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By Rob Robertson

The problem of fine coal slimes has been addressed in a unique way at A. T. Massey Coal?Company. Several plants have employed two-stage classifying cyclones to separate the minus 1 mm raw coal into 3 sizes. Larger cyclones make the initial cut at approximately 150 µ (100?mesh) sending the underflow to a cleaning circuit (usually spirals) while the overflow is pumped to a secondary cyclone circuit using smaller cyclones. The small cyclones make a cut at near 70 µ (200 mesh) and produce an underflow that is a des limed flotation feed. The overflow is discarded to refuse due to its high ash and superfine size which would produce a high moisture product even if suitably recovered.

Jan 1, 1998

By M. Bunch

Today?s mine operating managers face an incredible challenge of meeting the forever increasing legal and regulatory requirements for mining projects. Managers know that meeting compliance of these requirements is just a starting point of assuring sustainability for the project. So how do today?s managers meet these requirements while at the same time focus on continuous improvement in Health & Safety, Environmental, Costs & Production, Labor Relations, Social Corporate Responsibility, and Quality? This paper outlines means by which managers can take control of their operation through the implementation of an integrated Business Management System (BMS) and lay the foundation of a continuous improvement culture in their organization.

Jan 1, 2010

By K. A. Heasley

The objective of this paper is to back analyze the August 6th, 2007, collapse at the Crandall Canyon Mine in Utah, in order to better understand the geometric and geomechanical factors that contributed to that collapse. In this work, the LaModel boundary-element program, along with the best available information, is used for the back analysis. To initiate the analysis, a six-step base model of the mining in the Main West area was developed. This base model included a step for each of the critical stages in the mining of this area. Next, calibrated values for the critical input parameters, rock mass stiffness, gob stiffness and coal strength, were developed and optimized based on the best available information. Finally, the model was used to simulate the final mining scenario. As a result of this back analysis, a number of conclusions can be made concerning the mine design and the August 6th collapse: 1) overall, the area was primed for a massive pillar collapse because of the large area of equal-size pillars, 2) the abutment stress from the active retreat sections and the adjacent longwall panels were significant contributors to the collapse and 3) from the modeling alone, it is not clear exactly what triggered the August collapse, although the active mining is a reasonable assumption.

Jan 1, 2010

By D. E. Traut

A fluidized countercurrent ion-exchange system was developed, operated, and evaluated by the Bureau of Mines. The system consisted of integrated multiple-compartment absorption and elution columns in which the solution flows are continuous except for short periods when resin increments are withdrawn. The exchange of uranyl sulfate between a simulated acid leach uranium solution and a strong-base, ion-exchange resin together with the subsequent elution with an acidified sodium chloride solution was studied. The effects of the number of sections, section heights, amount of resin withdrawal, and solution flow rates were investigated. Also examined were the kinetic and equilibrium relationships for the absorption step. The experimental data indicate a strong interdependence between variables. Solution retention time appears to be a major limiting variable. The column was efficient over a range of conditions, but close control was needed for optimum operation.

Jan 1, 1975

By D. Corrigan, A. Ahmad, R. Sood, J. Bratt, R. Holt

Zinc oxide based electronic ceramics are being used increasingly to protect electric and electronic circuits against transient voltage surges. Varistors are produced by sintering and annealing ZnO based powder compacts through long sintering and annealing cycles. Because of the length of these cycles, a manufacturing plant is saddled with expensive high temperature equipment with low throughput. Ceramics Kingston Inc. has developed a new technology that uses 2.45 GHz microwave energy for sintering and annealing. The new technology has the potential for increasing equipment and labour productivity very considerably. Additionally, the new technology will result in appreciable energy savings and add flexibility to the manufacturing process. Microstructural examination of varistors sintered conventionally and by microwave technology showed considerably smaller grain size in the microwave sintered materials. The electrical properties of the microwave sintered ceramics compare very favorably with those of the ones sintered conventionally.

Jan 1, 1990

Sewage sludge contains heavy metals, pathogens and bears annoying characteristics that limit its land application. For the sewage to be applicable on land, several stabilization methods can be used. Stabilization with lime (CaO) is used to raise pH and temperature and therefore, according to ASTM standards, reduce pathogen levels and achieve compliance with regulatory requirements. Although the process results in the production of a stabilized material, its direct application to soils is rather limited mainly due to the improper product texture. Inert materials can be further added to sewage sludge stabilized with lime to tackle this problem. The objective of this study is to investigate the potential use of dried bauxite residues as an inert material together with lime for the stabilization of sewage sludge from a municipal water treatment plant. It was indicated that the addition of bauxite residues and lime to sewage sludge apart from meeting the requirements of ASTM standards, it further reduces moisture content, improves material texture and eliminates odors. It was also found that although some elements leachability increased due to the treatment with lime, it further decreased when bauxite residues were also added.

Jan 1, 2006

By Jerry M. Whiting, Samuel Frimpong

Superior ventures selection and the subsequent management of their development and production are crucial in the competitive environment of the upstream minerals and energy industry. An important element of this chain is the management of uncertainty and risk dynamics. In the world of faster and more complicated technological and environmental changes, international competition and commodity market dynamics, thorough and sophisticated valuation must be carried out to establish a venture's value and return on investment. Thus, managers and investors must use methods that respond to market dynamics, investment and feasibility study options and provide relevant information for strategic investment decisions. Conventional methods have no built-in procedures to help investors analyse these options. Modern financial methods based on the dynamic arbitrage theory overcome these and other limitations of conventional methods. In this study, dynamic arbitrage theory has been used to formulate 3D parabolic differential equations that govern the stochastic processes of a copper mining venture with ongoing feasibility studies. The alternate direction implicit algorithm is used to solve the numerical approximations of the differential equations and their boundary conditions. Phase dynamics of the venture have been analysed to provide investors the appropriate timing for strategic investment decisions. The study also shows the amount and value of appropriate feasibility studies required to maximize the value of the mining venture.

Jan 1, 1996

By C. E. Jordan

The U.S. Bureau of Mines investigated flotation hydrodynamics to improve the recovery of coarse phosphate. Fluid velocity profile measurements were used to characterize the hydrodynamics within commercial phosphate flotation cells and laboratory flotation cells. The effects of agitation, aeration, and pH on coarse phosphate recovery were measured in the laboratory flotation cells and correlated with the hydrodynamics measurements. Test results revealed that the agitation energy and aeration level had a significant effect upon flotation response. By optimizing these two parameters, 92 pct of the phosphate was recovered in a rougher flotation concentrate grading 28 pct P2O5?

Jan 1, 1994

By David M. Mchaina, Steve Hardcastle, Michel Grenier

An overview of the process employed to assess arsenic exposure levels at a gold mine is provided together with the recommended control measures. Arsenic and its compounds are regulated in Ontario as designated substances in all workplaces except mines and concentrators. There is a proposal to remove the exemption for mine and concentrators. If the exemption is removed, the mining industry will be required to adopt the proposed exposure Limit of 0.01 mg/m over 40 hours. There are many mines in Ontario which will be affected by this new regulation. To determine the extent of which workers are exposed to Levels exceeding 0.01 mg/m , an assessment program was initiated at the mine. The main objective of the program was to determine the effect of the proposed regulation on underground and surface operations in term of compliance if it becomes Law. The data obtained from the assessment program shared that only 1ML of the workplaces monitored for arsenic indicated levels above the proposed limit of 0.01 ,/yard all workplace levels were below the present Limit of 0.2 mg/m .

Jan 1, 1992

By E. M. Schern

The Morenci/Metcalf porphyry copper mining operation, located in southeastern Arizona, currently processes approximately 100,000 tons of ore per day and has copper ore reserves estimated to be in excess of one billion tons. Functional groups within the Geology Depart¬ment (currently staffed with six professional and two support personnel) include mine geology, project geology, and hydrogeology. The primary task of mine geologists is daily preblast bench face mapping with grade and mill amenability estimates. Auxiliary duties include detailed in-pit metal distribution evaluation, mineragraphic work and flux quarry geology. Project geologists conduct explora¬tion and preliminary development projects both within and outside the Morenci district and provide support to ore reserve block modeling and geotechnical work performed by the Morenci mine engineering group. Hydrogeologists handle exploration for and development of groundwater' resources and groundwater flow modeling, mine dump leach solution penetration and recovery evaluation, and tailing dam water reclamation.

Jan 1, 1983

By Walter Hoecker

The dissolution of gold in cyanide_ leaching has been we11 published with the genera1 acceptance that gold is oxidised by oxygen and stabilized by complexation with cyanide [1]. The dissolution of gold is essentially an electrochemical process. The rate of the anodic gold dissolution is controlled by the cyanide concentration. - (2) While the cathode reduction of oxygen is controlled by dissolved oxygen concentration - (3) There are a number of factors influencing the concentration of oxygen, and if 1owered substanth.lly will effect the efficiency of the leaching plant. These include: "' salinity "' temperature "'partial pressure "'oxygen consumption rate The use of pure oxygen for· cyanidation is only beneficial if oxygen is rate limiting, Conversely a slurry saturated with air (typically 5 - 8 ppm) may not be enough for maximum leach rate. The diagram below shows the maximum dissolved oxygen levels obtainable with pure oxygen and air. DISSOLVED OXYGEN (MAXIMUM) IN WATER At steady state, the rate of the cathodic reaction must equal the rate of the anodic reaction. Thus the rate of gold dissolution is dependent on both the· cyanide and oxygen concentrations. - (4) Using an average of Do/Den =· 1.5 [2] (where Do and Den are the oxygen and cyanide diffusion coefficients) the table below illustrates the maximum effective oxygen concentrations for given cyanide levels in clean water [3].

Jan 1, 1992

By Clyde N. Garman

The Homestake-New Mexico Partners consist of Homestake Mining Company of Lead, South Dakota; Rio de Ore Uranium Mines, Inc; United Western Minerals Company; White, Weld and Company; J.H. Whitney; San Jacinto Petroleum Corporation; and Clyde Osborn, Homestake Mining Company is the general partner, the others are limited partners. The Rio de Ore Uranium Mines, Inc. has. a mine in the Ambrosia Lake area; this was the first mine to go into production in this area. The United Western Minerals Company also has a mine in the Ambrosia Lake which is operated as a "farm out" from the San Jacinto Petroleum Corporation. These mines are the principal sources of ore for the mill. This group was the first to obtain a contract with AEC to make uranium concentrate from Ambrosia Lake ores and the first to have a mill in operation specifically for these ores. With Clyde Osborn as the sparkplug and co-ordinator holding the ore suppliers of, this group together, a contract with AEC was agreed on as to its essential points by mid-summer, 1956, At that time, there was no general partner and no financing, so me formal contract could be signed. By December, 1956 when the contract was signed and the present partnership officially formed, much of the basic engineering was done and purchasing of main elements of the mill waited on the formalizing of agreements, at the specifications and sizes agreed on previously. Ground for the mill was broken in April, 1957. The sampling plant went into operation in October and ore was first fed to the ball mills on February 5, 1958, ten months after construction actually started. Filling of the circuit with sodium carbonate bicarbonate solution had begun a week before that.

Jan 1, 1959

By Ehsan Alavi, Glen Frank, Michael DiPonio, Mike Mooney, Lisa Mori

"A study was conducted on the N125 project in Seattle to investigate the use of apparent density as an assessment tool for the effectiveness of soil conditioning. The formation of an air bubble as well as the plugging of cutterhead and excavation chamber can be a result of improper soil conditioning. Both air bubble formation at the top of the excavation chamber and developing plugging issues can be identified by analyzing the apparent densities in the excavation chamber. In this study, apparent densities less than unity were observed in the upper portion of both northbound and southbound TBMs, suggesting the presence of an air bubble. Apparent densities greater than the in-situ soil density were observed in the lower portion of the excavation chamber. Particularly high values of apparent density were coincident with clogging observed at multiple locations along the alignment. The combination of less than unity upper chamber apparent density and very high apparent density in the lower portion of the chamber are related, and indicate the inability of the TBM to effectively condition and mix the soil in the chamber.INTRODUCTIONProper soil conditioning in EPB tunneling offers many advantages to the quality and productivity of the project. There are few operational parameters that can be used to assess the soil conditioning performance such as advance rate, torque, thrust, chamber pressure signature, etc. One of the other parameters that potentially can be used is the apparent density. The apparent density of the material in the chamber was introduced by Guglielmetti et al. (2003) as the vertical chamber pressure gradient calculated from the physical relation between the horizontally measured chamber pressures and the vertical distance between the pressure sensors. Guglielmetti et al. (2003) introduced apparent density as a measure to ensure the excavation chamber is filled with material. To guarantee face stability the authors suggest to keep the apparent density over a certain limit so the material is able to transfer effective stress to the virgin soil, and thus provide support of the excavation face. They implemented this method at the Metro project in Porto, Portugal.Comparing the vertical gradient of the horizontal chamber pressures to the densities of excavation chamber samples, Bezuijen et al. (2005) discovered that the gradient is not necessarily representative of the muck density. They assumed that the yield stress of the muck as well as the adhesion between the muck and the cutterhead and bulkhead material have an influence on the vertical gradient during mining (Bezuijen et al. 2005, Bezuijen & Talmon 2014)."

Jan 1, 2016

By Dan Mackie

Since the production prototype continuous vat leaching pilot plant was installed at Ariel Resources in Costa Rica in 1995, the test results and lessons learned have been invaluable in plotting the future of this method. Vigorous test programs in base and precious metals as well as design developments for studies have shown the advantages, economically, technically, and environmentally that favor this method over current practices in heap leaching and stirred tank leaching. Much larger individual vats have been developed with throughputs as high as 5000 t/d with larger vats envisaged, and there has been a trend towards using vats with ground ore. Five projects are slated to begin detailed engineering this year, three in precious metals and two in copper. Of particular interest to future producers is the ability to deposit d,y, detoxified tailings at a fraction of the cost of conventional methods. Proprieta,y work is ongoing which promises to eliminate the need for tailings dams when using other methods of processing such as flotation. This is of particular importance in light of dam failures around the world in recent years.

Jan 1, 2000

By P. Eger

In 1991, LTV Steel Mining Company decided to close an open pit taconite mine in northeastern Minnesota, using a passive treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. Over 50 million metric tons of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages, and prior to closure annual median concentrations ranged from 1.5-50 mg/L. Copper, cobalt and zinc are also present but are generally less than 5% of the nickel values. Median pH ranges from 5.0 to 7.5, but most of the stockpile drainages have pH greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential a stockpile had to produce acid drainage, the lower the permeability of the capping material required. Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to over 90% for the plastic liner. Five constructed wetlands have been installed since 1992, and have removed 60-90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1 % of those for an active treatment plant. Since mine drainage problems can continue for over a hundred years, the lower annual operating costs should pay for the construction of the wetland treatment systems within seven years.

Jan 1, 1999

By B. J. Scheiner

The Federal Bureau of Mines has developed a chlorine-oxygen leaching technique for the recovery of metal values from lead-zinc sulfide concentrates. Lead, zinc, copper, cadmium, and silver extractions are in the 95- to 99.9-percent range. During leaching, the zinc, copper, cadmium, and silver are solubilized as metal chlorides, and lead is converted to insoluble lead sulfate. The iron contained in the concentrate is converted to insoluble iron oxide, and a majority of the sulfide is converted to elemental sulfur Minor metals such as copper, cadmium, and silver are recovered by precipitation with zinc dust. Zinc is then recovered from the purified zinc chloride solution by evaporation to dryness; the lead is recovered from the leach residue by brine leaching and crystallization to produce lead chloride. Recovery of zinc and lead metals by fused-salt electrolysis of the chlorides is being studied separately.

Jan 1, 1975

By D. D. Young

During the 1970's a number of covered storage facilities were constructed in North America to store and handle large quantities of bulk, solid materials. This trend, away from outdoor storage piles, will probably continue at a stronger pace in the 1980's. This paper attempts to answer some of the questions often raised about the economics of large covered storage facilities. The paper is in four parts: 1. Why Build a Storage Facility? 2. 2. Common Components of Storage Systems With Details of Six Storage Facilities 3. Results of a Study for 50,000 Mg Clinker Storage 4. Guidelines for Conducting a Study to Select a Storage System.

Jan 1, 1980

Development of computer-based information systems is predicated on the merger of rapidly developing computer technology and growing managerial demands for information. The focus of this section is on managing the development and implementation of information systems for the 1980's. It is the experience of the majority of contributors to this volume that among unresolved problems of major dimensions in a mineral organization are those of managing the computer-based information systems resource itself. There are three major reasons for this: (1) mineral information systems are relatively new to the senior management of a mining company or a mineral organization; (2) problems are compounded by a developing technology, a new type of personnel with a changing experience/education mix; and (3) an organizational structure and location which, in many organizations, are still being examined. The three authors in this section present aspects of managing the information systems function which, based on their experience, are common to the solution of the problem. The premise that the information systems function has been placed appropriately within the entire business plan of the firm has been made by the authors in their discussion of the various aspects of the management process.

Jan 1, 1979

By Ronald R. Hartman

I can recall a time 10 or 12 years ago when I spent a pleasant Sunday afternoon driving to Jim Thorpe, Pennsylvania to see a carnotite deposit that had recently been discovered. The announcement of the discovery stated that it was in the Pottsville conglomerate in a road cut along the highway. To my surprise, the highway was lined with cars and every weekend prospector for 100 miles had come to see the ?big uranium deposit of the east?. I literally had to stand in line to make a measurement with the scintillation counter I had with me. The thought at first occurred to me that this is evidence of how thoroughly the surface of the United States must have been prospected, more likely, perhaps it points out quite the opposite. A lot of time and energy was being spent in tracing the footsteps of others and a lot of time was spent looking for the obvious occurrences. The point is, that in the early days a tremendous amount of uranium exploration was carried out but few systematic surveys were made. Thorium anomalies were usually discounted after cursory surface field checks. Conversely, in airborne surveys - anomalies due to elevation changes or thin over- burden on hilltops were often investigated more thoroughly than smaller indications on hillsides and valleys. An adequate supply of uranium was nevertheless found due to the ingenuity and persistence of the geological profession and the public in general. This ?adequate? supply, like so many estimates for raw materials turned out to be far too low.

Jan 1, 1967

By D. C. Sisti

A paper was presented during the 1970 SME Fall Meeting on the Stinson Preparation Facilities by representatives of Beaver Creek Consolidated Cool Company and Heyl & Patterson, Inc. This paper summarized a combined approach to development of a flow diagram and selection of cleaning equipment required to produce a uniform metallurgical coal at maximum recovery with special emphasis on sulphur reduction. These facilities were located in the Elkhorn. Coal Fields of eastern Kentucky and, in particular, the area of Wayland, Knott County, Kentucky, where approximately forty-five- million tons of Elkhorn No. 3 coal could he recovered. The facilities incorporated a Bradford Breaker for reduction of the ROM coal to minus 1-1/2 x 0, 6000 ton-raw coal storage, preparation plant, water clarification and thermal drying facilities, clean coal storage and a 4000 TPH unit train loading facility.

Jan 1, 1973