Search Documents

Residential and commercial plumbers in the United States were introduced to Viega?s copper press technology in 1999. In short, the technology allows plumbers and installers to join copper pipe securely in four to seven seconds on pipe sizes of 1.2 to 10 cm (0.5 to 4 in.) by pressing the connections with specialized tools and fittings rather than through sodering or welding. The water- and air-tight technology, first introduced in Germany in 1989, includes three different sealing elements, a variety of materials and a selection of configurations. By eliminating the need to thread or solder pipe, connections and repairs can be made quickly and securely. Installations are also much quicker and as secure as traditional methods.

Jan 1, 2012

By W. A. Zingg

Impervious zones in copper waste heaps create a problem in contacting the rock with leaching solutions. These zones are normally associated with compacted layers .formed on the surface of each lift by dump truck traffic and by disintegration of the rock exposed to atmospheric conditions. These layers are usually only a few feet in depth--but, nevertheless, act as barriers to vertical flow causing the leach solution to perch in the heap, Consequently, much of the rock remains untouched and the leach solution breaks out the side of the heap instead of continuing downward to bedrock. One solution to this problem is breaking the hard pans with explosive charges. However, to use explosives means adopting new explosive materials and methods. To use this process successfully requires finding answers to operating conditions inherent to waste heaps. Foremost among these are: (1) type and size of casing that can be used because of limitations brought about by drilling problems, caving and, corrosive conditions; (2) perforating the casing at required levels; (3) an explosive capable of being pumped; (4) obtaining detonation of the, main charges through, the wail of the casing; (5) an explosive with the ability to propagate through the voids of the rubble and one which is not affected by water, acidic solutions, or back pressure conditions from hydrostatic heads; (6) to heave and rupture the compacted zones without chambering or recompressing the waste material.

Jan 1, 1970

By H. C. Juvkam-Wold

The design of an aquifer depressurization system is discussed. The system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15X of their potential values in the absence of wells

Jan 1, 1980

By Edwin B. Wilson

Electric power generation remains the greatest market for coal in the United States. In 1967, about 272 million tons of coal, amounting to over 51 percent of total coal consumption, were burned to satisfy this nation's hugh demand for power. The size of the utility market is currently five times that of 1941 and continues to grow with the demand for more and more energy. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F.

Jan 1, 1969

By Charles G. Zink

Anthracite is widely known as a domestic or space heating fuel. The prevailing market ratio of domestic to industrial consumption was about 80 to 20 up until 1950. Since then it has been shifting until now the ratio index is about 50/50, exclusive of overseas export. Despite a declining domestic space heating market, the demand for industrial anthracite remains good. However, as a result of stringent air pollution regulations, there is a renewed interest in this low sulphur coal which cannot smoke under any conditions. Anthracite serves other important industries such as power generating, metallurgical, cement, ceramic, chemical, water sewage and industrial wastes filtration. Anthracite is an excellent natural source of carbon and may be utilized in many processes.

Jan 1, 1966

By Fan Yang, Meigui Yi, Lan Xiang, Zhuoying Yang

This paper reported the calculation of the reaction heat in titanium-bearing blast furnace slag (abbreviated as TBFS)-H2SO4 system based on estimation of thermodynamic data of CaTiAl2O6 by mechanical mixture model. The thermodynamic analysis indicated that CaTiAl2O6 was more stable than the corresponding ternary oxides as CaO·TiO2, CaO·Al2O3, and Al2O3·TiO2. TBFS-H2SO4 system was highly exothermic since all of the reactions involved in the system were exothermic. For example, the increase of temperature from 25 to 200°C led to the increase of the release of the reaction heat in TBFS (100.0g)-H2SO4 system from 181.28 to 189.73kJ. Eighty-five to 90%of the reaction heat in TBFS-H2SO4 system was contributed by the reactions among CaTiAl2O6, CaTiO3, CaMgSi2O6, and H2SO4.

Feb 1, 2021

By M. L. Wouden

The Bureau of Mines investigated pegmatite and granite formations at Copper Mountain, Fremont County, Wyoming, for recovery of tantalum and niobium. Sampling of surface exposures identified about 1.27 mega tonne of pegmatite resource material ranging between 0.02 and 0.04% Ta20, and 0.007% Hb20,. Beneficiation studies were conducted involving coarse-grained and fine grained pegmatite samples. Over 80% recovery of the coarse-grained tantalite was achieved in a concentrate averaging over 45% combined tantalum-niobium oxide. Lower concentrate grades and recoveries resulted from the treatment of fine-grained pegmatite.

Jan 1, 1991

By Peter T. Chiang

A brief literature review on metal separations by ion exchange and solvent extraction of their thiocyanate complexes which are practiced in analytical chemistry as well as in industries was performed. Owing to the poor stability of free thiocyanic acid in acidic aqueous and organic media, technical and environmental problems which cause high thiocyanate consumptions often arise during the practice of the separation processes. This prompted the conducting of a second and more thorough literature review on the chemistry of thiocyanic acid. The objectives of this undertaking are to compile and interpret literature data on the physical properties and chemical reactions of thiocyanic acid, thus providing a clearer understanding of the causes of these problems and giving options as to how to minimize them. The best answer found for carrying out the separation processes is to keep the temperature, thiocyanic acid concentration and total acidity as low as practical.

Jan 1, 1984

By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By R. Cooper, K. De Wet, A. Janwong

"Horsehead Metal Products is a zinc refinery in Mooresboro NC treating crude Waelz Oxide (WOX) to produce Special High Grade Zinc by a hydrometallurgical process, comprising leaching, zinc solvent extraction/electrowinning (SX/EW), melting and casting and bleed treatment. Cadmium removal by zinc dust cementation plays an essential role in the bleed treatment circuit to prevent a build-up of cadmium in the circuit. Silica, although not present at significant levels in the WOX feed material (approximately 0.3%), had a significant impact on the efficiency of cadmium cementation with zinc dust, most likely due to the passivation of zinc dust particles with silica gel. Solid/liquid separation efficiency by filter press was also impacted. The silica levels were mapped throughout the circuit in an attempt to identify the source of the silica issues. Adjustments including using PLS as feed to cementation, pH control in WOX leaching and neutralization have been introduced to mitigate the issues created by silica gel in the circuit. INTRODUCTION Located in North Carolina, Horsehead Metal Products Inc. is a hydrometallurgical zinc refinery processing Waelz Oxide (WOX) to produce Special High Grade (SHG) zinc. The flowsheet, known as the Modified Zincex® process, consists of leaching, solvent extraction, electrowinning, melting and casting and bleed treatment as illustrated in Figure 1. Cadmium cementation, part of the bleed treatment process, provides an essential bleed of cadmium from the circuit, as metallic cement. The Cadmium cementation circuit consists of agitated cementation reactors, a zinc dust addition system, filter presses, agitated purification (releach) reactors and a cadmium concentrate filter press Silica can be found in several forms in acid leaching. The first form is fine silicate particles. The size of the particles can vary from one to twenty microns (1). Fine silicate particles can lead to the formation of crud in solvent extraction circuits (2, 3). At Mooresboro, crud has been observed in Depletion, which is part of the solvent extraction circuit. Silica content in the solution in this section is high. The second form of silica is monosilicic acid Si(OH)4, which begins to polymerize almost immediately upon being leached into solution. Monosilicic acid polymerizes to silica gel or a silica precipitate dependent primarily on supersaturation (5). Factors that influence the rate of polymerization include temperature, sulfuric acid concentration / pH, hydrofluoric acid concentration, seeding, and dissolved salts concentration such as zinc and aluminum in the solution (4, 5, 6). In sulfate systems, silica solubility is reported in the range of 150 to 450 ppm of SiO2 (3, 5, 7)."

Jan 1, 2016

The National Mining Hall of Fame and Museum will hold its Ninth Annual Induction Banquet Sept. 8, 1996, at the Las Vegas Hilton Hotel. Six mining greats, two of them living, will be enshrined at the event. They will join 126 other mining legends previously honored by the hall of fame. The keynote speaker will be William Perry Pendley, president and chief legal officer of Mountain States Legal Foundation in Denver, CO. Jeffrey Zelms, president and chief executive officer of The Doe Run Co., will be master of ceremonies. Richard Swayne, regional director USA for Boart Longyear Co. of Salt Lake City, UT, will introduce the speakers. Thomas Falkie, president of Berwind Natural Resources Corp. and chairman of the Mining Hall of Fame’s board of governors, will enshrine the inductees.

Jan 1, 1996

By S. B. Kim, J. Hong, K. Park, W. Kim, H. Kim, Y. Han, J. Choi

"For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50–200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.INTRODUCTION A great number of potential applications of lithium are being developed currently by the thermonuclear fusion power generation industry(1,2) as well as by the battery and fuel cell industry(3). Even though lithium is mainly consumed in the form of lithium metal and some lithium compounds, about 10% of total lithium production is consumed directly as mineral concentrates by the ceramic industry for the manufacture of special ceramics and mica based glass-ceramics(4). Granitic pegmatites normally contain feldspars, quartz, and mica in addition to lithium-bearing minerals such as spodumene (LiAl(SiO3)2), petalite (LiAlSi4O10), and lepidolite (KLi2Al(Al,Si)3O10(F,OH)2). The amount and grade of metallic minerals tend to gradually decrease and become lower, leading to the increase in the price of base metal or metallic compound(5). Accordingly, recent studies have been extensively devoted to developing the technique to improve the grade of metallic minerals from low grade metallic ores(6,7). Nevertheless, studies regarding the improvement of Li grade from lepidolite ores are very scarce. Lepidolite is a phyllosilicate mineral of the mica group and is often associated with other minerals such as calcite, muscovite, feldspar, and quartz, which need to be separated for lepidolite enrichment(8). Many studies have reported the flotation techniques for separating calcite, muscovite, feldspar, and/or quartz from various targeting minerals(9-11); however, there has been no attempt to investigate physico-chemical properties of lepidolite and its separation from such types of gangue minerals through flotation. Hence, in this study, for the first time, flotation has been carried out for the quaternary ammonium salts (stearyl trimethyl ammonium chloride (STAC, (CH3)3CH3(CH2)16NCl))-lepidolite system based on only the electrokinetic property of minerals that consist of lepidolite ores without adding any depressant to get an initial insight on its flotation behavior. The experimental variables that influence the lepidolite flotation such as amount of collectors, feed size and solution pH have been also examined."

Jan 1, 2015

By D. G. Feuerbacher

Maximizing production of oil from sandstone petroleum reservoirs is aided by use of non-damaging drilling and workover/completion fluids. Various tests, such as X-ray diffraction, scanning electron microsccpy, petrographic microscopy, porosity and permeability are conducted on core samples. Several fluids are selected, on the basis of these results, for return permeability tests. A report is then written giving the results of all tests, potential reservoir problems, and recommended practices for exploiting the reservoir.

Jan 1, 1983

By S. Bhamidipati

Abstract. Controlled flow is an aspect often desired in mine ventilation. This is normally obtained by using fans and regulators to achieve the required pressure balance in the system. Preference for a certain network layout of these control devices is influenced by technical as well as legal and economic factors. In this study, a model is developed based on an economic criterion by which an optimum layout of fans and regulators for a controlled flow system can be determined. The concept is analo¬gous to the critical path crashing. However, a linear programming package is used to demonstrate the solution procedure for a hypothetical venti¬lation network.

Jan 1, 1983

By John Turner, David Carey

The Robbins Mobile Miner demonstrates the successful combination of hard rock excavation technology and the latest electronic control technology. The mobile miner, a partial face hard rock tunneling machine, features a fully integrated control system relying on a Programmable Logic Controller (PLC). This PLC controls all functions: tramming, steering, boom swing, cutting depth, conveyor operation, air scrubbers, hopper loading and unloading, etc. The machine is fully instrumented allowing the PLC to monitor the results of all commands on a continuous basis, to record data, to evaluate developing problems, or to shut the machine down if necessary. The paper describes the development of the Robbins - Pasminco automated mobile miner and early testing at Pasminco Mining's Broken Hill Southern Operations, New South Wales, Australia.

Jan 1, 1993

By Paul H. Johnson

A new system for leaching many types of ores has recently been developed on a commercial basis by J and J Research and Development, Inc. of Hanover, New Mexico. This revolutionary new leaching system consists principally of three new leaching reactors; viz, (1) a large, air-agitates, column-like reactor for leaching crushed ores that is constructed in an underground environment and has the inherent ability to do a very efficient job of leaching, (2) a vat-like, air-agitated vessel for leaching an rinsing finely ground ores and , (3) an air-agitated copper precipitation column that is built underground and utilizes an inexpensive dense or heavy scrap iron as a copper precipitant. Each of these new reactors have been used in a large leaching plant near Hanover, New Mexico.

Jan 1, 1973

By Michael McNinch, LaTasha R. Swanson, Jennica L. Bellanca, Justin Helton

As manufacturers and mine operators develop and implement proximity detection systems (PDSs), they need to be mindful of the systems’ compatibility with mineworkers’ tasks, and possible unintended consequences. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) interviewed mineworkers at mine sites that currently use or previously have used PDSs on mobile equipment, including shuttle cars, battery haulers and scoops. Mineworkers reported that mobile PDSs affect loading, tramming, section setup, maintenance and general work on the section. Mineworkers discussed the operational effects and increased burden, exposure and risk. Mineworkers also suggested that improved system task compatibility, training, logistics and PDS performance might help address these issues. Manufacturers and mine operators implementing this or similar technologies may also consider mitigating task incompatibilities up front, performing additional site-specific usability testing and restricting the use cases of the system to improve performance.

By Jon Pocock, Ashma Singh

The traditional approach for the beneficiation of South African siliceous sedimentary phosphate ores has been reverse cationic flotation. The robustness of this approach, however, has been a concern due to its sensitivity to parameters such as slimes content, headgrade ( P2O5 and SiO2 content), reagent dosages and conditioning times. The phosphate mineralisation for the ore body under investigation is predominantly carbonate fluorapatite composed of mainly quartz and apatite and minor amounts of chlorite, ilmenite and carbonates. Beneficiation of low grade sedimentary ores containing calcareous impurities, such as calcite and/or dolomite in addition to siliceous gangue, is required to meet the increasing demand; therefore, much research has been carried out to find an alternative technique to beneficiate this material. This paper investigates traditional flotation approaches versus the currently adopted ‘Crago Process’. Comparative results are presented in terms of upgrade potential for the production of concentrate rock for downstream applications. The novelty of the ‘Crago Process’ lies in its double stage approach, i.e. direct fatty acid flotation followed by reverse cationic amine flotation. The Crago process was able to achieve higher upgrades reporting at 32.1% P2O5 compared to conventional cationic flotation only achieving grades of 18.5% P2O5. Furthermore, the recovery gain was 3%.

May 13, 2023

By S. C. Suboleski

In a high risk venture such as mining where capital is committed and contracts are signed on the minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control and, due to the wide range of mining conditions that may be experienced, little effort has been made to develop objective methods for measuring their effects on mine out- put. The aim of this paper is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. psing empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions

Jan 1, 1980

By G. A. Hayes

The range of gold ores tested at AMMTEC LTD over several years has resulted in the requirement to analyse for the mode of occurrence of gold in order to assist selection of ore processing options. The aim of this paper is to describe the laboratory testwork and analytical procedures which have been of benefit in detail­ing the mode of occurrence and mineral associations of gold and hence being of value in developing an optimised ore processing route. The range of ore and mineral assemblages described include relatively simple pyrite and free milling ores, more complex pyrite plus arsenopyrite gold ores and the quite com­plex associations of gold in copper bearing ores or with car­bonaceous mixed sulphide ore assemblages. The aim of this paper is to describe the laboratory testwork and analytical procedures which have been of benefit in detail­ing the mode of occurrence and mineral associations of gold and hence being of value in developing an optimised ore processing route. The range of ore and mineral assemblages described include relatively simple pyrite and free milling ores, more complex pyrite plus arsenopyrite gold ores and the quite com­plex associations of gold in copper bearing ores or with car­bonaceous mixed sulphide ore assemblages.

Jan 1, 1996