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By M. Schreiner, J. Brune, D. Theisen, C. S. -J. Tsai

This study reports that routine mining activities could produce a high number of nanometer sized particles which have not been well characterized and may represent an unacknowledged exposure present in the mining environment. A preliminary survey of the particle emission from the feed-leg drilling activity was conducted in the excavations of an experimental mine. The level of particulate exposure was monitored by real time direct reading instruments include a NanoScan scanning mobility particle sizer (measurement range 10-420 nm) and an optical particle sizer (measurement range 0.3-10 μm). Particulate morphological and structural examination was conducted through transmission and scanning electron microscopy and x-ray dispersive analysis of samples collected by a thermophoretic sampler, and a novel nanoparticle sampler. The real time instrument data revealed high concentrations (> 3.5 x 106 particles/cm3) of ultrafine/nanoparticles generated from the drilling activity. Analysis of particle sampler specimens with energy-dispersive x-ray spectroscopy showed a large amount of submicron silica, spherical primary particles and agglomerated soot particles rich in carbon. Exposure to particles in the nanometer size from various sources within the mining environment may be associated with the poorly understood rise in respiratory and systemic disease among miners. INTRODUCTION Exposures to mine dust have been measured and evaluated for decades. Exposures to aerosolized dust such as coal or silica particles can cause lung and other diseases (1-7). One way that The Mine Safety and Health Administration (MSHA) characterizes inhalation exposures within the mining environment is through measuring the respirable dust mass concentration within the breathing zone of workers (8). Respirable particulate matter (RPM) is of great concern due to its ability to deposit in the alveolar region of the lungs (9-10) where it can affect respiratory function. Interventions championed by MSHA have greatly reduced the prevalence of coal workers pneumoconiosis (CWP) and progressive massive fibrosis (PMF). Although great progress has been made, the prevalence of CWP and PMF appears to be trending upwards and the measured increase in prevalence is not elucidated in RPM measurements (11-12). Though the presence and risk associated with ultrafine particles such as emission from diesel engine within the mining environment has been previously established (13-14). There is suspicion within the mining industry that this resurgence of lung disease may be due to very fine particulate matter from various source that is not properly characterized by current sampling methods. Nanometer sized particles, in the range of ultrafine particles, fall within the RPM size range and have been found to deposit in all regions of the respiratory tract (15). Nanoparticles are commonly accepted as particles that are greater than 1 nm in two or three dimensions but smaller than 100 nm (16). Once in the lungs, nanoparticles can enter the blood stream (17) and selectively affect other target organs such as the heart, liver, bone marrow, lymph nodes, spleen, and brain (15,18-19). The size of nanoparticles has been shown to correlate with their translocation behavior on secondary target organs (20-21). There is strong evidence that the clearance mechanisms used to rid the lungs of particulate matter are not as effective on nanometer sized particles, leading to a greater fraction of never-cleared particles which may enhance disease development (20). Research has demonstrated that nanometer sized particles have unique properties (22) whose adverse health impact is greater than what has been found with micrometer sized particles of the same type (23-26). The large ratio of surface area to mass compared to larger particles is believed to make nanoparticles a greater hazard. Utilizing mass to measure these types of exposure will be very difficult to accurately characterize the quantity of

Jan 1, 2019

By M. K. Mohanty

A modified coal flotation characterization procedure, referred to as the Advanced Flotation Washability (AFW) technique, has been developed which, compared to traditional procedures, provides a more accurate prediction of the optimum separation performance achievable by a froth flotation process. The AFW procedure uses a vertically-baffled flotation column which provides enhanced selectivity among particles of varying degrees of hydrophobicity due to a plug-flow environment and an improved carrying-capacity environment. In fact, the separation performance of the traditional procedures was enhanced by increasing the possibility of operating under improved selectivity conditions. The separation performance provided by the AFW procedure was superior to that obtained from multiple cleaning stages using commercially-available flotation columns under both kinetic and carrying-capacity limiting conditions.

Jan 1, 1997

By Miche1 Dagbert

In most open pit operations mining porphyry type deposits, production planning rests on an are reserve inventory block file which is derived from diamond drill hole data. With such a practice, the way by which block values are generated is critical and in the recent years many studies deal with the comparison of different estimation methods for block grades (Mueller, E. (1), Knudsen et al (2) (3), Barnes, (4), Williamson and Mueller (5). Typically in such studies, one selects a bench or a group of benches where there is a "sufficient" number of blast holes (BH) with assay values in each of the blocks (generally 30.5 x 30.5 m (100 x 100 ft) or 15.2 x15.2 m (50 x50 ft). Then the arithmetic mean of the BH values in each block is computed and it is assumed to represent the real block grade against which different estimated values are compared. However it is sometimes observed that the variation of these BH values within a block is high and that their arithmetic average may significantly differ from the real average grade of the block (Barnes (4). The problem of the precision of the mean BH grade in a block has been examined by Williamson and Langlois (6) in an experimental way. They strove to find a better estimate of the average block grade than the mean BH grade but their results were not conclusive. The purpose of this study is to investigate the same problem within the frame of geostatistical models (David (7). Besides practical results obtained with these models, two general points are emphasized and illustrated in the text. First, "good results" are obtained if "good geostatistics" is done (David et al (8).

Jan 1, 1978

By Terry O. Arney

This paper is a description of the digital Data Acquisition and control System that is installed at Cities Service's Pinto Valley Concentrator. Pinto Valley Concentrator ? The Pinto Valley Concentrator (5, 41 is located approximately seven miles west of the town of Miami, Arizona. The Concentrator is situated south of the open pit mine and was designed to process 40,000 tons of ore per day with an average grade of .45% copper. The comminution process consists of primary, secondary, and tertiary crushing, and single-stage closed-circuit grinding 161. Concentration of the copper sulfides is by means of froth flotation. Concentrates are transferred to the Inspiration Consolidated Copper Company smelter in Miami, Arizona through a slurry pipeline.

Jan 1, 1976

By R. Owens, C. Roos, B. Hill, S. Rosenthal

It is common practice, and even legally required in many jurisdictions, to design two-lane haul roads in open pit mines to three and a half times the widest dimension of the haul trucks operating on the road. In open pit gold mines with high strip ratios, the road width has a significant impact on the economics of a design. It is possible to minimize the flattening of the highwall if the road width is reduced, assuming the width used is not needed to flatten the slopes for geotechnical purposes. With the use of autonomous haulage and pullouts, it may be possible to operate safely and efficiently on a reduced road width of two times the width of the hauling equipment.

Mar 2, 2022

By T. Skodack

This presentation will compare actual work site results for the loading and transport of shot rock for two major tunneling projects in North America. "SCARMAR" (the Canadian subsidiary of S & M Construction) is operating a rail bound Hagglund continuous gathering arm loader in combination with a Hagglund nine car shuttletrain system at the West End of Table Mountain on the B.C. Railway project near Tumbler Ridge, Canada. Al Johnson Construction is operating a Hagglund rubber tired continuous gathering arm loader in combination with haul trucks at the Rocky Mountain Pump Storage Project near Rome, GA. This paper will compare: 1) tunnel and ground conditions, 2) the total work cycle as it relates to mucking and haulage 3) efficiencies and related problems with the two systems 4) mucking and haulage rates 5) operating costs, and 6) recommendations for future large tunnel excavations. Manuscript not received in time for publication.

Jan 1, 1983

By Arthur L. Raub

During the last decade, there haven't been any great innovations in the design features of a copper concentrator. What has worked well in the past continues to work well, so that major breakthroughs have been minimal. Conservatism in the ranks also plays an important part. As a copper concentrator is not designed and built everyday, Davy was elated to have an important part in this project. This is the story of the design of the oracle Ridge Project located north of Tucson on the back of Mt. Lemmon at an elevation of 5,900 feet on the N.E. slope of the Catalinas. The Oracle Ridge property, formerly known as the Control Mine, is owned by Oracle Ridge Mining Partners, a joint venture between Continental Materials Corp. of Chicago and Union Miniere of Brussels, Belgium; both or¬ganizations specializing in the non-ferrous metal industry.

Jan 1, 1979

By L. M. English

A basic model has been developed to help assess methane control needs for longwall mining of coal in gassy areas. Rather than depending upon reservoir and rock mechanic theory, it uses an empirically-determined gas emission rate as an input and operates on the assumption that, within a specific region and zone, gas emissions will be relatively equivalent for uniform incremental volumes of gob created by mining. The computer program divides longwall panels into segments, keeps track of the face advance, and generates emission rates and volumes for both the entire panel and for individual zones within the panel by summing values for all undermined segments. This model can aid the determination of the number, size, and location of vertical wells or other methane control applications that are needed for gob gas control.

Jan 1, 1998

By P. G. Irwin

Natural resins, those derived from coal and those mined in the Uintah basin, face challenges from synthetic resins that are derived from petroleum sources and rosin or wood sources. In the past, fossil resins from coal were produced by various companies, the last one being Hercules, Inc., which sold BLACKHAWK resin until a fire destroyed the plant in the mid 1970's. Approximately four to fjve million pounds of BLACKHAWK were produced and sold mostly to the printing ink industry. Uintaite, more commonly known as Gilsonite® resin, was widely used by various industries, notably in printing inks, coatings, stains, adhesives, foundry, asphalt paving, and oil well drilling muds. Gilsonite has lost market share over the last thirty years to various synthetic resins particularly hydrocarbon resins that are derived from petroleum sources.

Jan 1, 1990

By F. Mielli

Over the last three years there has been an increase in mining congress and conferences focusing on water management. Water in mining is a key concern for mine managers and operations, and we are now seeing this operational dilemma escalated to the level it deserves. According to Frost & Sullivan research, mining water and wastewater treatment and its related technologies will be a U$3.6 Billion global market in 2016, which translates the importance of this issue. Looking at the current mining trends, some factors increased the importance of water in mining operations, including: ? Future mining investments will be located in geographical locations where water is scarce (water stressed areas) ? A decline in grade will increase the intensity of mineral processes and therefore increase the use of the water ? Increased sustainability and regulations will extend the control/monitoring of water during the entire mine life cycle representation of the mine water flow system. A water balance has several benefits/objectives in a mine operation: ? Mine planning/simulation of mining scenarios/climate change Production optimization ? Minimizing strategic and operational risks ? Social license to operate ? Water-smart mine planning ? Target: water neutral mines ? Benchmarking within and between sites ? Sharing knowledge/technology transfer ? Reporting/communications ? Permitting/Compliance

Feb 23, 2014

By G. F. Weaton

1.1 The purpose of this paper is to show the way by which estimates are made of the tonnage and grade of iron ore and taconite reserves of Minnesota. 1.2 The procedures include those of estimating the open pit reserves of: (a) Natural iron ore, and (b) Taconite 1.3 The methods of estimation which will be discussed are primarily based on the information from exploring iron ore deposits. They consider the geology of the deposit as well as the contained mineral of potential value. 2.0 Some geologic, engineering, and economic principles. 2.1 Ore 2.11 "In the broad economic sense, and from a legal standpoint as well, ore is mineralized rock, which under appropriate conditions of time, space, technology, economics, and politics, can be mined, processed, and made to yield a saleable metal , or other mineral products at a profit."(Parks, 1957) Stated differently, metallic ore is rock material from which presently known methods of beneficiation, a merchantable concentrate, suitable for use in the manufacture of metals at a profit, can be produced. Crude ores as low as 0.38% metal, as in the case of copper and even lower in the case of the precious metals.

Jan 1, 1985

By Ihsan Berk Tulu, Mark Alexander Van Dyke, Deniz Tuncay, Ted M. Klemetti

Bleeder entries are critically important to longwall mining for the moving of supplies, personnel, and the dilution of mine air contaminants. By design, these entries must stay open for many years for ventilation. Standing supports in moderate cover bleeder entries were observed, numerically modeled, and instrumented by researchers at the National Institute for Occupational Safety and Health (NIOSH). The measurements of the installed borehole pressure cells (BPCs), standing support load cells and convergence meters, and roof extensometers are presented in this paper in addition to the numerical modeling results and visual observations made by the NIOSH researchers in the bleeder entries. The results include the effects of multiple panels being extracted in close proximity to the instrumented site as well as over one and a half years of aging. As expected, standing supports closer to the longwall gob showed the greatest load and convergence. The roof sag appeared generally independent of the proximity to the longwall gob. The BPC readings were driven by both the proximity to the gob and the depth into the pillar. The results of this study demonstrated that the entry roof can respond independently of the pillar and standing support loading. In addition, the rear abutment stress experienced by this bleeder entry design was minimal. The closer the mine development, pillar, or supports are to the gob, the greater the applied load due to rear abutment stress.

Jan 7, 2021

By J. Appleby

This paper reviews earlier in-plant testing at the Sidbec-Normines pelletizing plant at Port Cartier, Quebec, Canada. It describes the result of the more prolonged use of coke breeze during recent months and in addition, the effects of varying dolomite and coke additives upon the metallurgical properties of the pellet production have been studied. Mention is also made of some brief test work carried out to use peat moss as a carbonaceous additive to the pelletizing process and in particular the plans for future work in this respect. Earlier laboratory pot-grate test work had indicated that a production rate increase of between fifteen and twenty percent was a practical possibility, or alternatively that the plant could be run at design rating with significantly lower energy consumption. These energy reductions were of the order of ten to fifteen percent for fuel and main process fan power respectively. The physical and metallurgical pellet properties for both blast furnace and direct reduction furnace use were little affected by the production rate increases, and were actually somewhat improved when practicing maximum energy conservations. Pellet properties could be further improved by not extracting the maximum energy economy. Two phases of carefully controlled in-plant testing were run to assess the effect of energy conservation under plant conditions. These two phases of testing confirmed that an overall fuel saving of approximately fifteen percent could be realized, with a reduction in the Bunker C oil consumption of about forty-five percent, and a reduction in main process fan power of approximately ten to fifteen percent. The present scope of work is aimed at establishing the use of varying levels of coke addition up to about one percent under normal plant operating conditions.

Jan 1, 1980

By P. A. Cornejo

Blastings always generates induced vibrations through seismic wave, these are lost energy from the blasting and therefore causing the disturbance of slopes and structures near the blast source. Most of the components of an open pit mine have to reach a physical stability, especially during its closure process. Aiming to develop a vibration prediction model using the historical records from an open pit mine located on Peru, this research has two main focuses depending on the distance from the blast source to the structure: to protect the final slopes and to protect the villagers houses. Both are based on the Devine model of the Square Root Scaled Distance (SRSD) to predict the Peak Particle Velocity (PPV). The Mid field model, where is found mainly final slopes from the pit, limited by the failure criteria of McKenzie based on the geo mechanical properties of the rock mass. The Far field model ranges distances where are located the most community households, limited by the German rule DIN 4150 for highly sensitive structures. Both scenarios resulted on a distribution abacus to limit the weight of used explosives to get the best operational advantage and structure safety.

Mar 2, 2022

By V. P. Mehrotra

The effect of dissolved ions present in plant water on the flotation of phosphate ore from central Florida was investigated. Of the three most abundant ions, namely Ca++, Mg++ and SO4--, calcium ions were the most detrimental in the flotation of phosphate with sodium oleate collector. In one feed, a 10 ppm concentration of Ca++ ions reduced the BPL recovery from 86% to 46% whereas in the other a 40 ppm concentration lowered the recovery from 90% to 52%. The effect of Na2C03, NaHC03, Zeolite and EDTA to remove ca++ ions from water and hence improve apatite flotation was also studied.

Jan 1, 1986

By L. H. McGuire

Many coal beds in the State of Washington, pitching as much as 90°, offer unusual mining conditions. This paper describes methods and safe practices of mechanized mining in pitching bituminous-coal beds that have attracted the attention of mining people from most of the coal-producing countries of the world. The development and use of continuous miners as part of the mechanized program apply particularly to the Roslyn-Cle Elum coalfield, Kittitas County, Wash. All three mines now operating in the field use continuous miners and during 1957 furnished 72 percent of the State's total coal production. Mining operations are now conducted in three coal beds of the Roslyn-Cle Elum field. The coal measures range from 3-1/2 to 20 feet in thickness and vary in dip from 5° to 45° in the localities where the coal is mined. Some safety measures adopted by-the principal operating company in the field during the past 30 years of mechanized mining follow: Use of only permissible electrical or compressed-air-operated equipment on other than intake air; providing and using an explosion gallery to test repaired permissible electrical equipment before taking it underground; use of only compressed-air-operated drill augers in preference to permissible

Jan 1, 1959

By C. O. Petter

This paper, in its first part, compares the profile and economic weight in the extraction of industrial minerals and aggregates to the so called conventional mining activities (metals, coal, gas and oil extraction) in Brazil. In its second part, a descriptive analysis of the present situation of the education in Brazil is made, emphasizing the graduation and post-graduation formation especially in engineering. The curricular structure of the schools that prepare the mining workforce is discussed and the presence of specific subjects in industrial minerals is evaluated. Finally, considerations are made on the actions being taken in the main universities and companies, aiming to improve the formation of the specialized workforce. The Brazilian mining production, comparing 2010 to 2011 showed an expansion of more than 3% (IBGE, 2012). Not bad, but nothing to do with the 13% growth between 2010 and 2009 (influenced by a recovery effect from the 2008 commodities? nightmare). The commodities that had a rising behavior were titanium, gypsum, nickel, graphite, bauxite, phosphate, chrome and chrysotile. All of them were eclipsed by the impressive growth of iron ore production. Some decreases could be noticed, eg. in zinc, kaolin, magnesite and salt production (DNPM, 2012). In fact, the mining activities followed the positive growth of the country these last 5 years. The commercial balance (exports against imports) was not spectacular (positive in US$ 30 billion in 2010). It is important to notice that the mineral commodities balance was US$ 35 billion, representing 27.4% of the total exports and 15.6% of the total imports of Brazil (DNPM, 2012). In this positive environment, the workforce in Brazil showed progress in number of formal jobs and average revenues.

Feb 23, 2014

By Yuchen Wu, Jing Mei, GUOZHONG LIU, KE GAO, Songjie Tian, Jianwei Cheng, Yu Wang, Yuhang Wu, Hui Wang

The stability and integrity of protective coal pillars between the longwall working face and development roadways are greatly affected by the mining activities such as the development face advancing or retreat mining. Due to underground strata pressure, the coal pillar cracks could be further developed and then the air leakage passages (mainly cracks) could be produced greatly. The air circulation caused by the atmospheric pressure difference between the two sides of the coal pillar may also provide suitable conditions for the possible spontaneous combustion of the residual coal in the mine gob. In this paper, a typical the protective coal pillar in a Chinese coal mine is studied. The deformation and stress of coal pillars during the mining process of longwall working face are simulated by using FLAC3D. The displacement and strain of coal pillars are analyzed. Two indexes, the linear fracture rate (LFR) and area fracture rate (AFR), are introduced to characterize the development of internal cracks’ development within coal pillars. By using field measurement, the air leakage intensity distribution due to coal pillar cracks is obtained; the equation of air leakage resistance of coal pillar under the influence of mining is derived. Then, the possible location of large air leakage of coal pillar is determined, which can be used as guidelines to study the possibilities of coal spontaneous combustions happening in pillar or mine gob. The research results help to control such potential hazards in advance.

Jun 16, 2022

By Stanley V. Lachmansingh

Bauxite can be regarded as a mixture of hydrated aluminium oxides the predominant constituent - and oxides of iron and titanium, silica and silicates. Heterogeneous and non-crystaline, most bauxites vary in average composition from one deposit to another both in terns of impurities as well as the proportion of Gibbsita and the Monohydrates Diaspore and Boehmite. Iron levels (as Fe2O3) can vary from less than 1% to as high as 30% with the alumina content ranging from 40 to 6o%,. Gore than 90% of all bauxite mined in Guyana is used as feed for the - production of refractory grade calcined bauxite. There are -however, several speciality grades used in various industrial applications and these are characterised by the quality of the bauxite in particular ;,with regards to iron and silica levels which generally have to be low. The main speciality grades are designated Refractory, Abrasive and Chemical. Bauxitte is also used in the production of nigh alumina cements,, activated bauxite end in the manufacture of electrical insulators.

Jan 1, 1977

By MARK J. VANARELLI

Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates.

Jun 13, 2021