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By D. Whittles, S. Kingman, K. Jackson, S. Bradshaw, N. Miles

The influence of microwave energy at high electric field strength on ore strength has been investigated. Two ores of varying mineralogy were treated in both multimode and single mode microwave cavities. After treatment, any change in strength relative to untreated ore was established. It was shown that in the multimode cavity reduction in strength was related to the applied power level. Results of tests carried out in the single mode cavities showed that, for both ores, reductions in ore strength > 50% could be achieved in very short periods (<1 second). Thermal stress analysis showed that the mechanism of microwave induced failure was the development of tangential stresses at the grain boundaries. It was concluded that operation at 915 MHz with high power and short residence times gives feasible scale-up possibilities.

Jan 1, 2003

ALABAMA Alabama City.-Eddy, L. Altoona.-Cain, J. America.-Foreman, J. T. Anniston.-Foster, R. N. Ashland.-Sturdevant, J. C. Bessemer.-Ball, E. M. Calhoun, F. W. Maschmeyer, W. L. McKenzie, W. C., Jr. Birmingham.-Abbott, C. E. Aldrich, T. H. Aldrich, T. H., Jr. Ashton, J. J. Aufderhaar, H. C. Ball, T. L. Biddison, P. M. Blair, C. S. Brown, T. S. Bush, M. W. Clark, G. H. Crawford, G. G. Crockard. F. H.

Jan 1, 1929

By J. R. Thoenen

Up to 1914 almost all of the world&apos;s supply of potash came from Germany and Alsace. With the cessation of shipments from Germany during the World War the importance of a domestic suppler was evident. During the past 15 years the United States has been working toward the establishment of a domestic potash industry which would end foreign dominance in this commodity. The Federal government has taken an active part in this program. As its share in the work, the Bureau of Lines has ascertained the potash resources in certain district&apos;s through core drilling and has engaged in a comprehensive program of research on the extraction of potash from its various minerals. Until the passage of the Winter bill (H. R. 496) by Congress in 1928 the Bureau of Mines had not been able to give any consideration to the western ores, wyomingite (leucite) and alunite. With the massage of this bill, however, the ray was opened for the extension of the potash studies to cover these materials.

Jan 1, 1932

By Ponisseril Somasundaran, H-L. Chen, University of Athens, D. R. Nagaraj, Zhonghua Pan, Jing Wang

Gums are often used as depressants for talceous gangue minerals in the flotation of nickel and platinum bearing ores. However, the mechanisms of gum adsorption on talc are not clearly established. In this work, adsorption of guar gum at the talc-solution interface is investigated using spectroscopic and allied techniques. Guar gum adsorption on talc is not affected significantly by changes in solution conditions such as pH and ionic strength. Electrokinetic studies showed that guar gum decreased the negative zeta potential of talc but did not reverse the charge. Fluorescence spectroscopy studies conducted to investigate the role of hydrophobic bonding using pyrene and dansyl probes showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of guar on talc to the same extent as that for guar/alumina system, in which hydrogen bond plays an important role. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding rather than electrostatic or hydrophobic force.

Jan 1, 2003

By C. Restarick, R. G. Robins, R. M. Taylor, I. Ennis

Lime addition to acid mine drainage waters (AMD), possibly accompanied by aeration, has been the basis for their remediation by precipitation of predominantly metal hydroxides. An efficient novel alternative technique causes precipitation of double M(II)-M(III) hydroxy sulfates which readily precipitate and are easily dewatered. When the Fe(II)/Fe(III) + Al(III) ratio of the AMD is appropriate, the Green Precipitate (GP) Process provides a more effective alternative to normal liming/aeration. The process can be adapted to give a continuous in-line treatment by the choice of suitable computer-controlled reactors designed to improve the liming efficiency, reduce scaling and control the rate of treatment. The processes are described in terms of the chemistry involved.

Jan 1, 2000

By John C. Gathje, Rick Moritz, Wilhelm de Beer, Gary L. Simmons

"Froth flotation has a long history of success for the recovery and concentration of a wide variety of minerals of commercial interest. Both the art and science of flotation have progressed greatly, and as our knowledge has increased so has our ability to improve mineral separations and recoveries.One area of interest in recent years has been the flotation of refractory gold ores to recover the goldbearing sulfides. In many instances, the use of conventional air flotation to concentrate these values has achieved only limited success. However, as a result of intensive research, Newmont Mining has expanded the boundaries of flotation, and it can now be used to successfully treat many gold-bearing sulfide ores as well as platinum and palladium ores. This has been achieved through the use of the patented N2TEC technology, which utilizes nitrogen as an inert gas in the flotation process."

Jan 1, 2003

By David A. Staab

Numerical modeling was used to investigate the feasibility of using two geophysical imaging techniques, cross-borehole ground penetrating radar (XBGPR) tomography and electrical resistivity (ER) tomography, for detecting and characterizing defects in deep-mixed soil columns. XBGPR modeling was accomplished with a three-dimensional numerical forward modeling code and a two-dimensional inversion routine. Spatial variations in apparent dielectric constant (Ka) and attenuation (a) were mapped. Electrical resistivity modeling was accomplished with a three-dimensional numerical forward modeling code and a three-dimensional inversion routine. Spatial changes in electrical resistivity were then mapped. Three different types of defects were simulated, in addition to a defect-free column. The computer simulations suggest that XBGPR tomography and ER tomography might be useful, non-destructive methods for detecting and estimating the extent of defects in deep-mixed soil columns. The results show that small, isolated defects might be difficult to detect, but defects approximately equal to or larger than the sampling interval (for XBGPR) or vertical electrode spacing (for ERT) should be detectable.

Jan 1, 2004

By Edith Lafontaine

Modern underground mines operate fleets of mobile production equipment including drill jumbos, long-hole drills, load-haul-dump machines, trucks and bolters. Their availability has a substantial impact onto production cost and thus onto mine profitability. Through appropriate collection of pertinent data and information, use of adequate performance measures and their analyses, mine operators can identify the most promising and cost effective opportunities to get more from their equipment and to reduce the overall cost. This paper presents results of the study aimed to review and analyse means and measures used to quantify equipment availability and its contributing factors (reliability, maintainability and maintenance support) in several Canadian underground mines. It overviews current reporting procedures, sources, quality and quantity of the data and information collected as well as examines performance measures and their definitions used by the surveyed mines. Problems concerning data acquisition as well as meaningfulness and usefulness of the above mentioned metrics are also discussed. The paper concludes with some suggestions and recommendations concerning several aspects of equipment availability assessment. It is believed that the latter may become a more useful tool for mine operators in their efforts to reduce production cost than it seems to be the case at present.

May 1, 2007

By Juliana Gutiérrez-Paredes

Keywords: Slag, chromium oxide, recovery, stainless steel Experimental and theoretical work was performed to estimate the effect of slag basicity and amount of reducing agents on the reduction of chromium oxide from the slag which interacted with molten steel at 1600°C. The slag system contained CaO, MgO, SiO2, CaF2 and Cr2O3 together with Fe-alloys (Fe-Si and Fe-Si-Mg). The CaF2 and MgO contents in the slags were 10 mass % each; Cr2O3 was 25%. The amount of the ferroalloys ranged from 12.5 to 50 g per 100 g of slag. The (CaO+MgO)/SiO2 ratio was held at 1 and 2. The Cr yield was determined using both Fe-alloys as reducing agents. Some estimations were made to determine the theoretical effect of temperature, slag basicity, (CaO+MgO)/SiO2, and amount of reducing agents in the slag on the chromium recovery. The FACT (Facility for the Analysis of Chemical Thermodynamics) computational package is used to determine the equilibrium between the slag and molten steel.

Jan 1, 2005

By Chris A. Bennett, Glenn S. Dobby, David A. Bulled

Establishing reagent dosing strategies for new ore bodies has traditionally involved a combination of experience and empirical experimentation using standard laboratory tests. The grade and recovery data resulting from these lab tests have historically been used as direct indicators of plant performance despite the obvious differences between the flotation environments. A reagent scheme selected in this way would subsequently be employed to generate the grade and recovery information for the geometallurgical model which in turn was used for metal production and cash flow forecasts. If the reagent scheme was sub-optimal then so too would be the forecasts and the resulting cash flow.

Jan 1, 2003

By Victor Avdokhin, lvan Kovlekov

"Studies of the process of concentration of gold-containing sands and technogenic resources show that the main reason of gold losses is misbalance between size of gold particles and degree of roughness of mineral bed. This results in free circulation of small gold particles in pores with following washing off the particles from the bed by turbulent flows.We elaborated design of magnetic sluice, intended for improving efficiency of recovering fine gold by optimizing magnetic field of a magnetic system on the base of forming catching coat from magnetic mineralsThe magnetic sluice includes trough-shaped body from magnetic-conducting material. On the bottom of the trough, magnets are placed, and opposite poles of the magnets are oriented outwards. Thickness of the bottom is determined to be sufficient for locking magnetic lines of force of the magnets on each other. The magnets of rectangular plate shape are placed on the rough bottom, covering the whole surface or with spare areas; the magnets are placed across the trough with alteration of rows with the same pole orientation."

Jan 1, 2003

By Briony C. Ruse, David V. Boger, Fiona Sofra1

"The sustainability of the mining industry must be addressed through improving tailings management. The use of thickened tailings and pastes stems from a paradigm shift towards designing tailings disposal sites to suit their surrounding environment, rather than manipulating the environment to accommodate the tailings. Thickened tailings and pastes usually exhibit non-Newtonian behaviour, so a thorough understanding of the rheological characteristics of the material is required in order to determine the disposal plant operating conditions.As environmental factors translate into economic issues, minimising waste production using dry disposal methods is gaining popularity. The use of rheological information is of high importance in evaluating the spreading characteristics, the transportation and the dewatering of thickened mineral tailings. The principles outlined may be applied to many industries encompassing a wide range of waste materials. The main obstacle to the widespread implementation of dry disposal methods has been the high initial capital cost of the methods due to the dewatering step, and the high cost of pumping thick suspensions across any great distance. Proper and thorough costing of tailings disposal activities combined with an accounting approach that shows closure and post-closure care costs on a per tonne basis of tailings disposed throughout the life of the tailings facility will show that dry disposal methods are more favourable than they might seem on initial appraisal."

Jan 1, 2003

By O. K. Olawale, G. O. Edaogbogun, B. N. Ben‑Festus, F. Ben, F. R. Amodu

The environmental and health implications of artisanal gold mining activities at mining sites across Nigeria have rekindled research interest. This study aimed to assess the scalability of naturally occurring radioactive materials in gold mining sites in Iperindo, Nigeria. Soil samples were collected from three different mining sites and control locations and analyzed for natural radionuclides, mainly 238U, 232Th, and 40K, using gamma spectrometry having a sodium iodide detector. The average activity concentration values of 61.55 ± 3.71, 72.65 ± 4.45, and 1134.99 ± 38.12 Bqkg− 1 obtained from within the mining sites for 238U, 232Th, and 40K, respectively, were above the world permissible values of 33.0 Bqkg− 1 for 238U, 45.0 Bqkg− 1 for 232Th, and 420.0 Bqkg− 1 for 40K. The average activity concentration values of 15.26 ± 3.19, 21.46 ± 4.27, 381.04 ± 23.36 Bqkg− 1 estimated for 238U, 232Th, and 40K, respectively, for the control location were, however, lower than the global permissible values. The study also evaluated other radiological parameters such as radium equivalent, dose rate, annual effective dose rate, internal and external hazard indices, and alpha and gamma indices. The obtained values were 252.83 Bqkg− 1, 119.98 nGyh− 1, 147.15 mSvy− 1, 0.85 Bqkg− 1, 0.68 Bqkg− 1, 0.31 Bqkg− 1, and 1.89 Bqkg− 1 respectively. Except for radium equivalent, external and internal hazard risks, and alpha index, which were significantly lower than the recommended threshold, all other radiological parameters were higher than the recommended global limits. Moderate data reproducibility and a p-value of 0.000574 further reinforced the robustness and reliability of the results obtained in this study.

Feb 22, 2024

By G. Demi, G. Belardi, N. Shehu, S. Cico

The physico-chemical interaction between minerals such as olivine, chromite and serpentine and the ions most commonly present in solution, like Ca and Mg and flotation reagents such as EDTA and oleic acid was investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit (Albania).

Jan 1, 2003

By J. R. Thoenen

Up to 1914 almost all of the world&apos;s supply of potash came from Germany and Alsace. With the cessation of shipments from Germany during the World War the importance of a domestic supply was evident, During the past 15 years the United States has been working toward the establishment of a domestic potash industry which would end foreign dominance in this commodity. The Federal government has taken an active part in this program. As its share in the work, the Bureau of Mines has ascertained the potash resources in certain districts through core drilling and has engaged in a comprehensive program of research on the extraction of potash from its various minerals. Until the passage of the Winter bill (H. R. 496) by Congress in 1928 the Bureau of Mines had not been able to give any consideration to the western ores, wyomingite (leucite) and alunite. With the Passage of this bill, however, the ray was opened for the extension of the potash studies to cover these materials.

Jan 1, 1932

By A. F. Deng

A general description of the project, mainly the pier foundation design of the ZHU JIANG FANYING is presented in the paper. The major contents include the foundation scheme, the evaluation of bed-rock characteristics, the allowable bearing pressure, the design and construction of pier foundation.

Jan 1, 2010

By Lawrence Adler

MINE hoist ropes have hitherto been selected by successive approximation, a process both tedious and inexact. The proposed expression is a readily solved synthesis of existing data and the following standard equation:&apos; [ W + Wr + (W + Wr) -a 9 (W + W)f + b] n=T [1] For convenience, a glossary of all terms appears on page 564. Since rope weight (W,) and bending load (B) are functions of unit rope weight (Wv), which in turn is a function of rope strength (T), W, and B can be expressed in terms of T. W, as a Function of T: A study of the curve in Fig. 1, unit rope weight vs strength, yields Eq. 2: W. = -f- [2] Therefore Wr = WvL = T. [3] iv B as a Function of T: From Fig. 2, unit rope weight vs diameter, Eq. 4 is obtained: W, = 1.6d2 [4] B is related2 to d and D, and d has been expressed in terms of W, by Eq. 4, so the curve B vs W, (Fig. 3) gives Eq. 5: 177,000 177,000 This may readily be checked from the expression3 for a 6x19 rope, i.e., d3 B = 288,000D Since d2 = 0.625 W, and N = substituting d into the above expression gives Ea. 6: 180,000 180,000 B T, which will be used. [6] Into Eq. 1 substitute Eq. 3 and Eq. 6, noting that f=0.02: W + T 1.02+=T. [7]

Jan 1, 1958

By D. J. Parker

On Thursday, March 18, 1937, the country was shocked by news of a terrific explosion at the New London, Tex., school, which caused the death of 280 pupils avid 14 teachers. The explosion occurred at about 3:05 p.m. in the largest of the 11 school buildings on the campus. Fire 1 shows this building, marked "Main high school building", with respect to other buildings, pipe lines, oil wells, and gas lines or the property.

Jan 1, 1937

In 1973, US Borax & Chemical Corp. began investing three days wages and about $20 in training materials in every new employee before having him report to his first job. The result? Accidents involving new employees in the past two years have dropped by more than half from the 1972 level. What made this success possible was safety training done with programmed instruction materials-which, incidentally, US Borax also uses for vocational training.

Jan 4, 1976

By Richard E. Danell

"Blasting is a principal step in the surface mining process for breaking and, in the case of overburdencasting, moving rocks and minerals. As many surface mines are coming to the end of theiroperational life, blasting can once again play an important role through the earthmoving operationsrequired to rehabilitate the minesite. Since blasting is such an energetic and destructive process, itis difficult initially to envisage its use in rehabilitation. However, blasting has found applications inmany civil engineering projects aimed at rehabilitation, including well digging, channelling and soilcompaction. For surface mine rehabilitation, the main purpose of earthmoving operations is toproduce a stable landfonn that will sustain revegetation. In particular, blasting can be applied toreducing the slope of steep walls left by quarrying and open pit mining through a modified form ofthe overburden casting technique. Blasting can also be applied to breaking up pit floors andbenches to speed and improve revegetation of these areas (subsoiling)."

Jan 1, 1994