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By M. S. Moats, A. Luyima, W. Cui

"Organic smoothing additives are used to produce dense, thick, high-quality cathodes in copper electrowinning. Glue had been used traditionally and is still used in operations that do not employ solvent extraction to produce the electrowinning electrolyte. With the advent of solvent extraction–electrowinning, guar started to be used and remained in use for many years as it does not affect the phase disengagement in solvent extraction. Recently, however, guar has been replaced by less-expensive saccharide- and polyacrylamide-based additives. This paper is the first of a series of four papers that examine saccharides and polyacrylamides as new additives for copper electrowinning. A review of previous research related to copper electrowinning additives is presented here, along with a selected review of additives in other copper electrodeposition systems.IntroductionThe recovery of copper from solution by electrowinning was first practiced in the early 1900s, but it was the combination of solvent extraction with electrowinning (SX-EW) in March 1968 at the Ranchers Bluebird Mine (Kordosky, 1992) that changed the landscape for the electrowinning process. Most copper electrowinning capacity is now associated with solvent extraction, though some copper is still won directly from leach solutions (Robinson et al., 2013). The ability to produce high-purity copper cathodes from SX-EW has taken the continued improvement of SX-EW technology over the past more than 40 years.One of the technologies that has seen improvement is that of the organic smoothing agents used during the electrodeposition of copper in the tankhouse. These organic additives are added to the acidic copper sulfate electrolyte during electrowinning to improve the smoothness, brightness and density of the copper cathodes. The organic additives that are presently in use are different from those used in 1999 (Jenkins et al., 1999). Over the past decade, many tankhouses have replaced the use of guar-based organic additives with those derived from other saccharides. Until now, there has been no comprehensive publication in the open literature on the behavior of these additives during copper electrowinning."

Jan 1, 2016

By M. Howe

This is a study of the impact of cyanide from mining waste on riparian communities, primarily vegetation, near Whitewood Creek, down-stream from Homestake Gold Mine in Lead, South Dakota. Cyanide is used in gold processing and the effluent, until fairly recently, was discharged directly into Gold Run Creek which empties into Whitewood Creek. Vegetation, soil, and water were collected from four different sites over a six month period, and samples tested for cyanide concentration. Data indicate a relationship between cyanide in soil and its uptake by certain plants, also, that the Homestake cleanup effort has made the stream viable again.

Jan 1, 1983

By X. Zhu, Chen. L., R. Guru, M. Peiravi, M. Mohanty, L. Ackah, B. Xu

"The overall goal of this study is to develop a suitable flow sheet to extract rare earth elements (REEs) from coal ash. A total of 14 coal samples of different ranks were examined for REE concentration, and an anthracite coal sample with the highest REE concentration of more than 700 ppm in the coal ash was selected for REE extraction tests. This paper reports on the results of the experimental program completed in the first part of the study, which included hightemperature leaching with nitric acid followed by solvent extraction tests using various organic extractants, namely, tributyl phosphate, Cyanex 572, di-(2-ethylhexyl)phosphoric acid (D2EHPA) and their combinations. A 4×2×2 experimental design was used to conduct a total of 32 high-temperature leaching tests by varying acid molarity at four levels, solids content at two levels and leaching time at two levels. The highest recovery rates of 90 percent for light rare earth elements (LREEs) and 94 percent for heavy rare earth elements (HREEs) were obtained from the optimum leaching test conditions while maintaining impurity recovery to the leachate at less than 40 percent. D2EHPA was found to be the best extractant in this solvent extraction test series, providing an REE recovery rate of nearly 99 percent.IntroductionGlobal demand for rare earth elements (REEs) and other strategic metals is increasing rapidly due to their use in a variety of advanced technological applications, with more than 100 kt of rare earth oxides used worldwide on an annual basis. The United States has less than 10 percent of the world reserves of REE mineral deposits, and in 2013 imported more than 60 percent of its rare earth oxides from other countries, mainly China (United States Geological Survey, 2017). China’s institution of export quotas has significantly reduced supply to the United States, raising the urgency of finding new ways of producing REEs and/ or substitutes. Coal combustion byproducts, which are usually discarded as waste materials, are known to contain REEs in low concentrations that could be extracted with a suitable process flow sheet. This may be a worthwhile route to pursue, considering the short supply of rare earth minerals and the abundance of coal ash in thousands of ash ponds in the United States. More than 110 Mt of coal combustion byproducts are produced annually in the process of satisfying the country’s need for electricity (American Coal Ash Association, 2016), and less than 50 percent of these byproducts are being successfully used in various applications, with the remainder dumped as waste materials in landfills and ash ponds."

Jan 1, 2017

By A. Dell’Era, E. Ciro, C. Lupi

The indium recovery via electrowinning from sulfate baths has recently gained significant attention as it does not present toxic emissions, hermetically sealed system requirements, human health, and environmental hazards. Following previous works related to the optimization process for AISI 316L and Ni cathode, it was observed significant importance of the metal supports on the input and output parameters of the indium electrowinning process from sulfate solutions. Thus, comparing input and output parameters in both cases seems very interesting. Particularly, regarding the input parameters, the attention has been focused on the electrolyte composition, current density, and temperature, while productivity, morphology, and structure have been considered regarding the output parameters. Considering the productivity as the optimal output, the findings for Ni cathode were better than that for AISI 316L in most of the selected conditions studied. In the case of morphology, indium grains appear rounded and dendritic on the AISI 316L, while those on the Ni cathode show stratified lamellar grains. Anyway, the indium deposit obtained on Ni cathode shows bigger grains independently from the used operative conditions with respect to that on AISI 316L. Regarding the structure, it is clearly tetragonal, but preferential orientation, crystallinity, and deformation of the structure strongly depend on the metal support.

Jun 14, 2023

By M. Zhang, M. Menabde, R. Middleton

Whilst mine planners almost universally assume deterministic forward commodity prices when undertaking valuations of mining projects, historical data well demonstrates that those prices are quite volatile. This paper seeks to understand and quantify how this forward price uncertainty will impact mining project valuation. This paper will also present a way of computing an upper bound on the expected Net Present Value (NPV) of a mining project given forward commodity price uncertainty.

Jan 1, 2007

By SH. Shahsavari, H. Akbari, M. Noaparast, M. Oliazadeh

Mejel valley zircon ore in Iran is located in north part of Iran and was sampled to evaluate its concentration. The aim of this project was to define the mineralogy of this zone and separating zircon from other minerals using gravity concentrators and magnetic separators. It is constituted of various valuable minerals, mainly zirconium, niobium-tantalum, titanium, rare earth elements particularly cerium-bearing minerals namely zircon, sphene and rare earth elements oxides. We used statistical method for designing of experiments. Yates method used for analysis of basic experiments results. The grade of zircon in primary sample was 1.1%. Different experiments were designed to optimize all required parameters. The final concentration with 75% zircon was produced and final recovery was 79%. Finally, lab-scale based flow sheet was prepared using experiments results.

Jan 1, 2005

By Paul C. Jones

Summitville is an old mining district located south of Wolf Creek Pass in the southern San Juan Mountains of Colorado at an elevation higher than 3500 m (11,500 ft). The Summitville mine site is about 40 km (25 miles) southwest of Del Norte. The current mine, developed by Galactic Resources Ltd. and its subsidiaries in the mid-1980s, is on the north facing side of South Mountain. The area is drained by Cropsy Creek to the east and Wightman Fork to the north, both tributaries to the Alamosa River. Mining in the Summitville area began in 1870 when James Wightman discovered placer gold on what is now known as Wightman Fork of the Alamosa River. The first vein-type deposits were located in 1873 on South Mountain near the current Summitville Mine. Mining began in the district in 1875 and continued sporadically through 1942. Major mining episodes occurred from 1875 to 1894 and from 1926 to 1942. Total gold production from the mining district through 1949 totaled 7.5 t (240,000 oz). An additional 7.7 t (249,000 oz) were produced during Galactic's tenure. Natural degradation of the outcropping sulfide-rich veins in the area and the early mining activity, including development of the Reynolds, Dexter and Iowa drainage tunnels in the late 1890s, have polluted the streams draining the area with heavy metals and acidic water. Names of the various tributaries to Wightman Fork, such as Iron, Alum and Bitter Creek, testify to this natural pollution. This degradation has reduced, or killed, aquatic life in several area creeks, including Wightman Fork, for many years before recent mining activity.

Jan 1, 1993

By S. M. Jarrett, W. B. Schmidt

Within the last year, the Nation has been shocked by two major tunneling disasters. Almost exactly a year ago 17 men died in the San Fernando Tunnel in an explosion attributed to gas. A few months later another 21 men died in an explosion laid to the same cause at Port Huron, Michigan. The analysis of the causes of these accidents is still continuing. While it appears that they differ substantially from each other in their specifics, they share the common trait that, like most industrial accidents, they might well have been prevented. Gas explosions in tunneling are neither new nor particularly unusual. Forty years ago, Assistant Director Jarrett was hired as a safety engineer on the Hetch Hetchy Aqueduct in California after an explosion that killed 12 men. Prior to 1946, in California alone, the Bureau of Mines had recorded 27 gas explosions incidental to hard rock mining and tunneling. The purpose of this paper is to review the status of the principal regulations affecting tunneling and to indicate some ways in which safer and more healthful conditions can be obtained. The Bureau of Mines was established by an Act of Congress of May 16, 1910. Since that time the Bureau has been making investigations and compiling and publishing health and safety data relating to mining and to tunneling. If any benefit is to come from an anaylsis of tunneling accidents, it must be the knowledge needed to prevent their repetition. The Bureau of Mines has also had informal discussions with the Department of Labor regarding the possibility of the Bureau's assuming that agency's responsibility for tunnel inspections.

Jan 1, 1997

By D. M. Bodily, M. D. Deo, E. M. Whitney

Field data from coalbed methane wells indicate a significant variation in composition as a function of flow rate and time. In particular, San Juan Basin wells have displayed an increase in C02 concentration over time. Prediction of gas quality is critical to the economic evaluation of any coalbed project. Previous models have forecast only pressure and production profiles, ignoring compositional variations. In this study a multicomponent model that incorporates binary isotherms for methane and carbon dioxide has been developed. An extended Langmuir isotherm is used for the adsorption representation and a constant separation factor (similar to relative volatilities in distillation) describes the phase distribution of the species. This separation factor depends both on the surface characteristics of the coal and on the adsorbing species. The chromatographic separation equations have been superimposed on Darcy's law flow. The formulation allows decoupling of the pressure and compositional partial differential equations. The equations have been cast in dimensionless form and solved for pressures and compositions. It is observed that the composition of the preferentially adsorbed C02 increases at the wellbore as a function of dimensionless time. The dimensionless time is directly proportional to the real time and coalbed permeability and is inversely proportional to the gas viscosity, coal porosity and the square of the length of the reservoir. As the separation factor increases, the compositional variation increases. This variation in produced C02 concentration is also greater when the initial C02 concentration in the reservoir is higher. A sensitivity study has been performed to identify the effects of important parameters such as isotherm variables and reservoir characteristics on pressure and composition profiles.

Jan 1, 1993

In this study, the flotation performances of ethoxycarbonyl thionocarbamate (ECTC), dialkyl thionocarbamate (DATC) and xanthate copper sulfide collectors are compared by the structure-reactivity relationship using generalized perturbation theory and density functional calculation at the B3PW91/6-31G(D) level. The electron-donating power of xanthates is strong and, therefore, xanthates can strongly react with metal cation on the surfaces of copper and iron sulfide minerals through the formation of normal covalent bonds. This explains the poor selectivity of xanthates and also the high pH levels (above 13) required for the flotation separation of copper/iron sulfide minerals. DATCs are more selective for copper sulfide flotation, particularly against gangue iron sulfides. Although less powerful than xanthates, DATCs can perform copper/iron flotation separation at lower operating pH (commonly at pH levels below 11.5). ECTCs use an ethoxycarbonyl replacing an alkyl N-substituent in DATCs. The presence of the ethoxycarbonyl group effectively changes the functional group of collector from -C(=S)NH- to -C(=S)NHC(=O)-. The strong electron-withdrawing ethoxycarbonyl group adjacent to the C=S group decreases the electron density of the sulfur atom, which improves ECTC?s selectivity against iron sulfide minerals at slightly alkaline conditions. The lowest unoccupied molecular orbit (LUMO) of ECTC, which is constituted by the pz-orbit of every atoms in the conjugate -O-C(=O)-N-C(=S)-O- group and which is pleased with accepting richly d-orbital electrons (feedback electrons) from the (t2g)6(eg)3Cu(II) or t6e4Cu(I) configuration of copper cation on the surfaces of copper sulfide minerals, resulted in the formation of dative p-bond. The iron atom, which has a (t2g)6Fe(II) or (t2ga)3(ega)2 Fe(III) configuration on the surfaces of iron sulfide minerals (Fe(III) is the predominant composition at alkaline conditions), has difficulty in offering its d-orbital electrons (feedback electrons) to ECTC?s LUMO. ECTC collectors are powerful for copper sulfide minerals and very selective against iron sulfides, which has been further confirmed by UV spectra and bench-scale and industrial-scale flotation tests.

Jan 1, 2008

By C. J. Pritchard, R. E. Gundersen

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyurethane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft- are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners' safety. Although these heavy polyurethanes lend themselves to a "pouring" application around the annulus of the shaft liners and is a continuous process, past experience with atomizing and frothing polyurethane spray systems indicates a high degree of maintenance and operator attention to the nozzle1 delivery system. This may require more miner's time to be spent in the shaft maintaining the foam system, negating some of the safety advantages of the system. If polyurethane foams are to be used in mines, they must be of the highest quality available in terms of flame spread, heat emitted while curing, and contaminants emitted while curing and spraying. In addition, employees must be given adequate training and be thoroughly informed in all aspects of polyurethane foam safety procedures. As witnessed by our fellow miners in South Africa, we can accept no less.

Jan 1, 1991

By Hans Treichl

1. INTRODUCTION For Europe the Arlberg road tunnel signifies the elimination of the largest traffic barrier between Bucharest and Paris in the east-west transversal. Apart from that the tunnel will serve the feeder system to the two north-south links Ulm - Milano, and the Brenner motorway, and links the Inntal and the Rheintal motorways closer together.. Thus, the supraregional road system carrying traffic through the Tyrol and Vorarlberg will considerably be emproved by the Arlberg road tunnel. 2. THE PROJECT The 16.1 km contract section of expressway S 16 includes a ramp section of approximately 2.6 km, the access points at St.Anton and at Langen, and the main 13.98 km section of the road tunnel. This section cuts the link between St.Anton and Langen by 3.7 km, and saves 475 m in altitude. The Arlberg road tunnel is planned to have two tubes with two lanes each. In the first stage the southern tube was under construction. Its traffic capacity is 1,800 car units per hour. The tunnel has a cross section of 9o to 103 m2. The sloping gradients are by 1.3o and 1.67 per cent. Fresh air is supplied and used air removed through a ventilation system, fed at the portals and through two vertical ventilation shafts. One of them, at Maienwasen, is 222 m deep, its cross section 66.5 m2. The diameter in clear is 8.32 m. The vertical shaft Albona is 736 m deep, the diameter in clear is 7.37 m. The tunnels is 9,4o m wide, providing for a 7.5o m roadway plus o.95 m sidewalks on each side of it. 4.7o m above the traffic area the conduits for fresh and used air. A transverse ventilation system with reduced exhaust air has

Jan 1, 1979

By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By R. A. Williams

The Pascua Lama Project is situated on the border of Chile and Argentina at an elevation of 4,800 m. The ore contains gold, silver and copper, and an initial milling production rate of 33,000 t/d is planned. The mineralogy of this deposit is unusual. The ore is hard and abrasive, and it contains a complex array of sulphate minerals, such as chalcanthite, jarosites and alunites. The sulphides are predominantly enargite and pyrite. A novel flowsheet has therefore been developed, which includes dry grinding and ore washing to remove and then neutralize the soluble salts, prior to flotation, cyanide leaching and Merrill-Crowe recovery of the precious metals. These metallurgical issues and challenges associated with plant design and construction in the high and remote Andes Mountains make this a particularly challenging project.

Jan 1, 2001

By William G. Fischer

This paper attempts to close the gap between extensive rock testing with field measurements and the mine operator's need for safe mine layouts and alternatives. It was found that many of the variables that influence mine geometry and worker safety are relatively unimportant while others are critical. The development of empirical relationships which tie the critical variables to the "safe useful life" of a trona mine layout and observations made in 140 production areas where the variables were researched over a fifteen year period are discussed. The concepts presented may have applicability in mine design for other bedded deposits.

Jan 1, 1984

By John H. Raymer

Groundwater inflow into hard rock tunnels is strongly affected by recharge and drawdown of the water table. Previous analytical and empirical methods for estimating inflow have generally not accounted for these factors in an accurate or systematic way, resulting is wrong conclusions about inflow and the effects of the tunnel on the surrounding environment. This paper discusses these issues and provides some simple analytical equations to estimate inflow and water table drawdown around the tunnel. Examples from tunnels in the Atlanta area are provided.

Jan 1, 2005

By S. Lähteenmäki, P. Koivistoinen, J. Levanaho

Semi Autogenous Grinding (SAG) circuit is the most common grinding circuit to day. In Europe and South Africa fully autogenous (AG) circuits are also popular. SAG circuit has a lower capital cost and simple operation. SAG circuit requires the use of grinding balls, which increases operating costs and decreases availability. An AG circuit may produce a higher Net Present Value to the investment. The AG circuit is more complex to design and operate. However, operating experience from AG circuits illustrates that an AG circuit can be as trouble free as a SAG circuit with the benefit of lower operating cost.

Jan 1, 2001

By Paul K. Edwards

The forces of nature have concentrated sand at various geographical locations that are being mined and processed for a large variety of industrial uses. While most operations serve a number of industries, this paper deals only with the foundry requirements. The forces that have decomposed a source rock, transported this material and redeposited it, have created two general types of sand. These types are classified as the (1) Lake and Bank Sands and (2) Silica Sands. The Lake and Bank sands will contain 92 to 94% Sio2 while silica sands are in excess of 98.5% Si02 and most of the producers wash these sands to up grade their products to 99.5% or better. Included in the Lake and Bank sand would be the river sands that are used primarily for construction purposes. The Foundry Industry is broken down into three types of castings : 1. Grey Iron Foundries The grey iron castings largest market is the automotive industry in Ohio, Northern Kentucky, Indiana, Illinois and Michigan. These castings are poured at temperatures ranging from 2400° to 2700°F. The Silica Sands or the Lake and Bank Sands will satisfy the requirements of the grey iron castings. There are 2 ½ to three million tons per year shipped from the state of Michigan far grey iron castings by the Lake and Bank Sand Producers.

Jan 1, 1974

By Richard Addison

Rosario Dominicana, S. A. operates an 8,500 tonne per dayopen pit gold/silver mine in the Dominican Republic on the Caribbean island of Hispaniola. The mine is located in an agricultural area which is also an earthquake and heavy rainfall zone. In the 64 years from 1910 to 1974 there were 19 earthquakes within 300 km of the mine in the range of 6 to 8 on the Richter scale and the most recent earthquake in this range occurred in March, 1979. Average annual rainfall in the area is 1.7 m and is distributed throughout the year. Safe and environmentally sound tailings disposal in such conditIons has demanded the buiIding of an extremely strong dam wall and use of a fail-safe system of tailings disposal and solution reclaim. The type of dam, the system of tailings disposal and solution reclaim comprise an interesting example of the manner of handling tailings for a medium tonnage mine. The system is relatively costly but does assure a long-term, safe and trouble free structure and operating system. General views of the dam wall and tailings pond are shown in Figures l through 4.

Jan 1, 1980

By Michael Mccorkle

The Turnkey Project contracting approach is a very viable project delivery system for many mine and mill owners. Generally speaking, the Turnkey Project approach makes sense when the owner knows what it wants, is willing to accept the contractors judgement on process elements and maintenance standards, and early construction completion/facility stmt-up are of primmy importance. Projects with unclear process and project objectives make poor candidates for true Turnkey applications. If the objectives are unclear, under development or significant refinement, the owner's effort should go into a good schedule "A" package allowing Engineering, Procurement, and Construction (EPC) contractors to develop cost and schedule proposals for the final design ( engi­neering), procurement and construction of the facility. Figure 1 and 2 graphically depict (in general terms) the stan­dard Design-Bid-Build, Construction Management (CM) Fasttrack, EPC, and Turnkey Approach.

Jan 1, 1998