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By G Luxbacher

Computer simulation of mine ventilation systems is rapidly becoming an essential tool in mine planning and design. This paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve mainly for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria, could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1977

By Thomas Novak, Sampurna Arya, Joseph Sottile

Dust generation and its dispersion in a longwall mine pose significant health and safety issues. The concern is prominent at both the working face, where coal excavation exposes workers to high dust concentrations, and also in the return, where float dust accumulates. To address this issue, researchers at theUniversity of Kentucky designed and fabricated a flooded-bed dust scrubber integrated into a full-scale physical model of a longwall shearer. This mock-up was installed in the longwall test gallery at the Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH). A full-factorial experiment was designed to measure the effectiveness of the scrubber on dust capture. Test results indicated dust reduction of up to 57% in the return airways. This paper presents the development of a computational fluid dynamics (CFD) model and its validation by comparing the simulation results against the experimental results. The CFD simulations show good agreement with experimental results with differences between + 6.9 and − 9.7%. The validated CFD model was used further to predict the scrubber performance under additional operating conditions, resulting in a dust reduction of up to 66.5%. With this level of success, the scrubber concept can be a game changer for the mining industry, and it can be utilized to improve health and safety in longwall mines.

May 26, 2020

By D. E. Healy

In 1989 an Autogenous Grinding Task Force was formed to study potential autogenous grinding circuits to replace the existing semi-autogenous grinding at the National Steel Pellet Plant located in Keewatin, Minnesota. Pilot plant test work performed by the Hanna Research Center (HRC) indicated that fully autogenous grinding with pebble extraction and crushing could feasibly be incorporated into the existing circuits. In 1990, one of the existing ten grinding mills was converted for an in-plant test incorporating pebble crushing. The full scale test work conducted in 1990 and 1991 verified the pilot plant projections with primary mill throughputs from the fully autogenous circuit utilizing pebble crushing being greater than throughput of the existing SAG mill circuits.

Jan 1, 1992

By George R. Stephans

The Climax Mine is a panel caving mine which has had a long history of incidents of severe ground control problems. The nature of the ore deposit, which lends itself to the caving meth- of of production, a1 so makes the mine susceptible to large scale stress concentrations which are referred to as ?weight? problems. These problems have increased with increased production and also with expansion to deeper mine levels. During the past twenty years the mine has had to learn to cope with these problems in order to remain in operation. A number of practical guidelines and useful techniques have emerged from these efforts. The purpose of this paper is to share a few of these ideas. The Mine is located near Leadville, Colorado on the continental divide at an elevation of 3450 meters. The ore body is a large low grade deposit of disseminated molybdenum sulfide. It measures about 1200 to 1600 meters in diameter and it had an original depth of about 660 mters. The Mine has been in operation since 1918 and the massive nature of the ore body together with its blocky, highly fractured condition made it natural for the caving system to have been adopted for production at an early date. Open pit mining was started in 1973. The total plant has a capacity of more than 50 thousand tons per day, and more than 400 million tons of reserves at an average grade of 0.310 percent molybdenum disulfide remain to be produced.

Jan 1, 1982

By D. E. Ranta

Orebodies with intricate three-dimensional shapes (such as porphyry molybdenum deposits) are difficult to model using geostatistics or other computer-assisted methods. The strong trends in their spatial grade distributions occur as mathematically complex shapes and prevent the customary assumption of local stationarity that is required for accurate ore reserve estimation. "Zoned Kriging", a new method developed by AMAX, solves this problem directly by using the geologist's interpretation of the ore zones as a parameter in the kriging equations. The geological basis and methods used in the Climax ore zoning technique are reviewed and discussed relative to their application in zoned geostatistical modeling. The Zoned Kriging technique is described and demonstrated using data typical of mineral deposits.

Jan 1, 1984

By L. Alagha, J. L. Corchado-Albelo

To address the U.S. Department of Energy’s critical minerals strategies regarding rare earth elements (REE) in the U.S.A. This study evaluated apatite-rich mine tailing from the historic Pea Ridge Iron Mine (PR) for possible enrichment of REE by the froth flotation process. Comprehensive characterization studies were performed on the tailing samples to quantify the REE content, identify the REEbearing minerals and their liberation behavior. The aforementioned characterization studies were: x-ray fluorescence analysis (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and TESCAN’s Integrated Mineral Analysis (TIMA). The ICP-MS analysis showed that the concentrations of heavy-REE and light-REE were 8000 ppm and 3000 ppm, respectively. TIMA showed that monazite was the major REE-bearing mineral. Additionally, it was shown that monazite and other REE-bearing minerals were strongly locked within larger apatite grains. Findings from the characterization studies suggested that REE could be enriched using phosphate minerals’ direct froth flotation process. Flotation feasibility tests were performed using selected organic and inorganic iron oxides’ depressants, including polyacrylamide (PAM), in-house synthesized hybrid polyacrylamide (HyPAM), chitosan, sodium silicates, and corn starch. Results showed that the depressant’s efficiency at pH 9 was in the following order: HyPAM > chitosan > PAM > sodium metasilicate > corn starch. Zeta potential studies on the selected depressants indicated that chitosan had the highest adsorption on magnetite’s surface at pH 7. Therefore, additional batch flotation experiments using chitosan as an iron oxides depressant were conducted as a function of chitosan dosage. Results indicated that the highest P2O5 recovery of 55% and grade of 28 wt.% were obtained at 150g/t of chitosan. However, the concentrate’s highest total REE enrichment of 1.07% was achieved at a 200 g/t dosage of chitosan. The low enrichment of REE highlighted the complex mineralogy of the PR tailings and the need to implement additional beneficiation strategies before and after the froth flotation process.

Mar 2, 2022

By Kadri Dagdelen

The importance of factoring mining dilution into feasibility stage ore reserve estimates is discussed. An example that relates the issue of mining dilution to the size of smallest volumes that can be mined selectively is given. Relationship between the size of the selective mining units (SMU's) and the variance of their average grade is presented. The concept of variance reduction and its use in factoring mining dilution into geostatistical ore reserve estimation is described. An approach to estimate variance reduction factor by way of conditional simulation is introduced.

Jan 1, 1996

Smart defense: that?s what the industry needs to play for the next four years, according to panelists at the 118th Annual Meeting of the Northwest Mining Association (NWMA), which met December 2-7 in Spokane, WA. The conference was well attended, with approximately 2,200 attendees, 244 booths in the two packed exhibition halls, and a rich offering of short courses, field trips, social events and technical sessions. Speakers at the packed legislative session articulated many of the frustrations felt by members of the mining community after the U.S. elections in November, and offered words of advice. Matthew Ellsworth, the new Government Affairs hire at NWMA, stated it best: ?Elections are like Christmas: you find out who?s naughty and nice ? and it?s always going to come again.?

Jan 1, 2013

By Kenneth E. Merklin

The heavy media process is now being used extensively throughout the world for the gravity concentration of a great number of different minerals. The process is a commercial adaptation of the heavy liquid procedure which has been used in laboratories for many years to separate mineral of different specific gravities. In the heavy media process, a suspension of finely divided particles in water is used to increase the apparent specific weight of the fluid to the desired separating point. The original heavy media process used sand, galena, pyrite and occasionally other materials as the solid constituent of the separating suspensions. As the process developed, the need for a more universal media meeting the following requirements was recognized: 1. High specific gravity. 2. Resistance to abrasion. 3. Resistance to corrosion, 4. Readily reduced to a suitable size consist for suspension in water. 5. Available in quantity at economical price levels. 6. Easy to recover by a simple method.

Jan 1, 1958

By J. B. Davis

Isotope analyses distinguish biogenic sulfur ores from non-biogenic ores, but do not distinguish bioepigenetic from biosyngenetic ores. Sulfur deposits of salt dome caprocks and of bedded Permian evaporites of west Texas, however, are clearly bioepigenetic. Anhydrite, introduced by salt diapirs into geologically younger sediments, is converted biogenically to sulfur and calcite in the presence of petroleum; for example, in Challenger Knoll, a salt dome at a water depth of 3600 m in the Gulf of Mexico. Bedded evaporites of west Texas in association with petroleum show an obvious epigenetic replacement of the anhydrite layers by biogenic sulfur and calcite

Jan 1, 1978

By S. M. Bulatovic

The western industrial world has to rely more and more on complex polymetallic sulphide ores as sources for base metals. These ores are composed of fine grained sulphide minerals such as chalcopyrite, galena, sphalerite, pyrite, pyrrhotite and marcasite. The liberation sizes of the individual minerals can range between 30 um and 5 um. Therefore, applying conventional techniques to recover these finely disseminated minerals usually results in unsatisfactory metallurgical performances with high losses of the valuable mineral to the slime , fraction of the tailing. New concepts for treating these polymetallic complex ores are discussed in this paper. Beneficiation techniques utilizing new reagents and a new approach to pulp preparation are described. Some of these techniques were applied to ores from existing concentrators as well as to new ores. The results of these studies are discussed in the following sections.

Jan 1, 1990

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974

By Roy A. Grancher

HAPPY BIRTHDAY Not only is 1971 the Centennial Year of the AIME, but it also marks the One Hundredth Anniversary of the United States Portland Cement Industry. On September 26th in 1871 David O. Saylor of Allentown, Pennsylvania, received his patent Numbered 119,413 for the manufacture of portland cement. "Cement" had been used in the United States before that. This was, however, natural cement - a direct product of rocks as found in nature, usually burned at low temperatures in open kilns. During the early 1800s this natural cement played an important role in such projects as the building of the Erie Canal. It was only after the Civil War that small amounts of high priced portland cement was imported from Europe. The successful use of this material in construction led to Saylor's experiments and subsequent patent for the manufacture of a scientifically controlled product in this country. These one hundred years have witnessed four major "ages" of cement . . . three of them occurring in the last quarter century since World War Two. The first age was the "Age of Development", a seventy-year period which saw the growth of cement and its concrete end uses as major construction materials. Next followed a period called the "Age of Demand" when, after the war, cement became in short supply relative to large building requirements. In effect a cement shortage existed. The decade of the Sixties proved to be the "Age of Reaction", with its courses of action coming in response to the problems that arose when the industry's expansion programs provided too much capacity. Today cement, and the concrete industries, find themselves entering the "Age of Reason". Overcapacity, low price, rising costs, and poor returns are several of the reasons behind that name, As these industries face the construction challenge of the Seventies, and beyond, the application of basic management principles (otherwise known

Jan 1, 1971

By Alan R. Johnson

Because of the competitive nature of the iron ore pelletizing industry, commodities required for the production of pellets are continually being scrutinized to minimize their usage and offset rapidly escalating costs. In the Tilden pellet plant, the usage of one commodity, bentonite, has been reduced from over twenty-four pounds per long ton of pellets to as low as eight pounds per long ton. The evolution of bentonite usage from plant start-up to the present time is described.

Jan 1, 1984

By R. K. Clifford

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

Jan 1, 1974

By C. Bazin

The fundamental error associated to the sampling of heterogeneous ore particles is unavoidable and can only be minimized by an adequate selection of the sample mass and/or size reduction of the sample before division into sub samples for testing or assaying. The preparation of ore batches to carry out the mineral processing evaluation of an ore is a sampling process. The fundamental error associated with the division of the ore into batches is responsible for the differences in the composition of the batches. This paper attempts by various means to assess the reproducibility of the gold content of test batches prepared from a gold ore sample. The results of the investigation shows that for fine gold grain sizes the variability in the composition of the batches is less than that predicted by Gy?s formula and that the gold grain size is a strategic information in the assessment of the gold content variability of test batches.

Feb 23, 2014

By R. Zhang, S. Azam, S. Liu, J. H. Golbeck, V. Kurashov, S. Bhattacharyya

Free radicals (FRs) present in coal dust directly influence the interaction behavior between lung cells and dust particles. FRs are atoms or groups containing unpaired electrons, with strong chemical reactivity and a short lifespan. FRs which are quite persistent in natural environments, termed environmentally persistent free radicals (EPFRs), have recently received much attention as new environmentally hazardous substances. EPFRs present on coal dust serves as an active intermediary to catalyze reactive oxygen species (ROS) production by oxygen molecules endangering mine workers’ health. Many EPFR species may be bonded to the particle surface or trapped within the particle during coalification and can be modified with progressive size reduction through cutting at the mining face or crushing/pulverization in the plant. This study measured EPFRs for lignite, sub-bituminous, and anthracite coal dust at various sizes. We especially focused on EPFRs for submicron coal dust prepared by cryogenic methods. The outcome of this study will directly improve the free radical-dependent toxicity quantification and ultimately contribute to the size-dependent coal dust toxicity quantification.

Mar 2, 2022

By Olivier Martin

In busy and historic cities, traditional open box metro stations are becoming outrageously difficult, unacceptable for the citizen and uneconomical. Hybrid stations provide an interesting alternative. In-house experience of Gautrain (South Africa), West bay (Qatar), Cairo line 3A (Egypt), and Melbourne (Australia) all aim to reduce disturbance to the city and its inhabitants during construction. Constructed in rock or in deep soil under water table, they take advantages of the latest construction techniques from cement grouting to freezing, and from traditional excavation of cavern to large tunnels constructed by sophisticated tunnel boring machines (TBM). Today, they form the ultimate construction challenge.

Jun 13, 2021

By George Schmitt, Ted Dowey, Grant Millener, Sean McAndrew, Eric Jordan

The Rondout-West Branch Bypass Tunnel is being built to bypass a substantial leak in New York City’s primary water supply tunnel. The 13,500 foot long tunnel travels 600 feet under the Hudson River through the same troubled geology and high pressure water inflows that the original tunnel did in the 1940s. A Robbins TBM traversed this geology and built gasketed segments. Nine thousand two hundred feet of 16 foot diameter interliner was installed and backfilled within the segments. Finally, reinforced cast in place lining was placed. This paper addresses the challenges and the multi-tasking approach the contractor utilized.

Jun 13, 2021

By A. C. Barlow

The use of deep wells for waste disposal is not a new technique. The production phase of the oil industry has been using this method to dispose of unwanted oil field brine since the 1930's The adoption of this method by other branches of industry, however, to dispose of manufactured wastes is a relatively new development, but one which is finding increased use (2). Deep well waste disposal is not an ordinary technique even though it is finding relatively wide application. In fact, just the opposite is true; it is still a rather extraordinary measure. It is not now, nor is it ever likely to be a disposal method which can be assured of success before it is tried.

Jan 1, 1964