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By S. Gupta

Froth flotation is a process commonly employed for the selective separation of phosphate from unwanted mineral. Column flotation has become widely accepted in the mineral processing industry, including phosphate industries, due to its ability to improve selectivity, lower operating cost, lower capital cost, and superior control. In this work, a hybrid model is developed that combines a physicochemical model with artificial neural networks. The physicochemical model is based on axial dispersion with first order collection rates. A new approach, in which both frankolite (the desired mineral containing phosphate) and gangue (undesired product) are modeled, enables prediction of grade of the recovered product. Thus, two basic parameters are required in this model: flotation rate constants for frankolite and gangue. Artificial neural networks are used to predict flotation rate constants. The model also takes into account the particle size distribution and predicts grade and recovery for each particle size range. The model then combines grade and recovery for each particle size range to determine the overall grade and recovery of the column. The model is validated against laboratory column data.

Jan 1, 1998

By Herschel H. Potter

While preparing this paper, I soon realized I had a problem in defining what injuries should be classified as "personal." Admittedly, in some cases, falls of persons, sprains and strains, pulling and pushing injuries, and back injuries may have been caused by the individual. But, I believe the number of injuries directly attributed to an individual's carelessness is relatively small in comparison to the total number of injuries in those categories. For discussion purposes, the injuries most often considered to be personal, that is, caused by individuals are those classified as back injuries. My paper will be devoted to back injuries because this category represents the greatest number of injuries occurring in coal mining. A man's best friends are his wife, his back, and his dog. The back, however, has a reputation of not being as faithful as his other two friends.1 "Industrial back injury is one of the major occupational health problems plaguing industry to- day. According to national surveys, back injury accounts for more lost time than any other occupational injury and costs companies thousands of dollars in compensation, medical fees and over- time pay."2 A study conducted by USA Today found that back ailments afflict an estimated 75 million Americans, have totally disabled about 2.5 million adults, lead to as many as 200,000 required surgeries each year, are a leading cause of absenteeism and disability, are the second leading cause of hospitalization, are responsible for 18 million doctor visits a year and cost about 93 million work-days annually. The cost to industry is estimated at $14 billion a year.3 During the past 30 years, a great deal of accident prevention education has been directed toward the reduction of back injuries. However, this effort has not produced any great change in the incidence of the injury. Back injuries should be of the utmost concern to everyone here today. I don't need to tell you what the incidence rate is for back injuries, nor will I use any statistics to inform you of the incidence rate for the coal mine industry or any specific mine. It is only important to know that the number of back injuries is excessive. Back in- juries resulting from lifting have been and continue to be one of the most constant and undiminishing problems in the occupational environment. The fact is, we use our backs to per- form work that the back was not designed to do. Historically, manual materials handling related accidents have consistently accounted for the largest percentage of all industrial accidents. In fact, over 25 percent of all industrial accidents are related to handling of materials.4 In underground coal mining operations, material handling accidents account for even larger percentage of lost time injuries. In 1983, for example, they accounted for 34 percent of all lost time injuries and 32.6 percent of all non-lost time injuries. 5 I want to use one example of a task that will illustrate what I have just said: the building of a concrete block stopping. Each solid concrete block will weigh from 60 to 70 pounds. To build a stop- ping 6 feet high and 20 feet wide will take approximately 80 blocks. On the average, these 80 blocks will be handled at least four times from loading into the conveyance for transportation to being placed while constructing the stopping. This generally requires repetitive lifting from ground level. The next three slides demonstrate the lifts

Jan 1, 1986

By G. J. Hartman

A presentation of this project was given previously at the SHE Annual Meeting, Denver Colorado February 23-27, 1987. The project concerns the development of in situ recovery of borate products from a deep-seated colemanite deposit in California. The deposit contains some 147 million tons of borate ore containing 6.4% boron oxide (B2O3). This paper involves the numerous changes in the process that has taken place since that first presentation. This paper further explains the reasons for these changes which are primarily environmentally based and secondarily capital requirements related.

Jan 1, 1994

By George G. Reed

Approximately 200 samples of iron ores and other iron- bearing materials have been tested for amenability to treatment by the R-N process in bench scale laboratory work. Twelve large lots, ranging in size from 900 net tons to 18,500 net tons, but generally 3,000 to 4,000 tons each, have been processed in the R-N demonstration plant. The ores tested in the demonstration plant ranged from 27 to 70 percent iron content and gave excellent results. (1) The demonstration plant has a nominal daily capacity of 50 tons of high quality iron briquettes and has now operated for over five years. A continuing program of process improvement is carried on between demonstration on potential licenses ores. An important development is the complete elimination of any secondary products which, in the past (2,3,4,5), resulted from treatment of certain low-grade ores.

Jan 1, 1960

By C. C. Harvey

Based on resource studies in many developing countries, four categories of industrial clay resources are recognized as precursors to development strategies. Category I: High quality, high technology clays requiring major investment for large tonnage international markets. Category 2: Unique specialty clays requiring advanced technologies for small tonnage niche markets. Category 3: Lower technology, moderate quality clays, predominantly to supply local markets. Category 4: Low quality clays requiring little or no processing. Projects with Categories 1 and 2 clays require extended development times (green field to investment decisions) with significant pre-development investment, while projects with Categories 3 and 4 clays require shorter development timetables and lower levels of investment.

Jan 1, 1998

By W. G. Pariseau

Reliable stress measurement using hollow inclusion gauges and monitoring stress change using borehole stress meters and borehole deformation gauges in anisotropic rock remains a challenge for the rock mechanics community. In this regard, the complex variable method advanced in 1983 for deducing stress in anisotropic rock is flawed and software is privileged. Fortunately, advances in computer hardware and software now enable fast, reliable reduction of hollow inclusion stress measurement data for determining stress in anisotropic rock. Monitoring stress change in anisotropic rock poses a different challenge but is also subject to numerical analysis. Stress measurement using a hollow inclusion (HI) gauge such as the triaxial Australian HI is done in four steps: 1) drilling a measurement hole, 2) installation of an HI, 3) stress relief of the HI by overcoring, and 4) data reduction. The last step, data reduction, is the focus of this work. The process is well-known in linearly elastic, isotropic rock (Worotniki and Walton 1976, Duncan Fama and Pender 1980). However, in case of linearly elastic, anisotropic rock the requisite technology is not readily available. This situation is somewhat surprising because anisotropy is more often the rule rather than the exception, especially in the neighborhood of ore bodies. Rahn (1984) has pointed out the potential for significant errors with neglect of anisotropy and the adverse consequences for engineering design. Amadei (1984) has also pointed out the potential for errors with neglect of anisotropic rock properties in stress measurement. Worotniki (1993) cites other studies that indicate potential for serious errors when doing measurements in anisotropic rock. In both theoretical cases (isotropy and anisotropy), data reduction is essentially a composite of solutions to boundary value problems in linear elasticity. In the finite element approach, the analysis is a simulation of gauge hole drilling, installation and overcoring. Two important advantages with the finite element approach are a more faithful representation of the conditions of HI stress measurement than approximated in theory and the capability for handling rock whether isotropic, transversely isotropic or fully anisotropic

Mar 2, 2022

By Yongsik Jeong, Kwangmin Kim

Conventional tailings slurry contains a significant amount of water, and water management is key to ensuring the stability of a tailings storage facility (TSF). Simply reducing the water content in the slurry before discharging it from the mill could be an effective way to improve TSF water management. This study investigated the potential for using an environmentally friendly polymer as a new drag reduction agent (DRA) to reduce frictional pressure loss and also conserve water. It entailed conducting pipe loop tests to assess the polymer’s effect on pressure loss in tailings flow and then applying the test results to validate a numerical model using computational fluid dynamics (CFD). The model was also used to determine the polymer’s optimal concentrations at given solid concentrations and flow rates, its effect on energy efficiency for tailings transportation, and its potential for saving water. A case study for a mid-sized, hard-rock mine with a throughput of 50,000 t/day found that the solid concentration could be increased from 30 to 45% with no pressure loss by applying 1996 m3 of the polymer per day. Adding the polymer also resulted in water savings of 57,552 m3/day. The results of this study demonstrated the potential for using the new DRA not only to improve TSF stability but also to save water.

Jun 29, 2020

By R. D. Peterson

Autocad has become the standard graphics package for the mining industry as well as the general engineering profession. This paper discusses the evolution that mine planning has undergone and the trend toward compatibility with Autocad. It discusses the common use of Autocad in mine planning and systems modeling using a program called ICAMPS developed by Ohio Automation. As an example of its usefulness the use of the interactive ventilation network modeling capabilities are discussed specifically and are applied to mine planning at an operating trona mine. The ventilation analysis feature of the ICAMPS software works from Autocad drawing of the as-mined map and the projected mine layout. Using on-screen displays of these maps and the snap-on feature of Autocad, the planner designates nodes in the ventilation network, connects them into branches and selects branch characteristics from a side bar menu. The color coded ventilation network appears with the branch parameters alongside each branch. The software calculates the length of airways, computes the branch resistances where needed, converts the input into the required format and passes this information as input data along to the PENNVEN simulation program written by the Pennsylvania state University. Output is available in graphical as well as report format. The color coded graphs include pressures at the nodes and flow quantities on the branches. Since the networks come from the mine maps, the ventilation schematic displays are to scale and can be plotted separately or superimposed on the mine maps.

Jan 1, 1995

By R. J. Piniazkiewicz

Talc orebodies are mined in Asia, Australia, Europe, North America, and South America. Operators in North America must be efficient quality suppliers to thrive in a talc market in which many overseas suppliers have advantages such as lower hourly wages, shorter distances to ports, and less government regulation and intervention. Continuous improvement through teamwork and innovation is needed in the following areas to thrive amidst worldwide competition: 1) Maximization of the in-place value of ore. 2) Research and development to yield new processes and products. 3) Safe productivity. 4) Involvement in legislative processes. 5) Wellness programs to lower health care costs.

Jan 1, 1993

By J. Reyher, R. Bratton, G. Luttrell, B. Li

"Flotation is regarded as the best available method of upgrading minerals and coal fines. However, its efficiency deteriorates rapidly with decreasing particle size. Further, ultrafine concentrates are difficult to be dewatered economically, forcing companies to discard part of the ultrafine materials to impoundments. To overcome these problems, a new method of separating and simultaneously dewatering ultrafine particles has been developed. Following extensive laboratory-scale test work, the process, known as hydrophobic-hydrophilic separation (HHS), has been tested successfully in continuous operations at proof-of-concept (POC)- and pilot-scale tests. The results show that the HHS process is capable of producing high quality clean coal with high recoveries and low moistures. INTRODUCTION Coal preparation plants are designed with up to four parallel processing circuits for treating coarse (> 12 mm), intermediate (12x1 mm) small (1x0.15 mm), and fine (<0.15 mm) particles. The plus 0.15 mm fractions can be effectively cleaned efficiently with gravity separation methods (Wills, 2006). At present, the only commercially viable option for cleaning the finest fraction is froth flotation (Yoon et al., 1999). In flotation, air is dispersed in the form of small air bubbles in a tank in which coal fines are suspended. The small air bubbles selectively collect the hydrophobic coal particles and float to the surface, forming a froth phase which overflows into a launder. As is well known, ultrafine coal particles of less than 30-50 µm are difficult to be collected by the air bubbles, resulting in low recoveries. Furthermore, fine particle flotation suffers from low carrying capacities and poor selectivity due to entrainment problems. (Bethell et al., 2005; Luttrell et al., 2014). In addition, the froth products containing ultrafine coal are difficult to dewater. Mechanical dewatering in general becomes inefficient with decreasing particle size due to small cake porosity and high surface area, resulting in high moistures (Hucko et al., 1988). The cost often becomes prohibitive with particles of smaller than ~45 µm (Bethell et al., 2005). Moreover, the high-moisture products are difficult to handle and incur high shipping costs and lower thermal efficiencies (Honaker et al., 2013)"

Jan 1, 2016

By P. M. Brown

The Bureau of Mines, U. S. Department of the Interior, has developed a method of dewatering clay slurries based on flocculation by high-molecular-weight polymers and water removal from the formed flocs using a trommel or hydrosieve. The exchange ion on the clays affects their dewaterability. Metal ions in solution and on the exchange sites of smectite clays are known to act as Lewis acids. Recent work has determined that these ions can be titrated with high-molecular-weight polymers. The relative acidity of the exchange ion and the basicity of the polymer determined by the new method give insight into the dewatering mechanism.

Jan 1, 1988

By G. M. Bernard

An overview presentation of the fast-track start up of Cerro Colorado, a new copper heap leach project in Chile&apos;s Atacama&apos; desert. A brief explanation &apos;of location of the property, exploration history, geol-ogy, reserves and development are presented. The overview includes mining, crushing, agglomeration, and the solvent extraction-electrowinning recovery process. Challenges and requirements specific to heap leach systems will be addressed and analyzed. A detailed description will be given of the mobile heap leach conveying and stacking systems used in the building of heaps for on-and off-pad operations.

Jan 1, 1995

By R. C. Keaney

The metals industry is in complete chaos with mines being shut down, profits becoming non-existent, and continual losses to imports from other countries. Yet the raw material supplier to the glass industry has many opportunities to grow and to produce profits. Fortunately, the cost of most glass raw materials are low enough that competition from imports is not anywhere as critical as it is in the metal industries, such as copper, aluminum, lead, and others. But the glass raw material supplier must develop new products, both chemically and physically, to effectively compete in the future. The purpose of this paper is to point out generally where these opportunities exist and to suggest how they may be further developed. As the glass industry looks for energy saving materials, they look once again towards finer materials. A glass furnace is now approximately 40% efficient. Glass engineers are constantly striving for energy savings and it is well known that finer materials melt easier so that the manufacturer can operate his furnace either at lower temperatures for the same production or he can produce more material at the same temperature. The old 20 mesh sand specification is no longer sacred and as the mesh size for sand changes so do the specifications for all other raw materials used in the melting process. Highly instrumented glass furnaces can now measure quite accurately the energy needs to produce glass and can also measure the energy loss in each furnace. Glass technologists desire today a sand with a top size of 40 mesh while some would like to have the top at 60 mesh. This becomes more difficult to accomplish as a raw material supplier without .grinding. As you well know, grinding develops fines. Yet the same technologists will tell us that we can have nothing passing a 140 mesh screen. Therefore, we must develop processes which allows us to produce a finer screen size without increasing the amount of fines passing through the 140 mesh screen. To counteract this, different and changing industries are now demanding much finer products so possibly there will be markets for the fines which are currently separated out of the products. Methods that are practical and low cost must be found to develop different products with different screen specifications. What works for sand can be carried over to the other raw materials used in melting. Among the answers to finer products, of course, are pellets. Aglomeration or pelletizing has been looked at in the past and will be looked at in the future. Considerable work has been done in the glass container industry on this and must be carried out more extensively. By using aglomerated material or pellets, the glass producer will gain the benefits of melting fine materials without suffering from handling or dust problems. Pelletizing, particularly where using basic glass melting materials such as burned lime or sodium silicate, will not only produce a good pellets but will add desirable minerals to the glass batch.

Jan 1, 1986

Effective ground control in the gate entries, particularly in the tailgate travelways, is essential for safe longwall mining. Longwall pillars maintain gate entry stability and carry abutment loads. To answer the need for effective longwall pillar design, an empirical method called Analysis of Longwall Pillar Stability (ALPS) was proposed several years ago. Some recent research at the Bureau of Mines has focused on the refinement and verification of the ALPS method. ALPS was originally developed from field studies in which multiple stressmeters were installed in longwall pillars and monitored during mining. Several new field studies have now been incorporated into the ALPS data base. The field measurements have&apos; been used to verify formulas for predicting abutment strength and pillar loads, and to develop an expression for the distribution of the abutment load.

Jan 1, 1989

By V. M. Torres

An empirical correlation to detennine laboratory mill grinding time has been developed. Grinding samples to 90 ± 5# below 147 micrometers was required for a flotation testwork at Companhia Vale do Rio Doce (CVRD) Research Center. The initial samples were all below 1 mm in size with different size distributions and work indices (Wi) ranging from 13 to 23 kWh/st. Grinding curves were determined for some initial samples. A correlation was developed between percent retained on 147 micrometers at a standard time and the time required to grind each sample to the required size. This correlation was then used to grind all samples, based on the preliminary grinding model. Finally, a statistical analysis with the size distribution of all samples was performed. The success of using the correlation was confirmed and an equation was determined using the data set.

Jan 1, 1996

By M. Yekeler

The critical surface tension of wetting values (Ye) of realgar (AsS), talc [Mg3si401o (OH) 2]&apos; stibnite (Sb2S3), and sulfur (S) were determined by flotation in the absence of conventional flotation collectors as 38.7, 38.0, 35.5, and 30.0 dyne/cm, respectively. The surface tensions of flotation media were arranged by methanol. Separation of binary mixtures of these minerals was performed exploiting their Ye differences-which form the basis of the "ganuna flotation process". One step flotation test showed that sulfur floats preferentially from its mixtures with realgar and stibnite at recoveries of 73.6 and 70.7 % and grades of 81.7 and 91.2 %, respectively. The separation of stibnite from realgar gave a recovery of 4.1 % and a grade of 41.2 % for stibnite, indicate that a minimal Ye difference of 3.6±0.2 dyne/cm is essential for such separation when conventional flotation reagents are not used. This paper presents data and describes the approach employed in these separations.

Jan 1, 1994

By CHENCHEN SUN, GUOPING LUO, GUOCHENG ZHANG

Preparation of briquettes by adding CaF2 reagent into the Australian iron ore powder. The structure and morphology of iron ore briquettes during various reduction stages (i.e., Fe2O3→Fe3O4, Fe3O4→FeO, and FeO→Fe) were observed via an ore microscope and scanning electron microscopy. The results showed that CaF2 reacted with SiO2 to form CaO and SiF4 gas during the roasting process. The reduction swelling index decreased from 12.36 to 8.83% when the CaF2 content in the briquettes increased due to CaF2-mediated refinement of the hematite grains during the first stage of the reduction process. Lattice distortion resulting from the presence of Ca2+ in the FeO lattice during the second stage of the reduction process, coupled with an increase in the porosity of the iron ore briquettes and the formation of a low-melting-point slag phase, promoted the anisotropic growth of FeO lamellar crystals, which resulted in an increase in the reduction swelling index from 4.27 to 7.36%. During the third stage of the reduction process, the growth of iron whiskers was promoted by wüstite (FeO) lattice distortion caused by a solid solution of Ca2+ in the FeO lattice; the reduction swelling index increased from 15.61 to 24.72%, resulting in the catastrophic swelling of the iron ore briquettes.

May 27, 2021

By C. D. Litton

This paper describes two new gas diagnostic techniques which have been used successfully to determine: 1) the combustion status of underground mines which have been sealed due to fire (Littol1 Ratio); and 2) the location of fires in abandoned, underground mines or waste banks (Kim Ratio). The Litton Ratio makes use of the rate of change of CO, calculated on both an air-free and methane-free basis, from mine gas samples and compares these values with those expected from a normal, combustion-free environment. The Kim Ratio uses the concentrations of total hydrocarbons, C2 ?C5, less the methane, to arrive at ratio values which increase as combustion intensity increases. The details of these two new techniques, their application to real situations, and their limitations will be discussed.

Jan 1, 1989

By A. Haghighat

The Missouri University of Science and Technology?s (Missouri S&T) Experimental Mine is a teaching and research facility which has been excavated in limestone by mining engineering students over almost 100 years. The mine is currently being extended to a second level. Available fans for ventilation are two surface fans of 24 kW and two underground booster fans of 12 kW. The design of a ventilation network in conjunction with multi surface fans and booster fans entails a complex procedure. Ventsim Visual software modeling has been used for network analysis to determine the optimum surface and booster fans locations, blade settings, and speeds. Both natural and mechanical induced ventilation pressures have been taken into account. Three working faces on each level have been designated as target points that minimum air quantities are required. The model has been calibrated against a pressure and quantity survey. Design of ductwork, door/stopping positions and different fans characteristics have been examined. The optimum flow rate at identified working faces, efficiency and minimum energy losses and annual network power cost determine the best scenario. The optimum design has been determined for the ventilation network for the next 100 years. The optimum flow rate across working faces is the key criterion selected.

Feb 23, 2014

By K. Osseo-Asare

LIX63 in combination with DNNS selectively extracts nickel and/or cobalt from acidic leach liquors with pH values as low as 1.0. Nickel/cobalt and cobalt/nickel selectivities are achieved by varying the relative concentrations of LIX63 and DNNS. Increasing LIX63 concentration retards both extraction and strip-ping rates while DNNS has the opposite effect. Slope analyses of equilibrium data indicate that both LIX63 and DNNS are present in the extracted complexes. Examples of possible flowsheets are presented.

Jan 1, 1978