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By P. Lan

Gold is often associated with arsenopyrite in many refractory gold ores. The selective recovery of arsenopyrite by flotation is therefore necessary in order to maximize the recovery of gold. However, the complexity of arsenopyrite flotation often makes it difficult to obtain a high recovery from real lean gold ore. This paper presents the results of arsenopyrite flotation by ultrasonic pretreatment in micro flotation experiments and bench scale flotation tests. The tests showed that pure arsenopyrite exhibited low natural floatability due to the oxidation on the mineral surface under ambient conditions. Using ultrasonic pretreatment, the oxidation film was ruptured and the floatability was enhanced greatly. The presence of Fe (III) was found to inhibit the flotation of arsenopyrite and this depression was also removed by the ultrasonic pretreatment. This result explained why the arsenopyrite in real ore is often difficult to float and how ultrasonic pretreatment can effectively improve the arsenopyrite flotation in real gold ores. Guanidine (GMM) was found to be a superior collector for arsenopyrite in acidic medium and xanthate in alkaline medium.

Jan 1, 1998

By F. Taylor Ostrander

Some countries are infinitely poorer than others in mineral resources-despite the perfect equality of their political leaders ambitions. Compare the mineral poverty of Kenya and Tanganyika with the riches of Katanga Province and Northern Rhodesia. Compare Paraguay with Chile, There never has been any equality in the distribution of nature's wealth. Minerals cannot play any role at all in economic development where they don't exist, and there are bound to be differential rates of economic development where there are basic differences in the wealth of mineral resources available. Africa is my principal area of interest and I know that there is an unfortunate but widespread misconception about Africa's "vast mineral resources, "its "untapped mineral wealth." Why is it untapped? Why is it undeveloped?

Jan 1, 1963

By P. T. Bissert, J. P. Ducarme, J. L. Carr, A. K. Smith

The continuous mining machine is a key piece of equipment used in underground coal mining operations. Over the past several decades these machines have been involved in a number of mine worker fatalities. Proximity detection systems have been developed to avert hazards associated with operating continuous mining machines. Incorporating intelligent design into proximity detection systems allows workers greater freedom to position themselves to see visual cues or avoid other hazards such as haulage equipment or unsupported roof or ribs. However, intelligent systems must be as safe as conventional proximity detection systems. An evaluation of the 39 fatal accidents for which the Mine Safety and Health Administration has published fatality investigation reports was conducted to determine whether the accident may have been prevented by conventional or intelligent proximity. Multiple zone configurations for the intelligent systems were studied to determine how system performance might be affected by the zone configuration. Researchers found that 32 of the 39 fatalities, or 82 percent, may have been prevented by both conventional and intelligent proximity systems. These results indicate that, by properly configuring the zones of an intelligent proximity detection system, equivalent protection to a conventional system is possible.

Jan 1, 2016

By S. Phillipson

The Mine Safety and Health Administration’s Roof Control Division (RCD) evaluated the use of Shuttle Radar Topography Mission (SRTM) data to identify fracture traces on Earth’s surface. Results were compared to the analysis method employed by RCD for 30 years, which relies on LANDSAT-TM Band 4. SRTM elevation models are expected to provide a direct representation of bedrock surface, while LANDSAT-TM Band 4 represents reflected near-infrared radiation as an indication of moisture content and is only a proxy for possible structures. Three areas in southwestern Pennsylvania were chosen for ground-truthing lineaments derived from both methods, following a series of desktop comparisons in six areas of the contiguous U.S. Field studies that identified numerous instances in which SRTM lineaments corresponded with joints at the projected location, and were oriented within 10° of joint strike, indicating that those SRTM lineaments represented the structural grain of the area. In some cases, lineaments were associated with individual joint zones. Photo-lineaments derived from the existing LANDSAT-TM methodology appear to offer a higher coincidence with expected trends of joints on a regional scale when performing the desktop comparisons, while field observations indicated that SRTM-derived lineaments had a higher association with individual geologic structures in the case study field area. It appears that both methods can identify the structural grain of an area, and that both tend to identify linear segments of valleys where erosion has preferentially occurred along joint zones or other structures.

Jul 1, 2023

By William J. Miles

The inhalation of dust has been a problem in the mining industry since antiquity. Crystalline silica is now known to be the cause of silicosis, a form of pneumoconiosis that is associated with excessive exposure to respirable particles in some mining and industrial environments. Crystalline silica was reviewed by the International Agency for Research on Cancer (IARC) in 1986 and classified as a Group 2A, Probably Carcinogenic to Humans in Volume 42 and Supplement 7 of the IARC Monographs (1987). In 1996, IARC reviewed additional literature and studies published in the intervening decade and recommended that quartz and cristobalite, two polymorphs of crystalline silica, be listed as Group 1, Carcinogenic to Humans. Their recommendations and reclassification were published in 1997 in IARC Monographs 68.[2] In both Monographs, IARC classified amorphous silicas as Group 3, Inadequate Evidence for Carcinogenicity to Humans.

Jan 1, 1998

By Liming Yuan, A. C. Smith

Barometric pressure changes affect air density, leading to change in the mass of the gas in the gob. When the barometric pressure decreases, the volume of gas in the gob expands, while the volume of gas contracts when the barometric pressure increases, a process which causes the gob to “breathe” out and in. Although the concept of gob “breathing” is simple, its effect on spontaneous heating of coal in the gob area is not clear. In this study, computational fluid dynamic (CFD) simulations were conducted to model the spontaneous heating of coal in the longwall gob area under measured barometric pressure changes. A single longwall panel using a bleederless ventilation system was simulated. If there is no barometric pressure change, the intake airflow rate is equal to the return airflow rate. When the barometric pressure changes, these two airflow rates are no longer equal, and the difference between the two airflow rates represents the airflow rate the gob breathes in and out. The effect of inflow and outflow of gas on the potential spontaneous heating in the gob was investigated using the CFD model developed in our previous study. The effect of barometric pressure changes on the spontaneous heating was found to be dependent on the gob permeability and the coal oxidation rate. The effect of barometric pressure changes on oxygen concentrations in the gob was also examined.

Jan 1, 2010

By Michael A. Trevits

A mine fire represents one of the most dangerous and challenging safety issues facing underground mine operators. Given the right circumstances, a mine fire can occur at any location in the active or abandoned mine workings, can quickly grow beyond control, and threaten the welfare and livelihood of the entire underground workforce. The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), has been conducting an in-depth program of research addressing mine fire prevention, early and reliable fire detection, and mine fire suppression technologies. One portion of this program is focused on understanding the characteristics of mine fire combustion products and flame spread through large scale deep-seated (firmly established) fire tests and use of computational fluid dynamics (CFD) modeling. In this study, two deep-seated fire tests were conducted; one fire consisted of coal material and the other utilized the two most abundant fuel sources found in a coal mine: coal and wooden cribbing blocks. The fires were burned to completion while the combustion products were collected and analyzed. In addition, an array of thermocouples was placed within the body of the material to measure flame spread rate. The coal fire test information was then used to develop a CFD model of the fire. This paper describes the fire tests, provides insight into characteristics of flame spread, and presents the CFD modeling work results.

Jan 1, 2009

In the screening process, used to prepare particles for many applications, shape is known to have a significant effect. The degree of flakiness of construction aggregates has been considered particularly important. The objective of this research was to find values of operating parameters that optimize the separation of flaky from non-flaky particles by slotted screens. Thus an investigation was conducted to experimentally determine the influence of the particle size and thickness on the screening process. The Response surface method was employed for modelling and analysis of the data. Experiments employing a central composite design were performed on a pilot-scale, rectangular-aperture, vibrating screen to examine the effects of the screening variables the mass recovery of flaky and non-flaky particles to the oversize product. The SAS statistics package was used to fit a second-order model to each response and to analyze the fitted surface to determine the optimum levels. The optimization associated with a dual response system was then considered. The results of this study should provide a basis for optimizing screening conditions to obtain maximum recovery of non-flaky particles to the screen oversize while minimizing the recovery of flaky particles, which should be of interest to the aggregate industries.

Jan 1, 1999

By Georgene Renner

Due to disturbance of their traditional roosts, caves and tree hollows, more than half of the 44 bat species found in the United States and Canada now live in abandoned and inactive underground mines. The North American Bats and Mines Project was created two years ago by Bat Conservation International Inc. (BCI) in Austin, TX and the Bureau of Land Management (BLM) in response to the issue of mine closure and bat habitat. The partnership provides national coordination among government and private agencies and the mining industry to minimize the loss of bats living in mines. It also trains land managers on how to conduct cost-effective mine assessment and closure to protect both bats and people.

Jan 1, 1996

By M. Ziegler

The article deals with the use of a digital twin in the assessment and optimization of a conveyor system in the Chilean copper mine. This example shows that a digital twin is initially just a new (albeit powerful) tool with which the system behavior can be examined. The benefits for the customer arise through the system identification and automatic detection of critical deviations from the target state. This knowledge allows mine management to react and coordinate operational and/or maintenance counter measures to insure optimal performance of their conveyor system. The information derived from the BeltGenius digital twin also allows mine management to gain a clear perspective of the overall efficiency of their conveyors, which will be invaluable for future conveyor component selections.

Mar 2, 2022

By J. C. Irvine

Meramec Mining Company, a joint venture by Bethlehem Steel Corporation and St. Joe Minerals Corporation, is engaged in the mining, concentrating, and pelletizing of iron ore from the Pea Ridge Mine located near Sullivan, Missouri, about 70 miles southwest of St. Louis. The orebody was delineated in the mid-1950's by St. Joe during an exploration program to discover new lead orebodies. An airborne magnetometer survey which was run by the U. S. Geological Survey, the Missouri Geological Survey, and several min¬ing companies was published in 1950 and showed an anomaly in the Pea Ridge area. Test holes drilled in 1953 and 1954 revealed the presence of a large orebody of probable commercial significance; additional drilling in 1956 and 1957 provided confirmation of this. Meramec Mining Company was incorporated in 1957 and shaft sinking began in the latter part of that year. The Pea Ridge orebody lies under about 1300 feet of sediments. It is tabular, about 2600 feet long and up to 600 feet thick, and lies in an approximate east-west delineation. The orebody dips about 800S and is of unknown depth. The ore is primarily high grade magnetite with smaller zones of specular hematite, The Pre-cambrian wall rock is rhyolite porphyry. The mine is serviced through two concrete-lined shafts, 19 feet 1 inch in diameter and 2500 feet deep. No. 1 shaft, equipped with an "A" type head-

Jan 1, 1972

By Nancy C. Shaver, Alan Tapp

Leach pads of 272,000 tonnes (300,000 st) and 910,000 tonnes (1,000,000 st) with associated operating ponds have recently been constructed on sidehill locations with up to 20 percent slopes. The larger pad was designed in anticipation of ore heights up to 30 meters (100 feet). This paper describes site investigations and civil engineering design as well as construction experience associated with development of these pads. The leach pads were underlain by a double liner system consisting of 2 mm (80- mil) HDPE over compacted fine-grained tailings, with an intermediate leak detection layer. Both sand and geotextile drainage layers were used. Pad slopes were limited by the factor of safety against sliding on the HDPE liner. The sites for the facilities had been substantially disturbed by prior mining and construction activities. Natural conditions included peat layers and locally swampy ground. Site preparation included french drains to lower the water table and stripping of unsuitable subgrade materials.

Jan 1, 1987

By W. E. Lamont

As part of its program to minimize mineral and metal needs, the Federal Bureau of Mines conducted investigations to determine the feasibility of producing foundry-sand-grade olivine concentrates from low-grade sources. Using a Bureau-patented attrition-grinding technique, concentrates meeting Steel Founder's Society of America (SFSA) specifications for loss on ignition (LOI) were prepared. Studies showed that green strengths and tensile strengths of the attrition-ground olivine were equivalent or superior to those of commercial materials. Metal-casting studies showed that molds of attrition-ground olivine produced better surface finishes. The improved surface finishes were attributed in part to increased grain sphericity.

Jan 1, 1977

By A. S. Ibrado, D. W. Fuerstenau

"Gold, silver and copper form various complexes with cyanide, of which only the singly charged dicyano form adsorbs appreciably on activated carbon. The adsorption of the dicyano complexes appears to be controlled predominantly by chemical reaction at the surface of a shrinking unreacted core. Metal uptake over time is non-linear, which eliminates control by boundary layer diffusion. The rate of adsorption is not enhanced by a reaction interruption, which suggests the absence of concentration gradients in the pores. Finally, the rate of adsorption increases with decreasing activated carbon size in a manner consistent with the shrinking core model. The results of this investigation accentuate the importance of efficient acid washing of carbon and removing carbon fines from the barren carbon stream. INTRODUCTION With the dwindling reserves of high-grade ores, most of the world’s gold is produced from low-grade ores by cyanide leaching. In the past, leaching was followed by the Merrill-Crowe process, in which gold is precipitated from clarified pregnant solutions by zinc cementation. This process is still being used for high-silver ores, where the cost of carbon stripping becomes prohibitive. For deposits with silver-to-gold ratios of about 4 or less, adsorption on activated carbon would be the usual solution purification step taken. The process simplifies solid-liquid separation and offers a viable solution to preg-robbing organic carbon in some ores. The modern industrial application of carbon adsorption started with the carbon-in-pulp (CIP) process, where carbon adsorption was used mainly as a solution purification step. In 1973, Homestake Mining Company commissioned the first large-scale CIP plant in the U.S.A.1 Later, carbon was added earlier in the circuit to control preg-robbing by adsorbing gold cyanide onto activated carbon as soon as it is dissolved. The scheme is successful because activated carbon is a stronger adsorber than the organic carbon found in preg-robbing ores. This process came to be known as the carbon-in-leach (CIL) process. Numerous research investigations have been performed on the chemistry involved in the CIP process, which at the time of its introduction was not clearly understood. Of these, research on the kinetics of adsorption probably bears the most immediate impact on industrial practice,2,3 where adsorption systems rarely reach equilibrium, if at all, and slight slowdowns in the adsorption rate can translate into significant decreases in revenue. To illustrate this, organic compounds, like flotation reagents, have been known to impair CIP circuits. However, laboratory tests showed that the organic compounds do not significantly affect the adsorption capacity of activated carbon. Rather, the harmful effect may be attributed to a lowered adsorption rate.4,5 Also well known is the faster rate at which fine activated carbon powders reach equilibrium compared to coarse activated carbon, even though the final (equilibrium) amount of material adsorbed per unit weight is the same."

Jan 1, 2015

By R. R. Klimpel

The process of flotation is an extremely important solids separation technique employed in a wide variety of industrial process applications. Froth flotation is practiced in the coal industry to recover fines produced during the mining and cleaning of coal. A recent review article by Aplan (1) covers the processing variables encountered in the flotation of coal and the variety of chemicals and operating conditions which affect recovery. Numerous engineering and scientific studies have been performed with the goal of providing semifundamental laws of flotation behavior for improved screening of flotation chemicals, better equipment scale-up factors, etc. Often the results of such work are expressed in the form of mathematical models (e.g. 2, 3, 4, 5, 6) which are potentially useful for evaluating (simulating) on paper such alternatives as possibles process operating or configuration changes, the effects of ore and reagent changes, etc. It appears to be commonly accepted that a complete scientific/engineering characterization of flotation is immensely complicated and not sufficiently developed at the present to accurately predict (or understand) many important industrial facets of flotation. Thus, one is often reduced to detailed experimental characterization in both the laboratory and plant in order to fully evaluate flotation changes or alternatives. It is the purpose of this paper to describe a method of batch laboratory data characterization that is useful in evaluating flotation chemical reagents including froth flotation of coal. The approach consists of running a series of time-recovery curves in a batch float cell followed by the computer curve fitting of this data to a series of mathematical models based on semi-physical reasoning. The unknowns or parameters of these models are then optimally chosen so as to best fit the experimental data. It has been found in both coal and mineral systems that changes in reagent type, concentration, system pH, grind, etc. cause very consistent and logical changes to

Jan 1, 1979

By P. Tsang

To gain insight into the current status of pillar design practice in the underground coal mines of United States, a survey has been undertaken in the late 1993 and early 1994. A total of 552 room-and-pillar mines and 75 longwall mines have been surveyed to collect general, geological and mine plan information. The collected information are critically analyzed with special emphasis on the pillar design criteria adopted in these mines. A safety factor analysis has also been carried out for the pillars in room-and -pillar mines.

Jan 1, 1995

By Ilmar J. Martens

The statistical information and cost data used in this report has been made available by NICKDATA INC. Since 1982, NICKDATA INC. of Toronto, Canada, has produced an annual comprehensive nickel industry cost study. Up to date information on 22 mines, 21 smelters, and 16 nickel refineries representing 30 nickel production operations in 17 countries are included in the computerized cost analysis. The report is compiled from information obtained through regular annual visits to major nickel operations and continuous monitoring of information on all nickel producers. The 1984 report which was completed this summer, reveals drastic changes in the nickel industry cost structures.

Jan 1, 1984

By N. Sahin, M. Can, Z. Ekmekçi, Y. Öztürk, Ö. Biçak, I. B. Çelik, B. Kocabiyik

"In this paper, a case study from Çayeli Bakir Isletmeleri A.S. (Rize, Turkey) about the selective flotation of copper minerals from sphalerite is discussed. Çayeli Cu-Zn Sulfide Ore contains different ore types, such as yellow ore, clastic ore, bornite-clastic ore, bornite-yellow ore, and black ore. For some of these ore types, selective flotation of copper and zinc is very difficult presumably due to presence of secondary copper minerals such as bornite, chalcocite and covellite, and also surface oxidation. These factors affect Cu-Zn selectivity due to activation of sphalerite particles in the ore during the process. The main objective of this work was to improve Cu-Zn selectivity by optimization of the pulp chemistry for different ore types of Çayeli ore. After preliminary flotation tests investigating effects of different chemical conditions, a plant survey was performed to determine the plant performance and sources of the problems when problematic bornite-clastic ore is treated in the plant. Various chemical conditions are tested in the laboratory scale test for better depression of sphalerite in copper flotation circuit. Combination of Na2S+ZnSO4+MBS was found to be the most effective depressant scheme. INTRODUCTION Ore variability is one of the most important factors affecting performance of a process plant both in short and long term planning. The geometallurgical modelling becomes a common tool to determine ore variability problems and develop the most efficient solution during life of mine (1, 2). Flowsheet design and equipment selection and sizing are usually done based on the results of ore variability test works. However, in some cases ore variability may not be foreseen during the design stage and therefore the solutions should be developed based on the existing flowsheet and equipment in the plant. In this situation, ore characterisation, problem statement and diagnostic testing should be applied step by step. The problem could be due to changing feed grade, mineralogical characteristics, grindability and surface characteristics when flotation is involved. The variability in feed grade with fixed mineralogy can be handled with relatively simple modifications (i.e. adjusting throughput or equipment capacity) in the plant. Variability in ore mineralogy is the most complex and difficult problem to tackle. Because, mineralogical variations could bring variations in mineral composition, texture and liberation. These variations can potentially lead to the variations in grindability of the ore and flotation behaviour. Variations in grindability are usually managed by optimization of operational parameters in grinding circuit, as it would be costly to replace the existing equipment in the circuit (3). The variations in flotation behaviour are mainly due to variations in mineral types and distribution, texture and surface oxidation. One or all of these factors could be observed in a flotation operation. Therefore, a comprehensive investigation both in plant and lab scale should be conducted for definition of source of the problem. The testwork to solve the problem and retrieve the performance is planned and conducted depending on the source of the problem (4, 5)."

Jan 1, 2017

By Jacob Bouke, Jason Janisch, Erik Vlot

The use of conventional tailings deposition methods has been the standard for decades. With the need to reduce the impact of mining, alternative methods are considered when expanding or upgrading tailings handling systems. Converting an existing tailings management system to a more sustainable deposition method during the operation of a mine may incur considerable operational and financial risk, and when assessed more traditionally, does not provide significant advantages. As a result, most mines choose to continue their current technology and add an additional pumping stage or pumpstation to their tailings line in case of a pipeline extension or Tailings Storage Facility (TSF) expansion. This also often involves raising embankments. Changing pumping technology is traditionally assessed by comparing the energy efficiency of current and prospective pumping technology. Despite a reduction in absorbed power, this traditional assessment does not include possible savings in water and the carbon footprint. With the consideration of all these three aspects, alternative pump technologies, such as Positive Displacement (PD) technology, become more economically feasible, providing increased sustainability and enable a site to future-proof their operations. Project feasibility may be affected by the high capital investment required for PD pumps. The benefit of applying PD pumping technology could be enhanced by reducing the volumetric throughput of the pipeline by dewatering the tailings to 65% solids concentration by weight. It was found that despite increasing capital expenditure, the improved reclamation of water will have a positive effect on the direct and indirect cost of fresh water intake to mine operations. This paper seeks to illustrate that in many applications the long-term benefits of investing in sustainable tailings management are optimized when more efficient PD pumping technology is combined with tailings dewatering when upgrading or expanding the tailings handling system.

Feb 1, 2024

Laboratory testing by the Federal Bureau of Mines has shown that the removal of insoluble slimes using selective flocculation and flotation is a viable method for treating low-grade potash ores which have a high content of water-insoluble impurities. Results indicated that up to 85 percent of the insoluble slimes could be removed from sylvinite ore containing 5 percent water insolubles and 13 percent K20 using nonionic or cationic polyacrylamide flocculants and cationic, anionic, and/or nonionic collectors. Subsequent potash flotation recovered up to 88 percent of the potash in rougher concentrates containing 47 to 57 percent K20. Sizing and cleaner flotation of the rougher concentrates upgraded the products to 60 percent K20. Filtration of the insoluble slimes flotation concentrates recovered 87 to 0 percent of the brine. Flotation concentrate filtration rates were 7 times faster than the filtration rates of mechanically deslimed products.

Jan 1, 1977