of production equipment at the coal face. Due to several scheduled and unscheduled interruptions in continuous miner's coal mining activity, resulting slurry flows possess stochastic characteristics. Proper understanding of these characteristics is believed to lead to a more realissic and economic design of slurry handling equipment. Fundamental ideas supported by field observations are presented and a Semi-Markov model of the slurry flows is developed. As a result of this formulation, behavior of combined slurry flows from N independent coal faces can be expressed in analytical form. The contents of a slurry surge tank receiving slurry flows with certain stochastic characteristics is investigated as a function of discharge pump characteristics and time.

Jan 1, 1981

By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By Ray A. Rothrock

The in situ mining of uranium is the process whereby chemical lixiviant is injected by means of wells into, and flowed through, an ore body. The lixiviant reacts with uranium which has been previously oxidized making the uranium soluble. The solution is then brought to the surface by means of producing wells. In situ mining disturbs the ground-water quality in the immediate area. Since ground water is a natural resource used by man, care must be taken not to allow the lixiviant to escape the local mining area. Also, when the ore body is mined out, the area should be restored to as near its original state as is reasonably achievable. The return of ground-water quality to its original state can occur naturally over a long period of time or be enhanced using appropriate technological means.

Jan 1, 1981

The mining industry is an important economical factor in Vietnam. Mining is presently being conducted at about 60 locations and at over 1000 mines. Petroleum extraction and coal mining are the most important parts of industry though metals such as zinc, tin, chromites, iron are also extracted. Last year the sector produced 20 million tons of crude oil, 26 million tons of coal and 500,000 tons of apatite. In particular, Vietnam is one of the world?s largest producers of anthracite, and it is one of the top producers of ilmenite and zircon in the Asia-Pacific region. The government intends to increase the mining production on all levels, however, at present one can observe adverse impacts of the mining activities on the natural environment such as insufficient waste dump rehabilitation, occurrence of acid mine drainage, mining subsidence and emissions as well as lack of appropriate water treatment facilities. This paper describes the current mining situation, future perspectives, the major environmental challenges of the country and approaches to solve these problems. Particular emphasis will be given to the research project ?RAME ? Research Association on Mining and Environment in Vietnam?, a venture carried out by universities, research centres and industry. This project is worked out in collaboration with the national Vietnamese coal and industrial minerals company VINACOMIN.

Jan 1, 2006

By Raj K. Singhal

Canada is a world class producer and exporter of minerals and mineral products. Canadian open-pit mines are highly mechanized and use state-of-the-art equipment and support technology. During the past few years, productivity improvements at Canadian open-pit mines have been achieved by taking advantage of larger equipment, in-pit crushing and conveying, truck dispatch systems and electronic management tools. The most recent developments are related to hydraulic transportation and the application of global positioning systems (GPS). Mine planning has become computerized. Environmental issues are dealt with in all phases of planning. Equipment modifications are pursued with vigor to keep the equipment functioning in the hostile Canadian north. In 1997, the mining and mineral processing sector employed 370,000 Canadians, contributing $26.2 billion to Canada's gross domestic product (GDP). The value of production of the Canadian mineral industry, including coal, amounted to $19.1 billion in 1997. Gold remained Canada's leading mineral with production valued at $2.8 billion. This was followed by copper ($2 billion), coal ($1.9 billion), zinc ($1.6 billion) and nickel ($1.9 billion). [ ] Synthetic crude oil from oil-sands mining operations in Alberta represents an important part of Canada's petroleum production. In 1997, the value of synthetic oil production was $2.87 billion. Canadian oil-sands mining has contributed significant technology developments in Canada.

Jan 1, 1999

By Furuyama Takashi, Mori Sukeyuki, Hara Tsuyoshi, Fukushima Yujin

In mineral processing practice, flocculation is largely established as an engineering technique of waste water treatment and the study of parameters increasing the settling velocity of particles is still of great importance to improve the process. Further investigations were made using quartz (Q89) and fluorite samples (F91) which included 58.8% and 65.8% of -2.3 µm particles respectively. In all the experiments the flocculation phenomena were observed varying the pH value of the aqueous suspension. In contrast to quartz particles (Q89) which did not flocculate for all pH values, it was, noticed that fluorite particles (F91) flocculated in the alkaline range of pH over 11. With an aqueous suspension containing equal quantities of Q89 and F91, a hetero-flocculation of particles was observed at a range of pH below 10. In this case, the maximum floc size of the hetero-flocculation was 37.0-26.2 µm This size was about three times larger than when quartz (Q84) and fluorite particles (F85) were used with 32.4% and 40.4% of -2.31 µm particles respectively. Besides, in the experiments using Q89 and F91, the maximum size of hetero-flocculated single particles was found to be 6.54 µm instead of 3.27 µm as obtained with Q84 and F85.

Jan 1, 1995

By L. J. Hoover

The objective of this study was to assess the health and environmental impacts of fluidized-bed combustion (FBC) of coal, specifically as applied to baseload generation of electrical energy by utilities. The study* was a short-term effort that based its analyses on information derived from the experience of the group or quickly obtained from the literature. The approach was to compare Atmospheric Fluidized-Bed Combustion (AFBC) and Pressurized Fluidized-Bed Combustion (PFBC) with two current technologies: low-sulfur coal combustion (LSC) and flue gas desulfurization (FGD) used with high-sulfur coals. A wet-limestone process was selected as the FGD technology. The impacts compared involved not only health and environment but also sociology, resource use, and dollar cost. Conditions for comparison were centered around a nominal date of 1988, when initial operation of commercial AFBC plants may occur. The PFBC has a later introductory date, a nominal 1995 (its impacts relative to other competitive technologies now in the R&D stages were not compared.)

Jan 1, 1978

By VÍCTOR VÁZQUEZ-VÁZQUEZ, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, JESÚS L. VALENZUELA-GARCÍA, OFELIA HERNÁNDEZ-NEGRETE

The present study examined a process for precious metal recovery (silver and gold) from difficult minerals which exhibit refractory characteristics to cyanidation and ammonium thiosulfate leaching (low extraction and high consumption of leaching agent). It is well known that mangano-argentiferous minerals are mainly composed of manganese, silver, gold, and iron. In this research, a mineral sample from Monte del Favor mine, located in Hostotipaquillo, Jalisco, Mexico, was physically and chemically characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fire assay, and atomic absorption spectroscopy (AAS). Two-stage leaching was carried out: first to eliminate manganese from the sample using sodium sulfite (Na2SO3) as a reductive reagent and sulfuric acid (H2SO4) and a second stage to dissolve silver and gold with sodium hypochlorite (NaClO) and hydrochloric acid (HCl); the results show extraction around 96% for Mn and 98.73% and 83%of Ag and Au, respectively. The usefulness of high acidity and Na2SO3 to obtain good results in Mn and Ag leaching is discussed along with the roles that HCl and NaClO play in the dissolution of Ag and Au values.

Apr 15, 2020

By L. H. Michaud

An existing mining company plans to extend their surface coal mining operations in central Pennsylvania. Although the proposed site contains pyritic material, the results of the acid-base accounting for the site show an overall NP:MPA ratio of 4.26:1 for the entire site. The pyritic material is, however, associated with the lower of the three seams to? be mined. If traditional dragline mining methods were used, this would result in the acidic material being placed at the top of the spoil piles, exposing it to air and water, and therefore to the formation of Acid Mine Drainage (AMD). Further concerns are associated with the fact that the alkaline material is not distributed evenly over the mine site. In order to prevent the formation of AMD, the company has proposed to mine the area using Truck/Shovel mining methods. This technique offers a more flexible alternative for cut sequencing and for the selective placement of waste material. Working with the Department of Mineral Engineering at The Pennsylvania State University, a mine plan was developed for this site. This plan results in the layering of the alkaline and acidic spoil in order to achieve an overall net alkalinity in all spoil areas. Mining of this site should therefore not result in the formation of AMD.

Jan 1, 1994

By Jamal Rostami, Omid Frough, Wei Hu

Characterizing the abrasiveness of soil/rock and the allowable wear of hard-facing products in various conditions is a critical factor in selection of the best material for certain applications related to drilling and excavation in mining and construction industries. The Soil Abrasion Index test machine at Colorado School of Mines (CSM) is one of the recently developed unique systems capable of testing soil/crushed rock abrasion under various conditions, such as dry, wet, and saturated settings. It is also capable of testing the performance of various types of hard-facing materials in a given geo-material. This paper studies the wear properties of different hard-facing materials in various crushed rocks from a surface mining operation in the iron range region of the USA. The hard-facing materials include regular and hardened steels and six different specialized hard facings, based on chromium carbide. The soil/rock include a standard sand and two rock samples from the surface mine. Fourteen abrasion tests were conducted, where the weight loss of each hard-facing material was measured over timespans up to 1 h of testing. The results show the distinct performance differences between the steels with 17 HRC and 43 HRC hardness and the hard-facing products for this application. The results show the possibility to evaluate the abrasiveness of different rocks at a mine or construction site and the performance of various hard facings in similar working conditions. This is a practical solution for selection of the cutting tool or reinforcement of bucket lips and truck beds for comparison of relative wear life between different wear-resistant materials.

By Carl G. Consalus

The Kemmerer Coal Company's Sorensen Mine is located approximately 7 miles Southwest of the Town of Kemmerer, Lincoln County, Wyoming. The coal it produces is delivered via conveyor directly to Utah Power and Light's Naughton Steam Generating Plant. The Plant went on the line in the spring of 1963 and the Sorensen Mine has been producing coal since February of that year. In this period, approximately 2, 000, 000 tons of coal have been delivered to the Plant. Present Sorensen mining operations are being carried out in the upper seams of the Adaville Formation. The formation contains, in some places, up to 30 coal seams of varying quality and thickness. Thirteen seams are considered major and are given numbers; the rest are considered splits off of the major seams and are so named. The lowest seam stratigraphically is the No. 1, or Elkol seam. So far, it has not been committed to power production but is being held in- reserve. It is the thickest seam with 80-90 feet of coal as its average thickness. The other major seams vary from 10-50 feet thick, with most of the seams averaging 17-26 feet of thickness. Each major seam has been opened at least once' to obtain a true gross sample of the coal's performance in the Plant.

Jan 1, 1967

By P. D. Chamberlin

The interface between precious metal miners and gold refiners has been an uneasy interface over the years. The reasons for this interface and its apparent uneasiness and lack of trust include technical factors, economies of scale, and cultural differences. Technical factors take two forms. First, concentrates, precipitates and sponge produced at the mine site are notoriously difficult to sample and a non-representative sample can be the cause of misunderstanding and distrust. Dore, however, is homogeneous and can be correctly sampled and analyzed. Second, the technology and chemistry of fine gold and silver production is complex and quite different from that of dore production. Most mining companies are content not to be involved with additional processing steps.

Jan 1, 1986

By Jamal Rostami, Omid Frough, Wei Hu

Characterizing the abrasiveness of soil/rock and the allowable wear of hard-facing products in various conditions is a critical factor in selection of the best material for certain applications related to drilling and excavation in mining and construction industries. The Soil Abrasion Index test machine at Colorado School of Mines (CSM) is one of the recently developed unique systems capable of testing soil/crushed rock abrasion under various conditions, such as dry, wet, and saturated settings. It is also capable of testing the performance of various types of hard-facing materials in a given geo-material. This paper studies the wear properties of different hard-facing materials in various crushed rocks from a surface mining operation in the iron range region of the USA. The hard-facing materials include regular and hardened steels and six different specialized hard facings, based on chromium carbide. The soil/rock include a standard sand and two rock samples from the surface mine. Fourteen abrasion tests were conducted, where the weight loss of each hard-facing material was measured over timespans up to 1 h of testing. The results show the distinct performance differences between the steels with 17 HRC and 43 HRC hardness and the hard-facing products for this application. The results show the possibility to evaluate the abrasiveness of different rocks at a mine or construction site and the performance of various hard facings in similar working conditions. This is a practical solution for selection of the cutting tool or reinforcement of bucket lips and truck beds for comparison of relative wear life between different wear-resistant materials.

By Tyler Luxner

Stillwater Mining Co. (SMC) is the largest primary producer of platinum and palladium in North America. SMC operates two underground mines in south central Montana, along the 45-km (28-mile) platinum/palladium J-M Reef in the Stillwater Complex. The Stillwater Mine exploits 9.6 km (6 miles) of deposit strike length and East Boulder Mine exploits 4 km (2.5 miles) of deposit length. The two mines are 20.4 km (12.7 miles) apart with SMC controlling a considerable length along the entire J-M Reef trace. Production at the Stillwater Mine began in 1986 and in 1988 the first tunnel boring machine (TBM) was commissioned, becoming an integral part of mine development at SMC. TBMs have been used for developing production footwall laterals (FWL) to access new mining blocks at the Stillwater Mine, as well as boring twin crosscut ac-cess tunnels at the East Boulder. Two TBM development expansion projects are currently in progress: the Graham Creek project at the East Boulder Mine, which will extend footwall lateral development 2,591 m (8,500 ft) to the west, and the Blitz project, where a TBM will be commissioned to extend east out of the Stillwater Mine to 3,658 m (12,000 ft) beyond the current production mining front. General strike and dip of the Reef is west to east and to the north, respectively.

Jan 1, 2012

By M. Rancourt, J. Levay, D. K. Murphy

INTRODUCTION The LG-2 project is one element of the La Grande Complex, an integrated development of hydro-electric potential being constructed in north-western Quebec by the James Bay Energy Corporation. The project is located on the La Grande River about 65 miles east of Fort George on the James Bay coast and 600 miles north of Montreal. It comprises a 525 foot high dam, 81,000 feet of dykes, spillway and river diversion works and a 16 unit underground powerhouse that will have an installed capacity of 5,328 MW. The power installations at LG-2 represent approximately half of the total potential for the complex. When completed in 1982, LG-2 will rank as the largest underground powerhouse in the world. Studies and site explorations for the project were begun in 1971, construction commenced in 1973 and the roll date for the first machine is scheduled for February, 1980. GENERAL ARRANGEMENT OF POWER INSTALLATIONS As shown in Figure 1, the power installations are located on the south bank of the river about 4 miles downstream from the main dam. The general arrangement of the complex is presented in Figures 2 and 3. The intake structure consists of 2 groups of 8 gated intakes separated by a central service area. Sixteen 26 foot diameter in-

Jan 1, 1976

By Feng Liu

"With seven new applications for plans of work for exploration in the international Seabed Area approved by the Council during its twentieth session of the International Seabed Authority, 26 total approvals have been made by the Council up to date. Among them, three contracts were made with COMRA. On 8 August 2014, China Minmetals Corporation submitted another application to the Authority for approval of a plan of work for exploration for polymetallic nodules in the Area, which is also sponsored by the Government of the People’s Republic of China.China is one of the main contributors to the international seabed regime. The Presentation will describe China’s activities in the Area, such as exploration, technology development, environmental protection and policy making.JIAOLONG is a submersible with capacity of 7000 meters. JIAOLONG’s sea trials were carefully made in 4 years, from 2009 through 2012 and it successfully dove to a depth of 7062m in June 2012 at Mariana trench. A so called "Test Application Phase" started thereafter, and is planned to last for 3-4 years. Two cruises and 4 legs have already been made since then. A wide-range of findings were obtained during dives in South China Sea, and in COMRA’s Exploration Contract Areas for polymetallic nodules and cobalt-rich ferromanganese crusts. This presentation will reveal the colorful findings."

Sep 1, 2014

By David N. Hedges

This paper discusses the actual recovery and installation of a longwall in a bituminous coal mine in Western Pennsylvania. The coal bed mined is in the Lower Freeport seam which averages 42 inches (1.07m) in height locally. Drainage from the mine is approximately 3.5 million gallons of water per day (13.25 million liters per day). This water deteriorates the mines predominately fire clay bottom making it extremely difficult to move equipment. Support removal is accomplished by pulling the 6 ton (5443 kg) shields out under their own hydraulic power and transporting them by track over four miles (6437m) co the next longwall panel. This paper also discusses the changes that will be made to aid in the succeeding longwall recoveries and installations.

Jan 1, 1984