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By Ronald B. DeDiemar

It is generally held that cone crusher application technology is strictly an art and thus subject to the vagaries of emphirical and/or trial and error judgments. While this is basically true, certain factors have been identified which, when properly defined, can significantly reduce the element of chance. This paper will bring out these factors as well as pointing out other technologies available to predict and/or analyze cone crusher performance.

Jan 1, 1977

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By R. G. Reddy

Solid state reduction of roast movat chromite ore with carbon was carried out as a function of C/FeO ratio and temperature in the range 800°C to 900°C by thermogravimetry analysis (TGA). A two stage mechanism, (1) the reduction of FeO present in Roast Movat with carbon monoxide; and (2) the regeneration of CO by the oxidation of carbon with CO2 was proposed. The rate controlling step is the carbon oxidation reaction. A kinetic equation, that of random nucleation, was proposed. The activation energy for the reduction was determined to be 55800 J/mole and is compared to those activation energies determined for other chromite ores.

Jan 1, 1998

By Dwight K. Smith

Fly ash as an additive for oil well cement was introduced to the oil industry by the Halliburton Company in 1949. Since its early usage in the Illinois area of the U. S., the total amount of fly ash pumped into wells has exceeded 30 million sacks, The advantages of using fly ash-portland cement mixtures in wells are fundamentally the same as for concrete except the conditions of placement and curing are variable and the nomenclature of properties are expressed somewhat differently. In some instances deep wells have been cemented with mixtures of fly ash and hydrated lime together with an activator which functions as a catalyst for setting. This fly ash-lime formula has many advantages for high temperature-pressure conditions found in wells.

Jan 1, 1968

By James D. Bliss

Evaluation of data for three engineering variables-absorption, bulk specific gravity, and freeze-thaw durability (350 cycles)-was made for quarries in carbon- ate rocks in Oklahoma that supply aggregate. It was found that lower Paleozoic carbonate rocks (Cambrian through Devonian) are likely to make a better quality aggregate than upper Paleozoic (Mississippian to Permian) carbonate rocks. In addition, freeze-thaw durability can be forecast from absorption and is exemplary for lower Paleozoic carbonate rocks.

Jan 1, 1999

By Thomas F. Stinson

Energy-producing states see severance taxes as attractive sources of increased revenues for otherwise tight budgets. Consumers in energy-poor states, however, protest that current rates are excessive and have moved to obtain a reduction. The US Supreme Court heard two cases questioning such taxes during its 1981 term, and Congress, in each of its last two sessions, has seriously considered measures placing a ceiling on severance tax rates. Although discussions usually focus on coal severance taxes levied by Montana and Wyoming, ramifications of changes in national policy are much larger, potentially affecting mineral taxes in all states. Severance taxes yield substantial revenues in some states, as illustrated in the accompanying table. In fiscal 1980, Texas collected more than $1.5 billion from such taxes, while Louisiana, Alaska, and Oklahoma collected $525 million, $507 million, and $436 million, respectively. Oil and natural gas production were the major items taxed. While the table shows only the 10 states with the largest severance tax collections, a total of 17 states had severance tax receipts exceeding $10 million in 1980. The enormous increases in severance tax revenue between 1970 and 1980 can be seen from the table by comparing columns A and B. For the 10 states shown, revenues increased from $650 million to $3.8 billion during that period, due to a combination of higher prices, increased production, and new or increased taxes. In most states, increases in prices and production were more evident than higher tax rates. Although the revenue increase is impressive, it understates the extent of changes occurring during the past decade. Since tax collections are shown for fiscal 1980, the full impact of the decontrol of domestic oil prices is not evident. Also, taxes on natural gas reflect controlled prices. When full de-control of natural gas occurs, significantly higher revenues can be expected in gas-producing states, even if tax rates, production, and world prices remain constant. These increases in severance tax revenues, coupled with further increases expected to accompany natural gas decontrol, have produced fears that a substantial transfer of income is taking place from residents of energy-poor states to those living in energy-rich areas. Others worry that increased severance tax revenues will be used to substitute for a substantial portion of state taxes that would have otherwise been collected from firms and individuals. The resulting improvements in tax climate, it is thought, may encourage firms and workers to migrate to energy-producing states. While these issues are often portrayed as pitting energy have-nots against the haves, such is not entirely the case. Much of the original impetus for limits on coal taxes came from Texas residents, the state collecting the most severance tax revenue. One way of gaining perspective on these concerns is by examining severance taxes per capita and as a percent of state tax collections (see columns C and D in the table). When this is done, Alaska, where 1980 taxes on oil and gas production totaled more than $1300 per capita (and 35% of all state tax collections), stands out as a special case. There, the state was able to eliminate some individual taxes, place revenues in a permanent trust fund, and consider offering a rebate of some previous income

Jan 4, 1982

By Dal Negro Enrico, Andrea Picchio, Boscaro Alessandro

"The Doha Metro Project is one of the most relevant ongoing tunneling projects. The whole project consists of about 100 km of tunnels with 21 EPB TBMs working in the same period. Due to the variability of the geological formations, the soil conditioning is a relevant aspect of this project because the parameters should be frequently adjusted to achieve the best performances of the TBMs. The study of the soil conditioning has been carried out accurately to obtain the best results on site. The study of the geotechnical data, the choice of the most suitable foaming agents and polymers and the laboratory study of the soil conditioning has been a fundamental part of the job. The application of the soil conditioning products on site with the analysis of the TBM data have confirmed the preliminary study results with some correlation between the features of the ground and the soil conditioning parameters to be used. INTRODUCTION Phase 1 of the Doha Metro Underground project is composed by 3 lines able to bring passengers to all the points of interest in the Qatar capital city. The Red Line, also called coastal line, connects the north of the city to the south, and to the new Hamad International Airport, following the coast line. The Golden Line, called Historic Line, will connect the southern area of Doha to the “Aspire zone” the area of the city where many state of the art sport centers are located, passing through the old city center. The Green Line, named education line, will connect the old city center to the Doha Education City. All the lines are realized with 2 tubes, single track. The whole underground project is realized with 21 TBMs, excavation diameter of 7.10 m. The project has been divided in 4 packages, for a total excavation length of more than 100 km. The need to underpass roads, existing buildings, and to excavate, in some areas, at less than 100 m from the coast line, forced the choice of a tunneling system with Earth Pressure Balance (EPB), that involves in the project another fundamental aspect of this tunneling system: the soil conditioning. The soil conditioning has multiples functions in the EPB system such as to make the soil suitable to properly apply the pressure on the tunnel face and to be extracted effectively with the screw conveyor. To properly study this topic it was necessary to study the geological formations to be excavated, the hydrogeological conditions of the underground, the foam injection systems of the EPB TBMs and to perform specific tests to evaluate a suitable conditioning to be verified and adjusted during the real scale application."

Jan 1, 2016

By Steven W. Hunt, Gregory C. Baker, Glen J. Rorison

Microtunneling methods were utilized beneath pile-supported clarifier basins to replace settlement damaged sludge drain lines at the Jones Island Wastewater Treatment Plant in Milwaukee, Wisconsin. To minimize the risk of blockage and expensive recovery of a microtunnel boring machine against pipe piles or construction debris, a Soltau RVS 80 was utilized. This machine allowed the alignment to be initially bored with guided 114-mm diameter rods to ensure proper alignment and lack of obstructions. Casing pipe was then installed by jacking 1-m long, 305-mm diameterclay pipe along the rods and behind an auger head. This case history also discusses how 2.4-m diameter precast concrete pipe was used as a one-pass sinking caisson for workshafts and new cleanout manholes.

Jan 1, 2001

By [Miroslaw] M. Hajdasinski

The Payback Period (PBP) is one of the most widely applied project evaluation criteria 'in the mineral industry. As much as this criterion is liked by practitioners, it is also criticized by academicians who seriously question its validity. Inspired by this criticism, the author of this paper examines the classical definition of the PBP criterion, and formulates a new one designed for both investment and borrowing projects. It is demonstrated that the PBP, in its revised version, is free from all the shortcommings of the old one, and is fully compatible with the Net Present Value (NPV) criterion, as well as with all the other NPV compatible project evaluation criteria. Since the traditional approach to the comparison of mutually exclusive projects (MEP1s) by means of the PBP criterion has been incorrect, the paper also outlines the correct approach to this problem. Finally, owing to the fact that the PBP depends on the assumed interest rate, and using a specially developed computer program, the PBP is graphically presented, in six numerical examples, as a function of the interest rate.

Jan 1, 1989

By E Marambio, R Brändle, G Fischer, G von Rickenbach, L Burgos, R Luis Fonseca

Ground support systems must provide safe and effective designs for underground excavations under high stress conditions. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the arrangement, measurement, results, and the preliminary analysis of a single impact dynamic test performed during 2021 of a ground support system with a high-tensile steel wire mesh MINAX 80-4.6 is presented.

Apr 26, 2022

By S. Yap, F. J. Sotillo, L. P. Irwin, F. M. Utsey

Slimes, especially clays, are detrimental to several processes in the Mining Industry. The efficiency of classification, clarification, gravity separation, and flotation decreases significantly in the presence of slimes and clays. This problem is particularly critical in the Phosphate and Sulfide Industries. To reduce the effect of slimes in mineral processing, several desliming techniques and chemical additives are used, such as sodium silicate, sodium carbonate, sulfuric acid, tripolyphosphate, hexameta phosphate, etc. Lately, the Mining Chemical industry has shift to more “Specifically Developed” reagents that offer the most efficient and cost effective performance, mainly using organic polymers. For this purpose, the Mining Chemical Industry needs to understand the crystal chemistry of minerals, the chemistry of the aqueous media, the interactions in solids-aqueous-gas interfaces, the rheology of the system, and the plant operation conditions and parameters. This paper describes the use of surface chemistry fundamentals on the design of an organic polymer capable of modifying the rheology of clayish slurries of a phosphate ore. The change in the rheological characteristics of the clayish phosphate slurries allow fine ore particles to settle faster by reducing the slurry viscosity. Thus, abetter separation of the ore from the slimes is possible using gravitational or centrifugal forces. As examples of the application of this reagent, industrial and pilot plant tests on desliming using tanks and hydrocyclones are presented. These tests showed the reduction of 32%-36% in ore losses for different phosphate ores during desliming operations, and the increase of cyclones desliming efficiency to 80%. Tests were also carried out to improve the rejection of unwanted iron bearing slimes in phosphate feed. These tests demonstrated that it is possible to reduce by 0.25%-1.23% Fe2O3content in the flotation feed product. As a result, significant economical benefits are observed with the use of this new technology without any adverse effect on down stream operations, such as clay settling or phosphate flotation.

Jan 1, 2003

By D. R. Schmitt, B. L. Jensen, T. J. Ahrens, C. L. Smither

The in situ elastic moduli of rock are measured holographically by a borehole instrument in marble and oil shale. A point force induced displacement field is recorded with double expo- sure holography. Data consists of a fringe pat- tern on the viewed hologram. The elastic moduli are determined by modelling of the fringe pattern. Only Young's inodulus is fairly constrained by the present data reduction. For an applied force of 520 [ ] 50 Newtons, a marble was found to have a Young's modulus of 56 [ ] 8 GPa, near an ultrasonically determined value of 48 [ ] 6 GPa. In an oil shale, an applied force of [ ]

Jan 1, 1986

By D. W. Park

Longwall mining is considered the most efficient underground coal mining technique in terms of coal extraction ratio, production rate, and safety standards. Due to the increasing demand for higher coal production, wider panel and faster face movement have become the recent trends. Thus, longwall mining can create unexpected threats such as roof falls, excessive face convergence, shield damage and numerous maintenance problems causing sudden interruption of coal production and serious safety hazards. A recent study at the University of Alabama is dedicated to develop LoSCoMS (Longwall Strata Control and Maintenance System) which integrates real-time shield monitoring, data presentation, analysis, forecasting, and warning modules. The main objectives of this system is to provide the stability and maintenance information, at every minute, such as high load, low setting pressure, leg leakage, etc., analysis of various mining and geological parameters to determine past and present roof characteristics and forecasting of loading patterns for the following mining cycles, next periodic weighting, etc. Using this unique system, mine operating personnel are well aware of past, present and future roof loading patterns at the longwall face, and thus, proper safety measures can be taken ahead of time.

Jan 1, 1997

By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (US.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have in- creased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.

Jan 1, 1997

By Hassan El-Shall, G. L. Zucker, T. S. Jordan

INTRODUCTION This chapter will discuss, both from fundamental and practical points of view, the flotation of non-sulfide min- eral s. The flotation characteristics of silicates, salt-type minerals, oxides and coal will be reviewed. Dup- lication of the thorough and excellent presentations by many authors is not intended and a comprehensive list of references is included. GENERAL PRINCIPLES Collectors for Non-Sulfide Minerals : All minerals, with only a few exceptions are readily wetted by water, that is, they are said to be hydrophilic. The purpose of a collector is to coat the mineral surface and render it hydrophobic, preferring an environment of air over an environment of water. Relative to sulphide minerals, the non- sulfides are more naturally hydrophilic and therefore, require a collector with a greater chain length. This is accomplished by using a collector which has a proportionally longer hydrocarbon chain. Both anionic and cationic flotation collectors are used in non- sulfide flotation. Anionic Collectors. These are collectors which ionize in solution to give a negatively charged radical. They have the general structure R-A, where R is a hydrocarbon having 8 or more carbon atoms and A is a hydrogen or an alkali metal. The most common collectors in this group are fatty acids which could have saturated or unsaturated hydrocarbon chains. Such chains may be straight or branched. The configuration of the chains affects their solubility in water and their adsorption characteristics. In general, as the chain length increases the adsorption and the collecting power increases. However, it should be noted that the solubility decreases. The solubility of unsaturated chains is greater than that of saturated fatty acids because double or triple bonds are polar and thus attract water molecules. Solubility data for collector metal salts, even though important for a proper understanding of flotation are not available for all collector systems. Solubilities and structures of different fatty acids are reported by Fuerstenau (1982). Values for the solubility products of fatty acid salts selected from a paper by Du Rietz (1958) are given in Table 1.

Jan 1, 1986

By G. Machiavelli, P. Bevilacqua, G. Ferrara, T. P. Meloy

During several years of operation in Europe, South Africa and other locations, the Tri-Flo process has demonstrated substantial improvements in dense-medium dynamic-separation systems. The reasons for this improvement are: • a high-sharpness separation due to the multistage system and the application of new concepts in the design of the regeneration circuit and in the control of the medium Theology, and • the possibility of performing two cuts at different densities using a single separation device and a single regeneration circuit. This paper discusses the above points in detail with particular reference to the multistage technology (based on the circuit analysis theory) and to the control of the medium rheology (based on recent work in the modeling and simulation of the rheological behavior of dense suspensions). Concerning the multidensity separation, information is given on the new three-stage separator where the high-density separation is performed by the first stage and the low-density separation is performed by the second and third stages. This configuration (already realized in two operating plants) was selected because no particular sharpness was required at the high-density separation, while high sharpness was required at the low-density separation. However, the configuration can be inverted or a fourth stage can be added (at very low additional cost) to provide two stages for each separating density. The importance of achieving a high sharpness separation is related to minerals (industrial minerals in particular) where the density difference of the phases to be separated is very low (as in processing of lithium ores, feldspar- and others). Information is provided on plants operating in South Africa and Canada, for the beneficiation of lithium minerals and on a plant under construction in Italy for the beneficiation of feldspar. Finally, the importance of making the separation at two densities is emphasized with particular reference to coal; i.e., producing a low-ash premium coal and recovering, in the middling, a by-product without losing heating value. Also, very important for some minerals is the production of a high-grade concentrate (at the first stage) suitable for sending directly to metallurgy (e.g., chromite ores) and the production of a low-grade concentrate that can be further treated. In this way, a higher overall recovery of the valuable mineral can be achieved, and, at the same time, a reduction of the treatment costs can be obtained. All of the above applications were once considered impossible.

Jan 1, 1995

By S. Rezaei

Moving ground in the mining industry is almost inevitable; however comprehensive awareness of these movements is necessary to mitigate risk. Monitoring of displacements caused by mining is a key tool for geomechanical risk management. Good monitoring may prevent unexpected failures and protect personnel and equipment. Many displacement monitoring techniques are available, however not all are reliable, accurate, and cost effective. Close range photogrammetry (CRP) is a monitoring method with high accuracy, reliability, and cost effectiveness; and has the ability to measure places that are inaccessible. In CRP, some series of photos are taken in different positions with different angles at different time intervals depending on the displacement rates. These photos are processed using PhotoModeler software and 3D models are made. By comparing 3D models, displacements can be measured. This method has been demonstrated at the Freeport-McMoRan Safford Mine in Arizona. A fault related instability in part of the pit is reactive to mining, and provided an opportunity to compare results between traditional monitoring methods and CRP. In this project, multiple series of photos were taken at different times using a Canon 5D Mark III digital camera, then PhotoModeler software used to make 3D models for each specific measurement event. Movement rates were determined by comparing different 3D models. These results are then compared to results of other monitoring methods to validate the CRP displacement method.

Feb 27, 2013

By J. H. Bassarear, P. F. Thomas

Large-scale equipment can reduce both capital and operating costs for concentrators. Large semiautogemus (SAG) mills can be effectively utilized in big mills but they must be kept fully loaded to tab advantage of their great potential. With varying hardness ores, controlling throughput is difficult and careful design must take this into consideration. A variable speed drive on large primary semiautogemus mills can overcome this problem to a considerable degree. This paper provides a base case using standard accepted technology of two wound rotor single speed 4476 kW (6000 hp) motors to drive the primary SAG mills of a hypothetical 36,364 t/d (40,000 stpd) typical porphyry copper mill. One other fixed speed drive will be described and jive variable speed drive configurations will be reviewed. Capital costs for the entire grinding circuit, from crusher product to flotation feed, were developed for the base case and each of the alternatives. A technical evaluation comparing the advantages and disadvantages of each drive is presented.

Jan 1, 1987

By David P. Keller, George Podolsky

Iron oxides are unique in that they are the only significant colored mineral found in a natural state suitable for use as a pigment after being pulverized to pigmentary size. The world production of iron oxide pigments is estimated by the authors to be between 350 and 400 kt. The fact that highly colored natural deposits of iron ore are found throughout the world accounts for its use in prehistoric man's artistic cave paintings. These early artists did not realize that they had established man's first paint test which now has some 20,000 years of exposure. In addition to abundance, iron oxides (about 7% of the earth's crust) have the advantage of low cost, permanency, and are non- toxic. Through the centuries, succeeding civilizations have utilized iron oxides as a major source for decoration and protection when these properties were desired. In the last century the chemical industry has improved on nature by developing a complete range of synthetic iron oxide pigments which surpass the pigments produced from natural iron ores in uniformity, color quality, and chemical purity. In the United States, the combined production of natural and synthetic iron oxides produced sales of over $97 million in 1980 (Spimad, Jr., 1980), increasing to $138 million by 1990 (Templeton, 1990) NOMENCLATURE With the increasing importance of the synthetic iron oxides it is necessary to make a distinction between the natural or mineral pigments and the synthetic pigments. Natural pigments are those products that are derived from selected ores and should not be confused with iron ores mined for steel production. Iron ores that are mined for steel must be capable of being mined and reduced to iron on a competitive commercial basis. These ores are selected on the basis of iron content and processing economics. It is therefore unusual when iron ores for steel production are suitable for use as mineral pigments. Natural pigment ore sources are selected for their special physical-chemical properties and are able to command a premium price over iron ores used for steel manufacturing. Synthetic pigments, and in this instance iron oxides, are those pigments produced from basic chemicals. Through chemical synthesis pigmentary particles are produced as opposed to the use of comminution, the major procedure common to all natural iron oxide pigments.

Jan 1, 1994

By Richard Switalski, Mark R. Kritzer, Boro J. Lukajic, Robert Pintabona

Ground freezing was chosen as an initial support method during construction of two deep shafts at the Mill Creek project. The Mill Creek, Phase 2 tunnel (MCT-2) is utilized to convey and store combined storm and sanitary sewage collected from the member communities in the greater Cleveland area. The main objective of groundfreezing was to provide a strong support structure to resist soil and groundwater pressures. This was achieved by creating a watertight, frozen-ground barrier around the shaft perimeter. The paper will provide an overview of ground freezing techniques applied during the construction of two shafts, each 250-feet deep.

Jan 1, 2003