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By K. S. Eric Forssberg, T. V. Subrahmanyam

The present paper deals with the important technological developments in gold processing and where possible, the data is presented in the form of tables. Gold processing methods have evolved to such an extent that low grade and complex ores once considered uneconomic are now becoming viable. Constant efforts are underway to innovate technologies in order to improve the efficiencies and cut down the capital and operating costs. The methods are discussed.

Jan 1, 1988

By H. Polat, S. Chander

Relatively large amounts of hydrocarbons such as fuel oils are often needed in the flotation of low rank coals. The amount of oil can be decreased considerably by using surfactants as promoters. The reagents that are good candidates as surfactants to promote hydrophobicity can also act as emulsifying and wetting agents. Because the physical and chemical variables influence various subprocesses in different ways, their influence on the performance parameters is complex. The results of laboratory tests are presented to show that the dual role of reagents can be judiciously exploited to increase both the recovery and grade of the clean coal. The mode and order of reagent addition is critical in enhancing their efficacy as flotation promoters. The results demonstrate the benefits of proper conditioning of the pulp prior to flotation.

Jan 1, 1999

By Houston Kempton, David Atkins

Mining in semi-arid climates can produce environmental impacts that will not begin for hundreds of years, but once started, may continue for thousands of years. Pit lakes may eventually exceed toxicity thresholds as metals are evaporatively concentrated, and slow unsaturated flow through acid-generating waste can eventually load several kg-SO4/m2-yr to underlying water tables. U.S. regulations are poorly equipped to respond to delayed and long-term environmental impacts, delaying permits as operators and regulators grapple with uncertainty. Improved uncertainty analysis, additional long-term mitigation options, and explicit regulatory guidance offer solutions to this dilemma.

Jan 1, 2000

By R. J. Nankee

Recent on-going efforts to develop commercial coal cleaning beneficiation processes using chlorinated solvents-as the separating media will be described. True heavy media separations were performed on raw coal feedstocks, including Pennsylvania anthracite; Western, Eastern, and Midwestern bituminous; and lignite coals. Separation techniques included bath-type devices, cyclones, and liquid/liquid partitioning. Details on separation devices, removal of solvent, and recovery and recycling of solvent will be discussed. Projected costs of full-scale plants will be given for various coal sizes. A number of the coals evaluated are good candidates for beneficiation using chlorinated solvents. Coal beneficiation is desirable to provide needed coal quality. These needs include low ash fuels for coal water slurries and low sulfur fuels to meet emission regulations. In October of 1985, a paper, "Chlorinated Solvents for Coal Beneficiating"' was presented at the fall meeting of SME-AIME at Albuquerque, New Mexico. It reported the results obtained from various coals as feedstocks and of the separations using chlorinated solvents. These beneficiation results depended on true heavy media gravity and liquid/liquid partitioning separations. This paper will include detailed descriptions of the liquid/liquid partitioning process used in "Dow's Advanced Coal Cleaning Technology?2 and of the "Dow Solvent Recovery Technology.?3

Jan 1, 1987

By L. Zhou, D. Bahrami

A reliable and stable ventilation system is essential to the safe operation of underground mines. The stability of a mine ventilation system becomes extremely critical while responding to a fire incident since an unstable ventilation system will pose a risk of airflow reversal. The reversed airflow could bring the fire contaminants such as toxic gases and smoke unexpectedly to working areas. In the past few years, there has been a growing interest in the study of ventilation network stability using the concept of resistance sensitivity, which is described as an indicator of how the airflow in an airway is reacting to a resistance change of other airways. Several methods of calculating the resistance sensitivity in a mine ventilation network have been carried out by researchers and scholars around the world. However, the proposed methods heavily rely on a vast amount of mine ventilation simulations, which are very time and computer-power consuming, especially for a large-scale mine ventilation network. In this paper, a direct derivative method calculating the resistance sensitivities with a single mine ventilation simulation has been developed and implemented into a mine fire simulation software, MFIRE. The results from the direct derivative method were verified against the results from a traditional method. The direct derivative method has been proved to be reliable and accurate.

Mar 2, 2022

By John T. McDonough

The Climax Mine of AMAX's Climax Molybdenum Division is currently producing approximately 34,000 tons of molybdenum ore per day from two underground levels (see Figure I), and initial design is underway for the next deeper (1200) level. The aim of this report is to present the methods of site evaluation used at Climax for cavability determinations and underground support design. Climax succeeds with its panel caving system of mining (Julin, 1973) (Figure 2) largely because of the presence of pervasive geologic structural discontinuities. The stockwork ore body at Climax was formed by the multiple intrusion of mid-Tertiary rhyolitic magmas into Precambrian granite, schist and gneiss, and the hydrothermal emplacement of molybdenite into the network of fractures that were generated during the forceful upward intrusion of magma. Subsequently, intrusive events that were more deeply seated refractured the overlying, ore- bearing stock and propagated a complex system of axial and radial fractures. Post-ore movement along the Mosquito Fault (Wallace, 1968) and its associated stranded shear zones further fractured the ore body and disordered the existent geologic structure. The result of these structural events is a brittle, crystalline ore body that is transected by a complex pattern of faults, shear zones, and joints that augment cave initiation and enhance comminution of the ore blocks. Generalizations can be made about the structural trends within the ore deposit (King, 1946; Kendorski, 1973), however, the intensity and orientation of geologic structure is by no means uniform throughout the ore body. The relative intensities of silicic and argillic alteration are also highly variable (Vanderwilt and King, 1955). As a consequence, no single rock-mass model suffices as a standard for mine design, and site characterization for cavability and support design is a continuous process.

Jan 1, 1977

By Kenneth S. Johnson

Oklahoma is a region of complex geology where a mobile belt of Paleozoic geosynclines and uplifts on the south abuts against the margin of the North American craton to the north. The state contains many classic areas where fundamental concepts of sedimentation, stratigraphy, structural geology, historical geology, mineral investigation, and petroleum exploration have been formulated through the years. In the southern Oklahoma mountain belts, there are exposed a great variety of igneous and sedimentary rock units seen at few other places in the Midcontinent area. Major geologic provinces of Oklahoma (Fig. 1) include: (1) the cratonic and relatively stable northern shelf areas, including the Ozark uplift; (2) the Ouachita geosyncline (now the Ouachita Mountain belt) and associated Arkoma basin in the southeast; and (3) the southern Oklahoma aulacogen (geosyncline), comprising the area of Anadarko, Ardmore, Marietta, and Hollis basins, as well as the Arbuckle and Wichita Mountain uplifts. The three principal fold belts, the Ouachitas, Arbuckles, and Wichitas, all originated from a series of Pennsylvanian orogenies (about 300 million years ago) in the two Paleozoic geosynclines.

Jan 1, 1999

By A. W. Mitchell

Mining of a bedded barite deposit exposed highly pyritic siliceous sediments which have weathered and degraded subsurface and surface waters. The ph, sulfate, and total dissolved solids are the most seriously affected parameters. Several solutions were tried and eventually horizontal holes were drilled into the mine wall to draw down the water table and decrease the movement of groundwater through oxidizing zones opened up by the mining operation. Areas of surface disturbance were capped with layers of soil, bentonite, and gravel to decrease the infiltration of water into the disturbed areas. These actions have begun to decrease sulfate and total dissolved solids concentrations and increase ph values.

Jan 1, 1987

By Chuck R. McLendon

A new face ventilation system was needed at the Allied Chemical Trona mine, near Green River, Wyoming. The development of an exhaust manifold face ventilation system came from a need to reduce the dust and noise concentration level while maintaining methane control at the continuous miner working face. Dust laden air from a heading being driven by a continuous miner was contaminating the intake air in the mine around the roof bolter operator and adjacent headings. Each working heading was exhausted into the last open crosscut by a face fan. A face fan would contaminate the adjacent downstream heading with dust-laden air until a high dust concentration developed in the final entry before the returns. A face ventilation system was needed to give the exhaust of each heading an individual path to the return air. In addition, the system could not interfere with the present room and pillar mining process. A manifold system of rigid duct ventilation tubing was designed using the existing fans in a parallel arrangement. Each system was to consist of the rigid duct tubing in three headings junctioned together at the last open crosscut and exhausted at a common branch in the return air. Each heading was to have its own damper (or valve) so that air could be directed where it was most needed. The system was installed using both round and oval rigid duct ventilation tubing to minimize head loss and to allow proper ground clearance for mining machinery. Two fans in parallel were used to exhaust three headings. By adjusting the valves at each heading, up to 18.0 kcfm (9.36 cu m per sec) could be exhausted from one heading and still keep the methane level controlled in the other two headings. The manifold exhaust system has proven to be an efficient, long lasting ventilation system at the Alchem Mine. It has reduced the dust and noise exposure levels at the working faces while keeping the methane level under control.

Jan 1, 1980

By George Bárdossy

Most of the bauxite deposits in Europe belong to the karst type. They are located mainly ill Southern Europe along the Mediterranean Sea and in the Ural Mountains. Lateritic bauxite deposits occur on the Russian Platform, in Poland, Northern Ireland and in Turkey. Tikhvin-type deposits arc found on the Russian Platform. Bauxite formation in Europe started in the Middle Devonian. The main bauxite forming period was the Upper Cretaceous. Very few bauxites are younger than Eocene. Most deposits are covered by overburden of up to 1000 m. Prospecting is carried out by drilling. Several geophysical methods are used to detect the hidden deposits. Geostatistical methods were introduced in several countries for evaluation of the reserves and the geometry of the deposits. Data on bauxite production are given for 1982 and since the beginning of mining in Europe.

Jan 1, 1984

By R. L. Grayson

The Office for Mine Safety and Health Research, National Institute for Occupational Safety and Health is responsible for providing research leadership in the prevention of mining work-related illness, injury and death. Planning of the NIOSH FY99 research program focused on the comprehensive collection and risk analysis of fatality, injury and illness data according to commodity and mine type. This data, coupled with the mapping of information obtained from stakeholder meetings over several years, provided the basis for prioritizing research needs. Results of the combined analysis were compared to the FY98 program to identify surveillance and research gap areas. The FY98 research program was then assessed according to commodity and mine type and compared with exposure assessments, traumatic fatality rates, injury rates and employment trends in each commodity-mine type combination to gain insight into the potential balance of the future research program. This paper presents the methods, data and results of this planning process.

Jan 1, 2002

By Louis L. Sirois, Kwang S. Moon

The flotation mechanisms of various flotation machines are briefly reviewed. The counter current column flotation mechanism is described in more detail. The merits of counter current column flotation include; improved metallurgical performance in terms of grade and recovery, effective cleaning action in the long cleaning zone with a blanket of fresh water, smaller floor space required due to the vertical configuration of a flotation column, low capital, operational, and maintenance costs due to the absence of moving parts and finally, easier flotation control due to the simplified circuit. The results of column flotation studies on various minerals and coal at CANMET are discussed. Some of the industrial experiences with the Canadian flotation column on various sulphides, oxides and coal are also presented.

Jan 1, 1988

By Randal J. Barnes

Computer based techniques for solving the Ultimate Pit Limit Problem have appeared in mining literature since the early 1960's. The majority of papers pertaining to this subject can be partitioned into one of two categories: discussion of the pros and cons of a particular algorithm, or a case study presenting specific applications of an algorithm. Subsequently, there has a1 so been considerable debate concerning the best techniques between, essentially, two camps: those favoring the moving cones techniques, and those favoring the techniques which yield true optimal pit designs. The purpose of this paper is not to add to this debate, but rather to present a few new ideas (partially a new look at an old idea), which can be easily implemented to noticeably improve any ultimate pit limit approach independent of the particular algorithm used. These ideas fall under the heading of "bounding the optimum" (Barnes and Johnson, 1980).

Jan 1, 1982

By R. Asamoah, K. B. Owusu, G. Abaka-Wood, W. Skinner

The hostile nature of industrial autogenous (AG)/semi-autogenous (SAG) mill operation necessitates the need for robust and reliable online measurements. Mill slurry density is regarded as a critical variable and requires a suitable range for grinding efficiency. In this work, mill acoustic sensing of five different slurry densities (50, 60, 70, 80 and 90 wt.% solids) was investigated using a laboratory-based AG/SAG mill. The results showed that slurry density of 70-80 wt.% solids gave the highest mass of -75μm particles and similar acoustic intensity. The mill acoustical level increased continuously coupled with energy reduction as a function of increasing slurry density, an indication of potential realtime measurement.

Mar 2, 2022

By Erich U. Petersen

Chemical zoning studies of mineralization can be useful in guiding exploration efforts. They permit one to determine the limits of mineralization and to correlate mineralized intervals in drill holes. Fahlore minerals are well suited for zoning studies because they are common minerals found in a variety of deposits, exhibit chemical diversity, and record the chemical evolution of migrating hydrothermal fluids. Zoning information in the form of metal ratios preserved in fahlore minerals was used to determine ore body limits in the Orcopampa precious metal system, Peru, and to correlate between multiple ore horizons in a sediment hosted massive sulfide (SHMS) currently under investigation. The current generations of electron microprobes provide the most efficient, accurate and economic way to analyze the tens to hundreds of sample required to successfully describe and use zoning information at the mine scale.

Jan 1, 1991

By A. D. Unsted

The Premier mine has been in existence for over 75 years and is closely woven into the glamour of the history of South Africa. A note on the geological formation of the diamond pipe and the gabbro gives a clearer overall picture of the mine. Mining methods for operations above and below the gabbro sill are briefly discussed. Ventilation arrangements for mining above the sill are briefly described and possible ventilation arrangements for mining below the sill are discussed in more detail. Note: conversions to S.I. units are not exact as rounding has been done.

Jan 1, 1980

By S. Chander

Neutralization of acidity by addition of alkaline materials is a commonly used method to treat acid mine drainage. However, this procedure requires large amounts of reagents based on acid-base accounting. The potential use of organic additives in preventing or ameliorating acid mine drainage was investigated in this research. The tests were conducted in weathering columns using refuse samples from a coal cleaning plant. Both cationic and anionic compounds were tested. For a comparison, tests were made in the presence of limestone and lime. The results show that some of the reagents substantially retarded the rate of oxidation whereas others even enhanced it. The suppression of the rate of pyrite oxidation was ascribed to surface chelation. Formation of surface compounds prevented the pyrite particles from further oxidation. Such a treatment required only small quantities of reagents since the reaction was confined to the surface.

Jan 1, 1992

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials will borrow strongly from terrestrial experience but will also involve the necessity of handling literally unEarthly feedstocks, reagents and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed, with the production of rocket propellants, life-support fluids, structural metals and refractories as the goal.

Jan 1, 1994

By G. M. Wilemon, B. J. Scheiner

The Bureau of Mines conducted investigations on extracting phosphate values from fine-particle wastes generated during the mining and beneficiation of phosphate ore by leaching dried wastes using a H2SO4-methanol mixture. Although phosphatic clay waste contains up to a third of the phosphate originally present in the ore, recovery of these values represents a significant challenge due to the fine grain size of the material, the particles averaging less than one micrometer in diameter. Waste samples obtained from two Florida producers yielded phosphate extractions of 71 and 84 pct, respectively, when leached under ambient conditions and at a stoichiometric acid ratio of 1.4:l. Elevated temperatures did not improve the amount of phosphate extracted. Undesirable A12O3, Fe2O3, and PlgO impurities were largely rejected; higher grade wastes gave acids that meet established industry impurity standards and lower grade samples yielded acids that marginally fell short of the standard. Separation of the crude acids from the insoluble residues was accomplished via vacuum filtration through either filter paper or commercial filter cloths. Both filtration rates and solids retention were improved by the addition of 0.5 lb/ton of poly(viny1 acetate) (PVAc) or poly(ethy1ene oxide) (PEO) to the methanol-acid slurries. These results show potential for substantially increasing the reserves of an important domestic resource.

Jan 1, 1989

By Raivo Maripuu

The Boliden Group encompasses Sweden's foremost operations related to the mining and production of copper, lead, zinc, precious metals and metallic by- products. It is also the dominant swedish producer of sulphur-based heavy inorganic chemical products and fertilizers and has an international trading organization covering, in adition to the group's basic products, industrial minerals and oil. Boliden's activities in- clude the marketing of proven Boliden technique and know-how. Boliden Metall - the mining and metallurgical company within the Boliden Group - produces about 13 million mtpy of ores at mines in northern and central Sweden. Boliden has, over the years, become a specialist in processing poly- metallic sulphide ores and its eight concentrators presently serve 15 mines. Boliden has a long history of close cooperation with Swedish and foreign manufacturers in developing new products and processes.

Jan 1, 1979