Search Documents

Laboratory tests were conducted to evaluate the silica collection efficiency of flooded-bed scrubbers with six different filter panel designs and at two operating velocities. Test results indicated that reductions in filter density negatively impacted respirable dust collection. Silica collection efficiency for the least dense filter was as much as 33 % lower than the collection efficiency of the densest filter. At the low operating velocity, the least dense filter allowed over 40% of the respirable silica dust in the scrubber intake air to pass through the unit, where it would be discharged back into the mine environment. Operation of the scrubber at the higher test air velocity increased silica collection efficiency, regardless of the filter panel tested. The density of the filter panels also impacted the quantity of air that is moved through the scrubber, with higher density filters reducing scrubber airflow. For each filter, the relationship between dust collection efficiency and air moving capacity must be considered to determine overall effectiveness for specific mine applications.

Jan 1, 1998

By K. N. Han

Coal is becoming increasingly important as a major energy source in the face of the world's depleting energy mainly based on oil reserves. Coal is by far the most abundant fossil fuel both in the United States and abroad. Currently, because of increased mine mechanization, the fineness of preparation plant feed is increasing. Further, in the future as the grade of coal diminishes and the sulfur content increases, upgrading preparation of coal is very important. Because the density of coal is less than that of rock materials that occur as impurities, coal is separated from such waste largely by gravity-controlled processes for particle size between 5 inches and 28 mesh. If the size of coal particles is below 28 mesh, froth flotation is a good method for upgrading fine coal. Previously, numerous investigators have tried to upgrade coal values by froth flotation(1-16) and have achieved moderate success. However, the recovery and grade of coals in the concentrates are not always satisfactory, especially when the particle size is small. In general, when the size of coal is below 100 mesh, the above methods suffer from poor grade and low recovery. The reason for this is that as size decreases, the effects of gravity diminish, and other forces take effect.

Jan 1, 1985

By R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (K088) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron-and steel making and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

"The 35th Annual American Mining Hall of Fame Awards Banquet and Fundraiser, sponsored by the Mining Foundation of the Southwest (MFSW), will be held at the JW Marriott Tucson Starr Pass Resort & Spa on Saturday, Dec. 2, 2017. This year, the Foundation will honor one living Hall of Fame inductee, two Medal of Merit recipients, four honorees from Mining’s Past and an Industry Partner for their respective contributions to the mining industry.Gary J. Goldberg will be the 2017 Hall of Fame Inductee and will serve as the keynote speaker at the awards banquet. Goldberg was appointed president and chief executive officer and joined the board of directors of Newmont Mining Corp. in March 2013. Prior to this appointment, he served numerous companies in key positions including Rio Tinto Minerals, US Borax and Coal & Allied Industries. At every appointment, he was able to improve safety concerns and reduce injury rates. While serving as chairman of the National Mining Association, Goldberg launched the CORESafety initiative and US Borax was the first mining company to receive the California Governor’s Environmental and Economic Award.The Medal of Merit will be awarded to John C. Lacy, a shareholder of DeConcini McDonald Yetwin & Lacy, P.C. and a director of the Global Law Center at the University of Arizona’s Law School. Lacy’s law practice concentrates on mining and public land law and encompasses transactional and title consideration involving acquisition of mineral rights. He played a crucial role in the revisions to the mining law of the Republic of Bolivia and the English translation of the mining laws and regulations of Mexico. Lacy’s expertise in mining law impelled the University of Arizona James E. Rogers College of Law to approach him to head the new Global Mining Law Center in 2015. The program now partners with the Lowell Institute for Mineral Resources and offers cross-listing of courses"

Jan 10, 2017

By Brian E. Davies, Bobby G. Wixson

INTRODUCTION The mining, extraction and refining of metals into useful materials is an honorable profession with an ancient and productive history. Civilizations have long depended upon metals for their implements, structures and machinery necessary for survival, growth, and development. Today, as in the future, metals and minerals are essential to the progress of mankind as we approach the 21st century with technologies and concepts that will require new concepts and production from the metal mining and processing industries. Today is the tomorrow we talked about yesterday and the implementation of new ideas is essential if we are to achieve "Frontier Technology in Mineral Processing". Unfortunately, the state-of-the-art mining, processing, smelting and refining methods historically employed were less than desirable environmentally, which has caused todays public to view the metal mining and processing industry with concern. Presently the ancient rock and chat tips connected with old Roman lead-zinc mines which were worked in Wales are causing stream contamination problems that must be corrected at considerable expense to the local governmental agencies (Firth, J.N.M., et al., 1981). However, improved progress has been made and the environmental control and clean-up procedures utilized by modern lead-zinc operations in the "Viburnum Trend" or "New Lead Belt" of South East Missouri may serve as a model to illustrate how alternative technologies, environmental concerns and cooperative efforts contribute to efficient mineral production within the confines of a U.S. National Forest region without significant environmental impacts. This area received international attention when it was opened within the boundaries of the Clark National Forest in the mid 1960's. By 1970 it ranked first in the world by producing 432,576 short tons of lead ore and has since continued in this position producing 451,153 short tons of lead ore in 1983 representing 91% of the total United States lead production (U.S. Bureau of idines, 1983). This production comes from a mining area approximately 40 miles long by 10 miles wide extending in a north-south direction. Geologically the lead is disseminated throughout the Cambrain age Bonneterre Formation, mostly a dolomite, at depths ranging from 700 to 1200 ft. (213.4 to 365.8 m). Galena (lead) is the principal ore mined with lesser quantities of sphalerite (zinc), chaleopyrite (copper) and silver being recovered as economic co-products. This new mining development in one of Missouri is most scenic areas could have led to a classic confrontation between industries and environmentalists. Instead, through the cooperation of industries, governmental agencies and university researchers, the Ozark environment has been protected, and may serve as a model for future coexistence of the mineral industry with the environment. Cooperative Program Development As early as 1965 five new mines and two lead smelters were being prepared for production and environmental concern was an essential part of that planning. All the mining companies became acquainted with representatives of the various federal and state agencies and scientists from the University of Missouri-Rolla (UMR). During the next six years, St. Joe Minerals Corporation, American Metal Climax, Inc., Cominco American Incorporated, Ozark Lead Company (Kennecott) and American Smelting and Refining Company participated in cooperative research efforts. The companies also participated in information exchange meetings, the development of improved analytical methods and the utilization of research findings in the modification or construction of pollution-abatement facilities. Early on research was carried out to determine background values and to establish natural baselines of trace metals in the surrounding environment. The unusual topography and drainage pattern of the mining area were helpful since it was possible to establish control sites and test sites below individual mine-mill operations to study waste-water effects on the receiving streams. The location of the ‘New Lead Belt', mines, mills,

Jan 1, 1985

By R. S. Kinasevich

As part of other work related to the studies of kinetic factors that influence the flotation of specific sulphide minerals, specially designed kinetic flotation experiments at Cominco included work done on -65 + 100 mesh and -100 + 150 mesh, high purity galena. The flotation collector used was sodium isopropyl xanthate containing radioactive sulphur-35. Radiation monitoring of the galena fractions from stage flotation tests indicated that the adsorbed radioactive xanthate was uniformly distributed among the floated fractions and the non-floated, or residual portion of the galena. This anomalous behaviour could not be correlated to changes in Seebeck coefficients, to lattice distortions, or to the nature of the mineral surface as revealed by infrared spectroscopy and by microscopic measurements.

Jan 1, 1970

By Robert E. Moore

Investigators have attempted to develop lime refractories on a scale for broad applications in the metal and ceramic industries for several decades. There was a flurry of activity in the early to mid-fifties but no commercial developments were forthcoming. The literature of that period yields little information on plant trials. A major factor suppressing past interest in lime has to have been the high success with the application of magnesic and dolomitic materials. These materials, usually tar-bonded or impregnated, have become the refractories success story of the past two decades, especially in BOF applications. It is safe to say that their development and application has essentially plateaued, and that work today is focussed on finding cheaper paths to produce MgO-based refractories. For example there are efforts underway to extract MgO from mineral magnesite and to combine natural dolomite with MgO1. Beginning in the late sixties, rather intensive research began on the development of CaO brick, especially in East and West Germany, in Poland, and other communist bloc satellites, 'and also in Italy and Spain. One speculates that the motivation was a regional shortage of good magnesia and dolomitic material. Of course, There has always existed the prospect of cost savings should it be possible to use raw limestone as the starting material. Quite a large literature has appeared treating of these developments which in the early seventies had already reached full plant scale trials and uses. Some of the directions followed in the research have led to novel methods of brick manufacture.

Jan 1, 1985

By J. A. Mielczarski

An infrared external reflection spectroscopy (ERS) technique has been developed to study the structure of the adsorbed layer of ethyl xanthate formed on copper and natural chalcocite (Cu2S) electrodes. The infrared technique provides information concerning the identity and the orientation of the adsorbed species at monolayer and submonolayer coverages. X-ray photoelectron spectroscopy (XPS) studies have also been conducted to monitor changes at the surface. The results show that the first oxidation peak on the voltammograms for copper and the first and second oxidation peaks on the voltammograms for chalcocite electrodes are not characteristic of a chemisorbed xanthate species, which is contrary to what has been reported by other investigators previously. As evidenced by the XPS spectra, there was an increase in sulfur relative to copper on the copper and chalcocite surfaces over the potential region where these oxidation processes occur. The spectroscopic results (ERS, XPS) indicate that the second and third (on copper) and the third and fourth (on chalcocite) oxidation processes recorded on the voltammograms are due to cuprous ethyl xanthate adsorption. The orientation of the adsorbed molecules of xanthate was observed to change with increasing surface coverage. Therefore, it has been concluded that xanthate can modify the copper and chalcocite surface in two different ways. At lower potentials, xanthate is a source of sulfur for the formation of a sulfur-rich surface. At higher potentials, an adsorption layer of cuprous ethyl xanthate is formed. Contact angle measurements show that both of these processes of xanthate surface modification lead to an increase in the hydrophobicity of the substrates.

Jan 1, 1990

By William R. Yernberg

Caterpillar introduced 21 new products during Caterpillar Press Days ‘96, held in June at the company’s proving grounds near Tucson, AZ. The event, billed as the largest product introduction ever held by Caterpillar, was attended by press from around the world. Most of the new products were demonstrated at Caterpillar’s Tinaja Hills Training Center in the Sierrita Mountains south of Tucson. Under the scorching Sonora Desert sun, the press was treated to demonstrations of the new equipment. After a display of the equipment’s power and capabilities, the press was given an opportunity to operate the new models and, in some cases, compare them with the old.

Jan 1, 1996

By H. F. Anderson

The Palabora Mining Company Ltd. is probably best known for its production of copper since 1965. The success of the PMC mine lies in the outstanding technical and highly organized efficiencies applied to the massive mining, transportation, and treatment operations necessary to produce profitable copper. We are not however going to discuss the well-known copper operation but the extremely successful recovery and marketing of Baddeleyite by the PMC group. Let us first review the extraction process at the Heavy Minerals Plant. Non-magnetic ground ore from the copper magnetic separators is processed in the Heavy Minerals Plant for the extraction of the "heavy minerals" uranium and zirconia (Baddeleyite). Thorium is also present as a potentially recoverable mineral. The content of the minerals in the feed is probably the lowest in the world to be treated commercially. Minerals are separated from the waste ore by a gravity separation process in which the high density minerals segregate preferentially in a waterborne system.

Jan 1, 1985

By Douglas J. Lacke

1974 marked the start of a new era for Climax Molybdenum Co., a division of AMAX, with the initiation of an open pit operation above the existing successful underground block panel caving mine. A number of problems posed a challenge to the Climax open pit. Highly fractured rock, old mine workings, permafrost, and more than 7.6 m/a (300") of snowfall forced changes in normal operations. Final pit wall design was altered. Production bench heights were lessened due to old workings. These and other modifications contribute to a highly successful open pit operation.

Jan 1, 1981

By W. M. Cross

Optical fibers have revolutionized the telecommunication industry, because of their ability to transmit large amounts of data over long distances. Without optical fibers many of the communication technologies on which business, industry and research rely would be impossible. In addition to their use as communication devices, optical fibers are often used as sensors. Despite the great promise that optical fibers have for the development of many types of remote sensing devices, few remote sensing devices have been built for use in the mineral industries. This paper will describe the use of optical fibers as sensors for surfactant adsorption at mineral surfaces.

Jan 1, 1995

By Charles J. Johnson

The United States is totally dependent on imports for all primary chromite and most ferrochrome supplies. Although the United States imports chromite and ferrochrome from a number of countries, the long-term future of chromite supplies appears to lie in southern Africa (Republic of South Africa and Zimbabwe) where 88 percent of known world reserves exist. Floreover, low mining costs and the availability of low-cost electricity for ferrochrome production gives South Africa a comparative advantage over most other chromite and ferrochrome-producing nations. A well-known problem faced by the United States is that when viewed from a longer-term perspective, the major sources of supply of metallurgical grade chromite and ferrochrome may be subject to disruption. The three countries that have caused the greatest concern have been the Republic of South Africa, the Soviet Union, and Zimbabwe. South Africa presents a particularly difficult problem because it may be subject to internal political unrest and/or U. N, economic sanctions. South Africa has increased its share of world chromium production from about 30 percent in 1968 to 62 percent in 1978.1

Jan 1, 1982

By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production; however, the thermal state of pellets in drying section is still unclear. In this study, the temperature distribution of drying section was investigated using computational fluid dynamics (CFD). Based on the calculated results of airflow velocity, space temperature distribution, and the temperature change of pellets, it concluded that there is a coupling effect in drying section in traveling grate. The gas with higher temperature in DDD transfers heat to UDD through the gap of the insulation board, and the temperature gradient of the pellet bed changed before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD was displayed in UDD in advance. Moreover, a contrast experiment was conducted to verify the model.

Feb 1, 2021

By Stanley R. Riggs

The rocks exposed in the phosphate district are of Neogene age and consist of clayey quartz and phosphorite sands overlying phosphatic dolomite. The Bone Valley Formation is redefined as a marine phosphorite containing primary phosphorite and abundant terrigenous sediments. It contains a Middle Miocene vertebrate and invertebrate fauna and conformably overlies the Hawthorn Formation containing similar invertebrate fauna. A new, unnamed formation, with Pliocene and Pleistocene fauna and containing reworked phosphorite, overlies the Bone Valley disconformably. Its phosphorite is derived from the subjacent Bone Valley by post-Middle Miocene erosion and deposition in stream channels and marginal marine environments. The Bone Valley contains two main types of primary marine phosphorite. Orthocbemical phosphorite, a direct precipitate of microcrystalline phosphorite (microsphorite), occurs as a cement or binder in thin beds. Allochemical phosphorite consists of clastic phosphorite particles that were originally formed as microsphorite on another part of the shelf. Microsphorite was deposited in a very shallow open marine environment which had an abnormally high phosphorous content caused by upwelling currents. The mechanism of deposition is still in doubt, but organisms probably were a major factor. Soon after deposition, microsphorite was indurated, periodically torn up, and the resulting fragments transported and deposited elsewhere on the shelf. These processes account for a great portion of the clastic phosphorite in the Miocene deposits of Florida. The primary fossil skeletal material is of minor importance.

Jan 1, 1965

By B. C. Darst

Developments in the agricultural use of potassium (K) have been based solely on the essential role K plays in crop production. Crop plants cannot complete their normal life cycle if K is deficient or absent. In fact, no essential plant nutrient other than nitrogen is required in greater quantities. Table 1 shows the amounts of K some crops take up from the soil. Although the exact functions of K in the plant are not well known, its primary role seems to be tied to plant metabolism. Potassium is vital to the process of photosynthesis. When K is deficient, photosynthesis declines, but respiration increases. These two K-deficient conditions. . . reduced photosynthesis and increased respiration ... lower the plant's carbohydrate supply, the end result being poor agronomic crop production. Potassium is also essential to several other plant functions, including the following: 1) Protein synthesis. 2) Water use efficiency, through the influence of K on stomata opening and closing, to maintain the turgidity in plant leaf cells. 3) Translocation of heavy metals such as iron and zinc. 4) Ionic balance. 5) Control of enzyme reactions within plants.

Jan 1, 1985

By Robert A. Bauer

Investigations of bedrock within subsided areas over abandoned coal mines reveal) very little disturbance of the bedrock. In areas that have surface subsidence of .3 to 1 m (1.0 to 3.25 ft), examination of cores from exploration drilling and investigations of the boreholes by means of closed circuit television have shown that fractures are spaced at least .9 to 3.6 m (3 to 12 ft) apart and are located within a zone 6 to 15 m (20 to 50 ft) above the collapsed area in coal mines 42.6 to 112.7 m (140 to 370 ft) deep. The dip of the fractures ranges from 25 to 60 degrees, cutting across nearly horizontal sedimentary bedding planes. Typical core recovery is 80 to 95 percent within the subsided areas and 100 percent outside the subsided areas.

Jan 1, 1984

By A. Kaina

The San Luis deposit is one of the few documented gold deposits on a detachment surface. This paper presents mineralogic and geochemical data that was gathered to characterize the mineralization, classify the ore deposit, and provide details of the ore forming process. Included are data on the paragenesis; alteration-mineral assemblages major and trace element geochemistry, and fluid inclusions. The San Luis deposit occurs on the western slope of the Sangre de Cristo Mountains adjacent to the San Luis Basin about 5 miles northeast of the town of San Luis in Costillo County, south-central Colorado. Mineralization was discovered in the district in the early 17th century. Production began in 1890 on lead-silver ores from which the district took the name the old name of "El Plomo". From 1897 through 1934 gold was intermittently produced. Battle Mountain Gold Company took an option on the property in 1987 and proved on ore body comprising an eastern block that has 1,277,300 t ore at a grade of 1.68 g/t and a western block of 9,744,000 t with a grade of 1.34 g/t. Production began in 1990. A companion paper by Benson (1994) describes the San Luis district and the ore body, hence the reader is referred to this or Robert and David (1990) for details of the geology from which the following is summarized.

Jan 1, 1994

By Tim Haldane

Cyanide consumption at the Gold Fields Operating Company Mesquite Mine has shown a steady decline since the heap leach operation started up in 1986. A series of solution strength changes and equipment design improvements have resulted in a reduction of sodium cyanide consumption from peak levels above 1.0 pounds NaCN per ton of ore in 1986 to current levels at 0.15 - 0.20 pounds NaCN per ton of ore. Aside from the obvious cost benefits associated with this reagent consumption reduction, the property has also enjoyed environmental benefits which go hand-in-hand with these cost savings.

Jan 1, 1990

By Anna Gustafson, Sohail Manzoor, Håkan Schunnesson

Sublevel caving operation relies on the estimation of ore grade at drawpoints, as the mine management uses grade to decide whether the material at a certain ring should be loaded or abandoned. Grade is estimated in various ways, including visual estimation, density-based calculation, and sampling and assay methods. The grade estimation at the world’s two largest underground iron ore mines owned by LKAB in northern Sweden is based on the density difference between ore and waste. The calculations assume a constant swell factor, a theoretical fill of 100%, and a linear relationship between bucket weight and material grade. This study evaluated these assumptions in detail based on the loading data for 12,237 buckets and concluded that the method has some shortcomings which render the assumptions invalid. Further research is required to deal with these shortcomings to improve estimation of the material grade.

Oct 17, 2022