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By John H. Bassarear

By 1968 Cyprus Pima was milling 38,000 tpd of copper ore using a conventional flowsheet consisting of three stages of crushing rod mills and ball mills. A 15,000 tpd expansion was put on stream late in 1971 using primary crushing, semiautogenous mills, and ball mills. Identical ore is treated in both concentrators. This paper shows the weight and life of each individual liner for each crusher and each mill over a four year period from 1974-1977. Power and media consumption are shown for the same period and a comparison is made between the two reduction methods.

Jan 1, 1980

By I. A. Tinto

Labrador City is located in the southwestern portion of Newfoundland-Labrador, approximately 965 kilometers north-east of Montreal. The mine and beneficiation complex of the Iron Ore Company of Canada, known as the Carol Project, is situated 535 metres above sea level in a climatic region characterized by cold winters and short, cool summers. History The iron Ore Company of Canada commenced work in the area in 1949, however, it was not until 1958 that the decision was made to proceed with mining operations. The ore body consists of Specular Hematite (Fe203) and Magnetite (Fe304) with small quantities of Limonite and Geothite. The average grade of the ore bodies is 39% iron.

Jan 1, 1985

By Burke Trafton

An earlier paper1 introduced a rapid solution for mine ventilation network problems, employing the digital computer. In this paper, refinements and additions to the computer program which expand its scope of application and a solution to a ventilation network having a coal-mine configuration are presented. Specifically, the revised program--written in FORTRAN for the IBM 7074 computer in Penn State's Computation Center--is applicable to any mine ventilation network employing natural splitting and having its fan located externally. It accomplishes the following; 1. Distributes an assumed total quantity of air flow among all air- ways of the network, performing iterations until an acceptable level of error is attained and the flow in each airway is known. 2, Computes the pressure drop (head loss) in all airways and the overall network and mine head losses. 3. Determines the operating point for the mine and a given fan, adjusting all air flows and head losses to the actual values.

Jan 1, 1964

By Robert W. Row

Advanced physical coal cleaning processes that are now under development may remove significantly greater fractions of pyritic sulfur and ash than do commercial coal cleaning processes at comparable heating value recoveries. These processes may be useful for reducing sulfur dioxide emissions from electric utilities and other emission sources. However, little work has been done to determine their applicability to any major coal market. The northeastern states of the United States are interested in burning more coal, but with further sulfur dioxide emission restrictions. Their nearest coal sources are relatively high sulfur Northern Appalachian coals. The project discussed in this paper, which is scheduled to be completed in June 1985, has the objective of technically and economically evaluating various coal supply scenarios involving five selected advanced physical coal cleaning processes; and comparing the economics of them with alternative fuel supply options open to the northeastern users.

Jan 1, 1985

By R. E. Williams

University of Idaho scientists research under U.S. Bureau of Mines Cooperative Agreement C0278001 constitutes a complex hydrogeological, hydrochemical and metallurgical mine waste management project at an existing Superfund site. Technologies that may prove useful for the extraction of dissolved metals from acid mine water and solid wastes include lixiviation and biosorption. Acid mine water is the major, long-term problem in the valley. We are attempting to delineate the major sources of ground water recharge which feed the acid mine drainage and their hydraulic properties. Grouting of recharge areas may facilitate minimizing the production of acid mine drainage if recharge pathways can be identified.

Jan 1, 1990

By Sarah Vest, Richard Sherman, Leo Martin

In 1988 a major exploration program was undertaken to determine the characteristics of the rock and soil for a 7.6 m diameter sea outfall tunnel beneath Boston Harbor out into Massachusetts Bay. The diffuser discharge location had been mandated by the EPA to a 10 sq. km area of seafloor connected to the proposed Deer Island Treatment Facility by a 14.5 km tunnel corridor. Geophysical surveys, deep rock borings, and laboratory testing, provided the information for the conceptual design. The program identified the range in material types and parameters to prove feasibility of a TBM driven tunnel and to locate the optimum alignment and depth.

Jan 1, 1991

By James M. Krese

The West Kentucky Division of Island Creek Coal Company, which is a wholly owned subsidiary of Occidental Petroleum Corporation, operates the new Hamilton Mine. It is located six miles West of Morganfield, Kentucky, in the Northwest section of Union County, adjacent to the Ohio River in Lock 50. On July 15, 1968, a unique new coal conveying system was put in operation. This system consists of eight conveyor units carrying coal from the bottom of the mine slope ultimately to barges on the Ohio River. It is over two miles in length and has a total of 3175 connected horsepower. The river loading conveyor is the longest 72" wide conveyor in operation in this country.

Jan 1, 1969

By Vas Choudhry

The eighties are likely to witness the first commercial-size coal-to-gasoline plant(s) in the U.S., although uncertainty regarding crude prices and cautious involvement of the Federal Government in the synfuels development are evident. The formation of The U.S. Synthetic Fuels Corporation with passage of the Energy Security Act is projected to pave the way for some of the projects on a moderate scale. The corporate objectives (1) are to provide funds for supporting a number of feasibility studies and loan guarantees for the construction of at least some commercial-size plants and the possibility of product price supports or purchase commitments. There are a number of coal conversion processes (2) currently under evaluation for producing either gaseous or liquid plus gaseous fuels, the other processes such as SRC I are for producing desulfurized deashed clean solid fuel for commercial use.

Jan 1, 1982

By T. Good

Twin roll sizers are neither compactly designed machines nor are they configured to accommodate underground mobility; in fact, twin roll sizers leave room for improvement in many aspects of the design. The DRC1200 capitalizes on the weaknesses of these machines to make a more productive, easily maintained, and compact twin roll sizer than current market offerings. These strides were made through the inception of the Hard Rock Extraction System (HRXS), which requires a mobile sizer as part of the system. After use of a third party sizer on the HRXS, potential improvements were evident. These improvements include improved structural design to reduce overall footprint and an optimized design to reduce operating cost.

Feb 23, 2014

By W. K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating the electrochemistry of mineral flotation. A significant need in this area is greater reliability of sensors. The USBM is testing electrolytic methods to clean and condition redox-sensing electrodes to improve the reliability and extend the service life of these instruments in the harsh physical and chemical environment of mineral processing slurries. A novel method for removing scale from fouled electrodes has been developed that includes anodic polarization to 1.2 V versus the Ag/AgCl reference potential, followed by brief potentiodynamic conditioning. Laboratory results show that this technique removes calcarious deposits from gold sensing electrodes and returns the electrode to useful service within approximately 10 min. Mechanical abrasion to remove the scale is thereby avoided.

Jan 1, 1994

By P. A. Rittenhouse

Reserves of potash are more than adequate to meet future world demand for this primary fertilizer nutrient. The bulk of both reserves and current production is located in only a few countries. Recent attention has focused on potential development of smaller reserves to supply local markets in developing areas of the world. However, most new capacity in the next decade will be built in countries with large current production and reserves. The paper reviews current and future projects that will add to the world supply of potash.

Jan 1, 1985

By A. W. Khair

This paper presents an engineering approach to solve a complex ground control problem at reduced cost, allowing the mine to be operated safely and economically. The mine has experienced serious and complicated cutter roof problem in the entries. This cutler roof problem has delayed the advance of the entry development considerably and cost of these entries is very high due to the requirement of very heavy artificial supports. The analysis includes assessment of the cause of cutter roof and step by step action taken to improve the entry condition through appropriate longwall panel entry design and roof support system. The approach for solving the problem was two-fold: 1) to apply yield pillar concept in order to reduce the effects of in-situ horizontal stress in the roof strata and 2) to find an effective way to reinforce the roof strata and to support the fractured roof and avoid caving.

Jan 1, 1990

By S. K. Kawatra

Outokumpu Electronics has designed a new on-line coal slurry ash analyzer, based on an instrument developed at Michigan Technological University. The primary goal was to build an accurate instrument at the lowest possible cost. The instrument determines ash content from measurements of X-ray backscatter, iron K, fluorescence, and low-energy y-ray absorption. It is capable of measuring the ash content with a standard error of 1.1% ash over an analysis range of 9-21% ash and 7-22% solids. The analyzer was tested on coals from United States, Poland, Great Britain and the USSR.

Jan 1, 1993

By Henry H. Rubin

Rubber and its contributions to the economic solutions of environmental problems in the minerals industry. The intelligent applications of "Rubber" to systems of noise abatement, vibration isolation, dust containment, weak and corrosion resistance has proven economically beneficial. Intelligent application requires a thorough understanding of the nature of the material, knowledge of the process wherein it is going to be applied, and consideration of the environmental conditions in which it will serve, for these determine the proper amount, type, compound and configuration for an economically successful application.

Jan 1, 1979

"The Industrial Comminution Efficiency (ICE) working group, part of the Global Mining Standards and Guidelines Group (GMSG) has engaged a large number of industry professionals representing mining companies, equipment vendors, consultants and metallurgical laboratories with interests and capabilities in the comminution field. These participants have collaborated to develop three guidelines for the assessment of the efficiency of mineral comminution circuits. Two of these guidelines deal specifically with power based modelling techniques to quantify energy efficiency using widely practiced techniques, those developed by Bond (1961), Rowland and McIvor (2009), and Morrell (2009). The third guideline deals with the sampling and surveying of grinding circuits as is required to provide the necessary information, at appropriate quality, to furnish the efficiency analysis promoted by the first two guidelines. This preprint will focus on the Guideline on Methods to Survey and Sample Grinding Circuits, which is currently in the final stages of peer review and finalization by the GMSG. INTRODUCTION It is important to make a clear distinction on the scope of work of the GMSG guideline for sampling grinding circuits. Many mineral processing practitioners are familiar with the sampling and surveying of comminution circuits, in particular grinding circuits, for performance diagnosis and the identification of optimization potential. These surveys often provide information for population balance modelling of individual comminution and classification unit processes, and as a result require a large amount of information to calibrate and validate the unit models. As a result these surveys are labour intensive, somewhat expensive depending on internal capabilities of the mine site or company, and have a long time span from initial planning to final reporting. They also require a high level of expertise to process the survey data, simulate the circuit and make sensible recommendations on follow up actions. As a result of these factors full grinding circuit surveys are not a common occurrence at a large number of facilities, and several years may pass before follow up surveys are conducted. In the ensuing gap between surveys, the efficiency of the grinding circuit must often be taken on faith, and this is considered an unacceptable lapse in an environment of strained natural resources and low commodity prices. To support the rapid and productive energy efficiency analysis being promoted by the ICE working group, a much simplified survey and analysis process is required. The process reflected in the GMSG guideline is indeed more conducive to frequent analysis, at a skill level that is well within the capabilities of the average plant metallurgist. As a result it becomes feasible to conduct mini-surveys of plant performance, which can be used to quickly and precisely diagnose the high level impact of process changes. It can also be manipulated by experienced practitioner to provide sufficient information for modelling of the circuit to estimate the impact of process changes, supporting an initial rate and rank exercise to focus plant optimization efforts."

Jan 1, 2016

By Roland W. Merwin

The Bureau of Mines has studied the possibility of using the heap leaching process for treating the gold ores in the sedimentary beds of northeastern Nevada. This paper summarizes all available information on the technical and economic feasibility of heap leaching oxidized ores from these beds, past industry application of vat leaching, results of recent Bureau of Mines and industry tests on heap leaching ores from this region, and requirements for planning the proper application of heap leaching. Preliminary tests on representative samples of ores from the region show that a satisfactory recovery of gold can be obtained by heap leaching the ores with cyanide at a relatively coarse size. Significant deposits of gold ore occur in sedimentary beds of various locations over an extended area 40 miles wide and 200 miles long in northeastern Nevada. The area is centered 40 miles west of and runs parallel to the leading edge of the Roberts Mountain thrust fault system, a prominent geologic feature in the area. The general locations of past and present gold mining operations are shown in figure 1. (slide 1)

Jan 1, 1969

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By Lauren W. Choate

Wollastonite, a calcium metasilicate, derives its name from the man who discovered the mineral, Doctor William H. Wollaston, an English scientist. OCCURENCE Occurences of the mineral have been noted in Finland, Switzerland, Russia, Japan, Mexico and in the United States in Texas, California, Arizona, and New York. The only commercial deposit now being exploited is at Willsboro, New York. It is mined and processed by the Cabot Corporation whose home offices are in Boston, Massachusetts.

Jan 1, 1964

By Armin C. Supp

Since 1975, about a dozen high capacity flotation plants have been installed in the Ruhr district. Depending on the size of the preparation plants, the design capacity of the flotation section is between 100 - 150 t/h. The flotation units generally comprise rougher and cleaner stages in which 5 to 6 or 4 to 5 agitators respectively are arranged in line. The unit volume allocated to each agitator is up to 16 m3. The type of flotation machines, the design of these plants and their instrumen¬tation and control equipment are described in detail. The run of mine coal in the Ruhr district is characterized by a wide variety of the volatile matter. Generally, a distinction must be made between coals with more than 30 - 35% V.M., which are preferably used in power station, and coal with lower V.M. content, which are preferably used as coke-oven feed. The difference between these coals in respect to grain-size distribution, ash cotent and flotation properties will also be described in detail.

Jan 1, 1985

By Bernard Scheiner

A number of wells were drilled at two phosphogypsum stacks, one at P-21 owned by IMC and the other at Agrico's South Pierce Stack. Each well was sampled, and composites representing 5-ft increments were leached with synthetic rainwater to determine the extent of metal and nonmetal migration. To simulate what was occurring in the stack, composite samples were placed in a column, so that the column represented the stack in miniature form. Leaching experiments showed that both metals and nonmetals moved down the column when water was added to the top of the column. Data obtained from P-21 showed that with time the concentration of metals and nonmetals reached equilibrium values. The concentration of Ca, SO4, F, Si, and PO4 were -600 ppm,~1,500 ppm, 32 ppm, 14 ppm, and 22 ppm, respectively. Column leaching of South Pierce material, representing 0 to 55 ft of stack, showed that after 355 in. of water, the stack was near equilibrium values down to the 33-ft level. With continued addition of water, the portion of the stack at equilibrium would continue to increase and eventually reach the values observed for P-21. The test showed that the sulfate concentration of the effluent from the stack would never reach the USEPA standard value of 250 ppm. During the leaching test, it was determined that the permeability of the phosphogypsum in the columns was 0.000103 cm/sec. This number was used in the modeling. The data obtained from the leaching experiments cast some doubt on the practice of entombment now being practiced for closure of phosphogypsum stacks. The data clearly shows that with time, the amount of material leaching from the stack is low in concentration, with only the calcium and sulfate at higher levels. When a stack is closed at an existing operating plant, allowing rainwater to fall on the stack and capturing the solution in the existing pond system would eliminate the need for covering the stack, since with time the closed stack would continue to leach and at some point reach the equilibrium values of the P-21 stack. Entombment means that the leachable material in the stack will always be there and will require monitoring forever. Allowing rainwater to decontaminate the stack may be the best environmental solution to the problem.

Jan 1, 1999