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By Richard C. Corson

The objective of blending materials in a bedding pile is to reduce the variation in successive samples taken from the materials to be blended. In designing a bedding and reclaiming operation, several mechanisms are available to effect the reduction of variability, or increase in homogeneity, of the materials. These mechanisms can act before stacking, in the stacking process, in reclaiming and after reclaiming. In evaluating alternative methods of stacking and reclaiming, the potential user must judge each method on the basis of certain criteria; the capital cost of the equipment, the allowable absolute variability of the reclaimed product and the effectiveness of blending. Several stacking and reclaiming methods have been tested using a computer simulation. Based on the results of this program, factors were developed to describe the effectiveness of blending for chevron stacking of discrete materials and preblended materials, bucket wheel reclaiming and drum reclaiming. From these factors, the total effectiveness of a combined stacking and reclaiming system can be determined.

Jan 1, 1985

By P. Tsang

To gain insight into the current status of pillar design practice in the underground coal mines of United States, a survey has been undertaken in the late 1993 and early 1994. A total of 552 room-and-pillar mines and 75 longwall mines have been surveyed to collect general, geological and mine plan information. The collected information are critically analyzed with special emphasis on the pillar design criteria adopted in these mines. A safety factor analysis has also been carried out for the pillars in room-and -pillar mines.

Jan 1, 1995

By Richard A. Thomas, Connor B. Brown, Thomas H. Dubaniewicz, Teresa Barone

Electric vehicles powered by lithium-ion (Li-ion) batteries are being developed by mining vehicle manufacturers as a replacement for diesel-powered vehicles. Explosion-proof (XP) enclosures are frequently employed to enclose electrical ignition sources in gaseous underground mines to prevent the spread of an internal methane-air explosion to a nearby explosive atmosphere. Due to thermal runaway (TR), Li-ion batteries have the potential to cause pressurized explosions in an enclosed structure. Past research has shown the potential for well-confined Li-ion cell TR to drive pressures beyond the conventional pressure specification for XP enclosures. Researchers at the National Institute for Occupational Safety and Health (NIOSH) used an Accelerating Rate Calorimeter (ARC) to induce thermal runaway of Lithium Titanate or Lithium Titanium Oxide (LTO) type 18650 cells enclosed within containers with various volumes and found an inverse power relationship between the TR pressure and available free space. The results were similar in magnitude to that of lithium iron phosphate (LFP) cells, which were used in prior testing. Temperatures, gas amounts, and TR pressure-rise rates were also recorded. The data indicate that with enough free space, the pressures can be lowered below the conventional pressure specification for XP enclosures.

Feb 1, 2024

By Chunbao Sun, Qi Liu, Chao Wang

Entrainment is a process by which fine and ultrafine particles are transferred to the flotation froth from the top of the flotation pulp, and eventually discharge to the concentrate product, evenwhen they are not attached to gas bubbles. Therefore, entrainment can be considered as a two-step process, one at the upper layer of the pulp to the flotation froth, and the other from froth to the concentrate. Entrainment is inevitable for both hydrophobic and hydrophilic minerals and is one of the significant factors affecting concentrate grade. This paper provides a comprehensive review of the entrainment mechanisms and entrainment models, as well as a summary of the main factors affecting entrainment and the techniques thatmay be used to lower or eliminate entrainment. Based on the review, we point out that selective aggregation of fine and ultrafine gangue minerals using appropriate process aids (polymeric depressants, inorganic salts, etc.) to increase their particle sizes appears to be a convenient and economical method. Directions of further research along this line are discussed.

Aug 31, 2020

By Michael Ferrell

The primary reason pigments are used in plastics is to impart a desired color to the plastic. Color is one of the more important assign considerations associated with today's market oriented society. Secondary reasons for adding pigments to plastics include: 1. Improved UV stability 2. Enhancement to selected physical properties 3. Changes in optical properties Pigments may be used at loadings as high as 20% or as low as .001%. Generally the loading levels are between 0.2% and 2.0%. Pigments may be added to the plastic either by the manufacturer of the plastic, or by the user of the plastic. If the customer buys material that is already colored, it is referred to as "pre-colored". If the customer buys uncolored plastic and adds colorants, the process is referred to as "in-house" coloring.

Jan 1, 1985

By Xiyu Gao, Yi Yang, Mark I. Pownceby, Shuiping Zhong, Miao Chen

In the present study, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray absorption near edge structure (XANES) spectroscopy, and Raman spectroscopy were used to investigate the effect of chloride ions on chalcopyrite bioleaching and chemical leaching at 25 °C. The leaching results show that the addition of chloride ions suppressed the dissolution of chalcopyrite in both chemical and bacterial leaching. In chemical leaching, the solution redox potential in the experiment without Cl− stayed in a range more suitable for chalcopyrite dissolution compared with experiments with Cl− . In bioleaching, the bacteria activity was suppressed by Cl− leading to low dissolution rates of Cu. Surface morphology and chemical speciation studies confirmed the formation of potassium jarosite on the surface of the chalcopyrite leach residues. In addition, S K-edge XANES indicated the formation of trace amount of elemental sulfur and covellite on the mineral surfaces.

By George M. Anderson

The extraction of industrial minerals is usually confined to relatively small mining operations. The recent COSMAR (Committee on Surface Mining and Reclamation) report found that 93% of all mines in the United States were of the small unit variety. Also, of the total number of mines in the U.S. (15,279) 96% were in the industrial minerals (non-metals excluding coal) category. To break it down further, 86% were sand and gravel, and crushed stone operations. Therefore, we are talking about a very large number of small mining operations. If these small miners can afford to hire a college graduate, what kind of training should this person have beyond the normal mining engineering curriculum to best serve the problems that he or she will encounter?

Jan 1, 1981

By J. Rao Mokka

Extensive exploration has resulted in delineation of a massive sulfide district on the north flank of the east-central Alaska range. The district covers approximately 400 square miles and contains numerous stratiform; transported and some replacement type sulfide deposits ranging in size from less than 1 million tons to 20 million tons. Five types of ores were sampled for the study. Mineralogical analysis revealed that the minerals are too fine grained for conventional grinding and beneficiation. Hydrometallurgical studies were con-ducted using ferric chloride as a lixiviant. Ore microscopic studies as well as electron microprobe analyses of minerals in the raw samples and leach residues explained the low recoveries for certain elements as well as sources of impurities that need to be eliminated from the process streams.

Jan 1, 1991

Silver bearing bulk sulfide concentrates from several Peruvian mines were autoclaved in a 19 liter (five gallon) laboratory autoclave in Lima, Peru. Cyanidation of autoclaved concentrates following a hot lime jarosite destruction step extracted over 98 percent of the silver and over 95 percent of the gold. Autoclave operating parameters such as time, temperature, pulp density and autoclaved solids recycle were investigated and reaction rates determined. The problems of excessive heat generation, silver solubility during autoclaving, and formation of pellets containing unreacted sulfides were addressed. The data presented will be used to design a continuous autoclave pilot plant to pro-vide reliable scale up data for a 50 -100 ton per day facility.

Jan 1, 1992

By Roshan B. Bhappu

Although the economic importance of recovering copper by leaching of mine work dumps from open-pit operations has been realized for some time, serious attempts to understand and to improve such operations through scientific research has been made only in recent years. This progress report covers the results of chemical, physical, and biological studies pertaining to the dump leaching process and discusses salient features and parameters that may be helpful in improving such operations.

Jan 1, 1968

By Atta Ur Rehman, Kwame Awuah-Offei

"Information diffusion potential of a social media user affects how quickly information about a mineral project can diffuse through that user. If management can use social media and network analysis in community engagement programs to understand how fast and how far information will diffuse to communities and followers of particular social media users, it can selectively focus on the most influential users. This article proposes a method to examine the information diffusion potential of social media accounts. The work uses Gephi, an open source software, to extract and analyze data from different Twitter handles to predict their information diffusion potential. The work uses case studies of real Twitter users (e.g. mining news organizations and bloggers) associated with mining to illustrate the approach. The case study results show that there are significant disparities in information diffusion potential that will demand selective attention. This research will help mines develop effective social media engagement strategies.The mineral industry provides raw material for industrial activity to support society (Martens and Rattmann, 2001). Mines have changed from conventional mining practices to sustainable ones because of the negative impacts of mining in the past and increased public awareness (Wang et al., 2016). The concept of sustainable mining is getting mature, as stakeholders (e.g., governments, investors and host communities) are getting more involved in mining projects (World Economic Forum, 2014). The failure of mining companies to address the demands of these stakeholders might result in the failure to acquire a social license to operate (SLO) (Thomson and Boutilier, 2011). The SLO, if granted, is mutually beneficial to all stakeholders. Mines prefer being granted SLO and keeping it to avoid any kind of social unrest due to their operation (Prno, 2013; Moffat and Zhang, 2014). Mining communities can grant different levels of SLO ranging from withholding SLO to psychologically identifying with the project (Joyce and Thomson, 2000; Thomson and Boutilier, 2011).Most of the previous work to understand community perceptions and SLO in mining is generally qualitative (ICMM, 2012a; Thomson and Boutilier, 2011; Prno, 2013; Moffat and Zhang, 2014; IFC, 2014). In particular, there is limited work on how community perceptions change over time due to information diffusion (Boateng and Awuah-Offei, 2017). However, SLO changes with respect to time (Yates and Horvath, 2013), which can result in risks that are not easy to predict. Mine managers and engineers have a desire to understand these changes so as to mitigate these risks (Que and Awuah-Offei, 2014; Que et al., 2015)."

Jan 4, 2018

By Donald K. Sparling, C. Edwin Baker

The White Mesa uranium/vanadium mill is six miles south of Blanding, UT, on the Colorado Plateau, which has historically spawned more than 200 uranium mines. As uranium prices approached an all-time high during the mill planning period, Energy Fuels Nuclear Inc. anticipated the reopening of many of these mines, whose low grade ore suddenly looked economic. The company located the White Mesa mill close to these mines, to minimize hauling distances to the mill and give vendors added incentive to reopen or expand mine operations. A receptive local community, a relatively unencumbered trip through the regulatory maze, and some mill circuit innovations all helped to make the White Mesa mill a well functioning reality. From a strategic standpoint, and to begin ore stockpiling as early as possible, Energy Fuels constructed two ore buying stations and began receiving ore in early 1977. The buying stations were located at Hanksville and at what is now the Blanding mill site. Ore receipts at Hanksville did not materialize as anticipated and the facility has since been closed. The Blanding ore buying station is now an integral part of the milling operation. All ores, whether company, vendor, or for toll milling, are received at the Blanding station. The Blanding site was central to the plateau mines, and was well received by area residents, who encouraged the introduction of industry to the area. Residents viewed mill construc¬tion as an economic blessing and were prepared to accept the associated im¬pacts. Energy Fuels hired as many local people as possible for mill opera¬tions.

Jan 4, 1981

By G. Rinelli, Arthur F. Colombo, Donald W. Frommer

With the opening of the Tilden mine near Ishpeming, MI, a new era in iron ore beneficiation was begun. A description of a U. S. Bureau of Mines investigation is summarized to illustrate the selective flocculation-deslime-flotation process developed by the Bureau and used at the Tilden concentrator, which is also briefly described. The operating parameters for the selective flocculation-cationic flotation of an oxidized taconite from the Mesabi range are discussed. A water reclamation system using lime and a cationic flocculant was applied to reclaim the effluents from a 900-pound-per-hour flotation pilot plant. About 80 percent of water requirements were recovered, and the calcium content of the reclaimed water was found to be more important than clarity in influencing the selective flocculation and flotation processes. Although reclaimed waters with about 10 ppm calcium registered turbidities of approximately 5,000 ppm SiO2 equivalents, the concentrates produced using these waters contained 64 percent Fe and =5.0 percent SiO2 and had accompanying iron recoveries of 75 percent. Lower grade concentrates resulted from using reclaimed water with higher calcium contents and lower turbidities.

Jan 1, 1976

By M. Rotz

In the minerals industry today, the ?low hanging fruit? that once existed to debottleneck production and improve recovery, while meeting market needs for quality in mineral processing operations, are more and more difficult to find. Systematic methods for establishing plant mass flow, recovery, operational efficiency and control strategy in context with customer specifications provides the necessary insight and confidence for plant operators to prioritize improvement projects in order to maximize return on investment (ROI) for the site. The evaluation of aggregate and industrial mineral processing plants requires the following steps when projecting cost saving opportunities: collecting background data, conducting a base-line evaluation, analyzing specific unit-operation performance, defining investment options, prioritizing the selected improvement opportunities and the implementing process changes. The following paper describes the approach and challenges of developing an improvement plan for a dry and wet mineral processing operation.

Feb 23, 2014

By Hun-Joon Sohn

Chemical metathesis and electrochemical reductive conversion of chalcopyrite in the presence of cupric ions were studied in sulfuric acid solutions for temperatures up to 90°C. The process results in the displacement of iron in the chalcopyrite lattice by copper ions with rejection of ferrous ions to the aqueous phase. The rate of reaction was found to be very slow, requiring subsieve-sized particles for extensive reaction to occur. The reaction was insensitive to copper ion concentration. Stirred ball milling of chalcopyrite introduces lattice strain. The reaction rate with strained particles was markedly higher than with annealed chalcopyrite. The reaction rate was found to be diffusion-limited, showing two distinct reaction stages corresponding to the formation of CuS (covellite) followed by Cu1.8S (digenite). The experimental activation energy for the first stage was 102 J (24.4 kcal) and the second stage 123 3 (29.4 -kcal) per mole. The rate-controlling process is diffusion of lattice ions, probably iron. The enhanced rate after milling is attributed to a recrystallization process which provides new paths for diffusion along dislocations and grain boundaries.

Jan 1, 1984

By Michel Dagbert

In the exploitation of porphyry-type deposits, the quality of the ore is mostly defined according to its grade. Besides the simplest distinction, ore-waste, several grade categories may exist and they correspond to the different ways in which the ore is further processed. At the time of mining the selection of the different categories is done from extensive information available from blast holes. But planning has to be done before this information is available and it is necessary for the geologist to forecast, from exploration and development data alone, the possible outcome of the selection done later on a block, a level, or the whole deposit and ultimately predict the ore reserves and value of the deposit. A good statement of this problem has been presented at the 1976 AIME annual meeting by Williamson and Hueller (1976). They have shown that, if the cut-off values are directly applied to the estimated grade of blocks, a gross overestimation of the recovered tonnage of ore (14%) will occur. This problem, now termed "the vanishing tons problem" (DaVid, 1977) seems to be common in many open-pit operations and it has been explained several times (DaVid, 1972; Huijbregts, 1975). In order to solve it l.Jilliamson and Mueller proposed a solution based on compiling masses and masses of blast hole data available from mined-out portions of the deposit. They derived empirical correction factors which provide for every block, given its estimated grade, the expected tonnage and average -grade of each category of material within that block. The purpose of our work is to repeat the same exercise but ignoring the blast holes data i.e. we want to derive the correction factors from the only DOH data. Doing this, we are more in the real conditions where the valuation of the mine and are reserve analysis has to be made before production actually starts. Two possible ways to achieve this goal will be investigated and the emphasis will be on recently

Jan 1, 1977

By J. Platt

Debate over acid rain legislation has presented a moving target for coal and utility company planners attempting to figure out how legislation will affect their business environment. In spite of disagreement among experts, the prospect for continued change, and persistent --perhaps even growing --uncertainty, a great deal has been learned about coal market dynamics. This paper reviews progress and describes some of the major problems and controversies.

Jan 1, 1990

By X. Xie

The dissolution behavior of palladium powder in thiourea solutions has been studied. The variables studied included temperature, stirring speed, and concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was found to be chemical reaction controlled with an apparent activation energy of about 2S.3 kJ/mol.

Jan 1, 1995

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 D. N. Hillhouse

The economics of exploration target selection can be measured ultimately only against a company's success at developing mines. In the following brief history of the mine acquisitions of one company, Placer Development Limited, I try to identify the principal targeting parameters and the principal skills that came into play for each property and examine how these have changed with time. The process of target selection in exploration is directed: - first by corporate investment criteria which define objectives and acceptable levels of risk for pursuit of those objectives; - second by experience and skills which permit us to minimize risk; and - third by anticipation of future events relating to ore discoveries and changes in external risk factors.

Jan 1, 1984