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By D. An, J. Withers

A nano-scale investigation has been carried out by applying an AFM (atomic force microscope) to study in situ the adsorption of various collectors, i.e., oleic acid, octanohydroxamic acid (HA), and salicylhydroxamic acid (SHA), on bastnaesite in aqueous solutions. The obtained AFM images show that the surface morphology of bastnaesite changes greatly after it contacts the solutions of the collectors, suggesting that all these collectors can effectively adsorb on bastnaesite. Increasing temperature can help increase the adsorption of oleic acid on bastnaesite. FTIR (Fourier transform infrared) results also show that all these collectors adsorb strongly on bastnaesite with a strong absorbance spectra being detected, which confirms with the results obtained with AFM imaging analysis. In general, hydroxamic acid collector (HA and SHA) adsorbs on bastnaesite mainly in the form of insoluble metal hydroxamate. This specific adsorption mechanism explains that a high selectivity with a moderate collectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite. INTRODUCTION Rare earth metals, which are very important to modern industry, are generally extracted from numerous rare earth minerals. In practice, however, the actual extraction of rare earth is mainly from bastnaesite, monazite and xenotime. The Mountain Pass mine is one of the largest rare earth mine in the world, at which the main rare earth mineral is bastnaesite. In the past years, froth flotation has been applied to the beneficiation of Mountain Pass ore. In practice, the rare earth ore is usually crushed, milled and further separated from calcite, barite and other gangue minerals by froth flotation, in which the rare earth oxide-bearing minerals stick to aerated bubbles in the pulp and float to the surface, leaving the gangue at the bottom of the flotation cell and disposed of as tailings.(Bulatovic, 2010) In spite of the fact that froth flotation has been applied to treat the bastnaesite ore at the Mountain Pass mine, the rare earth oxide (REO) recovery is still low,(Anderson, 2015) especially compared to the one obtained with sulfide flotation. For example, the typical recovery obtained at the Mountain Pass mine was only about 70%. This may be due to the low selectivity of the collector (oleic acid). In addition, to enhance the flotation selectivity, the pulp in the mine circuit has to be heated up to 70 to 90°C and it involves a lot of energy consumption. Last but not the least, a lot of depressants have to be added to improve the selectivity of flotation process. Therefore, it is critical to re-examine the existing flotation process at the Mountain Pass mine and seek any chance of improvement. (Anderson, 2015)

Jan 1, 2019

By K. J. Sollman

With an ongoing concern for safety and health in the workplace, NYCO® requested three medical evaluations be undertaken to study possible health hazards of wollastonite. Two of the evaluations were conducted by the National Institute of Occupational Safety and Health (NIOSH). One was in 1976 (Ref. 1), and the second in 1982 (Ref. 2). The aim of the two studies was to answer the following two questions: 1. Do wollastonite workers exhibit more respiratory abnormalities than workers not exposed to wollastonite? 2. Is there a relationship between prevalence of respiratory abnormalities and accumulated expo-sure time to wollastonite?

Jan 1, 1988

Early experiences suggested autogenous mills were difficult to operate and consumed substantially more energy than conventional rod/ball mill circuits. As our understanding has increased and the technology has matured this perception has changed to the point where most new comminution circuits are ag/sag based. In addition many operators have replaced existing conventional circuits with this technology. The JKMRC has been studying ag/sag mills for over 20 years. During this time it has amassed what is probably the single largest and most detailed data base of pilot and full scale mill operations in the world. This has been used to help develop and refine its cur- rent commercially available mathematical model of ag/sag mills. A decade of its application has greatly helped simplify both design and operation of ag/sag milling circuits as well as helping to promote the effective use of recycle crushing, secondary crushing and closed-circuit operation. This paper describes the development of ag and sag milling in terms of our understanding and the evolution of the technology. In addition the application of mathematical modelling and simulation in designing and operating efficient circuits is described with the aid of practical examples.

Jan 1, 1998

By Robert Turner

Gold and silver processing techniques are some of the oldest in the mining industry. Gold mining of high grade veins and deposits has existed for centuries. However, only with the higher gold prices in recent years and heap leaching techniques have the low grade gold and silver deposits become feasible to mine and process economically. By mining and hauling 3,600,000 tons of ore per year at an average grade of 0.03 ounces/ton gold and 0.385 ounces/ton silver, the Zortman- Landusky operations became profitable in 1982. To maintain profitably, a stripping ratio of less than one ton of waste to one ton of ore, and mine run ore placed on the leach pads which will yield approximately seventy percent go1 d recovery.

Jan 1, 1984

By Raymond Sandiford, Taehyun Moon

"In 2012, Superstorm Sandy (Sandy) caused extensive flooding in many of the tunnels in New York City. The inundation resulted in two distinct stress changes to the tunnel structures. The first stress change was water pressure on the inside face of the tunnel lining. The second condition related to the change in buoyancy of the tunnels. In areas where the tunnels were supported on rock and an adjoining area supported on soft soil, overstress issues arose. Numerical analyses were performed to assess the structural impacts of the tunnel water inundation; especially stress changes due to internal pressure as well as changes resulting from the buoyancy effects. The paper will discuss the assessment process and its results; it will demonstrate that the change in internal pressure were of little consequence, however the change in buoyancy resulted in significant increases in bolt stresses. INTRODUCTION Superstorm Sandy caused tens of billions of dollars in damage in the NYC metropolitan area. It also caused significant disruption to the transportation system by flooding most of the under river tunnels servicing Manhattan from the outer boroughs and New Jersey. The rehabilitation of the tunnels was of paramount importance to the restoration of the NY and NJ economies. With this rapid restoration, it was essential to determine whether the flooding of these tunnels caused damage to tunnel structures. A series of analyses were undertaken to ascertain whether the change in the stress conditions and buoyancy of the tunnels, due to the flooding, was significant enough to cause damage or over-stressing of the tunnel components. The effects of this unforeseen loading condition was a concern to the agencies operating these tunnels and were thus analyzed to ascertain if there were any adverse impacts. This was a concern because the majority of under river tunnels in NYC was built earlier in the century and constructed using bolted cast-iron lining segments. The cast iron, although quite strong in compression, is much less so in tension. Also, after nearly a century of use, the bolts connecting these segments together have under gone varying degrees of corrosion. The stress changes in both the liner segments and the supporting bolts were estimated for conservative ground support conditions to provide confidence that the flooding had not caused permanent damage."

Jan 1, 2016

By Harrison A. Schmitt

During .the past five decades or so we have passed from a time when it was difficult to point to a mine or an ore body and verify that it had been discovered by geological methods, through the. Twenties when the common saying was, "Who ever heard of a mine found by a geologist?", to recent decades when hundreds of mines and ore bodies are acknowledged geological discoveries and the above query can be ignored. Recently, however, the application of mining geology appears to have been downgraded, or so it seems to me. Basic geology in mining has been cheapened and glossed over in favor of geophysics and outcrop sampling, even though the latter is merely one technique of mining geology and, to some extent anyhow, has been used for a. long time. (Locke, 3, pp 81-87). Geophysics by itself and in conjunction with geology has had success in certain geological provinces, but limited attainment in mountainous terrane except in those few cases where strongly magnetic minerals are associated with ore. Nevertheless, in the Cordillera .many experimental techniques are offered as proved ones. This is not an intent to try to depreciate honest geo- physics. Continued experimentation and use of it is approved by all, but at the same time it is foolhardy to throw mining geology overboard, Generally both approaches should be considered and usually, at first anyhow, geology is the most direct one.

Jan 1, 1960

By Robert J. Watters, Peter C. Kelsall, Joseph G. Franzone

Two separate studies investigated the compressive strength of basic igneous rocks and its relation to index properties such as porosity, density and soundrave velocity. The rocks tested were weathered dolerite from S. W. England and vesicular lavas from California. In both cases strength was affected considerably by porosity. In the dolerite, strength was also affected by fissures (microcracks) which were formed in the parent rock by shearing and later accentuated by weathering. While test results show that porosity, density and sound velocity are not reliable indices of rock strength, these properties are useful in interpretation of strength test results. Index testing can be used to classify samples according to similar behavior and to recognize the influence of fissures.

Jan 1, 1986

By Joseph D. Martinez

Salt, because of its plasticity, exerts a major influence in deformation. Resulting salt structures are common world-wide. A special type, salt domes, are associated with thick sequences of sediments deposited over salt. Their upward intrusion is generally thought to be in response to buoyancy. Mines in salt domes reveal an internal pattern compatible with large amounts of vertical flowage. Caprock, the end product of accumulation of anhydrite from salt dissolution, attests to long continued upward growth and concomitant truncation by moving underground waters. Concepts of modes of growth are evaluated and related to problems in utilization.

Jan 1, 1979

By Takeshi Tanaka, Shinya Ono, Tsuyoshi Kato, Masaji Kato, Yuusaku Tominaga

The knowledge of the macroscopic characteristics of a ventilation network is of fundamental importance for taking counter- measures to increase air quantity in-specified branches, such as those corresponding to working faces at advancing entries or longwall panels. Because the ventilation characteristics are inherent properties of each mine, it takes a long time for an engineer to accumulate experience on how a specific regulator may affect the air quantity in a specific branch of a mine with a complicated ventilation system. A computer-simulation training system, based on the macroscopic ventilation characteristics, is presented in this paper. When a trainee selects a specific condition from five regulator option (closed, almost closed, slightly open, half open, open), the change in air quantity for a network branch is indicated by the color allocated to the ratio of the new air quantity to the old or planned air volume. After the ventilation simulation, the colors in the specified branches are defined by using the fuzzy set theory. The trainee continues practicing the selection of closed/open conditions for different regulators until each of the specified branches is displayed in good state of airflow. The ventilation net- work of the Horonai coal mine is used as an example of the training system to control air quantities in six working faces with 33 regulators.

Jan 1, 1996

By Pentti Seppanen

The activities of Outokumpu Oy in the mining industry span all branches from prospecting to the production of refined metals and the manufacture of semifinished products. Products include copper, zinc, mercury, cadmium, nickel, cobalt, sulfur, gold, silver, iron ore, stainless steel, selenium, ferrochromium, lead and chromium concentrates, as well as chromite foundry sand. In addition, the activities of Outokumpu Oy extend to development and production of instruments, planning of industrial projects and instrumentation as well as the manufacture of specialized machines for ore concentration. The company now operates ten mines, eight of which are underground and all of which are in sulfide deposits except one. The fully automated monitoring and control of underground mine ventilation at the Pyhasalmi mine are an important technological contribution to the industry. Development work on the ventilation control was started in 1969, and since May 1973 it has operated in a fully automated computer-controlled mode. The Pyhasalmi mine has been in production since 1962, having begun as an open-pit operation. Development of underground mining began in 1967. The present annual production is one million tons all from underground mining. The underground mine is equipped with a main shaft and an auxiliary shaft, and two raises for ventilation. There is also a rampway from the surface to a depth of 500 m. The main shaft is for ore hoisting and the auxiliary shaft is used for waste-rock hoisting and for downcast ventilation. One of the raises is for downcast ventilation and the other is for upcast ventilation. The mining methods employed at Pyhasalmi are sublevel stoping with backfill, sublevel caving, and sublevel shrinkage stoping. Copper and zinc concentrates are produced. The Pyhasalmi mine is highly mechanized with about 4000 installed diesel horsepower underground. The maximum capacity of fresh air is 150 m3/s.

Jan 1, 1979

By Barry Silverman

As a significant mineral supplier, consumer of primary fuels, and producer of wastes and emissions to air, water, and land, the domestic copper industry through its investment and operating decisions influences the nation's economy and the environment. In turn, the copper industries' decisions are influenced by various factors: government energy and environmental policies, economic conditions, and technological considerations. The authors have developed a framework for assessing in an integrated manner the impact of these factors on the future investment and operating decisions made by copper firms. Specifically, this model is designed to capture the technology forcing nature of regulatory constraints, the differential situation of individual copper deposits and plant locations, and the price of factor inputs and conditions in the nation's economy. The capability to do this has only become real because of the decision of the U.S. Bureau of Mines to create Mineral Availability system1 or MAS. This system contains detailed but confidential information about each mine and mill in each of 35 mineral industries." Without MAS or a similar information system, the utilization of the methodology we offer would be impractical, but with. MAS it offers a unique technique of dealing with environmental-resources policy questions.

Jan 1, 1979

By K. Norris

The Amax Gold Guanaco mine is located in the Atacama Desert, approximately 260 km southeast of Antofagasta, Chile. The 6,000 tpd leach operation produces approximately 90,000 oz of gold, and 360,000 oz of silver per year. Production began in 1987, and the operation has been managed by Amax Gold since 1992. The mine has been plagued in the past by high operating costs and low production. Several significant changes have been made to the operations which have resulted in lower costs and higher operating efficiencies. A review of these changes is presented herein.

Jan 1, 1997

By K. W. Harris, K. A. Perry

Reserve depletion in Central Appalachia is continuously creating unique ground conditions for underground coal mines with many of these difficult environments directly attributable to multiple seam mining and/or deeper overburdens. While many empirical studies have been performed in an effort to improve understanding of these problems along with potentially improving safety and extraction, many of the difficulties encountered lie outside of the normal realm of expected behavior. This is often the case when mining in bump prone ground, where additional concerns are introduced and design buffers are warranted. The boundary element software LaModel was used to study three bump events in a deep-cover, multiple-seam reserve located in Harlan county in the Kentucky region of Central Appalachia. This region is notoriously bump prone due to significant areas of deep cover, the presence of strong to massive lithology (such as sandstone), and an extensive history of underground mining that increases the probability of multiple seam interactions. Multiple seam interactions are best understood with respect to site-specific parameters, including both the geological and geometrical components of interburden, overburden and mine workings. Initially, empirical-based approaches (ARMPS/AMSS) were used when attempting to back-analyze the bump events. However, it was recognized that a more detailed investigation was necessary to understand the fundamental causes/conditions associated with the bump events. Consequently, the LaModel study resulted in a mine-specific calibration method for the reserve. With this method in place, enhanced bump prediction throughout the reserve is expected, such that the stability, recovery and safety of future mining may be improved.

Jan 1, 2014

By W. C. Streib

A wide variety of materials have satisfactory to superior insulating properties and can be used to control the flow of heat, provide energy savings, improve personal comfort and contribute to personal safety. Such materials range from completely organic products--both of natural origin and synthetics--to completely inorganic. In many cases, thermal protective systems are actually combinations of both. Obviously, those insulating materials which are principally inorganic have the inherent advantages of low to minimal combustibility as well as utility at vastly elevated temperatures. Both of these properties are highly desirable in providing not only thermal energy conservation, but also personal safety in residential and commercial applications. As the thermal insulation needs of man and industry have developed, there has been an ever-increasing demand on the minerals industry to provide the resources required to fill these needs. On a global scale, industrial minerals have become the fundamental base upon which today's thermal insulation industry has been built. The use of minerals to control heat flow range from the most unsophisticated applications to those requiring the ultimate in scientific technology. In many cases the minerals are themselves converted in- to the major insulating media; for example, fiber glass, rock wool or refractory fiber. In other cases, minerals are used as the chemical reactants to form the binder matrix which in turn provides the product strength required for adequate handling and installation; for example, calcium silicate bonded products wherein the binder is the reaction product of lime and silica. In still other cases, low density mineral products are added to a high density binder System to provide lower weight and better insulating properties; for example, the use of expanded perlite in concrete.

Jan 1, 1976

By Staff

Assembling consistent data for a 40-year time series is a challenge because of the many changes that have occurred in this period. In many cases, because of process improvements and consumer requirements, grades of materials change in a 40-year span. This can lead to a wide fluctuation in price data simply because of increased costs for premium grades. Sources for obtaining price data can also change during a 40-year period. Changing the data source also introduces anomalies in a time series. In some cases, published price data are not representative of the real value of the material and provide little basis for further analysis. For some industrial mineral commodities, there are only a few producers, and value and production data are considered proprietary. In the data presented in this chapter, every attempt was made to ensure that the data were as consistent and representative of the industry as possible. However, the factors mentioned above may have introduced inconsistencies in some of the data series. Many different factors influence trends for industrial minerals because of the diversity of end uses for these commodities. Trends in production and prices for most of the industrial minerals can be related to one or more of the following: changing demand or technologies in end-use industries, development of new end uses, the effect of environmental regulations, production and processing technology changes, energy costs, foreign competition and substitution by other materials, and production as a byproduct of other minerals. World economic conditions, such as recessions and inflation rates, also play a part in some production and price trends. Data for 40 years of production for industrial minerals in the United States are presented in [Table 1] in 10-year increments. Unit values for the industrial minerals, in actual and constant 1990 dollars, are shown in [Tables 2 and 3].

Jan 1, 1994

By Ted C. Mathews

Pre-concentration by sorting is as old as the mining industry. Inevitably waste rock is broken with ore. Separation may take place in the stopes by selective mucking and transport, or selective loading and transport of ore and waste by 12-cu, yd. shovels and 100-ton trucks in large open pit operations. Hand sorting of 1" to 16" pieces, formerly widely practiced at underground chutes and prior to or following first stage crushing, has greatly diminished in the United States with its high per hour labor cost, although still widely practiced in other countries and, surprisingly, in some of the most modern mills where inexpensive labor is available. The economics of pre-concentration by sorting is attractive since elimination of waste at any cost less than the total milling cost will show a profit. The size at which sorting should be under- taken is determined by the size at which liberation is secured to yield a product of ore and waste, and greatly influences cost and the point in the flowsheet where sorting can be undertaken. In some instances mining costs can be reduced where an inexpensive sorting system to eliminate waste is combined with a less selective and less costly mining method. This is particularly true in deep mines where hoisting capacity determines the rate of extraction and sorting is performed underground, with waste utilized for fill. Hand sorting, while efficient, is expensive because of low sorting rates. Peale (1) quotes man hour capacity at 1/3 ton per hour on sizes 3/4" to 3" copper ore, and up to 5 tons per hour on rich iron ore sized from 4" to 16".

Jan 1, 1974

By John E. Wallace

A recent study by the New York Trap Rock Corporation has conclusively determined that the number of blasting complaints is directly related to the noise produced by the blast. In turn it has been known for some years that the noise produced by the blast is directly related to atmospheric structure of temperature, wind, and humidity in the vertical direction. Normally during daylight hours the temperature decreases with altitude at the rate of about five and one half degrees per thousand feet on a sunny day, and to somewhat lesser amounts on cloudy days. Consequently, sound travels slower with altitude because of the lower temperature, and the sound rays tend to bend skyward, and are soon dispersed in the atmosphere. Quite frequently, however, the temperature increases with altitude, and just the opposite effect is attained. That is sound rays are bent downward, and sometimes reach the ground with intensities approaching that at the source. When the temperature increases with altitude a temperature inversion is said to exist. Less frequently than these two atmospheric conditions a condition is observed where temperature remains constant with altitude. This is called an isothermal atmospheric condition, and sound passing through this type of atmosphere tends to travel in straight lines, neither bending upward nor downward. The sound will be greater than normal near the blast, but will dissipate rapidly with distance from the blast site with no zone or zones of silence.

Jan 1, 1962

By Stanley Kesler

The first of two initial 650-mw units of the Paradise Steam Station, located on the banks of the Green River in the south-central portion of the western Kentucky coal basin, is scheduled for operation in late fall of 1962. Location of the site is shown on the map of figure 1. This plant will be the eighth, large-capacity,, modern station built by TVA in a series starting with Johnsonville, operated first in 1951. During that period of 10 years,, unit sizes have increased from a capability of 125 mw to 500 mw at the recently completed Widows Creek Unit 7 addition and at Paradise to 650 mw. This new unit will take its place in a power system that serves an area of some 80,000; square miles with a present installed capacity of over 12,000 mw. Upon completion of the Paradise units and other additional hydro and steam units presently under construction, the system capacity will have reached over 15,000 mw. Projected load estimates indicate that this system will provide a margin' of slightly under 10 percent of dependable capacity above peak demand at that tire. One Paradise 650-mw unit at that time will represent approximately 4 percent of the total system installed capacity.

Jan 1, 1962

By M. A. Klugman

[This paper represents a portion of a lager study, concerning dispersion patterns of major, minor and trace elements in wall-rock about ore-bodies in part of the Colorado Mineral Belt. This phase of the work pertains to the Mg/Ca ratio variations in wall-rock adjacent to ore-bodies in two mines of the Alma-Horseshoe Mining District of Central Colorado. The mining district is located 80 miles southwest of Denver (Figure 1) on the east flank of the Mosquito Range. The area is typified by rugged relief with altitudes from 10,500 to 14,000 feet.]

Jan 1, 1962

By Daniel C. McLean

Chemistry plays a more important role in milling operations than is generally recognized, particularly in fluid- solid separation processes. Chemical aspects are also very important insofar as plant water quality is concerned, and in the manner in which this water quality effects plant design and operation. Aside from the inherent chemical characteristics of plant water, the mineral preparation industry is becoming increasingly more dependent on the use of mining chemical reagents--relatively new to the coal industry, but items of I standard usage in complex metal recovery plants. These chemicals have many useful properties and can produce significant improvements in operations and metallurgical efficiencies when used properly and intelligently. They can produce poor results and sometimes severe losses when used improperly. Most reagents are relatively expensive on a per pound basis, hence costs can be excessive if they are used wastefully or inefficiently.

Jan 1, 1968