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By M. S. Moats

Galvanic stripping, in conjunction with solvent extraction, has been proposed as a technical option to the challenging problem of iron removal in certain hydrometallurgical processes. The galvanic stripping process is based on the ability of a solid metal to directly reduce ferric ion to the ferrous state in an organic media. Stripping the iron into the aqueous phase is then easily accomplished. Previous work has shown the reaction kinetics and efficiency are affected by such operating parameters as water and oxygen contents, temperature, time and metal reductant. In this study, the optimum operating range for some of these variables was determined. Both zinc and iron metal were used in the separate stripping of iron from D2EHP A. Reasons for the differences in the extent of the reaction obtained using the various conditions are discussed.

Jan 1, 1996

By P. Leo

The Al-Zn-Mg alloys (e.g. 7004, 7020) are employed for land transport and architectural applications whereas the Al-Zn-Mg-Cu alloys (e.g. 7075, 7050) provide the high strength aircraft alloys. The Cu gives rise to suitably sized and distributed precipitation but causes high quench sensitivity. Their hot work processing also has marked differences; the Cu-free alloys have good extrudability whereas the Cu-bearing alloys have low extrudability and are difficult in rolling as well. The behaviors of the two classes are described in terms of flow stresses and ductility over 300 - 500°C, along with constitutive contrasts. The ductility of the alloys with Cu is much reduced above 400°C by precipitation of a phase at the grain boundaries that can be avoided by suitable heating schedules. The high strength alloys are subject to de-lamination corrosion of sheared edges due to severely pancaked grains; this can be alleviated by holding between passes, in mid-rolling schedule. In torsion tests at 10-1 to 10 s-1/ 250 - 500°C, the stresses (ductilities) at 300°C/ 1s-1 and activation energy Q for 7004 were 118 MPa (2) and 262 kJ/mol. The 7075 was tested after several pretreatments: completely over-aged (softened): 107 MPa (5), Q=150 kJ/mol; whereas, solution and quick cooling to testing caused extraordinarily high peaks related to dynamic precipitation resulting in 160 MPa (1.2), Q=300 kJ/mol.

Jan 1, 2011

By K. Thuro, S. Schneider, H. Kasling, P. Ellecosta

"One of the most important methods for material testing is the characterization of the hardness, which is defined as the resistance of a material to the penetration of another one. The methods according to Brinell, Vickers, Rockwell and Knoop are today the most common and standardized tests for metal. As they are developed for predominantly ductile materials like steel, they can’t easily be applied to rocks which react much more brittle under indentation. But just as steel, rock is composed of different minerals and has a specific microstructure. Its mechanical parameters are connected with the particular grains, their cohesion and interlocking, just like steel.The abrasivity of rocks and the accompanied wear of drilling tools today are mainly determined by simple and fast laboratory tests such as the Cerchar abrasivity test or the rubber wheel test. Such laboratory tests are good tribological tests, but there are limits. The Cerchar abrasivity test for example has weaknesses in extreme cases, that mean soft or very hard rock types. This leads to an underestimation of abrasivity, e.g. in poorly lithified sandstones or very hard, fine grained and extremely abrasive rocks. As mentioned, hardness characterizes, depending on the type of deformation, predominantly plastic (metal) or elastic properties (rubber). Rocks are in the range between these two extremes. Since the rock drilling process can be seen as a kind of penetration process on macroscopic and microscopic scales, we picked up the idea to characterize the interaction of rock materials and TBM-disc-cutters with hardness tests. In addition, this supports for a better understanding of the wear process on disc cutters. We used the hardnessdisparity concept after Cardu & Giraudi (2012) because wear can be understood as the interaction between the wear part and the material which causes the wear (tribological system). Several rock-forming minerals and some fine to coarse-grained monomineralic and polymineralic rocks were tested. In contrast to Cardu & Giraudi, we used in the first step of investigations the method after Vickers with loads up to 294.2 N (HV 30), depending on the estimated hardness to get bigger indentations and therefore as well information about the cohesion and interlocking of the minerals/grains. We also tested several associated disc cutters. First results show that with higher loads (HV 5 - 30) and at least 15 indentations, we get a structural hardness in fine-grained rock samples, which allows a good characterization of the elasticity and brittleness. Nevertheless, for the coarse-grained rock samples we need up to 40 indentations for a good characterization. Using this method, a prediction of disc cutter wear is feasible taking into account the hardness of the disc cutter steel. In this paper, we would like to present this approved method in material sciences to derive an additional parameter for the characterization of rock abrasivity and wear."

Jan 1, 2015

By Chas. F. Jackson

This paper is one of a series dealing with mining methods and costs, prepared and published under the sponsorship of the United States Bureau of Mines and made possible through the cooperation f many mining companies in the United States and foreign countries. The preparation of this paper follows a field study of top-slice mining during which the author visited and discussed with operating officials a large number of iron mines in the Lake Superior region. During this study special note was made of changes in top-slicing practice during the past decade, prior to which the author had acquired several years experience with the method through active connection with a number of mines employing top slicing.

Jan 1, 1931

By Thomas H. Sheldon

In the zeal for opening up new ore-bodies, or for extracting the ore from attractive bodies already opened up, we very often lose sight of the fact, that, after all, the operation of a mine is a business proposition, pure and simple, and, for the best working-results, should be treated upon a strict business basis. Of course, in every mine of consequence, a record is kept of expenditures and receipts, and such glittering generalities as " gross receipts," " net receipts," " mining expenses," and a per cent. profit," can be told to the cent; but does this record show economy of management, as compared either with the same record of other months, or with the record of other mines of the same class ? Moreover, if such a record shows that the cost of mining is high, does it in any way enable the manager to put his finger on the leakage ? Does it necessarily follow that a mine which makes a profit of, say, 40 per cent. on 25-dollar ore, is doing less economical mining than one which saves 60 per cent. on 80-dollar ore ? Of course the figures in the latter case look the more attractive; yet when it comes to the point of saving everything which can be saved, and of cutting down expenses to the lowest possible cost of operation, the former mine is doubtless on the firmer and more economical financial basis. But as to the relative merits of the system of mining in the two cases, nothing could be decided without a basis of detailed comparison ; if one system is more economical than the other, why is it so, and wherein does the advantage lie ? This can be shown only by keeping accurately the cost of each mining operation. And no matter how dissimilar two mines may be in character and operation, yet there are a few general heads common to all mining operations. In the first place, it is necessary to break the ore from the solid ground;

Jan 1, 1907

Reduce the dust exposure of workers in large processing buildings at mineral processing operations, using a total mill ventilation system.

Jan 1, 1994

IN the footnote on the first page of Prof. Stoek's paper, as printed in vol. xxviii. of the Transactions, I alluded to him, under an erroneous impression, for which he was in no way responsible, as " the present Director of the Scranton Schools." This incorrect statement placed him in a false position, as possibly having authorized the use of a title to which he had no claim. In fact, Prof. Stoek has never had any official connec-

Jan 1, 1900

By Stephen D. Cramer

The objective of the present studies was to develop thick adherent and coherent coatings of platinum and palladium on refractory metals and other substrates of industrial and engineering importance. Existing platinum and palladium electrolytes were modified to make them suitable for the electrodeposition of thick deposits. The optimum operating conditions for these electrolytes were established. Pretreatment procedures for columbium, copper, graphite, molybdenum, nickel, stainless steel, tantalum, titanium, tungsten, vanadium, and zirconium substrates were studied. New pretreatment procedures for columbium, molybdenum, stainless steel, tantalum, tungsten, and nickel were developed. The internal stress and hardness of selected electrodeposits were measured. The effects of heat treatment upon the properties of electrodeposits were studied.

Jan 1, 1967

By J. A. Woolf, A. P. Towne

"INTRODUCTION A considerable part of the metallurgical work of the Precious Metals Section comprises ore-testing experiments on ores selected as representative of various mining districts on areas. Projects authorized by the Bureau and assigned to the Precious Metals Section generally include only those ores or tailings in which the precious metals are the main valuable constituents; however, there are also included ores that contain strategic or critical metals in addition to the precious metals. The recovery of strategic and critical minerals is the most important phase of the treatment of this latter class of ores. However, if a considerable percentage of the precious-metal content of such ores can be recovered without complicating the flow sheet too much, it may be possible to treat an ore for the recovery of strategic or critical metals that could not otherwise be treated at a profit.Standard testing procedure involving cyanidation, amalgamation, gravity concentration, and flotation, or a combination of these methods, is employed in the greater part of this work. However, as the complexity of the ores furnished for this work has increased, it has been necessary to include special applications of standard procedures in many instances, Standard methods of conducting tests and the purposes of the work as a whole have been discussed in previous reports 4/ of ore-testing studies. In the present report, whenever it has been necessary to apply some special phase of standard treatment, this has boon explained in detail in that particular section of the report."

Aug 1, 1944

By Roger L. Baer

Introduction Brief Review -SEC mission & history -Development of SEC mining disclosure guidelines -Principles of good public company ‘disclosure’ SEC staff views of alternative approaches to mining company disclosure -SME Resource & Reserve Committee – April 2003 Food for thought

Jan 1, 2003

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990

By Dirk van Zyl

Three conditions are required for a risk to be realized: (1) a source of risk (i.e., hazard) must exists (2) some process must take place which will lead to the exposure of people, animals, and/or the environment to the hazard: and (3) as a result of the expense, undesirable effects are produced on the people, animals, and/or the environment. A comprehensive risk assessment addresses all three of the conditions through the following four steps: (1) risk source (hazard) characterization, (2) exposure assessment, (3) dose-response assessment, and (4) risk estimation. Although the terminology may differ, the overall approach of financial, public health, and environmental risk assessments is the same (National Science Foundation, 1985).

Jan 1, 1988

By E. A. Zawadzki

The problem of pollution of water by mine drainage is at least as old as the mining industry itself. However, research on the formation, composition, treatment, and abatement of mine water is a relatively recent historical event. At Bituminous Coal Research, Inc., acid mine drainage control has been an important area of work since 1944, at which time BCR began sponsorship of research at West Virginia University. The work at West Virginia University involved a detailed study of the acid mine drainage problem and led to the identification of iron oxidizing bacteria as important factors in the formation of acid mine water. The results of this research were summarized in 1954 by Temple and Koehler (1) who concluded that "no practical solution for the problem" of controlling acid mine drainage is yet known.?

Jan 1, 1967

By J. K. Whyatt

U.S. Bureau of Mines researchers reviewed an in situ stress estimate developed from measurements of overcore strain taken at test sites on the 7300 and 7500 levels of the Star Mine near Mullan, ID. Although the field measurements of over coring strain were found to be useful, significant deficiencies were found in the stress estimation procedure. A new stress estimate was developed incorporating statistical methods and an improved understanding of stress concentration factors for interpreting overcore strains recorded by doorstopper' cells. Spatial variability of overcore strains and the implications for stress field variability were explored.

Jan 1, 2010

By L. Filip

The roast-leach-electrowinning (RLE) process for zinc was modified to treat two typical complex concentrates containing zinc, lead, copper, gold and silver. Laboratory testwork results indicated that the optimum roasting temperature ranged from 700 to 800°C, in order to produce acceptable residual sulfur levels. The calcined concentrate was subjected to a three-stage leach sequence. The resulting leach solution was purified by hematitic precipitation and directed to the recovery of copper and zinc by solvent extraction and electrolysis. Alkaline smelting and subsequent electrolytic purification recovered the lead and precious metals from the leach residue. A flowsheet was developed based on the laboratory testwork results, and demonstrated in a large-scale pilot plant. The recoveries produced during the pilot plant operation ranged from 90 to 92% for zinc and copper, 85% for lead and 90% for gold and silver, respectively.

Jan 1, 1999

By N. R. Sainath

This paper discusses the results of a laboratory investigation carried out to study the microscale flow characteristics of copper ores and the variation in flow behavior resulting from flow of leach solution. Fractures in 1.5 and 4 inch diameter cores were mapped by visual inspection. The cores were stressed in a triaxial stress field representative of in situ conditions. The permeability of the samples to water was then estimated. The samples were exposed to 20 g/l sulfuric acid and the experiment repeated. The Permeability of unleached samples ranges from 10-1 to 10-19 m2 and it increases as leaching progresses. The porosity variation and the rate of recovery of copper from the specimen during leaching were also studied.

Jan 1, 1991

By Jessica M. Wempen, William G. Pariseau, Michael K. McCarter

"Quantitative analysis of mine-wide subsidence at the kilometer scale and details of stress distribution about an advancing longwall face are estimated using an adaptation of the finite element method. The method is well suited to the tasks at hand. For greater realism, variability of strata properties is taken into account as are the effects of joints and cleats on elastic moduli and strengths. Evolution of pillar stress and entry closure remote from the face is readily quantified in a series of analyses that simulate face advance. Computed results compare favorably with the evolution of closure measurements about an instrumented pillar in a two-entry headgate. The appropriateness of the finite element method is confirmed. This method is based on first principles that avoid empirical schemes of uncertain applicability and numerical models “calibrated” by fitting computer output to mine measurements.INTRODUCTIONMine-induced seismicity is intimately related to strata mechanics associated with longwall coal mining and room and pillar mining, as well. Strata deformed beyond an elastic limit often tend to fail rapidly by brittle fracture and, thus, to emit acoustic signals in the form of elastic waves. Understanding the induced seismicity in coal mining offers the potential for early warning of hazardous conditions. Many years of experience with seismic phenomena associated with hardrock mining suggest considerable complexity should be expected. However, recent coal mine studies (Pariseau, 2014; Pariseau, 2015; Pariseau and McCarter, 2015; Pariseau and McCarter, 2016) have shown high correlations of seismicity with element failures in finite element simulations. The main lesson learned from these studies is one elaborated by Iannacchione et al (2005); deviation from normal activity is an early warning of ground control difficulty. For example, an abrupt increase in seismic event rate, or equivalently, an increase in element failure in finite element simulation of panel advance, is a cautionary indication for ground control. Present and past study results demonstrate the effectiveness of finite element simulations for mine design and early detection of potential ground control issues."

Jan 1, 2018

By Fazel G. Jahromi, Ahmad Ghahreman

"Several studies were performed on the atmospheric leaching of copper sulfide minerals in the presence of activated carbon and a new catalyst, AF 5. AF 5 is a carbon based catalyst with similar properties to those of activated carbon however much better mechanical properties. The activated carbon surface chemistry has been investigated in various studies; however the connection of the surface chemistry of activated carbon and AF 5 with the sulfide minerals during the atmospheric leaching process is not well-understood yet. Based on the surface analysis, AF 5 showed higher surface area than activated carbon (AC). Adsorption and oxidation of copper, arsenic and iron ions in the presence of different activated carbon were investigated. Adsorption properties of both catalysts were similar and 18-24% of iron, 12-18% of copper and 10% of arsenic adsorbed on the catalysts surface form 5 g/L Fe(III) and Cu(II) and 2 g/L As(III) at 80°C. In oxidation experiments, both catalysts reduced Fe(III) and Cu(II) ions and re-oxidized the reduced species in the presence of oxygen and oxidized As(III) ions. The addition of oxidizing ions can enhance the oxidation process kinetics and increase the catalytic capability of carbon.INTRODUCTION Hydrometallurgical processes of copper sulfide concentrates are under development and various different methods have been proposed to increase the atmospheric leaching rate of copper sulfide minerals. These methods include using different media, reagents, and catalysts. Among different methods, leaching of the copper sulfide minerals in the chloride media has some advantages over sulfate media. Smaller scale of operation, increased leaching rates, and lower sulfate formation are some of the benefits of the chloride leaching media over other similar media. Moreover, using ferric and cupric ions as oxidants and utilizing activated carbon as a catalyst has been proven to enhance the leaching rate of copper sulfide minerals effectively. Activated carbon (AC) and AF 5 (micro porous carbon based catalyst) are two of the most efficient and practical catalysts in copper sulfide leaching processes. AC can enhance the copper recovery of enargite in chloride media from 69% to 92% after 96 hours of leaching under the similar conditions (Jahromi & Ghahreman, 2016). It has been shown that AC at acidic pH can generate hydrogen peroxide in the presence of oxygen which can leach copper minerals (Ahmumada et al., 2002)."

Jan 1, 2017

By Robert L. Brooks

Blasting liability problems are frequently compounded by a company's inability to effectively communicate with concerned property owners and the lack of adequate complaint documentation. Often, by the time the insurance carrier becomes involved in a blasting claim, the situation has deteriorated to the point that a solution agreeable to both parties is virtually impossible to reach. The insurance carrier, wishing to minimize their lose potential may decide to pay on a somewhat questionable blasting claim rather than be drawn into lengthy civil proceedings that would ultimately end up in front of a jury with little chance for a successful outcome.

Jan 1, 1992

An experimental study of the influence of surface active agents on the dewatering of fine coal was undertaken with a view to evaluating the usefulness of such materials in reducing the residual moisture contents of filter cakes. Experimental evidence is presented which suggests that while polymeric fiocculants have a beneficial effect on settling, they can have adverse effects on the filtration of the thickened underflow. Detergent addition, on the other hand, was shown to reduce filter cake moisture, and the magnitude of this effect was determined, in part, by the prevailing electrochemical equilibrium at the solid-solution interface.

Jan 1, 1976