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By A. F. Silva, J. M. G. Sotomayor, V. F. N. Torres

Geotechnical monitoring plays an important role in the detection of operational safety issues in the slopes of open pits. Currently, monitoring companies offer several solutions involving robust technologies that boast highly reliable data and the ability to control risky conditions. The monitoring data must be processed and analysed so as to allow the results to be used for several purposes, thereby providing information that can be used to manage operational actions and optimize mining plans or engineering projects. In this work we analysed monitoring data (pore pressure and displacement) and its correlation with the tension and displacement of the mass of an established failure slope calculated using the finite element method. To optimize the back-analysis, a Python language routine was developed using input data (point coordinates, parameter matrix, and critical section) to use software with the rock mass parameters (cohesion, friction angle, Young’s modulus, and Poisson’s ratio). For the back-analysis, the Mohr-Coulomb criterion was applied with the shear strength reduction technique to obtain the strength reduction factor. The results were consistent with both the measured displacements and the maximum deformation contours, revealing the possible failure mechanism, allowing the strength parameters to be calibrated according to the slope failure conditions, and providing information about the contribution of each variable (parameter) to the slope failure in the study area.

Oct 1, 2021

By John Paul Gries

During World War II, when the curtailment of imports led to an unprecedented demand for domestically produced mica, beryl, and other pegmatitic minerals, the Bureau of Mines and the Geological Survey entered upon a program designed to expedite the production of these minerals from the Black Hills area of South Dakota. The program involved mapping, sampling and drilling many pegmatite dikes found in the southern portion of the area and beneficiation tests in the field and in the Bureau of Mines laboratories at Rapid. City, S. Dak., Rolla, Mo., Salt Lake City, Utah, and College Park, Md. This paper describes the mode of occurrence and the sampling and beneficiation tests on one dike, the Helen Beryl pegmatite, which was investigated as part of the general pegmatite study in South Dakota. Investigation of the Helen Beryl Pegmatite by the Bureau began in August 1943 and was terminated in April 1944. During this period the Bureau took a series of bulk samples from pits for beneficiation tests, drove an adit through the center of the dike to obtain feed for a bulk-sampling plant operation, and finally drilled a series of long holes to sample the deposit further. Geologists of the Federal Geological Survey mapped the deposit and the faces of all excavations and logged drill holes from sludge samples recovered from long-hole drilling.

Jan 1, 1949

By Albert Sauveur

IN an important paper on The Critical Ranges of Pure Iron1 presented at the May, 1913, meeting of the Iron and Steel Institute, Professor Carpenter reports and illustrates the results obtained by him in determining the critical points of some very pure electrolytic iron sheet about 0.01 in. thick. The iron strip was rolled into the form of a cylinder 1; in. long and fn in. wide, weighing 42 g., the thermo-couple being inserted in a small hole in the center. The points Ac3 and Ar3 were readily detected, as well as the point Art, but the point Act was absent from every heating curve. The author concluded from this occurrence that the conception of A2 as an independent allotropic change must be abandoned. At the October, 1913, meeting of the American Institute of Mining Engineers, Dr. G. K. Burgess and J. J. Crowe read a paper on The Critical Ranges A2 and A3 of Pure Iron2 in which they described some extremely important experiments conducted by them at the Bureau of Standards, Washington, D. C. They tested Professor Carpenter's electrolytic iron and detected a sharp and well-defined absorption of heat corresponding to the point Act. Professor Carpenter's failure to detect this point is explained by them on the ground that unless the iron be in a single piece entirely surrounding and in contact with the thermo-couple junction, the thermo-couple will integrate the irregular progress of the heat through the sample and the curves will lose their sharpness. In discussing Messrs. Burgess and Crowe's paper, Professor Carpenter accepted this explanation as probably accounting for the absence of Act in his heating curves.

Jan 2, 1914

The standard procedure of fire refining consists of sulphur removal via air injected through tuyeres, arsenic slagging via soda-lime flux and oxygen reduction by air or oxygen deficient air or a steam fuel mixtures. The use of porous plugs to stir with an inert gas has been mainly considered as a surface renewing agent that increases the product quality and shorten the refining cycle. In the present study the effect of the bottom stirring by nitrogen gas injection through porous plugs for the treatment of the crude copper in the range of 400-150 ppm sulphur, 3,000-2,000 ppm arsenic and 14,000-7,000 ppm oxygen content was investigated. The combined effect stirring-reducing, by the use of air or a steam fuel mixtures through tuyeres for oxygen removal, follows a kinetics of first order where the constant, K, can be represented by the following polynomial expression: K = A * R2 + B * R + C Where A, Band C are constants that depend on the nitrogen flow rate and R is the air-fuel ratio or the steam-fuel used in the reducing step. Depending on the optimization of the flow of nitrogen and the air-fuel or steam-fuel mixture and only if just the oxidation, complexing and reducing steps are considered, the process cycle might be shortened by 45%.

Jan 1, 2003

Open pit production planning is a procedure consisting of multiple stages. Although all the planning stages rely on the geostatistical block models, long- to short-term plans each require their appropriate resolutions and levels of details. The main motives behind using different resolutions are the tractability of the models and the practicality of the generated schedules. The current approach in the mining industry is to use nested pits generated by Lerchs-Grossman as the basis for long-term planning and to use manually generated polygons, within those pushbacks, as the units of production control in mid- and short-term planning. However, the nested pits generated by Lerchs-Grossman algorithm and the polygons drawn by mining engineer do not provide control over the value and tonnage of ore and waste inside the planning units and therefore cannot lead to optimum solutions. In this paper, we first present a pushback determination approach which maximizes the profit of the mine with control over the tonnage of ore and waste within each pushback. We then propose a clustering approach with size and shape control that determines aggregates within those pushbacks; and finally, we introduce a mathematical programming model which uses the generated pushbacks and aggregates as the planning basis and generates production schedules that maximize the net present value of the operation and are practical from the operation?s point of view.

Aug 1, 2013

By C. Acuna

The standard procedure of fire refining consists of sulphur removal via air injected through tuyeres, arsenic slagging via soda-lime flux and oxygen reduction by air or oxygen deficient air or a steam fuel mixtures. The use of porous plugs to stir with an inert gas has been mainly considered as a surface renewing agent that increases the product quality and shorten the refining cycle. In the present study the effect of the bottom stirring by nitrogen gas injection through porous plugs for the treatment of the crude copper in the range of 400-150 ppm sulphur, 3,000?2,000 ppm arsenic and 14,000-7,000 ppm oxygen content was investigated. The combined effect stirring-reducing, by the use of air or a steam fuel mixtures through tuyeres for oxygen removal, follows a kinetics of first order where the constant, K, can be represented by the following polynomial expression: K = A .* R2 + B * R + C Where A, Band C are constants that depend on the nitrogen flow rate and R is the air-fuel ratio or the steam-fuel used in the reducing step. Depending on the optimization of the flow of nitrogen and the air-fuel or steam-fuel mixture and only if just the oxidation, complexing and reducing steps are considered, the process cycle might be shortened by 45%.

Jan 1, 2003

By J. W. Furness

THE utilization and collection of waste materials have gone on for centuries, and have become a habit of the human race. The degree to which the salvaging of waste plays a part in a nation's industry depends largely on the availability of raw materials within the political confines of the country itself, or its ability to purchase such material from outside. When purchase is necessary careful economical use of the raw materials results. These economies, as a rule, are represented by lengthening the life of the given article as well as much re-use. For many years the steel industry of Italy and Japan has depended largely on importations of scrap, yet both are important. As long as the expenses incident to the conditioning and marketing of materials manufactured from salvaged waste are less than the cost of virgin material, the salvaged material will be re-fabricated and in many cases will compete with primary materials. One of the most obvious methods for furthering the efficient utilization of our limited mineral resources is the salvaging of mineral wastes. This method, moreover, in¬creases the available supply of a given material. If the price depends on a balance of supply and demand and the recovery from wastes enlarges. the supply, there can be no question but that it influences the sales price of primary.

Jan 1, 1931

By H. Vuthaluru, O. Kavianipour, C. -Z. Li, N. Suresh, D. Sahu

The paper describes a CFD model developed for 76mm Dense Medium Cyclone (DMC) using Ansys Fluent Software to gain insights into the separation of particles according to their size and density. The simulation used in this paper includes the Reynolds stress model to predict the turbulence inside the cyclone body. An Eulerian-Eulerian multiphase CFD model was applied to model a number of physical aspects such as the separation of coal particles and the segregation of magnetite media solids. The experimental results generated in a laboratory scale DMC were used for the validation purpose and the predicted results of CFD have been validated for the flow splits of water, magnetite and coal. The simulation results obtained from the Eulerian-Eulerian multiphase model revealed that the prediction agreed with experimental results, and matched reasonably well in terms of the mass flow rates of water, magnetite and coal. Furthermore, the partition curve of the DMC when mapped for the separation of - 3.0+0.50 mm size also showed to be in agreement with the experimentally obtained curves. The gravity of cut (SG50), also predicted by the Eulerian-Eulerain multiphase CFD model, was found to be in the vicinity of observed experimental value of SG50. Keywords: Dense medium cyclone, Eulerian-Eulerain multi-phase modelling, computational fluid dynamics, cut gravity (SG50)

Jan 1, 2020

By Robert Stefanko

13.1-SUBSIDENCE AND GROUND MOVEMENT ROBERT STEFANKO 13.1.1-SUBSIDENCE AND FAILURE This treatment of subsidence and ground movement will be confined to subsidence control for limiting surface damage by assessing the significant parameters affecting ground movements during mining to optimize mining techniques. The material will be equally applicable to evaporite mining as well as coal but will not deal with block caving or similar systems where failure is deliberately induced and surface protection is not necessary or provided. When an underground opening is established, the original equilibrium is disturbed with resultant stress concentrations. While many factors are involved in opening stability, the span (W) undoubtedly is one of the most important factors in failure. Assuming it is relatively small, the overlying rock strata can bridge across the opening and little if any movement or convergence of top and bottom will occur. However, as the span increases, a point is reached where the stress in the overlying rock strata exceeds some strength value of the rock, and the top breaks. If the opening span is limited to some subcritical value (-We) and/or is at great depth (D), a pseudo-arch will form, achielring stability before rupture occurs to the surface. The boundary of this arch is thought to approximate an ellipse in form with the major axis vertical and equal to four times W, although there has been little field research to substantiate this theory. However, if the width of this opening is increased at this horizon to some critical value (W,) or the same span is created in a shallower seam, the overlying strata ill progressively rupture to the surface and the characteristic subsidence trough is formed (Fig. 13-1) The area of the surface affected is much greater than the area of the seam extracted, depending on the "angle of draw" (a), which is the angle between a vertical line from the edge of the opening and another line extended to a point at which subsidence tails out to zero. This angle has been found to be about 35° in Europe but is rather academic, being a function of instrument precision in detecting subsidence. Since the subsidence effect is so small at any point beyond n 25° angle, this latter may be considered the practical limit of subsidence. Further- more, indications are that the angle of draw varies with depth and nature of the strata.' In a field study over a 1,000-ft-deep potash mine in New Mexico, the maximum angle of draw was found to be 51.5°.2 So far, only a single opening has been considered. However, the width of the excavation applies to any complex mining system of entries, rooms and longwalls as long as the seam has been fully extracted and the width represents the distance from one solid rib to another. It will be noted that the amount of vertical displacement varies from point to point on the surface (s), but the maximum subsidence for a given trough occurs at the center (S). This latter value may not he equal to the maximum possible subsidence (Sm) which occurs only if a critical or super- critical (+W,) width has been exceeded (Fig. 13-1). Substantial surface damage can result when subsidence occurs. Factors affecting the amount and type of ground movement are: thickness and properties of the seam, angle of draw, width of excavation, depth and type of overburden, inclinations of strata and surface, and the amount of support left in the gob. In Europe,

Jan 1, 1973

By Ragnhild Aune

In fire refining of copper, the affinities of various impurity elements on dissolved oxygen is of great significance. Further, in the design of oxygen probes in liquid copper, the influence of solute interactions on the activity of oxygen need to be considered in order to evaluate the oxygen concentration in molten copper. The present paper presents a series of measurements of the activities of oxygen in liquid Cu-M-o alloys (where M stands for Mn, Zn, As, Se or Te) carried out by the present group employing the solid electrolyte galvanic cell technique. Extreme care was taken to control the oxygen potentials in the inert gas atmosphere, and to keep the oxygen levels very low in the molten metal. The oxygen content was determined by analysis of the samples taken out from the melt. The results obtained showed that Mn has a strong negative influence on the activity coefficient of oxygen in liquid copper. A similar, but less prominent effect was observed in the case of Zn. Arsenic had no influence on the activity of oxygen in Cu (liq.). Se and Te had slight negative effect on oxygen activities in copper at XO > 10-5, while at lower oxygen levels the interaction coefficients were found to be positive. The results obtained were compared with empirical models for the calculation of interaction coefficients available in literature.

Jan 1, 2003

By J Li

Cannington Mine has been developing through paste backfilled stopes since the year 2000. These paste drives have been used as either production drill accesses or long-term bypasses. Prior to this study, the ground support requirements for each paste development cut were: an initial 50 mm layer of fibrecrete, weld mesh bolted with 2.4 m split sets, followed by a second coat of 50 mm fibrecrete. Both layers of fibrecrete and the layer of mesh were to be installed before the next cut could be bored and fired. This support regime proved successful at Cannington, however, the total cycle time for each cut was lengthy due to the installation and curing times associated with each layer of surface support. In an effort to reduce the cycle time a study was carried out, with the aid of RocScience’s Phase2 numerical modelling software. The modelling reviewed all of the parameters controlling the stability of a newly excavated development cut. The parameters studied included the early strength of fibrecrete, the ground support load capacity, and the strength of the paste fill masses which varies depending on the cement content. As a result of the study, the ground support standard was revised. The revision has significantly decreased the cycle time as well as fibrecrete consumption, all the while maintaining the safety of personnel and equipment.

Mar 21, 2011

By H. H. Wang

Construction safety documents regulate significant safety actions and requirements by which construction workers or employees should abide in order to secure them from occupational hazard events. Therefore, facilitating faster identification of applicable safety requirements from the documents has become an important topic in the construction safety domain. To address the need in this regard, tools and techniques have been developed and research efforts have been made. One of the research efforts is to utilize ontology, a knowledge representation and reasoning approach, as the methodology to achieve the goal of identifying applicable safety requirements. In such ontology-based researches, the development and construction of the safety concept ontology is an essential task as the concepts and the relationships between the concepts both representing key safety knowledge need to be carefully identified. In this paper, the author focuses on the safety documents without predefined concept structure and aims to address the concept and relationship identification difficulties. Specifically, the author leverages the Formal Concept Analysis (FCA) methodology, a theory of data analysis that identifies conceptual structures among data sets, to mine and analyze the documents in order to discover safety concept structure and to further assist the development of the concept ontology for the construction safety documents. The author expects the application of FCA to construction safety domain can eventually benefit the ontology-based approaches for identification of applicable safety requirements.

Aug 1, 2013

By R Atmuri, W Liang, R Prasad, Y Liu, E Wingate

Yellow phosphorus (YP) has been commercially produced since the 1920s. First in the USA by the Tennessee Valley Authority (TVA), next in Russian (Kazakhstan) in the 1950s, and finally in China in the late 1970s and early 1980s. There are operations in Vietnam and Sarawak on a smaller scale. YP has become very in vogue due to its use in the production of lithium iron phosphate battery cathode precursor materials by the Chinese and other western battery manufacturers. The YP is also used to produce purified phosphoric acid and higher grades of acid using a thermal oxidation process after smelting. This paper will look at the basics of the smelting including slag chemistry, alloy chemistry and offgas chemistry. The paper will look at the design of the furnaces used in the YP production process as well as the downstream recovery of phosphorus from the smelter off-gas stream to YP. The next part of the discussion will focus on the operations of a YP smelter with regards to control of the furnace to optimise phosphorus recovery to YP. Will discuss tapping cycles for alloy and slag with a view to optimal phosphorus recovery. The discussion will close out with a review of operational challenges in the smelter and a brief description of the downstream conversion of YP to high purity phosphoric acid.

Aug 21, 2024

By Neil S. Fishman

Tabular uranium ore in the Grants uranium region, New Mexico, occurs as tabular layers of a urano-organic mixture suspended within host sandstones of the Morrison Formation. The intimate urano-organic association points to the organic material as the main ore control. Petrographic evidence indicates that the organic material was postdepositionally introduced into the host sandstone, probably as humic acids; however, the mechanism by which these acids precipitated from solution remains uncertain. A model, the cation scavenging model, is proposed in this paper to explain humic acid precipitation. The model, supported by evidence from regional alteration studies of the host sandstones, proposes that cations responsible for humic acid precipitation were scavenged from framework grains which altered during passage of the humic-rich fluids through the host sandstone. This process, coupled with the affinity of organic molecules for each other, caused flocculation of humic acids into tabular zones. The precipitated humic substances then continued to concentrate uranium to form the orebodies. The cation scavenging model requires only one solution, the humic-bearing solution, in the precipitation process. All cations necessary for humic acid precipitation originated in the host sandstones. This model contrasts with a previously proposed model--the brine interface or two solution hypothesis--in which it was proposed that a cation-rich brine introduced into the host sandstones provided the cations necessary for humic acid precipitation. The brine hypothesis has several drawbacks, one of which is unrealistic hydrologic reconstructions necessary to accommodate mineralization at various stratigraphic horizons in the Morrison Formation. Moreover, no mineralogic evidence exists to suggest a brine occupied the host sandstones at the time of mineralization. The proposed cation scavenging model for humic acid precipitation not only readily accounts for humic acid precipitation, but also is consistent with geologic observations and regional alteration studies.

Jan 1, 2013

By Cyril Stanley Smith

ARCHEOLOGISTS, by use of the terms Bronze Age and Iron Age, indicate that metals have in the past determined the character of civilization. The relatively simple discovery by a primitive metallurgist that the addition of tin to copper both facilitated the production of castings and increased the durability of the product enabled hunter, warrior, and housewife alike to do things never dreamed of before. Similarly, the smelting of iron and the discovery of hardening methods greatly changed the arts of peace and war. Discoveries of low-melting-point alloys for joining and for making household utensils, and perhaps the adornment of a feminine form by sparkling precious-metal jewelry, have at times changed the destiny of a country. Bronze cannon, the cast and wrought iron Watt engine, copper transmission lines, and aluminum alloy aircraft, are cases of particular metals making possible the realization of an improved engineering design. Perhaps of the greatest influence of all upon civilization was the development of type metal. The rapid increase in the rate of dissemination of knowledge dates from the day that the technique of the pewterer was utilized in making rapidly reproducible and accurately sized letters for printing. It was not movable type, but metal type that was important, for metal castings could be made of identically the same shape and size at an enormous rate, and possessed excellent inking and wearing characteristics.

Jan 1, 1946

By Teemu Väyrynen, Matti Vilkko, Antti Jaatinen, Pekka Itävuo

"This paper shows that smooth and accurate feed-hopper level control is essential for consistent cone crusher operation. The objective of the paper is to define the best practices for tight control of cone crusher feed-hopper level. The paper discusses the challenges involved in a delay-dominant level control problem (specifically, dead-time-induced performance and stability issues, mass flow disturbances, process and actuator non-linearity) and proposes five corresponding control structures. The performance of the proposed control structure candidates is evaluated in a simulation study and, finally, a full-scale experiment is conducted for the best-performing candidate. The results of this study emphasize the importance of control structure selection. While the most obvious control structures failed to deliver the desired performance, the best result was achieved by using control structures that eliminate the conveyor transport delay (dead-time) from the control loop. In practice, the control loop dead-time can be eliminated by either using an actuator (variable-speed feed conveyor) that is connected directly to the feed-hopper, or by redefining the process boundaries closer to the used actuator (regulate the circuit mass balance instead of feed-hopper level). The presented control structures provide means to achieve a consistent cone crusher performance and size reduction. This facilitates efforts to improve the plant’s performance and increases the plant’s overall stability."

Jan 1, 2014

By Heidi Fauser

The aim of the project was the development of an electroforming process for the production of medical implants out of gold. To prove the applicability of this technology, tympanostomy tubes were chosen as demonstrators. These barbell-shaped tubes are usually produced mechanically; of silicone or, for higher therapeutic demands, of metal ? gilded silver or gilded stainless steel. Gold electroforming of the tubes as an alternative manufacturing process would reduce the expenditures for the mechanical preparation and lower the corrosion susceptibility significantly. To obtain electroformed gold tubes of the desired shape, the following steps are necessary: fabrication of a negative template by drilling holes with countersinks in an insulated aluminium sheet, electroforming process, removal of the aluminium by using a sodiumhydroxide solution. For the optimisation of the shape and surface quality of the tubes respectively the simplification of the manufacturing process, various parameters were tested, e.g. aluminium quality and sheet thickness, type of insulation layer, substrate processing, hydrodynamic conditions, type of electroforming electrolyte, electrodes position, etc. The manufactured tubes were characterised in view of thickness distribution, hardness, surface roughness and purity in comparison to mechanically produced reference tubes. From the results obtained during the project it can be concluded that electroforming processes can be easily adopted for the manufacture of medical implants. The time-consuming electroforming process is by far compensated by the simultaneous production of an arbitrary number of implants.

Oct 1, 2003

By Jeffrey Shawn Peterson

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response, the National Institute for Occupational Safety and Health (NIOSH) conducts research to reduce the noise emission of various underground coal mining equipment, an example of which is a roof bolting machine (RBM). After the removal of coal or rock, the remaining strata may be subject to fall, either from overhead (the roof) or from the side (the rib). One method used in underground coal-mines to prevent failures requires the installation of roof bolts. The roof bolting machine operator trams the machine to the required location, drills a hole into the strata, and then installs a roof bolt, supporting the roof or the rib, as the case may be. Field studies support the premise that, on average, drilling noise is the loudest noise that a roof bolting machine operator would be exposed to and contributes significantly to the operators? noise exposure. NIOSH has determined that the drill steel radiates a significant amount of noise during drilling. NIOSH is developing bit and chuck isolators to reduce vibration, and thus noise radiation of the drill steel, with the longer-term goal of reducing roof bolting machine operator noise exposure. Laboratory testing has shown that operator ear sound pressure levels may be reduced by 3 to 7 dB(A), depending upon the test configuration and drilling media.

Jan 1, 2009

By William L. Crentz

Floyd County, KY., contains sizable deposits of high volatile bituminous coal. Some of the coals have been blended with higher-rank coals and used in the manufacture of high-quality metallurgical coke. The Upper Elkhorn No. 3, Upper Elkhorn No. 2, and Upper Elkhorn No. 1 beds produce the bulk of the present output in the county and contain the main known reserves of coal. Little information is available concerning the quality and extent of the deposits underlying the Upper Elkhorn No. 1 bed, although small operations in the past have worked a bed that is reported to be; the Lower Elkhorn. Undoubtedly, these lower beds occur in Floyd County, but depth Will preclude their development into a major source of fuel as long as large deposits of more-accessible coal are available. More is known of the occurrence of the beds above the Upper Elkhorn No. 3 owing to sporadic mining ventures in the upper measures. Many of the coal samples from beds above the Upper Elkhown No. 3. were collected in mines that had been abandoned. Almost all of the present production of Floyd County coal is taken from the Upper Elkhorn beds, and it is unlikely that their dominant position as coal producers will be challenged in the near future. Table 1 shows the coal production of the county by beds, during 1950.

Jan 1, 1952

By George S. Rice

THE year 1929 has shown a surprising growth in the attention given by mining men to the subject of ground movement and subsidence from mining, as evidenced by the large number of articles that have appeared in technical journals, also papers and discussions in mining societies in the leading mining countries of the world. These have not been confined to consideration of the narrower limits of the subject but in application have extended to many of the fundamental questions involved in mining. The papers and discussions have been concerned with .ground movements resulting from mining of a great variety of minerals, metallic and lion-metallic. Examples of the former are: the mining of gold ore at Johannesburg, South Africa, and in the Kolar field, India; mining copper ores in Arizona and Utah; and lead and zinc in the Joplin region. Examples of ground movement resulting from mining non-metallic minerals are found in: the mining of. coal in many countries; potash mining in Germany; the mining of- common salt in several parts of the' United States; and the mining of sulfur in Texas and Louisiana; and examples of subsidence in the non-metallics are found exceptionally in the extraction of petroleum by wells, as in the Goose Creek field, on the Gulf Coast,' and recently in the Sour Lake field' of Texas

Jan 1, 1930