Search Documents

By William T. Ingram

Early in the 60's the author served as Chairman of the Engineering Foundation's Coordinating Committee on Air Pollution Research. One of our objectives was the development of a study on the measurement of stack emissions. Three publications of the Foundation resulted from these efforts to focus attention on the stack sampling problem.1,2,3 Two of these were annotated bibliographies covering 197 references. The third reported the results of a workshop meeting at which some 21 individuals from research institutes, industry and government discussed the possible and probable areas of research that would add to or increase the ease, precision and utility of sampling gaseous and particulate matter emitted from stacks. The American Society of Mechanical Engineers has had in its Power Test Codes a Standard Code for Determining the Dust Concentration in a Gas stream4 since 1941, The American Industrial Hygiene Association has published, in its Air Pollution Manual,5 a Section on Stack Sampling. Industry and regulatory agency requirements for stack sampling have utilized some modification of the alternatives in methodology. There has been ho single guide to stack sampling that met the needs of those who have the need to know.

Jan 1, 1970

By Christopher J. Farrow

This paper describes the grinding circuits installed at two remote sites in northern Canada. One is Cominco's Polaris Project at Little Cornwallis Island; a barge-mounted lead/zinc concentrator. The other is Echo Bay Mines' Lupin Project at Contwoyto Lake, 400 km northeast of Yellowknife, a gold mine, all components of which had to be flown to the site. Logistics and considerations of operating and maintenance presented challenges which were met by innovative design. The evolution of the grinding circuits is discussed. Both plants are operating at design throughput.

Jan 1, 1983

By J. Driscoll, T. Morson, Ross M. Workman

The study investigates the effectiveness of the canopy air curtain (CAC) in reducing respirable dust exposure for shuttle car and ramcar operators in underground coal mining. Field testing showed that the CAC reduced dust exposure by 11-34% overall and by 57-65% during ramcar loading by the continuous miner. These results demonstrate the CAC’s potential as a significant dust control device.

Feb 19, 2022

By R. Bruce Sheibach

The Picher Mining District, located principally in north-eastern Oklahoma, was one of the world's largest lead-zinc mining areas during its 55 year life. The field covers an area of approximately 72 square miles (186 km.-); an estimated 1.6 x [103 yds3 of material (1.22 x 103m3)] worth in excess of one billion dollars, has been mined. Mining activities were typified by surface exploratory drilling identifying ore distribution and extension of underground workings to the lead and zinc deposits outlined. Exploration holes were either left unplugged or plugged at the surface with a section of a telephone pole. Low grade ore and waste rock were discarded in mined out portions of drifts. These waste piles containing pyrite and marquisette were left underground and oxidized during the many years of active mining. Upon cessation of mining activities in the mid-1960's, the drifts and shafts of the abandoned workings began to flood as the cone of depression filled in, leading to the dissolution of the oxidized sulfides and the formation of large volumes of acid mine water in the mined out openings. The resulting poor quality water, with high concentrations of cadmium, iron, lead and zinc, began discharging at the surface in 1979. Contamination of the underlying aquifer supplying local residents was first detected on a localized scale in 1980. The present surface water and ground water contamination have lead to the area being classified as one of the top ten hazardous waste sites in the U.S. by the EPA under the superfund program.

Jan 1, 1982

By R. Zhang, S. Azam, S. Liu, J. H. Golbeck, V. Kurashov, S. Bhattacharyya

Free radicals (FRs) present in coal dust directly influence the interaction behavior between lung cells and dust particles. FRs are atoms or groups containing unpaired electrons, with strong chemical reactivity and a short lifespan. FRs which are quite persistent in natural environments, termed environmentally persistent free radicals (EPFRs), have recently received much attention as new environmentally hazardous substances. EPFRs present on coal dust serves as an active intermediary to catalyze reactive oxygen species (ROS) production by oxygen molecules endangering mine workers’ health. Many EPFR species may be bonded to the particle surface or trapped within the particle during coalification and can be modified with progressive size reduction through cutting at the mining face or crushing/pulverization in the plant. This study measured EPFRs for lignite, sub-bituminous, and anthracite coal dust at various sizes. We especially focused on EPFRs for submicron coal dust prepared by cryogenic methods. The outcome of this study will directly improve the free radical-dependent toxicity quantification and ultimately contribute to the size-dependent coal dust toxicity quantification.

Mar 2, 2022

By Nelson M. Solow

Raise boring of mine ventilation shafts in many cases offers a lower cost and higher speed method of construction in comparison to conventional shaft sinking. Where underground access is available for raise boring the potential savings indicate that raise boring should be considered as an alternative to other methods. Raise boring machines are currently in use which have the capability for reaming shafts up to twenty feet in diameter, depending on the strata and depth. These large capacity machines make it possible to consider raise bored shafts for moving large volumes of air. Although we will consider here only ventilation shafts, raise boring should also be considered for men and material shafts. When the mine planner has determined the volume of air required through a shaft at a particular location he is faced with the problem of selecting the shaft size. The principal factors in optimizing the shaft size are the construction costs for the shaft 'and the power cost to move the air through the shaft. The larger diameter the' shaft is the more it costs to construct, but for a given volume of air the power required (cost) becomes lower as the diameter increases. The construction cost is paid only once, when the shaft is constructed. The power costs, however, are paid throughout the life of the shaft. Methods of optimizing air shaft size found in the literature (References 1 and 2) amortize the construction cost and include it in the average annual cost of operating the airshaft. These methods derive a formula for the average annual cost vs. shaft size and de-rive the formula to compute the optimum size for a given air flow rate. It is, however, desirable to take into account tax considera-

Jan 1, 1977

By Peter G. Chamberlain

The Bureau of Mines is conducting research to boost domestic production of manganese. Virtually no mining exists in the low grade and/or small deposits that occur in this Country. One large, low-grade manganese deposit located in westcentral Arizona--The Artillery Peak district--was extensively studied and sporadically mined during the 1940's and 1950's. Although manganese mining in the district has been long dormant, recent studies indicate that the deposits may be amenable to economical production by heap and/or in situ leaching methods. A conceptual design for an in situ leaching system features undercutting and blasting a block of ore, leaching with SO2, and extracting the manganese as a sulfate or oxide. Possible applications to other manganese deposits depend upon formation permeability and specific manganese mineralogy.

Jan 1, 1981

By A. D. Trujillo, R. D. Wunder

The Chino Mines Co., a Kennecott- Mitsubishi partnership, located in Hurley, NM, recently completed a $405 million modernization of its mine, concentrator, and smelter facilities. The mine/concentrator modernization commenced in 1980, and the smelter modernization began during 1982. Modernization of the mine and concentrator facilities involved increasing the mining rate from 98 kt/d (108,000 stpd) to 152.2 kt/d (167,800 stpd). Ore mining was designed to increase production from 20.2 kt/d (22,300 stpd) to 34 kt/d (37,500 stpd). A new concentrator was con- structed near the mine using semiautogenous grinding. The new smelter uses the INCO flash smelting process, increasing capacity by 40.8 kt/a (45,000 stpy) to 99.8 kt/a (110,000 stpy) of saleable copper.

Jan 1, 1988

By G. L. Alston

The mine disaster last November in northern West Virginia has compelled the coal mining industry to take a closer look at the methods of transporting and applying rockdust. The USBM has indicated they would like to see a minimum of 80% incombustble in the back entries and want rockdust to be maintained to within 40 feet of the face at all times. With today's high rate of advance of mining machines it will be necessary to apply dust in the immediate returns continuously and the working places mutt have dust applied during the operating shift. The inspectors have become more demanding in requiring clean-up of coal and coal dust in the working place before rockdust is applied and are insisting on better clean-up and better rockdust applications along belt conveyors. Maintaining a constant application of rockdust in the back entries can be done with a Trickle-Duster. The machine is designed with hopper capacities of either 400 or 1,000 pounds of dust. The discharge rate of dust being fed through 1-1/2 inch diameter hose can be adjusted from 1/2 to 5 pounds per minute. The hose is extended into the return through the last open breakthrough and the return air carries the rockdust along w th the coal dust, depositing them uniformly on rib, roof and bottom.

Jan 1, 1969

By Harry Perry

Although the markets for coal in the United States have changed rapidly over the last three decades, the uses of coal, namely, to produce heat and power or coke have been left almost unchanged. The coke is used either as a chemical reducing agent alone or as a reducing agent and source of heat. Most of the heat and power markets for coal require no coal processing, although for more than 50 years, many proposals to skim the more valuable substances in coal before burning have been advanced. Thus, the only large tonnage market requiring processing of coal is high-temperature carbonization to make coke. At present, coal requires processing for some small markets, but for future potential large markets, such as gasification, conversion to liquid and gaseous fuels, and conversion to chemicals, coals will require more processing than is now being done.

Jan 1, 1962

By Malcolm J. Robinson

Over 80% of Australia's population lives within 200 km of the coast, 70% in 10 major coastal cities. Potential cement raw materials are widely distributed but deposit size, quality, transport, market and environmental considerations are important in determining economic value. Major production locations are in a variety of geological environments ranging from Lower Paleozoic crystalline limestones to Tertiary and Recent polyzoal limestones and limesands, both onshore and offshore. Raw material transportation is by road, rail, sea, aerial ropeway and pipeline; road/rail transportation of the finished product is traditional but movement by sea of clinker and cement is increasingly a feature of the industry.

Jan 1, 1982

By A. Toulet

Mining in Mexico has an immensely long tradition. In his first letter reporting to his sovereigns from Mexico in July 1519, Hernan Cortes wrote, "To our mind it is probable that this land contains as many riches as that from which Solomon is said to have obtained the gold for the temple ... " 1 But not only precious metals drew his attention; in 1524, short of tin needed for casting guns, he found it in Taxco. As an added bonus, those who went to find it "came upon a vein of iron which according to experts is of exceeding richness." 2 Since then, the mines of Mexico have yielded up enormous amounts of mineral and continue to do so. Mexico is one of the ten principal producers of minerals world-wide both in production volume and diversity. 3 Tens of thousands of tons of iron, sulphur, and coal come from its earth annually; it is the world's second largest producer of barite; third of antimony, fluorite, and graphite. 4 Copper, zinc, silver, molybdenum, arsenic and cadmium and others are wrested from its mines. The wealth is there; but maximizing its potential requires investment, technology, and markets that the government cannot itself provide. Thus mining, since the Mexican Revolution severely restricted by both law and policy, today looks to private investment to develop its potential. Beginning in 1989, Mexico's government cautiously moved to liberalize private sector involvement in mining; 5 using the experience gained from these initial regulatory changes, the current new Mining Law was adopted in 1992 6 and new Regulations were promulgated in 1993. 7

Jan 1, 1994

By Om P. Garg

The purpose of this paper is: 1) To summarize the capabilities and some of the limitations of the existing mine planning software. 2) To provide some guidelines for acquiring the software. 3) To identify problems and challenges in terms of how to justify increased use of computers (particularly the 32-bit microprocessor based super micro computers), for various activities related to a mining operation No attempt has been made to review the contents of available software packages in detail. Also the scope of this paper is limited to mine planning related computer applications. Applications related to accounting, inventory control, preventive maintenance, equipment scheduling, etc. have not been covered.

Jan 1, 1983

By C. Haycocks

The evolution of longwall mining is briefly traced from its inception in England in the 1620's. In the beginning this method recovered 90% of coal with roof closure controlled by packs and walls. Mechanization began with kerf cutting, crude face conveyors, and improved face support. Full face mining was accompanied by the introduction of self-advancing hydraulic supports. U.S. longwalls evolved a retreating system to recover blocks of coal outlined by room and pillar panels. Computer control combined with the most modern technology has greatly increased productivity. Past trends are used to predict future technological directions.

Jan 1, 1997

By Gustavo A. Aristizábal-H, Oscar J. Restrepo-B, J. Alejandro Delgado-J

"In Antioquia region of Colombia – South America most of extractive activity is developed as artisanal and small-scale level, exploiting different types of minerals resources but predominantly gold. This is not only an ancestral livelihood of hundreds of families in this region, but also their unique way of subsistence. However, that situation has not had a positive effect in the sustainable development of this territory because of several unsustainability factors mainly related to mercury use for gold extraction, the incorrect management of tailings and the informal way in which miners perform their activity. In 2010 Antioquia was the place with the highest contamination by mercury in the world with serious effects in ecosystems and health of habitants of this region (Veiga 2010) This paper presents a Socio-Technical Model focused on strengthening capabilities and social capital of artisanal and small-scale miners and its surrounding communities in Antioquia region. This is based on processes of evaluation, design and implementation of appropriate technologies to obtain “clean minerals” without using mercury and with a right management of tailings. In gold extraction it is about gravitational methods of concentration, which take advantage of high density of this element. These methods not only are cleaner but more profitable for miners. Notwithstanding its technical origins, the current model proposes a holistic framework that manages the elimination of mercury in mining not only as a technology transfer matter. Thus, more than formalization the strengthening process seeks to promote a business vision in miners and to develop productive chains in surrounding communities, this means to improve the skills of artisanal and small-scale miners to organize in a corporative way and to help surrounding communities to provide support and supply services to mining and even to other companies. Besides, the articulation with local institutions drives to reinforce their functions of control and accompaniment. In shorthand, this effort aims to empower local institutions, miners and surrounding communities in such a way they are able to face together their own development challenges in a sustainable way."

Jan 1, 2017

THE FUTUREGEN CLEAN Coal project will be the recipient of $1 billion worth of federal stimulus money by way of the U.S. Department of Energy (DOE), which announced the commitment to the project. The money is expected to kick off years of further work that could finally see the project completed. One of the companies involved, Ameren Corp., said the $1.2 billion project ? which will include some private funding ? still has a number of hurdles to clear.

Jan 1, 2010

By Robert F. Conley

Attrition milling, once employed exclusively for the dispersion of pigments, has in recent years found a host of new applications in the area of mineral processing and mineral-pigment production. Broadly categorized, attrition milling is divided into two classes, as defined by the machinery's function, vibratory milling and rotational milling. Each mill type has been defined as a variation on ball milling and the terms, "vibratory ball mill" and stirred ball mill" appear in the literature. The primary design differences between attrition and ball mills are: (1) a stationary canister (or shell) (2) smaller grinding media (3) grinder energy is motor limited rather than gravity limited (4) strong media/feed size dependance.

Jan 1, 1983

When Caterpillar announced that it had purchased Bucyrus for $8.8 billion, it was billed as the next great chapter in the history of mining. Surely, when the history books are written, it will be remembered as a deal that changed the face of the mining equipment sector, and it could well be a major milestone in the path toward autonomous mining in the future. In the short term, the deal is a clear indication that the world?s largest equipment maker is bullish on the mining sector. The purchase of Bucyrus allows Caterpillar to expand its mining interest to six product segments (underground, surface extraction, large mining trucks, surface material handling, hauling products and growth markets) with 16 product lines to serve the mining industry. But the commitment doesn?t end there. According to Steve Wunning, president of Caterpillar?s resource industries group, which includes Cat?s global mining division, the commitment to mining goes far beyond the acquisition of Bucyrus.

Jan 1, 2011

By D. J. M. Grodzian

Polymorphic transformations taking place in grinding processes, of massicot to litharge in PbO system, and of y to a in Fe203 system, were re-investigated. Grinding was carried-on in a steeel rotation mill charged with WC balls, under inert atmosphere. The kinetics of transformation in PbO was established by means of quantitative X-ray diffraction analysis. The resulting data fit a modified logistic growth function up to about 75% of transformed volume fraction, when a mixture at steady-state equilibrium is formed. The reasoning for the use of a modified logistic function is discussed. A sigmoidal growth function can be used if resulting data fit also an empirical power relationship between transformed volume fraction and time. However, it lacks the significance expressed by a modified logistic function. Assuming, the loss in magnetism is directly related to the amount of transformation in Fe 203, a quantitative analysis was performed using a magnetic balance method. The results fit only the modified logistic growth function, and transformation proceeds almost to completion. A wide literature survey of the subject is given. Available data from literature is compared with the results of the present study, and is shown also to fit a modified logistic grown function, with surprisingly similar slpes in a linear plot, independently of the material. The instrumentation effect on kinetics parameters, and the establishment of equilibrium mixture values, are discussed.

Jan 1, 1975

By Frank Cook

As in other areas of the country, surface coal mine productivity in the Central Coal Province--primarily Illinois, Indiana, and west Kentucky--has declined steadily since 1969 (figure 1). Productivity, as measured in tons of clean coal produced per man-shift, dropped 35 percent during the period 1969-1975. Unwelcome at any time, this phenomenon is particularly untimely now, when increased coal production is a national goal. The U.S. Bureau of Mines has been working with the coal industry to develop new operating methods and equipment to enable increased productivity and improved reclamation performance in surface coal mining. Several projects have involved identification and evaluation of existing overburden handling and reclamation practices, and development of means to improve operational procedures. Some results of one of those projects, as they apply to the Central Coal Province, are summarized in this paper.

Jan 1, 1977