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By G. Heiken

On the Earth's Moon, obvious hazards to humans and machines are created by extreme temperature fluctuations, low gravity, and the virtual absence of any atmosphere. The most important other environmental factor is ionizing radiation. Less obvious environmental hazards that must be considered before establishing a manned presence on the lunar surface are the hazards from micrometeoroid bombardment, the nuisance of electro-statically-charged lunar dust, and an alien visual environment without familiar clues. Before man can establish lunar bases and lunar mining operations, and continue the exploration of that planet, we must develop a means of mitigating these hazards.

Jan 1, 1991

By Samuel S. Adams

Economic concentrations of potassium are essentially limited to thick, stratigraphic sections of marine evaporites. These deposits were precipitated through the evaporation of sea water in restricted epicontinental seas or in grabens related to continental margin rift systems. Following deposition the deposits were subjected to diagenesis and varying degrees of metasomatism and structural deformation. The origin and characteristics of potash deposits are easier to study and interpret than those of most ore deposits because the phase chemistry of the salt systems is known and the approximate composition of the ore-forming fluid (sea water) can be inferred with confidence. It is particularly helpful that the temperature and pressure of deposition approximated that of present earth surface conditions and the pertinent mineral assemblages can readily be duplicated in the laboratory. The study of these comparatively simple salt deposits provides examples of the practical advantages of understanding the genesis of an ore deposit. These observations, in turn, illustrate the importance of pursuing research on the more complicated magmatic, hydrothermal, and ground-water systems as a means to the more successful exploration for and exploitation of the deposits they have produced. It is the purpose of this paper, therefore, to discuss certain aspects of salt deposit geology as they contribute to exploration and mining through some understanding of ore formation. References to field examples and chemical relations in the salt systems are brief. All examples are more fully discussed, however, in the references cited.

Jan 1, 1970

By Shaoyang Yan, Xinming Chen, Huazhe Jiao, Huaibao Chu, Chang Wang

In terms of the technical problems of rib spalling in large mining height coal face, a long-distance advanced pre-grouting layer flexible reinforcement technology is proposed in this paper. Based on the mechanism and failure mode of rib spalling in the coal face, the mechanical properties of the aluminum plastic composite pipe were analyzed by using the tensile and compression experiment. The deformation and strength characteristics of “flexible pipe + grouting” specimens were studied by uniaxial compression test, splitting test, and shear test. The UDEC numerical simulation software was used to simulate the reinforcement effect of “flexible pipe + grouting” at different positions. Combined with the field application, the feasibility of long-distance advanced pre-grouting layer flexible reinforcement technology was verified. The test results show the following: The coal face has the characteristics of brittle and large deformation. The aluminum plastic composite pipe has the characteristics of good elongation and tensile strength, which can endure the large deformation of the coal face. The “flexible pipe + grouting” can improve the tensile and shear strength of coal. The UDEC numerical simulation analysis indicated that the grouting hole layout of “flexible pipe + grouting” has a significant difference in the reinforcement effect of the coal face. Compared with single row grouting reinforcement, the reinforcement effect of double row grouting holes 1.5 m and 3.0 m away from the roof is better. According to the field application, it is feasible to use aluminum plastic composite pipe as a flexible grouting pipe to reinforce coal seam with 80–100 m long-distance pre-grouting. Long-distance advanced pre-grouting layer flexible reinforcement technology can improve the daily production of coal and reduce the support cost of the coal face. As a new method of reinforcement, long-distance layered flexible reinforcement has a significant effect on the prevention and treatment of rib spalling in large mining height coal face.

Sep 27, 2022

By W. E. Adkins

Ore and waste haulage usually constitute one of the major cost items in the operation of an open pit mine. This has always been true at the Chino mine, one of Kennecott Copper Corporation's western mines, located in southwestern New Mexico. The Chino Mines Division is an integrated operation. The open pit mine, dump leaching operation, and a precipitating plant are located at Santa Rita, New Mexico, and a power plant, mill, smelter, and fire refinery are located in Hurley, New Mexico, about nine miles south of the mine. Approximately 22,000 tons of ore are mined and processed each day; in addition, approximately 42,000 tons of waste are removed from the pit. Originally the pit was located along the side of Santa Rita Creek but it has deepened and expanded so that at the present time, it could better be described as a nearly circular pit about one to 1.5 miles in diameter. The bottom is at an elevation of 5750 feet, the west rim near the ore gathering yard is at an elevation of 6230 feet, and the highest bench on the east side of the pit is at an elevation of 6750 feet, giving a vertical mining depth of 1000 feet. The train waste dumps reach a maximum elevation of 6580 feet. At the present time, Chino uses electric locomotives, off-the- highway trucks, and a skip system for mine haulage.

Jan 1, 1963

By Douglas W. Fuerstenau, Pradip Pradip

The design and development of selective flotation collectors has been the key to the remarkable success of flotation in beneficiating complex, difficult-to-process ores. It remains a challenging area of contemporary research in mineral processing.

By R. E. Miller

Accelerometers and pressure transducers mounted in suspension components can be used to monitor the ride of haulage trucks. Presently, it is difficult to tell what caused a jolt to the truck using either pressure or acceleration data alone. When information from a Global Positioning System is recorded at the same time as shock pressures or acceleration data, then the exact location of an event can be determined. Mine management can then determine what caused the jolt to the truck.

Jan 1, 1999

By K. C. Watts

The Silver City mining region is located in Grant County, southwestern New Mexico (Fig. 1). This area is well known, having produced large tonnages of base and lesser amounts of precious metals over the past several years. Mining within the region continues today, as well as exploration activity, which seems to have been on the increase since the recent discovery of a large skarn-associated Zn-Pb-Cu replacement deposit near Pinos Altos, a mineral district within the region (McKnight and Fellows, 1978). Because the Silver City area contains a number of mineral districts and retains promise for additional deposits, as suggested by widespread hydrothermal alteration and favorable igneous rocks, it was selected as the focus of two independent geochemical studies, both seeking to enhance anomaly-to- background contrast in order to improve our abilities to detect blind metal deposits or subtle manifestations of near-surface occurrences. The first of these independent studies involved the systematic sampling of those secondary Fe-Mn oxides that occur within coatings, selvages, and fault fillings, and then the selective extraction of these oxides from the host-rock matrix by chemical methods. The second study sought to isolate clastic Fe-Mn-rich materials from the heavy fraction of stream alluvium. The ultimate source of the clastic Fe-Mn oxides is presumed to be the same coatings, selvages, and fault fillings sought by the direct sampling of joints, but has been transported as a result of lateral erosional processes.

Jan 1, 1981

By A. B. Cecala

The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour(acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec(50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average mill-wide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al.,1987).

Jan 1, 1995

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi, Mohammad Raouf Hosseini

This study aims to investigate the effects of the operational variables on the concentrate grade, recovery, separation efficiency and kinetic parameters of the copper flotation process. The results indicate that concentrate collecting time and pulp density were the parameters with the greatest effects on the concentrate grade. Considering copper recovery, the concentrate collecting time, collector dosage and pulp density were the most significant variables, in decreasing order of importance. The separation efficiency was found to be mainly influenced by the concentrate collecting time. This study can be helpful in identifying the parameters with the most effects on flotation performance and, consequently, the overall process efficiency, including recovery and separation efficiency. Such an outcome can be used as a decision-based tool to apply the necessary changes in a real-life industrial operation in a more effective way to improve the quality and quantity of the flotation concentration.

By D. J. Turk

Faced with decreasing production from the gold heap leach operation, Robinson implemented a drilling and blasting program on the leach pads in 1993. This program offset some of the negative effects of low ore permeability and short circuiting of leach solution that resulted in lower than optimum recoveries. The drilling and blasting program created new solution flow paths and increased gold recovery. Production and pulp assays at depth intervals, prior to and following drilling and blasting, reveal the degree of short circuiting and benefits of the program.

Jan 1, 1995

By J. E. Bevan

Once mining compromises the stability of a rock mass, the dangerous task of roof bolting begins. Many attempts have been made to automate this process, but there are still many refinements that need to be made. In the past, roof bolting modules were designed around the abilities of a human operator. Currently, researchers are taking a new approach that focuses on designing modules that can utilize bolting methods that are easily automated. A non-rotating anchor that is locked into position by a linear force (as opposed to a rotational force) was designed by researchers at the U.S. Bureau of Mines. Once the bolt is secured in the bolt-hole by the anchor, the bolt is tensioned and a collet is used to secure the other end of the bolt. This process replaces the traditional bolt-nut fastening method. This program is part of an effort at the U.S. Bureau of Mines to automate the coal mining process.

Jan 1, 1994

By H. S. Soto

The exact reasons that explain the low recoveries of coarse particles in conventional flotation machines are not clear. Being a concern for only a couple of mineral industries comparatively very few studies have been devoted to the problem of coarse particle flotation. Coarse particles flotation is particularly important in potash and phosphate beneficiation. Potash concentrates with particles larger than 1-2 mm do not require additional compaction or recrystallization and receive a premium price. However, recovery of this size particle in conventional flotation cells is very low, and therefore, the coarse floation tailings have to be reground and refloated to produce, at a higher cost, a less desirable concentrate. In phosphate beneficiation deslimed coarse ore (nominally l4x35 or l6x35 mesh) is normally treated separatedly from the finer (35x150 mesh) ore. Concentration by conventional froth flotation alone yields very low recoveries, and therefore, additional processes such as agglomerate flotation in tables spirals and belt conveyors have to be used ( Moudgil and Barnett 1979). Fatty acids and fuel oil used in phosphate flotation have a moderate level of selectivity but considerable amounts of sand report to the froth product, thus concentrates have to be further upgraded by a double flotation process. Concentrates from the anionic circuit are scrubbed in an acidic media to desorb the collectors and then refloated in a cationic circuit to eliminate the fine silica (Lawver et.al. 1978). In this paper the reasons that explain the low recovery of coarse particles in conventional flotation are discussed. A flotation column modified according to the main conclusions of this discussion is tested with two coarse phosphate samples.

Jan 1, 1989

By M. L. Bricker

The Jim Bridger Mine is operated by Bridger Coal Company and is located in Sweetwater County, 35 miles (56 km) northeast of Rock Springs, Wyoming (USA). The general location of the mine site is shown on Figure 1. Bridger Coal is a joint venture of NERCO Coal Corp, the operator, and Idaho Energy Resources Company. The permit boundary encompasses in excess of 20,000 acres (81 km2) and is nestled against the western side of the Continental Divide. Production started on July 3, 1974, and the mine has produced approximately 90 million tons (82 million t) while moving approximately 450 million cubic yards (344 million m3) of virgin earth. Annual production averages 5 to 7 million tons (4.5 to 6.4 million t) of run-of-mine coal. Coal is consumed on site by the Jim Bridger Power Plant, a 2,000-megawatt generating station, and the electricity is transmitted to the Pacific Northwest power grid (Oregon, Idaho, Northern California, etc.).

Jan 1, 1991

By George White

On June 25, 1876 Lt. Colonel George Armstrong Custer led the Seventh U.S. Cavalry Regiment., comprising 31 officers and 637 enlisted men, into the valley of the Little Big Horn River in southern Montana. His assigned mission was a reconnaissance-in- force to locate the Indians reported to be assemblying in that area. Custer was extremely successful in locating the Indians. Unfortunately he located more than 3000 Cheyenne and Sioux under the leadership of the great war chiefs Crazy Horse and Gall. Custer's entire battalion of more than 200 men was annihilated; there were no survivors. While I don't seriously suggest that things will be all that bad in the uranium industry, I do suggest that some very fundamental changes have occurred in the uranium market. Conventional thinking based on past truths will no longer suffice. Geology, economics, politics, nuclear growth pat terns, technology, and utility attitudes have all changed. New thinking is in order. It is at this point that I would offer my usual disclaimer. My views regarding the future are simply that--my personal views. My belief that certain events will come to pass does not mean I view those events as appropriate, wise, good, equitable, or economic.

Jan 1, 1985

By T. Guler

Turkey has important celestite reserves in Sivas. These reserves have gypsum and/or calcite as gangue minerals. Celestite-calcite ore cannot be concentrated by gravity methods due to the low efficiency of gravity methods in fine sizes. Research was tried to concentrate celestite to a market grade by flotation. Parameters such as pH, particle size, dosage and types of collector and depressant were examined. Cyanamid A-845 and Na-oleate combination as collector, sodium silicate as depressant, and Aerofroth-65 as frother were found as the optimum flotation reagents. By applying 3-stage cleaning, a concentrate assaying 95,34 % SrS04 was obtained with 84,93 % recovery.

Jan 1, 1999

The authors provide a discussion of the paper, ?Coal workers? pneumoconiosis prevalence disparity between australia and the united States,? a peer-reviewed paper that appeared in the technical papers section of the July 2012 issue of Mining Engineering magazine. The original authors, G.J. Joy (gjoy@cdc.gov), J.F. Colinet (jcolinet@cdc.gov) and D.D. Landen (dlanden@cdc.gov), respond.

Jan 1, 2013

Longwall mining is a commonly used method of coal extraction that involves the complete removal of large, rectangular panels of coal. Longwall mining causes the immediate seam roof to break and fall into the void created by mining. The convergence of the surrounding strata towards the mining void causes subsidence on the surface. The subsidence magnitude is related not only to the mining depth, the topography, the geological features and the overburden materials, but also to the sequence of the strata overlying a coal seam. In additional to the vertical subsidence which is evident at the surface, there are also horizontal movements inwards toward the centre of the void, which cause the surface to tilt, bend, stretch and com-press. This paper presents a parametric investigation of the influence of the overburden stratigraphy to surface deformations due to longwall mining using 2D finite element models. Models simulate rock movement by applying equivalent edge load to the open roof.

Jan 1, 2008

By Victor F. Hollister

This first section of case histories of mineral discoveries, Vol. 3, covers some of the milestones in porphyry copper and skam exploration successes. It was during the era of these discoveries that large, complex exploration departments emerged as permanent adjuncts of large mining companies. The discoveries helped shape how and where exploration activity was conducted. Probably the most important factor in exploration success is management. Few management people are mentioned in this section or in any exploration history, yet the distinction between success and failure ultimately rested with the decisions they made. One of the most successful groups was initiated by Roger Straus and Herbert Brownell when they sought to make Asarco into an important metal producer. Relying on Clem Pollock and L.H. (Bill) Hart to identify and push worthwhile projects, the Asarco management remade the company. Asarco will benefit from exploration successes com- pounded by that team for years to come. Duval is an example of a management that decided to add metal production to its industrial minerals output. When Page Morris was president, that company opened three major porphyry copper mines and became an important factor in metals. Under the Monis management team, Duval became a leader in exploration. At the other end of the scale are managements that snatched defeat from the jaws of victory and by so doing changed the character of their companies in other ways.

Jan 1, 1991

By Franklin T. Matthias

No one involved in the contruction business wants litigation, except maybe some lawyers. Contractors rarely resort to litigation unless they have sustained econmic wounds that are serious or mortal. The major cause of serious contractor losses occur because of sub-surface conditions which cannot be defined with certainty in any practicable way except as shown during construction and prove during construction to be substantially worse and more expensive to cope with than anticipated during bidding. Building, Dam and Highway contractors are generally close in their estimates of cost after they get foundations excavated and are building above ground. Their main risk in bidding is the cost of getting out of the ground compared to their estimate. So maybe 10%, 20% or even 30% of their project represent high risk underground work. The tunneling and underground contractor is dealing with high risk work for virtually 100% of his project. He appreciates this risk and is willing to assume it up to a bearable limit. His costs are highly sensitive to relatively small variations of the ground in underground work. His work is unique in other respects. As contrasted with other types of construction where loads develop as construction progresses and do not reach ultimate until the project becomes operative, tunnel and underground construction requires the immediate structural support of ultimate loads that are there when he digs or very soon thereafter. He must put in enough support

Jan 1, 1974

By G. Deschenes, M. Fulton

The New Britannia Mine processes a qumtz-carbonate gold ore containing 4.63 git Au at a rate of 2,200 tpd. The ore contains approximately 3 .0% arsenopyrite, 2. 7% pyrite and the rest is gangue minerals. Eight to ten percent of the gold is refractory to leaching. Two years ago, New Britannia Mine experienced cyanidation problems. Gold extraction was not stable and occasionally decreased significantly. Preliminary test work, at laboratory scale and in the plant, indicated that lead nitrate addition was beneficial. A laboratory study was initiated to evaluate the level of control of the parmneters (grinding size, dissolved oxygen, pH, free cyanide and lead nitrate) to optimize the efficiency of the process. It was found that lead nitrate addition is required to alleviate the effect of metallic sulphides. This addition causes a significant increase in the gold leaching kinetics and a reduction in the cyanide consumption. The optimum system appeared to be: leaching for 24-30 hours at pH 11.8, 50 git lead nitrate, 250 ppm NaCN and 8 ppm 02. The gold extraction was 89.8% with grinding at 89%-74Fm (leached tail at 0.48 git). Cyanide and lime consumption are 0.40 kglt NaCN and 1.9 kglt respectively. Following the incorporation of lead nitrate, overall gold extraction was increased from 89.2% to 91.1 % but no change was noticed in cyanide consumption. The gross profit is $CDN 988,000 per year.

Jan 1, 1999