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By Jurgens PE Hamman, Faisal Putra, Hadnaltias Alpeki, Willem de Beer

The Deep Ore Zone mine is the third lift of caving at PT Freeport Indonesia’s East Ertsberg Skarn System. An increasing trend in seismicity along the northern boundary of the DOZ cave, as well as the northern fringes of the DOZ production and infrastructure levels, was taken as indicative of an interaction between the approaching DMLZ cave and the DOZ subsidence zone. Seismicity trends and locations indicated a reducing crown pillar and an associated stress increase along these DOZ excavations, as well as the regional area along the DOZ cave boundaries. Although rockbursts were not identified as an immediate hazard, seismic shakedown was a highly probable hazard in the case of remote large (≥3.0) seismic events. An evaluation process, as described in the Canadian Rockburst Support Handbook (1996), was followed to identify and quantify the various parameters that could contribute to a shakedown evaluation. A shakedown assessment, based on the Peak Particle Velocities scaling relation, was conducted to assess the current installed ground support systems along the northern fringes and the fixed facilities of the DOZ mine. The range in ground support systems were mostly due to different geotechnical environments. The load–deformation characteristics of these support systems were evaluated to determine the support capacity and compared to the potential support demand under varying shakedown conditions. Shakedown hazard maps were compiled to indicate the installed ground support system’s vulnerability to seismic shaking. Based on this information, areas were divided into zones indicating whether they were sufficiently supported, additional support was required, access was to be restricted, and / or they were to be abandoned. Mine management utilised these hazard maps to strategize actions for the various operational zones within the DOZ, including the fixed facilities. This paper briefly describes the derivation of the PPV scaling relationship. Seismic and geological data for the DMLZ – DOZ interaction areas were evaluated to determine the likely source of large events. Subsequent larger events and their effects are shown to assess the veracity of the magnitude and PPV estimates, as well as the effectiveness and appropriateness of the ground support systems.

Apr 26, 2022

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil. One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester. Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e .? in flash combustion mode. The velocity. temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data. this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By Xia Lou, Hossein Dashti

Gas hydrates technology has been considered as an alternative method for carbon dioxide (CO2) separation. A wide range of studies have been reported in the past decade on the improvement of the separation efficiency by using chemical additives. While most of these studies have shown improved kinetics, thermodynamics and/or separation efficiency at the laboratory scale, there has been no quantitative analysis of the energy consumption for viable industrial applications. Comparison of the effectiveness of the chemical additives from separate studies or groups also is impossible. The present work is focused on the modelling of the hydrate-based CO2 separation process and provides a quantitative approach that is new in its analysis of the effectiveness of chemical additives in relation to the energy required and the kinetic parameters involved in the process.

Mar 1, 2018

By J. Gonzales

For this paper, blending is conceived as a linear process that takes a proportion from one stockpile or location and mixes it with another proportion from another stockpile or location, with the aim of obtaining a set of attributes in the final combination that satisfies a given quality standard. A blending class is the combination of ore attributes and grade limits that should be stockpiled in order to achieve the target quality for the process Plant. Current literature considers the number of blending classes in the Open Pit Scheduling Problem as fixed; however, this paper shows how to define specific blending classes for a given deposit so that the schedule can be solved with Sequential Linear Programming. Finally, a practical application in a Peruvian copper mine is shown, involving four ore attributes: alteration code, arsenic, oxide content and copper grade. INTRODUCTION In copper ore deposits, blending for quality has not been a typical issue as it was for coal and iron ore; however, current copper deposits in the world are becoming geologically and chemically more complex than in the past and is not uncommon to have quality standards involving up to four attributes, introducing an additional complexity to the mine scheduling process [1]. In order to solve the Open Pit Scheduling Problem with multiple ore quality constraints, two assumptions are necessary [2]: - Grade constraints are defined only by specifying an upper and lower limit; - Ore attributes in stockpiles are pre-determined, i.e., the upper and/or lower grade limits defining each stockpile are already known at the time of setting the schedule. Assuming each ore attribute is classified as high, medium or low, and there are four attributes to be controlled in the target ore quality, the number of possible blending classes would be 3^4 = 81. This number is impractical to manage in Operations, and increases the complexity at the time of running the schedule; therefore, a more efficient way of classifying ore is required. Note that in practice, one blending class can be split into more than one stockpile location due to physical capacity constraints. Therefore, the number of stockpiles could even be more than 81. BLENDING CLASSES DETERMINATION For a given set of ore grades with lower and upper limits to be achieved, one has to find all feasible ore classes such that when blended, their grades will lie within those limits.

Jan 1, 2019

By Robert Stefanko

The widespread and increasing use of electrical power for mechanized power has made a tremendous impact on the coal mining industry. It is probably the single most important factor influencing the productivity of a coal mine. In fact, as a part of a study of 62 coal mines in Pennsylvania and northern West Virginia, plus information that was obtained from other sources, it was possible to show a direct correlation between the rise in the use of electrical power and mine productivity, Figure 1. This increased power demand has not always been achieved through proper planning and a careful evaluation of all design parameters, many of which are not even recognized. The result has been increasing problems in power distribution and utilization establishing the need for scientific studies including considerable underground measurements. Because the cost of power for ton of coal produced is generally a relatively low value, inadequate attention is paid its distribution and utilization. Furthermore, a poor system of records and a lack of adequate measurements add further to a paucity of statistical evidence that would permit a rational analysis of overall power costs. However, the direct cost figure alone is highly deceptive; of much greater value is the indirect costs associated with the use (or misuse) of electrical power underground. Success in highly mechanized mining correlates directly with equipment utilization. Today's machines have tremendous potential capacities but profits are measured in terms of performance and not potential. Thus the reliability of electric motors is an extremely important factor for consideration and the effects of all parameters should be carefully evaluated. Thus while studies are continuing on the evaluation of primary and secondary mine electrical systems with interesting results, this paper will be limited to reporting on the results of a study of a specific motor application.

Jan 1, 1972

By M Korte, J McMaster, C Brent

The Barrick Osborne concentrator has gone through a number of upgrades since commissioning and has increased production from the original 119 t/h design capacity to a milling throughput of 265 t/h in 2008. This was achieved incrementally over several years, by maximising operating efficiencies, in order to minimise capital expenditure, and take advantages of economies of scale; but more importantly it was reached with no measurable loss of recovery. Osborne currently processes a blend of underground and open pit material from the nearby Trekelano deposit. Following primary/secondary crushing, the material is processed through a rod/ball mill grinding circuit ahead of rougher/scavenger flotation that produces a copper concentrate. Osborne was seeking a further increase in plant throughput of the order of 15 per cent, but at more sustainable levels of secondary crusher plant utilisation. In early 2008, Osborne contracted Metso Process Technology and Innovation (PTI) to review the entire process from run-of-mine feed to final copper concentrate. This review would be done concurrently with surveys of both the crushing/grinding and flotation circuits being performed at the same time. The outcome would be a steady-state model of the complete flow sheet allowing the crushing/grinding model to interact with the flotation circuit model, such that overall process optimisation was possible. This was to apply both by exploring the operating limits of the currently installed plant, as well as looking at the logical next stage of capital plant expansions. Surveys of the crushing and grinding circuits were conducted at the Osborne concentrator in May 2008. The main objective of the surveys was to review the potential of increasing grinding throughput whilst maintaining the flotation feed 80 per cent passing size. This would also require improving the efficiency of the crushing circuit which was already operating in excess of 80 per cent of the time. Steady-state simulations were performed using the developed circuit models to identify opportunities to increase throughput and alleviate high circulating loads in both the secondary crushing and grinding circuits. Due to operational changes, the recommendations resulting from this project were considered by Osborne but have as yet only been partially implemented.  This paper covers part A or the crushing and grinding component of the project. A separate paper discussing part B or flotation is also being presented at this conference. The results of interactive simulations between the flotation and grinding circuit models are included in part B of this paper.

Jan 1, 2009

Numerical simulation of the fluid flow and heat transfer has been carried out for a waste-heat boiler in an Outokumpu type copper flash smelter. In this boiler, SO2-containing off-gas flows into the waste-heat boiler radiation section at about 1350°C. A fraction of cooler off-gas from the electrostatic precipitator at about 200°C was recirculated into the radiation section, and a small amount of ambient air was leaked into the boiler from the bottom. The computational results show that the flow is strongly recirculating and distinctly three dimensional in most of the boiler, particularly in the radiation section. The hot off-gas cooled down rapidly after entering the radiation section due to radiation. The predicted flow pattern and temperature distribution were in a good agreement with laboratory models and industrial measurements.

Jan 1, 1995

By Georg Petersen

El Perú es un país rico en diversidad de metales empleados en los campos de la minería, metalurgia, orfebrería y artesanía durante los tiempos pre-históricos. Dichos metales son: oro (objetos laminados por martilleo, repujados, pulidos, vaciados, soldados y dorados), plata (objetos trabajados de la misma manera que los de oro), cobre (objetos en diversas formas, como son discos, recipientes, herramientas y armas, en muchos casos dorados y/o plateados) y el azogue (cinabrio usado preferentemente para pintar las caras de los guerreros, las máscaras de los fardos funerarios y las caras de las mujeres nobles, costumbre que se generalizó a principios de la época colonial). De otro lado, existen otros cuatro metales que se emplearon en cantidades pequeñas como: fierro, platino, plomo, estaño.

Nov 1, 1970

By Marino Carrión P

Ante la crisis ecónomica que afecta al sector minero, este ha previsto expandir su producción y reducir los costos operativos que le competen. En esta perspectiva, la Compañía minera Atacocha busca ampliar su rango de producción a partir de la elaboración de un proyecto racional del ore-body Santa Bárbara. El proyecto consiste en explotar el cuerpo mineralizado por encima del nivel 400. Sin embargo, las condiciones para la mineralización son insuficientes. En este sentido, el presente texto presenta una alternativa de explotación mecanizada donde el cuerpo mineralizado tolere los niveles altos de temperatura a través de un nuevo block que se aplique en la profundización del ore-body y puede minimizar los costos operativos que esto conlleva.

Apr 1, 1991

By Xu Wang, Bang Chen, Xiujian Luo, Wei Tang, Xiao’ou Xia, Fangming Liu

"The inertia cone crusher has lots of advantages, such as big crushing ratio, fine particle size, material layer crushing, good passing tramp iron performance and stable technical index, realized open crushing circuit and simplified crushing flowsheet. The crusher was input to China’s Beijing General Research Institute of Mining and Metallurgy (BGRIMM) from Russia’s Mekhanobr-Tekhnika Research & Engineering Corporation at the beginning of the 1990s. This paper introduces that after years of absorption and innovation how Chinese researchers optimized and creatively designed about transmission mechanism, bracing structure, kinetic parameters, lubrication system, dust sealing system, damping system and hydraulic control system etc on the basis of keeping its advanced theory and unique structure, therefore the crusher’s stability was raised and the usage cost was reduced greatly. Accordingly the inertia cone crusher in China has been widely used in many fields, such as mineral resources and the recycling of metallurgical slag. The achievement in cooperation was fully affirmed by governments of Russia and China, and cooperation of science and technology in the mining and metallurgy industry between Russia and China is promoted greatly. INTRODUCTION From the early 1950s, the former Mekhanobr Institite(now Mechanobr-Tekhnika Research & Engineering Corporation) devoted itself to the research of inertial cone crusher and put it into industrial application in the late 1980s. Inertial cone crusher is like a maverick flower in the field of crusher. With its excellent performance and excellent application effect, it shocks the world and is destined to shine with a bright future. In the early 1990s, the chief leaders of the Beijing General Research Institute of Mining and Metallurgy (BGRIMM), Academician Sun Chuan-yao and Professor Zheng Baochen, captured the extraordinary performance and strong vitality of inertial cone crusher with keen eyes. So the two big institutes started the cooperation to introduce inertial cone crusher to China. Since then, Inertia cone crusher has been able to flourish in China and have achieved impressive results with two institutes’ continuous effort."

Jan 1, 2018

By J. A. Jirestig

Laboratory investigations on the possibility for magnetic separation of sulphide minerals are reported. A survey of several sulphide ores and flotation concentrates shows that magnetic separation in most cases is not a suitable primary method of beneficiation. However encouraging results have been obtained in concentrate purification. At the Boliden complex sulphide ore concentrator in Garpenberg a Allis-SALA MK III carousel High Gradient Magnetic Separator (HGMS) is used together with a small flotation circuit to recover sphalerite lost to the galena concentrate in lead flotation. The result after four years of refining the HGMS process, show increasing zinc recovery and enhanced quality of the lead concentrate.

Jan 1, 1993

China's coal energy development, characteristics and relationships with atmospheric pollution are reported. Atmospheric pollution sources from coal combustion are analyzed. Some of the projects for clean coal combustion in the Shanghai area include use of industrial briquettes, investigation of coal combustion additives, and blending combustion of coal with industrial wastes. Coal is China's main energy source, and 80 percent of China's annual coal production is used in combustion devices. Coal-flue gases from the domestic stoves and industrial furnaces are the main atmospheric pollution source. China's atmospheric pollution is, in fact, the pollution of coal-flue gases. To 2000, in view of China's energy needs as a developing nation, the atmospheric pollution from coal combustion must receive our utmost attention.

Jan 1, 1994

By J. L. Francke

This paper describes the practices and methods used in a study of Time Domain Reflectometry (TDR) as an inexpensive deformation monitoring tool in underground excavations at the Waste Isolation Pilot Plant (WIPP). The WIPP is being developed near Carlsbad, New Mexico, for the disposal of transuranic nuclear wastes in bedded salt 655 m (2 150 ft) below the surface. Data collected from WIPP geomechanical monitoring are used to characterize conditions, confirm design assumptions, and understand and predict the performance of the deep salt excavation. The geomechanical monitoring program encompasses numerous geomechanical monitoring techniques ranging from inspection of observation boreholes to advanced radar surveys. In 1989 TDR was introduced as a monitoring tool with the installation of 12.7 mm (0.5 in) diameter TDR cables in the underground excavations. In 1993, a new TDR system was installed in a separate location. Based on experience with the previous installation, enhancements were implemented into the new TDR system that: 1.) extended the period of performance by increasing cable diameter to 22.2 mm (0.875 in), 2.) increased accuracy in locating areas of deformation by aligning cables with nearby observation boreholes, and 3.) improved data acquisition and analyses using a standard laptop computer, eliminating the chart recorder previously used. In summary, the results of a correlation between the TDR signatures to nearby observation boreholes and geomechanical instrumentation will be presented.

Jan 1, 1996

By A. Shakoor, T. P. Gautam

The long-term slaking behavior of clay-bearing rocks in the field can be quite different than the short-term slaking behavior in the laboratory. To assess this difference, 12 replicate samples of each of 20 clay-bearing rocks, including 5 claystones, 5 mudstones, 5 siltstones, and 5 shales, were exposed to natural climatic conditions for 12 months. After each month of exposure, one replicate sample of each rock was removed from natural exposure and its grain size distribution was determined. Disintegration ratio (DR), defined as the ratio of the area under the grain size distribution curve of the slaked material for a given rock to the total area encompassing all grain size distribution curves of the tested samples, was used to quantify the amount of disintegration under natural climatic conditions. DR values of naturally exposed samples were then compared with the corresponding values of second-cycle slake durability index (Id2) determined in the laboratory. The relationship between Id2 and DR after, 1 month of exposure, exhibits an R2 value of 0.65 but the relationship deteriorates when DR values for 6 and 12 months of exposure are used, with R2 values of 0.63 and 0.25, respectively. However, when DR values for laboratory samples, computed from grain size distributions of slaked material after second cycle, are compared with DR values of naturally exposed samples for the three periods of exposure, the relationship improves with the corresponding R2 values being 0.61, 0.71, and 0.41. These results suggest that DR may be a better parameter for assessing the long-term disintegration behavior of clay-bearing rocks than Id2.

Jan 1, 2015

By Laís Ávila de Oliveira Silva

A aplicação de ligas de NiTi como biomateriais exige que sua superfície tenha um excelente acabamento final, para garantir a alta resistência à corrosão e a biocompatibilidade. O polimento eletrolítico é um processo capaz de diminuir as imperfeições da superfície, sem alterar as propriedades do material, e de formar uma fina camada protetora de TiO2. Nesse estudo, foram realizados eletropolimentos em fios superelásticos e com memória de forma, usando dois eletrólitos ácidos distintos. A partir dos resultados obtidos, foi possível concluir que a solução de ácido sulfúrico produz superfícies mais homogêneas do que o de ácido perclórico, para os mesmos tempos de polimento, e se apresenta como uma boa alternativa para o tratamento superficial de ligas superelásticas e martensíticas de para sua aplicação como biomateriais.

Aug 17, 2017

By Nikzad Oraee, Parham Khajehpour, Kazam Oraee, Arash Goodarzi

"Rock fall related accidents continue to occur in coal mines, although artificial support mechanisms have been used extensively [1]. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata, as a key factor in coal mines, must be determined by a survey which proactively investigates fundamental aspects.Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or slide out of the walls [2]. A practical rule based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard, an accident causing a huge collapse in a coal mine leading to four fatalities is illustrated by way of a case study. A comprehensive investigation of the hanging wall has been gathered through a systematic collection of evidence. The investigation results are then analyzed, and an interpretation of the evidence gathered is provided.For this purpose, horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident and hence recommend corrective actions to prevent or minimize reoccurrence probability of similar accidents. The corrective measures are placed into a rule-based framework for the benefit of the mine operators.INTRODUCTIONRoof rock failure has generally been the most dangerous hazard for underground coal mining in the world. Failure of rock around shallow coal mine openings often results from loosening of blocks of rock on the weakened planes under the influence of gravity. This condition is not typically seen in large deep coal mines. There are a number of differences between large mechanized mines and small mines related to ground control [3]."

Jan 1, 2015

By F. Habashi

Magnesium is the eighth most abundant element in the earth's crust, It occurs in nature in sea water, brines, and a number of minerals, Metallic magnesium was first isolated by Humphry Davy (1778-1829) in England in 1808 via electrolysis of anhydrous magnesium chloride with a mercury cathode, Antoine Bussy (1794-1882) in France extracted the metal in 1828 by reducing fused magnesium chloride with metallic po¬tassium vapour, The first industrial production of magnesium by electrolysis of molten carnallite began in 1886 in Hemelingen in Germany, In 1940 Lloyd M, Pidgeon (1903¬1999) in Canada pioneered the first industrial metallothermic magnesium extraction plant based on the reduction of dolomite with ferrosilicon under vacuum, Since then the magnesium industry developed further and a variety of processes are presently used.

Jan 1, 2006

By Tingting Li, Guodong Li, Dezhou Wei, Cong Han, Shuling Gao, Yanbai Shen

"The aim of this study is to solve the problem of tungsten leaching from scheelite concentrate using sodium hydroxide in the presence of phosphate by an autoclaving process, which is one of main development techniques for tungsten recovery. To understand the applicability and leaching performance of tungsten leaching from scheelite concentrate, the main work is to investigate the effects of leaching parameters such as initial concentrations of NaOH and Na3PO4, reaction temperature, stirring speed, liquid-to-solid ratio and reaction time on WO3 dissolution rate to obtain the optimal leaching conditions. The chemical composition and phase composition of the samples were evaluated by means of XRF and XRD. The content of WO3 in the leaching residue obtained via washing, filtering and drying was analyzed by thiocyanate spectrometric method. The optimal leaching conditions were found to be NaOH concentration of 6.76 mol·L-1, Na3PO4 concentration of 1.35 mol·L-1, reaction temperature of 180°C, stirring speed of 400 rpm, liquid-to-solid ratio of 2.0 and reaction time of 90 min. The results showed that tungsten leaching rate of 99.20% was reached under the optimal conditions. The technology exhibited superior leaching performance, which not only reduced the consumption of sodium hydroxide but also greatly decreased reaction time in comparison to a conventional autoclaving process. INTRODUCTION Tungsten is an important strategic metal, which is widely utilized in a variety of industries due to its high melting point, superior mechanical properties and heat-resistant performance [1-3]. The chief raw materials for the production of tungsten in nature are wolframite and scheelite [4, 5]. Among them, approximately two-thirds of the tungsten reserves contain scheelite deposits in the world [6, 7]. With the progressive exhaustion of high-quality wolframite resources, scheelite has become a predominant primary resource for the production of tungsten [8, 9]."

Jan 1, 2018

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By J. A. Finch

The metallurgical performance of a flotation cell is strongly influenced by the features of the bubble population, characterized by the gas dispersion properties, a collective term including bubble size, superficial gas velocity and gas holdup. It is required that gas be well distributed throughout the cell. Gas distribution is estimated here by simultaneous measurement of gas velocity (Jg) at different distances from the center (radial Jg mapping). This communication describes a technique to perform radial Jg mapping together with fundamentals for the interpretation of the data.

Jan 1, 2009