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By Todd Kilduff, James Grillo, Shrey Arora

In efforts to improve ingress/egress from the existing subway platforms in PATH’s Exchange Place Station, a new 18-foot horseshoe cross-passage tunnel was constructed by Walsh Construction who retained Kilduff Underground Engineering for design of the initial support system and to install and maintain geotechnical instrumentation. The project presented some unique challenges as a result of the proximity to pedestrians on the platform. PATH service remained uninterrupted, limiting the Contractor to mechanical means of excavation to advance the heading. The logistics proved very challenging for the approximate 100-foot-long tunnel excavated in soft Manhattan Schist. This paper will present the design and construction challenges for the project.

Dec 1, 2022

Explosives are used to mine coal. Any blast results in three size categories of products, namely over-, middle-, and under-size. Boulders can still be broken smaller in further operations after blasting. The under-size, for instance coal fines, negatively affects the mining efficiency. Their reduction ensures better returns. The paper concerns investigations aimed at reducing coal fines' generation. Inherent fractures are identified as one of source of fines. The discussion is therefore centered on establishing a relationship between the fracture occurrence, the explosive properties and the blast outputs evaluated in terms of the fines generated.

Jan 1, 1996

By Richard Keith Corbin

INTRODUCTION The purpose of this paper is to assist explorationists and entrepreneurs in deciding whether to invest in gold mining concessions in lesser developed countries (LDCs) and, if so, in deciding which LDCs provide the best opportunity. The first decision is difficult in the face of common notions that foreigners are not welcome - only their money; that the best gold deposits were worked out long ago; that even if you survive the mal- aria, and in spite of 51% control by a national partner, you manage to profit from a new discovery, they will tax your operation to death, or worse yet, nationalize it. Close scrutiny of what happened to foreign investors in LDCs during the “Mexicanizationt” of the 1930's through the "Zambianization" of the 1970's shows that many of these concerns are well-founded historically. But the trend of knowledgeable writers over the past decade seems to be away from this gloomy foreboding, and towards a cautious optimism, based on recently perceptible metamorphoses in certain LDCs' conditions and attitudes. If the explorationist or entrepreneur decides to seize on this apparent opportunity, the second decision -- which of these certain LDCs to invest in -- is doubly difficult, because of the formidable tasks of coming up with a rating system to provide rational comparison, and then gathering enough current, reliable information to apply. To assist in these tasks, a suggested rating system and case studies, respectively, follow a brief review of recent writings on the subject

Jan 1, 1987

By Dominick Mandalari, David Mast, Heather Ullinger, Juan Granja, Amanda Foote

The City of Akron will construct the Northside Interceptor Tunnel project, a U.S. EPA/ DOJ CSO Long Term Control Plan Project. The system will provide at least 10.3 million gallons of storage in a 16.5-foot finished ID and 6,660-foot-long rock tunnel. The system will reduce both overflow volume and number of overflow structures on the Cuyahoga River. The project includes deep drop shafts and more than 3,000 linear feet of 48 to 96-inch I.D. sewers installed by trenchless construction methods. This paper will discuss the project background, ground conditions, and other challenges overcome during the design phases.

Jun 13, 2023

By K. Thomson

The Mule Canyon gold deposit, located 14 miles ESE of Battle Mountain, Nevada, was discovered in 1986 as the result of a GFMC grass-roots exploration program. Drilling to date has identified six discrete orebodies which contain a demonstrated gold reserve of 8.487 million tons at an average grade of 0.136 oz/ton, totaling 1,152,000 ounces. Mineralization is associated with argillic alteration and silicification, localized along NNW trending high-angle faults within Miocene basaltic andesites. Trace element geochemistry at Mule Canyon is typical of upper level hot spring precious metal systems, displaying elevated Ag, As, Sb, Hg, and Se.

Jan 1, 1993

By H. P. Hatch

Ash is a material that many people leave to nature to handle. Others sometimes sweep it under the rug to be disposed of by someone else. In our business we cannot do either. In fact the American Electric Power System spends many millions of dollars in plant investment costs to collect the material, and then many more millions to dispose it. In 1965 alone the coal fired steam generating plants in., the AEP System produced approximately 2,400,000 tons of ash, enough to fill 40,000 coal cars which would extend as a single train across the entire states of Ohio and Indiana. Even though our present ash production is large, this is only the beginning when we forecast the future growth of our system. By 1980 it is estimated that our generating capacity will expand to about three times its present size, and with coal as our primary source of fuel our ash production will increase proportionately to about 7 million tons a year.

Jan 1, 1966

By C. B. Kettering

In the early operations of the Inspiration Consolidated Copper Company, which extended from 1914 to 1926, the ore as mined contained principally sulphide copper minerals, manly chalcocite (Cu2S), This ore was milled in a 20,000-ton concentrator and the copper was recovered as a flotation concentrate which, was smelted at the nearby plant of the I ternational Smelting and Refining Company. In those days no attempt was made torecovercopper from any oxide minerals present. As mining operations progressed it soon became evident that the proportion of oxide minerals present would steadily increase, and. it was realized that some method of treatment would have to be developed whereby copper could' be recovered from both oxide and. sulphide minerals contained in the ore. A research program was instituted and after some years of experimental and, pilot plant work a new hydro-metallurgical process was developed whereby it became possible to extract copper from both the oxide and. sulphide minerals in a single leaching operation. The solvent adopted consisted of a mixture of sulphuric acid and ferric sulphate,' Following dissolution, the dissolved copper would be recovered by electrolysis. Also in the process of electrolyzing, spent solutions of sulphuric acid, H2SO4, and. ferric sulphate, Fe2(SOk)3, would be regeneratede and. somade available for continuous reuse. The process appeared to be a success and the decision was made to build a full-sized leaching plant for the future treatment of I spiration mixed ore. Construction was started and the leaching plant was completed in 1926, With the start of ferric-sulphate leaching the Inspiration Concentrator was shut down and, with the exception of a few short time runs has not operated since that time. The ferric sulphate leaching process served. Inspiration well for some 30 years and during that time won a name for itself as a classic example of hydro-metallurgical treatment of mixed sulphide oxide ores. Originally the plant was designed. to process some 7,500 tons per day of a mixed ore containing about 1,2% copper, of which 60% was present as oxide and. 40% as sulphide, Down through the years various improvements were made for the purpose of increasing plant capacity and as well to change the limiting 'factor of sulphide-oxide ratio, The final result was a leaching capacity of 9,600 tons per day when treating a 1% copper ore with a reversal of the sulphide-oxide ratio to 60% sulphide and 40% oxide.

Jan 1, 1958

By S. A. McGhee

ASARCO Incorporated embarked on a modernization and expansion program to improve overall operating efficiencies and to more effectively develop the large mineral reserve at the Ray Complex Open-Pit Mining operation located near Kearny, Arizona. Major elements of this Ray Modernization and Concentrator Expansion Project included engineering and construction of a 54,400 MTPD (60,000 STPD) In-Pit Crusher and Overland Conveying System. and a 24,200 MTPD (30,000 STPD) Copper SAG Concentrator and Tailings Disposal System. Detailed engineering, procurement, and construction management were initiated in November 1989 under contract with Bechtel Corporation. Field construction commenced in May 1990 leading to mechanical completion and start-up during February 1992.

Jan 1, 1993

By Larry A. Enloe

The 16-to-1 milling operation is Sunshine Mining Company's first new silver and gold producing facility. The 16-to-1 underground mine and mill are located approximately 64 km (40 miles) southwest of Tonopah, Nevada. Ore re- serves in the epithermal vein deposit are estimated at 0.91 Mt (one million st) of ore, at an average silver grade of 206 to 240 g/t (6 to 7 oz/st) and an average gold grade of 1.2 g/t (0.035 oz/st). The underground mine uses a large diameter blasthole stoping system of mining using highly mechanized rubber-tired equipment. The mill uses conventional cyanide leaching with countercurrent decantation and Merrill-Crowe precipitation. The mill start-up was in February 1982 resulting in the first pour of dore' in March 1982. The mill's present annual production is approximately 31.1 t (1.0 million oz) of silver and 264 kg (8500 oz) of gold.

Jan 1, 1984

By Foreback T. G.

The McKinley Mine is a large strip operation sup-plying coal to several utility and industrial customers. The mine reserve comprises many coal seams of varying quality and thickness. Erosion of the terrain has created coal out-crop lines that are encountered frequently with associated deviations in quality. Due to the complex nature of the coal reserve and the various customer quality requirements, coal quality control is a primary consideration and a constant challenge at the McKinley Mine. This paper will discuss the practices employed to ensure that the available coal meets contract specifications.

Jan 1, 1994

By Zhian Liang, Xiong Huang, Weixin Wu, Lifeng Cui, Zhuanhua Wei, Guoyao Li, Xiao Ni, Junrong Wang, Shuiping Zhong

ZJ 201 (modified starch) is a non-toxic, odorless, and biodegradable polymeric depressant, which selectively depressed galena in batch flotation tests while chalcopyrite was not significantly affected. In a plant trial, copper-lead separation was successful for the first time without using dichromate. Moreover, the plant process could be changed to sequential Cu-Pb flotation using ZJ 201 for higher grade lead concentrate. A copper concentrate was obtained with a Cu grade of 24.91% and a Pb grade of 5.11%, which recovered 76.6% of the copper from the original ore; a lead concentrate was also obtained with a Pb grade of 21.90% and a Cu grade of 5.31%, which recovered 52.6% of the lead. In addition to the effective copper-lead separation observed in the plant trial, another improvement observed is that gold was recovered mostly in copper concentrate, which could be sold for higher prices. Au grade reached 230.64 g/t, and its recovery reached 65.8% in the copper concentrate. Au grade in lead concentrate was only 18.90 g/t.

Aug 27, 2021

By J. Diaz

"Antioquia region, in Colombia, is considered one of the areas with the highest mercury contamination in the world due to its use in gold recovery through artisanal mining, emissions to the environment between 100 and 150 tonnes of mercury are estimated by year. Therefore it became necessary to develop a project in which it was proposed aim to empower traditional artisanal mining community, or in different areas, such as gold mining in the region of Antioquia, in the implementation of safe mining practices and environmentally sustainable, from the introduction of clean technologies, in order to prevent or mitigate the impacts generated by traditional mining on the environment and the communities involved. In order to achieve this training to traditional mining community developed and technical visits to artisanal mining were performed in order to optimize operating processes and promote safe mining practices. In the project more than 1400 artisanal miners were trained.INTRODUCTION In the developing world, a combined 30 million individuals extract more than 30 different minerals using rudimentary techniques. Gold is the preferred mineral extracted by artisanal operators due to its high unit value and its market price, which has increased almost sevenfold over the last decade (Veiga et al, 2014). The artisanal gold mining sector in Colombia has 200,000 miners officially producing 30 tonnes Au/a. In the Northeast of the Department of Antioquia, there are 17 mining towns and between 15,000 and 30,000 artisanal gold miners (M. Veiga, 2010) (Upme, 2014). This production, however, has caused environmental problems, including high levels of river siltation and mercury pollution (Veiga et al, 2014) (UPME, 2007) (Cordy et al., 2013). The mercury contamination in Colombia by artisanal gold mining has been recognized by a number of researchers and local authorities for over a decade estimated that the annual mercury emissions from artisanal gold miners in Colombia in 2007 were between 50 and 100 tonnes, however given recent gold value increases and gold rush activity, current mercury emissions are likely much higher. Colombia is likely the world's 3rd largest source of mercury emissions from AGM after China (240 to 650 tonnes of Hg/a) and Indonesia (130 to 160 tonnes of Hg/a) (Telmer and Veiga, 2008) and is the world's highest per capita mercury polluter (M. Veiga, 2010)."

Jan 1, 2016

By H. E. Rudi

The advent of open nit mining permitted the development and processing of minerals never before thought possible. New equipment was needed; new techniques were devised; new methods were called for. This development and acquisition of new techniques, methods and equipment did not, however, stir the souls of our industry and educational leaders sufficiently to a recognition of the problem of people, especially the future development of the people needed in open-pit mining. The people problem has been and will be with us as long as there are two of them. The development of people will be required for the same reason. The problem of developing future personnel for open-pit mining is not what must be developed; that is known to all of us and can be briefly stated ashore and better of everything." As I see it, the real problem lies in determining (1) what personnel are really critical, (2) why are they critical and (3) how can we develop them.

Jan 1, 1965

By Tracey A. Conrad, Mark E. Mussett, Max Kaufmann

The varied benthic habitats of the Pacific Ocean are comprised of different types of seafloor geology. These geologic domains generally consist of sedimented abyssal hills, high relief features such as seamounts, and polymetallic nodule fields that vary in spatial extent and abundance. Nodules represent a deep ocean habitat type, and are of economic interest owing to their metals content. Multibeam data can be used to classify seafloor geology. The wide swath of hullmounted multibeam systems used in deep water provides efficient coverage of large areas of seafloor. Our research examines how multibeam backscatter and bathymetry data, with regional environmental parameter assessments and GIS analysis, can help identify probable polymetallic nodule fields in the deep remote ocean prior to groundtruth seafloor observations. A workflow for processing 30 kHz hull-mounted multibeam data within QPS Qimera and FMGT software was developed to facilitate multibeam processing, while also generating a terrain model and backscatter products. An additional GIS protocol for evaluating multibeam data products, including cluster analysis, was also developed. These methods were applied to a test case of publicly available multibeam data collected by the Ocean Exploration Trust and NOAA. Processed multibeam products were used to identify areas exhibiting coarse sediment backscatter characterization with low relief; filters for water depth at or below the regional CCD, seafloor age, and sedimentation rate were then applied. Sophisticated GIS cluster analysis further identified trends within the data to forecast where coarse sediment domains, potentially including nodule occurrences, exist. The test case multibeam data allow determination of the composition and variability of seafloor geology. This analysis can further identify where previously unexplored nodule fields may exist and edify estimates of nodule extent throughout the ocean. The research methods and outcomes contribute to marine spatial planning, ecosystems modelling, and mineral resource management initiatives.

Feb 22, 2026

By P. C. Thakur

Horizontal drilling in coal mines is a relatively new technology. The earliest recorded drilling in the United States was done in 1952 at the Humphrey Mine of Consolidation Coal Company for degasification of coal seams. Spindler and Poundstone experimented with vertical and horizontal holes for eight years. They concluded in 1960 that horizontal drilling in advance of underground mining appeared to offer the most promising prospect (for degasification) but effective and extensive application would be dependent upon the ability to drill long holes, possibly 300-to 600 m, with reasonably precise directional control and within practical cost limits.(1) Mining Research Division of Continental Oil Company, the parent company of Consolidation Coal Company, began a research program in the early 1970's to achieve the above objective. The technology needed to drill nearly 300 m in advance of working faces was developed by 1975 and experiments on advance degasification with such deep holes began in 1976. Preliminary Its of this research have already been published.(2) To date nearly 4500 m of horizontal holes have been drilled for advance degasification and earlier results were reconfirmed. In summary, these are: 1) The greatest impact of these boreholes was felt in the face area where methane concentrations were reduced to nearly 0.3 percent in course of two to three months from original values of nearly 0.95 percent.

Jan 1, 1979

Growing concerns of climate change and its potential association with the release of greenhouse gasses to the atmosphere have prompted possible legislation which would require minimization of greenhouse gas emissions. Carbon dioxide and methane, both of which largely contribute to the greenhouse effect, have direct links to the fossil energy industry sector. Specifically, the combustion of one ton of coal produces between one and three tons of carbon dioxide, dependent upon the carbon content and heating value of the combusted coal. Additionally, coal mine methane (CMM) released through a mine?s ventilation system has a radiative trapping impact approximately 20 times greater than that of an equivalent mass of carbon dioxide. The capture of coalbed methane (CBM) prior to the mining process and its utilization as an alternative energy source provides the possibility of a decreased carbon footprint. Domestically, the past 25 years have seen a significant expansion of the CBM industry. Internationally, in developing countries such as China, the need for western coal degasification technology is growing. A collaborative, international effort will be required to initiate a recognizable decrease in global greenhouse gas emissions. This paper identifies the potential decrease in equivalent carbon dioxide emissions through effective degasification at a hypothetical longwall mine located in China. Advanced, three-dimensional gas reservoir simulation software will be utilized to determine the maximum feasible CBM recovery in a low permeability, high gas content reservoir prior to the mining process.

Jan 1, 2010

By S. Middlemiss

The Indentation Fracture technique is being developed as a tool for use in comminution and mineral liberation analysis. Fracture toughness measurements for a number of mineralogical materials were made and comparisons were drawn between these and properties measured with the Ultrafast Load Cell drop weight apparatus. The technique has also been used as a probe to quantify differences in fracture properties at different areas in the microstructure of a material. In both a Utah limestone and a South African quartzite, material near a grain boundary fractures very differently to that in the bulk. Ongoing work is ultimately aimed at producing a comprehensive fracture model for a multi-mineral system based on its micro-fracture characteristics.

Jan 1, 1994

By H. Colijn

Weight may be defined as the gravitational attraction or earthpull on a body (mass). Thus, from a practical viewpoint, a scale or other form of weighing device is a mans for determining mss. Weighing devices fall into two principal categories: (1) gravimetric; and (2) non-gravimetric or nuclear devices. At present, after many centuries of use, the effect of gravitational force as a meas¬ure of mass in industry and commerce remains by far the most common method for mass (weight) determination. Non-gravimetric methods are just becoming established in the industry. The general trend is toward weighing materials on the Trove. The predominant advantage of continous weighing over batch weighing operations is its ability to handle large tonnages without interrupting the material flow. The accuracy and reliability ability of continuous weighing equipment have improved greatly over the past decade. However, static weighing equipment still outsells continuous weighing equipment, because it is considered more accurate. Batch weighing can also produce a continuous weighed delivery through automation where the process requires it. In caparison with continuous weighing devices, such as belt scales, the batch-type scales have same inherent advantages affecting their accuracy. For example, weighing 300 lbs. per minute on a belt scale may mean that only 3 lbs. will be on the scale mechanism at one time. In order to obtain a scale accuracy of 1/2%, the sensitivity must be at least 1/2% of 3 lbs. or 1/4 oz. On the other hand, a batch scale may discharge a 300 lbs. load every 60 seconds through a timing mechanism. An accuracy of 1/2% can be easily obtained with a sensitivity of 1/2% of 300 lbs. or 24-oz.

Jan 1, 1970

By J. Gauntt

Calcium carbonate is one of the most widely used industrial minerals in applications like cement, lime, agriculture, power plant fluegas desulfurization (FGD) and construction aggregates. Most applications are generally high-volume and low value ($9/t or $10/st) or less free-on-board (f.o.b.) mine site) uses of this material. Specialty uses of ground calcium carbonate (GCC) are typically referred to as ?performance mineral? or ?extender and ?ller? applications. Primary specialty markets for GCC include paper and plastics as well as a number of construction applications including joint compounds, carpet backing, paint, and adhesives, caulks and sealants (ACS). Other important specialty applications for GCC include rubber, food and personal care products. A new and growing application for GCC is in nonwoven fabrics, where this mineral replaces a small percentage of the polymer. Typical specialty applications for GCC are color sensitive and require extremely white/bright materials. Although deposits of limestone are located in most states, high brightness resources are relatively rare and controlled by a limited group of suppliers.

By D. A. Knight

The property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3,600 mm of annual rainfall and a temperate climate with temperatures ranging from 10" C to 22° C throughout the year. Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960's when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group.

Jan 1, 1992