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By Ezra L. Kotzin

Foundry sands used to make molds and cores have been very important to foundrymen since metal casting began hundreds of years ago. They are now used in two basic ways, either in an uncured green state, grain-bonded with clay, or in a set cured state achieved with sand that, mixed with resins or oils, is cured by baking or by chemical reaction. The term sand, as generally used in foundry applications, may best be defined as material composed of granular particles of mineral matter, ranging in size from 0.5 to 2 mm in diameter. The particulate nature of the material may be the result of natural disaggregation or result from crushing and screening of rock or ceramic materials; crushed and screened products are sometimes referred to as "manufactured sand." Based on their origin, the raw materials for foundry sands will vary in grain shape, grain composition, relative surface, grain size, and grain distribution patterns. These properties, in addition to their chemical analyses, sintering point and expansion characteristics play an important part in the choice of sands used as the base molding or core aggregate in metal casting. Sands with different origins may be blended to produce specific compositions and grain size distributions. Early raw material requirements based on silica sand were simple, but as sand/core/mold technology became more sophisticated and binder technology continued to be developed, the physical properties of foundry sands became more critical. Silica sand is composed of quartz, along with, in most cases, small amounts of feldspar, mica, clay, and other common minerals. Although silica sand is still by far the most widely used base material in production of molds and cores used in metal casting, other natural mineral sands have their own unique characteristics and fill an important niche in special applications. As a result, the term sand, as applied to raw materials used in metal casting, has been logically extended to include granular materials composed of a group of minerals other than quartz. With increased use in advanced foundry technology, natural sands composed predominantly of zircon, chromite, staurolite, or aluminum silicate minerals and of granularized chromite or olivine, have become more than just alternate materials and are now commonly classified as sands when the grains are sand-sized. Foundry sand may therefore be considered under two categories: silica sands and non-silica sands.

Jan 1, 1994

By R. C. Fox

The geophysical aspect of reconnaissance marks the beginning of extensive computer applications supporting development of a mine. Although there are some storage and retrieval applications in geology, and some statistical analysis in geochemistry, large-scale compilation, reduction, and interpretation of mineral resource data are initiated in reconnaissance geophysics. The reasons for this fact are quite simple. Geophysics is oriented toward quantitative evaluation of areas of interest, and methods of data collection are automated to the extent that large amounts of analog and digital information are recorded. The large volume of data must be interpreted in a reasonable time. Furthermore, some modeling problems involving complex numerical solutions could not be attempted without the computer. Therefore, the computer is essential to the success of an exploration project using geophysics. For example, aeromagnetics is a common technique for reconnaissance examination of areas associated with sulfide systems and porphyry deposits. An area covering 161 X 161 km (100 X 100 miles) may be flown with a 1.6-km (1-mile) line spacing yielding 10,000 line miles (16,093 km) of data. If only 10 measurements are recorded per mile, 100,000 data points, including location and magnetic field intensity, must be reduced and stored for quantitative interpretation. Computer applications often represent a significant investment in manpower and hardware. It is desirable, therefore, to initiate an engineering approach to the application of computers to geophysics. By this it is meant that computer programs and systems should be formulated, developed, and implemented in a disciplined manner such that their usage is dependent only on the application and not on the individual doing the programming. In other words, computer application, development, and usage should evolve beyond the personal gadget phase to an important applied technology. Geophysics has evolved over the past two decades in a course parallel to computer hardware development. During the sixties, the computer became large enough and fast enough that complex models required by geophysics could be solved. Automation also relieved the geophysicist from routine manual calculations. During the seventies, computing power in¬creased and applications expanded from two-dimensional problems to three-dimensional modeling. Moving into the eighties, as computer hardware costs will significantly decrease, the major expense of computing will be the manpower required to develop, implement, and use an application; therefore, improved programming techniques and applications software engineering methods will be used to optimize and preserve this investment. This chapter presents a general overview of computer methods in geophysical reconnaissance; it is divided into two parts: geophysical methodology and software engineering.

Jan 1, 1979

By M. J. Virnig, Christopher A. Fleming

THE CIP PROCESS "IN THE RIGHT PLACE AT THE RIGHT TIME? After its tentative introduction to the precious metals mining industry in the earlier part of this century, the carbon in pulp (CIP) process has now come of age, and is the process of choice on all new gold mills. Well over 50 percent of all gold that is mined each year is recovered by adsorption on activated carbon, and the percentage will increase in the years ahead, when old mills using Merrill Crowe technology come to the end of their lives, and as the proportion of world gold production from low-grade resources increases. The pioneering process development work in this field, which was mainly concerned with carbon elution, was carried out by Zadra and his colleagues at the United States Bureau of Mines in the early 1950's (Zadra et al., 1950, 1952), and led to the commissioning of the first large-scale, industrial CIP plant, at the Homestake Mine in South Dakota, in 1973 (Hall et al., 1974). From there, the process spread rapidly, firstly in South Africa in the late 1970's. and then throughout the rest of the gold producing world in the 1980's. There were several factors that led to the meteoric (by gold industry standards) acceptance and successful implementation of this new technology into gold processing operations worldwide. Firstly, and perhaps most fortuitously, the development of the technology closely paralleled the 1968 release of the gold price from the rigid constraints of the $35/oz. gold standard. With the value of the metal allowed, for the first time in modern history, to fluctuate in response to free market supply and demand forces, the gold industry witnessed an unprecedented boom as the price of their commodity increased ten-fold in a remarkably short period of time. This had several important spin-offs as far as new process developments were concerned: The profits realized by established gold-mining companies increased enormously and, consequently, there was more to spend on research and development and exploration for new deposits.

Jan 1, 1993

By Eduardo Poltronieri Trés, Anderson Denadai Thomazini, Rodrigo Boyer Fernandes, Francisco de Assis Dutra Macedo, Gilvandro Bueno, Maycon Athayde, Rossano Augusto Pilon Nunes

The earliest industrial application of high pressure grinding rolls (HPGR) at comminution was in 1984 in the cement industry. Since then, the equipment has been widely applied in mining activities. Despite the rapid spread across the industry, several challenges are still present in the equipment’s application, especially considering the complex ore breakage behaviour reported for this process. The pellet feed’s HPGR comminution was recognized as fundamental to efficiently increase the particle surface area (e.g., blaine specific area, BSA) at a lower energy and water consumption level (Chapman et al. in J Southern Afr Instit Mining Metall 113:407–413, 2013). The present study considers a novel milling process applying only HPGR as a re-regrind stage after concentration. The amount of successive ground product recirculation into the machine to achieve the required particle size for the pelletizing process was investigated. The study compared the ball wet milling process with the innovative processing technology for hematite–goethite ores. Green pellet balling and induration processes were simulated in bench and pilot scale. The milling results showed a considerably steep increase in BSA after each recirculation step into the HPGR, although compared with the ball-milled product the size fraction <45 μm% increased a modest five percentage points after three recirculation cycles, remaining steady until the last recirculation step. As a result, the green pellet generated presented higher concentration of pellets between 10 and 16 mm (%10-16 mm), with a higher drop number than typically observed when produced with ball-milled feedstock. Consequently, on the induration process, a higher pellet deformation was observed during the pot grate loading. Despite that, the fired pellets still presented an outstanding performance in cold crush strength (CSS) considered suitable to an industrial application.

By Gabriel de Almeida

INTRODUCTION The widespread use of desktop computers by an ever increasing number of people, both for personal and for business and government uses, has brought public attention to surprising stories about computer abuse. Before the advent of microcomputers in the information processing environment, hundreds of amazing misdeeds involving large computers had already been reported, most of them perpetrated by highly skilled professionals. The undreamed enlarging of microcomputer potential has steadily posed a major threat to complex mainframe computing systems, as joyful teenagers become familiar with the habit of hacking around someone else&apos;s large processing system, by means of makeshift phone communication networks, based on their intended homework for personal computers -- for the sheer fun of it. Now, the never ending capacity and speed improvement of commercially available micros has given rise to a brand new concern for society: the hazards of processing sensitive information in the powerful, but still unsafe microcomputer itself, whether or not linked to other micros or mainframe networks. This paper deals with some aspects of the problems and presents some practical hints as to enhance protection and minimize risks to sensitive and secretive information when processed on microcomputers. The physical considerations of computer security and pertinent safety precautions will not be discussed, because while essentially relevant to information protection, recommendations are well defined by processing resources suppliers and their importance is more widely recognized by users in general. Definitions and Classifications. The following definitions and classifications will be considered in this report: Information Assets: Any knowledge or information processing, storing or conveying device displayed in one&apos;s environment. It consists of two main categories: INFORMATION RESOURCES: End user&apos;s application data wherever recorded. PROCESSING RESOURCES: EDP skilled user&apos;s hardware, software, peripherals, magnetic media, communication devices, auxiliary equipment, supplies and related operational procedures. Information Protection: In a broad sense this is the set of necessary procedures to assure to the legitimate user the effective control of the operation and allow modifications of information assets, so that their physical or cognitive integrity be preserved or any unexpected loss minimized inspite of accidental occurrences or intentional actions. Classification Processes: Commonly two classification processes are used to define key terms in information protection: SENSITIVE CLASSIFICATION: Pre-defined standards for assessing the vulnerability to losses due to lack of proper processing continuity if information is destroyed, disclosed, secluded, or misused. SECRECY CLASSIFICATION: A spectrum of degrees as to the expectancy of holding exclusiveness of unique information whose destruction, disclosure, seclusion or misuse will cause a negative impact on the legitimate holder environment. Sensitive Information: Any knowledge whose destruction. disclosure. seclusion or misuse - - - implies losses to its legitimate holder. It may be classified as: VITAL INFORMATION: An essential knowledge whose lack of proper availability implies total loss or termination of p

Jan 1, 1987

By G. W. Kenzy

Recently, in the United States, questions of possible deleterious synergistic health effects of the gaseous and particulate components in the diesel exhaust and mineral and coal dust have been the impetus for extensive research by several agencies. At the present time, diesel engines are tested and approved for use in gassy and non-gassy underground metal and non-metal mines under Parts 31, 32, and 36 of Title30 of the Code of Federal Regulations. Diesel-powered equipment for use in underground coal mines, though not explicitly addressed in the law, is administered under Parts 32 and 36 of Title 30, with Part 36 being applied in the case of equipment working inby the last open crosscut or in the return airways. Operation of diesel equipment in underground mines has the potential for serious health and safety hazards from the gases, vapors, and particulates in the exhaust. Therefore, various countries have rules and regulations for the safe deployment of diesel equipment. The applicable laws and regulations from several countries who have long experience with diesel-powered equipment in their mines are reviewed. Four major areas have been addressed: (1) testing and approval procedures of diesel engines, (2) ambient mine air quality specifications, (3) frequency of sampling and location of samples, and (4) air quality specifications in splits where diesel-powered equipment are operated. The review indicates that most regulations generally consider four possible hazards: (1) toxic components in the engine exhaust, (2) ignition of flammable atmospheres by the engine or electrical equipment, (3) fire hazards presented by the engine fuel oil and by combustible material that might come in contact with the equipment, and (4) mechanical hazards. There is a remarkable similarity in the laws with regard to engine design, testing and approval procedures. However, the aspects with regard to mine air quality and quantity are quite variable-- from a general statement to very specific standards for many different diesel exhaust constituents. However, the laws with regard to synergistic effects of diesel exhaust components and other mine air contaminants are an exception.

Jan 1, 1980

By Owen Kingman

This paper discusses grade control of ore mined at Tennessee Copper Company. Mineral zoning and the influence of mineral zoning on production grade are discussed and illustrated. In order to make this most understandable we will first briefly examine the flow sheet at Tennessee Copper to indicate the path followed by the raw material toward its various products. Then we will discuss some of the characteristics of the ore, specifically the distribution or zoning of the minerals in the ore which cause some of the grade control problems. Finally we Will discuss same of the steps that are taken to combat these problems. The flow sheet is illustrated as plate 1. The mined ore is allied to obtain 3 usable products: Copper concentrate, iron concentrate and zinc concentrate. Copper is found in the mineral chalcopyrite, CuFeS2. The Copper concentrate from the mill contains about 20% copper. These concentrates are smelter in reverberatory furnace and Pierce-Smith converter to blister copper containing 99.2% copper. Some metal is cast into 360 lb. pigs and shipped to the refinery. Some is made into shot copper and used locally to make copper sulfate. Copper sulfate is marketed from Copperhill principally in fungicides.

Jan 1, 1960

By John W. Amos, John A. Christophersen

The Deister No. 7, "77" and "88" Coal Washing Tables have been used by the coal industry in the cleaning of finer sizes of coal (-1/2") since washing of coals became necessary. This paper will deal with the in-plant use of the CONCENCO "88" Deister Coal Washing Table, along with a brief description of the Deister Refuse Superscalper. Efficient in-plant operation of the Deister Coal Washing Table can be accomplished by the adjustment of six basic variables. These variables are: 1. Headmotion 2. Feed 3. Riffle Pattern 4. Dressing Water 5. End Elevation Adjustment 6. Side Tilt Adjustment VARIABLE NO. 1 HEADMOTION The reciprocating movement of the "88" Table is developed within the headmotion entirely by rotating eccentric weights. Four parallel shafts each carry pairs of eccentric weights (Figure 1-A). The shafts are geared together with gears of 2 to 1 and 1 to 1 ratios, so that the two shafts in vertical alignment which carry the small eccentric weights operate at twice the speed of the other two shafts. The other two shafts are also in vertical alignment with each other and carry large eccentric weights. As power is supplied to one high-speed shaft, once each revolution the forces produced by the large eccentric weights are reinforced and then opposed by the small eccentric weights in a horizontal plane. The direction of movement of the table decks is reversed much more sharply at the forward end than at the backboard end of the stroke, causing material to move toward the refuse end of the table. Because in the vertical plane all centrifugal forces oppose each other and cancel out, there is no vertical movement and virtually no impact to the support steel. The "88" Coal Washing Table is suspended by wire-rope cables from three overhead steel beams, and operates with a perfectly uniform and exact differential motion curve in every stroke (Figure 1-B). The decks, being attached to the headmotion, are reciprocated in a parallel line from the head- motion to the refuse corner at speeds varying from 260-300 strokes per minute. Both length of stroke and speed are set at the factory for the coal characteristic desired and should not be changed. A 3 HP motor is mounted on the top of the headmotion and uses 3 V-belts to transmit driving power to the headmotion. The headmotion must be kept running on a horizontal plane. Punch marks are provided on the side and end of the main frame for use in leveling the motion (Figure 1-C). In leveling the motion, the work must always be done with two cables. To level the long side of the headmotion both front or both rear cables are raised or lowered to bring motion back to level. To level side to side, both right side cables or left side cables are raised or lowered to bring motion back to level VARlABLE NO. 2 FEED When tabling different size coals, each deck of a "88" DIAGONAL-DECK Coal Washing Table will handle feeds as described in figure 2-A.

Jan 1, 1988

By I. B. Tulu, M. M. Sears

In 2015, 40 longwall mines provided nearly 60% of the US coal production from underground mining methods. This represents a substantial yet gradual increase from just under 50% over the last 5 years. As a result of this increased production share, the percentage of ground-fall-related fatalities in longwall mines has also increased when compared to all US underground coal mines. Additionally, about 80% of ground-fall-related fatalities have occurred in areas where the roof was supported. In an attempt to better understand the status quo of current US longwall support practices, a sample of 25 longwall mines were visited representing nearly 50% of the currently active longwall mines representing all of the major US longwall-producing regions. The resulting data was obtained from a wide variety of overburden depths, geologic conditions, mining heights, ground conditions, support practices, and gateroad configurations. The data collected is reported using both qualitative and quantitative methods. Results from the research update previous efforts in classifying mining accidents and injuries as well as current support practices presented by this author at the 2017 Society for Mining, Metallurgy, & Exploration Annual Meeting. This data provides a necessary background for future research aimed at further reduction of ground fall accidents and injuries.

By I. B. Tulu, M. M. Sears

In 2015, 40 longwall mines provided nearly 60% of the US coal production from underground mining methods. This represents a substantial yet gradual increase from just under 50% over the last 5 years. As a result of this increased production share, the percentage of ground-fall-related fatalities in longwall mines has also increased when compared to all US underground coal mines. Additionally, about 80% of ground-fall-related fatalities have occurred in areas where the roof was supported. In an attempt to better understand the status quo of current US longwall support practices, a sample of 25 longwall mines were visited representing nearly 50% of the currently active longwall mines representing all of the major US longwall-producing regions. The resulting data was obtained from a wide variety of overburden depths, geologic conditions, mining heights, ground conditions, support practices, and gateroad configurations. The data collected is reported using both qualitative and quantitative methods. Results from the research update previous efforts in classifying mining accidents and injuries as well as current support practices presented by this author at the 2017 Society for Mining, Metallurgy, & Exploration Annual Meeting. This data provides a necessary background for future research aimed at further reduction of ground fall accidents and injuries.

By D. H. Carlson, J. H. Johnson, C. F. Renders

Research was conducted at a western coal mine on a wide variety of underground mining vehicles to develop testing procedures for portable instrumentation monitoring of tailpipe concentrations of diesel particulate matter (DPM), carbon dioxide (CO2) carbon monoxide (CO) and nitric oxide (NO). DPM was measured using the Emissions Measurement Appa¬ratus (EMA) developed by Michigan Technological University (MTU), and an ECOM-KL five-gas analyzer was used to measure gaseous tailpipe concentrations. Baseline concentrations of the tailpipe pollutants were measured using vehicle systems to load the engine. Concentrations before and after the water scrubber were measured and water scrubber efficiencies were estimated by calculation. Field measurement procedures were established. Heavy-duty vehicles with automatic transmissions were loaded using the torque converter to stall the engine. Consistent engine loading for light-duty vehicles with manual transmissions involved placing the transmission in neutral and adjusting the throttle to maintain a constant engine speed of 2,500 rpm. Tailpipe CO2 concentrations for Caterpillar 3306 and 3304 engines were compared to laboratory CO2 data from Caterpillar and MSHA to help determine if engine settings were correctly adjusted for operation at high altitudes. (Perfect agreement between the mine vehicle tailpipe and laboratory measurements would not be expected because of the differences in the test conditions.) DPM concentrations for light-duty vehicles ranged from about 20 to 160 mg/m3, and one light-duty vehicle averaged near 1,000 mg/m3. DPM concentrations for heavy-duty vehicles ranged from about 55 to 200 mg/m3. Widely ranging DPM concentrations for a particular vehicle type reflect the state of maintenance, fuel rate settings and different engine loading procedures as well as differences between samples collected upstream and downstream of the waterscrubber. The calculated DPM removal efficiencies due to the water scrubber varied considerably between vehicles, ranging from 13% to 51%. Calculations indicate that, under worst-case conditions, very large reductions in DPM may be required to meet the proposed DPM PEL of 0.15 mg/m3, even on vehicles with water scrubbers. In-mine ambient air studies, which are needed to actually measure the impact of the tailpipe concentrations on the work environment and the effect of mine ventilation on the dilution of DPM were not done in this first set of tests.

Jan 1, 2000

By James R. Brown

Mount Isa Mine should be regarded as a large mining complex rather than one mine. This arises from the geography, variety and extent of the orebodies, the mining methods, and the use of 14 shafts for ventilation distribution. A brief resume is presented here since comprehensive descriptions of lead-zinc mining methods {11}, copper mining methods {2 }{3}, geology 241, stope fill {5} and ventilation techniques {6}{7}, have all been published in the last five years. Mining extends over a north-south strike length of 2.5 miles (4 Ian) with a maximum width across dip approaching 3 200 ft (1 Ian). Current mining is to a depth of 3 150 ft (960 m) with the ore hoisting shafts extending 660 ft (200 m) deeper. The composite longitudinal section, Figure 1, shows a representational disposition of the copper and lead-zinc-silver orebodies in the central shaft complex where the main service and hoisting shafts are located. To the south the X41 man and materials shaft provides access to the copper area. The mine layout is typical of high tonnage track- less mines, utilising a large diesel fleet, raise- borers and some large diameter hole stope drilling. Mining methods include sublevel open stoping, slot and massfire, and a trial vertical crater retreat in the copper ore, and sublevel caving, sublevel open stopes with and without rib pillar recovery, and mechanised cut and fill in the numerous lead orebodies. All ore reports to one of the three crushing systems located below 19 level in the central shaft complex. Copper ore is hauled exclusively along the 19 level computer assisted Rockflo haulage system, and lead-zinc-silver ores report via central orepasses from Granby haulages on 13 level and 15 level. Tonnages hoisted during the 1977178 financial year were 5.0 million for copper at 3.2%. and 2.3 million for lead-zinc-silver at 7.8%. 6.3% and 7.06 oz/ton (216 g/tonne) respectively.

Jan 1, 1980

By Kenny Lo

"SummaryFor more than a century, ground freezing has been a construction technique used in stabilization of ground by means of lowering the temperature of surrounding soil strata. This technique is used in circumstances where conventional grouting method is unable to achieve the degree of consolidation required to prevent settlement and water ingress during the execution of underground excavation. Whilst ground freezing is effective in imparting self-supporting characteristics to the excavation profile, it poses significant challenges when it comes to the New Austrian Tunneling Method (NATM) where sprayed concrete is used to support the freshly excavated ground. Sprayed concrete, if used in an appropriate manner, provides a fast, efficient and structurally-reliable means of supporting the structure, especially in underground construction. The evolvement in sprayed concrete technology is attributed to the development of concrete know-how, improvement of spraying technique with the use of automation spraying equipment, more in-depth understanding of sprayed concrete behavior and enhancement of materials used in production of high quality sprayed concrete Not only has this markedly escalated the prominence of sprayed concrete on wider perspective,. the positive development has also pushed sprayed concrete beyond its boundaries, enabling it to be embarked on area of application not considered possible decades ago. Nevertheless, sprayed concrete, for all its placement versatility, still depends largely on the technicality provision very similar to concrete to achieve the required quality. Parameters such as raw material grading composition, curing temperature and cement quality are some of the factors that can easily sway the quality of concrete from one extreme to another. Conducive ambient temperature is critical in ensuring optimum hydration of concrete. This is more important in sprayed concrete where temperature plays a pivotal role in influencing the early strength and long term strength development. The low temperature imposed by ground freezing is everything but ideal for competent hydration to take place. This paper outlines how the innovative use of sprayed concrete helps to overcome the adverse ambient temperature in the construction of a 110m underground pedestrian walkway utilizing ground freezing technique in Hong Kong."

Jan 1, 2016

By Jida Wu, Zhenqian Wang, Chusheng Liu, Wenqiang Qiu, Mengqi Zou, Wei Zhao

During the dry screening, the hole plugging is a serious problem for most traditional screening equipment sieving the moist fine coal. It would lead to the low preparation efficiency and the low screening efficiency. The flip-flow screen is a new kind of screening equipment by using flip-flow motion of elastic screen surfaces to implement the separation of material. With the remarkable advantages of the extraordinary vibration intensity of screen surface, the hole is difficult to be plugged, and the screening efficiency is improved. In this paper, a kind of centralized forced flip-flow screen (CFFS) was proposed based on the crank rocker mechanism. The flip-flow motion of elastic screen surfaces is achieved by the periodical reversed motion of inner and outer screen boxes driven by crank. The advantages of the CFFS include considerable deformation of the screen surface, stable flip-flow quantity, low working noise, low vibration influence on environment, etc. The principle and construction of the CFFS were introduced, and the modal analysis and harmonic response analysis of key components (the crank and the linkage) were implemented based on finite element method (FEM), respectively. The first six orders of natural frequency and vibration modes were obtained. The maximum equivalent stress and strain under working and resonance frequency were achieved. The results illustrate that the resonance frequency is much higher than the working frequency, and the stress and strain are all within the safe limit of the material. The prototype was manufactured, and the sieving experiment demonstrates that the CFFS perform steadily, and screening efficiency is over 80%. The new feasible method of the dry screening was proposed by the CFFS. The corresponding numerical simulation and the experiment provided a reliable basis for the future promotion of similar product design and research.

Jan 1, 2017

By M. M. Champion

INTRODUCTION Since the first introduction of explosives into mining operations, safety considerations have prohibited the use of machinery in association with the explosives. Only within the last 25 years has this situation changed appre¬ciably; the closest thing to "machinery" used by a powderman in the "old days" was his wooden tamping stick. With the blackpowder and dynamite used during the first 150 or so years of mining blasts, substituting a drill steel or a metal "spoon" invited serious disaster. With the advent of ammonium nitrate-fuel oil (ANFO) explosives (1950s) and water-gel explosives (1970s) for underground blasting, machinery started to play a large part in blasting procedures. The lower sensitivity of ANFO and water gels allows these prod¬ucts to be loaded in a variety of safe ways. Not only has this meant cost savings in labor and blasting materials, but it has also resulted in whole new mining concepts where the limitations of dynamite previously made those concepts uneconomical, impossible, or excessively risky. Increasingly (totally for some mines), the traditional tamping stick has given way to a variety of pneumatic machines for loading explosives and blasting agents. The resulting blasting operations have become safer, more efficient, less uncomfortable for personnel, and a major step forward in mining technology. ANFO LOADING EQUIPMENT Three basic types of loaders are used for ANFO explosives, these being the pressure-vessel loaders, Venturi loaders, and combination loaders. Pressure-Vessel ANFO Loaders ANFO consists of prilled ammonium nitrate (porous pellets I to 2 mm in diam) and fuel oil in the appro¬priate 94 to 6% blend. The material is fairly dry, pourable, and easily conveyed by an air stream. One device or system for handling (hole loading) ANFO is the pressure-vessel loader. ANFO is dumped into the vessel or "pot," and the vessel then is pres¬surized. The ANFO is conveyed out of the bottom of the vessel into a semiconductive hose that has been inserted into the blasthole. Fig. 1 illustrates a typical pressure-vessel loader in use. Applications: The use of pressure-vessel loaders is widespread in room-and-pillar mines, including salt, potash, trona, lead, and other rubber-tired mines where the heavy pressure vessels can be mounted on a vehicle for transport from face to face. The vessel often is large enough to hold eight or more 23-kg (50-1b) bags of ANFO, so several faces can be loaded before refilling. Pressure-vessel loaders also are suitable for effec¬tively loading long holes such as those that are 6 m (20

Jan 1, 1982

By R. K. Mehta, S. K. Dhar, R. R. Mallepali

Introduction The incentives for developing a distributed form of the comminution model include: • for describing the heterogeneous comminution behavior of multiphase mineral systems (i.e. realistic ore bodies, such as complex sulfide ores consisting of chalcopyrite, galena, sphalerite, pyrite and siliceous minerals) and •for generating, for various locked and free particles, in situ, microscopic, breakage behavior such as the mode of fracture (intergranular vs. transgranular), the relative rates of breakage and the breakage distribution. However, the computational difficulty and the effort made in estimating a large number of parameters (Andrews and Mika, 1975; Wiegel, 1976; Herbst et al., 1985, 1988) do not justify the utility of this approach. Also, obtaining the results experimentally is very tedious and time consuming if using this approach. Although recent work in this area (Choi, Adel and Yoon, 1987; Mehta, Adel and Yoon, 1989, 1990) showed good results for liberated particles, the quality of the estimation and prediction was poor for locked particles. Attributing this to the complex breakage behavior of locked particles, it was concluded that additional constraints, and possibly modification in the breakage distribution functional form for locked particles, were necessary. However, further mathematical analysis revealed that the method previously used was in error. The purpose of this technical note is to present the correct solution methodology used in solving the general model equations of a multicomponent mineral system containing multiple classes of locked particles. Previous work and connection The general form of the comprehensive, distributed-component comminution model has been described as (Herbst et al., 1985) [d (m (0) -[ I - B ] S_ m(t) = A m(t) (1)] where [A] is the fundamental matrix/state companion matrix, commonly referred to, in the comminution literature, as the "mill matrix." Note that for a distributed-component comminution model, this is a full, general, real matrix, unlike a lower triangular matrix for a simple grinding model or a lumped-binary grinding model with one locked-particle class (Herbst et al., 1985, 1988). Also note that all of the underlined letters refer to matrices. Herbst et al. addressed the difficulty in arriving at a closed form of the analytical solution of Eq. (1) via similarity transformation [IT J inv (T)]]. This difficulty occurs for several reasons: •[A], as a general real matrix, may have complex eigenvalues and complex eigenvectors. •More importantly, there is no guarantee that a set of eigenvectors of [A] will turn out to be independent. An attempt was made to solve this problem by implementing a decomposition method. With this technique, the mill matrix was decomposed into a sum of lower and upper triangular matrices [(i.e., A = L + U)]. Then the solution was obtained using similarity transformation (Mehta, Adel and Yoon, 1989, 1990). [e(At) = e(L+U)t = e(Lt).e(Ut) _ [ TL Jt- (t) inv(T_L)] [-Tu Ju (t) inv(Tu)]] [But, unfortunately, e 1+U = e t . eu is true only for scalars and not for matrices (i.e., eL+u# eL- eU) unless they commute. In other words. eAt = e(L+u)t= ekt - eU&apos; if LU = UL. Hence, this decomposition scheme must be replaced by a mathematically acceptable method known as the "splitting method"]

Jan 1, 1994

By David A. Hedderly-Smith

Sealaska Corporation, the Alaska Native Regional Corporation of Southeastern Alaska, was organized under the laws of the state of Alaska pursuant to the federal Alaska Native Claims Settlement Act of 1971. Large areas of Sealaska&apos;s 630,000-acre (250,000 hectare [ha]) fee subsurface holdings are underlain by carbonate, and while much of this material is assumed to be common variety limestone and lesser dolomite, at least two areas in the Silurian Heceta Limestone contain high-quality limestone at tidewater. This limestone has many potential commercial uses. On northern Prince of Wales Island, about 90 miles (144 km) north-northwest of Ketchikan, resource development at Sealaska&apos;s Calder deposit has established a reserve of 13 mil- lion short tons (st) (12 million metric tonnes [mt]) of carbon- ate rock containing an average of greater than 98 percent CaC03, approximately 0.5 percent MgO, less than 0.5 per- cent Si02, and approximately 0.15 percent Fe203, with insolubles averaging less than 0.5 percent and an average Hunter Brightness of 92.07 for the -150 mesh grind (with a bright- ness cutoff of 90). The deposit is open at depth and to the south. Ultimate reserves will likely be several times those currently established. In 1998, Sealaska began mining the Calder deposit, with about 100,000 st (90,000 mt) produced, and also completed a marine terminal one half-mile (800 m) from the deposit. The terminal can load ships up to 680 feet (200 m) in length at a rate of 2,000 st (1,800 mt) per hour. 0 m) in length at a rate of 2,000 st (1,800 mt) per hour. On Dall Island at Breezy Bay, about 60 miles (100 km) southwest of Ketchikan, Sealaska has identified a limestone reserve in excess of 150 million st (135 million mt) that (based on 18 surface samples distributed evenly over about a section of land) contains about 98 percent CaC03, and less than 0.5 percent MgO, 0.5 percent Si02, and 0.15 percent Fe203. Brightness of the Breezy Bay carbonate is considerably less than at Calder. Five samples of brighter material from Breezy Bay returned brightness analyses in the high 80s and low 90s; average brightness is probably below the mid- 80s. Sealaska has also identified a deposit containing more than 19 million st (17 million mt) of similar rock near View Cove, a few miles south of Breezy Bay.

Jan 1, 2001

By Z. Kowalski

In the non-operational ?Górka? quarry, there are situated both a waste disposal site of an area of 6.7 ha, containing approximately 1 million ton wastes from high aluminium content materials (incl. about 400000 t of wastes from aluminum hydroxide production), and a pond of an area of roughly 3 ha, up to 15 m deep, with about 400000 m3 of polluted water and infiltrates from the disposal site mentioned. The basic problem related to the effluents in the Górka pond is both their high alkalinity (pH 12-13.4) and a variable analysis of pollutants whose level increases appreciably with the pond?s depth. The solution offered provides, first of all, remedial pumping and a treatment of effluents retained in the Górka reservoir. Effluents would be treated in a reverse osmosis plant according to a process verified so far on a quarter-commercial scale. The treatment process by-product, a brine solution (containing about 25% NaCl) whose amount may reach up to 100000 m3 might be supplied to the Debiensko Mine, which produces technological salt from salt-bearing mine waters. In parallel, an intake of underflows of infiltrates would be provided (previous geochemical identification) in order to take them away from the high aluminum site (by means of deep wells, and possibly girdling ditches). Such effluents would be subject to treatment. The successive stage is the utilization of approx. 50000 m3 of bottom slurry, left in the emptied reservoir, in the production of self-solidifying mixtures, which would be then used for sealing the bottom and the banks of the Górka reservoir. The empty and sealed reservoir would be filled up with a volume of approx. 600000 t of ashes, coming from coal burning in the thermal-electric power station. For the last stage, instead, is scheduled the rehabilitation of the entire waste disposal site in the Górka quarry. The site will be drained, covered with a leveling, sealing and rehabilitating layer, which will allow to introduce plants on the rehabilitated waste site. Later on, the area could be turned into a town park

Jan 1, 2006

By R. Addison, P. V. Avotins, E. Martinez, L. A. Haas, D. K. Mortenson, E. EI-Shall, R. D. Kulkarni, M. D. Flavel, S. Chong

Mineral processing activities in general reflected the economic ills of 1981 and early 1982, but in some areas the depressed state of the industry resulted in increased activity. As were all aspects of the minerals industry, processing plant operations were severely affected by the recession-prone economy, by sagging prices for primary metal products-copper, molybdenum, nickel, iron, manganese, and especially uranium-and numerous shutdowns and layoffs. Copper production by major producers in Arizona and Utah was severely curtailed; Amax, the major US molybdenum, producer did considerable belt-tightening; and the uranium industry was in a state of disaster. Even the precious metal superstars-gold and silver-were affected, with a steady decline throughout the year in world market prices. Perhaps hardest hit have been newly developed properties, particularly in the uranium industry, and old-line properties where historical development impacts today. No longer can such properties afford the luxuries, for example, of a long haul distance between mine and plant or continued use of antiquated facilities. Surprisingly enough, the very state of the economy has caused increased activity in some sectors of the mineral processing industry. In mill design, although large projects have been tabled, smaller projects have gone on, with innovations in design, often for cost-saving reasons, that will affect future designing approaches. Economic restrictions are impacting on mill flowsheets as researchers look for improvements and better, less expensive techniques. Other unit processes-hydrometallurgy, pyrometallurgy, concentration, materials handling-are impacted by the need for a better, less costly product. Although at the end of the first quarter of 1982, no major environmental legislation had been enacted, rumors persist that there will be a loosening of some of the stricter standards, both in the requirements themselves and in the time allowance for implementation. The year had seen some relaxation in how current legislation and standards are administered. For example, in OSHA (Occupational Safety and Health Administration) operations, there has been a shift toward voluntary checking of industry compliance with work rules, rather than emphasis on agency inspections. However, the industry continues to view environmental factors as having major influence on future operations and efforts to design for environmental safety are becoming almost as important as the processes themselves. Throughout the industry there has been a further focussing on project management, recognizing the necessity for tight control of budgets and schedules-and the systems used to effect them. Materials Handling Review prepared by A. T. Yu, ORBA Corp. The frenzy of coal export activities has continued into 1981. Many modern export terminals are now in construction while others have either been held up or cancelled. Economics and environmental permits have been some of the major problems. Currently under construction are terminals in Newport News, VA; Charleston, SC; and Baltimore, MD. Expansion of existing facilities at Mobile, AL, and New Orleans, LA, is also well under way. A wide variety of systems and components are being used. They include traveling shiploaders, tunnel and bucket wheel reclaim¬ers, stackers and high line trippers, and bottom and side dump-type car dumpers. Manufacturers from Japan and Europe have been participating along with domestic suppliers. As an attempt to avoid environmental problems, a system of loading and unloading coarse coal

Jan 5, 1982

By Holger Witthaus

Various seam conditions had been examined during longwall production at RAG German hard coal mines. Based on the field data a prediction method was developed considering separation planes as influencing factors for roof falls at the face. The characteristics, orientation, and density of separation are important factors on the occurrence of roof falls. In addition to geological influences, the performance parameters and geometry of support must be considered and optimized for the prediction and prevention of roof falls in a longwall face. Based on detailed macro- and microscopic investigations of e coal seams considering various ranks of carbonization, the origin and characteristics of separation planes are determined and a strata-specific influence on roof fall is interpreted. It was assessed that the coal face fracturing and displacement caused by the stress depend on the floor and roof strata conditions due to activation of the existing separation planes. Field studies are shown giving an idea of influences by advance rates of the longwall face, support delay and hydraulic pressure to the roof control in longwall faces in depth of more than 3000 ft. The analysis includes the application of specific software developed for longwall roof fall prediction as a result of a European research project. The software allows a laminar graphic display of roof fall probability, which is used for recognition of risk areas and risk management.

Jan 1, 2009