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By M. S. Riyazulla

The Hutti greenstone belt comprising predominantly of low-potassium tholeitic basalt has undergone regional metamorphism of a transition zone between greenchist to amphibolite facies. The important mineral constituents of the volcanic suite are amphibole and plagioclase which appear to be the product of regional metamorphism. These minerals have been recognized as the main indicators of metamorphic temperature and pressure. With a view to understand the P-T conditions of metamorphism of the belt, electron microprobe studies were carried out on amphibole and plagioclase and the chemical data was used to decipher the metamorphic conditions. The results obtained indicated a metamorphic temperature of about 6000 c and pressure of 5 kbs. for the Hutti greenstone belt.

Jan 1, 1996

By III Kimball

Mining wastes have received individual attention under the Resource Conservation and Recovery Act (RCRA) since its inception, in recognition of the special characteristics that distinguish mining wastes from other solid wastes. The Environmental Protection Agency (EPA) has recognized that: - Mining wastes are generated in much larger volumes than other industrial wastes. Most material handled in mining is waste (over 99% in many cases) and not marketable product, whereas waste is a small portion of raw materials used in most industries. Consequently, controls used for hazardous wastes may be technically infeasible or economically impractical. - Nearly all mining waste is managed at the site of generation and is land-disposed. . - Mining wastes typically pose lower hazards than other industrial wastes. Mining operations are located predominantly in sparsely populated areas and in arid or semi-arid areas with little surface water runoff and deeper water tables.

Jan 1, 1990

By Manchao He, Xiaoding Xu, Yubing Gao

Based on the geological conditions of the 15,600 working face in Pingba Mine, this paper establishes the mechanical model of the stress distribution in the pre-working face under the influence of mining pressure based on a hemispherical stress distribution theory. The analytical formula for the stress distribution is determined. A numerical model for the mining pressure under the influence of key layer is also constructed, and dynamic stress interruptions under various roof-cutting relief schemes in different horizontal positions are simulated. The stress distribution of the stope under different pressure relief schemes is analyzed and compared with the theoretical results. Results show that blasting roof cutting blocks the transmission of the abutment pressure to the working surface to the coal and rock mass in front of the working face, reducing the significant working face mining pressure influence range, which decreases as blasting pressure relief position moves toward the working face. Stress accumulation in the coal in front of the working face also increases as the blasting pressure relief position moves toward the working surface. Engineering practice results show that blasting cutting can effectively block the propagation of mining pressure, and the stress impact range is shortened by approximately 1/3.

Jul 31, 2021

The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. To develop the model of the ventilation system with the fire in this validation study, the following adjustments were made: (1) flow and gas distribution in the entire ventilation network, and (2) fire parameters matching the data recorded by the monitoring system. After close correlations between simulation and real data were achieved, additional analysis of the ventilation system with the mine fire was performed. Presented and discussed in this paper are the following stages of the fire at the Pattiki Mine: (1) early fire (before the fire was detected), (2) preparation for and fire fighting with water, (3) fire sealing, and (4) fire extinguishing. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

Jan 1, 1995

By Vincent C. Grimshaw

High pressure fluid energy grinding, or jet milling, is a versatile method of continuously fracturing solids into fine particles to gain substantial increases in exposed surface area. Applications in the minerals industries include calcium carbonate, talc, barytes, mica, diatamaceous earth, bauxite, rutile, coal, kaolin, sepiolite, diamonds, etc. The basic principles can be extended to provide continuous drying and delivery of discrete particles from a wet process slurry. The main design and operational features of jet mills and dryers are described, relating energy consumption for both air and steam milling and hot air drying techniques. Mean particle sizes in the order of 1 micron are achieveable from pre-milled feeds, or maintained from similar slurries in the drying mode. Aspects of feed preparation and multi-stage processing are discussed.

Jan 1, 1983

By R. Hawker, P. Singh, K. V. Jessu, P. C. Pinazzi, A. J. S. (Sam) Spearing

Rock bolts are highly important underground to prevent falls of ground and thus, ensure safety. In situ, the ground reinforcement is subjected to a combination of loads, such as shear, tensile, and/or bending loads. Studies have been conducted to evaluate the effect of either shear, tensile, or bending loads on the ground support. However, only a few studies have been done to evaluate the effect of combined load on the rock bolt performance. In situ, the order of loads acting on the bar cannot be predicted, and more than one load can act on the bar at the same time. Thus, a hybrid failure criterion was developed that covered all combined loading conditions. Fifty-eight un-grouted laboratory rock bolt tests were conducted in total under two load conditions: applying shear displacement to the rock bolt and then tensile load to failure, and applying tensile displacement to the rock bolt and then shear load to failure. From the test results, the failure criterion was developed based on regression analysis. A nonlinear relationship was determined for the loading condition variations. The failure criterion presented in this paper can be used as a guide in the rock bolt capacity design under all loading conditions.

Sep 8, 2020

Mine design and selection of ore processing capacity depend upon a correct estimate of the grade-tonnage distribution. The estimate must reflect what can be recovered and processed. The McCoy/Cove operation in central Nevada, USA, is a gold and silver mine. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and the log-affine variance correction. From this model, the grade-tonnage distribution was constructed. Optimal pits were generated by utilizing the distribution, and the results were compared with the pit generated by ordinary kriging. Studies indicate that the proposed method for multi-metal recoverable reserve estimation is more accurate than ordinary kriging in terms of both tons and the grade. Using recoverable reserves for mine design will maximize global recovery of mineral resources.

Jan 1, 1997

New South Wales (NSW) and Queensland dominate Australian black coal production and exports. NSW produced 86 Mt (95 million st) of saleable coal in 1994, a doubling of output since 1980. Asian demand for thermal and coking coal has driven this growth. This high Asian demand is expected to continue and NSW will seek to secure its share. History The history of the New South Wales (NSW) coal industry can be traced to 1797 when coal was first taken from Newcastle to Sydney (Ellis, 1969). At that time, NSW was a British colony, independent from the other colonies, such as Victoria and Queensland. Australia, as a federation of colonies, did not exist until 1901. The Newcastle coal industry grew through the 1800s in line with the growth of the colonies. Several events spurred demand for Newcastle coal. These included: ? The NSW and Victorian gold rushes of the 1850s and associated population growth. ? The development of steamship traffic at the expense of sail. ? The development of railways and town gas supplies. By 1900, Australia was producing 6.4 Mt (7 million st) of coal, most of it from NSW. By then, NSW had established strong export markets in Indonesia, China, Japan and New Zealand. The history of energy consumption is marked by continual competition, changing intensity of use and substitution. From 1900 to 1940, the Queensland, Victorian and Indonesian coal industries developed at the expense of NSW exports. Similarly, New Zealand developed its hydroelectric industry and thus declined as the largest customer for NSW coal. Oil replaced steam in the shipping and railway markets and electricity replaced gas for lighting. Industrial efficiencies also affected coal. Between 1928 and 1938, coal consumed in generating power fell from by 17% on a kilowatt hour basis and, during the same period, the amount of gas produced per ton of coal rose by 18% (Shaw and Bruno). Faced with these pressures, production and exports stagnated. By 1941, Australian black coal production was 14.2 Mt (15.6 million st). NSW's production was 11.7 Mt (12 million st), up only 19% from 1912. Exports had virtually ceased (Fig. 1). In such circumstances, the industry had lost focus. Unions resisted the need for mechanization, for security of employment reasons, and owners were loath to invest. This reluctance to mechanize and the associated in-

Jan 1, 1997

By G. E. McClelland

In recent years exploration and development of low-grade sulfide precious metal ore deposits has increased. Low- grade ores are usually processed using conventional heap leach cyanidation methods. The potential for acid mine drainage from spent sulfide ore heap leached residues remains a concern even though the processed residue is stacked on an impervious liner system. It is therefore of critical importance to evaluate methods for long term prevention of acid mine drainage from sulfide heap leachable ores during the precious metal recovery process rather than mitigation during the closure and reclamation phase. This paper discusses two simple AMD prevention options for the recovery process phase. Laboratory evaluations were made using a modified humidity cell kinetic AMD test method on two low-grade sulfide ores without addition of an alkaline component and on the same ores with natural limestone or acid neutralizing oxide ore blended with the feeds before kinetic testing. Laboratory results are discussed in detail and demonstrate that blending an acid neutralizing component with sulfide ore effectively prevents the production of acid from the processed residue.

Jan 1, 1996

By Lana Alagha, Keitumetse Cathrine Monyake

The abstract discusses the synthesis and investigation of polyacrylamide functionalized chitosan polymers (CS-PAMs) as selective depressants for pyrite in the flotation of galena and chalcopyrite from complex sulfide ore. The study employed response surface methodology (RSM) to model and optimize the flotation process, varying parameters like the degree of deacetylation of chitosan, weight ratio of chitosan to acrylamide, and CS-PAM dosage. The developed RSM models effectively predicted iron and lead grades and recoveries, while optimization showed optimal pyrite separation from galena and chalcopyrite using CS-PAM synthesized from chitosan with a high degree of deacetylation and a specific chitosan:acrylamide weight ratio.

Apr 9, 2022

By C. G. Treworgy

Geologists at the Illinois State Geological Survey are evaluating geologic and land use conditions that affect the minability of coal to determine how much coal is available for development using current technology and mining practices. Coal resources are being evaluated for selected 7.5-minute quadrangle study areas. In a central Illinois study area, more than 25% of the deep-minable resources were limited from development by unstable roof conditions resulting from thick unconsolidated sediments overlying thin bedrock overburden. In some southern and southeastern Illinois study areas, geologic conditions associated with a paleo-channel limit the minability of significant resources of low-to medium-sulfur coal. Some features which were thought to limit mining, such as areas of closely-spaced oil wells, have been found to have minimal impact on the amount of coal recovered.

Jan 1, 1995

Dravo Corporation was founded in 1891 and has long been recognized as a major domestic engineering and construction firm headquartered in Pittsburgh. In 1977, Dravo had revenue of $852.2 million with international business activities contributing $248 million; quite a different picture than envisioned at the turn of the century. Engineering and construction activities still dominate Dravo's most recent history and will do so for the immediate future. However, fluctuations in capital spending by large industrial sectors of our economy during the late sixties were affecting Dravo's planning for continued growth along its traditional lines of business. Diversification was a possible solution to smooth out the upward trend in corporate earnings. One large result of these continuing efforts was the formation of Dravo Lime Company, a vertically integrated, proprietary chemical supplier for the air pollution control market. Briefly retracing the seventies, the passage of the Federal "Clean Air Act" in 1970 supplied the impetus for Dravo Lime Company. This law promulgated limits on the emissions of sulfur dioxide (SO2) from large stationary sources that would affect local air quality. The major industry that felt the brunt of this regulation was the electric utility industry, especially those generating electricity with coal-fired boilers. The law hastened the development of a new industry, flue gas desulfurization (FGD), and is composed of three major segments: (1) the electric utility, (2) the FGD equipment suppliers (the scrubbing modules), and (3) the scrubbing chemical suppliers. Dravo's experience suggested the equipment end of the business but market analysis indicated that our long range corporate goals could be better attained by investigating the chemical processes involved in the removal of the SO, gas. The result being Dravo Lime Company. This paper will briefly describe the Thiosorbic lime scrubbing process and review our innovative mine and calcining facility.

Jan 1, 1978

By J. J. Moore

Combustion synthesis or self propagating high temperature synthesis (SHS) reaction systems are discussed with respect to thermodynamics and kinetics. In particular, tile effect of the process parameters, ego particle size, AHf, ignition and combustion temperatures on these self sustaining reactions is discussed. Combustion theory is used to investigate the effect of the overall activation energy of the SHS reaction on the combustion front propagation rate and in obtaining a clearer understanding of the transition from stable to unstable propagation. Finally, examples of the application of combustion synthesis to advanced materials processes are made, in particular the synthesis of Ni-Ti -X intermetallic shape memory alloys, TiC-Al2O3 and ZrB2 ?Al2O3 ceramic composite materials.

Jan 1, 1991

By H. Ankara

Determining the identicalness levels of the same model trucks working in open pit mine transportation system by means of statistical analysis methods is very significant in terms of availability analysis. In this study, the identicalness levels of two trucks picked randomly from the 170-short-tonne truck fleet working in open pit coal mine over one-year period were examined through a non-parametric test, Mann-Whitney U test for two samples. Time to failures (TTFs) and Time to Repairs (TTRs) of the trucks were analyzed with this test technique and then whether they were identical or not was determined. In order to determine whether the trucks identified to be identical at the end of this test displayed the same mining performances within the same open pit transportation system, the availability analysis of the identical trucks was carried out. As a result of the availability analysis, it was observed that the trucks had availability values that were very close to each other. It was also determined that Mann-Whitney U test could be employed together with availability analysis. Finally, it was observed that Mann-Whitney U test for two samples could yield rapid results in the performance analysis of complex systems like open pit mines.

Jan 1, 2010

By Donald Bishko

Zoning is the legal means by which land use can be controlled. Although zoning laws have historically been quick to prevent quarrying, one is hard pressed to find zoning ordinances which specifically state that land should be used (or held in reserve) for quarrying and prevent other uses such as recreation, housing, etc. This situation is especially true when the mineral to be quarried has a low intrinsic value such as sand, gravel, and crushed stone. The chance of a gold mine surviving urban sprawl is probably considerably greater than that of a sand and gravel pit, even though it is possible that the dollar value of the sand and gravel' would exceed that of the gold mine. The research reported herein was concerned with two major topics: to delineate the real costs associated with the non-protection of our construction aggregate resources (growth minerals) and to develop a computer simulation model which would aid planners in making economically sound decisions. This paper describes the problems faced by the mineral aggregate industry and discusses the role of computer simulation in planning problems. It briefly describes a simulation model which has been developed and previously reported12 and discusses the results of a pilot study conducted on the Tri-City area (Albany, Schenectady, and Troy, New York). 3

Jan 1, 1970

By D. A. Lowrie

Environmental concerns and increasing mine development costs have created a need for early information on gold recovery from its host environment. The habit, association, and approximate abundance of minerals which contain unacceptable metallic ions which may be released during process of concentration of gold should be identified in exploration drill core. One case of a "clean" gold orebody is described to show that early petrographic studies contributed to a rapid decision to mine a small deposit by open pit and to custom mill the ore in an already restricted effluent environment. A second example describes identification of an undesirable mercury content and resulting action taken.

Jan 1, 1985

By A. F. Barsotti

Apart from jewelry, holistic apparel, and special collections of color and sometimes rare crystal specimens, the average layperson has little or no appreciation of the omnipresence of minerals or mineral derived products in the home. From concrete in the driveway to aspirins in the medicine cabinet, minerals, especially industrial minerals, play a major role in day to day living. For a better appreciation of this let's look into the a day of the life of a fellow named John, and see how much we depend on industrial minerals. The sounds of soft violins nudged John from his sleep. The melodic sounds of Beethoven's Pastoral coming from his radio alarm clock brought him out of his dreams. He reached for the reading light switch, then checked his watch--6:30 a.m., and another day of work. As he got up, the darkness outside reminding him of winter coincided with the soft voice of the all night disk jockey forecasting the fall of four inches of snow. Warm beads of water beating on his face removed all remnants of sleep and, like a stimulant, the morning shower brought thoughts of yesterday and plans for a new day. These carried over as he looked himself in the mirror while shaving and brushing his teeth.

Jan 1, 1993

By J. Kallioinen

Theoretical considerations, experimental results and plant experience have lead to a new design concept called the unit reactor approach. It has been successfully implemented to the largest flotation cell on the market, the 4000 cu ft OK TankCell. The work has also lead to a new operating idea called size specific flotation. The paper discusses these concepts in the view of full scale field experiments. In large scale porphyry copper flotation experiments conducted in Chile the new large TankCell with its new low energy input Free Flow mechanism out-performed the more conventional designs. The recovery was substantially better, especially in the coarse fractions. In some experiments the difference in total recovery was up to 10%-units and the savings in total energy consumption at the same time over 40%.

Jan 1, 1995

By S. R. Maynard

The Ortiz Mountains lie 25 mi (40 km) northeast of Albuquerque, New Mexico in Santa Fe County (Figure 1). Approximately 350,000 ounces (11,000 kgs) of gold have been produced from the Ortiz Mountains since the 1820s. The 100 square mile (260 square km) Ortiz Mine Grant was secured from the Mexican government in 1833 by Jose Francisco Ortiz for the purpose of mining gold. The Grant has remained more or less intact to the present. The mineral rights are currently owned by Ortiz Mines, Inc. of Joplin, Missouri and are leased to LAC Minerals, USA, Inc. (west half) and to Gold Fields Mining Corporation (east half).

Jan 1, 1989

By J. A. Organiscak

This paper describes the research con-ducted on bit wear and respirable dust generation conducted by the US Bureau of Mines (USBM) and West Virginia University (WVU), a member of the Generic Technology Center on Respirable Dust. The USBM investigated wear, energy and dust characteristics of various conical bit designs when cutting rock. WVU studied the functional relationships between wear, cutting force, energy, and dust of one conical bit type when cutting coal. The objective of the USBM study was to identify qualitative bit selection guidelines for cut-ting rock; WVU's research objective was to determine optimum bit replacement guidelines. These research studies both found that bit geometry (a function of bit design and wear) influences energy consumption and dust generation. Bit selection and replacement recommendations are given.

Jan 1, 1995