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By L. Vinnett, J. Yianatos, S. Flores

"A numerical conditioning analysis for mineral recovery estimation was performed for industrial flotation plants, considering the copper (Cu), molybdenum (Mo) and iron (Fe) separability. A modified relative condition number, ?, was presented that allowed sensitivity analysis to be evaluated for the component recovery by means of an analytical formula. This closed form made it possible for the error propagation to be determined from feed, concentrate and tail grades with different orders of magnitude. The ? parameter can be evaluated using available grade data from the design criteria or historical mass balances, in which the variability is typically unknown. Reconciled data from different Cu/Mo concentrators were employed to evaluate the effect of small numerical disturbances in the grade data on the mineral recovery estimation. Higher error propagation was typically observed for Fe. The Mo minerals presented numerical problems, mainly in second cleaners and in the first cell of rougher banks. Lower condition numbers were observed for Cu due to the higher flotation rates.Mass-balance data reconciliation without redundancy was evaluated for a typical Cu/Mo flotation circuit using relative error minimization. Significant relative errors in the mineral recovery estimation were obtained with nonreconciled data in ill-conditioned problems. Negligible improvements in the mineral recovery estimation because of the data reconciliation with regard to the nonreconciled approach were obtained in well-conditioned problems. In addition, the improvements in mineral recovery estimation by using Cu, Mo and Fe in the data reconciliation were nonsignificant with respect to using only the best-conditioned component in well- and ill-conditioned problems.Despite the effort in data reconciliation and data repetition, poor performance may be obtained in ill-conditioned problems, which can deteriorate the flotation rate characterization. The error propagation has a negative impact on the mineral recovery of the first cell, which may significantly bias the flotation rate characterization of both valuable and nonvaluable elements.IntroductionMass balances have been extensively used in flotation processes to determine the mass flowrates (production) and mineral recovery (efficiency) of valuable minerals. Simple relationships for steadystate processes based on the feed, concentrate and tail grades can be obtained by taking a black-box approach. However, the calculation of concentrate flowrates from different components of the system, such as size fractions, chemical elements or minerals, does not satisfy the mass-conservation principle because of measurement errors (Smith and Ichiyen, 1973; Romagnoli and Sánchez, 2000). Mass-balance data reconciliation allows for obtaining a unique solution that satisfies the total and component mass balances, making small adjustments to the process data and taking advantage of the information redundancy (Narasimhan and Jordache, 2000). This methodology, which is based on a constrained weighted least-squares minimization, has proved to be robust when measurement errors are normally distributed, in the absence of gross errors.Commercial software has been developed to conduct massbalance data reconciliation in flotation processes, including MATBAL (Algosys, 2002), BILMAT (Algosys, 2013), JKMultibal (JKTech, 2013), BILCO (Caspeo, 2013) and HSC Chemistry (Outotec, 2013), which accomplish the reconciliation using known data accuracy in the optimization problem. The data accuracy can be obtained by sampling a stream n times in a run, known as repeats, each with independent chemical assays. Some unmeasured variables can be estimated using the measuring redundancy and sensor location. At present, grade and flow rate sensors may be incorporated in flotation to conduct real-time mass balances. However, a lack of sensor calibration and maintenance for suitable online measurements hinders the quality of the information. In"

Jan 1, 2016

By John B. Gustavson

This paper describes a case history of geochemical prospecting. An area of known mineralization was available for an orientation survey which led to the selection of elements and criteria for a reconnaissance survey in the area offsetting the known mineralization. Certain anomalies were found which were then made subject of confirmation sampling and of rock geochemical investigations. Inasmuch as the geochemical prospecting technique specifically led to a detailed area which now serves as a target for drilling and other exploration efforts, the geochemical prospecting part of the program is considered successfully concluded and, therefore, reported on here. Whether the target area will turn out to host the deposit or not is, of course, of utmost importance to the Company, but is of less importance to this paper. We will describe the concepts, the planning, the execution, the analysis and the interpretation of this typical geochemical prospecting case. A number of people on the staff of International Oil & Gas, Inc. have participated in this prospect, as have students from Southeast Missouri State University and their professor, Gary M. Lowell. In addition, the Missouri Geological Survey has been most helpful with records and letters on the century-old prospecting and mining in the general area. Many valuable discussions have also been held with geologists from the industry who, from time to time, have visited the area, examined the property and reviewed the status of the project. The support and interest from all these parties has made it possible to pursue and expand this exploration concept from one of being just "more of the same kind" to the most chal-1enging and exciting with which this author has ever been involved, namely the prospect for tin porphyry deposits in the mid-continent United States.

Jan 1, 1977

By T. Stauffer, B. McGunegle, A. Adu-Acheampong

The Fairmount Minerals, Inc., Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 15-inch-diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially-available, high-volume/low-pressure fans combined with a systematic layout of control structures. The recommended re-design was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2007

By Eduardo Pimenta de Melo, Rambabu Pothina, Rajive Ganguli

Sensors are everywhere in the mining industry, with sensor information being used to monitor and operate processes. Therefore, when sensor information is wrong, economic losses can occur. Unfortunately, sensor errors are usually not detected till they become large. This is problematic as most calibrate their sensors no more than once a year (Beamex, n.d.). Using principles of data mining, where all relevant information is tapped to glean hidden information, Pothina [8] designed an algorithm to detect errors in temperature sensors in gold stripping circuit in Pogo mine, Alaska. This paper continued his work by analyzing the behavior of the algorithm on baseline data and testing the algorithm in new data and under more rigorous conditions. It also made a change to the algorithm. The modified algorithm performed very well in the new data. It also worked well under the new error conditions. Three types of errors were seeded, a fixed additive error (+ 2%), a fixed subtractive error (− 2%), and a noisy, normally distributed error, with a mean value of + 2%. Artificially seeded errors were detected within about 20 gold stripping cycles. Inherent bias in operation impacted algorithm performance by increasing the number of cycles needed to detect errors. This paper reinforced Pothina’s [8] conclusion that when data mining approach is used, sensor errors can be detected even when they are pretty low. Significant economic losses can thus be minimized.

By C. Y. Haas

Of all the industrial clay minerals, attapulgite probably enjoys the widest variety of applications. A review published over three years ago by Haden and Schwint (18) cited some 80 individual uses, a list which continues to grow. In its near half-century of commercial life, attapulgite has received a generous share of research study and patent development effort, both on the part of producers as well as consumers. This work has been divided between understanding the mineral's structure or properties and applying it to specific end-uses. Naturally, information gained from the former has pointed toward opportunities in the latter. References of particular significance are cited throughout the text. Attapulgite's variety of uses derives from the unique three-dimensional structure and needle-shaped particle form of this crystalline hydrated magnesium aluminum silicate. Its inherent colloidal and sorptive properties are well known, and distinguish it from its sister clay minerals. Attapulgite is characterized by its high surface area, porosity, sorptivity, and decolorizing power. Its slips or slurries are viscous and thixotropic, however, unlike bentonite are not flocculated by electrolytes. In Table I are compared the general properties of attapulgite, bentonite, and kaolin. The properties in Table I are documented in greater detail by the wealth of scientific literature which has been published on the composition (14)(15), structure (6)(16), surface (16)(4)(22)(24), adsorption (31)(4)(5)(25), rheology (10-11)(12)(13)(26)(27)(32), plasticity (30) (31), and chemistry (23)(3)(7) of attapulgite. Attapulgite is the principal mineral constituent (70 to 80%) of attapulgite clay as it is commercially produced in the Georgia-Florida area of the United States. As mined, this clay also contains 10 to 1S% montmorillonite, sepiolite, and other clays; 4 to 8% quartz, and 1 to 5% calcite or dolomite. (18) During processing, non-clay fractions are removed so that commercial products are enriched to 85 to 90% attapulgite. By wet processing (such as practiced in the

Jan 1, 1971

By Adrian Molinari

A radioisotope probe (Minexan 202) capable of simultaneously analyzing a mineral slurry for five elements and pulp density has been developed by Outokumpu Oy, Finland. The probe is designed to operate immersed directly in a process stream, or it can be equipped with a flow cell through which passes a continuous sample of the main stream. A minicomputer (PDPII) is used to control the probes and calculate the assay data. This paper describes the probe as applied to slurry analysis and compares it to the conventional x-ray on-stream analyzer (Courier 300).

Jan 1, 1977

By Brian Y. Lattimer, Kray D. Luxbacher, Jonathan L. Hodges, Manuel J. Barros-Daza

The abstract discusses the importance of predicting fire response time (the time before conditions become untenable for firefighters) in underground coal mines. It introduces a data-driven approach using artificial neural networks (ANNs) to predict response time and fire size based on measurable parameters like CO concentration, mine geometry, air velocity, and time since fire detection. The approach was tested using simulations from fire models (FDS and FSSIM), showing promising results for real-time predictions during mine fires.

Mar 6, 2022

By Inoka E. Perera, Michael J. Sapko, Marcia L. Harris

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effectively inert a coal dust explosion, rock dust must be able to disperse as individual particles to air. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anticaking additives after being exposed tomoisture and then dried. The dusts were exposed tomoisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anti-caking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Experimental Mine (LLEM), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for 1 day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for 6 months. This report details the analysis and characterization of anticaking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber.

Apr 12, 2021

By D. P. Bryan

An aggregate resource study was done for southern Washoe County, Nevada, which contains the Reno-Sparks metropolitan area and a population of about 300,000. The study included an inventory of existing operations, projection of future demand, identification of potential aggregate resources based on geology, and determination of economic potential of these resources. Economic potential was determined by the integration of GIS layers that included aggregate potential, distance from market, distance from major and minor transportation arteries, and elevation. The investigation resulted in a determination that resources of high quality aggregate sufficient for future consumption are present in southern Washoe county; the limiting factor for future utilization is accessibility.

Jan 1, 1996

By M. R. Shahan, C. E. Seaman, Mischler S. E., T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. IntroductionCoal mining processes produce airborne dust that naturally deposits on the floor, roof and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 µm in diameter, are deposited in the return entries of coal mines and can be reentrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; U.S. National Institute for Occupational Safety and Health (NIOSH), 2006). These particles are also those most likely to participate in coal-dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (U.S. Mine Safety and Health Administration (MSHA), 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal-dust-fueled explosions."

Jan 1, 2018

By REHMAN ATTA UR, Kwame Awuah-Offei

This work evaluated the effects of bucket orientation and operating parameters on resistive forces and penetration for rubber-tire loaders (RTLs), such as load-haul-dumps (LHDs) and front-end loaders (FELs). The work used a 1:16 scale LHD model to test an RTL bucket operating at different levels of traction (tractive effort), speed, digging height and rake angles in a full factorial design experiment. The test was repeated on two muck piles with different particle sizes, and generalized regression modeling was applied to test the association of rake angle, tractive effort, speed and digging height on penetration and resistive forces for RTL buckets. The results show that speed and tractive effort are more important in explaining RTL penetration and resistive forces than height above the floor and rake angle. Speed, tractive effort and height above the floor are positively correlated to bucket penetration, whereas the rake angle is negatively correlated to penetration. Similarly, speed, tractive effort, rake angle and height above the floor are all positively correlated to resistive forces incurred during initial penetration. The results show that the combined effect of speed and tractive effort is negatively correlated to penetration and resistive forces — a novel finding that enhances our understanding of RTL loading. The results also show that the effects of speed, tractive effort and height above the floor all change with changes in particle sizes. This work provides insights into the effects of rake angle, height above the floor, tractive effort and speed on penetration and resistive forces for RTLs to facilitate better design and efficient use of these loaders.

By O. Schumacher

Guidelines for publication of information defining the amount and grade of resource material available in a deposit are well established in Australasia?s JORC Guidelines, Canada?s National Instrument 43-101 and similar documents in South Africa, Peru, Chile and elsewhere (Table 1). These guidelines provide standards to apply regarding the geologic and geostatistical basis for describing the level of confidence to be assumed for an estimate of the amount and grade of material. All of them provide for a strict distinction between material that has been demonstrated to be economically mineable and that which has not, and all of them provide terms such as ?resource? or ?exploration information? to be applied to data regarding material that has not been demonstrated to be economically mineable. It is not until an economic study has been completed that we are allowed to apply the powerful terms ?reserves? and ?ore? to our deposit material. Indeed, the application of these eye-catching labels immediately tells the reader that an economic study has been completed by a qualified person, and that the results of the study were positive. While extensive guidelines are established for describing the level of confidence in published geologic data, and the nature of the economic study that should be accomplished before using the terms ?reserves? or ?ore?, surprisingly little guidance is provided regarding the process to use, and the level of detail to attain, for estimating capital and operating costs for the study. The intent of this paper is to lay the groundwork for development of suitable guidelines for the cost estimating process. While the codes do not provide specific instructions for the cost estimate, they do provide numerous hints and clues to help determine the level of detail expected and the type of procedure to apply in preparing the estimate. This paper will first review the various codes to gain an insight into the thinking of the drafters of the codes regarding their unstated expectations for the cost estimating process. Based on this review, a series of guidelines are proposed for this purpose.

Feb 27, 2013

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

There are several methods (empirical, statistical, and machine learning tools) to calculate blast-induced ground vibration. Still, due to complications in the blasting procedure, under varying blasting loads and strata conditions, it is not easy to predict and simulate blast vibration precisely. Therefore, a study was conducted to simulate the field blast data in Ansys software using explicit dynamics. For this study, monitoring of ground vibration for 20 single hole blasts was carried out. The density of emulsion explosives was in the range of 0.9 to 1.15 g/cc. In the laboratory, rock properties were determined from the rock sample collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and the density of the emulsion explosive were also determined. These parameters were used for numerical analysis to know the ground vibrations at specified points. The results of ground vibration predicted by the model are validated using field data.

By W. H. Langer

At the start of the 20th century Denver?s population was 203,795. Most streets were unpaved. Buildings were constructed of wood frame or masonry. Transport was by horse-drawn-wagon or rail. Statewide, aggregate consumption was less than 0.25 metric tons per person per year. One hundred years later Denver had a population of 2,365,345. Today Denver is a major metropolitan area at the crossroads of two interstates, home to a new international airport, and in the process of expanding its light rail transit system. The skyline is punctuated with skyscrapers. The urban center is surrounded with edge cities. These changes required huge amounts of aggregate. Statewide, aggregate consumption increased 50 fold to over 13 metric tons per person per year. Denver has a large potential supply of aggregate, but sand and gravel quality decreases downstream from the mountain front and potential sources of crushed stone occur in areas prized for their scenic beauty. These issues, along with urban encroachment and citizen opposition, have complicated aggregate development and have paved a new path for future aggregate development including sustainable resource management and reclamation techniques.

Jan 1, 2009

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

e Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

e Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

By G. Ferrara

The paper describes the new design criteria and control strategies for multi-density dense medium separation (DMS) circuits. The role of the multi-density separation is discussed, and it is emphasized that for many processing problems -related to minerals and coals -it may be very important to perform two or more cuts at different densities in order to obtain a remarkable improvement in quality of products, process efficiency and economy. The two-density separation by dense medium cyclones was generally performed using two dense medium plants in sequence. In contrast to the former technology, the multi-density separation can now be performed by using a single medium circuit composed of different interconnected medium sumps. The sumps, one for each density, are fed with different medium streams selected according to their density, size composition and content in non-magnetic contaminant in such a way that the rheological properties of the media are optimized. This new technology is based on dynamic systems to density the medium, on the size-density segregation of the medium in the cyclones and separating devices and on accurate control systems for the density, viscosity and stability of the dense media of the different sumps. The present paper reports on the theoretical basis for the new, advanced medium circuits and on the systems for the control of the densities and of the rheological properties of the dense media. A typical circuit for a two-density separation is also described, and some industrial applications reported and discussed.

Jan 1, 1994

By Shawn Orser, Jennifer Waddell, Mike Sierakowski, Tom Barrett

Production evaluations were conducted at Daisy Gold Mine (Glamis Gold, formerly Rayrock), between August, 1997 and August, 1998 to quantify the effect of 3M fluorochemical surfactants (fluorosurfactants) on extraction kinetics and gold recovery in gold heap leach mining operations. Ore was treated at a level of 7-10 grams surfactant per ton of ore using 3M Pluorad TM Leach Mining Additive PC-GOLD. Kinetics and gold recovery were determined by solution assay for each of the tests. Both tests indicated improved kinetics, and data from Test 2 was used for determination of a quantitative increase in gold recovery resulting from PC-GOLD addition. A discussion of test results including methods used to determine gold recovery is provided.

Jan 1, 2000