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By P. Moran

A promising and increasingly popular tailings management strategy is to place cemented tailings underground as backfill. The placement of cemented tailings results in enhanced geotechnical stability and a purportedly more geochemically stable tailings form with lower leaching potential. Conventional subaerial tailings management can negatively affect water quality if weathering causes acid rock drainage and metal leaching (ARD/ML) to occur, whereas cemented tailings can limit leaching via porosity and permeability reductions and contribute alkalinity to limit the potential for ARD/ML. Cemented tailings backfill appears to be better, but how can this advantage be proven? Currently, cemented tailings backfill is utilized at mining operations internationally, but there is limited guidance on performing geochemical characterization and associated evaluation of the potential impacts to water quality. As a result, various approaches to simulating the leaching behavior of cemented backfill have been utilized, including some methods that are unlikely to represent weathering under site-relevant conditions. American Society for Testing and Materials (ASTM) Standard Test Method C1308-08 is a diffusion testing method initially developed to assess constituent release rates from solid nuclear waste forms. ASTM C1308-08 uses intact cylinders that more closely represent actual backfill than methods that require crushing or size reduction. It is widely believed that leaching from actual cemented tailings is controlled by diffusion through small pores that exhibit limited exposed surface area, making diffusion testing particularly applicable to cemented tailings placement.

Feb 27, 2013

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By SIMON DIAZ-QUEZADA, HUMBERTO ESTAY

The heap-leaching process is widely used for recovering different metals. In Chile, copper production by heap leaching has been accounting for between 30 and 40 percent of annual copper production over the last 10 years. This level of production has been achieved through and supported by the use of a mathematical relation known as the leaching ratio (LR), which correlates operational parameters with metal extraction in a heap-leaching operation. In spite of the widespread industrial use of this relation, few scientific studies mention it. This disparity between industrial practice and scientific research could lead to operational decisions that lack substantial theoretical support and to scientific studies with limited industrial impact. This study describes the LR and its current uses and limitations.

By Deniz Akbay

The strength of rocks and soil is a crucial design parameter in engineering projects, and it can be determined through various test methods such as uniaxial compressive strength, tensile strength, and shear strength. The point load index test is a popular indirect test method for predicting the uniaxial compressive strength of rocks. However, the reliability of the point load index’s estimation of uniaxial compressive strength of rocks is questioned due to the wide range of coefficients that are used to predict uniaxial compressive strength of rocks using point load index values. Factors such as the shape and type of rock specimen, practitioner, and test apparatus used can affect the accuracy of the point load index test. This study investigated the effect of four different specimen shapes used in point load index test (diametral, axial, block, and irregular lump tests) in predicting the uniaxial compressive strength. The rock samples were tested using four test procedures which are called diametral, axial, block, and irregular lump tests. The results showed that the irregular lump test was the most accurate in predicting uniaxial compressive strength, with the highest correlation coefficients and lowest mean absolute percentage errors. The point load index test can be used as a reliable predictor of uniaxial compressive strength of rocks when the irregular lump test is preferred.

Oct 18, 2023

By J. Richard Kyle

The Pb-Zn ore bodies in the Pine Point district are localized in paleo-solution structures that developed as the result of post-middle Givetian subaerial exposure of the carbonate barrier complex. Sulfides are concentrated in transgressive pale-solution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character, one of which contained metals and the other reduced sulfur. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition. District and ore body metal distribution patterns may reflect the nature and movement of mineralizing fluids.

Jan 1, 1979

By C. E. Jordan

The U.S. Bureau of Mines investigated flotation hydrodynamics to improve the recovery of coarse phosphate. Fluid velocity profile measurements were used to characterize the hydrodynamics within commercial phosphate flotation cells and laboratory flotation cells. The effects of agitation, aeration, and pH on coarse phosphate recovery were measured in the laboratory flotation cells and correlated with the hydrodynamics measurements. Test results revealed that the agitation energy and aeration level had a significant effect upon flotation response. By optimizing these two parameters, 92 pct of the phosphate was recovered in a rougher flotation concentrate grading 28 pct P2O5?

Jan 1, 1994

By W. P. Barnett

In 1988, the U.S. Department of Energy's Pittsburgh Energy Technology Center identified three coal cleaning options for achieving flexible environmental control strategies aimed at reducing energy-related SO2 emissions. These are selective agglomeration, advanced froth flotation, and advanced cycloning. Each technology relies on maximum liberation of pyrite and other mineral matter through feed coal comminution to fine and ultrafine sizes. Research projects designed to expeditiously develop each of these technologies to the point of commercial viability were initiated. This paper will present the status of these projects and the application potential of each technology to coal beneficiation.

Jan 1, 1992

By R. Raitani

Five kaolin crudes from the state of Georgia in the U.S. were investigated for processability with chemically enhanced magnetic separation (CEMS) technologies developed by Cytec. The technologies used magnetic reagent alone or in conjunction with specialty chemicals to selectively agglomerate and magnetize the desired minerals (impurities) to be removed by the conventional magnetic separation equipment. All crudes indicated treatability using CEMS. Results indicated that CEMS technology could be applied to different kaolin crudes to obtain a product with titanium impurities less than 0.6% TiO2 from individual crudes. The features and benefits of the technologies were also reviewed.

Feb 1, 2012

By Diane Moody

I have been asked to give you the National Coal Association's (NCA) view of the future of the coal industry. However, before discussing the outlook for the future I would like to set the stage by taking a brief look at how the industry has changed over the last decade. In 1977 the coal industry was in the midst of a period of steady growth. Although most of the gains in the early and mid 1970's occurred in the west, the industry was still predominately eastern, with eastern production accounting for 76 percent of the 697 million total tons produced in 1977. The labor force was nearing a high - at over 220,000 workers, and the number of active mines was also at a decade high of over 6,000. Productivity on the other hand was at a low. The average miner produced 1.80 tons per hour, and labor relations were also at a low point. Projections for coal's future were very optimistic, mainly because of the unprecedented growth in coal use by the utility industry. In 1977 the 477 million tons of utility coal accounted for 68 percent of U.S. coal production, and the utility industry planned on 129,000 MW of new coal-fired capacity over the next decade. Consumption of metallurgical coal at coke plants was the second largest market at 78 million tons; the industrial and residential market consumed 70 million tons and exports were at 54 million tons. But in retrospect, a lot was happening in 1977 that signalled many changes in the coal industry: - Amendments to the Clean Air Act were passed, which required that utilities take an entirely different approach to meeting New Source Performance Standards at new plants, and required that standards be set for industrial boilers as well; - the Surface Mining and Reclamation Act became law; -electrical generation, despite the optimistic forecasts, was nearing the end of a period of close to five percent annual growth; -1977 ended and 1978 began with the longest coal strike in U.S. history. -crude oil imports in the U.S. reached an all time high as did both total consumption of petroleum products in the U.S. and oil consumption at utilities. The high level of oil imports set the stage for the oil price increases of 1979 and 1980 which resulted in an immediate increase in demand for coal, not only in the United States, but world wide. Labor strikes in Australia and Poland sent foreign buyers to the U.S. literally in droves, and quickly made the U.S. a force in the world steam coal market. The U.S. coal and transportation industries responded to this overwhelming potential demand for coal. In a very short time, the capability had been developed to mine and transport the 1.2 billion tons of coal that forecasters said would be needed by the mid 1980's. What was not anticipated was that the economic effects of sharply higher oil prices would dampen demand for energy, especially for electricity, as quickly as we have seen; that coal industries in other countries would respond as rapidly as the U.S. coal industry, and at a rate

Jan 1, 1988

By Z. Xu, Z. Li

Colloidal interactions play a critical role in mineral processing, including grinding, physical separation (particularly flotation), dewatering, and tailings management. Despite great energy input in comminution to liberate valuables from gangues, heterocoagulation between valuables and gangues would prevent the separation of valuables from gangues. On the other hand, selective coagulation/flocculation to increase the size of desired fine particles could enhance physical separation and dewatering, while dispersion is needed for fine grinding. To control the state of colloidal dispersions by creating favorable conditions, it is of paramount importance to study colloidal interactions in a relevant system and understand underlying mechanisms. This review summarizes recent advances in developing the-state-of-the-art techniques and novel methods of measuring colloidal forces, including atomic force microscope, surface force apparatus, zeta potential distribution measurement, quartz crystal microbalance with dissipation, and our recently developed integrated dynamic force apparatus. The basic principle of each technique was introduced first, followed by a summary of critical information derived for the relevant mineral processing systems. Finally, the pros and cons of each technique were discussed to emphasize the use of complementary techniques that assist in solving fundamental problems in mineral processing.

By McDonald E. Wrenn, Narayani P. Singh, Victor E. Archer, Ceno Saccomanno

Fourteen uranium miners' lungs from Colorado plateau were collected at autopsy and the concentrations of 238U, 234U and 230Th were determined by radiochemical procedures utilizing solvent extraction - alpha spectrometric techniques. The uranium and thorium isotopes are in near equilibrium with average concentrations of 238U, 234U and 230Th being 89.3, 95.2 and 91.1 pCi/kg respectively. The combined average radiation dose rate to lung from these three isotopes is about 24.2 mrad/year at death excluding the unmeasured contribution from the 226Ra and daughters. The average concentration of 230Th is about 65 times higher than the mean concentration of 230Th in lungs of non-miners dying at comparable ages from the same region.

Jan 1, 1981

By J. B. Yianatos, G. S. Dobby, J. A. Finch, A. R. Laplante, R. Espinosa-Gomez

The question is posed as to why columns typically have a collection zone 10 m high (H) by 1 m in diameter (D). Three geometry dependent factors are considered: degree of mixing, Np; volumetric bias rate, B; and volumetric gas rate, G. Increasing H:D decreased Np and B, which improves performance but decreases G, which causes the column to approach overloading. Taking typical column operating conditions, it is concluded that a collection zone H:D of 10:l is a reasonable compromise.

Jan 1, 1987

By M. H. Bolu

Since undergoing a major mill expansion in 1979, Canada Tungsten Mining Corporation Limited has successfully operated a somewhat unconventional rod mill/rod mill grinding circuit at its mill in Tungsten, N.W.T., Canada. The concentrator employs two rod mills in series, of unmatched size and horsepower, for production of feed to a gravity (tabling) circuit. Cyclones and screens are closed circuited with the secondary rod mill. Outlined in this paper are the rationale behind, and consequences of operation of this unusual grinding and classification configuration.

Jan 1, 1984

By H. Nazeri, T. G. Rozgonyi

Many industries when volumes of the solid materials are large invariably relay upon the gravity to induce solids to flow out of storage, through channels and reactors. In mining industry ore pass’s requirements to less energy (only gravity) have made them very popular both in underground and open pit mines. This paper discusses the major findings of research on 2D Discrete Element Method simulation of gravity flow of ore in ore passes. Results show that ore characteristics, ore pass configuration can significantly affect loads (static, dynamic) on the gate assembly and creation of hang-ups.

Jan 1, 2003

By NEHA PANDEY, Sunil Kumar Tripathy, ARIJIT BISWAS

Due to the growing market of Electric Vehicles (EVs), there is a rise in battery demand. Nickel can be used as a potential element in cathode for lithium-ion batteries. Nickel can provide thermal stability, high energy density, and conductivity in cathodes of lithium-ion batteries. Low-grade chromite overburden from Sukinda mines contains less than 1 wt% of nickel, which can be utilized to extract nickel. Recovery of nickel from such low-grade overburden can help in value addition. The present study provides deeper insight into the aspects of extraction of nickel product derivatives (NPDs), mainly mixed hydroxide product (MHP), through the hydrometallurgical route. The current study focuses on extracting nickel and cobalt from a mine overburden with 0.41% nickel with major silicate gangue. MHP can be processed further for nickel sulfate production, a potential raw material for cathodes in EV batteries. The study discusses a process flowsheet to recover nickel and cobalt from overburden through atmospheric leaching with pre-calcination. It is observed that the step of pre-calcination improves the effective recovery of nickel from overburden. The leaching reactions are effective at a temperature of 90 °C and 1 atmosphere pressure. The orthophosphoric acid was used as a lixiviant for the selective recovery of nickel and cobalt from overburden. Recovery of nickel and cobalt obtained at optimum conditions is 84.0% and 39.9%, respectively. The iron impurity in the leachate solution is 1.27%. It is concluded that the process with pre-calcination along with acid leaching is effective for extracting nickel and cobalt at atmospheric pressure.

Dec 28, 2023

By Sandeep Kumar Asarapalli, Sunil Kumar Bisoyi, Bhatu Kumar Pal

Spontaneous heating of coal is one of the major concerns in the coal mining industry. Hundreds of millions of tons of coal are lost each year because of spontaneous heating. If necessary arrangements are made, many fires due to spontaneous heating may be avoided. Therefore, protective measures have become essential to prevent coal from spontaneous combustion. A large amount of coal reserve can be saved by the assessment, suppression, and prediction of spontaneous heating of coal, which also helps in betterment and efficient coal production. The use of chemical retardants can act as inhibitors for the liability of coal toward spontaneous heating by increasing its ignition temperature, thereby, increasing its incubation period. The coal-chemical mixture can be used for whitewashing the exposed coal in galleries as it creates a layer between coal and oxygen in the atmosphere, delaying the oxidation process and ultimately inhibiting the spontaneous heating liability of coal. This work examines the effect of chemicals such as sodium chloride, calcium carbonate, potassium iodide, sodium nitrate, and potassium chloride on the spontaneous heating of a coal sample. Thereby, it suggests a better chemical for inhibiting the liability of coal toward spontaneous heating. The experimentation involves flammability temperature (FT), crossing point temperature (CPT), and differential thermal analysis (DTA). The ignition and oxidation temperatures were found from the above experimental methods for Lingaraj open-cast coal mine samples, with and without adding chemicals. The results are cross-checked and verified through DTA. Correlation analysis was carried out among the results obtained from CPT, DTA, and FT, and better chemical retardants that effectively inhibit coal’s tendency toward spontaneous heating were suggested.

Dec 23, 2023

By David Sugden

Intense, tropical weathering of Cretaceous-Tertiary sediments has developed similar laterites in distant areas of the Amazon Basin. In two areas, Trombetas and Paragomina s, bauxites of commercial potential arc found. The bauxite comes mostly from the lower horizon of the three component laterite. The laterite is overlain by a clay cover, possibly an integral part of the weathered profile. The laterites are found on almost flat plateaus with individual areas of up to 80km2. There is a close relationship between the morphology and the ldterites. The process of lateritization is allegedly Pliocence but probably continues today.

Jan 1, 1984

By Steven M. Puricelli

In recent times, smelter off gases treatment plants have become more efficient and environmentally friendly. Where in the past it was acceptable to process only high strength, treatable furnace gases, new smelters must now treat primary gases and abate dust and SO2 from secondary gases: Processing smelter gases can present some interesting challenges. Some equipment can see varying concentrations of sulfuric acid, up to the boiling point, with a periodic table of contaminates thrown in for good measure. Treating weaker secondary gases have, in the past, been cost prohibitive. Nowadays, new technology, like physical absorption or catalytic carbon, show promise for economically treating low strength secondary gases. Modem smelters do a much better job of treating the SO2 laden gases generated by the smelting process but significant challenges remain.

Jan 1, 1998

By Bijan Taheri, Behrouz Maghsodi, Monireh Heshami, Reza Kohan

A common problem recently encountered with the increase in the rate of input feed at Enrichment Plant 2 of the Sarcheshmeh Copper Complex is the loss of value to the tails, translating to lower recoveries. The feasibility of the direct transfer of part of the high-grade concentrate from rougher stages to an appropriate position along the circuit was studied, and two positions were proposed for direct transfer of the concentrate. One position was the feed flow into cleaner cells, and the other was the feed flow into the recleaner cell. The results indicated that transferring the concentrate from the first unit of the rougher stage to the feed flow into the cleaner cells was feasible, with no limitations, while the second position required the installation of a set of hydrocyclones. It was found that the transfer of concentrate to the proposed positions not only addressed the problem of limited cell capacity, resulting in debottlenecking of the circuit, but also improved metallurgical separation efficiency up to 1.4%.

By Walter Hoecker

The dissolution of gold in cyanide_ leaching has been we11 published with the genera1 acceptance that gold is oxidised by oxygen and stabilized by complexation with cyanide [1]. The dissolution of gold is essentially an electrochemical process. The rate of the anodic gold dissolution is controlled by the cyanide concentration. - (2) While the cathode reduction of oxygen is controlled by dissolved oxygen concentration - (3) There are a number of factors influencing the concentration of oxygen, and if 1owered substanth.lly will effect the efficiency of the leaching plant. These include: "' salinity "' temperature "'partial pressure "'oxygen consumption rate The use of pure oxygen for· cyanidation is only beneficial if oxygen is rate limiting, Conversely a slurry saturated with air (typically 5 - 8 ppm) may not be enough for maximum leach rate. The diagram below shows the maximum dissolved oxygen levels obtainable with pure oxygen and air. DISSOLVED OXYGEN (MAXIMUM) IN WATER At steady state, the rate of the cathodic reaction must equal the rate of the anodic reaction. Thus the rate of gold dissolution is dependent on both the· cyanide and oxygen concentrations. - (4) Using an average of Do/Den =· 1.5 [2] (where Do and Den are the oxygen and cyanide diffusion coefficients) the table below illustrates the maximum effective oxygen concentrations for given cyanide levels in clean water [3].

Jan 1, 1992