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By W. S. Weldon, R. M. G. Machunter

The use of spiral separators for the beneficiation of fine coal typically in the size range - 2+0.lmm is now well established process technology. Developments during the mid 1980's resulted in the production of cost effective, efficient large diameter coal spiral separators. Recent developments and research have been geared to optimise metallurgical performance, materials handling and equipment geometry of large diameter coal spiral separators.

Feb 24, 1997

By Paulo José Costa Couceiro Junior, Manuel Lopez Cano

The biggest Port of Latin America - the Santos Port in São Paulo, Brazil - has been drilled and blasted by controlled underwater techniques in order to remove around 40,000 m3 (52,318 cubic yard) of rock divided in two outcrop rocks: Teffé and Itapema. Underwater pumped explosive, in combination with small cartridges areas, was successfully used in order to reach a target depth of -15m (-49 ft) and a width of 220m (722 ft) in the navigation channel. It was the first time that a pumped explosive was used in underwater blasting in Brazil and it represents a historic benchmark for projects of this kind in this country. The main challenges faced in this project include the control of the ground vibration, due to the necessity to carry out detonations 40m (131 ft) away from the quay wall - where the passenger terminal and the 80 year-old warehouse were located – and the rush schedule available, in order to finish the underwater drilling and blasting phase before the coming cruise season. Therefore, the perfect combination of an ideal pumped product with an effective pumping system has permitted to carry out the project in a record of less time than 3 months (against to the original expected time of 18 months), with all vibration events under control as result of the special ground vibration program carried out.

Jan 1, 2016

By T. Holmes, J. Middlemiss

"Agnico-Eagle (AE) has been operating their Kittila Mine in Northern Finland since 2008. The mine has experienced considerable ore flow problems with ratholing, bridging and freezing in their mill feed bin since start up. In the first winter of operation, the entire central portion of the contents of the cylindrical flat-bottomed 2000 tonne mill feed bin froze. Flow was erratic and could only be achieved through small diameter ratholes. To maintain a reasonable, albeit limited, feed to the mill, the bin had to be kept less than ½ full and a portable steam generator was brought in to melt the frozen agglomerates that frequently blocked the outlets. The combination of limited surge capacity and frequent outages required the crushing plant to operate 24/7 and resulted in inconsistent production levels and high operating costs.AE had planned to expand the processing plant to increase throughput by about 30% when they transitioned from open pit to underground ore. These plans presented an opportunity to improve the material handling.To avoid the problems experienced with the original mill feed bin, AE enlisted Jenike & Johanson Ltd. (J&J) to test samples of the ore, and based on the measured flow properties to provide design recommendations to ensure that the new mill feed bin would operate reliably. The new 2000 tonne expanded flow mill feed bin and apron feeder were installed in 2014 and are now supplying almost 93% of the total mill feed with the remaining coming from the original bin.IntroductionIn early 2009, AE engaged J&J to visit their then recently opened Kittila mine and mill in Northern Finland (Figure 1). Over the first half-year of operation, production had been restricted in the ore handling and storage system by flow problems such as ratholing, bridging and freezing including blockages of chutes and hoppers as a result of frozen fines buildup and large frozen agglomerates. AE wanted to increase production in the existing open pit mine and mill feed operation and also wanted to avoid similar ore handling problems when they commissioned the new underground mining system under development at that time."

Jan 1, 2017

By Refik Elibay, Lawrence A. Williamson, George D. Barnes

Under an extremely aggressive schedule, final design of 13.5 km (8.4 miles) miles of 8.2 m (27 ft) diameter deep rock tunnel, 322 ML/day (85 million gallons / day)submersible pumping station and associated facilities were accomplished ahead of a federal court mandated consent decree schedule. Challenges overcome by the project team in enabling timely completion of the construction documents will be presented. Discussion includes evolution of final design, consideration of future O&M requirements, and risks identified for construction and operations, together with measures to manage and proactively prepare for such risks.

Jan 1, 2005

By Anthony T. Xannacchione, Luis E. Vallejo

At present, there is little knowledge concerning the shear strength of clays containing floating rock particles with concentrations from 0 to 30%. In practice, the effect of rock particles is typically disregarded in shear strength analysis The two primary reasons for this are: 1) a lack of agreement concerning the influence of rock particles on material strength, and 2) the expense and difficulty of testing day-rack mixtures with existing laboratory procedures. These factors have impeded the development of successful slope remediation design techniques far colluviums derived from resistant sedimentary rocks or spoil produced from surface mining. This study reviewed 3 1 technical papers which contain analysis of shear strengths for clay and sands with varying mixtures of rock particles. These technical papers, published over the last 40 years, are comprised of field case studies, laboratory evaluations, and theoretical analysis. Evaluation of this body of knowledge ha shown that the shear strength gradually increases with increasing percentages of floating particles in unsaturated clays.

By Lance A. Roberts

Micropiles are commonly utilized for applications other than foundation retrofit. In bridges, for example, micropiles can serve as the permanent foundation elements or can be used in temporary support applications. In this paper, a case study on the use of micropiles for the 18th Street Expressway Bridge rehabilitation/repair project in Kansas City, Kansas is presented. In the project, micropiles were utilized for support of six temporary jacking structures, which allowed the bridge to be lifted while repairs were completed. A group of six micropiles was required to support each jacking structure. The required compressive service load per micropile was approximately 300 kips (1300 kN) and the settlement of the micropiles under the service load was to be limited to 0.5 in. (12.7 mm). Two field compression tests were conducted as part of the project. The field load test data was integrated within a soil-structure interaction capacity approach in order to analyze and permit the shortening of the design bond length for the production micropiles.

Jan 1, 2009

By D. Settles, R. Rose, P. L. Dunn

"A new mineral sands operation is being developed in Georgia by Southern Ionics, Inc. (SII). Prevailing mineralogy and certain design constraints required detailed testing and circuit analysis to create a robust separation processes. The floating wet concentrator plant (WCP) and mineral separation plant (MSP) flow sheets were designed based on historical testing information and recent SII test campaigns on various composite feed samples. The flow sheets were finalized through rigorous process and orebody sequence modeling.The process uses traditional physical separation equipment; however a new MT spiral, the MG12, was selected for use on board the WCP for roughing duty. The MG12 spiral is a two-stage, twelve-turn spiral that has been proven to achieve very high recoveries of heavy minerals. The floating plant includes feed desliming operations, a central MT surge bin for optimum spiral circuit feed control and ancillary operations for concentrate and tailings handling. Scrubbed heavy mineral concentrate (HMC) is then transported to the MSP for concentration of the titanium and zirconium bearing mineral fractions.The testing, flowsheet development, and plant design will be described and explained, and a brief summary of the current project status will be given.IntroductionSouthern Ionics Inc. (SII) is a privately held chemical manufacturing company, founded in 1980 by Milton Sundbeck. SII focuses primarily on the sale of specialty and intermediate inorganic chemicals. Core markets include cement and refinery catalysts, molecular sieves, zeolites, pulp and paper, pharmaceuticals, TiO2 and water treatment. SII is built on the four cornerstones of service, quality, technology and delivery with all SII facilities ISO certified and key products used in potable water treatment certified to NSF standards. SII owns and operates its own transportation fleet and is focused on being a low cost producer, committed to safety and the environment."

Jan 1, 2015

By S. A. Osterberg, J. L. Breckenridge, R. S. Popielak

Multidisciplinary investigations were completed to prove the availability of water resources for the proposed San Cristóbal silver-lead-zinc mine in the arid Altiplano of Bolivia. Surface water resources are scarce, of poor quality, and unsuitable for development. Therefore, hydrogeological reconnaissance targeted alluvial aquifers for development. Follow-up resistivity, refraction, and water quality assessments were used to prioritize areas with prolific production potential. Pumping tests and regional water balance analysis indicate an alluvial aquifer can sustain the required approximately 40 000 m3 per day production for the life of the mine and predict no significant negative environmental effects on local groundwater users and the environment.

Jan 1, 2002

By Michelle Lostra, Red Blanchette, Jan Babendererde, Greg Colzani

The City of Portland’s Westside CSO Project is constructing a deep tunnel system to reduce combined sewer overflows (CSO) from entering the Willamette River. Several kilometers of microtunneled pipelines connect the existing system to the new tunnel. The alignments encountered a variety of ground conditions, including fill, manmade obstructions (wood, steel piles, debris), fine-grained to dense coarse-grained materials, cobbles and boulders, all below groundwater. A slurry MTBM convertible to varying diameters, equipped with mix shield capabilities, was selected to cope with the conditions. This paper will discuss access shaft construction,

Jan 1, 2005

By L Olivier, R J. Lowther, J L. Lett, I Brunton

Hydraulic fracturing to precondition the orebody to enhance rock mass cavability is gaining acceptance in underground cave mining applications. Assisting cavability is becoming important as an increasing number of cave mines are being implemented in hard, deep and competent rock masses where clamping stresses are higher and cave column heights may be in excess of 1000 m. Propagating large caves to surface in such conditions can be challenging as risks such as slowed propagation and air gaps can develop during the process.Underground-based hydraulic fracturing is routinely used at Cadia East as a means of preconditioning the orebody to assist in cave propagation, fragmentation and seismicity reduction. This paper presents a summary of a surface-based hydraulic fracture program that was successfully implemented to assist in the propagation of the Cadia East Panel Cave 1 (CE-PC1) cave to surface through competent overlying rock masses. In this case study, the propagation of the CE-PC1 cave slowed as the cave grew past 750 m in height, initiating a Trigger Action Response Plan regarding the cave propagation rate. Surface-based hydraulic fracturing was subsequently used to stimulate the cave to propagate through the final 450 m to surface. The paper details the equipment, strategy, implementation and risk management involved in the program as well as the key learnings.CITATION:Lowther, R J, Olivier, L, Lett, J L and Brunton, I, 2016. Implementation of a surface-based hydraulic fracturing program to successfully propagate a large cave through hard, competent near-surface rock masses to achieve breakthrough, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 83–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By M. Ramström

"In 2002, Atlas Copco Rock Drills AB released the new rig control system (RCS) technology for all of its drill rig types. RCS opened the way for a new generation of computerized drill rigs based on modern, standard PC-computer technology. Drilling accuracy, information logging, reduction in manpower in some types, and serviceability have all taken a quantum leap forward when compared with previous generations of drill rigs. RCS is modularized and distributed by means of CAN-bus technology. This technology, which is well proven in automobile applications, forms the communication backbone of the rig. The modularity facilitates almost unlimited possibilities for the expansion and adaptation of drill rig functions."

Jan 1, 2005

By S. Rivard

"This paper demonstrates the selection of grinding circuit technology for a number of recent projects including discussion of the key drivers and the role of energy efficiency. Decreasing head grades combined with a strong and sustained increase in operating costs has forced miners to examine increased project size, increased equipment capacity and efficiency improvements in order to reduce their unit operating costs and improve overall project economics. Comminution energy consumption, safety and capital cost considerations play a critical role in the success of projects. This paper presents some key guidelines for a successful and cost effective comminution circuit design and includes a case study on three projects, outlining the issues and the drivers which led to the ultimate circuit selection and the critical role that energy efficiency played.IntroductionComminution circuits for minerals processing are selected based on their suitability and efficiency in reducing run-of-mine ore to the desired feed size for the downstream process. The input material (ore) properties and downstream process requirements are the key determinants and there are standard approaches for each circumstance.The minerals processing industry has been a fast adaptor of efficiency improvements based on increasing capacity of equipment (e.g. trucks, crushers, mills, pumps) but less successful in adapting radically new technologies that disrupt incumbent flowsheets or processes.The installed power of grinding mills has increased linearly over the past 25 years (Meka & Lane, 2010) and pumps and classification equipment have kept pace. The autogenous grinding (AG) and semi- autogenous grinding (SAG) mills displaced stage crushing as a dominant method of coarse rock breakage in many applications causing crusher manufactures to increase the capacity of cone crushers to meet the competitive demand.Examples of new comminution technology in the 20th and 21st centuries are the development and adoption of cyclone classification in the 1940s (Newtech, 2016), AG milling in the late 1950s, vertical grinding mills in the 1980s, high pressure grinding rolls (HPGRs) also in the 1980s and ultrafine milling technology in the 1990s (Meka & Lane, 2010)."

Jan 1, 2017

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A. G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids, and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue-gases, the circulating fluid bed technique with internal oil combustion at 220°F for the calcining step and a five-stage fluidized bed cooler for heat-recovery from calcines, the process gives an outstanding heat-efficiency. In a first industrial plant for 560 sh. tons/day of alumina heat consumption figures of less than 1·400 B.T.U./lb Al203 g were achieved.

Jan 1, 1972

By W. H. Schiffbauer

NIOSH has developed an active proximity warning system called HASARD (Hazardous Area Signaling and Ranging Device) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels which are calibrated to identify levels of danger. The receiver outputs can include visual, audible, and vibratory indicators and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak, and on a highwall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed and proved to be rugged enough to withstand the harshest of production environments.

Jan 1, 2001

By John Kosek

The electrochemistry of carbon monoxide, nitric oxide and nitrogen dioxide was investigated at a variety of electrode materials in different supporting electrolytes. A portable detector for carbon monoxide was developed using a porous gold anode in perchloric acid supporting electrolyte. This detector has two full scale ranges, 0-100 ppm and 0-500 ppm. A portable detector for mixtures of nitric oxide and nitrogen dioxide was developed using a porous silver cathode in sulfuric acid supporting electrolyte. Nitrogen dioxide was determined in the gas stream by electroreduction. The nitric oxide in the gas stream was oxidized to nitrogen dioxide by passing it over Cr(VI) on firebrick. Electroreduction gave the sum of NO + N02. Analog circuitry was used to display the amounts of NO and N02 separately. Two ranges were available for each gas. They were 0-10 and 0-50 ppm for NO and 0-2 and 0-10 ppm for N02.

Jan 1, 1979

By Richard Rittenhouse

This program was to develop a new base line system for automated continuous room and pillar type mining. The primary requirement estab¬lished for this machine is that the machine be capable of mining and bolting simultaneously. Additionally, this machine was to provide temporary and permanent roof control, have a productive - full - face semi-automatic mining system, leave a clean entry outby the machine, provide maximum operator protection, provide effective dust suppression and provide air scrubbing to restrict respirable dust to permissible levels. The machine has effectively demonstrated the ability to mine and bolt simultaneously. Additional above ground operation, testing, and time studies are recommended to further verify the machines abilities. Design improvements are recommended for future generation AES machines. These relate to marginal design areas such as side loading on vent duct lift cylinders, etc., that will not impair additional testing of the existing machine.

Jan 1, 1983

By James L. Eirls

Tracor MBA under a contract to U.S. DOI Bureau of Mines designed, developed, fabricated and demonstrated a conveyor belt service machine. It is self-contained, battery powered, rubber tired and capable of handling, storing and transporting conveyor belting, wire rope and associated structures for sectional conveyor belts. While moving the tail section to its next position the machine discharges the belting, wire rope and belt structures. The belting is elevated and separated to provide for the insertion of the structures with minimum expended effort. A hydraulic system provides the power for steering, braking, winding or unwinding under controlled tension the belting and wire rope, operating a load-bed slat conveyor, raising, lowering and locking connection hitches and powering external hydraulic tools. Also, a pneumatic system is available to operate air impact tools. The service machine, with its present components can function in coal seams as thin as 48 inches, double wind conveyor belting 42 inches wide, 400 feet long, load or unload 3/4" wire rope on two separate reels and is controlled by two operators. A complete belt move using this machine requires only four workers. Successful underground demonstrations were conducted in coal mines located in West Virginia and Kentucky.

Jan 1, 1983

By B. J. Moore

This publication contains analyses and related source data for 269 natural gas samples from wells and pipelines in 18 States. All of the samples were obtained and analyzed during, calendar year 1979 as a part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4862 and 576.3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the general public. Twenty-one previous publications have presented tine results of 11,883 gas analyses made prior to 1979. The first three, Bulletins 486,4 576,5 and 617,6 contain analyses and related source

Jan 1, 1980

By Gary A. Halvorson

Plots were established on regraded abandoned mine spoil to determine if nearby good quality spoil could be used in place of topsoil for the reclamation of these sites. Gypsum, calcium chloride, and power plant ash were also tested to determine the effectiveness of these materials in reclaiming these sites. Two sites were selected on which very little vegetation was growing on highly sodic spoil material. Gypsum, calcium chloride, and ash were added to the spoil at a rate designed to reduce the (sodium adsorption ratio) SAR in the surface 15 cm to 10 or less. The good quality spoil (replacement soil) was then laid on the swface at rates of 0, 5 or 15 cm of material. The plots were seeded to a mixture of smooth bromegrass (Bromus enennis Leyss.), crested wheatgrass (Agropyron desertorum (Fisch. Ex Link) Schult.) and alfalfa (Medicago sativa L.). The addition of 5 or 15 cm of replacement spoil significantly improved vegetative growth on these sites. Chemical treatments had no effect on vegetative growth. Weathered ash showed no adverse effects on plant growth or soil properties.

Jan 1, 1991

By Thomas A. Giordano

Portable communications equipment is becoming increasingly important in underground mining. Proper selection of microphones and hearing devices to be part of these communication systems is essential if the messages are to be transmitted intelligibly. In this program a thorough study of the requirements for these transducers was made with respect to intelligibility, mechanical configuration, human factors and safety. A computer analysis was made to predict how several combinations of transducers would perform at typical mining noise levels. A survey has been made of those microphones and hearing devices on the market today that might be applicable to the miner communication system. Several systems are proposed and evaluated.

Jan 1, 1976