Search Documents

By L. E. Sausa

Measuring the specific gravity of a pulp in concentrating plants is a relative, y simple procedure, but the desired accuracy is often difficult to attain. Many plants use the system of weighing a known volume of the pulp on a scale. In many cases, this method is quite accurate, but obtaining a true sample presents quite a problem. This is especially true when the pulp tends to froth, the solids settle rapidly, or the flow is fast at the point of sampling. There is also the problem of the operator neglecting to take the sample because of duties elsewhere, or, if everything Is apparently running smoothly, he assumes the pulp density is also all right. In 1952, the Pine Creek plant of Union Carbide Nuclear Company began working on a better method for measuring and controlling pulp density. After an extensive investigation of different methods for measuring the specific gravity of moving pulps, the Research Department decided that the bubble tube method appeared to be the simplest and most promising for our applications. It consists of two bubble tubes, of different lengths, submersed in a pulp. Low pressure air is supplied to, the two tubes through sight bubblers to maintain approximately equal volume of air to each bubble tube. The bubble tubes are also connected to a differential manometer, one to each side. Therefore, knowing the vertical distance between the outlets of the bubble tubes, the manometere can be calibrated to measure directly the specific gravity of the pulp. (Figure No. 1 illustrates this model.)

Jan 1, 1960

By Josef Arnold, Norbert Fuegenschuh

The “Eggequerung” is an important part of the German Railway’s (Deutsche BahnAG) modernized Dortmund—Kassel line. The heart of this 13-km-long (8 miles)construction lot is the double-track Egge Tunnel with a total length of 2,880 m(9,450 ft.). The tunnel was driven using the New Austrian Tunnelling Method (NATM).The construction contract also called for a reinforced concrete secondary lining, guaranteed for a full water pressure of 30 m (100 ft.) water column. Preliminary geological study already showed that very problematic geological-hydrological conditions would have to be expected. This talk describes the chosen NATM driving concept that was adapted to the prevailing geological and hydrological conditions, the special driving method applied in geologically difficult zones as well as the water control concept used during driving. The flexibility and the limits of the NATM under exceptional hydrological conditions are illustrated. Also described are reinforced concrete lining works for the watertight secondary vault (reinforced concrete secondary lining without water-proofing membrane).

Jan 1, 2003

By Hongling Wang, DI WU, Shuai Li, Hui Shu

Isothermal reduction experiments on carbon-bearing pellets of copper slag were investigated by the thermogravimetric method with biomass carbon as a reducing agent. The results indicated that the reduction process of copper slag‑biomass composite pellets was dominated by gas phase diffusion, and the apparent activation energy was 88.44 kJ/mol. In the temperature range from 1000 to 1200 °C, the metallization rate of pellets increased with increasing temperature, and the maximum metallization rate was 78.4%. The optimal reduction temperature of CSBCP (copper slag-biomass composite pellets) was 1200 °C.

Nov 23, 2022

By Robin Dill, Julian Prada, Kathryn Kelly, Brian Hann, Todd Moline

Narragansett Bay Commission’s (NBC) Pawtucket Tunnel Project includes construction of the 11,600-ft long, 30-ft ID, deep rock tunnel. This paper presents insight into the features and benefits of lump-sum, design-build that led NBC to select it as the project delivery method. The use of a design-build contracting process that included proprietary meetings to discuss and obtain feedback on Alternative Technical Concepts as well as to facilitate reaching consensus on modifications to the GBR-B is also described. The discussion includes features and benefits of design-build process that not only addressed NBC’s desired outcomes, but also allowed the Design-Builder to propose several innovative changes to the Base Technical Concepts included in the bid documents, and to develop a GBR-C that was compatible with their proposed means and methods of construction and addressed what they believed to be the more significant subsurface risks on the project.

Jun 13, 2023

By Ronney Rodrigues Silva, Renata Mendonca, Gabi Knesel, Cathrine Monyake

Locus Mining is working side-by-side with a prestigious iron ore company to evaluate the addition of Locus ESG-friendly green flotation reagents with the primary goal of improving recovery and grade. In this paper, we will focus on the cationic reverse flotation application. The most “established industry” reagents for cationic reverse flotation are amine as the collector, starch as the depressant, and in some cases frothers are also used (among them MIBC, pine oil, others). Here, we evaluate the synergies of different classes of eco-friendly biosurfactants and industry-standard reagents during the cationic reverse flotation method. Exploratory research was done first with an analog sample under different pHs, eight different biosurfactants with starch and no-starch, and a customized DOE was used to perform 145 microflotation tests. The results show Separation Efficiency from 20% (baseline) to 50% (biosurfactant), and Selectivity from 3.27 (baseline) to 5.67 (biosurfactant). Optimized result conditions were then applied to the iron ore samples received from our client to perform flotation tests on a Denver Lab cell. Similar results were obtained by improving Separation Efficiency and Selectivity, which corroborate with the previous work.

Feb 1, 2025

By Edwin R. (Original by) Phelps

Surface mining refers to the process of removing the material (over- burden) overlying a coal seam and exposing the coal so that it can be loaded out and conveyed by trucks or other methods to the preparation plant or other facility. Surface mining has not always been important in the coal industry. In the early 1900s, almost all of the coal mined in the United States was mined by underground methods. In 1900, about 192 Mt (212 million st) of bituminous coal were mined and less than 1% was mined by surface methods. The development and use of larger equipment has allowed surface mining to gain prominence throughout the years. Table 1 shows the total production of coal by mining method in the United States for ten-year periods since 1920 and indicates the growth of surface-mined coal production. Surface mining will undoubtedly continue to account for a large percentage of the coal production in the US for many years because: 1) The capacity of surface mining excavators has continued to increase. Today, mining companies are using shovels (see Fig. 1) which are able to move up to 137.6 m3 (180 cu yd) in each bite and draglines (see Fig. 2) which move up to 168.2 m3 (220 cu yd) in each bucketful. 2) Increasing tonnage from the thick western coal seams is being produced by surface mining methods. 3) Surface mining has normally had lower costs and a better safety record than underground mining; 4) Surface mining normally recovers a- much higher percentage of the coal reserve than can be recovered by underground mining. 5) Some coal measures can best be extracted by surface mining [ ] methods because of geologic reasons such as the nature of the roof or bottom, thickness of the seam, multiple bedding, etc.

Jan 1, 1981

By I. Mikov

Established in the 60-ies, the Zlatna Panega quarry is a cement raw materials quarry supplying 95% of the needs of the Zlatna Panega Cement Plant with limestone, marl and other silica-aluminates. The two major types of raw materials are formed by accordingly dipping strata of Upper Jurassic limestones and lower Cretaceous marls. Between them there is a ?transition-zone? or ?contact-zone? of a high-silica content layer, about 5-m thick, defined as ?flint? by investigations including spot sampling throughout the quarry. For many years this ?contact-zone? layer was neglected due its negligible thickness. Further, with the increasing demand on the quality of the raw materials feed to the Plant and the focus on variability of the chemical and mineralogical components, it was decided not to mine any of the parts of the quarry contaminated by this material, for about three years. The latter had an impact on the availability of operating benches that could result in a substantial decrease in the total recoverable re-serves of Zlatna Panega, particularly with respect to marls. There were considerations for resorting to a partial, selective excavation of the quarry pit with a reduced lifetime for the lime-stones and re-opening of an other (currently in-active) marl quarry at a distance of 6 Km from the Plant. The Quarry Team of the Zlatna Panega quarry was assigned to study the problem. The ?contact? layer was duly confirmed with systematic geological (including mineralogy) studies, statistical analysis of available data, surface sampling and shallow exploration drills, resulted into distinguishing a third type of reserves and their credible subsurface delineation by means of geological 3-D modeling and quarry design. A new quarry design was finally elaborated with a view of providing flexibility in mining, utilization of the total volume of all available reserves and maximizing the mine life of Zlatna Panega quarry. An industrial test took place in December 2005, by using the contaminated parts of the quarry (co-mining of the ?contact-zone? materials) at a contribution of 15-20% in the raw materials mix, as dictated by their contribution in the total recoverable resources of the quarry. The purpose was to investigate the viability of this solution ? in line with improved quarry planning ? without compromising the quality of cement production and the efficiency of Plant Operations. Results were overall successful.

Jan 1, 2006

By K. V. Raj, R. Jacksha

Conveyor systems persist in being a source of injuries and fatalities in the mining industry. To reduce these incidents, better methods are needed to enhance the monitoring of probable hazards and improve situational awareness during the normal operation and maintenance of conveyor systems. To address these issues, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) continue to investigate emerging technologies that show the potential to improve miner safety around conveyors. This paper presents a feasibility assessment by NIOSH researchers of a fully integrated, commercially available wireless Internet of Things (IoT) system to improve situational awareness around conveyor systems.

By J. B. Yianatos

This paper addresses the impact on performance of column height (H), and column height to diameter (H/D) ratio by modelling the effect of HID on mixing and consequently on recovery and grade. Mineral recovery increases with increasing H/D ratio for a constant column volume and feed flowrate, while the concentrate grade decreases to a minor extent. Columns 10-15m in height with H/D-10 are well suited for feed rates 150-600 L/min. Maximum H/D is determined by the gas carrying capacity, an important consideration for pilot units where H/D?200.

Jan 1, 1987

By William Gleason

For the first time in many years, the Liebherr Group chose to host its annual conference for the international construction trade press in the United States. The reason for the move is simple ? mining. Like other large corporations, especially those in the construction fields, Liebherr felt the effects of the global economic crisis that began in 2008. The slowdown in the housing market was especially hard on Liebherr?s mobile crane and earth moving divisions. The mining division, however, while affected by crashing commodity prices that led to cancelled orders and the loss of financing for some customers, was not battered as badly as the other divisions. And now, with the price of commodities once again on the rise, it seems that it will be Liebherr?s largest machines that lead the family-owned company to better days. ?We can report that our generally optimistic view during the crisis has proved adequate,? said Joachim Janka, president of Liebherr mining equipment, at the conference in Williamsburg, VA, just down the road from the company?s mining truck division global headquarters in Newport News, VA. ?Since the third quarter of 2009, our mining equipment activities have been recording once more a strong and steady demand. This has already yielded a substantial increase in market shares for our product lines of large mining shovels as well as for mining trucks.?

Jan 1, 2011

By S. S. Wang

Dialkyldithiophosphinates are a new class of flotation collectors for base metal sulfide ores. Structurally, they are quite different from the conventional collectors such as mercaptans, xanthates, thionocarbamates and dithiophosphates. Collectors Structures [Mercaptans R-SHS Xanthates R-OCS-M+ Thionocarbamates R-OCNH-R Dithiophosphates 2 R-CCNH-R' Dithiophosphinates (R) 2-PS-M+ ] In the above structural formula, R and R' stand for a hydrocarbon radical, and M+ is an alkali metal or ammonium cation.

Jan 1, 1982

By R. J. Gray

Oxidation of coal can best be described as a process of deterioration, since most of the uses of coal, such as for fuel and by-product chemical and coke production, are adversely affected by coal oxidation, and the inclusion of oxidized coal in most coal products detracts from their value. There are probably many mechanisms of coal oxidation, and the ways oxygen molecules combine as complexes with coal macromolecules to form new substances have been dealt with and speculated upon by many workers1)* but are not dealt with in the present work. This study deals with tests and methods of detecting oxidized coal, with particular emphasis on the microscopically discernible changes that accompany the chemical and physical changes that affect the technological properties of coal during oxidation.

Jan 1, 1974

By SHANTAE LEE, ELAHEH TALEBI, Frank A. Drews, ROGERS W. PRATT

Fatigue is a relatively well-investigated topic in the surface transportation industry with a research focus on sleep deprivation and disruption. This paper examines fatigue in mining operations. While mine operators are using or currently introducing technology to monitor fatigue, there is little work that focuses on the operators’ experience of fatigue and the acceptance of fatigue-monitoring technology. Focus groups were conducted to investigate these topics. The results of this research suggest that current fatigue-monitoring systems lack validity, reliability and user acceptance. Overall, these results emphasize the importance of a socio-technical systems perspective to guide interventions aiming at improving miner health and safety.

By ANA E. BOHE, MICCO GEORGINA DE, GASTON G. FOUGA, JUAN P. GAVIRIA, FEDERICO J. POMIRO

To the best of our knowledge, this paper comprehensively summarizes a thorough study to determine the thermodynamic viability of the reactions between light rare earth oxides and chlorine with and without carbon. The kinetics and mechanisms of light rare earth oxide chlorination and carbochlorination reactions are analyzed and discussed according to results in the literature. Lanthanides between lanthanum (La) and gadolinium (Gd) are considered as light rare earth elements (LREEs) in agreement with previous literature and the results detailed in this review. Both laboratory- and industrial-scale light rare earth chlorinations and carbochlorinations, starting from oxides and ores, are reviewed.

By Irina Melekestseva, Beltenev. Victor, Victor Ivanov

"One of the major problems discussed over the last years is a possibility of mining of seafloor massive sulfide deposits. In spite of the pessimistic points of view on their commercial development, they are still of great interest and continue to be studied (Hannington et al., 2011). Recently, Barriga (2012) paid special attention to the underestimated amount of massive sulfide hydrothermal fields and pointed to the importance of the buried fields and subseafloor mineralization.This study examines the geochemistry of seafloor and subseafloor precipitates collected at the Peterburgskoe (19°52´ N) and Irinovskoe (13°20´ N) hydrothermal fields (MAR) during the 34th cruise of the R/V Professor Logatchev in 2011. These fields were discovered by the Polar Marine Geosurvey Expedition in 2010 and 2011, respectively (Shilov et al., 2011; Beltenev et al., 2012). The Peterburgskoe field, associated with basalts, is located 16 km west of the main rift valley at the depth of 2800-3100 m at the junction of a large non-transform discontinuity with the second rift ridge parallel to the rift valley. The Irinovskoe field occurs at depths of 2700-2850 m and has a northwestern satellite sulfide site, both confined to an oceanic core complex (MacLeod et al., 2009), which includes mafic and ultramafic rocks. The details of geological structure of the fields may be found in the relevant papers.Diverse samples were collected from the hydrothermal fields: seafloor massive sulfides, Fe-hydroxide crusts, SiO2-rich sulfide-bearing precipitates, and subseafloor mineralized rocks (Melekestseva et al., 2014a). Massive sulfides may be subdivided on the Fe-rich and Cu-rich types. The marcasite-pyrite, pyrite, hydroxide-marcasite, and chalcopyrite-pyrite (Fe-rich) mineral types are dominant in the Peterburgskoe field at lesser amounts of sphalerite-hydroxide-chalcopyrite and pyrite-covellite-chalcopyrite (Cu-rich) massive sulfides. The mineralized sulfide-talc-carbonate-chlorite, chlorite-sulfide-quartz, and hematite-sulfide-quartz rocks host stringer-disseminated sulfides including chalcopyrite, covellite, and pyrite."

Sep 1, 2014

By PAITIP THIRAVETYAN, KANJANA KUDPENG

The aim of this study is to compare amino acids and organic acids in the extraction of gold from silicate ore. Amino acids were found to have higher efficiency of gold extraction than organic acids at the same acid concentration, which is likely due to amino acids having both carboxylic and amine groups in their structure, while organic acids only have carboxylic groups. Five amino acids (glycine, aspartic acid, glutamic acid, lysine and tryptophan) and seven organic acids (citric, malic, tataric, fumaric, oxalic, succinic and ascorbic acids) were selected to investigate gold extraction efficiency. Aspartic acid was found to have greater capacity to extract gold than succinic acid. The optimal gold to aspartic acid molar ratio was 1:6, and low concentrations of aspartic acid extracted 35 to 42 percent of gold from silicate ore within 15 days. Further studies are needed to increase gold leaching and reduce incubation time. The results imply that aspartic acid can be used as an alternative reagent to traditional methods for extracting gold from ore. This method is nontoxic to humans, is environmentally friendly and can have real applications.

By Evan Brinkerhoff, Steve Chorley

The largest hard rock TBM ever to bore in the USA, an 11.6 m diameter Robbins Main Beam TBM, recently underwent a planned in-tunnel diameter change to a more compact 9.9 meters. The first-of-itskind conversion process for the Main Beam TBM was undertaken 2.8 km into the bore and was not done inside a shaft or pre-excavated portal. This paper will detail the unique dual-diameter machine designed for the Mill Creek Drainage Relief Tunnel in Dallas, Texas, USA, machine performance, and successful size conversion process that took place in early 2021—a process that utilized the four C’s of construction to enormous benefit: Communication, Cooperation, Collaboration and Coordination.

Dec 1, 2022

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 Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By H. K. Lin

Elemental sulfur is founded to be the predominant sulfur-containing species in a leaching residue resulting from ferric chloride leaching, under given conditions, of a chalcopyrite concentrate. The mineralogical study of the leaching residue which consists of 52% elemental sulfur reveals that the sulfur formed at the end of leaching process is in the form of discrete crystal rather than coating film. Flotation has been applied to recover the sulfur successfully using xanthate as a collector. Dispersants arc needed to prevent the mechanical entrapment of silicate and quartz by sulfur. Very high recovery of sulfur with satisfactory grades can be achieved with a relatively simple notation scheme.

Jan 1, 1991