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By Walter H. Schwedes

Ore grinding mills are really just slowly rotating barrels, but barrels that are growing in size so fast that the application of electric drives for them is rapidly approaching a technology like that for wind tunnels or pumped storage drives. This application is particularly worthy of care because some 40% of the 75 megawatts of power used by a large copper ore concentrator, or some 60% of the 200 megawatts supplied to a large iron ore concentrator, are for grinding. These ore plants are located where the ore is, not where a utility happens to be. So, the challenge is not only to choose a drive and .power transmission for reasonable cost, high performance, reliability and minimum maintenance, but to afford the interface between mill drive and power distribution and source systems to minimize the whole ore plant's monthly power bill, or costs of self generation. Conclusions can be reached in optimizing a drive selection only for each particular ore plant's set of parameters, but by identifying the criteria for selection and then weighting each type of drive per criteria, yardsticks for final choice become apparent. This is the purpose of this paper. Grinding action takes place inside the barrel, where the ore charge is ground with the aid of balls, or mill length rods, or large chunks of ore as in autogenous grinding.

Jan 1, 1972

By A. Aly Selirn

An economic simulation model was developed to predict the amount of copper recovered from copper oxide deposits and the cost of producing it as a function of the deposit parameters. The economic simulation model includes models of fragmentation design and cost, copper extraction, solution distribution and recovery, effluent solution cutoff grade, and financial analysis. Cost and price indices were also developed to evaluate the economic feasibility of in situ leaching operations as a function of their starting date. Application of the models to various properties having the same area and different ore thickness shows that the effluent solution cutoff grade does not vary with the ore thickness nor with its grade. The percent of copper recovery is, however, shown to increase with the increase in the ore thickness and is independent of the ore grade. it is also shown that while the profit per unit of extracted copper increases with the increase in ore grade or ore thickness, the rate of return on total investment does not show any correlation

Jan 1, 1977

By Dairo E. Chaverra, Carlos Argumedo‑Jimenez, Oscar J. Restrepo‑Baena

This paper presents the results obtained by processing a gold and silver telluride mineral concentrate from a mine in Colombia. An acid wash, also known as acidification, was carried out, followed by oxidation with nitric acid as a pretreatment. Cyanidations of the pretreatment residues were carried out and the results were compared with results from cyanidations of base materials. The removal of carbonates in the acidification, a tellurium extraction close to 90% during the pretreatment, and a 30% improvement in the gold recovery compared to the conventional process were achieved.

Nov 8, 2023

By D. R. Nagaraj

Editor&apos;s note: Minerals concentration is a disparate area, one involving many disciplines. Flotation, flocculation, reagents, microbial processes, gravity and magnetic separation, and the areas of coal and oil shale - concentration is relevant to all of these. In his article, Nagaraj reviews the latest developments and findings in concentration that have ocurred during the past year. Flotation The Monograph Series "Development in Mineral Processing," (Elsevier, 1985) was devoted to "Flotation of Sulfide Minerals." This volume has 26 articles covering the aspects of flotation chemistry, process development, plant design and equipment, and modeling and process control. The numerous articles on sulfide flotation had one recurring theme - the role of electrochemical processes and redox potentials in flotation and depression. Significant advances have been made in this area. A differential desorption-reflotation process was developed for the beneficiation of calcitic phosphate pebble (Hsieh and Lehr, Industrial Engineering and Chemistry, 1985). The carbonate and phosphate minerals were first separated from silica using fatty acid and the modifiers diphosphonic acid and HF. The collector on phosphate was then desorbed using sulfuric acid, and calcite was selectively floated without additional collector. A two-stage conditioning - initially at pH 10, followed by that at pH < 4.5 - with sodium oleate was developed to improve the separation between apatite and dolomite (Moudgil and Chanchani, Minerals and Metallurgical Processing, MMP, 1985). Separation of Mussorie rock phosphate in India from gangue calcite, dolomite, silicates, pyrite, and carbonaceous impurities was achieved with a three-stage flotation only on -75 µm (-200 mesh) fraction (Vaman Rao et al., International Journal of Mineral Processing, IJMP, 1985). The separation of fine SiC whiskers from other products of coked rice hulls by immiscible liquid and froth flotation was achieved using M1BC, pine oil, and mineral spirits (Parekh and Goldberger, MMP, 1985). Flotation was more economical. The carrier flotation separation of hematite fines from quartz fines was effected using coarse hematite as a carrier and oleic acid and ferric chloride (Cristoveanu and Meech, CIM Bulletin, 1985). Potash recovery from brines by laboratory-pan solar evaporation and amine flotation was discussed by Foot and Juiatt (Salts and Brines &apos;85, Proceedings, 1985). Flotation in a 45-kg/h (99-lb per hour) unit recovered more than 95% of the potash in schoenite and sylvite concentrates containing 28% and 62% K2O, respectively. The effects of fresh concrete into cement and aggregate by a single-step flotation process in aqueous suspension was described (Naegle, Chemical Engineering Science, 1985). The physico-chemical principles for the selective separation of proteins from mixtures using flotation were discussed by Ostermaier and Dobias (Colloids & Surfactants, 1985). Selective flocculation of hematite from silica was studied by Bagster and Mcllvenny (IJMP, 1985). Selective flocculation was more favorable with more highly charged anionic polyacrylamides and with high molecular weight. The cationic and non-ionic polymers flocculated both minerals. In minerals mixtures, there appeared to be very little selectivity unless a combination of dispersant and electrolyte was used. The effect of dissolved minerals species, such as Cu, Fe, and Ni on flocculation of chalcopyrite, pentlandite, millerite, pyrrhotite, and covellite was studied by Acar and Somasundaran (SME-AIME, 1985). Reagents There were some major advances made in reagent development for the minerals processing industry. Cyanamid introduced several classes of collectors, one of which - the diaryl monothiophosphates as acid circuit col¬lectors of sulfides and oxidesulfide ores - was commercialized in 1985. The monothiophosphates are more stable and powerful collectors than the xanthates and dithiophosphates. Hydrolyzed dithiophosphate containing 80% monothio and 20% dithiophosphate was found to give optimum recovery of copper from crude cementation precipitate and separation of Cu and Ni sulfides from matte (Akimova et al., Obogashch, Tonkov, Rud, OTR, 1985). A new class of O-alkyl-Nallyl

Jan 9, 1986

By L. J. Blatnica

Throughout the 1980&apos;s the tem Mine-Wide Monitoring System has had various meanings for manufacturers of these systems and underground mine operators alike. System suppliers had visions of grandeur in the early 80&apos;s as they envisioned each mine, that has more than a single section, installing a computer based monitoring system to provide surveillance, control and documentation of the entire mining operation, including everything from a single heat detector to the weekly payroll. In a few cases this may have become reality but the truth is these systems have quietly become a steady but unspectacular workbase for the modern mining industry of the 1990&apos;s. As it exists today the total market for underground monitoring systems may not exceed $10 million annually. Suppliers have lowered their expectations of the dollar value of this particular market. Some were entering a new market because of experience with computer based data acquisition systems. Others had been active in the mining industry for years with more traditional equipment (communication systems, methane monitors, safety equipment, etc.) and decided to become involved with Mine-Wide Monitoring Systems.

Jan 1, 1990

By Charles H. Wells

This paper presents a review of the state of the art in coal preparation plant instrumentation and a discussion of automation practice that could be applied based on current mineral beneficiation experience and demonstrated foreign technology in coal washing plants. Specific e-mules of applications of remotely controlled slurry values, pneumatic and electronic field transmitters, computers for control and data logging, and on-line analytical instrumentation are given. A program, to demonstrate this technology is described.

Jan 1, 1980

By Teena Redhorse, David Tsztoo, Anthony Yu

"Since ancient times, storing and conveying water via underground water systems and tunnels has been touted for its strategic advantages. Underground cisterns and tunnels assured protection of essential fresh water supplies from man made contamination and especially from enemies who would gain an advantage by disrupting an adversary’s water supply in a siege. Modern day engineers do not usually specify tunnels for reasons of avoiding deliberate contamination or siege — however, they are just as enamored with the idea of building tunnels for water conveyances.Such was the case for the San Francisco Public Utilities Commission (SFPUC). The SFPUC provides drinking water to 2.6 million residential, commercial and industrial customers in the San Francisco Bay Area. The SFPUC’s water system includes 257 km (160 miles) of transmission pipelines and tunnels from the SFPUC’s largest reservoir, the Hetch Hetchy Reservoir inside Yosemite National Park, to San Francisco. About 129 km (80 miles) of the system consist of tunnels. A 30-km (19-mile) section of the tunnel network, called the Mountain Tunnel, was thought to be at risk of a catastrophic failure in its concrete-lined section of 18 km (11 miles). For much of the project planning process, a new replacement tunnel was presumed to be required according to the tunnel planners.Originally constructed between 1917 and 1925, the Mountain Tunnel has been in continuous service since 1925. The 30-km (19-mile) tunnel is located downstream of the Hetch Hetchy Reservoir water source in Yosemite National Park, between the Early Intake and Priest Reservoir (Fig. 1). Approximately 18 km (11 miles) of the tunnel is lined with unreinforced concrete. Though the condition of the tunnel was being monitored through water sampling and periodic inspections, there was growing concern that the tunnel lining was at risk of a partial collapse that could interrupt water delivery for up to nine months. The SFPUC was faced with a decision to construct a new bypass tunnel to replace the lined section of the Mountain Tunnel or to rehabilitate the existing tunnel."

Jan 6, 2018

By Michael F. Gleason

In 1986, Gold Fields began negotiations with a large Nevada electrical power utility to supply power for its Chimney Creek Mine In northern Nevada. After the long negotiations reached an impass over various costs associated with the power line, a decision was made by Gold Fields to generate its own power. Self-generation is not uncommon overseas, but it is rare for any but very large or very small operations in the United States. Surprisingly, under certain conditions a mine can generate its own power profitably and Gold Fields has found that the associated operating and maintenance problems are minimal. The following report details what factors went into this decision and how it works. Hopefully, it can serve as a guideline for those who may find themselves in a similar position.

Jan 1, 1990

By J. O?Hanlon

The 4500 m3 blast furnace at the Redcar Works of ESC operates or, a burden of sinter and pellets, both materials being produced within the works. The early history of the furnace was given to the AIME Ironmaking Conference in 1981(1) when the burden was 65% superfluxed minter and 33% acid pellets. While ironmaking performance was adequate, it was felt that there were advantages to be gained by the use of fluxed pellets. For example, Kobe Steel had reported (2) that the rise of 30-50% dolomite fluxed pellets had enabled them to achieve better furnace permeability, higher gas utilisation, and enhanced ore/coke ratios. It appeared probable to BSC that the use of magnesia-bearing fluxed pellets would give a burden which had compatibility of softening and melting properties, i.e., fluxed sinter and dolomite pellets would result in a thinner cohesive zone because of closer matching of softening and melting temperatures, with consequential benefits on furnace stability and efficiency.

Jan 1, 1983

By R. Berton, M. Walden, S. Melberg, N. Rocco

Recent tailings dam failures around the globe have influenced many mining industry regulators to reassess their requirements for the numerical modelling of tailings dam failures. This type or forward modelling is associated with overarching uncertainties as the model cannot be calibrated against a physical result. Dam breach analyses that meet the requirements of current industry standards and guidance typically begin with identification of credible failure modes and selection of appropriate topographic data set to represent the study area. The breach parameters and the volume of tailings released are then determined using available methodologies and empirical relationships. Subsequently, when the breach hydrograph is developed and the hydrology of stream networks are complete, the runout simulation is implemented. Due to the uncertainty involved in the process, sensitivity analyses are recommended to quantify variations in model inputs on the inundation extent and the flow characteristics. This paper outlines some common methodologies utilized for development of dam breach models, summarizes associated uncertainties with these methodologies and inputs, and provides guidance on how sensitivity analyses can address a wide array of uncertainties inherent in tailings breach analyses. This paper provides an understanding of how selecting appropriate breach parameters can result in reasonably conservative inundation extents consistent with the identified credible failure modes.

Mar 2, 2022

By J. R. Hoskins

Method - A direct approach to instrument users, initially by letter and later by telephone or personal contact was made. The resultant data was compiled to give specific use information on the seven instruments. During the course of the study attempts to evaluate the Griswold Gage were abandoned when it became apparent that the gage was not being commercially produced. One company is developing the gage for its own use. The information presented is the result of over 1200 inquiries.

Jan 1, 1973

By H. E. Hirsch

Propelled by the invention of the transistor at Bell Laboratories, germanium&apos;s unique properties have advanced our electronic world by many years. Germanium has found major uses in infrared optics, fiber optics and a revised vigor as a catalyst for PET plastic production. Other advanced applications are in various stages of development. The solid state electronics industry has been the driving force behind the accelerating demand for gallium since the late sixties. Past developments of substrates for light emitting diodes, lasers and magnetic bubble memories are paling in view of the current excitement over the use of semi-insulating gallium arsenide for high performance integrated circuits. This application requires gallium metal and gallium compounds of extraordinary purity.

Jan 1, 1986

By Basilio Giurgola, Jeremiah M. Jezerski, Filippo Azzara, Federico Bonaiuti, Russell H. Lutch

The Northeast Boundary Tunnel Project consists of a 23 ft diameter, 27,000 ft long, CSO tunnel, multiple underground connections, and significant surface works within an urban corridor. The NEBT alignment depths range from 60 to 140 ft and includes seven shafts ranging in depth from 77 to 155 ft with diameters varying from about 19.5 to 56 ft, some as in-line connections and others required adits for connection to the main tunnel. This paper focuses on the design and construction of two major underground connections which are the First Street Connector Tunnel and the Mount Olivet Road Diversion Sewer.

Jun 13, 2023

By Earl M. Woodward

INTRODUCTION Kerckhoff-2 is a 140 MW underground hydro-electric project designed and owned by Pacific Gas and Electric Company and constructed between May, 1980 and May, 1983 by Auburn Constructors. The project is located in the western foothills of the Central Sierra Nevada Mountains, about 30 miles northeast of Fresno, California, and develops the power potential of the lower San Joaquin River and its tributaries between the existing Kerckhoff and Millerton Lakes. The Kerckhoff-2 Project consists of project roads, adits, and access tunnels, service tunnels, power tunnels, powerhouse, tailrace tunnel surge shaft, buss shaft, intake structure, discharge structure, and switchyard. In the 1920s, the Kerckhoff 1 project, consisting of a dam, reservior, tunnel, and 34 MW powerhouse, was built in the same general area as Kerckhoff-2. The tunnel was constructed by conventional methods, and was left unlined. In time, other projects were built upstream, allowing the flow of the San Joaquin River to be regulated. The Kerckhoff 2 project is designed to harness that regulated flow, providing an additional 140,000 ON of power. Kerckhoff 2 will be the primary power plant; Kerckhoff I will produce power whenever the flow rate exceeds 4,800 cubic feet. The new power tunnel is built along the east side of the San Joaquin River between Kerckhoff and Millerton Lakes, parallel to the existing tunnel but extending approximately one mile further downstream.

Jan 1, 1983

By Roger Escoda Estelrich, Joan Carles Casado Ortega, Mitchell Gerdau, Jose Raul Martinez, Jeb Pittsinger, Frank Perrone

The existing Chesapeake Bay Bridge-Tunnel complex is being expanded to include the Parallel Thimble Shoal Tunnel. This will be a subaqueous bored crossing between two islands constructed for the original 1960s immersed-tube tunnel. Jet grouting was employed by the Chesapeake Tunnel Joint Venture (CTJV) to provide watertight base plugs, launch and retrieval blocks for the tunnel boring machine (TBM), a TBM canopy to limit ground movement, and a retaining wall to enable off-island excavation: all within hydraulically placed sands. This paper will review the design and construction challenges, including soil permeability and recharge, grout communication, installed grout strengths, and remediation requirements.

Jun 23, 2024

By Gordon Clark, Basar Arioglu, Nasri Munfah, Sanja Zlatanic, Tolga Togan

"The 13.2 m (43 ft) external diameter, double deck Istanbul Strait Road Tube Crossing is one of the most challenging underwater tunnel projects in the world. Subjected to 11 bars of hydrostatic pressure, variable geology, and being in a very active seismic area, the execution of the project required innovative solutions, sophisticated construction techniques and prudent risk management approach. The 5 km (3.1 mile) tunnel consists of a 3.4-km (2.2-mile) tunnel boring machine- (TBM) bored tunnel, 1 km (0.62 mile) twin NATM tunnels and cut-and-cover sections. The project is being delivered in a build-operate-transfer (BOT) contract in a public-private partnership. The technical challenges, coupled with financial and commercial risks required the implementation of sophisticated risk management tactics including the provision of independent design verification. The project was opened to traffic on December 20, 2016, four months ahead of schedule.. This article presents the technical challenges of the project from the design, construction, and risk management aspects..Project backgroundThe $1.245 billion Istanbul Strait Road Tunnel Crossing project, dubbed the Eurasia Tunnel, is one of several major infrastructure projects being implemented in the Republic of Turkey in a public-private partnership approach. The project provides a direct and easy connection between the Anatolian (Asian) side of Istanbul and the heart of its historical district on the European side across the Bosphorus Strait which connects the Black Sea with the Sea of Marmara. The project improves connections to a wide network of motorways on both sides, increase capacity across the Bosphorus by 100,000 vehicles a day, reduces congestion and saves motorists an average of 45 minutes of commuting time in each direction bringing significant economic benefits to the city and the region. It eases traffic across the strait, reduces congestion, decreases pollutants and emission while maintaining Bosphorus. It is the most complex part of the project with the greatest challenges and risks. Part 2 is 5.4 km (3.6 miles) long consisting of 3.4 km (2.2 miles) of 13.2 m ( 43.3 ft) external diameter TBM bored tunnel under the Bosphorus Strait, 1-km (0.62-miles) of twin NATM tunnels on the Asian side, cut-and-cover transition boxes in the Asian and the European sides and depressed approaches on both sides. In addition, this segment includes the toll plazas, ventilation buildings, and the tunnel control and maintenance facilities."

Mar 1, 2017

By A. Anttila, S. Persson

The grinding mill is probably the most common unit operation in mineral processing. There is, however, much that can still be done in the way of optimization. This paper discusses the results of a well-controlled pilot-scale test in which the performance of a tumbling mill equipped with a conventional rubber lining and lifter bars was compared to a tumbling mill equipped with a smooth rubber lining of the magnetic type. The results indicate that the smooth lining is about 14% more effective with respect to energy consumption. By optimizing the size of the grinding media, the mill capacity can be increased in many grinding operations. In this specific case, grinding with a -20-mm ball charge required 26% less grinding energy than grinding with a -30-mm ball charge. The energy savings can, in most cases, be converted to an increase in capacity. The wear of the grinding media is difficult to assess over a short test period, but the results suggest that the wear is somewhat less when a smooth lining is used. A determination of the wear of the linings was not included in this study, but it is generally accepted that the use of magnetic linings reduces the lining costs dramatically. Computer simulation using the Millsoft code developed by Mishra et al. confirms and explains the increased effectiveness of comminution when a smooth lining and smaller grinding balls are used.

Jan 1, 2000

By K Martin, C. J. Nelsen, J. L. Schutz, S. R. Maynard

Investigations in the Ortiz Mountains have revealed the relationship of igneous activity and gold mineralization to the Tijeras-Canoncito Fault System (TCFS). The northeast-trending TCFS passes through the southeastern part of the Ortiz Mountains where its principal structure is the asymmetric Ortiz Graben. Several fault blocks, containing up to 305 m (1000 ft ) of Eocene Galisteo Formation, comprise the graben that has up to 1220 and 610 m (4000 and 2000 ft) of stratigraphic separation on its southeast and northwest sides, respectively. Intrusions in the Ortiz Mountains can be subdivided into two petrochemical types: an older calcalkaline suite and a younger alkaline suite. The calc-alkaline rocks are characterized by extensive sill, dike, and laccolithic bodies of latite-andesite intrusives and at least one younger (?) granodiorite stock at Candelaria Mountain. The alkaline rocks consist of a large nepheline-bearing augite-monzonite stock, a latite-porphyry hypabyssal plug, the Ortiz diatreme (vent breccia), and trachytic-latite dikes radial to the diatreme. K-Ar age determinations suggest the older suite to be 34 +/-2.2 million years while the younger alkaline rocks range from about 30 to 26 million years. Gold mineralization in the Ortiz Mountains occurs in five distinct environments: brecciapipes, skarns, veins, porphyry-like stockworks, and placers. Lode mineralization is associated with the alkaline suite of intrusive rocks postdating the Ortiz diatreme and predating most of the trachytic-latite radial dikes.

Jan 1, 1991

By Yoginder P. Chugh

Physical mine modeling and computer simulation techniques were used to conduct technical feasibility and economic analyses of selected pit configurations for surface mining a single coal seam dipping at about 15 percent to a maximum depth of 150 feet. The pit orientations along the dip (dipline), strike (strikeline) and along an apparent dip were studied. Physical models of each pit configuration were prepared first to delineate potential operational problem areas, and also to furnish a data base-for the computer simulation models. A dragline micro- simulation model (Fluor), a shovel/truck simulation model and a cost analysis model were used to conduct the study. Sensitivity analyses were conducted on variables such as the pit width, block length, and angle of dip. The productivity (Cu.yds/hour) of the mining equipment (dragline or stripping shovel) under each set of conditions was used to optimize the pit configuration. Both block length and panel width were found to significantly affect the dragline productivity larger size trucks were preferable to smaller size trucks in the pit configuration along an apparent dip. The cost analysis results showed that the pit configuration along the seam dip was more economical than the pit along the strike or along an apparent dip.

Jan 1, 1984

By W. H. Stahl

The continuous vacuum filtration is the solid-liquid separation process that is nowadays most frequently used in the beneficiation industry all over the world. After a development time of several decades, the various filter types such as drum filter, disk filter, plate filter and belt filter can be consideres as a sound functional design ensuring a trouble-free operation. Nevertheless, the vacuum filtration does no longer meet the present and future technological requirements. The moisture content of filter cakes is too high. Their thermal secondary drying is too expensive (coal, ores) and may bring about undesirable material changes and the filter cake conditioning with water-binding substances for dumping purposes is too costly.

Jan 1, 1983