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By G. E. McClelland

Agglomeration techniques have been successfully applied to commerical heap leach cyanidation operations for the recovery of precious metals from low-grade ores, mine wastes, and tailings. The major parameters important for successful agglomeration pretreatment of these feed materials are discussed. Several commercial agglomeration-heap leaching operations are described. Two of the operations converted from conventional heap leaching to agglomeration-heap leaching after coventional heap leaching proved unsuccessful. Heap performance before and after agglomeration is discussed. A fairly recent operation that began production using agglomeration-heap leaching technology is also described. Two operations that processed milled tailings by agglomeration are discussed. The tailings feeds could not have been economically processed by means other than agglomeration-heap leaching.

Jan 1, 1986

By D. Men, R. Q. Honaker, J. C. Hower

"Maceral separation is one possible technique to expand coking coal resources, either by increasing the blending ratio of non- or slightly caking coal or rationally utilizing the coking coal according to the different behaviors of macerals in coking. The success of maceral enrichment for a given coal using flotation is dependent on the differences in flotation kinetic rate among macerals. This paper presents the flotation rates and zeta potentials of the vitrinite-rich and inertiniterich maceral concentrates obtained from six coal samples of different ranks – from high-volatile B bituminous coal with mean random vitrinite reflectance (Rrandom) of 0.64 percent to low-volatile bituminous coal with Rrandom of 1.73 percent – using a float-sink procedure. The flotation results show that vitrinite-rich concentrates can be produced in tap water using froth flotation only with frother for the high-volatile B and A bituminous coal samples, but there was no good performance for the high-volatile C bituminous and medium- to low-volatile bituminous coal samples. The zeta potential results show that froth flotation could probably separate the high-volatile C bituminous coal samples well by adjusting pH, but there was no good performance for the higher-rank coal samples. IntroductionMetallurgical coke is used in blast furnaces for steel production and is produced by the carbonization of coking coal. Because caking coals are rare and expensive, they are often blended with non- or slightly caking coals. Considering the tight supply-demand situation for coking coal in China, it is important and urgent to develop highly efficient technologies for rationally utilizing and expanding coking coal resources (Mochizuki et al., 2013)."

Jan 1, 2015

By K. J. Reid

With the current trends of increasing costs and decreasing head grades the mineral industry is no longer operating in very high profit areas and has been forced to pay greater attention to the application of modern technology. Although here are many technological advances to the credit of the industry in recent years there are still many processes being operated in the traditional manner and still many areas awaiting the application of methods which have been proven in other industries. Compared with the chemical industry the mineral industry is seriously ageing in the general areas of process analysis and process control, more so than can be justified by the complications arising from having to deal with particulate systems with properties far different from ideal, or even non-ideal, liquid systems. One area in which there has been a remarkable lack of application in the Mineral industry is that of analog computation and the authors feel that there is considerable scope for the use of the analog computer in studying mineral industry processes. The paper outlines the basic principles and features of the analog computer and describes its role as a simulation tool in some engineering and mineral processing systems.

Jan 1, 1972

By George S. Austin

Adobe, dried mud bricks, have been used since before historic time in the construction of dwellings. Building materials are normally evaluated for thermal performance based on measurements known as R- and U-values. The R-value is an indicator of the ability of a wall to insulate effectively and the higher the R-value, the better it is as an insulating material. The U-value, or value of conductance, is the reciprocal of the R-value and reflects the rate at which heat is conducted through a material. But the "heat capacity of the wall" must also be considered. This measures the length of time that passes before a steady state of heat flow is achieved. The effective U-value measures both the resistance to the transfer of heat and the capacity to hold heat. These latter value make adobe a far more interesting as a modern building material that was formerly recognized.

Jan 1, 1983

By N. Moony

The benefit of gravity separation in improving total gold recovery in grinding circuits has been outlined in a significant number of papers to date. However, the use of batch centrifugal concentrators (BCC) as an industry standard to extract gold has limited the potential for maximizing gravity recoveries -particularly in coarse gold deposits. This is a reflection of the high upgrade ratios obtained by BCC's which has an inverse relationship with recoveries. Survey work in Australia has indicated that installation of the InLine Pressure Jig as an alternative to the Bee will significantly increase recoveries of gold by gravity and, accordingly, increase total gold recoveries and lower operating costs.

Jan 1, 1998

By Elizabeth Anne Semon

The marketability of a large volume bulk material is significantly effected by transportation costs. Hence, it is essential for anyone that deals with minerals or mineral wastes to be able to reliably estimate bulk transport costs. The three types of bulk overland transportation modes that will be discussed are truck, railroad, and pipeline. Contract and private carriage are the two types of truck transport generally suitable for movement of bulk commodities. Contract carriers are those transportation firms that service a limited number of shippers and geographic points, and carry a restricted number of commodities. Private carriage consists of control over drivers and equipment by the shipper, ownership or lease of the transport equipment, and shipment of commodities related to the primary business of the shipper.1 A combination of private and contract carriage may also be used. Depending on the size and regularity of the shipment, rail offers single car, multiple car, or unit train service to move bulk minerals. Both long and short distance pipeline transportation has been shown economically and technically feasible for many different solids such as, mine and quarry products, coal, chemicals, copper concentrates, phosphate rock, and sewage sludge. 2

Jan 1, 1973

By John F. Abel

Convergence measurement across the 17.4 m (57ft) high shaft station/loading pocket at Mt. Taylor provided continuing verification of stability and safety. Three levels of instrumentation, consisting of three lines each, were installed and monitored. The instrumentation showed that the flexible lining restrained the adjacent rock. The flexible lining consisted of pea gravel with neat cement between rock and liner plate, wooden crush blocks between liner plate and steel ring beams. The loading pocket is elliptical, 11.6 by 9.6 m (38 by 31 1/2 ft) I.D. The crush blocks were designed to allow 15 cm (6 in.) of convergence. Maximum predicted convergence was 7.0 cm (2 3/4 in.) and 5.7 cm (2 1/4 in.) was measured. Convergence measurements also demonstrated decreasing deformation with respect to elapsed time and distance from the measurement station to the temporary bottom of the shaft excavation.

Jan 1, 1984

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the bubbles, water, and ore, selectively attaching these bubbles to the hydrophobic mineral's surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. The rapid flotation system was evaluated for beneficiation with a western porphyry copper ore containing 0.67 pct copper, and a phosphate-bearing amine flotation tailings sample containing 9.5 pct P2O5 in a quartz matrix. Over 88 pct of the copper was recovered from the ore in a rougher concentrate containing 5.9 pct copper at a rate 7 times faster than conventional flotation. Sixty percent of the quartz in the phosphate-bearing sample was floated at a rate 4 times faster than conventional flotation. The unfloated product retained 80 pct of the phosphate in a l6.9-pct P2O5 concentrate.

Jan 1, 1993

By L. Adler

A systematic, balanced and inclusive formulation of the vast input data for mine design is presented. Since the quality of this statement severely influences subsquent design it is extremely important to senior mining engineers and the profession-at-large. If unfocussed, chaos can result along with serious ommisions. The basic categories, each a traditional one are: 1) Natural Conditions (geology and geography), 2) Company Capabilities (monetary and managerial), 3) Public Domain (regulations, contracts, good will, etc.) and 4) State of Art (mining engineering professionalism). To further reduce the data additional organizing principles were used: the distinctions of mining (vs. civil) engineering, proceeding from the general to particular, the basic engineering dimensions, and separating dependent from independent variables. The results are a unique and unified corpus, which anticipates the mine design procedure.

Jan 1, 1987

Fossil resin types occurring in the Hiawatha seam of the Wasatch Plateau coal field, Utah, have been separated according to color and their physical and chemical properties evaluated. These resin types were separated into four color fractions, yellow, amber, light brown, and dark brown. Each resin type has then been subjected to comprehensive spectroscopic examination and other physical methods of characterization. Included among the spectroscopic methods of characterization are FTIR and 13C NMR spectroscopy. Physical properties that have been measured include density, optical, and magnetic properties. These analyses reveal that the resins are distinct from other macerals, predominantly nonaromatic in nature with small amounts of oxygen functionalities and a low degree of unsaturation. The four resin types show distinct differences in certain physical and chemical properties such as density, hexane solubility, magnetic susceptibility, and aromaticity.

Jan 1, 1990

By W. Edwin Dill

For the mining industry, the Internal Revenue Code and regulations offer a range of choices in arriving at the allowable depletion. Each case is essentially unique. Two prerequisites can optimize these opportunities: communications between the mining company's tax specialists and its technical staff; and an understanding of IRS definitions. For the latter, a logical starting point is consideration of exploration and development, since they precede production and depletion is unallowable prior to production. Criteria for selecting engineering and accounting options for exploration and development indicate the necessity of interaction between these company functions to achieve the most favorable tax position.

Jan 1, 1982

By Robert L. Bates

In this paper I use the term "industrial minerals" in its broad general sense, and I distinguish two main groups. The first consists of the bulk materials, characterized by low unit price, nearness of deposits to markets, relatively simple methods of extraction and processing, and a tendency to be closely related to the construction industries. The second group includes those materials valued for exceptional purity, or for some special property such as hardness, immunity to acids, or dielectric strength. These materials are produced in smaller amounts, at high unit values, from deposits notably restricted in. distribution; and they require more or less sophisticated methods of production and beneficiation. The applications of this second group are not closely tied to any particular part of the economy. From the way in which the commodity committees of the Industrial Minerals Division are set up, I take it that the chief interest of most members is with the first group of materials mentioned above. Hence this paper will deal mainly, though not exclusively, with such bulk commodities as sand and gravel, clay, and stone. The first word in the title of the paper also requires brief explanation. It is here given a threefold interpretation. First is the role of the industrial minerals themselves in industry; this would probably be taken as the conventional meaning of the title* The second is the role of the industrial-mineral producers as citizens of the community. The third is what may be called the scientific role of these producers.

Jan 1, 1964

By Linda D. Raedeke

The main platinum-group metal (PGM) deposit in the Stillwater Complex is associated with a stratiform zone formed by magma mixing. In general, the intrusion is a large, layered body of Archean age which formed by repeated magmatic injections in- to a single, large, hypabyssal magma chamber. The Complex is broadly divided into the lower Ultramafic series of olivine ± orthopyroxene rocks (1000-2000 m thick) and the upper Banded series of predominantly plagioclase-rich rocks (24500 m thick). The latter is further divided into Lower, Middle, and Up- per Banded zones. The Ultramafic series, plus most of the Lower and Upper Banded zones formed from repeated injections of an olivine-saturated magma, the rocks accumulating from the floor upward with a crystallization order of olivine, or- thopyroxene, plagioclase, clinopyroxene. The olivine-bearing subzones of the Middle Banded zone formed predominantly from a magma which crystallized in the sequence plagioclase, olivine, clinopyroxene. Olivine-bearing subzone I, with which the PGM mineralization is associated, occurs generally -400 m above the Ultramafic series-Banded series contact. Ore grade mineralization is usually found in plagioclase or plagioclase-olivine cumulates. The platinum-group elements are associated with disseminated base-metal sulfides dominated by the assemblage, pyrrhotite-chalcopyrite-pentlandite. Olivine-bearing subzone I marks an interruption in the crystallization sequence of the Lower Banded zone, with the reappearance of cumulus olivine and an associated change of the crystallization sequence. These changes indicate the addition and mixing of a secondary magma of the same composition as that which later dominated in the formation of the Middle Banded zone. Characteristics associated with mixing include laterally discontinuous but well-developed layers, xenoliths of ultramafic rocks, and sedimentary-type structures such as slum- ping and graded layering. The influx of new magma caused sulfide saturation by one or more of several chemical changes including addition of sulfur, decrease in oxygen fugacity, decrease in FeO, or increase in SiO2. Once an immiscible sulfide liquid was formed, platinum-group elements were scavenged from the magma by the sulfide liquid and segregated.

Jan 1, 2013

By S. K. Kawatra, H. J. Haselhuhn

"Thickening is used during two primary mineral processing operations: water removal and desliming. During water removal, the pulp density is increased through the injection of flocculants. These flocs settle and create a dense pulp while clarified water is removed through the overflow. During desliming, fine particles are removed through the overflow. Desliming can also be used as a mineral separation process known as selective flocculation-dispersion, where valuable minerals are flocculated and gangue minerals remain dispersed and exit through the overflow.There are many ways to analyze thickener performance on a laboratory scale, but these analyses often do not correlate well with full-scale performance. Some pilot-scale systems have been designed using a semicontinuous approach, but the amount of material required to perform their tests can make semicontinuous pilot thickeners impractical for most applications. This paper focuses on the design and optimization of a continuous pilot-scale deslime thickener that requires minimal material to operate. The design, optimization strategy, and an example study of reagent selection are demonstrated. IntroductionMany laboratory methods have been employed to size and optimize thickener performance. The most common of these include the Coe and Clevenger method and methods derived from the Kynch theory of sedimentation. The Coe and Clevenger method was developed in 1916 and was proven for slurries that do not require flocculation to settle. This method proposed that the settling rate of the pulp is only a function of the solids concentration. It is executed by creating slurries of several different concentrations of solids and performing bench-scale settling tests in graduated cylinders. For each concentration, a thickener unit area can be determined using the following equation (Coe and Clevenger, 1916; Laros, Slottee and Baczek, 2002):"

Jan 1, 2017

By C. L. Jiang

The selective depression of pyrite obtained from Kentucky No.9 seam in coal flotation with various kinds of inorganic and organic chemicals was systematically examined. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates has been explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta potential measurements. It was shown that pyrophosphate reacts strongly with iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1998

The properties of interfacial water at hydrophilic surfaces are of great importance in many technological areas including flotation, solid-liquid separation, dispersion and emulsions, flocculation, adsorption, corrosion, and soil contamination. This paper examines the use of FTIR/internal reflection spectroscopy (FTIR/IRS) to study the spectral characteristics of interfacial water at silica surfaces. FTIR spectra were characterized by consideration of the OH stretching region (3000-3800 cm-1) associated with the vibrational spectra of interfacial water. The broad peak in this region was deconvoluted in order to isolate overlapping spectral features that describe the nature of hydrogen bonding in interfacial water. Three distinct bands were found; -3600 cm-1 (free OH), -3400 cm-1 (incomplete tetrahedral coordination), and -3240 cm-1 (complete tetrahedral coordination) and the variation of their intensities with pH was found to be significant. This spectral information helps to explain orientation and bond ordering of interfacial water molecules at hydrophilic surfaces.

Jan 1, 1998

By Atmesh K. Sinha

Death and injury rates in mining have been the highest of any industry; the injury severity rates in mines have also been the highest. Tentative figures reveal that 1971 was the best year yet for the bituminous coal indus¬try with the lowest number of fatal accidents. Nevertheless, 177 men were killed at a frequency rate of 0.76 per million man hours. Coal mine accident statistics have been described at various times as unacceptable and intolerable and recently resulted in the enactment of massive legislation. The 1969 Coal Mine Health and Safety Act was passed by Congress "to improve the working conditions and practices in coal mines and to prevent accidents and occupational diseases originating in the coal mining industry." The prevention of accidents in coal mines is the statutory responsibility of mining engineers and the moral responsibility of all who have any part to play in mining coal. The questions to be answered by these men may well be - What are the reasons for the high accident rate? Are the mines as safe as they can be? Are our mines sufficiently manned to insure proper supervision of production cycles and safety requirements? Are our plans for safety committees, safety campaigns, and safety inspections sufficient? Are they producing the results intended? If not, how can these be reorganized to have a greater impact? What is the real cost of an accident? What are the immediate and long-term plans for further improvements? These questions are in no way exhaustive, and the answers are not easy. There are many aspects of mine safety, and any one of them can be the subject of a lengthy discussion. The aim of this paper, therefore, is to limit the analysis to documented fatal electrical accidents in mines so that meaningful conclusions for improvement in electrical accident-experience statistics can be made. In doing this, it is also the intention to emphasize areas of missing information and propose a few suggestions for better hazard analysis.

Jan 1, 1972

By R. Mensah-Biney

The kinetics of loading of gold from bromide solution onto an anion exchange resin, PAZ-4, were investigated in a batch stirred reactor. The initial loading rate was described mathematically by a first-order reaction rate equation. The effect of agitation speed, temperature, resin particle size, resin concentration, initial concentration of gold and bromine in solution on the rate was investigated. The model described fairly accurately the loading process in terms of the variables investigated. The rate constant for the initial loading ranged from 0.5 to 1.3 x10-3 sec-1 and the half-time was 9.3 to 56 minutes. The initial rate constant increased with increasing temperature with an activation energy of 15.7 kJ/mole (3.8 kcal/mole). The rate constant was directly proportional to the concentration of the resin in solution. The subsequent reduction reaction was also modeled by the first-order rate equation and the apparent rate constant was estimated to be 3.0 x 10-6 sec-1 with a half-time of about 44 hours.

Jan 1, 1994

By L. B. Rothfeld

This paper presents preliminary results of a Bureau of Mines study of potential costs of compliance with the federal Resource Conservation and Recovery Act for copper heap and dump leaching. Specifically, estimates are given for the cost of compliance with possible technology standards that would require the use of liners and closure caps regardless of terrain and underlying geology and hydrology. This cost is compared to the co lit of compliance with present state requirements for terrain a typical of those found at existing copper leach sites in the Southwestern U.S.A. Incremental compliance costs are found to widely exceed screening criteria used by the Environmental Protection Agency to denote significant economic impact.

Jan 1, 1993

By R. C. Burtan

Long before the dawn of recorded history, man began to dig into the earth's crust in a never ending search for useful materials. It has been well established that prehistoric man discovered flint. "The Flintstones" were aptly named. The flintknappers of southern England and Wales still exist today in ever dwindling numbers as they seek out chunks of flint. It is a well known fact that more than half of the earth's crust is composed of silicon dioxide (SiO2), also known as silica. Silica and silica containing materials have a great many uses in modern society. However, this material is potentially extremely hazardous to our health. Centuries before the Christian Era, Hippocrates wrote of a lung disease common to those who mined in hard rock. It is obvious to us that he was describing silicosis. It is also apparent from ancient writings, that the Egyptians were aware of this malady. Dioscorides also wrote on this subject in the fifth century, B.C. It is undoubtedly the oldest and best studied of the occupational lung diseases. It was certainly described by Agricola in his "De Re Metallica" published in 1556, in which he described lung disease among hard rock miners. This publication, I'm sure, is of special interest and perhaps known to many of you in the mining community. The original document was written in Latin and was translated in 1912 by two gentlemen, Hoover and Hoover. One of these translators was Herbert L. Hoover, a former president of the United States, who made his living before his presidency as a mining engineer.

Jan 1, 1984