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By D. Randall Crooke, Ron R. Jorgenson

Many coal combustion products (CCPs) have historically been unsuitable for placement as mine backfill because of their physical and geochemical properties and/or regulatory status. However, innovations in paste production and transport of CCPs utilizing the high, fine particle contents of these fine-grained waste materials and their water retention colloidal properties produce a non-segregating, self-cementing material that may be environmentally suitable for placement as mine backfill. Both industry and the regulatory agencies are enthused by the possible cost reductions, both in design and construction of disposal sites, and the reduced environmental impacts of CCP realized by implementation of this new use/disposal technology.

Jan 1, 2001

By Robert Moore Lewis

Extensive exploration is being undertaken throughout the world in search for heavy minerals, particularly rutile and other titanium minerals. The federal government is sponsoring research involving rutile ores and recovery of stockpile-grade concentrates from domestic sources. Producers are being forced to turn to deposits with a heavy mineral content as low as 0.50% (essentially rutile and zircon). The North Carolina State University Minerals Research Laboratory investigated the possibilities of recovering heavy minerals from the amine tailings of the Texasgulf Inc.'s phosphate plant at Aurora, North Carolina. One laboratory beneficiation procedure using gravity, electrostatic and magnetic processes, resulted in the recovery of 78.7% of the heavy minerals in the amine tailings. Based on this percentage recovery and the present rate of phosphate mining, approximately 13,000 tons per year of heavy minerals (principally ilmenite and zircon) with a potential value of approximately $1,045,000 (1977) could be recovered. The economic potential for recovery of these heavy minerals appears to be favorable. A flotation procedure for up-grading the heavy minerals content in the amine tailings has been developed at the Laboratory, which could allow for concentration of heavy minerals and storing them in tailings area other than main tailings for future processing.

Jan 1, 1978

By R. L. Guerguerian

Hydrostatic trunnion bearings were recently provided on large Semi-Autogenous Grinding (SAG) mills driven by wraparound motors assembled on the head to shell flanges. A conventional SAG mill would have a ring gear driven through one or two pinions. The effects of the magnetic air gap forces from this new SAG mill drive arrangement on the performance of the bearing are discussed. A step-by-step systematic analytical de-sign of the hydrostatic trunnion bearing is presented, followed by a discussion of grinding mill erection requirements to conform with the design. A brief comparison with other bearing types and their response to the effects of magnetic air gap forces are also presented.

Jan 1, 1992

By Michael A. Trevits

A mine fire represents one of the most dangerous and challenging safety issues facing underground mine operators. Given the right circumstances, a mine fire can occur at any location in the active or abandoned mine workings, can quickly grow beyond control, and threaten the welfare and livelihood of the entire underground workforce. The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), has been conducting an in-depth program of research addressing mine fire prevention, early and reliable fire detection, and mine fire suppression technologies. One portion of this program is focused on understanding the characteristics of mine fire combustion products and flame spread through large scale deep-seated (firmly established) fire tests and use of computational fluid dynamics (CFD) modeling. In this study, two deep-seated fire tests were conducted; one fire consisted of coal material and the other utilized the two most abundant fuel sources found in a coal mine: coal and wooden cribbing blocks. The fires were burned to completion while the combustion products were collected and analyzed. In addition, an array of thermocouples was placed within the body of the material to measure flame spread rate. The coal fire test information was then used to develop a CFD model of the fire. This paper describes the fire tests, provides insight into characteristics of flame spread, and presents the CFD modeling work results.

Jan 1, 2009

By B. H. Kim

The use of a 25.4 mm diameter water-only hydrocyclone for separating fine-size (-150 µm), high-density (>4.5 g/cc) particles from similar-size, lower-density (2.65 glee) particles was investigated. It was found that a single-stage separation recovered nearly 90% of the heavy minerals (7.0 g/cc), while achieving a volume reduction of about 70%. The use of dense medium in a single stage improved volume reductions to 90% at similar heavy mineral recoveries. In addition, computer simulations of a three-stage circuit were performed, which showed that recoveries approaching 97% with volume reductions of 95% were possible.

Jan 1, 1998

By P. T. Luckie

Analysis of classifier performance independently of a closed grinding circuit configuration may result in a poor match-up between the grinding device and the classifying device. This paper examines the relationship between classifier and grinding device in dry grinding circuits by employing a semi-empirical methodology.

Jan 1, 1980

By Nathaniel Wollman

About nine years ago the President's Materials Policy Co commission under the chairmanship of William Paley released its report entitled "Resources for Freedom." Not long ago the Senate Select Committee on National Water Resources under the chairmanship of Senator Kerr released a study entitled Water Supply and Demand. Both reports contained projections of future water user the report for 1975, and the Select Committee print for 1980 and 2000, It is my task to compare the two reports. In the initial letter from Mr. Kazmann arranging for thus session he suggested that I present "a critical evaluation of the Paley Report's section on water ?ten years later,? which might include a comparison of predicted and actual water-use rates and would spotlight the assumptions which lead to errors in the predictions , . ." It is possible to compare the results of both studies, and it possible to explain art of the differences that can be found between them. The remainder must remain shrouded in doubt, since the Paley Report did not give all details of the methods used in estimating the com¬ponents of water use.

Jan 1, 1961

By G. Bourque

Early in the design stage of their new concentrator for the Mount Wright Plant, Quebec Cartier Mining decided to use a process computer for total control of crushing, grinding and concentrating. A map of the area is given in figure 1 and a view of the plant in figure 2. Although the use of process computers is not a new idea in petrochemical and chemical industries, their use in the mining industry is very limited. We innovated in using the computer, not only for data logging, as we have seen in some other plants, but a sole operator located in the administration building, starts and stops mill lines, crushers, load-out system, tailings, thickeners, etc ... by means of a CRT console. Our process is fairly simple as can be seen on the schematic process flow diagram (figure 3). .The ore, carried by 136t diesel electric trucks, is dumped through ore pockets onto two primary pan feeders. The feeders supply two 1,52mx2,79m gyratory crushers which reduce the ore to minus 20,32 cm. Each crushing line have a capacity of 5600t per hour and feed a shuttle conveyor distributing the crude ore into six silos.

Jan 1, 1979

By A. W. Storm

Vertical shaft furnace design and operation have their roots deep in antiquity. There is substantial evidence to indicate that iron was reduced from its oxides to serve mankind's needs long before recorded civilization - - actually prior to 3500 B .C. For at least 5500 years man has been matching wits with Nature to find better methods of extracting this most common, yet essential, metal from her, grasp. And, during nearly all of this period, the vertical shaft furnace has played a principle role in this dramatic struggle.

Jan 1, 1962

By B. C. Lewis

The mining industry has experienced a general trend toward an increasing number of longwall operations, an increasing percentage of underground coal being mined by longwalls, and increasing productivity from the longwalls. Longwall operators have not yet reached a state of mining euphoria. Competitiveness both within the industry and from alternate fuel sources is forcing continued pursuit of higher productivities and lower costs. The following graphics present trends in the industry. Longwall mines, as defined for this presentation, are those reportedly having longwall installations in each of the respective years. Production from both the continuous miner and longwall units is included in the longwall mines. Non-Longwall mines are all other underground mines. Productivity calculations are based on total employee-hours associated with the operation.

Jan 1, 1990

By Norman L. Weiss

The full importance of tailings disposal is yet to be realized by the mining industry, but our awareness of its present and future implications is growing faster, perhaps, than any single phase of ore processing. Few engineers can look very far into the future because of the complexity of the problems that may confront us if we project from the general indifference of past years through what we are already being expected to correct in existing operations, to confrontations with new statutes and an awakened public in any new plants hence- forth. The mistakes of the past have not been limited to the United States nor even to other countries of the Western Hemisphere. Indeed, all continents and subcontinents have suffered from myopia in releasing the tailings without retaining responsibility. However, the US as one of the world's great leaders in technology has a particularly unimpressive record. It may be safely generalized that the degree of control applied to the tailings of a milling operation has depended upon several factors more important than national boundaries. Thus in arid and semiarid climates no incentive was needed other than the scarcity of water to create a permanent and stable lodgment for mill tailings. On the other hand. where water has been plentiful. the temptation to let the tailings run into a river or lake or ocean (at least at certain times of the year) was often irresistible. So we find that modem tailings disposal in the southwest deserts of this country, with one or two notable exceptions where very serious breaks seem to occur at regular intervals, is satisfactory according to the standards of the 195QF and 1960s. while in various operations in Idaho, Michigan, western Colorado. Newfoundland, and elsewhere the record has been less praiseworthy. In the same way, cyanide plants which did not concern themselves about leakage, seepage, spillage, or wastage of tailings pulps with solutions containing toxic levels of free or combined cyanide soon heard a demand for better control. In consequence the industry has seen a growing use of cyanide regeneration of tailings or wash solutions, elimination of leakage, and careful structuring of tailing dams. The chemical and thermal qualities of tailing waters have occasionally been a spur to good tailings management. Some tailings disposal problems for example, the southeastern Florida phosphate clays and the Bayer red muds-have been given the intensive study they merited, but not always with much success.

Jan 1, 1985

By Mark E. Gershon

A mixed-integer formulation of the mine scheduling problem is discussed and applied for the purpose of optimizing both the mine production sequencing and the mill blending and processing problems simultaneously. Previous attempts at solving these problems separately, although successful, fail to take into account the interrelationships between these problems. Project structure serves as the outline of this paper, which is directed towards a mining engineering audience. Generalized in its organization, this concept is useful for long, intermediate and short range scheduling. Actual applications are mentioned which show that the concept is also applicable to mining a variety of ores.

Jan 1, 1982

By Pablo Hadzeriga

There are two places in the world where potash, trade name for potassium chloride, is economically recovered from naturally occuring brines by solar evaporation. One is at the Dead Sea and the other at Wendover, Utah. American Potash and Chemical at Trona, California recovers potash from natural brines, but uses fuel to accomplish evaporation. Under proper meteorological conditions the use of solar evaporation might be desirable from the economical standpoint. Of course, this may not be true when, if by artificial evaporation, a group of very valuable salts are recovered. This is the case of the American Potash operation at Trona. Solar evaporation has its limits. The working temperature is low. We may say, just to cover most areas of the world where solar evaporation may be practical, that it will take place between 18°C and perhaps around 45°C. In most cases the average working temperature expected will be around 25°C.

Jan 1, 1963

By Tristan Joubert, Fabio Panella, LiLing Chen, Yung Loo, Michael Devriendt, Nasir Qureshi, Ahmad Ali

Tunnel inspections have traditionally been carried out manually by inspectors writing up observations and taking photos of defects. The results from the inspection and the defects observed are dependent upon the rigor of the inspectors and may be subject to repeatability and consistency issues and is often time consuming with elevated health and safety risks. This paper will discuss work that is being carried out in developing and implementing an innovative hardware and software solution integrating machine learning to automate the process of capturing objective tunnel condition information, offering cost and programme savings as well as health and safety improvements

Jun 13, 2023

By Y. Jinnouchi

An air-pulsated jig has been widely adopted as a main coal washer. It may be mainly because of its many technical and economic features such as large capacity, low running cost, long life, etc. However, the recent increasing demand of fuel coal requires a higher productivity and efficiency of the air-pulsated jig. To fill this requirement theoretical and experimental investigations have been conducted on model and practical jigs in Japan. This paper generalizes the results of these investigations. In jig operation it is essentially of the most importance to create efficiently the pulsation of the water best suited for coal washing. The optimum pulsation should be determined by the theory of jigging process, and the method to realize it by that of pulsating mechanism.

Jan 1, 1982

By A. Khan

The effect of sulfur dioxide on collectorless and collector induced flotation of chalcopyrite was studied by cyclic voltammetry on a rotating disc electrode. Contact angle measurements were made to determine the effect of sulfur dioxide concentration and electrochemical treatment. The benefits of sulfur dioxide in enhancing the selectivity of separating chalcopyrite from complex sulfide ores are discussed.

Jan 1, 1996

By Paul Lenchuk

The concrete block industry can trace its beginnings to the early 18th century when most of the experimental work was being carried out in England. In America, the concrete masonry industry got started shortly after the Civil War and has had sometimes a spectacular, but always a steady growth since then. From a few hundred thousand concrete masonry units made in the late 19th century, the industry today produces approximately 3.3 billion concrete masonry units making it the largest industry in the United States for masonry wall materials. There were 3500 concrete masonry plants manufacturing these units after World War II. This nwnber decreased to 1500 by 1970 although the production of concrete masonry units increased by over 100% in the last 25 years. One of the reasons for this increase in production by less than half of the plants which once existed, is the tremendous strides made in automation of production machinery. The concrete masonry plant of today is probably one of the most automated small businesses in existence. Within a few years it will be possible to push a button and the entire manufacturing process will begin with no human hands touching the units until they are laid up in a wall at the manufacturing plant and are trans-ported to the job site. No other concrete product has reached this state of manufacturing sophistication and it is one of the reasons why the price of a concrete masonry unit is not much different than it was 2S years ago. Because of automation, it is safe to say that concrete masonry will remain a highly competitive building material for many years to come. The problems that beset the continued use of this material are not related to the cost of manufacturing and delivering the product. What are some of the problems as well as some of the opportunities and is the golden age of opportunity knocking rather than a wolf in disguise? The use of concrete masonry has grown each year because a larger unit was provided at less cost than other competitive materials. Concrete masonry has had severe competition from the clay products industry as well as masons who laid the product in the wall and who resisted concrete masonry for many years. Even today

Jan 1, 1971

By M. J. Zdunczyk

The final 1995 figures on industrial sand and gravel have not yet been compiled by the US Geological Survey (USGS). There is usually about a nine-month lag time in receiving and compiling this information. However, USGS estimates that domestic production of industrial sand and gravel will increase about 4% to 28.2 Mt(31 million st). The average unit price is expected to increase as well. The top five producers during 1995 were Unimin, US Silica, Fairmount Minerals, Oglebay Norton and Morie Co. Glass manufacturing for containers, automobiles and buildings was mixed during 1995. Containers, the largest consumer of silica sand, remained steady, with regional increases. However, silica use in glass containers face increased competition from plastic and recycled glass (cullet). It was reported that the Pepsi Cola announced plans to replace glass containers with plastic during 1996.

Jan 1, 1996

By J. E. Dreier, R. E. Scheffel, A. Guzman

"This paper outlines a comprehensive, cost-effective testing program for the acid-ferric sulfate heap leaching of oxide, supergene and primary copper ores. It is based on extensive experience in copper heap leaching and uses the many technological advances in the field developed over the past several decades. The approach described requires firstly a detailed resource evaluation, then a hydrodynamic characterization of representative samples and, finally, a focused metallurgical testing program. The principles communicated here can be applied to other acid leachable minerals. The program varies considerably from conventional testing in its disciplined, orderly, step-by-step approach, its application of hydrological and chemical principles to leaching, and its reliance on fewer, more tightly controlled column tests. The purpose of the test program is to optimize the financial, time and other resources devoted to the program, while minimizing the financial risks to the development company or companies and the project funding providers. IntroductionThe major goal of any process development testing program should be the successful implementation of the project. With respect to heap leaching, the metallurgical testing program plays a critical role in the larger objective, as described in Scheffel (2013, 2014). McNulty’s series of papers (1998, 2004, 2014) confirm that the success of any project is directly proportional to the extent and quality of the testing program on which the process is designed.Therefore, a key development objective is to conduct a well-focused metallurgical test program. While the primary focus of this paper is copper, the acid leaching of any substance would benefit from a similar approach.This paper addresses primarily the sulfate system, which is compatible with the bioleaching of sulfide minerals. Nicol et al. (2011) described the advantages of the chloride leaching of copper sulfide minerals. United States patents Nos. US 2009/0173188 A1, US 8,597,933 B2 and US2015/0232963 A1, assigned to BHP Chile Inc. and BHP Billiton S.A. Ltd, describe methods for both the oxidative and nonoxidative leaching of primary and secondary copper sulfides. Reyes (2013) and Ipinza and Flaquer (2014) described commercial applications of chloride-based heap leaching. The testing disciplines discussed in this paper will also apply to the development of an acidic chloride leaching system."

Jan 1, 2016

By James P. Dorian, James M. Otto

The value of exported nonenergy minerals from the less-developed countries has increased substantially between 1970 and 1985, but their market share relative to world exports has remained stagnant. Of the top twenty minerals exporters, only four are developing countries. Production capacity in the developing countries is shown to be less sensitive to demand downturns than capacity in the developed countries. Two approaches to the management of cyclical minerals demand are given using examples from India and Papua New Guinea. The authors conclude that pro¬tective policies implemented by developing nations have, barring a few exceptions, relatively little impact on the chronic nonfuel minerals oversupply problem.

Jan 1, 1989