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By Francis J. Quinn

The Natural Gas Act, of 1938, which put interstate pipelines under the jurisdiction of the Federal Power Commission, did not place a protective competitive shield around such companies - nor does any provision of the act guarantee them a profit. Natural-gas pipelines are competitive with each other and also with the coal and oil industries. Gas distributing companies must compete not only with the coal and oil industries, but also with the electric industry. Natural gas has captured markets from oil, which had taken them from coal. Oil men contend that gas prices have: been, held to an artifically low level by regulation. The electric industry is moving into the space-heating market, which pleases the coal people because the coal industry's largest customer since losing the railroads to dieselization has been the electric companies. The coal industry is attempting to monopolize the industrial and electric generating market through government intervention, and this is being done under the guise of concern for the national welfare through advocation of a "National Fuels Policy purporting to, further the cause of fuel conservation. Such a policy is contrary to American principles and would result in the individual's loss of freedom of choice and ultimately, in less reserves of preferred fuels because of diminished exploration efforts.

Jan 1, 1961

By Yonghong Qin, Songbo Ma, Qi Zhang, Peng Gao, Jianwen Yu

Herein, the coal-based reduction was proposed to utilize the ferronickel slag of Jingchuan company. An excellent index with metallization rate of 99.22%, iron grade of 77.91%, and iron recovery of 92.79% was obtained at carbon addition coefficient 2.0, reduction temperature 1573 K, reduction time 60 min, the particle size of coal and ferronickel slag − 2.0 mm, and CaO content 15%. The 2FeO·SiO2 was reduced to Fe and SiO2 with the increase of temperature. The CaO could promote the reduction of iron oxide. Most of the sulfides (Fe, Cu, Co, and Ni) in the sulfonium were reduced to metal. The reduction degree increased with the reduction time and reduction temperature. The higher reduction temperature represented the higher peak value of reduction rate and the shorter time of reaching the peak value. The isothermal reduction process included three stages: early stage, middle stage, and late stage. The mechanism function were f(α) = 1/2(1 − α)3, f(α) = 3/2(1 − α)4/3[(1 − α)−1/3 − 1]− 1, and f(α) = 4(1 − α)[− ln(1 − α)]3/4, respectively. The activation energy of three stages was 183.498 kJ·mol−1, 420.077 kJ·mol−1, and 656.619 kJ·mol−1, respectively.

May 24, 2022

By W. Gibson Jaworek

Of increasing importance to the student of fuels economics has been the extent to which different primary energy sources can substitute for each other in the various energy markets of the nation. Knowledge of the nature and extent of fuel interchangeability can aid the fuels economist in projecting trends of energy utilization, as well as giving him a better understanding of the past and present conditions of fuel markets. It is also important to the consumer to know just how much flexibility he can maintain in his energy consuming operations. And, finally, various governmental bodies show keen interest in the degree of energy substitutability in determining public policies concerning the fuels industries. The presence of excess fuel production capacity in the United States during the early 1960's indicates that fuel interchangeability should become more prevalent in the increasingly competitive energy markets of the nation. Discussion of fuel intercompetition is almost always restricted to qualitative terms-because of the lack of comparable statistical data, between the different energy sources in geographic or "type-of-use" fuel, markets. There are exceptions, of course, such as, the excellent fuel consumption data which are available on steam electric generating plants throughout the nation. In other sectors, statistics are at best incomplete.' Inmost instances, indirect fuel consumption indicators, such as sales of fuel burning equipment, are extensively used to measure market shares of a particular fuel; however, these indicators are hard to evaluate precisely without prior knowledge of the total competitive market.

Jan 1, 1961

By Dejan Petrović, Pavle Stojković, Jelena Ivaz, Saša Stojadinović

In spite of the fact that flyrock phenomenon represents the real threat for personnel and machinery, it still remains insufficiently investigated. There are efforts, in the mining community, to explain the causes of flyrock, but the models capable to accurately predict flyrock occurrence and define the flyrock distance still do not exist. This article is an attempt to establish such a predictive model. The model utilized the adaptive nature of artificial neural networks and combined it with the accuracy of numerical modeling of physical phenomena. Necessary data were collected by high-speed camera recordings of actual blasts at three different surface mines and processed for further use for artificial network training. The result was a neuro-numerical couple which was capable to predict flyrock occurrence, estimate the launch velocity of flyrock fragments, and calculate the maximum distance of flyrock fragments. The safe distance was then calculated by multiplying the flyrock distance with a factor of safety. The article explains the procedure for data acquisition and processing, artificial network construction, training, and validation. It also explains the principles of flyrock distance calculation and, finally, provides a definition of factor of safety and safe distance. The results showed that the prediction was satisfactorily accurate and reliable.

Oct 22, 2021

By Johann Steynberg

The design and construction of a Concentrator based on initial pilot plant work is rarely perfect. Palabora's plant was no exception although the basic objective to produce copper in a safely conservative manner was certainly achieved in a profitable manner. identification of the metallurgical and mechanical deficiencies of the plant through operating experience and a better concept of the minerology of the orebody enabled the development of a more efficient process both in terms of the metallurgical performance and cost effectiveness. To maintain and improve this level of efficiency, continuous inspection and revision of the plant metallurgy and engineering standards is required. In this presentation a few of the investigations and changes are described: 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill. 2.0 An analysis of the environmental condi¬tions in Palabora's grinding circuit and the introduction of high chrome balls as grinding media. 3.0 The role of magnetite in the beneficiation process at Palabora. 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill.

Jan 1, 1985

By James H. Allen

The air lift method of pumping water is discussed. A review of several large diameter hole drilling projects that used reverse circulation air lift techniques is presented. Proposals are made for reverse circulation flow rates for slow rates of bit penetration (5 fph) as well as reverse circulation flow rates for faster rates of bit penetration (10 fph). The Ingersoll- Rand air lift equations are modified for rotary drilling operations. By establishing minimum reverse circulation flow rates and utilizing the modified air lift equations, the establishment of minimum circulation equipment sizes and a more definitive requirement for improved bit body design should result.

Jan 1, 1976

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By J. B. Platt

Many utility fuel choices 1990-95 defied expectations, with utility decisions and coal market developments ever more closely linked. The Central Appalachian coal boom never occurred; clean-enough coal was developed in the hard-hit Midwest; Colorado-Utah coal surged; Pittsburgh seam production strengthened; utilities embraced Powder River Basin coal; and emission allowance prices collapsed. Competition drove productivity gains, but the future is not a simple repeat. Phase 2 brings fewer viable compliance options. Mega-railroad pricing has become a key risk factor --will this be countermanded by merging utilities and power market competition? Revenue losses from vintage contracts are problematic. Uncertainty also plagues natural gas, in spite of unanimity across major forecasts, since recent experience has been so heavily influenced by the gas bubble.

Jan 1, 1997

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Hypochlorite leaching system is a strong oxidizing solution for metal sulfides, which are naturally associated with gold extraction. This study evaluated the hypochlorite leaching of refractory gold ore by using the response surface method–central composite design (RSM-CCD) as a statistical approach in determining the optimum condition of gold extraction from refractory gold ore. The studied parameters for the gold recovery were pH (4 to 6), concentrations of Ca(OCl)2 (0.5 to 1.5 M) and NaCl (2.5 to 3.5 M) in the solution. It was found that the maximum gold extraction of 82.46% (13.85 g/t) was achieved at a pH of 4.0 with NaCl and Ca(OCl)2 concentrations of 2.93 M and 1.08 M, respectively. The statistical analysis also revealed that the amount of gold recovery in chloride solution was significantly depended on pH as the main factor, followed by concentrations of Ca(OCl)2 and NaCl.

Jan 8, 2021

By D. M. Hausen

Carbonaceous gold ores are ubiquitous to virtually all of the Carlin-type gold deposits along the Carlin gold belt in north central Nevada, representing the unoxidized "zones" of presumably extinct thermal spring systems of mostly Tertiary age. A period of subtropical weathering resulted in deep sub-lateritic zones in most deposits to several hundred feet below surface. Carbonaceous ores below this supergene profile of weathering have been investigated by various methods, including petrographic study, standard geochemical and organic carbon analyses, carbon and hydrogen isotopic ratios, electron-spin resonance spectra, infrared spectra, and DTA techniques. Results have been integrated with recent findings by other investigators utilizing fluid inclusion and thermal brine data to indicate a first phase hydrothermal solution temperatures and pressures at a minimum depth of 6 km under normal geothermal gradient. This phase resulted in the quartz-barite-calcite vein filling of the host rocks. Gold mineralization took place later at shallower depths. Primary organic material in carbonaceous ores from the Carlin and other mines appears to be a pyrobitumen residue derived from an old oil pool that had been heated by the thermal solutions, and from which the light hydrocarbon fractions were removed. Some of the bitumen was remobilized along silicified veinlets in the ore, but its role in the emplacement of the gold, itself, is not clear. The gold was localized submicroscopically in fine pyrite, mostly in framboids, and as fine metallic particles, but does not appear to be concentrated within the carbonaceous matter per se. However, reducing conditions associated with bituminous residues are believed to have been favorable for gold deposition.

Jan 1, 2013

By R. Mensah-Biney

The aqueous biphase separation process (ABS) has been used to separate ultrafine industrial minerals. The partition behavior of TiO2, Al2O3, Fe2O3 and kaolin was not pH dependent. The partition behavior of SiO2 was, however, pH dependent. The partition coefficient of kaolin in PEG 3400/ Na2CO3 biphase system was = 150 and that of the silica in the same system was = 0.02, resulting in a separation factor of = 8500 between kaolin and silica. The aqueous biphase separation system was used to separate free silica from kaolin in a raw clay sample from Mexico. The partition behavior of mica, feldspar and clay from North Carolina was also evaluated.

Jan 1, 1999

By G. Roberts, S. S. Klima, W. R. Reed, J. Deluzio, G. Ross, A. Mazzella

The abstract discusses the problem of silicosis among roof bolter operators in coal mines due to respirable quartz dust (RCS) exposure. It presents a study comparing a new wet box collection system to the traditional dry box system. The wet box system uses water to saturate collected material, reducing RCS exposure during cleaning. The study found that the wet box system significantly reduced RCS exposures and quartz content in samples compared to the dry box system.

May 11, 2022

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Southwestern New Mexico is part of a large belt of Late Cretaceous to Eocene copper porphyry deposits found in Arizona, New Mexico, and Mexico. These deposits are the result of arc magmatism that occurred during the Laramide orogeny. Recently, attention has been brought to other commodities that can be extracted as by- and co-products, many of which are critical minerals. A new compilation of the geochronology of these deposits shows two main pulses of magmatism that produced mineralized deposits and, along with new dates by the author, shines new light on the geologic history of these deposits and the role it plays in critical mineral abundance.

Feb 1, 2024

By James E. Lawver

During the past century, the Florida Phosphate Industry has established an enviable record of innovative technology in nearly all aspects of mining and beneficiation. A notable exception is the lack of technology to improve the present practice of storing waste clay in earthen dams. The rule which has been adopted by the Department of Natural Resources states, "Since storage of clay wastes for long periods of time interferes with expeditious reclamation and since above grade storage of clays takes otherwise useful land out of production and raises potential health and safety problems, below grade storage and rapid reclamation techniques are encouraged." The two waste products from the beneficiation plant are clay slimes (-0.1 mm in size) and sand tailings. The sand tailings do not present a problem since the tailings rapidly dewater to a dry weight of about 100 pounds/ft3 and make good land fill. By contrast, disposal of waste clay slimes is a formidable task. The basic problem is simply that the waste clay not only dewaters very slowly, but also that the ultimate solids content is very low and in most cases the volume of the clay greatly exceeds the available volume of below ground storage of the mined land.

Jan 1, 1984

By R. Casagrande, L. R. Moore, J. Sessoms, P. Macy

"A South American nickel mine has been producing a nickel concentrate that also contains copper and iron (15 percent nickel, 5 percent copper, 28 percent iron) for the end use of stainless steel production. A critical specification for the quality of the steel is the iron to magnesium oxide ratio (Fe:MgO), with a ratio of below 3.5:1 having a substantial impact on the nickel value. This nickel concentrate producer historically mined the sulfur-rich mineral pyroxenite but had been forced to move to a magnesium oxide/silicate (MgO/SiO4)-rich mineral harzburgite, resulting in nickel recovery being reduced to around 50 percent to maintain the required Fe:MgO ratio. In this study, ore mineralogy, water chemistry and the chemistries associated with the flotation process were evaluated in an effort to increase nickel recovery while maintaining the Fe:MgO ratio according to specification. New chemistry was introduced with the specific goal of complexing with the MgO and retarding its interaction with the bubble flow in the flotation process.IntroductionGlobal nickel production in 2011 totalled to 1,770,000 tons, according to the Raw Materials Group (2013). From 1950 to 2005 there was an aggregate 4.4 percent increase in nickel production, with a market-value high of $1,000/ton nickel reached in 1998 (Mudd, 2010). Approximately 65 percent of nickel production is consumed by the stainless steel industry, with 12 percent of the remainder used in super alloys or nonferrous alloys. Nickel imparts corrosion resistance, temperature resistance and other benefits to its alloys (Table 1) (Oberg, 1996; Cáceres, 2003). The dominant types of nickel-bearing ores are classified as either laterites (limonite: nickel-iron oxide; and garnierite: nickel hydrosilicate) or magmatic sulfide deposits (pentlandite: iron-nickel sulfide) (U.S. Geological Survey, 2013a, 2013b). In 2012, about 40 percent of the nickel ore mined was sulfidic-type ores and about 60 percent was laterite. The processing of laterite ore is expected to continue to increase as the availability of sulfidic ores continues to decline."

Jan 1, 2015

By Ali Jaberi Zamharir, Abolfazl Shoghian‐Alanaghi, Hossein Aghajani, Arvin Taghizadeh Tabrizi

In this study, the leaching rate of molybdenite concentrate was evaluated in sulfuric medium, and the influence of the diverse oxidants including hydrogen peroxide, manganese oxide, copper sulfate on the leaching rate was studied. Also, the effect of the addition of the ethylene glycol to the hydrogen peroxide was studied and results showed that with the addition of ethylene glycol, the leaching rate is increased 55% from 41% up to 80.3%. The optimum condition is achieved as 0.7 M of H2SO4, 4.4 M of H2O2, and 3.5 M of EG at 30 °C within 4 h of leaching time and 500 rpm. Also, inserting the oxygen with the pressure of 6 bar to the leaching autoclave, the leaching rate is increased more up to 86.4%. Finally, the leaching process was studied kinetically and the determined mode of controlling factor was specified based on the activation energy which equals 46.252 kJ/mole indicating the chemical reaction mode.

Jun 5, 2022

By J. T. Crawford

A comprehensive strategic planning model has been developed for the phosphate strip mining and chemical operations at White Springs, Florida. The computerized model covers ore body modeling, production simulation and financial analysis. Several innovative features in the model include using NPV techniques in ore body block economics, adapting the floating cone method to a floating template for generating dragline mining units automatically, using interactive graphics for designing mining units, and a dragline move economics algorithm for automatic scheduling of mining unit assignments and moves. Simulation of chemical plant production uses linear programming and concentrate inventory levels control mine operating schedules.

Jan 1, 1997

By Kwame Awuah-Ofei, Sisi Que, Shaochun Yuan, Yumin Wang, Ziwei Ding

This research sought to facilitate improved stakeholder analysis in mining by providing further insights into the preferences of local community members using discrete choice theory. While recent research has demonstrated the usefulness of discrete choice theory in mining stakeholder analysis, no previous work has examined which discrete choice model (DCM) is most suitable. This paper provides a research note on a case study in a mining community that was performed to compare three DCMs. After a thorough examination of the benefits and deficiencies of all models, this study concludes that the conditional logit model stratified by questions is the most useful DCM for mining stakeholder analysis. The recommendation is based on the usefulness and accuracy (ability to match the survey data) of this model.

Jul 25, 2022

By Saghar Farajzadeh, Fatemeh Kazemi, Ataallah Bahrami

Spirals, the most common equipment for the separation of heavy minerals such as chromite, are greatly affected by size distribution and the liberation degree (hence the specific gravity and size) of the feed particles. In this study, the efficiency of spirals in separation of low-grade chromite particles has been investigated by studying the distribution of grade, size distribution and liberation degree of feed, concentrate, and tailings of spiral. For this purpose, mass balance constraints were applied to the spiral-containing chromite processing circuit. Afterwards, the grade variations and size distributions have been investigated. According to the results, when the feed to the spiral has a larger size distribution, the enrichment ratio of the feed is 1.32 and, with the smaller feed size, this value has increased to 1.99. When the spiral feed has a larger size distribution and higher specific gravity, the recovery of chromite increases with increasing particle size up to 250 microns, and then with increasing particle size, recovery decreases with a relatively steep slope. Evaluation of spiral efficiency with respect to particle liberation degree has also shown that despite the high degree of liberation of spiral feed in size fractions smaller than 75 microns (88.9%), the liberation degree of spiral concentrate and tail in this faction is equal to and less than that of feed, which can indicate poor spiral performance in these size fractions.

Oct 27, 2020

By Magnus Ericsson

The unexpectedly quick recovery in world crude steel production in the second half of 2009 was due almost entirely to increased production in China that began in late 2008. Previous peaks in monthly production in China were matched by April 2009. The rest of the world had still not reached pre-crisis production rates by May 2010. Chinese production drives growth, but there has been some growth in most other larger crude steel producing countries as well, compared to production in 2009. If the production rate of the first four months of 2010 continues, the total output of crude steel in 2010 will be somewhere around 1,410 Mt (1.5 billion st), the same as in the record year of 2007.

Jan 1, 2010