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By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By G. D. Hood, B. E. Davis

A problem that has continued to plague the Florida phosphate industry is loss of coarse phosphate in the flotation circuit. Attempts to remedy this problem such as floating the coarse material (plus 425 µm) in a separate circuit have resulted in limited success, but recovery is still not optimum. A fundamental examination of the mechanisms involved in the conditioning of the coarse phosphate has led to results that seem to supersede common paradigms. The Bureau of Mines investigated conditioning parameters such as fatty acid/fuel oil dosage, residual clay content in the feed, conditioning time, mixing intensity, and conditioner solids content. The study revealed that the effect of all these parameters was important. However, it was discovered that contrary to common beliefs, the conditioning time affected the grade of the rougher concentrate much more than the recovery. Specifically, the longer the conditioning time, the less quartz that was floated. It was also discovered that high mixing intensity conditioners could lower the conditioning time required for good grade. Many phosphate operators use low intensity drum type conditioners. Optimizing the conditioning time, mixing intensity, and other conditioning parameters resulted in a rougher concentrate grading 30 pct P.2O5, with an attendant recovery of 95 pct.

Jan 1, 1993

The 29th annual American Mining Hall of Fame Awards Banquet and Fundraiser sponsored by the Mining Foundation of the Southwest (MFSW) will be held at the JW Marriott Star Pass Resort, Tucson, AZ on Saturday, Dec. 3, 2011. Each year, one living inductee, two recipients of Medals of Merit, and up to five honorees from mining history are chosen by the MFSW for their outstanding contributions to the mining industry. Chilean Minister of Public Works and former Minister of Mining, Laurence Golborne Riveros will be the guest of honor, featured speaker and inductee into the American Mining Hall of Fame. Golborne Riveros was instrumental in managing the rescue of the 33 Chilean miners in October 2010 and in the coordination/management of the ?townsite? for family members, rescue support and the media. His engineering background and executive management skills made him ideally suited to assist in both a technical and managerial role in this emergency.

Jan 1, 2011

By Lancelot E. Kun

The high-rate floc blanket clarification process developed by the Anglo American Corporation of South Africa is capable of continuously clarifying gold and uranium pregnant solutions containing 200-2500 mg/L suspended solids to below 25 mg/L solids at an average rising velocity of 8 m/h at the low process cost of R0,001-0,002 per ton of liquid treated. Overall process cost savings are mainly due to increased polishing filtration cycle times.

Jan 1, 1984

By Muhammad I. Kabir

A new minitest of in situ uranium leaching processes at reservoir conditions is proposed. The test which consists of a single observation/ production well and two observation wells is designed to permit the evaluation of both restoration and leaching parameters. It is shown that by using a straight forward history matching procedure, sometimes called a type curve analysis, both the rate of leaching and the ultimate uranium recovery can be evaluated based on the results of the test. Type curves are presented for the case in which the reaction rate is kinetically controlled and there are no other minerals competing for oxidant. Other situations can be approached using the same techniques as those presented here.

Jan 1, 1981

By Ernest Y. Baafi

The technique of linear kriging as a grade estimation method of mining blocks is reasonably established in the mining industry. Because of the nonbias condition imposed in kriging which requires that the kriging weights (?i) add up to one, negative weights are sometimes used in kriging. The use of negative weights is not justifiable from the practical standpoint. Also, negative block grades can be obtained in some extreme situations which makes no practical sense. To guarantee non-negative weights an additional constraint is required in the kriging system of equations. Unfortunately, the nonnegative weight constraint results in a set of non- linear system of equations. In this paper, a derivation of the resulting set of nonlinear equations is presented and a numerical algorithm is developed for the solution of the equations. Because the algorithm developed does not remove negative weights arbitrarily, optimal nonnegative weights are always guaranteed. Results obtained using the developed algorithm were compared with those using the standard linear kriging, in terms of computer time and the estimation results. Both the computer time and the kriging variance were found to be higher with nonnegative constraint, as expected. However, some systematic pattern was observed in the kriged values (i.e., over or under estimation) with or without the nonnegative constraint. The study also demonstrated when one should generally expect negative kriging weights in practice, and what practical impact the negative weights can have on the kriging estimates.

Jan 1, 1984

By E. B. McNew, J. M. Barnes, A. E. Torma

The applicability of biosorbent materials for the removal of uranium and other heavy metals from synthetic and actual uranium mil 1 tailing (UMT) solutions has been investigated. The biosorbent materials used in this study were barium loaded beads of alginate, alginate-dextran sulfate, alginate-carrageenan, and alginate-xanthan gum. These studies were performed in stirred vessels and packed columns. It was observed that 100 percent of the uranium could be removed from a synthetic solution following 2 hours of contact time in a stirred vessel, and 80-100% of U, V, Mo, Mn, Sr, and Zn could be removed from a UMT effluent solution with a packed column. Kinetic evaluations were performed, using a generalized rate equation, on the biosorption of uranium with these barium loaded beads.

Jan 1, 1992

By L. Adler

Existing classifications of mining and construction equipment have had major deficiencies. They often lack organization, balance, and have remained obscure. Particularly when proceeding to great.er resolution these deficiencies have proven crippling. By adopting "Classes", "Groups" f "Types" and "Kinds" at successive degrees of refinement, a "Taxonomy" is developed based on clear visual differentiation or on a "Morphology??. This symbiotic application, adopted from the Biological Sciences, yields clear, simple and unambiguous results. Supporting this effort are guidelines for easily and credibly sketching equipment which are also distinctive. Numerous illustrative examples are provided. Communications are improved and the engineer obtains a confident feel for the equipment at hand.

Jan 1, 1989

By A. Unal, H. Sevim

The utilization of high-sulfur Illinois coal by utility plants has been decreasing since the enactment of the 1990 Clean Coal Air Act Amendment. Illinois coal producers can make their coal more attractive by offering the choice of taking the coal combustion and flue-gas desu furization products from the utility plants and placing them in the abandoned sections of their mines To be competitive, however, coal producers need to select an environmentally acceptable transportation-handling-placement system through which the cost-per-ton of product disposed of can be minimized In this paper, several such systems are presented The favorable operating conditions of each system are determined in terms of distance and tonnage ranges. For a 90 kt/year (100 thousand stpy) operation, it is found that, up to a distance of 150 km (93 miles), transporting products by truck would be less expensive than using rail cars and intermodal containers. Also, a case study is given in which a cost analysis is conducted for an underground coal mine receiving products from two Illinois utility plants. At 90 kt/year (100 thousand stpy) and a distance of 40 km (25 miles) between the power plant and the mine, it is found that truck transportation and under ground placement would cost $0.090/tkm ($0.131/st-mile) and $2.98/t ($2.70/ st), respectively.

Jan 1, 1999

By Wm. I. Weisman

Sometimes in assessing where we are and where we are going it is informative to take a look at where we have been. Whether or not it adds to our understanding of the present, I think it may be interesting to review some of the past history of our industry. As a starting point I chose to use the famous Paley Commission Report, formally known as "The U. S. President's materials Policy Commission -Resources for Freedom."(l) The Paley Commission report said "Fluorspar is an essential raw material for the steel, aluminum, and chemical industries." Of course this statement is still true. It also said, "United States known reserves of fluorspar would be sufficient for some 15 years at present rates of consumption--about 426 000 short tons in 1960. Projected consumption for 1975, however, is several times as great, and reserves in other free countries do not appear adequate to supply United States deficiencies during the next 25 years." This simply demonstrates how even the most learned and competent people can observe all the facts avail-able to them at a given time and yet be unable to predict the future very accurately. We all know that reserves in other countries are more than adequate to supply the United States today, 25 years since the report was published. In fact, the report estimated free-world reserves at something over 36 million tonnes (40 million short tons). Contrast this with 246 million tonnes (271 million short tons) estimated as total world reserves from the section on fluorspar from Commodity Data Summaries of 1974, published by the Department of the Interior. (2) The Paley Report discusses other matters pertaining to fluorspar that are still of interest, such as improving mining methods. Furthermore, it certainly did a good forecasting job in noting that greater recycling should become possible in the aluminum industry in regard to fluorine lost in wastes and also concerning the substitution of fluorspar in the steel industry by other fluxing materials. It also suggested that non-fluorine containing propellants should be investigated as a replacement of those containing fluorine as a conservation matter. Some discussion was devoted to recovering the fluorine content of phosphate rock, which is being practiced today, but was in its infancy in 1950.

Jan 1, 1978

By Kefton H. Teague

An article entitled "The Rule of the Geologist in the Industrial Mineral Field" by G. R. Gullet, was published in the August, 1967, issue of the Canadian Mining Journal. Mr. Gullet defined industrial minerals as follows: "Industrial minerals are largely non-metallic minerals and rocks that find value because of their physical or chemical properties." This definition is brief, but all-inclusive. Mr. Gullet continues, "They include all useful minerals and mineral commodities except those used as fuels and those from which metals are extracted. Factors in the evaluation of an industrial mineral deposit are generally as different from those used in the evaluation of a metal deposit as is the assessment of a potential oil field. The key to the successful development of an industrial mineral, deposit is more often a balance of accessibility, transport, and proximity to markets than to any natural quality advantage of the deposit itself."

Jan 1, 1972

By J. Peck, M. J. Scoble, C. Hendricks

This paper is based on field studies in North American surface mines. The work involved the adaptation of microprocessor-based instrumentation to monitor various operating parameters on-board rotary blasthole drills and mining shovels. Following a review of instrumentation and monitoring methodology - drawing on experience gained under field conditions-the paper will focus on the application of monitoring technology within the framework of an Integrated Equipment Monitoring System. Such a system will permit real-time performance evaluation of key equipment involved in surface mine production. Drill performance monitoring has been demonstrated through work to date, to provide significant input into blast design, reserve estimation, mine planning and production control processes, through an improved facility for ground characterization. Monitoring excavation equipment has been proven valuable in assessing how effectively the input from drill monitored data has been used in the evolution of blast designs. This specifically refers to assessing blast efficiency through measuring associated levels of excavator performance in relation to muckpile characteristics. The medium-term goal of equipment instrumentation and monitoring has been to assist mines in optimizing the overall rock breakage and handling process. Based on the reported results, this has been accomplished. Long-term efforts now concern using a greater understanding of equipment performance and response to varying operating conditions as a foundation for the implementation of mining automation.

Jan 1, 1993

By H. J. Brown

Pluess-Staufer (California) Inc. Lucerne Valley California operation is one of the largest producers of high brightness high purity fme grind limestone products in western North America. The San Bernardino Mountains area of southern California contains the largest high brightness, high purity limestone mining operations and undeveloped reserves in western North America (Fig. 1, Brown 1987). Combined annual production of high brightness limestone products from several operations is approximately 1.5 million tons, with an estimated gross value of $75 million dollars per year (Fig. 2). An additional 5.0 million tons of cement grade limestone is mined by several large cement producers in the nearby Mojave area (Brown, in press). The purpose of this paper is to summarize the geologic setting, genesis and mining of white, high purity crystalline limestone by Pluess-Staufer (California) Inc.

Jan 1, 1994

By Gary S. Brierley, James R. Lambrechts, Andrew F. McKown

Various innovative Ground Improvement techniques have been proposed and applied to facilitate construction of the Central Artery/Tunnel Project in Boston. Given in this paper are discussions of the extensive use of deep soil mixing and jet grouting, and passive construction dewatering applications that are associated with the Design Sections D009A, D007A, and D019E.

Jan 1, 1999

By Tim Neil, O&apos

Acid rain legislation, the new tax package, excess coal capacity, the effects of low oil prices, how to increase coal exports: These were among the items discussed at the May 4-7, American Mining Congress coal convention in Pittsburgh. Some 2000 people attended the convention, which also offered 15 technical sessions. As always, the state of the domestic coal industry might be characterized as "long-term promise, short-term problems." And one of these problems is acid rain. Acid rain The proposed acid rain legislation in Congress could be the most costly piece of environmental legislation ever written. In its present form, the measure could cost the nation up to $110 billion over the next 15 years. Rep. Henry Waxman's (D-CA) bill, HR 4567, would mandate large reductions in sulfur dioxide emissions from coal-fired power plants. The bill has more than 150 Republican and Democratic cosponsors. Ed Addison is president of the Southern Co., one of the nation's largest utilities and users of domestic coal. Addison noted that America's electric utility industry buys and uses nearly 85% of the coal consumed in this country. He said Waxman's bill would drive up prices of low-sulfur coal, raise electric rates, and force miners out of work in high-sulfur coal regions. In repeating a standard coal industry response, Addison said the Clean Air Act is doing the job. In recent years, while coal use has gone up, S02 emissions have gone down. Current air pollution standards are producing cleaner air, he said. Despite concern over HR 4567, the bill's future is uncertain. Several coal industry executives and analysts predict the bill will die under weight of opposition from coal, utility, and steel interests. But the acid rain issue is gaining momentum. Future legislation of some kind is likely. Meanwhile, research continues to develop clean coal technology to deal with the S02 problem. Commercialization of these front-end technologies currently lags public sentiment for acid rain legislation. Ground water runoff and contamination is another area where future legislation would seem likely. Already, one bill has been introduced in Congress. A second is being drafted. The impact of such legislation may be significant according to Bruce Leavitt, a hydrogeologist with Consolidation Coal Co. He said if current proposals are adopted, there will be more federal, state, and local government involvement in ground water regulation. In any event, the coal industry can expect to see more emphasis on preventing acid mine drainage and on water replacement, according to Leavitt. He urged those in the coal industry to present information about mining and ground water. That is needed to prevent misdirected state and federal programs, he said. Another coal industry concern is excess capacity. The industry has the mines, equipment, and employees to produce 15% more coal than at present. Problem is, the markets are not there. Slower-than-predicted growth in electric utility coal use has kept sales sluggish. There are also tax uncertainties. Congress is considering repeal of the investment tax credit and elimination of black lung payments and excise taxes as deductible expenses. One analyst estimates the coal industry would lose $1.1 billion in five years, if the changes are approved. In addition, there are the usual concerns about excessive governmental regulations involving safety and environmental matters. Bill Kegel, for example, said these regulations mean extra costs and delays in developing mines. Kegel is president and chief executive officer of the Rochester & Pittsburgh Coal Co. More than half the electrical power in the US is generated by coal-fired plants. That percentage could slip by a couple of points as nuclear generators come on-line the next few years. About 1990, though, we will see the end of US nuclear plant construction. No new nuclear plants have been scheduled since 1978. So any growth in electric power use should benefit the coal industry. BethEnergy - High Power Mountain During 1985, BethEnergy - a Bethlehem Steel Corp. - subsidiary developed High Power Mountain, a 1.8-Mt/a (2-million-stpy) surface mine in West Virginia. Construction saw movement of more than 3 hm3 (4 million cu yds) of earth. A computerized 544 t/h (600 stph) heavy media cyclone prep plant and a 3.6-kt/h (4000-stph) railroad loadout facility were built in six months. And a 5.6-km (3.5-mile) railroad spur and loop bridging a major highway were constructed. Larry Willison of BethEnergy noted the project's ambitious construction schedule. It was forced by the need for the project to be market driven and - lacking available capital - externally financed. BethEnergy did several things before obtaining with Detroit Edison a market for 0.9 Mt/a (1 million stpy) of coal. Willison said his company prospected and proved the eastern half of its 8-km2

Jan 7, 1986

By D. R. Spears, D. A. Stanley

The US Bureau of Mines investigated the fundamental aspects of shear-flocculation using a rapid, in-situ particle size analyzer. Silica was stirred in the presence of an aliphatic amine to determine the effects of collector coverage, stirring speed and solids concentration on the kinetics of shear-flocculation. The results showed that shear flocculation is a two-stage process. In the first stage, which occurs during the first 1-2 min. of the reaction, the mean particle size increases rapidly, and in the second stage, an equilibrium is set up between the rates of floc growth and floc decay. Collector dosage affected the position of the equilibrium by altering the number of surface sites for particle-particle attachment. A minimum stirring speed was necessary for shear flocculation, which was dependent on solids concentration and collector dosage. This stirring speed was the minimum necessary for particles to overcome the electrostatic energy barrier, and that results in keeping the conditioned particles dispersed. Larger particles flocculated more rapidly. At very high stirring speeds, large flocs became unstable, resulting in a narrowed particle size distribution in the slurry.

Jan 1, 1995

By Harry Sutcliffe

INTRODUCTION The need for discussion of Owner-Engineer-Contractor relationships in tunneling arises from the increase in costly and time-consuming litigation. The paper examines the objectives, motivations and responsibilities of each party, discusses some common causes of claims in underground work, and makes some suggestions for improvements. The viewpoint and bias are those of an engineer. If a subtitle were required for the session, "Sharing the Risk" would be appropriate. Sharing the risk is an important aspect of Owner-Engineer-Contractor relationships because when a risk is shared, all parties have an incentive to minimize it. The System It would be shortsighted not to recognize that the system is wider than the Owner, the Engineer and the Contractor. There are many outside influences which affect the day-to-day behavior of each party: Financing agencies Insurance agencies Bonding agencies OSHA and other safety legislation The Federal Power Commission The Public Utilities Commission The General Accounting Office

Jan 1, 1997

By Charles R. Marek

There is an ever-increasing need for quality construction materials to provide the necessary housing and transportation facilities required for the protection and movement of people and goods. By the year 2000, requirements for housing in the United States will have doubled due to population growth. Requirements for transportation facilities in this same period will also have increased substantially. Further, all existing facilities for both housing and transportation will require substantial maintenance of one form or another. Aggregate is the basic material of the construction industry. There is some occurrence of aggregate source material in virtually every state of the United States, and in every country in the world. United States reserves of commercially useable aggregate have never been systematically estimated and are probably so vast as to be incalculable.1 However, in many areas its existence is largely negated by inaccessibility. Often it is lodged deeply or intricately in the earth or it is too distant from markets to offer a desirable "return on investment" under the present economic structure. Other factors that prevent its utility are the occurrence of small scattered deposits that individually are too small to justify the necessary capital investment for exploitation and collectively are too widely disseminated; also, the aggregate nay be deficient in certain desired chemical or physical qualitites.1

Jan 1, 1974

By A. J. Friedrich

Conveyor belts are designed to go unnoticed. When they work well, they attract little attention. When they are not doing the job right, it is noticeable, and they need to be fixed immediately. Vulcanising contractors compete for the maintenance of belts in mining/quarrying and general materials handling worldwide. Damage repair is approached in similar fashion. The damaged section of belting is normally cut out and discarded, and the belt re-spliced using hot vulcanising, Cold splicing, or mechanical fasteners/clip joints. However, there is a cost-effective alternative, alleviating the need to remove damaged sections which are often perfectly recoverable. This is the use of cold-curing repair resins and adhesives.

Jan 1, 2000

By Jim Oehler

The US minerals industry, as well we know, has been hit hard by the recent recession and is faced with what is projected to be a slow recovery. Even so, there was an underlying feeling of optimism at American Mining Congress' International Mining Show in Las Vegas, NV, Oct 11-14. More than 25,000 people attended during a particularly rough financial year, dispelling fears that attendance would dip sharply below 1978's 30,000 plus tally. The equipment expositionheld every four years-was the largest show of its kind this year in the Western Hemisphere in terms of exhibit space, providing an extensive view of mining-related equipment. In addition to the nearly 700 exhibits occupying more than 445 hm2 (11 acres), 20 technical sessions were held covering topics ranging from minerals availability and the state of the mining industries to communications, computers, and accounting. Government officials were well represented, with six US senators and five US representatives participating in various convention functions. Sen. Paul Laxalt (R-NV) was the keynote speaker at the welcoming luncheon. Other senators involved in the show included Howard W. Cannon (D-NV), Pete V. Domenici (R-NM), James A. McClure (R-ID), Frank H. Murkowski (R-AK), and Steven D. Symms (R-ID). Representatives on the program were Joseph M. Gaydos (D-PA), Guy Vander Jagt (R-MI), Don Young (R-AK), Jim Santini (D-NV), and Ceil Heftel (D-HI). There were also many international vistors at the show, including exhibitors from Australia, Austria, Canada, England, Finland, Sweden, South Africa, and West Germany. Equipment Highlights Equipment and services featured at the exposition ranged from aerial mapping to wire rope. Aisle space alone between exhibits exceeded 8 km (5 miles). And the companies represented ranged from small businesses to large corporations. Some of the company products described here are representative of the many exhibitors in attendance. Atlas Copco's extensive display of rock drilling and tunnel and shaft boring equipment featured its Boomer H-201, the newest addition to its line of underground drifting rigs; the ROC 306, a new track-mounted, high pressure down-the-hole drill rig; a new hydraulic surface crawler drill, the ROC 712H, designed for small and medium-size holes in quarries and small open-pit mines; a computerized analysis system, CARE (see page 1570), designed to project productivity and operating costs for various mining operations; several electro-hydraulic loaders, including the new rail bound LM E60 and LM E80, and two Hagg-loaders-the 7HR and 10HR-that use two digging arms to rake and guide muck; a mechanized blasthole charging system; rock bolting equipment and its new Swellex roof bolting method; Sandvik Coromant drill steel and bits; and its new Jarva R200 raise boring machine.

Jan 11, 1982