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The transfer of Langmuir-Blodgett (LB) monolayers of collector molecules to the surface of mineral crystals is an excellent method for the study of collector adsorption phenomena and is of particular significance in the understanding and development of improved flotation separations. The fatty acid/fluorite and amine/sylvite potation systems were investigated by the Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS) examination of transferred LB monolayers of collector molecules at the surfaces of the mineral crystals. The [ir]-A isotherm study of fatty acid and amine, typical anionic and cationic collectors, showed the different packing trends dependent upon the pH and/or type of subphase. This result clearly reflects the effect of pH on compound formation and dissociation of the collector molecules. Identification of the collector adsorption state and confirmation of the validity of the FT-IR/IRS adsorption density equation were included in this research effort. This allowed for a detailed discussion of collector adsorption phenomena. As a result of these experiments, it is possible to relate the hydrophobic character of a surface to the nature of the adsorbed collector structure and thus describe flotation behavior in greater detail. For example, it appears that in the case of oleate/ fluorite the equivalent of an LB monolayer can form spontaneously during adsorption from solution, and this structure is known as a self-assembled monolayer (SAM). Such a state is significantly more hydrophobic than the oleate structure which forms on the calcite surface at an equivalent adsorption density.

Jan 1, 1996

By V. B. Achanti

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the: fragmentation process were found to be: bit spacing, bit geometry, depth of cut, and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Three bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 90°. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Respirable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Jan 1, 1997

By J. A. Lombardi

Innovative hard rock narrow-vein, longwall, and stope leach mining systems concepts are described and evaluated economically. The principal tool proposed for use in these systems for both mine development and production is the U.S. Bureau of Mines radial-axial splitter. The mining systems concepts are prefeasibility level costed and projected to be cost competitive for steeply dipping veins, 0.6-1.2 m wide, for horizontal tabular ores 2 m -5 m thick, and for leachable ores with greater than a 1.7:1 stripping ratio. In all of the systems the orebody, less swell, is retained underground for use as backfill.

Jan 1, 1994

By Raj K. Rajamani, Samira Rashidi

Wear is an extremely important topic when considering high-pressure grinding rolls (HPGR) for any new application. Given the inevitable variations in ore properties throughout a mine’s life, it is difficult to predict the effect of material and operating conditions on the wear parts: specifically, the HPGR rolls. However, the possibility of continuous scanning of rolls provides ample information to review the wear pattern and ways to optimize it. In this regard, as part of a broader investigation, the feasibility of in-line scanning of HPGR rolls in a laboratory-scale HPGR is studied and presented. The choice of scanners and methods adopted to achieve high-level accuracy for determining wear is discussed in this paper, and the inherent variability affecting the measurements is evaluated. 

By Nathaniel Arbiter

The increasing size of flotation cells as the use of flotation has increased is traced from the first United States application of the process in Montana in 1911 through the following eight decades, using data from the Taggart handbooks (1927) and (1945), from the SME Handbook (1984), and from recent manufacturers' catalogues and other sources for the 1980s and 1990s. With the earliest mechanical cells less than 1 m3 (359) in volume and the largest now available at 200 m3 (7,000ft3), three requirements are necessary: 1) demonstration of advantages in replacing smaller volume by larger volume cells; 2) estimating power requirements, impeller dimensions, and operating rpm by correlation equations; 3) considering effects of using larger cells, in necessarily much shorter rows, on process kinetics. The resulting seven tables that address these problems are presented, and their implications discussed.

Jan 1, 1999

The Colorado Joint Review Process (JRP), a bold step to expedite energy and mineral projects, is off and running. Blazing the trail is Amax Inc., which serve as guinea pig in JRP's development and is now test-flying the process at its Mt. Emmons molybdenum property in Gunnison County, CO. Although JRP is still in its infancy, the new permitting review process has drawn enthusiastic applause from across the resource spectrum: William K. Reilly, president of the Conservation Foundation, said JRP is "one of the most interesting projects I've seen" and called on environmentalists to monitor its progress "because it appears worthwhile." Stan Dempsey, vice president of Amax Inc., noted that of all the locales in which Amax operates, Colorado is "the only place where the complicated mine permitting scheme appears to work"-an achievement he attributes to JRP. Lynda Lee Brothers, the federal Energy Department's assistant deputy secretary of environment, reported that an extensive DOE search has not turned up "another single mechanism in all of government and private industry as good as JRP as a model for the proposed federal Energy Mobilization Board."

Jan 7, 1980

By George L. Wilhelm

Many factors, some of which are not easily defined or described, must be considered in the design of a hydraulic backfill system. After participating in the design of several plants, I have a conviction that future refinements in sandfill systems must come in large part, from the merging of good design ideas and information from existing operating plants. It is important then, that we document and publish information on existing plant designs and their operating characteristics. This information will then be available for use by our successors and later innovators in hydraulic fill placement. The Mayflower hydraulic sandfill system is similar to other plants. The intent of this paper is to describe only this system's unique design and operating characteristics. I will not describe in any detail, the familiar elements of the system. I will document some of the observed hydraulic characteristics of the system, elaborate on some of the design situations that had to be solved, and will discuss operating factors that are not generally described in our technical literature.

Jan 1, 1968

By Brian Burdett, Terry I. Mudder, Robert T. Richins, James A. Stevenson, Michael M. Botz, Alan L. Wilder

The first Cyanisorb process was constructed in 1991 at the Golden Cross Mine in Waihi, New Zealand to recover cyanide from CIL tailings. The Golden Cross operation consists of an open-pit and underground gold mine with a conventional crushing, grinding and CIL circuit with Merrill Crowe zinc precipitation for gold recovery. Prior to disposal in the tailings pond, slurry tailings are stripped of cyanide at a pH of approxi­mately 7.5 using the Cyanisorb process. Mill throughput is approximately 2,500 tons per day (TPD), and CIL slurry tailings average 37% solids with a specific gravity of 1.27. CIL tailings WAD cyanide average 150 mg/L. The Cyanisorb process recovers approximately 85% of tailings WAD cyanide, produc­ing a slurry effluent with approximately 20 mg/L WAD cyanide. A second Cyanisorb process was commissioned at the NERCO DeLamar silver mine in southwest Idaho in May, 1992. The ore milling and silver recovery operation consists of crushing, grinding, a CIP circuit and Merrill Crowe zinc precipi­tation for silver recovery. Cyanide recovery is from clarified tailings with WAD cyanide ranging from 3 50 mg/L to 600 mg/L, producing an effluent with less than 30 mg/L to 60 mg/L WAD cyanide. Due to the presence of zinc-cyanide complexes in mill tailings resulting from the Merrill Crowe process, cyanide is stripped at a pH of approximately 5.5.

Jan 1, 1995

During the past 20 years, FKC-Lake Shore, located in southern Indiana, has been working with Contitech, the German conveyor company, to push vertical conveyor technology to new depths and open up additional opportunities for underground mine owners. Historically, the underground mining industry has largely been unable to realize the benefits of these efficient systems due to the design limitations in maximum depth and capacity. Until recently, only relatively shallow depth mines with low production rates have been a ?t for a vertical conveyor system. This, however, is changing with technical advancements in the Pocketlift system. With each milestone, a new vertical conveyor record is set for depth and capacity. For instance, in 2002, FKC-Lake Shore set one such record with the installation of a Pocketlift system at a mine in the Illinois coal basin with a lift height of 273 m (896 ft) and a production rate of 1.8 kt/h (2,000 stph). Although it was unthinkable at that time, today?s vertical conveyors are capable of reaching lift heights up to 700 m (2,300 ft) with an average production rate of 450 t/h (500 stph). These new lift heights and production rates are opening the technology to more potential mine owners and shifting the way people look at moving material in the future.

By Andrew J. Petruska, Austin F. Oltmanns

The paper proposes a capacitive load cell for detecting changes in material and tool wear conditions for conical picks used in underground mining. The current process is dangerous and subjective, relying on human operators near the cutting interface. The new sensor aims to improve worker safety by allowing operators to perform their functions from a greater distance.

Aug 1, 2023

By J. D. Goodrich

Success of The Carter Mining Company's safety program can be primarily attributed to "total immersion" of all operating and staff personnel in program design and implementation. Currently, the Company operates two surface coal mines in Campbell County, Wyoming. Total employment is about 440 and current annual production is about 15 million tons. The safety program has evolved from one which was administered primarily by staff personnel (the Safety Department) to one which requires active participation by line management and operating personnel. Lost time accident frequencies have declined from a high of 1.86 per 200K hours worked in 1978 to zero in 1982. Reportable accident frequencies have declined from slightly over 5 to slightly over 2 during the same period. Analysis of program results indicates that the most important achievement by the company has been to gain strong commitment to safe operation by all employees. It is important that program format and content be frequently changed and modified so that: 1) The requirement for safe job performance is communicated well and often, 2) The safe job performance message is trans- mitted in new and interesting ways, and 3) Operating personnel participate in design and implementation of the program.

Jan 1, 1983

By T. Bednarski, T. McCallum

"Physical impurity transfer in solvent extraction (SX) has a significant impact on operating costs, electrowinning (EW) performance, and cathode quality. Some operations use a wash stage to limit impurity transfer by diluting the entrained pregnant leach solution (PLS) to prevent direct transfer to EW. Wash stage operating conditions vary impacting impurity transfer. A number of factors impact dilution efficiency including mixer continuity, wash aqueous acidity, and organic quality. The impact of these variables on dilution efficiency was studied and compared to current industry practice. INTRODUCTION With the exception of iron, impurity transfer in copper SX is due to PLS carryover in the loaded organic via aqueous entrainment and crud movement. The quantity of impurity transfer is influenced by many variables including operating set points, organic quality, and settler housekeeping. Crud management and treatment is a common practice aimed at minimizing transfer of impurities to EW. Crud is a complex solid-stabilized emulsion of aqueous and organic[9]. As such, it contains a large aqueous component and the associated impurities (from the PLS). A common practice is to remove interfacial crud to prevent movement. Additionally, mixer continuity can be altered to enable compaction and improve the efficiency of interfacial pumping[10]. Understanding the factors impacting aqueous entrainment and optimizing the available controls should be a key focus for any operation. Aqueous entrainment in the loaded organic can be impacted by: • Mixer continuity • Mixer organic/aqueous (O/A) ratio • Mixer speed and impeller type • Organic and aqueous depths • Specific settler flow • Use of settler internals (picket fences, coalescing packs) • Organic quality • Design and operation of loaded organic tanks Conventional thought is to run the E1 mixer in aqueous continuity to reduce aqueous entrainment. Generally, O/A ratios close to 1:1 result in improved metallurgical and physical performance. Mixer speeds should be chosen to achieve acceptable stage efficiencies while minimizing over-mixing. Organic depths can be increased in the E1 stage to increase retention time and minimize aqueous entrainment. Settler internals can also be used, but require maintenance to maintain effectiveness. The quality of the plant organic inventory will impact physical performance. Poor organic quality can lead to higher phase disengagement times increasing impurity transfer to the electrolyte. Additionally, the design and operation of the loaded organic tank can impact impurity transfer[8]. Despite the variables that can be used to reduce aqueous entrainment and crud movement, impurity transfer is still an issue in some operations. For these operations with high PLS impurity concentrations, a wash stage may be beneficial to manage impurity transfer. Understanding factors impacting wash stage performance is important to optimize performance and limit impurity transfer."

Jan 1, 2016

A one-day seminar designed to help quarry and mining managers make their operations more productive, more efficient and less expensive was held in Harris- burg PA. "Rock-Solid Productivity" was sponsored by Pittsburgh Power & Light (PP&L). The seminar, one of a series sponsored by PP&L in 1997, proved to be well-organized and provided valuable information to the many quarry and mining professionals who attended. The information presented included a comparison of on-site diesel power vs. electric power, discussions of equipment improvements and topics on environmental management.

Jan 1, 1998

By LeEtta M. Shaffner, John R. Marks

The Homestake Gold Mine in Lead, South Dakota, commenced operations in 1876. As is the case with old, deep, continuously developing mines, a ventilation improvement is periodically required to maintain acceptable underground environmental conditions. Recent historical improvements at Homestake include a 5.2m diameter air shaft driven in the 1960's and a 2.1 MWR (580 ton) chilled water plant installed in 1978. By 1983, it became apparent that yet another ventilation upgrade would be needed to keep pace with accelerated development in the deepest mining sections. A study was therefore undertaken to project ventilation requirements for the next ten years and to select the method(s) most suitable to meet those requirements. The study called for a two-phase approach in which air flow and air conditioning were carefully balanced. Phase I, the installation of a new 2240 kW surface fan and several underground circuit changes, was completed in 1986. This paper describes Phase 11: the planning, design, installation and initial performance of the air-conditioning portion of the upgrade.

Jan 1, 1989

By D. E. Walsh, J. T. Hollow, H. K. Lin, J. L. Oleson

At the Fort Knox Mine, Fairbanks, Alaska, carbon fines are generated during stripping, acid washing and kiln regeneration operations. Because of their gold value, carbon fines are collected by a filter press. Samples of the carbon fines show that they consist of 20% to 30% carbon, 70% to 80% grit and 0.17 to 0.68 g/kg (5.0-19.9 oz/st) gold. About 80% of the gold values in the carbon fines used in this study are in the form of recrystallized free gold grains, with the balance being the adsorbed gold on the carbon. High recoveries of gold and carbon were obtained from the fines in laboratory tests using froth flotation, with a high rejection of the grit. More than 95% of gold and 90% of carbon can be recovered by three stages of gold flotation followed by two stages of carbon flotation. Key words: Gold recovery, Activated carbon, Flotation

Jan 1, 2003

By Jay S. Silhanek, Vernon E. Andrews

[Introduction] Section 122 of the Clean Air Act Amendments of 1977, Public Law 9595, directed the Administrator of the Environmental Protection Agency, to review all relevant information and determine whether emissions of radioactive pollutants into ambient air will cause or contribute to air pollution which may reasonably be anticipated to endanger public health. In August 1979, EPA published a preliminary report on assessments of public health impact resulting from emissions of radionuclides into air from a broad spectrum of major source categories (1). A section of this document presented a theoretical analysis of the radioactive airborne emissions from several non-uranium mines including iron, copper, zinc, clay, limestone, fluorspar, and phosphate. Since 1978 EPA's Las Vegas Laboratory has been gathering field data on actual radionuclide emissions from these mines to support the earlier theoretical analysis. The purpose of this paper is to present the results of those field measurements in comparison with the assumed values for the theoretical analysis. Data were presented in EPA's preliminary report on both gaseous radon-222 and particulate uranium-238 emissions from non-uranium mines. Most of the emissions data were rough estimates based upon the uranium content of the ore. Preliminary data from a few field studies were also used. Although both the theoretical and field studies by EPA were concerned with radon-222 and radioactive particulate emissions, this paper will concentrate only on the radon effluents. Radon from mines seems to have the greatest potential for possible health effects due to radiation. Data on particulate emissions are presented in other technical reports (2-5). [Theoretical Study] The theoretical emission data are presented in Table I. The estimates for the iron, zinc, and clay mines are based upon preliminary measurements taken by the Las Vegas laboratory. The estimates for the other mines were made assuming that 20% of the total radon-222 in the ore was released during the mining process and the radon release rate from the exposed ore surface was a factor of two greater than that resulting from mining. [ ] Dose assessments for radon from these mines were carried out using model facilities located on generic sites (1). The AIRDOS-II computer code (for estimating dispersion of airborne pollutants) with some minor modifications was used to determine working level exposures to a maximally exposed individual and a regional population. A conversion factor for risk/WL-year(O.021 fatal cancers/person-WL-y) was developed primarily from information on uranium miner exposures (6). This computer code and conversion factor were then applied to the assumed emission rate of radon-222 from each type of mine to develop estimates of working levels, lifetime risks and number of fatal cancers. A summary of this data is presented in table II. [ ] The highest estimated number of cancer deaths per year of operation is 0.05 cancer deaths or 1.0 death due to radon during the 24 year life of a phosphorous mine. For comparison, EPA estimates that underground uranium mines would cause .03 cancer deaths per year of operation in a regional population(1). [Field Study] As a followup to the theoretical study, EPA's Las Vegas laboratory began making measurements in 1978 of actual emissions of radon-222 and radioactive particulates from mine vents at several facilities for each of the industries listed in Table I and II. They were intended to verify general information and radon emissions from EPA's theoretical estimates.

Jan 1, 1981

By M. Misra

The interaction of xanthate with SO2 in the flotation of sphalerite and chalcopy.ite is discussed. 'The SO depression of sphaledte is due to the decomposition reaction of xanthate by SO2 The decomposition reaction is dependent on the cole ratios of xanthate/SO2, oxygen concentration and pH. Xanthate adsorbs at a faster rate by chalcopyrite than sphalerite. The faster rate of xanthate adsorption by chalcopyrite and the specific action of S02 on the surface of chalcopy.ite facilitate the selective separation of chalcopyrite from sphaledte.

Jan 1, 1989

By C. RAMADINI, F. NURJAMAN, A. SHOFI, B. SUHARNO

Nickel demand is increasing along with the rising need for stainless steel and other alloy steel/iron. The small addition of nickel in such materials can improve impact strength, ductility and corrosion resistance. Nickel is generally obtained from nickel sulfide ores (nickel associated with sulfur) and nickel laterite ores (nickel associated with iron and magnesium silicate). Almost 60 percent of nickel is now produced from sulfide ores, despite its existence in sulfide ores being less than in laterite ores. However, the depletion of sulfide ore reserves makes the mastery of nickel laterite ore processing of important and immediate concern. Selective reduction followed by magnetic separation has been in development in lateritic nickel ore processing to overcome the issues of high energy consumption and pollution associated with conventional pyrometallurgy methods such as blast furnace and rotary kiln electric arc furnace (RKEF).

By R. W. Smith, K. A. Altman

The use of activated alumina for the removal of selenium from heap leach detoxification solutions was studied at a laboratory scale. Three different aluminas were studied, one unmodified and two chemically modified to function better in a basic pH range. The best performer, Discovery Chemicals DD-6, readily accumulated selenium oxyanions. Furthermore, it could be stripped of selenium and several metals by a mild caustic solution (pH 11.5 – 12.0) and regenerated for further use. Tests using - 600 µm, + 300 µm (28 x 48 mesh) material indicated that 96 % could be removed from solution and using – 1.18mm, + 600 µm (14 x 28 mesh) material 91 % could be removed. However, soluble silica can accumulate on the activated alumina and subsequently interfere with its regeneration and should be removed from the detox solution prior to use of the adsorbent.

Jan 1, 2003

By John C. Draper

[Duquesne Light Company's three power plants in western Pennsylvania are now receiving high BTU clean coal from a new coal preparation plant. When burning coal from this plant, particulate emissions are greatly reduced and the sulfur content of stack ace descend. The cleaner coal also leads to more effecting overall operating of the power plants because of less bulk handling of fuel and ash. Environmental improvement is an important benefit of the cleaner, more complete combustion.]

Jan 1, 1976