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By E. R. DeMen

In late 1965 General Mills announced the availability of a new liquid ion exchange reagent, LIX®-64, for the recovery of copper from various solutions, such as dump leach liquors. Acceptance of this material by the copper industry has been gratifying. A number of pilot plants have been operated, and at this writing there are four commercial plants either in operation or under construction. The properties and operating characteristics of this reagent have been described in previous papers.1,2 LIX-64 is quite effective and selective for copper extractions although partially limited in pH ranges, losing extraction efficiency as the acidity of the feed solution increases to below pH 1.0. Also, the LIX-64 content in the kerosine carrier was limited to about 10 volume percent (except for special cases) because of rapidly decreasing phase disengagement rates above this content. This in turn led to large plant capital costs, as the organic flow rates had to be in- creased (rather than LIX-64 content) to extract the copper from high content liquors. This was true in all circuits where the feed copper content ran above 2.0 g/l copper. A reagent was needed which would extract copper from more acidic liquors (or higher copper content liquors) and which exhibited improved phase disengagement characteristics with reagent contents up to 30 volume percent. General Mills is pleased to announce the availability in commercial quantities of a new and improved reagent, L+-64~. This reagent broadens the pH range in which copper can be extracted, and exhibits superior phase disengagement characteristics. The improvement in the reagent has been noted in laboratory circuits, as well as pilot plant runs and commercial operations.

Jan 1, 1970

By James Withers, Dongbo An, Jinhong Zhang

A micro-scale investigation was carried out by applying an atomic force microscope (AFM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to study in situ the adsorption of three different collectors — oleic acid, octanohydroxamic acid (HA) and salicylhydroxamic acid (SHA) — on bastnaesite in aqueous solutions. The results show that all three collectors adsorb on bastnaesite. The hydroxamic acid collectors — HA and SHA — adsorb on bastnaesite mainly in the form of insoluble metal hydroxamate. Their specific adsorption mechanism indicates that high selectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite.

Due to deposit shape and dimension, narrow vein makes reserve modeling, geological control, stope design, drill and blasting more challenging. It needs high standard quality control as errors can be created easily, which could cause significant amount of ore loss or dilution. From channel sampling, survey control, reserve modeling, drill hole design, blasting, communication with underground drillers to backfill, this paper illustrated every step and its quality control of a long hole stope mining. Compared to other narrow vein mining methods (cut and fill and shrinkage), long hole stoping means higher production, less labor, and significantly lower cost when deposit characteristics allowed.

Jan 1, 2012

By Juan J. Monsalve, AMAN SONI, Nino Ripepi, Richard Bishop

The design and strength of pillars are important parameters when implementing the room-and-pillar mining method in a limestone mine. The process becomes complex with the presence of karst voids, which are frequent phenomena in carbonate rock formations. This research continues a previous study aimed at studying the effect of karst voids on the strength of a particular limestone pillar. Using calculated pillar strength and estimated redistributed stresses, it was assessed that the pillar can counter more stress than currently imparted on it. Numerical modeling studies combining in situ stress determination and excavation sequencing were used to estimate the existing stresses on the pillar. Different possibilities of modification to existing pillar design were simulated using distinct element method (DEM) modeling to determine a better design.

Jun 1, 2023

By Hans W. Schreiber

Most geologic and mining engineering consulting firms* began to experience the recession with declining billing levels, number of inquiries, and proposal requests in late 1981 or early 1982. As of today, most of them have been functioning at reduced income levels for nearly a year. And while many consulting firms have apparently reached a stabilized income level, they can see little prospect for attaining normal (pre-late 1981) billing levels and income for the remainder of 1983. A few firms have escaped being affected by the recession. Such com panies almost without exception are small (fewer than 20 personnel), offer a limited range in technical capabilities, and tend to be highly specialized in a particular niche. They include those specializing in the heap leaching of precious metals ores, in ground water testing programs, and in the derivation of computer-aided programs to monitor particular mineral processing functions. Those firms affected by the economic downturn have instituted a variety of policies and undertaken actions to cope with significantly reduced incomes to bring fixed costs in line with the depressed demand for services. These changes fall into the following broad categories: • management and management practices; • markets and market definition; • marketing and the pursuit of assignments; and • administration and personnel relationships. Not all of the perceived changes have necessarily been instituted by every consulting firm, and any one appears sporadically instituted. Management and Management Practices In favorable times the managers, and often the owners of the equity, of consulting firms tend to concentrate their attention on the part of the business they find most satisfying and enjoyable. For some, this means acting as project or assignment leaders, even undertaking a specific technical aspect of the job. For others, it means constant marketing with the associated heavy travel and entertainment schedules. In unfavorable conditions, such as the current recession, managers tend to spread themselves far more thinly, expending time and effort on all facets of the business including marketing, proposal preparation and cost estimating, budgeting, general administration, accounting and cash flow monitoring, project/assignment overview, and actual client work. The manager who in favorable times concentrated on client work is now less billable. The manager who concentrated on marketing is somewhat more billable. The manager now needs to pay attention to and expend equal effort on each facet of the business just to keep all the facets in relative balance. Falling behind schedule on a client job or carrying an unduly large percentage of accounts receivable exact a cost to the firm. Clearly the absolute cost to the firm is the same whether demand for service is good or slack. But in periods of slack demand the firm is frequently less able or even unable to bear such costs. Marketing and Market Definition Markets appear to have undergone some significant changes: • Federal and state governments have assumed a greater importance as providers of work vis-a-vis both industry and private groups. • Projects with increase-in-capacity aspects have given way to projects with maintenance or reduced operating cost aspects. • Projects searching for new deposits of minerals in generally new locations have given way to projects reviewing known mineral districts or known deposits. • Industrial mineral and mining companies have exhibited a great propensity to cut back the use of consultants and to undertake as much work as possible in-house. Further-more, a number of industrial mineral and mining companies have entered the competitive arena with consulting firms, submitting proposals (usually to the federal government) in an effort to keep their staffs intact and occupied. In response, consulting firms have reevaluated their capabilities by reviewing old work and reassessing personnel. The purpose is to broaden the services offered and the potential client base, thus redefining the available market. For example, a firm specializing in assessment of technical and cost parameters of a deposit would normally assist a prospective lender in judging the deposit's suitability for project financing. That same company could easily expand into the field of analyzing production costs for an individual operation -something that is needed in periods when lower prices reduce profit margins. Similarly, a firm that has confined such economic assistance to commercial banks could expand to provide its expertise to other lending and even equity buying in-stitutions such as insurance companies. Marketing and the Pursuit of Assignments With few exceptions, consulting firms have significantly increased their

Jan 2, 1983

By G. K. Hoffman

Humate, defined as weathered coal or mud-stone rich in humic acid (HA) and fulvic acid (FA) have been mined, primarily as soil amendments or drilling mud additives, in New Mexico for 15-20 years. The New Mexico humate resource is estimated to be 11 Gt, including weathered coal and organic mudstone. The HA and FA content determines the end-use, therefore a simple and consistent method of measuring organic-acid content was developed. The New Mexico Bureau of Mines and Mineral Resources method is based on repeated alkali leaching and acid precipitation. Precipitates of humate are ashed, with mass balance of solids maintained, to correct for material added during alkali-acid treatment. Analyses of upper coal member, Cleary Coal Member (Menefee Formation) and Fruitland Formation samples from the southeast San Juan Basin show ashing to be important in accurate analysis of FA content. Ash in the total FA fraction averages 70% compared to 2% in HA. The FA in weathered coal and organic mudstone are similar, although HA is significantly higher in the former. As weathering progresses, the FA content of weathered coal increases faster than in organic mudstone because of the greater total organic material in coal.

Jan 1, 1994

By Donald P. Richards

Is a shaft the same as a tunnel and can it be approached in the same manner for design and construction? The most obvious difference between a shaft and a tunnel is that of orientation; whereas a tunnel is commonly near horizontal or slightly dipping, a shaft is commonly vertical or steeply inclined. As a result, design and construction methods employed for tunneling, in general, cannot be directly applied to shafts, although some of the basic concepts of behavior are quite similar. Many of the shafts that have been sunk in various parts of the world are owned by private mining companies. Each company has generally accumulated years of experience in shaft sinking and mining techniques pertinent to its particular geographic location. When a new shaft is to be sunk or an existing shaft deepened, the tendency often seems to be to continue to use the methods that have been used successfully in the past.

Jan 1, 1979

By J. J. Reilly

The Vesta Mines of the Jones & Laughlin Steel Corporation operate in the Pittsburgh Seam in Washington County, Pennsylvania. This seam is overlain with a drawslate, 12" to 16" in thickness, which slimes readily when wet. Because of the need for a uniformly good quality metallurgical coal, the amount of reject, together with the top and particle sizes of the raw coal feed, is a serious problem at the Vesta Preparation Plant. The Preparation Plant operates two, seven and one-quarter hour shifts per day and processes 2,100 tons per hour of raw coal feed. The third shift is, used for planned maintenance of equipment. Since the water clarification equipment is so vital in insuring a uniform product, there is no alternative but that it be in operation at all times. To insure this continuous operation,. well-planned maintenance is a necessity. For years, Plant Management has kept performance records of the various units to determine the renewal dates of vital component parts, the length of wear, the various materials used in the manufacture of the equipment, and the labor cost for renewal. These records have been of inestimable help in planning an effective maintenance program to insure continuous operation of the various units.

Jan 1, 1959

By Michael J. Mankosa

Increased emphasis has been placed on recycling consumer and industrial waste products. This trend has created a new industry that is focused on recovery/ separation of byproducts from waste material. As a result, interest has increased in the development of separation systems designed for the recycling industry. Much work has been done in this area. However, existing techniques developed for minerals beneficiation are often ignored. An example of is the foundry industry. There are currently more than 3,000 foundries in operation throughout the United States. Each consumes between 9 and 900 t/d (10 and 1,000 stpd) of sand for mold production. Either silica, chromite or zircon is, used in various combinations with chemical or clay binders. After casting, the sands are typically discarded into a landfill. This practice has become an environmental concern, especially the disposal of chromite and zircon. Silica sand is not environmentally sensitive. But it is used in greater abundance (6 to 7 Mt/a or 6.6 to 7.7 million stpy)and thus has prohibitive haulage and landfill costs. Current technology for sand reclamation involves thermal treatment to remove residual binders followed by dry mechanical attritioning (Leidel, 1993; Klein, 1994). This approach results in high losses due to fines generation and high costs associated with thermal treatment. As a result, this approach has shown only limited success. Stringent regulations are also affecting the disposal of secondary materials, such as plastics and metals. This is particularly true for the ferrous and nonferrous scrap metal industry. It plays a major role in industrial recycling of steel, aluminum and copper. Applications such as wire recycling present challenging problems since a hazardous byproduct (plastic insulation) is generated by the recycling.

Jan 1, 1997

By Roger Bell

Most modern mines can profit from improvements in information handling. Recording systems in many cases were designed to satisfy certain necessary legal requirements, but not specifically to provide management information. As a consequence, the top managements of these properties work with cost data and production information that is dated, lacking in detail and clouded with supposition. It is the intent of this paper to describe an information system for a mine-plant complex in terms of the type of data, application areas and the existing equipment technology that may be applied to improve this situation. The economics of information processing and data handling will not be discussed in detail. This paper is based on the premise that information is something of value and that information processing like a manufacturing operation works for and is subject to management control. Information, the product, must be of quality, and the cost must be favorable in terms of its use.

Jan 1, 1965

By J. W. Jang

The wear behaviors of grinding media with different chemical compositions and microstructures in wet grinding of a quartz-pyrrhotite mixture was investigated under various environments. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of martensite and ferrite within the same ball. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment, while balls composed of both soft ferrite together with hard martensite exhibited decreased wear due presumably to the difference in their passivation? behaviors. The galvanic interactions between the two phases as well as among these phases and an electroactive mineral were investigated through electrochemical measurements under abrasive conditions in a slurry. The rates of formation of passive films controlled the corrosion currents of the high chromium steel media. Corrosive wear and its effect on flotation are discussed using the passivation kinetics model thereby developed.

Jan 1, 1989

By Paul G. Schmidt

The Crandon massive sulfide deposit Forest County, Wisconsin, was discovered by Exxon Minerals Company, U.S.A., in July 1975. Announced estimated in-place reserves are 62 M metric tons (70 million short tons), grading about 5% zinc and 1% copper. The reserves are evenly divided between massive sulfide are and stringer sulfide ore. The sulfide body is associated with Precambrian felsic pyroclastic rocks, and it is overlain by intermediate volcanic rocks and their derived sedimentary rocks. These rocks were subjected to greenschist facies metamorphism and were tilted to a near-vertical attitude. Geologic observations indicate a submarine-volcanic-exhalative origin for this deposit.

Jan 1, 1978

By M. D. Attfield

During 1992 a number of papers were published on aspects of respiratory disease in US underground coal miners. These included reports on trends in prevalence of coal workers' pneumoconiosis, the risks of developing coal workers' pneumoconiosis in relation to dust exposure, and the relationship between lung disease other than pneumoconiosis and dust exposure. The intent of this paper is to provide a summary of the essential findings from these investigations. PREVALENCE AND INCIDENCE OF COAL WORKERS' PNEUMOCONIOSIS Coal workers' pneumoconiosis (CWP) is usually detected in living miners through use of the chest x-ray. Deposits of dust in the lung, and the fibrotic tissue reactions to the dust, are manifested on the x-ray as small and large opacities. These abnormalities are quantified into degrees of severity using a standardized classification scheme (the International Classification of Radiographs of the Pneumoconioses of the International Labour Office). For small opacities, the scheme provides for a four-point scale of abnormality (0, 1, 2, 3), reflecting increasing profusion of the opacities on the x-ray. In this report, category 1 or greater small rounded opacities (CWP 1+) represents the earlier radiographic stages of pneumoconiosis. Large opacities, indicate the later and often disabling stage of pneumoconiosis, usually referred to as progressive massive fibrosis (PMF). Information collected in a national surveillance program for underground coal miners (the Coalworkers' X-ray Surveillance Program (CWXSP)) and a large epidemiologic study (National Study of Coalworkers' Pneumoconiosis (NSCWP)) provide a means to assess trends in CWP prevalence over the years following the reduction in dust levels mandated by the 1969 Federal Coal Mine Health and Safety Act (FCMHSA). These programs are operated by the National Institute for Occupational Safety and Health (NIOSH), and are described in detail in Attfield and Althouse (1992) and Attfield and Castellan (1992). Both studies were divided administratively into distinct time periods, and the results shown here reflect that division. Figure 1 shows the prevalence of CWP 1+ as determined from data from the CWXSP, plotted by time period and years in mining. There is evidence of a temporal reduction in prevalence. (The lack of an obvious decline in the early 1970s may be an artifact arising from use of different versions of the standard classification.) Figure 2 provides information in the same format for PMF, and shows a similar trend [ ]

Jan 1, 1993

By Ann M. Hagni

One of the most costly factors in the production of aluminum is the consumption of energy in the form of electricity. Energy consumption is increased as refractories in the Hall-Heroult reduction cells are corroded by penetration of the fluxes cryolite (Na3AlF6) and villiaumite (NaF). To decrease thermal conductivity and refractory waste, protective barrier linings are installed. Dry powder barrier linings form stable reaction products at cell operating temperatures. Four dry powders composed of vermiculite, corundum, wollastonite, and anorthite are characterized mineralogically by X-ray diffraction, reflected light microscopy, scanning electron microscopy, and cathodoluminescence microscopy in this research project.

Jan 1, 1998

By Neil S. Fishman

Tabular uranium ore in the Grants uranium region, New Mexico, occurs as tabular layers of a urano-organic mixture suspended within host sandstones of the Morrison Formation. The intimate urano-organic association points to the organic material as the main ore control. Petrographic evidence indicates that the organic material was postdepositionally introduced into the host sandstone, probably as humic acids; however, the mechanism by which these acids precipitated from solution remains uncertain. A model, the cation scavenging model, is proposed in this paper to explain humic acid precipitation. The model, supported by evidence from regional alteration studies of the host sandstones, proposes that cations responsible for humic acid precipitation were scavenged from framework grains which altered during passage of the humic-rich fluids through the host sandstone. This process, coupled with the affinity of organic molecules for each other, caused flocculation of humic acids into tabular zones. The precipitated humic substances then continued to concentrate uranium to form the orebodies. The cation scavenging model requires only one solution, the humic-bearing solution, in the precipitation process. All cations necessary for humic acid precipitation originated in the host sandstones. This model contrasts with a previously proposed model--the brine interface or two solution hypothesis--in which it was proposed that a cation-rich brine introduced into the host sandstones provided the cations necessary for humic acid precipitation. The brine hypothesis has several drawbacks, one of which is unrealistic hydrologic reconstructions necessary to accommodate mineralization at various stratigraphic horizons in the Morrison Formation. Moreover, no mineralogic evidence exists to suggest a brine occupied the host sandstones at the time of mineralization. The proposed cation scavenging model for humic acid precipitation not only readily accounts for humic acid precipitation, but also is consistent with geologic observations and regional alteration studies.

Jan 1, 2013

By Francisco A. Fonseca

The Carajás Hills are in Brazil's Eastern Amazon, between the Araguaia and Xingu rivers, and parallels 5° and 7° Latitude South. A location map is given in Fig. 1. It is an area of low mountains (maximum altitude 900 meters), covered by the Amazon rain forest. Annual average temperature is 25°C, ranging from 31°C (maximum) to 19°C (minimum). Annual rainfall averages 2,000mm. Although it rains throughout the whole year, heavy rains occur from December through March. At the beginning of the 20's, Brazilian explorationists made brief geological descriptions of the area. Due to the thick soil, scarce fresh rock outcrops and the tropical forest covering a completely unpopulated area, detailed geological studies were difficult and reconnaissance expeditions were limited to the river margins.

Jan 1, 1982

By J. Hupka

The limited effectiveness of the original hot water process for recovery of bitumen from certain Utah tar sands containing bitumen of higher viscosity (e.g. Sunnyside, Tar Sand Triangle)1,2 indicated that bitumen viscosity strongly' influences the separation efficiency. In this regard, there should exist a critical value of bitumen viscosity above which the effectiveness of the hot water process decreases significantly. Apparently certain tar sands contain bitumen of such high viscosity that even a digestion temperature of nearly 100°C is insufficient to lower the viscosity below the critical value. In addition it seems that differences in physico-chemical forces which act between sand and bitumen are negligible in comparison to the difference in visco-mechanical forces. Predominantly mechanical forces hold viscous bitumen on the rough surface and in the pores of sand particles, resulting in strong adhesion. This phenomenon is a critical feature in the phase disengagment of oil-wetted domestic tar sands with viscosity control by temperature. Besides increasing the temperature for viscosity control the effectiveness of the original hot water process could be enhanced by control of bitumen viscosity with diluent additions. Strictly speaking this appraoch is the only possibility for heavy bitumen for which the high temperature of digestion does not lower the viscosity sufficiently. As a result of viscosity control by diluent addition the digestion temperature can be lowered which is important from an industrial standpoint. Another important consideration is that effective phase disengagement occurs only when the entire bitumen phase has the same viscosity. This means that some time (penetration time) is necessary for complete and uniform dilution of the bitumen. If the viscosity of bitumen, which is a function of temperature, diluent addition and penetration time, controls the separation efficiency, hot water processing of many different kinds of tar sands should be possible, assuming that the sand phase consists primarily of quartz-type minerals.

Jan 1, 1982

By Richard Wilson

In the early 1970s, it became a concern that exposure to the mineral fibers associated taconite ore processed in Silver Bay, Minnesota would cause asbestos-related disease including gastrointestinal cancer. At that time data gaps existed which have now been significantly reduced by further research. To further our understanding of the types of airborne fibers in Silver Bay we undertook a geological survey of their source the Peter Mitchell Pit, and found that there are no primary asbestos minerals at a detectable level. However we identified two non-asbestos types of fibrous minerals in very limited geological locales. Air sampling useful for risk assessment was done to determine the type, concentrations and size distribution of the population of airborne fibers around Silver Bay. Approximately 80% of the airborne fibers have elemental compositions consistent with cummingtonite-grunerite and the remaining 20% have elemental compositions in the tremolite-actinolite series. The mean airborne concentration of both fiber types is less than 0.00014 fibers per milliliter that is within the background level reported by the World Health Organization. We calculate the risk of asbestos-related mesothelioma and lung cancer using a variety of different pessimistic assumptions. (i) that all the non-asbestos fibers are as potent as asbestos fibers used in the EPA-IRIS listing for asbestos; with a calculated risk of asbestos-related cancer for environmental exposure at Silver Bay of 1 excess cancer in 28,500 lifetimes (or 35 excess cancers per 1,000,000 lifetimes) and secondly that taconite associated fibers are as potent as chrysotile the least potent form of asbestos. The calculated risk is less than 0.77 excess cancer case in 1,000,000 lifetimes. Finally, we briefly review the epidemiology studies of grunerite asbestos (amosite) focusing on the exposure conditions associated with increased risk of human mesothelioma. © 2008 Elsevier Inc. All rights reserved. Keywords: Risk; Fibers; Particles; Taconite; Asbestos; Exposures

Jan 1, 2007

By I. M. Arbuthnot

Over the last five years, a large number of small to medium sized carbon-in-pulp gold treatment plants have been built in Australia, most designed to treat between 250,000 -1,500,000 tpa of ore. In many cases, the primary requirement was to get a plant built and operating in a short period of time and at minimal capital cost, relating to the limited capital resources and tight cash flow positions of these relatively small mining companies. Since the inclusion of both pre-leach and tailings thickeners resulted in an obvious and significant capital cost, most plants were built without thickeners, without doing a detailed cost-benefit analysis on their inclusion, However, the increasing use of High Rate Thickener?s (HRT s) in the mineral processing industries resulted in a reassessment, in some cases, because of their considerably lower cost. This reassessment was triggered primarily by the need to conserve water in arid mining areas, where borefields were costly to install and water was limited. It has become apparent, though, since startup and operation of these installations, that the savings in cyanide consumption is also a very significant factor and can be used as a primary justification for the installation of a HRT in many cases.

Jan 1, 1991

By Ken Wangerud

The benefits of historic mining to this country have been many, but have come at a cost to the environment that has only begun to be understood over the past twenty years. While estimates vary, it is generally recognized that there are over 200,000 inactive and abandoned hardrock mines, with most of them located in the western U.S. Only a fraction of them are believed to be sources of metal releases with significant adverse environmental effects to the watersheds and receiving streams. State water-quality and natural resource management agencies have noted that hundreds of miles of streams are metal-impacted, and the aggregate effects of these sites within watersheds and drainage basins is poorly understood. Resources for the environmental assessment of abandoned mine land (AML) sites and watersheds have been and continue to be limited. Few hardrock mining states receive substantial reclamation funds under the (coal) Surface Mining Control and Reclamation Act. EPA Region VIII (EPA8) has an estimated 90,000 abandoned mining, milling and smelter sites, mainly in Colorado, Montana, South Dakota, Utah and Wyoming. An estimated 13,000 of the sites may have metal releases causing Clean Water Act and CERCLA non-compliance. Results of inventories by states and federal land managing agencies, indicate it is plausible that only 3,000-4,000 of these sites may be causing significant environmental degradation.

Jan 1, 1999