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By J. Iannicelli

High intensity, high gradient magnetic separation can economically remove weakly paramagnetic contaminants down to 0 1 micron from industrial minerals This process is employed by all waterwashed kaolin producers in Georgia where seventeen huge magnetic separators are used to upgrade this product As a result, reserves of kaolin in Georgia have been doubled Design improvements have steadily increased the efficiency of separators and reduced power consumption below 300 KW for a nominal 65 TPH unit Beneficiation of ultrafine minerals is discussed based on pilot plant results on bauxite, ball clay, calcium carbonate, glass sand, talc, and numerous other minerals Operating parameters of the process are reviewed and some alternative equipment configurations discussed

Jan 1, 1983

By Ronald Allum

Arizona leads all other states in the value of gemstones produced with an annual production which exceeds $3,000,000. Gemstones are an important component of the mineral wealth of the State. Turquoise, peridot, chrysocoll a, petrified wood, fire agate and crystallized mineral specimens are among the gemstones commercially mined. Numerous additional deposits are operated by hobbyists. The State's reputation as a source of gemstones and specimens for the collector and lapidary adds to the economy of the State by attracting tourists. Production of gemstones further adds to the State's economy through employment in the value added gemstone processing industries and by employment of Native American craftsmen.

Jan 1, 1988

By Rossen Halatchev

The production sequence optimization of open pit mine is a procedure that reflects the exploitation conditions over life of mine. These conditions are determined by the geological characteristics of the deposit, requirements of the mining and processing technologies and economic parameters of the exploitation. From a technological point of view the production sequence optimization deals with two aspects - spatial and time. Each of them plays a tremendously important role in searching for the optimum solution of the problem. This paper treats the time aspect of the production sequence optimization. This aspect is revealed in the context of the problem of the working zone formation of the open pit mine in time. The problem formulation places an accent on the determination of the theoretically possible time distribution of the waste and ore quantities of each bench of the open pit mine. A mathematical solution to the problem has been developed based on combinatorial analysis. The solution provides a multi-variant investigation of the production sequencing with the use of an optimization model developed as a linear programming formulation. The model objective function uses the Net Present Value as a criterion for assessing the effectiveness of production sequencing. A case study is provided for the conditions of Assarel copper open pit mine (Bulgaria) to illustrate the applicability of the approach. The results obtained reveal the complex nature of the variation of the Net Present Value as a function of the mining factor.

Jan 1, 2002

By Edward M. Dowey

This paper presents the excavation of the Roosevelt Island Valve Chamber, the final of three chambers in Stage One of New York City's Third Water Tunnel. The valve chamber and passageways 13 379.7 cu m (17 500 cu yd) are drilled and blasted. The rock is stabilized by grouted rock anchors. The 6.1 m (20 ft) diameter shaft is drilled, blasted, rock bolted and wire meshed for a depth of 70.7 m (232 ft). Then shaft excavation proceeds with immediate concrete lining for another 120.7 m (396 ft). Two 6.1m (20 ft) diameter manifolds are excavated using heading and bench. The raise drilling of eight 3.7 m (12 ft) diameter laterals occurs during lower shaft sinking.

Jan 1, 1987

By C. Laughton

The Deep Underground Science and Engineering Laboratory (DUSEL) is to be constructed at the defunct Homestake Mine, in South Dakota. As a cornerstone of DUSEL?s research program, it is intended to conduct experiments into the fundamental nature of neutrino and proton particles. The experimental apparatus required to con-duct these experiments will be housed in large rock cavern(s) sited at depths of over a kilometer. As conceived, these cavern(s) are planned to have mined volumes of up to half a million cubic meters, and spans of approximately 50 meters. The paper will describe key end-user requirements, and outline the in situ rock conditions and mine site constraints that are likely to play determinant roles in identifying candidate sites and developing cost-effective design options(s).

By R. C. Shodde, R. D. La Nauze

Major societal and industry changes over the last four decades have influenced the management of technology in the minerals industry. From the authors' experiences in both private and public sector R&D, the paper analyzes the range of strategic and structural changes and provides examples of some key technology delivery responses. For those charged with managing technology, the two key challenges facing them over the next decade are (I) moving technology development from a cost focus to a value focus (that is, from "how much long-term research can we afford?" to "identifying and capturing the value created from R&D”) and (2) the recruitment and retention of key talent. THE NEED TO ADAPT "Change is slow and gradual. It requires hard work, a bit of luck, a fair amount of self- sacrifice, and a lot of patience (Greene 1998)." Since the 1960s the world has changed and the minerals industry has had to adapt to the changing circumstances. In the '60s, minerals were there to be discovered and fortunes to be made; in Australia, the World War I1 embargo on exporting iron ore was lifted and the Western Australian iron-ore boom commenced, to be followed by the exploitation of the Darling Range bauxites; copper, lead, zinc and nickel were discovered and mines developed. The Australian dollar was worth US$1.11 whereas today it is around US$0.65. The oil crisis of 1976 sharpened focus on the sensitivity of the minerals industry on energy costs. By the late 1970s The Club of Rome was predicting the imminent demise of certain key metals-a prediction that has not been fulfilled-though the signs of the shift

Jan 1, 2004

By John W. Wilson

INTRODUCTION In the past, the cost and time required for the construction of shafts has played an important part in the planning of underground mines. For reasons that are discussed later, the economics and technology of shaft construction in the future can be expected to play an even greater role in the planning of new mines and the operation of existing mines. Indeed, the very feasibility of a proposed mining venture may depend on the cost and timing of the shaft requirements. The most commonly used shaft sinking methods used today for excavating vertical shafts are discussed and the need for new technology and methods emphasized. In one study by the U. S. Bureau of Mines, it was reported that the coal industry in the United States alone could require 170 to 190 new shafts per year on the basis of doubling current production by the mid 1980's or 70 to 90 shafts on a more moderate coal production expansion program. This study concluded that the attainment of the required number of shafts would be unlikely with the present shaft sinking resources and costs. In order to meet the requirements for shafts in the United States coal and metal mining industries, more efficient and speedier shaft construction methods will be necessary. Current shaft sinking methods are, in the main, labor intensive, and it is noteworthy that it is becoming increasingly difficult to attract the work force required to sink shafts conventionally. Because of this situation, some attempts at mechanization have been made to compensate for this ever-increasing scarcity of trained

Jan 1, 1976

By Jerry D. Pfarr, Gary Loving, David G. McDowall

Introduction The Open Cut is one of the best known landmarks in South Dakota's Black Hills. It is the site of the original discovery of the Homestake ledge, or lead, in 1876. Between that time and 1945, the Open Cut produced about 36 Mt (40 million st) of gold ore, the majority of which was drawn from underground operations. In 1981, a drilling program was undertaken to determine how much ore the old timers left behind. The results of this study indicated an ore body made up of broken and caved ground, and solid blocks in pillars and crowns. Reserves are estimated at about 6.8 Mt (7.5 million st) of gold ore, grading at 4 g/t (0.116 oz per st). Total tonnage of material, including waste, is estimated at more than 60 Mt (66 million st). The mining plan is a combination open pit and underground operations. The bottom 78 m (255 ft) will be mined by the underground panel-caving method. The open pit was designed as a contractor operation up to the expected milling stage or the point of sustained ore production. The pit was designed to avoid disturbance of US Highway 85 near Lead, SD. In 1983, the South Dakota Board of Minerals and Environment approved the mining and reclamation plan. Test mining began in the north of the Open Cut using open pit methods. Upon completion of the test pit, Homestake Mining's board of directors approved an expanded mine plan. They committed an additional $27.1 million to prestrip the ore body that is expected to yield 23 t (750,000 oz) of gold. Project life is estimated at 15 years. Exploration program In early 1980, 10 diamond drill holes were drilled from the surface in the vicinity of the east side of the Open Cut. The reserves delineated by that drilling were too small to justify their development. A continuation of this study attempted to quantify the tonnage remaining in the bottom of the Open Cut in the crushed remnants of old stope-and-crown pillars. This was originally thought to be minable by improved drawhole methods using highly mechanized procedures. By early 1981, however, thinking turned toward surface mining methods. The effort to quantify minable ore tonnage ultimately involved drilling 385 reverse-circulation rotary drill holes. These were drilled from August 1981 to March 1983 in several groups of holes. Each group, or drilling program, had a slightly different immediate goal or purpose. The holes were drilled to various depths using truck-mounted Drill Tech 40 drills with doublewalled 76 mm (3 in.) pipe with 134 mm (5.25 in.) three-cone rotary bits. Initially, wet drilling was employed using a cyclone collection system. Since cutting recovery was not as high as it should have been, all subsequent drilling was dry. The cuttings were collected and deposited by way of a cyclone into the sample bag. The pickup for the cuttings using the three-cone bits was about 50 mm (2 in.) above the bottom of the hole. Overall cutting recovery for the drilling program was estimated at 75%. Samples were taken on each 1.5 m (5 ft) of hole drilled. Each sample was split into three 48-g (1-2/3 assay ton) charges. The accepted value was the straight average of the three charges. Because of the known "nugget effect," assays were nearly impossible to duplicate. Therefore, to validate the regular assays, a series of screen fire assays were run. Based on this method of assays and checks, it was concluded that 10% more ounces would be produced than indicated by mine grade. Test pit The northernmost portion of the mine as planned is known as the Terraville test pit. This portion was mined ahead of the rest and separately. It provided answers to questions on slope stability, reserves correlation, mill recoveries, mining costs, and surface mining conditions in various weather and ground conditions since many boulders and much timber were expected. The mining plan for this portion of the pit was successful. More ore was mined than was expected. Mixing of Open Cut ore with underground ore in the mill feed was successful. Impact on the surrounding communities

Jan 10, 1987

By Stavros A. Argyropoulos

The strides that have been made in recent years in applying Artificial Intelligence to pyrometallurgy, are reviewed. The computer reproduction of the way in which a human being reasons and calls on past experience and stored knowledge when faced with problem will be extremely helpful in pyrometallurgy. It is expected that Artificial Intelligence will be applied in all areas of human endeavor. Areas of pyrometallurgy that are most promising for expansion into A1 in the near future are presented.

Jan 1, 1990

By Majid Sadeghi, Ali Naghi Dehghan, Kaveh Ahangari, Seyed Mahdi Pourhashemi

"Instrumentation and monitoring of ground deformations in tunneling is a principal means for selecting and controlling the excavation and support methods among those foreseen in the design, for ensuring safety during tunnel construction (including personnel safety inside the tunnel and safety of structures located at ground surface) and, finally, for ensuring construction quality management. In this paper, the effect of Hakim Tunnel excavation on the behavior of the surrounding ground was investigated based on the geotechnical instrumentation. This tunnel with 1080 m length, 18 m width and 12.6 m height is being constructed using the SEM/NATM along the Hakim Highway in Tehran. The results which are obtained from recorded displacements by geodetic pins (on the tunnel wall and roof), extensometers and settlements pins (at the ground surface) demonstrate the tunnel stability during the various stages of excavation. However, it is concluded that the rate of excavation in different sequences could have a major role on stability of tunnel. In this case the surface and underground openings were monitored as well as needed for controlling the face probably collapse. INTRODUCTION Tunneling is increasingly being used world-wide to provide the infrastructure required for sustainable urban areas. The high demand for space and the disturbance of existing infrastructures by construction measures increasingly forces future infrastructure projects to be conducted underground. One of the important purposes of tunneling projects in urban area is not only to minimize displacements but also to control them during the construction (Pourhashemi et al., 2015). Normal method of tunnel stability analysis is not able to evaluate the real rock and soil mass behavior. Hence, instrumentation is a practical method to monitor displacements, to evaluate the stability of underground openings, and also to determine the rock and soil mass properties (Dehghan et al., 2012. Dehghan, 2013). Rocks and soils are materials with properties that can change instantly and significantly from one point to the next. Some complications may often happen due to uncertainties in the loads that the new facility must withstand during construction and operation. Instrumentation and monitoring provide quantitative information on actual behavior of ground and adjacent structures. A lot of deformation monitoring studies for determining and analyzing different kinds of engineering structures such as tunnels, bridges, high-rise buildings and dams are implemented. Considering the type of the structure, its environmental"

Jan 1, 2016

By I. Weir-Jones

I. Introduction The experimental work described in this paper was carried out during 1967 and 1968 in an inclined reinforced concrete adit which had been driven during 1965 and 1966 to provide primary access for a new gypsum mine. The new mine was situated near the village of Sherburn-in-Elmet in central Yorkshire in an area of extensive post-glacial plains of deltaic and lacustrine origin. These plains cover a large area of this part of Yorkshire extending inland from the coast for a distance of about 35 miles. The gypsum deposit at Sherburn dates from Permian times and it is considered" to have been associated with the western-most edges of the ancient Zechstein Sea which was also responsible for the formation of the extensive evaporite deposits in north-east Yorkshire. The gypsum deposit, which varies in thickness from 10 to 15 feet, is extremely pure and it occurs quite close to the surface; in the Sherburn area the overburden is only 120 feet thick. The proximity of the deposit to the surface, however, tends to give a somewhat false idea of the magnitude of the problems associated with its extraction. These problems were all related to the nature of the overlying strata. As has already been mentioned, the surface deposits are post-glacial and they consist of an extremely large number of thin layers of varved clays, fine silts and sands extending down to a depth of 75 feet. From the bottom of the post-glacial deposits to the seam, a distance of about 45 feet, the strata consists of a succession of marls, weak sandstones, and siltstones, which although they are inherently incompetent materials, are appreciably stronger

Jan 1, 1971

By Thor Skjeggedal

The Norwegian contracting firm A/S Høyer-Ellefsen has for the last 2.5 years carried out substantial pregrouting in a 7600m long tunnel just outside the city of Oslo. This has been done to avoid groundwater lowering and consequent damage to surface structures. A WIRTH TBM is used in combination with a 2 boom Atlas Copco hydraulic jumbo for the drilling of groutholes in front of the machine. The detailed procedure for the drilling and grouting will be discussed, and the results obtained will be presented.

Jan 1, 1981

By Cynthia M. Walck, S. K. Grant, R. D. Hagni

The Post Gold deposit is located in the northern part of the Carlin trend. The mineralization at Post occurs in proximity to a Jurassic-Cretaceous composite stock. Most of the gold at Post is hosted by non-metamorphosed calcareous siltstone and highly altered diorite, adjacent to the low grade skarn. Endoskarn, exoskarn, hornfels and marble are developed outward from the intrusive. The skarn is composed dominantly of diopside, tightly intergrown with gannet, k -feldspar, and sphene. The highest grade gold values are adjacent to the skarn, which acted as a permeability barrier to fluid migration. Post is the first Carlin-type deposit at which a skarn has been recognized to play a significant role in the localization of gold.

Jan 1, 1990

By Alan J. Reed

The Afton copper-gold mine is located in the southern interior of British Columbia, 16 km (10 miles) west of Kamloops and 257 km (160 miles) northeast of Vancouver. 'An aerial view of the property in 1976 is shown in Fig. 1. The Afton copper-gold ore body [27 Mt (30 million tons)] of open pit ore with a grade of 1.0% copper, 0.46 g/t (0.01 6 oz per ton) gold, and 4.1 g/t (0.12 oz per ton) silver, occurs within the Triassic Iron Mask pluton adjacent to its faulted contact with Tertiary rocks. The geological setting of the Afton ore body is described by Carr and Reed (1976). Rocks of the Paleozoic, Mesozoic, and Cenozoic eras outcrop in the vicinity of Kamloops, but the unit with the greatest economic significance is the Upper Triassic Nicola volcanic group and its subvolcanic dioritic intrusion, the Iron Mask pluton. The Afton ore body occurs at the northwesternextremity of the Iron Mask pluton immediately south of a deep graben structure that developed in post-Triassic time (Coast Mountains orogeny) and which was the focus of vigorous sedimentation and volcansim in Tertiary times. The Iron Mask pluton is a lenticular composite intrusion approximately 14.5 km (9 miles) in length in a northwesterly direction. The petrography of the Iron Mask pluton ranges from picrite and serpentinite to latite porphyry. Outcrops of individual petrographic units are generally elongate in a northwesterly direction parallel to the axis of the pluton. The Iron Mask pluton represents the moderately slowly cooled core of an oceanic fissure volcano which built up an island flanked by shallow-water sediments including reef knolls and which, during its later stages, intruded its own volcanic pile.

Jan 1, 1991

By Alden B. Carpenter

Brines (a solution containing more than 100,000 mg/l dissolved solids) in sedimentary basins are genetically related to evaporites in one of three ways: (1) dissolution of evaporite minerals, generally halite; (2) interstitial fluids in evaporites which are expelled from their source rock during compaction; (3) incongruent alteration of hydrous evaporite minerals (carnallite). Most brines of commercial interest originate as interstitial fluids in halite-rich rocks. These fluids are initially rich in magnesium, sulfate, and potassium but evolve in composition to an Na-Ca-Cl brine during their migration to their present host rock. A particularly important reaction in this process is: 2CaCO3 + Mgt+ = CaMg(CO3)2 + Cat (1a) This reaction reduces the magnesium content of the brine and ultimately converts it to a calcium-rich brine. The loss of sulfate occurs by two mechanisms. One of these is by direct precipitation as calcium sulfate (either as gypsum or anhydrite): Ca 2+ + SO4 2- = CaSO4 (2a) Additional sulfate may be lost from the brine by sulfate reduction: S042 + 1.33CH2 + 214- = H2S + 1.33CO2 + 1.33H20 (3a) The loss of carbonate species occurs by precipitation as carbonates: H2O + C02 + Cat = CaCO3 + 2H+ (4a) The net result of reactions 3 and 4 is: Ca 2+ + SO4 2- + 1.33CH2 = H2S + CaCO3 + 0.33H2O + 0.33CO2 (5a) The loss of potassium from brines is caused by the formation of potassium aluminosilicates: 2K+ + Al2Si2O5 (OH)4 + 4SiO2 = 2H + 2KAlSi2O8 + H2O (6a) The hydrogen ions produced by this reaction dissolve carbonates: 2H+ + CaCO3 = Ca 2+ + CO2 + H2O (7a) The net result of reactions 6 and 7 is: 2K+ + CaCO3 + Al2Si205 OH)4 + 4SiO2 = Ca2 + 2KA1Si3O8 + H2O + C02 (8a) A study of brines from central Mississippi has shown that the composition of these brines is related to the interaction of pore fluids from evaporites with minerals in the enclosing sedimentary rocks.

Jan 1, 1978

Editor?s note: Each year, the June issue of Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue. Thank you to the industrial minerals annual review editor, to the technical committees chair and vice-chair, and to the authors of the individual commodity profiles. Jim Norman, member SME, of GeoTrans, Inc., is the industrial minerals annual review editor. SA Ravishankar, member SME, of Cytec Industries, is chair of the industrial minerals technical committees. Technical committee vice chairs include: ? Abani Samal, member SME, of Pincock Allen & Holt, agricultural minerals. ? Aaron McMahon member SME, of Pincock, Allen & Holt, ceramics and refractories. ? Bradley S. Van Gosen, member SME, of the U.S. Geological Survey, chemical raw materials. ? Mark Zdunczyk, member SME, of Continental Placer, Inc., construction materials. ? Jerry Gauntt, member SME, of JEG Minerals Consultants, fillers and pigments. ? Michael Cheshire, member SME, of Indiana University, sorbents, filters and process aids. Their help makes possible this June industrial minerals issue. On behalf of ME readers, the editors thank them.

Jan 1, 2008

By Eleanore L. Nestlerode, James R. Guilinger

In April. 1990 Addwest Minerals acquired the Phillips Ranch sulfur property. The sulfur deposit, hosted by the Permian Castile anhydrite, occurs as two distinct elongate. parallel orebodies within a series of northeast-trending grabens. After completing a positive feasibility study, based, in part. on successful drilling programs by Addwest Minerals and previous operators, the decision was made to place the property into production. Utilizing an existing on-site kasch plant, plus significant portions of the recently purchased Texasgulf Comanche Creek Frasch plant. Addwest is currently constructing an 800 long ton per day Frasch mining facility.

Jan 1, 1992

By K. Oraee

Excessive emissions of methane from the coal seams can have a serious adverse effect on both safety and productivity of longwall coal faces. Mechanization of coal faces has increased production possibilities to the extent that normal ventilation systems may not be able to ventilate coal face areas in order to lower methane content in the air to within legal limits. Production increases may therefore be prohibited for this reason, especially in gassy seams. Methane drainage from the coal seam by means of long holes and before production starts can act as a useful remedial action. In this paper a two dimensional mathematical model has been produced. The model that is based on finite elements, simulates a methane drainage system where the resultant risk is linked to the coefficient of diffusion, coal permeability, holes pattern and the duration for which the seam is subject to drainage. It is concluded that methane drainage of this type can assist in achieving production increases in many coals seems, especially where high gas content is a virtue of the seam.

Jan 1, 2010

By Kenneth J. Reid

The application of computers for control purposes in hydrometallurgical processes is not as well-established as in mineral processing plants. This is not only due to the comparatively new development of large-scale application of hydrometallurgy and the relatively small number of operating plants, but also due to some of the basic dynamic characteristics of hydro- metallurgical processes., Basically there is little difference in the development and application of digital control techniques in hydrometallurgical plants from those techniques widely in use throughout the chemical process industry and in nonslurry applications; particularly for those cases involving liquid streams only, the primary sensing elements are essentially the same. On-stream X-ray fluorescence analysis is a well-established method for determination of metal content in the process streams, and standard equipment is used for the measurement and control of pH, flow, density, temperature, pressure, and other variables. Nevertheless, the high proportion of corrosive slurry streams at elevated temperature and pressure poses a challenge to the instrument engineer concerned with developing long-life, reliable instrumentation. One major difference and potential problem area in developing control systems for hydro- metallurgical processes is related to the very long time constants which are common in the larger plant. In these circumstances, it is important to define the overall control objectives very carefully and be prepared to allow for considerable drift in intermediate variables. In larger projects with many control loops the general advantage of lower costs compared to conventional analog instrumentation can be confidently expected. Also in most cases, the process analysis necessary to design and specify a comprehensive computer control system and the increased operator involvement in implementing digital control systems yield additional benefits due to the increased understanding of the dynamic characteristics of the process.

Jan 1, 1979

By Tim O’Neil

The search for precious metals opened up the American West. And Nevada was right in the heart of this development. In the mid-19th century, prospectors seeking gold roamed the hills of Nevada and discovered the ComstockLode. The development of this huge silver and gold deposit began in1859 and was responsible for Nevada’s early entry to statehood. Mining was Nevada’s first industry. In more recent years, the Nevada mining industry has led the nation in gold, silver and barite production. Nevada also produces many other minerals. These include aggregates, clays, copper, diatomite, dolomite, gypsum, lime and limestone, lithium and magnesium compounds, perlite, salt and silica. Even today, Nevada’s mining industry continues to be a major economic force in the state. The mining industry has made more than $10 billion in capital investments in Nevada since 1985. And the value of Nevada’s mineral production last year was about $2.7 billion.

Jan 1, 2000