Search Documents

By M. Misra

The dissolution of mercury during gold cyanidation is the cause of many environmental, health and processing problems. A study was undertaken to find a suitable reagent for the removal of mercury bearing complexes from the leach liquor. Removal of mercury from synthetic solutions and process water from a gold mine was investigated using sodium sulfide, sodium and potassium dimethyl dithiocarbamates as precipitating reagents. The results have shown that efficient mercury removal could be achieved by addition of potassium dimethyl dithiocarbamate (KDTC), by formation of stable mercury compounds. The resultant mercury-potassium dimethyl dithiocarbamate precipitates are stable under present plant operating conditions and do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is also possible to stabilize the mercury in the heap during cyanidation by adding dimethyl dithiocarbomate.

Jan 1, 1998

By E. R. Palowitch

On February 5, 1973, Eastern Associated Coal Corp began shortwall mining in their Federal No. 1 Mine, thus marking the first attempt in the United States at modern shortwall mining, i.e., using a continuous miner to extract coal open-ended from pillars 100 to 200 feet wide, under the protection of a self¬-advancing roof support system (1)1/. Since then, four additional shortwall faces have been operated. While the number of face-years of shortwall experience in the United States is limited, this experience has been anything but uniform. Differences in operator motivation, coalbed parameters, geologic conditions, panel dimensions, and face equipment all have contributed to a wealth of knowledge which can provide guidance for the design of future shortwalls. The purpose of this paper is to review the history of shortwall mining in the United States and to assess its value to the U.S. coal industry in terms of the health and safety of the miner, the percentage of coal recovered, coal production, worker productivity, and relative cost performance.

Jan 1, 1976

By RIINA SALMIMIES, ANTTI HAKKINEN, PAULA VEHMAANPERA

Better understanding of the mechanisms and kinetics of dissolution can benefit several industrial processes. For example, iron can be leached from clays, which can be further used as a raw material in the ceramic industry. Another important application is the regeneration of ceramic filter media, which are used in the dewatering of iron ores. Dissolution of iron oxides in mixtures of acids is fairly uncommon and a less well-understood phenomenon, but it can result in a more efficient process. This work also shows that the determination of dissolution mechanisms and kinetics is not straightforward in different acid systems.

By William Gleason

"It has been more than 10 years since Montana Resources’ copper/molybdenum mine has had a lost-time injury at its site in Butte, MT. With more than 350 employees and an average production of about 15.5 Mt/a (17 million stpy), which includes 29.5 kt (65 million lbs) of copper and 4 kt (9 million lbs) of molybdenum, the mine’s journey to a decade of exemplary safety is an impressive feat that has required hard work, commitment and, most of all, leadership from every level of the operation.It has not always been an easy journey, nor has it been one without scrapes and bumps along the way, but it is one that has produced stellar results. Mike McGivern, vice president of human resources, and Pete Steilman, safety manager at the mine, spoke with Mining Engineering about how the operation transformed from a site that was accustomed to collecting citations for safety violations to one that is now collecting awards for its safety record.Simply put, Montana Resources has made safety a value and the people its top priority.The operations faced many predictable challenges in 2003, when the mine was being brought back online after three years of sitting in care-and-maintenance status. It had been shuttered in 2000 because of low commodity prices and high operating costs, and, in the three years that the mine was idled, the equipment became dilapidated, and some of it was no longer in compliance. Less than half of the workforce returned to the site for the restart, and the team was challenged with getting the gears turning again to produce copper and molybdenum. But the most daunting challenge of all of was keeping the workforce safe during the transition.In the first few years of operation the mine racked up citations from the U.S. Mine Safety and Health Administration (MSHA) at an alarming pace, so much so that in May 2006, Montana Resources received a letter from the MSHA District Office informing the company that the operation was being placed on the Potential Pattern of Violations list due to its excessive citation history and high rate of significant and substantial citations. It was clear that something significant had to be done to change the course of action at the mine."

Oct 1, 2019

By Robert W. Gordon

The art of excavating tunnels with continuous, full-face boring machines began almost 90 years ago, in the early 1880's. At this time, Colonel Beaumont designed and manufactured a seven-foot diameter tunneler for boring under the English Channel, Despite the absence of modern materials and manufacturing techniques, Beaumont's tunneler, powered by compressed air piped in from the surface, was quite successful. During its short, but impressive existence, this machine set a record of advancing in chalk 50 feet per day for 53 days - which is impressive even by today's standards. Despite the apparent success of this early tunneler, almost 80 years passed before any further significant development was accomplished in this field. Demands from the construction and mining industry and society itself have motivated the development of the modern tunneling machine. Our rapidly growing civilization needs faster, less expensive and safer means of excavating tunnels. Space age technology and materials have played a major role in making hardrock tunneling machines possible.

Jan 1, 1970

By C. Vasquez, A. Nieto

In past drilling programs for a multi-seam Texas lignite reserve, extensive e-log data was collected; however, little laboratory analyses were performed. As a cost and time saving incentive, sampling of lignite was intensified. In a recent drilling program in east-central Texas, detailed laboratory analyses and e-log information was gathered on a multi-seam lignite reserve of the upper Wilcox Group. This data will undergo statistical and geostatistical techniques in an attempt to discern whether or not predicted Ash and Btu/lb values can be derived from the e-log gamma-density relationships. Final characterization of the dataset will be used in a geostatistical model of that reserve. This model will be the basis for further geological investigations and mine planning.

Jan 1, 2004

By G. V. Henderson

The San Gabriel Valley contains some of the richest and most extensive sand and gravel deposits in California. Operating quarries within the San Gabriel area mine more than 15 million tons of high quality aggregate per year. This represents about 45 percent of the total mined in the greater Los Angeles area, one of the nation's largest aggregate markets and producing regions. Popular opposition to continued aggregate production in the San Gabriel Valley is high, especially in the city of Irwindale where 40 per-cent of the city's property is made up of "excavated holes," some 150-200 feet deep. Reclamation of 70 years of mining is now an almost impossible task. Zoning regulations have the effect of depleting these vast reserves rapidly by changing the definition of total reserves to include only "legally minable reserves." All but two or three of the aggregate mines now operating will be depleted or zoned out of business by the year 2000. Some studies indicate that there will be no aggregate mining operations by 1995. Recent studies show a drastic change in land use patterns within this valuable mineral resource area over the past 20 years. The San Gabriel Valley is a classic example of the lack of adequate regional planning with regard to urban development in MRA's and represents a "too little, too late" effort by local government and industry.

Jan 1, 1978

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 AMIT SHARMA, BIBHUTI BHUSAN MANDAL

This paper describes the vibration transmissibility characteristics of mining vehicle seats under dynamic conditions in an opencast iron ore mine. Magnitude and frequency contents of vibration signals on the seat floor as well as on top of the seats were measured to record the change during transmission. The conventional rigid seats were found to resonate at about 4 Hz, which coincides with the resonance of the human spine. The pneumatic suspension seats also proved to be more efficient in attenuating the overall vibration energy transmitted from the vehicle chassis to the human body.

By D. M. Hausen

Carbonaceous gold ores are ubiquitous to virtually all of the Carlin-type gold deposits along the Carlin gold belt in north central Nevada, representing the unoxidized "zones" of presumably extinct thermal spring systems of mostly Tertiary age. A period of subtropical weathering resulted in deep sub-lateritic zones in most deposits to several hundred feet below surface. Carbonaceous ores below this supergene profile of weathering have been investigated by various methods, including petrographic study, standard geochemical and organic carbon analyses, carbon and hydrogen isotopic ratios, electron-spin resonance spectra, infrared spectra, and DTA techniques. Results have been integrated with recent findings by other investigators utilizing fluid inclusion and thermal brine data to indicate a first phase hydrothermal solution temperatures and pressures at a minimum depth of 6 km under normal geothermal gradient. This phase resulted in the quartz-barite-calcite vein filling of the host rocks. Gold mineralization took place later at shallower depths. Primary organic material in carbonaceous ores from the Carlin and other mines appears to be a pyrobitumen residue derived from an old oil pool that had been heated by the thermal solutions, and from which the light hydrocarbon fractions were removed. Some of the bitumen was remobilized along silicified veinlets in the ore, but its role in the emplacement of the gold, itself, is not clear. The gold was localized submicroscopically in fine pyrite, mostly in framboids, and as fine metallic particles, but does not appear to be concentrated within the carbonaceous matter per se. However, reducing conditions associated with bituminous residues are believed to have been favorable for gold deposition.

Jan 1, 2013

By R. A. Limons

Natural ores, sinters, and pellets were subjected to a carbon monoxide reduction-disintegration test under laboratory conditions including a simulated blast furnace gas and a 1000°F temperature. The most significant findings were that: 1. Self-fluxed pellets broke down to a greater extent than either the acid pellets or the acid or self -fluxed sinter. 2. When pre-reduced, both the acid and self-fluxed pellets had very good resistance to breakdown.

Jan 1, 1964

By David J. Dunn

Materials related problems at mines can be big ones - like a newly completed 1 -m (3.5ft) water pipeline burst during initial filling, grinding ball consumption at double the typical norms on startup of a new semiautogenous grinding (SAG) mill circuit or 30 open-pit haul trucks in the shop for new bed liners after less than a year’s service. Materials engineering provides solutions to these kinds of equipment problems by selecting good materials and designs, by trouble-shooting service failures and by maintaining high quality in vendor-furnished materials and components. Materials with good properties, correctly made and fabricated, correctly installed in mining and processing equipment, produce ore and final products reliably and efficiently. Materials engineering, applied during design phases, specification writing, and receipt and installation of materials, ensures that equipment will have the best possible shot at performing up to expectations. Good calls on materials properties - specifying state-of-art materials produced by competent manufacturers - help mine managers to reduce downtime and mining and processing costs. Materials that are improperly made or specified can make a mining operation less efficient or, possibly, uneconomical.

Jan 1, 1992

By Eric Lundgren

The mining paradigm is changing on the continent of Africa. Jessica Kogel?s closing statement from her September 2013 President?s Page (ME, September 2013, pp. 6) has never been more appropriate, ?Africa is shaping up to be the next mining powerhouse, and there is huge opportunity for local communities, national governments and private industry to work together to create a win-win situation for all.? Supporting this notion, attendance at numerous industry conferences around the world demonstrates the shift toward a more sustainable, more environmentally conscious extractive model. But questions remain: How effectively is the industry making this transition, and how willing are companies to learn from the experiences of others? The international development community, as we like to call ourselves, is going through a parallel shift. We are experiencing our own funding crisis; governments are not as flush with resources as they were pre-economic meltdown. But more importantly, after a half century of implementing development programs, we must admit that while some of our programs have been fantastically successful, too many still fail to achieve the goal of poverty alleviation for the world?s poorest. Moving forward, we are forced to recognize that achieving success in scale and sustainability is not always accomplished from our work alone. As the director of international programs for Africare, a nonprofit with more than 40 years of experience implementing community-based development programs in Africa, I can report that our organization is changing the way we think about successful development partnerships. Africare recognizes that for too long the mining sector and nonprofits have been at odds, choosing noncommunication as a ?solution? to the problem. Both sides now recognize that this standoff is outdated, and Africare, specifically, is ready to cross the proverbial line. We see the potential benefits of mining for local communities and, when done responsibly, the opportunity to properly manage Africa?s resource boom as a benefit to all. There are challenges in this conversation. Many mining professionals view nonprofits as whistle-blowers, ready in a pinch to speak to news sources and complain about poor operational standards. Those are advocacy organizations, and while their role is important, they are not the only nonprofits interested in mining operations in developing countries. Organizations like Africare, with decades of experience implementing poverty reduction programs, approach this differently. We know we can work with mining companies to promote economic opportunity in the communities where mining operations are occurring. We recognize that the conversation is difficult, and we are open to discussions about how we can bring our unique experience to bear on the problems faced by mining companies in carrying out their investment programs.

Jan 1, 2014

By R. L. Pozzo

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite-grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying the Faraday's Law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a nonmagnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-electrode system involving pyrrhotite, pyrite and grinding media was also investigated as a first step towards elucidating the nature of interactions that occur in the grinding of complex sulfide ores.

Jan 1, 1987

By R. O. Burt

The paper examines the role of gravity concentration in both an historical contest and within the modern mineral processing industry. It discusses the principles of the process on both a theoretical and practical level. The importance of ore mineralogy and its effect on the choice of the wide range of equipment available is discussed. The paper concludes with a discussion on the relative merits of gravity concentration to other forms of processing and seeks to answer the classical question - "Quo Vadis?"

Jan 1, 1982

By Hubert E. Risser

At the outset of a discussion on the adaptability of Illinois coals for use in iron and steel production, it is perhaps well to define terms. ?Adaptability? as used in this context, means that a coal can be, adapted to use within a given technological and economic framework. For a coal to be adaptable, to use in the manufacture of metallurgical coke within the present technological and economic framework, it must possess, among other things, at least the following characteristics: 1. The coal must be capable of producing, alone or in combination with other coals, a coke that can meet at least a minimum standard of required performance in the present-day blast furnace. The coke must have sufficient strength, stability, hardness, and freedom from impurities to make it suitable. 2. If the coal in its raw form does not meet these requirements, it must be amenable to beneficiation or upgrading so that the requirements can be met. 3. It must be available in uniform quality and in sufficient quantities to meet the need. 4. Use of the coal must be economically attractive. If its quality is equivalent; to that of the coals with which it must compete, it must be no more expensive than they. If It is better, a premium price may perhaps be demanded. If, in any respect, it is the least bit less suitable, the cost must be lower to offset its disadvantages.

Jan 1, 1961

By L. A. Taylor

The production of oxygen on the Moon utilizing indigenous materials is paramount to a successful lunar colonization. And several processes have been put forth to accomplish this. The LLOX generation schemes which have received the most study to date are those involving?: 1) the reduction of ilmenite (FeTi03) by H2, C, CO, CH4, CO-CI2, & Cl2 plasma, 2) magma electrolysis, both unadulterated and fluoride-fluxed, and 3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reductions of ilmenite and magma electrolysis processes have received the most study to date. They are both feasible schemes with various pros and cons, including their feedstock requirements. However, all processes should be addressed at least at the onset of our considerations. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and this paper reviews several of the most studied and feasible processes for winning oxygen from lunar materials.

Jan 1, 1991

By Rodolfo V. de la Cruz

The in-situ deformability of a highly jointed basalt rock mass was determined by two distinctly different methods: one, by the NX- borehole jack method where the displacements of opposing curved platens were related to the applied hydraulic pressures, and; two, by the modified Goodman jack method where the tangential strains on the borehole walls were related to the induced tangential stresses. The modulus obtained by the modified Goodman jack method were much higher than those obtained by the NX- borehole jack method. To explain the discrepancy, the influence of fractures and test variables such as depth, orientation, hole number and applied pressure on the calculated modulus of the rock mass were analyzed by factorial analysis and it was found that the orientations and depths of measurement has statistically significant effects. The in-situ deformability values obtained by non-linear regression analysis were also found comparable with other measurements and empirically predicted values for the basalt rock mass.

Jan 1, 1982

By W. P. Diamond

The Bureau of Mines has been investigating several techniques, including the use of horizontal and vertical boreholes, to remove gas from coal in advance of mining. Horizontal boreholes drilled from underground workings as part of the mining cycle have been shown (Finfinger, 1980; Hagwood, 1983; Perry, 1978; Prosser, 1981; Thakur, 1980; VonSchonfeldt, 1982) to be very effective in providing short-term, immediate relief from high methane emissions. This technique has been widely accepted in the coal mining industry, but it does require close coordination to integrate the drilling and subsequent gas drainage and disposal into the projected mine development plan. Vertical boreholes can be placed several years in advance of mining to predrain gas from coalbeds over relatively large areas (Dunn, 1984; Elder, 1975; Lambert, 1980; Steidl, 1978; Stubbs, 1979). The vertical borehole technique has the additional advantage over horizontal boreholes of allowing work to be performed on the surface instead of in the more restrictive underground environment. However, except for the relatively large scale vertical borehole programs for both mine safety and commercial production in the Black Warrior Basin of Alabama (Dunn, 1984; Lambert, 1980; Stubbs, 1979), the technique has been underutilized. The primary reason for this seems to be a combination of the current economic climate in the coal industry, legal questions as to the ownership of coalbed gas, and potential roof damage from the stimulation treatments required to increase the characteristically low permeability of coalbeds to enhance gas production. The question of potential roof damage is the subject of this paper.

Jan 1, 1985

By Ted H. Eyde

Both private industry and the Interior Department have become alarmed about the enormous amount of Federal land that has been withdrawn from appropriation either under the Mineral Leasing Laws or the Mining Law of 1872. According to a recent article by Gary Benethum and L. Courtland Lee, governmental actions have withdrawn nearly 400 million acres from the operation of the Mining Law of 1872 and over 500 million acres from the Leasing Laws. An addition al 100 million acres for the Mining Law of 1872 and 70 million acres for the Leasing Laws are either encumbered or being managed in such a way as to constitute a defacto withdrawal from mineral development. This means simply that mineral exploration end development under the Mining Law of 1872 is either prevented or discouraged in an area the size of the states of California, Arizona, Washington, Oregon, Nevada, Utah, Idaho, and one half of Colorado combined. Under the Mineral Leasing Laws, exploration and development is either prevented or discouraged in an area equal in size to all the states east the Mississippi River, except Maine.

Jan 1, 1976