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By S. M. C. Santos

Preliminary bench-scale studies were carried out on the leaching of a zinc sulphide concentrate from Somincor, Portugal, and the purification of the resulting pregnant solution using solvent extraction techniques. The sulphide concentrate contained 36% Zn, 36% S, 2% Fe and 4% Cu. The leaching was carried out with sulphuric acid in the presence of ferric sulphate as the oxidant. Important leaching parameters, such as the effect of reaction time, the solid-liquid ratio, temperature and concentrations of acid and oxidant, were investigated. After leaching, the recovered solution was contacted with an organic phase containing Acorga 5640 to remove the copper. Subsequently, the removal of iron from the leaching solution was achieved with a mixture of Cyanex 272 and TBP. This solvent mixture was relatively selective for iron over zinc. The stripping of the loaded solvent was performed with 200 g/L H2SO4. Six countercurrent extraction stages achieved a separation of about 99% of the iron from the leaching solution. The iron-free leachate can be further treated to recover minor metals by cementation, and finally, zinc by liquid-liquid extraction. The advantages of the suggested process relative to the traditional jarosite process are discussed.

Jan 1, 2006

By S. Komar Kawatra, J. J. Carlson

"It is widely known that steel made from iron ore pellets high in phosphorus is brittle. Removal of phosphorus from iron ores such as hematite has proven to be difficult. The majority of research on phosphorus removal from hematite ores has been focused on flotation. The purpose of this study was to assess phosphorus distribution under current operations at an existing hematite concentrator and determine how efficient the plant is at removing phosphorus. Objectives included: (1) Perform a phosphorus balance at an operating plant to assess phosphorus distribution under current operations; (2) Determine phosphorus removal efficiency of each separating unit and (3) Perform a quantitative liberation analysis to determine max phosphorus removal by physical means. Liberation was quantitatively determined using wet high intensity magnetic separation (WHIMS) to separate iron ore from liberated apatite (and other nonmagnetic compounds).It was observed that 61.2% of the total phosphorus entering Plant F was rejected during current operations. The desliming process was the most efficient step at removing phosphorus (45.1% P removed), whereas the flotation step was much less effective (16.1% P removed). Liberation analyses indicated that the deslime thickener may have been more efficient at removing phosphorus than the flotation circuit due to the greater abundance of liberated phosphorus in the deslime thickener feed. The scavenger returns stream was identified as having a high concentration of phosphorus and a possible point of phosphorus removal. However, liberation analyses indicated that only 32.4% of the total phosphorus in the stream was liberated. Grinding the scavenger returns to 80% passing 5.2 µm increased the amount of liberated phosphorus in the stream to 70.4%."

Jan 1, 2014

By K. Scholey, S. Marcuson

As high grade nickel sulphide ores are being depleted and with the continuing challenges experienced in economically processing nickel laterite ores, it is important to investigate technologies that can extract nickel from low grade ultramafic ores which are present in large quantities worldwide. In the Thompson Nickel Belt, there are some hundred million tonnes of mineralization that are potentially amenable to surface mining. Since the original discovery of the Thompson orebody, recovery of nickel from these ultramafic deposits has been an elusive goal. Research and development projects as well as commercial processing have been attempted. In the 2000's as other resources became scarcer, a major drilling, mine evaluation and research project was initiated at Vale. In 2007, Vale Base Metals Technology Development invited Cytec and potential academic partners to participate in an industry-university research consortium with the goal of developing new technologies and methods of processing the ultramafic deposits. Three university professors, J. Finch of McGill, P. Somasundaran of Columbia and R. Pelton of McMaster accepted, each group attacking the problem with a different approach. This paper describes the management of the research consortium and the significance of the results from Vale's perspective. The next four papers in this session will summarize the project and results from the partners' point of view. Vale is pleased to share the experience of the collaborative research and development with the mining industry.

Jan 1, 2011

By Gihan E. Abdelraham, Youssef G. Youssef, Mohamed M. Kamel

"Previous studies defined Narrow Mechanically Stabilized Earth, NMSE, walls as a retaining wall with aspect ratio (wall width to its height, L/H) less than 0.70 as in traditional walls. Some studies investigated its behavior and its failure planes compared to those of traditional walls. In this paper, parametric study using finite element analysis PLAXIS, 8.2 has been introduced to discuss global factor of safety, FS, maximum horizontal displacement, Ds, maximum tension force of reinforcement element, Tmax, and active earth pressure coefficient, ka, as a function of different aspect ratio of NMSE wall, L/H, reinforcing elements spacing, S, elastic axial stiffness of reinforcement element, EA, wall batter, 1/m, soil friction angle, f, and wall height, H. The results indicated that increasing aspect ratio increases the factor of safety, maximum horizontal displacement, maximum tensile force and active earth pressure. Increasing elastic axial stiffness increases factor of safety, maximum tension force of reinforcement element while decreasing the maximum horizontal displacement.IntroductionReinforced earth is a composite geoconstruction material, which embodies two basic components; namely engineering fill and reinforcing elements. The latter one is responsible for improving the tensile and shear resistance of the soil. The soil-reinforcement technique has been in use for many geotechnical applications especially MSE walls.A narrow wall system is referred to as a MSE wall with an aspect ratio, L/H, below 0.70 that is placed in front of a stabilized wall. An example of a narrow wall system with its dimensions is illustrated in Fig. 1."

Jan 1, 2017

By Arthur W. Ruff

The iron-ore beneficiation and shiploading facilities of the Marcona Mining Company are at San Nicolas Bay which is on the Peruvian coastal desert about two hundred and seventy miles south of Lima. The mines are at elevation of 2,500 ft. Crude ore is transported from the Mine primary crushers to the beneficiation plants by ten miles of overland belt conveyors. After the predominantly magnetic ore is reduced to minus 3/4 in. in the secondary crushing plant, the ore is ground by rod and ball mills and concentrated with magnetic separators. The concentrate slurry is pumped to a thickening and filtering installation for desliming and dewatering. Pelletizing is accomplished with a Lurgi and also a Dravo-Lurgi machine. Deep-water shiploading facilities are available close to the beneficiation plants. Figure 1 shows a flowsheet of the general operation. Pelletizing operations are scheduled 24 hours a day and 365 days per year. A maximum tonnage rate with a high percentage of operating time is necessary to produce the three and one half million tons per year required from the two pellet lines. Process control is a major responsibility and of primary concern to all Operating personnel. The particle size, moisture, and chemical composition of the filter cake must be closely controlled to get uniform high-grade pellets. Key points are sampled routinely and analyzed on a two-hour basis to provide the necessary structure and chemical data to maintain a superior final product. The iron content of the pellets is held between 65.3 and 65.8 percent with 4.0 percent Si02. Sulfur is below 0.04 percent and copper is below 0.02 percent in the finished pellet.

Jan 1, 1968

Although the technology involved in removing material from below the earth's surface has a long history, communication systems in underground workings are relatively new to the industry. Communication equipment did not begin appearing in underground mines until the early 1900's. Figure 1-1 shows a miner using a Western Electric standard telephone set for underground mines in 1913. These early phones were essentially the same as those used aboveground, except that they were enclosed in cast-iron boxes as protection against moisture, acid fumes, and gases.

Jan 1, 1984

By S. K. Kawatra, J. E. D. McDonald, S. C. Roache

"The formation of geopolymers from mine tailings using cold-bonding processes is known to be possible. Numerous cold-bonding methods exist, but the hydrothermal processes involving high temperatures and pressures in the presence of steam have been found to be the most ideal. This paper presents the results of successful preliminary studies to apply hydrothermal bonding processes to mine tailings agglomerates. Particle-size analysis revealed the particle size of the tailings waste to be 80 percent passing at 35 µm. The compressive strengths of the tailings pellets were shown to increase with time in the curing vessel, closely approaching the 400 lbf of standard iron ore concentrate pellets. These strengths are sufficient to allow use of the tailings pellets as aggregate materials for asphalt and cement. Additional applications may be possible, including reprocessing to extract more valuable materials and usage as agglomerated road-bed materials, backfills for building foundations, and replacements for sand and lime in cement.IntroductionMine tailings are a waste byproduct of ore concentration and are available in large quantities across the world. Despite their abundance, they have received little attention or consideration for beneficial use. One reason is that the chemical nature of the material is not well known. Another factor that has hindered direct usage is the fine particle size. This raises the questions: what is the composition of the tailings, and how can such fine solids be beneficially used? Because the mining industry produces concentrates, the tailings may be treated as concentrates and processed in the same fashion, but it would be inefficient to consider full sintering or induration conditions for materials that have little ore content. To achieve sustainable operation, the development of technologies to use these tailings is necessary. Mine tailings should not be considered waste, and an “out of sight, out of mind” mentality does not represent a sustainable solution for the future.One iron ore mine in Michigan is estimated to have accumulated more than 400 million metric tons of tailings during its last 30 years of operation, with an additional 180 million metric tons accumulated before the ore body is depleted. These mine tailings currently have no practical use, largely due to a scarcity of knowledge of their true physiochemical nature. It is thought that lack of quality control of the waste material prevents its use, but variability in the unprocessed ore prevents a consistent waste stream composition. The fact that the tailings are available in such great quantities makes them an extremely attractive resource. However, developing a sustainable, low-cost means of repurposing the mine tailings waste as a construction material may only be completed once the tailings are physically and chemically understood. Due to the high silica content of the material studied, cold bonding was determined to be the most viable method for processing the tailings into a usable product."

Jan 1, 2016

Underground testing was carried out by Ingersoll-Rand, Inc., under contract to the Bureau of Mines to determine the effectiveness of a machine-mounted scrubber system for ventilating the face during an extended advance. A continuous miner equipped with an integral flooded-bed dust scrubber system was instrumented with methanometers and Real-time Aerosol Monitor (RAM) dust monitors. Methane and respirable dust data were collected at brattice setbacks of 7.5 m (current operating distance), 10.5 m, and 15 m (blowing ventilation) during production shifts. Results showed that a suitable machine-mounted scrubber system can adequately ventilate the face at brattice setbacks up to 15 m. No deterioration in ventilation performance was observed as brattice setbacks were increased from 7.5 m to 15 m. The scrubber system effectively controlled face methane levels at large setbacks, though respirable dust levels increased as much as 33 pct at the operator's cab at setbacks greater than 7.5 m.

Jan 1, 1986

"Mining of ore bodies that are located at great depths enforces long distances to move the excavated rock masses to the surface. The excavated rock mass contains not only ore that can be economically extracted from the face but also waste, which is usually discarded several steps further downstream in the process. As a result, a large amount of rock is transported to the surface, influencing the costs at which the ore is produced. Reducing the amount of waste rock being transported to the surface by introducing a near-to-face sorting plant would improve the in many cases strained transport system in the deep mine. In this study, one of Boliden’s cut-and-fill mines was analysed with respect to the challenges related to rock transportation and increasing mining depth. The study aims to evaluate the potential use of a new near-to-face sorting system in the operating underground mine. Discrete event simulation was used to study and analyse the rock transportation system with and without the near-to-face sorting plant. The paper shows how the underground rock transportation system and the production were influenced when the near-to-face sorting equipment was added into the current system. INTRODUCTION The locations of waste rejection in the mining processes and the cost of removing waste from the system compared with the cost and energy necessary for further comminution are important parts in the material handling system (Bowman and Bearman, 2014). In an underground mine, longer material transportation distances generate the need for further investment in the mobile fleet and ancillary equipment in order to reduce the waste from the material handling as early as possible. One of the ways of reducing the waste (coarse particle size) in material handling is by use of pre-concentration. The benefits of pre-concentration are well known (Schena et al. 1990; Feasby, 1995; Peters et al. 1999; Klein et al. 2002), as well as the factors governing the feasibility of underground pre-concentration (Peters et al., 1999) and the mining integration issues (Klein et al. 2003). In the Onaping Depth orebody in Sudbury, Ontario the study of implementing the pre-concentration resulted in increased capital costs of 6% and a reduction in the operating costs of between 20-40% (Bamber et al, 2004). In this paper, the effects on the production and the transportation system of implementing underground pre-concentration by means of a near-to-face ore sorting plant in the Kristineberg mine are modeled and analyzed using the AutoMod tool. This tool is based on discrete event simulation (DES) (Banks, 2004), allowing high flexibility in customization and enabling the user to view the production of the system before ore sorting plant integration. The sorting plant selected in the simulation is built from modules. The material is fed by conveyor and goes through the comminution, classification, sorting and service processes after which the waste is redirected to backfill headings via trucks. The system mechanically ejects the particles from the feed stream on the basis of the information obtained from both the XRT sensor’s signal and 3D laser scanner based on both density and rate of refraction of light within a particular mineral. The sorting plant could pre-concentrate the metal ore up to 300 mm size. The plant requires little auxiliary infrastructure, is easily modularized for underground installation and can be easily relocated to different areas."

Jan 1, 2016

By John M. Gordon

DURING and after 1949, various groups of British mining engineers came to the Dominion Coal Company, Limited, at Sydney, N .S., to see at first hand the Dosco MINER ( 1). These visits culminated in 1952 with the ordering of four Dosco Miners by the (British) National Coal Board on an experimental basis through their Experimental Expenditure Funds. Others are now on order. The first machine was delivered in February, 1953, and, after slight alterations to suit the different power supply, the machine was made ready to work. Due mainly to the size of the machine, new rules and regulations governing its operation had to be put into effect and it was not until April, 1954, that the machine was put underground. It started to produce in June of that year. The three others were delivered early in 1955. The authors were sent to England by the Dominion Coal Company to install and demonstrate these machines and to work with the Coal Board engineers to- further interest in the machines in the British coal fields .

Jan 1, 1956

By J. E. Matta

The methane gas emitted from coal samples collected from the conveyor belts dumping into silos was measured by the Bureau of Mines. Approximately 50 pct of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No simple correlation between the gassiness of the coal stored and the methane concentration in the silo open space above the coal was found. This was probably because the gassier coals were stored in open-top Silos, which were better ventilated. Although the methane concentration in the open space above the coal pile was less than 1 pct for all 34 silos investigated, a methane measurement in the coal pile showed that high methane concentrations can exist. The methane released in the pile appears to accumulate and not liberate freely into the open space above the coal pile. Probably this gas is released during reclaiming operations, but further research is required to substantiate this claim.

Jan 1, 1978

By E. A. Schmidt

The Thompson Creek molybdenum deposit is located in the Bayhorse mining district about 20 air miles southwest from Challis, Idaho. Cyprus Mines Corporation began exploration on the property in 1968, and at present is in the pre-production stripping phase. Molybdenum mineralization is contained in a late Cretaceous (88 m.y.), composite, biotite granodiorite-quartz monzonite intrusive complex. The complex intruded carbonaceous argillites, causing local silicification and hornfelsing of the sedimentary rocks. The main portion of the orebody is unconformably overlain by up to 1000 ft of Challis volcanic rocks (49 m.y.). Surface mineralization and related rock alteration can be recognized over a 2500- x 8000-ft area extending northwesterly from the discovery outcrop. Molybdenite occurs in a network of subparallel quartz-biotite-muscovite-orthoclase veins and veinlets within the intrusive rocks. The zone of +0.020/0 Mo mineralization outlines a steeply dipping tabular configuration in the main orebody and gradually changes into a hood-shaped configuration along strike to the northwest. The overall grade [ ] of the deposit is controlled by the abundance of the quartz- molybdenite veins and veinlets in the intrusive rock. Very little disseminated mineralization is present, and no economic mineralization occurs in the argillaceous sedimentary rocks. Muscovite, biotite, and orthoclase/microcline define three alteration zones that conform with the overall zone of mineralization. The upper alteration zone contains dominantly muscovite and sericite associated with quartz veins. The central zone contains coarse biotite and locally orthoclase and microcline. Molybdenite is most abundant within this zone. The lower zone contains thin envelopes of orthoclase/microcline around quartz veins. Based on about 313,000 ft of drilling and 8592 ft of underground development work, computer-derived ore reserve calculations indicate 200 million tons averaging 0.1 1% Mo at a 0.050/0 Mo cutoff grade with a waste to ore stripping ratio of about 3:l.

Jan 1, 2013

By Guo Xueyi

The environmental impact assessment of the Imperial Smelting Process for metallic zinc and lead production in Shaoguan Smelter, China, was carried out by the life cycle assessment method. The detailed inventory analysis of the Input/Output in the process during 1998-2000 was conducted and the allocation was done among the main products of zinc, lead and sulfuric acid, according to the system expansion and substitution principle, The environmental impacts were assessed by using the following five Eco-indicators: Gross Energy Requirement (GER), Global Warming Potential (GWP), Acidification Potential (AP), Heavy Metal Toxicity (HMT) and Solid Waste Burden (SWB). The results from this study are useful to address the environmental situation of the technology practice in this smelter, and provide a scientific basis for the further improvement.

Jan 1, 2003

By Earl M. Frizzell

This paper addresses considerations for the use of artificial support of pit walls in surface mines, a new project of the Bureau of Mines. Results to date indicate that a polymer-coated cable with embedded grit could provide good anchorage for stabilizing benches and highwalls, and an electronic method of recording discontinuities in the field is being reviewed and developed for application to mining. The objectives of the work in progress are to define the engineering parameters and evaluate the concepts for artificial supports in order to provide safe working environments when pit slopes are steepened to increase ore recovery and reduce overburden handling.

Jan 1, 1986

By A. B. Cecala

An evaluation was recently performed on a district recirculation system at a trona mine in Granger, Wyoming. A 1.52m (5 ft) diameter, 37.3kw (50 hp) vane axial fan was installed in a crosscut between the intake and return airways and recirculated approximately 31.4 m'/sec (66,578 ft'/min) of air back into the intake. This amounted to a recirculation factor of approximately 20 pct of the return air. This air was part of the primary ventilation to three different continuous miner sections at operating distances of between 6l0m (2,000 ft) and 1,829m (6,000 ft) from the recirculation fan. The mine environment was constantly monitored for respirable dust, methane, and carbon monoxide in the operating sections and in the main intake and return entries. In addition, air samples were taken with and without the recirculation system during the evaluation and analyzed using gas chromatography. The results of this study showed only small increases in dust, while all other mine contaminants remained at such low levels that it was impossible to determine any relative changes from the recirculation system. Because of this, a brief SF. tracer gas analysis study was subsequently performed to more precisely determine an increase in a mine contaminant with the recirculation system.

Jan 1, 1991

By Paul Wellman

The energy problem of the U. S; was emphasized by the oil embargo of late 1973 and early 1974 and it seemed for a time that the Federal Government, under pressure from the general public, might take some corrective action. However, this was not the case. With the gasoline lines gone and an apparent plentiful supply of petroleum products, public concern quickly dissipated., This country is more vulnerable to an oil embargo today than we were in 1973-1974 and this fact should be of concern to all our people. Since 1968, we have used oil and natural gas at a much more rapid rate than we have been able to find new domestic sources; thus, there is an increasing gap between domestic production and consumption and we have filled the gap with ever increasing oil' imports. These imports have increased at an alarming rate in the recent past, some 58 percent in 1976 compared with 1975. Imports are nearing 8 million barrels per day. Then, by applying some simple arithmetic, at $12 per barrel, the resulting trade deficit is $96 million per day or $35 billion per year. Obviously, this cannot be tolerated by our economy over a long period of time. Historically, we have shifted from one fuel to another as is shown in this slide. In 1850 about 90 percent of our fuel requirements came from direct combustion of wood, by 1900 we shifted to coal for 70 percent of our fuel, and now about 78 percent of fuel requirements comes from oil and natural gas. The difference is that the previous shifts were voluntary and the one facing us now is of necessity.

Jan 1, 1977

By Z. H. Zhang

Shizhuyuan is a world-class WO3, Mo, Bi and CaF2 poly-metallic deposit; it has rich reservation, but great difficulty in ore?s processing; thereby, for many years, it has been the target problem of beneficiation technologies. This paper, while briefly reviews its main scientific and technological advancement, pays special attention to the complete set of new technology and technical index achieved in recent years, which is characterized by using full-floatation flow-sheet as the backbone flow-sheet, explores some key factors influencing tungsten floatation, and presents a brief introduction to such new equipment as flotation column and comprehensive utilization of fluorite.

Jan 1, 2014

By Kazuhiro Nisizono, Takashi Kuroki, Nobuyuki Mori, Keisaku Ogi

"The improvement of critical current density and mechanical property is essential to the practical application of the superconductive oxides. A solidification technique is developed in this study for the growth of columnar or single Y123 crystal with finely dispersed Y211 and Ag particles through a monotecto-peritectic reaction of Li.(Ba-Cu-Ag-0 rich liquid)+ Y211-+ Y123+Lz(Ag rich liquid). The large solidification rate and temperature gradient can refine the Ag and Y211 particles. But Ag-free region is widely formed along the crystal growth direction in the central part of the Y123 cell. Since this phenomenon occurs because of the cellular growth, it is necessary to narrow Y123 cell width or to grow Y123 crystal with flat freezing interface. By controlling crystal growth direction using a seed crystal, Y123 columnar or single crystal with uniformly dispersed fine Ag particles are obtained. The· behavior of Ag and Y211 particles during the solidification of Y123 crystal is simulated by the peritectic growth model of faceted Y123 crystals.IntroductionY-Ba-Cu-0 superconducting oxide (YBCO) with high critical temperature also has excellent superconducting characteristic under the high magnetic field. The critical current density (Jc) has been enhanced by ·using unidirectional-solidification technique, which can overcome the weak-link problem at grain boundaries and control the crystal orientation and the distribution of Y211 particles which give effective magnetic flux pinning centers in the Yl23 matrix [1-4].In addition to improving superconducting properties, it is necessary to improve mechanical property for the practical application. The silver addition to the melt-textured YBCO superconducting oxide has been reported as the effective method to improve mechanical properties without degrading superconducting properties. Since the material properties are considered to be largely affected by silver particle size, form, dispersion state etc. in the Y123 phase, it is important to control Ag distribution in YBCO/Ag composites. Besides, it is also reported that the silver addition improve the corrosion resistance to the water and CO2 [5,6]. Nishizono et al. [7-9] have reported that the silver distribution in the YBCO/Ag composites is largely affected by the solidification condition, but yet some unclear points are also remained. YBCO has been also fabricated by the zone melting method [10-12], and Furuya et al. [5] and Hirano et al. [13] have reported the fabrication of silver added YBCO composites, but the distribution and behavior of Ag are not investigated in detail"

Jan 1, 2000

By T P. Medhurst

In many cases mine design is the most important driver of the profitability of a mining project, however to reach an æoptimumÆ mine plan many compromises have to be made. Some of the fundamental profit (and loss) drivers relate to stoping methods and stope design parameters. Inevitably trade-offs have to be made between the stability of underground openings, ground support costs and production efficiency. This paper looks at the role of geomechanics in the mine planning and design process. The concepts of æcontrollable lossesÆ and æuncontrollable lossesÆ are developed as a means of partitioning ground control costs. A stope design example is given which provides a method of examining mining costs, and includes a decision making element in order to quantify geotechnical impacts and select stope dimensions. The method also provides a general framework as a means of balancing ground control costs against maximising returns from an underground mining project.

Jan 1, 2000

By Henry E. Perlee

Air compressor explosions that are caused by the ignition of combustible vapor mixtures cannot be explained by a single reaction mechanism or sequence of events. Explosions have been caused by the sudden release of large quantities of lubricating oil, by the rapid vaporization of oil that had accumulated slowly in high-pressure piping, and by the production of decomposition products from carbonaceous deposits. Ignitions can be caused by the heat produced in a catalytic reaction, in a compression process, or when a shock wave is propagated through a combustible vapor-air mixture. The frequency of these ignitions can be minimized by establishing proper maintenance and cleaning schedules. Further study is needed to satisfactorily correlate the various factors involved in compressor explosions.

Jan 1, 1963