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By George C. Bravner

WITH the great expansion currently being made in the aluminum output of the United States, not only by the company that has heretofore been the sole producer but by a now organization in the field it is only natural to wonder to what degree the; ore reserves of the United States can contribute to the growing consumption. For the three-year period 1937-'39 the U.S. Bureau of Mine's figures indicate that the annual domestic production of bauxite averaged about 370,000 long tons, compared with average, annual import of about 194,000 long tons. About 85 per cent of the imports came from Surinam, nearly all of which went into aluminum manufacture. Not all of the or -kipped from mines in the United States is used to make alumimun however as Bureau figures indicate that in these three years an average of only 48 per cent of the domestic ore shipment were so used the abrasive chemical and other industries taking respectively 27, 21, and 4 per cent of the output. The recent increase in the demand for bauxite has been of course in it use for aluminum manufacture. This as is well known is largely attributable to the world race for supremacy in

Jan 1, 1941

By Jacolien P. Wyethe

Zincor uses a Roast-Leach-Electrowinning circuit to process zinc sulphide concentrates. It also processes zinc oxide fume, originating from a slag smelting operation in the Democratic Republic of the Congo (DRC). Zincor achieved an average zinc recovery of 90.3% during the period January 2006 to May 2007. The bulk of the losses occurred in the iron and lead silver residues, both as soluble and un-dissolved losses. The un-dissolved losses in the iron residue constituted around 33% of the total zinc lost from the circuit, and were largely attributed to the presence of zinc-ferrite in the calcine used for neutralization during iron removal. As part of Zincor?s continuous improvement programme, the un-dissolved zinc losses in the iron residue were targeted by: the partial replacement of calcine with zinc oxide fume (from the DRC); and the preferential use of ?low-ferrite content calcine? as neutralizing agents in the iron removal circuit. These initiatives, coupled with other operational factors, resulted in a marked improvement in recovery to 92.6% during June to December 2007. The zinc oxide fume, directly fed to the circuit, required investigation of the halide rejection capacity of the Zincor circuit. Rejection of chloride via the magnesium bleed operation was considered adequate. Fluoride was mainly rejected via the iron (~70%) and lead silver (~27%) residues. Fluoride rejection via the lead silver residue varied significantly, probably as a result of variations in the sparingly soluble CaF2 content in the feed. The mechanism for fluoride rejection in the iron residues is uncertain. The fluoride rejection capacity of the Zincor iron residue (comprising of mainly jarosites, schwertmannite and ferrihydrite) at 2 ? 4 mg/L F in solution, was estimated at 0.14 ? 0.19 kgF/tFe residue.

Jan 1, 2008

By R. Tamir

This paper will describe the benefits of utilizing the decision support system, DSS to support the methodology of structured decision-making in the mining environment. It will outline the layers of the mining related decision making – 1. Creation of “one truth” situational awareness utilizing 2. existing planning, ERP, operational and monitoring agents, a. Expressing plan verse performance across mining phases and functions compared with the actual and trends to evaluate performance. b. Creating alternate courses of action and the implications up and downstream. 3. It will review the current condition were although a multitude of technologies resolve multi variable issues they do not interact in a way that assists decision makers throughout the organization in making high-quality decisions that will push the overall performance envelope. 4. The paper will show the benefits of integrating military methodologies to resolve multi variable complexed issues (operational, financial and other), operating in changing environments in order to meet time sensitive objectives with restricted resources. This is achieved by creating a shared situational awareness thru incorporating information from a multitude of data generating agents, creating COA, selecting the appropriate and turning it into a plan. The paper will discuss the implementation and suggest a path.

Feb 1, 2023

By R. E. MacDougall

Very few mineral properties spend their entire lifespans from discovery to depletion in the hands of one owner. More likely, properties will have several owners, and partial interests may change quite often. Similarly, mineral companies are bought and sold with frequency, in recent years at what appears to be an accelerating rate. The reasons for selling a property can be manifold -need for additional capital in other parts of the business, need for development capital, realization of a large gain at a perceived high point in the market, pessimistic commodity outlook, retirement of principals, or resolution of estate problems. Regardless of the reasons for a sale, there are specific steps that logically follow. Spruce up the business, package the information, market the property, negotiate the terms, close the sale, and make sure it stays sold. Adherence to certain very basic ground rules in property sales can maximize the profits and minimize the effort.

Jan 1, 1990

By Donald R. Sadoway

The viability of treating certain forms of hazardous waste by direct electrolysis in molten oxides is under investigation. Secondary residue or waste mud produced in the course of chromate chemical production is the focus of attention in this study. The goal is to reduce the water soluble hexavalent chromium either to insoluble trivalent chromium or to chromium metal. Electrolysis tests have been conducted in a high temperature cell containing chromate sludge dissolved in an electrolyte composed of Al2O3, SiO2, CaO, and MgO. Oxygen production on a carbon-free anode has been confirmed.

Jan 1, 1992

By D. DePaoli, P. Zhang

"Phosphate ore is one of the most significant secondary resources for rare earth elements (REEs), and Florida phosphate is of particular interest due to its much higher ratio of heavy REEs, especially yttrium. Analyses of numerous samples from different phosphate processing streams in Florida showed that heavy REEs account for about 50% of the total REEs in Florida phosphate with yttrium accounting for approximately 30%. It was estimated that the amount of yttrium from US phosphate processing could meet the world demand for this critical element. This research aimed at recovering both REEs and phosphorus from a phosphate flotation tails. This tails is composed of mainly silica and phosphate with a small fraction of heavy minerals including monazite and xenotime. Since the specific gravity of silica is 2.6 versus 3.2 for phosphate and 4.5-5 for rare earth minerals, pre-concentration of the minerals of interest by gravity separation was investigated first. A pilot scale shaking table was used in this study. One pass gravity concentration achieved a shaking table concentrate analyzing over 600 ppm REEs at about 40% recovery. Flotation of the shaking table concentrate resulted in a product containing 1809 ppm REEs and 26.37% P2O5 with corresponding recoveries of 73% and 82%. Sulfuric acid leaching at 75oC could recover over 60% REE and nearly all the P2O5. Higher REEs (>90%) recovery was achieved by conducting leaching at higher temperature with concentrated sulfuric acid. The phosphoric acid from leaching of the flotation concentrate is of superior quality compared with that generated from regular phosphate rock.INTRODUCTION Rare earths are a group of 17 elements including those of the lanthanum series, as well as the non-lanthanides, yttrium and scandium. These elements have very specific critical uses in a multitude of markets. For example, lanthanum is used as a catalyst in breaking down crude oil to produce gasoline, diesel and jet fuel and neodymium is the core magnetic component in high-strength magnets for electric car batteries, wind turbines and hard disk drives. Rare earths are also essential for many military applications. Many of these applications have no substitute materials and the move to green technologies has dramatically increased their demand."

Jan 1, 2018

By Sönke Schmachtel

Several possible physico-chemical properties of composite electrodes for oxygen evolution are presented to describe experimental data for which a mathematical model had been developed. On this basis, local electrical and electrochemical properties of a composite electrode were investigated with conductive atomic force microscopy (CAFM) and scanning electrochemical microscopy (SECM). It could be shown by CAFM measurement that the boundary between matrix and catalyst particles seemed to have special advantageous electrical properties. The SECM measurements showed the presence of mass transport phenomena with increased surface concentrations, whilst the thickness of the Nernst diffusion layer was very small. An intermediate was detected and assigned to be hydrogen peroxide. From all species involved in the oxygen evolution reaction (H2O2, H+ and O2), it was concluded that local active spots exist on the electrode on which hydrogen peroxide reacts to oxygen and protons. A two?step two-material process was suggested to explain the whole oxygen evolution mechanism.

Jan 1, 2008

By R. A. Wyman

A comparison of the amount of minus-28-mesh product produced by a standard grinding test procedure is provided for 45 non-metallic materials. The percentage of product, the weight of product per unit of energy used and the weight of product per mill revolution are shown. The results exhibited excellent reproducibility and demonstrated an accurate comparison of grindability for non-metallic materials.

Jan 1, 1977

By Tom Snyder, John Brulia

"The U. S. commercial explosives industry annually transports thousands of tons of hazardous materials (HM) in the form of explosives, oxidizers, and combustible liquids by highway in truck-tractor/trailer combinations and straight trucks, including pickups. Managing risk during transportation is every commercial explosives industry motor carrier’s number one job."

Jan 1, 2014

By Y. Qi

A cell-level nonlinear dynamic model of solid oxide fuel cell (SOFC) based on physical diffusion principles is built in this note. It demonstrates that reactant diffusion processes from gas flow bulks to triple phase boundaries (tpbs) play an important role in the dynamic behaviors of SOFC. The simulation shows that under certain condition, the effect of the double layer capacitance may be neglected. The phenomenon of slow rise of voltage in current interrupt experiment may be explained by the dynamic behaviors of partial pressures in the vicinity immediately above tpbs.

Jan 1, 2005

By A. W. Ambrose

"Introduction.Oil-field operations have often been carried on under great stress and haste, in which the prime purpose has been to put the wells down rapidly as possible, without regard to a few of the various factors affecting cost. In such fields as Burkurnett, Texas, where the well locations are town lots and other small tracts, the operator was concerned primarily with in drilling. In such cases a few thousand dollars more or less in the cost of a well not considered. We are reaching a time, however, when our reserves a,more definitely outlined and properties are being along more economic lines. Operators are becoming more concerned with the actual cost of this work, and are gradually learning that fuel consumption can be reduced in drilling and producing without delaying the speed of drilling, and in the case of production, it will greatly reduce the unit cost per barrel of production.Types of Field Boilers.In the oil fields there are in general two types of boilers; those which are used for drilling wells and are of a more or less portable character, and those established later in a more permanent form and serve for the purpose,of generating steam for producing the oil. As a rule, the latter type of boilers are larger than those of the drilling type. Usually, little care is given to the installation of drilling boilers; particularly in attempting to set them up in such a way as to avoid waste in of fuel. Because of the temporary nature of these installations there may be some justification for not giving them more,attention in this resend, but it is believed that a few precautions could be taken that would amply repay the cost and trouble taken. In connection with the boiler plants that are afterwards established, when a few producing wells have been,brought in with a life of two to ten years and probably longer, much care to the boiler-plant construction and to the installation of recording instruments which will assist in operating the plant at minimum cost."

Nov 1, 1920

By Wenjun Ju, Xiaodong Sun, Jianwei Zheng, Bingding Yi, Zhaorui Ma, Pengfei Jiang, Lingfu Zhu, Yangfa Zheng

The presence of hard roof poses a significant threat to the safety of underground coal mining. In this study, a mechanical model is established for underground stopes to analyze the overburden structure with the advancing of the mining face. It is indicated that the load-bearing arch structure (LBAS) is formed above the stope for roofs with regular hardness, whereas the reversed-basin bearing structure (RBBS) is formed for hard roofs. Compared with the LBAS, the RBBS can induce an additional pressure at the foot of the bearing structure, and this effect becomes less as the distance between the hard roof and stope increases. The ultra-deep borehole hydro-fracturing technique (UHT) is proposed to weaken the hard roof for pressure release, and the associated equipment and procedures are also presented. The UHT is based on horizontal drilling along the axial direction of the roadway in the roof, and then the receding segmented hydraulic fracturing technique is used to achieve the purpose of fracturing (weakening) of the surrounding rocks. Field tests are carried out in 3022 roadway of Daliangwan coal mine in Yulin to assess the developed technique, equipment, and fracturing procedures. To evaluate the fracturing effect, deep borehole stress-meters are installed at different depths of the fractured and un-fractured zones of the roadway, along with hydraulic support pressure sensors placed at the mining face. The results show that compared with the un-fractured zone, the pressure on the wall and pillar sides is lower than that in the fractured zone, and the associated weighting duration and weighting area ratio of the fractured are reduced by 53.23% and 33.59%, respectively. This indicates that the presented UHT can provide a new solution for the prevention and control of mining disasters induced by hard roof failures in underground coal mining.

Nov 2, 2020

By Sudarshan Martins, Peter Radziszewski

"Tumbling mills are machine, operating in non-equilibrium, capable of applying forces on the ore contained within, causing the ore to break down. The action of the mill on the ore is very inefficient, producing a large quantity of heat. The inefficiencies of the mill drive the desire for improvement, spawning research and development activities. Given the non-equilibrium nature of the mill, the theory of Large Deviations is proposed as the framework that captures the state of the mill. The theory of Large Deviations allows for the determination of the rate function and the scaled cumulant generating function (SCGF), for systems in either equilibrium or non-equilibrium. Powerful connections can been made between familiar concepts of statistical physics and the concepts introduced by the theory of Large Deviations: entropy can be associated with the rate function; the scaled cumulant generating function with the free energy. It is shown that observables, compatible with Large Deviation theory, can be identified for the tumbling mill. Here, the time series of the energy associated with an element of the charge is such an observable. Furthermore, using some experimental data, it is shown that the time series of the energy can define a rate function, thereby describing the system within the Large Deviation framework. Finally, a discussion of the results is given, particularly how this theory can be further developed for tumbling mills."

Jan 1, 2014

By Shengqin Zhang, Jagannath Pal, Yousef Mohassab, Hong Yong Sohn, Mohamed Elzohiery

The kinetics of magnetite reduction with mixtures of hydrogen and CO of various compositions has been investigated as part of the development of a flash ironmaking process at the University of Utah. This new process bypasses the cokemaking and pelletization or sintering steps required for the blast furnace. The particle kinetics were studied using magnetite concentrate particles of different sizes. Reduction degree of 60% was achieved in a few seconds in at 1350 oC using CO reductant alone and over 90% when H2 + CO gas mixture was used. The effects of reductant partial pressures, temperature, and particle size on the reduction kinetics were studied.

Jan 1, 2016

By Marc. A. Meyers

The analysis of the phenomena involved in the determination of the compressive strength of iron-ore agglomerates leads to the identification of the important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compression axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments is due to internal voids of varying sizes, that act as stress-concentration sites. Two novel testing procedures are proposed. The first consists of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents significant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1981

By Hermann Schmalzried, Carl Wagner

UPON heating a metal oxide or sulfide in H2, first only oxygen or sulfur is removed from the surface. Thus the metal/nonmetal ratio in the oxide or sulfide increases and the thermodynamic activity of the metal increases accordingly. For the formation of metallic nuclei, a certain super saturation is necessary, i.e., the activity of the metal must become greater than unity. Once nuclei of the metal have been formed, the supersaturation is supposed to decrease. Even under steady-state conditions of a reduction process, however, the activity of the metal inside an oxide or sulfide phase must be greater than unity in order to have a driving force for the individual steps of the reduction process. As an example, consider the reduction of Ag2S with a high mobility of cations and electrons. As shown schematically in Fig. 1, the reduction process involves the following steps:' 1) sulfur removal along the entire Ag2S surface in form of H2S, 2) migration of Ag' ions and electrons from the Ag2S surface to nuclei of metallic silver, 3) transfer of Ag+ ions and electrons from the Ag2S phase to the metal. For a finite rate of step 3, the activity of silver in Ag2S next to the Ag2S-Ag interface must be greater than unity. Moreover, for a finite rate of step 2, the activity of silver at the gas-Ag2S interface must be still somewhat greater. Theoretical considerations lead to the tentative conclusion that at least under steady-state conditions the supersaturation will be rather low.' To test this conclusion, the average activity aAg of silver in a Ag2S tablet about 2 mm thick with a diameter of 5 mm was followed as a function of time by measuring the electromotive force E of the cell Pt I Ag | Agl I Ag2S I Pt where AgI is used as a solid electrolyte in which only Ag+ ions are mobile. The activity aAg is calculated as aAg=exp(-EF/RT) Since the diffusion coefficient for transport of silver in Ag2S is very high (- 3 . l0-2 sq cm per sec),3 the average activity aAg is representative for both the bulk and the surface of the Ag2S tablet. Experiments were conducted at about 400°C. The cell was surrounded by an aluminum block in order to secure a uniform temperature and to eliminate thermoelectric effects. With the help of a potentiometer, first a potential of 0.16 v was applied to the above cell in argon in order to obtain a well defined initial state with a Ag/S ratio close to 2.000.~ Then the cell was disconnected from the potentiometer and a gentle stream of H2 was passed along the Ag2S surface. In view of the removal of sulfur in form of H2S, the electromotive force E decreased within 20 to 30 min to zero corresponding to a Ag/S ratio of 2.003 and became negative, indicating a value of aAg> 1. A representative plot electromotive force E vs time is shown in Fig. 2. The minimum of the electromotive force characteristic of the onset of

Jan 1, 1963

By E. C. Weichel

THERE have been many attempts at permanent roof support in anthracite mines, in some cases brick arches, in others concrete, and also combinations of brick or concrete walls with steel beams. These supposedly permanent roof supports have frequently failed when heavy pressure is brought to bear upon the structure, because they are so rigid that failure occurs because the structure is unable to adjust itself to the increased load. Roof pressure exerts a tremendous weight, and it is at times difficult to find any means of support which is strong enough to bear the entire pressure, unless this supporting structure has in itself the element of some flexibility which will enable the structure to hold the moving mass until it "arches" itself. If the supporting medium has flexibility enough so that it can adjust itself to the heavy initial loads, and so give the overlying material an opportunity to form a self-supporting arch, then such a roof support will be more useful than any rigid roof support. There has recently been introduced into the anthracite region a new form of gangway lining that is flexible enough to slightly adjust itself under heavy pressures, and so give the loosened material which is being supported a chance to form into an "arched" mass. This lining, manufactured under patents granted to Hans Schaefer of Essen, Germany, was introduced in the United States in the summer of 1928, at which time the Amercan licensee, Richard Howells of

Jan 1, 1930

By Yazen Khasawneh, Yao Zhang

Upgrading and maintenance programs were proposed at a power generating plant in Indiana. To perform construction activities associated with the proposed upgrading and maintenance, a LR11350 crawler crane with a dead load of 1,500 ton was required in the vicinity of existing plant structures. The contact pressure from the crane tracks for the heaviest lift, maximum reach and angle (worst loading condition) were estimated by the rigging engineer to be on the order of 84 psi. Several concerns were raised regarding the total and differential settlements while the crane is in operation and the induced stresses on existing underground utilities due to crane loads. Three-dimensional finite element simulations were conducted using hardening soil model for the subsurface soils and elastic model for the other structural elements (underground utilities and crane mats) to optimize the configuration of the proposed crane foundation. It was found 1-foot thick engineered steel mats underlain by a 1.5-foot thick crushed stone pad will provide enough support to the crane. It will also control the settlement to the allowable limit and maintain the stresses in the underground utilities within tolerance. INTRODUCTION A LR11350 heavy lift crawler crane was proposed as part of an upgrade program at an existing power plant in the state of Indiana. The proposed crane will be sitting on an open ground in the vicinity of existing plant facilities, with multiple underground utilities going beneath the proposed footprint of the new crane pad. The existing utilities are of diverse kinds, including sanitary sewer corrugated metal pipes, electrical conduits and variable steel water/oil drain pipes. The safety and functionality of these underground utilities are critical to maintain the proper operation of the power plant. Therefore, the design of the new crane pad foundation system is of essential to control the ground settlement and the imposed stresses to the existing utilities (Davie et al., 1998, Scott 2017). To ensure all utility locations and depths are identified, the proposed footprint was thoroughly surveyed. Information in regard to each identified utility was provided by the owner. Subsurface explorations were conducted using geotechnical soil borings and soundings to evaluate the ground conditions and generate soil profiles. Numerical simulation and analysis utilizing finite element method were performed to design the crane pad foundation system and evaluate the responses of the utilities. This paper summarizes project information, geotechnical conditions and then focuses on the finite element analysis in assisting the design of crane pad and the utilities evaluation.

Jan 1, 2019

By Shadia J. Ikhmayies

"Cadmium sulfide thin films were prepared on glass substrates by the spray pyrolysis technique at a substrate temperature of 490°C. Some of the films were etched by HC1 in distilled water, others were heat treated in nitrogen atmosphere, and another set of films was first etched by HC1 and then annealed. Room temperature impedance spectroscopy measurements on the films were performed using coplanar geometry in the dark and in room light in the frequency range 20 Hz to 1 MHz. The experimental data were represented by complex plane diagrams and showed one well-defined semicircle in the high frequency region. Hence the equivalent circuit that models the CdS: In thin films was found to be a single RC circuit, which indicates the bulk conduction through the grains. The influence of treatments on the electrical properties was investigated.IntroductionCadmium sulfide (CdS) is a brilliant II—VI semiconductor material with a direct band gap of 2.42 eV at room temperature. It has many outstanding physical and chemical properties, which have promising applications in multiple technical fields including photochemical catalysis, gas sensor, detectors for laser and infrared, solar cells, nonlinear optical materials, various luminescence devices, optoelectronic devices and so on [1]. There are different methods to prepare undoped and doped CdS films, such as rf sputtering [2] chemical bath deposition (CBD) [3], pulsed laser deposition (PLD) [4], and spray pyrolysis (SP) [5-11]. Of these methods, spray pyrolysis represents the less expensive option, and can produce large area high-quality low cost thin films [12]."

Jan 1, 2012

By J. O. Guthrie

Newmont has delineated a 600,000+ ounce gold reserve in the Cargo Muchacho Mountains. This is a desert range underlain by Proterozoic(?) Tumco Formation (gneiss) intruded by Jurassic granitic plutons, and cut by low angle shears of the late Cretaceous Chocolate Mountain Thrust event. Gold, associated with pyrite, quartz veinlets, and propylitic alteration, is emplaced along low angle shears. The mineralizing system, enriched in tungsten, copper, zinc and arsenic, was active during Eocene time. Gold reserves are found in eleven areas as moderate to high tenor deposits that may be mined by open pit and underground techniques. Eastmaque Gold Mines Ltd. is developing the deposit.

Jan 1, 1987