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By S. K. Kawatra, R. A. Seitz

There is considerable variation in the types of coal flotation circuits in use in various parts of the world. For example, Russian plants frequently use scavenger flotation, while this is almost unheard of in the United States. The numerous circuit designs are intended to address specific problems in coal flotation, or to take advantage of the peculiarities of certain coal deposits. As a result, it can be difficult to decide which circuit is best for a given application. For this paper, coal flotation circuits were collected worldwide from many operating plants. These circuits include varying degrees of conditioning, and complexity ranging from simple rougher flotation to multi-stage split- stream processing. The design goals of each circuit are described, and the advantages and disadvantages of each are discussed. Extensive sampling campaigns were carried out in two plants with the most common types of coal flotation circuit (simple rougher, and rougher with deslimed feed). The performance of each plant was evaluated, and the benefits of more sophisticated processing in each case are described.

Jan 1, 1993

By Peter J. Tarkoy, Terence G. McCusker

INTRODUCTION The discovery of oil and gas reserves in the North American Arctic has led to substantial thought being given to their development. Systems adequate for exploration are not always, or even often, suitable for permanent installations. Combinations of offshore pipeline, drilling ships, platforms, sub-sea systems, sand islands and -ice island bases have been proposed. However, conditions in the Arctic are such that these methods may be difficult or impossible to implement. Problems exist with (1) the freezing of the Arctic Ocean surface for 9 - 10 months per year, (2) the movement of sea ice, (3) scouring of bottom sediments by ice islands and icebergs to great depths below the ocean bottom and (4) deep water channels. Any method which can avoid the problems associated with surface construction in these very adverse conditions merits detailed examination. One of the proposed solutions is to tunnel from a convenient or available access point to a point within the field, construct a chamber large enough to accommodate the drilling equipment and drill the development wells in a protected environment. Service and delivery lines would use the access tunnel and further tunnels and chambers would be constructed in a radiating pattern to develop the whole field. In order to determine the feasibility of underground construction in the North American Arctic, it is first necessary to understand the geologic and environmental factors which would affect such construction, to be knowledgeable concerning the problems and then to consider the techniques appropriate to the conditions which will be encountered, bearing in mind the need to minimize both con-

Jan 1, 1976

By Kostas Fytas

A computer package has been developed which is capable of evaluating alternative production schedules (long and short range) of an open pit mine once the ultimate pit limits have been defined. The model user can choose the best alternative according to cash flow considerations and the particular mining conditions. The package involves a combination of simulation for long range production scheduling and linear programming for short range scheduling. The simulation model based on an iterative technique, maximizes the profits within each long scheduling period (eg. year or sixth month period), and at the same time defers stripping as long as possible. A minimum exposed ore quantity is kept at the beginning of each mining period. The final long range schedule satisfies a set of constraints for each period, mainly ore quality and quantity constraints for ore and waste. An interactive smoothing procedure at the end of each period results in a schedule that is feasible in terms of mining practice. Finally a cash flow analysis model carries out cash flow calculations so that the user can select the best alternative. The linear programming model, based on a certain number of shovel regions, defined interactively by the model user, calculates the optimum production schedule for each short period under consideration, so that a set of constraints is satisfied.

Jan 1, 1986

By C. B. Manula

The total systems model for underground coal mine planning and design (Master Design Simulator) is a set of computer programs which encompasses a realistic reproduction of the interaction among the geological, environmental, equipment, methods, and the health and safety aspects of the mining plan (Manula, Rivell, and Ramani, 1975). The total system includes nine major subsystems: geology and reserves, methane generator, roof support, subsidence, production, rail haulage, cost, water generator, and ventilation (Fig. 1). The subsystems themselves are divided into two categories based on the frequency with which they are executed: (1) event-oriented subsystems are executed either independently or at discrete intervals when certain specific events occur; and (2) dynamic subsystems function interactively during the production cycle, transferring data to or requesting data from event-oriented subsystems only when specific events occur (Fig. 2). Each subsystem has been tested and validated independently (Ramani, White, and Sutton, 1974; Ramani and Owili-Eger, 1974; Manula, Mozumdar, and Jeng, 1974a; Manula, Mozumdar, and Jeng, 1974b; Manula, et al., 1974; Manula, Rivell, and Sanford, 1974; Ramani, McClay, and Burgos, 1975; Manula and Owili-Eger, 1975; and Ramani, Owili-Eger, and Manula, 1975).

Jan 1, 1979

By Barry Silverman

As a significant mineral supplier, consumer of primary fuels, and producer of wastes and emissions to air, water, and land, the domestic copper industry through its investment and operating decisions influences the nation's economy and the environment. In turn, the copper industries' decisions are influenced by various factors: government energy and environmental policies, economic conditions, and technological considerations. The authors have developed a framework for assessing in an integrated manner the impact of these factors on the future investment and operating decisions made by copper firms. Specifically, this model is designed to capture the technology forcing nature of regulatory constraints, the differential situation of individual copper deposits and plant locations, and the price of factor inputs and conditions in the nation's economy. The capability to do this has only become real because of the decision of the U.S. Bureau of Mines to create Mineral Availability system1 or MAS. This system contains detailed but confidential information about each mine and mill in each of 35 mineral industries." Without MAS or a similar information system, the utilization of the methodology we offer would be impractical, but with. MAS it offers a unique technique of dealing with environmental-resources policy questions.

Jan 1, 1979

By G. T. Adel, P. E. Richardson, R. Pazhianur

Cathodic protection using impressed current was employed to reduce mill wall wear during ball milling. Wear rates were determined from weight-loss measurements made on four 1-in.-diam mild steel coupons that were installed flush with the interior surface of the mill wall. Grinding tests were conducted on quartz, pyrite and quartz-pyrite mixtures at pH levels of 4.6, 7.1 and 9.2. Cathodic protection was shown to reduce mill wear by 30% to 60%. An examination of the coupon surfaces using scanning electron microscopy showed that cathodic protection greatly reduced pitting corrosion. The presence of a sulfide mineral, such as pyrite, was found to increase the wear rate significantly, possibly due to galvanic interactions. It was also found that the wear rate is significantly higher than the sum of abrasive wear and the corrosive wear, due to a synergistic effect.

Jan 1, 1998

By Kal V. S. Sastry

Modeling and simulation are two major tools available to a mineral process engineer for a consistent and systematic process analysis. The application of these tools to the analysis of specific mineral processing unit operations is well documented in the literature; nevertheless, they are used only to a limited extent in the industry. This is because the fundamental principles of modeling and simulation in the context of mineral processing context are not available. This paper represents the first in a series of papers planned to meet this need. General principles of process modeling and a unified mineral process model development methodology are presented. A simple example of model development using the flotation unit operation is given. A discussion of the practical significance, challenges and opportunities associated with mineral process modeling is included.

Jan 1, 1990

The National Mining Association’s (NMA)MINExpo International ’96 is shaping up to be the organization’s largest. About 30,000 mining industry business and technical professionals are expected to descend on Las Vegas, NV Sept. 9-12 to take part in the 25 technical sessions and visit the more than 900 exhibitors who will be showing off their products and services. MINExpo will be the largest mining equipment and services exposition in the United States this year. Exhibits at MINExpo will fill the Las Vegas Convention Center, parking lots and part of the Hilton Center, located next door to the convention center. NMA estimates that this year’s show will cover more than 46,450m2 (500,000 sq ft) of exhibit space. Some of the exhibits on display will include haultrucks, hydraulic shovels and excavators, conveyors, continuous miners and tunneling machines. In addition, an array of computer equipment and software will be demonstrated. A new feature this year will be a helicopter pavilion, located in the Hilton Center. Helicopters and fixed-wing aircraft have become indispensable to many remote mining operations. NMA said that at least one full-size helicopter will be on display.

Jan 1, 1996

By V. Russel Burkhart

One of the most difficult items to justify economically on any budget is a training program. The costs can easily be identified--primarily the cost of the program and the inconvenience and cost of filling in for the men taking the training by working other personnel extra hours at overtime rates. Operating efficiency, higher productivity, increased plant availability, development of confidence, improvement in morale and less absenteeism are only a few of the benefits which far exceed the costs. A good preparation plant training program can accomplish more in 5 weeks than can be accomplished in five years of on-the-lob operation. During recent years, coal preparation plants have become more sophisticated and complex as the specification for coal used by electric utilities in their power plants have required improvements in coal quality to adhere to air quality regulations and to improve boiler performance and reliability.

Jan 1, 1981

By K. J. Bruxvoort

Background ground water quality is often used to drive remediation programs at sites with waters affected by mining activities. In the past these levels were sometimes chosen without rigorous statistical and geochemical analysis. A probability distribution approach was used at the Sweetwater Uranium Project to separate a large set of geochemical data into populations that represent contributions from different sources. Natural background populations were identified for major ions, metals, and radionuclides, and were submitted to the Nuclear Regulatory Commission to modify the extent of a Corrective Action Program and to establish control limits for future monitoring.

Jan 1, 1998

By John T. Atkins

Utah International's Shirley Basin Mine is located in the Southeastern High Plains of Wyoming at an elevation of about 7,100 feet. The Shirley Basin area is a gently rolling semi-arid land. The uranium ore zone occurs at depths ranging from 270 to 350 feet below the surface. Overburden consists of poorly consolidated sandstones, siltstones, and clays. Underground mining was begun in 1960. Conditions were made difficult by high rates of water inflow and ground support problems. The development of a solution mining I or in-situ leaching technique allowed underground operation to be abandoned in 1964. Solution mining provided limited production from 1963 to July 1970. In January, 1969, large scale development of open-pit mining was begun. A 1,200 ton per day mill went "on stream" in March, 1971.

Jan 1, 1973

By D. S. Dick

Over the last few years, new methods to characterize the flow properties of bulk solids have been developed. Abrasive wear and particle attrition can now be accurately measured in a laboratory and scaled up to field conditions. In addition, the effect of large particles on a material's flow properties (cohesive strength, bulk density, wall friction) can be determined as well as the effects of various additives such as Freeze Conditioning Agents. New developments have also taken place in terms of devices to improve the reliability of solids flow. Much attention has been paid to finding ways to provide a mass flow pattern with relatively shallow hopper walls through the use of inserts. Such devices can also provide reliable in-bin gravity blending of bulk solids and/or completely non-segregated discharge. Other developments have occurred in the area of belt-to-belt transfer chutes and sealing screws. Many of these developments have direct application in the mining and minerals processing industries. Examples of each will be highlighted.

Jan 1, 1988

By Steve Kral

The third edition of the Underground Construction Association of SME?s (UCA) Cut-ting Edge series of conferences focused on a challenge every underground construction and tunneling project faces: controlling ground water. The conference, held in New York City in November, is a partnership between the UCA and The North American Tunneling Journal. It featured more than 20 technical presentations by professionals from around the world. Each described specific challenges unique to their projects and the solutions employed. More than 175 professionals attended the two-day conference that included an exhibition featuring 17 companies. In addition to the technical program, the Cutting Edge conference featured a site visit to the $10.4 billion East Side Access Project. Sponsors of the meeting included Soil Freeze, Traylor Bros., Kiewit, Skanska, Moretrench, Aecom and The Robbins Co.

By M. D. Baker

Coal-water slurry preparation requires fine grinding and cleaning of coal by flotation. Finer grinding leads to increased ball wear and its effect on the surface properties of coal becomes of concern. Marked ball wear tests were performed to study the effects of oxygen, pH, the soluble species of coal and the addition of pyrrhotite on ball wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel balls during grinding. Electrochemical measurements on a mild steel electrode in coal slurries and SEM observations of grinding ball surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1989

By J. W. Jang

The wear behaviors of grinding media with different chemical compositions and microstructures in wet grinding of a quartz-pyrrhotite mixture was investigated under various environments. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of martensite and ferrite within the same ball. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment, while balls composed of both soft ferrite together with hard martensite exhibited decreased wear due presumably to the difference in their passivation? behaviors. The galvanic interactions between the two phases as well as among these phases and an electroactive mineral were investigated through electrochemical measurements under abrasive conditions in a slurry. The rates of formation of passive films controlled the corrosion currents of the high chromium steel media. Corrosive wear and its effect on flotation are discussed using the passivation kinetics model thereby developed.

Jan 1, 1989

By Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jennica L. Bellanca

Accidents involving powered haulage and mobile equipment like haul trucks are a major safety concern in the U.S. mining industry. They account for more than 50 percent of surface mine fatalities each year [1]. A recent National Institute for Occupational Safety and Health (NIOSH) analysis of 91 fatal incidents identified loss of vehicle control and situational awareness as key contributors [2]. However, the first-hand perspectives of operators are often missing, emphasizing the need for deeper insights into operators’ decisionmaking, lessons learned, sensory cues and mental strategies used during near-miss events. The findings in this analysis will help inform the development of training and safety solutions to prevent or reduce haul truck accidents.

May 1, 2025

By Michel L. Bilodeau

Mineral exploration is a sequential information gathering process. Primary exploration programs filter favorable areas through a series of geological, geochemical, and geophysical tests resulting in the discovery of mineral occurrences. The most favorable of these discoveries provides economic justification for a delineation drilling program. The purpose of delineation drilling is to provide information for estimating relevant physical characteristics of the mineral occurrence. These estimates are used to evaluate the exploration project and, eventually, the economics of mine development. Delineation drilling normally completes the exploration process. If the assessed economic characteristics of the delineated occurrence provide justification for mine development and production, an economic mineral deposit is the end result of the exploration process. Subsequently, a development drilling program is initiated to obtain the necessary data for detailed mine planning. The delineation drilling stage is in itself a sequential investment process. As delineation information accumulates, the reliability of geological estimates is improved and, thus, the uncertainty associated with the assessment of profitability criteria is reduced. Delineation drilling should continue as long as the marginal benefits, which result from improving the reliability of profitability criteria, exceed the marginal costs associated with the additional drilling.

Jan 1, 1979

By G. Triantafillou

The aim of this paper is to present the progress of the plan of the Greek Public Power Corporation S.A. (PPC S.A.) at the Lignite Centre of Megalopolis in Peloponnesus (southern Greece) to manage impacts on local communities in areas affected by its activities during the lignite mining operation and post-closure. The reclamation works in the waste dump areas of the mines that constitute the Megalopolis Lignite Centre, concerning the utilization of waste dumps for infrastructure community projects constructions are discussed. Moreover, selected environmental indicators concerning land use and closure and rehabilitation are presented.

Jan 1, 2008

Stratabound uranium deposits consist generally of two comingled geologic and statistical populations. Barren zones, usually having radiometric assays too low for recording on digitized logs, comprise a large portion of a mineralized stratum. In between are mineralized zones; where the grades are distributed essentially lognormally. Estimation of open-pit ore reserves requires the prediction of the tonnages of selective mining units (the smallest mined volume which may be segregated as ore or waste) and their grades within panels of convenient size for open pit planning and economic analysis. The proportionate tonnage of mineralized selective mining units within each panel can be predicted by kriging an an indicator function assigned to each composite (1 if mineralized, 0 if barren). Next, using logarithms of mineralized assays, the conditional lognormal distribution of grades of mineralized selective mining units can be found. Using this distribution and the krigedestimate of the probability a selective mining unit is mineralized, the grade and tonnage of selective- mining units above any cutoff can be predicted. A case study illustrating this two- step procedure is presented for the Imouraren uranium deposit located in the Republic of Niger. Using cross validation, the estimation procedures were checked and were shown to be adequately accurate for mine planning purposes.

Jan 1, 1979

By Byron V. Knelson

Although the concept of centrifugal recovery has been around in one form or another for many years, it has not been until recent times that it has become clearly understood and properly put into perspective. Simplistic in theory, it is when one begins to examine the variables involved that the true complexities of this matter begin to emerge. In creating an enhanced g force concentrator, there are many aspects both positive and negative that are encountered. Many conditions that are inherent to all conventional 1 g concentrators do not apply to centrifugal concentrators and therefore very few cm factors exist between them. In developing this technology, virtually all principles were proven by method of trial and error. Among the topics discussed are the effect of g force enhancement on particulate behavior with respect to size and shape, density, enrichment, fluidization, and the "teeter principle". In addition, we will discuss the physical effects of g force enhancement with respect to manufacturing in the areas of abrasion, bearings, and vibration. In discussing the recovery parameters of centrifugal concentrators we will draw direct comparisons to various other recovery methods, outlining the conditions most favorable to their application.

Jan 1, 1988