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By C. W. Schultz

Earlier publications from The University of Alabama have indicated that column flotation performance is improved when operating at low pulp levels and when the feed is directed into the froth phase. To validate these early observations a series of tests were performed in which the position of the feed entry to the column and the pulp-froth interface were systematically varied. The optimum grade-recovery relationship was achieved with high feed entry (WA) of column height) and very low pulp levels (<10% of column height). The position of the pulp-froth interface appears to be the more critical variable. When operating in this mode (1. e. at low pulp levels) column flotation becomes. in reality. a froth separation process.

Jan 1, 1991

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the National Institute for Occupational Safety and Health and a cooperating trona mine in the Green River basin of Wyoming, USA. The mine operation uses the longwall mining method in trona bed 17, a commonly mined unit in the region. The longwall face length is 228 m (750 ft), and caving on the face occurred up to the back of the longwall shields. The mine is ventilated using a main blowing fan and a bleeder shaft. For this study, sulfur hexafluoride (SF6) tracer gas was released in two separate monitoring experiments. For the first experiment, tracer gas was released on the face, this test focused on airflow along the longwall face of the active panel. Face test showed the airflow patterns to be more complex than just head-to-tail flow in the main ventilation air stream on the active panel. For the second experiment, tracer gas was released 2 crosscuts inby the face on the headgate side, this test focused on gas transport in the mined-out portion of the same active panel. Gob test showed a pathway of movement through the front of the active panel gob that moved outby from the tailgate corner. The primary pathway of tracer gas movement in the active panel gob was towards the headgate and tailgate bleeders and out of a bleeder shaft. The rate of movement towards the back of the gob was measured to be 0.19 m/s (37 fpm).

By Barton G. Stone

"Sampling is the process of taking a small portion of an article such that the consistency of the portion shall be representative of the whole," (Baxter and Parks, 1939)."An orebody is a mixture of minerals in proportions that vary in different parts of the mass. As a consequence, the proportion of contained metals also varies from place to place. Therefore, a single sample taken in any particular place would not contain the same proportion of metals as does the orebody as a whole except by a highly improbable coincidence."The probable error, which would be very large if only one sample were taken, decreases with the number of samples, but it never disappears completely unless the samples are so numerous and so large that their aggregate is equal to the orebody itself, in which case the orebody would be completely used up in the process of sampling."Since carrying sampling to such an extreme would defeat its own purpose, some probable error is always present in actual cases and the practical objective is to reduce this probable error to allowable limits. This means balancing the number of samples against the desired accuracy; if there are not enough samples the result is unreliable; if there are too many, the time and expense of taking them is excessive." (McKinstry, et al., 1948).In an actual orebody, the accuracy of sampling depends not only on the number of samples but also on their proper distribution throughout the orebody, for it would obviously be incorrect to take all of the samples either in a rich part or a lean part. Therefore, it is important to select the places in such a way that all parts of the orebody will be represented."

Jan 1, 2014

By B. Das

Most coals are susceptible to spontaneous heating which in turn creates problem to mining, storage and transportation of coal. It is impossible in actual practice o eliminate spontaneous heating but spontaneous combustion can effecively be controlled through a clear understanding of its mechanism and the factors affecting it. There are altogether six stages in the process of spontaneous combustion. This includes the water adsorption stage and six oxidation stages: chemi-sorption (upto 70°C), decomposition of peroxygens (70°C-150°C), oxy-coal formation (150°C-230°C), combustion initiation (230°C) and active combustion (> 230°C). Heat is produced in all these stages. On the other hand heat is also dissipated so that some equilibrium temperature is reached. If this temperature exceeds a certain critical value (generally about 70°C), coal oxidation may advance to spontaneous combustion. The major factors influencing spontaneous combustion of coal are: coal rank, maceral composition,, water, mineral matter, joints and fissures, seam depth and thickness, mine Layout, method of ventilation, etc. Susceptibility is high for low rank coals and generally decreases with increase in rank. Of the macerals, the exinites are generally most susceptible, the inertinites least and the vitrinites somewhere in between. Water plays a major role on the spontaneous heating of coal, assisting in someways and inhibiting in other. Unrecovered coal in the gob (generally in thick seams) is a major source of fire hazards and this is specially important in shallow mine. Proper design of mine ventilation system can substantially reduce the risk of mine fire. Panel layout and load transfer can affect the development of induced cracks which in turn influence spontaneous heating. Finally, the difference between the spontaneous heating of coal in a seam and that in storage or transportation is mainly due to the change in moistured content, air circulation through the coal and coal fragmentation. These aspects have been analyzed in this paper with a view o reducing the risk of spontaneous combustion.

Jan 1, 1986

By Hasan Nizamoğlu, M. Deniz Turan, MÜCEVHER TURAN, RAMAZAN ORHAN

Tailings (flotation waste) that is formed during copper production may be considered in the class of valuable wastes due to the amount of copper it contains. Owing to the decreasing grade values in copper ores, utilization of wastes such as tailings that carry certain amounts of copper as secondary sources has become a necessity in both the economic and environmental sense. This study investigated the usage conditions of five different ammonia salts as leaching reactants for the purpose of selective extraction of copper from tailings. For this purpose, the effects of parameters such as leaching temperature and leaching time were examined at different concentrations of ammonium hydroxide, ammonium carbonate, ammonium nitrate, ammonium chloride, and ammonium persulfate. The copper extraction efficiency in the case of using the aforementioned salts by themselves were listed as (NH4)2CO3 (73%) > (NH4)2S2O8 (69%) > NH4OH (64%) > NH4Cl (42%) > NH4NO3 (40%). The highest copper extraction efficiency was obtained in the leaching process that was conducted with the solutions obtained by mixing ammonia salts in the best conditions. Accordingly, as a result of 6 h of leaching at 30 °C in the presence of 22.5% NH4OH and 100 g/L (NH4)2S2O8, 91.47%of the copper was transferred into the

Jun 3, 2020

By Rambabu Pothina, MELO EDUARDO PIMENTA DE, Rajive Ganguli

 The mining industry is home to a mass of sensor-generated data that are critical to real-time and long-term optimization. This heavy reliance on sensor data has resulted in an undesirable development. The industry is reluctant to verify the accuracy of sensors as it would mean shutting down important processes. Sensors are typically calibrated once a year, if at all. Errors in sensors go undetected until the next calibration or until errors are so gross as to be obvious

By Douglas W. Barr

If some of you have been through the long hot summer in the southwest, you may find it refreshing to turn your thoughts to the wintertime problems of mineral processing in the northern climates. The purpose of this paper is to point out some of the ways in which heat is gained or lost in the tailing basin operation and the problems that can result if too much heat is lost.

Jan 1, 1980

By Scott O’Brien, Richard Williams, Camilo I. Mejias, Elias Godoy, Javier Sierra

High-rate thickeners play a critical role in tailings management by enhancing water recovery and increasing solids concentration. However, these units face operational instability due to fluctuations in feed solids, flow rate, and flocculant response typically managed in manual mode with delayed corrective actions. This work presents an adaptive automatic control algorithm designed for dynamic thickening environments. The algorithm integrates real-time measurements of feed density, rake torque, bed level, and turbidity (overflow), optimizing the underflow slurry density while minimizing suspended solids in the overflow. The proposed control strategy is modular, simple, scalable, and applicable to both existing and new thickening systems, offering a robust alternative to manual operation in increasingly demanding metallurgical environments.

Feb 22, 2026

By Dennis C. Parker

The Porters Creek clay is mined for its absorbent properties. The formation is part of the Upper Mississippi embayment and is recognized in Alabama, Mississippi, Tennessee, Kentucky, Illinois, and southeast Missouri. Major minerals in order of abundance are Montmorillonite, Quartz, Illite, Kaolinite, and Chlorite. Mining consists of open pit operation utilizing track loaders or scraper. The clay is dried or hardened in rotary kilns and crushed to size by roll crushers. The clay granules are sized and air classified prior to storage for shipment or packaging. Granules are sold for pet absorbents, oil absorbents, anti-skid material, fertilizer, and pesticide carriers.

Jan 1, 1979

By E. O. Strahl

In the search for economic mineral deposits, the need for efficient mineral or chemical assays is of prime importance. Costly analytical methods and long delays in obtaining assay results severely limit the effectiveness of an exploration program. The assay problem becomes acute once a potential ore body is located and large numbers of samples are generated in close interval drilling programs. In order to avoid the delays and high costs of extensive assays, the exploration geologist or mining engineer is likely to be required to curtail his drilling program, composite samples, or restrict the required analyses to a limited number of critical elements. As a result, the definition of the potential ore body may be less than needed for final economic evaluation. The assay requirements for bauxite exploration usually involve a considerable number of total elemental and empirical analysis. Since the Bayer process for extracting alumina from bauxite involves the selective dissolution and reaction of specific minerals from the bauxite, a direct chemical analysis for elemental composition yields only a portion of the data required to effectively describe the potential economic value of ore body or deposit. To fully characterize the economic value of a bauxite requires digestion, mud separation and mud settling tests under conditions approximating a commercial Bayer plant. A close approximation of the process behavior of a bauxite also can be calculated from a combination of the chemical and mineralogical analyses. By determining the elemental chemistry, mineralogy, and Bayer plant processing characteristics of a few samples of a given bauxite, correlations can be derived that permit defining a bauxite in terms of a given set of process conditions.

Jan 1, 1977

By B. Hines

Grinding efficiency in a vertical stirred mill is affected by a wide range of process and mill configuration variables. Of these, the media fill, size, and intrinsic density have a significant effect on power draw and grinding performance. Media-related factors that influence grinding performance include, e.g.,a higher media filling providing additional particle breakage sites, or a lower bead density decreasing the running torque at a given media filling. It has been estimated that the grinding media can cause up to a 30% change in the specific energy required to grind. FLSmidth has generally recommended that the intrinsic density (specific gravity) of the grinding media be more than triple the slurry density. This density difference helps to ensure that sufficient stress intensity is generated in the mill to provide particle breakage. It also reduces the chance of media ?float? if there is a spike in either slurry density or slurry flow rate. The VXPmills have historically operated at slurry density values between 1.2 and 1.5 kg/L, which translates to nominal bead intrinsic density range between 3.6 and 4.5 kg/L. The current trend towards regrinding bulk flotation concentrates to even finer sizes, to improve recoveries of fine grained minerals, has provided motivation to consider closed-circuit operation of stirred media mills. The slurry density in this application is typically higher than in open-circuit operation due to the higher percent solids in cyclone underflows. An additional effect is that closed-circuit operation increases the potential for media float due to higher flow rates as slurry is recycled to the mill. The normal progression in extending the operating range of existing equipment is to carry out laboratory testing before pilot-scale and plant-scale trials. The results presented in this paper examine the media density to slurry density ratio and its effect on grinding performance.

Feb 23, 2014

By N. Moelans, I. Bellemans, K. Verbeken

Metallic droplets can remain attached to solid particles within liquid slags, resulting in production losses in several movement of solid particles in the liquid slag in a system, considering the attachment of liquid metal droplets to solid slag and on the resulting microstructures is investigated as a function of the velocity of the particles. For all wetting For the amount of metal attached to the particle, a clear trade-off was found between the speed of motion of the solid particle and the wetting regime.

By Jon Bowler

Daw Mill Colliery, UK Coal, near Coventry in England, mines the Warwickshire Thick Seam at 800 m/2500 ft depth using longwall retreat with gateroads supported by rockbolts. Over the last eight years the mine has worked longer and wider panels with extraction heights of over 5 m. Recently the mine has experienced high deformation conditions principally from the rib sides resulting in operational issues and production delays. Investigation of rib deformation was undertaken using new inspection and measurement techniques, including systematic laser surveying, and improved rib support consumables were developed and introduced. A new rib trussing system using textile webbing has proved very successful.. A rib support management system was also developed and introduced for face retreat. This allowed rib support to be more effectively managed both for production and safety. For the current developments, new 28-mm-diameter roof and rib bolt systems have been introduced and rib bolt length has been increased to 3 m, with the aim of achieving gateroad stability over the life of the panel. Significant reductions in roof and rib deformation have been confirmed by the latest monitoring results. These ground control innovations are allowing Daw Mill?s potential to be realised. Production from 302?s face in 2008 set new UK and European records. However the support enhancement process continues and further innovations are planned.

Jan 1, 2009

By P. Clifford

FIPR-sponsored research will playa critical role in enhancing the competitiveness of the Florida phosphate industry as ore grade declines and environmental restrictions tighten. FIPR&apos;s program seeks to improve surface mining and pipeline transportation while reducing the energy cost for pumping phosphate matrix. The development of a reliable on-line analyzer and a modern process control strategy will result in improved processing efficiency. Significant improvement in overall efficiency will also be realized as the industry adopts column flotation technology. Economic acidulation of high-Insol rock will allow the industry to adopt simplified flotation flowsheets thereby reducing operating costs. Various applications of phosphogypsum would save the industry millions of dollars in constructing and closing gypsum stacks.

Jan 1, 1998

By G. Mei

"This study explores froth flotation and selective flocculation methods to recycle waste phosphors containing several rare earth elements, namely, yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb). The effects of the presence or absence of collector and of flocculant and their dosages, as well as the pH, were investigated. Reverse flotation resulted in concentrates with grade of 27.03 percent and recovery rate of 71.36 percent, while flocculation resulted in concentrates with grade of 31.43 percent and recovery rate of 91.28 percent. The flotation and flocculation behaviors were further analyzed by X-ray diffraction analysis, zeta potential measurements, particle size distribution and other methods. The successful separation of rare earth minerals by flotation was attributed to the selective adsorption of the collector onto quartz, making it particularly recoverable by reverse flotation so as to be separated from the valuable materials. The analysis of the particle aggregation process indicated that its better flocculation performance was due to the selective adsorption of flocculants onto the unwanted materials, enlarging the flocculant sizes by forming aggregations and facilitating the separation of rare earth minerals from waste materials based on different settling rates. IntroductionBecause waste phosphors pose the problems of heavy environmental burden and high risk to human health (Hu and Cheng, 2012) as a result of containing heavy metals such as mercury and manganese (He et al., 2006; Lucas and Emery, 2006), they have received added attention as urban mining resources for extracting rare earth elements (REEs) like yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb).At present, chemical processes such as acid leaching, alkali fusion, roasting and extraction are the primary methods for recovering REEs from waste phosphors (De Michelis et al., 2011; Li et al., 2012; Li, 2010). With these strategies, phosphors can be effectively decomposed and their REEs extracted. After the removal of impurities, the REEs can be efficiently precipitated by adding an H2C2O4 solution (Porob et al., 2012). Although relatively high recovery rates are achieved, those processes entail high energy consumption and can cause severe environmental pollution."

Jan 1, 2017

By S. K. Kawatra, J. E. D. McDonald, S. C. Roache

"The formation of geopolymers from mine tailings using cold-bonding processes is known to be possible. Numerous cold-bonding methods exist, but the hydrothermal processes involving high temperatures and pressures in the presence of steam have been found to be the most ideal. This paper presents the results of successful preliminary studies to apply hydrothermal bonding processes to mine tailings agglomerates. Particle-size analysis revealed the particle size of the tailings waste to be 80 percent passing at 35 µm. The compressive strengths of the tailings pellets were shown to increase with time in the curing vessel, closely approaching the 400 lbf of standard iron ore concentrate pellets. These strengths are sufficient to allow use of the tailings pellets as aggregate materials for asphalt and cement. Additional applications may be possible, including reprocessing to extract more valuable materials and usage as agglomerated road-bed materials, backfills for building foundations, and replacements for sand and lime in cement.IntroductionMine tailings are a waste byproduct of ore concentration and are available in large quantities across the world. Despite their abundance, they have received little attention or consideration for beneficial use. One reason is that the chemical nature of the material is not well known. Another factor that has hindered direct usage is the fine particle size. This raises the questions: what is the composition of the tailings, and how can such fine solids be beneficially used? Because the mining industry produces concentrates, the tailings may be treated as concentrates and processed in the same fashion, but it would be inefficient to consider full sintering or induration conditions for materials that have little ore content. To achieve sustainable operation, the development of technologies to use these tailings is necessary. Mine tailings should not be considered waste, and an “out of sight, out of mind” mentality does not represent a sustainable solution for the future.One iron ore mine in Michigan is estimated to have accumulated more than 400 million metric tons of tailings during its last 30 years of operation, with an additional 180 million metric tons accumulated before the ore body is depleted. These mine tailings currently have no practical use, largely due to a scarcity of knowledge of their true physiochemical nature. It is thought that lack of quality control of the waste material prevents its use, but variability in the unprocessed ore prevents a consistent waste stream composition. The fact that the tailings are available in such great quantities makes them an extremely attractive resource. However, developing a sustainable, low-cost means of repurposing the mine tailings waste as a construction material may only be completed once the tailings are physically and chemically understood. Due to the high silica content of the material studied, cold bonding was determined to be the most viable method for processing the tailings into a usable product."

Jan 1, 2016

By William F. Abercrombie

The role of the laboratory is described in relation to the prospecting and exploration of kaolin clays. Test methods used to evaluate crude ore samples of kaolin clay for commercial consideration are reviewed. A background of the kaolin mineral and known means of prospecting this mineral are presented. Common analytical methods are discussed with special emphasis on those in use today.

Jan 1, 1982

By A. Moergeli, Philip Sander, John J. Reilly

"Estimating and managing the costs of complex infrastructure projects – in the planning/design and construction phases, for both owners and contractors – has been a challenge for decades. The more complex and technologically advanced the project, the greater the uncertainty, including potential risks that are important to owners and contractors, such as:• Cost risks to owners – meeting budget and schedule, maintaining public credibility.• Cost risks to contractors – profit, consequences of loss, impacts to reputation/future work.This concern has been addressed in various ways by the underground construction industry for some time (Reilly, 2001). In particular, while significant advances have been made in cost estimating for the planning and design phases (Reilly et al., 2004), that are important to agencies and political decision-makers, it is not apparent that these advances have been widely adopted for construction cost estimates. The reasons for this may relate to lowbid considerations – any method that tends to increase the contractor’s cost estimate, by including risk or likely costs, could lead to an erosion of the contractor’s competitive position – if others are not similarly required to include such costs.Different cost estimating methods produce different levels of information. Specifically, there is a large difference in the character and depth of information if a deterministic (quantities times price plus a contingency) and risk-based cost methods are used. It is this difference in character and depth of information that is the reason that risk-based cost estimating has potential value for owners and contractors. Figure 1 presents hypothetical cost results from deterministic and risk-based methods and illustrates some of these differences.In Fig. 1, the results for deterministic and risk-based cost estimates are given related to the potential profit or loss for a typical project. As is evident in this example, there is significant potential for costs to be realized that are higher than the proposal/bid value estimated using a deterministic approach, with a 15 percent probability of a loss. There is a 30 percent probability that the project will have a reduced profit. There is a 55 percent probability that the project will return a good profit. Using a risk-based approach, it is possible to better recognize this potential outcome in the bid phase and, as a consequence, develop a strategy to:"

Apr 1, 2016

By M. Fan

Coal has in general a wide range of density from minus 1.3 to plus 2.0 g/cm3 because of its variations in purity, rank, and porosity, etc. The coal density has great impact on froth flotation performance, but much less attention has been paid to particle density than particle size. Our previous research results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different density fractions (minus 1.3, 1.3-1.4, 1.4-1.5, 1.5-1.6, 1.6-1.8, 1.8-2.0, 2.2-2.2, and plus 2.2 g/cm3) of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50-mm-inside-diameter column, and a 152-mm-inside-diameter column. It was found that nanobubble has the biggest impact on the flotation performance of 1.4-1.8 g/cm3 medium-density coal particles.

Feb 23, 2014

By Felicia F. Peng

The manganese removal from aqueous solution containing high Mn2+ concentration by adsorption and oxidation was studied using manganese oxide particles as the adsorbent. The operating parameters including pH, flow rate, initial manganese concentrations, and oxidant dosage affect the performance of Mn2+ removal were evaluated in a laboratory packed column. In the multi-column adsorption tests, each additional column doubled the time for complete manganese removal. No further decrease of pH was also observed once it was lowered to pH 4.5 to 5. This finding implied the possibility of complete high manganese removal without further pH adjustment during adsorption. Oxidation of Mn2+ by dissolved oxygen was found to be insignificant for manganese removal for high Mn2+ concentration. Adsorption was the predominated mechanism involved with manganese removal. Extremely low H+/Mn2+ stoichiometry compared to the reported values was measured. These low values suggested that different adsorption mechanisms such as chemisorption other than H+/Mn2+ ion exchange might play an important role at low pH. This paper presents the quantity and explanation of the results obtained for the mechanism of adsorption and oxidation of high concentration manganese on the manganese ore particles.

Jan 1, 1997