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By R. J. Roman

The results of column leaching tests on 3 different mixed oxide/sulfide ores from a Chilean deposit are presented. The 3 samples contained different ratios of oxide copper minerals to chalcocite and chalcopyrite. The results of the column leach tests are interpreted in light of the shrinking core model for coarse particle leaching. The copper recovery from the oxide minerals and the sulfide minerals each conforms to the shrinking core model with the total recovery equal to the weighted average of the individual minerals. The use of column test results to predict field heap leaching results using the multi-mineral shrinking core model is discussed.

Jan 1, 1993

By R. K. Mensah-Biney, M. T. Hepworth, K. J. Reid

The loading characteristics of gold-bromide species onto activated carbon were evaluated using a batch system. The overall loading of gold onto activated carbon was rapid for the first few hours, but it continued without cessation as a result of the reduction of gold. Therefore, conventional equilibrium considerations were not applicable. Although loading continued slowly after several days, an abnormally high, loading capacity value of 10-12 meq/g carbon (650-800 kg Au/t) could be attained in 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of (AuBr4)- species to the external surface to be reduced to metallic gold by carbon. Elution of gold from loaded carbon was feasible provided the carbon had not been loaded to high capacity values. If loading is carried to high levels, complete elution becomes impractical, and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon for gold-bromo species is discussed.

Jan 1, 1994

By R. L. Godfrey

The Custom Coals advanced coal cleaning plant will be designed with a unique blending of existing and new processes to produce two types of compliance coals: Carefree Coal? and Self-Scrubbing Coal?. Carefree Coal will be produced by cleaning the coal in a proprietary dense media cyclone circuit utilizing fine magnetite to remove up to 90 percent of the pyritic sulfur and correspondingly greatly reduce the ash. While may utilities can achieve full S02 reduction compliance with Carefree Coal, others face higher sulfur reduction requirements due to the higher sulfur content of their existing fuel supplies. For these circumstances, a patented Self-Scrubbing Coal will be produced by taking Carefree Coal and pelletizing limestone-based additives with the finest fraction of the clean coal. These technologies will enable over 150 billion tons of non-compliance U.S. coal reserves to meet compliance requirements.

Jan 1, 1995

By Nagashi Ogushi

Geochemical prospecting method using stream sediments, soils and rock chips has been tested to see the applicability for the typical Kuroko field in Japan. Three independent anomalies have been detected in maps being shown by grav densities of cells which are represented by the results of factor analysis as well as distribution of minor elements scaled in logarithm. A small vein type mineralization which has outcrops could be attributed to the origin of them whereas the one near the surface of known Kuroko deposit to a coincidence. The addition of drill core geochemistry is required to complete the interpretation.

Jan 1, 1982

By B. G. Stone

"INTRODUCTION “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 alone on the number of samples but also on proper distribution of them 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. “For those who cultivate land which is alike arid, heavy , and barren, and in which they sow seeds, do not make so great a harvest as those who cultivate a fertile and mellow soil and sow their grain in that. And since by far the greater number of miners are unskilled rather than skilled in the art, it follows that mining is a profitable occupation to very few men, and a source of loss to many more.” (Georgius Agricola page 5 Book 1 as translated by H.C. Hoover and Lou Henry Hoover, 1950)“It is evident that mining is very profitable to those who give it care and attention”"

Jan 1, 2015

By R. Q. Honaker

Recent research has shown that enhanced gravity separators provide the opportunity to effectively clean I mm x 37 micron coal. At Southern Illinois University, a detailed experimental program was performed on a continuous Falcon Concentrator, which was found to achieve separations at mass throughput capacity values in excess of 100 tonnes/hour. The apparent particle separation density for I mm x 73 micron coal was about 1.60 with relatively high efficiency (Ep = 0.12). Typical ash and sulfur rejection values of 85% and 70%, respectively, were achieved while recovering 85% of the combustible material. Metallurgical and efficiency data from the evaluation are presented in this publication.

Jan 1, 1998

By Alec G. Richardson, S. H. Chiang, Ralph W. Lai, McMahan L. Gray

The potential of coal cleaning by selective agglomeration was examined for a Pittsburgh seam bituminous coal using isooctane as an agglomerating liquid. The effects of particle size, pH, degree of mixing, and dosage of isooctane on the pyrite and mineral matter removal from finely ground coals were investigated. The role of shear-enhanced-hydrophobic-association in the flocculation of fine particles was examined. The degree of liberation of pyrite from coal at different grinds was examined using an automated petrographic image analyzer. The effect of dispersant on slurry rheology during grinding was studied. The results indicate that over 95 percent of the pyritic sulfur can be removed from the coal. Final products containing less than 0.9 percent ash at a combustible recovery in excess of 90 percent have been obtained with multiple stages of cleaning.

Jan 1, 1989

When solid pillar is not left to separate different mining levels in underground mine with high dip angle deposit, waste rock in the backfilled stope could be a safety hazard to future mining activities on levels above or below the backfill. Different backfill methods can be used to eliminate this hazard according to the deposit shape and mining method. Building concrete pillar in ore drift of each mining level is one of them. Concrete pillar had been constructed in underground mines based on operational experience. Little design literature and pillar performance data can be found. At Great Basin Gold Hollister Mine, over two thousand feet of concrete pillar had been constructed. The project started with engineering design which combined civil engineering concrete design and the specialties of underground construction. Time Domain Reflectometry technique was installed to monitor the pillar movement and concrete cylinder samples were collected and tested for quality control. Engineering design, underground construction, quality control and concrete pillar monitoring, as well as precious concrete mixing data from years of experience are fully covered in this paper to give a general frame of concrete pillar method.

Jan 1, 2010

By C. G. Anderson

The treatment of concentrates for the recovery of the precious metals imposes many processing and environmental challenges. Hydrometallurgical technology for recovery of values from refractory precious metal materials has been developed at Sunshine Mining and Refining Company. Historically, conventional pyrometallurgical methods have been used for to recover values from refractory precious metal materials. However, enhanced environmental awareness has worked to constrain typical refractory material processing methods. This hinders and limits the ability of established smelting or roasting technologies to fill the needs of new sources of refractory materials. An alternative is to treat refractory precious metal bearing materials by hydro metallurgical techniques. These methods are considered more environmentally appropriate since they do not produce gaseous pollutants like sulfur dioxide. Industrially, Sunshine Mining and Refining Company employs hydrometallurgical technology to process refractory precious metal materials. The Sunshine antimony leach uses a mixture of sulfur and caustic under ambient pressure and boiling conditions. The Sunshine oxidation leach uses a mixture of sulfuric acid and a minimal amount of sodium nitrite under relatively mild oxygen pressure and temperature conditions. These conditions result in a nitrogen species catalyzed sulfuric acid pressure leach. Since hydrometallurgical technologies provide industrially proven processing options for many types of refractory precious metal containing materials, their usage should be considered. Ample work has been conducted to prove the effectiveness of Sunshine refractory processing technologies on various materials. This has included platinum group metal materials, refractory gold concentrates, silver materials and indium materials. In some cases, complete process flowsheets have been designed to recover both base and precious metals from these materials and to treat the generated waste streams in environmentally sound manners.

Jan 1, 1996

An AFM has been applied to study in situ the adsorption of oleic acid on fluorite in aqueous solutions. The AFM images show that fluorite surface becomes smoother with the adsorption of 7 × 10-5 M oleic acid solution at pH 9. Force measurement shows that fluorite is strongly positively charged in water at pH 6, suggesting a neglectable surface carbonation of fluorite. The adsorption of oleic acid at pH 9 renders fluorite more and more negatively charged. The surface morphology change of fluorite as shown by the AFM images suggests that oleic acid chemisorbs on fluorite at pH 9. Increasing temperature can help increase the adsorption of oleic acid on fluorite. It may also improve the lateral polymerization of unsaturated oleic acid on fluorite as suggested by the smoother mineral surface in oleic acid solutions at an elevated temperature.

Feb 23, 2014

By J. D. McKay

Flotation columns have been readily accepted for use in most sulfide flotation plants; however, recently columns are being used in many other areas. Recent improvements in design methodologies have overcome many operating problems and led to improvements in metallurgy. In addition, physical improvements in column design have simplified their operation while leading to better control. The Turbo-Air External Bubble Generator has provided a method for bubble size control and variation in air holdup and carrying capacity. These have enabled commercial operations to improve grades and recoveries by optimizing performance.

Jan 1, 1990

By M. Misra

It is estimated that the volume of low -level and intermediate level contaminants present in the soil at different DOE sites is of the order of several million cubic feet. The existing remediation scheme is containerization followed by burial in Land Disposal Facilities (LDF's) which is economically unattractive warranting the need to develop alternate remediation routes. One such route is the physical separation based volume reduction approach to removing a MINIMUM AMOUNT OF CLEAN SOIL with the radioactive particles, reducing the amount of material that requires disposal. The purpose of this study was to evaluate and test the feasibility of using physical beneficiation techniques for removal of contaminants from soil. The performance criterion was to recover at least 80% of the activity in 20% or less of the original contaminated soil volume. Four different radioactively contaminated (primarily uranium and plutonium) soils from DoE sites namely LANL, INEL, Fernald Plant 1 Storage Pad (ID-B) and Mound soils were tested using gravity, magnetic, gravo-magnetic, hydrocyclonic and flotation devices. The paper is divided into the two sections. The first section presents the overview of the Heavy Metals in Contaminated Soil Treatability Project conducted at the University of Nevada, Reno (UNR) describing the salient features of a state-of-the art Soil Washing Laboratory and the technology equipments used in the test program. The second section describes the soil characterization and typical volume reduction results obtained from the UNR tests. Among the physical separation processes, only flotation processes passed the performance criterion. For the LANL and INEL soils where the contamination was contained in coarse particle size, it was possible to recover more than 80% of the activity in less than 10-20% of the original volume of the soil thus rendering 80-90% of the soil "clean". For Fernald and Mound soils where contamination was of colloidal nature, flotation based processes showed encouraging results and are recommended for further studies.

Jan 1, 1995

By T. J. Cox

The Red River is located within the Sangre De Cristo Mountain Range in northern New Mexico. An approximate 12-mile segment of the river from the town of Red River to the village of Questa (Questa) includes several hydrothermal alteration zones. Alteration ?scars? formed as a result of rapid chemical weathering and physical erosion of pyrite-rich hydrothermally altered rocks. Storm water runoff from the scar drainages contributes metal-laden, acidic water to the river and creates a visible plume of discolored water in the river. Acidic runoff reduces the river pH from 7 to the mid 3s for at least 2 hours during large storms and the low pH water continues downstream. Runoff from scar drainages increases some metal concentrations in the river from below chronic ecological criteria to as much as two orders of magnitude greater than acute ecological criteria, and results in acutely toxic conditions for macro-invertebrates. A general improvement in the river?s water quality occurs downstream due to dilution from tributary inflow from non-mineralized watersheds, the natural buffering capacity of the river, and storm water controls at the Chevron Mining Inc. Questa mine.

Jan 1, 2011

By Herry Poernomo, Agus Prasetya, Iga Trisnawati, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Panut Mulyono

We studied yttrium extraction from untreated zircon sand processing waste tailings. Xenotime mineral as the rare earth element source with an abundance of yttrium (REY) was detected in sufficient grade for extraction. As much as 9.03% yttrium exists in zircon tailings (analysed by X-ray fluorescence spectrometry). The presence of yttrium was confirmed by X-ray diffractometry in xenotime minerals, which are yttrium carriers (Y-PO4). The purpose of this research was to determine the effect of leaching conditions on yttrium recovery from zircon sand after alkaline fusion treatment. Alkaline fusion was chosen to decompose phosphate into hydroxide in the xenotimemineral,which will reduce further required hydrometallurgical processing.Alkaline fusionwas carried out for 3 h at 450 °C, with a ratio of sodium hydroxide to zircon tailings sand of ~ 1:1. The alkaline fusion product was leached with water, followed by hydrochloric acid treatment to leach the yttrium. Yttrium recovery reached 87% under optimum conditions (60 °C, 1MHCl, and solid-to-liquid ratio = 1/10 for 7.5 min). A suitable model for yttrium dissolution with hydrochloric acid was diffusion through a solid particle ash layer. The calculated activation energy (EA) for this model was 20.21 kJ/mol.

May 26, 2020

By R. H. Grau, C. D. Taylor, A. L. Martikainen

Utilization of belt air in underground coal mines has been discussed extensively during the last decade. The Final Report of the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining formed by the Mine Improvement and New Emergency Response (MINER) Act of 2006 recommends research on leakage, use of booster fans, and escapeway safety. This paper discusses the role of ventilation modeling in evaluating primary escapeway pressurization in a three-entry development system to improve emergency escape in a coal mine using belt air. The intake entry of the National Institute for Occupational Safety and Health (NIOSH) Bruceton Experimental Mine was pressurized using a 1.1-m (42-in.) diameter, 37 kW (50 hp) fan. The work details air movement in the simulated three-entry system and the resulting leakage patterns. Three mine ventilation software packages were compared to analyze their performance in predicting the airflows and leakage conditions with different fan settings. NIOSH researchers found that the measurement results correlated well with the results of modeling.

Jan 1, 2010

By S. D. F. Rocha, A. L. A. SANTOS, E. M. A. BECHELENI, R. M. Papini, P. R. M. Viana, F. P. C. Silvas

The kinetics of atmospheric sulfuric acid leaching from a Brazilian nickel laterite ore was assessed using distinct reducing agents and ore mineralogy. This transitional ore contains 1.63% Ni distributed as 1.27% in coarse size (− 500 + 150 μm), mainly as silicates (lizardite and chlorite—28.6%), and 2.06%in the fines fraction (− 75 μm), mainly as iron oxy-hydroxides (goethite and hematite—49%). The effects of temperature, acid concentration, reducing reagent type, and concentration were evaluated. The − 75 μm fraction limited the leaching efficiency and the use of reducing media with thiosulfate improved leaching and Ni-Fe selectivity. However, at constant Eh of 626–743 mV and a pH range between 0.2 and 1.1, no substantial rise in metals extraction, except for Co and Mn, has been observed. In order to determine the process control at 95 °C, two regions in the extraction curves were used in combination with the shrinking core model. Control by porous diffusion was observed and the kinetic constant was found to be in the order kFe<kNi<kMn<kCo<kMg for atmospheric leaching without Eh control. In reducing media for the first 15 min of leaching, the kinetic constant was found to be kFe<kNi<kMg≅kCo<kMn as derived from Ni disseminated into iron oxides structures.

Oct 7, 2020

By d&apos, L. F. G. Assumpcao

Kaolin samples from Rio Capim resources were treated in conventional and superconducting magnetic separators to study the main variables that influence the color removal process. Coating clays and delaminated clay were tested. Retention time (or pulp injection velocity), magnetic field intensity and matrix type were the&apos; variables studied. The feed brightness ranged from 84.7 to 87.6 % ISO for the coating clays and from 80.7 to 85.4 % ISO for the delaminated clay. The results showed unleached brightness values higher than 88 % ISO for coating products and higher than 87 % ISO for the delaminated product, using a conventional magnetic separator with an applied field of 1.5 to 2.0 Tesla. With a maximum field intensity in the superconducting machine of 5.0 Tesla, unleached brightness values higher than 88.5 % ISO for both coating and delaminated clays were attained.

Jan 1, 1995

By J. G. Groppo

Lowering of filter cake moisture of ultra-fine coal to a 20 percent level using conventional vacuum filtration could be achieved using a combination of metal ion and surfactants. Pretreating coal slurry with about 0.2 Kg/ton of a surfactant and 50 ppm of copper or 10 ppm of aluminum ions provided filter cake containing 22.8 percent moisture. The lowering of moisture is explained due to formation of hydrophobic micro-agglomerates which facilitates dewatering.

Jan 1, 1994

By D. C. Yang

A practical and economical flowsheet has been developed and demonstrated by integrating the packed column flotation with the GranuFlow process for fine coal recovery. Orimulsion, which was used as an additive, served a dual purpose: first in the flotation and second in the dewatering and granulation steps. The test results on the coal preparation effluent sample show that Orimulsion is flexible and compatible with fuel oil and various frothers used in the packed column. Clean coal with ash contents of 3.0, 3.7, 4.3 and 5.1% were produced from a head sample of 33% ash at combustible matter recoveries of 72.4, 81.1, 87.5, and 89.2%, respectively. Other advantages include high throughput, low moisture, improved handleability, and reduced dustiness of the dewatered coal, thus providing a very significant economic Incentive for the integrated process.

Jan 1, 1998

By L. Alagha, J. L. Corchado-Albelo

To address the U.S. Department of Energy’s critical minerals strategies regarding rare earth elements (REE) in the U.S.A. This study evaluated apatite-rich mine tailing from the historic Pea Ridge Iron Mine (PR) for possible enrichment of REE by the froth flotation process. Comprehensive characterization studies were performed on the tailing samples to quantify the REE content, identify the REEbearing minerals and their liberation behavior. The aforementioned characterization studies were: x-ray fluorescence analysis (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and TESCAN’s Integrated Mineral Analysis (TIMA). The ICP-MS analysis showed that the concentrations of heavy-REE and light-REE were 8000 ppm and 3000 ppm, respectively. TIMA showed that monazite was the major REE-bearing mineral. Additionally, it was shown that monazite and other REE-bearing minerals were strongly locked within larger apatite grains. Findings from the characterization studies suggested that REE could be enriched using phosphate minerals’ direct froth flotation process. Flotation feasibility tests were performed using selected organic and inorganic iron oxides’ depressants, including polyacrylamide (PAM), in-house synthesized hybrid polyacrylamide (HyPAM), chitosan, sodium silicates, and corn starch. Results showed that the depressant’s efficiency at pH 9 was in the following order: HyPAM > chitosan > PAM > sodium metasilicate > corn starch. Zeta potential studies on the selected depressants indicated that chitosan had the highest adsorption on magnetite’s surface at pH 7. Therefore, additional batch flotation experiments using chitosan as an iron oxides depressant were conducted as a function of chitosan dosage. Results indicated that the highest P2O5 recovery of 55% and grade of 28 wt.% were obtained at 150g/t of chitosan. However, the concentrate’s highest total REE enrichment of 1.07% was achieved at a 200 g/t dosage of chitosan. The low enrichment of REE highlighted the complex mineralogy of the PR tailings and the need to implement additional beneficiation strategies before and after the froth flotation process.

Mar 2, 2022