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By L. I. Gyrskia, Y. V. Andreev, T. N. Greiver, G. V. Petrov

Traditionally, chromite ores are regarded exclusively as a monomineral raw material for extraction of chromium. The results of the investigations indicate a wide range of PGM in the Ray-Iz chromites, amounting to 1-3 ppm PGM. The study of products of primary gravity concentration from heavily and lightly disseminated ores (Tsentralnoe deposit, Ray-Iz block), showed that the platinum-group minerals are concentrated in the tails and slimes of the processed products, containing 10-30 ppm total PGM. Preliminary data make it possible to conclude that an in-depth study of the platinum mineralogy of the Ray-Iz block chromite ores is necessary to develop a process that will produce both chromium and the PGM.

Jan 1, 2000

By J. Winterton

Estimating the residual metal inventory of large heap leaching operations is desirable for many reasons. Several methods have been tried with limited success. Drilling data from the Valley Leach Facility at AngloGold Ashanti's Cripple Creek and Victor Gold Mine has been used to develop a robust inventory estimation technique. The technique is presented along with discussion of the particular inventory components and evaluation methodologies.

Feb 27, 2013

By David R. Delling

Introduction In 1967, Tenneco acquired Kern County Land Co. The primary reason for the acquisition was to obtain Kern's agricultural, manufacturing, and oil interests. Included in the Kern portfolio were the core of Tenneco's present sodium leases in Sweetwater County, WY. This lease base has been ex¬panded and now consists of 62 km2 (24 sq miles). Beneath this property lies more than 500 Mt (550 million st) of economic trona ore. Following the Kern acquisition, Tenneco continued exploration and feasibility studies concerning the trona leases. The effort was accelerated in 1976. Tenneco was attracted to trona because of the favorable lease position it held, the growth rate of the Wyoming industry during the 1960s and 1970s, and the prospects for a long-term, stable business enterprise. The reserve picture was certainly attractive to a company long accustomed to the never-ending struggle to replace oil and gas reserves. In 1978, Wyoming was a boom area that had experienced rapid growth for a number of years. Unemployment was very low and vacant housing nonexistent. The prospects for soda ash were somewhat different in the 1970s than now. But it was recognized even then that a new producer would have a challenging task to compete in this business. Tenneco knew the capital burden required to build a grassroots facility during inflationary time, would have to be offset elsewhere Since labor and energy are the dominant direct costs in mining trona and producing soda ash these factors have always received a great deal of attention. Contracting and permits Environmental monitoring on the site began in late 1977. With the already mentioned considerations in mind, engineering began by mid-1978. Brown & Root Inc. was selected as the general contractor for the project. S. A. Scott & Co. was the engineering subcontractor for the mine shafts, hoists, ventilation system, and miscellaneous mine facilities. Frontier-Kemper was awarded the contract for sinking the two mine shafts. Acquisition of numerous federal, state, and local permits occupied all of 1978 and 1979. The Wyoming Industrial Siting Permit, which addresses socioeconomic issues, drew the most public interest. Siting issues were all satisfactorily resolved by negotiating reasonable stipulations with various local governmental units, school districts, and the like. Site location The Green River project location is not truly remote. It is located within 5 km (3 miles) of Interstate 80 and only about 32 km (20 miles) west of the city of Green River. Nevertheless, a substantial investment had to be made in communication and utility links to the site. These included: • A 14-km (8.5-mile) rail spur connecting with the Union Pacific Railroad at Bryan, WY. This spur has four bridge structures including one crossing Interstate 80. Most soda ash is shipped by rail, and coal is received over this line as well. • A paved 5-km (3-mile) roadway connecting to Interstate 80. • A powerline extension of about 27 km (16.5 miles), along with two new substations. • A 24-km (15-mile) waterline connecting the plant to a pump station on the Green River. The site is located on gently sloping terrain at an elevation of about 2.1 km (6800 ft). Ground conditions are good for construction. Weathered bedrock lies near the surface in most places. Geology The general geology of the Green River Basin has been well described previously. Tenneco's ore is in several superimposed evaporate beds. But the bulk of it is present in Bed 17, located about 457 m

Jan 10, 1985

WELCOME to the world-class Cripple Creek district where gold exploration and production continue 95 years after the initial discovery. More than 21 million troy ounces of gold have been recovered, valued at greater than $7.8 billion using today's gold price ($371/oz). The Cripple Creek district is localized within and around the margins of a silica-undersaturated alkalic diatreme-intrusive complex. The diatreme appears to be comprised of three sub-basins: 1) a sub-basin east of the Cresson (Fig. 1); 2) a southwestern sub-basin between Victor and Cripple Creek; and 3) a northwestern sub¬basin within which the Globe Hill and Ironclad pits (Fig. 1) are located. The recognition of three separate basins was made by G. F. Loughlin and A. H. Koschmann (1935, Fig. 8) who prepared a contour map on the floor and walls of the composite Cripple Creek basin. The northwestern and southwestern sub-basins are apparent due to the discontinuous exposures of a partially exhumed ridge of Precambrian rocks (Fig. 1). The separation of the eastern and southwestern sub-basins was recognized in mine exposures where a fault-bounded ridge line extends from the vicinity of the Ajax mine toward the Precambrian "island" (Fig. 1).

Jan 1, 1986

By Martin B. Treuhaft

Expectations for coal in the early to mid-1970's prompted the government and industry to pursue research and development programs to increase underground and surface mining coal productivity and net coal recovery. Several programs concerned advanced surface mining methods for thin seam coal recovery. Three such programs, along with related areas of interest, are presented in this paper, namely: (1) extended depth augering for trench-strip applications; (2) high recovery auger heads for enhanced recovery; and (3) variable wall mining in low cover longwalls. Conceptual development is examined, prototype testing is discussed, and potential operations are considered.

Jan 1, 1983

By C. S. Kucukkaragoz

An ilmenite concentrate was reduced in the solid state with carbon under argon atmosphere at temperatures between 1000oC and 1400oC. The ilmenite concentrate and 50% excess carbon were reacted to achieve the highest attainable degree of reduction at each temperature and the reaction products were subjected to a series of analytical work by optical microscopy, X-ray diffraction analysis and SEM ( EDS) analysis. The ilmenite remained unaltered at 1000oC and had a slight change in its composition at 1050oC. A secondary oxide phase containing metallic nuclei was detectable at 12% reduction at 1100oC. The reduction of TixOy took place in a sequence changing the y/x ratio from 2.0 to a value less than 1.0 at 84% reduction at 1400oC. Metallic phase consisted of Fe and C initially and started to include Ti at the later stages. Complete reduction of TixOy to metallic Ti was not possible at these temperatures.

Jan 1, 2005

By Anuradha Khetwal, Sandeep Khetwal, Andrea Panciera

The observation method is a design optimization approach for the drill and blast method in tunneling. This method includes first identifying the hazard scenarios through site investigation, formulating suitable solutions, obtaining feedback during construction, and finally using that data to optimize the design methods. This paper illustrates the application of the observational method for T-48, a railway tunnel project in the Himalayas. It is a 10.2 km long tunnel with a parallel escape tunnel and 26 cross passages. The use of observational methods in this project optimized the overall tunnel design and considerably saved the overall project cost.

Jun 23, 2024

By M. S. Klima, A. Simard, M. L. Turek

Laboratory testing was carried out to evaluate several devices for recovering clean coal from bituminous coal refuse material. The bulk of the testing focused on using a dense-medium cyclone to process -0.6-mm refuse material. A hindered-settling column and a spiral concentrator were also used to process 1.2x0.15-mm material. Product yields and ash contents were obtained for all tests, while partition curves were generated for selected tests from which the characteristic performance parameters (relative density of separation and probable error) were determined. The results indicated that the dense-medium cyclone was capable of cleaning down to 0.037 mm, while the other devices were effective to 0.15 mm.

Jan 1, 2002

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

By M. Fan

Dry coal separation technology has particular advantages in the applications in arid and cold regions, or low rank coal separation. The hazardous pollutants in low rank coals can not be efficiently removed by conventional wet coal separation processes because a considerable amount of porose and easily friable low rank coals suffer serious particle size degradation problems in water. In this paper, a novel dry coal separation method with a vibrated air-fluidized bed of magnetic fly ash and magnetite is put forward for dry coal beneficiation. The magnetic fly ash used in this study was derived from fly ash obtained as a byproduct of coal combustion. The vibration?s effect on the uniformity and stability of a magnetic fly ash air-fluidized bed was studied. The 6×0.5 mm dry coal separation results with a vibrated air-fluidized bed of magnetic fly ash and magnetite showed that the probable error E value of separation is 0.06-0.08 t/m3.

Jan 1, 2009

By G. Luttrell, S. Keles, M. Eraydin, R. Yoon

The dewatering of fine particles is energy intensive and often requires costly capital expenditures. To address these issues, a series of advanced dewatering technologies have been developed at Virginia Tech. These include novel dewatering aids that enhance the performance of existing filtration equipment and an innovative hyperbaric centrifuge that utilizes both air pressure and centrifugal force for dewatering. The moistures obtained using these processes are 30-50% lower than those obtained using conventional methods. Another dewatering technology, known as the hydrophobic displacement process, can reduce product moistures to a level previously attainable only through the use of thermal dryers. This article presents test results obtained with these various advanced dewatering technologies along with estimates of the power consumption for each process.

Jan 1, 2007

By W. Chae

The influence of solution ionic strength (IS) and electrolyte valence on the flotation behavior of malachite has been investigated. The microflotation tests were conducted over a range of solution IS (1?300 mM) at a constant speed (340 rpm), pH (9.5), flotation time (10 min), and sodium oleate dosage (5.3×10-7 moles/g). The size of malachite ranged from 45 to 53 µm, and two different types of electrolytes (NaCl and CaCl2) were employed. Electrophoretic mobility was also measured over the same IS range employed in the microflotation study. Overall, strong coupled effect of solution IS and ion valence was observed. Specifically, the flotability of malachite increased with increasing IS in the presence of monovalent cation (Na+) while the flotability increased up to 30 mM and decreased with increasing IS in the presence of divalent cation (Ca2+). Notably, the flotability of malachite was greater with the presence of Na+ compared with Ca2+ under high IS conditions (IS>30 mM). Consistent trend for Na+ versus Ca2+ was observed from the flotation results with different SO dosages. The characterization and flotation results suggested that the trend was likely attributed to the increased unfavorable interaction between malachite and bubble via the charge reversal of bubbles and malachite at higher IS in the presence of Ca2+.

Feb 27, 2013

By A. D. Trippel

The Cripple Creek Mining district is located in Teller County, Colorado, 30 km west of Colorado Springs and 9 km southwest of Pikes Peak (Fig. 1). Since its discovery in 1891, the district has produced almost 21 million tr oz of gold (Gott et al., 1967), most of which has been from high-grade vein deposits. Globe Hill is located in the northern part of the district (Fig. 2). Production from its summit has yielded over 100,000 tr oz of gold. Early production was concentrated along high-grade veins and fault structures, but emphasis was soon placed on the extensive, low-grade (0.0X oz/t), breccia-hosted mineralization. From 1977 to 1981 Newport Minerals, Inc., a subsidiary of Gold Resources, Inc., mined 680,000 t of low-grade gold ore from the Globe Hill pit (Fig. 3) and production is expected to resume in 1986. These strongly-altered and -oxidized breccias are amenable to bulk-mining methods, and thus similar deposits are currently being sought elsewhere in the district. Numerous publications and reports discuss the breccia-hosted mineralization at Globe Hill. They include Cross and Penrose (1895); Argall (1905, 1908); Lindgren and Ransome (1906); Keener (1962); Peters (1982); Thompson, Trippel, and Dwelley (1985); and Trippel (1985). This preprint is a summary of the recently-completed research documented by Trippel (1985).

Jan 1, 1986

By P. Ashayer, J. Curran

Introduction Rockfalls occur when rocks or boulders detach from mountains or hills and tumble down. They can pose significant hazards to infrastructure such as highways, buildings, and mine open pits, and they sometimes result in personal injury or death. Prediction of rockfalls is a difficult task. Slopes that are at risk of rockfall have highly variable geometries. The location, mass, and shape of the rocks that might dislodge and fall are uncertain. Moreover, the materials that make up a slope can vary considerably from one section to another. Furthermore, the relevant material properties are usually not well known. Performing probabilistic simulations of rockfalls, combined with proper statistical analyses, has proven to be an effective and acceptable method for dealing with these difficulties [1, 2, 3]. The movements of a falling rock can be classified as freefall, bouncing, sliding, toppling, or rolling. The falling trajectory is controlled mainly by the geometry of the slope, the block shape, and the energy dissipated at each contact of the block with the slope. A rockfall model is evaluated based on its ability to efficiently predict the velocity, frequency, height of bounce, and run-out distance of falling rocks. With this information, the engineer can design remedial measures such as restraining nets and ditches. Most of the existing rockfall simulators are based on particle models that consider the falling rock as an infinitesimal particle with a mass, called the lumped mass or stereomechanical models [1, 2, 3, 4]. Other models involve hybrid methods relying on simplified assumptions. The most common hybrid methods are based on contact searching for the movement of a dimensionless object and incorporate some aspects of rigid body impact for bouncing [5, 6, 7]. There are also some rigid body models in the literature that employ simplified versions of rigid body models [8, 9]. This study applies a more sophisticated rigid body theory based on rigid body impact mechanics (RBIM), which was developed by Stronge [10, 11, 12]. The new theory captures all modes of rigid body movement. Due to the importance of the rock geometry, single impacts of ellipsoidal and prismatic rocks with rectangular cross sections are investigated. The effect of rock slenderness on rebound velocities and energies is also investigated for ellipsoidal rocks. The correspondence between the model parameters and the data from the rockfall literature data will be discussed.

Jan 1, 2007

By A. E. Koski

Two of the largest industries in northern Michigan, pulp and paper manufacturing and iron mining, formed a mutually beneficial partnership and collaborative research program to utilize paper mill residuals for waste rock stockpile reclamation. Historically, the majority of the paper industry’s residuals have been disposed of in landfills. The beneficial use of paper mill residuals for mine reclamation provides an environmentally sound recycling solution for the solids generated at northern Michigan paper mills and eliminates the need to strip additional overburden (glacial till) for final mine reclamation. Residuals offer a cost-effective source of organics and nutrients necessary for successful reclamation and waste rock stockpiles offer an economical and environmentally sound solution for disposal of residuals. The goal is to successfully pioneer technical development of paper mill residuals to accomplish vegetation of steep waste rock stockpile slopes and benches to establish a self-sustaining plant community that meets final reclamation requirements. Of the various types of iron mining wastes, rock stockpiles pose the greatest reclamation challenge. Success depends on incorporating sufficient organic matter into the rock stockpiles to produce a growth medium that can sustain vegetation without the need of overburden. This is an ongoing research program that is evolutionary in nature with numerous field trials, greenhouse studies, data collection and monitoring over multiple growing seasons. The program is a combination of innovative ideas and accepted reclamation practices that is proving to be a beneficial and economic approach to paper mill residual management and mine reclamation that will eventually lead from research to standardized reclamation procedures.

Jan 1, 2006

By B. Cousins

Flotation reagents are critical to the optimum performance of flotation circuits. How a flotation reagent performs within the first few cells of a flotation train is a key indicator of how well it will perform throughout the entire circuit. A method to compare reagent performance was recently developed by Ashland Water Technologies. The procedure involves collecting a timed sample of concentrate from each cell and then measuring the volume of the settled solids. An estimate of the percentage of concentrate collected from each cell can then be mathematically determined, providing an understanding of the recovery changes in each cell. Data from trials at a coal flotation circuit are used to demonstrate the method's validity.

Feb 27, 2013

By Y. I. Rabinovich, S. C. Brown

In the Florida phosphate industry, fatty acid collectors are used to separate phosphate ore from silica during the rougher flotation stage. However, the presence of multivalent ions (in particular Ca++) in the processing water has been reported to result in the activation of silica with respect to oleate adsorption, rendering it floatable. Hence, adequate separation may not be achieved during the rougher flotation stage. In this study, the direct measurement of surface inter-action forces via atomic force microscopy was used to delineate possible mechanisms for calcium activation under phosphate flotation conditions at oleate/calcium concentrations both above and below the calcium dioleate precipitation limit.

Jan 1, 2004

By R. C. Freas

Composite materials are finding new applications daily, ranging from automotive parts to synthetic lumber. The variety of applications seems almost limitless. However, these emerging products bring both new opportunities and new challenges to the field of industrial minerals. One of the primary challenges is from alternative materials other than industrial minerals. Thus the question is asked whether industrial minerals will truly benefit from the growth in market applications for composite plastics. This article highlights some of the opportunities for industrial minerals while focusing on performance and competitive demands on mineral products intended for use in this developing market.

Jan 1, 2000

By A. L. Crandell

History The Cortez Mining District has a long history of mining activity dating back to 1862. More recently, Cortez Gold Mines had operated a cyanide leach, counter current decantation (CCD) recovery gold mill from January 1969 to February 1976. This type of plant has been standard in the US for treating higher grade, finely disseminated gold in Carlin type ores. The mill was initially operated from 1969 to 1973 at 1.5 kt/d (1650 stpd) on oxidized ore from the Cortez ore body. In 1973, the mill was operated at 2 kt/d (2200 stpd) on softer, less oxidized, high clay ore from Gold Acres, located 13 km (8 miles) west of Cortez, NV. In February 1976, the oxidized portion of the ore body at Gold Acres was depleted and the mill ceased operations. Successful heap leaching of the lower grade portion of the ores was practiced at both Cortez and Gold Acres to supplement the milling operations. Valuable experience was gained in the operation of these two heap leaching programs (Duncan and Smolik, 1977). The ore heaps at Gold Acres and Cortez were releached with a limited crew from 1976 to 1979. The surge in the price of gold in late 1979 sparked an interest to incorporate new techniques into treating lower grade and less oxidized carbonaceous ores at Cortez. In early 1980, heap leaching was started on low grade oxidized dump material left from the earlier Cortez mining operation. By June of 1980, testwork was completed on the London Extension Dump, a low grade, mildly carbonaceous dump at Gold Acres. It was decided to convert the mill at Cortez from the conventional cyanide leach CCD recovery plant to a carbon-in-leach (CIL) recovery system. In May 1983, ore processing from the Horse Canyon deposit began. The Horse Canyon ore body contains both oxide and carbonaceous ores and is located 22.5 km (14 miles) from the Cortez mill. The Cortez CIL circuit was expanded to handle a blend of oxide and carbonaceous ores from Horse Canyon. Ore selection In the last quarter 1979, gold prices were increasing to a point where restarting the Cortez mill, idled since 1976, appeared imminent. Several previously explored geologic reserves at various stages of development were available as possible sources of feed for the mill. Initial metallurgical testing of dumps and tailings from earlier operations was completed, and previously uneconomic deposits were explored. It was decided to pursue sources of ore with the least lead time to production and those with the least capital cost requirements. A master plan was developed to bring the four profitable ore resources into production. The plan called for: • Heap leaching of waste dumps from the Cortez mining operation; • Restarting the mill to handle the waste dumps from the London

Jan 9, 1986

By Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996