Search Documents

By Si Qin

Unknown goafs and roadways of abandoned coalmines can be a great water inrush hazard for coalmine workers. Consequently, advance detection of such hazards is of great importance. By detonating seismic charges in underground coal seams, we can collect seismic data using a surface survey line, which is located across the ground projection of the underground shot point. This experiment was conducted in a coalmine in Shaanxi Province, China. After surface elevation compensation and travel time adjustments, we accurately determined the position of the goaf boundary along the survey line based on the wave velocity anomaly on the seismic record. Then we used a scattered wave imaging technique to enhance the energy of the scattered waves that are generated when the coal seam roof slide wave (refracted wave when the incident angle bigger than the critical angle) hits the roadway, thus confirming location of a geological discontinuity (roadway). This experiment shows that the coalmine ground seismic method, employing an underground explosive charge and a surface seismic array, has the ability to detect an abandoned roadway and goaf in advance of coal mining, thus can improve worker safety.

Aug 1, 2013

By Y. Duna

The reliability of mine ventilation systems is critical to normal and safe production in a mine and includes reliability of the following parts: ventilation system branch (or passage), ventilation structures, ventilation network, and the fan. Among these, the reliability of a ventilation branch may be considered the foundation of the whole ventilation system. The branch ventilation flow includes four parameters: air volume; toxic and hazardous gas concentrations; temperature, and dust concentration. The calculation model for the reliability of a branch was established based on the analysis of normal distribution of flows in any one branch. Then, the efficiency of the ventilation structures and fire risk compromising the reliability of branch was studied. The results obtained were as follows: if the air volume, toxic and hazardous gas concentrations, temperature and coal dust concentrations of the branch are within reasonable limits, set at any stable state and at the same time, then this branch is reliable.

Aug 1, 2013

By M. E. Holter

"Three main potash members are recognized within the Prairie Evaporite Formation of Saskatchewan and have been designated, in ascending order, the Esterhazy, Belle Plaine and Patience Lake members. Each is composed of sylvinite near the geographic center of the member and becomes increasingly carnallitic marginally. Each stratigraphically higher member has a narrower carnallitic margin. The sharp contact between carnallitic and non-carnallitic components of the formation describes a surface which may be traced regionally and is not related to bed-ding. The contact rises higher in the stratigraphic section toward margins of members. Within each of the three members, analyses indicate that carnallite becomes more abundant toward the north whereas sylvite and insolubles, increase toward the south. Within each member, areas rich in carnallite are coincident with areas in which the member as a whole is thicker than averag,e. The Belle Plaine Member contains the highest concentrations of carnallite, the Esterhazy the lowest. A maximum content of about 30 per cent sylvite is common to all three members. Insoluble contents increase in successively higher members.Map studies are combined to outline the economic potential of the potash beds in terms of depth to the top of the Prairie Evaporite, ""salt-back"" thicknesses and sylvite grades for each member."

Jan 1, 1971

By E. Barsky

"Theoretical notions of mass transfer processes in cascade separation of bulk materials have not been adequately developed as yet (Barsky M.D. 1980). In this paper we have derived linear difference equation of the second order for a cascade with initial feeding top any stage proceeding from mass exchange regularities. The solution of these equations has allowed us to determine quantitative dependences of the material distribution over the cascade stages, which serve the basis of the method of predictive estimate of the process results. We have also examined the model of the material distribution coefficient formation at individual cascade stages.We have checked the adequacy of this model to experimental data. It is noteworthy that the obtained theoretical results are phenomenological, i.e. they can be applied to the processes of separation of different physical nature, e.g. of isotopes, liquid media, gases, etc.INTRODUCTIONRecently, the processes of cascade separation of bulk materials have found broad application in various industries. They ensure a high separation efficiency and high-quality composition of final products. Although specialized literature gives serious attention to cascade processes [1], their theory is not sufficiently developed yet. To achieve optimal organization of this process, we examine mass transfer in a cascade gravitational classifier with stages of identical design."

Jan 1, 2016

By Lloyd W. Trevoy

Syncrude Canada Limited is presently studying commercial production of heavy minerals from plant tailings of the openpit A lhabasca tar sands operation. When tar sands are processed and upgraded to synthetic crude oil, heavy minerals can be removed f rom the extraction circuit and beneficiated to provide concentrates of zircon and titanium minerals. Calculated recovery rates indicate that crude oil production capabilities of 105,000 barrels per day would provide 26,000 tonnes of zircon and 114,000 tonnes of titanium minerals annually. The titanium minerals concentrate is a mixture of ilmenite, leucoxene and rutile; it could be used as recovered or upgraded to synthetic rutile. With the consrruction of further synthetic crude oil plants in Western Canada, a large reserve of heavy minerals will become available.

Jan 1, 1984

By A. A. Brant

BECAUSE of its simplicity, the dip needle is widely used for locating magnetic rock formations in drift-covered areas. Although it responds only to strong magnetic disturbances, it has the advantage that surveys with it can be carried out rapidly, at relatively low cost, by untrained operators. More accurate surveys can be made with a much more sensitive instrument known as the magnetometer, but this must be operated by a specialist and the resulting survey costs are much higher. Mining men use the dip needle for the location of magnetic ores or mineral deposits associated with magnetic rocks. In certain districts, a survey with the dip needle may aid in solving geological structure. In the Little Long Lac and Crow River gold camps of Ontario, it has recently been used for these purposes. In interpreting the results of a dip needle survey, an understanding of the chief magnetic and mechanical factors determining the dip recorded by the needle is definitely necessary. For example, many observers locate a magnetic body by the highest dip values, apparently unaware that these frequently may not lie directly above the body. It should also be realized that a careful dip needle survey may yield information regarding the dip, breadth, and perhaps depth, of the magnetic body. Moreover, the observer should know when numerous closely-spaced dip readings are necessary, and when the dip may be measured at more widely separated intervals. The purpose of the following article is primarily to describe the factors affecting the registration of the dip needle, with a view to aiding investigators in a more accurate and complete interpretation of their results. To explain the cause of magnetic disturbances (anomalies) and the action of the dip needle, a knowledge of certain fundamental magnetic terms is necessary.

Jan 1, 1938

By Richard K. Komarek, Antonios Zavaliangos, Roman T. Dec

Current industrial compacting and briquetting practices are largely based on trial-and¬error techniques. This paper introduces a two dimensional finite element model of compacting/briquetting process in the roller press. Compared with other modeling techniques used in the past, finite element method offers the most versatile approach because it incorporates adequate information about powder behavior, geometry and frictional conditions and offers predictions for the density distribution, velocity field, stress distribution, roll force, roll torque and other important process variables. More over, when the model includes elasticity, it offers predictions on the internal stress state in the briquet after its exit from the pressing zone. This enables to perform realistic computer experiments which are helpful for establishing the pressing system design, forming cavity geometry and process conditions necessary to produce compacted or briquetted product with the desired properties.

Jan 1, 2004

By A. K. Verma

This paper provides a brief overview of evolution of deformations, stresses, and pore pressures due to different excavation stages during construction of an URL. Excavation of a rockmass develops a damage zone of finite width around the excavated zone which is associated with changes in permeability and which affects the fluid flow mechanism. In this study, a coupled hydromechanical (HM) analysis has been conducted for a water saturated porous rock mass which has been created by sequential excavation and backfill of vertical disposal pit of an URL. For this purpose, an Atomic Energy of Canada Limited?s in-floor concept for a deep geologic repository suitable for Indian conditions has been used. Changes in rock deformations, stresses, strains and mechanically induced pore pressure in an undrained condition, during excavation, as well as those caused by mechanically induced rock deformations after backfill of the disposal pit, have been modeled. A three-dimensional finite difference tool FLAC3D has been used for the analysis.

Jun 1, 2012

By J. Ellis Thomson

For many years the value of qualitative microscopic investigation has been recognized in both of the fields of pure and applied science. In particular, its aid has been invoked in the determination of rock specimens in thin section, and some at least of the interrelations of minerals present in any one section have been observed and, to a limited extent, applied for the solution of different problems. During the past decade this form of research has also been diverted to the determination of ore minerals in polished section, with some observation of their structural relations. Microscopic research of a quantitative character, on the other hand, while started nearly one hundred years ago, has found but a limited application in petrography and has scarcely been used at all in the more modern science of mineragraphy. This is very largely due to the methods employed, since most of them consumed too much time and were, in addition, too laborious to encourage many workers in their use. The details of procedure for these earlier methods will be found in another paper by the writer, and will be omitted from this discussion as being of small interest to practical mining men.

Jan 1, 1930

By G. Frithum

In the present paper a new and highly economic route for Fe-separation from HCl leaching processes in hydrometallurgical applications is described. In most ore leaching processes, Fe is involved and needs to be separated; HCl has become an interesting leaching agent, because it can be recycled. Usually a mix of Fe2+ and Fe3+ is obtained which can be hydrolyzed directly (in case only Fe3+) or roasted via pyrohydrolysis (in case of Fe2+) to ferric oxide. Economic oxidation of Fe2+ to Fe3+ is described, and potential technologies for regeneration of HCl with separation of Fe are shown and compared.

Jan 1, 2014

By Yin Wang, Lin Li, Zhongwei Bi, Like Wei, Wen Li, Shaogang Li, Bin Zhang, Hongjie Li

Presently,Many long-wall fully-mechanized faces in shallow depth coal seams are below room and pillar goaf in Shendong mining area. When the working face is advanced out of concentrated coal pillar in upper room and pillar goaf, strong strata behaviors often cause support crushing accident. Aiming at a support crushing accident which happened in Shigetai coal mine of Shenhua group in Shendong mining area, this paper analyses the stress transfer process while mining out of concentrated coal pillar by numerical simulation software FLAC3D. According to the feature, simplifying the roof of upper room and pillar goaf as supporting-beam structure explains mechanism of large area collapse in room and pillar goaf roof. Based on the feature of supporting-beam structure, deep-hole blasting concentrated coal pillar technology is proposed to control the strong strata behaviors in Shigetai coal mine. The blasting control effect is confirmed through characteristics of strata behaviors, growth circumstance of ground crack and multi-point extensometer monitoring results. By using control technology, Shigetai coal mine has been successfully avoided support crushing accident.

Jan 1, 2015

By J. Someehneshin

Nowadays along with population growth, industry development, consumption of mineral resources and the fact that the reserves on hand are running out, the depth of surface and underground mines for further exploitation are increasing. During recent years, in underground mining, the block caving method for low-grade and large-scale deposits has shown a growing rate of application. This method is very cost effective and economically affordable. The dimensions of blocks are one of the most important parameters which should be taken into account since it has been proved to have a great deal of effect on technical issues such as commencement of caving and mine design. Proper calculation of the length and width for a block in this method leads to proper caving and discharging which are the most important stages. Therefore, in this method, the calculation of the optimized dimensions (length and width) of blocks is not only important but also directly helps the productivity of extraction. In this study, firstly for the purpose of facilitation, some assumptions were considered and having used these assumptions for estimation of optimized length and width of block, a relationship based on rock mechanics and physics was explored. Furthermore, some necessary details were added to the said relationship and finally, it was transformed into an inequality. Solving this inequality provides us with the optimized length and width of the block. The explored relationship was analyzed with MATLAB software and the graphs thereof were drawn. In these graphs, each time one of the input parameters has been drawn up in a logical range so that it could be compared with previous states.

Aug 1, 2013

By S. N. Aliferova, E. I. Afonina, S. N. Titkov, A. Ju. Bondareva, N. N. Panteleeva

"Potash ore is mainly processed using the method of cationic flotation. Potash ore deposits of the CIS, namely: at Upper Kama river, Gremyachinsk (Russia), Starobin (Belarus), Tubegatan (Uzbekistan) are characterized by relatively low KCl impregnation (1.0 – 1.5 mm) and contain up to 10% of waterinsoluble impurities (WII). Water-insoluble impurities are presented by aluminosilicate, silicate, carbonate (calcite, dolomite) minerals and anhydrite. In the process of milling the ore to a flotation size there are released and dispersed the insolubles impurities actively sorbing the cationic collector, i.e. aliphatic amines C16 – C22. In this regard there is carried out a preliminary desliming of the ore.Currently grinding the ore to a flotation size (1.5 mm or less) is carried out in rod mills along with forming of a large number of fine-grained ore fractions having the size under 0.25 mm, which results in the increased KCl losses with halite slime waste and reduction in the quality of finished product. There has been developed the technique for processing of potash ores with a high content of water-insoluble impurities (10 – 12%) containing, in different ratios, silicates, carbonates and anhydrite. The technology involves the use of the ore dry grinding to the flotation size and subsequent reagent activation of the processes for sludge removal and sylvite flotation.INTRODUCTIONCurrently there are being developed the potash ore deposits in the CIS countries, namely: at Upper Kama river and Gremyachinsk deposits (Russian Federation), Starobin deposit (Republic of Belarus) and Tubegatan deposit (Uzbekistan). Potash ores are a mixture of sylvite and halite and contain water-insoluble impurities of silicates, carbonates and anhydrite. The content of water-insoluble impurities (WII) reaches up to 10%, disseminated (impregnated) sylvite does not exceed 1.5 mm and in connection with that the ore is crushed to a particle size under 1.5 mm. Ore grinding is performed by wet process in rod mills with producing a significant amount of fine-grained mineral fractions and sludge, which are actively sorbing a cationic collector, i. e. primary aliphatic amines C16 - C22. The ground ore is deslimed and the slime product is directed to a sludge depot (pits)."

Jan 1, 2016

By A. A. Ruitenberg, G. Ruitenberg, J. Chandra

"The Caledonian Belt is mainly underlain by Late Precambrian and possibly Early Palaeozoic rocks, which are in part overlain by younger strata. Most of these rocks are weakly deformed, except for those in some linear . zones, which have been intensely deformed by cataclasis. Mineral deposits related to two distinct metallization episodes have been recognized. The earliest are zinccopper- lead sulphide deposits, which have been concentrated in the axial regions of late-stage cross-folds within the main cataclastic zone. The host rocks are andesitic and dacitic tuffs which show effects of intense talcose alteration, silicification and chloritization. Deposits related to the second episode are mainly composed of copper sulphides with locally abundant tennantite and tetrahedrite, which occur in brecciated and fractured carbonate-quartz veins. These veins postdate the late-stage cross-folds. VLF-EM and high-sensitivity magnetics proved to be very effective in delineating the geology of these deposits."

Jan 1, 1972

By Albert G. Zima

THE conservation of strategic materials during war rime gives rise to many problems not commonly encountered in times of peace. During normal times, when world trade is unrestricted, we are apt to become lavish to a point of extravagance in our use of those materials which, during rime of war, become scarce owing to inadequate transportation and production facilities or because the enemy may be in position to control sources of supply. It becomes necessary, then, to enforce rationing of available sup-plies, and in some cases, where such supplies are wholly inadequate, we find we must resort to the use of substitute materials. We are now confronted with such a problem to an extent never before experienced, with the result that many of the commodities upon which our civilization depended are now either shut off completely or, because of the heavy demand occasioned by war production, are not available in sufficient quantities to meet requirements predicated on peace-time standards and manufacturing methods. It has become necessary, therefore, to make many changes, some of them very drastic indeed, to enable us to carry on our war effort effectively. This? discussion will deal briefly with one phase of this problem, namely, the conservation of alloys required in the making of steels necessary for war production. In line with a request from the War Production Board, the Technical Committee on Alloy Steels of the American Iron and Steel Institute made a study of experimental steels embodying the !east amount of alloying constituents, with the objective in mind of substituting these steels wherever possible for the standard alloy steels used heretofore. This study embraced the following phases: (1) The availability of silicon and manganese; (2) The average quantity of alloying elements recoverable from scrap; (3) The effect of increases in manganese and silicon contents on the general properties of steel; ( 4) The elements and ranges of elements which might be used to duplicate the hardenability of the steels now in use; (5) The effect of combining several elements in small quantities upon the properties of steel at various hardness and strength levels; (6) A determination as to whether or not the steels selected would suffice for general application. Working on this basis, the Committee arranged for the manufacture of several heats of steels containing various combinations of different amounts of such elements as silicon, manganese, chromium, nickel, and molybdenum. The steels thus produced were compared by hardenability tests.

Jan 1, 1943

By D. G. Sediako

Chemical composition and the casting/rolling production routes determine the cost and properties of the wrought material. For example, the coarse-grained structure frequently associated with DC casting requires complex rolling schedules to refine the grain size. Hot forming (rolling/forging/extrusion) results in a strong crystallographic texture, which is responsible for the tension-compression strength asymmetry frequently exhibited by magnesium alloys. Understanding the influence of alloy composition on texture evolution during forming provides useful practical information to optimize industrial hot-forming technologies for magnesium alloys. In this study, a series of Mg-based alloys containing varying combinations of Al, Rare Earths, Zn, Ca, and Sr were subjected to identical casting and extrusion processes in order to isolate the effects of alloy composition on texture evolution. Textures were measured by neutron diffraction at the NRC Canadian Neutron Beam Centre. The ability of neutrons to penetrate deeply into materials allowed information to be retrieved from all regions of the bulk specimens without destructive and time-consuming sectioning operations, thereby providing true bulk texture data. {1010} , (0002), {1011}, and {1012} pole figures were generated for all of the as-processed alloys, from which Orientation Density Functions were obtained. The were then used to reconstruct the pole figures and to extract semi-quantitative texture data showing how the (0002) and {1010} planes align themselves with respect to the extrusion axis. It was found that varying the concentration of aluminum (3-4 wt%) and Rare Earths (2-3 wt%) in AE alloys had a weak effect on texture development. All of the alloys showed similar magnesium extrusion textures, in which the (0002) poles align themselves preferentially with the extrusion axis. The substitution of Sr for Rare Earths also did not have a significant impact on texture development. On the other hand, while the presence of small amounts of Zn and Rare Earths did not have a strong effect on texture development, alloys with higher concentrations of these alloying additions (in combination) showed an enhanced tendency for the {1010} poles to align themselves with the extrusion axis. The addition of Ca also enhanced the alignment of the {1010} poles with the extrusion axis. These textures can complicate further processing and introduce a significant anisotropy that could influence creep properties.

Jan 1, 2007

By Nader Golchinfar

The V-shaped breakout zones around excavation boundary have been captured by a variety of numerical methods such as FEM and DEM methods and failure criteria such as linear Mohr-Coulomb and non-linear Hoek-Brown failure criteria. Diederichs (2007) used Hoek-Brown parameters in his spalling parameter approach; however, it is convenient to use the Mohr-Coulomb failure criterion in numerical modeling because the material parameters can easily be determined from triaxial tests. It is shown in this study that when peak and residual strength parameters as well as dilation angle are properly defined, the brittle Mohr-Coulomb failure criterion can be used to model depth of failure near underground excavations satisfactorily.

Jun 1, 2012

By A. J. Russell

"This paper investigates why it is critical for a mine to accurately determine thermal rock properties and virgin rock temperatures. Theoretical simulations of deep mining production zones have demonstrated that thermal conductivity (k), virgin rock temperatures and specific heat (cp) significantly impact rock heat predictions which can be the dominant component of a mine’s heat load. Natural variability in these factors showed that realistic errors can have a significant effect on mine heat loads. This can ultimately affect miner safety and introduces risk to the viability and sustainability of a project. INTRODUCTION Accurate heat load determinations are critical to ensure that underground working conditions are maintained within legislated and mine specific parameters to safeguard the safety and productivity of employees. Underpredicting mine heat loads will result in hot underground conditions, which risk the health and safety of employees, reduce the productivity of employees or stop production if legislated temperatures in working areas are exceeded. Overestimating mine heat loads will result in increased capital and operating costs reducing the viability of the project. Over- or under- predicting the heat load for a project will increase the project risk. Heat sources in a mine can broadly be broken into two categories. These two categories are defined by Hemp and Rawlins (2014) as natural and artificial heat sources. Those sources which depend on the size, location and depth of the mining areas are defined as natural heat sources, whereas those heat sources which are a result of the actual mining activities are defined as artificial heat sources. Autocompression, or the conversion of potential energy, to enthalpy is an important consideration when determining the air temperature in the mine and its interaction with natural and artificial heat sources. It is documented by Jones (1985) and Hemp and Rawlins (2014), that the heat flow from rock in deep mines can dominate other heat sources; information from BBE’s archives show that this is between 40% and 60% of the total heat load. They also point out the importance of accurately measuring both the thermal rock properties and virgin rock temperatures (VRTs) for determining and planning the ventilation and refrigeration requirements for a mine. Both of these texts cite multiple methods for calculating the heat-flux and ultimately the heat load for the different working areas in a mine. All of these methods demonstrate that the heat flux and heat load will increase proportionally with increased thermal conductivity (k), specific heat (cp) of the rock or mineral, and VRT depending the area of the mine or mining method."

Jan 1, 2019

By Jun Dai

Based upon research findings from several countries, the combination of microwave and mechanical means to break hard rock holds promise for the future. To achieve this goal, it is essential to understand the laws governing strength reduction of hard rock, such as granite, induced by microwave irradiation. Two aspects to consider are: 1) laws associated with the tensile strength of hard rock after microwave irradiation and 2) the sensitivity of different types of rock strengths to microwave energy. In this study, granite with a range of tensile strengths was exposed to microwaves for various time periods to compare the response of rocks with different strength values exposed to the same microwave irradiation. In addition, a method based on hotspots is presented to explain the mechanism by which granite strength is reduced by microwave irradiation. Granite extracted from Qinling Mountain in Shaanxi Province, China is used in the research. ?50 × 50 mm cylindrical granite specimens were exposed to microwaves at a specific power level. The strength values of the heated granite specimens were compared with those of unheated specimens. Through the comparison and analyses, relationships were determined between 1) reduction in granite strength and microwave irradiation time period, and 2) granite strength and sensitivity to a given energy of microwave irradiation. Finally, a mechanism to explain the experimental results is proposed. Research findings will aid in the design of a microwave + machine rock-breaking system for use in rock breakage in underground mines at depth and for future mine applications on earth and other planets. In addition, the experimental approach could be used to test other rock types to further our understanding of rock damage induced by microwave irradiation.

Aug 1, 2013

By M. Kucharski

The model of the Outokumpu direct-to-copper process deals with a steady-state process the parameters of which do not depend on time. To give a prediction for the process outcome, "a modified black box" method, which ignores most of the chemical reactions in the furnace, was used. This method takes input and output parameters into consideration. The presented model describes the Outokumpu direct-to blister process in the form of the set of linear equations which give mass and enthalpy balances as well as the distribution of elements between blister copper and slag. However, only major substances where quantities in the feed charge exceed a certain level (for example 0.5 kg/ lMg of smelted concentrate) are taken into consideration. Minor elements are distributed among slag and metal phases in a different way. Some of the equations are derived from distribution coefficients. The value of distribution coefficients can be calculated from plant production data.

Jan 1, 2007