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By A. M. Galperin

Back analysis is a very important procedure for proper understanding of physical processes. Back analysis can be used to establish the role of different factors, define parameters to be calculated and formulate the behavior of natural or physical processes based on field experimental results. It is evident that, in order to obtain the necessary data for back analysis, field observations are required. For the Michailovsky region (Kursk Magnetic Anomaly, KMA) the long-term strength characteristics of the clay covering the quarry slopes were established with the help of back landslide calculations. The obtained data allowed quantification of the shearing resistance parameters at the presence or absence of intermittent dips of discharge in the pit bank massif structures. Based on the results of investigation for material composition, strength and deformation of finely dispersed (clay-chalk) deposits in the Kursk Magnetic Anomaly including measuring of the settlements of filled structures, complex probing and laboratory determination of water-physical and mechanical properties of "man-made" soils, engineering-geological zoning of filled structures was carried out.

Jan 1, 2005

By Donald E. Ralston, V. Rajaram, Michael N. Greeley, John W. Peters, Terry J. Laverty, F. S. Kendorski, Peter G. Chamberlain, J. Brent Hiskey, William C. Larson

Preliminary figures from the US Mine Safety and Health Administration show 801 underground metal mines and 490 surface metal mines, at the end of 1981, up from 663 and 383, respectively, in 1980. Preliminary MASH figures also show 207 underground nonmetal mines and 1070 surface nonmetal mines at the end of 1981, compared with 167 and 1092, respectively, last year. In addition, preliminary MASH figures show there were 14,676 mineral extraction operations on the surface and 3845 underground at the end of 1981, versus 14,951 and 3675, respectively, for last year. The number of mines, then, in three of four categories increased significantly, while having a lower net total of just 2% in the other category. And the number of underground extraction operations increased nearly 5% for the year, while surface operations were down less than 2%. But despite operations totals that mostly held their own or showed significant increases, it was a tough year for the nation's mining industry. The nonferrous segment of the industry had a bad year and 1982 may be no better, according to Business Week (Jan. 11, 1982), which adds that a turnaround is impossible unless the general economy recovers. Even then, with diminishing markets and overcapacity plaguing its products, the mining industry's condition "will be far from robust," the magazine says. The basic problem is that nonferrous metals-aluminum, copper, lead, molybdenum, nickel, and zinc-are tied to the most troubled sectors of the US economy. As recently as 1979, for example, more than 40% of all aluminum shipments went to the construction and transportation industries. Last year, these markets were down to 35% of aluminum shipments. And molybdenum sales to steel producers dropped by nearly 15% last year. Moreover, nonferrous products ended 1981 at disastrously low prices. Molybdenum oxide sold at $8.77/kg ($3.98/lb), half its $17.63/kg ($8/lb) price earlier in 1981 and aluminum was listed at $1.08/kg ($0.49/lb), compared with $1.54/kg ($0.70/lb) a year earlier. The Comex price of copper was $1.54/ kg ($0.70/lb), down from $3.11/kg ($1.41/lb) in early 1980, in real terms the worst copper price in 30 years. Lower prices led operators to cut their output and increase layoffs, shut down mines, and defer capital spending projects. In December, Duval Corp., a Pennzoil Co. subsidiary, shut all four of its US copper mines until March. Aluminum Co. of America had laid off 7.3% of its work force, shut nine of its 38 smelting lines, and entered 1982 operating at only 68% of capacity. Inco Ltd., the Free World's largest nickel producer, lost money in 1981, an estimated $11 million, for the first time since 1932. And, like Falconbridge Nickel Mines and other major nickel producers, had cut back on nickel production and was operating at only 63% of capacity (Forbes, Feb. 15, 1982). Amax, the country's largest molybdenum producer, had cut production by 20%. And Hanna Mining Co. sold lead for $5.07/kg ($2.30/lb), about $1.54/kg ($0.70/lb) below what it cost to produce. Another problem is that copper companies in the next few years must come to terms with problems of aging smelters. Some companies are simply closing them. In 1980, Anaconda closed its 75-year-old Butte, MT, smelter and is shipping concentrates to Japan, rather than modifying the smelter to meet environmental requirements. And oth Phelps Dodge Corp. and Asarco Inc. have antiquated smelters on which they will have to make decisions. The most troubled metal in 1982, Business Week said, will be molybdenum, with no real recovery in sight until the mid-1980s. High molybdenum prices in the late 1970s, caused in part by shortages, triggered overexpansion that will take years for the US market to soak up. On a more upbeat note, 1981 mergers might help stabilize the industry by providing funds for mining companies. Standard Oil Co. (Ohio) said it plans to spend $7 billion on Kennecott during the next 10 years for modernization and expansion. And Atlantic Richfield Co. said it will spend $500 million on Anaconda Copper Co. during the next five years. Another positive note was sounded by T. H. Adams of the United Banks of Colorado Inc. He said he expects the mining industry to experience moderate growth in 1982, led by "interest rate sensitive" demand from energy, electronics, and defense markets. And mining will be helped by "weak, but improved" construction and auto markets. The mining industry will be operating in an economy stronger than 1981, but still relatively sluggish by postwar standards, Adams predicted. Iron Ore Estimated US iron ore production in 1981 was 75.2 Mt (74 million long tons), up 6% from 70.7 Mt (69.6 million long tons) in 1980, though down from the 87.1 Mt (85.7 million long tons) produced in 1979. The mine value of usable iron produced from domestic mines was estimated at $3 billion. US iron ore was produced by 28 companies operating 35 mines, 26 concentration plants, and 16 pelletizing plants. The mines included 34 open pits and one underground mine. Byproduct ore recovered from copper- and titanium-mining operations accounted for less than 1% of total iron ore production. Fifteen mines operated by nine companies accounted for 94% of total

Jan 5, 1982

By Jürgen Kretschmann

According to the model of product life cycles, the global coal mining industry is in the stagnation phase. The coal demand of the main consumer, China, has peaked in 2013 and is slowly declining. The Norwegian sovereign wealth fund, the world’s largest, has excluded coal-related companies for ethical reasons. Important players like the UN or the EU have already begun to describe pathways towards decarbonization. Increasing competition between coal mining companies and the mining regions can be expected worldwide if companies want to keep their positions on the global and national coal markets. Companies will focus on the best deposits. European countries like France, Spain, or Germany are only forerunners of this development—their centuries of coal production have been finished. The concept of sustainable development (SD) is fundamentally based on a model of progress where ecological, economic, and social dimensions should be developed equally and positively. But without the idea of competition, the concept of SD is incomplete. Questions arise, such as how can SD be realized on stagnating or declining markets without guarantees for companies “to live forever”? How can SD be a corporate goal in a phase of decline? How can declining mining regions sustainably progress into a better future? The German hard coal mining industry’s lifecycle has ended in 2018 after 60 years of stagnation and decline. As of 2019, all hard coal consumed in Germany will be imported, especially from Colombia, Russia, and South Africa. What has been done in Germany to handle the coal decline in a sustainable way and the lessons learned from this process is described in this paper. It may be useful for mining regions who will face a similar future sooner or later.

The Northside Storage Tunnel Project in Sydney includes over 20 km of TBM driven tunnels, over three km of declines and major caverns and pump rooms. The paper describes methods used for design on the project. Emphasis is given to the refinement of the use of empirical rock mass classifications, and to the use of discontinuum numerical methods. The use of empirical rock mass classifications in Sydney sandstone has usually led to conservative design because the systems are based on a random orientation of joints in the rockmass. Because the joint sets are usually oriented in a way that is beneficial for tunnelling, limits must be placed on the parameters used in the classifications system. The paper discusses these limits and the derivation of the parameters. The use of numerical methods in Sydney sandstone is discussed. Continuum methods have their uses, but discontinuum methods are preferred. The use of UDEC has been validated against a previous project, the New Southern Railway. Recommendations are given for UDEC models. In Sydney's geology, so advantageous for tunnelling, the challenges of this project have been to make the best use of the good conditions, while maintaining safety for the workforce and the future operators of the project.

Jan 1, 1999

By T. Bednarski, T. McCallum, L. Moya, B. Gay

"Molybdenum recovery by solvent extraction has gained interest partly due to advances in concentrate leach technology. Historically, both molybdenum and rhenium have been produced using amine-based extractants with the ability to co-extract both metals. Alternatively, a phosphinic acid-based extractant (CYANEX® 600) can be used depending on the flow sheet. CYANEX® 600 selectively extracts Mo leaving Re in the raffinate, which is a valuable feature in plants which require rejection of the rhenium from the molybdenum circuit. CYANEX® 600 piloting results are reviewed and compared to commercial experiences with an amine-based extractant. INTRODUCTION Molybdenum is most commonly found as molybdenite (MoS2) in primary porphyry deposits (about 59% of global reserves) and copper porphyries (about 39% of molybdenum reserves)[1]. Recovery from molybdenite traditionally involves flotation (concentrates typically containing 85 – 95% MoS2) followed by roasting to produce MoO3. Solvent extraction is also used to recover molybdenum from acidic aqueous solutions resulting from scrubbing of roaster and smelter off gasses and leaching of molybdenite (uranium ores). Molybdenum is also frequently found in low concentrations in copper leach inventories[2]. More recently, pressure oxidation has gained interest to treat molybdenite concentrates. Molybdenum Chemistry The chemistry of molybdenum is complex with a series of extractable species existing dependent on the pH and oxidation state as shown in Figure 1.Under strongly basic conditions, molybdenum primarily exists as MoO42- while under strongly acidic conditions MoO22+ becomes the predominant species. In between, a number of isopolymolybdates such as Mo7O246- and Mo8O264- are dominant. Equations (1) – (3) demonstrate some of the proposed molybdenum equilibrium reactions[1]."

Jan 1, 2017

By Ronald L. Wiegel

In a mineral processing plant there are a number of routine decisions which are based at least in part on the plant's metallurgical performance. Among these are those related to: 1) equipment functioning properly 2) suitable operating conditions 3) reagents achieving desired results 4} determining operating response to changes in ore 5) defining circuits offering potential for improvement A step beyond the routine, are the periodic management evaluations of operating supervision and technical assistance, which are based largely on profit -a direct function of are availability, metallurgical performance and operating costs. The "yardstick", excuse me -"meterstick", by which performance is best measured is the plant metallurgical balance, which tells not only what was produced but how it was produced. Since this metallurgical balance is directly related to both plant profits and individual rewards, it is only reasonable to make that "meterstick" as precise as humanly possible.

Jan 1, 1978

By Savita Schlesinger, Mike Hanna, Nathan Scalla, James O’Shaughnessy, Steve Miller

Loudoun Water’s Quarry A (Milestone Reservoir) project involves conversion of a rock quarry to a billion-gallon raw water reservoir. The project includes a new 40 MGD pump station, deep intake shaft, and three drill and blast intake tunnels for accessing the reservoir. Due to concerns regarding constructability and construction risks, the project design was paused while a Construction Manager At-Risk (CMAR) contractor was procured. The CMAR contractor was engaged collaboratively with the design team to provide risk and constructability input for refining the design. Aspects of the original design, design modifications, and benefits of the CMAR collaboration will be presented.

Jun 13, 2023

By Ruichen Ren, Xu Han, Caixia Li, Zengchuan Yue

In this paper, the size-density distribution of coarse middling coking coal (CMCC) with different grinding fineness and flotation concentrates was investigated. Then, the flotation behaviors and liberation characteristics of different size-density fractions in ground CMCC were analyzed, and the different size-density fractions were divided into five categories: mostbeneficial, secondary-beneficial, poorly liberated, insignificant-pollution, and serious-pollution. Based on the content of particles with different liberation characteristics, an evaluation index of the liberation characteristic of ground CMCC, namely, the liberation perfection index (LPI), was proposed. The results indicated that grinding changed the size-density composition of CMCC, which affected the flotation performance. Insufficient grinding and overgrinding were not beneficial to flotation. Insufficient grinding caused a higher content of poorly liberated particles and a lower content of most-beneficial particles. Overgrinding increased the content of serious-pollution particles and reduced the content of most-beneficial particles. The size order of the LPI values of different ground CMCC was consistent with the flotation efficiency, and the LPI values of the other two similar samples were overall positively correlated with their flotation performance, suggesting that the method is universal.

Feb 14, 2023

By J. Gibson

"INTRODUCTION As one of the most pressing and important political debates of this century, climate change has captured global attention and is forcing governments to take action towards decreasing GHG and carbon emission levels below what was previously thought to be necessary. With the ever-increasing price of diesel fuel accompanied by the popular topic of carbon taxes and greenhouse gas emissions, the mining industry is looking to industry specialists for assistance. The benefits of a no-idle policy reach far beyond carbon reduction and fuel savings, ranging from decreased maintenance to increased engine life. With products like battery powered A/C systems and diesel-fired heaters, going no-idle is easier today than ever before. With both systems being manufactured to withstand the harsh environments of the mining industry, the end user will see a seamless change from conventional, inefficient belt-driven systems to future, stand-alone mobile equipment HVAC. THE HISTORY OF GHGS AND CLIMATE CHANGE In 1896 Svante Arrhenius first claimed that the combustion of fossil fuels may eventually result in enhanced global warming, but not until 1955 did Gilbert Plass draw global attention to global warming by summarizing that adding carbon dioxide to the atmosphere would intercept infrared radiation and thus warm the earth. Then in the early 1960’s Charles Keeling developed modern technology to produce concentration curves for atmospheric CO2 (Figure 1). In 1988 the Intergovernmental Panel on Climate Change (IPCC) was founded by the United Nations after acknowledgement of a rising global annual temperature. The IPCC consists of over 2500 scientific and technical experts from more than 60 countries, and because climate change could not be solved by a single country, the Kyoto Protocol was negotiated in 1998 requiring all participating countries to reduce their GHG emissions by at least 5% from the 1990 levels. The Protocol was signed by 186 countries in 2001 (since then several countries have retreated from the agreement, including the United States)."

Jan 1, 2015

By Clinton Birch

The multiple-criteria decision analysis is a technique that helps to find an optimal solution by evaluating conflicting criteria. In this study, an approach to perform multiple-criteria decision analysis for cut-off grade optimization, which considers the diverse stakeholder groups prevalent in the mining industry, is presented. The optimization model developed in this approach links the resource block model to the financial model, enabling the process to either maximize profit, net present value, revenue to the State, or extend the mine's life. To identify the optimal cut-off grade in each case, the Excel Solver function is utilized. Although it has limitations, the Solver function can still be modified to handle models with thousands of block values for determining input variables based on the target value. Following stakeholder engagement and dialogue, a single weighted average cut-off grade can then be determined. This approach is demonstrated for nine South African Witwatersrand gold mines.

Jun 25, 2023

By T. V. Johnson

The microstructural relationships in dolomitic fluxed taconite pellets were studied. The influence of basicity (in the range 0.75 to 2.1) and firing temperature (to 1340°C) on the grain structure, macrostructure, and mineralogical phase relationships are described. Extensive slag bonding of hematite grains begins at temperatures between 1220 and 1230°C, and results in fundamental changes in grain structure. Successive temperature increases result in little change in grain structure until 1340°C, when extensive coalescence of the hematite grains begins.' Increasing flux additions have little effect on grain structure but greatly influence pore character. The compressive strength decreases with increasing flux addition, increases with increasing firing temperature, and is related to the macrostructure of the pellet. The compositions of the slag phases are represented on the CaO-Fe2O3-SiO2 phase diagram, and the compositional path of slag development is described.

Jan 1, 1980

By RIINA SALMIMIES, Paula Vehmaanperä, Antti Häkkinen

The dissolution of iron oxides in mixtures of acids is fairly uncommon but can result in a more efficient dissolution process. The objective in this work was to investigate the dissolution of synthetic hematite powder in mixtures of oxalic and sulfuric acid. Experiments were done at different acid ratios and temperatures. An increase in temperature from 15 to 35 °C increased solubility, whereas an increase from 35 to 50 °C did not change the solubility but had a profound effect on the kinetics. An important finding was that oxalic acid advanced the dissolution process since increasing the amount of oxalic acid in the system resulted in faster kinetics and higher solubilities. The dissolution kinetics were well described with the Kabai model, which was the only studied model able to describe the whole reaction time. However, the solid specific constant a varied for the different acid ratios and this is argued to be a result of changes in the solid phase. The changes in the constant a were not in line with the original study of Kabai, which indicates that a cannot be the solid specific constant but it can be the constant connected to dissolving media describing the changes in the dissolution mechanism.

Sep 23, 2020

By Dongjie Zhang, Zeyu Liu, Shuxin Liu, Yang Liu

Lateral pressure provided by caving rocks plays an important role in keeping the stability of the sidewall rock mass and controlling the rock movement. Taking Xilinhot Fluorite Mine as an engineering background, we studied the control mechanism of the granular media lateral pressure on the rock movement by combining physical experiments, theoretical analysis, and field monitoring. The results indicated that with the increase of the granular media depth, the lateral pressure provided by the static granular media presented two stages of rapid growth and slow growth. The lateral pressure on the footwall was negatively correlated with the dip angle of the orebody, and the lateral pressure on the hanging wall was positively correlated with the dip angle of the orebody. Ore drawing only caused the granular media lateral pressure near the drawing point to decrease. As the granular media moved, the granular media lateral pressure outside the pressure reduction area further increased, and this part of the granular media would play a key role in limiting surface rock movement. On this basis, the improved calculation formula of GLMP was given, which could be better applied to calculate the GLMP and critical granular media column with different dip angles. The action mechanism of the GLMP in the control of the surface rock movement was clarified. The granular body in the collapse pit was mainly composed of three parts: the bottom loose granular media column, the middle compaction granular media column, and the upper critical granular media column. The critical granular media column was the most important area to control surface subsidence and rock movement. Finally, through field practice, after effective filling of the collapse pit, the surface vertical displacement of the hanging wall and footwall was decreased by 56.8% and 55.6%, respectively, and the control effect of surface rock movement was remarkable.

Sep 18, 2023

By I. Melik-Gaykazov, N. N. Melnikov, V. A. Fokin, S. P. Reshetnyak

Kola Mining Institute has been carrying out investigations of the possibility to steepen the walls of the Kovdor open pit with the design depth of 600 m. Steeping (up to 60°) wall angles is done by double height (24 and 30 m) benches with vertical slopes. One of the safety factors of mining with such walls is choosing the width of the safety berms preventing against rock falling from the slopes into the pit working area. The test on rock falling from 24 m benches has shown that vertical slopes are not more dangerous compared to the inclined(60-75°) ones.

Jan 1, 2003

By Gary Peach, Khalid Saif Al-Khayareen, Vigil Fernandez, Furqan Hameed

The Musaimeer pump station and outfall project (MPSO) is in Doha Qatar. This technical paper will discuss and explain the three major stages of geotechnical investigation employed. Stage one the tender geotechnical data and how this was used to design the TBM and identify various areas of risk. Stage two was the selection of supplementary geotechnical investigation methodologies. Stage three was the geotechnical investigation by specialist equipment installed on the TBM and providing further data on a real time basis as the TBM was advancing. Analysis of all the data will be provided along with the lessons learned.

Jun 23, 2024

By Howard W. Adam

Mill length was the primary variable investigated in an autogenous pilot mill circuit. The 5-1/2' diameter mill had both pebble ports and 1/2" wide slotted grates. The plus 1/2" mill product was crushed in a cone crusher and returned to the mill feed along with the minus 1/2" plus 4 or 6 mesh fraction. Tests were run with a short mill, inside length of 26-3/8", or diameter-to-length ratio of 2.50 to 1. The same mill was then lengthened to 48-3/8", diameter-to-length ratio of 1.36 to 1. The effect of mill length on circuit product characteristics was studied. Results show that (1) circuit throughput or grinding rate is lower per foot of mill length in the longer mill, (2) the long mill product is finer than the short mill product, and (3) KWH per ton of circuit product is slightly higher with the longer mill; however, KWH per ton of minus 200 mesh material (finer fraction) produced is essentially the same in the long mill as the short mill, It is not known whether the relationships found for the pilot mill are valid for commercial size mills.

Jan 1, 1973

By D. L. Langhans

Platinum-group metal (PGM) converter matte from the Stillwater Complex, MT, was subjected to chemical and biological leaching in an effort to upgrade the matte by decreasing the Cu and Ni content. Copper and NL extractions were optimized in a two-stage chemical leach. Atmospheric pressure sulfuric acid leaching removed over 90 pct of the Ni and Fe in the first stage, while 95 to 98 pct of the Cu was removed is the second stage using an acidified cupric chloride leach. This two-stage leach, followed by an elemental sulfur removal step, decreased the weight of the matte by 90 pct. The combined Cu and Ni content was reduced from 65 pct to less than 20 pct, while the PGM content was increased from less than 2 pct to 26 pct. Biological oxidation using Thiobacillus ferrooxidans also proved to be an effective method for removing Cu and Ni. Over 90 pct of the sulfide was oxidized and 99 pct of the Cu and Ni were solubilized, leading to a 60 pct reduction of sample mass during the 17 week bio-oxidation of the Stillwater converter matte. The final residue, after removal of jarosite that accumulated during bio-oxidation, contained less than 3 pct combined Cu and Ni and 6 pct MM.

Jan 1, 1993

By Chiranjibi Santi, Amit Kumar Gorai, VIVEK KUMAR HIMANSHU

Air overpressure (AOp) and peak particle velocity (PPV) are the most undesirable effects of blasting in mines. It is an urgent need to design a predictor model for AOp and PPV for universal applications to minimize environmental effects and damages that occur due to blasting. The present study attempts to design an artificial neural network (ANN) model for the prediction of AOp and PPV in different conditions. In this study, the blast design parameters (number of holes, depth of the blast hole, stemming length, spacing, burden, distance of vibration monitoring location from the blast site, charge weight per delay) of two active mines (coal and iron ore) are considered in four different conditions for training and testing of the model for the prediction of AOp and PPV. The model was trained and tested in four different combinations of data (trained using data of one mine and tested using data of another mine, trained and tested using data of coal mine, trained and tested using data of an iron ore mine, trained and tested using combined data of both the mines) for examining the applicability in different conditions. The results indicate that R2 values are ranged from 0.886 to 0.908 and 0.8728 to 0.8959, respectively, in the prediction of PPV and AOp. A comparative study of the performances of the developed model with the other empirical model is also demonstrated. For this, the site constants of different empirical models were estimated individually for both the mines. The study results indicated that the ANN model performs much better than all the empirical models. It can be inferred from the results that blast vibration cannot be accurately predicted only from charge per delay and distance from the blast hole. The ANN model was considered many other factors and thus can predict the vibration level more accurately.

Jul 30, 2021

By William Gleason

The mining industry is at a crossroads. Currently, there is an estimated $25 billion worth of projects around the world that have been stopped as the consequence of a dispute or disagreement with their communities, the government or some other stakeholder. Anglo American chief executive officer Mark Cutifani is one who sees the mining industry in need of change and on Dec. 12, he gave the keynote address for the launch the Kellogg Innovation Network?s Mining Company of the Future Initiative?s Development Partner Framework (DPF). The launch was held at the Ford Foundation building in New York City. The DPF seeks to inspire and support the mining industry to adopt a new way of thinking and a new approach to how it secures, nurtures and revitalizes its social license to operate. Working with a diverse group of people from faith-based organizations, nongovernmental organizations (NGO) and other stakeholders, Cutifani often had the rather uncomfortable position of representing the mining industry in a room full of people who are far from the industry?s biggest fans.

By Steven J. Schatzel, James Addis, K. Vaibhav Raj, Berk Tulu

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to enhance methane control and mine ventilation practices at coal mines, as a method to mitigate hazardous work conditions. NIOSH researchers conducted case studies to investigate the effectiveness of existing systems and improve performance to decrease the potential for unplanned or excessive methane emissions. At one mine, drainage was influenced by hydrofracking inefficiencies where two of the six wells showed good frack development. Methane content was variable, from 300 ft3/t to 600 ft3/t. This paper also summarizes overburden movement during undermining and the estimated quantities of gas transported to the mine using FLAC3D and CFD modeling. The findings from this research effort highlight considerations based on specific mine conditions that may also be applicable to most longwall mines utilizing methane control systems.

Feb 1, 2025