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By R. H. Olson

Pigments are used in two segments of papermaking, as the major component in paper coating formulations and, in small percentages, as fillers in the paper web. Historically, the dominant use has been in coating, however, recent developments have fostered a multifaceted effort to substantially increase the pigment component in the paper furnish. Factors responsible for these developments together with their relationship to recent and forecast changes in papermaking technology are reviewed. Finally, some thoughts are presented on the probable timing and extent of these changes as well as their expected impact on the future demand for the common paper pigments.

Jan 1, 1985

By Raj K. Rajamani, Samira Rashidi

Wear is an extremely important topic when considering high-pressure grinding rolls (HPGR) for any new application. Given the inevitable variations in ore properties throughout a mine’s life, it is difficult to predict the effect of material and operating conditions on the wear parts: specifically, the HPGR rolls. However, the possibility of continuous scanning of rolls provides ample information to review the wear pattern and ways to optimize it. In this regard, as part of a broader investigation, the feasibility of in-line scanning of HPGR rolls in a laboratory-scale HPGR is studied and presented. The choice of scanners and methods adopted to achieve high-level accuracy for determining wear is discussed in this paper, and the inherent variability affecting the measurements is evaluated. 

By MAURICE SUNKPAL, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

In this study, various rib bolting scenarios were investigated to better understand the effectiveness of the support systems. A coal mass constitutive model is implemented to a distinct element method (DEM) code, and rib factor-of-safety (RibFOS) analyses were performed by applying strength reduction for the coal matrix and explicitly modeled face cleats. Ribs with various overburden depths and mining heights composed of solid banded bright coal were considered. Different scenarios such as rib bolt length and number of bolts were studied to quantify the effect of primary rib support density on rib stability. As a result of the unsupported coal rib analyses, a decaying exponential relationship is proposed between the mining height-overburden depth and the RibFOS. The developed coal rib models clearly show the coal-rib bolt interaction and illustrate how the addition of rib bolts restricts the movement of the coal rib. The results reveal that the strength-reduction method in DEM code with the coal-mass model can aid in the development of practical primary sup- port charts, which can help in the rib support design process.

Feb 1, 2024

By R. A. Winters

At the operations level, productivity is a principle key to profitability. If you are competing with other mines that are paying roughly the same wage rate and the same prices for capital, materials, and energy, the only way your profit can be greater is by producing more output per unit of input. Mines with higher productivity have higher profit margins. Higher profit margins lead to greater operating cash flow, and cash flow is what distinguishes a dog from a cash cow. The turnaround in U.S. metals during the 1980s was in large part due to incredible improvements in productivity. According to statistics compiled by Kaufmann, 1991, labor productivity, measured as tonnes of primary production/manhour, increased 64% in steel, 94% in copper, 75% in lead, 143% in zinc, 132% in molybdenum, and 75% in gold. These improvements were hard won. However, with most modernization programs now complete, measuring and monitoring productivity becomes even more important as producers strive to maintain the gains they have achieved.

Jan 1, 1993

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION Sublevel long-hole stoping is a large tonnage stoping method that may be used when there is a fairly com¬petent straight vein and the walls will stand with little support. It is a method that lends itself to a high degree of mechanization. Two variations of the method are illustrated in Figs. 1 and 2. Fig. 1 illustrates development typical for a 3-m (10-ft) wide vein. Initial development is by a lower haulageway, which may be either track or trackless. A two-compartment raise is driven in the footwall of the vein. At about 12 m (40 ft) above the main head¬ing, a footwall scram is driven and pockets through the vein are cut on 7.6-m (25-ft) centers. Each of the sub¬level blocks selected in this example is 45.7 m (150 ft) long by 12 m (40 ft) high. Stoping starts at the slot raises at stope endlines and retreats to the timbered raise. This retreat sequence starts on the lowest sublevel and the opening cut is blasted into the slot raise. This retreating system is used in order to provide a good safe back over the miners working in any given sublevel. A crawler-mounted down-the-hole or conventional pneumatic drill puts the holes down from one sublevel to the next on any desired drill pattern. Gravity flow brings the broken ore down to the scram level. The illustration shows a large slusher mounted at the timbered raise and slushing from the pockets back to the raise chute. Development of the ore block in Fig. 2 is typical for a 5.5-m (18-ft) wide vein. Initial development is by a trackless heading driven in the footwall of the vein. Pockets are then put into and through the vein on 7.6-m (25-ft) centers. For ease in using trackless rubber tired mucking equipment, these pockets are crosscut to the vein at approximately 1.04 rad (60°) rather than per¬pendicular. A two-compartment timbered raise is driven down from one level to the next. Endline slot raises are again put through from level to level. Each of the sub¬level blocks selected in this example is 40-m (130 ft) long by 33.5 m (110 ft) high. Stoping starts at the slot raises and retreats back to the timbered raise. Long holes are drilled from one sub¬level down to the next by starting between the lowest pair of sublevels and then working up the ore block. Mucking out of the pocket drawpoints is accomplished by rubber-tired load-haul-dump (LHD) units which then dump into a centrally located orepass.

Jan 1, 1982

By Nate Ober, Heath Rushing

"Mining companies want to be in a position to move quickly and seize a favorable market or to keep their key staff productively busy. One of the problems for these companies is the time required to compensate for unavoidable impacts that the mine will have on the natural environment and to gain environmental permits. All too often, circumstances that were favorable when the project was proposed have become less favorable by the time all the hurdles have been cleared.Accordingly, many mining companies are interested in ways they can inject more predictability into their timelines for gaining environmental permits, shorten those timelines, and be more certain of getting the permits they need to carry out their next project.One increasingly popular way to do this is through a relatively new kind of service — the mitigation bank.Mitigation banks purchase property or easements through property that has been impacted by agricultural, industrial or resource activity. They then turn it around from an environmental point of view. This might include restoring streams and wetlands so that fish and aquatic organisms can survive, and animals have habitat and food to flourish.Appropriate native species of plants including trees and shrubs are planted, and steps may be taken to introduce wildlife to the new habitat. In some cases, a special focus is placed on creating habitat for rare and endangered species of plants or animals.The property is inspected by regulatory authorities, coordinated through an interagency review team (IRT). If the property is determined to be effective as natural habitat, the mitigation bank is then issued credits that it can then sell to development projects that are creating an unavoidable permitted environmental impact elsewhere. A mining company, for example, would buy credits to offset the aquatic impacts due to construction of a mine, access roads and other infrastructure — as required by the Section 404 Clean Water Act permit that governs those unavoidable aquatic impacts. The mitigation bank used for offset must have an IRT-approved service area that includes the location of the impacts."

Jan 11, 2017

By Leo Gentile, David Selhorst

The $528 million Toledo Waterways Initiative (TWI) was implemented by the City of Toledo in 2002 and completed in August 2020. Toledo is one of many US cities required to implement a Long-Term Control Plan (LTCP) but one of few to have completed its plan. TWI consists of three storage and conveyance tunnels, four below grade storage basins ranging from 4 to 36 million gallons (MG), miles of sewer separation and interceptor improvements, green infrastructure and other appurtenant structures to dramatically reduce combined sewer overflows to the Maumee River, Ottawa River and Swan Creek. All three rivers flow into Lake Erie. The City’s 180-year history as a Midwest shipping, manufacturing and transportation hub provided design engineers and contractors no shortage of unknown underground challenges to complete the projects. The City will begin its 5-year Post-Construction Compliance Monitoring in 2021 to satisfy the final LTCP requirement. A program overview and experience from tunnel and underground basin construction in urban areas with buried active and legacy infrastructure will be discussed.

Jun 13, 2021

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedoms with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth". The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1979

By Barry R. Doyle, Emma C. Ross

This paper presents a 20-year global account of tunneling in gassy ground demonstrating high probability of schedule delays, cost overruns, worker injuries and fatalities. Causes of these failures are systemic. Gas is seldom characterized in terms relevant to design of effective ventilation systems. Control measures deployed in tunnels are often based on outdated industrial safety codes. A change in approach is needed. This paper describes how to perform a desk study to determine if field investigation for gas is warranted, and lists the content of an effective characterization of gas in a geotechnical report.

Dec 1, 2022

By Kostas Kaklis, Zach Agioutantis, Robin Flattery

Pillars are used as the primary support structures for underground mining to maintain stability by supporting the over laying strata. In the case of horizontal seams, the pillars are typically subjected to axial loading due to the weight of the overburden and/or abutment stresses, while in the case of inclined seams they are subjected to oblique loading due to both the vertical and horizontal in-situ stress.

By E. E. Malouf

For centuries small amounts of copper have been recovered from acid mine-drainage waters. In recent years, the expansion of copper-bearing waste dump leaching for copper recovery has established a technological basis that is rapidly converting the art of copper leaching' into a science. Leaching of copper, whether from copper-bearing ore or waste, follows well established chemical reactions. These reactions are commonly in an acid circuit, but where leaching of copper is to be made in rock that is a high acid consumer, ammonia and ammonia carbonate, as well as cyanide leach solutions, can be used effectively. Current hydrometallurgical processes are being applied at an ever increasing rate to recover the trace amounts of copper in copper mine waste by in-place leaching. Currently approximately 300, 000 tons of copper are produced annually in this manner where as recently as ten years ago, only one-eighth of this amount of precipitate copper was produced.. Where copper occurs as an oxide in higher concentrations as to be classified as an ore rather than waste, then the hydro-metallurgical processes are applied as percolation or agitation leaching in vats, pachuca tanks, or prepared heaps. This approach gives better control over the recovery of the leach solutions, particularly in the processes where ammonia or cyanide leaching agents are to be used.

Jan 1, 1972

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jason Navoyski, Jennica L. Bellanca, William J. Helfrich

Recent advances in computing, rendering and display technologies have generated increased accessibility to virtual reality. Virtual reality allows for the creation of dynamic, high-fidelity environments to simulate dangerous situations and test conditions and to visualize concepts. Consequently, numerous products have been developed, but many of these are limited in scope. Therefore, U.S. National Institute for Occupational Safety and Health (NIOSH) researchers developed a virtual-reality framework, called VR Mine, to rapidly create an underground mine for human data collection, simulation, visualization and training. This paper describes the features of VR Mine, including mine generation, simulated networks, proximity detection systems, and the integration and visualization of real-time ventilation models.

By Elif Emil-Kaya, Bernd Friedrich, Merve Papakci

Samarium (Sm), one of the rare earth elements (REEs), and cobalt (Co) are used in the production of SmCo permanent magnets, which have excellent temperature stability, corrosion resistance and oxidation resistance. Of the two types of SmCo magnets, one contains a high amount of iron, approximately 15.2 percent. This paper focuses on the recycling of iron (Fe)-bearing SmCo. In this study, an oxidative leaching process with nitric acid was developed to eliminate iron through in situ hydrolysis and to dissolve REEs and Co. The influence of experimental conditions on the formation of an amorphous iron compound through the hydrolysis of Fe3+ in a nitric acid environment was thoroughly examined based on a Taguchi orthogonal array. The optimal parameters for oxidative leaching were determined to be an acid concentration of 3 mol/L, a solid-to-liquid ratio of 1/10, and a process temperature of 60 °C.

Jul 1, 2024

By Trevor Riters

Advancements in Emerson’s instrumentation technology have brought value and efficiencies to the mining industry. Some think of instrumentation as basic sensors and valves, but with our solutions, we equip operators with real time, accurate, and reliable data that they can use to operate more effectively. Working with Caltrol, an Emerson Impact Partner, we successfully engineered wireless skids for a leach pad to provide precise measurement and control of raffinate solution to many of the large mine sites in Arizona.

Feb 1, 2025

By P. Otto, G. Borm, Th. Dickmann, F. Amberg, R. Giese

Based on many years experience, the well approved Tunnel Seismic Prediction System (TSP) has been substantially enhanced for online geological prognosis in underground construction. The method provides high resolution seismic images of the rock mass ahead of a tunnel face via an array of standard anchor rods. These contain3D-geophones and can routinely be installed during the excavation process. A further outstanding feature of the system is the newly developed high frequency repetitive seismic source which can easily be fixed at a tunnel boring machine. A user-friendly software package enables online data acquisition, processing, 3D-visualization, and interpretation.

Jan 1, 2001

By O. Porterfield, M. O’Kane, M. Endersby

BHP Iron Ore initiated research programs in January 1995 to develop long-term plans for decommissioning waste rock material at its Mt. Whaleback operation. More than 2 Gt (2.2 billion st) of waste rock were deposited during the past 30 years. Ultimately, a total of 4 Gt (4.4 billion st) will be deposited in waste rock dumps constructed near the open pit. The Mt. Whaleback operation is located in a semiarid climate adjacent to Newman, Western Australia. The primary research program includes the development of technology for the long-term performance of the waste rock dumps with respect to vegetation, slope stability, surface runoff, erosion and water infiltration. This paper focuses on the design and implementation of a cover system to prevent water infiltration to the underlying waste rock. Data obtained from a laboratory program and from soil-atmosphere modeling was used to design horizontal field test plots. The construction of the horizontal surface field test plots is discussed together with the field instruments installed to monitor performance. The cover system is designed to maximize infiltration during wet periods for subsequent evapotranspiration while minimizing surface runoff. The result is a near-zero net infiltration to the underlying waste material. An important feature of the design is the use of run-of-mine waste material as the cover material. Monitoring is in progress and will continue for at least two annual wet/dry cycles. The optimum cover system should minimize the net infiltration of water to the underlying waste rock while maintaining physical and ecological integrity for long-term performance.

Jan 1, 2000

By William Gleason

"When Dr. Joseph A. Holmes was named the first director of the U.S. Bureau of Mines in 1910, the challenge in front of the mining industry was urgent and profound. Just three years before the Bureau was formed, the United States’ coal industry saw a spike in fatalities, as 3,242 miners lost their lives, including 918 miners killed in 18 major disasters. Holmes, who is often called the Founding Father of Mine Safety, was charged with researching and finding new and safer methods to conduct mining activities as well as more efficient ways to conduct mine rescue to educate miners.The U.S. Bureau of Mines was dissolved in 1996, but the mission of the Holmes Mine Rescue Association remains intact, although the challenges have changed greatly.During the 102 years between its formation and the 2018 Joseph A. Holmes Safety Association & Holmes Mine Rescue Association Annual Meeting and Training Seminar in Denver, CO June 5-7, the mining industry has evolved to become one the safest industries in the United States, with an injury rate on par with school teachers and better than retail workers. The work of Holmes and the Bureau of Mines plotted a course for others to follow, and the fatality rate has plummeted to historic lows. However, those who work in the mining safety and health sector remain diligent to their cause and are slow to celebrate too much the accomplishments of the past century, focusing instead on the work that lies ahead.“The nature of mining accidents has changed and it is very difficult to make changes when you get down to the asymptotic part of the equation,” David Zatezalo, assistant secretary of the U.S. Mine Safety and Health Administration (MSHA) told Mining Engineering. He was the featured speaker at the Joseph A. Holmes Safety Association annual meeting’s banquet dinner and presented a thorough overview of the mission of MSHA and his goals as its top man.Nominated by President Donald Trump, Zatezalo was sworn in as the ninth assistant secretary for MSHA on Nov. 30, 2017 and brings with him a lifetime of experience in mining. During his presentation, he displayed the chart (Fig. 1) showing the dramatic improvement in safety that the industry has achieved during the past century, but he noted that, as the industry gets closer to its end goal of zero fatalities, it has become increasingly more difficult to cross the finish line."

Jan 8, 2018

By D. Spindler

Pursuant to the Federal Surface Mining Act of 1977 and the Illinois Surface Mining Act of 1980, Illinois has adopted revegetation success standard regulations that include the Agricultural Land Productivity Formula. The Formula establishes yield goals and standards to measure the success of meeting yield goals for reclaimed prime farmlands. The formula compares the quality of the pre-mining soils in the permit area and the county, to the crop production achieved on the reclaimed permit area and the county crop yield in a given crop year. The regulations also specify acceptable crops, erosion control requirements and time frames for demonstrating success.

Jan 1, 1986

By Romeo S. Jurani

Yucca Mountain, located in Southern Nevada approximately 160 krn northwest of Las Vegas, is currently the site of intensive surfacebased and underground investigations. The investigations are required to determine if the site is suitable for long term isolation of the Nation's high level nuclear waste inventory. A major component of the program is the Exploratory Studies Facility, or ESF. The ESF, when completed, will consist of approximately 25,600 meters of tunnels and drifts. The network of tunnels and drifts (Figure 1) will house and support a wide array of testing programs conceived to provide physical information about the site. Information on geologic, geomechanical, and hydrologic data will be used in the repository design if the site is found suitable. Besides a few special requirements, the general ESF ventilation criteria during construction are similar to that of commercial tunneling and mining operations. The minimum air velocity at the Tunnel Boring Machine (TBM) and other active mining faces is 0.51 meter per second (m/s) (100 feet per minute [fpm]). Airways, estimated leakages and ventilation controls are converted into equivalent resistances for input to mine ventilation network computer simulations. VNETPC Version 3.1 computer software is used to generate the ventilation models for optimized system design and component selection. Subsequently, actual performance of the ventilation system will be verified and validated to comply with applicable nuclear regulatory quality assurance requirements. Dust control in the ESF is dependent on effective dust collection, enclosure, and airflow dilution. Minimum use of water, as feasible, is necessary to avoid adding moisture to the potential repository horizon. The limitation of water use for test drilling and TBM operation, and the rigid compliance with applicable federal and state regulations, make the ESF a ventilation design challenge.

Jan 1, 1995

By Debra C. Man, S. Thomas Freeman, F. Wiley Horne

INTRODUCTION The Metropolitan Water District of Southern California (Metropolitan) is the largest water wholesaler in southern California. Its service area spans the major urbanized portions of Ventura, Los Angeles, Orange, San Bernardino, Riverside and San Diego counties. More than 15 million people are serviced by Metropolitan through its 27 member agencies. The primary sources of Metropolitan's water supply are the Colorado River Aqueduct (CRA) and California's State Water Project (SWP). Currently, planning and design level studies are underway by Metropolitan to expand the water storage and conveyance systems within the service area for the purposes of providing increased efficiency and flexibility to manage limited water supplies, improving water quality, and increasing system reliability. The system reliability issue is particularly significant because the conveyance facilities from both the CRA and the SWP must cross the active San Andreas fault. This fault is considered to be the source fault for the anticipated "Big Earthquake" in southern California. To meet these objectives, Metropolitan's expansion plans involve a major new storage reservoir, new large diameter pipeline and tunnel conveyance facilities, more efficient utilization of existing groundwater basins, and an aggressive public awareness and conservation program. This paper focuses on the planning studies that have been carried out for over 50 miles of tunnels being considered for several of Metropolitan's proposed conveyance systems. These tunnels have ranged in length from a few hundred feet to over 42,000 feet, with depths of cover ranging from a few tens of feet to over 3,000 feet, and finished diameters ranging from 10 to 20 feet.

Jan 1, 1993