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By A. W. Khair

This paper presents an analysis of respirabie dust generation due to the action of a continuous miner. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). An analysis of -400 mesh particles was done on gravity collected material. Samples of entrained dust were collected through the use of cascade impactors. Both samples were analyzed for size distribution and particle shape. Using the simulated coal cutter permitted variation of operating and in-situ parameters to provide information on the effects on generation of -400 mesh particles. In these tests coal blocks with an approximate dimension of 18 in. x 15 in. x 6 in. (45.7 cm x 38.1 cm x 15.2 cm) were first subjected to confining pressures, equivalent to in-situ conditions. Such blocks were then cut by the cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using an optical microscope with an attached camera.

Jan 1, 1985

By D. A. Dahlstrom

Since the initiation of continuous vacuum filtration over a half a century ago, control of the performance of these units has been largely in the hands of the plant operators, Obviously there has been the introduction of variable speed drives, adjustable speed feed slurry agitation, vacuum control, etc. However, control of , filtration rate, cake moisture content, dissolved solids recovery by cake washing and dryness of solids where thermal drying is practiced is primarily up to the operators judgment and the settings he imposes on the controls he regulates, - filter cycle time, submergence, vacuum level, filter medium condition, wash water- rate, and other such factors. While this may seem to indicate that good operators are a paramount necessity, and certainly always desirable, a considerably more vital factor is a properly designed filter and filter station for the particular application. With improper design, highly skilled operator control will still leave much to be desired in the way of process performance. On the other hand, with correct design and application, the operator can easily and quickly control normal plant surges and quality variations within the flow sheet. Due to the growing complexity and inter dependency between the various processing steps in the modern flow sheet as well as the rising costs of capital investment, labor, maintenance, and losses involved with off quality product or insufficient recovery, automatic or inherent performance control of many of the unit operations within the metallurgical mill must be achieved. Continuous filtration should and can be susceptible to such control. However, as every instrument engineer knows, before control and automation can be achieved, a basic understanding of the operation is mandatory. This is primarily due to three factors. First, as in so many control applications, it may not be possible or feasible to measure the factor that it is desired to control. Thus, secondary variables that influence the major factor are substituted for control purposes. Secondly, it is always desirable to take advantage of any ?self-regulation? within the operation being performed on the equipment. In so doing, not only will automatic control be facilitated, but instrumentation is minimized while experiencing most efficient operation. Finally, automatic control is not a cure-all for improper process and equipment design and application. Hanging instruments on such an operation can be compared to constructing a sizable building on sand, Results will be disappointing.

Jan 1, 1960

By D. R. Dixon

Since the critical role of oxygen in xanthate flotation of sulphides was established (1) subsequent studies have been concerned mainly with the galena-xanthate system. It is therefore surprising to find at the conclusion of a comprehensive review of the topic by Granville, Finkelstein and Allison (2) that it was not possible for them to draw unequivocable conclusions on the mechanism of xanthate adsorption. It was apparent that some new advances were likely if systems other than galena-xanthate (Pbs/x-) were examined. (2) Specifically a less reactive sulphide such as ZnS may interact with flotation reagents at a slower rate than PbS and more information per unit time gathered. Again ZnS is far less reactive electrochemically than PbS or stated equivalently, it is a poorer semiconductor than PbS. More importantly, the ability of ZnS to act as a semi-conductor can be controlled photochemically rather than by direct doping reactions for which it is difficult to assess the uniformity of doping. Thus the conductivity of ZnS can be made the same as that of PbS by irradiating the ZnS with ultraviolet light at circa 360 n.m. (3)

Jan 1, 1974

By Alex G. Sciulli

According to recent estimates, nearly 30 percent of the material from underground coal mining in the United States is rejected on the surface as waste. This accumulation of almost three billion tons of coarse and fine coal refuse is primarily from coal cleaning operations. The marketable coal is intermixed with sandstone, clays, shales, and carbonaceous rocks, which must be removed and disposed of in an acceptable manner. The disposal of mineral wastes is a major environmental concern. The most common types of environmental problems associated with coal refuse disposal are acid formation, erosion, and sediment control. Other areas of concern include air and water quality, combustion control, mine sealing, and reclamation. This paper focuses on these topics and attempts to outline special environmental features which can be incorporated into the design and construction of a coal refuse facility. Often these measures can minimize and possibly eliminate the potential environ- mental hazards. It is imperative, however, that these measures be adopted prior to and during construction, because of the relative ease and cost savings compared to post-construction implementation.

Jan 1, 1983

By E. M. Schern

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

Jan 1, 1983

By C. R. Peterson

A cutter vibration monitoring system is described which would map seam strata non-uniformities to permit guidance within the seam. An extremely simple and rugged transducer is used which is compatible with conventional cutters and cutter replacement practices, and believed to be suited to the mining environment. Laboratory tests show that the system can detect bedding planes in otherwise homogeneous material. A data display system which would employ the human operator's natural pattern recognition skill and judgement will be developed, Intended for remote control applications in general, the system is of direct interest for today's continuous excavators in coal or in any other machine excavated bedded deposit.

Jan 1, 1985

By Larry S. Diaz

It is felt that prior to the presentation of the technical portion of this paper, some general information would be of interest. The Sar Cheshmeh Copper Mining Company was founded by the Iranian Government to oversee the design and construction of Iran's first copper smelter complex, which will be another step in the industrialization of Iran. Since this is the first such plant in Iran, Sar Cheshmeh wisely chose to enlist the technical assistance needed in regard to the facilities requiring engineering and operating know-how from outside of Iran. To obtain the foregoing, SCCM signed a contract with Anaconda-Iran, Inc., which was formed by The Anaconda Company for this project. The general scope of this contract covers the overseeing of engineering and design by Parsons-Jurden as well as physical plant construction. In addition to this, the same services were given to water supply and tailings disposal systems which were not included as part of the Parsons-Jurden contract. Anaconda-Iran is also assisting SCCM in setting up a training program for Iranian personnel for plant operations, administration, etc., which .will go on for some time after the plant startup, under the guidance of Anaconda-Iran expatriates. SCCM?s other responsibilities, in respect to the development of this industrial effort, are the building of a townsite for approximately 2200 families, the expected manning requirements, having all the facilities necessary to provide a pleasant life in a remote area. It has been estimated that the manpower for operations will be 2050.

Jan 1, 1976

By E. J. Freech

In this part of the two-part paper we discuss briefly the adaptation of the comminution model to describe the observed behavior of an industrial grinding circuit. Although reported verification of comminution models for continuous systems is limited, some interesting work has been reported 1,2 recently. The data acquisition and modeling efforts are described first, followed by discussion of some of the simulation results. Observations pertinent to steady-state operation are presented followed by a description of the application of a dynamic model of the grinding circuit for synthesis and evaluation of grinding-circuit control. The pilot-scale work indicated the comminution model should be capable of describing an industrial size-reduction process. Recognizing the broad utility of a process model based on first- principles, the Industrial Nucleonics Corporation of Columbus, Ohio, embarked on a joint program with the Duval Corporation of Tucson, Arizona, to evaluate the industrial applicability of the models described in Part I. This program was conducted in a grinding circuit, which included a rod mill 12.5 feet in diameter and 16 feet long and a ball mill 12.5 feet in diameter and 14 feet long, at Duval Corporation's Esperanza property3. The rod mill was operated in open circuit and the ball mill in closed circuit with cyclone classifiers.

Jan 1, 1970

By G. E. Tooker

This paper (1) presents new data on the use of horizontal curves to optimize the alignment of belt conveyors. The operating concept of a horizontal curve is simple. As an element of the belt passes through the curve, it is motivated to drift toward the center of the curve by unbalanced tension forces in the belt. This lateral drift is resisted by the forces of friction and gravity, which in turn can be stated as a function of drift. Resisting forces, as a function of drift, are stated in terms of variables such as the amount of load on the belt, and parameters such as the trough angle, tilt angle, and super elevation angle, and number of rolls in the idler. The trick is to determine that the belt will drift to a position of equilibrium within predictable limits, without physically constraining the edge of the belt. In practice this prediction is not easy to make without the aid of a computer. The motivating force is easy to calculate, but its value is continually changing throughout the angle subtended by the curve arc. The resisting forces are constant throughout the curve for a given drift and load condition, but the calculations are very complex. Data in this paper will assist the conveyor designer in making preliminary calculations for horizontal curves. Presented is the equation for calculating the motivating force, and a family of curves that show the resisting force as a function of lateral drift for some commonly encountered conveyor design criteria.

Jan 1, 1985

By E. Scott Bair

Renewed interest in the vast reserves of anthracite coal in eastern Pennsylvania led to the use of a numerical model for simulating the hydrologic effects of constructing an open-pit anthracite mine. The proposed mine would be approximately 1800-m (5900-ft) long, 1000-m (3300-ft) wide, and 300-m (1000-ft) deep. A two-dimensional, finite-difference, ground-water flow model was used to calculate ground-water seepage rates into the proposed mine, to evaluate the effectiveness of various deep-well dewatering systems, to calculate drawdown in adjacent wells and properties, and to estimate the capacity of the water-treatment plant. Site-specific values of pertinent hydrogeologic parameters were used in the simulations.

Jan 1, 1980

By Robert W. Carn

This paper presents the concepts which are presently being utilized in the design of coal export terminals. Criteria for selecting a viable site and establishing the terminal plan are presented. Factors affecting the design of the terminal as well as the present techniques and procedures in use today to determine the optimum use of equipment will be discussed along with the current trends in export terminal control systems. Finally capital and operating costs for a typical export terminal are reviewed.

Jan 1, 1982

By A. T. Yu

Bulk sampling is define' as the ?process of extracting a small fraction of material from a large bulk ...sufficiently representative ...for the intended purpose.? (ref. 1). Today's pressing need for simple, effective and reliable sampling systems is intensified by the growing demand for quality control as a means to cope with inflation, competition and rapidly increasing consumption of raw materials. Much has been written on bulk sampling (ref. 2 thru 9). It involves a wide range of subjects cutting across the domains of physics, chemistry, geology, mining, materials handling and processing, as well as probability and statistics. Since the problem itself is complex, any in-depth treatment cannot avoid a somewhat lengthy coverage. Of all of the related topics. Arbitrary, haphazard studies, on the other hand, can leave out important details and obscure or confuse the issue.

Jan 1, 1970

By I. Iwasaki

The presence of calcium ion in iron ore pulps causes heterocoagulation of montmrillonite on hematite leading to indiscriminate dispersion. Two methods were investigated to control the adverse effect of montmorillonite: chemical method using such complexing agents as EDTA and sodium tripolyphosphate, and mechanical method involving ultrasonic treatment. Their roles in controlling the adverse effect were investigated by zeta potential measurements, starch adsorption tests, and flocculation and selective flocculation tests.

Jan 1, 1986

By Keith Wallace

Although systematic control of ventilating air currents in underground mines dates back to the Greek and Roman empires, quantified analysis dealing with the cost of providing airflow did not appear until about 1860 when the first fans with acceptable efficiencies became available. Initially, these were introduced to avert methane explosions initiated by shaft bottom furnaces. However, discussions arose on how much coal the steam driven fans consumed in comparison with shaft furnaces in order to produce the sane amount of airflow. Ventilation economics had arrived. In 1981/82 a project was funded by the Department of Energy and carried out at the University of California, Berkeley in order to analyze and compare alternative ventilation designs from the viewpoint of economics and systems efficiency1. This paper highlights some of the results of that study.

Jan 1, 1983

By V. Svalbonas

With the occurrences of serious mill structural failures on both ball and primary mills, the mining industry has entered the era of detailed fabrication specifications. Such specifications, however, have been developed as individual entities, often by people not related to the mill design function. Therefore, there has been no effort to relate mill failure or safety to the existence or elimination of specific fabrication flaws; that is, no cause-effect failure relationships have been developed. The omission of this step produces a specification which can be termed uneconomical at best. The present paper attempts to fill this void, by reviewing methods for design consideration of flawed structures, and describing experimental tests used to tie such data to a meaningful quality assurance program in fabrication.

Jan 1, 1985

By J. Harrison Daniel

More stringent dust standards, because of quartz in coal, have become a major compliance problem for the coal industry. Reducing quartz levels has become the major focus of the Bureau of Mines dust control research program. Results to date have identified hath the sources of quartz and prospective control technology. Control techniques are being developed for both room-and-pillar and longwall mining underground operations. Techniques include changes in face ventilation, mining cycle modifications, and better roof bolting dust control.

Jan 1, 1985

By Joseph M. Morrison

This paper offers a comprehensive solution to the problem of dust emissions at belt conveyor transfer points. It discusses details of enclosure design and presents a straightforward procedure for calculating required dust control exhaust volumes. Many design variables are taken into account which heretofore have been commonly ignored or inadequately considered. These include belt widths, belt speeds, enclosure openings, material flow rates, material bulk densities, material lump sizes, height of material fall, material temperature, and ambient air temperature. All of these quantities are handled by means of a "fill-in-the-blanks" type of calculation form which permits quick, reliable solutions by relative "non- experts".

Jan 1, 1970

By Jim V. Rouse

The mining, beneficiation, and processing of phosphate rock in the Florida phosphate district constitutes a large portion of the southeastern mining industry. For example, 1973 production is reported to have been approximately 35 million tons of phosphate rock (Guimond and Windham, August 1975) and production has increased to over 45 million tons in recent years. The 1973 activity involved the movement of approximately 127 mil lion tons of material. From the hydrologic standpoint, this mining and beneficiation requires the dewatering of ore horizons, pumpage of large quanitites of water for mining and processing operations, and the entrainment of immense quantities of water in waste slurries. Also of significance is the fact that the cited 1973 production involved the disruption of approximately 3200 curies of radium and over 6000 curies of uranium. Much of this material reported with waste products, with the potential for contamination of area ground waters. However, natural removal mechanisms active within the area have generally been effective in preventing significant contamination of the ground-water resource.

Jan 1, 1983

By T. W. Peterson

There are two approaches to developing a minicomputer based application for an industrial grinding circuit. Usually, the control program is coded and compilation-debugged on a large-scale scientific computing system or the minicomputer itself if the machine is available. Final debugging and testing must wait for installation and checkout of the entire minicomputer system. Two immediate disadvantages of this approach are the need to obtain, install and check out the hardware before the final debugging stages of program development can begin, and interference with normal mill operation during such final testing. This work reports on an alternative to the usual procedure. Here both compilation and execution bugs are eliminated from the application program before hardware installation by testing the control program against a reasonable dynamic simulation of the entire process. Thus, software development can be completed before the target mini is installed. Such off-line development requires a reasonably accurate mathematical model for the entire process system as well as a suitable simulation package for communication between the simulated environment and the minicomputer application program. Specific data describing the design configurations and dimensions of the mills, cyclones, sumps, pump characteristics and analog controller configuration were supplied by ANAMAX for a grinding division consisting of a rod mill followed by two ball mills in parallel. This information was used to set up a plausible model structure. Steady state ANAMAX data on particle size analysis at various points in the circuit and corresponding values of flow rates, pump speeds, sump heights and slurry densities were used for model parameterization. The preferred operating control strategy - "best grind at operator-set rod mill feed rate" - was set by ANAMAX. An inferential particle size analysis technique using the cyclone cluster as an on-line particle size sensor was used in a novel control strategy_ to achieve the stated objective. Two disturbances common in the ANAMAX circuits - rod mill scoop pluggage and shut down/start up of one of the ball mills - were studied in detail. This report out- lines the steps in system development and testing and the results obtained.

Jan 1, 1974

By Merih Celasun

The literature in operations research centered on mineral exploration has been comparatively limited in view of the significant implications of mineral discoveries upon the national economies in general and mineral industries in particular. Much of what has been published is of somewhat unsure academic nature, indicating to a certain extent the scarcity of industrial applications. Mineral exploration activities present quite difficult operational and conceptual problems. The purpose of this paper is to discuss the principal characteristics of decision problems encountered in planning an exploration program, to indicate an optimization approach to a certain class of allocation problems, and to suggest directions for future research effort.

Jan 1, 1962