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By Susumu Ukita

We have developed first a conveyor belt for transporting large lumps, i.e. Rock Belt successfully, in June 1976. The First Rock Belt had been delivered to Myodani site of Kobe City Developing Board in Japan, and its' successful operation has attract keen interests in customers from over the world as well as Japan. However, this First Rock Belt was removed in arch '81, viewing it has satisfactory expired its service life of about five-year, and also original location of this belt become to be far from the site due to long-years earth collecting work. Taking this opportunity, we introduce the Second Rock Belt applied for Rock Belt Loader as ell as three types of application of our Rock Belt working for rationalization of quarry of major company in Japan, and, view the prospect of Rock Belt:

Jan 1, 1981

By William W. Leathen

Acid mine drainage became a reality through the exposure of the first bituminous coal seam, either by man or by nature. At first the small amount of acid formed was quickly and efficiently neutralized by basic rock strata and by neutral or alkaline water. As soon as extensive mining operations overtaxed nature's own defensive measures, acid mine drainage became a problem of concern to government and the coal industry. It was the purpose of the studies conducted at Mellon Institute to accumulate knowledge, both applied and fundamental, relating to the formation and disposal of acid mine effluents. It was during this program that the microbiology of acid mine water was studied. Most bituminous coal mine effluents are highly acidic and contain, along with other ions, high concentrations of ferrous iron. The acid is sulfuric, and. the iron is present as the sulfate; both are the oxidation products of iron sulfides (FeS2) which are present in the form of pyrites, marcasites, or other sulfuritic minerals. The oxidation occurs, in the absence of moisture, according to the following reaction: [ ]

Jan 1, 1959

By Dave D. Ferris

Today the coal industry is beginning to use some very fundamental economic evaluations to determine the most economical circuit to produce a specified saleable product. The fundamental economic methods used are standard return on investment and net present value calculations. By utilizing these economical evaluations, one can justify a larger capital expenditure and realize more return for an investment over the life of a coal property.

Jan 1, 1983

By Randal J. Barnes

A system, such as a mine production system or a mine ventilation system which includes the movement of commodities or some material between decision points may, in many instances, be effectively modelled as a network. Mining has often been characterized as primarily a materials handling function. To a great extent this is true, even though it is an over simplification of all the activities involved in a mining operation. Accepting the materials handling characterization of a mining operation permits the extension of the characterization to a flow process. That is, the ore flows from the mining face through the mining phase (excavation & loading, hauling, dumping) through the milling phase (crushing, grinding, recovery) through the smelter phase and finally to marketing. With this concept it is possible to depict a mining operation as a simple network. For example consider an operation consisting of two mines (A and B) with mills at each mine (MA and MB) with the possibility open to treat ore from mine b at mill NB, but it is not feasible to treat mine B ore at MA. The product of both mills is sold.

Jan 1, 1983

By Daniel T. Hegyan

The employment of continuous rotary vacuum disc filters to filter refuse from the fine coal washing circuits has been increasing as it has become more important to close the water circuits and eliminate sludge holding ponds. This paper will discuss our past experience filtering refuse, effects of solids concentration in the filter feed, use of polymer flocculation aids, effect of flocculation devices, and effects of particle size and ash content on the filtration rate. Detailed tests were performed on existing installations utilizing coal refuse filters to determine optimum flocculant dosage, solids concentration, and disc rotation speed to form a dischargeable cake. Information was also obtained showing effect of flocculant addition on the moisture of the filter cake. Our test work has shown that the continuous filtration dry cake rates for fine coal refuse correlates very well with the data developed and presented by Silverblatt and Dahlstrom1 except that the curves have moved up the scale by use of polymer flocculant additions. These polymers were not available at that writing. Finally, our tests also confirmed the general premise stated by S. K. Mishra2 that controlled additions of polymer flocculants will reduce filter refuse cake moistures somewhat.

Jan 1, 1974

By J. S. Orphanos

The requirements for controlling air and stream pollution are a most timely subject for all concerned people. The coal industry has taken great measures to reduce both types of pollution. Through the use of more efficient scrubbing equipment on their thermal dryers, pollution has been considerably reduced. In many cases, the complete elimination of thermal drying by using centrifugal dryers to dewater fine coal products and meet customer specifications has completely eliminated air pollution from this source. To help eliminate stream pollution and the hazards created by tailing ponds, the coal industry is using centrifugal dewatering equipment. Use of centrifugals to dewater fine refuse for disposal would eliminate refuse ponds or extend their life. In doing this effectively and economically, preparation plants have the option of recycling the clarified water to close the water circuit or of discharging the water into receiving streams with the assurance that it contains an acceptable amount of refuse solids.

Jan 1, 1974

By W. E. Horst

In Part I of this paper we describe two techniques that were employed in the development of mathematical descriptions of the size reduction process which takes place in a ball mill. In Part II we show how the comminution model was imbedded in a process model to effect steady-state and dynamic simulation of a closed-circuit grinding operation. Increasing emphasis is being placed on development of approaches whereby the essential characteristics of a process can be succinctly represented in terms of a mathematical description of the relationships that exist among important process variables. This activity, commonly known as mathematical modeling, predates modern electronic computers: however, these computers with their tremendous computational capability have given new impetus to the whole field. Although the computer is quite helpful in the development of mathematical models, the real value to the engineer lies in the fact that computers represent such a powerful tool for simulating systems described by mathematical models. As a consequence, engineers may simulate and thereby study the behavior of complex. interacting, systems over a broad range of process variables and configurations once appropriate process models have been developed for the sequence of steps comprising the process.

Jan 1, 1970

By M. V. K. Reddy

A differential flotation process for recovery of molybdenite from chalcopyrite concentrates produced at Rakha Copper Concentrator, Bihar, India has been developed. The flowsheet is simple, and relatively inexpensive and yields a concentrate assaying not less than 45% Mo at a recovery of minimum 65%, starting from chalcopyrite concentrate assaying 0.4% Mo. The consumption of the main depressant used, sodium sulphide is not more than 25 kg/t of copper concentrate processed without steaming; and with steaming the consumption was brought dorm to less than 12 kg/t of concentrate. Further reduction is possible by optimization of steaming parameters. Based on laboratory experimental results, further tests were conducted on concentrator site and process design parameters were established for design of commercial plant.

Jan 1, 1982

The effect of addition of a flotation collector (dodecylammonium chloride) on grinding of quartz has been studied. The data obtained are correlated with the results of tests conducted under similar chemical conditions to study influence of these additives on relevant basic sub-processes (primary breakage, pulp fluidity, and dispersion and flocculation of ground products). Such correlations suggest that the role of chemical additives in grinding is determined by their cumulative influence on the above mentioned basic properties of the system.

Jan 1, 1982

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By M. G. Ayat

In the previous work (1,2), initial developments in a novel tracing technique employing specifically prepared trace particiles were fully described. The synthetic tracers produced proved to represent coal particles in specific gravity based coal washing equipment in this work, a detection system has been developed that can detect the artificial tracers in the product or refuse part of the density-separating coal cleaning units and thus indicate the performance characteristics of the circuit. This system could not only be a simple, accurate, and inexpensive replacement for the usual time-consuming washability analysis, but it could also be used for diagnostic purposes in coal separatory devices.

Jan 1, 1987

By T. Cantwell

Techniques useful in operations, analysis are applied to the problem of planning an exploration program. The model used treats mineral exploration as a Markov process, and maximization of gain is the criteria determining the optimum program. The mathematical description of the model and the optimization are first worked out. Application of the mathematics to several simple examples is given. Finally, comparison of the data necessary to use this operations analysis with the available data shows that the method can only be a guide to planning an exploration program.

Jan 1, 1962

By Patzen Wu, Chao-Ming Tsai, Shaw-Chii Wu, Yuan Lin

INTRODUCTION The development of nuclear industry in Taiwan requires an increasing supply of uranium. Uranium recovery from phosphate ores, becomes an important item of the R & D programs. Many countries have already started such a program. USA has set up an industrial-scale production plant; South Africa, Israel, Morocco and other countries have also engaged in the development of extraction technology of uranium from phosphate ores and started setting up the production plant. In Taiwan, a feasibility study of establishing the production plant was started in 1977. A pilot plant was completed, tested, and operated in 1979. The main source material. - phosphate ores is obtained from China Phosphate Company. The annual yield of the pilot plant has been planned to be one ton of ammonium diuranate (ADU). The Health Physics Division of Institute of Nuclear Energy Research (INER), Atomic Energy Council of Republic of China (ROC AEC), is responsible for the radiation safety control of the plant. The purpose of the radiation safety control is to collect radiation safety information of the plant of this type, to evaluate possible radiation hazards to the personnel, and to analyze the radiation safety of the immediate environment adjacent to the plant. Furthermore, the information and experience obtained are used as the basis for applying radiation safety control to the production plant. The main emphases of the radiation safety control are therefore the arrangement of radiation safety control areas and the collection and evaluation of the health physics data. This report includes the past one and half years' experiences of the radiation safety control of the pilot plant, the planning of the production plant with an annual yield of 10 ton ADU, and considerations given in improving the radiation safety control of the production plant. PILOT PLANT AND ITS OPERATION PROCESS The pilot plant occupies an area of 350 m2 and is a two-story rectangular building. Exits are provided by a front and a rear door. An additional small door at the central right side of the building is connected to the maintenance area located outside the main building. The interior of the building is divided into interconnected offices, laboratories and process area (Figs. 1 and 2). A stairway to the process area of the second floor is located in the central part of the first floor. The second floor offices are accessible by the additional front and rear stairways. The main process area of the first floor is furnished with plastic floor, and the second floor with poriferous iron-grid floor. The building is not furnished with centralized air-conditioning system. Individual air conditioners are, however, available to some laboratories. Because the back door of the building is frequently open, the product storage room is provided with a blower to maintain good ventilation. Natural uranium contents of phosphoric acid solution vary in the range from 0.07 to 0.11 kg/m3. The process consists mainly of the uranium concentration cycle and the purification cycle. A flow diagram of the process is shown in Fig. 3. CONSIDERATIONS GIVEN FOR RADIATION SAFETY CONTROL AND THE ESTABLISHMENT OF RADIATION CONTROLLED AREAS The radiation safety control of the pilot plant is carried out on the basis of the considerations listed below:1,2 1) Since the wet process is adopted, and the flow of the radioactive material is confined to closed pipes and containers, air contamination is therefore not too much of concern. 2) The concentrations of radioactive material of the whole process are mostly less than 10 ppm. An exception is the final ADU product after precipitation and centrifugal separation, which contains up to 50% natural uranium. It is therefore necessary to apply radiation safety control to the process area where

Jan 1, 1981

By M. D. Flavel

Testing methods are described to help in decisions of selecting the most viable comminution circuits. The authors present a comparison evaluation based on numerous studies to help make initial choices for feasibility evaluations. An update summary of completed Bond grindability and Abrasion Index testwork at Allis-Chalmers Process Research Test Center for all materials is included. "What is the best circuit to comminute primary crusher product to make beneficiation feed?" This frequently asked question has the implication that there is one circuit which is universally the right circuit. The answer has been sought ever since it has been necessary to break rock to liberate entrapped mineral values. With every new contribution to the art and the science of comminution, the scope of the discussions broaden. It is not even possible to define what the abstract term best means.

Jan 1, 1981

By James K. A. Harral

The growing national concern over energy has aroused a great deal of interest in the most efficient and least costly way to use our remaining fossil fuel reserves. A number of studies have been published which compare the overall thermal efficiency and cost of gas and electric energy. These studies have been carried out by a wide variety of organizations including Oak Ridge National Laboratory, The Rand Corporation, The Stanford Research Institute, and The Institute of Gas Technology. This paper is an attempt, by PGandE, a large combined gas and electric utility serving most of the northern and parts of central California, to compare the cost and efficiency of gas and electric energy for certain residential appliances using actual operating data and financial statistics for the year 1974, and thereby develop some guidelines for future energy developments utilizing these limited fossil resources. The appliances chosen for the study were kitchen ranges, clothes dryers, hot water and space heaters. These appliances were selected because they can be served with either gas or electricity and they account for approximately one-third of PGandE's total residential electric sales and nearly all of PGandE's residential gas sales.

Jan 1, 1976

This paper presents a method for evaluating the economic feasibility of solution mining a hypothetical uranium roll-front deposit. It is assumed the wellfield will be operated in a prudent manner and that leaching tests were performed in depth in both lab and field (push-pull) prior to startup. Leach test results are reduced to two important parameters and used as the basis for solution mining a wellfield. This case study assumes a 10 mil- lion-lb uranium deposit with 40 possible small wellfields; four are kept in operation simultaneously until the deposit is depleted. The wellfields have different ore reserves and grades, lixiviant circulation rates, leach rates, and peak concentrations, and thus the daily uranium production will vary. Daily production is used to assess the profitability of a particular lixiviant and the mode of well- field operation in light of realistic market price estimates. The mathematical procedure is simple and straightforward, based on reasonable in-situ leaching relationships as well as accepted accounting practices.

Jan 1, 1985

By Robert S. Hedin, David M. Hyman

Acid mine drainage (AMD) is a common water pollution problem on active and abandoned coal mine sites in the eastern United States. AMD forms when surface mining brings unweathered pyrite-containing rocks to the surface or when deep mining allows oxygen to contact buried pyritic strata. In the absence of neutralizing compounds, the drainage that results can be extremely acidic and contaminated with dissolved iron, manganese, and sulfate. Drainages with pH < 3.0 and concentrations of sulfate greater than 1,000 mg/L, iron greater than 50 mg/L, and manganese greater than 10 mg/L are common. Where water flows through alkaline materials (such as limestone) before surfacing, the drainage is less acidic and occasionally circumneutral, but it can still contain high concentrations of sulfate and metals. Current water quality standards in the United States require that mine discharges have a pH between 6 and 9, total iron concentration less than 3.0 mg/L, and manganese less than 2.0 mg/L. At thousands of active and inactive mine sites, drainage does not meet these standards and is being treated before discharge by the mining company. At thousands of other sites, which were abandoned prior to the enactment of water pollution laws or were operated by companies that have gone bankrupt, untreated AMD is polluting receiving water systems. The standard mine drainage treatment system involves the addition of a1 kal ine chemicals to the water, which raises the pH and cause metals to precipitate in a settling pond. These systems are expensive, often costing tens or hundreds of thousands of dollars per year for chemicals, operation, maintenance, and disposal of the metal- laden sludge. Because the drainage on many sites will likely be contaminated for decades, there is financial incentive to find alternative water treatment systems. In the last five years, many mining companies and engineering firms have experimented with the construction of wetland treatment systems. Very few of the several hundred wetland systems that have been built are performing well enough to justify total abandonment of chemical treatment. Nonetheless, systems continue to be built because the mining companies have found that wetlands can reduce their AMD treatment costs. It is also their hope that further research and development will eventually result in systems that will completely rep1 ace chemical treatment and offer long term performance at minimal cost. The Bureau of Mines has been actively involved, from a research perspective, with this approach to AMD treatment since its inception. In this paper, the status of constructed wetland technology is discussed with respect to the construction and performance of systems, chemical and biological processes that affect AMD chemistry within constructed wetlands, and the future of this technology as perceived by the Bureau of Mines. ORIGINAL OBSERVATIONS The constructed wetland concept has its roots in observations of natural Sphaqnum peat wetlands that received acid mine drainage and, instead of being adversely affected, appeared to cause an amelioration of the polluted water (Huntsman et al. 1978; Wieder and Lang 1982). These observations instigated the idea that wet1 and systems might be used for the intentional treatment of mine drainage. Because the discharge of AMD into a natural wetland is prohibited in the U.S. by several laws, it has been necessary to construct wetlands which act solely as water treatment systems. Initially, most wetland research and construction efforts mimicked the original observations by utilizing Sphaqnum moss and peat. Despite promising laboratory results (Kleinmann et al. 1983; Tarleton et al. 1984; Burris et al. 1984; Gerber et al. 1985), virtually all field tests of Sphasnum-dominated constructed wetlands failed to provide sufficient water treatment for more than several months. Sphasnum proved quite sensitive to the stresses associated with transplanting, abrupt changes in water chemistry, excessive or insufficient water depth, and

Jan 1, 1989

By James J. Scott

Shale formations are the Nemesis of the Mining Engineer. Shales react to changes in environment in the most unusual and unpredictable manner. Increase in temperature may cause spalling, increase moisture and compression induced fractures may occur, and if a full face is exposed it may deteriorate due to atmospheric exposure. Combine only small amounts of shale in layered fashion with hard brittle competent rock and the whole structure may be fractured and fail due to stresses generated in and around the shale. In this paper the author will discuss failure mechanisms encountered under various field conditions and remedial action which may be employed by the engineer.

Jan 1, 1969

By H. Nakazawa

Galvanic contact, occurring between electricall y conducting minerals in flotation pulps, may affect the nature of mineral surfaces and influence their floatabilities. Rest potential and galvanic current measurements were made on an electrode combination of pyrite and pyrrhotite under nitrogen, air and oxygen aeration conditions, and the results were correlated with their oxygen-consuming characteristics and flotation behaviors. The galvanic contact improved the floatability of pyrrhotite, but adversely affected that of pyrite. Auger electron spectroscopy, x-ray photoelectron spectroscopy and scanning electron microscopy indicated that the formation of hydroxide or oxide and sulfate species of iron on pyrrhotite decreased whereas that on pyrite increased when these minerals were held in contact. An electrochemical mechanism was proposed for the observed behaviors.

Jan 1, 1985