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In order to overcome some of the deficiencies associated with conventional fine coal cleaning methods, a novel process known as microbubble column flotation (MICROCEL?) was developed at Virginia Tech. This article provides an overview of recent commercialization efforts and in-plant testing of this technology. The results of the in-plant test work indicate that the MICROCEL technology offers several advantages for the upgrading of difficult to clean coals. The test data have also been used to develop guidelines for the design of coal flotation columns and to validate existing scale-up procedures.

Jan 1, 1991

By D. Pacey

"This paper reviews the installation, start-up, and operation of a comprehensive monitoring and targeting management technique in which all plant utilities (i.e., electricity, natural gas, compressed air, and water) are managed as controllable resources in the same way that raw materials, mined ore, personnel and capital are managed.The essential elements of monitoring and targeting (M&T) include:•gathering in a systematic, disciplined way the utility information by energy account centres;•closely monitoring the utilities used in each centre and comparing them with production on a common time base (e.g., kWh/ton per day);•bench marking and target setting to pro-vide attainable energy reduction goals which can be further refined as they are achieved; and•establishing an implementation plant that may provide efficiency enhancing benefits to various operating areas within the plant.The M&T system will reduce utility consumption per unit of production on a continuing basis.This would translate into sustained operating cost and waste. M&T will also provide better information for assessing the plant operation and progressively implementing further enhancements."

Jan 1, 1997

By R. Kaibyshev, I. Zuiko

"The effect of thermomechanical processing (TMP) including cold working by tension or rolling before aging on mechanical properties and a dispersion of secondary phase particles of an AA2519 alloy (Al–5.64Cu–0.33Mn–0.23Mg–0.15Zr–0.11Ti–0.09V–0.08Fe–0.01Si (wt. %)) was examined. It was shown that the use of tension to impart pre-strain =10% in the alloy provides the best combination of properties in peak aging condition of the material. The AA2519T87 alloy processed by tension exhibits the yield stress, ultimate tensile strength and elongation to failure of 425.4±2.4, 475±2.4, 12.1±0.4, respectively. The one pass rolling leads to -5% decreases in yield stress and –20% decreases in ductility. Dislocations serve as heterogeneous nucleation sites for ?'-phase precipitation. The positive effect of tension is attributed to the formation of more homogeneous dislocation structure, uniform distribution of ?'-phase particles with higher aspect ratio. Precipitation of the O–phase plates on {111}a habit plane was detected. In addition it was shown that the low angle boundaries are heterogeneous nucleation sites for ?' and O particles.INTRODUCTION Precipitation-hardened alloys are a commercially important group of the materials because their mechanical properties can be modified by treating and changing the microstructure. Age-hardenable aluminum alloys belonging to the Al–Cu–Mg system are widely used due to their attractive combination of high specific strength, good fracture toughness and enhanced creep resistance attributed to the highly efficient strengthening by the ?'-phase (Palmer, StJohn, Nie, & Qian, 2017). An AA2519 alloy exhibiting superior mechanical properties among high-strength Al–Cu alloys (2XXX-serie) due to minor Mg additives. It is known that, in alloys with high Cu/Mg ratio (=5.6) the classic precipitation sequence (Palmer et al., 2017; Wang & Starink, 2005; Wang et al., 2010) of supersaturated solid solution (SSSS) decomposition occurs: SSSS ? GP zones (Al3Cu) ? ?? (Al3Cu) ? ?' (Al2Cu) ? ? (Al2Cu) (1)"

Jan 1, 2018

By J. R. Budden, P. A. Spencer, J. Barrett

The initially produced arsenic (III) is very toxic to the unconditioned culture but the mixed culture has the capacity to oxidise it to arsenic (V) in the presence of iron (III). It was possible to build up the resistance of the culture through progressive sub-culturing on arseno-pyrite until it could tolerate steady-state concentrations of 30 mM arsenic (III) and 200 mM arsenic (V). With some samples tested in the continuous systems the final arsenic concentrations reached 330 mM. It proved possible to use the laboratory batch data to establish the optimum operating conditions for continuous test systems with capacities of up to 32 m3. Data on the residence time, oxygen uptake rates and gold extraction from the bio-oxidised residues could then be confirmed by continuous testing without the need first to use empirical means to determine optimum conditions for continuous bio-oxidation. The data on residence time, oxygen uptake rate, solids density and neutralisation could be used to estimate the capital and operating costs of treating any given tonnage of the concentrate of interest. It was established that the arsenopyrite concentrates can be suitably bio-oxidised to cause the liberation of at least 90% of the gold content. The method is simple to operate and is flexible over a wide range of external conditions

Apr 1, 1991

Cannington Mine is an underground, hard rock, metalliferous mine located in North-Western Queensland, Australia. Weld mesh is installed to prevent the failure of rock from between the installed reinforcement elements. Corrosion reduces the capacity and life expectancy of mesh and presents a real hazard to underground personnel and equipment as it reduces the effectiveness of the support system. Corrosion influences the economics of the mining operation through the need to conduct rehabilitation of the ground support which involves re-installing new mesh or shotcreting over the affected mesh to protect it from further corrosion. The requirement for rehabilitation is determined by the geotechnical engineer based on an individual visual assessment with little or no engineering input. It was identified that a more quantitative method was required that considered the safety and economic risks involved. A project was undertaken to develop a simple method to evaluate corroded mesh and to provide selection criteria for rehabilitation. A weld mesh corrosion classification has been developed that relates the average wire diameter of corroded mesh to the remaining capacity of the mesh. Accompanying selection criteria provides recommendations as to when rehabilitation may be required based on the estimated residual mesh capacity, the remaining development life, and the level of personnel exposure.

Nov 25, 2010

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study oxidation of four synthetic nickel mattes, which were screened into three size fractions, Experimental conditions were: reaction gas from N2 - 21 to 75 vol-% O2; gas preheating temperatures ranging from 500 to I 100'C. The four mattes were synthesized so that Ni/Cu ratios of I and 10 were obtained with high and low iron contents. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect their morphology, internal composition and structure. The best sulfur removal from the synthetic nickel mattes was achieved under the most oxidizing conditions with the finest size fraction. The matte with Ni/Cu = 1 and high iron content was found to be most reactive. The least reactive matte was with Ni/Cu = 10 and low iron content; the coarse fraction particles did not react at all under the conditions studied.

Jan 1, 1996

By J. Stachurski

Flotation tests were carried out on 6 coal samples of different rank as well as their oxidized samples. A mixture of diesel oil and alcohols was used in these tests. Surface oxidation caused a distinct decrease of the flotation recovery with some improvement in the grade The reduction in the recovery increased with increasing the concentration of the oxidizing agent. The floatability of low rank coals was affected by oxidation to a higher degree than medium and high rank coals. The recovery size curves of oxidized samples mere similar in shape to that of non-oxidized coals.

Jan 1, 1990

By W. E. Wallace, S. -G. Xing, M. J. Keane, J. C. Harrison

"SummaryDiesel-exhaust particles from two sources were dispersed in aqueous mixtures of dipalmitoyl phosphatidyl choline, a major component of pulmonary surfactant, and were tested for genotoxicity. Diesel samples from the same sources were extracted with dichloromethane and transferred into dimethyl sulfoxide and subjected to the same assays. Both types of extractions yielded similar results in both the Salmonella mutagenicity assay and the sister-chromatid exchange assay using V79 cells. After separation of the samples into supernatant and sediment fractions, the activity of both diesel samples was shown to reside exclusively in the supernatant fraction for the solvent-extracted samples, and exclusively in the sedimented fraction for surfactant dispersed samples. These findings indicate that genotoxic activity associated with diesel particles inhaled into the lung may be made bioavailable by virtue of the solubilization / dispersion properties of pulmonary surfactant components.While diesel engine emissions are associated primarily with transportation, they are also very common in the workplace. Estimates for the U.S. are that as many as 1.35 million workers in as many as 80 000 workplaces are exposed to the combustion products of diesel engines (NIOSH, 1988). These occupations include, but are not limited to mining, agriculture, motor vehicle maintenance, fork lift truck driving, truck driving, and tunnel and bridge operation."

Mar 1, 1992

By M. S. Klima

Coal gasification solid residue (slag) contains unconverted carbon (char), which is considered an impurity for utilization applications of slag. Under this study, table concentration was used to process approximately 24,000 pounds of a nominal-3.4 mm gasifier slag (-85% ash) to separate high (-100%) ash slag from low (-50%) ash char. The results indicated a nearly ideal separation of the slag from the char for sizes coarser than about 1 mm. An overall slag yield of 71 % was obtained. The slag was sufficiently clean to be used as feed material for the production of expanded lightweight aggregate. The recovered char had an ash content of about 47% and was a nominal -1mm in size.

Jan 1, 1997

By Y. S. Sun, Northeastern University, W. B. Li, P. Gao, Z. Y. Zhang, J. W. Yu

"The boron-bearing iron concentrate was extracted from ludwigite ore by the process of magnetic-gravity separation. In order to fully utilize the refractory ore and meet the boron consumption of China, a novel process for separation of boron from iron in boron-bearing iron concentrate was proposed in this paper. In particular, laboratory scale experiments of improving boron reactivity were performed. Fine boron-bearing iron concentrate briquettes were reduced by bituminous coal completely at 1125 °C for 150 min. The effect of sodium carbonate, which was used as an additive in the roasting process, was investigated. The addition of sodium carbonate decreased the boron reactivity and facilitated the volatilization of boron. The influence of diverse cooling methods of the reduced samples on the boron reactivity was studied. The results indicated that boron reactivity could reach up to 80.76% when the reduced samples were cooled by rapid water quenching. In addition, the magnetic material containing 92.71 % Fe with a recovery of 95.11 % and boron-rich non-magnetic material containing 14.51% B2O3 with a recovery 88.85% could be obtained by low-intensity magnetic separation. The magnetic material and boron-rich non-magnetic material were good raw materials for steel-making and borax production, respectively.INTRODUCTION Ludwigite ore is abundant in Liaoning province of China, with 28.43 Mt B2O3 accounting for 57% of the boron resources of the country (Liu et al., 2006). However, it has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination (Wang, Wang, Ding, Ma & Xue, 2012). At present, boron-bearing iron concentrate and boron concentrate can be obtained from ludwigite ore using magnetic-gravity separation. The boron concentrate contains B2O3 12%~16%, which can be used as a high-quality raw material for the boron chemical industry after activated roasting, but the B2O3 content in the iron concentrate reaches up to 4%~6%. In order to further separate boron and iron from boron-bearing iron concentrate, a blast furnace and a solid pre-reduction followed by electric arc furnace melting have been proposed (Liu, Cui & Zhang, 1998; Wang et al., 2012). However, both of these two current routes face the same crucial problem that molten boron-rich slag has to be cooled slowly to obtain the alkali-dissolution activity of boron, which affects the yield of boron resource."

Jan 1, 2016

By W. Kunda

Silver nitrate solution is a very common product in hydrometallurgical processes involving the treatment of various silver bearing materials. Silver is recovered by electrolysis. The alternative method for the recovery of silver from aqueous solutions is the precipitation by hydrogen at elevated temperature and pressure. A previous study by the authors revealed the feasibility of this technique for the silver ammine sulfate system. Further study showed different behavior for silver in the silver ammine nitrate system and a systematic study was initiated to establish the optimum conditions for the process. The study showed that the process can be controlled by (1) composition of the feed solution, (2) temperature and (3) hydrogen pressure. The recovered silver product was in the form of very fine powder.

Jan 1, 1989

By K. S. Raja, B. McNall, B. Pesic

"High-level radioactive wastes are stored in large underground storage tanks made of low-carbon steel. The wastes consist of concentrated solutions of sodium nitrate (NaNO3) and sodium hydroxide (NaOH), and the radionuclides 137Cs, 99Tc, and 90Sr. The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV), which in turn modifies the kinetics of corrosion of the storage tank. To understand the influence of technetate ions on the corrosion of steel, electrochemical polarization studies of A 537 steel samples were carried out in 1 M NaNO3 + 0 .05 M S r(NO3)2 + 0.1 M NaOH with and without addition of HReO4 at different temperatures (24 – 85 °C). The concentration of HReO4 was varied from 0.014 – 0.04 M.INTRODUCTIONAqueous processing of spent nuclear materials generates a large amount of high-level radioactive wastes. The wastes are primarily salt solutions of sodium hydroxide and sodium nitrate which also contain fission products such as 137Cs, 99Tc, and 90Sr. Among the high level radioactive fission products, Tc-99 is of great importance because of its high concentration, long half-life (2.1 x 105 years), high solubility in geologic waters as technetate, and rapid diffusivity through the geologic systems. The solubility of technetate ions varies depending on the oxidizing conditions prevailing in the storage containers. High level radioactive wastes are stored in single shell or double shell tanks made of low carbon steels such as ASTM type A15, A516-70 and A537. Most of the available literature on corrosion of steel in simulated radio active waste environments pertains to nitrate induced stress corrosion cracking (Subramanian & Mickalonis, 2005). The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV). Corrosion of steel and formation of Fe(II) and Fe(III) will affect adsorption and reduction of Tc species. The radioactive species can irreversibly be sorbed on the steel surface by oxidation of Fe(II) to more stable Fe(III) and fixed as less soluble Tc(IV)/Fe(III). The solubility of Tc species is also affected by other factors such as dissolved oxygen, local pH, temperature etc. How the corrosion behavior of steel will be affected in the presence of Tc species is not clearly understood.Cartledge (Cartledge, 1960) demonstrated that passivation of iron can be achieved in the presence of oxygen along with suitable inhibitor ions/molecules of the general formula XO4 n-, such as pertechnetate (TcO4 -). The pertechnetate ion is univalent. Since it is derived from a strong acid, no buffering action can be expected from this ion. The redox potential of the reaction (1) is 0.738 VSHE (Pourbaix, 1974)."

Jan 1, 2012

By Stephanie Singarayer, Damodara Reddy Chinnasane, Mike Yao, Danielle Pelletier

Mining at Vale’s Creighton Mine has been active for nearly 120 years in Sudbury, Ontario, Canada. Being the deepest mine in the Sudbury region, mining induced seismicity is a common occurrence at Creighton Mine. Over the past five years, 26 large magnitude seismic events ranging from 2.5 Mn to 3.7 Mn (Nuttli) have occurred. Out of these large magnitude events, three 3.0+ Mn events occurred between April 2020 and January 2021. The majority of the 3.0+ Mn events are believed to be the fault-slip type that could be linked to the known major geological structures and/or long-term effect of mining over many years. The recent large magnitude events are believed to be triggered by high induced stresses while mining the first few stopes of a new lower horizon in the top-down centre out mining sequence.

Apr 26, 2022

By Charles W. Frey

OF all the machinery used in mining work, mine cars are probably the most abused. They are hauled through water and muck, up hill and down grade, whipped around curves, bumped and jerked, and exposed to the ravages of the weather. However, as a general rule their lubrication is not altogether neglected. The mine operator may not heed the extra drag that a frozen conveyor bearing gives, but he is all too aware of the increased load that faulty mine car wheels put on his power plant. When the circuit breakers begin to fly, and when his mine loco- motives come out with only half the cars that they were able to carry a month before, then neglected mine car wheel lubrication becomes apparent, and woe to the person responsible.

Jan 1, 1938

By WILLIAM BOWIE

IN most human endeavors a knowledge of the terrain is essential to the effective carrying out of projects, but no line of work is more dependent on maps than theoretical and applied geology. Maps of a kind do exist for all of the area of the United States, but most of them are crude affairs and of little use in engineering, planning, and scientific research. Topographic mapping in the United States was initiated on a national scale by the U. S. Geological Survey and the organizations that were merged in its creation to make base maps for geologists. Their work could not be effectively done then and cannot be effectively done now without maps that accurately delineate the earth's surface. The distribution of the rock masses that contain valuable mineral bodies, or that by their intrusion brought them into existence, is the first step in a study of the mineral resources of the nation. This work requires three-dimensional maps, that is, topographic maps on which the land forms are shown by contours.

Jan 1, 1938

By Alberto Tremea

The eddy current system is universally recognized as a most suitable method to point out discontinuities or modifications on the roll surface. The automation of the controls through the implementation of sophisticated equipments on the grinding machine has favoured its employment in the roll shop. A big effort is still going on to clarify the best way to promptly identify situations that could be really unsafe for the roll life. The results presented in this paper have been obtained through an intensive activity conducted in field by Innse Cilindri on work rolls of finishing stands of hot strip mills. The correct interpretation of the eddy current signals and a good calibration of the automatic system have allowed, in many cases, a substantial optimisation of regrinding practices.

Aug 16, 2017

By Angel Rafael Arce Chilque

O presente trabalho trata do estudo micrográfico e mecânico de junta soldada a multipassesde tubo de aço API 5L X70, pelo processo manual com eletrodorevestido (SMAW) para os passes de raiz, enchimento e acabamento na posição vertical 3G. Em acordo com API 1104, o consumível escolhido foi eletrodo revestido básico E 9018 – M, a fim de atender a parâmetros de soldabilidade e permitir a comparação dos resultados com trabalhos anteriores. Foram realizados ensaios macrográficos e micrográficos qualitativos da junta soldada e do metal de base, bem como a medição da microdureza Vickers (HV) ao longo da junta e medição do tamanho de grão da região de superaquecimento. Ensaios mecânicos de dobramento, tração e impacto também foram realizados. Os resultados dos ensaios Charpy foram correlacionados com a estrutura metalúrgica, tamanho de grão e microconstituintes presentes na junta soldada.

Aug 16, 2017

By Maria I. De Rosa

The U.S. Bureau of Mines conducted experiments for predicting materials' ease of combustion (smoldering onset, smoldering, flaming, and decomposition rates) by means of submicrometer smoke particle characteristics for the development of a simple test method. The experiments were carried out in an approximately 20-L furnace, with a 10-L/min airflow through the furnace for a 14-min duration, at set furnace temperatures of 150°, 250°, and 1,000° C. The variables studied as a function of time were the onset time of smoke particles, time and duration of maximum smoke particle generation, average concentration of smoke particles, and particles' average diameter, mass weight loss, and furnace temperatures. Results show that the onset time of smoke particles is predictive of materials' ease of smoldering, and the time of maximum smoke particle generation and its duration, coupled with mass weight loss, are predictive of materials' ease of smoldering and flaming (depending on the experimental temperatures), and decomposition rates.

Jan 1, 2010

By Dr. Kyle Perry, Ryan Sibley

Rock blasting is an inherently difficult field to quantify independent & dependent variables and the specifics of how the energy interacts with the material for a number of reasons. Independent variables such as geology are innumerable and stochastic, thus, on a laboratory and full-scale basis these variables are assumed to be homogenous across the desired rock boundary. Dependent variables are difficult to quantify in the laboratory based on the specific aspect of the fracture mechanisms that caused the fracturing. The same variables are difficult to quantify in the field because of the shear amount of material being blasted. The energy interactions with the material are difficult to quantify due to the rate of the reaction and the lack of quantification of independent variables. The second main issue with laboratory scaled rock blasting is the nature of the small form-factor explosives required for use in a scaled setting. These explosives that are utilized, traditionally PETN detonating cord, have a greater ratio of potential energy converted to shock energy rather than gas energy when compared to traditional field explosives, such as emulsion or ANFO. Research over the past decades has indicated that gas pressure has the greatest contribution to rock blasting performance, such as fragmentation and material throw. The factor of varying ratios of energy production has not been discussed in any of the reviewed publications. Publications discuss dimensionless scaling, dynamic similitude, and length-based scaling, however, none of these scaling methods discuss the ratio of energy production. The main focus will be correlation of energy production ratio of shock versus gas to dependent variables. This paper analyzes previous publications within rock blasting and related field as they pertain to scaling procedures and will highlight the similarities and differences in the various publications and detail the observed omitted variables that possibly lead to skewed data.

Jan 21, 2025

By Chengjia Shang

Aiming at greatly increasing efficiency and saving budget, higher strength and larger-diameter pipes have been developed and applied for constructing long distance pipeline projects in China. At the same time, in order to produce pipeline steel with high strength, high toughness and excellent DWTT performances, it is critical to refine austenite grain by static recrystallization rolling. Therefore, this paper focuses on the brief introduction of development of pipeline projects in China and also on the basics research in the field of static recrystallization during austenite processing of Nb-bearing steel.

Oct 1, 2019