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By J. P. McDonald

Exposure to particulates containing metals and metal fumes (PCMMF) is a potential concern in ore refining and smelting. Some metals of primary interest are arsenic, cadmium, copper and lead, which have been linked to various adverse health effects. The current National Institute for Occupational Safety and Health (NIOSH) sampling method for metals in particulates requires the use of a filter, precision airflow pump and laboratory analysis. A major concern with this method is the one-to-two weeks? wait before laboratory results are available for use in determining if additional controls are needed to assure adequate exposure protection for workers. Particulates containing these metals were sampled during sixteen sampling events at a copper smelter using the traditional NIOSH methods. Monitoring of particulates was simultaneously conducted using a TSI 8520 Dust-Trak real-time aerosol monitor with a 10-µm-cutpoint sampling inlet. NIOSH analytical methods related to particulates and metals (methods 0500, 0600 and 7300) were used to determine particulate mass and individual mass contributions of metals on sample filters. Linear regressions with y-intercepts forced to zero were developed to determine the relationship between the PM10 measurements recorded by the DustTrak and laboratory-reported total particulate mass, PM10 and respirable arsenic, cadmium, copper and lead concentrations. These linear regressions yielded correction factors that can be applied to DustTrak readings to obtain total particulate mass, PM10 and respirable concentration estimates for each of the four metals. The R2 (coefficient of determination) values from the linear regressions ranged from 0.65 for total lead to 0.91 for total copper. These results suggest that the DustTrak may produce real-time data useful in providing estimates for airborne concentrations of arsenic, cadmium, copper and lead in copper smelter particulates.

Jan 1, 2011

By Terence P. McNulty

Gold-bearing outcrops were discovered in 1862 by Union soldiers garrisoned at Needles, CA, near the northwest corner of the future State of Arizona. Sporadic mining began several years later, but engineered shaft sinking and mill construction were not adopted at Oatman and the neighboring camp of Goldroad until about 1900. Geological interpretations in 1915 enabled major production during the next decade. In the late-1930s, USSR&M built a new mine and mill in Gold Road and the District flourished until closure by Federal Order L-208 in October 1942. For about a decade, Oatman’s mines were among the largest gold producers in the American West.

Feb 1, 2024

By Francisco J. Sotillo

Using new ecological-natural-organic depressant for gangue and pyrite with antibacterial properties (control of acid mine drainage) with new improved xanthate collectors using rheology additive not chemical reacting with xanthate resulted in better sulfide flotation. Rougher-scavenger lead flotation tests were conducted increasing the concentrate grade from 7.07% Pb to 13.44% Pb, enhancing selectivity. Lead recovery increased from 64.08% to 79.38% and 80.40% using only the new depressant, and improved xanthate Z-11 and Z-4, respectively. The results demonstrated that the new depressant was selective and efficient, and the new improved xanthates stronger more selective collectors.

Feb 22, 2026

By Michael Edesess

The salt gradient solar pond has been the focal point of accelerating international attention and interest in recent months. Only recently have most investigators in the renewable energy field come to realize the versatility of the solar pond, and its ability to overcome certain problems usually associated with solar technologies. These realizations, together with clear demonstrations in Israel and elsewhere of its technical feasibility, have combined to bring the solar pond to the forefront of renewable energy technologies. The solar pond is a natural or site-built pond, about one to five meters or more in depth, which has been altered to retard the loss of absorbed solar energy. The absorbed solar energy is usually lost through upward buoyancy of the warmed water, followed by the loss of its heat to the atmosphere. The chief solar pond technology -the salt gradient, or "nonconvective" solar pond-prevents this upward buoyancy by means of a vertical density gradient achieved with dissolved salt. The deep waters in the solar pond reach high temperatures, up to and even above the boiling point of pure water.

Jan 1, 1981

By K. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 meters (1MPa, tensile strength) in the rock mass, a distance that is sufficient to impact the pit-scale slope over the long term. In addition, the damage zone was calculated using the reasonable assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone ? up to 5.6 meters (30MPa, 30% of the compressive strength) ? indicates that microfracturing can occur throughout the entire rock mass in the blasting area. Finally, an economic analysis was conducted by comparing two reasonably assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond?s law after increasing the blast energy from 180kcal/t to 350kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. An optimal blast design should consider both slope stability (safety) and downstream comminution energy (production).

Feb 23, 2014

By John J. Simmons

There is considerable interest in the iron and steel industry in the development of technologies that can reduce carbon dioxide emissions, as the iron and steel industry is the third largest producer of carbon emissions in the world, after automobiles and the power generation industry. The E-Iron Iron Nugget Making Process, invented by Dr. Komar Kawatra and Dr. Tim Eisele, provided a major breakthrough in the iron making process as the process uses biomass in the form of hard wood or soft wood as the reductant in the place of coal. Dr. Kawatra recognized that biomass is rich in both carbon monoxide and hydrogen, two important reducing agents. This resulted in initial experiments conducted by Dr. Kawatra and Dr. Eisele in the laboratories of the Chemical Engineering Department of Michigan Technological University (Michigan Tech) that prepared self-reducing pellets with wheat flour as the reductant and limestone/dolomite as the flux. Initial results were encouraging so they extended their work to include hardwood, which is in huge supply in the forests of Michigan and Minnesota, as the reductant. Dr. Kawatra has also applied the E-Iron Technology to other iron bearing minerals to produce pig iron grade iron nuggets. He used the E-Iron Process to convert red mud, a high iron waste product of the aluminum industry, into pig iron nuggets with the rare earth elements reporting to the slag. This work resulted in a patent with Dr. Kawatra and Dr. Michael Archambeau named as the inventors. Dr. Kawatra then extracted the rare earth elements as a separate high value bi-product using oxalic acid, which he produced from carbon dioxide. Dr. Kawatra also conducted a test program that produced pig iron nuggets from New Zealand beach sands. The vanadium in the beach sands was retained in the iron nuggets, recoverable as a valuable bi- product in a separate process. The titanium dioxide in the beach sands reported to the slag. This demonstrates the potential use of the E-Iron Process to convert the large ilmenite reserves in Northern Minnesota into pig iron and titanium dioxide. Another use of the E-Iron Process discovered by Dr. Kawatra was its ability to produce iron nuggets from manganiferous ores. Dr. Kawatra was able to direct the manganese into either the metal or slag by adjusting process temperature. The above discoveries are included in several patents that were assigned to Carbontec Energy. This presentation will only address the use of the E-Iron Process to produce pig iron nuggets from steel mill waste and un-pelletized, mid-grade iron ore. Carbontec Energy Corporation agreed to sponsor additional research directed at improving this new technology that would later be trade named, The E-Iron Process. Carbontec Energy conducted further work that proved that the E-Iron technology could also convert steel mill waste into metallurgically acceptable iron nuggets. Carbontec also collaborated with the Lawrence Livermore National Laboratory and Purdue University Northwest to conduct a Department of Energy (DOE) sponsored program that would use their high performance computer capability to both verify and model the E-Iron Process. Purdue University Northwest reported that the E-Iron Process can produce pig iron nuggets with 85% less carbon emissions than a blast furnace. The E-Iron Process is similar to the ITmK3 process, developed by Kobe Steel, that also produces iron nuggets but uses coal as the reductant.

Feb 1, 2025

By Erika Moonin, Jim Nickerson, Marcus Jensen

"This paper will explain how the Contractor and Owner avoided a contractual dispute involving characterization, impacts, and final remedy for challenging ground conditions encountered during drill and blast excavation of the starter tunnel required for launch of the tunnel boring machine (TBM). During excavation more than 600 feet underground, the Contractor encountered a large complex fault zone subject to more than 14 bar of water pressure. Successive ground inflows from the fault complex over a six-month period presented significant technical and partnership challenges for the team and ultimately delayed the project by nearly one year. This paper will discuss how the Contractor, Owner, and their respective consultants worked together to address these challenges, make decisions, and ultimately move the project to successful completion. PROJECT BACKGROUND AND NEED Seven states of the western United States of America rely heavily on the Colorado River and its tributaries for their water supply. The primary source of water for the Colorado River is winter snow that falls in the mountains ringing the Colorado River basin, including the Rocky Mountains, the Wind River Mountains, and the Uinta Mountains. Flows in the Colorado River vary significantly from year to year, depending on the amount of snow and rain deposited in the basin. During the 1980s and 1990s, snowfall was relatively abundant and Colorado River flows were high on average. Beginning in the year 2000 and continuing to the present day, snowfall has been well below documented historical averages and Colorado River flows have diminished. In fact, a trend toward diminishing flows is evident during the period of the historical record. This variability in Colorado River flows and the trend to lower flows is represented in the following Figure 1."

Jan 1, 2016

By M. Jaramillo

The Expanded West Pit of the 15 MTY El Cerrejon Mine will reach a maximum depth of270 m. Slope stability evaluations indicated that this depth, combined with structural complexities, would create a serious risk of footwall instability. Stabilization call for anchoring the footwall by installation of cable bolts, 9 to 33 m long, of multi-strand steel cable. For each of the 15 m high mining benches, a row of bolts is installed with variable horizontal spacing, depending on dip magnitude. Cable bolting is now standard operating practice and 11800 bolts will have been installed during the life of the mine.

Jan 1, 1995

By Albert R. Rule

Beneficiation studies were made by the Bureau of Mines to develop a process for concentrating phosphate minerals from the altered rock of the Phosphoria Formation. This report describes research on intermediate - and marginal-grade ores from southeast Idaho, The process developed consists of attrition scrubbing and sizing to produce a coarse concentrate; desliming at about 800 mesh (18.5 microns); flotation of the fine sands; roasting of the combined concentrates for removal of organic carbon and combined water; and leaching with SO2 for removal of magnesium and nonapatitic calcite. Results of continuous tests on three different ore types showed that approximately 80 percent of the available phosphate can be recovered at a grade suitable for phosphoric acid production. While leaching with SO2 is not necessary for all ore types, it is an important step in purifying concentrates containing excessive magnesium.

Jan 1, 1966

By P. J. Ryan

Phelps Dodge’s Candelaria copper-gold mine is located 20 km (12miles) south of Copiapó in northern Chile’s Atacama province (Region III) (Fig. 1). The Candelaria Mine is about 800 km (500miles) north of Santiago and 75 km (47 miles) east of the Pacific Ocean. Its elevation is 600 m (1,970 ft) above sea level. The Copiapó River Valley is 6 km (4 miles) northeast of the mine site. It is the only major source of water in this arid region. The average rainfall is 14mm/a (0.5 in./year). During 1995, the mine produced 521.4 kt (574,800 st) of copper concentrate containing 150 kt (165,000 st) of salable copper and 3 t (98,800 oz) of gold. The 1995 unit cash cost was less than 50 cents/lb of copper. This makes Candelaria one the world’s lowest cost copper producers.

Jan 1, 1996

By J. N. Cox

Coal preparation is based on the properties of noncombustable materials (impurities) in coal being different from the organic constituents. The most commonly used property difference is density, via its affect on settling rates; and either gravitational or centrifugal forces can be used to remove impurities. However, examination of various particles settling rate correlations shows that at smaller sizes, particle drag becomes a very important factor. Classification, based on differential settling rates, becomes impractical and some property other than density must provide the basis for fine coal cleaning. Froth flotation and agglomeration employ differences in surface properties to clean coal. These methods are very successful except that the oxidized surface of a pyrite particle is somewhat hydrophobic and will tend to be collected with the organic portion of the coal. Surface property cleaning techniques have not been very effective in rejecting sulfur, except for two-stage flotation.

Jan 1, 1984

By Gregory Rumbaugh, Christopher Mark

Recent pillar collapses have caused five large airblasts in underground U.S. limestone mines. One of these events injured three miners, but all of them put many other miners at risk. To better understand the hazards, Mine Safety and Health Administration (MSHA) conducted a comprehensive review of the international literature on airblasts. More than 40 airblast cases have been documented, in a wide variety of minerals. Experience shows that miners that are in the direct path of the air as it moves towards the mine exits are at the greatest risk. The paper describes a risk management methodology that can be used to evaluate the level of hazard throughout the mine and aid in the selection of controls to reduce the risk. The paper concludes with a detailed case history of an actual pillar collapse and airblast.

By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By H. Ehnes

"“Industry 4.0” – “Mining 4.0” - perhaps you have already heard of these terms? These keywords signify the next stage of industrial production. The internet and production technologies are growing closer together. Machines can communicate with one another, wherever they may happen to be located. The “Internet of Things” is the appropriate term. But what does SAFETY 7.0 mean? It is both brand new and traditional at the same time. It also has to do with the success of companies, with efficient production. And yet there is a great deal more at stake. It has to do with our lives and our safety – the supreme commodity in this world. What exactly SAFETY 7.0 means, what the number 0 stands for and the meaning of the number 7, and what this all has to do with mining will be explained in the following article. Mining is a fascinating undertaking. Mining is indispensable for a country’s economic development, whatever that may concern: infrastructure, energy supplies or raw materials for industrial production. Mining has brought forth many technological developments and innovations that can currently be found in our daily lives. Mining is impressive, grandiose and repeatedly fascinates mankind with its immense dimensions. Miners throughout the world still work hard and, for this reason, are bound to one another in a special way. In mining, every man looks out for the other; you have to be able to rely on each other. That creates a strong bond. The other side of the coin is that mining and disasters belong to normality in the media and thus also in our perception. Accidents at work and even catastrophes occur in mining, quarries, or raw material operations almost on a daily basis somewhere in the world. They are often associated with extremely serious injuries, or even a fatal outcome, for the miners affected and, in turn, dramatic consequences for the families of those involved. It could be in China, India, Russia, or somewhere in Africa, Asia or America – it mostly does not happen in front of our door or in our neighbour- hood. Perhaps because of this in the daily concert of negative headlines, we do not register these catastrophes any more in our minds. We write them off under the heading “Nothing special”, since there are, day in day out, more terrible news items about wars, civil wars, famines, or ecological disasters. Things only really change if there is a dramatic number of deaths or when we are personally affected, close by in the vicinity, or can witness the rescue action live. In Europe, these three mining disasters in particular have recently generated media resonance:"

Jan 1, 2016

By G. Bylapudi, A. Spearing, J. Weber, K. Mondal

U.S. National Institute for Occupational Safety and Health (NIOSH) reports state that about 100 million rock anchors are installed annually in U.S. coal mines (Tadolini et al., 2006), and rock-related safety remains an issue. The majority of these coal mines have conditions that make corrosion probable in the longer term. Despite this, very little research has been performed to analyze corrosion and its effects on rock anchors in coal mines. To further evaluate the effects of corrosive conditions in coal mines on rock anchors, three different experiments were conducted during an initial Illinois Clean Coal Institute (ICCI)-funded project from 2008-2009. The results of these experiments were further studied, with additional tests, in the extended ICCI-funded project during 2011-2012. The experiments were destructive testing, electrochemical testing (potentiodynamic polarization tests) and open circuit potential (OCP) testing, conducted in order to study corrosion in environments similar to those found in Illinois coal mines with a focus on major rock anchor types typically installed underground. Destructive test results showed highest reduction in peak strength at higher pH and temperature. From the destructive test results, epoxy-coated and galvanized anchors were observed to be better when compared to uncoated. Electrochemical testing was performed to find the corrosion potential and corrosion rates of ASTM A615 steel grades 40, 60 and 75 in four different solutions of varying sulfur content at ambient temperature. The effect of temperature and pH levels on corrosion potential and corrosion rates of steel grades were also evaluated with additional electrochemical testing, where an increase in temperature with all other constant conditions caused a significant increase in the corrosion penetration rate. OCP data indicated higher corrosion potential values (-mV) for rock anchors in wet areas, when compared to those from the dry areas. OCP test results of the rock anchors from the laboratory corrosion chambers were similar to those measured in the sampled coal mines.

Jan 1, 2013

By R. K. Clifford

The formation of elemental sulfur on the surface of sphalerite in aqueous systems was investigated. Hallimond tube flotation tests showed that unoxidized sphalerite did not float well without a collector. Flotation recoveries of greater than 95 percent were obtained without the use of a collector or frother after the sphalerite had been reacted with oxygen under pressure and water at pH 2.8 at room temperature. High flotation recoveries also resulted when sphalerite was reacted in acidic solutions in the presence of platinum sponge, titanium sponge, 316 stainless steel, copper turnings, or [10-5M++]. Conditions which produced high flotation recoveries of sphalerite yielded contact angles of 37° to 40° and also produced elemental sulfur. The increase in elemental sulfur on the surface of sphalerite was detected by elemental sulfur extraction with petroleum ether, electron spectroscopy for chemical analysis (ESCA), and the electron beam microprobe. The quantity of elemental sulfur formed was insufficient to be detected by infrared or Raman spectroscopy, or by the optical microscope or by the scanning electron microscope. An electrochemical type reaction for the production of elemental sulfur in acidic solutions was proposed. The cathodic reduction of oxygen was the slow step which needed to be catalyzed. A chemical type reaction which produced H2S rather than elemental sulfur was evident in non-oxidizing conditions.

Jan 1, 1974

By H. Sevim

This paper identifies and formulates the probabilistic nature of underground coal face operations using the Semi-Markovian theory. Through this theory the probability of coal flow from a face is obtained for any given time t of a shift. These probabilities are used for determining the capacity and operating policy of a surge tank located at the shaft bottom.

Jan 1, 1984

By S. R. Hutchins

Several refractory sulfide and carbonaceous gold ores were examined to determine whether microbial pretreatment could be used to enhance gold recovery. Test samples were biologically leached using unique, thermophilic microorganisms to solubilize iron sulfide minerals. Gold recovery from sulfide ores and concentrates was enhanced following pretreatment with the thermophiles; responses varied widely for the individual materials. Although bioleaching had little effect on the preg robbing characteristics of the carbonaceous gold ores, cyanidation of the bioleached residues yielded higher gold recoveries than cyanidation of the native ore. By combining bioleaching with abiotic processes designed to inhibit preg robbing, gold recoveries of 83-98% were obtained from carbonaceous ores yielding 10-50% gold recovery by direct cyanidation.

Jan 1, 1987

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-yd3) transit mixer and a shotcrete spray boom carrier, is used bya 2-man crew to transport and place up to 25 m3 (32 yd3) of steel-fiber reinforced, dry, silica fume shotcrete per II-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control is performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1991

By Langtry E. Lynd

Ilmenite concentrates prepared from beach and dune sands of Florida, India, Australia, and other localities deviate to varying degrees from the theoretical composition of pure ilmenite, and generally contain more Ti02 than the formula FeTiO3 would indicate, and some Fe203. This variation in composition is due to different amounts of altered ilmenite in the concentrates.(l) The alteration has been shown to take place by oxidation and leaching of the iron in ilmenite, to yield residual products consisting of amorphous or very finely crystalline titanium dioxide and ferric oxide, Other studies (2) have stressed that ilmenite may alter first to an amorphous titanium-iron oxide, or to an amorphous mixture of titanium and iron oxides, with later alteration to crystalline titanium dioxide. There has been some speculation as to whether alteration of ilmenite is usually caused by weathering or by hydrothermal processes,(3, 4, 5) Three main methods of approach were used to study the mechanism and rate of ilmenite weathering, (1) Etch tests were used to learn the relationship between crystallographic orientation and the rate of chemical attack on ilmenite. (2) Altered ilmenites in New Jersey sands were compared with ilmenite in rocks of the area from which the sands were probably derived, (3) Experiments were carried out to determine at what rate, and by what agents, originally fresh ilmenite could be altered in the laboratory under simulated weathering conditions.

Jan 1, 1959