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By Yasuhiro Konishi

Hydrolytic stripping is the process in which metal ions are simultaneously stripped from a loaded cation-exchange solvent extractant and precipitated as oxides or hydroxides. Hydrolytic stripping is usually effected by contacting the loaded organic phase with water at elevated temperatures. The possibility of using hydrolytic stripping to prepare ceramic powders with controlled size and morphology is now being evaluated for different systems, using carboxylic acid extractants. As part of this work, mathematical models were developed to describe the kinetics of nucleation and growth of nickel ferrite particles. This paper describes the development of the models, along with estimation of key parameters appearing in the rate equations from experimental data.

Jan 1, 1990

By D. D. Dunkin

SANDSTONE has been prepared for glassmaking purposes, and marketed from the White River Valley in-Arkansas at Guion, Izard County, since about 1910-soon after the completion of the White River Branch of the Missouri Pacific R. R. Co. Until 1921, operations were somewhat spasmodic and ended in many failures. In that year a plant was built by the Silica Products Co., Inc., and since that time the operation has been continuous and steady. The land is held under leases, covering about 30 sq. mi. of the best sandstone adjacent to the railroad. Most of the product is shipped to glassmakers. GEOLOGY The St. Peter sandstone is rather widely distributed in north central Arkansas and- is exposed most prominently in outcrops along the slopes of the White River Valley and its tributaries that form the division between the Boston Mountains to the south and the Salem Plateau of the Ozarks to the north. It is of Ordovician age and is generally underlain by Cotter dolomite and capped by Plattin limestone, except in the vicinity of Bellefonte and Everton. At those places, it is a massive cross-bedded, laminated, saccharoidal sandstone; underlying it is the Everton limestone and overlying it, the Joachim magnesium limestone. The sandstone at Everton contains numerous phosphatic pebbles and inclusions of sandy limestone. The irregularity of cross-section, the evidence of sorting action and the phosphatic pebbles appear to be indications of secondary deposition.

Jan 1, 1928

By Barbara Mazzini Loureiro

As placas de circuito impresso (PCI) são materiais heterogêneos e sua composição pode variar em função do ano de fabricação, tecnologia empregada, propósito de utilização, legislações vigentes e país de origem, entre outros. Essas características interferem diretamente no valor econômico agregado a estes resíduos, pois dependem da composição dos mesmos, de tal maneira que as empresas recicladoras tomam como base essas informações no momento da aquisição da sucata. Assim, a classificação e caracterização de PCIs é de suma importância para o mercado de reciclagem de resíduos eletroeletrônicos. A fim de alcançar este objetivo foi realizada cominuição em moinho de facas utilizando grelhas com abertura de 9, 6 e 3mm. A etapa de caracterização incluiu ensaios de digestão em água régia, perda ao fogo, análises química quantitativa por ICP-OES e MEV/EDS. Verificou-se que o lote de PCI estudado possui 39,5% de material cerâmico, 34,5% polimérico e 26 % metálico. A porcentagem em massa de cobre na placa é de 14,28%, de ferro 3,73%, de ouro 0,012% e de estanho 1,29%. O lote não é lead free e é multilayer com quatro camadas de cobre.

Aug 8, 2018

By Carl S. Westerberg

Coal preparation practice and trends follow, among other factors, production trends in any given area. Considering an area the size of a state, some broad predictions may be made after a review of the annual production records. As this paper is concerned with coal cleaning in Utah, data on its production record are pertinent. Table 1 shows the percentage relation of coal production in Utah to the national total as a single figure up to 1935 which includes all recorded production. From 1935 through 1947 these data are presented by years. It is evident from these data that the production of Utah coal is ascending. The reason for this trend is industrial growth in the West resulting in a population shift which accounts for more people than the normal increase would supply together with Utah's relatively fortunate geographical location and its abundance of good-quality coal. Utah is also hopeful of supplying more coal in the future for West Coast power generation.I Utah is not unique among coal-producing states in anticipating greater production in the future. Coal Age states, " . . . it is now evident that a billion-ton yearly production of anthracite and bituminous by 1960 is not impossible." At present it is about 610,000,000 tons, the all-time high in 1947 was approximately 687,803,000 tons. In view of the trend outlined above, obviously more new mines will be required to produce the necessary tonnage. These in turn will require more mechanical cleaning capacity. Whether the required new plants will be built by present operators of mines and mechanical cleaning plants or by others now in the business of producing coal or expecting to enter it is of no consequence in this discussion. The fact is— they will be built.

Jan 1, 1950

By Hall ST, Miles NJ

Recently an inorganic salt, sodium polytungstate (SPT), has become available that allows the preparation of non-toxic solutions of relative densities up to 3.1. It is relatively expensive and at the higher relative densities achievable, highly viscous. Alternative inorganic compounds may in the future be identified that overcome these limitations. The Australian Mineral Industries Research Association Ltd (AMIRA) has initiated a project to examine possible alternatives. However, it has been found that by the addition of finely divided ferrosilicon to solutions of SPT, relative densities of up to 4.0 can be achieved. A laboratory technique for density fractionation of sized mineral samples utilising this finding has been developed. This is currently being extended to study the potential applications of such liquids and suspensions in dynamic systems for mineral, coal and recycled waste separations.

Jan 1, 1993

By S. Kelebek

Batch flotation tests were carried out using samples from stockpiles that were up to 1.5 months old as well as fresh samples oxidized in the lab for up to six months. Head grades and size distributions of samples were equalized whenever possible. The samples from stockpiles and oxidation experiments produced inferior nickel grade-recovery compared to the fresh sample. The poorer grade-recovery performance was attributable to two factors. First, a significant dilution effect was observed due to complete flotation of pyrrhotite. Secondly, the same stockpiling conditions caused nickel losses that were attributable to non-floatability of some pentlandite. Application of a high pH of 10 compared to the regular pH of 9.2 slowed down pyrrhotite flotation kinetics, but was not able to prevent complete flotation after 8 minutes. The samples oxidized in the lab did not match full characteristics of stockpile samples. They provided somewhat better selectivity for pentlandite. Some correlations were observed on a qualitative basis between surface characteristics such as elemental sulphur formation, activation and flotation behaviour. Oxidation conditions, which induce floatability on pyrrhotite while causing incremental loss in pentlandite floatability appear to be the root cause of difficulties in the processing of oxidized forms of these ores.

Jan 1, 2006

By William I. Watson

Problems encountered in beneficiating mineral raw materials become increasingly difficult as there is a shift to lower grade and more complex raw materials, and because of the economic need to strive for ever higher recoveries, higher grade products, and lower processing costs. Methods of attacking the many problems should include not only the familiar chemical and physical tests and equipment, but such techniques as X-ray analysis, infra-red analysis, differential thermal analysis, and the use of electron and X-ray microscopes. Many people in the mineral-treating field are unfamiliar with these newer methods and techniques. The differential thermal analysis method, in particular, does not seem to be very well known, even though it offers interesting possibilities in the study of many ore treatment problems.

Jan 7, 1959

Due to geographical location, AustraliaÆs economy and trading are closely related to Asia. With ChinaÆs increasing demand on resources and energy and Japan and KoreaÆs steady imports in these fields, AustraliaÆs mining industry is experiencing a so called æboomÆ period. Traditionally, engineers or skilled workers from South Africa, Britian or other parts of Europe moved to Australia for its mining industry. Now, more students from Asia are starting to choose mining engineering (similar choices include mining geology, metallurgy, geotechnical engineering and mining surveying) and expect to work in these fields. How does AustraliaÆs mining industry face such a situation? What kinds of challenges and opportunities do the mining industry and universities face? How do mining companies utilise these human resources? This paper concludes with an analysis of all these questions at an industrial level and some personal deduction as to the preferred course for international students.

Jan 1, 2005

By Gerald W. Elger

To determine the feasibility of removing nonferrous metal impurities from automobile scrap by thermal treatment in a rotary kiln, the Bureau of Mines conducted four series of tests with synthetic scrap mixtures heated at various temperatures under oxidizing and reducing conditions. The treated scrap mixtures were melted in an electric-arc furnace and cast into small ingots for impurity evaluation. Analyses showed that the ingots were essentially free of residual metal impurities except for copper. Test data indicated that in an oxidizing atmosphere the percentage of copper removed increased with treatment temperature. Percent of copper removed in a reducing atmosphere was found not to be temperature dependent. A significant finding was that copper was embrittled under some of the operating conditions and was mechanically removed by fragmentation.

Jan 1, 1968

By Toffeg A. N, Abdul-Hameed I

More than 1000 Ian of seismic reflection data correlated to ten exploration wells along with geological, gravity and magnetic data are used to construct the subsurface structure, in particular the crystalline basement, along a corridor approximately 100 Ian wide that traverses central Iraq in SE-NW direction for a distance of about 500 km from Baghdad in the central part of Iraq to Dohuk near the Turkish border. This transect is one of few such transects that represents the Iraqi contribution to the Global Geoscience Transects (GGT) project. The transect crosses two out of three major tectonic elements of Iraq: the unfolded zone and the folded zone.

Jan 1, 1990

By J. D. Morgan

The US economy grew steadily in 1989, reaching an annual rate of $5.3 trillion in the last quarter (US trillion=1012 ). The value of domestically processed, mineral-based materials rose 5% to $315 billion (US billion=109). The value of metals produced from US ores rose 14% to $11.6 billion, while industrial minerals rose 2% to $20.2 billion. Recycled scrap was valued at $10 billion. Increasing economic activity stimulated metal prices. Yearly lows and highs were $2.31 and $3.56/kg ($1.05 and $1.62 per lb) for copper, $1.58 and $2.57/kg (72 and $1.17 per lb) for aluminum, 77 and 97 cents/kg (35 cents and 44 cents per lb) for lead, and $1.58 and $2.09/kg (72 cents and 95 cents per lb) for zinc. Many mining and metal companies reported reasonable profits. Consumer demand strongly affects mining because the US economy is saturated with long-lived products. Consumer, mortgage, and Federal debt continued to rise. 250 million US citizens already possess 172 million licensed motor vehicles and 100 million dwelling units. New car production fell 4% to 6.8 million units, while truck and bus production fell 1 % to four million units. New housing starts fell 9% to 1.4 million units. Imports supplied a significant proportion of total US consumption of several important mineral materials. Imports of crude and refined petroleum costing $50 billion exceeded domestic crude oil production. President Bush expressed "strong concerns about this country becoming further dependent on foreign oil." And the Department of Energy held a series of hearings around the country to develop ideas for a "national energy strategy."

Jan 1, 1990

By A. Romero-Juarez

This paper is concerned with the effect of propping-agent concentration on flow capacity of a fracture in the case in which there is embedment of the propping agent. Previous published studies have shown definitely that there is a relationship between fracture flow capacity and prop ping-agent concentration, and it has been shown that the theoretical results are confirmed by laboratory experiments. The problem of directly finding sand concentration for maximum flow capacity of a sand-propped fracture is solved, and formulas and charts are given to obtain this concentration under various conditions of effective overburden pressure, medium sand-grain diameter and rock properties. It is shown that, for the same effective overburden pressure and the same rock characteristics, optimum sand concentration in pounds per gallon does not depend on medium sand diameter. For conditions met in bydraulic fracturing operations, it is found that sand concentration in grains per square inch for maximum flow capacity varies within a wide range of values; this indicates the convenience of using data of fracturing pressure and rock characteristics for calculating sand concentration in order to achieve the best results in fracture treatments. INTRODUCTION It has been pointed out in the published literature1 that one important factor controls the success of a hydraulic fracturing operation — the propping of the fracture. The main effect of the propping agent is to hold the fracture open by means of the reaction forces that oppose the pressure due to the overburden. It is assumed in this paper that the propping agent is sand, that the grains are spherical and uniform in size, and that this sand is distributed in a monolayer in the fracture. The existence of a sand concentration value for maximum fracture flow capacity has been recognized since the publication of one of the first studies on the subject.2 In the reference cited, flow capacity was assumed to be proportional to the cube of the fracture volume per square inch not filled by sand. The obtained experimental curves relating to flow capacity and sand concentration had the same appearance as the curves obtained with the afore-mentioned assumption. Recent work3 has shown that fracture permeability, in the case of a monolayer, can be calculated accurately by means of a modified Kozeny-Cacman equation; thus, it can be shown that fracture pqmeability is a function of free volume in the fracture and of the rock and sand wet surfaces. The flow capacity of a fracture is dependent on the permeability of the fracture and on the fracture width. If all excessive quantity of sand is present in the fracture, its width may be large but its permeability i:; low due to the greater flow resistance; too few grains of sand per square inch are present in the fracture, sand embedment in the rock is greater and the width becomes small enough to appreciably decrease the rate of flow. To determine optimum conditions of flow, therefore, it is necessary to know the dependence of fracture width on density or concentration of propping agent. This relation is given in a study4 in which the approach to embedment is similar to the one made in a penetration hardness test of metal. With the equacions presented by Darin and Huitt,3 the number of sand grains per square inch that results in maxirnum fracture capacity can be determined graphically by plotting fracture capacity vs sand concentration. Since the relationship between fracture capacity and sand concentration may be considered known, one is led to formulate the analytical problem of directly determining sand concentration for maximum fracture flow capacity, in order to study the effect of the various quantities that come into the process. The solution of this problem appears to be interesting both from the viewpoint of fluid mechanics and from the practical viewpoint of oil production in hydraulic fracturing treatments. EQUATION FOR FRACTURE FLOW CAPACITY It can be shown3 that the fracture flow capacity of a monolayer is given by the following expression,

By Nicholas C. Lias

Quartz crystals are the raw material from which are made the crystal units utilized in filters and oscillators so vital to the performance of all long distance communications systems. These devices act as the heart of equipment that permits a single telephone cable to carry hundreds of conversations simultaneously. Quartz crystals are of value in communications because of this piezoelectric nature, that is when an electric signal is applied to the quartz, there is a resulting mechanical motion and conversely, a mechanical stress results in an electrical output signal. A plate cut from a quartz crystal will oscillate at some specific frequency, which is determined by the physical dimension of the plate. During the early stages of telephony, all quartz plates were cut from natural quartz, which was imported mainly from Brazil. Since the source of this important raw material was based upon a foreign supply which is located at a great distance from the user and could be vulnerable in time of a national emergent, it became necessary to maintain a large inventory of this strategic material. Also due to the considerable cost of natural crystals of a size and quality suitable for Bell System use, an investigation was made by Bell Laboratories into the possibility of developing a substitute material. The effort was successful and led to a joint development program between Bell Laboratories and Western Electric. This program brought about the design of manufacturing facilities capable of producing large quantities of cultured quartz at Western's Merrimack Valley Works, No. Andover, Massachusetts.

Jan 1, 1973

By D. E. Hartman, J. M. Roberts

A detailed study of the temperature dependence of the critical stress, TB . necessary to cause a damping loss of 1.41 x 10-6 g mm per mm3 in pre-strained magnesium single crystals has been carried out in the temperature range 82" to 320°K. Tb is found to be linearly related to the reciprocal of the ahsol~cte temperature in this temperature range. The temperature dependence of the anelastic limit, TA, defined as the stress necessary to form open unidirectional stress-cycle damping loops has been measured between 82" to 320°K. ta is found to be independent of temperature in this range. It is suggested that TA is determined by the stress necessary to activate Frank-Read dislocation NUMEROUS studies1-9 have been reported concerning the details of yielding and microstrain near and below the generally discussed macroscopic flow stress. The work of Kramer and coworkers10-13 is helpful in determining certain qualitative facts. concerning preyield phenomena. The absence of a stress-dependent delay time in annealed copper and aluminum single crystals between 83" and 298 suggests that the preyield mechanism is temperature-independent in this range. This is not sources. The temperature and stress dependence of the effective activation volume (Veff) has been measured in the damping-loop region in prestrained magnesium single crystals. The data suggests that Veff/kT is approximately constant, equal to 2 4.5 sq mm per g in the temperature range 130°to 298°K, and that Veff is almost independent of stress at stress levels greater than 10 g per sq mm. A restricted model is developed to predict the stress (rb) necessary to cause a small fixed damping loss as a function of temperature, effective activation volume, and dislocation density. Various possible dislocation mechanisms controlling TB are discussed. true for zinc, p brass, and iron crystals in the same temperature range, however, since the existence of a stress-dependent delay time suggests a thermally activated preyield mechanism in these materials.10-13 The work by Vreeland et a1.14 confirms the work by Liu et al.ll on delayed yielding in zinc single crystals. A stress-dependent delay time between 82" and 298°K was found12 in prestrained aluminum and copper crystals. These results suggest that the preyield phenomena may be different between prestrained and unstrained or annealed crystals. The temperature dependence of the yield point at 2 x 10-8 plastic strain found by Rosenfield and Averbach3 in annealed copper and aluminum is not in agreement with the delay-time data, unless possibly the delayed yielding experiment only de-

Jan 1, 1964

By Osvaldo A. Bascur

The implementation of continuous quality improvement is the confluence of Total Quality Management, People Empowerment, Performance Indicators and Information Engineering. The supporting information technologies allow a mineral processor to narrow the gap between management business objectives and the process control level. One of the most important contributors is the user friendliness and flexibility of the personal computer in a client/server environment. This synergistic combination when used for real time performance monitoring translates into production cost savings, improved communications and enhanced decision support. Other savings come from reduced time to collect data and perform tedious calculations, act quickly with fresh new data, generate and validate data to be used by others. This paper presents an integrated view of plant management. The selection of the proper tools for continuous quality improvement are described. The process of selecting critical performance monitoring indices for improved plant performance are discussed. The importance of a well balanced technological improvement, personnel empowerment, total quality management and organizational assets are stressed.

Jan 1, 1995

By R. W. Stahl

The use of continuous mining machines has greatly minimized the necessity for blasting in coal mines, even during pillar recovery; however, explosives are still used to blast stumps. The use of improper blasting materials, improper procedures, or both has caused mine explosions and fires, with loss of life and property damage. Researchers and manufacturers are continuously improving explosives and blasting accessories; use of the more recently developed materials will make the blasting operation safer. Extreme caution is mandatory when blasting stumps, as the ignition of methane or coal dust may trigger an explosion or cause a fire. Since the blasting of stumps will no doubt continue, although often unnecessarily, this paper summarizes recent findings published by the Bureau of Mines and recommends safer methods.

Jan 1, 1962

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Jan 1, 1938

By Donald M. Podobnik

The Cuajone Concentrator of the Southern Peru Copper Corporation is located approximately 900 kilometers southeast of Lima, Peru, near the 500 year old town of Moquegua, in an area that has been occupied since antiquity. Since the plant was started in July, 1976, the throughput has steadily increased from 36,000 to 46,000 metric tons per day. The widely distributed molybdenite content of the ore body ranges from 0.02 to 0.04% MoS2. The molybdenite content of the copper concentrate has always been sufficient to justify operation of a byproduct molybdenite plant. During the first nine months of 1980, the average grade of the ore was 1.169% copper and 0.026% molybdenite.

Jan 1, 1981

By E. D. Gardner

Apparently the widespread agitation for the codification of our mining laws has had its effect, and it is quite possible that Congress will take up the question during this present session. The greatest objection to our present statutes pertaining to metalliferous deposits seems to be directed against the law of the apex. Those who are not in favor of changing this law are very far in the minority and they apparently realize that it is useless to urge its retention. Next in importance to the repeal of the law of the apex, seems to be a widespread advocacy for the repeal of the law requiring discovery of mineral before a valid location of a mining claim can be made. To a lesser extent there appears to be a desire to have the law changed so as to allow patent for claims without mineral discoveries. The purpose of this article is to review the arguments in favor of the proposed change of the discovery requirement, to show some of the evils that may be expected to result therefrom, and to consider whether a system may be devised to correct the undesirable features of the present law in this respect and at the same time not expose the mining fraternity and the general public to the evils which would result from the repeal of this fundamental requirement. Under the law as at present framed, the validity of a mining location is dependent upon the fact of discovery of mineral within the boundaries of the land claimed. " * * * but no location of a mining claim shall be made until the discovery of the vein or lode within the limits of the claim located" (Sec. 2,320, U. S. Rev. Stat.). All authorities agree that discovery is the source of the miners' title. Lindley, in his valuable work on Mines (3d Ed., Sec. 335), lays down the rule in part as follows: "Discovery is the initial fact. Without that no right can be acquired. * * * Such discovery must precede the location, or be in advance of intervening rights. The proof of recording and marking a claim will not authorize the court to presume a discovery." As is well stated by the U. S. Supreme Court in Erhard v. Boaro (113 U.S. 536):

Jan 1, 1917

By E. P. Youngman

This paper presents one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative, to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the mining laws of British Guiana has been prepared from the best available sources in Washington and is, released subject to amplification and correction, if necessary, by United States foreign-service officials. INTRODUCTION The sources of information available in the preparation of this paper are the following: 1. The Crown lands ordinance, No. 32 of 1903, September 26, 1903.

Jan 1, 1934