Search Documents

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through the use of more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the air bubbles, water, and ore, rapidly attaching the hydrophobic mineral to the bubble surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. A rougher concentrate containing 4.5 pct copper was obtained from a western porphyry copper ore containing 0.67 pct copper. Over 99 pct copper was recovered from the ore at a rate 7 times faster than conventional flotation.

Jan 1, 1991

By Charles W. Bauer

Most of the aluminum produced in the United States today is derived from foreign bauxite deposits. Earth Sciences, Inc. initiated a program to evaluate domestic non-bauxite sources for alumina in the 1960's. In the initial evaluation of alunite, domestic resources were not sufficient to support development. An exploration program led to the discovery of large deposits of alunite in Utah and several other western states. Identification of alunite is difficult as both its physical and chemical characteristics are similar to the minerals with which it is associated. Most of the significant alunite deposits in the western United States are replacement type deposits. These deposits have formed as a result of hydrothermal alteration of volcanic, sub-volcanic, and igneous rocks. Typical alunite deposits contain between 30% and 50% alunite between 50% and 70% quartz with minor amounts of other minerals. Four mineralogical zones are common in these systems. They include a siliceous zone, a quartz-alunite zone, a kaolinite zone and a chlorite-montmorillonite zone. Total U.S. reserves of alunite were estimated at 20 million metric tons (at 30% alunite) by the U.S. Bureau of Mines in 1941. Here recent work by the U.S. Geological Survey estimates reserves of 252 million metric tons and potential resources at 1.4 billion metric tons. Reserves and resources estimated for 23 properties on which field work has been done by ESI are considerably higher. Most of these properties have reserves and potential resources of several hundred million metric tons. The combined demonstrated reserves at these properties are estimated to be about 650 million metric tons. Inferred reserves are estimated at 2.5 billion metric tons and potential resources at 8 billion metric tons. It appears that the U.S. has sufficient reserves and resources for alunite to be considered as a potential non-bauxite source of alumina.

Jan 1, 1980

By I. Weir-Jones

[Currently the cost of carrying out 'in situ' geotechnical investigation programmes or installing and operating monitoring systems at construction or mining sites is rising var." rapidly. This is primarily because of our ever increasing labour rates. As a result of this problem efforts are no,, being made develop techniques for the economical; collection of large quantities of geotechnical data relating, to such problems as done stability evaluation, the behaviour of underground openings, or 'in situ' testing procedures. The efforts to reduce the labour content. are particularly apparent in those procedures which have traditionally been manpower intensive e.g. 'in situ' permeability testing where an entire drilling crew and their associated eguipment have been on standby while testis has been carried out; or data collection in underground construction operations where much tine is typically wasted obtaining or maintaining access to instrument sites. In an attempt to illustrate one specialist consulting company's approach to the problem of reducing investigation costs, this rarer examines four recent developments in the field of geotechnical investigation and monitoring which have come about during the last two Years as a result of cur research and development programme. Although these techniques and devices have been developed for specific projects, they all have broad applications in the geotechnical field and they are indicative of the direction in which this company feels developments will take place.]

Jan 1, 1975

By M. du Plessis, J. P. Gouvea

Mesh based areal support is commonly applied in South-African deep-level gold mines. It forms part of an integrated support system that can cater for both rockfall and rockburst incidents. The application has been successfully applied over many years. Operations have different geotechnical conditions and practical considerations, which has led to the development of various types of mesh and integrated mesh-based support systems (i.e. meshing and lacing versus welded or chain-link mesh sheets). Typically rolls or sheets of mesh is pinned with rockbolts to the surface of an exposed excavation. Applications vary from hangingwall coverage in a conventional stope gully to complete excavation coverage in footwall drives of conventional mines or on-reef drives in massive mechanised mines. It is however critical to understand the behaviour of the rockmass and apply suitable support systems.

Apr 26, 2022

By Harry H. Peek

Artesian pressures of unusual magnitude occur in the deeper aquifer units beneath a considerable part of southeastern North Carolina and extend into South Carolina. The high pressures were first observed in 1968 in wells near Wilmington that were drilled to "basement" rock and which were screened between depths of about 260 to 300 m (meters). The pressure was recognized by Peek and Heath1 as an anomalous geo-pressure and unrelated to recharge conditions in the region. Since 1973, much new information has been obtained on hydro-geologic conditions in the area and a preliminary report on the deep artesian pressures was published in 1975.2 Most of the basic information has been obtained from groundwater research stations constructed by the Groundwater Section of the North Carolina Department of Natural and Economic Resources as a part of Ground-water studies in the Coastal Plain Region. These stations consist of an exploratory well drilled to basement rock with wells completed in each principal aquifer unit to provide data on aquifer characterestics, water levels and water quality.

Jan 1, 1977

By Raymond S. Shrode

Transportation is one of several important increments in the total market cost of most commodities. On a national average it has been reported that transportation accounts for about 25% of the total cost of a product at the market place. And industrial minerals are no exception. In fact, the proportionate cost frequently exceeds the 25% average. Further, it may actually determine the economic value of a deposit. Transportation may possibly be thought of as a specialized subject of concern only to a traffic manager and of only nominal interest to the mining engineer, the geologist or other technically oriented member of mineral producers' staff. However, in the industrial minerals field, interest is not commonly confined to exploration, development, production or marketing, but is in contrast an overlapping one. In a very real sense this broad area of interest in the total economics of the business is the specialty of the industrial minerals man. And transportation is a vital part of the total picture. Comments in this paper deal with rail transportation.

Jan 1, 1969

By G. J. Goldberg

Through the early 1980's, surveying at Bingham Canyon required a great deal of repetitive and manual work. The advent of total station surveying equipment provided an opportunity to improve the speed and accuracy of surveying work while reducing manpower needs. An evaluation of total station systems and their ability to meet the surveying requirements of Bingham Canyon culminated in the purchase of a total station system as the mine re-opened in 1986. This paper presents the procedure for evaluating, implementing and using the total station survey system at Bingham Canyon.

Jan 1, 1990

By Stuart R. Cotterill

Open cast surface mining requires blast hole drilling with many interesting facets in order to achieve mine planning forecasts. Interestingly, no single method or combination of theoretical hypothesis of mining economics is right for all conditions. On occasion mine planners introduce a project with little or no regard to drilling and blasting. Generally, drilling and blasting costs are a significant percentage of total mine overhead. One such drilling and blasting method which can be utilized to reduce overall mine expenditure is inclined or angle hole drilling. One must bear in mind, that angle hole drilling per-se mill not reduce costs, unless a set of required circumstances is met. An attempt will be made to detail when conditions of the mine design criteria dictate the use of angle drilling.

Jan 1, 1984

By N. E. Norman

The big hole drilling industry is a relatively new one. In fact, very little big hole drilling was done prior to 1950. If there is to be a marriage between big hole drilling and mining, we should certainly take a look at the background of the big hole drilling industry. Let us examine the three main features of big hole drilling and determine how each applies to mining. Let's also look at the good qualities and the limitations of each of these character traits.

Jan 1, 1968

By E. K. Albert

In 1977, Congress enacted Title IV of the Surface Mining Control and Reclamation Act (SMCRA), providing for an "abandoned ml.ne reclamation fund". This fund, taken from a fee collected from operating coal mines, provides capital for the reclamation process. However, given the number and extent of abandoned mine sites in some states, the question of project selection is important. This paper describes a project in progress to create a Management Information System application for project ranking under multiple objectives. The benefit of this project for the need of new environmental control technologies will be discussed.

Jan 1, 1990

By R. A. Thomas, C. D. Litton

"The objective of this study was to develop a laboratory-scale method to rank the ignition and fire hazards of commonly used underground mine materials and to eliminate the need for expensive large-scale tests that are currently being used. A radiant panel apparatus was used to determine the relevant thermal characteristics of the materials: time to ignition, critical heat flux for ignition, heat of gasification, and mass loss rate. Three thermal parameters, TRP, TP1, and TP4, were derived from the data, then were developed and subsequently used to rank the combined ignition and fire hazards of the combustible materials from low hazard to high hazard. The results compared favorably with thermal and ignition hazards of similar materials reported in the literature and represent a simpler approach to quantifying these combustible hazards. INTRODUCTION The potential fire hazard from combustible mine materials is a major concern that can impact the safety of mine workers. Combustible materials tend to be solids and within this category there exist degrees of flammability and fire resistance. These materials may be readily ignitable or they may be able to withstand high temperatures and high heat fluxes. Presently, no simple methodology exists to assess these possible fire behaviors and quantify the resultant fire hazards. Thus, better knowledge of the thermal properties and chemical characteristics of combustible materials is of great importance to the safety of mine workers. Tewarson [1994] developed a methodology which he subsequently used to evaluate the ignition and fire resistant properties of combustible mine materials, but these efforts are more than 20 years old, and do not include many of the new materials used in mines today. The standard practice that has evolved for a combustible material to be approved by the Mine Safety and Health Administration for use in underground coal mines is to conduct extensive and costly large-scale experiments on each new material that is used in a particular mine operation. Results of such tests provide pass/fail answers to the questions of a material’s flammability or fire resistance, yet they provide little, if any, information that will lead to a better understanding of the basic mechanisms involved. Therefore, there is a need to quantify material flammability properties and to develop a methodology to rank the ignition and fire hazards of commonly used underground mine materials. During the heating and ignition stages of combustible materials, properties such as smolder susceptibility, minimum surface temperature for ignition, thermal conductivity, heat capacity, density, and heat of gasification are known to be important [Apte, 2006]. During the flaming stage, additional parameters, such as the heat of combustion, heat release rate, flame spread rate, yields of soot/smoke, and toxic gas production become more important as the flame is sustained and spreads. In very general terms, the heat flux incident on the surface of a solid combustible not only controls the rate of temperature increase of the local fuel surfaces, resulting in expulsion of fuel vapors that sustain the flaming process, but also the heating of other combustible surfaces that subsequently ignite and spread flame."

Jan 1, 2015

By S. D. Bearden

The world's reserve base is adequate for at least 100 years at the current consumption rate. China, India, and the U.S. are expected to remain the leading producing countries. The U.S. will continue to be the largest consumer of the production. None of the known substitutes for barium sulfate are expected to impact existing applications. World production in 1995 was 4,410Mt. This is about 50% of the projected capacity. Consumption is directly proportional to hydro-carbon well installation activity. Imports are expected to continue to supply more than half of the U.S. requirements.

Jan 1, 1997

By E. E. Malouf

For centuries small amounts of copper have been recovered from acid mine-drainage waters. In recent years, the expansion of copper-bearing waste dump leaching for copper recovery has established a technological basis that is rapidly converting the art of copper leaching' into a science. Leaching of copper, whether from copper-bearing ore or waste, follows well established chemical reactions. These reactions are commonly in an acid circuit, but where leaching of copper is to be made in rock that is a high acid consumer, ammonia and ammonia carbonate, as well as cyanide leach solutions, can be used effectively. Current hydrometallurgical processes are being applied at an ever increasing rate to recover the trace amounts of copper in copper mine waste by in-place leaching. Currently approximately 300, 000 tons of copper are produced annually in this manner where as recently as ten years ago, only one-eighth of this amount of precipitate copper was produced.. Where copper occurs as an oxide in higher concentrations as to be classified as an ore rather than waste, then the hydro-metallurgical processes are applied as percolation or agitation leaching in vats, pachuca tanks, or prepared heaps. This approach gives better control over the recovery of the leach solutions, particularly in the processes where ammonia or cyanide leaching agents are to be used.

Jan 1, 1972

By R. J. Sweigard

Productive and beneficial use of reclaimed surface-mined land is a concern of industry, government, and the general public. An investigation was conducted of current mined-land planning practices to aid in the development of a procedure for evaluating postmining land use potentials. This investigation considered both the industry and public planning approach to mined-land planning and was based primarily upon three case studies conducted in various regions of the United States. The site planning process that was developed during the investigation is iterative in nature and has been designed specifically for the mining industry. It centers around preliminary studies and data collection, development of land use alternatives, and the evaluation of alternatives. Use of this process facilitates the evaluation of economic, environ- mental, and social impacts of postmining land use alternatives. In this paper, the process is presented along with a description of its development, application, and significance.

Jan 1, 1984

By H. S. Castro

The by-product molybdenite technology in Chile is reviewed. Flowsheets, reagents and some operation features for the actual six Chilean moly plants(Chuquicamata, El Teniente, El Salvador, Andina, Las Tortolas and Pelambres), are presented. The chemical and physicochemical factors involved in the depression of copper and iron sulfides during the selective flotation of molybdenite, with sodium sulfide, sodium sulfhydrate, anamol-D and LR-744, are discussed. Advances in technology to solve problems of excess of lime (precipitation with sulfuric acid); excess of residual flotation reagents (activated carbon and kerosene); and optimization of depressant consumption (Eh control, nitrogen and low-oxygen air), are discussed.

Jan 1, 1998

By John Greenhalgh, Benoit De Rivaz

"1.INTRODUCTIONThis paper is based on the Lee Tunnel project, which is part of the Thames Water’s Tideway Project.The client Thames Water has employed a Joint Venture of Morgan Sindall/Vinci Grand Projets and Bachy Soletanche to undertake the design and construction of the project under the management of CH2M Hill at a value in excess of £635 million ($990 million). The 3 main elements of the tunnel project are the permanent lining to the shafts, the precast segmental lining, and the secondary tunnel lining. All 3 are reinforced with different types of Dramix steel wire fibers and each element will be described in this paper. This paper will explain the basic structural design of FRC (Fiber reinforced concrete) based on the post cracking residual strength and will describe all the steps of this project, the testing program realized to support innovative design and the main technical learning point. 2.BASIC CONCEPT OF STRUCTURAL DESIGN OF FRCStructural design of FRC elements is based on the post-cracking residual strength provided by fiberreinforcement. Other cases, like early age crack-control or fire resistance, are considered non-structural use of FRC. For structural use, a minimum mechanical performance of FRC must be guaranteed. Fibers can be used to improve the behavior at SLS (Service Limit State) since they can reduce crack spacing and crack width, thereby improving durability and they can be used to improve the behavior at ULS (Ultimate Limit State) where they can partially or totally substitute conventional reinforcement in most conditions. In the design process, the definition of the performance expected from the material is a key factor and the mix-design of the material has to be optimized for the required structural performance.2.1 Testing Method In order to ascertain the structural requirements requested for the FRC segments, preliminary testing on samples will be required and the effectiveness of the proposed solution will also be assured by the testing of full scale specimens. Structural design of FRC elements is based on the post-cracking residual strength provided by fiber reinforcement. For structural use, a minimum mechanical performance of FRC must be guaranteed. Nominal values of the material properties can be determined by performing a 3-point bending test on a notched beam according to EN14651 (figure 1) or by performing the ASTM C1609 beam test:"

Jan 1, 2016

By Jun Yuan

Kaolin clays from five different commercial deposits in Georgia were studied to understand the variations of zeta potential and related fundamental properties. The results suggest that higher negative zeta potential is related to exchangeable or soluble calcium ions in the clays.

Jan 1, 1997

By Warren D. MacEvoy

INTRODUCTION Good ventilation bulkheads (stoppings) can be obtained only by conscientiously adhering to four basic principles: carefully selecting the site for the bulkhead, adequately preparing the site, properly constructing and sealing the bulkhead, and checking the results with a smoke tube before leaving the area. If all these guidelines are followed during each ventilation project, a poor job will result only from the use of improper materials and cannot be blamed on carelessness or oversight. SITE SELECTION A perfectly constructed bulkhead in the wrong location can be completely worthless. Conceivably, a bulk-head in the wrong location could cause dangerous ventilation conditions that are difficult to identify and isolate. If the suggestions herein are followed, a considerable amount of work, time, and material may be saved. Perhaps the single most important step is always to select the exact site for a bulkhead before starting construction. Although the latitude in selecting a site may be limited by instructions or operating conditions, it is common to find poor bulkheads built within a few meters (feet) of a site that would have been far superior but was overlooked during the planning process. The ideal site for a bulkhead should have as many of the following features and conditions as possible: 1) To provide a solid bulkhead, the selected site should be in firm and unbroken ground. 2) To minimize the amount of work and material required and to minimize the danger of later damage to the bulkhead, the site should have as small a cross section as possible. 3) The bulkhead site should not be encumbered by interferences such as pipes, wires, ditches, wire roof supports, trash, muck piles, etc. 4) The walls and timbers of the site should be free from oil, grease, or tar that would inhibit adhesion of the sealant used on the bulkhead. 5) Unless special precautions are taken, the site should not have water seepage, standing water on the floor, or water-carrying ditches. 6) To expedite construction of the bulkhead, the site should have reasonable access to transportation, supplies, communication facilities, and compressed-air lines. 7) The site should have a reasonably level floor, allowing direction of the bulkhead door swing to be reversed at a later time if so desired. In a steeply sloping location, it may be possible to open the door in one direction only. SITE PREPARATION Once a suitable site has been selected for the bulk¬head, it must be prepared properly. All site preparation work should be completed before starting any construction work on the stopping itself. Unfavorable site conditions can be identified during the course of thepreliminary site preparation, saving time, effort, and materials that otherwise might be wasted. The follow¬ing preparation steps help assure the construction of a good stopping: 1) If wire mesh has been used at the site, a strip 457 mm (18 in.) wide should be cut and removed from the walls and roof at the selected location. 2) The exposed strip of rock should be barred down thoroughly to provide a smooth surface. 3) All obstructing materials should be removed, including old timbers, pipes, rockbolts, wires, etc. If a conduit must cross the bulkhead area, it should be located or relocated away from the floor, walls, and roof to allow a 6.28-rad (360°) seal around the juncture between the conduit and the bulkhead structure. 4) All loose muck should be cleaned from the site and a trench about 152 mm (6 in.) deep should be dug from wall to wall in the floor. The trench must be wide enough to accommodate the entire bulkhead, including the posts. 5) The rock surfaces of the walls and roof should be cleaned with a wire brush to remove as much loose surface material as possible. Thorough cleaning promotes adhesion of the bulkhead sealant to the surfaces of the walls and roof, thus promoting an airtight seal. 6) It is quite difficult to seal landing mats that cross a bulkhead. If such a crossing cannot be avoided, the bulkhead should be placed between the end and the first hole in the steel so at least one side of the bulk-head can be sealed easily and completely. That may have to be done prior to actual construction if the end is located on the opposite face from the seal coating of the bulkhead. BULKHEAD CONSTRUCTION The three principal considerations in bulkhead con¬struction are the type of bulkhead, materials to be used, and construction method to be employed. For many projects, the bulkheads are specified by the requesting agency, with no latitude for independent choice of the type, materials, or construction method. In such cases, any deviations from the specifications, for any reason, must be approved in advance by the proper department or by the project senior ventilation engineer. Types and Materials When a choice of type, materials, or method is allowed, consideration should be given to factors such as cost, required useful life, proximity to blasting concus¬sions, availability of materials, direction of permissible air leakage, and degree of airtightness required. Other factors to be considered include the amount of time available, accessibility of transportation, potential for interference with operations or production, ambient water conditions, availability of connections to com¬pressed-air lines, etc. Despite the multitude of factors to be considered, most stoppings can be analyzed easily and the proper choices can be made without much difficulty. The four common classes of bulkheads utilized in

Jan 1, 1982

By Greg Watson, Dennis Ofiara

"TBMs have been used in mining in decades past, but their use has been limited and sporadic, due to both perceived and actual application difficulties. With new technology and mounting success stories, this is changing. For both coal and metals mining, deep ore bodies require long access tunnels, and an efficient and economical method of reaching those deposits. Today, mining engineers are considering TBMs as part of the overall mine development plan. Planned TBM mine drifts are not only longer, but have more complicated trajectories. Mine development TBMs will have to cope with varying geology, potential for high water inflows, steep gradients, and high temperatures. TBM systems are being planned to cope with such difficulties. TBM systems will be considered and increasingly deployed for mine development, even if commodity prices remain low. TBMs can satisfy the need for increased productivity, better life of mine infrastructure, and safety. Effective conveyor systems are essential to support TBM operation in many mining applications. Many mine development tunnels are slopes, driven down at the steepest practical gradient to reach the deep ore body. Conveyors are often the only safe and effective way to haul the TBM muck form such tunnels. This paper will review the historical use of TBMs in mining, and will discuss the 2015 status of TBMs and conveyor systems in mining, and the special requirements and adaptable features needed in order to make efficient TBMs a reality in mines worldwide.HISTORICAL USE OF TBMS IN MINING APPLICATIONS The first successful hard rock TBM was invented in 1954. Over the next decades, TBMs have been used in many mining applications: Mine access drifts in several Spanish mines •,White Pine Copper Mine, USA •,Selby Coal mine drift, UK •,Coal slopes in Appalachia, USA •,German coal mines accdess drifts, several mines •,Magma Copper San Manuel, USA •,Cape Bretton Undersea Coal Slopes, Canada •,Stillwater Mines, USA"

Jan 1, 2016

By Daniel Hodouin

Artificial neural networks (ANN) are of growing interest in a wide variety of applications. Pattern recognition, speech processing, financial analysis, signal processing and process control are at present the most successful ones. This paper is an attempt to illustrate the potentiality of ANN applied to mineral processing. An introduction to the technology of ANN is first proposed to describe the various components and to explain the various phases encountered in setting up a network. Then examples are given to illustrate the use of ANN dynamic modelling of mineral processing units or plants and in process control.

Jan 1, 1991