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By D. C. Torre

Ever since the early '60's there have been efforts to develop and produce reliable continuous haulage systems capable of taking the full output of a continuous miner and transporting it, in one continuous flow, from the face to the tipple. The majority of the continuous haulage systems which have been most successful to date were placed in operation in the early '70's and were all of the bridge conveyor type, usually consisting of bridges and mobile bridge carriers attached at the inby end to the continuous miner and at the outby end to the panel conveyor itself. These successful bridge conveyor type continuous haulage systems were, and continue to be, either of the belted or chain type. Undoubtedly, the most successful belt type continuous haulage systems are those manufactured and marketed by the Long-Airdox Company. Until early 1977, the most successful chain conveyor type haulage systems were manufactured and marketed by Jeffrey Mining Machinery Division. In 1977, Long-Airdox reentered the market with a chain type system to complement its belted system. I say "reentered" because the original bridge type continuous haulage system was introduced to the coal mining industry in the early '60's by the old Long Company, a predecessor of the current Long-Airdox Company, and those original units were of the chain conveyor type.

Jan 1, 1981

"Tell us how you got involved in mining?I was first exposed to mining at a young age, as a consequence of my dad and his passion for the industry and rock collecting. Even though he graduated with a degree in mining engineering from Washington State University, my dad spent most of his career working as a structural engineer for the Boeing Company. At the time, Boeing supported a range of employee activities and clubs, including one devoted to mineral prospecting, small-scale dredging and rock hounding. My dad was extremely active in the Prospectors Club, where as a family, we spent a good part of my youth tramping around the Pacific Northwest digging for mineral specimens and panning for gemstones and gold. On my mother’s side of the family, I had relatives that mined in Dawson City and Fairbanks, AK which left a family legacy of sorts. I loved the stories that my dad and a close buddy of his, who was a geologist, would tell about various operations and towns, as well as the wild times at the annual Northwest Mining Association (NWMA) meeting in Spokane, WA. My first recollection of ever being at a commercial operation was during a tour of the Bunker Hill Mine with my dad when I was 7 or 8 years old; this had to have been shortly before the May 1972 fire at Sunshine. That visit of the mine and processing facilities made a permanent impression on me. While I always knew there was something special about the Silver Valley, I began to understand why. To this day, I still get the same feeling when I visit historic mining districts like Leadville, Morenci, Virginia City, Butte, Silverton and Barkerville. During our summer excursions to Helena, MT to dig sapphires, we would usually make visits to Butte and watch mine operations inside the Berkley Pit and surface activities at the Kelly and Mountain Con. In high school, I did well in math and science and began entertaining thoughts of pursuing a degree in engineering. Above all, I wanted to go to a college in the West that had a good academic reputation, where I could also play football. As a 6-ft, 190-lb nose guard, my options for a Division I scholarship were pretty slim, and there weren’t that many technical schools in the Northwest that were Division II that offered athletic scholarships. As fate would have it, I was unexpectedly contacted by Marv Kay, a legendary coach at the Colorado School of Mines (CSM), and was recruited to play ball. Fortunately, I had a couple of high school friends who were already attending CSM, and I had just secured a summer internship with Asamera Minerals in Wenatchee, WA. It was as if all the stars had aligned, and, with the support of my parents, I made the decision to attend Mines. Despite the stress of getting through CSM during a period when the mining industry was in freefall, it was a great decision to attend Mines, and I’m thankful for all the opportunities, friendships, and faculty mentoring I received as a student"

Mar 1, 2019

By S. J. Root

The mineral processing industry supplies raw materials to a wide variety of manufacturing sectors. Large companies such as Ford, Microsoft, and Johnson&Johnson have pledged carbon neutral supply chains in the coming decades, leaving suppliers to reevaluate their energy sources [1–3]. National Renewable Energy Lab [4] has partnered with over 700 organizations with similar goals in mind. The energy needs are broad in scope in the mineral processing industry. Generation IV of nuclear reactors, which is currently under development in both the private and public sector includes a class called microreactors like the small modular reactor XEnergy plans to install at Dow Chemical’s Gulf Coast facility by 2023 [5]. As the name implies, these are smaller than the utility scale nuclear power plants in operation today, and are intended to be more versatile. A specific reactor core design, along with modules could be selected to fit a certain application without needing to design a greenfield power plant. Basic water cooled designs could easily supply shaft work, electricity, and low grade process heat to a facility. More advanced designs, such as molten-salt-reactors and high-temperaturegas-reactors can achieve higher temperatures needed for ore roasting. Similarly, these reactors could produce hydrogen by high temperature electrolysis to use as combustion fuel and reducing atmosphere in blast furnaces.

Feb 1, 2023

By S. S. Klima, A. L. Mazzella, J. S. Driscoll, T. W. Beck

Previous testing was performed by researchers at the National Institute for Occupational Safety and Health (NIOSH) to improve longwall dust control using underside shield sprays with a longwall directional spray system. This testing provided encouraging results toward respirable dust exposure reductions for longwall personnel, achieving as high as 99% dust reduction at some sampling locations along the longwall personnel walkway. Additional laboratory testing was conducted to test these underside shield sprays in conjunction with a shearer-clearer spray system located on the longwall shearer body. The purpose of this testing was to determine if the underside shield sprays interacted positively or negatively with the shearerclearer sprays. Results from this testing indicate that while the shearerclearer system influences where the respirable dust particles are directed, underside shield sprays can still lower respirable dust exposure for longwall personnel.

Mar 2, 2022

By B. Boutilier, R. Mendoza

"First Majestic Silver Corp. (FMS) is a silver mining company founded in 2002 that operates exclusively in Mexico. It has six producing silver mines, one of which is the La Encantada silver mine (La Encantada) located in the state Coahuila. La Encantada is located near the southern United States border and 708 km (440 miles) north of the city Torreon.La Encantada is located in the Sierra Madre Oriental and is a high-temperature carbonate replacement deposit. Mineralization in La Encantada occurs in many different forms such as veins, chimneys, breccia pipes and reefs (mantos). Mineralization is mainly oxides of iron, zinc, lead and manganese, with high concentrations of sulfides at depth relating to two main intrusive events: the Milagros Intrusive and the La Prieta Skarn.Mining began in La Encantada during the 1950s with small vertical shafts, drifts and raises. It focuses on the high-grade silver zones using traditional hoists and extraction methods, before branching into two main separate mining camps: El Plomo and Penoles camp. Penoles, the previous owner, focused mainly on large ore bodies using post pillar cut-and-fill mining method to extract the higher-grade material. Due to the type of ground, irregularity of pillars, and rock conditions, large amounts of high-grade pillars had to be left in situ to ensure the stability of the excavations. The mined-out areas would then be filled with lower-grade material to assist in the stability of the secondary level. These room-and-pillar development entries were 2.5 m x 2.5 m (8.2 ft x 8.2 ft) and spaced every 10 m (32 ft), leaving a vertical pillar of 7.5 m (25 ft). First Majestic acquired La Encantada in 2006. After the acquisition of the mine, the company began the conversion of the surveying reference system from a local grid (Maria Isabel Shaft as 0,0) to the Nav27 coordinate system, and subsequently converted to the WGS84 coordinate system in 2015. Due to the extensive history of the mine, different areas were surveyed with different systems, causing significant challenges when designing the principal extraction levels, pillar heights and ramp locations. To overcome this difficulty, the entire mine was resurveyed and the old workings transposed to the new coordinate system, except for some inaccessible areas due to poor ground conditions or ground collapses. To further ensure pillar height and the safety of the mine workers, probe holes were drilled during the development process."

Sep 1, 2019

By W. M. Middleton

The exploiting of geothermal steam is a new endeavor in this country and is for that matter a very new science in the world. With the majority of steam wells in the world having been drilled during the last twelve years relatively little experience and knowledge has been gained that can guide us as compared to the techniques the oil and gas producers have developed for their use. We few technical personnel associated with the field find it a continuous challenge to understand and explain what effects or causes the various unusual phenomenon experienced. We have had unending discussions attempting to formulate pet theories which we can use as guides. We know, so the geologists tell us, that the source of the heat is from the hot magmatic core of the earth. Theory has it that the magma is cooling off and that hot gases are given off as this magma cools and shrinks. In volcanic' areas along fault lines where the magma reaches closer to the surface than in other areas, there is a higher concentration of gas evolution; consequently, geyser or geothermal areas are developed. As these hot gases rise toward the surface they encounter various minerals, including overlying bodies of water. It is into these underground lakes that our wells are penetrating. As the heat enters these lakes it spreads out by conduction, convection and water migration. We can strike this hot water over quite large areas in many of the geothermal fields. At present there is one anomaly to this in the United States as there is in Italy where our wells do not penetrate a hot water lake. This is at The Big Geysers in California. Here superheated steam is produced with a heat content, so high that it could not have been boiled off of a fresh water pool. This puzzled us until last year when a well was completed into a large body of brine in the Imperial Valley. This brine exists at close to 500°F and at a hydrostatic pressure sufficient to preclude any boiling. It is now believed by some of us that a similar pool of brine must exist below The Big Geysers area, from which the steam is emanating. If there is such a brine pool, it offers a plausible explanation of the high-heat content, for brine boils at a higher temperature than fresh water. I am now beginning to think that a similar brine pool may exist under all the geothermal basins for if it is under two of them, it is highly probable that it is under the others. The partial understanding of what we are drilling toward, and formulating a theory to explain its behavior helps guide us in our steam well drilling.

Jan 1, 1963

By Gary E. Slagel

The federal Office of Surface Mining (OSW) has undertaken an effort to revise many of their permanent program regulations. Numerous procedures for compliance are being rewritten to allow for greater flexibility while meeting the requirements of the Surface Mining Control and Reclamation Act. This study investigates, for certain select provisions, the cost differential between complying with the original OSM standards and the more flexible, state-specific standards being allowed in many of the revised regulations. Estimated cost savings that could be realized under a few of the revised regulations are substantial and should provide a basis for seeking revisions to the state regulatory programs.

Jan 1, 1982

By M. K. Mohanty, H. Akbari, L. A. Ackah

Dry separation was the predominant method of coal cleaning in the United States from the 1930s to 1980s. The application peak of dry separators for cleaning raw coal was in 1965, when about 23.1 Mt of cleaned bituminous coal was produced. The main advantage of dry coal cleaning is the elimination RIWKH GHZDWHULQJ VWDJHV DQG VLJQL¿FDQWO\ UHGXFHG moisture in comparison to wet processing. In addition, developed dust control systems have made dry cleaning method an environmentally friendly process. The largest air-based coal cleaning plant was built in Pennsylvania in 1968 and could clean 1,272 t/h of raw coal sized smaller than 19 mm. This was followed by a decline in dry coal cleaning to less than 3.6 Mt in 1988. Some of the main reasons that shifted coal operations IURPGU\WRZHWSURFHVVLQJZHUHWKHQHHGIRUPRUHHI¿FLHQW separations with lower density cuts, increase in raw coal surIDFHPRLVWXUHVSHFL¿FDOO\LQXQGHUJURXQGPLQLQJWRFRQWURO GXVW ¿QHUSDUWLFOHVL]HUHTXLUHPHQWV LQFUHDVHLQ¿QHVLQUDZ coal from underground mines, and health and safety concerns related to dust and noise (Arnold, Hervol and Leonard III, 1991; Miller, 2011).

By Jean-Michel Rendu

That you are giving the Daniel C. Jackling award to me is a great personal honor. But more significantly, it is a recognition that geostatistics has come of age. And since I am considered by many as belonging to an older generation of geostatisticians, I thought that it would be fitting that I reflect on where geostatistics came from and where it might be going. First, though, let me propose a definition of geostatistics. Etymologically, paraphrasing Webster's definitions of "geo" and "statistics," it is "a branch of mathematics dealing with the collection, analysis, interpretation and presentation of masses of numerical data taken from the earth." This definition is most appropriate in the context of mining geostatistics. It includes both classical and spatial statistics. It emphasizes the earth aspect, or the analysis of geologic features. And it should remind the practitioner that geologic input is a critical part of all geostatistical applications. In the 1910s, statistical methods were already used to analyze geological data. However, the origin of geostatistics, as we know it today, is best set in the late 1940s, when H.S. Sichel recognized the lognormal distribution of sample values in the South African gold mines. In 1951, Daniel Krige observed that "it can be expected that the gold values in a whole mine will be subject to a larger relative variation than those in a portion of the mine." In other words, samples taken close to each other are more likely to have similar values than if taken farther apart. This observation is the foundation on which spatial statistics, which characterizes values defined in a multidimensional space, is built. However, the 1950s were marked by studies based on classical, as opposed to spatial, statistics. It was only in the 1960s that the need was recognized to model the similarity between sample values as a function of the distance between samples and that the semivariogram was defined. A theoretical framework was developed by Matheron that supplied an elegant mathematical explanation to the empirical observations made by Krige. Matheron coined the term "kriging" in recognition of Krige's pioneering work on the geostatistical evaluation of mineral deposits. As soon as this theoretical framework was developed, it was possible to bring geostatistics to the academic world. The "Centre de Geostatistiques" was founded in Fontainebleau. Numerous students were trained there, disciples eager not only to improve the theory and develop more sophisticated mathematical tools, but also to spread the new faith throughout the world. Expansion of geostatistics exploded in the 1970s, arguably the most fertile decade if it is judged by the frequency of theoretical breakthroughs, the number of original publica-

Jan 1, 1995

By C. T. Wallace

Evans Industries, Inc., a management coal consultant and company was assigned to evaluate National Steel Company's coal properties in Knott and Floyd Counties, Kentucky. The results of evaluation showed large reserves of good quality, high volatile metallurgical coal contained in the Elkhorn coal beds and resulted in the formation of Beaver Creek Consolidated Coal Company. Based on results of the exploration and feasibility work, the decision was to install a coal nine, preparation plant and related facilities having a production capacity of one' and three quarter million tons per year with Evans Industries acting as Beaver Creek's management company. The recoverable tonnage assigned to the Stinson Mine is approximately forty-five million tons. This paper discusses the general arrangement of storage, conveying, loading, refuse disposal facilities and the flow sheet of the preparation plant developed by engineers of Heyl & Patterson, Inc., and Evans Industries, Inc., with emphasis on practical flexibility, sulfur reduction in all circuits, and high product yield with the minimum amount of selective mining, Three and one-half miles of railroad have been built by the Chesepeake & Ohio Railroad to service this mine.

Jan 1, 1970

By John T. Langstaff

Rock bursts in the deep metal mines of the Coeur d’Alene district present an ever increasing problem in the safe and economic mining of the district’s silver, lead and zinc ores. Hecla Mining Company operates two mines in the district - the Star, a 1100-ton/day lead-zinc mine, and the Lucky Friday, a 750-ton/day silver- lead mine. Rock burst problems at both operations prompted Hecla management to make an all-out attempt to find a practical method of predicting and eventually controlling these bursts. Research by personnel from the Denver Research Center of the Bureau of Mines at ASARCO's Galena Mine indicated that a recognizable pattern of seismic activity preceded some bursts and this activity could be precisely monitored by present- day, off-the-shelf electronic devices. Using information gained by the Bureau and other sources, Hecla designed and installed a 24,- channel seismic monitoring system in the Lucky Friday mine. Installation was completed in December 1973 and after a year of successful operation, it was decided that a similar system would be installed in the Star mine. This second installation was completed in June 1975. Both systems are now operating and providing continuous information on underground seismic activity. Each monitoring system consists of a network of geophones with attendant amplifiers that are connected by shielded cable through an interfacing device to a computer. The origin of each seismic event is determined by the computer and a three-dimensional location is printed out. This information is plotted daily and is used to pinpoint rock burst prone areas and chart their relative seismic activity. This paper will review the causes and effects of rock bursts in the Coeur d'Alene district, the equipment and operation of the microseismic system at the Star and Lucky Friday mines, and the results obtained to date.

Jan 1, 1977

By Roy A. Grancher

CYCLING WITH CEMENT "THE WHEEL IS COME FULL CIRCLE" Shakespeare's King Lear Act V, Scene 3, Line 176 The time clock of the cement industry has been turned back to the early 1950s. After the trials and tribulations of the decade of the Sixties, the hands now stand where they did just over twenty years ago. Cement shipments have steadily increased, with a record 419 million barrel level (78.8 million tons) being reached last year. Plants are operating at average utilization rates in excess of 85 percent of rated capacity. The spread between supply and demand has narrowed to where a definite shortage of cement now exists within the industry. The notable and unfortunate difference between the two periods however is that, back then, cement's returns were a respectable 14 to 18 percent, whereas today they stand at less than half those levels. Insufficient return forms the present foundation of the U.S. cement industry. This lack is destined to have a cumulative effect. Just as the industry's balance between supply and demand is returning to favorable proportions, promising a period that has historically and now should generate those profit levels required to modernize and provide for capacity addition, cement instead finds itself frozen by federal price controls into the semi-depressed condition that has existed for over a decade and from which it was just starting to emerge. Capital is not attracted to continued low returns, and increasingly restrictive pollution control measures are necessitating great non-productive expenditures be made as definite costs to stay in business. Even a clouded crystal ball would reveal that additional cement plant closings can be expected.

Jan 1, 1972

By O. M. Johnson

Barite and bentonite are the two principal components of drilling fluid systems used in the petroleum industry for oil and gas well drilling with rotary-type rigs. Approximately 87 percent of the world's annual production of barite is used in drilling applications. Of the worldwide production of bentonite, an estimated 30 percent is used. The drilling fluid, or drilling mud, to which barite and bentonite are added, performs five distinct functions: Lubrication-The liquid phase of the drilling mud lubricates the drill bit, preventing premature failure of the cutting edges and bearings. it also helps to soften the formation being drilled. Cuttings Removal-A mud system must be able to carry rock cuttings broken loose by the bit up to the surface where they can be removed by mechanical or chemical methods. The fluid's ability to perform this function depends upon maintaining a proper balance between the rate of circulation of the fluid and the colloidal properties required to entrain the cuttings in the mud to prevent their settling to the bottom of the hole. Hole Stability-The pressure exerted by the mud against the wall of the bore hole prevents the collapse of the uncased portions of the hole. Downhole Information-The fluid characteristics of the mud should be such that good cuttings samples, cores and electric logs may be obtained to help evaluate a well's productive zones and potential. Control Oil, Gas and Water Flows-It is essential that a drilling fluid offset any pressure from naturally occurring formation fluids in order to prevent a potentially wasteful and dangerous blowout.

Jan 1, 1980

By D. Suarez

The work of engineers responsible for the design and performance of mine facilities is often challenged by economic and practical constraints in the field. Problems have developed in implementing design criteria dictated by persons or agencies not familiar with the dynamic nature of mine engineering. Regional and site-specific conditions frequently require changes to standard designs, or the use of a completely innovative approach, which is not provided for in the regulations. The implementation of engineering design, therefore, usually requires a hard-sell approach to management and regulatory agencies that allows for a happy-medium to all parties concerned. Flexibility on the part of the regulatory agencies is needed to solve operational and environmental problems with sound engineering. Typical hydrologic issues which will be discussed fall in the following general categories: ? Design criteria for sizing water control structures (i.e., culverts, diversion and sedimentation ponds, ditches, etc.) ? Implementation (construction and operation) difficulties ? Regulatory compliance ? Reclamation planning with hydrologic considerations ? Protection of groundwater resources

Jan 1, 1986

By E. D. Gardner, William O. Vandenburg

This chapter on the square-set system of mining em¬bodies the results of a special study of the subject made as a part of the US Bureau of Mines (USBM) general investigation of mining methods and costs. Data for the chapter were gathered by the authors during visits to mines using square-set mining, from information circu¬lars prepared by consulting engineers to the USBM on mining methods at individual mines, and from articles in the technical press and the Transactions of the American Institute of Mining and Metallurgical Engineers. Al¬though some of the properties discussed are no longer in operation, the methods described are still valid. The square-set system of mining has been very widely applied and is one of the oldest methods in use in the US. It is mainly employed for extracting rela¬tively high-grade ore in heavy ground. It is also useful in taking out pillars left in mining by other methods. It is used to some extent as an auxiliary method with many underground systems and as an alternate with cut-and¬fill, shrinkage, and open-stope methods when heavy ground is encountered. In some cases as much as 50% of the ore may be extracted by square setting at mines listed as using some other method of mining. A large tonnage has been mined yearly by square setting, prin¬cipally in the western states. Due to the high cost of timber and the relatively low average production per manshift, this system generally is not used when the ore can be mined by some other method; it usually is adopted as a last resort. Square setting, however, has a special field in that ore bodies not minable by other methods can be stoped by this system. As square-set mining was widely known, there was a tendency for years to use the method regardless of its suitability. With the increasing need for economy and the development of other methods, square setting has been superseded in many mines by cut-and-fill, top slic¬ing, or sublevel caving methods. The term square-set mining as used in this chapter includes all stoping methods in which the space made by the removal of the ore is timbered with framed sets. The sets usually are square in horizontal section. The stope may or may not be filled with waste rock as stoping progresses. HISTORY OF THE SQUARE-SET SYSTEM Prior to 1860, open-stope methods with stulls for casual support accounted for most of the mineral pro¬duction from underground mines. Attempts to mine large ore bodies that required artificial support resulted in disastrous cave-ins and loss of life. The art of mining received a tremendous impetus following the introduc¬tion of methods for mining the bonanza ore body which was discovered in 1860 in the Ophir mine on the Comstock lode, Virginia City, NV. This ore body was phe¬nomenally rich and eventually proved to be 122 m (400 ft) high, 27 m (90 ft) wide, and 98 m (320 ft) long. The mining of this large high-grade ore body taxed the best engineering talent of the time; the problem was finally solved by Philip Deidesheimer. According to Eliot Lord (1882): "At the 50-foot level the vein of black sulphurets was only 3 or 4 feet thick, and could be readily extracted through a drift along its line, propping up the walls and roof when necessary by simple uprights and cap-posts. As the ledge descended the sulphuret vein grew broader until, at the depth of 175 feet, it was 65 feet in width, and the miners were at a loss how to proceed, for the ore was so soft and crumbling that pillars could not be used to support the roof as in coal mines. They spliced timbers together to hold up the caving ground; but these jointed props were too weak and ill-supported to with¬stand the pressure upon them, and were constantly broken and thrown out of place. The dilemma was a curious one. Surrounded by riches, they were yet un¬able to carry them off and their mass of black sulphurets bade fair to become a white elephant on their hands. The Ophir Company began to wish themselves less for¬tunate, as their miners narrowly escaped burial day after day in their attempts to stope out the ore. "A young mining engineer, Philip Deidesheimer, was in charge of a quartz mine in Georgetown, El Dorado County, Calif., in the autumn of 1860, when this serious check to the development of the lode occurred. At the request of William F. Babcock, a trustee of the Ophir Company, Mr. Deidesheimer left his California mine and crossed the mountains with a letter from the direc¬tors of the Ophir Company, authorizing him to inspect the workings of their mines and make such changes in the method of timbering as should seem to him expe¬dient. After examining the vein he designed, in the course of a few weeks, a system of timbering which proved to be exactly adapted to the requirements of the work. Experiments which he had previously made in California gravel and quartz mines furnished the out¬line of his plan. This was to frame timbers together in rectangular sets, each set being composed of a square base, placed horizontally, formed of four timbers, sills, and crosspieces from 4 to 6 feet long, surmounted at the corners by four posts from 6 to 7 feet high, and capped by a framework similar to the base. The cap pieces forming the top of any set were at the same time the sills or base of the next set above. These sets could readily be extended to any required height and over any given area, forming a series of horizontal floors, built up from the bottom sets like the successive stories of a house. The spaces between the timbers were filled with waste rock or with wooden braces, forming a solid cube when¬ever the maximum degree of firmness was desired. By adjustments of these sets the ore bodies along the line of the lode were extracted with comparative ease and security." Most mining methods are evolved slowly and are the result of the combined efforts of a number of minds; Deidesheimer's feat was remarkable in that his system was immediately successful. He died in 1916 at the age

Jan 1, 1982

By Changjiang Li, Jun Yang, Qiang Fu, Xu Chang, Xing Wu, Yubing Gao

With the development of underground mining, the deformation of roadway floor has increasingly become a major constraint on the safe and efficient production of coal mines. To address the floor deformation that was caused by massive stress concentration in roadway, an innovative method based on deep-hole directional tensile blasting technology is put forward. By taking No.122108 working face in Caojiatan Coal Mine as engineering background and analyzing the mechanism of deformation, a numerical simulation and field test are carried out to verify the effect on deformation control of this technology. It is found that the deep-hole directional tensile blasting technology can actively control the fracture position of the roof in the gob area and cut off the stress transmission path, so as to relieve the stress in the roadway. And since different blasting parameters have different impacts on the stress relief effect, a numerical simulation is implemented and it is found that the stress relief effect is the best when blasting depth is set to be 32 m and the blasting angle be 60°. By applying the optimal blasting parameters to the field engineering test, it can be seen that the deep-hole directional tensile blasting technology could effectively reduce maximum stress value and stress field range of the both sides of the roadway, and make the stress field far away from the roadway, thus effectively controlling the deformation of the roadway floor. The deep-hole directional tensile blasting technology can effectively solve the problem of roadway floor deformation and can be safely applied to engineering sites.

Jun 13, 2023

By U. Schoepf

Economic and at the same time environmentally acceptable mining of small vertical ore bodies and veins to great depths has always been a challenge for miners. The Bauer cutter system, widely used in civil engineering, has been further developed for applications in exploration and mining, to a sustainable system for selective mining with a focus on small vertical ore bodies and veins, as well as residual ore in open pit operations. Current situation of conventional mining of small ore bodies and vertical veins Small ore bodies and vertical or near-vertical ore veins often pose a challenge to the mining industry. The relatively small size of the ore deposit over great depths or lengths, with only limited exposure to the surface makes economical mining difficult. Open pit mining of such ore bodies must either be terminated early because of the high stripping ratio and the enormous environmental impact or is unprofitable from the very beginning. The required massive stripping of waste rock leads to high material hauling times and costs, intensive roadway and bench construction and maintenance, possible safety hazards due to heavy vehicle movement, pit wall stability risks, intensive surface water management and massive waste dump requirements. In addition, it can be assumed that increasingly extensive rehabilitation measures will be required in the future after mine closure. Particularly in vertically oriented magmatic and hydrothermal deposits the technical, economic and environmental limits for further pushbacks, to extend the open pit depth, can lead to an early end of mine life even if a significant quantity of residual ore is left behind. Going underground is only a viable option in a limited number of mines with very high ore values and volumes. The high development cost of an underground mine, as well as the higher underground mining costs, often prevent further mining to greater depths.

Feb 1, 2023

By W. L. Price

I. INTRODUCTION Today, there are two conflicting trends facing the designer of the bulk material handling system. The first trend is the necessity to stockpile increasingly larger amounts of bulk material (coal, ore, stone etc.) as economically as possible. Fig. 1 illustrates such a typical large storage pile. The second trend is the increasing awareness of the ecological problems of today manifesting itself in a new concern over possible air pollution from storage pile surface particles. The conflict between these two trends can become dramatic when this bulk storage pile is located near a heavily populated area. Strong winds can easily create a severe local problem by blowing the particles from the pile surface toward residential and commercial areas, igniting a crisis in public relations. (2), (3), (4). To help define our combined subject and ecological culprit more accurately, Fig. 2 shows the commonly accepted size range of dust particles. A descrip¬tion of the present state-of-the-art of dust control for large storage piles is the intent of this paper. II. OPEN STORAGE PILE SYSTEMS - ALTERNATE CHOICES AND RELATIVE COSTS In discussing the open storage dust problem and possible solutions, one obvious question arises - what are the economics of placing large bulk storage under cover? Part or this answer will be found in Fig. 3 - an approximate unit capital cost comparison between several methods of storage. It will be noted that the cost curve(s) for the closed concrete silo storage illustrated in Fig. 4 is cheaper per ton at relatively small tonnage capacities, but as tonnage increases, the open pile storage unit cost (B) becomes more economical. Curve (T) covers the cost of open storage using the plow feeder arrangement shown in Fig. 5. A gravity draw-down pile with feeders at the base as shown in Fig. 6 represents yet another open storage choice.

Jan 1, 1972

By C. L. Wilsey, K. M. Oakes, W. J. Reich, M. J. Protani

The time frame required to complete the National Environmental Policy Act (NEPA) process for a new mine or the expansion of an existing mine can range from nine to 24 months, or even longer. The time frame will vary depending on whether an environmental assessment (EA) or an environmental impact statement (EIS) will be completed Completing properly designed baseline studies to collect natural resource data to support the EA or EIS prior to the start of the NEPA process can shorten this time frame. In this paper, a two-year natural resource baseline study by Homestake Mining for the Ruby Hill Mine, Eureka County, NV, is used as a case study to describe how a properly designed and executed natural resource baseline study streamlined the NEPA process.

Jan 1, 2003

The introduction of nitro-carbo-nitrate (NCN) blasting agents has been one of the most significant innovations in the explosive industry in the last twenty years. The most commonly used blasting agent is a rather narrowly proportioned mixture by weight of 94% ammonium nitrate (AN) and 6% No. 2 diesel fuel oil (FO) that is generally designated as ANFO. Other formulations have been developed but none of these have been as extensively used as ANFO. The relative safety of the nitro-carbo-nitrate (NCN) blasting agents almost immediately suggested bulk loading techniques to obtain economies in materials handling. The first attempt at bulk handling was to pneumatically load boreholes with ANFO. When the initial experiments were made in 1957, it was apparent that there were three problem areas which needed study to minimize potential hazards. These were: 1. Static Electricity 2. Fumes 3. Safe Handling Procedures Since those early days, considerable work has been performed in evaluating these problem areas and in arriving at procedures and recommendations that would provide the required safety. Despite the relative insensitivity of ANFO type products, all normal practices for the safe handling of explosives should be obselved. Smoking should not be tolerated in the vicinity of blasting agents and misfires should be handled in the same manner as a misfire with a dynamite charge. The purpose of this Technical Report is to discuss the problems of static electricity and fumes and the solutions that have been developed. Safe handling procedures have been discussed by the Bureau of Mines and are specified by various state and local regulations. Since regulations vary from state to state, the local, applicable regulations must be followed within the area of their jurisdiction. General information is contained in a U. S. Bureau of Mines report, IC 8179, "Safety Recommendations for Sensitized Ammonium Nitrate Blasting Agents" (1963).

Jan 1, 1973