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By W. Zhang

"The adsorption of collector on bornite has been studied in situ in aqueous solutions by applying an atomic force microscopy (AFM). The AFM images show that xanthate, such as potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX), adsorbs strongly on bornite mainly in the form of insoluble metal xanthate, which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This adsorption mechanism is very similar to the one obtained with chalcocite/xanthate system. However, the result also clearly shows that the adsorption of xanthate on bornite is totally different from its adsorption on chalcopyrite, during which oily dixanthogen is the main adsorption product on chalcopyrite surface. The obtained AFM images also showed that the adsorption increases with increasing the collector’s concentration. When Cytec Aerofloat 238, a dialkyl dithiophosphate collector, is used, it adsorb on bornite mainly in the form of an oily substance, which can be rinsed off mineral surface by flushing with ethanol alcohol. AFM images also show that the adsorption of Cytec Aerofloat 238 increases with increasing the adsorption time. INTRODUCTION The adsorption of collector on mineral surface is vital for a successful flotation process to achieve a satisfying recovery. Historically, many works have been carried out to clarify the adsorption mechanism of collectors on sulfides. (Gaudin and Schuhmann, 1936, Poling and Leja, 1963; Allison et al., 1972, Fuerstenau, 1982; Leja, 1982; Woods, 1984) Compared to other copper minerals such as chalcopyrite and chalcocite, much less work has been done to study the adsorption collector on bornite. Allison et al. (1972) studied the reaction products of various sulfide minerals with xanthate solutions and reported that the measured rest potential of bornite in 6.25×10-4 M KEX solution at pH 7 was +60 mV and the reaction product of PAX on bornite was cuprous alkyl xanthate. Mielczarski and Suoninen (1984a, 1984b) applied the XPS and studied the adsorption of potassium ethyl xanthate on cuprous sulfide. It was reported that there was a relatively rapid formation of a well-oriented monolayer of xanthate ions followed by a slow growth of disordered cuprous xanthate molecules on top of this layer. Buckley et al. (1984) investigated the surface oxidation of bornite by linear potential sweep voltammetry and X-ray Photoelectron Spectroscopy and proposed the adsorption products on bornite depended on the solution potential. Zachwieja et al. (1987) studied the electrochemical flotation of the bornite-ethylxanthate system and reported that KEX reacted with bornite through an electrochemical oxidation reaction forming cuprous xanthate between -0.4 and -0.2v (SCE). Hangone et al. (2005) studied the flotation of a bornite-rich copper sulfide ore using thio collectors and their mixtures and reported that the highest copper recoveries were obtained with the diethyl dithiophosphate (di C2-DTP)."

Jan 1, 2016

By J. van Oldenborgh

The world market for bunkers represents some 140 MT (1980) of marine fuel oil and distillates. This is equivalent to 23CMT of coal, a potential market for steam coal larger than the total seaborne trade of steam and metallurgical coal today, and an obvious area which could contribute savings in world oil consumption. Oil bunkers are lifted fairly evenly throughout the world, the main supplying regions being Western Europe, the Middle East, North and Central America and Japan (Figure 1). Not surprisingly, the main customers are the tankers representing about 50 percent of the world market - (95 percent of the Middle East Market) - dry bulkers represent some 30 percent and general cargo ships the rest.

Jan 1, 1982

By P. B. Queneau, J. E. Litz, T. P. McNulty

I. INTRODUCTION Modern hydrometallurgy has its roots in such notable successes as heap leaching for recovery of copper, cyanidation of gold ores, the Bayer process, the Oxland process for tungsten, electrorefining of copper, roast/ leach/electrowin process for zinc, and production of yellowcake from lowgrade uranium ores. Metallurgical testing techniques, sampling and analytical procedures, operating and maintenance practices, and improved methods and materials of construction which were pioneered in these processes have promoted the extension of hydrometallurgy into other applications. Periodically, new tools such as solvent extraction, resin ion exchange, and flocculants have opened new avenues to hydrometallurgists. Conversely, pursuit of more complex mineralization, the rising costs of energy and environmental quality preservation, and declining ore grades continue to create new challenges. For much of this century, it can be fairly said that practically any hydrometallurgical development moved the frontier of technology. The 1970's and 1980fs, however, have seen a significant maturing of hydrometallurgy's role in process metallurgy. Simplistically, this maturing seems to derive from a growing awareness of the strengths and weaknesses of hydrometallurgy and a determined effort to capitalize on the strengths. For example, many of us were among those revolutionaries of the 1960's and 1970's who taught that "chemical smelting" was the answer to the treatment of all sulfides. We now recognize, however, that only in very special cases can hydrometallurgy offer economic advantage over the generally less energy-intensive pyrometallurgical systems. The maturing of hydrometallurgy does not, however, signal stagnation. Important innovations are being studied and developed in most extractive areas, and a number are approaching or have achieved commercialization. From our company's perspective, that of an organization dealing with the development of the most economic solutions to metallurgical problems, innovation must be defined as the commercially successful reduction of an idea to practice. There appears to be no shortage of ideas, nor has there ever been a shortage. Many ideas now being implemented were conceived decades ago, but reduction to practice was foiled by the lack of such technology as responsive process control and economical materials of construction capable of withstanding highly corrosive or erosive environments. Commercialization of a new process is a particularly challenging undertaking. Even if technical risks are reduced to a minimum through careful and thoughtful process development, there are inevitable uncertainties in feed characteristics, variable costs, and product prices. Commercialization takes courage, both on the part of innovators who may be staking their careers or reputations and of investors who may face financial disaster in the event of project failure. This paper discusses innovative programs and recently commercialized processes which either have been discussed in the literature or disclosed to Hazen Research staff in private nonconfidential conversations with contacts in industry. Regarding this latter category of information, relative ease of communication has resulted in many of our observations being of North American origin.

Jan 1, 1985

By Robert L. Frantz

The various facets of university-company cooperative activities and the opportunities for collaborative research for the mineral industries are presented in this paper. The advantages and disadvantages of various alternative research funding arrangements for the researcher, the university, and the sponsoring corporation are discussed. Examples of university-industry cooperative research programs are briefly outlined. The concept of a cooperative mining research program is presented. The improvement of performance through techno- logical developments and human skills may well be the greatest competitive edge available to the U.S. mining industry. In this regard, the need for new endeavors between industry and universities can hardly be overemphasized.

Jan 1, 1984

By St. Mergentime, K. Zeidler, V. Gall

2001, the New Jersey Transit Authority commissioned the JV Merco-Obayashi with the rehabilitation contract of the approximately 130-year-old, 4,200 ft long, partially brick- lined Bergen North Tunnel. The contract entailed the tunnel enlargement, shotcrete and rock dowels initial support according to the NATM, a waterproofing system, tunnel drainage and a cast-in-place concrete lining. The rock conditions encountered required design adaptations and significant modifications of the initial tunnel support. Flexibility, skill and extensive experience on the Authority’s and Contractor’s side finally lead to a success. This paper describes the operations and design modifications carried out.

Jan 1, 2003

By Y. C. Kim

M.S. Azun The article unfortunately has some serious flaws negating the usefulness of the paper. The authors claim that kriging (linear kriging) is superior to other methods such as polygon. This is not the case. The deterministic methods (referring to polygon, ID, IDS, etc.) should not be compared with the statistical methods (linear kriging, disjunctive kriging, etc.) because they differ not only in their assumptions, but also their tools used in estimation. Thus, they give different results. By comparing the results of deterministic methods and linear kriging, the authors conclude that polygon, IDS, and linear kriging give an average thickness close to the value obtained from realizations. Besides, they argue that linear kriging gives less variance than the others (Fig. 2). The first conclusion is expected, due to the well-known central limit theorem. The second is the result of the statistical properties of different estimators. Thus, the comparison presented in the paper is rather meaningless because the authors have failed to follow basic statistical procedures. The numerical results of different approaches to an estimation problem cannot be generalized. In conclusion, the paper is not a meaningful contribution, and sadly, quite erroneous. Reply by E.Y. Baafi and Y.C. Kim The two key contentions made by M.S. Azun regarding the paper are: deterministic methods should not be compared with statistical methods and, hence, the results are erroneous; and the paper does not make a meaningful contribution. The first contention is an academic one. Most practitioners in ore reserve estimation could care less whether the tool they are using falls under a deterministic or a probabilistic method, so long as it gives the desired answers. It is probably for this reason that, whenever any new tool such as linear kriging is introduced to practioners in the mining industry, they would like to see a comparison test performed between the existing and the more familiar tools with a new and "strange" tool. Only when a new tool passes such a test, the generally conservative mining community would begin to utilize the new tool to its advantage. The second contention, is a subjective one. The final judgment should be left up to the readers within the mining community. If kriging is accepted more among practitioners, partly due to the paper, then the paper makes a practical contribution to the state-of-the art in ore reserve estimation. Finally, M.S. Azun entirely missed two main points in the paper. The first is that any comparative study of kriging vs. Polygonal or IDS should be performed for local estimation and not for global estimation. In the past, kriging was frequently compared with other existing tools in its performance on global estimation. Such results were nearly identical due to the central limit theorem effect, which further prevented the acceptance of kriging by practitioners. The second point is that a single case study using an existing property, as it was frequently performed in the past, is not sufficient because results depend not only on the tool itself, but also on the nature of the mineralization.

Jan 3, 1984

By William M. Warren

Recent sinkhole activity in carbonate terranes of Alabama has resulted in damage to transportation lines, structures, utility lines, and property in general. Active sinkhole development and subsidence has been well documented in Alabama, Florida, Pennsylvania, and South Africa. An excellent example of the potential danger resulting from this activity is the spectacular collapse under a South African gold ore crusher plant that resulted in the death of 29 men in 1962. Due to the severity of the problem in certain localized areas in Alabama, a detailed investigation is being undertaken by the Geological Survey of Alabama and the U. S. Geological Survey. One of the most promising techniques is the application of aerial photography and thermal infrared imagery. Conventional and modern remote-sensing techniques are being used in Alabama to locate and define areas of sinkhole activity and to determine which areas are most prone to its occurrence.

Jan 1, 1975

By M. K. Rizkalla

This paper discusses the time-dependent behaviour of rock when it involves the presence of several layers of rock strata in the vicinity of mine openings, mining in sequences and the placement of backfill. The paper describes numerical techniques which proved useful when such situations are encountered in practice. The model is elastoviscoplastic. At given time stations, short term loading or changes can be made to the creep behavior of the rock. The modelling technique is first described and is followed by simulations of stresses and displacements in a potash mine with the primary objective to demonstrate the effect of such aspects as mining and fill sequences in 3-D. This involves cutting finite elements representing the strip of the mining face and simultaneously filling those elements representing the newly placed fill. The stiffness of the fill varies with the degree of compaction at each point. In this way, the effect of the time of fill placement, the gap between the top of the fill and the back as well as the degree of compaction are simulated. The second example is a 2-D problem simulating the long term effect of backfill, as a material compacting with time, on the settlement of the layers above it as well as the closure of the room.

Jan 1, 1996

By Antonio Tafra, Rene Dominguez, James Spenceley, Brady Hays

"Extracting one of the world’s most valuable natural resources — copper — hinges on the availability of the world’s most essential resource: fresh water. But try sourcing fresh water in one of the driest places on Earth, Chile’s Atacama Desert.BHP, majority owner of the Escondida copper mine in Chile’s Antofagasta region and Minera Escondida Limitada (MEL), operator of the mine, were looking for sustainable solutions to deliver desalinated water to the mine, while protecting the environment and complying with the local water authorityregulations.The mining giant chose Black & Veatch to solve this challenge.Solving a global miningchallengeMines use large quantities of water for mineral processing and metal recovery. Water supply, and not mineral ore, is often the major constraint to mining production and development of projects, especially in Chile. Mining operations must have a reliable water source that complies with local regulations, without adversely impacting the environment or affecting the water supply of nearby communities.Worldwide, mining companies and their owners, shareholders and regulators are placing new levels of focus on minimizing the impact of mines on the surrounding landscape and communities. Balancing the economic benefits and needs of mining operations with the potential freshwater impacts requires mines to pay serious heed to the environmental and social issues related to water. Today, mining companies are being proactive and are taking action to protect precious freshwater resources while seeking opportunities to reduce and mitigate their water impact.Delivering a desalination solutionBHP and MEL needed an efficient, technologically advanced seawater desalination plant, along with a conveyance system and infrastructure that would carry desalinated water more than 180 km (112 miles) from the ocean to the mine. Four pumping stations convey the water to a reservoir at the mine site, which is 3,200 m (10,500 ft) above sea level."

Jan 6, 2018

By C. F. Curry

In the early 1940's Humphreys Mining Company in Florida pioneered heavy mineral mining with a dredge in the United States, In 1948 Du Pont, in conjunction with Humphreys, opened their first of two mining operations recovering a titanium dioxide product in Florida. Later on in 1952 Du Pont opened their second plant, both of which used a cutterhead suction type of operation. This process is also used in heavy mineral mining in Australia and Africa. In 1957 ASARCO started prospecting in New Jersey. Test borings indicated a large deposit of ilmenite bearing heavy mineral sands had been deposited and concentrated in an area near Lakehurst in central New Jersey. Humphreys Mining Company was contacted about the possibility of mining the ASARCO New Jersey property in much the same way as Du Pont and themselves were doing in Florida. An extensive study was made to determine the economic feasibility of mining the ASARCO property. During this study, extensive test drilling and samples for a pilot plant were taken.

Jan 1, 1975

By J. T. Crawford

A comprehensive strategic planning model has been developed for the phosphate strip mining and chemical operations at White Springs, Florida. The computerized model covers ore body modeling, production simulation and financial analysis. Several innovative features in the model include using NPV techniques in ore body block economics, adapting the floating cone method to a floating template for generating dragline mining units automatically, using interactive graphics for designing mining units, and a dragline move economics algorithm for automatic scheduling of mining unit assignments and moves. Simulation of chemical plant production uses linear programming and concentrate inventory levels control mine operating schedules.

Jan 1, 1997

By R. W. Utley, J. Carr

The tremendous growth in grinding mill size and horsepower during the 70s demanded advancements in gear cutting technology and equipment for the 80s. A new standard in gear cutting machines is now used to generate-cut large open gear sets to over 12.2 m (40 ft) in diameter at an AGMA quality level much higher than the accepted levels a short five years ago. The precision of the resulting gear set assures maximum tooth contact with the resultant longer gear set life.

Jan 1, 1987

By R. R. Beebe

Marcona Corporation produces about 3.5 million long tons of iron ore pellets annually on its two travelling grate pelletizing machines at San Nicolas, Peru. During 1969, these pellets will be shipped to customers in four marketing areas--Japan, the United States, Europe, and South America. All of these sales are on the open market, and product quality is a major concern. Typical chemical, structural, and quality test results for Marcona pellets are given in Table 1. [ ]

Jan 1, 1969

By James Wm. White

Calculation of consistent steady-state mass balances in operating metallurgical plants and pilot plants is of interest for many reasons. In general, enough data can - and should - be collected to overdefine the system, i.e., permit calculation of nonmeasured quantities via more than one path. In such cases, resulting steady-state metallurgical mass balances rarely close due to sampling, analysis and/ or instrument error. Indeed, determination of a valid calculational sequence for complicated process flowsheets with multiple recycle streams can prove quite difficult. Here we present and discuss a method that has proven useful in analysis of numerous grinding circuit flowsheets of varying-degrees of complexity our technique requires only a consistent process flowsheet with appropriate associated data and arbitrary numbering of streams and equipments. Process topology and user data are decoded to yield a set of "search" or base variables and a set of "calculated" variables in solids, water, particle size and splitter parameter space. This procedure greatly speeds subsequent actual mass balance adjustment calculations since perturing certain variables (e.g., a solids value) does not require recalculation of other variables (e.g., the water balance). Finally, internal search and calculated variables are back converted to User units and used in a Sum-of-Squares criterion. Global minimization of this performance functional then yields a consistent mass balance in a least, squares sense. Weighting factors of choice can be used. Examples illustrate application of these methods.

Jan 1, 1979

By M. A. Ouederni, G. C. Chorosz, E. P. Déliac

This paper deals with the heat flow problems in deep workings (depth greater than 1000 m in France). The approach benefitted from experience gathered in France and South Africa. Deep mines are located in the East of France (coal in Lorraine and potash in Alsace), where the geothermal gradient can reach 4 'C per 100 m (Virgin Rock Temperatures, VRT, around 50 'C). This paper is concerned with the following topics: method of studying the heat flow problem on a mine-wide basis, specific models for heat and moisture pick-up, interfacing of heat and ventilation calculations and a case history in the Lorraine collieries. The heat flow problem on a mine-wide basis is studied in a fashion similar to ventilation networks. Each branch is considered as a "black box" where the air picks up heat and moisture (or is cooled, in the case of an air-cooler). Each box is therefore modeled as a heat transfer unit, hence the calculation of outlet temperatures (wet- and dry-bulb) from the intake ones. The whole network can thus be computed as a sequence of boxes from the air intakes towards the outlets. The second section reviews a number of models used for the assessment of heat and moisture pick-up in the "boxes", with emphasis on stopes and development ends, which are particular to the mining method in use. Two types of stopes are considered: longwall (horizontal and inclined) and cut-and-fill (subvertical). Mechanized rock breaking and blasting can be accounted for. A particular attention is given to development ends, especially complex from the heat flow point of view (rock characteristics, wetness factors, etc.) and usually quite hot. These workings, which are critical in order to secure new production areas, are studied on an average basis as well as in extreme conditions. The calculation takes into account the history of rock temperatures. The interaction between ventilation and thermodynamic calculations is still under development. The idea consists of coupling ventilation calculations with the "box" models: the first step determines the direction of air flow, hence the sequence of the boxes; thereafter the calculations yield the effect of temperature and presssures on air flows. The final section reports on the validation of the whole approach against field data. It concerns several heat flow surveys aimed at checking the models for shafts, stopes and development ends. The accuracy of the method is found very satisfactory.

Jan 1, 1987

By M. Gunter, M. Buzon

"Talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic, and lacking in amphiboles. In southwest Montana, talc formed from hydrothermally altered dolomitic marbles, and is still actively mined. These talc deposits are typically in contact with quartzofeldspathic gneiss and marble. Accessory minerals vary between these rocks and the ore producing body; the identification and characterization of such minerals requires carefully selected analytical methods. Recent litigation and ensuing confusion over the petrology and asbestos content of these deposits challenges the talc mining industry in Montana, and elsewhere in the world. INTRODUCTION Commercial talc has been mined from the deposits in southwest Montana since the 1940s, and by 1956 the region had output 200,000 tons of talc ore (Chidester et al., 1964). Commercial talc refers to rocks containing more than 20% of the mineral talc (McCarthy et al., 2006); the ores from Montana typically contain upwards of 90% talc. This region remains the leading domestic source of talc in the U.S. partly due to the reserves in the area, and partly due to the diagnostic purity of the ore compared to that of other regions, some of which are no longer actively mined. The mineral talc, a sheet silicate, is expressed by the formula Mg3Si4O10(OH)2, and therefore can form in geologic environments that are rich in Mg, Si, O and water. The protolith for the talc deposits in southwest Montana is a dolomitic marble, but other common protoliths include ultramafic igneous, mafic igneous, and siliceous dolomites (McCarthy et al., 2006). Physical properties such as hardness of 1 on Mohs hardness scale, white streak and slippery feel are among some of the reasons why talc is so widely used as fillers in a number of industries. In decreasing order, ceramics, paper, paint, roofing, plastics, rubber, and cosmetics are the leading domestic industries that use talc despite the decreasing trend in U.S. talc use and production since 1994 (Virta, 2015). The purpose of this paper is to describe the mechanism of talc formation in southwest Montana by focusing on talc deposits and surrounding rocks in the Ruby, Greenhorn, and the Gravelly Ranges, and to relate the mechanism of formation to the composition of talc ores. The compositional data show mineral content of selected ores, and the major and trace element content of those minerals, specifically talc. Our electron microprobe (EPMA), powder x-ray diffraction (XRD) and x-ray fluorescence data for samples from five mines in these three ranges provide continued evidence of the purity of these ores despite claims made during recent litigation that these ores contain asbestos. The five mines that we discuss include the Beaverhead, Treasure, Regal, Willow Creek, and Yellowstone Mines (Figure 1.)"

Jan 1, 2016

By L. R. Berry

The successful selection of a slurry pump depends on the accuracy and completeness of the information provided for the application. Inaccurate or incomplete information can result in incorrect pump selection and / or operational problems. Some information is more critical to the selection process than other information. A full description of the slurry (liquid -solid mixture) including the particle size distribution and maximum concentration, the flow, head and NPSH requirements are most important for successful slurry pump selection and operation. Common problems resulting from improper slurry pump selection will be discussed to illustrate the need for correct selection requirements.

Jan 1, 1996

By M. C. Baumann

The Getchell Mine is located in Humboldt County, Nevada, approximately 70 km northeast of Winnemucca. Slope management has been a critical factor in the feasibility of mining operations since they began in the early 1930's. Although underground entries began in 1937, underground production was limited because hanging walls consisting of clay gouge and crushed rock tended to collapse into the workings. Controlling these collapses required extensive timbering. Due to these poor ground conditions, surface open-pit mining was the primary mode of production from 1938 to 1967 with only minor contributions from underground operations. Mining was suspended in 1967 due to economic pressures. From 1960 to 1967, the previous operator mined the property in three open pits. Initially, these pits were constructed with footwall benches, but these failed. These failures were aggravated by construction of 60° slopes in footwalls with shale partings dipping into the pit at 43° to 60°, resulting in large planar failures and wedge failures. In response, the previous operator adopted a slope parallel to the bedding planes.

Jan 1, 1993

By L. G. Kirk

The Mississippi embayment ball clay region, including western Kentucky, western Tennessee, and northwestern Mississippi, accounted for more than 95% of the total U.S. ball clay production during 1985. Other producing states during the year were Texas and Maryland. The U.S. Bureau of Mines reported total domestic production for 1985 of 910,000 short tons. The United States exports approximately 20% of the annual ball clay production. Geologically, the ball clay deposits are sedimentary in origin and occupy the north- eastern flank of the Mississippi embayment. The commercial deposits have been confined to the Claiborne and Wilcox formations within mid to lower Eocene and upper Paleocene age strata. The deposits are lenticular in nature and highly variable in areal extent and thickness. They exhibit very abrupt lateral boundaries and are bounded laterally and vertically by unconsolidated sands, silts, and waste clays.

Jan 1, 1986

By M. Katzer

The effect of selective dispersants as wet grinding aids for ores is demonstrated on laboratory scale batch and continuous grinding equipment. A complete characterization of behavior is performed on a given ore to demonstrate correlations involving torque, % solids, net production rate, and slurry weight and volume loading. The relationship between such laboratory data and industrial scale testing results is very consistent.

Jan 1, 1979