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By G. Frey, D. Scott, C. Pritchard

Controlled recirculation has been used in the metal/nonmetal mining industry for energy savings when heating and cooling air, in undersea mining and for increasing airflow to mining areas. For safe and effective use of controlled district recirculation, adequate airflow to dilute contaminants must exist prior to implementation, ventilation circuit parameters must be accurately quantified, ventilation network modeling must be up to date, emergency planning scenarios must be performed and effective monitoring and control systems must be installed and used. Safety and health issues that must be considered and may be improved through the use of controlled district recirculation include blasting fumes, dust, diesel emissions, radon and contaminants from mine fires. Controlled recirculation methods are expected to become more widely used as mines reach greater working depths, requiring that these health and safety issues be well understood. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted two controlled recirculation tests over three days at a Wyoming trona mine, utilizing an inline booster fan to improve airflow to a remote and difficult-to-ventilate development section. Test results were used to determine the effect that recirculation had on air qualities and quantities measured in that section and in other adjacent areas. Pre-test conditions, including ventilation quantities and pressures, were modeled using VnetPC. During each test, ventilation quantities and pressures were measured, as well as levels of total dust. Sulfur hexafluoride (SF6) tracer gas was used to simulate a mine contaminant to monitor recirculation wave cycles. Results showed good correlation between the model results and measured values for airflows, pressure differentials, tracer gas arrival times, mine gasses and dust levels.

Jan 1, 2013

By Chee Theng

The Mineral & Metallurgical Processing Division (MPD) of the Society for Mining, Metallurgy & Exploration held the 13th MPD Student Poster Contest on March 1, 2023, during the MINEXCHANGE 2023 SME Annual Conference & Expo. The event showcased the work of 24 graduate and undergraduate students from U.S. and international institutions. The contest began in January when the students submitted one‐page abstracts for judging. In February, they prepared and presented posters that explained their research, and each student had five minutes to showcase their research to a panel of judges during the conference. In recognition of their efforts, the MPD provides monetary rewards to all participants. For graduate students, first place receives $1,000, second place $500, and third through seventh places $200 each, and for undergraduate students, first place receives $1,000 and second place $500. The main authors of nonplacing entries receive $125 each. Participation in the contest also includes a free ticket to the MPD Luncheon, where the winners are announced.

Nov 28, 2023

By Charles G. Zink

Anthracite is widely known as a domestic or space heating fuel. The prevailing market ratio of domestic to industrial consumption was about 80 to 20 up until 1950. Since then it has been shifting until now the ratio index is about 50/50, exclusive of overseas export. Despite a declining domestic space heating market, the demand for industrial anthracite remains good. However, as a result of stringent air pollution regulations, there is a renewed interest in this low sulphur coal which cannot smoke under any conditions. Anthracite serves other important industries such as power generating, metallurgical, cement, ceramic, chemical, water sewage and industrial wastes filtration. Anthracite is an excellent natural source of carbon and may be utilized in many processes.

Jan 1, 1966

By J. F. T. Agapito

The load carrying capacity of oil shale pillars excavated by conventional blasting, presplit blasting, and mechanical mining is evaluated. The study was based on a comparison of in-situ vertical stresses and fractures obtained from overcoring horizontal holes in the Colony Mine, Piceance Creek Basin, Colorado. Results indicate that conventional blasting causes a zone of damage approximately 3 m (10 ft) thick with low stress distributions. Presplit blasting reduces damage significantly, and increases the load carrying capacity in the 3 m (10 ft) thick zone by 5.93 MPa (860 psi). Mechanical mining causes little or no rock damage, and an increase of 9.83 MPa (1425 psi) in strength in the same 3 m (10 ft) thick zone. An example of pillar design is given showing that the use of presplit blasting and mechanical mining techniques can increase the extraction ratio by at least three and five percent, respectively, as compared to conventional blasting. It is speculated that comparable increases in extraction should also occur due to increases in span dimensions.

Jan 1, 1984

By Amila Sandaruwan Ratnayake, T. Dilmi. U. Wijewardhana, H. C. S. Subasinghe

The value addition potential of ilmenite was examined using several characterization techniques. Raw ilmenite is composed of 93.65 wt.% of FeOTiO2, 3.55 wt.% of SiO2, 1.22 wt.% of Al2O3, and the remainder being other minor oxides. Ilmenite and powdered carbonized coconut shells were mixed in the weight ratio of 4:1. A separate fraction of the same mixture was added with powdered seashells in the weight ratio of 4:1:0.5. Six fractions of each mixture were distinctly milled from 1 to 6 h in a planetary ball mill. XRD spectra (broadened and diminished reflections of ilmenite) and FTIR observations (Ti―O―Cbonding) of milled samples indicate the possible incorporation of carbon into the ilmenite structure. Any clues of an occurrence of new rutile peaks were not observed in XRD spectra of milled samples. Consequently, the carbothermic reduction has not been initiated during mechanical activation. In this case, samples powdered for 6 h in a mill were isothermally annealed for 2 h under normal airflow at temperatures of 800 °C, 1000 °C, and 1200 °C, respectively. According to the X-ray diffractograms, the annealing temperatures of 1000 °C and 1200 °C exhibited almost similar trends with rutile (R), pseudobrookite (PB) and elemental iron (F), and a very few ilmenite (I) peaks. Consequently, 6 h of milling and 1000 °C annealing were concluded as the optimum conditions for the carbothermic reduction. Moreover, this study indicated seashells as a potential rate raiser for the carbothermic reduction of ilmenite at 800 °C. Therefore, this process is applicable to upgrade ilmenite into a mixture of synthetic rutile and elemental iron.

Mar 29, 2021

By Long An, Chao Wu, Yuanhui Li, Xing Sun, Shuai Xu, Changyu Jin

Stage open stope mining (SOSM) maintains the stability of excavation openings by leaving a large number of rib pillars. Affected by the strong unloading due to stage mining and the low width-to-height (w/h) ratio of the pillars remaining, largescale destabilization disasters of rib pillars or excavation openings easily occur when the distribution of ground stress or the size of rib pillars is unreasonable. In view of these problems, a physical SOSM model test was carried out based on an underground metal mine in Chifeng City, China, revealing the deformation and failure characteristics of the SOSM pillar group by overloading. The physical model test results of SOSM and room-and-pillar mining (RPM) with a weak pillar were compared, and the failure process of the SOSM pillar group showed the characteristics of rapid and severe damage. The strength difference between a weak pillar and the adjacent pillars enhanced the stress rebalancing effect and extended the failure process of the pillar group. Similar to the SOSM pillar group with a low w/h ratio, some high-strength pillars can be used to avoid large-scale destabilization disasters caused by the synchronous failure of pillars.

Mar 8, 2023

By B. J. Scheiner

The Bureau of Mines, U. S. Department of the Interior, is conducting research on a dewatering technique for fine particles generated during the mineral beneficiation process that will recover a portion of the water now being lost using conventional waste disposal methods and significantly reduce the time required for land reclamation. The technique utilizes a flocculant, polyethylene oxide (PEO), that forms strong stable flocs that can be dewatered rapidly on static and/or rotary screens. In field tests, phosphate clay waste has been dewatered from a nominal 2.5 percent solids to greater than 20 percent solids. In other field tests, coal-clay waste has been dewatered from a nominal 3 percent solids to greater than 55 percent solids, in addition, small-scale continuous tests have shown that bentonitic clays can be dewatered from 12 percent solids to 40 percent solids.

Jan 1, 1983

By Paavo Eerola

In May of 1984, it was decided that Outokumpu Oy would design and build a new nickel flotation mill to process ore from the newly discovered Enonkoski mine in eastern Finland. Since there hart peen a number of successful process charges in the existing mills, the design effort included the study and incorporation of several new developments, including all-autogenous grinding, "flash flotation", lane cell roughing, large cell cleaning and a computer-based, profit optimizing, process control system. The paper discusses the background and results of those studies, and a description of the resulting mill which will begin production in 1986.

Jan 1, 1985

By Frank Pollard

The Australian coal industry over recent years has experienced the situation whereby exploration and mine development are moving into geographical areas where the coal seams have never been mined to any extent in the past, if at all, and particularly where there is no history of experience in preparation of these seams. Additionally, the demands have been such that the development of a mine up to production stage should proceed with minimum delay. This is a situation which is of some importance and concern, in view of the coal quality requirements now experienced within world markets which can only be met, in most cases, by careful preparation. Costs are such that the preparation plant should operate as required by the situation and with maximum efficiency, which means that laboratoty information of breakage and washability characteristics which are required for preparation plant design should be accurate and available as soon as possible, even to a certain extent during the progress of the exploration.

Jan 1, 1981

By Subhash Bhagwat

The definition of high sulfur coal varies from plant to plant and is subject to changes over time as the environmental regulations change. In plants constructed after September 1978 hardly any domestic coal can currently be burned without the use of Flue Gas Desulfurization (FGD) because a 70 percent reduction in potential S02 emission is mandatory even when the potential emission is less than 0.6 lbs. S02/106 Btu heat input. On the other hand older power plants may in many cases be legally emitting up to 6 lbs. S02/106 Btu or more under some State Implementation Plans (SIP). The Clean Air Act requires, however, that in the long run all stationary sources of S02 pollution must abide by the ceiling of 1.2 lbs S02/10 Btu heat input.. Coals with a potential to exceed this limit must, therefore, be considered as high sulfur coals. Such a definition would be unrealistic because many SIP's aim at an emission level of 1.8 to 2.0 lbs. SO2/106 Btu for existing plants and a stricter limit does not appear to be enforceable in the next 5 to 10 years. As a result, coals with an emission potential of greater than 2.0 lbs of S02 per 10 Btu heat input are considered high sulfur coals for the purpose of this investigation. Based on this definition and the 1984 actual consumption of coals by U.S. electric utilities (table 1) only 7 out of the 24 coal producing states could be categorized as low sulfur states. The actual S02 pollution, however, depends on total tonnage of a type of coal as well as the sulfur content of the coal. Table 1 also indicates that only 6 states--Kentucky, Illinois, West Virginia, Ohio, Pennsylvania and Indiana-account for nearly 77 percent of S02 pollution potential in the United States. These 6 states have therefore been chosen for this investigation.

Jan 1, 1986

By İlknur Erol

The abstract highlights that hearing loss is an occupational disease caused by noise exposure in the workplace. The study investigates noise-induced hearing loss among miners in underground coal mines in Turkey, considering factors like occupation, age, and exposure time. The research employs logistic regression analysis to reveal the relationship between hearing loss and these factors. The findings suggest that occupational groups and duration of noise exposure significantly affect hearing loss. Miners in production groups and those exposed to noise for 10-14 years have a higher risk. The study concludes that age does not significantly increase the probability of hearing loss.

Mar 24, 2022

By Henry E. Swanson

In the early 1960's the Company, then named the United States Smelting Refining and Mining Company, was drilling the Continental ore body located near Fierro, New Mexico. Reserves of underground ore of sufficient quantity were indicated to build a mill. At the same time some ore from the Continental No. 1 mine was being milled at the Company's Bullfrog Mill, formerly a lead-zinc mill. The copper ore in comparison to the lead-zinc ores was very hard, abrasive, and heavy. These factors pointed out the possibility and attractiveness of autogenous grinding. While prior to this some study had been given to autogenous grinding, no large scale tests had been made. Such a program was carried out and from the pilot plant data the following was established: 1. Grinding of the ore by autogenous means could be accomplished. 2. This could be done in one stage; however, not at a satisfactory tonnage throughput rate. Thus, the use of a secondary unit has been employed. 3. Grinding in the secondary unit could be done by pebbles generated in the primary unit. This resulted in the scheme whereby the ore would be ground 100% autogenously. 4. Liberation of the copper minerals was excellent so that good recovery at a satisfactory concentrate grade would be obtainable.

Jan 1, 1976

By W. W. Mason

The United States began exporting coal in the late 1800'5, at first in very small quantities to Canada and beginning in 1897 and 1896, to the east coast of South America. Shipments to European countries began on a very limited basis in 1902 and these shipments increased gradually until World War One when shipments overseas increased from the 8 million tons per year level to 22 million tons. After the war exports dropped as fast as they had increased and, with the exception of exports to Canada, remained at very low levels until just after World War 11 when the United States again emerged as a major coal exporter. World War II left the coal industries of Europe in ruin. As the United States was the only country able to supply the large quantities of coal at reasonable prices needed for reconstruction of the European economy, the U. S. coal exports overseas expanded rapidly to 42.5 million tons in 1947. Additionally, we shipped 25 -2 million tons of coal to Canada In that year for a total export of 68.7 million tons. Unfortunately, that level was not reached again until 1957 when exports reached an all-time high of 76 .4 million tons- -a high I might add that has not been reached since.

Jan 1, 1980

By J. A. Delgadillo, C. A. Pérez-Alonso

"Tumbling mills using balls as grinding media are used extensively in the mining and cement industries to produce fine powders; however, it is well known that the process of size reduction is highly energy-intensive. For this reason, much of today’s comminution research is aimed at understanding grinding mechanisms, by estimating power draft and modeling milling circuits using the discrete element method (DEM). DEM predicts individual particle trajectories, the distribution of energy and contact forces at each collision, lifter wear and power draw. This paper presents a prediction of the discharge particle size distribution using three components, mass balance model (sometimes referred to as a population balance model, PBM), impact energy distribution of the mill obtained from the simulation of the charge motion using DEM and breakage characteristics of particles determined from drop-ball tests. DEM simulation of the charge of a tumbling mill was done using the code MinProSim 1.0 to obtain impact spectra at different operative conditions. Then, the population balance model (PBM), based on impact energy distribution, was used to predict the final particle size distribution in a batch mill and compared with experimental data. It is demonstrated that the DEM-PBM approach allows a reliable solution to predict particle size distribution for tumbling mills. Ideally, the model has to predict size distribution for any operational condition and feed characteristic; however, it has been shown that predictions include some degree of error.IntroductionThe discrete element method (DEM) has recently become a powerful numerical tool that can be used to investigate internal mill charge in ball mills. The early work of Cundall and Strack (1979) used DEM to analyze soil as a discrete medium. Later, the method was improved to simulate the operation of tumbling mills and optimize the design in order to increase the efficiency of energy utilization. Also, it is of great interest to relate ore breakage based on impact energy spectra obtained by DEM simulations and the breakage distribution function used in the PBM to predict particle size distribution in tumbling mills.King and Borgeous (1993) broke single particles in an ultra fast impact load cell to compute the phenomenological parameters in a microscopically more detailed population balance model. Kapur et al. (1997) simulated the size spectra of progeny particles produced by impact grinding as a function of the impact energy. Narayanan (1987), Narayanan and Whiten (1988) and Lira and Kavetsky (1990) estimated the energy-dependent breakage distribution function for scaleup and modeling of industrial ball mills."

Jan 1, 2015

By Abhilash, S. Sarkar, T. Venugopalan, P. Meshram

"To explore blast furnace slag as a secondary resource for rare earth elements (REEs), blast furnace slag containing lanthanum (La), cerium (Ce), erbium (Er) and neodymium (Nd) in concentrations of 17, 16, 4 and 44 ppm, respectively, was processed with sulfuric acid while optimizing the parameters of acid concentration, temperature and pulp density. The experiments showed that recovery rates of 92, 36, 35 and 52 percent for La, Ce, Nd and Er, respectively, were achieved at 1 to 5 weight/volume (w/v) percent pulp density using particles smaller than 250 µm and treating with 1 M sulfuric acid for one hour at room temperature. Raising the temperature to 95 °C promoted the dissolutions of Ce and Nd to 89 and 84 percent, respectively, for the same 1 M acid concentration and one-hour duration at 5 w/v percent pulp density. Cyanex 923 was preferred over Cyanex 301 for the purification of REEs from leach liquor. In another route, the leach liquor was subjected to precipitation with 0.5 to 1 M oxalic acid, resulting in a product with 4 to 5 percent concentration of REEs.IntroductionRare earth elements (REEs) are important materials in numerous high-technology applications, but they have high supply risk, giving rise to the study of new sources. The recycling of REEs has been well researched, especially on a small scale, but has not been widely implemented. Less than 1 percent of REEs were recycled in 2011 (Binnemans et al., 2013). REEs occur in a large number of minerals in oxidic compounds, such as oxides, carbonates, phosphates and silicates, and are present as mixtures at 10 to 300 mg/kg concentrations in many rock formations, such as basalts, granites, gneisses, shales and silicate rocks. The most abundant REE in the Earth’s crust is cerium (Ce), at a concentration of 20 to 70 mg/kg, followed by neodymium (Nd) and lanthanum (La), with heavier REEs being less abundant (Binnemans et al., 2013). REEs occur in nature in their oxidized forms in salts and minerals due to their electropositive nature and high affinity for oxygen. The possibility of recovering REEs"

Jan 1, 2017

By A. F. Peterson

There is no single mining problem at Benson that does not exist at some other mine. There are four, however, that require special attention primarily because they occur together and have an influence on each other. These are the nature of the mineral occurrence, the shape of the ore body, the operating schedule, and the climate. It is the purpose of this paper to describe mining practices in relation to these four factors. Iron ore was first noticed in the Star Lake area early in the nineteenth century. Prior to Jones and Laughlin leasing the facilities built by the Defence Plant Corporation, several companies tried to mine the ore body but gave it up as uneconomical. While there is a little high grade (40%) magnetite, most of the ore contains 20 to 25% iron and not enough was known prior to World War II to design a profitable operation. By 1943, and certainly in the years that followed, technological developments in ore dressing and mining not only put the magnetite into the category of a commercial ore, but made possible the concentration of the non-magnetic iron mineral, martite. This last development nearly doubled the ore reserve. Jones and Laughlin bought the DPC holdings in 1946 and has since expanded the plant to its present capacity of 4,400 gross tons of concentrates daily or 1,600,000 gross tons per year. Magnetite makes up 62% of this production at the present time, but it will be necessary before long to bring martite production up to about 45% of the total because of the ratio of the two ores in the reserves. To keep the plant supplied, 14,000 to 15,000 tons must be mined and crushed daily, with a ratio of concentration that varies from 2.8 to 3.4. The ore body is 12,000 feet long and varies in width from 600 to 1,500 feet. The waste rock is, for the most part, a granite gneiss, and the overburden, of which little is left, is a glacial drift sand. For the entire reserve, there is a half ton of rock for every ton of concentrate, but the stripping ratio is more than one to one at present because of the existence of more rock in the upper mining levels in relation to the ore. The dirt stripping or development work that cannot be handled by company facilities is contracted to an outside firm. The need for this diminishes every year and will soon disappear. The deposit looks like a "J" in plan, with the long leg running approximately north and south and the short leg to the west. The primary crushing plant, consisting of a 54" gyratory followed by two 18" gyratories and a 1,500 foot conveyor belt to the fine crushers, is located on the third level where the long and short leg of the mine meet. The widest part of the pit lies just the north of the crusher. The mine is operated on a lease that expires in 199l0 There are two fee owners, the Benson Iron Company, which owns slightly overhlf of the reserves, and the Newton Falls Paper Company, which owns the balance. There is no appreciable difference in the mining on the two fees, so the ore is removed in strict proportion to calculated reserves during each year. Basic mining equipment consists of eight 45 yard electric shovels, a fleet of twenty-five 22 ton end dump trucks, eleven churn drills for nine inch blast holes, and two small percussion drills for four to five inch holes, There are the normal auxiliary items, such as dozers, graders, wagon drills, and two drop-ball cranes. Power is purchased and, where practical, is used at 4100 volts. Pit drainage pumps can handle a maximum of 11,500 GPM from the several sumps, but water is a problem only during the spring or when a sudden thaw follows a heavy snowfall.

Jan 1, 1958

By Thomas S. Nye

Mineral exploration in the United States relies heavily on theoretical geologic concepts and indirect methods such as geophysics and geochemical prospecting, as there are few exposed areas of mineralization which have not already been explored at least once. In Mexico ore-grade samples can be cut at the surface on vein, replacement, and disseminated types of deposits in many areas. Here the problem is not in finding a mineralized area but in deciding which mineralized area can be explored and developed at the least risk and cost, and have the greatest profit potential, within the framework of Mexican mineral economics and government policies. Mexico's min¬eral industry is regulated through a system of permits for various phases of mineral exploitation, and by taxes. This regulation and its effects are not unlike those which may be expected in the United States if present legislative and administrative trends continue.

Jan 1, 1972

By S. S. Huyett

The opportunity to cooperate with the Mining Department of the Pennsylvania State University in their Student-Trainee Program is accepted by The New Jersey Zinc Company who believes that the participation in this type of a program will lead to a larger supply of high calibre engineers in mining. Trainees compete with other employees to earn the cost of their education while gaining practical experience in the mining industry. The practical experience is arranged to complement the technical education through a variety of work assignments. Job opportunities for the trainee are related to the work requirements of the Company and to the performance of the trainee. Management must consider and deal with a good many problems uncommon with regular, full 'time employees. For a number of reasons this program is recommended to other companies as a means to encourage outstanding young men who are interested in a career in the mineral industry to obtain a professiona1 education.

Jan 1, 1963

By Duncan M. Lamb

Commercial computer "time-sharing" is a new and powerful tool for the engineer. It is a system of virtually simultaneous use of a digital computer by several individuals. Access to the computer is by means of a conventional teletypewriter which transmits over the regular telephone lines to the computer which may be located any distance from the user. Complex or repetitive computations can be programmed and the speed of computation is many times that which one can do with slide rule and desk calculator. The availability of such a commercial computer "time-sharing" system offered an opportunity to transform a tedious and time-consuming task into one that requires only a few minutes. Until the work of F. C. Bond produced widely accepted mathematical statements concerning the performance of grinding mills, the selection of the proper size equipment was done by comparison with similar operating equipment. Allis-Chalmers systematized Bond's work in a bulletin published in 1963 but the calculations are laborious and the final mill selection still required comparison of the calculated power draw with the power requirements listed in equipment catalogs. This was, however, a step forward from previous procedures. This paper discusses a rapid and simple method of determining the size and power requirement of overflow ball mills. A shared-time computer program has been developed which rapidly calculates and displays the physical dimensions, power requirements, grinding media size and quantity, as well as the important correction factors used. All of these data are calculated from input information which is usually available.

Jan 1, 1969

By George F. Swindle

This paper discusses a composite of two coal reserve studies, each of which made use of a computer-based modeling system to assist in an evaluation of multi-seam deposits. The model permitted simultaneous consideration of seam thickness, seam structure, overburden thickness, over-burden ratio, and quality parameters for sulphur content, ash content, BTU values and the EPA Compliance index. The model is designed for use by a non-programmer, geologist or mining engineer. It enables the user, from a computer terminal in his office, to specify constraints (for example maximum um sulphur and maximum- ash content, minimum seam thickness and minimum BTU rating), and produces a report showing the volume, quality and location of that part of the total in place deposit satisfying all the constraints.

Jan 1, 1983