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By Eduardo Velasco, Paz Navarro, Alfonso Navarro, Claudio Cimiotti, Alejandro Sanz, Nick Karlin

The LA Effluent Outfall tunnel is a 7-mile long, 18' internal diameter, secondary treated effluent discharge tunnel currently under construction by Dragados USA for the Los Angeles County Sanitation District No. 2 (LACSD). The purpose of this tunnel is to add redundancy and increased capacity for discharge of secondary treated effluent from the LACSD’s Joint Water Pollution Control Plant, located in Wilmington, California within Southern Los Angeles County. Current discharge from this facility flows through two existing tunnels of 8' and 12' horseshoe profile, constructed in 1937 and 1958, respectively. When the new tunnel is complete, it will add an additional capacity of 670MGD in peak wet weather flow conditions. Geology of the roughly 7 mile long tunnel was divided into six reaches by the contract documents. Tunnel Reaches (TR) 1 to 3, comprising 19,550' will be excavated in alluvial sands of the San Pedro and Lakewood formations, with cover ranging from 45 to 90 feet. In this reach the tunnel intersects the seismically active Palos Verdes fault Zone. TR 4 is a 1,600' transitional zone between alluvium and the rock formations of the Palos Verdes (PV) Hills, comprised mostly of Malaga Mudstone. TR’s 5 and 6 total 15,591', and are within the rock formations of the PV Hills with overburden ranging from 315' to 475'. The primary constituent of the PV Hills is Altamira

Jun 13, 2021

By J. A. Organiscak

Enclosed cab filtration systems are typically used on mobile mining equipment to reduce miners? exposure to airborne dusts and diesel particulates generated during mining operations. Various filter configurations can be used within the heating, ventilation, and air conditioning (HVAC) systems of cabs to remove the airborne contaminants. The air cleaning performance of cab filtration systems is highly dependent on the efficiency of the air filters, the number of filters used, and their placement within the HVAC system. This paper shows how to mathematically model cab filtration systems and illustrates a methodology for developing other cab filtration system design models. Node diagrams of several filtration system circuits are illustrated with their mathematical models at steady state airflow and concentration conditions. Laboratory and field data are presented to demonstrate the validity and utility of modeling enclosed cab air cleaning performance. The paper concludes that incorporating multiple filters throughout the HVAC system improves the air cleaning performance and robustness of the cab filtration system design.

Feb 23, 2014

By Avula Rajashekar Yadav, Sreenivasa Rao Islavath

Barrier pillars and gateroads play a vital role for the safe exploitation of coal from the panel in the longwall workings. The barrier pillars and gateroads are subjected to the front abutment and side abutment loads during the retreat of the panel. These structures may fail if the developed load on them is higher than their strength. The stability of the longwall structures such as barrier, gateroads and face is paramount in extracting the coal from the panel safely. For this, a deep longwall mine in India is chosen for the study using a 3D numerical modelling technique. In this paper, three critical conditions such as scenario 1 (no side goaved-out panel), scenario 2 (with side goaved-out panel) and scenario 3 (with two side goaved-out panels) are taken. For each scenario, five retreat distances such as 100, 125, 150, 175 and 200 m are considered for detailed investigation. The development of vertical displacement in gateroads, vertical stresses on barriers, vertical stress concentration factor, abutment zone and yield zone for longwall face are extracted and analyzed. Also, the safety factor of the barrier and longwall face is estimated considering the Hoek–Brown rock mass failure criterion. From the study, it is observed that the maximum vertical displacement of 121 mm in TG3 at scenario 3 for a retreat distance of 200 m and a minimum vertical displacement of 33 mm in TG2 for a retreat distance of 100 m at scenario 2. The development of vertical stress on the barrier is found to be between 8.78 and 13.40 MPa, and the safety factor of the barrier lies in between 1.56 and 1.80. The study also revealed that the yield zone at the longwall face lies within 2 to 3 m.

Dec 29, 2023

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for the industrial and defense sectors. In 2018, the U.S. Department of the Interior presented the final list of critical minerals that are vital to the U.S. economy and defense [1], which included REEs among other mineral commodities. REEs are not rare, despite their name, but economically viable deposits of REEs can be found only in certain geographical areas, and the political and social conditions characterizing these areas may not always be in favor of mining operations. Mining operations may be placed in great operational and financial risk if operations are planned in such areas. Erroneous decisions by decision makers may lead to a chain of events that can completely shut down a mining project. 

By Mingyang Li, Yan Lv, Xiaolong Ma, Xudong Gao, Jie Zhao, Yingyi Zhang

This study aims to investigate the reduction thermodynamics of ilmenite and pre-oxidized ilmenite, and reveals the isothermal reduction kinetics of pre-oxidized ilmenite concentrate by carbon monoxide. The results indicate that the ilmenite concentrate and pre-oxidized ilmenite concentrate can be selectively reduced by controlling the temperature. The pre-oxidation process leads to the breakage of complex mineral structure, and the formation of porous simple oxides, which is an effective method to increase the reduction and leaching rate. 

By Crystal Poon, Paul Matlashewski, John Morkeh, Kathryn Dorfschmidt, Jose Carvalho, Chad Williams

Rockfall hazards are ubiquitous in mining environments making their control critical for safe mining operations. The complex processes involved in rockfall events necessitate a probabilistic modeling approach with well-calibrated material properties. The controls designed to mitigate rockfall hazards need to be reliable, efficient, and safe to deploy to meet the constraints present at an active mine. This paper presents an innovative solution to rockfall at Rio Tinto’s Bingham Canyon Mine. The solution incorporates the site-specific calibration and creation of a predictive rockfall model with the design, field testing, implementation, and monitoring of the rockfall controls.

By V. K. Srivastava, T. Gupta, T. Ghosh

"In recent years, the demand for rare earth elements (REEs) has grown due to increasing demand and global supply shortage. The supply deficit of these critical elements has encouraged the search for new sources, with coal and coal byproducts as possibilities. Coals from certain parts of the world can be rich in REEs and can approach a total concentration of 1,000 ppm. Two Alaskan coal samples, from Healy and Wishbone Hill, were investigated for the effects of density and particle size on REE concentrations for three selected size fractions, and flotation tests were conducted on finer fractions. Additionally, bottom ash and fly ash samples from a power plant were examined for their REE concentrations. The results show that the upgrade potential for REEs on an ash basis from a whole-coal basis ranges from 2:1 for the Wishbone Hill samples to 4:1 for the Healy coal samples. Flotations of the finer fractions of the two coal samples, conducted under similar conditions, revealed higher concentrations of REEs in the tailings. Both coal samples had comparatively higher contents of light-group rare earth elements (LREEs) than heavy-group rare earth elements (HREEs). REE content trends for the power-plant products on an ash basis indicate that fly ash has slightly higher concentrations of both LREEs and HREEs than bottom ash. IntroductionRare earth elements (REEs), also known as rare earth metals, and their compounds are vital components in industrial, automotive, petrochemical, defense and medical applications. Dysprosium in combination with other elements is used in laser materials and nuclear control applications. Neodymium is present in magnets that are used in the manufacture of wind turbines and hybrid cars. Europium, terbium and yttrium are used in devices that have visual displays such as computer screens and laptops (Haxel, Hedrick and Greta, 2002; Bunzli, 2013). REEs pose fewer environmental problems of disposal and recycling than their conventional heavy metal counterparts (Haxel, Hedrick and Greta, 2002). They are key materials for radar systems, avionics, modern national defense and satellites (Cammarata and Sieradzki, 1994; Hedrick, 2010; Martin, 2010; Szumigala and Werdon, 2011; Cordier, 2011; Bunzli, 2013). REEs are often classified into light-group rare earth elements (LREEs) and heavy-group rare earth elements (HREEs). This classification is primarily based on the electronic configuration in the outermost shell. LREEs, ranging from lanthanum to gadolinium, have a single or no spinning electron in the outermost 4f shell while HREEs, ranging from terbium to lutetium, have paired electrons in the 4f shell. This difference in electronic configuration is responsible for the differences in physical and chemical properties of REEs."

Jan 1, 2017

Flooded-bed scrubbers on continuous miners have been shown to be an effective respirable dust control technology, traditionally used during the extraction of extended cuts of up to 12.2 m (40 ft). To effectively use scrubbers in faces that employ exhaust ventilation, the return ventilation curtain or tubing should be located outby the scrubber discharge on the continuous miner, which results in a setback distance from the face of approximately 12.2 m (40 ft). The goal of this research was to compare respirable dust levels generated in 6.1 m (20 ft) cuts when using extended curtain setbacks with a scrubber operating to dust levels in 6.1 m (20 ft) cuts when using traditional exhaust face ventilation without a scrubber operating. Dust surveys were completed at three mines with area and personal sampling conducted to quantify respirable dust concentrations on a cut-by-cut basis. Sampling results did not show a statistically significant difference in respirable dust at the continuous miner or shuttle car locations with and without the scrubber operating. However, with the scrubber operating, respirable dust concentrations in the return airstream downwind of the miner showed reductions of 91%, 86%, and 40% at Mines A, B, and C, respectively. The reductions at Mines A and B were statistically significant. Likewise, reductions in respirable quartz dust levels in the miner return were observed at all three mines, with statistically significant reductions of over 80% observed at Mines A and B. Consequently, operation of the flooded-bed scrubber did not impact respirable dust levels in the face area but did significantly reduce respirable and quartz dust levels downwind of the continuous miner. These results were obtained with the mines operating at or above the minimum operating levels specified in their ventilation plans.

Feb 23, 2014

By David Hartley

United States Steel Corporation Minntac Mine is located at Mt. Iron, Minnesota, on the Mesabi Iron Range. The taconite pit is two miles long by a mile wide, with a maximum depth of 170 feet. This paper will deal with the radio remote control of locomotives engaged in the railroad haulage of crude ore and waste rock at this property.

Jan 1, 1970

By Donald J. Olson, Thomas J. Lutzenberger, John Ramage

The North Shore Inline Interceptor, Phase IA tunnel is a 8,550-meter (28,000-ft) interceptor tunnel currently being constructed by Traylor Bros./Frontier-Kemper, Joint Venture, using a 9.8-meter (32-ft - 4-in) diameter Robbins tunnel boring machine (TBM). This tunnel is being driven in Silurian age dolomite approximately 91.5 m (300 ft) below ground surface. Significant water inflows were encountered when the tunnel drive penetrated the thinly-bedded Waubakee Formation. Flow increases approaching 0.75 cu m per min per 30 m of tunnel (200 gpm per 100 ft) have occurred in this formation. After driving approximately 2,285 m (7,500 ft) of tunnel (200 m full face in the Waubakee Formation), total flows exceeded 12 cu m per min (3,200 gpm) with about 5.7 cu m per min (1,500 gpm) entering the tun¬nel from the 200 m (600 ft) of exposed Waubakee Formation. Additional water control measures consisting of increased pumping capacity, increased water treatment capacity, surface grouting ahead of the tunnel, grouting ahead of the tunnel face and panning to improve the working environment for installation of tunnel support, were implemented to deal with the large water inflows. Currently (January 24, 1989), 3,400 m (11,000 ft) of tunnel has been driven, total water inflows are in the range of 11.7 cu m per min (3,100 gpm) with only 6.8 cu m per min (1,800 gpm) inflow from about 1,220 m (4,000 ft) of tunnel driven full face through the Waubakee Formation.

Jan 1, 1989

By Kenneth W. Torpey, James G. Ball, Richard F. Flanagan, David S. McAllister

INTRODUCTION Under a Federal grant by the Urban Mass Transit Administration (UMTA) (80%), and sponsored by the State of New York (200), Niagara Frontier Transportation Authority is constructing a 10.3 km (6.4 mile) light rail rapid transit system in Buffalo, New York. The $450 million project, which began construction in the Spring of 1979, is unique in rail transit alignment designs in the U.S.A. and the first predominantly underground light rail system in North America. The Buffalo project is unique in that the first phase of the expandable system follows the alignment of Main Street and is on the surface in a proposed 1.6 km (1.0 mile) pedestrian mall in the downtown business district. The alignment then progresses northward into a cut-and-cover portal and standard double-box configuration for 2.74 km (1.7 miles) at a depth of 9.1-10.7 m (30-35 ft) and subsequently drops into bedrock at depths of 18.3-27.4 m (60 to 90 ft). The 5.63 km (3.5 mile) rock tunnel section consists of two single tunnels 4.88 m (16.0 ft) nominal finished diam. and includes five stations. The rock tunnel line section was divided into a north and south contract of 2 316 m (7,600 ft) and 3 243 m (10,640 ft), respectively. Due to the existing surface facilities and the future station locations, the line tunnel contracts differed considerably in their shaft access

Jan 1, 1981

By T. Petrov

This study was performed to analyze the behavior of the blowing curtain face ventilation system modified with a specially designed regulator, called Wing Regulator. The purpose of the regulator is to extend the airflow penetration depth toward the face and allow effective face ventilation at curtain setback up to 13.7m (45ft) from the face. A small scale model of the Wing Regulator was successfully tested in the Mine Ventilation Laboratory at the University of Kentucky. Then a prototype of the proposed regulator was tested in full-scale in mine environment. Series of three dimensional simulations were performed to support this research using validated CFD code. This paper presents results of the performed studies and discuses the advantages of using the Wing Regulator. Presented information relates to the US Provisional Patent Application No 61/818,112.

Feb 23, 2014

By T. A. Gray

The environmental liabilities of coal waste disposal sites can have a major impact on a mining project's economic viability. Developing a waste disposal site is no longer simply an exercise in completing paperwork to obtain a permit, with the proliferation of environmental regulations in recent years, managing disposal sites now requires design creativity, short term and long term planning and detailed monitoring to maximize the benefits to the mining company. Operating costs and future capital costs for expansion of existing sites, new site development and regulatory compliance should be reviewed periodically and considered in the overall management plan. This paper discusses various management methods that are being employed in the industry to improve waste disposal operations both environmentally and profitably.

Jan 1, 1994

By N. Ripepi

"The Langmuir model has been widely used for the coal-methane sorption process via an isothermal test. However, even though the temperature-dependent Langmuir model were recognized theoretically and experimentally, the quantitative relationship between the Langmuir’s constants (a & b) and temperature have not been clarified and confirmed by lab test data. This paper collects 158 methane-coal sorption data under different temperatures, which apply the Langmuir model to consider the relationship between Langmuir’s constants (a & b) and temperature (see APPENDIX I). Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters (a & b). The results from these published isothermal tests confirm that 1) there is no consistent relationship between Langmuir’s constant-a and temperature; 2) the Langmuir model is a temperature-dependent model, and the temperature-dependent feature is mainly shown by the relationship between Langmuir’s constant-b and temperature; 3) The relationship between Langmuir’s constant-b and temperature can be described by both the exponential and linear relationship with dried coal. This paper provides a database for temperature-dependent Langmuir’s model, which can be used for reservoir simulation of coalbed methane reservoir, coal seam degasification modeling for underground coal mines considering the heating effect induced by geotherm and heat injection (via hot water, hot steam, ultrasonic, etc.). INTRODUCTION The isothermal test for gas sorption on coal is one of the fundamental tests in Coalbed Methane (CBM) recovery fields, such as underground coal mine methane degasification, CBM gas-in-place estimation, and carbon dioxide sequestration in un-minable coal seams. Generally, two methods, volumetric and gravimetric, are employed to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012). Based on these two approaches, a series of commercial and self-assembled instruments are built and several calculation methods are used to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012, Gasparik, K., 2014; Goodman, A. L., et al, 2004; Zhang, L., et al, 2013). In the post-processing stage, many models are provided to analyze isothermal data in order to understand the storage mechanism of gas in coal. Common models include the Langmuir model (and its extended forms), the pore-filling model, multilayer adsorption model (BET), and the Gibbs’ model. Among these models, the Langmuir model is the most widely used for its simplicity and functionality. The Langmuir model is expressed as follows:"

Jan 1, 2016

By Richard Klimpel

The laboratory ball mill grinding of coal/water slurries is described for three coals. Emphasis is placed on the measurement of specific rates of breakage for various operating conditions. Corresponding rheological information is also presented based on data collected using a rotational viscometer. A rheological explanation of the influence of various slurry fluidity conditions on the specific rates of breakage is presented. This rheological approach has proved useful In both the identification of suitable chemicals for increasing breakage rates in coal/mineral slurry grinding and in the plant scale implementation of dense slurry grinding systems.

Jan 1, 1982

By JIAQI JIN, Joe Milbourne, Maoming Fan

Gold is very important to support the financial system, and to be used in industries of the jewelry, high-tech fields such as electronics and aerospace, etc. Gold is mainly extracted from three types of ores: primary ore (vein gold), placer (alluvial gold) and associated ore. Cyanide was widely used in gold ore flotation to depress gangue minerals and leaching/cyanidation. The process of extracting gold from gold ore, its separation and flotation concentrate, specifically through a technique called cyanidation or cyanide leaching. This method, which has been dominant since the 1970s, utilizes a dilute solution of cyanide to dissolve gold from the ore. While effective, the use of cyanide raises environmental and safety concerns due to its high toxicity. Cyanide spills can have severe environmental consequences. This has led to the exploration of alternative, environmentally friendly reagents. This paper discusses processing results using the alternative flotation depressants such as sodium sulfite (Na2SO3), etc. to produce a goldrich flotation concentrate for sale to a smelter or as feed to an alternative leaching agent. and methods to extract gold from ore without relying on cyanide.

Feb 22, 2026

By Malcolm J. Robinson

Over 80% of Australia's population lives within 200 km of the coast, 70% in 10 major coastal cities. Potential cement raw materials are widely distributed but deposit size, quality, transport, market and environmental considerations are important in determining economic value. Major production locations are in a variety of geological environments ranging from Lower Paleozoic crystalline limestones to Tertiary and Recent polyzoal limestones and limesands, both onshore and offshore. Raw material transportation is by road, rail, sea, aerial ropeway and pipeline; road/rail transportation of the finished product is traditional but movement by sea of clinker and cement is increasingly a feature of the industry.

Jan 1, 1982

By Charles H. Rice

Coal liquefaction processes can be divided into two broad classifications - direct and indirect. Direct liquefaction processes, in general, slurry coal with a solvent and react it with hydrogen under elevated temperature and pressure. Indirect liquefaction is the term applied to processes in which coal is first gasified to generate a synthesis gas of carbon monoxide and hydrogen. The synthesis gas is then converted to various types of liquid fuels by the proper selection of catalyst and conditions. The first experiments on direct coal liquefaction were undertaken in 1933 by Bergius. Development and commercialization of the Bergius concept was accomplished mainly through the effort of I.G. Farben at the Ludwigshafen plant of its subsidiary, Badische Anilin und Soda Fabrik A.G, under the leadership of M. Pier (1). A demonstration plat having an annual capacity of 100,000 tons of coal was built in Leuna, Saxony in 1927. Six years later, Imperial Chemicals Industries, Ltd., commissioned a plant in Billingham, England (2).

Jan 1, 1981

By Crystal Poon, Paul Matlashewski, John Morkeh, Kathryn Dorfschmidt, Jose Carvalho, Chad Williams

Rockfall hazards are ubiquitous in mining environments making their control critical for safe mining operations. The complex processes involved in rockfall events necessitate a probabilistic modeling approach with well-calibrated material properties. The controls designed to mitigate rockfall hazards need to be reliable, efficient, and safe to deploy to meet the constraints present at an active mine. This paper presents an innovative solution to rockfall at Rio Tinto’s Bingham Canyon Mine. The solution incorporates the site-specific calibration and creation of a predictive rockfall model with the design, field testing, implementation, and monitoring of the rockfall controls.

By James S. Redpath

"The ways of the world be many and most of the ways be tried, you follow in the footsteps of others till you come to the great divide". These words, written by Robert Service a long time ago, come to mind when I think of our original attitude upon entering into a contract with the International Nickel Company to sink the deepest shaft in the world outside of the Union of South Africa. This shaft was to be sunk to a depth of 7,137 feet from surface, and while it was recognized by all concerned to be a somewhat unusual undertaking in our part of the world, the fact that quite a few shafts had already been sunk to this depth in South Africa probably gave us the feeling that we were following in the footsteps of others. In retrospect, because this shaft was being sunk under entirely different conditions than those existing in South Africa, we were in fact venturing into an entirely new area of endeavour without properly recognizing this fact. It has occurred to me that others considering a similar type of job could benefit from our experience, especially in an assessment of the risks involved and how they compare to those encountered in an ordinary shaft. For comparison purposes, I would define an ordinary shaft as being sunk to a depth of 5,000 ft or less, and a deep shaft as one being sunk to a depth of between 5,000 ft and 8,000 ft. The sinking of the Creighton No. 9 Shaft has been de-

Jan 1, 1997