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By Sihua Lei, Hong Zhong, Shuai Wang, Yu Gan, Zhanfang Cao

High purity MgO is widely used in various fields as an important magnesiumcompound. The separation of Mg and Ca is of great importance for the preparation of high purity MgO from dolomite. In this study, the key effects of carbonization temperature and nano-calcium carbonate agglomeration on the separation mechanism of calcium and magnesium have been investigated. The results indicated that the reaction in the carbonization process was stepwise. Precise control of the carbonization temperature was essential for the formation of Mg(HCO3)2 due to its low reaction efficiency at lower temperatures or decomposition markedly at higher temperatures. Meanwhile, there was a common-ion effect in solutions containing Mg2+ and Ca2+. Nano-CaCO3 particles were formed during carbonization and agglomerated with the prolongation of static time. A product with a purity of 99.56% MgO and 0.16% CaO was obtained under the optimized conditions: ratio of liquid–solid 30 L/g, carbonization temperature 22–25 °C, carbonization time 1 h, and refining time 4 h. This work has important guiding significance for the preparation of high purity magnesium oxide from dolomite.

Apr 21, 2020

By Ronald Ticona, Anaani Huaman, Andrea Lucero

Mine-to-mill optimization begins with a clear understanding and ongoing assessment of blasting, crushing, and grinding operations. Modification of blasting practices to optimize feed size can increase a mine’s throughput. However, this is only an initial step. To optimize the entire process and fully utilize downstream equipment, fragmentation must be measured at critical points along the size reduction circuit

Jan 1, 2019

By G. Abowitz, R. B. Gordon

The velocity of sound, mass density, and thermal expansion coefficient were measured in dilute lead, tin, zinc, bismuth, cadmium, indium, and potassium amalgams as a function of composition. Measurements in the Hg-TI system extended ovev the wider range of composition, 0 to 40 at. pct TI. The sonic velocity was measured as a function of temperature. The calculuted adiabatic compressibility in all cases was found to decrease much more rapidly than would be expected on the basis of a linear variation with composition. An interpretation of the results is given in terms of changes in the Debye characteris -tic temperature of mercury on alloying and a possible change in the bonding of mercury itself. If a liquid is considered as an isotropic elastic medium, the phase velocity of a longitudinal elastic wave traveling in the liquid is given by where K is the bulk modulus, G the shear modulus, and d the mass density. G can be neglected for liquids of ordinary viscosity, i.e., approximately 1CT2 poise, because the shear stress component is relaxed essentially at once. That is, for liquids of ordinary viscosity and at frequencies of the applied stress up to several hundred megacycles, the relaxation time of the shearing process is much shorter than the period of the applied stress. Eq. [I] then reduces to The adiabatic rather than the isothermal compressibility is measured at the megacycle frequencies used in ordinary ultrasonic velocity measurements. The sonic velocity and compressibility have been determined for many organic liquids and aqueous eletroltes,' and the results have been interpreted in terms of existing theories for these fluids. The velocity of sound and compressibility are important parameters in theories of the liquid state. For example, equations of state have been proposed relating the free volume of liquids to the acoustic velocity.3 Comparatively very little work has been done on the acoustic properties of liquid metals and alloys. leppa,' orddon, and several other investigators

Jan 1, 1963

By Caibin Wu, Ali Lei, Ningning Liao, Jingsheng Ye

"The particle size distribution characteristics of ground product can influence the quality of the classification overflow and the next beneficiation indexes in an ore concentrator. Usually, the size distribution of ground product is considered to be determined by that of new ball mill feed. However, based on large amounts of data from industrial grinding circuit surveys, this paper has clearly shown that the size distribution of ground product should be determined by the size characteristics from classification underflow unless the circulating load was small, because the new feed is an important component and occupy a dominant position of mixed ore from belt feed and classification underflow. On the other hand, the correlation coefficient of the size distribution between ground product and classification underflow can be more than 0.99 when the relevance principle and its method are used. Meanwhile, their P80 value also keeps a synchronous correlation. The greater the capacity of classification underflow is, the higher the correlation of size distribution between the ground product and the mixed feed is. Furthermore, the correlation coefficient of the size distribution between ground product and classification overflow which is from primary or secondary can be 0.96. It is another discovery that the correlation coefficient is related to the type of classifier. The coefficient of size distribution of overflow and underflow from hydrocyclone is superior to that of spiral classifier, which can explain the reason why the hydrocyclone is widely used to replace the spiral classifier in concentrator.INTRODUCTION It is well knows that ball mill circuits closed with cyclones or spiral classifier such as a primary grinding circuit, a secondary grinding circuit and SAB mill have become an industry standard. Which grinding process employed will be determined by the P80 value of ground products. When the primary closed circuit ball mill or SAB that it is different throughout between the two processes was employed, a grinding fineness with -200mesh under 68% will be available. However, the secondary grinding circuit with the fineness of -200mesh above 80% can be conducted. Of course, the grinding fineness is determined by the grain size characteristics of the mineral."

Jan 1, 2018

This paper presents the latest developments in the flotation model being developed collaboratively between the Julius Kruttschnitt Mineral Research Centre in Brisbane, Australia, and the Mineral Processing Research Unit of the University of Cape Town in South Africa as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. It includes: - characterisation of flotation cells using the bubble surface area flux, Sb; - relationship of Sb to the overall flotation rate constant; - determination of the froth recovery factor; - evaluation of ore floatability; - modelling of entrainment - development of the Floatability Characterisation Test Rig (FCTR); - use of the model in design and optimization of flotation plants; and - current and future work.

Jan 1, 1999

By J. M. Kuchta

The Bureau of Mines investigated four simulated coal gob fires to obtain a more reliable data base for defining the state of a sealed mine fire and to evaluate the performance of various fire detectors. The fires were conducted in a multiple-entry section of the Bruceton Experimental Mine by heating 4,000 to 21,000 pounds of rubblized bituminous coal to ignition and monitoring the temperature, gas emissions, and smoke under ventilated and sealed combustion conditions. Product gas concentrations depended upon the coal bed size, coal temperature, heating rate, and oxygen concentration or ventilating condition but varied little after the fires were sealed. Expressions are given that define the temporal variation of CO and O2 after sealing when the coal temperature decreased rapidly. The CO/C02 ratio is a more sensitive fire indicator than the CO/?02 ratio, although the latter is universally used for detecting the incipient state of a coal fire. In comparison, the Jones-Trlckett ratio [ CO2 + ¾ CO ? ¼ H2 ?O2] is less reliable for this purpose. The best detector for determining the state of a mine fire after it has been sealed was a prototype submicrometer smoke particulate sensor. Limitations of the various detector systems are also discussed.

Jan 1, 1982

By J. A. M. Cano

An extensive research work was developed by Samarco Mineracao S/A to study the quality characteristics of blast furnace pellets produced with high content of MgO. Comparative blast furnace simulation tests were conducted both in Samarco and foreign laboratories. The objective was to evaluate the behavior of high MgO and normal Samarco pellets in the blast furnace operation. Additives such as dolomitic hydrated lime, dunite and magnesite were used for increasing pellet MgO content. The test results showed that pellets produced with high MgO content are similar in quality to normal Samarco Pellets.

Jan 1, 1991

By L. C. Brichta

During a study of the Badger-Peacock area from October 1950 to June 1953, the Federal Geological Survey and the Federal Bureau of Mines completed nearly 98 miles of resistivity profiling and drilled 96 test holes aggregating 17,628 feet of bore, In addition, seismic profile measurements were made along 8 traverse lines for an aggregate length of about 16,600 feet. The geophysical surveys were conducted by the Geophysics Branch of the Geological Survey; the drilling was done by the Bureau of Mines. Electrical-resistivity measurements disclosed 21 low-resistivity anomalies and 1 high-resistivity anomaly. Correlation of the resistivity data with the geological information revealed by the drilling disclosed that the low-resistivity anomalies indicated either slumped shale deposits in limestone sinks or undisturbed deposits of shale lying in erosional depressions in the limestone. The high-resistivity anomaly indicated hard, undisturbed limestone at or near the surface.

Jan 1, 1958

By K Hooper

Over the past 20 to 30 years statistics as a science has grown in significance. Not a day passes without reference to the latest statistics by the print, audio and audio-visual media. The Northern Territory Government has been part of this growth and like other public and private sector organisations collects a broad range of statistics. The Northern Territory Department of Mines and Energy participates in the government's statistics collection process. Statistics collected and published by the Department of Mines and Energy include geoscientific; mining and exploration tenure; environmental (e.g. mine site waste water management); production of minerals, oil and gas; mining sector employment; and occupational health and safety. The importance of statistics collection to the Northern Territory Government is discussed in the paper.

Jan 1, 1994

By M. Melashvili

"The SART Process was introduced to the gold mining industry in the late 1990s and several commercial plants were built over the following 10 to 15 years. Most of these plants have operated well and enjoyed plant performance in line with expectations based on the underlying chemistry of the process. However, two of the plants have consistently suffered from high reagent consumption and poor product quality, which has motivated a re-examination of the process fundamentals.The primary product in the SART Process is synthetic chalcocite, Cu2S, and the stoichiometric requirement for sulphide addition is therefore 0.5 moles per mole of copper in solution. It is shown here that when sulphide is added in excess of this amount (generally with the express purpose of lowering residual copper in solution) it not only fails in its intended purpose, but can have a negative impact on the settling and filtration characteristics of the copper sulphide product, as well as the final product quality. Moreover, these problems are exacerbated the higher the selected operating pH in the pH 3 to 5 range, and the longer the residence time of slurry in this pH range.Freshly precipitated copper sulphide compounds are known to be very fine and slimy, with poor settling and filtration characteristics. It is therefore important to engineer the SART Process in such a way as to encourage growth in the average particle size of the precipitate crystals. This was the rationale for recycling a portion of the thickener underflow to the primary reactor when the SART Process was developed. However, the theory of crystallization predicts that compounds of extremely low solubility, such as chalcocite (Cu2S: KSP = 10-48), are unlikely to experience growth in crystal particle size through heterogeneous nucleation and are more likely to grow through aggregation. On this basis, the SART practice of recycling a portion of thickener underflow to the primary reactor in the commercial plants is unlikely to lead to crystal growth via nucleation, and could in fact promote breakage of the aggregates that formed in the thickener. Recycling thickener underflow could therefore have the opposite of the desired outcome. The result of testwork that is reported here lends credence to this theory and questions the wisdom of recycling in the SART process."

Jan 1, 2016

By T. Hayashi

A sophisticated process of extracting ultrafine sulfide mineral particles of under 1µm size suspended in clay slurry has been developed through studies of electrochemical properties of particle surface. Experimental procedure and data of the process applied to some clay ores containing sphalerite and pyrite, and molybdenite and other sulfide minerals are reported. Discussions concentrated on the function of process reagents, particularly on various modifying reagents, and on the effect of dispersed or flocculated state of ultrafine particles in slurry which affect significantly the performance of the process.

Jan 1, 1982

The Acid Drainage Technology Initiative (ADTI) was initiated in 1995 by federal agencies, the National Mining Association (NMA) and the Interstate Mining Compact Commission (IMCC) to identify, evaluate and develop cost-effective and practical acid drainage technologies. In 1999, ADTI was expanded through the addition of the metal mining sector, which is focused on drainage quality issues related to metal mines. ADTI addresses drainage quality issues from abandoned, active, and future coal and metal mines. The guiding principle of ADTI is to build consensus among industry, federal and state regulatory agencies on acid drainage technology development and technology transfer issues. ADTI is focusing its efforts on mine drainage prediction, sampling/monitoring, modelling and avoidance/remediation. ADTI is not a regulatory or policy development program. ADTI includes the Coal Mining Sector (CMS) and the Metal Mining Sector (MMS) under the overall guidance of the ADTI Operations Committee. The Operations Committee consists of representatives from industry, state and federal government and academia. The Coal Mining Sector includes two committees; a prediction committee and an avoidance and remediation committee. The Metal Mining Sector includes steering committee and work groups on prediction, sampling and monitoring, modelling, mitigation, and pit lakes. The Coal Mining Sector has produced two publications on the prediction and prevention of acid drainage. The Metal Mining Sector has workbooks under preparation covering the work group topics. This past winter, the Metal Mining Sector, working with the US Bureau of Land Management, presented a satellite training session on acid drainage. ADTI has evolved in response to changing needs and technologies as evidenced by the addition of the Metal Mining Sector in 1999. The Operations Committee and the members of the Coal and Metal Mining Sectors will guide future direction in response to identified issues.

Jan 1, 2003

By William L. Crentz

Late in the nineteenth century en active coal-mining industry was begun in the Lower Freeport bed near Reynoldsville, Pa., where the bed thickened to more than 10 feet in places . The coal was readily accepted as an excellent steam fuel. Much of the thick coal his been depleted, but there are many areas where the deposit averages about 14 feet in thickness. As the more desirable mining sites were worked out in the Lower Freeport bed, other beds were exposed from which will come the county's major cowl production in future. The Lower Freeport bed is still the most important bed in Jefferson County from a production standpoint. The Lower Kittanning bed is second. Sporadic mining is being done in the Upper Freeport, Upper Kittanning, Middle Kittanning, Clarion, and Brookville beds. Strip mining has permitted recovery of much coal that could not be mined profitably by conventional underground methods.

Jan 1, 1953

By David B. Reger

Extensive drilling for gas and increased pipe-line building were the major petroleum activities in West Virginia during 1937. According to the West Virginia Department of Mines, 1034 permits to drill were issued. A running account of operations from trade journals and other reports shows that 1041 wells were drilled, resulting in 193 oil wells with 1238 bbl. of daily production; 680 gas wells with 1,048,057,000 cu. ft. of daily open flow; and 168 dry holes. The new oil-well average is 6.4 bbl. per well per day; the gas-well average is 1,541,260 cu. ft. per well per day; the ratio of dry holes to completions is 16.13 per cent. Very little attempt was made to develop new supplies of oil. Because of the continued low price, operators evidently considered it good business to leave oil in the ground rather than to produce it at a loss or on a small profit basis. The principal oil wells completed, by counties, are: Calhoun, 16; Clay, 10; Pleasants, 17; Ritchie, 42; Roane, 16; Tyler, 13; Wetzel, 11; Wirt, 14; Wood, 13. The leading counties in gas, with the number of successful wells in each, are: Boone, 54; Braxton, 31; Cabell, 48; Calhoun, 46; Gilmer, 82; Kanawha, 134; Lincoln, 44; Ritchie, 56; and Wayne, 26. General State of the Industry In Table 1 will be found an approximate summary of oil and gas territory and reserves, oil and gas production and number of oil and gas wells. The amount of land under lease is an approximation, because the exact figures are not available through any public or private agency. The proved land and reserves represent the opinion of the writer. The oil production for 1937 is subject to revision, and the gas production for the same year is only an estimate, based on demand and supply. The number of oil and gas wells now active is also an approximation, based on previous studies, and revised for completions and abandonments. Principal, Areas of Activity In Boone County, 62 wells were drilled in various localities, resulting in 4 oil wells and 54 gas wells with 18,170,000 cu. ft. of new production.

Jan 1, 1938

By John Kostuik

AT the Sladen-Malartic mine, a number of orebodies have been mined, some by shrinkage and others by open sub-level scopes, from which the ore is handled either through a grizzly system or by mechanical loaders. This paper deals with the comparative costs and relative merits of the two handling arrangements. The facts brought out in this comparison have a bearing on the selection of a proper handling method. The mine is in Fourniere township, northwestern Quebec, about forty miles east of the town of Rouyn. It is served by the Rouyn-Senneterre branch of the Canadian National railways. Two vertical three-compartment shafts give access to the present workings. No. 1 shaft, at which the plant is centralized, is the main hoisting shaft, with five levels to 950 feet. No. 2 shaft, 2,400 feet east of No. 1, is under development, with four levels to 725 feet. At the main shaft, the ore is hand-trammed in 1 1/2 tons cars from the scopes to the stations o:i each level and hoisted in cages to surface at a rope speed of 900 feet per minute. Air-operated tipples are used to dump the ore through grizzlies of 14-inch openings into a surface bin of 150 tons capacity. The ore hoisted at No. 2 shaft is trucked from the headframe bin to the mill. Milling commenced in January, 1938, ar a daily rate of 250 tons. Within two months this rate was increased to the unit's maximum capacity of 325 tons. A second unit to treat a further 325 tons daily was installed in April, 1939. The orebodies mined at No. 1 shaft are parts of a silicified zone at the contact between syenite porphyry and greywacke. The zone is ten co sixty feet wide, strikes easterly, and dips to the south at 55 to 85 degrees. The hanging-wall of the zone is marked, though not precisely, by a strong gouge fault. Locally, the boundary of silicification may be as much as twenty feet either above or below the fault, but for practical mining purposes the fault is the hanging-wall of the ore-zone. The footwall roughly parallels the fault, but as an assay wall it is usually irregular in detail. The ore is dense and hard, a siliceous replacement of both porphyry and greywacke, mineralized with fine disseminated pyrite.

Jan 1, 1941

By J. Jara

Oxygen, ozone and air were evaluated in the oxidation of ferrous iron in the presence of hydrochloric acid ranging from 0.1 to 4 M HC1. Stoichiometric coefficients were determined through mass balances of gases and ferrous titration. The molar ratio ferrous to ozone increases from two at 0.1 M HC1 concentration to six at 4 M HC1. For oxygen the same ratio is constant and equal to 2 and it is in agreement with other works. The stoichiometric coefficient of hydrogen ion was not defined due to the effect of hydrolysis of ferrous and in particular ferric ion on measuring acid concentration by titration with sodium hydroxide. Agitation, gas flow and pressure contribute in the utilization of gas. A technique to compare the gas efficiency at several conditions is discussed and it is based on the relationship between oxygen and ferric during time. There is a strong compromise between gas efficiency and ferrous conversion. Oxygen efficiency decreased with time due to ferrous depletion. The gas efficiency ranged from 3 % (low level of agitation) producing 25 g Fe(III)/h to 12 % at 1000 rpm with 60 g Fe(III)/h converted. At 405 kPa absolute the oxygen efficiency was in the range of 80 % producing 300 g Fe(III)/h. The replacement of chlorine with oxygen to enrich molybdenite concentrates by reducing copper to less than 0.2 % was evaluated. Oxygen can be employed in batch or continuous operation and it can treat molybdenite concentrates with high variation of copper content. The dissolution rate is mainly controlled by oxygen addition in which utilization of oxygen plays an important role. Improvement on safety and environmental conditions is feasible by using oxygen instead of chlorine gas. The economics indicate good opportunities to implement oxygen without significant modifications to the actual circuit and enough benefit when oxygen is well used.

Jan 1, 2007

The most frequent initiation of coal dust explosion results from the ig- nition of high methane volumes, often at low concentration close to the minimum flammability limit, by a weak ignition source, e.g. frictional sparks. Tests performed in the 400 m underground test gallery of 7.5 m2 cross section indica- ted the following: 1. Methane at 200 m3 volume and con- centration 4.0 - 5.0 % CH4 may initiate the coal dust explosion. 2. Suppression of explosions result- ing from such initiation is very difficult, even when employing triggered, barriers.

Jan 1, 1988

By I. A. Ibrahim

Ilmenite, in its natural form, is an inactive mineral from which the selective removal of iron is rather difficult. The reactivity of ilmenite. so that it can be leached with dilute hydrochloric acid, can be enhanced by chemical reduction in solution using a suitable metal as a reducing agent. The present paper aims at the evaluation of an Egyptian ilmenite ore for the production of synthetic rutile by direct leaching with hydrochloric acid in presence of iron powder. In this process, the titanium and iron contents are dissolved; meanwhile, the dissolved titanium is hydrolyzed and re-precipitated leaving mainly iron in solution. Leaching conditions were optimized to obtain less iron in the final solid product. Addition of sufficient amount of iron powder during leaching reduces the dissolved Fe3+ to Fe2+ and reduces the dissolved Ti4+ to Ti3+. The creation of Ti3+ in solution is assumed to have a role in dissolving the ferric iron and hence increasing the reactivity of the ilmenite ore. Synthetic rutile of about 90% TiO2 and 0.77% Fe2O3 was obtained from ore with a grain size 100% passing 200 mesh and a 5-hour leach time with 20% HCl at boiling temperature (110°C) and 0.11 g iron powder / g ore.

Jan 1, 2003

By Yasushi Ishikawa

The fact that the degree of granulation and the state of granulated particles of sinter raw mixtures are the influential factors in ensuring coke combustibility and permeability during sintering has been clarified. Based on this knowledge, Nippon Steel developed the divided coke-addition process and the technology to utilize binder, and applied them on a commercial scale. Productivity and sinter quality are thereby greatly improved with a significant reduction in fuel consumption.

Jan 1, 1977

By H. D. B. Wilson

"IntroductionRECENT ADVANCES in geo-chemistry and in •our knowledge •of crystal structure provide a key which enables us to create a systematic picture of the genesis of many ore deposits. This genetic scheme may be used with confidence in assessing certain types of orebodies and may be of some aid in actual exploration, since it affords a rational explanation of the dependence of the composition •of the ore minerals on that of the rock type in which they occur with which they -are •associated. For purposes of the present paper, .the elements chosen are •chromium, vanadium, iron, and titanium. The oxides of all these metals occur in deposits of similar or related type, and it is proposed to show that, for each, the composition of the •ore mineral is related to •the composition of the enclosing :rock, and that one of the principal factors controlling the composition of the ore is the ionic size of its constituent elements.Geochemical PrinciplesThe crystals of the rock-forming silicates and of the magmatic oxide minerals are essentially ionic types. This means that they are composed •of oppositely charged ions such as Mg²+ and 0²-, which are held together by electrostatic attraction. The ions of each element are spherical, with characteristic size known as the ionic radius. Crystals are built up by the packing of these spheres in the most stable arrangement compatible with the size and the size and valence of the ions• involved.Many of the principles governing the formation of ionic crystals are •simple ,and logical."

Jan 1, 1953