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By Fred Woodcock, A. R. Laplante

A laboratory technique is presented that uses the Knelson Concentrator and a relatively small sample to predict the amenability of a given gold ore to gravity recovery. The technique applies to develop­mental orebodies as well as retrofitting existing plants. Justification for this approach is discussed. Actual results of the technique applied to existing and prospective circuits are presented and discussed.

Jan 1, 1993

By J. C. Yingling, R. Kumar, J. Sottile

The capability for on-line measurement of the quality characteristics of conveyed coal now enables mine operators to take advantage of the inherent heterogeneity of those streams and split them into wash and no-wash stocks. Relative to processing the entire stream, this reduces the amount of coal that must be washed at the mine and, thereby reducing processing costs, recovery losses and refuse-genera¬tion levels. In this paper, new ap¬proaches for optimal control of the segregation process using time-se¬ries models and empirical distribu¬tions are presented and demon¬strated using field data.

Jan 1, 2000

By Lester F. Sanford

Located in the Santa Cruz Mountains eight miles north of the City of Santa Cruz and inland from the coast, lies a typical beach sand consisting of quartz and feldspar grains of the Santa Harguerita formation of the middle tertiary age, Reserves of over twenty-five million tons of this sand form the deposit presently being harvested by Pacific Cement & Aggregates, a Division of Lone Star Cement Corporation. The deposit ranges from 350 to 700 feet above sea level and varies from two percent passing a 200 mesh screen to ten percent retained on a ¼ inch screen (see Figure '#l) In 1929 the first sand plant went into operation at this site. It was replaced by a new plant in 1937. This plant continued operation until the middle of 1965 when replaced by the modern plant described in this paper.

Jan 1, 1967

By Louis G. Silano, Aram Grigoryan

Parsons Brinckerhoff is providing engineering services for the Atlantic Avenue Station Complex Rehabilitation and Passageway Reconstruction for New York City Transit. Project reflects current realities and challenges of underground excavation, support, and construction under operating subway tracks and platforms, and under major transportation hub, comprising three subway stations, railroad terminal station, and busy street intersection. The construction requires extensive underpinning of subway structures and operating tracks. This Paper addresses engineering challenges of IRT subway station rehabilitation and passageway reconstruction without interruption of transit operations and street traffic. Total construction cost of the Project is $ 105,000,000.

Jan 1, 2003

By A. Giblett, J. Shuttleworth, R. Dunne

In a previous paper (Dunne, Martins, Goulsbra, Chittenden 1997), the new gravity circuits at Telfer Gold Mine, which incor­porate Knelson centrifugal separators in both the sulphide and oxides, are described. The advantages of the new circuits over the replaced spiral ( oxide circuit) and jig (sulphide circuit) were discussed, as were the improvements in gravity gold recovety. It is of note that the installation of the centrifugal separators in themselves did not result in increased gold recovery. The realisa­tion that changes in gold room practices are required to take advan­tage of the increased fine gold recovery from the Knelson concen­trator was an important step towards improved gravity gold recov­ery. This was achieved by increasing the time taken to treat the Knelson concentrate on the shaking table in the gold room. Although this increased gold recove1y, it was found that the table tailings, especially from the sulphide circuit, still contained high values of gold. In an effort to ascertain ways in which gravity gold recovery could be fu1iher improved, a sample of the sulphide table tailings was sent to the Oretest Laboratory in Perth for testwork. The results from this program are discussed in this paper.

Jan 1, 1998

By S. M. Alvarez

The Moon Creek Reclamation Project provides a case study in the development of creative cleanup solutions for an abandoned lead and zinc mine and mill site located in northern Idaho. Innovative design features include construction of a 88,000 cubic yard combined waste containment facility on soft in-situ tailings, water-balance cap, limestone gravel drains, a geocell mattress for stability, and a below-grade scour protection berm. The stream, including a wetlands buffer, will be relocated within an existing road alignment and rehabilitated to provide trout habitat. These elements allow for the integration of reclamation and stabilization measures into an effective site design.

Jan 1, 1999

By P. Johnson, G. E. Jones, G. K. Hoffman, C. B. Krueger, J. S. Raugust, M. Wilks, V. T. McLemore

The NMBGMR is slowly converting historical data into a relational database using Microsoft Access 97. The purpose of this database is to provide data on districts, mines, and mills in New Mexico to government agencies, public organizations, industry, and citizens to make informed decisions about resource development, resource management, water supplies, environmental impacts, hazard assessment, and waste disposal. Once the data are entered into the database with locations, the data can easily be converted to GIS format for displaying as different map layers.

Jan 1, 2003

By Terry I. Mudder, Michael M. Botz

In general, the cyanidation of silver ores requires higher con­centrations of cyanide in comparison to gold ores to affect simi­lar leaching rates and metal recoveries. The requirement for high cyanide concentrations in a silver ore leaching circuit may translate into higher operating costs, however with operation of an acidification-volatilization-reabsorption (AVR) plant to recover and recycle tailings cyanide, cyanide consumptions can be significantly reduced. At each of the currently operating AVR plants in the world, overall cyanide consumptions have been reduced by approximately one-half by recovering and recycling tailings cyanide. In addition, the AVR plants have reduced tail­ings cyanide concentrations to less than 20 to 30 mg/L WAD cyanide and reduced potential adverse impacts to wildlife in the tailings impoundments. This paper presents an analysis of the application of A YR to a silver ore leaching operation which has a CCD/Merrill-Crowe circuit included in the metallurgical plant.

Jan 1, 1998

By HONGWEI YANG, Lili Zhang

Copper slag is mainly used in cutting tools, abrasives, asphalt pavement, road construction, and in the production of concrete as an alternative to sand and cement [1]. As a renewable resource, only about 15-20 percent of the slag is used for these applications, and the dumping or disposal of surplus unused slag results in waste of a certain amount of usable metal in the feedstock [2]. In this work, the oxidation behavior of copper smelting slag under nonisothermal condition is studied using data obtained by the thermogravimetric (TG) method, and the kinetics parameters and reaction mechanism of oxidation are determined. It provides a theoretical basis for the comprehensive recovery of iron resources in slag and the selection of reasonable slag-making conditions.

Oct 1, 2022

By W. A. Weimer

Coal and coal mining is no longer the mighty king of industry and in our daily lives and homes that it once had the privilege of commanding. Many of you will remember that one of the chores of your youth was to bring in the scuttles of coal, morning and night, to feed the heater or stoke the furnace in the morning and bank it at bedtime. Growth of gas and oil have displaced coal in home furnaces and commercial buildings, and have taken over some segments of industrial markets. The coal burning locomotives have virtually disappeared in favor of the more efficient diesel engine. However, coal as a prime mover still holds its strategic position as is evidenced by act that the electric power industry almost entirely depends upon coal for its generation.

Jan 1, 1961

By P. Zhang

The Crago “Double Float” process is widely used in upgrading phosphate ore. This process is inefficient, as it floats about 30-40% of the sands in the flotation feed twice and requires a deoiling step. This paper summarizes several research projects on improving phosphate flotation. The University of Utah investigated a new flotation chemistry for efficient flotation of phosphate in a single step. The Florida Institute of Phosphate Research developed several single-collector, all-anionic flotation flowsheets using various sizing schemes. In addition, Eriez invented the HydroFloat separator, which demonstrated great potential for processing coarse flotation feed in one step.

Jan 1, 2004

By H. R. Cooper

Refinements and increased sophistication in modeling and simulation, and introduction of advanced techniques in automatic control made feasible with digital processor handling of data, represent the most significant fields of advancement during the past ten years. Extensions in capability to predict performance of beneficiation and other mineral extraction techniques now provide powerful assistance to developers and and designers of minerals processing unit operations and complete plant flowsheets. Computer aided advances are categorized by work in the following fields: - Steady state modeling and simulation of processes - Dynamic modeling and simulation of processes - Optimization methodology in crushing, grinding, and flotation - Optimal process control methods - Expert systems in process control

Jan 1, 1989

By John F. Slonaker

This report is a review of current research being conducted in the United States which is intended to increase the utilization of coal ash. In order that this report be as timely as possible, the majority of information was obtained by direct comunication with the people listed in the references. Due to the magnitude of the flyash research program, some projects may be inadvertently omitted. Field research on flyash for use as an agricultural fertilizer is being monitored at Virginia Polytechnic Institute and State University.1 This research is directed at determining the plant nutrients that are available in flyash as well as the quantities of flyash that can be applied to agricultural soil without adversely affecting plant growth, Coal mine spoil and refuse bank reclamation with power plant flyash is being demonstrated by United States Bureau of Mines, Morgantown, West Virginia.2 Numerous highly visible coal refuse piles and strip mine spoil banks contribute to air, water, and land environmental problems. Revegetation of several experimental sites with flyash from bituminous coal-fired power plants was undertaken in West Virginia and Pennsylvania. Conventional farm equipment was used at some of the sites while large earthmovers were required at others. The flyash served as a neutralizing agent, dilutent, and soil amendment to provide some nutrients which enhanced vegetation of the barren areas, Estimated cost of reclamation by this method is $300.00 per acre of previously leveled area. This figure can vary considerably depending upon the topography of the site, haul distance, quality of the soil and quality of flyash.

Jan 1, 1974

By Fernando Muge

A complex pyrite orebody located in the South of Portugal (MO INHO) was exploited in the past by cut and fill methods until a certain level. It was decided to design a new plant for non ferrous metal extraction and the rate of production and exploitation method was modified accordingly. So, a sub level stoping (SLS) method was en visaged for the exploitation of the deepest part of the orebody (under 265 m level). For the planning of this SLS method, it was decided to perform a geostatistical study of the orebody, on the basis of the available information, which consists mainly of channel samples assayed for Cu, S, Zn and Pb.

Jan 1, 1979

By Nikhil Dhawan, Veeranjaneyulu Rayapudi, Singh Rahulkumar Sunil

The ever-increasing demand for steel and the subsequent depletion of high-grade ores requires the massive utilization of low-grade iron ores. In the present study, an iron ore slime sample containing 56.1% Fe was investigated using physical beneficiation, carbothermal reduction, and a microwave-assisted process; however, physical beneficiation and microwave exposure were found to be inefficient as they yielded lower iron recovery. Using coconut shell as an alternative reductant was found to be promising and does not lead to the formation of higher iron oxides, such as fayalite and wustite phases. The microwave-assisted carbothermal reduction was found at par with conventional reduction, saving time and heating. The optimum magnetic concentrate obtained in both carbothermal reduction routes (microwave and muffle furnace: Fe grade, Fe recovery, and yield of 64.3, 97, and 84%, and 67, 99, and 83%, respectively) are suitable for alternative iron-making or blast furnace units.

By K. Hanumantha Rao, K. S. E. Forssberg, H. R. Manouchehri

This paper summarizes the practical considerations of the various electrical separation methods used in mineral processing. The effective factors related to mineral characteristics and equipment attributes are described and analyzed with reference to conventional industrial applications of the electrical methods. Some new aspects of electrical methods application and their potential for mineral beneficiation, apart from the mineral systems that have been successfully beneficiated, are also presented. In addition, wet dielectric separation, which now appears to be promising, is briefly cited.

Jan 1, 2000

By M. W. Harmer, J. M. Quist

Laboratory test work, pilot plant testing and plant experience with wet, fine-mesh screens are discussed. High-frequency, low-amplitude, fine-mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with hot ferric chloride to remove lead and copper contaminants before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1991

By Boshou Bian

Air quantity is the primary parameter governing the working condition of a mine fan. In order to improve the fan performance and efficiency, reduce its energy consumption, and guarantee mine safety, it is very important to obtain an accurate value. However, generally speaking, the fan ducting or drift on surface is very short in distance and contains sharp bends. The air quantity of the mine is so concentrated in this way that the air velocity becomes very high, and the airflow, either in the fan drift before the fan impeller or at the downstream diffuser, is very turbulent. Therefore, no anemometer is satisfactory because there is too much difference between the measured value and the actual value of air quantity at the mine fan.

Jan 1, 1989

By William H. Engelleitner

Agglomeration by balling in cylindrical or shallow pan devices dates back to the early part of this century. The first sintering tests conducted by Dwight-Lloyd on nonferrous ores included a mixing step for ore, flux and fuel carried out in a deep pan device similar to the balling pans, or discs, presently in use. Further work directed mainly toward sintering of ferrous and nonferrous ores always included a preparatory step, usually referred to as mixing, agglomerating or green-balling of the ingredients. In the late forties and early fifties two methods of particle preparation prior to firing were in general use. In Europe the balling pan was used predominantly, both as a mixer and as a pelletizer. In the United States many pilot plants and semi¬commercial plants used balling drums. When the first iron ore pelletizing plants were built in this country, the most frequently used device for green-balling was the cylindrical drum. At the same time, the pan device was used both in Europe and the United States for many other materials such as fertilizer, cement, flyash, alumina and copper concentrates, as well as to mix the feed for sinter machines. The difference between these two balling devices - -the drum and the disc - has been the subject of much discussion and is well covered by several papers included in the 1962 publication "Agglomeration' issued by AIMS, based on their 1961 International Symposium held in Philadelphia. (1)

Jan 1, 1965

By P. S. Parobeck, T. F. Tomb, R. S. Ondry

From October 1980 through August 1982, surveys were conducted on 19 longwall mining operations to obtain data relative to respirable dust levels associated with particular longwall operations and occupations, to make recommendations for enhancing dust control, and, where applicable, to evaluate the effectiveness of new technology implemented to control dust. The paper summarizes the data collected during these surveys and, where possible, draws conclusions and discusses actions that can be utilized to reduce exposures to respirable coal mine dust on longwall mining operations.

Jan 1, 1987