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By Debra Switzer, Swapnil Urankar, Douglas Watson, Steven Hunter, Chandranth Banerjee, Shashank Pathak

A hydrocyclone is a piece of equipment commonly used as a classifier in mill circuit operations. Traditionally, hydrocyclone performance is characterized by the classification efficiency parameter, such as cut size (d50c), sharpness of separation () and bypass (Rf ). A plethora of endeavors have already been made to develop parametric models to determine hydrocyclone performance that correlate design and process variables. In contrast to those studies, we made an attempt to develop an approach to derive required design parameters purely from hydrodynamic principles that provides a platform to optimize the operation of a hydrocyclone for a given application. In this selection methodology, we calculated the differential pressure at the air core, as well as the tangential velocity at the boundary of the air core from the vortex principle in a confined geometry at different operating regimes. A series of experiments were conducted using Weir’s Cavex® hydrocylone where process variables—such as solids concentration and feed flowrates—were experimentally studied to determine the key classification parameters. For the validation of the current approach we used the same process variables to derive design parameters and compared them with the existing design. The current approach can provide insights towards the selection of design parameters and can be useful for mining industry professionals to optimize different operating parameters of hydrocyclones to achieve the best performance.

Feb 1, 2024

By Jon A. Hummer, MICHAEL R. SHAHAN, Aleksandar D. Bugarski, Shawn Vanderslice

Occupational exposures to respirable dust and submicrometer aerosols emitted by diesel-powered equipment are a health concern for underground mining operators and regulators. A study was conducted in an underground mine with the objective to identify, characterize and source apportion airborne aerosols at the setup face and recovery room during longwall move operations. 

By J. F. Brune, A. Verma

"Face ignitions in underground coal mines are a major risk for underground mining operations, as they can lead to methane or coal dust explosions. The 2010 disaster at the Upper Big Branch Mine resulted in 29 fatalities due to a methane and coal dust explosion initiated from a face ignition. Much research has been conducted to mitigate face ignition hazards, from water sprays to installing passive and active explosion barriers. Despite the increased use of water sprays in U.S. coal mines, there have been more than 50 documented face ignitions in the U.S. underground coal mines since 2010, indicating that this hazard still prevails. This paper will examine the statistics of face ignitions and gas explosion in U.S. coal mines based on MSHA data. It will study factors contributing to these face ignitions and outline best practices for their prevention based on experience and practices worldwide. INTRODUCTION Methane and coal dust explosions are one of the major causes of coal mine disasters in the U.S. and around the world. Such disasters have resulted in the large number of fatalities and loss of mine infrastructure. The recent explosion at the Soma coal mine in Turkey has caused the death of 301 miners (Mining Turkey, 2014). As documented by U.S. Mine Safety and Health Administration (MSHA, 2015a), the U.S. coal mining industry has also experienced several catastrophic mine explosions with accidents at Upper Big Branch mine, Darby mine, Sago mine and Jim Walter Resources No. 5 mine in the last decade, causing the deaths of almost 60 miners. Every explosion requires a source of ignition, the right amount of fuel and oxygen. In underground coal mines, methane acts as a fuel while ventilation air acts as a source of oxygen. The source of ignition may vary from spontaneous combustion, electrical equipment and switchgear, mechanical heat sources, face ignitions due to friction rock-on-rock or from cutter bits and lightning strikes. Under the right conditions, energy of less than 0.3 mJ is sufficient to ignite methane-air mixtures (James, 2007) that can result in a catastrophic explosion. Much research has been done to mitigate the methane explosion hazard by proper dilution, continuous monitoring of methane and elimination of ignition sources. Historical studies indicate that face ignitions are the major cause of explosion in underground coal mining operations worldwide (Belle, Carey, and Robertson, 2012). Statistics shows that most mine disasters were started from a small face ignition, which turned into a major explosion fueled by additional methane and coal dust (Belle et al., 2012). To investigate face ignition hazards, researchers must study potential ignition sources as well as potential explosive atmospheres near mechanical coal cutting operations. Statistical analysis of U.S. coal mine face ignitions reported by the U.S. Mine Safety and Health Administration (MSHA, 2015b) shows that several factors are responsible for face ignitions."

Jan 1, 2016

By R. Church

The southern Powder River Basin (PRB) of Wyoming has developed into the largest coal producing region in the United States in the relatively short time span of 22 years. Since the opening of the first non-captive mine in the Basin in October 1972, truck/shovel fleets have played a major part in this rapid growth. In 1994, more than 200 trucks and 50 shovels will be used at 14 mines to help produce more than 190 Mt (210 million st) of coal in the southern PRB. This article presents an overview of the truck/ shovel operations in the Basin. Fleet sizes are reviewed, applications discussed, operating considerations explored, factors looked at that drive high capacity and restrictions listed for future growth. Fleet size Various sizes of trucks and shovels can be found in the southern PRB. However, a clear trend of increasingly larger size units is being established as producers attempt to remain competitive and productive.

Jan 1, 1994

By M. Prasad, G. M. Rao, A. K. Majumder, T. C. Rao

Froth flotation was employed to beneficiate a lean-grade siliceous rock-phosphate ore containing fluorapatite, the phosphate-bearing mineral. The main gangue minerals were quartz, iron oxides and aluminum oxides. After the rougher stage, four cleaning stages were required to upgrade the ore. The liberation size of the phosphate mineral was below 200 mesh, The reagent scheme consisted of commercial-grade sodium silicate and sodium oleate. The effect of reagent dosages, number of cleaning stages and pulp density on the efficiences of separation were studied systematically. A flowsheet was proposed for the processing of low-grade siliceous phosphate ore containing 12.1% P2O5, 55.36% SiO2 and 15.45% CaO. The flowsheet provided a useable phosphate concentrate containing 34.18% P2O5 and 14.20% SiO2 with a P2O5 recovery of 70.4% (the weight yield was 25.0%).

Jan 1, 1999

By Rambabu Pothina, Rajive Ganguli

The economics of a mineral-processing circuit is dependent on the numerous sensors that are critical to optimization and control systems. When a sensor goes off calibration, it results in errors that can have a severe impact on plant economics. Classical statistical approaches fail to detect when errors are “subtle,” unless they grow and become large enough to be “gross,” whereas methods based on signal processing and artificial intelligence fail in dealing with the complexity of process fluctuations. Due to the sheer volume of sensors, undetected errors are not remedied until the next calibration, which on average are a year apart across all industries [1]. This research aims to detect such subtle errors (2 percent bias) in shorter time spans of about a month — rather than wait for errors to grow — using innovative data-mining techniques and algorithms.

By L. Yuan, R. A. Thomas

"Atmospheric monitoring systems (AMS) have been widely used in underground coal mines in the United States for the detection of fire in the belt entry and the monitoring of other ventilation-related parameters such as airflow velocity and methane concentration in specific mine locations. In addition to an AMS being able to detect a mine fire, the AMS data have the potential to provide fire characteristic information such as fire growth — in terms of heat release rate — and exact fire location. Such information is critical in making decisions regarding firefighting strategies, underground personnel evacuation and optimal escape routes. In this study, a methodology was developed to calculate the fire heat release rate using AMS sensor data for carbon monoxide concentration, carbon dioxide concentration and airflow velocity based on the theory of heat and species transfer in ventilation airflow. Full-scale mine fire experiments were then conducted in the Pittsburgh Mining Research Division’s Safety Research Coal Mine using an AMS with different fire sources. Sensor data collected from the experiments were used to calculate the heat release rates of the fires using this methodology. The calculated heat release rate was compared with the value determined from the mass loss rate of the combustible material using a digital load cell. The experimental results show that the heat release rate of a mine fire can be calculated using AMS sensor data with reasonable accuracy.IntroductionFires at different stages generate different gases and smoke toxicity hazards. When fires occur in underground mines, a significant amount of toxic gases and smoke enter the mine ventilation system and are carried throughout the mine ventilation network, increasing the hazard potential for personnel even if far away from the actual fire. Although fires that develop to the point of rapid flame spread pose imminent hazards, fires in their smoldering, pre-flaming stages can also contaminate the mine atmosphere with debilitating levels of smoke and toxic gases.The most important parameter for evaluating the fire hazard in mines is the heat release rate (HRR), which is directly related to the rate at which heat, smoke and toxic gases are produced and transported by the ventilation system and which provides an indication of the time available for escape or firefighting (Babrauskas and Peacock, 1992). The HRR is also an important input parameter to mine fire simulation models."

Jan 6, 2017

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By Jeremy Maurer, Duah Philip, Awuah-Offei Kwame, Donya Otarod

Land use impact assessment for mining is time- consuming and expensive. Because of mining’s impact on biodiversity, land use assessment methods that evaluate biodiversity are important for mining land use impact assessments. Remote sensing, in particular satellite multispectral sensing platforms such as Sentinel‑2 and the Landsat mission series, have been used to assess and quantify biodiversity through proxy variables such as NDVI (Peña-Lara et al., 2022). The objective of this paper is to present results of a comparative study of land use and biodiversity based on multispectral satellite observations and production data from copper and cobalt mining in the Democratic Republic of Congo. We quantify the relationship between different spectral bands and vegetative indices and the production data provided by the mining companies and measure correlations. The results suggest that remote sensing could be a cost- effective means of assessing biodiversity impacts of mining.

Feb 1, 2025

By A. W. Storm

Vertical shaft furnace design and operation have their roots deep in antiquity. There is substantial evidence to indicate that iron was reduced from its oxides to serve mankind's needs long before recorded civilization - - actually prior to 3500 B .C. For at least 5500 years man has been matching wits with Nature to find better methods of extracting this most common, yet essential, metal from her, grasp. And, during nearly all of this period, the vertical shaft furnace has played a principle role in this dramatic struggle.

Jan 1, 1962

By Brij M. Moudgil, Shoulian Zhu, J. L. Pinault

A new technique, prompt neutron activation probe (PNAP), for analyzing phosphate rock slurry in-situ was evaluated both in the laboratory and at the plant. The technique yielded a high precision in the analysis of Ca, Si and H using 252Cf source. Low accuracy of the direct measurement of P using 241Am/Be in the laboratory tests was attributed to the interference of rare earth elements present in the samples, particularly Gadolinium. No significant effect of variables such as solids loading, particle size distribution, and flotation reagents was observed on the probe performance. The probe can detect the compositional changes of the feed, tailings and the concentrate streams in the plant.

Jan 1, 1993

?Energy-related systems: wind, solar, electric are typically materials intensive. As new technologies are widely deployed, significant quantities of the elements required to manufacture them will be needed. However, many of these unfamiliar elements are not presently mined, refined or traded in large quantities, and, as a result, their availability might be constrained by many complex factors. A shortage of these ?energy-critical elements? could significantly inhibit the adoption of otherwise game-changing energy technologies. This, in turn, would limit the competitiveness of the U.S. industries and the domestic scientific enterprises and, eventually, diminish the quality of life in the US.? -Energy Critical Elements: Securing Materials for Emerging Technologies?- American Physical Society, 2011.

Jan 1, 2012

By Jan M. Mutmansky, David R. Kalasky

Computer simulation continues to be one of the most successful analytical applications of computers in the mining and mineral processing industries throughout the world. Through simulation, managers and engineers can explore the impact of new technologies, equipment designs, plans and operating strategies to improve their operations. It is not uncommon for a single simulation application to provide a quick payback of analysis expenses (within weeks or months) yielding long-term financial and operational dividends. The paper will present a summary of the types of software systems that are available for use on PCs and other computer systems. Support software for curve fitting, statistical analysis, and optimization of simulation models will also be presented. Methods of leveraging simulation efforts through networking and coupling of software systems will be discussed. Finally, the trends in simulation in the mineral industries will be analyzed. Areas of strength and weakness of simulation will be discussed along with the usefulness of commercial general-purpose and custom-writ- ten simulation packages. The future possibilities for simulation in the mineral industries will be outlined and predictions on trends for the future will be presented.

Jan 1, 1996

By Jean-Michel Rendu

Accurate modeling of the semivariogram is an extremely important step in the geostatistical analysis of mineral deposits. Automatic fitting of a mathematical model is often possible but not necessarily desirable. Significant geologic and statistical information must be taken into account in the fitting process, which is not always available to the computer. Manual fitting of the model is, on the other hand, extremely time consuming. Interactive graphics are best suited to optimize the process. A number of interactive methods are described, which are adapted to the modeling of semivariograms in one-, two-, or three-dimensional environments.

Jan 1, 1982

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By L. W. Swent

Dr. Emrick, honored guests, distinguished speakers, ladies and gentlemen, I am Langan Swent, Vice President for Environmental Affairs and Occupational Safety and Health, of Homestake Mining Company. Today, I appear on behalf of the American Mining Congress, as chairman of its uranium mine health subcommittee. The American Mining Congress is a trade association of several hundred members, which include the producers of a large proportion of the nation's uranium. I've been asked to make a statement of principles for the uranium industry. There are two types of principles that apply to industry in general, and specifically to the uranium industry. Some have external origins and apply regardless of what industry does or thinks. Others are generated by industry itself and serve as goals for the industry. I'll discuss some of each type. I'll limit my statement to those principles related to the subject of this conference--radiation hazards in mining. I won't take your time trying to explain some of the unrelated principles that we must all contend with, such as Parkinson's Laws, Murphy's Law, and the Peter Principle. First and foremost, industry has a sincere interest in the well-being and health of its employees. There are two basic reasons for this. One is a basic respect for human lives, especially those of people we see and work with every day. No one in management wants to carry the lifelong burden of blame for a life lost due to poor working conditions. Most uranium and other mining is done in small communities. Production workers, maintenance workers, service workers, shift bosses, foremen, superintendents and managers all live in the same community. They attend the same churches. They serve together in civic activities. Their children go to the same schools. If one employee in such a community loses his life due to poor working conditions, those remaining know in a daily and intimate way the resulting personal tragedy, usually of a bereaved widow and fatherless children. This sad experience makes the community, including industry management, intensely sensitive to the need for maintaining good working conditions in the mines. But what about the segment of industry that does not live in the mining communities? Corporate and owner's offices are frequently hundreds of miles from the communities where the mining takes place. Many of these people are not personally acquainted with the workers, and there are few close personal ties between the two communities. The distant staff are, however, still human beings and motivated by the same basic human respect for life. Mr. Manuel Gomez of MSHA and a member of the planning committee for this conference summed this point up expressively when he told me: "No one group has a corner on compassion." In addition to compassion, there is another factor. In both communities the basic assignment to everyone is to produce profits. In carrying out this assignment, supervisory and management people are acutely aware of the high cost of illnesses and accidents. Their objective of maximizing profits is advanced significantly by minimizing illnesses and accidents at the mines. A business that has illnesses and accidents generally suffers from poor employee morale and high employee turnover, both of which detract from profits. Next, I would like to talk about what industry has done in the field that is the subject of this conference. We have worked at all sorts of methods to reduce exposure of employees since the exposure standards were first introduced and then lowered. Other speakers will go into details of technology, and I'll simply comment on exposure results. These are best shown in Table 1. The table shows the average WL to which miners in U.S. underground uranium mines have been exposed since 1937 through 1980. The trend of decreasing radon daughter concentrations throughout the period is obvious. Figure 1 presents this data graphically and shows the trend at a glance. This record begins in 1937 when uranium, as such, really wasn't being mined or sought. The concentrations given by the U.S. Public Health Service were for a few small vanadium mines which carried uranium as a by-product. A few years later, when the Manhattan project to develop the atomic bomb was begun, these mines became the first U.S. uranium mines and the vanadium became the by-product! The radiation hazard then also received attention and the average concentrations began to decline. As knowledge of the reality of the hazard spread, conditions improved. The search for uranium in the U.S. turned up new and larger ore bodies that had to be mined by large underground mines. These mines involved ventilation planning from the beginning, and when they came into production in the late 1950's they lowered the average concentrations greatly. Then in 1960 the American Standards Association adopted a standard setting 1 working level as a satisfactory condition, and several action levels up to 10WL, at which point removal of people from exposure was called for. As a result of the uranium producing states governors' conference in December 1960, state mine inspection agencies, in the early 1960's, began to adopt and enforce the ASA standards. As a result, average concentrations again declined. In 1967, the Federal Radiation Council recommended an annual limitation of 12 WLM per individual. This represented a great change in the methods of

Jan 1, 1981

By Mark E. Gershon

A mixed-integer formulation of the mine scheduling problem is discussed and applied for the purpose of optimizing both the mine production sequencing and the mill blending and processing problems simultaneously. Previous attempts at solving these problems separately, although successful, fail to take into account the interrelationships between these problems. Project structure serves as the outline of this paper, which is directed towards a mining engineering audience. Generalized in its organization, this concept is useful for long, intermediate and short range scheduling. Actual applications are mentioned which show that the concept is also applicable to mining a variety of ores.

Jan 1, 1982

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. 

In the late 1980s and into the 1990s, the Mountain Pass Mine in California produced about 40 percent of the world?s rare earth elements. At the height of this production, the facility produced up to 54 L/s (850 gpm) of saltwater that was piped to offshore holding ponds where the water was evaporated. In 1998, following a series of waste water pipeline breaches, separations activities were suspended, reducing the Mountain Pass site to just the openpit mine and mill. The environmental concerns were addressed and the affected areas have since been remediated. However, in the years following the breaches, 97 percent of the world?s production of rare earth elements moved to China. By 2011, Molycorp, and the Mountain Pass Mine, had rebounded from the difficult times and were once again in a position to become a significant player in the rare earth industry.

Jan 1, 2011

By BHAMIDIPATI S. SASTRY, SRIVATSAN J. SRIDHARAN, ANMAYA NAIK, ASIF AHMAD, ADITYA PANDEY

Wet kata cooling power (WKCP) measured using a kata thermometer is a well-known heat stress index in mining industries. Although over the years several researchers have proposed different heat indices and indicated the limitations of the kata thermometer, it is still being used in many areas, especially in the South African gold mining industry, mainly because of its simplicity and rapidity of assessment. This paper presents a comparative analysis of the newly developed empirical expression for WKCP, and some of the more prevalent empirical expressions. The analysis presented based on a regression technique aims to assess the disagreement between model predictions and actual measurements. It is found that the WKCP expresses bioclimatic interaction quite well under the specific parameter of interaction that explains the harsh thermal environment and air condition, such as metabolic activity, the person’s clothing, and the velocity of the air in which the person is working. The statistical analysis shows that the WKCP exhibits significant estimates to thermal stress under lower air velocities, light clothing, and higher metabolic activity rates.