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Continuous improvement has become the watchword of the 1990s for most iron-ore-processing operations. In many instances, this improvement has been achieved through stepwise application of advanced control techniques to optimize operations. The benefits of this stepwise application have been great. However, they have fallen short of the full potential offered by the prospect of overall plant optimization. The successful integration of computers, instrumentation and control software throughout a plant promises to deliver an additional 3% to 5% of productivity in even the best-run plants (Herbst and Bascur, 1984). LKAB is Europe's largest iron-ore producer and a leading implementer of advanced control technology. In the late 1980s, LKAB introduced advanced control in its concentrator at Kiruna, Sweden to improve plant performance through higher productivity, greater efficiency and lower costs at each processing step.

Jan 1, 1995

By Kenneth N. Han, Jianshe Liu

Various techniques used in the removal of metal ions from effluent streams have been reviewed. These techniques include recovery of metals by biological treatment, chelating agents, adsorption, ion- exchange and chemical precipitation. The main thrust of this paper however, is concerned with the removal of cadmium and zinc ions from the solution by adsorption utilizing liquid fluidized beds. The bed particles used were silica of 150x200 mesh. The range of the concentration of these ions studied was 10-3 to 10-5 M. Important variables examined included flow rate, concentration of metal ions and amount of bed particles. A mathematical model describing the concentration profile of metal ions in the axial direction in liquid fluidized beds has been developed. The equation of continuity was solved numerically and the results were used to predict the recovery of metal ions in fluidized beds.

Jan 1, 1992

By W. C. Yates

Lack of visibility from large, open-pit haulage truck cabs has become a serious safety problem. Anaconda conducted a research program to develop a low cost system to alert haulage truck operators to small vehicles present in blind areas. Several systems were developed and tested. As open-pit haulage truck size has increased, so has the size of the blind areas. Mine utility vehicles, pickup trucks, and cars are concealed within these blind areas and become safety hazards. Figure 1 shows the typical blind areas of a 136 t (150-ton) haulage truck. The areas of greatest concern are at the rear center and front right corner of the truck. In these "no visibility" areas many small vehicles have been crushed by large haulage trucks at various mine sites. In most instances, the occupants escaped the vehicle before it was destroyed. But injuries and death have occurred. In most cases, the accidents were attributed to negligence or carelessness by the small vehicle driver. The limited visibility problem still exists, though, and a solution is needed. Initial Solution The usual plane mirror on the driver's side and the convex mirror on the right front of the haulage truck allow only limited rear visibility. The typical, right side convex mirror is generally small and difficult to locate at a glance. This convex mirror also presents an image that distorts distance perception. These mirrors are of¬ten broken and immediate replacement not demanded or made. The US Bureau of Mines, in a contract with M.B. Associates, San Ramon, CA, developed an improved visibility system. It consisted of a larger, left view mirror and unique, blind area viewer. The large 230 x 690 mm (9 x 27 in.) left mirror has a small convex spot mirror near the bottom. The entire unit can be quickly replaced if broken. The large size provides a full view of driver orientation features such as the rear tire and the top of the load bed. The right 300 x 410 mm (12 x 16 in.) mirror has a convex surface and is quite rugged. The 510 mm (20 in.) spherical radius presents the operator with some distance distortion, but objects in its view are easily seen. The "blind area viewer" consists of a modified fresnel lens that allows the driver to "look around the corner." Installation of three of these lenses on the front of each haulage truck is rec¬ommended for adequate blind area coverage. This system significantly increases an operator's field of view and allows viewing of objects within about 3 m (9.8 ft of the truck. Many open-pit mines are nor mounting on smaller vehicles a long whip with a flag and lamp or both. This increases vehicle visibility to haulage truck operators. The whip is permanently attached to the mine vehicle. It can also be magnetically attached to transient vehicles. The whip system. though, is inadequate for visibility in the critical rear and right front blind areas. Alternate Solutions All of these visibility aids as¬sume an attentive driver. In addi¬tion, areas such as the rear blinc, area are not covered. Based on the inadequacy of existing visibility systems, Anaconda made a com mitment to further the truck de¬tection technology. The best ap¬proach was considered to be ar active system. It would notify the haulage truck operator that an en¬croaching vehicle is present. Sev¬eral systems were considered, in¬cluding ultrasonics and elec¬tromagnetics. For the ultrasonic system, com mercial and in-house design were looked at. Designing an( building transducers with the spe cific beam shape to match the haulage truck blind spots re¬quired a major technological breakthrough. False alarms ap¬peared difficult to prevent en¬tirely. They were caused by pass¬ing, trailing, or leading vehicles a., well as nonthreatening objects. As a result of these problems, the ul¬trasonic technique was not pur sued. An alternative, an electro

Jan 7, 1982

More than 5,300 mining professionals from around the world attended the SME Annual Meeting and Exhibit, March 1-3 in Denver, CO. Seventy three technical sessions highlighted innovative technologies and applications for the development of mineral resources. And the exhibit featured 421 companies worldwide and 632 exhibit booths. The 1999 SME Annual Meeting had 10% international attendance Professionals from outside the United States were guests at the first SME International Reception. Other meeting highlights included the Keynote Session. This pivotal session examined the international experience of North American-based companies. Speakers presented their perspectives on international explorations and operations. Keynote speakers included Robert Buchan, Chairman an( Chief Executive Officer, Kinross Gold; Dave Baker, Director Global Mining Project Management, Caterpillar; and Leendert Krol, Vice President International Operations Newmont Gold. Ihor Kunasz, 1998 SME President, made the introductory remarks.

Jan 1, 1999

By Ahmad Rahbar-Kelishami, Zahra Karimi

When alumina is extracted from bauxite ore, one of the environmental pollutants created is known as red mud (RM). This study clarifies that the RM obtained from the Iran Alumina Company has a significant proportion of iron oxides (24%), alumina (19%), silica (17%), and calcium (21%), as well as trace amounts of other minerals. The elements in the RM can be removed and utilized again to reduce environmental pollution. Acid leaching is one of the best ways to selectively exclude some minerals from the RM. In this research, the RM is exposed to different inorganic acids, including HCl, HNO3, H2SO4, and H3PO4, and their binary mixtures. By comparing the results obtained from XRD, EDX, and SEM, it was discovered that CaSO4 crystals are formed by exposing the RM to sulfuric acid. Besides, phosphoric acid was only able to destroy the surface of RM particles. The XRD analyses of acid-washed residues demonstrated that except for the residue of HCl 5 N, all residues contain hematite, showing that inorganic acids cannot easily extract hematite from the complex phases of red mud. While the dissolution of RM with HCl or HNO3 will remove most of the calcium content of RM texture, increasing its iron oxide percentage, which may subsequently be utilized to make colors and pigments.

Mar 29, 2024

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

A high calcium fluidized-bed combustor ash was shown to be an effective binder for iron ore pellets at dosages of 1 % to 2% of the magnetite concentrate weight. Magnetite pellets that were between 1.1 and 12.7 mm (7/16 and 1/2 in.) in diameter were produced with dry crushing strengths greater than 22.3 N (5.0 lb-force) per pellet, which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. The addition of calcium chloride at a rate of 0.1 % to 0.2 % of the total powder weight increased the strength of the dried pellets by as much as 22 % compared to the strength of pellets made using fly-ash without accelerators.

Jan 1, 1999

By S. R. Rao, J. A. Finch, E. El-Ammouri, K. Ngoviky, P. A. Disten

Sludges produced by lime treatment of acid mine drainage (AMD) can contain significant quantities of base metals which represent both a potential hazard and a loss of values. A new technique for metal recovery from sludge is proposed by combining selective acid leaching and adsorption of metal ions by activated silica sol. The process is demonstrated on two AMD sludges, one containing primarily nickel and the second zinc. They were first treated with sulphuric acid (pH 3.5) to selectively leach the target metals and then activated silica sol was added to the leach solution to adsorb the nickel and zinc. Thickening and centrifuging gave about 90 percent rejection of the input volume to effluent. The adsorbed metals were redissolved by strong acid into a concentrated solution relative to the feed and the silica sol was recycled.

Jan 1, 2000

By M. J. Lowe

National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the Mine Safety and Health Administration Permissible Exposure Level. Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Pittsburgh Research Laboratory. The results show that the entire screen contributes to noise below 1 kHz and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2010

By William D. Hanson

Celestine (celestite) (SrSO4), the primary ore mineral of strontium, is present in the DeQueen Limestone Member of the Trinity Group (Lower Cretaceous) in Sevier, Howard, and Pike Counties, southwest Arkansas. Two mappable celestine beds have been identified. One bed is commonly 3-5 in. thick, but ranges up to 18 in. in thickness; the other bed is generally 2-3 in. thick. The beds are concordant within the DeQueen Limestone and were formed by precipitation from periodically restricted sea water. Reports concerning celestine date back to 1929, when Hugh D. Miser and A. H. Purdue mapped the geology of the DeQueen and Caddo Gap quadrangles. A small amount of celestine was produced in the early 1940s in Howard County. During 1941, the J. W. Hintze Company collected 1,500 pounds of celestine for testing purposes. In 1942 and 1943,750 test holes were drilled by the Bennett-Clark Company in Howard County. Afterward, approximately 90 tons of celestine was open-pit mined and shipped to Texas for processing. Since then, no mining of celestine in Arkansas has taken place.

Jan 1, 1999

By A. M. Al Taweel, V. K. Kasireddy

Intensive coal cleaning usually necessitates fine grinding of the feed in order to liberate inorganic constituents from the surrounding organic matrix. This however adversely affects the ability of flotation techniques to beneficiate coal. Such difficulties are mainly attributed to the increase of particle population density, the decrease in capture efficiency, and the greater tendency of inorganic components to report with the froth. A three-pronged approach was adopted in an attempt to overcome these difficulties. The aggregative flotation technique was used to reduce particle population densities and improve capture, while unconventional spargers were used to generate a wide range of bubble sizes. Use of unagitated flotation columns allowed for the maintenance of countercurrent flows in both the recovery and washing sections. The combined effect of these parameters enabled the recovery of 92% of the carbon content of coal having an average particle size of 20.5 µ m, while rejecting 85% of the ash. This was accomplished using 2 kg of fuel oil per tonne of coal in a column 2 meters high operating at 2-3 tph/m3, a capacity which compares favourably with conventional cells.

Jan 1, 1989

By M. Nichols

Where am I? Where are they? Where is it? These are the fundamental questions that need to be answered in managing people and resources. This paper explains how GPS positioning technologies answer those fundamental questions and provide better information management from initial exploration work through daily mine operations to reclamation work and environmental monitoring.

Jan 1, 1998

By S. S. Klima, J. A. Organiscak

Researchers at the National Institute for Occupational Safety and Health (NIOSH) performed laboratory testing to examine and improve airborne dust capture and methane removal performance of flooded-bed scrubbers on continuous mining machines using a blowing face ventilation configuration to reduce respirable dust exposure to shuttle car operators. Several testing conditions were examined to minimize shuttle car operator dust exposure without adversely affecting continuous miner performance and production. Curtain-to-face setback distance of 9.1 m versus 15.2 m (30 ft versus 50 ft), face ventilation airflow of 226.5 m3/min versus 339.8 m3/min (8,000 ft3/min versus 12,000 ft3/min), and the use of side-body-mounted blocking sprays (on versus off) were the three primary parameters compared. Scrubber airflow was set and maintained at 198.2 m3/min (7,000 ft3/min) throughout testing. An examination of slab cuts versus box cuts and the location of the shuttle car (present behind the continuous miner versus not present in the entry) was also performed to demonstrate the effects of these constantly changing scenarios on scrubber performance. Results show that the best blowing face ventilation setup for minimizing shuttle car operator dust exposure for the tested parameters uses a 15.2-m (50-ft) curtain-to-face setback with 339.8 m3/min (12,000 ft3/min) face ventilation while operating the side-body-mounted blocking sprays. INTRODUCTION Coal mine worker overexposure to respirable coal dust continues to be a problem in U.S. underground coal mining operations, potentially leading to coal workers’ pneumoconiosis (black lung). The U.S. Mine Safety and Health Administration (MSHA) requires that respirable dust exposure to coal mine workers does not exceed a 1.5 mg/m3 average over the actual working shift (79 Fed. Reg. 24814 (2014)). Although using a blowing face ventilation configuration on continuous miner (CM) sections is beneficial for removing methane emissions from the mining face, it can be detrimental for dust control for shuttle car (or ram car) operators and any other workers on the return ventilation side of the CM when compared to exhausting ventilation. Even with machine-mounted scrubbers on CMs, shuttle car operators still have some of the higher dust exposures with blowing face ventilation systems (NIOSH 2011, Beck et al. 2015). Although scrubber discharge air is not completely clean, dust being blown around the scrubber inlet and therefore not being captured by the scrubber can further increase these dust exposures (Goodman 2000). Dust control problems are also caused by inadequate face ventilation quantities causing scrubber face airflow recirculation issues (Schultz et al. 2010). In order to minimize respirable dust exposures on blowing face ventilation sections, ventilation, water spray, and scrubber parameters were experimentally examined to improve operating ranges for both dust and gas control. Several blowing face ventilation factors were examined with respect to CM spray systems and scrubber operation. Curtain-to-face setback distance and side-body-mounted blocking sprays were previously examined in the laboratory for dust control on a full-scale CM model using a scrubber on a blowing face ventilation system (Goodman 2000). The blocking sprays produced larger dust reductions at the CM’s rear corners and return for a 6.1-m (20-ft) curtain setback distance as compared to a 12.2-m (40-ft) curtain setback distance with equal face and scrubber airflows of 169.9 m3/min (6,000 ft3/min). Because face ventilation airflow quantities, shuttle car operator locations, and tracer gas concentration gradients were not previously examined during these experiments, additional research was required to determine improved operating parameters for blowing face ventilation systems.

Jan 1, 2019

By R. A. Womack, Alex Ruzycki

Over the past six years, 4.5 million tonnes (5.0 million short tons) of gold ore have been heap leached at the Alligator Ridge Mine. Ore is leached in successive lifts, resulting in heap heights of 20 m (66 ft). Recoveries from each lift are determined through an extensive post-leach drilling program. The relationships between heap height, recovery rate, ore preparation, heap construction, and leach solution application are discussed.

Jan 1, 1987

By Takeo Oki

A new suspension electrolysis method has been developed, which enables without any gas or dust pollutants a direct anodic extraction of zinc from zinc sulfide concentrates, while simultaneously oxidizing sulfide sulfur to elemental sulfur. The investigations were performed in a laboratory scale electrolytic cell with suspended zinc sulfide concentrate particles with or without graphite powder additions in dilute sulfuric acid electrolyte. By regulating the redox potential of the electrolysis system in combination with some additions, for example [Fe3+/Fe2+, MnO 4/MnO2, MnO 2/Mn2+ or MnO 4/Mn2+], the anodic dissolution reaction of zinc sulfide has been accomplished effectively without evolution of hydrogen sulfide. Under optimum conditions the anodic current efficiency of zinc dissolution ammounted up to 95 %, while sulfide sulfur was converted nearly completly to the elemental form. Purification by removal of sulfur and other impurities gives a zinc sulfate solution suitable for electrolysis to cathode zinc.

Jan 1, 1975

By P. Karimi, A. Akcil, A. Amini, H. Abdollahi

"In this study, cyanidation experiments were carried out on a massive sulfide ore sample, whose grades of the precious metals gold and silver were found to be 4.2 g/t and 311.9 g/t, respectively. Other elements in the ore were arsenic with average grade of 1,751.6 g/t; antimony, 619.7 g/t; zinc, 781.4 g/t; copper, 454.6 g/t; lead, 101.8 g/t; mercury, 324.3 g/t; and bismuth, 0.6 g/t. The first objective of test work focused on determining the best conditions for extracting gold from the ore, ground to less than 75 microns. Different influential parameters such as particle size fraction, cyanide concentration, pH and leaching time were investigated. The optimum parameters were found to be particle size fraction of less than 25 microns, cyanide concentration of 2,000 mg/L, pH of 11 and cyanidation time of 24 hours. In these optimum conditions, the highest gold and silver leaching efficiencies were 76.88 and 59.63 percent, respectively. In addition, roasting as pretreatment at a temperature of 700°C over a period of two hours was evaluated. Cyanidation testing of the roasted ore in the optimum conditions found increases in the gold and silver leaching efficiencies to 85.97 and 67.57 percent, respectively. Moreover, antimony extraction rose to 43.10 percent, from 23.73 percent without roasting.IntroductionGenerally, gold ores can be classified as “free milling” or “refractory,” depending on how they respond to cyanide leaching (La Brooy et al., 1994; Celep et al., 2009). While high gold recoveries (> 90 percent) from free-milling gold ores can be readily achieved, refractory gold ores are often characterized by low gold recoveries (50-80 percent) within a conventional cyanide leaching process (Rubisov et al., 1996; Adams, 2005; Celep et al., 2009). The presence of preg-robber components such as carbonaceous matter, sulfide minerals and aluminosilicate can further decrease gold and silver dissolution rates and recoveries. With the negative effect of the presence of preg-robbers, gold dissolution is considerably diminished in solutions with high cyanide concentration (Tan et al., 2005). In such refractory gold ores, gold particles may sometimes be occluded or included in the sulfide minerals, and pretreatment becomes necessary to break down the mineral structure to liberate gold for subsequent recovery. These ores are usually pretreated with an oxidizing process, after which gold and silver can be recovered by a standard cyanidation process. The main oxidizing processes available for refractory gold ores are roasting (LaBrooy et al., 1994; Angelidis and Kydros, 1995; Li et al., 2009; Karimi et al., 2010; Kyle et al., 2012), biological oxidation (Lawrence and Bruynesteyn, 1983; Komnitsas and Pooley, 1990, 1991; Deng and Liao, 2002; Ciftci and Akcil, 2010, 2013) and pressure oxidation (Mason, 1990; Murthy et al., 1992; Qingcui et al., 2009). In addition, ultra-fine grinding is being used in some plants for the liberation of gold and silver particles that are interlocked in the sulfide or silicate minerals (Celep et al., 2011)"

Jan 1, 2015

By John Stroiazzo, Bernard C. Aubé

Brenda Mines, located 22 km Northwest of Peachland in British Columbia, Canada was an open pit copper- molybdenum mine which closed in 1990 after 20 years of operation. The primary concern in Brenda's tailings and waste rock drainage is molybdenum at a concentration of approximately 3 mg/L. The mine drainage is alkaline and contains little or none of the typically problematic heavy metals. Given that the waters downstream are used for municipal water supply and some irrigation, a discharge limit of 0.25 ma molybdenum was imposed with specific water quality guidelines in the receiving creek. A review of all existing and potential molybdenum removal methods was undertaken prior to mine closure. The chosen process is a two-step iron co-precipitation with clarification and sand filration at a slightly acidic pH. A 4,000 usgpm (912 m3/h) treatment plant was constructed and commissioned in 1998, at a cost of $10.5M. The successful removal of molybdenum from the drainage water is explained with details on some design innovations and operational challenges encountered during plant start-up. Investigated sludge disposal options are discussed although the long term disposal scenario has not yet been finalised.

Jan 1, 2000

By O. Ofor

Coal fines of less than 0.5 mm particle size, discarded as too fine for gravity separation, were subjected to flotation tests at varying pH and temperatures using modified dosages of kerosene as oil phase and methylisobutylketone (MIBK) as frother. Optimal coal recovery of over 74% was obtained using 200 kg kerosene and 4 kg MIBK per ton of coal fines at a pH of 9.7 and an ambient temperature of 26° C. The coal concentrate obtained under these optimal recovery conditions assayed 9.10% ash, 0.35% sulfur and 0.011% phosphorus, representing reductions in the ash, sulfur and phosphorus contents of approximately 75%, 43% and 8.3%, respectively. Its gross calorific value was 32.9 MJ/kg, its percentage of volatile matter measured 30.6 and the fixed carbon content was 66.3% (d.a.f). Caking tests showed the optimal concentrate has a standard welling number of 1 and is a Gray-King coke type C. These results show that the optimal flotation product could be utilized for such industrial purposes as steam raising or for processing in gasworks, but it would be unsuitable for metallurgical coke production.

Jan 1, 1993

By Yixian Zhao

Although many ultimate pit limit design algorithms have been developed for the past one- quarter century, only the well known Lerchs-Grossmann's (LG) algorithm is capable of producing a truly optimum ultimate pit limit today. This paper presents a graph theory oriented algorithm for optimum ultimate pit limit design. This algorithm produces a true optimal solution and maximizes the total undiscounted net profit for a given 3-D block mine model. The algorithm performs much better than the well known LG algorithm, in terms of the reduction in computation time and computer memory requirements. More importantly the new algorithm is easier to understand and implement than the LG algorithm. Specifically, this paper discusses: 1) the computer representation of arcs and the rules of arc generations which dictate the formation of trees in the graph, 2) the mechanism of joint support and re-allocation, 3) the properties, the general procedures of the algorithm, and the suggested specific steps to implement the algorithm, 4) comparison between the new algorithm with LG algorithm, and 5) some experience in implementation of the algorithm and two case study results.

Jan 1, 1992

By Yisa Liu, Lili Xu, Shina Li, Kang Li, Jiong Dong, Zichen Yin, Ruixin Ma

With the evolving landscape of gold mineral resource development and utilization, the easily treatable gold resources are continuously decreasing, while refractory gold minerals are becoming the most important resources in the field of gold extraction. In these original ores, most of the gold is encapsulated in the lattice of pyrite and arsenopyrite, resulting in difficulty of gold transfer into the solution during the leaching process. The most effective method to solve the problem of insufficient contact between gold particles and leaching reagent is oxidation pretreatment before leaching. Different from traditional high-temperature roasting, concentrated sulfuric acid was used as both an oxidant and leaching agent in a sulfideencapsulated refractory gold ore to decompose the pyrite in the curing environment to expose the gold and improve the leaching efficiency. The experimental results showed that under the conditions of liquid solid ratio 3:1, curing temperature 240 °C and the reaction time 1.5 h, the weight loss rate and iron removal rate of the ore sample reached the highest value of 60.01% and 99.68%, respectively. The main phase of curing residue was Fe2( SO4)3, and silica was nearly the only phase after washing. At the same time, by combining the sodium thiosulfate system gold leaching method, the gold leaching rate increased from 3.67% to 81.30% before and after pretreatment with concentrated sulfuric acid.

Feb 19, 2024

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981