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By Alfred Boyles

"HEREDITY"' in cast iron has been a subject of much discussion. Numerous experimenters have found that the properties of gray iron may vary greatly without corresponding variations in composition or thermal treatment. The main structural difference in such cases is in the size and distribution of the graphite flakes and the explanations given usually attribute this difference to some chemical element not shown by ordinary analysis or to some physical factor, such as inclusions in the melt. It cannot be said that any of these theories is completely satisfactory. Much remains to be learned about cast iron and for this reason a study of the material was undertaken as a part of the program of fundamental research at Battelle Memorial Institute. A review of the literature indicated that very little systematic work had been done on the mecha-nism of freezing in cast iron. The experiments described below are largely concerned with that problem.

Jan 1, 1937

Jan 1, 1935

By R. E. Miller

Accelerometers and pressure transducers mounted in suspension components can be used to monitor the ride of haulage trucks. Presently, it is difficult to tell what caused a jolt to the truck using either pressure or acceleration data alone. When information from a Global Positioning System is recorded at the same time as shock pressures or acceleration data, then the exact location of an event can be determined. Mine management can then determine what caused the jolt to the truck.

Jan 1, 1999

By M. Schwartz

Hosting copper, gold, oil and liquefied natural gas, the country is an interesting target for miners. However, remote locations in inhospitable, unusual and difficult terrain cause problems. The government has worked to create a Sovereign Wealth Fund to manage government surpluses from minerals and energy but PNG scores very low among many criteria, including land dispute resolution, as revealed by the 2014 Canadian Fraser Institute in its survey of senior mining personnel.

May 1, 2015

By Beeforth C. G

The use of Non-Linear Programming to obtain improved schedules of future activity in two specific cases of mining and treatment of minerals is described. The two cases were (i) reclamation of gold, uranium and sulphur from old surface tailings dams and, (ii) underground mining of gold. The method used an augmented Lagrangian device to reduce a constrained Non-Linear Programme to a sequence of unconstrained hill- climbing procedures. The main advantages of the method appear to be those of (a)flexibility of modelling of industrial characteristics and constraints and, (b) reasonably modest computation times.

Jan 1, 1977

By L. A. Vermeulen, D. D. Howat

A study was made of the performance of a rod mil operating without liter bars and with different arrangements of liter bars in the lining. . The results show that striking improvements in performance, increased throughput, and reduced consumption of liner metal and electrical energy can be obtained by a change in the geometry of the liter-bar arrangements within a mil. Rod mils of equal size fitted with the same arrangement of liter bars but operating at different speeds presented apparent anomalies in the relative consumption efficiency of electrical energy for the production of material smaller than 75 µ m. Marked savings in the consumption of liner metal were achieved by the use of an arrangement of alternating lines of higher and lower liter bars. A study of the relative performances of two large tube mils showed that the use of liter bars in one of the mils resulted in a marked reduction in the consumption of liner metal and electrical energy per ton of material smaller than 75 µ m in the product.

Jan 1, 1986

By A. Kowalski

This paper presents methods of implementation and the added value that can be achieved by connecting personnel tracking systems and alarm-broadcasting systems. The authors point out the functions of the two systems that enable cooperation between them. Methods for connecting the systems on the surface and underground areas of mines require some intervention in both systems, so the authors point out a possible phased approach to introducing cooperation methods. Due to the fact that tracking systems in Polish mines are at an early stage of implementation, the article aims to provide new functionality, attempts to identify the needs of future users, and describes the experience of both production companies in terms of the development of cooperation methods.

Aug 1, 2013

By Collins DN, Hollick CT

Conventional processing of heavy mineral deposits containing radioactive rare earth minerals such as monazite and xenotime may cause industrial hygiene problems through atmospheric dust and contamination of product concentrates. An alternative procedure has been developed in which such minerals are removed from bulk heavy mineral concentrates by flotation with little loss of other economic minerals. With fine ores, recoveries of over 95% have been achieved and with coarse ores over 80%,in both cases at high grade. Several flotation regimes have proven effective. The potential for generation of radioactive dust or product contamination is subsequent processing -is correspondingly reduced.

Jan 1, 1990

By Sangjian Zhang, Zhu Xiao, Lairong Xiao, Rushi Chen, Mei Fang, Zhou Li

The copper-graphite metal matrix composites were fabricated by two different production methods: directly sintering with copper and graphite (Cu-Gr composite), and in-situ sintering with cuprous copper and graphite (Cu2O-Gr composite). During the in-situ reaction sintering, a redox reaction occurs at the interface of the Cu2O particles and Gr particles, resulting in the improved physical and mechanical properties of Cu2O-Gr composites. Compared with Cu-Gr composite, Cu2O-Gr composite has a higher compression strength at any given graphite content due to the improved interface bonding and uniformly distributed fine graphite particles in the matrix. Increasing graphite content decreases the mechanical properties of the copper-graphite composites. The compression strength of Cu2O-Gr composite is 50-100 MPa higher than that of Cu-Gr composite. INTRODUCTION Copper-graphite composites have been widely used in industry due to their low density, relatively high strength and hardness, good thermal and electrical conductivity, arc ablation resistance and self- lubrication ability (Grandin & Wiklund, 2018; Han & Xu, 1999; Huang et al., 2017). Electric sliding contact friction pair in the high-speed railway system and motor brush in electric contact components have a very high demand on electrical conductivity and self-lubrication ability of materials. The electric devices need to bear both mechanical load and high electric current. Copper-graphite composites with good mechanical, electric and self-lubrication properties are the best candidates for application in multifunctional electric sliding contact frication components. The relative sliding speed of friction pair is developing towards 100 m/s or even faster, which can withstand the electric flow of more than 800 A, and it is often accompanied with vibration and impact (Guo & Ding, 2008). Conventional wear-resistant materials can no longer meet the current requirements and this promotes the development of copper- graphite composites with excellent comprehensive properties (Ding, Chen, Zhu, Zhang, & Zhou, 2009; Yasar, Canakci, & Arslan, 2007). There are many ways to fabricate copper-graphite composites, mainly including powder metallurgy method, liquid immersion infiltration method, rapid sintering method and electrodeposition method (Kalin & Poljanec, 2018; Kim, Lee, & Han, 2014; Liu et al., 2018; Wang et al., 2018). Each method has its own advantages and disadvantages, and the powder metallurgy method is the most commonly used one due to its simple process, high economic benefit, and industrial production applicability. The common steps of the powder metallurgy method are as follows (Samal, Parihar, & Chaira, 2013): firstly mixing the copper (copper alloy) powders and graphite with a certain ratio, following by die-forming, and then sintering at the high temperature with or without pressure. The advantage of copper-graphite composites is that the graphite distributed in the copper matrix uniformly and it can form a carbon diaphragm preventing the wear of the composite (Fu & He, 2010). However, the bonding strength of the interface between the copper matrix and the graphite is relative low as the combination between them is mechanical interlocking but not metallurgical bonding (Ma et al., 2008). It is meaningful to develop new fabrication technology of copper-graphite composites with better interface bonding, which could provide guidance for the design of copper-graphite composites with excellent comprehensive properties.

Jan 1, 2019

By J. P. Allen

Cobalt, nickel, and manganese can be recovered quickly, cleanly, and selectively from cobalt-rich manganese crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be non-hazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods for recovering their valuable components.

Jan 1, 1990

By W. C. Elmore

THE magnetic powder method, long used for roughly mapping mag-netic fields, has recently been refined 1,2 for investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators3 have used Bitter's original technique, with slight modifications, to study the varia-tion of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations-of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement in the powder technique which led us to the discovery of a new effect throwing con-siderable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure.

Jan 1, 1935

By S. R. Zimmerley, S. F. Ravitz

High-grade cobalt concentrates were produced from the complex Blackbird ore with very good recovery in continuous pilot-plant operations in which a low-grade bulk cobaltite-pyrite flotation concentrate was roasted in a multiple-hearth furnace to oxidize the pyrite selectively. The cobaltite was floated from the resulting calcine. THE existence of the cobalt-copper deposits in the Blackbird district, Lemhi County, Idaho, has been known for many years. However, these deposits have not yet been exploited successfully because of the low grade of the ore, absence of information on ore reserves, and lack of feasible methods for concentrating and recovering cobalt from the ore. In 1941, when it appeared that World War II might interfere seriously with imports of cobalt from overseas, the U. S. Bureau of Mines started an extensive mining and metallurgical investigation of the Blackbird deposits. Exploration by trenching and drilling1 indicated that ore reserves were adequate to warrant consideration of large-scale exploitation. A process for producing high-grade cobalt concentrates from the ore was developed at the Salt Lake City Station of the Bureau,2 and hydrometallurgical procedures for producing cobalt metal or oxide from the concentrates were developed at the Boulder City Station.3 The Howe Sound Co., through a subsidiary, the Calera Mining Co., carried out further exploratory work, which increased probable ore reserves to a tonnage commensurate with a large investment in mine, mill, transportation facilities, and refinery. Simultaneously, the metallurgical staff of the company, working in cooperation with the Bureau of Mines, further investigated the metallurgical problems. It was the opinion of both groups that pilot-plant testing was required to translate laboratory results into plant operation. In general, the Blackbird ore has a high content of pyrite and some pyrrhotite and contains 0.5 to 1 pet cobalt and 1 to 2 pet copper, which are present essentially as cobaltite and chalcopyrite. The copper can be recovered readily as a high-grade concentrate by selective notation. The cobalt then can be recovered as a bulk sulphide concentrate assaying 4 to 5 pct cobalt, but no satisfactory procedure for separating the cobalt from the pyrite and pyrrhotite directly by flotation had been found. The method developed by the Bureau for producing a high-grade cobalt concentrate is essentially an application of the old Horwood process of selective roasting.4 The bulk sulphide concentrate is roasted to form an oxide coating on the iron mineral particles, and the calcine is then treated by flotation. The oxide coating prevents the iron minerals from floating so that it is possible to obtain a high recovery of cobalt in concentrates assaying more than 20 pct cobalt. Laboratory tests by metallurgists of both the Bureau and the Howe Sound Co. had indicated the optimum roasting temperature to be 425° to 450°C. At lower temperatures the rate of oxidation of the iron minerals is too low, whereas at higher temperatures substantial quantities of cobalt are rendered water-soluble. Because of its high sulphur content (35 to 40 pct), the bulk concentrate tends to continue to burn after it has reached the optimum roasting temperature. Although excessive temperatures could be avoided in the small-scale laboratory furnaces, there was considerable doubt that the temperature could be controlled properly in industrial equipment. To provide material for the pilot-plant tests, the Calera Mining Co. installed a small, temporary flotation mill at the Blackbird property and treated

Jan 1, 1951

By Sandra L. Mesa-Espitia, Gretchen T. Lapidus

Gold present in arsenopyrite matrices is refractory and requires highly oxidative pretreatments in order to obtain acceptable degrees of extraction. However, these release many byproducts that are harmful to the environment. In the present work, a high-grade arsenopyritic ore was pretreated with different solutions, containing hydroxide ion, EDTA, oxalic, tartaric, or citric acids, to improve gold extractions in a posterior leaching step. The pretreatments were carried out at room temperature for 24 hours with a respective ligand concentration of 0.25 M. Once completed, the residue was leached in a thiosulfate solution to quantify the effect of the pretreatment on gold extraction. Only 29% of the gold content was leached, with very slow kinetics, in the untreated mineral. However, after pretreatment with tartaric or citric acid, the kinetics improved, although the percentage of gold extraction only reached 42-45%. The highest gold recovery, with very rapid kinetics, was found with the oxalic acid or the hydroxyl ion pretreatment (70 and 62%), respectively, but also corresponded to the most arsenic co-dissolution.

Jan 1, 2014

By R. T. Mishler

Silver-gold. mine, in northern Mexico, with arrow veins in rhyolite. One fourth area developed has been ore. Deposits average 20 in. wide and 73 oz. silver per ton; diluted in mining to 40 oz. per ton. Developed by drifts and raises at 100-ft. intervals. Samples cut every 5 ft. Ore and waste sampled separately to make combined stoping width 3 or 3 1/2 ft. Ore reserves figured to sloping width; high assays not modified. Tonnage and assay of ore extracted higher than estimates. Ore stoped principally by cut and fill method. Cars from each stope counted and sampled. Cars check tonnage to concen¬trator within 1 per cent.; silver assay 9 per cent. high. Tonnage and assay from scopes corrected to agree with feed to concentrator. Profit or loss for each slope estimated monthly. THE Lucky-Tiger mine is a silver-gold property, situated at El Tigre, in the northeastern part of Sonora, Mexico, at, an elevation of 6000 ft. in the Sierra Madre Mountains. It is 30 miles by wagon road from the Esqueda station on the Nacozari railroad. Since its discovery in 1903, the mine has produced forty million ounces of silver. The ore has averaged 40 oz. silver and 0.25 oz. gold per ton. Copper, lead and zinc have been of minor importance, having averaged 0.4 per cent., 1.1 per cent., and 1.5 per cent., respectively. The richness of the ore,, combined with its occurrence in narrow veins, required the use of the more expensive methods of mining.

Jan 2, 1925

By Rudy Rogers

When Gas hydrate formation rates have two steps: a nucleation induction step and an agglomeration step. Hydrate induction in distilled water is extremely slow because of lack of nucleating particles. Our laboratory found that synthetic anionic surfactants greatly improve both hydrate induction and agglomeration because the surfactant?s hydrophilic head absorbs water molecules and the hydrophobic tail absorbs hydrocarbon gas molecules, creating necessary nucleation sites. Vast hydrate deposits inhabit seafloors. What is the seafloor hydrate nucleating mechanism? We find that nano-particles of smectite clays (bentonite and nontronite) are hydrate-nucleating sites in sea-water-saturated, packed porous media, especially when trace quantities of anionic biosurfactants adsorb on the clay particles. Microbes and their bioproducts proliferate around seafloor gas hydrate accumulations. The seafloor microbe-mineral-hydrate synergy is explored in this paper. Keywords: gas hydrates, biosurfactants, crystal nucleation, smectites

Jan 1, 2008

By Richard R. Klimpel

The purpose of this paper is to summarize some of the author's experiences in applying population balance models to a variety of industrial grinding circuits. Over 26 separate industrial circuits have been studied in detail during the last 10 years, each unique in its equipment type and layout as well as in the material (s) being ground. The success of the population balance approach during these studies was variable. Fourteen of the circuits were shown to be very amenable to such an approach while the remainder had conditions present that sufficiently violated the standard population balance assumptions so that the analysis was of less than optimal utility. Some discussion of the importance of standard population balance assumptions will be given. It is increasingly becoming this author's opinion that the use of population balance models has its greatest utility in defining logically and cheaply (in contrast to actual physical testing), the relative limits and comparisons of different proposed circuit configurations and changes in equipment types and/or operating conditions. As far as specific quantitative predictions and actual optimization of existing plant performance, the results of applying the population balance approach have been often disappointing and need to be coupled at the plant level with other engineering quantification techniques in order to achieve desired improvements.

Jan 1, 1992

By A. L. Williamson

Bio-mining, the use of micro-organisms to recover elements of interest, is potentially useful for the economic extraction and recovery of ore metals from a variety of ore deposits, including the lowergrade uranium deposits found in the uraniferous quartz-pebble conglomerate beds of the Quirke Syncline, Elliot Lake, Ontario. The metabolism of chemolithotropic bacterium Acidithiobacillus ferrooxidans depends on an ability to derive energy and reducing power from the oxidation of ferrous iron found in a varirty of iron sulphide minerals associated with base, precious metal and uraniferous ores. The characteristics of this bacterium, especially the ability to oxidize both iron and sulphur with an associated high tolerance of low acidity, allow the organism to contribute significantly to bio-mining processes. Under ideal conditions, A. ferrooxidans promotes the oxidation of ferrous iron in low sulphide ore materials, breaking the crystal structure of the ore minerals .releasing protons to the surrounding solutions, thus promoting the dissolution of uranium and rare earth elements, among others. This paper provides an overview of elemental dissolution and release of uranium, rare earth elements and investigates the acid generating potential of the final residues, from a series of environmentally controlled, biologically-mediated uranium ore extraction experiments. The findings will be used to guide in the design of larger scale bio-leaching experiments to further assess the potential for successful bio-mining operations along the Quirke Syncline.

Aug 1, 2010

By M. K. Jain, Z. T. Xu, M. Bruhis, V. Hegedekatte

"Strain rate and temperature dependent deformation conditions are present during elevated temperature forming of aluminum and other metallic materials. While many constitutive laws have been proposed to represent such deformation conditions, a closer investigation often reveals their limited applicability in terms of fit to the experimental data, and interpolation within and extrapolation outside of the range of experimental stress-strain curves. This is often because material-specific primary deformation mechanisms of temperature-dependent strain and strain rate hardening are poorly captured. In the present work, the Voce-Kocks constitutive model based on mechanics of dislocations storage and annihilation has been found to be suitable for many metallic materials. The model was modified to include the effect of temperature dependent shear modulus. The modified model is then employed to represent the experimental data obtained from uniaxial tensile tests on AA7075-O sheet at elevated temperatures and strain rates. Also, hot gas bulging tests were conducted to verify the applicability of this model. Further, finite element simulation of the hot gas bulge test was performed by incorporating the model as a user material subroutine. Good general agreement was observed between the experimental and FE model predicted results. Some sources of discrepancy in the prediction are also discussed.INTRODUCTION There has been much interest in light-weighting of automobiles from automotive related industries to reduce overall carbon footprint and increase energy efficiency of the vehicles. Aluminum alloys, and especially the medium-strength 5xxx and 6xxx series alloys, have been the primary focus in the last 3 decades to reach the above environmental goals (Huo, Hou, Zhang, & Zhang, 2016) whereas aerospace industry has traditionally focused on high strength 7xxx series aluminum (Al-Zn-Mg-Cu) alloys for structural components (Deng, Yin, & Huang, 2011). Recently, there has been much interest in high strength 7xxx series aluminum as a replacement for heavier steel automotive structural parts such as A-pillar, B-pillar, side impact beams etc. (Harrison & Luckey, 2014). This is both interesting and challenging since the above aluminum structural parts will need to not only meet impact safety standards but also possess sufficient formability for manufacturing such complex parts. Since the formability of high strength 7xxx series materials is quite poor at room temperature, much interest has focused on improving both formability and final part strength via high rate hot stamping, in-die quenching, and subsequent artificial ageing process steps (Kumar & Ross, 2016)."

Jan 1, 2018

By Hong Ouyang

A unified computational model has been developed for the Bridgman growth processes of B-NiAI and CdTe crystals. To handle the geometrical and physical complexities, a two-level approach has been developed. At the gtobatlevel, conjugate heat transfer, phase change dynamics, and variable material properties along with the realistic geometries and thermal boundary conditions are accounted for inside the entire crystal growth system. Refined calculations are then made within the ampoule, with the boundary conditions supplied by the global simulations. This model can optimize the use of computational source, help understand solidification behaviors, and improve designs of crystal growth system.

Jan 1, 1996

By Valentin Choquenaha Bombilla, Oscar Alvarez Muiloz

"Tintaya’s basic production line is copper concentrate, which has an important gold content. The process used is flotation; the objective of the metallurgical department is to obtain the best results in the copper recovery without neglecting the gold, using very specific reagents. Copper recoveries are considered high, nevertheless every day emphasis is placed upon increasing those recoveries. Regarding gold, optimum recoveries could not be achieved with flotation; and implementation of a gravity circuit was considered.According to microscopy studies, the coarse and very fine grains of gold in native form are lost to tails. The native gold due to its high specific gravity is concentrated at the underflow of the cyclone, remaining in the circulating load of the circuit. It reaches three times the concentration compared to the head grade entering the ball mills. This re-circulation generates very fine and laminated gold particles inside the ball mill, passing to the classification stage making a short circuit to the overflow of the cyclone.The very coarse gold particles as well as the thick flakes of gold do not react favorably to the conventional flotation process; thus studies that have included gravity separation have been conducted to increase the gold recovery. Part of the research included concentrating tables, jigs, and Knelson Concentrators. The Knelson Concentrator proved to be the best selection in terms of metallurgical performance and recoveries considering the throughput and operation conditions of the Tintaya Plant.The gravity concentration circuit with the Knelson Concentrator was commissioned in BHP Tintaya in October 1998, as per the flowsheet shown later on. Presently the global gold production surpasses any estimated expectations.Present efforts are directed towards showing the evaluation and optimization of the different parameters that govern the performance of the Knelson concentrator, as well as illustrating the difficulties and successes throughout the operating period.In the first year of operation 200 tons of gold concentrate have been produced with an average concentrate grade of 320 gramdton, having paid back in full the cost of the automated KC-XD- 48 Knelson Concentrator, the peripheral equipment, and the cost of the installation."

Jan 1, 2002