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By Alain Broussaud, Guy Fourniguet, Jacques Franck, Pierre Conil

Steady-state simulation is now in current use to assist mineral processing plant design and optimization. However, the reliability of results generated by simulators has not until now been seriously investigated. A simulator supervision algorithm was designed and programmed to study both the influence of the reliability of experimental data on the accuracy of unit operation model calibration, and the influence of unit operation model accuracy on the results of direct plant simulations. An application to a grinding flotation plant is described and discussed. The approach may open the way to the quantitative analysis of the risks taken in mineral processing projects, which would be similar to the application of geostatistics to mining projects.

Jan 1, 1990

By G. Mbuyi Kamba, J. Patigny, E. Jacques

Traverse anemometry is still widely used today. In this paper an investigation of the influence of three factors which are believed to contribute to the resulting error of the method, is reported. They are the shape of the traversing path, the size of the vane anemometers and the air velocity pattern. These factors are experimentally studied on a test facility developed specially for this purpose. Taking into account the results of 576 measurement sessions, as well as published information, some preliminary conclusions are drawn, and additional questions are raised.

Jan 1, 1993

The objective of the fines flotation step in a coal preparation plant is to maximize coal recovery subject to a constraint on the allowable ash in the concentrate. The objective is achieved when the incremental ash is driven to a target value determined by an economic constraint. In this paper, a phenomenological flotation model and ash analyzer combination are identified that allow the development of a soft sensor for incremental ash and subsequently a model-based strategy which manipulates key flotation variables to achieve the control objective. A combination of plant tests and computer simulations are presented to evaluate control-system performance in one operation.

Jan 1, 1999

By S. K. Kawatra, H. J. Haselhuhn

"Fine-grained hematite ore can be concentrated by the process of selective flocculation and dispersion, which relies on proper reagent selection and control of water chemistry. While many previous studies have been performed analyzing the effects of different reagents on this process in a laboratory environment, this paper focuses on investigating the water chemistry within the process in a pilot-scale continuous deslime thickener.The pH, sodium concentration, calcium concentration and magnesium concentration were varied to determine their effects on the iron concentrate grade and recovery, and the phosphorus concentrate grade and rejection in the pilotscale selective deslime thickener. The ideal pH for the iron grade and recovery of the process using a starch selective flocculant was found to be 10.5. Phosphorus rejection, however, was increased at lower pH values. Minimization of sodium concentration was shown to improve iron grade, iron recovery and phosphorus rejection. Calcium acted as a nonselective flocculant showing higher iron recovery, lower iron grade and lower phosphorus rejection with increasing concentration. Conclusions could not be drawn from the experiments that varied magnesium concentration.The zeta potential of the solid-liquid interface of particles in each sample taken was also analyzed to show relationships between zeta potential and process performance. In all cases, a maximization of the magnitude of zeta potential correlated with increased iron grade and recovery. This supports the hypothesis that a higher level of dispersion enhances the selective flocculation and separation process.IntroductionThe United States produced 53.2 million metric tons out of the 3,000 million metric tons of concentrated iron ore produced worldwide in 2012 (Tuck, 2013). With this in mind, there has been a large increase in iron ore processing research (Bolen, 2014; Carlson and Kawatra, 2008, 2013; Halt and Kawatra, 2014; Halt et al., 2014; Haselhuhn et al., 2012a,b, 2013a,b; Liu et al., 2014; Manouchehri, 2014; Sandvik and Larsen, 2014; Semberg et al., 2014). Of the 53.2 million metric tons produced, roughly 8 million metric tons of hematite (Fe2O3) concentrate were produced using a process known as selective flocculation and dispersion (Cliffs Natural Resources, 2011). This process is the only economically viable method for concentrating low grade (< 40% Fe) fine grain (< 25µm liberation size) hematite ores. It is scarcely used due to difficulty in controlling the surface chemistry of the ore and high reagent costs (Department of Energy, 2001; Haselhuhn et al., 2013a). The process is highly dependent upon both reagent selection and precise control of the water chemistry during separation. This study shows the dependence of the process performance of a pilot-scale deslime thickener on the water chemistry in the feed slurry."

Jan 1, 2015

By Lloyd E. Haight

After accepting the invitation to make this appearance today, it occurred to me that the subject matter which had been assigned to me, namely, the purpose and role of an advisor, was, contrary to what; some people might think, a controversial subject. In my brief lifetime, I have discovered that the world is full of advisors; that is to say, there are many people who undertake to render advice concerning subject matters upon which they may, or may not be qualified to speak. It shall be my purpose today to set forth what now appears to be the function of the members of the Advisory Council to the U. S. Public Land Law Review Commission; and, in so doing, I hope that I do not offend the Commission or any other-member of the Advisory Council with whom I serve. It has always been my personal conception of the role of an advisor that he should tender advice when it is requested, and then only if he has prepared himself concerning the matter upon which the advice is being given. I am sure it was the Congressional intent at the time the Public Land Law Review Commission was established indeed it was the hope. of Congress--that those of us who were to become members of the Advisory Council were informed upon certain particular subjects and then at the proper time express our opinions upon these subjects-and, by the same token, not attempt to enter opinions upon problems with which we have no experience in theory or in actuality. Some wag once said that if Columbus had had an advisory council, he would still be waiting at the dock in Spain, and there is more truth than fiction in that statement. With this problem in mind, let us examine the purpose of the Advisory Council itself.

Jan 1, 1967

By Michel Grenier, Mahendra Gangal

Two methods used to measure the exposure of mine workers to diesel exhaust particulate were compared. One method was developed by the U.S. Bureau of Mines and the University of Minnesota&apos;s Particle Technology Laboratory. The method which was originally developed for use in coal mines is a size selective sampling technique. The other method uses an “ashing" approach to assess the exposure to diesel particulate. This second method is based on the principles of sampling according to the ACGIH respirable dust sampling criteria and the use of a silver membrane filter as collection substrate. Because a silver membrane filter is used, both respirable combustible dust (diesel particulate) and respirable silica can be measured from one sample. The comparison study took place in a Canadian lead-zinc mine during tests which were primarily designed to evaluate the gaseous and particulate emissions characteristics of new diesel engine technology. The study has shown that under the test conditions encountered, some differences were observed between the results as obtained by the two methods. These differences seem to depend on the characteristics of the respirable dust found in the work- place, i.e., size and composition. The impact, on sampling and analysis of diesel particulate, of the proposed guideline (ACGIH) for a TLV® of 0.15 mq/m3 is discussed briefly.

Jan 1, 1997

By J. P. Vandenhoeck

Sizing devices used commercially are unfortunately not 100% efficient, the splits that can be obtained are usually inferior to the results obtained in the laboratory. Often the capital and operating costs of equipment capable of high sizing efficiency cannot be justified by the economics or requirements of the process. To reconcile the desired sizing efficiency needed to obtain optimum process requirements with the sizing efficiency of equipment economically practical, it is often necessary or desirable to predict the gradation and weight splits of the products obtained based on the expectant efficiency of the contemplated sizing device or method. The less efficient the sizing device one must employ, the more important it is to know the results that may be expected for the establishment of the optimum flow sheet and the more difficult it becomes to estimate the results accurately. Air classification equipment which sizes materials by opposing the drag force created by an air stream acting on a particle with a combination of gravitational, inertial or centrifugal forces are substantially less efficient than, for example, a laboratory sieve analysis. Air classifiers allow oversize material to contaminate the fine fraction and leave undersize material in the coarse fraction. The techniques employed to predict the gradation and weight splits obtained from air classification outlined below are adaptable to other sizing devices less than 100% efficient such as screens, sifters and wet classifiers.

Jan 1, 1965

By A. J. Neale

Much has been published lately about the application of advanced control strategies in the automatic control of autogenous and semi-autogenous grinding circuits. The application of adaptive control algorithms, self-tuning controllers, state estimation, and expert systems has been well documented. While these approaches can be very effective; experience has shown that quite often simply "fixing the fundamentals" can have a significant positive impact on overall grinding circuit performance. This paper will highlight the results of process optimization and process control work by the authors at a variety of autogenous and semi-autogenous installations. A review of one approach for quantifying the mill load/bearing pressure/power relationship is provided. Accurate monitoring of key mill process variables is a necessary prerequisite for both effective process analysis and process control. This paper discusses some of the concerns related to defining steady state operating conditions and the issues related to signal conditioning. The paper concludes with a discussion of an effective application of algorithmic constraint control which incorporates many of these considerations.

Jan 1, 1994

By C. H. Grant

On the Mesabi Range, Ammonium Nitrate is used for blasting a variety of materials having widely varying blasting characteristics. The materials vary from hard, dense, magnetic taconite, which requires heavy blasting, through relatively soft, earthy, direct shipping ores, which require only light blasting to facilitate shovel operation. In view of the fact that materials gradational between these two end members are encountered in large tonnages, it is evident that a wide range of blasting situations face the mine operators on the Mesabi Range. In April of 1956, at Cleveland-Cliff s Hawkins Mine near Nashwauk, Minnesota, a fertilizer grade of Ammonium Nitrate prills was first used as a blasting agent. This first attempt was made without the addition of any carbonaceous material and even though it did go off, the force was not sufficient to produce the required results. Fuel oil was then added In the amount of one gallon for each 80 pounds of Ammonium Nitrate, with the oil and Ammonium Nitrate being added to the hole simultaneously. This blast was successful. Since then most of the mining companies have used Ammonium Nitrate, experimenting with various ratios of oil and fertilizer, mixing these ingredients either before or during loading of the holes. Since the additional of fuel oil to the Ammonium Bitrate before loading produces a more uniform saturation, most companies have adopted the method of pouring the fuel oil directly into the Ammonium Nitrate bags and then pouring the mixture into each hole. The ratio of 3- ½ quarts of fuel oil to each 80 pound bag of Ammonium Nitpate prills is now being used.

Jan 1, 1958

By Roger D. Sharpe

The United States Gypsum Company operation at Plaster City, in Imperial County, California, consists of the largest gypsum quarry in the United States, a company-owned, narrow-gauge railroad and wallboard and plaster manufacturing facilities. A variety of gypsum products, including many types of wallboard, construction plasters, portland cement setting agent, and agricultural gypsum are manufactured. Gypsum is quarried from the Miocene age Fish Creek Gypsum. Evaporite minerals were deposited in a clastic-rich sabkha environment along the margin of a small embayment in the Salton Trough. The Salton Trough is a major regional structure that formed by rifting and transform faulting along the Elsinore, San Jacinto, and San Andreas fault zones. Sedimentary basins were formed between tilted fault blocks. The basins were filled by prograding alluvial fans, basin margin sabkha and marine sediments, and deltaic deposits from the Colorado River. Gypsum is exposed in the quarry on rounded hills with 250-300 feet of relief. The evaporites are up to 200 feet thick and average 125 feet in thickness. Anhydrite commonly occurs in the lower part of the evaporites under the crests of hills and beneath thick alluvial cover.

Jan 1, 1995

By W. Nahas, T. C. Watson, A. R. Maycock

The development of roasting technology for the oxidation of sulfides in refractory gold ores is discussed. Case studies covering operations dating from the mid-1930&apos;s to the present day are used to illustrate this development. The roasting of ores and concentrates is reviewed and various gas cleaning flowsheets are discussed with particular reference to environmental requirements. A sequence chart is provided to show the development path of a potential roasting project.

Jan 1, 1990

By Qing Wang

A longterm overburden removal plan can be realistic and optimum only when the cost and capacity profiles off the equipment assigned to the operation are taken into consideration. Therefore, the planning should involve the proper assignment of equipment capacity by insuring a timely investment and a timely replacement policy throughout the mine life. A dynamic solution algorithm has been developed, by which all possible truck fleet alternatives are evaluated for each year off the operation. Cumulative cost off the operation is carried throughout the analysis. The optimum solution is obtained by selecting the minimum cumulative cost at the last year and tracing backward the best fleet alternative for each year. The solution provides: 1. the optimum amount of overburden to be removed each year; 2. the best fleet to be assigned to the job; and 3. the best equipment replacement policy.

Jan 1, 1989

By J. C. Cawley, J. Sottile, J. L. Kohler

Control circuit failures contribute significantly to continuous miner downtime. The time required to put the machine back into production is a function of the time required to diagnose the problem, obtain parts and make the repair. Of these, the diagnostic time is often the largest. A microprocessor-based system with the ability to diagnose all of the common control circuit failures was designed, installed on a continuous miner and tested. This paper summarizes the development of the diagnostic system and provides examples of the system&apos;s diagnostic capabilities. Implementation issues and the hardware used for the prototype are briefly described. Comments on the system&apos;s performance are also presented.

Jan 1, 1995

By L. M. Petrie, D. C. Marozas, S. E. Paulson

The US Bureau of Mines (Bureau) is conducting research to evaluate the potential for developing an in situ leach mining process that will selectively extract manganese from oxide ores, leaving gangue relatively undisturbed. To accomplish this, a geochemical approach based on deposit-specific information, such as mineralogy and geology, is used to constrain the operating parameters of the system. Among the studies being conducted are: • leaching experiments to define reaction mechanisms and kinetics, • detailed petrologic characterization at the microscopic scale to assess manganese distribution and leaching efficiencies, • deposit characterization and evaluation, and • development of potential manganese recovery schemes. Data from these studies are being used to develop engineering design information for an in situ mining process. Specific details of the Bureau&apos;s research project are discussed, including results obtained to date.

Jan 1, 1993

By Charles D. Litton

This Bureau of Mines paper describes a novel fire detector that can be used to discriminate between smoke produced by a fire and smoke produced by a diesel engine. The detector uses a pyrolysis technique whereby a sample of smoke- laden gas passes through a short, heated tube within which fire smoke particles pyrolyze and increase their number concentration and decrease their average size, while diesel smoke particles are unaffected. The detector is designed for use in mines that use diesel-powered equipment where the detection of fires is complicated because of the diesel emissions background levels of smoke and other products of combustion.

Jan 1, 1989

By V. K. Gupta

A detailed laboratory study was carried out to investigate the effect of the particle size distribution on the grinding rate parameters, Si, for the dry ball milling of quartz and limestone. Contrary to the present belief, the Si values were found to vary strongly with the particle size distribution. In particular it was observed that: (i) the Si values increased with the fineness of the particulate charge - the increase being more pronounced in the case of the coarser sizes, (ii) the next finer size class had the maximum effect on the breakage of the particles of a given size class, while the coarser size classes had only a slight effect, (iii) the effect of two or more size classes was non-additive, and significant higher order inter-size interactions were indicated. The importance of these results in the context of the analysis, design and scale-up of the comminution systems is discussed.

Jan 1, 1987

By S. Chunhui, W. Anbin, R. B. Cook

The Xicheng is one of China&apos;s largest lead-zinc (Pb-Zn) districts with known minable reserves in excess of 10 Mt (11 million st). The centrally located Changba-Lijiagou and nearby deposits are representative of the district. They consist of stratiform and stratabound zones of pyrite-sphalerite-galena mineralization within deformed, moderately metamorphosed Middle Devonian clastic and carbonate units. When considered with other similar districts that extend for several hundred kilometers to the east, a major episode of Devonian sedimentary exhalative mineralization is indicated.

Jan 1, 1992

By Francisco J. Escandon V.

Numerous lead-zinc-barite-fluorite ore deposits, with simple mineralogy and roughly concordant with bedding, are found widely distributed all over the world, having been denominated and well described as "stratiform deposits" or "strata-bound ore bodies", not having any genetic relationship. During several years, its origin has been discussed, without getting to general agreement regarding the main mining districts of this type. Through studies made of large stratiform deposits in the United States, Europe and Russia, it has been found that there are, within this classification, syngenctic diagenetic and epigenetic ore bodies. During the Symposium about the genesis of the stratiform lead-zinc-fluorite-barite deposits, carried out in New York in 1966, Frank G. Snyder (1), presented an excellent analysis of the theories of the origin of these deposits and of the evaluation of the criteria regarding classification. As per his definitions (Table 1), "a deposit is syngenetic if formed by processes similar to and simultaneously with the enclosing rock, epigenetic if introduced into a pre-existing rock and a diagenetic origin implies deposition of metals with the host sediments but with recrystallization, rearrengement and limited migration".

Jan 1, 1974

By J. P. Van Dillen

Continuing interest in processes that will effect separations in the fine particle size range has prompted intense interest in the use of high gradient magnetic separation (HGMS) for beneficiation of uranium ores. Some of the uranium minerals are paramagnetic and hence are amenable to concentration by HGMS. This paper presents a brief review of the problems associated with uranium ores beneficiation, a description of the HGNS process, and the effects of the parameters--pulp velocity, field strength, matrix loading and magnetic field gradient on product recovery and grade. Unsatisfactory separation of uranium minerals by HGHS is related to ore specific properties such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix and interference of micron sized slimes. Experimental techniques to identify and resolve some of these problems are outlined.

Jan 1, 1982

By Daniel H. White

Block caving, unlike most other conventional forms of mining relies principally on the natural forces within the rock mass to fragment and transport the ore. Obviously, not every orebody can be satisfactorily mined by block caving. In the early stages of mine planning an attempt should be made to assess the benefits of the block caving system relative to others, and develop a reasonable mining concept that may be used to provide preliminary information to mine planners and financial specialists. It is the intention of this paper to outline some basic geotechnical parameters that are essential to: 1) Assessing the feasibility of block caving an orebody and 2) Providing semidetailed information relative to mine design based on drill hole and other data.

Jan 1, 1979