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By E. A. Twichell

An entirely new concept in the effective utilization of magnetic, energy has resulted in a major break-through in the design of magnetic separation equipment. One of the first applications of this concept has resulted in the development of a Permanent Magnetic Wet Drum Separator with strength .and operating characteristics equal to Electro Wet Drum Separators. Prior to this development when strength and adjustability were required, electro wet drums were specified even with all their drawbacks. The electros, by nature, are subject to coil failure or burnout, over-heating and loss of strength, high power consumption and generally high maintenance. Now the high strength and the adjustability, formerly the exclusive property of electros, has been engineered into permanent wet drum separators. These units combine maximum field strength in the separation zone with strength adjustment to suit changing conditions. Adjustment can be effected while the drum is in operation without stopping either the feed or the drum.

Jan 1, 1967

By X. Li, J. C. Stankus, J. Ma, H. Chen

Accurate evaluation of stress and geological conditions is critical to ground control design in underground openings. For a slope entry, the problem is more difficult, because a slope will transverse through many types of strata. Over the last few years, Keystone Mining Services LLC, an affiliate company of the Jennmar Corporation, has developed a new methodology designated the “Stress, geologic and support design system (SGS).” The method analyzes the stress, geology and support design for a mine slope. The method has been successfully applied in various new slopes across the United States, and ground control plans developed using SGS methodology has helped coal companies successfully pass review and/or hearings by state and federal regulatory agencies. With a case application in the U.S. Midwest, this paper details and demonstrates the main concepts of the methodology, including (1) analysis of stress and geology and identification of strong, fair and weak zones along the slope; (2) primary and supplemental support design; (3) long-term support design in the form of steel square sets or arches and (4) validation of the support design utilizing advanced finite element computer modeling.

Jan 1, 2011

By J. R. Arnold

The problem of recovering gold from a cyanide solution has been plaguing metallurgists since the cyanidation process was discovered in Glasgow, Scotland.1 The "perfect" method has never been found and this paper will not purport to fill that gap. But we, at Gold Fields, feel that we have developed a workable, cheap and efficient method of producing a refinery - ready product that has several distinct advantages over conventional electroplating techniques. The Gold Fields replating system is presently being used at their Ortiz and Mesquite operations. In short, the system electroplates the gold out on stainless steel wool, instead of mild steel wool as is usually done, then replates the gold by reversing the current onto stainless steel plates. By doing this the steel wool can be reused many times, the gold can be scraped off the plates cleanly and quickly, the operating costs are reduced and the slag production is greatly reduced.

Jan 1, 1986

By G. P. Larson

We define a specialized mineral market as follows: Specialized Markets are markets where a low volume of a given mineral is used to convey a large benefit to a specific product. Sales of these value added minerals to small markets generally require a different marketing approach compared to bulk or commodity markets for traditional minerals. Specialized and commodity markets are differentiated by several characteristics as listed in Table 1.

Jan 1, 1990

By Y. Yu

Florida phosphates ore typically processed by reverse flotation with an intermediate acid-scrubbing step. A single-reagent flotation process, using fatty acids or amines as the collector, would eliminate the intermediate scrubbing step plus an additional flotation step. This would not only simplify the process flowsheet but would also result in reduced reagent costs. The potential of single-reagent flotation of Florida phosphates using fatty acids as the collector is examined in this study. Introduction The beneficiation scheme now used for Florida phosphates involves the following three steps (Smith, 1976: Lawyer et al.. 1978, 1984: Moudgil et al, 1976, 1979, 1986, 1987): •rougher flotation of fluorapatitc particles using a fatty acid-fuel oil mixture as the collector. •scrubbing of fatty acid, and •cleaner flotation of silica particles using amine collector. Several attempts have been made to simplify the process flowsheet by floating either apatite or silica (not both, as is the current practice). However, single-reagent flotation schemes have had limitations in meting the concentrate-grade requirements of the phosphoric acid plants. In this study, an attempt was made to use a minimal amount of the fatty acid-fuel oil collector to obtain an acceptable grade (rougher) concentrate. Invariably, the recovery in such cases is expected to be lower than in the conventional rougher-flotation step. Therefore, scavenger flotation of tailings with additional fatty-acid collector was conducted to improve the phosphate recoveries.

Jan 1, 1997

By Ulrich Maidl, Gustavo Aguiar, Argemiro Ferreira, Marco A. Peixoto Silva, Marc Comulada

"Metro Line 5 in Sao Paulo is being constructed. This lot extends for 4,940 m with twin EPB shield tunnels under a dense and busy urban area, with an excavation diameter of 6.9 m. The tunnels run predominantly in the tertiary soils of Sao Paulo where extensive experience exists from previous EPB shield tunnel projects. However, new experience is being gained in Sao Paulo in shield tunnelling through Saprolite, the weathered product of the underlying Gneiss crystalline basement, through the resulting residual soils and in rock-soil mixed face conditions. Furthermore, experiences in difficult mixed face soil conditions with overconsolidated clay at the face in combination with loose sands at the crown under the groundwater table will be presented. Additionally, the design, operational and controlling approach followed for the shield drive at particular critical cross-sections where the shields were driven close or under buildings. INTRODUCTION Within the framework of Sao Paulo´s metro network expansion, the excavation of the shield tunnels for Metro Sao Paulo Line 5 is currently taking place. The present paper deals with the description of the most relevant features from the construction of the Line 5 – Lot 3 tunnels. The paper presents how particular challenges were dealt maximising potential of EPB shield tunnelling technology. Challenges were posed not only by the difficult boundary conditions of urban shield tunnelling, such as shield drive under buildings, but also by complex geotechnical situations. PROJECT DESCRIPTION The great urban area of São Paulo is one of the biggest cities in the world, with around 20 Million people living in the city and in the suburb area. The city faces great mobility problems and in the last years the government has been investing great amounts on the megacity´s metro expansion. The Line 5 Extension plays an important role to connect the south area to the central area of the city, with a whole extension of 11 kilometres, including 11 new stations. It is estimated that this line will transport almost 900.000 passengers/day. The first stretch of the expansion, Lot 3, consists of two single tunnels, almost 5 kilometres long each, crossing 4 stations. Figure 1 shows details of the Line 5 Expansion."

Jan 1, 2016

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals dore' from ores, principally silver bearing with associated gold co-products. In late 1995 a new orebody was commissioned, the Stone Cabin orebody, and the site began a phased shift from silver dominance to gold dominance in terms of precious metals revenue. The Knelson Concentrator was selected to remove gold from a portion of the cyclone underflow stream in the grinding circuit. This paper describes the development of the flow sheet, specific mineralogical impacts on Knelson product and downstream materials, and impacts on mine/mill grade reconciliation.

Jan 1, 1997

By James O. Mawyer

Fuel is a major .cost for power generating utilities. Virginia Power is completing one of the nation's largest coal reconversion programs. As a result, 10 million tons of coal will now be used at six generating stations. Four of these stations are located on naviagable waterways. They consume over half of Virginia Power's coal. Historically, railroads have exclusively served these plants. In an effort to substantially reduce fuel cost, Virginia Power has reexamined transportation logistics and is proceeding with barge delivery. A phased approach was used by Virginia Power for the transportation program. Plant requirements were first identified. Coal sourcing issues were then examined. The concept of intermodal transportation was investigated. The bottom line cost savings was used as the criteria for continuing the project. The results thus far have been gratifying. Virginia Power has begun to implement barge transportation.

Jan 1, 1986

By A. J. Kwitowski

Remote control for mining machines ordinarily means the operator is not seated on the machine, but is located within direct view of the machine and work area Thus, remote control operators are exposed to the hazards of roof/rib falls and dust/methane explosions. The U.S. Bureau of Mines has developed a method to disassociate remote operators from these hazards. Off-board, computer-based "tele-operational" systems are utilized that station the operators one-hundred meters or more distant from the working faces. Details are provided for tele-operated systems for thin-seam extraction and haulage equipment in highwall and deep, room-and-pillar coal mines.

Jan 1, 1992

By S. Bhattacharyya

"Coal bearing rocks are low in strength and have geological discontinuities and moisture sensitivity. Roof and rib falls have been a major cause of fatalities in underground coal mines. Mine engineers design ground control plans for regulatory approvals. A number of tools are available from the National Institute for Occupational Safety and Health to design and assess these plans. Quite often there is not enough geotechnical input information available and databases are used. The Appalachian coalfields have extensive scientific studies to provide reliable regional inputs. Coal mines in the western United States and Canada have different geological and geotechnical conditions, and less available data. Use of inappropriate inputs in the tools like Analysis of Retreat Mining Pillar Stability, Analysis of Longwall Pillar Stability, and Analysis of Roof Bolt Systems may result in unsafe designs or over conservative designs. The tools are convenient but thorough understanding of the inputs, calibration with local test results, and operating experience are important for effective designs. The current paper contains examples of difficulties faced during mine planning using the above tools. INTRODUCTION Sedimentary rocks hosting coal are low in strength. Scientific studies have placed the uniaxial compressive strength (UCS), triaxial strength, tensile strength, and shear strength of sandstone, shale, siltstone, and claystone in lower range of strength among engineering materials (1). Coal bearing rocks are most often weakened by the presence of faults, folds, slickensides, bedding planes, fractures, and other geological discontinuities. The host rocks and coal are often moisture sensitive. The geological discontinuities allow water to enter the strata from surface and underground sources. This combination of low strength, structural weakness, and presence of water results in difficult ground control situations for the coal mines. Roof (2) and rib falls have been a major cause of fatalities in the U.S. coal mines. Modern underground coal mines necessitate wide entries to accommodate large production equipment. The gate roads, section entries, and the mains entries of a highly productive coal mine are as wide as twenty feet (6.1 m). The actual intersection width is nearly thirty feet (9.1 m). Adequate ground control is a key to maintain safe production in such mines. Mine engineers and their consultants routinely submit ground control plans to the regulatory authorities. While working out the necessary roof control system the mine engineers are required to demonstrate the adequacy of the proposed system. There are multiple ways to demonstrate this. Some engineers use traditional load calculation approach of roof bolts (3). Some engineers use numerical methods. Yet a large number of professionals resort to a suite of ground control design software offered by National Institute for Occupational Safety and Health (NIOSH) commonly referred to as “NIOSH Ground Control Toolbar.” These software tools are free and easy to download from NIOSH website. The software included in this package are: Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Coal Mine Roof Rating (CMRR), Analysis of Roof Bolt Systems (ARBS), Analysis of Horizontal Stress Effects in Mining (AHSM), Analysis of Multiple Seam Stability (AMSS), Analysis of Retreat Mining Pillar Stability - Highwall Mining (ARMPS-HWM). These tools are relatively simple to install and use in planning and designing coal mines and prospective coal mines. They accept a number of geotechnical inputs which are collected from either an existing mining operation or from exploratory boreholes. In the absence of necessary input parameters, the programs use default values which are drawn from databases of geotechnical properties built by NIOSH."

Jan 1, 2015

By A. John R. Hart

INTRODUCTION In each given set of operational criteria for tunnel design, ground conditions dictate the selection of the most appropriate construction method and tunnel lining. The designer has the responsibility to choose or restrict the choice of the tunnel lining to insure that the final solution provides a cost-effective permanent construction which will require the minimum of maintenance and endure to the benefit of future generations. This Paper deals with some of the aspects of precast concrete tunnel linings, their history and development through the years. It does not purport to be a comprehensive review of all that has ever been tried or developed but, hopefully, a starting point to encourage discussion and development for the future. BOLTED LINERS As a result of anticipating a shortage of cast iron tunnel lining in 1936 when work was proceeding on London Transport's Central Line Metro, a design for the precast reinforced concrete bolted lining was born. The design took the form of the traditional cast-iron lining but with substantial concrete stiffeners to take the shield ram forces. This new lining was used to construct some 14,000 feet of running tunnel using a ring width of 1'8" which was the standard cast-iron width of the time. (Groves, G.L., 1943)

Jan 1, 1987

By Philip Antunes, A. E. (Tony) Reschke

"INTRODUCTION Tunnel Boring Machine (TBM) operations require the injection of material into the annular tail voids as the machine advances ahead of the segmental concrete lining. This annular gap is created because the cutting diameter of the TBM has to be larger than the outer diameter of the concrete segments of the tunnel lining. Fundamentally, the two basic types of annular grout are thick, concrete like mortars and thin, mobile, two-component grouts. While some European countries seem to still favor the concrete like mortars, from a global perspective it is now the two-component type grouts that dominate the industry. Two-component type grouts are comprised of an “A” component grout (typically cement, flyash, bentonite and a retarder/stabilizer) and a “B” component accelerator (sodium silicate or water glass as it is sometimes known). They are thus sometimes referred to as A/B type or bi-component grouts and were pioneered by the Japanese over 30 years ago. They offer a host of operational benefits over thick mortars, such as reduced settlement (Feddema et. al., 2001), effective penetration of the void space, with less energy, and reduced strain on the segmented linings (Robinson et. al., 2007). Two-component grouts are highly mobile and can be pumped many kilometers. The use of a retarder/stabilizer can also extend the shelf life of the “A” component grout for several days while the early strength of the accelerated grout stabilizes the ground and supports the segmental liner almost immediately. The batch plants that prepare the two-component grouts use one of two possible mixing methods for preparing the “A” component grout. The simplest plants use paddle type mixers and numerous tunnels worldwide have been successfully grouted using this technology. However, a superior type of mixer is available, namely the high shear colloidal mixer. Keller Colcrete successfully pioneered the development of the colloidal mixer back in 1937 and for over 75 years colloidal mixers have been internationally recognised as the most efficient method of mixing cement based grouts (Houlsby, 1990). These mixers are used in grout preparation for radioactive waste encapsulation, hydro dam grout curtains, soilcrete jet grouting, soil nailing, and numerous other geotechnical applications. In tunnelling, these mixers are also used for ground treatment, compensation grouting and for the preparation of bentonite lubrication for pipejacking. It has been only within the last decade however that these high-shear colloidal mixers have been adapted for use in the preparation of two-component grouts."

Jan 1, 2016

By Michael Markels

The United States Environmental Protection Agency (EPA) is charged under the Federal Water Pollution Control Act Amendments of 1972 with establishing effluent limitations which must be achieved by point sources of discharge into the navigable water of the United States. Section 301 (b) of the Act requires the achievement by not later than July 1, 1977, of effluent limitations for point sources, other than publicly owned treatment works, which are based on the application of the best practicable control technology currently available as defined by the Administrator pursuant to Section 304(b) of the Act. Section 301(b) also requires the achievement by not later than July 1, 1983, of effluent limitations for point sources, other than publicly owned treatment works which are based on the application of the best available technology economically achievable which will result in reasonable further progress toward the national goal of eliminating the discharge of all pollutants, as determined in accordance with regulations issued by the Administrator pursuant to Section 304(b) to the Act. Section 306 of the Act requires the achievement by new sources of a Federal standard of performance providing for the control of the discharge of pollutants which reflects the greatest degree of effluent reduction which the Administrator determines to be achievable through the application of the best available demonstrated control technology, processes, operating methods, or other alternatives, including, where practicable, a standard permitting no discharge of pollutants.

Jan 1, 1975

By G. A. Nyamekye

Two major Inco matte constituents, chalcocite and heazlewoodite, are separated by differential flotation with diphenylguanidine as collector. A new reagent system involving the use of dextrin as a modifying agent which provides better selectivity has been studied for the last three years. Adsorption tests reveal that while dextrin exhibits high affinity towards heazlewoodite, the adsorption isotherm for dextrin on chalcocite shows only weak interactions. Our electrokinetic measurements confirm such conclusions. Since dextrin interaction with solid surfaces seems to be especially strong when such surfaces are covered by hydroxide layer, our electrokinetic measurements are in line with other researchers' findings who postulated that copper hydroxide is not a stable product on the surface of copper sulphides.

Jan 1, 1992

By C. W. Chiaretta

Utah Power and Light Company's Deer Creek Mine had been developed to a point where mine ventilation efficiency had declined to an unacceptable level. Problems identified were ventilation of inactive areas, excessive leakage, and restrictions in the return and intake air ways. Mine management implemented an intensive mine ventilation improvement program to alleviate future problems with respirable dust in the working sections and diesel equipment emissions. Program objectives included sealing of inactive areas of the mine, rehabilitation of high resistance areas, and construction of additional intake and return aircourses. Applications of computer modeling techniques are used to predict the effects of ventilation changes and improvements. Improvements are then prioritized to achieve the largest efficiency increases first. Actual real time assessment of the mine environment and ventilation changes are accomplished with a mine wide monitoring computer system. The Deer Creek ventilation improvement program has more than doubled the ventilating efficiency of the mine.

Jan 1, 1990

By Steven McCutcheon

As most of us have learned through prior and often frustrating experience, anyone proposing to construct a new or expanded mining-ore processing facility must first contend with a rather complex array of environmental laws and permitting regulations administered by a number of different Federal, State and local agencies. At our lost count, there were about 55 federal enactments affecting base and precious metals projects. Applicable State and local laws will usually increase that number significantly. The time and costs associated with complying with all these various regulatory programs usually constitutes one of the major areas of uncertainty in the development of a proposed project. There are many in the mining industry who firmly believe that these environmental regulation and permit programs necessarily causes significant delays and increased costs in the development of a project. This belief, unfortunately, is probably a result of a basic misunderstanding of how the environmental permitting and regulatory system actually works.

Jan 1, 1984

By K. G. Black

When one's attention moves from the control of a process unit or from the control of a department of similar units, to the control of an entire plant, two things must change. One is the techniques of control, and the other, the goal or purpose of control. The goal is no longer maintaining a certain quality of product or maintaining a particular flow rate through a process unit. The goal becomes economic - how to make the most money out of the plant. The principal control techniques become those of optimizing, rather than regulating. It is quite common to discuss the control of an entire plant in terms of three levels of control l; regulation, supervision, and optimization. Regulation is the control of inputs to a process unit at desired values. This is accomplished by two or three mode analog controllers or DDC loops. The second level of control is the selection of these desired values, e.g., set-points of the regulation controllers. The third level is to make such adjustments or corrections to the supervisory calculations so as to optimize the plant profit. It is immediately evident that supervisory control and optimizing control are intimately related, and a distinct dividing line cannot always be drawn between the two. Some authors prefer to add even more levels such as adaptive control and management information systems, but we believe our point is well made without further division of the functions which are necessary for complete plant control. To accomplish the economic goal, that is, the optimizing (maximizing) of the profit of a mineral processing plant, the plant should ideally be operated as if it were a separate company, buying its raw materials on the open market and selling its products on the open market. While petrochemical plants endeavor to operate in that manner, unfortunately this is not true of a mineral processing plant. The plant manager has to accept the amount and quality of ore the mining department delivers to him, and the products (concentrates) are delivered to another department of the company for further refining. In some cases he may sell

Jan 1, 1972

By B. Pesic

Manganese is about twelfth in the list of the most abundant elements in the earth's crust (Reidies, 1981). More than 150 known minerals contain manganese as an essential constituent (Mellor, 1932). In general, ores containing at least 35%Mn are classified as manganese ores, ores with 10-35%Mn are called ferroginous manganese ores, and ores containing 5-10%Mn are known as manganiferrous ores. One very important class of manganiferrous ores are manganiferrous-silver ores. They occur in the oxidized portions of the silver deposits of the Western United States. Silver is very often associated with manganese oxides which in some ore deposits are dispersed through calcite, causing the black color of the host rock, which is known as black calcite. Black calcites can occur in carbonate rocks (10-1500oz Ag/ton) and in volcanic rocks (less than 1.0oz Ag/ton).

Jan 1, 1986

By R. P. King

Knowledge of the behaviour of flotation machines had developed and increased considerably over the last few years. Although much work remains to be done on the study of the fundamental processes that influence the collection of hydrophobic particles at an air-water interface, there is enough information to permit the building of realistic models of the gross flotation behaviour of various ores. These models serve as an ideal base for the development of simulation techniques for the steady-state behaviour of entire flotation plants that consist of a large number of individual flotation machines. Simulation techniques have a very real role to play in assisting with the design of new plants and in improving the operation of exisiting plants. Recently, highly efficient data-logging systems have been introduced on flotation plants. These systems are based on the on-line measurement of volumetric flowrate, pulp densities, and metal contents, and they generate enormous quantities of information regarding the operation of the plant. Unfortunately, this information is largely wasted at the present time because efficient data-reduction techniques, although available10 are not in common use. Simulation techniques play a central role in such data reduction because they form the essential link between the fundamental kinetic flotation processes on the one hand and the plant data on the other.

Jan 1, 1974

By Yuji Tsuneno, Yoshikazu Mikami, Yasuo Takeuchi

A new device was successfully developed in order to overcome the difficulty of drilling longer holes for anchors in soft soil bedrocks or swelling bedrocks, which is one of the major impediments to rapid excavation by NATM (New Austrian Tunnelling Method). With higher rotation (1200 - 1800 r.p.m.) and lower percussion energy (4 - 6 kg.m), the new drill has following advantages: (1) Applicability covers soils and medium hard rocks with the same drifter. (2) Longer hole (more than 9m) is achievable only with air flushing even in cohesive soils or rocks. (3) Better borehole stability is obtainable even in earth or in fissured rocks.

Jan 1, 1981