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By S. Seetharaman

A mathematical model has been developed to evaluate the viscosities of melts at high temperatures. The viscous flow in liquid is described by the equation, {n = Aexp(AG*/RT)} based on the absolute reaction rate theory. The Gibbs energy of activation,{ AG* } is considered to be a function of the temperature as well as the composition of the melt. The model has been applied successfully to various metallic and slag systems from unary to quaternary. On the basis of this model, a relationship has been suggested to relate the Gibbs activation energy of viscosity to the Gibbs energy of mixing in binary metallic melts. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the reported experimental values.

Jan 1, 1994

By J. Roger Loebenstein

This report presents a U.S. Bureau of Mines study of the flow of arsenic-containing materials in the United States, based on the best data available in 1991, includes a consideration of arsenic as a byproduct of the processing of nonferrous metals, the fate of arsenic in manufacturing wastes, the quantity of arsenic used in products, tile fate of arsenic in dissipative uses, and the useful life of discarded products. Where possible, estimates are given of the amounts of arsenic lost from the materials flow. Arsenic byproduct of mining nonferrous metals. Historically, most U.S. production has been from the states of Montana, Washington, and Utah. The smelters in these states are believed to be the areas of the country where arsenic is most concentrated in the soil, tailings ponds, and waste dumps. Since the closure of the last domestic producer of arsenic in 1985, all arsenic has been derived from imported sources. Historically, arsenic was important in agricultural applications as an insecticide, herbicide, and cotton desiccant. As the environmental movement gained momentum and the toxicity of arsenic became better understood, most of the agricultural uses for arsenic were banned. Beginning about 1975, the use of arsenic as a wood preservative began to grow. After 1980, wood preservative uses became more important than agricultural applications. By 1990, 70% of the arsenic consumed in the United States was used by the wood preservative industry and 20% by the agricultural industry. The major source of domestic arsenic emissions in 1989 was from the U.S. copper processing indus¬try. About 7,800 mt/yr of arsenic was discarded in leach dumps, tailings, and slag. Another 800 mt/yr was liberated to the atmosphere and 1/100 mt/yr was exported in copper concentrates. On the consumption side, 9,200 mt/yr was lost, mostly from dissipative agricultural uses and the disposal of obsolete arsenical products.

Jan 1, 1994

By John H. Raymer

Groundwater inflow into hard rock tunnels is strongly affected by recharge and drawdown of the water table. Previous analytical and empirical methods for estimating inflow have generally not accounted for these factors in an accurate or systematic way, resulting is wrong conclusions about inflow and the effects of the tunnel on the surrounding environment. This paper discusses these issues and provides some simple analytical equations to estimate inflow and water table drawdown around the tunnel. Examples from tunnels in the Atlanta area are provided.

Jan 1, 2005

By Sara Hornby

After almost half a century of experience in using DRI/HBI in electric arc furnaces (EAFs), and taking into account the decrease of natural gas cost in the USA, it is interesting to revisit some trends and controversial issues around this alternative iron source. This paper reviews aspects like the evolution of iron ore quality and its influence on EAF operation; DRI stockpiling and transport, regarding the risk for selfcombustion; optimum charge design; cold DRI/HBI charging (fifth hole, bucket, transporter); hot charging (ways and results); carbon content, metallization and silica in DRI/HBI, and its influence on EAF operation and performance; oxygen / carbon balance; chemical energy and DRI/HBI charge.

Aug 16, 2017

By R. Winand, P. Harlet

he cathodes produced are of electrorefined grade; metallographic structure and surface roughness are controlled to a depth of 1.3 cm (single-side deposits); silver levels in the cathode are regulated by the presence in solution of Cl- and Br- ions; organics must be used at very low concentrations (around 0.1 mg/l with a consumption of about 0.01 mg/l/hr). The required concentrations of additives were established according to a well-defined strategy based on the consumption of organics at the cathode by a mass transfer limited-process.

Jan 4, 1992

By Renpei Yoda

An investigation was conducted to develop columbium alloys with e1evated-temperature strengths higher than those exhibited by more common commercial columbium alloys, and attention was given to improving the oxidation resistance and ease of fabrication. Additions of carbon, aluminum, and chromium were made to some columbium-base alloys, and their effects on workability, recrystallization, oxidation resistance, and mechanical properties at elevated temperatures were explored. The additions were made to take advantage of (1) solid solution strengthening, and (2) precipitation hardening. Three alloys displayed good high-temperature properties with relatively good oxidation resistance at 1,000° C, and tensile strengths from 26,000 to 32,200 psi at 1,400° C. When the properties of these alloys were compared with those of commercial alloys, B-66 and FS-85 (1),4 the outcome was favor-able for the alloys studied in this investigation.

Jan 1, 1967

By Niels Verbaan, Ernesto Bourricaudy, Ronald Molnar, James Brown, Sunil Jayasekera

"SGS Minerals commissioned an internal R&D program to develop in-house expertise to design, set up and operate REE separation pilot campaigns at its Lakefield, Canada site. A team approach was used that included expert consultants in the field of REE separation as well as in-house expertise supported by the on-site Analytical Laboratories.A mini pilot scale SX circuit was designed and constructed consisting of several modular banks of 30 stages each. About 80 stages of mixer-settlers were used to separate Pr and Nd from La and Ce contained in a synthetic REE chloride stream simulating the raffinate from an initial La-Nd|Sm-Lu+Y separation.Two pilot campaigns were operated totalling 25 days of 24/7 operation with 99.4% plant availability in the final 20 day campaign. Purities of > 99.9% in the Pr-Nd strip liquor and > 99% in the La- Ce raffinate were achieved and simultaneously sustained in the second campaign for prolonged operating periods. Key to controlling and adjusting the circuit was the rapid assay turnaround (as low as 2 hours) provided by the on-site SGS analytical lab. This permitted the operating team to modify conditions and observe the effect of changes relatively quickly considering the large number of stages. A portable XRF analyser was also used to track evolving assay trends in the circuit. The small physical size of the circuit enabled longer operation with a limited amount of sample.This paper discusses the design of the circuit, operating conditions, some of the key operating factors and controls and results obtained.INTRODUCTIONSGS Minerals commissioned the design of and built a solvent extraction (SX) pilot plant for the separation of rare earth elements (REE). The plant consists of a battery of 120 mixer-settlers set up in a dedicated piloting facility.The purpose of the programme was to develop capabilities and in-house expertise in REE SX separation technology. The program aimed to establish operating procedures, sampling regimes, and analytical methodologies and protocols for this type of process/plant. A team comprised of SGS personnel and several external consultants with prior industrial and REE separation piloting experience was assembled to achieve these objectives."

Jan 1, 2016

By T. P. Meloy

In the last decade increased and prolonged interest has been displayed in the use: of tunneling or rapid excavation to solve many of the urban and industrial problems confronting our society. There has been talk and action on the interurban rapid transit systems for major cities, and even preliminary designs for a Boston to Washington interurban transit system. Much of this interest stems from the search to the solution of our increasingly complex urban problems, where the surface area must be given over more and more to the inhabitants, and the subsurface for transit, utility and other services. While tunneling is not a panacea to urban ills it holds a real solution to many existing problems. There is also, among the tunneling experts, a growing confidence that technical problems of rapid tunneling can be solved. To solve these problems, R & D money must be invested. If it is to be money invested either by private industry or governments, there must be significant returns on the investment to justify the research and development need to bring about the breakthrough that will make tunneling a major contribution to the solution of urban problems. To make these economic studies more extensive and more accurate tunneling demand figures were needed. To this end, the Organization of Economic Cooperation & Development - OCED - included in its Conference on Tunneling a section on tunneling demand. As a result of the conference the organization for Economic Cooperation and Development issued a report entitled "The Advisory Conference on Tunneling - Report on Tunneling Demand 1960-1980. " This report was presented at the OCED Conference on Rapid Excavation, held at Washington, D.C. To obtain the data in the Report, questionnaires were sent to the OCED countries and 18 replies were received from Australia, Austria, Belgium, Canada, Denmark, France, Germany, Ireland, Italy, Japan, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom, and the United States. While it is true, that data were missing, that sometimes the definitions were confused, and that several countries provided no cost estimates at all, in general, this report contains the most comprehensive gathering of data that ever existed in the field. All data in the OECD report is expressed in terms of meters or cubic meters, and costs are in U.S. dollars.

Jan 1, 1970

By Tim Lundquist

Disa Technologies Inc. provides innovative, sustainable solutions for mineral processing and remediation through its patented High-Pressure Slurry Ablation (HPSA) technology. HPSA processes solid feed material in slurry form, propelled by high pressure pumps through opposing nozzles that generate impinging jets within a collision housing. This process induces particle-to-particle collisions in a high energy zone, creating intergranular fractures along grain boundaries. In our batch scale and continuous operating testing, we have found that controlling key processing variables such as nozzle velocity, slurry solids percentage, and the number of passes can allow for controlled size reduction and maximum mineral liberation. Since 2018, Disa Technologies has demonstrated the versatility of HPSA by testing it on diverse materials, including phosphate, copper, uranium, vanadium, zinc, rare earth elements, lithium, nickel, mineral sands, gold tailings, and more. The intent of this paper is to present an overview of our test results describing in detail impacts on size reduction, recovery, and grade with a focus on HPSA's adaptability across ore types. Looking forward, it explores the potential to process materials such as DR-grade iron, clay, PGMs, bauxite, and various tailings. Additionally, it examines planned advancements in HPSA technology, including optimized nozzle spacing, higher capacity models, improved tonnage-to-footprint ratios, enhanced maintenance features, and expanded nozzle configurations.

Jan 1, 2025

By R. A. V. Raff

Although falls of roof, face and rib (or side) of coal mines were the third ranking cause of disabling accidents in 1966, the accidents from these falls resulted in the most serious injuries and accounted for approximately 50 percent of the total fatalities (I). Further breakdown of these statistics shows that 88 percent of the fatal accidents occurred within 100 feet of the working face and that 96 percent of the deaths were in bituminous mines, with only four percent taking place in anthracite workings. These figures demonstrated the need for improved reinforcement procedures in operational coal mines, and they provided ample justification for research in the area of accident prevention. The purpose of this project was to investigate the use of polymers and of related techniques to achieve rock bonding and reinforcement of coal mine structures, in order to obtain better or permanent ground support (e.g., drifts, entrees, coal and ore passes, galleries, tunnels and shafts) by the fill ing of fissures in the rock, thereby preventing or delaying the onset of serious rock degradation processes.

Jan 1, 1973

By J. N. Greaves

Investigations were conducted by the U.S. Bureau of Mines to develop flowsheets for the recovery of tungsten and gold from four Alaskan scheelite-bearing ores. Basic gravity concentration and cyanide leach tests were performed on all samples. About 46 pct of the tungsten and 30 pct of the gold from one sample were recovered in a gravity concentrate containing 24 pet W03 (tungstic oxide) and 119 troy ounces per short ton (tr oz/st) Au. Froth flotation of the gravity concentrate resulted in separate tungsten and gold products with grades of 38 pct W03 and 2,720 tr oz/st Au and recoveries of 60 and 97 pet, respectively. Additional gold was recovered from the gravity and flotation tailings by cyanidation. Overall recoveries of tungsten and gold from this sample were 28 and 94 pet, respeetively. A flowsheet with mill design parameters was developed that consisted of (1) free gold and scheelite recovery by gravity methods and froth flotation and (2) fme-grained gold recovery by cyanide leaching of reground gravity and flotation tailings, followed by a carbon-in-pulp (CIP) circuit. Data were developed from the Bond mill work index, gold and tungsten flotation, conventional and high-rate thickening, cyanide leaching, and CIP adsorption tests.

Jan 1, 1989

By Z. Smieszek, Z. Szota, P. Gajowski

"A new method for measuring the total quantity of suspensions contained in the electrolyte during copper electrorefining has been developed by the Institute of Non-Ferrous Metals, Gliwice. Electrolyte purity, and the suspensions content in particular, is of essential importance for the quality of electrolytic copper produced during the process. Suspensions contribute to the increase of slime impurities in electrolytic copper and increase losses in noble metals. Up to now, the laboratory method has been used for the· process control which provides analytical results with considerable time delay. Therefore, it is useless for the process control.The measuring method developed enables continuous measurements of a suspensions content directly within the stream of the flowing electrolyte. The principle of measurement is based on changes in optic properties of the electrolyte with varying suspensions content.1. IntroductionIn copper electrorefining, it is essential that the final product quality be maintained. If suspensions are present in electrolyte, the content of slime impurities in electrolytic copper, (such as Pb, Ag, Bi, Sn, Sb, and As), increases which can result in the occurrence of the so-called slime dendrites on cathodes, thus debasing the quality of the product. As a normal suspension content in electrolyte, the contents in the order of several mg/l are considered, usually not more than 5-6 mg/l, while contents exceeding 20 mg/l are referred to as an alarm state. Suspensions present in an electrolyte are usually a light fraction of anodic slime whose main components are metallic silver, lead sulphate, complexes of antimony and arsenic, and sometimes even calcium sulphate; they are mainly composed of very small particles of lead sulphate and antimony complexes. Sometimes - - in case of alarm states - - the so-called ""wandering slims"" can be observed, which are composed mainly of arsenic and antimony complexes. These ""wandering slims"" make a serious technological disturbance. In normal operating conditions of the electrorefining plant, an increase of suspension content can result from such reasons as crack of filter cloth in a slime filter, turbulent flow of the electrolyte, anodic passivation, aeration of the electrolyte, and improper servicing of an electrolytic tank. It is necessary to continuously control the suspensions content in electrolyte for proper electrorefining."

Jan 1, 1989

By R. St. C., G. E. Morris, M. Zbik, Smart

Effective flocculation and dewatering of slurry streams containing clays (particularly kaolin and smectites which are often <200nm in lateral dimension) is becoming increasingly urgent. Release of water (often >75 wt%), for recycle and reduced make-up water consumption, from slurries in tailings streams and dam beds is usually slow and incomplete. Changes in settling rates and solids density of tailings containing clays can be achieved in practice by changes in pH, dissolved cations and flocculant additions. To achieve fast separation of clays from water and minimization of retained water, individual particles need to be bound in the initial stages of thickening into large, high-density aggregates, which may sediment more rapidly with lower intra-aggregate water content. Quantitative STIMAN (STructural IMage ANalysis) cryo-SEM imaging, shows that the structure of aggregates formed before flocculant addition has a determinative effect on these outcomes. Without flocculant addition, 4 stages occur in the mechanism of primary dewatering of kaolinite: initially separate particles and aggregates are dispersed (<0.3GP, where GP is the gel point); a partially-gelled chain network then forms linking particles edge-edge (EE) still well below the OP but remains largely suspended; after an induction time, this network structure rearranges from EE to face-face (FF) contacts densifying, compacting and dewatering the aggregates with settling rates well above Stoke&apos;s Law estimates for >20µm particles or aggregates; the GP is rapidly reached during settling producing a network spanning the vessel with compressive strength. This sponge-like structure with EE oriented particles limits slurry dewatering because the steric effect in the resulting partially-gelled structure is much more dominant than the electrostatic effects predicted by DLVO theory. Van der Waal&apos;s forces at very close distances, as particles slide across each other, may be responsible for the EE to FF change in structure. In this way, the previously extended network contracts, and when the solid volume fraction is low, the continuous network breaks apart forming aggregates and aggregate associations as flocs which arc able to freely settle. These densified aggregates settle at increased rate, give lower bed density and retain less water after drainage. With flocculant addition, the internal structure and networking of the pre-aggregates is largely preserved but they are rapidly and effectively bound together by the bridging action of the flocculant(s). The STIMAN analysis shows that there is a inverse correlation of intra-aggregate porosity (and void permeability) with Darcian permeability (and extent of dewatering) whereas there is a strong positive correlation of Darcian inter-aggregate permeability with settling and primary dewatering rate.

Jan 1, 2004

By Franklin H. Persse

Domestic bismuth supply was projected from production figures for the ores in which it occurs--copper, lead, zinc, and tungsten. Published and unpublished data concerning host ores were examined to determine bismuth reserves and resources, and mine production. Potential recoverable bismuth occurring with reserves and resources of copper, lead, and zinc was estimated to be 36.3 million pounds. A bismuth availability diagram was developed from quantity estimates and ratios of production cost to value for these host ores. Additional recoverable bismuth occurring with domestic tungsten reserves was estimated to be 1.5 million pounds. Domestic byproduct production of bismuth will approximate 1.3 million pounds annually by 1980. This quantity will provide about 37 percent of the 3.5-million-pound estimated requirement for that year. Known world supply of bismuth appears to be sufficient for world demand to the end of this century. The study indicates that bismuth reserves and potential resources in the rest of the world have not been adequately reported.

Jan 1, 1970

By Graham John Mitchell

In May, 1919, a crosscut on the 1400-ft. level of the Briggs mine, a Calumet, & Arizona property at Bisbee, Ariz., penetrated a deposit of pyrite and chaleopyrite that had replaced quartzite and limestone and was cut, especially in the quartzite, by numerous fractures. As the drift advanced through these fractured portions, they were found to be free from copper-sulfate minerals although &apos;(sooty" chalcocite was present in the fractures and also as coatings and replacements of pyritc. Howcver, sulfate soon made its appearance in certain fractures, filled them, and began to form stalactites. Several centers of incipient growth were noted for subsequent study, observations in the drift at frequent intervals during the past 17 months affording the opportunity of determining the rate of formation of the stalactites. The one to attain the greatest growth during the period of observation measured 27 in. long and averaged 1 in. in diameter. A close study showed it to be composed of small interlocked crystals of chalcanthite radiating from a small central tube-like opening. The trielinic form of the crystals was evident with prism and pinacoid faces recognixable. Assuming that the supply of copper-sulfate solution was constant (luring the 17 months—-and such an assumption is supported by the fact that the number of drops of excess solution falling, per minute, from the tip of the stalactite at the times of observation checked closely—thc stalactite, it has been estimated, grew at the rate of 1.58+ in. per month. DISCUSSION James I?. Kemp," New Yolk City.—J. S. Curtiss, in the monogr:tpll on Eureka, Ncv., say:: that a stalactite formed in limestonc grew 5/8 in. in three weeks and continued to grow as long as it had a drop of water or solution at the lower end. Another grew at the rate of 3/8 in. in the same time. In the case cited by Mr. Mitchell, the growth was about 136 in. in three weeks. A year ago we had an instance of the formation of cubes of galena on a railroad spike. A mine in northeastern Oklahoma had been idle about two years but on account of pumping of neighboring properties, the circulation of water was active throughout the drift. A cube of galena,

Jan 1, 1922

By Cyril S., Smith

THE phenomenon of air-hardening is well known in connection with special steels. It occurs when the rate of decomposition of austenite to marten- site is so retarded that it takes place on free cooling in air rather than on more rapid cooling in a quenching bath. If an air-hardening steel is quenched sufficiently rapidly it will remain in the soft austenitic state, while if it is cooled very slowly it will again become soft owing to growth of the carbide particles. It depends on a critical adjustment of the decomposition velocity and diffusion rate, and such alloys are rather rare, especially in the non-ferrous field. In carrying out some experiments on some copper- rich copper-cobalt alloys, the author found that these possess very marked air-hardening properties. The alloys are covered by a patent issued to M. G. Corson (1,723,022-1919), which states that an alloy containing between 2 and 5 per cent cobalt is hardened by simple quenching from above 850° C.

Jan 1, 1930

The Bureau of Mines human factors research program is directed toward reducing accidents and improving the overall efficiency of the person-machine environment interface found in surface and underground mines. The focus of the hum factors program therefore, is to insure that sound knowledge is available concerning human capabilities and limitations, and that this knowledge is applied to the design, of mining equipment, work tasks, and management procedures. The papers presented in these proceedings summarize some of the recent Bureau research in hum factors. The papers focus on two broad areas, human resource issues and human engineering of equipment, tools, and work procedures found in mines.

Jan 1, 1987

By T J. Napier-Munn

This paper proceeds from the premise that process improvement is a key part of the mineral engineer’s role, and one in which he/she can make a significant contribution to shareholder value. It presents four tools to help with process improvement projects. Two are designed for process monitoring, to determine as soon as possible whether there has been a true change in performance: the cumulative sum (cusum) control chart plot with V-mask, and the control chart using a process model. The other two are used for process optimisation: simplex self-directing evolutionary operation (SSDEVOP), and a response surface model developed using a central composite rotatable experimental design (CCRD). These methods are robust, have a rigorous theoretical basis and are easy to implement. They also promote project continuity which increases the chances of success, particularly in fly-in/fly-out (FIFO) operations. Variants are used in other industries, but they are rarely if ever applied in mineral processing to-day for reasons which are unclear. The paper gives examples of the application of each method in concentrators which demonstrate that they have the potential to be useful additions to the mineral engineer’s professional toolbox.CITATION:Napier-Munn, T J, 2014. Cunning solutions to process improvement, in Proceedings 12th AusIMM Mill Operators’ Conference 2014, pp 5–10 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Goutam H. Shahani

The current economic downturn has been at the center of media attention for several years. Today, the mining and mineral sectors are being impacted by highly fluctuating supply-and-demand conditions, extreme price volatility and tremendous market uncertainty on a world-wide basis. There have been numerous plant closings, project cancellations and employee layoffs. In this gloomy economic environment, it is easy to forget that the world?s gross domestic product (GDP) has more than doubled in real terms during the last 30 years. While current market turbulence may continue for some time, the long-term trend is unmistakably upward. Living standards are rising all over the world, thereby creating demand for food, clothing, transportation and housing. This translates into tremendous demand for the mining and mineral sectors. In the future, new capacity and plant expansions will be necessary to meet this need. These investments, which typically have a life span of 30-plus years, will have to be based on long-term economic considerations rather than current market conditions.

Jan 1, 2011

By Philip D. Wilson

IT has been my privilege to read the article prepared by R. S. Dean entitled "Production of Alumina from Low-Grade Domestic Materials" which appears on another page of this issue. Dr. Dean should be congratulated on the preparation of such an erudite and scholarly dissertation on bauxite and on the work which the Bureau of Mines has been doing in connection with the development of processes to use low-grade domestic materials.

Jan 1, 1943