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By Wen Tao Liu, Tong Tian, Fu Sheng Niu, Xiu Man Liang

In order to address the difficulty of accurate segmentation of froth images of different sizes, a method of froth image segmentation based on highlight correction and parameter adaptation is proposed. First, a machine vision system on a single-cell flotation machine is built to collect froth images. Homomorphic filtering is used to improve the uneven brightness and shadow of the images. Fuzzy c-means (FCM) clustering is then utilized to classify similar highlights that belong to the same froth. After Otsu threshold segmentation, a parameter-adaptive morphological operation is used to extract the marker points and edge bands and correct the froth edges in the original image. Finally, the modified image is filtered by morphological reconstruction, and the highlight mark is used as the local minimum point for watershed segmentation. Three sizes of froth images are segmented in comparative experiments. The results show that the proposed method is suitable for the segmentation of froth images of different sizes. The position of the extracted segmentation line is close to reality, with average over-segmentation and under-segmentation rates for froth images of 2.6% and 6.8%, respectively. The froth image segmentation performance is stronger than that of the other methods examined.

By W. R. Reed, Y. Zheng

A recent study conducted by the National Institute for Occupational Safety and Health (NIOSH) evaluated the roof bolter canopy air curtain (CAC) systemin a blowing face ventilation system, demonstrating its effectiveness and illustrating the CAC protection zones. This study evaluates the roof bolter machine CAC while operating in an exhausting face ventilation system. This study considers two similar locations to allow comparison with the previous blowing face ventilation (Zheng et al., Min Metal Explor 36(6):1115–1126, (2019)) study: (1) a roof bolter machine bolting the roof at 20 ft (6.1 m) from the face and (2) a roof bolting machine bolting at 4 ft (1.2 m) from the face. The environment introduces 6.0 mg/m3 of respirable dust to represent the roof boltingmachine operating downstreamof the continuous miner. However, the exhausting face ventilation uses an exhaust curtain with 9000 cfm (4.25 m3/s) of air. Two roof bolter machine working positions are simulated with the use of dual drill heads in the inward position for two inside bolts and in the outward position for two outside bolts. The influence of the CAC on airflows and dust dispersion is evaluated with the CAC operating at 250 cfm (0.12 m3/s) with dust reductions ranging from 39.5 to 82.8%. When the roof bolter machine operated close to the face, increasing CAC airflow was required for adequate protection since the dust reductions can be as low as 39.5%. Additional CAC airflows of 350 cfm(0.17 m3/s) and 450 cfm(0.21 m3/s) were evaluated and demonstrated that dust reductions increased to 59.7% (350 cfm) and 72.0% (450 cfm) for the worst location where the roof bolter operators located.

Aug 26, 2020

By MOHAMMED AMINE BELMI, ANAS DRIOUCH, ABDELAZIZ LAHMILI, LATIFA OUADIF

For many years, underground workings in the Bou Azzer mine have been challenged by geotechnical problems related to the serpentinite instability. The stage of evaluation of the compression potential is crucial to develop an appropriate drilling method and the choice of non-standard support. This research work presents a retro-analysis of serpentinite behavior in underground excavations at different depths, using a multi-approach method, based on several empirical and semi-empirical and theoretical-analytical methods, calibrated by the observational method. The analysis performed in this work reveals that underground excavations in Bouazzer East and Ait Hmane area would encounter compression problems that were recognized as the most serious from a depth of 300 m because of the effects of lithology and tectonics. Therefore, the Aghbar region has a slightly negligible compression potential. The compressive failure mechanism in this mine, depending on the mechanical strength, is started at induced stress of 9 MPa.

Nov 27, 2021

By Miguel Reyes, Mathew Girman, Chenming Zhou

Modern smart mining increasingly depends on sophisticated electrical and electronic systems for improved safety and productivity. With more electronic systems being introduced underground, the mining industry faces electromagnetic compatibility (EMC) issues caused by electromagnetic energy emitted by one device adversely impacting the normal function of another. This paper provides an overview of EMC and electromagnetic interference (EMI) research for underground mining, including a review of EMI in other industries applicable to mining, published EMI research pertaining to mining applications, representative EMI incidences, related EMI legislation in mining, and mitigation strategies.

Jan 3, 2022

By A. I. Johnson

This paper describes," the application, of a modular or building block approach to the analysis, design, and control of complex mineral treating processes. The main purpose of the paper is tutorial, to show the reader how such processes can be modeled using a modern digital computer" and, not to discuss in any detail the results that may be achieved in such studies. It is proposed that, the main techniques be illustrated by reference mainly to the Bayer process for alumina extraction and purification; in cooperation with the Aluminum Company of Canada Ltd. the author and his Colleagues at McMaster University and their students have studied this, process as a means of applying new computer techniques to extractive metallurgical processes. The plant described was studied by the author and his colleagues as a senior undergraduate project in cooperation with the Aluminum Company of Canada. It is one of several studies that have been carried out with Canadian industry. (1)

Jan 1, 1972

By Paul R. Smith

The theoretical requirements for the flotation d large particles are discussed. A flotation machine is described which has components which meet many of the theoretical requirements for the flotation of large particles. The machine's salient features include multiple fine-bubble attachment, froth level feeding, quiescence, shallow depth, and short flotation time. Test conditions and results are presented for the laboratory flotation of 10 mesh phosphate, 4 mesh potash, and 1/2 inch coal. In addition, test conditions and results of pilot plant flotation of minus 14 plus 35 mesh phosphate and minus 14 plus 150 mesh phosphate are also presented.

Jan 1, 1969

By J. Rostami, J. Brune, S. Slouka

Respirable dust poses long-term health issues to personnel working in mining and civil projects where mechanized mining and tunneling machines are used for hard rock excavation. Machines, such as longwall shearers, roadheaders, or continuous miners, use consumable picks to cut rock. However, rock dust is generated in the work environment each time the pick tip contacts the rock surface. Additionally, the generated dust can be reintroduced into the air further down in production, such as at transfer points. The purpose of this study is to characterize respirable dust particles generated at the pick tip at two stages of pick wear: new and moderately worn. Understanding dust characteristics in terms of concentration, size distribution, and particle shape throughout the life-cycle of the pick will provide a basis to mine and tunnel operators for changing out picks to mitigate dust generation at the source. This paper discusses the dust characteristics generated from preliminary full-scale cutting tests in a laboratory of an igneous rock block cut with conical picks at new and moderately worn levels of wear. The moderately worn pick generated a size distribution that favored smaller particle sizes compared to the new pick. The moderately worn pick also generated more overall dust, as the concentration level in mg/m3 was over double the amount of the new pick. Lastly, both picks generated particles that had similar aspect ratios and roundness measures.

May 18, 2022

By J. Mark Richardson

The use of an integrated software package to simulate and optimize the performance of mineral processing circuits is illustrated by three examples. Each represents application of the software and associated techniques to optimization of an existing plant. In the first example, a South-western U. S. copper company employs the method to simulate and improve performance in crushing, screening and SAG milling. A second copper producer evaluates equipment changes and flowsheet alternatives in a closed-circuit ball mill-cyclone operation. A Southeastern U. S. aluminum refinery optimizes performance of a dry milling and classification circuit for production of carbon particles used in anode casting. Graphical and tabular data describe the circuits simulated and the results achieved in each example.

Jan 1, 1990

By C. L. Karr

Researchers at the University of Alabama are investigating artificial intelligence based computer models of mineral processing systems. Two approaches have been found to be particularly effective in developing data-driven computer models. The first approach employs neural networks which are computational paradigms based on the mechanics of the human brain. They are able to extract the basic relationships between input and output variables from large data sets. The second approach combines fuzzy mathematics with genetic algorithms to produce an adaptive modeling system. Fuzzy mathematics provide computers with the capability of manipulating abstract concepts like those which humans use so effectively in decision making. Genetic algorithms are search algorithms that mimic evolutionary processes apparent in nature. Together, these two techniques can be used to produce an effective modeling system. In this paper, the two approaches to modeling are compared and contrasted with respect to accuracy and computational time while used to model three mineral processing systems: (1) a grinding circuit, (2) a hydrocyclone separator, and (3) a flotation circuit.

Jan 1, 1997

By J. Helton, J. L. Bellanca, M. McNinch, L. R. Swanson

DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of company names or products does not constitute endorsement by NIOSH. ABSTRACT Accident data indicates that mobile haulage poses a significant pinning, crushing, and striking risk. Proximity detection systems (PDSs) have the potential to protect mineworkers from these risks. However, unintended consequences of mobile PDSs can undermine the safety benefit they provide. Soliciting iterative user input can improve the design process. Users help provide a critical understanding of how mobile PDSs may hinder normal operation and endanger mineworkers. Researchers explored users’ perspectives by conducting interviews with mineworkers from seven mines that have installed mobile PDSs on some of their haulage equipment. Mineworkers reported that mobile PDSs affect loading, tramming, section setup, maintenance, and general work on the section. Mineworkers discussed the operational effects and increased burden, exposure, and risk. Mineworkers also suggested that improved task compatibility, training, logistics, and PDS performance might help address some of these identified issues. This paper also gives additional insights into mobile PDS design and implementation. INTRODUCTION Pinning, crushing, and striking accidents are a large problem in underground coal mines, especially for mobile haulage. Between 1984 and 2014 there were 179 non-fatal and 42 fatal pinning, crushing, and striking accidents involving mobile haulage vehicles, including coal hauling machines and scoops [1]. Proximity detection systems (PDSs)—automated systems that decelerate and stop a vehicle in order to prevent a collision—have the potential to protect mineworkers in these situations. In fact, PDSs are now required on all place change continuous mining machines as of March 16, 2018, as a result of the final rule published in January 2015 (30 CFR 75.1732) [2]. To address mobile haulage, later in 2015 the Mine Safety and Health Administration (MSHA) also proposed a new rule that would require PDSs on mobile haulage vehicles [3]. Though there has been no additional actions related to the proposed rule and it is not currently required, mobile PDS can still help to save lives. MSHA estimates that the adoption of mobile PDSs could prevent approximately 70 injuries and 15 fatalities over the next 10 years [4]. As of June 2015, the underground coal industry had already equipped 155 of the 2,116 mobile haulage vehicles in use [1]. In order to capitalize on the projected safety gains afforded by PDSs, it is important that the systems are designed and implemented effectively. Along with others, researchers at the National Institute for Occupational Safety and Health (NIOSH) have been exploring PDSs for more than two decades [5-7]. Throughout this time, NIOSH has also held several stakeholder meetings (2010, 2014, 2016, and 2017) in order to disseminate information and provide an opportunity to discuss on ongoing issues and concerns. Despite some progress, human factors remain a key concern. Previous research examined mineworkers’ attitudes towards PDSs on continuous mining machines [8] as well as how continuous miner operators’ perceptions of risk have changed as a result of PDSs [7]. However, stakeholders have still expressed a need to better understand how mobile PDSs affect the mining process, the mineworker, and whether and how they may present previously unidentified risks.

Jan 1, 2019

By Diler Katircioglu-Bayel

This manuscript aimed to examine the impact of operating parameters on the wet grinding of talc in a vertical-type stirred media mill. Within the scope of the research, the effects of operating parameters including media filling ratio, solid mass fraction, grinding media size, and grinding time were studied. The findings were assessed based on the product particle size (d50, d10), surface area (Sw), and energy consumption (Em). As a result of the present research, the following optimum grinding test conditions were determined: 65% media filling ratio, 40% solid mass fraction, 1 mm grinding media size, and 120 min grinding time. After determining the optimum grinding conditions, the Box–Behnken statistical design was used to determine the effect of parameter interactions on the d50 size. The media filling ratio was found to significantly affect the decrease in d50 compared to the other two parameters. Furthermore, the minimum d50 size was also achieved under optimum grinding conditions.

Aug 12, 2020

By M. S. Riyaz Ulla

The Hutti Greenstone belt, located in the northern side of Dharwar Craton, India, contains several promising gold fields. It is predominantly composed of meta-volcanics with minor intercalations of meta-sedimentaries. Alkali-SiO2 and Zr-P2O5 diagrams, immobile element trends, and an iron-rich trend on the AFM diagram indicate that the volcanic suite is low-potassium tholeiitic basalt. The lower Mg number, MgO-TiO2, MgO-Ni, and Ni-Zr plots reveal that the basalt was derived from a fractionated, highly evolved magma generated by 10-20% melting of the mantle at 1100°C and 5 kb pressure. The chemical variations suggest that the Hutti metabasalt represents volcanic arc rocks generated at a converging plate margin.

Jan 1, 1993

By J. H. Lalor

The Olympic Dam deposit was discovered in July 1975 with the intersection of 38 m (125 ft) of 1.05% copper in diamond drill hole RD 1. A further eight holes were drilled with only marginal encouragement to November 1976 when RD 10 cored 170 m (558 ft) at 2.12% copper and an economic discovery was confirmed. The discovery of Olympic Dam is an excellent example of the application of broad-scale scientifically based conceptual studies to area selection combined with the backing of an exploration management willing to support its exploration scientists in testing their ideas with stratigraphic drilling. It also illustrates the persistence required in mineral exploration. The project began in 1969-1972 with the development of a conceptual model for the formation of sediment-hosted copper deposits. This model suggested that the alteration of continental-type basaltic rocks could release copper into solution from which it could be concentrated in favorable stratigraphic positions. In mid-1972, this concept was applied to a review of the Proterozoic and Lower Paleozoic rocks in South Australia aimed at defining targets for stratigraphic copper deposits.

Jan 1, 1991

By K. A. Natarajan, Abha Kumari

In this paper, electroleaching and electrobioleaching of ocean manganese nodules are discussed along with the role of galvanic interactions in bioleaching. Polarization studies using a manganese nodule slurry electrode system indicated that the maximum dissolution of iron and manganese due to electrochemical reduction occurred at negative DC potentials of -600 and -1,400 mV(SCE). Electroleaching and electrobioleaching of ocean manganese nodules in the presence of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans at the above negative applied DC potentials resulted insignificant dissolution of copper, nickel and cobalt in IMH2S04 and in sulfuric acid solution at pH 0.5 and 2.0. Mechanisms involved in electrobioleaching of ocean manganese nodules are discussed. Galvanic leaching of ocean manganese nodules in the presence of externally added pyrite and pyrolusite for enhancement of dissolution was also studied. Various electrochemical and biochemical parameters were optimized, and the electroleaching and galvanic processes thus developed are shown to yield almost complete dissolution of all metal values. This electrobioleaching process developed in the laboratory may be cost effective, energy efficient and environmentally friendly. Keywords: Ocean manganese nodules, Electroleaching, Electrobioleaching, Galvanic interactions

Jan 1, 2003

By S. K. Pan, R. Venugopal, L. A. Kumaraswamidhas, Rakesh Prasad, Chandan Pandey

Cold compressive strength (CCS) and apparent porosity (AP) of pellets are essential properties regarding the burden of blast furnaces. The optimal required values for industries are 2.5 KN CCS and 21% AP. Blaine fineness and firing temperature are the decisive parameters analyzed here. During firing, microstructure phases such as silicate, hematite, and pore are formed. The phase’s grain density during induration influences the pellet’s CCS and AP. The influence of the factors over the response is evaluated by I-optimal (response surface methodology) design. Blaine fineness, firing temperature, pore phase grain density (PPGD), silicate phase grain density (SPGD), and hematite phase grain density (HPGD) affect the CCS and AP of pellets. The RSM-I-optimal predicted responses with a coefficient of determination (R2) of 0.89 for CCS and 0.91 for AP of iron ore pellets. Optimal conditions were Blaine no. = 1668 cm2/g, 1250 °C firing temperature, PPGD value 90 no/mm2, SPGD value 250 no/ mm2, and HPGD value 490 no/mm2, with 4.5 KN CCS 27%. The induration processes were investigated through statistical design of experiments for process optimization. Statistical analysis indicated the direct and interactive influence over CCS and AP. In this study, RSM-I-optimal modeling is used for iron ore pellets processing. The I-optimal prediction could be applied to make the process economical because information is obtained through fewer experiments.

Aug 18, 2020

By Tim M. Benson, Adam L. Lamanna, Carolina Martinez-Gutierrez, Mark J. Stephani

The Lower Concourse C Extension (LCE) 108-in Storm Sewer consists of a 2,797-foot long, 27 to 55-foot deep, 108-in I.D. storm sewer tunnel. Situated beneath active taxiways and a terminal apron at Hare International Airport (D), the tunnel diverts ows from existing storm sewers located within the footprint of a future satellite concourse. The project was delivered via Construction Manager at Risk (CMAR) as part of Chicago Department of Aviation’s (CDA) ongoing O’Hare 21 Capital Program. This paper presents project details, multiple stakeholder coordination, subsurface risks and challenges, TBM performance, and impacts to existing infrastructure.

Jun 23, 2024

By R. L. Miller

The potential for recovery of enriched uranium from spent nuclear fuel which has been consolidated into a nuclear waste form was explored in the studies reported here. The waste form of interest is iron-enriched basalt (IEB)--a silicate-based, fused-cast ceramic. IEB samples were prepared containing fuel assembly materials that simulate the core debris of Three Mile Island Unit II;1,2 the nominal composition of the consolidated waste form is given in Table 1. Ore Types The IEB samples, or man-made uranium ores (MMUO), are in two different mineralogical forms. Each MU0 was made by melting the constituent materials and holding at about 1500°C for 1 h. The MMUOs were then heat treated to control crystallization and crystal growth and then cooled to room temperature.

Jan 1, 1983

By G. A. Plakhin, A. V. Luganov, V. A. Luganov, G. V. Gorbatenko

In order to extract gold from the complex sulphur-arsenic bear­ing raw materials and to remove arsenic and sulphur from the process in an ecologically safe form we have studied oxidizing roasting of highly arsenic gold bearing concentrates with soda, leaching of cinders, processing of the obtained solution and extraction of gold from the cake. There were processed concen­trates containing from 5 to 28% of arsenic, 12-20% of sulphur in the form of pyrite and arsenopyrite. The content of gold in the concentrates was 4-75 git. The roasting temperature was changed in the range of 773-l 173K, the consumption of calcined soda was 75-200% of stoichiometric necessarily for bonding of arsenic and sulphur into the water soluble compounds, the dura­tion of the process was varied in the range of 10-120 minutes. Under roasting in optimal conditions up to 97% of arsenic and 95% of sulphur go into water soluble compounds. The out­put of cake is 65-70% of the concentrates. The extraction of gold from the cake is higher than from the raw concentrates. The technology has been tested on a pilot plant scale

Jan 1, 1996

By James E. Monsees, Richard J. Proctor

INTRODUCTION Los Angeles is one of the world's largest cities in area with a span of 70 km between its north and south limits. The population in the Los Angeles Basin exceeds 11 million people. Los Angeles is second only to New York City in density of U.S. urban population and it operates one of the largest city bus fleets in the world, 2,500 buses. After many years of planning and many consultants' reports, it is planned to initiate a 30 km (18.5 miles) starter line subway -- the "Wilshire Corridor" (Figure 1). Construction is to start in 1985. In several locations, subway routes ultimately will skirt or cross old oil fields, which may cause gassy tunneling. Of particular note are the La Brea Tar Pits, which overlie a part of the old Salt Lake oil field. Tunneling through tar sands for about 3 km will be unique for subway construction and will occur on the starter line. Experience with previous gassy tunnels in the greater Los Angeles area shows that tunnels can be completed safely if precautions are taken. Abundant ventilation is the main solution, although other precautions are discussed herein.

Jan 1, 1985

By Paula N. Wilson, W. T. Parry

Carbonaceous and metalliferous black shales occur in close proximity to Mercur-type gold deposits in the southern Oquirrh Mountains, Utah. These shale units, the Manning Canyon shale and the Long Trail shale, have undergone regional hydrothermal alteration. Hydrothermal solutions oxidized organic matter and pyrite, replaced shale by hydrothermal phyllosilicates and silica, and replaced fossils by phyllosilicates. The shales are depleted in organic carbon, calcium carbonate, alkali and alkaline earth metals, and enriched in aluminum and hydrogen. Hydrothermal veins containing illite, chlorite, pyrophyllite, kaolinite, Fe-oxides, and sulfides are present throughout the study area.The illite in veins is an ammonium illite that contains up to 2 % NH4 and is correspondingly depleted in K. Correlations among Au, As, Hg, TI, Sc, and rare earth elements indicate that hydrothermal fluids responsible for formation of ammonium illite were gold bearing. K/Ar ages of illite veins and illite-rich, clay-size separates of altered shales indicate hydrothermal activity occurred in the time range 193 to 122 Ma. Several ages from clay-size separates within the Mercur district cluster near 160 Ma. These ages are coeval with thrust faulting recognized to the north and west.

Jan 1, 1990