Search Documents

By A. A. Schweizer

Buckhorn ore is hydrous, argillized basaltic andesite, and is at least 60% clay composed of kaolinite and subordinate montmorillonite. Moisture content runs from 10% to 25%. The original crushing plant was a typical compression type, employing a jaw crusher, and two cone crushers. The system was plagued with constant plugging and unable to meet production plans. The three compression crushers were replaced with a Stamler Feeder Breaker followed by a Hazemag Impactor. Production plans are now exceeded. Agglomeration has progressed from an agglomeration drum to cascading conveyors, to introduction of the lime and cement into the primary crusher.

Jan 1, 1987

By J. Perlacia

"As the bulk handling sector continues its transformation to Industry 4.0, the mining industry, and its harsh working and environmental conditions, provides a perfect spot to study the feasibility of remote analysis and maintenance of the components used for bulk handling. The most important and expensive tools have been adapted to the digital era in recent years, from remotely controlled haul trucks to monitored conveyor belts.However, the big items of the installations rely on smaller parts that have been leftaside, mainly due to the difficultyof adapting them to the Internet ofThings (IoT).The paradigmatic example is the lack of monitored rollers, while all the other components of the conveyorbelt installations (the belt itself, motors, drums, etc.) were monitored some time ago. The main problem is that a failure of a single roller can cause the stoppage of the entire conveyor, due to possible damage to the belt. Thus, the implementation of an integral monitoring system of all the components of the conveyor is a must.The research and development department of ULMA Conveyor Components has been working since early 2012 on the development of monitored rollers, testing all the problems until their final installation in different demanding conditions, from the extreme heat in Australia to the freezing cold of Norway. All the tests have been done under actual working conditions, in real installations and have provided valuable knowledge in the identification of problems, their solutions and the final advantages of a roller monitoring system.Background and current stateThe malfunction of a single roller in certain conveyor belts can force the standstill of the entire installation until its replacement, due to the risk of greater and more expensive failures, such as a rip in the belt. In the case of a bulk handling installation, where a continuous supply of material is necessary, an unexpected stop of one hour could result in huge economic losses."

Nov 1, 2019

By L. L. Probert

A three-year project focusing on the depth profiling of respirable coal mine dust particles using scanning electron microscopy coupled with energy dispersive x-ray analysis resulted in the development of statistically classified particle-behavior models. The models depict the changing silicon fraction for 5-, 7-, 9-, and 11-keV accelerating voltages, thereby giving a clear indication of the nature of various types of particles. This paper will focus on the results for respirable quartz particles that occur in underground coal mines across the U.S. The relationship between the amount of surface-available quartz and coal seam rank is well established for Pennsylvania

Jan 1, 1994

By F. Nelson

RJB Mining is the largest coal producer in the UK. In January 1995 the Company acquired the Central North and Central South Regions of British Coal consisting of: ? 15 operating collieries -including capital equipment ? 2 care and maintenance mines ? 16 operating Opencast sites ? Interest in 26 prospective and 46 potential Opencast sites ? Approximately 417 million tonnes of proven and probable reserves and considerable mineral resource ? 9 million tonnes of coal stocks ? Long term contracts to supply approximately 90 million tonnes of coal to National Power and PowerGen to the period of 3 March 1998 ?Approximately 7,600 employees and 4,500 mining contractual labour. Up to the acquisition RJB Mining had the capacity to produce 14 million tonnes of saleable output with an approximate 1,500 strong workforce.

Jan 1, 1998

By T. Harris

Exports of crude gypsum from Mexico currently comprise about 60% of all domestic shipments, and about 25% of the imported material consumed in the U.S. wallboard industry. However, of growing importance are the domestic markets for calcined gypsum in Mexico including building plasters and wallboard, which account for 55% of the internal demand for natural mined material. This paper will examine the current trends in the production and trade of natural mined gypsum in Mexico and North America and the opportunities and threats that are facing existing and new suppliers in this changing market.

Jan 1, 1996

By G. B. Walker

The success of Heavy Media Separation, the static sink-float process, is evidenced by the operation of an estimated 300 installations treating many millions of tons per year of a wide variety of mineral products ranging in value from gravel to diamonds. The static heavy media process is usually limited to the treatment of plus 1/4 inch material. Mr. Victor Rakowsky, who was largely instrumental in the development and application of heavy media separation, recognized the need for a new apparatus and process which would extend the application of heavy media into the finer size range without placing a restrictive limit on the top size of the feed. He recognized the requirement for the application of centrifugal force to augment the force of gravity in separating fines by sink-float techniques.

Jan 1, 1966

By S. C. Torma

Sources of lead contaminated soils are numerous, i.e., the uses of leaded gasoline, lead-based paints, leaded pesticides, solders, smelting of lead concentrates, refining of lead products, automobile demolition, recycling of lead batteries, and so on. Conservative estimation by the US Environmental Protection Agency, EPA, indicated that several thousand lead contaminated sites are awaiting remediation. The current remediation technologies include immobilization, reclamation and soil washing. In this paper, the above remediation technologies will be reviewed, and where appropriate, the economics of processes discussed and future possibilities indicated.

Jan 1, 1996

Solvent extraction-electro- winning appears to be one of the most important processes for the future in the North American copper industry and for this reason both the SX and EW steps are furtive areas for development. This paper has the objective of reviewing the present state of the electrowinning technology. It discusses some recent equipment developments and concludes by discussing the direction the technology will likely go fn the next decade.

Jan 1, 1985

By K. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 meters (1MPa, tensile strength) in the rock mass, a distance that is sufficient to impact the pit-scale slope over the long term. In addition, the damage zone was calculated using the reasonable assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone ? up to 5.6 meters (30MPa, 30% of the compressive strength) ? indicates that microfracturing can occur throughout the entire rock mass in the blasting area. Finally, an economic analysis was conducted by comparing two reasonably assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond?s law after increasing the blast energy from 180kcal/t to 350kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. An optimal blast design should consider both slope stability (safety) and downstream comminution energy (production).

Feb 23, 2014

By Martin H. Stanczyk

The Organic Act of 1910 established the Bureau of Mines and gave it authority and responsibility for conducting research on separation, recovery, and recycling of waste products and scrap generated by the mineral and metals industries and the consuming public.(1)1 It was apparent to our Nation's leaders even then that mineral resources, once mined, are irreplaceable and that the development of methods for recycling the values contained in wastes would be required to solve the problem of even¬tual scarcity, Estimates of the increase in per capita consumption of mineral resources in this country indicate that the consumption of metals, minerals, and fossil fuels by 1980 will be double that consumed in 1970 (2). The United States can expect to meet its future mineral needs in three basic ways: the first is through increased production of primary raw minerals; second by increasing imports from foreign sources; and third by recycling secondary materials and metals that were formerly discarded as waste. Rather than consider these

Jan 1, 1972

By Mike Hall, Tim Kelly, Mohammad Reza Jafari, Ulf Georg Gwildis

"Qatar’s capital Doha is undergoing major infrastructure improvements including a multiphase stormwater management program. Although located in an arid climate, Doha experiences flooding during rainfall events. Dewatering operations and rising groundwater levels add to the management needs. To address those needs, construction of the Musaimeer collection tunnel along Doha’s southern rim is being followed by a marine outfall tunnel connecting a pump station to a dispersion field 10 km offshore. Qatar’s geology is characterized by sabkha deposits, a series of predominantly weak and karstic rock strata that creates challenging conditions for mechanized tunneling, as highlighted by the uncontrolled flooding of a tunnel boring machine (TBM) used on the Doha Metro tunnels. Risk associated with these challenges is magnified for the outfall tunnel by drive length, sub-sea elevation, and a single access point. This paper describes the outfall exploration strategy and design decisions made in light of experience gained during the collection tunnel construction. CONTEXT – STORMWATER MANAGEMENT PROGRAM Qatar has an arid climate with an average annual precipitation of less than 100 mm. Precipitation is mostly confined to the winter months when rare, but occasionally heavy rainfall events easily lead to flooding in Doha’s metropolitan area. Its coastal location and flat topography a few meters above the sea level mean that the depth to the groundwater table is generally shallow. The karstic aquifers in the regional dolomite and limestone series contain groundwater of high salinity, which is not suitable as a potable water source. For supplying Doha’s population of more than 900,000 (2014) with potable water, the Ras Abu Fontas seawater desalination plant is operated about 10 km south of the city. This potable water production capacity is crucial for Doha’s development and – in conjunction with overirrigation and leaking sewage tanks – is also the root cause for rising groundwater tables that have been observed over the past years."

Jan 1, 2016

By K. Avarmaa, P. Taskinen

"The solubilities of rhodium (Rh) in a molten silver alloy in doré-smelting conditions for treating copper refinery slime at temperatures of 1,000 to 1,300 °C were measured using a high-temperature equilibration-quenching technique and direct phase analysis by electron probe X-ray microanalysis. The results obtained indicate that the solubility of rhodium in molten silver is very limited: only 0.04 to 0.26 weight percent at 1,000 and 1,300 °C, respectively. The thermodynamic properties of rhodium in molten silver were estimated from the solubility data. The compositions of the solid rhodium alloys in equilibrium with molten silver-rich doré metal were also measured in this study. The excess rhodium in the doré alloy will precipitate during the refining as solid, greater than 99 weight percent Rh.IntroductionSilver refining is a core step of the processes of anode slime treatment and precious metals recovery in copper refineries (Hait, Jana and Sanyal, 2009; Ludvigsson and Larsson, 2003). It separates the oxidic materials, such as nickel oxide (NiO) and barium sulfate (BaSO4), from metallics after the de-coppering and de-selenation steps of the anode slime, and refines the silver bullion from the undesired elements present (Cooper, 1990; Hyvärinen, Lindroos and Yllö, 1989). Doré metal is a silver-rich alloy which after the smelting step will be refined electrolytically, and the remaining constituents of gold as well as the platinum group metals (PGM) will be subsequently recovered in their own processing stages.Because of low concentrations of PGMs in copper, they are typically soluble in the doré metal in anode slime treatment. This can be concluded from their binary phase diagram data with silver (Massalski et al., 2007). One exception is sometimes encountered in the anode slime smelting operations if the smelter feedstock is rich in rhodium, as may be the case if the raw materials contain secondary raw materials such as e-scrap. The solubility of rhodium in solid silver is less than 0.04 weight percent (Królas and Sternik, 1995), and its solubility in molten silver is highly uncertain. The only experimental information in the literature (Królas et al., 1993; Elliott, 1985) suggests that the silver-rhodium alloy system at 960 °C forms a eutectic, which locates less than 2 °C below the melting point of pure silver (Arblaster, 2015). Early observations (Rössler, 1900) propose that rhodium is insoluble in molten silver even if solid silver-rhodium solutions have been recently produced on a nanoscale (Kusada et al., 2010).The aim of this study is to measure experimentally the solubility of rhodium in molten silver at doré metal smelting and refining temperatures. The silver alloy used to mimic the doré alloy contained silver and about 1 weight percent of the alloying elements copper, gold, palladium, rhodium and tellurium. The experiments were carried out in metal-slag equilibria with nitrogen-oxygen mixtures as the atmosphere, employing an equilibration-quenching technique and using direct phase composition analysis by electron probe X-ray microanalysis (EPMA) (Jak, Hayes and Lee, 1995)."

Jan 1, 2017

By Thomas E. Shufflebarger

Glass is one of man's most versatile creations. ---The earliest glaze known---is about 12,000 B.C. ---The oldest pure glass is a moulded amulet of about 7,000 B.C.---. Indicative of a knowledge of properly-proportioned, quality raw-material, means were found for producing the first relatively clear, transparent glass at about the beginning of the Christian era. The fundamentals of almost all the modern, technical processes of manufacture were established during the 3rd Century. (1) Glassmaking, practiced in Colonial America, was moved toward the Ohio Valley in response to increasing demands for fuel. This move, beginning in the 1860's resulted in the use of the glass sands contained in the Oriskany (and St. Peter) sandstone. (2) Glass sand,(3) virtually pure, fine-to-medium-grained quartz sand(4) is the principal raw material used in the manufacture of glass; it constitutes proportions which range to a maximum of about 72% and seldom is glass made without it. However, acceptable glass sands are, invariably, those which most nearly fit the glass-producer's economic needs and any method used to evaluate a raw material's potential must finally prove equatable with such needs. As used in the United States, source-rocks of glass sand include sandstone, unconsolidated silica sands, quartzites and vein-quartz. Admixtures of silica sand and other (principally clay and feldspar), readily separable components have been proven viable. However, the silica sand, refined by nature to a high degree of purity, is the desirable product of exploration. If the term, standard, is justified by long-continued use, the Oriskany - and St. Peter sandstones are, together, the nonesuch of the glass sand industry they provide the principal tonnage of melting sand. According to Grimsley,(5) Ottawa, Illinois, glass-sand is considered the standard glass-sand of the West and the analyses of Berkeley Springs sand (Oriskany) compare most favorably with this sand.

Jan 1, 1974

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

By E. J. Mayhew

Bentonite and newly discovered deposits of sepiolite, saponite, and hectorite are now being processed and marketed from the Amargosa Valley of Nevada. All of these deposits are large. The bentonite has been known for decades and is the whitest known. The only other sepiolite deposit is in Spain. The only other commercial hectorite deposit is at Hector, California. No other saponite deposit is known. All the components except bentonite are hydrous magnesium silicates. The bentonite is mixed layer Na-Ca. All the materials have characteristics unique to their locale and type, such as high yield point for drilling muds and liquid suspending agents. The sepiolite has geothermal stability. Figure 1.

Jan 1, 1979

By John F. Oyler

The performance of high alumina refractory subjected to high compressive loads and high temperatures is an area in which operating experience is quite limited. This paper documents the results of five months of operation of a combustion chamber lined with 83 pct alumina brick subjected to compressive stresses as high as 45psi and hot face temperatures of about 2750°F. It also describes a method for predicting long term subsidence results based on the limited information available in standard hot load limit tests. Descriptions of the chamber itself and the pilot plant upon which its design was based are included.

Jan 1, 1978

The need for an integrated approach to optimization of unit operations in both the pit and the mill has long been recognized, but the complexity and nature of the overall problem has up to now resisted solution. This paper reports on a modeling methodology which couples symbolic and numeric computing to unify operations in both the pit and mill. The ultimate goal of this work is to optimize all operations that are influenced by blasting. Blasting plays a key role in all facets of operations. Obviously, drilling and blasting costs are determined by blast design, but the down-stream costs that are closely related to blasting results are often treated as separate functions: loading, hauling, cleanup, and crushing and grinding are all heavily influenced. Diggablilty and bucket fill factor are a function of fragmentation, the condition of the floor and uniformity in the shape of the muck pile. Likewise, cycle times and loading delays partially determine haul cycles, while fragmentation distribution and size determines the efficiency of truck loading. Removal and breakage of oversize causes loading delays and increases cleanup costs. The influence of blasting doesn't stop at the crusher. Mill productivity, power consumption, and maintenance are a function of the feed. Even at the SAG mill a reduction of a critical particle size during blasting can increase throughput. Thus, a bottle-neck for production far removed from unit operations in the pit can be alleviated by a modification in blast design. The question is: how do we optimize blasting with respect not only to itself but to al\ related mining and milling operations? For that matter, how do we even model blasting so that we can control the results of a blast?

Jan 1, 1991

By M. Beale

Fuzzy logic and neural networks are new technologies being applied in many areas of engineering and business. While it is not always clear which kinds of problems are best suited to these technologies, and which problems are best approached with more standard methodologies, both fuzzy logic and neural networks appear to show great promise in the field of control systems. This paper demonstrates two advantages that these technologies offer: Easy controller design in the absence of a mathematical model of the plant to be controlled, and adaptive control capable of quickly responding to changes in the plant.

Jan 1, 1994

By K. V. Raj, T. Bhowmick

"Computational fluid dynamics (CFD) modeling of an open-pit mine has several challenges. A good quality mesh of the model domain is a pre-requisite for convergence in solution. Good quality tetrahedral meshing and insertion of prism layers in faceted open-pit mine geometry is complicated due to presence of numerous vertices and ridges. Presence of vertices and ridges result in poor quality tetra elements and holes in prism layers, which cause instability in the model. Good quality pit bottom prism mesh elements significantly improve the formation of velocity boundary layer and thermal boundary layer at the pit bottom. This results in an expected temperature dependent micrometeorological buoyancy flow in the pit. Whereas, model geometry without a prism layer, results in abrupt temperature gradient near pit bottom. Buoyancy flow and recirculation have significant effect in lifting mechanism of fugitive dust particles generated near pit bottom. Representative initial and boundary conditions and selection of appropriate turbulence model have significant influences on the simulation results. In this paper, three-dimensional models of open-pit mines are developed using commercial CFD software (CRADLE-CFD). Important constraints and various consequences in modeling complex open-pit geometries are presented. INTRODUCTION Application of Computational fluid dynamics (CFD) to model an open-pit mine to predict fugitive dust and pollutant concentrations in and around a mine is relatively new. In former Soviet republic (USSR), Baklanov [1] and Belousov [2, 3] presented numerical models of pollutant transport in open-pit mines in Arctic regions. In recent years, advances in mathematical and computational fields have enabled better modeling of pollutant dispersion phenomenon around mines using computational fluid dynamics (CFD). Several CFD software packages have been used by various researchers to model the pollutant transport in open-pit mines. Works by Alvarez et al. [4]; Lowndes et al. [5]; Silvester et al. [6]; Torno et al. [7]; Choudhury and Bandopadhyay [8]; Collingwood et al. [9]; Raj et al. [10] and Flores et al. [11]; are examples of application of various commercial and open source CFD packages (COMSOL, ANSYS, OpenFOAM) to model pollutant transport in open-pit mines. These researches provided a strong background for additional research involving CFD modeling of open-pit mines. Due to the limitations of computational times and capacity, 3D modeling and various aspects of fugitive dust dispersion in open-pit mines remained unexplored."

Jan 1, 2015

By Mahmoud Sepehrmanesh, Verya Nasri, Maziar Partovi

"This paper presents an assessment of the impact of tunneling and its associated risks on pile foundations located in the influence zone of tunneling operation. Tunneling in proximity of pile foundations introduces deformations in piles and in turn induces additional axial and bending forces. In modern mechanized tunneling, ground convergence is controlled through balancing the earth pressure at the tunnel face as well as applying pressurized bentonite through the shield. Reducing ground deformation can consequently lower the additional deformations and forces developed in the pile foundation and lessen the associated construction risk. In this paper, comprehensive detailed finite element modeling was performed to quantify the effect of the different parameters on induced forces in piles. Finite element models took into account the nonlinear behavior of soil and pile-soil interface. The modeling results are of practical importance in risk evaluation of tunneling in vicinity of pile foundations. INTRODUCTION Tunneling operation in congested urban areas becomes more frequent as demand for further utilizing underground spaces grows. In urban settings, it is not uncommon for tunnel designers to plan a tunnel route in close proximity to other structures to satisfy other competing objectives like raising the alignment to reduce excavation volume. Setting the alignment close to existing structures increases the risk involved in the project. It is the responsibility of the designer to thoroughly identify, assess, and mitigate all design risks involved. In this paper, we focus on the aspects involved in tunnel construction in proximity to existing pile foundations. Tunnel operations introduce deformation in the soil mass. Consequently, a pile located within deformation zone experiences extra forces as a result of the imposed deformation. The developed forces and bending moments can be in orders comparable with the pile capacity depending on the relative horizontal proximity of the tunnel and the relative depth of tunnel with respect to the pile length."

Jan 1, 2016