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By P. O. Ripley

Into this tumultuous twentieth century, every second, two new babies are born. This is 5,412 per hour, and 130,000 per day. Relentlessly, consistently, alarmingly, they add to the more than three billion human beings who already inhabit the earth. Every tick of tier clock brings with it a problem child, the problem of another mouth to feed, another body to clothe, another human being for whom to provide. On the other hand, medical science has achieved a postponement of death, considerably past the period of a few years ago. Thus, life expectancy has been increased and world population has increased accordingly. Darwin (4) writing in 1962, suggests "It is curious how long the world is taking to perceive that we are living in what is a fantastically abnormal period of history, and one which must inevitably end soon, The first warning note of a possible population explosion was given by Malthus in 1799". He suggested that population increases geometrical while production increases only arithmetically and that soon we would not be able to feed the rapidly increasing population.

Jan 1, 1966

By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

By M. L. Bricker

The Jim Bridger Mine is operated by Bridger Coal Company and is located in Sweetwater County, 35 miles (56 km) northeast of Rock Springs, Wyoming (USA). The general location of the mine site is shown on Figure 1. Bridger Coal is a joint venture of NERCO Coal Corp, the operator, and Idaho Energy Resources Company. The permit boundary encompasses in excess of 20,000 acres (81 km2) and is nestled against the western side of the Continental Divide. Production started on July 3, 1974, and the mine has produced approximately 90 million tons (82 million t) while moving approximately 450 million cubic yards (344 million m3) of virgin earth. Annual production averages 5 to 7 million tons (4.5 to 6.4 million t) of run-of-mine coal. Coal is consumed on site by the Jim Bridger Power Plant, a 2,000-megawatt generating station, and the electricity is transmitted to the Pacific Northwest power grid (Oregon, Idaho, Northern California, etc.).

Jan 1, 1991

By Y. Luo

Although considerable progress has been made in the last decade in predicting surface subsidence over longwall panels, a number of important issues deserve further studies in order to improve the techniques and accuracy of subsidence predictions. Some of the problems are: (1) subsidence over the chain pillars between mined longwall panels; (2) subsidence development process after face stop due to either a vacation or the completion of a longwall panel; and (3) subsidence initiation and development process over the setup entry area in the initial stage of mining a longwall panel. In this paper, the measured data related to the targeted problems are presented, the data analysis techniques are briefly introduced, and some of the prediction methods developed based on the collected data are proposed. The proposed methods can be used as supplemental tools for the existing subsidence prediction models to improve their prediction accuracy.

Jan 1, 1991

By P. Nelson, R. O’Connell, J. Rostami

Tunnel boring machine (TBM) system utilization is a critical factor for predicting machine performance. The process of estimating machine performance, including rate of penetration (ROP) and machine utilization (U) must incorporate an understanding of site geology, TBM specifications and site management. The study herein presents a preliminary analysis of the different activity time and downtime components from hard rock TBMs at two project sites to evaluate their impact on machine utilization. A comparison of crew experience, first between shifts and then between projects is included to analyze its effect on utilization and downtime. This work presents the sensitivity of the utilization factor to selected activities in the projects and the impact of geology and site set-up/logistics on machine performance.

Jun 13, 2021

By D. G. Chedgy

Environmental improvement efforts are focusing with increasing intensity on pollutants resulting from combustion. The high cost of removing these pollutants at the power station is well documented. Physical coal cleaning has always been and should remain the most economic method of reducing sulfur oxide emission from coal combustion. It is critical in the selection of preparation plant circuitry to consider capital and operating costs, as well as the level of sulfur reduction. This paper describes the technical criteria which must be used for efficient process selection and summarizes the cleaning systems available or in development.

Jan 1, 1990

By S. A. Beeson, C. Poole

This paper describes the development of a novel selective flocculation technique for recovering phosphate values from ores containing silicate or carbonate gangue minerals. Data from initial flocculation response and reagent adsorption studies on component mineral suspensions and synthetic mixtures were used to assess the influence of various process parameters (e.g., reagent dosages, particle size, solids concentration, and conditioning regimes) on single-stage selective flocculation tests involving natural silicate and carbonate ores. In these tests a high degree of selectivity was achieved using low dosages of a low-molecular-weight cationic dispersant and a mid-range molecular weight cationic flocculant. Testwork was then extended to the evaluation of several floc recovery systems (sedimentation, hydrocyclones, and floc flotation) in a multi-stage process involving redispersion and reflocculation. Results from these tests clearly demonstrated the feasibility of producing marketable phosphate concentrates from both ore types.

Jan 1, 1999

The value of US industrial mineral output last year was $20 billion, a 12% decline from 1981. A glance at the accompanying table and a review of the comments made by several contributors reveals how poorly many industrial minerals fared during 1982. Bromine and peat posted a 6% increase in production while recovered sulfur showed only a 3% gain over 1981. Pumice, salt, and dimension stone managed to stay more or less even with 1981 production. However, most industrial minerals posted losses for the year from 3% for vermiculite, sodium carbonate, and gypsum to 49% for ilmenite. Naturally, the depressed economy is to blame for decreased production and consumption. Low steel and auto production, lower housing starts, and many other factors impacted the industrial mineral industries. Hopefully the worst is over. Interest rates are down, energy costs are decreasing, the automobile and housing industries show signs of picking up. Perhaps the 1983 annual review will be less gloomy. Many thanks to these industrial minerals technical committee members for their contribution to this year's annual review: G. S. Austin, E. S. Montgomery, H. P. Ehrlinger III, D. B. Jorgensen, R. L. Parratt, J. F. Burst, W. Mallory, N. C. Trivedi, and N. K. Olson.

Jan 5, 1983

By M. S. Celik

Despite its importance in various diverse industries, research on beneficiation strategies of boron minerals has not received enough attention. Boron minerals are primarily upgraded by wet processing methods. However, severe environmental constrains have accelerated the development of dry processing techniques such as calcination. Interestingly, boron minerals, colemanite, ulexite and borax undergo respectively decrepitation (fragmentation), shrinkage and expansion upon heat treatment. Each mineral then requires a different beneficiation scheme. In this study, laboratory and pilot plant studies on calcination of boron minerals conducted in our laboratories are reviewed along with their implications in commercial operations.

Jan 1, 1997

By T. M. Klemetti, T. J. Batchler, T. J. Matthews

How representative are partial-panel screen tests of the in situ response of screen to roof and rib deterioration and displacements? Can a more representative procedure that tests up to two full screen panels improve the utilization and effectiveness of screen as a roof and rib support? This paper details a new full-panel screen test procedure and the initial results. The full-panel test frame was designed to test a 2.4 by 3.6-meter screened area with bolt spacing as small as 0.3-meter increments. The initial design included up to 6 screen pull points, but additional locations can be added to produce a more uniform loading. The test frame was developed to capitalize on the capabilities of the Mine Roof Simulator (MRS) at the Pittsburgh Mining Research Division (PMRD) of the National Institute for Occupational Safety and Health (NIOSH). The initial tests included a baseline test of a partial panel (1.22 by 1.22-m screen section) using the original 1.52 by 1.52-meter test frame, a 1.22 by 1.22-meter screen section test in the new full-panel test frame, and two tests of 2.4 by 3.6-meter screened area in the full-panel test frame. The 1.22 by 1.22-meter screen section tests in the full-panel test frame produced a peak load 6% higher and a yield load 30% lower than the partial-panel (original) test frame. The multiple pull points of the full-panel frame produced variable yield, peak, and intermediate loads, but on average were lower than the single pull-point tests. INTRODUCTION Roof and rib surface support has become a major component of the stability and safety of underground coal openings in the past 15 years. The use of screen, either metal or synthetic, has proven to decrease the injuries of underground coal miners. By 2005, there were 466 injuries in the United States caused by roof skin failures, with numerous mines not employing roof screen. In contrast, in 2015 there were 175 injuries caused by roof skin failures, with at least some of the reduction due to the increased use of roof screen. A continued effort to increase the utilization of screen in areas of underground coal mines where workers are traveling and working can reduce these injuries even further. To aid in this effort, the testing of various screen types under various loading and attachment conditions is required. Past testing efforts have primarily consisted of partial-panel testing in a laboratory setting. Laboratory testing of roof screen, both metal and composite, has been conducted in several ways by researchers, manufacturers, and other entities. The primary focus on the testing has been evaluating weld integrity of 1.22 by 1.22-meter screen section tests of various screen types utilized in mining (Dolinar, 2006; Dolinar, 2009; Tannant, 2001). There have also been several efforts at numerical simulation of the screen and screen/rock interactions (Murali et al., 2006; Shan et al., 2014). A few full-panel tests were performed with one pull or loading point in the center of the screen panel (Shan et al., 2014). As most previous efforts have mentioned, the only true way to evaluate the capabilities of screen is to conduct full-panel testing. Single wire strand, weld, and partial-panel (1.22 x 1.22-m) tests as well as numerical modeling only provide insight into the actual response of full-panel screen. A new test frame and procedure have been developed at PMRD to conduct various loading, anchoring, and material testing.

Jan 1, 2019

By S. P. Mehrotra

In this review article, various approaches and mathematical models that have been used to simulate, design, and synthesize flotation circuits are examined. First, a brief review of flotation kinetics is presented which is followed by a discussion on simulation of flotation circuits. The existing literature on optimal design of flotation circuits has been divided into two broad categories. In the first category, a generalized integral approach is used wherein the optimal circuit design involves determination of both optimal interconnection of various flotation cells/ banks of cells in terms of structural parameters and optimal values of various operating parameters. In the second category, a conventional circuit configuration is assumed to be the best configuration; the optimal design here only means the optimization of operating parameters. The merits and demerits of these two approaches are discussed.

Jan 1, 1987

By C. Pace, D. Darlington, A. Montera, C. Lingren

"A phosphate beneficiation plant in Utah is using isotope-based Prompt Gamma Neutron Activation Analysis (PGNAA) technology to analyze the entire slurry streams of the incoming feed and final product in order to adjust the flotation circuits in near real time and optimize the plant output. The plant has gained greatly improved visibility/control and has reduced product variability for improved profitability and product quality. This paper takes a look at the economics as well as application details and the difference this technology provides in a phosphate application. SIMPLOT PHOSPHATES INTRODUCTION Simplot’s Vernal, Utah Phosphate Mine and Mill are located in the northeast corner of the state in the Uinta Mountains along US Highway 191, eleven miles north of the town of Vernal. The phosphoric acid and fertilizer plant fed by the Vernal mine is located 94 miles Northeast of Simplot Phosphates in Rock Springs, WY.At the Vernal plant, loader and shovel mining to 85 Ton capacity trucks is done at an annual rate of 3.8 Million tons of ore. Run of mine ore is crushed in a mineral sizer to minus 14 inch diameter at the rate 11,500 tons a day and transported to the SAG Mill’s 130,000 ton surge stockpile by overland belt. ORE RESERVES The ore is a Phosphoria Formation of sedimentary rock type dating to the Permian Age. The ore body rests over a 25 mile area on Weber Sandstone from the Pennsylvania and Permian geologic period. Layers of Phosphate Rock can vary in thickness from 0.3 up to 2.1 feet, alternating with layers of Mudstone. The eastern edge of the ore’s body Panel “G” runs 16 feet deep with a feed grade of 21.5% P205 with lower MgO diluents of less than 2.79%."

Jan 1, 2016

By Fathi Habashi

THE UNIT process of adsorption involves two steps: 1) Loading of the adsorbent. 2) Recovery of metal values from the adsorbent. Charcoal is the adsorbent commonly used in extractive metallurgy. The discovery of the adsorptive power of charcoal from solutions is generally accredited to Lowitz (1785), who observed that several dissolved organic substances were precipitated on charcoal. Graham was the first to demonstrate that inorganic substances were also adsorbed on charcoal. In 1830, he reported that iodine dissolved in KI solution was adsorbed on charcoal. Also calcium ions were adsorbed from limewater, as were lead ions from lead nitrate solution. The use of charcoal in metallurgy was first applied

Jan 1, 1970

By G. Swiatnicki, w. Chruscielewski, T. Domanski

INTRODUCTION The inherent errors of simple passive track detectors /SPTD/ used for estimation of exposure to the radon daughters /RnDP/ amount to about 30% /Do75/ while for active detectors only reach about 3 - 4% /Ph78, Du79/. The large error inherent in SPTD is the result of strong dependence of its calibration coefficient on the equilibrium Rn RnDP in the vicinity of detector /0r80/. Nevertheless the SPTD shows many advantages and seems to be very useful for to the estimation of individual exposure of miners to RnDP /Do81a/. For this reason the investigations are undertaken to improve SPTD so that it might provide information about the equilibrium Rn : RnDP during exposure. If the equilibrium would be known then one could use a suitable calibration coefficient yielding a better precision of the measurement. So far, some investigations of the improved type of SPTD have been conducted. One was based on the concept of using the so called diffusion barrier permitting to differentiate the tracks originating from Rn and RnDP /Fr77/. Such improved detector has been named a passive differentiating track detector /PDTD/. However, own investigations have shown /Do81b/ that this type of detector cannot provide precise informations about equilibrium Rn : RnDP. For this reason the investigations of the new idea of PDTD have been carried out. The new model presented below is based on the use of the absorbers of alpha particles. THEORETICAL CONSIDERATIONS The first variant of the concept is as follows: The differentiating detector consists of two portions of detective foil /track detector/ but only one is covered with an aluminium absorber. Thickness of the absorber is carefully selected so that only RaC' particles /7.7 MeV/ can pass the barrier. The second portion of the detective foil records all alpha particles originated from Rn and RnDP i.e. works like a SPTD. The scheme of such a detector, the so called two-fields passive differentiating track detector /PDTD-2/ is shown in the Fig. 1. It is possible to introduce a parameter that can characterize the equilibrium Rn RnDP, namely, the so called track density ratio /TDR/. The definition of this parameter for the considered type of detector is TDR2 = D1•D2-1. One can expect the simple proportion to hold: [ ]

Jan 1, 1981

By Norm Greenwald

The Environmental Protection Agency ("EPA") has been attempting to develop a federal regulatory program for mine waste under Subtitle D of the Resource Conservation and Recovery Act since 1986. Recent regulatory and legislative events are now bringing this goal closer to reality. This paper discusses the mining industry's perspective on a number of the issues currently being addressed at EPA's Policy Dialogue Committee and in Congressionally-sponsored negotiating sessions.

Jan 1, 1992

By John J. Simmons

Federal and state regulations, in an effort to reduce acid rain, are becoming increasing more stringent regarding sulfur content of fossil fuels. Whereas coal from Illinois and Ohio contains between 1.5 and 37. sulfur, Wyoming has billions of tons of coal reserves containing less than O.5/% sulfur. However, much of Wyoming's coal is high in moisture, 25-30%, and low in energy, 8,200 to 8,900 BTU, vs. 10,500+ BTU for Illinois and Ohio Basin coals. Wyoming currently ships in excess of 130 million tons of coal to utilities as distant as Michigan, Wisconsin, Minnesota, Iowa, Nebraska, Louisiana, Oklahoma, and Texas. With freight charges ranging from $12.00-$20.00/ton, more than $1.5 billion a year is spent to transport water. A test shipment of more than 50,000 tons of Wyoming coal has recently been made from Mobil's Cabello Rojo Mine, south of Gillette, by Burlington Northern to the Robert's Bank British Columbia coal terminal for transloading and shipment to Taiwan Power Company. This coal assayed approximately 8,400 BTU/lb. and 277. moisture. Carbontec Energy Corporation feels the future availability of dried coal containing 11,000+ BTU could substantially enhance the potential export as well as the domestic market for Wyoming coal. Large and small utilities, along with industrial furnaces require tens of millions of tons of Wyoming, West Virginia, and other Eastern The federal government is encouraging the expenditure of hundreds of million of dollars by utilities to retrofit their boilers to allow them to burn higher sulfur coal. This program, if carried to completion, would cost many tens of billions of dollars, with the net result being high power costs sustained by the utilities. These costs will be passed on and paid for by the American consumer. A sensible alternative would be the burning of low sulfur coal by the utilities, without costly capital and operating expenditures. Carbontec Energy feels the successful operation of a Carbondry Coal Drying Plant in Wyoming will be the forerunner to other similar and larger operations in the State. CARBONTEC RESEARCH The activities of Carbontec's personnel to develop a viable process to dry sub-bituminous and lignite coal goes back some 14 years; in fact, for some of us it goes back to 1962 when we were involved in a program under which lignite coal from Truax Trayer's Velva mine was placed in low sulfur coal, which are burned alone or blended with high sulfur, Midwestern coal. Carbontec believes that a high BTU. reasonably priced, shippable coal fuel produced in Wyoming and delivered at costs competitive with Eastern low sulfur coal, could offer substantial benefits to Wyoming coal producers, utility customers, and to the State of Wyoming.

Jan 1, 1989

If a fire occurs outby an underground coal mine section, the immediate safe evacuation of miners from the working section should always be the first action during the rescue operation. Unfortunately, in many cases, the escape-ways (escape routes) dedicated for miners' evacuation are contaminated with fire byproducts from adjacent entries. The purpose of this paper is to present the ventilation control process that will maintain the escape-way free from contaminants and available for travel. Several scenarios in a different section on ventilation system arrangements are analyzed, discussed and presented. To perform these studies, the author used a mine-fire simulator, which provides a dynamic (in real time) representation of the fire's progress and also gives a display, a color-graphic visualization, of the spread of combustion products throughout the ventilation system. Presented and discussed in this paper, also, are ways in which the mine-fire simulator can be used as a training and teaching tool for miners and, particularly, for ventilation and safety personnel.

Jan 1, 1993

By Rainer Antretter

The city of Garmisch-Partenkirchen in southern Germany is located at a main transit road to Tyrol in Austria and suffers of a very heavy traffic load. Therefore, the Kramertunnel as a by-pass tunnel is built to release/mitigate the traffic through the city centre. The 3,600 m long single tube road tunnel is designed with a parallel but smaller emergency tunnel and with cross passages, fitted with single- and doublesided emergency bays, a vent shaft, and an intermediate ceiling to separate fresh air supply from the road traffic. The tunnel, concrete lined along its entire length provided the challenge to find smart formwork solutions for quick set-up, repositioning, setup and pouring. Three particularly specific sections are discussed in this paper.

Jun 13, 2023

By Dennis N. Poffenroth

One concern of the Mine Safety and Health Administration is the structural integrity of steel wire ropes used on mine personnel hoists and elevators. Failure of such ropes has resulted in loss of life and property. Although thorough and regular visual examinations are performed, hoist ropes may still fail from undetected internal wear, corrosion, and broken wires. To complement visual examinations, nondestructive rope inspection techniques have been developed to determine deterioration and removal criteria. The techniques use electromagnetic and permanent-magnet test instruments designed by a Canadian firm. This paper describes the operating principles, field and laboratory testing of these nondestructive testing instruments, and discusses the feasibility of using this type of testing as a supplement to visual examination and destructive tests.

Jan 1, 1982

By R. L. Amelunxen

P. T. Freeport Indonesia (PI) in conjunction with Crescent Technology Inc. has developed a method to predict the metallurgical performance of ores blends based on the behavior of their component ores. The question addressed in this paper is whether ores treated individually could be extrapolated to predict the behavior of a blend of ores. The work further investigates the use of modal analysis to establish individual mineral flotation kinetics in each of the ore zones. This information would lead to the prediction of grade-recovery curves of ores made up of those minerals. Nine samples of ore, representing various zones of FI's Grasberg ore deposit were tested metallurgically and examined microscopically. The same testwork was performed on blends depicting the 1994 mill quarterly feed. Flotation kinetics of the individual ores were then "mathematically" blended and compared to the results obtained from the quarterlies. The calculated kinetics of the actual blends of ore received by the mill were fed to the simulation program and compared to the actual mill performance.

Jan 1, 1995