Search Documents

By Xiang Ma, Halvor Dalaker, Kai Tang, Stefan Andersson

Silicon carbide (SiC) is one of the most important non-oxide ceramic materials for many industrial applications and is mainly synthesized by carbothermic reduction of silicon oxide by coke above 2200°C. Replacing natural gas (mostly methane, CH4) for coke in SiC synthesis could considerably reduce energy consumption and CO2-emissions owing to higher carbon activity of CH4 at lower temperature. The generally accepted reaction mechanism is that SiC is synthesized through gaseous intermediate silicon monoxide, SiO. In the present study, the reaction mechanism for the SiO and CH4 gaseous mixture has been examined using atomic scale modelling. Molecular dynamics (MD) using a reactive force field (ReaxFF) has been utilized to examine the initial stages of reactions involving a gas mixture of SiO and CH4 and surfaces of SiC. The MD results revealed some interesting SiC formation mechanisms. The reaction energies of the critical intermediate species were also estimated by density functional theory (DFT) calculations and the implications for the force field parameters used in ReaxFF was discussed.

Jan 1, 2015

By O. C. Ralston

Natural or artificial manganese dioxide of a grade pure enough to be satisfactory as depolarizer for dry cells has never been available in large supply simultaneously with being available in desired quality . The Second World War called for more of it than ever . A supply of natural material from the Gold Coast was ample for the war and was not completely exhausted . Whereas the crystal form of the manganese oxide was not recognized as a matter of importance until the war came , it is now known that gamma MnO2 is a desirable form and that pyrolusite , once thought acceptable , is not the best mineral . The following paper is a translation of an internal company report filed at the Bitterfeld office of the I. G. Farbenindustrie A.G. by Dr. Peter Marx in 1933 , just a year after G. W. Nichols had published in the Transactions of the American Electrochemical Society a study of making anodic manganese dioxide from solutions of manganous sulfate . The I. G. experiments were made to confirm the American work and were also extended to a larger scale . Only chemical purity was considered , and no mention is made of crystal form . The report adds to the knowledge submitted by Nichols but has not been previously available to the general public . Believing it of value to the United States industry , a translation has been made .

May 1, 1948

By WM. H. RINKENBACH, C. A. Taylor

No complete work on explosives, their constitution and analysis, has hitherto been published. Several books that contain chapte.r;s on analysis do not cover the matter thoroughly. Methods tha;t, manu~ facturers, testing stations, and other . agencies have developed to meet their own requirements have not been made public. The Bureau of Mines has issued four publications 1 - cov:eri:ng special phases of the subject. This bulletin. is not inte.nded to replace those reports, but rather to cover present methods employed 'in the , industry and to include all classes of explosives and the materials used in their manufacture. No sharp distinctions can be drawn between classes of explosives. . Surplus military explosives, for example, may be used for blasting, just as blasting explosives, under some conditions, may be employed for military purposes. Moreover, one class gradually merges into another because of similarity in composition. Explosives are here grouped as dynamites, black powders, propellants, detonators, and primers. Some materials are used in practically all these groups ; others in only one. To discuss all the materials that have been or that may be used and the methods for their identification and quantitative determination is not feasible, but the methods described will probably suggest ways of examining new mixtures.

Jan 1, 1923

By F. Waanders, Campbell. Q.

This project was specifically aimed at using increased acceleration separation, as a method to optimize the recovery of gold in an ore body mainly consisting of hematite where the specific gravity of gold is much higher in comparison to the carrying material, making it possible to separate gold from other materials like silica, base metals and their oxides, usually associated with gravitation-gold-recovery-processes. The ore body investigated in this project originated from a gold reef containing a large portion of gold locked inside the gold pyrite complexes, which was mined and treated in a conventional way. After gold extraction, the material was pumped to a tailings dump and the gold extraction of this dump was investigated. In order to assemble a concentration plant setup, the head grade and size distribution of the dump and bulk sample were determined accurately. Chemical analysis and mineralogical examination were done on a representative sample of the bulk sample, to determine the chemical composition of the material. The results obtained thereof were evaluated and a pilot plant was configured. A bulk sample was processed in the pilot plant and the results were evaluated. The results at optimum acceleration forces applied, resulted in a recovery of 5% of the mass, with a gold concentrate of 90 g/t Au, which represented 58% recovery of the gold. The hematite with high specific gravity as main phase positively influenced the high acceleration separation process. It proved that if the specific gravity of particles in a suspension were increased, high acceleration separation could be applied effectively to separate much smaller particle sizes.

Jan 1, 2014

By Jerome Feinman, Sven O. Santen

"The principles involved in the generation and application of plasma energy are reviewed briefly and the major developments in commercial and semi-commercial primary metal and alloy production are described and discussed in broad outline, with emphasis on present performance and future potential. New concepts in the application of plasma energy in primary operations are described with emphasis on the expected advantages over conventional technology and the problems that have to be solved to enable effective implementation.IntroductionThe use of plasma energy in industrial processes is generally considered to have started in 1905 with the operation of the Birkeland process for nitrogen fixation for fertilizer production. Although it seems logical to apply plasma energy to metallurgical processes, which also usually require considerable energy at high temperature levels, serious development work along these lines did not begin until the early 1970's. The reasons for this hiatus are associated in part with recognized difficulties in applying plasma energy in processes involving tonnage quantities of solids in severe industrial environments and the delicate nature of the earlier plasma generators. Another, and perhaps overriding factor, is the fairly steady improvement in efficiency and economy of most primary metal producing processes by conventional developments and modifications through the 1950's and 60's. Examples of these evolutionary changes include burden preparation and fuel injection in blast furnace applications and prereduction treatments in ferroalloy operations. By the end of the 1970's most primary metal producing processes had been optimized close to the limit, at least in terms of those operations that were able and willing to implement the developed improvements. In this context, plasma energy offered the possibility to achieve further significant improvements in primary operations where conventional means were exhausted."

Jan 1, 1988

By Agustín Arias

El presente artículo describe brevemente la historia, métodos de explotación, mecanización, energía eléctrica, las plantas de preconcentración y flotación y el consumo de reactivos de la compañía minera Milpo.

Nov 1, 1954

By M. M. Fine

"Button" type ore from the Cason mine, Batesville, Ark., can be up-graded to plus-40-percent manganese by mineral-dressing procedures. A simple process including gravity concentration and. magnetic separation yielded more than 50-percent recovery of concentrates containing 38.1 to 40.6 percent manganese. These values in turn could be raised to 41.4 and 42.8 percent, respectively, upon sintering to conform to size specifications. The Bureau of Mines in the past has surveyed and tested many manganese ores and prospects in an endeavor to alleviate the shortage of manganese. The present period of emergency again emphasizes the strategic position of the metal, and manganese investigative work is being stressed to find new ore bodies and to apply newer beneficiation techniques to the known deposits.

Jan 1, 1953

By C. H. Benedict

Largest and most important of the milling plants under construction during the year is the Morenci plant of the Phelps Dodge Corp., in Arizona, where plans are being rushed for production in 1942. Grate mills will be used for fine-grinding, and in the pilot plant, classifiers of the spiral type have the preference for the closed- circuit work. The flotation units will be chiefly of the pneumatic type, with some mechanical units as auxiliaries. The Fagergren, Pan American, and Agitair machines were left in the competition as the year closed. If the absence of European markets for finished products has dislocated the mining industry, fortunately the lack of raw materials required in the beneficiation of ores has not been serious. except possibly as to the inability to import flint grinding pebbles. Some of the less important gold mines still use pebbles for grinding as is also the practice in the comminution of nonmetallics used in various industries. T the Calumet & Hecla in the Lake A Superior copper district pebbles have been used exclusively in open- circuit grinding in the Hardinge mills treating the

Jan 1, 1941

By Ben Bowman

For certain ferroalloy furnaces, such as ferrochrome or ferromanganese, there is still doubt about the mechanisms operating under the electrode tips. In this paper a model is built that does not call upon an arc. The medium is best described as an electrically conducting slurry, a mixture of liquids, solids and gas. There are two sources of propulsion, the Lorentz force within the conducting part and buoyancy generated by CO bubbles, creating two opposed poloidal circulation loops, downward below the electrode axis and upward further out.

Jan 1, 2014

By Fernando Hernández Polanco

Transportation and handling metals and alloys from mills to consumption factories as well as dosing in conventional processes with ingots and scrap has always been considered a complicated activity with high operating costs. Several manufacturers of ferroalloys willing to solve these problems have chosen an alternative for their products that can be used to secure, during transport and dosage in the processes to making special steels, with more efficient consumption of ferroalloys. The trend for the production and sale of ferroalloys is to provide the product in the form of granules packed in bags or in bulk. In this paper we will show you how the granulation process was developed and rapidly adopted the ferroalloys industry as an effective solution to reduce operating costs, create cleaner and safer working environments.

Oct 30, 2017

By F. T. Davis

Many contributors have added to the fund of knowledge in the basic sciences related to mineral dressing during the past year. During 1964, the French edition of the Proceedings of the VIth International Mineral Processing Congress together with discussions was printed. Also, complete Preprints of papers delivered at the VIIth IMPC were published in September1. Over a third of the papers presented at VIIth IMPC dealt with fundamentals. COMMINUTION It has been postulated by Ponceleta that flaws need not exist before a stress is applied but rather the flaws are created at the tip of a propagating crack at a stress well below the theoretical breaking stress.

Jan 2, 1965

By G J. Halstead, R C. Steinhaus

The True Pipe® in-line sampler was developed in an attempt to address the need for a mechanically reliable and correctly designed sampler to suit one-dimensional pressurised slurry pipelines, often found in metallurgical process plants but for which no reliable and representative sampling solution as yet exists.The design, whose operation is based on the principle of symmetry, is described by Dominique François-Bongarçon (2005) with the synchronous opening and closing of relevant valves. It representatively isolates portions of the particulate material stream at predetermined intervals for effective extraction of primary increments for subsequent sample compositing.Theory of Sampling applicable solutions have proven elusive in flowing pressurised particulate material streams, with various attempts to date not having formulated a viable, mechanically reliable and acceptable design.Compliance to sampling theory is critical, and a number of tests were conducted where certain operating parameters were altered to determine their influence and sensitivity on sampling representativeness.The results of the initial series of tests performed on a carefully designed rig are presented, with additional work discussed for necessary investigation in the near future.Getting closer to a robust, economic and correct design for this challenging application in the minerals industry may now not be that far away. Plant management staff will see improved metallurgical mineral balances around their process plants and significantly reduced sampling discrepancies, particularly in tailings applications. Improved quality control is now possible where, due to plant head room constraints, classical cross stream sampling methods cannot be employed.CITATION:Steinhaus, R C and Halstead, G J, 2014. True pipe sampler – a correct design utilising the principle of symmetry in pressurised slurry particulate streams, in Proceedings Sampling 2014 , pp 127–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By Enrico Cerilli, Bryan Salt

Xstrata Nickel’s Sudbury Smelter has systematically developed its converting aisle from a single stage to a counter current multi stage converting process. This has required the development of two unique converters; the Slag Cleaning Vessel (SCV) and the Slag Make Converter (SMC). This has resulted in a unique three stage converting process that enables treatment of secondary materials and producing a slag that can be discharged without further treatment. The paper will also discuss future changes currently being considered to further improve environmental, plant hygiene and productivity performance.

Jan 1, 2009

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By Willard L. Hunter

A series of steel heats, one low-alloy and nine carbon, was made by the Bureau of Mines in a 1-ton arc furnace from ferrous scrap from incinerated refuse, steel cans, and detinned steel cans, both alone and blended with heavy-melting scrap. Two additional control heats, one of carbon steel and one of low-alloy steel, were made from electric furnace heavy-melting scrap to pro-vide comparative data. The steel products were cast into two 4-by 4-inch nominal 50-pound ingots; in most heats, an 8-by 8-inch nominal 7S0-pound ingot was also obtained. Tests of these ingots indicated that reinforcing bars of acceptable quality can be made from urban refuse components such as steel cans.

Jan 1, 1976

By Irving Hartmann, H. P. Greenwald

READERS of this journal are familiar with the danger of coal-dust explosions in mines and with recommended means for preventing them. The subject was treated in a paper by R. R. Sayers in the January 1943 issue, as well as in several previous articles. Similarly the danger of dust explosions is generally recognized in the handling of grain dust, flour, starch, sugar, and other carbonaceous products. However, until recently, few people realized that an analogous, real explosion hazard exists wherever dust suspensions of certain finely divided metal powders are formed. This lack of knowledge was in part due to the fact that until a few years ago only a small number of metal powders, such as aluminum, magnesium, zinc, iron, and tungsten, were produced, in comparatively small volume, and partly because information on the explosibility of metal powders was lacking.

Jan 1, 1945

By William H. Langer

I spent 41 years as a geologist with the US Geological Survey (USGS) conducting geologic studies and preparing peer reviewed maps and reports describing the results of those studies. Since retiring from the USGS in 2011, I have been a consultant specializing in aggregates and other industrial minerals. Consequently, I have had the opportunity and pleasure to apply the information contained in those kinds of geologic maps and reports to real-life situations. About half of my consulting is performing due diligence for mineral resource evaluations of one type or another where resource information has been provided by the property owner. Many of those jobs necessitate that I conduct desktop studies followed by field work. I then use my information to review and comment on the written reports of others; reports variably referred to as geologic reports, resource studies, reserve analyses, and so forth. While there are many well written reports addressing geologic resource issues, I was surprised to see that there are also a significant number of so-called geologic reports that only pay cursory attention to geology. Unfortunately, that lack of rigorous geologic investigation commonly leads to erroneous conclusions. This paper addresses three such reports covering concrete sand, metallurgical gravel, and proppants (frac sand). Although all three examples are located in the Gulf Coastal Plain Province, I do not reveal the exact location of any of the properties for purposes of confidentiality. Furthermore, I have generalized the site descriptions and illustrations. However, all the descriptions faithfully define the geologic situation.

Feb 1, 2024

By D Connelly

Quartz deposits are common in nature but the presence of quartz suitable for yielding high purity quartz is exceedingly rare. This paper describes a test work study on producing high purity quartz (HPQ) product to meet the tight product specifications of greater than 99.97per cent, including four and even five nines, for uses including, lighting and fibre optics and modern-day high efficiency solar panels. Due to demand in renewable energy applications the market for high purity silica solar panels known for their increasing efficiency and durability is rapidly growing. Demand continues to rise for the use of high purity quartz in semiconductors, electronics, imaging and sensor markets. Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon to obtain the desired transport of electrical charge and control of the current. The production of silicon metal from high purity quartz has been designated a Strategic Mineral by the European Commission and by the US Department of Justice due to the growing significance of this metal in various industries. The subsequent processing of quartz is the key step to adding value and aiding technological advances. Overall, the high purity quartz market is a highly secretive, specialised market with increasing opportunities for stakeholders. The attempt to produce HPQ in this work was carried out using an Australian quartz ore following a typical HPQ process flow sheet. The unit processes included primary crushing, scrubbing, magnetic separation, flotation, acid leaching followed by hot chlorination. The results indicate that grinding of quartz requires specialist equipment due to the hardness and extreme abrasiveness of the ore leading to additional iron contamination in the ground ore. The critical impurities were aluminium, iron, sodium, potassium, lithium, titanium, zircon, calcium and magnesium. The chemical refining was found effective. The hot chlorination process needed to be done at 1200°C in a chlorine – hydrogen chloride gas atmosphere. The risk of any gas being released during this stage is very serious and only specialist companies should and can carry out this step. More recent studies reported many new options that appear to facilitate the production of HPQ with the requisite purities more easily, but costly equipment along with highly trained operators are required and hence unlikely to become available in standard metallurgical laboratories any time soon.

Sep 1, 2024

By D. G. Minnes

Many non-metallic minerals and structural materials are produced in Ontario to serve the needs of domestic manufacturers and export markets. In 1982 production was estimated to have a value of $765 million. Approximately 81 per cent of this was represented by structural materials, nearly 12.8 per cent by salt, and the remainder was other industrial minerals. Total mineral production in Ontario in 1982 was estimated at $3 .16 billion, down nearly $1.5 billion from 1980's high of $4.58 billion.

Jan 1, 1984

By J. W. Perez

Raw coal will often break intragranularly in either a completely random way or in a differential mode where one species will have a different rate of breakage than another. Locked coal-ash and coal-pyrite particles can also break by the preferential detachment of one species from another along zones of inherent weakness in locked particle assemblages. The mode. cf breakage is largely a function of the nature of the feed, but it is also influenced by the comminution device and the operating variables. Evidence of breakage of particles in the various modes is seen in the crushing of raw coal and middlings particles with a rotary beaker, jaw crusher, rolls, hammer mill and rod mill. Evidence from the literature indicates the detachment mode is often important for coal, ores and metallurgical products. Further confirmation comes from the crushing of a specially prepared 'ore' of sized magnetite in plaster of Paris.

Jan 1, 1988