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By Susumu Ukita

We have developed first a conveyor belt for transporting large lumps, i.e. Rock Belt successfully, in June 1976. The First Rock Belt had been delivered to Myodani site of Kobe City Developing Board in Japan, and its' successful operation has attract keen interests in customers from over the world as well as Japan. However, this First Rock Belt was removed in arch '81, viewing it has satisfactory expired its service life of about five-year, and also original location of this belt become to be far from the site due to long-years earth collecting work. Taking this opportunity, we introduce the Second Rock Belt applied for Rock Belt Loader as ell as three types of application of our Rock Belt working for rationalization of quarry of major company in Japan, and, view the prospect of Rock Belt:

Jan 1, 1981

By J. A. M. Cano

Pot Grate tests were carried out in the pilot plant at Samarco producing pellets containing SiO2 between 2.0% and 2.2% in a wide range of basicity to be used in blast furnace. These pellets were submitted to tests in Samarco's laboratory and another laboratory in Germany to evaluate the metallurgical properties. The pellets in the binary basicity range (CaO/SiO2) from 0,87 to 0,95 were those that presented the best results in the Pot Grate tests. Based on the results, these pellets are being routinely produced?on industrial-scale confirming the results observed in laboratory tests.?

Jan 1, 1994

By Inoka E. Perera, Michael J. Sapko, Marcia L. Harris

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effectively inert a coal dust explosion, rock dust must be able to disperse as individual particles to air. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anticaking additives after being exposed tomoisture and then dried. The dusts were exposed tomoisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anti-caking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Experimental Mine (LLEM), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for 1 day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for 6 months. This report details the analysis and characterization of anticaking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber.

Apr 12, 2021

By H. F. Broicher

Introduction In April 1998, AIS Sommer GmbH of Germany delivered the first laser-induced fluorescence (LIF) analyzer to the mining industry. LKAB's Kiruna iron ore mine in Sweden shared the costs and the risk of building the prototype. This marks the beginning of LIF analysis as a technique for quality control in mining and mineral processing. Photoluminescence analysis is well established. In most laboratories, fluorescence spectrometers are standard equipment for quality or pollution control. LIF is being used in several applications, including combustion studies and particle image velocimetry. However, it has mostly been used in laboratory environments. The availability of rugged lasers for industrial use brings this powerful tool to the forefront of production, even in the rough conditions found in mining and minerals processing. Laser-induced fluorescence Basics. Fluorescence of naturally occurring minerals has fascinated man since scientific investigation of this phenomenon commenced about 200 years ago. However, importance in industrial application and peripheral activities. Hand sorting of ore under ultraviolet (UV) lamps is seen as an archaic method. Long gone are the days when geologists set out at night with UV hand lamps to find valuable ore deposits, especially those of tungsten. Today, fluorescent minerals are considered collectors' items and museum exhibits. In the late 1960s (Hemphill, 1968) and during the 1970s, attempts to use lasers for excitation of fluorescence in minerals led to the development of an airborne fluorosensor (Seigel and Robbins, 1980). However, this prospecting technology did not gain industry acceptance and vanished from the market. During the past seven years, ongoing research of the LIF of minerals resulted in new findings that give good reason to revive the interest in fluorescence and its use in the mineral industries (Broicher and Zydek, 1995; Broicher, 1998). Fluorescence is defined as the short-lived form of photoluminescence, in which matter emits visible radiation during and after irradiation with light – the fluorescence generally being of a longer wavelength than the irradiation. Fluorescence of matter is described by: • the absorption spectrum, • the emission spectrum, • the decay curve and • the quantum efficiency. The absorption spectrum shows the fluorescence intensity in a fixed spectral band as a function of the excitation wavelength, while the emission spectrum shows the fluorescence intensity at varying emission wave- lengths for a fixed excitation wavelength (Fig. 1). The decay curves describe the exponential decrease of the fluorescence intensity with time. The quantum efficiency is the ratio of irradiating energy to emitted energy. Re- cent research has found that: the quantum efficiency of minerals can be measured and evaluated,

Jan 1, 2000

By Basilio Giurgola, Jeremiah M. Jezerski, Filippo Azzara, Federico Bonaiuti, Russell H. Lutch

The Northeast Boundary Tunnel Project consists of a 23 ft diameter, 27,000 ft long, CSO tunnel, multiple underground connections, and significant surface works within an urban corridor. The NEBT alignment depths range from 60 to 140 ft and includes seven shafts ranging in depth from 77 to 155 ft with diameters varying from about 19.5 to 56 ft, some as in-line connections and others required adits for connection to the main tunnel. This paper focuses on the design and construction of two major underground connections which are the First Street Connector Tunnel and the Mount Olivet Road Diversion Sewer.

Jun 13, 2023

By W. F. Riggs

INTRODUCTION Flotation equipment is becoming more definitive in design as well as greater in dimension. The last ten years have witnessed the implementation of large flotation cells ranging in size from 28 to 85 cubic meters. However, small plants still operate with cells as small as 3 cubic meters. These changes have increased the operational sensitivity of the flotation system to the chemical reagents used. No scientific study has been undertaken to develop the relationship between the size of equipment and the response of reagents in the flotation system. Hence, this article is an attempt to present several observations from past experience for the purpose of stimulating future research in an area previously ignored and perhaps subsequently not used to advantage. CONVENTIONAL FLOTATION Recent advances in conventional flotation cell design have been made in two areas: a. Flotation cells are becoming larger, and b. Basic design of flotation cells has changed. They can be classified into two types: deep cell and shallow draft cell. Size and design changes of flotation cells have a greater effect on frother performance than on the performance of other chemical reagents. Hence, the discussion in the following sections is restricted to the impact of frothers in the flotation system. Flotation Cell Size The advent of increasing flotation cell size has resulted in the increase of frother consumption. There appears to be a correlation between reduced horsepower (kilowatt) consumption and increased frother consumption per ton of ore processed in the circuit. This is more prevalent when the frother chemistry remains unchanged. Another reason for increased frother consumption is the increased distance between the rotating central shaft and the lip of the cell for larger flotation machines. Increasing this distance results in increased surface area corresponding to the larger cell size. Reduced power input per ton combined with the need for longer, stronger load support of the froth bubble as a result of increasing cell size has resulted in the development of a new series of stronger and more persistent frothers. By the same token, these newer, stronger frothers are difficult to control when applied to the smaller cells. This is true even at lower dosages because the break point between too much frother and not enough frother for optimum metallurgy is normally very narrow. This problem is often exaggerated when operators have established an optimum setting for pulp level and air for the particular frother in use. Generally, the tendency is to operate the flotation cells simply by adjusting frother dosage. The increase in frother strength to accommodate the large cells often results in the realization, after a retrofit, that the existing pump box or sump which is still handling the same volume of concentrate is no longer adequate in size. Flotation Cell Design The two most common flotation cell designs installed during the past ten years are the deep cell and the shallow draft cell. The deep cell provides for complete mixing of air and pulp at the bottom of the cell. The shallow draft cell does all the mixing/pumping in the bottom haft of the cell whereas the mixing of the air is performed further up the shaft and is brought into contact with the pulp midway up the vortex. There are many preferences for one or the other. It is the author's contention that both designs have very valid concepts and must simply be suited to the particular situation as required by the operator. The following comments are subjective observations which should be explored in greater detail. The deep cell mixes both air and pulp together at the bottom of the cell requiring a full depth ascending of the homogenized air to the surface to form the froth layer. This design, in combination with charged air, provides for good concentrate grade control under adverse conditions of selectivity, especially when faced with a fine grind and a slime-laden gangue. A selective frother can be applied without a competitive loss in recovery. One of the conditions for good selectivity in this environment is operating at medium pulp solids concentration in the range of twenty-six to thirty-four per cent (26-34%). When a higher solids concentration is used in combination with a coarse grind, it becomes difficult to maintain the same recovery with a selective frother due to higher pulp viscosity. This condition sometimes results in an unacceptable coalescence of the air bubbles as they ascend the full height of the deep cell. The increased pulp viscosity at higher solids concentration can also retard the flotation kinetics. The combination of decreased surface area of dispersed air and slower kinetics can result in reduced recovery causing coarse particles to continue to drop

Jan 1, 1989

By William C. Howe

This paper describes the technical status of the atmospheric pressure fluidized bed combustion (AFBC) process for utility steam generation. Major areas where AFBC development work is needed are discussed. Various approaches to solving these key issues are identified and the ongoing research and development programs addressing the key development areas are described. Other significant programs pertaining to the development of AFBC for utility steam generation are also discussed and needs for future work identified.

Jan 1, 1978

By Robert E. Murray

It's indeed a pleasure for me to speak to you today about the development and operation of large-scale surface coal mining projects in the western United States. It is an exciting story about American business working to solve a critical national problem -- the energy shortage -- through research, new technologies, financial innovation, and imaginative management. The North American Coal Corporation -- the second largest independent mining company and ninth largest United States coal producer -- is proud to be a part of this story. Our operations in North Dakota reflect the coal industry's Western activities. So, today, I would like to focus on our planned involvement in that state. I'll briefly survey why North American is developing large- scale surface mining in North Dakota, and I will outline the many problems associated with this coal development and how we are working to solve them. Finally, I will look at the financial and management techniques we are using to make it all work. In short, I'm going to present a case study of Western coal mining. Let's begin by looking at the reasons we are in North Dakota. The United States Bureau of Mines estimates that 44 per cent of the nation's total recoverable coal deposits underlie the three Northern Great Plains States of North Dakota, Montana, and Wyoming. We estimate that North Dakota alone has about 25 billion economically surface-mineable tons of coal with today's technology. North Dakota has the energy that could keep our factories running and our homes lighted In the years ahead.

Jan 1, 1975

By Nikhil Dhawan, Veeranjaneyulu Rayapudi

This study investigates upgrading of low-grade banded hematite quartzite iron ore (Fe ~31%). Conventional beneficiation was found to be futile. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. Microwave exposure of coarse particles at 540 W for 10 min yielded a concentrate with Fe 56.30% and recovery of 50.68%. Conventional carbothermic reduction at 500 °C, 60 min and 9% charcoal yielded a concentrate with Fe 57.6% and iron recovery of 68%. The presence of sufficiently bonded silica leads to an easy formation of a fayalite phase. The microwave reduction design yielded FeG of 57.6%, FeR of 47% and a yield of 24% at an optimal condition of 540 W, 8 min and 6% charcoal. It was found that a small fraction of microwave-irradiated ore-charcoal mixture melted rapidly, and pure ferrite balls were observed within 8 min. An optical micrograph of a ferrite ball reveals the retained austenite and martensite phase.

By Donna L. Boreck

In an effort to increase recovery in thick and closely spaced coal seams, the Bureau of Hines, U.S. Department of the Interior, is studying the feasibility of introducing three mining methods-high-face longwall, multi-slice longwall, and longwall caving-in western coal operations. Geology plays a significant role in determining the success of such methods. Some of the factors that will affect development are as follows: (1) thickness and three-dimensional configuration of the seam, (2) cleats, joints, and fractures in the coal and roof rock, (3) roof composition and variability, and (4) coal quality and changes in quality within the seam. Through geologic mapping, the presence of many of these factors is predictable prior to development.

Jan 1, 1987

By Bülent Erdem, Zekeriya Duran, Tuğba Doğan

The objective of this study was to evaluate the potential health risk associated with exposure of dozer operators to whole-body vibration. Measurements were made on 31 dozers used in different surface mines in Turkey. Predictions of adverse health effects of vibration were based on the standards BS 6841:1987, ISO 2631–1:1997, ISO 2631–5:2004, and the EU Vibration Directive:2002. Operators experienced high and comparable levels of vibration acceleration and dose during all dozer tasks: pushing the material (DOZE), moving forward (FORWARD), moving backward (REVERSE), and ripping (RIP). Specifically, DOZE, FORWARD, REVERSE, and RIP showed high potential of adverse health effects in terms of vibration dose according to the worst-case axis and vector sum criteria and a moderate adverse health effect for acceleration according to the worst-case axis criterion. Operators of large dozers were exposed to lower levels of vibration. However, no statistically significant relationship between vibration exposure levels and the propelling mechanism and the service time of dozers, operator experience, operator age, and ground type was found.

Jun 16, 2022

By A. J. Abraham, K. E. Seitz, J. D. Humphrey

Caterpillar has led the way for sound reduction in off highway trucks (OHT) used for mining. In 2000 Caterpillar introduced the 793CXQ sound reduction OHT (Figure 4) to meet local noise level demands in the Hunter Valley near Sydney, Australia. The sound level of the mining equipment in the Hunter Valley is being reduced to pre-serve the quality of life for the residents of the area. To meet the levels established required a major redesign of the 793C, as a result the sound power level was reduced by 9 dB (A), which is a less than 1/8the original sound level.

Jan 1, 2004

By B. K. Parekh

Silicon carbide (SiC) can be produced by heating rice hulls to elevated temperature, The product is a mixture of beta crystalline silicon carbide whiskers, particles and unreacted carbon. The silicon carbide whiskers are 0.5 micron in diameter and 50 to 100 micron in length and have been found useful for reinforcing metal and other composite materials. The carbon can be removed by combustion, but this makes separation of the silicon carbide whiskers from particles difficult and a high grade whisker product cannot be made. However, a clean high grade Sic whiskers product can be obtained from the pre-burned converted rice hulls using physical separation processes that are based on differential wetting. Recovery of Sic whiskers from the pre-burned material was found to exceed 90 percent. A modification of the froth flotation process developed during this study is now being used commercially to separate silicon carbide whiskers and particles and to recover a high grade whisker product.

Jan 1, 1985

By Faruk Oksuz, Dave Schiemann, Miguel Sanchez, Patrick Jensen

"The McCook Main Tunnel connects Chicago’s Tunnel and Reservoir Plan (TARP) Mainstream Tunnel to the McCook Reservoir. The tunnel system consists of a 10 m (33 ft) finished diameter and 490-m (1,600-ft) long hard-rock tunnel constructed from a 27.5-m (90-ft) diameter and 92 m (300 ft) deep main gate shaft. The gate shaft houses six high-head 4.4 x 9 m (14.5 x 29.5 ft) wheel gates installed in the bifurcated and steel-lined section of the tunnel. The tunnel also includes portal and energy dissipation structures as it daylights into the reservoir. Construction of the McCook Main Tunnel in live flow conditions was a challenging task for the McCook Main Tunnel Project participants, the project owner U.S. Army Corps of Engineers (USACE), local sponsor Metropolitan Water Reclamation District (MWRD) of Greater Chicago, designer Black & Veatch and contractor Kiewit Infrastructure Co. (Kiewit). Once completed in two stages in 2017 and 2029, the McCook Reservoir will hold 38 billion L (10 billion gal) of combined sewer overflows (CSO) and flood waters from the city of Chicago and 36 surrounding communities in Cook County, IL The construction of the tunnel system was divided into two contracts. The first contract for the gate and construction access shaft was completed in August 2011. The second contract included tunnel excavation and concrete and steel lining that was completed in September 2014; installation of gates and hydraulic cylinders that was completed in June 2017; and the last major construction activity was the removal of a temporary concrete plug (bulkhead) and lining that tunnel section to bring the overall tunnel and gates system online before Dec. 31, 2017.This article focuses on the installation, testing and commissioning of the high head wheel gates. Live tunnel connection details to TARP Mainstream Tunnel were addressed in a previous paper submitted at the World Tunneling Conference in 2016."

Mar 1, 2019

By Dr. R. W. Mead

There are two basic problems when one attempts to separate a solution of metal ions utilizing a chelation-solvent extraction cascade (commonly called liquid ion exchange). First, it is impossible to produce any great degree of separation unless the separation factor (also called selectivity, which is the ratio of the distribution coefficients) is very large. Second, the richest possible extracted product, using an infinite number of equilibrium stages, is at best only in equilibrium with the feed solution. These factors combined with equipment design considerations have led to a situation where only the most selective chelating agents are applicable to economic industrial operations. The authors know that distillation techniques are used routinely to separate compounds with nearly identical relative volatilities and that there should be a way of operating solvent extraction cascades in an analogous manner to obtain separations of metal ions. The advantage of this approach would be that solutions of metal ions of any desired purity could be obtained even if the separation factor was close to unity. This paper presents this idea and suggests some possible applications.

Jan 1, 1977

By William F. Stowasser

The United States has traditionally been the world's largest producer and net exporter of phosphate rock and related fertilizer products with the exception of rock exports from Morocco. In recent years, however, U.S. producers have faced increasing competition from operations in foreign countries, leaving the future position of the U.S. phosphate .industry as a leader in the world markets somewhat less certain. This paper will review the U.S. phosphate rock industry in relation to its known demonstrated reserves, its historical and present production and export levels, and its future mining potential. The paper will include an analysis of the availability of phosphate rock in the United States represented by cost-tonnage relationships. The U.S. phosphate rock industry has for decades provided raw materials at reasonable costs to the phosphate fertilizer industry, and the fertilizer products have been made available to both domestic and international markets. Natural soils normally contain low quantities of phosphorus, and cultivation exhausts the available phosphorus through the removal of harvested products. Yields diminish, and it becomes necessary to apply phosphorus to the soil in an amount at least sufficient to compensate for removal. Raising the level of phosphorus also permits nitrogen and potash fertilizer nutrients to be effective and sustain the high crop yields necessary to support increasing food demands. In only a few areas of the world are soils, climate, rainfall, and low-cost phosphate fertilizer available to assure high agricultural yields in successive years. One of these areas is the central United States and south central Canada. By contrast, in the Soviet Union, the weather conditions in farming areas frequently cause crops to either bake or drown in the field. To attempt to counter the effect of weather on production, the U.S.S.R. has increased use of fertilizer and equipment in recent years. The effect of fertilizer on various crops has been documented, and in all cases, improvements in yield and plant development were noted, as was the ability of fertilizer to mitigate the effects of unfavorable climatic conditions. Phosphate resources can be classified as either identified or undiscovered. In the identified classification, we are principally concerned with demonstrated phosphate resources, or those that have been measured or indicated. In the southeastern United States, the phosphate mining areas of Florida and the Carolinas have been explored and drilled extensively in attempts to locate new deposits. The exploration programs indicate that another Florida Bone Valley Formation or North Carolina Pamlico River Deposit is unlikely to be discovered in the southeastern U.S. coastal plain. Phosphate rock deposits of commercial interest in the western United States are located in Montana, western Wyoming, northern Utah, and southeastern Idaho. The deposits are in the Permian Phosphoria Formation with most of the mining activity occurring in Idaho. Although substantial demonstrated resources have been identified, recovery costs and the field's isolation from markets have restricted growth of the industry in the west. The phosphate rock deposits in Tennessee are well known, and it is estimated that about 29 million metric tons1 are potentially recoverable. Undiscovered deposits of brown rock in Tennessee would likely be quite small.

Jan 1, 1985

By D. O. Murchu

Outokumpu Tara Mines located near Dublin, Ireland is Europe's largest producer of lead and zinc concentrates. To reduce dewatering costs and to improve environmental and working conditions, elimination of the lead concentrate thermal dryer was required. This paper describes the development and implementation of the pressure ceramic technology at Tara to replace a conventional vacuum filter/oil-fired dryer system. In 1996 the pressure ceramic filter dewatered 66,600tonnes of lead concentrate, producing a cake at 6 % moisture. Substantial operating cost savings have been realized. Commissioning of a second pressure ceramic filter to handle over 300,000 tonnes/year of zinc concentrates is scheduled for the first quarter of 1997.

Jan 1, 1997

By Sunny Schoone, Maximilian Getz, Felix Leaman, ELISABETH CLAUSEN

Jan 5, 2023

By W. D. Bullock

The King-Beaver mine of Asbestos Corporation Limited operates an open pit in the city of Thetford Mines, Quebec. The approximate loca-tion of the open pit is at Latitude 46° 02' North and Longitude 71° 20' West. The general topography is 1020 feet above sea level. Thirty-six percent of the company's scheduled asbestos ore production, for the Thetford Mines area, comes from the King-Beaver pit. The pit operates 24 hours a day, six days a week. Normal production is 10,500 tons of ore per day at a waste to ore ratio of 2 to 1. The remaining ore requirements are mined from the King-Beaver underground mine and the British-Canadian mine.

Jan 1, 1980

By A. S. Kane

According to the 1966 Bureau of Mines Mineral Year Book only three states reported production of lignite in that year. These state: were North Dakota, Montana, and South Dakota; although it is known that there is production of lignite in Texas, California and, perhaps, Arkansas. In the year 1966 North Dakota produced 3,543,000 tons of lignite, Montana produced 328,000 tons of lignite, and South Dakota produced 10,000 tons of lignite. In view of the fact that North Dakota produces approximately 95 per cent of all the lignite reported in the United States, in discussing lignite mining, my remarks will be confined to lignite mining as conducted in North Dakota and will be confined to the production of lignite by stripping methods, as this is the predominate method used today. The first lignite mining in Worth Dakota, undoubtedly, was done by people settling in the western part of the state where wood was scarce and where lignite is exposed in the banks of creeks and ravines. The first production records were kept in 1884 and indicate that 35,000 tons of lignite were mined that year. The growth of the lignite industry has been very slow during the intervening period, but in 1966 production started to increase, and it is now indicated that production in the next few years may approach 6,000,000 tons per year. Ninety-seven per cent of the lignite produced in the lignite area of the Midwest is utilized in the generation of electric power, and it is anticipated that this use will predominate during the next two decades.

Jan 1, 1968