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By John L. Ellenberger

Virtually no two mines operate with the same geographic, geologic, and mining conditions. It follows chat problems vary with the conditions from mine to mine or often from one section to another in the same mine. Actual situations are described, and a technique of "stacking" maps to predict hazards is presented. Two case histories of the use of multiple overlays are de- scribed. The first deals with a property that was examined before the start of mining. The second is a property in which severe ground control problems were encountered and the relationship between the problem areas and known conditions were found to be related.

Jan 1, 1981

By M. Ahrens

Gearless mill drives (GMD) are a well established solution for grinding applications in the minerals and mining industries. The paper describes the functionality and technical features of such drive systems as well as the development and the progress of GMD systems over the years. With an increasing installed base and many drives operating for many years, there is an increasing need to modernize or revamp existing GMD installations. The first installations of GMD took place in the cement industry and have demonstrated that ringmotors can achieve a lifetime well above 40 years, if maintained properly. The life cycle time of many other components, especially electronic parts, is usually shorter. It is therefore necessary to replace aged or out-dated components early enough in a planned manner in order to reduce the risk of component failures and the related shutdown times. Modernization upgrades can range from minor software updates to a revamp of the cycloconverter. The paper describes typical examples of such upgrades and shows the most important aspects that need to be considered.

Jan 1, 2008

By Jon Hurt

INTRODUCTION The entire scope of new facilities for Lake Mead Intake No. 3 includes a sub-merged intake structure, a deep tunnel beneath Lake Mead, a tunnel access shaft, Intake Pumping Station No. 3, and connections to an existing intake and water treat-ment facility, as shown in Figure 1. In March 2008 Vegas Tunnel Constructors (VTC), a joint venture of Impregilo SpA and SA Healy were awarded a $447m Design-Build contract by SNWA for a section of this work (Contract 070F 01 C1), including the 185 m deep tunnel access shaft, the 4.7 km long, 6.1 m diameter tunnel and the submerged intake. Arup, supported by Brierley Associates, is the Design Engineer for VTC. The scope of the work is shown in Figure 2. This paper will describe the design and construction on this contract, with a focus on the access shaft which is the most complete section of the work. The shaft is being sunk using drill-and-blast methods with the finallining placed as excavation proceeds. The shaft passes through a major fault zone, and extensive pre-excavation grouting for water control is required for much of the depth of the shaft.

By Carl Pinches

Underground or surface mining is only the first stage in the ore mining process. Once the ore is mined, it is transported to the surface for further processing. Generally, this is done to extract the particular metal or other component of the ore that has commercial value in its purified form. In its raw state, there are typically between 4 and 7 g/t (0.12 and 0.2 oz/st) of valuable material from rock mined. Once on the surface, the ore is crushed and milled in order to obtain smaller rock particles and to expose the minerals that contain the desired metal or component. Mixing the milled ore with water, a process known as ?froth flotation,? can be employed. This technique consists of a series of tanks, or ?cells? through which the process liquid flows. To obtain the maximum recovery, the milling and flotation process will often be repeated a second time. An increase between 100 and 1,000 g/t (2.9 and 29 oz/st) of rock following this stage of the process is typical. Efficient recovery is key to maintaining a profitable mining operation. The measurement and control of the froth flotation process is vital.

Jan 1, 2010

By D. B. Spears

The sillimanite group includes the aluminosilicate minerals sillimanite, kyanite and and alusite, all of which have the same chemical composition (Al2SiO5). This discussion also includes the closely related mineral, mullite(about Al6Si3O15), which, although rare in nature, is produced artificially for industrial use. All of the minerals in this group have a low coefficient of thermal expansion and high corrosion resistance. This makes them desirable for refractory applications, especially in the steel and foundry industries. Other uses include electrical insulators, abrasives and household ceramic products. The minerals in the sillimanite group decompose with an irreversible expansion at temperatures between 1,300° C and 1,600° C (2,372° F and 2,912° F). Sillimanite and and alusite have relatively small expansion on decomposition (4 percent to 6 percent) and, therefore, can be used as aggregates in refractory products. Kyanite’s expansion on decomposition is large (18 percent). So it is sometimes used to balance shrinkage of other materials such as clays in refractory mixtures. For applications requiring high-temperature volume stability, mullite is more desirable. As an additive, mullite improves resistance to creep and corrosion, and imparts thermal and electrical insulating properties.

Jan 1, 2005

By Y. Nien Wang

The Devil?s Slide portion of Highway 1 between Pacifica and Montara is often closed due to the instability of the adjacent slopes. Following many years of public input and careful evaluation of alternatives, Devil?s Slide will be by-passed via two inland tunnels, providing a safe, dependable highway between Pacifica and Montara. For the twin tunnels, each 9m diameter tube will accommodate only one traffic lane. Each tunnel tube will accommodate a 3.6 meter roadway, 0.6 meter and 2.4 meter inside and outside shoulders respectively, and 1.2 meter walkways on each side. Cross passages will connect the bores at about 120 meter intervals and jet fans will provide tunnel ventilation. The twin tunnels are approximately 1,250 meter long and 9 meter wide. Excavation will progress from south to north using tunneling techniques that rely on inherent rock strength for support known as the New Austrian Tunneling Method (NATM). Both tunnels will be excavated at the same time, one tunnel face approximately 40 meters ahead of the other. Staggering the tunnels reduces the likelihood of damage from blasting in alternate tunnels. The work schedule is 24 hours a day, 7 days a week resulting in a 24-month timetable to break through to the north portal.

Jan 1, 2008

Current design guidelines for the surface catalysed oxidation of Fe(II) on Fe(OH)3 (Ochre) in passive mine water treatment systems are based largely on empirical data as the details of rates and mechanisms have not fully been revealed. Also the effects of elevated carbonate concentrations, typical of many UK minewaters, on the surface catalysed oxidation rate are unclear. In order to move away from empirical design and towards sound engineering that is based on geochemical and hydrological understanding it is necessary to quantify these reaction rates. In this study the effects of Fe(OH)3 and carbonate on the rate of Fe(II) oxidation by dissolved oxygen have been investigated with an aim to delineate the reaction mechanism. Experiments were conducted under well-controlled conditions. Preliminary results indicate that the surface catalysed reaction is an order of magnitude faster at pH ~6.4 with 200 mg/l Fe(OH)3 than the homogeneous rate and is dominated by an elevated rate of removal and oxidation of Fe(II) from the solution phase. It is also apparent that the oxidation rate of actual adsorbed Fe(II) is substantially retarded with respect to the homogeneous rate. Carbonates were not shown to affect the surface rate within the bounds of this preliminary study.

Jan 1, 2006

By William R. Yernberg

Santa Fe Pacific Gold, headquartered in Albuquerque, NM is expanding its operation at the Twin Creeks Mine in Nevada. The $250-million sulfide expansion project, including the Sage Mill, is under construction and is 80% complete. Also, additional mining equipment has been purchased to haul the sulfide ore to the mill. With the expansion, employment at Twin Creeks is expected to reach approximately 970 people by the end of 1996. Santa Fe Pacific Gold now owns and operates three gold mines in the United States and is involved in several other gold projects. The three currently operating mines are the Twin Creeks, Mesquite and Lone Tree mines. The Mesquite Mine is located in California’s Imperial Valley. Lone Tree is located 55 km (34 miles) southeast of Winnemucca, NV. The company’s total gold production from these operations is expected to be in the range of 26.3 to 26.6 t (845,000 to 855,000 oz) in 1996. This compares to a total production of about 124 kg (4,000 oz) for the company in 1989. Production costs range from $6.90to $7.25/g ($215 to $225/oz). At the end of 1995, the company reported proven and probable reserves of 556.7 t(17.9 million oz) of gold.

Jan 1, 1996

By S. E. Younis

The mining industry is currently looking to better understand, anticipate, and be able to mitigate business and operational risks in order to deliver the rewards of risk taking, and to minimize the frequency and impact of risk on the downside. Assessing risk works from the premise that the identification and management of existing risks can be very challenging, especially when threats are not easy to detect, the likelihood of occurrence is difficult to gauge, and/or the consequences are uncertain. Some approach this as a ?check the box? task, even though fire and safety incidents continue to occur and investigations often find the hazard analyses did not properly identify the cause or consequence. You cannot engineer protective designs and safeguards for causes and consequences that have not been identified appropriately. For the mining industry, risk management is an important tool for making critical decisions and, in some cases, meeting regulatory requirements. Providing high-quality documentation that meets both regulatory and corporate requirements is critical for maintaining safe, uninterrupted mining operations. Risk management is a five-part process: 1. Identify the hazards and their causes, 2. Determine the hazard consequences, 3. Calculate the frequency of occurrence, 4. Quantify the risk associated with the system, process, or procedure, and 5. Provide feasible solutions for the risks

Jan 1, 2012

By Shiou-Chuan Sun

Notwithstanding the fact that unsaturated fatty acids are used in preference to saturated acids for most flotation purposes, information regarding their collecting properties is sketchy. Keck, Eggleston, and Lowry1 reported in 1939 that the collecting power of fatty acids on hematite decreased in the order of oleic, lauric, myristic, palmitic, and caprylic acid. Keck and Jasberg2 described in the same year that "unsaturated oleic acid with 18 carbon atoms was a better collector than saturated stearic acid" for floating magnetite. Gaudin and Cole3 stated in 1953 that the double bonds of oleic and linoleic acid were not oxidized during the flotation of fluorite, whereas the double bonds of linolenic acid were measurably altered even after one single flotation step. In August, 1953, Hukki and Vartiainen4 concluded that the collecting power of palmitic, oleic, linoleic, and linolenic acids on ilmenite, magnetite, pyrite, and rutile increased with an increasing number of double bonds in the acid molecules. This was subsequently proved to be generally true for the flotation of mapganese5, phosphate6, and magnetite7. The above cited literature indicates that, prior to the present paper, only about ten minerals were tested with pure unsaturated fatty acids as collectors.

Jan 1, 1959

By Herry Poernomo, Agus Prasetya, Iga Trisnawati, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Panut Mulyono

We studied yttrium extraction from untreated zircon sand processing waste tailings. Xenotime mineral as the rare earth element source with an abundance of yttrium (REY) was detected in sufficient grade for extraction. As much as 9.03% yttrium exists in zircon tailings (analysed by X-ray fluorescence spectrometry). The presence of yttrium was confirmed by X-ray diffractometry in xenotime minerals, which are yttrium carriers (Y-PO4). The purpose of this research was to determine the effect of leaching conditions on yttrium recovery from zircon sand after alkaline fusion treatment. Alkaline fusion was chosen to decompose phosphate into hydroxide in the xenotimemineral,which will reduce further required hydrometallurgical processing.Alkaline fusionwas carried out for 3 h at 450 °C, with a ratio of sodium hydroxide to zircon tailings sand of ~ 1:1. The alkaline fusion product was leached with water, followed by hydrochloric acid treatment to leach the yttrium. Yttrium recovery reached 87% under optimum conditions (60 °C, 1MHCl, and solid-to-liquid ratio = 1/10 for 7.5 min). A suitable model for yttrium dissolution with hydrochloric acid was diffusion through a solid particle ash layer. The calculated activation energy (EA) for this model was 20.21 kJ/mol.

May 26, 2020

By Howard W. Adam

Mill length was the primary variable investigated in an autogenous pilot mill circuit. The 5-1/2' diameter mill had both pebble ports and 1/2" wide slotted grates. The plus 1/2" mill product was crushed in a cone crusher and returned to the mill feed along with the minus 1/2" plus 4 or 6 mesh fraction. Tests were run with a short mill, inside length of 26-3/8", or diameter-to-length ratio of 2.50 to 1. The same mill was then lengthened to 48-3/8", diameter-to-length ratio of 1.36 to 1. The effect of mill length on circuit product characteristics was studied. Results show that (1) circuit throughput or grinding rate is lower per foot of mill length in the longer mill, (2) the long mill product is finer than the short mill product, and (3) KWH per ton of circuit product is slightly higher with the longer mill; however, KWH per ton of minus 200 mesh material (finer fraction) produced is essentially the same in the long mill as the short mill, It is not known whether the relationships found for the pilot mill are valid for commercial size mills.

Jan 1, 1973

By John A. L. Campbell

Although there has been an increased interest in the electrokinetic properties of coal (1) research on the subject is still in an early stage of development (2,3,4,5,6,7) To the author's knowledge, no electrokinetic studies have been made on coal lithotypes - particularly anthracite lithotypes. This paper presents the results of an investigation of the double layer properties displayed at the anthracite/water interface (whole coal and lithotypes) as determined by streaming potential methods, It is hoped that this investigation and related future investigations will provide correlations from which the surface properties of any coal can be predicted and then related to surface dependent processes such as froth flotation and flocculation. Another aspect of this research, undertaken to determine the physical and chemical parameters necessary for anthracite lithotype differentiation, was previously published (8). The number of parameters involved, lithologic, organic and inorganic, and the wide divergence of these parameters within an individual coal limits the practical utilization of the results, however, the results are of value and of interest in guiding theoretical developments. Keeping the limitations in mind, the results are analyzed in terms of their application to froth flotation processes and are used to indicate the feasibility of making a lithotype separation by flotation.

Jan 1, 1969

By J. I. Schoenherr, G. Schubert, T. A. Baloun

The currently known and used plastics and rubber recycling or sorting processes cannot be applied efficiently and economically due to large amounts and different numbers of plastics types as well as of fine bulky materials (<4mm). These wastes are mostly given to land-fill sites. Thermal adhesion seems to be a great means to efficiently separate plastics mixes. Tests carried out at a special lab-scale testing unit (TaA1) confirm the effectiveness and feasibility of the separating mechanism. The thermal properties of the individual types of plastics differ from each other to a sufficient degree so that special products or product mixes of high material purity can be obtained according to the respective requirements. For this reason, plastics mixes such as PE and PP can be sorted with very good results. The separation efficiency is influenced only by different contact surfaces. The contact period can be adjusted to a short period of time so that sorting large amounts of fine dispersed plastics seems feasible. Sorting processes in feed streams were shown to be technologically effective when applying appropriate technologies. For the time being, the technological application of a thermal adhesion drum separator (TaTr1) is suitable. First tests on such a pilot-scale unit provided good separation results.

Jan 1, 2004

By W. J. Wolfe

Using a combined fire assay-atomic absorption method, gold determinations with a minimum detection limit of 5 ppb were made on 345 samples of Early Precambrian felsic plutonic rocks collected 2 2 from intrusions ranging in size from 4 km to 88 km and in composition from syenite to granodiorite. Gold levels in unmineralized stocks are consistently below the 5 ppb detection limit of the analytical method used. In contrast, analyses of samples from stocks containing gold mines within their borders and in nearby metavolcanic-metasedimentary host rocks show a strongly skewed trace element gold population with a substantial percentage of gold values exceeding 5 ppb and ranging as high as 320 ppb. The data indicate that (1) ore-stage hydrothermal metasomatism has produced widespread Au enrichment in Precambrian intrusions that host epigenetic vein-type gold deposits, and (2) geochemical Au analysis of samples collected from 30 to 50 randomly distributed sites can be used to estimate the gold exploration potential of stock-sized bodies and to outline internal patterns of Au variation which may be useful in directing exploration to particular contacts or portions of a stock. The results do not conclusively indicate unusually high Au content in primary unaltered igneous rocks.

Jan 1, 1975

By P. Raffinot, C. H. G. Bushell, S. Hodgson, E. F. Milner, H. J. Bosshardt, N. Draper, D. E. Pickett, Edwin T. McKnight, J. Prieto

Zinc ranks third and lead fourth in world nonferrous metal conumption. In 1972 the free world consumed 3,333,000 mt of refined lead and 4,422,000 mt of refined zinc. The lead tonnage was divided into the following end uses: storage batteries (42%), lead allows (7%), pigments and chemicals (11%), cable sheathing (9%), gasoline additives (13%), pipes and sheets (8%), and miscellaneous uses (10%). The corresponding distribution of zinc uses in 1972 was galvanizing (39%), die casting (26%), brass (15%), rolled zinc (8%), oxide excluding American Process zinc made directly from concentrate (6%), and other uses (6%). The pattern of usage of lead and zinc varies considerably from country to country. During 1972 in the USA 49% of refined lead was consumed in storage batteries, 19% in gasoline additives, and only 3% in cable sheathing, whereas in the United Kingdom 28% of the lead was consumed in batteries, 14% in cable sheathing, and 14% in gasoline additives. For zinc the major US uses were die casting (41%) and galvanizing (37%), with about 3% consumed as rolled zinc; corresponding usages in the same applications in France were 12, 28 and 28% and in Australia 12, 67, and 3%, respectively. The outstanding resistance of lead to corrosion, its density, and

Jan 1, 1985

By Nasri Munfah

Long Island Rail Road’s (LIRR) service to New York City is limited to Penn Station on the West Side of Manhattan, which is operating at its practical capacity for the commuter railroad. This situation imposes serious considerations for future growth and limits the destination of many Long Island commuters. The East Side Access Project will provide a connection of the LIRR to the landmark Grand Central Terminal (GCT)on the East Side of Manhattan. The construction of the connection will require significant tunneling and underground work utilizing a variety of construction techniques. In Queens, the connection will require five soft ground tunnels using pressurized face tunnel boring machine. In Manhattan, the connection will require a series of rock tunnels and caverns connecting to two deep large station caverns under GCT to accommodate eight tracks with four platforms in a stacked configuration. The caverns housing train rooms are connected to the lower level of GCT where a large concourse will be provided. With a budget of $4.3 Billion, The East Side Access Project is the largest transportation project ever undertaken in New York City. This paper provides an overview of the project, discusses its environmental and the engineering challenges, and provides an insight into the design development to date.

Jan 1, 2001

By W. A. Haley

Wheel loaders were first introduced shortly after World War II as small machines designed for handling loose materials in various industrial and processing applications. It was not until the early 1950?s, however, that machine size permitted widespread loading of loose or stockpiled material into on-highway type trucks. An ever increasing number of machines continue to be used for this purpose today. In fact, it is by far the major use for wheel loaders in mining and quarrying. Many of these loaders were working at mines or quarries handling in-process or finished material and some were doing shovel clean-up. It was quite natural then, when the primary pit loading shovel was down, to attempt to maintain some production by replacing it temporarily with the wheel loaders. Most of these attempts were not very successful, however, until the really large wheel loaders, 4- to 6-yd. size were introduced in the early 1960&apos;s. Since that time these machines have proven they can be productive and economical primary pit loading tools, a job that was once the exclusive domain of the power shovel. To be competitive with the shovel however, conditions must exist or be made to exist, that will be favorable for the wheel loader.

Jan 1, 1967

By P. Moyo, S. Dixon, R. Norcross

The separation and recovery of copper from cyanide solution has been investigated since the early 1900s. The precipitation of copper using sulfide ion was patented in 1911 by Williamson, published by Leaver & Woolf of the USBM in 1931 and Cyanamid in 1960s. The current practice of sulfide precipitation is used in various processes such as “SART" for cyanide regeneration and copper recovery. The precipitation of copper sulfide requires the pH of the clear solution to be in the range of 4-6. The precipitated copper sulfide can be sold to smelters. Alternatively, copper cyanide can be precipitated from clear solutions in the pH range of 2-3. However, selling copper cyanide is challenging because of its cyanide content. Past work has focused on the use of boiling sulfuric acid to convert copper cyanide to copper sulfate as published by Seracini in 1991. This paper describes a simple process to convert copper cyanide to copper oxide using sodium hydroxide at ambient temperatures. The cuprite can be sold to smelters or used as a feed to an electrowinning circuit to produce copper cathodes. The process provides an effective method to recover copper from cyanide solutions with a lower capital requirement.

Mar 2, 2022

By Thomas F. Joyce

N L Industries, Inc., MacIntyre Development produces ilmenite and magnetite concentrates from its own open pit operation at Tahawus in New York&apos;s Adirondack Mountain region. The ilmenite concentrate is used within the company for the production of titanium dioxide pigments and the magnetite concentrate is sold to heavy media processors. Current production is from South Extension mine, loading by by six-yard Marion electric shovels into 85 ton Lectra Haul trucks. Bench heights are 44&apos; and are drilled with a Robbins Rotary 9 7/8" diameter hole on 25&apos; spacing for a yearly production of 3.4 million total tons of rock. The ore deposit occurs in veins dipping on the average at 40 degrees to the west. The ore body, which is divided into three zones, outcrops at surface and continues to depths of 800&apos;. Zone 1 is a high grade band of thickness 150-200&apos; with an Fe/Tio2 ratio of 2. Below this band is Zone 2, a low grade band of thickness 50-100&apos; with an Fe/Tio2 ratio of 2 and beneath that seperated by a band of anorthosite is Zone 3, a high grade band of irregular thickness 50-450&apos; with an Fe/Tio2 ratio of 1.6.

Jan 1, 1973