Search Documents

By J. V. Vogel

Jan 1, 1969

Hydrofluoric acid (HF) is traditionally used in plant operation to separate feldspars from quartz. It acts during the conditioning step as a pH regulator and an activating agent providing an excellent selectivity. However, a corrosive chemical environment and the ecological impacts from the potential fluoride ion contamination are limiting factors to use this chemical agent at an industrial scale. Investigations of the amine-feldspar interactions in the absence and presence of non-linear long-chain alcohols were carried out on two ore samples. The presence of alcohol molecules led to form a closed packed layer only on the surface of feldspars. The highest order and packing at the feldspar surface were observed with a particular alkyl chain structure as Guerbert alcohols. A new flotation process was developed and tested at both lab and pilot scales on different feldspar ores. The Guerbert alcohols allow to perform a feldspar concentrate with very low content in quartz (2.3-3.5 %) and feldspars recovery from 78 to 81 % while the aliphatic isoalcohols show a more higher recovery level (88-89 %). New HF-free process is strongly dependent on the pH range (1.7-2.5) and sulphuric acid consumption during conditioning steps. Optimal amine/alcohol weight ratio is ranged between 0.8 and 1.0. The values below 0.8 decrease strongly the flotation selectivity and the quartz recovery within the feldspar concentrates is higher than that occurs with HF.

Sep 1, 2012

By J. R. Bartels

The U.S. Bureau of Mines has established a wire rope research laboratory to examine the factors that affect the life of wire rope. Two sin-diameter 6x25 fiber core (FC) ropes were degraded on a bending fatigue machine, These were the second and third ropes in a series of tests on this construction and size rope. Tensile and nondestructive tests were performed on samples of the rope to determine the relationship between rope deterioration and rope breaking strength. The tests indicated that once a wire rope nears the end of its service life, both deterioration and the consequent loss of rope strength begin to increase at an accelerated rate.

Jan 1, 2010

By David Cheung, S. Paul Singh

"The characteristics of a blasted muck pile can have a significant effect on the productivity and economyof loading and hauling operations. Poorly fragmented and tight muck piles, caused by insufficientdisplacement of the broken rock, lead to higher digging and hauling costs. Therefore muck pile must be tailored to suit the loading and hauling equipment. In order to achieve this objective, it is imperative to understand the relevant muck pile characteristics and factors governing them. In general, muck pile characteristics are governed by the blast design parameters, rock mass geology, explosive characteristics and post-blasting requirements."

Jan 1, 2017

By Janene Barter

Telfer Gold Mine treats both gold/copper oxide and sulfide ores in a remote location in the Great Sandy Desert, Western Australia. Currently, the oxide gold ore is treated in a conventional CIL circuit by blending the low and high grade copper ores to minimise cyanide consumption and allow smooth operation. The sulfide ore is treated through a flotation circuit to produce pyrite and copper concentrates. The pyrite concentrate is treated in the CIL. Copper concentrate is stockpiled and sold to a smelter for further processing. In recent times, as the depth of the pit has increased the copper head grade has also increased, to the point where the ore was becoming uneconomical to treat. In addition, it was desirable to reduce the amount of cyanide reporting to the tails dam both from an environmental and economical viewpoint. Newcrest Mining Limited engaged GRD Minproc Limited to evaluated a process to reduce the amount of cyanide entering the tail dam with consideration given to copper recovery. From this investigation, the Sulfidisation, Acidification, Recycle and Thickening (SART) process was selected. A detailed testwork program for SART was undertaken with the objective to design and construct a SART plant at Telfer. This paper outlines how the SART process was chosen and summarises the testwork that led to the design of the SART plant. It also touches on some of the important issues for designing this type of process.

Jan 1, 1998

By V. Panayotov, M. Panayotova

"The combined use of semiconductor properties and specific flotation characteristics of minerals under different conditions with external influences ensures a possibility for process control and management. This work presents the relations between the volumetric and surface characteristics of minerals and the minerals' flotation ability (flotability), as well as the possibility for the flotability purposeful change. Results from proprietary laboratory and industrial research are presented showing how controlled impacts on minerals and flotation pulp improve flotation technology. Such an approach reveals prospects for the creation of new technologies for the minerals' beneficiation.INTRODUCTIONThe decrease of the useful components content in the ores, the increasingly complex nature of the raw materials, the increasing energy consumption per the unit of production, and the need to solve the problems related to the environment pollution require solutions different than the existing classical ones. One of the ways to find such solutions is the detailed consideration of the fundamental properties of minerals and, in particular, of minerals having semiconductor properties. The studies of Plaksin et al. (1968), Chanturia and Shafeev (1977), Chanturia and Vigdergauz (2008), Carta et al. (1973), Hoberg and Shneider (1975), Rao et al. (1992) have given an idea of the energy state of the minerals, their flotation ability, and the ways in which this ability can be changed in one or the other direction. The main line in these works is the study and use of the relationship between bulk and flotation properties of minerals. To improve the efficiency of the process, it is also necessary to consider the relationship between the surface properties of the minerals, especially minerals-semiconductors, and their flotation ability.THEORETICAL BACKGROUND IN BRIEFA quantitative estimation of energy changes in a solid phase in the process of flotation may be made by taking in account the changes in the Fermi level. Its position in the forbidden band is an indicator about the direction and the intensity of electron exchange between solid and liquid phases. The Fermi level energy EF enables the estimation of flotability, intensity of needed external impact before flotation, as well as efficiency of the process going on. Quantitative estimation of these processes can be made by means of the flotability coefficient Kf."

Jan 1, 2018

By José Darío Sanabria Cerrón

El presente texto describe la operación de las zarandas de alta frecuencia en la etapa de molienda de las operaciones mineras del país. Durante esta etapa se consume la mayor parte de energía que debe ser aprovechada eficientemente a través de una buena clasificaciónen húmedo de la molienda en minerales para disminuir los costos operativos sobre la base productiva de la planta.

Jul 1, 2015

By E. T. Pecina

Bioleaching is a viable option for the processing of auriargentiferous refractory ores with high arsenic content. The application of mesophilic (A. ferrooxidans and ?L. ferrooxidans?) and thermophilic bacteria of the genus Sulfolobus (S. solfataricus and S. acidocaldarius) as oxidant treatment before the cyanidation of an industrial arsenical pyrite concentrate is presented. The results show that extraction of gold and silver increases due to bio-oxidation caused by mesophilic bacteria and results in a maximum gold recovery of 68%. In all strains studied, biooxidation resulted in an average silver recovery of 50%. The results showed that all evaluated strains were sensitive to solids content (5 to 20%) and average particle size (75 and 38 µm) of the concentrate.

Jan 1, 2010

By C Jincheng, L. Liang, L. Wenjun

"Considering overgrinding in a grinding process, the grinding characteristics of comminuted hematite products using a HPGR and a conventional CC were comparatively studied. The major properties including particle size, grinding kinetics and grinding technical efficiency (Et) were investigated. Individual size distributions (ISDs) of -2.0mm in a HPGR product showed a more significant “double-peak” characteristic than a CC product. As a result, HPGR products were finer and had a wider full-size distribution because of the greater proportion of fines. The parameters m and zi in m-th order grinding kinetics were analyzed by the partial-derivative method and the critical time tc(tc = exp (1/ zi)) was obtained. zi mainly affected the breakage rate when t < tc; otherwise, m mainly affected the breakage rate. In these tests, tc was considerably higher than the grinding times, and HPGR products yielded a higher zi-value than the CC product for the same sieve size. This indicated that HPGR products had a higher breakage rate and needed a shorter grinding time for a certain grinding fineness. Et was calculated by simulating the size distributions of batch grinding products. HPGR products gave a lower Et at a decreasing rate than the CC products for -2.0 mm feed and -0.5mm feed, and then showed a slightly higher Et for -2.0+0.5 mm feed. This indicated that overginding in HPGR full-size products was more serious under the condition of coarse grinding, whereas the efficiency was higher and overgrinding weakened significantly in HPGR coarse products because of screening-out fines. Based on the above research, a new process of “ultra-crushing in HPGR – classified grinding” was advanced, reducing ores tonnage into first stage ball mill significantly, improving grinding efficient and weakening overgrinding in the whole grinding process.INTRODUCTIONIn mineral processing, comminution accounts for a substantial portion (approximately 60~70%) of the energy consumed in plants. As an ultra-fine crushing equipment,the application of the HPGR for industrial comminution has been paid close attention because of its low specific energy, low steel consumption, high capacity and high ratio of reduction, among others (Schonert, 1998; Norgate & Weller, 1994; Fuerstenau & Kapur, 1995). HPGRs comprise two counter-rotating rolls that draw feed material into the roll gap. One roll is fixed to the mainframe, while the other movable roll is mounted on slides and positioned by hydraulic rams. The specific pressing force (SPF) (i.e., total force divided by projected roller area) is typically in the range of 3~9 N/mm2 depending on the application, while pressures of up to 1000 N/mm2 have been measured within the operating gap (Maxton , Morley, & Bearman , 2003)."

Jan 1, 2016

By C. I. Basilio

The mechanisms involved in the adsorption of modified thiol-type collectors on sulfide minerals have been investigated in the present work. These collectors belong to the broad classes of thionocarbamates, thioureas, thiophosphates and thiophosphinates. They differ significantly from the traditionally used thiol-type collectors, such as xanthates and dithiophosphates, in terms of structural features that involve either the introduction of an additional oxygen donor or the alteration of electron densities on donor atoms. Electrochemical studies suggest that the adsorption of these classes of collectors is probably the result of a coupled reaction of the EC-type, involving an initial electron transfer step (E), followed immediately by a chemical reaction (C). Thus, the overall adsorption process is controlled by both the E, and pK of the system. The role of structural features in changing the interaction of the donor atoms with sulfide minerals is also discussed.

Jan 1, 1991

By J. Zhou1

"The extractive metallurgy of gold ores is largely driven by their grade and mineralogy. The concentration of gold in the crust is extremely low and highly variable, resulting ore variability in many gold and copper-gold deposits. More importantly, gold in an ore may occur in two or three forms (i.e. microscopic gold, submicroscopic gold and surface gold), making gold ore processing extremely challenging. Geometallurgy is a technique to document variability within an orebody and quantify and evaluate the impact of many factors including geology and mineralogy on grinding, flotation, leaching and metal recovery processes. The objective of gold geometallurgy is to reduce and minimize the technical risk in project evaluation, plant design, mine planning and production forecasting through geometallurgical modelling, representative sampling and subsequent systematic mineralogical and metallurgical testwork. Gold deportment study is a powerful tool in characterization of various gold ores. Effective and quantitative gold deportment results are critical and useful for predicting gold recovery and building geometallurgical models of gold ores. This paper provides an overview of geometallurgy fundamentals and applications in gold processing, with a focus being on the ore characterization and gold deportment study.INTRODUCTION Geometallurgy is an inter-disciplinary approach which links the geological, geochemical and mineralogical characteristics to the metallurgical performance of an orebody. Combined with mine planning, it has been used in scoping, prefeasibility and feasibility studies, process design and optimization of gold, copper-gold, copper-moly, nickel and iron projects among others (Williams & Richardson, 2004; Dobby, Bennett, Bulled, & Kosick, 2004; Bulled, 2007; Bulled, Leriche, Blake, Thompson, & Wilkie, 2009; Kormos, Sliwinski, Oliveira, & Hill, 2013; Muinonen, Sciortino, Korczak, & St-Jean, 2013; Leichliter & Larson, 2013; Leichliter, Jahoda, & Montoya, 2013; Hatton & Hatfield, 2013; Baumgartner et al., 2011, 2013; Hoal, Woodhead, & Smith, 2013; Zhou, 2013). The goal of a gold or copper-gold geometallurgical program is to characterize and understand the metallurgical variability of an orebody, such as comminution, gravity, flotation and cyanidation parameters and metal recoveries, and to build a geomet model which can be used to assist in mine planning and to predict the plant performance. In any geometallurgical program, representative sampling is the key to ensure the results of a geometallurgical study will reflect future performance once the plant is commissioned. Geometallurgy compliments, but does not replace, the traditional mineralogical and metallurgical approach during the development and operation of a gold or copper-gold project. Geometallurgy is a methodology for testwork design and a framework for mine planning. The first part of this paper provides an overview of geometallurgy fundamentals and application in gold ore processing."

Jan 1, 2017

By Felicia F. Peng

Using granular media for removal of soluble manganese from mine water and industry waste stream has the advantage of forming a compact surface layer of manganese oxide coating on the media. This process can avoid the step involving the separation of voluminous sludge of manganese hydroxide by the high-pH method for soluble manganese removal. The removal of soluble manganese is accomplished by adsorption and oxidation. The adsorption of Mn(II) on the manganese oxide-coated media was rapid through the specific adsorption and may be due to the ion exchange of hydroxyl ions on the manganese oxide by Mn(II). In the subsequent step, the adsorbed Mn(II) form the intermediate manganese complex on the manganese oxide product is oxidized with dissolved oxygen or other available oxidant source in the aqueous solution. This paper presents the efficiency of removal of soluble manganese from mine water by using a laboratory fluidized bed and the recovery of manganese oxide coating on the anthracite coal particles. In order to accelerate the formation of the manganese oxide layer on the surface of anthracite media, dilute potassium permanganate solution is used as an active oxidant. The effects of operation parameters on the manganese removal including pH, flow rate, concentration of feed and oxidant dosage are evaluated.

Jan 1, 1996

By Mario E. Rossi

Geostatistical conditional simulations are becoming increasingly popular as tools that provide models of uncertainty at different stages of a mining project. They have been used as grade control tools in daily operations, to assess the uncertainty of minable reserves at the project?s feasibility stage, and to assess mineralization potential in certain settings. Other applications include assessment of recoverable reserves, resource and reserve classification, and drill hole spacing optimization studies. All large-scale applications of conditional simulations intend to benefit from the ?correct? (or ?accurate?) characterization of uncertainty, adequately describing the variability observed from the data and its impact on the final objective. The objective of this paper is to compare the ad-hoc ?uncertainty model? provided by a traditional classification scheme with the probability intervals resulting from a conditional simulation model. It is argued that the uncertainty model derived from the use of classification schemes is of little practical use to the mining company or operation. The paper emphasizes differences in uncertainty based on the size of the mining unit considered and the extraction method, and local geological differences. Most importantly, it discusses confidence intervals for these mining units, as compared to the relative precision envisioned by a typical classification scheme. The application described in this paper is taken from a medium-sized Cu open and underground mine in northern Chile, and it demonstrates the impact of several variables on the resulting conditional simulation models. It also compares a more ?traditional? resource classification scheme applied, and the wide difference in local confidence intervals for each mining unit.

May 1, 2001

An enhanced gravity concentrator was installed in conjunction with an intensive leach reactor at the Sadiola plant in Mali last year and commissioned in December 2007. There has been much debate over the years as to the effect of gravity concentration on overall plant performance. The late Dr Laplante suggested that for every ten per cent of gold recovered by gravity, there was a corresponding 0.1 per cent to one per cent additional overall plant recovery. The results at Sadiola are consistent with this hypothesis with an overall four per cent gain in plant recovery. With total gold recovery of 12 per cent in the gravity section, grades are increased from 3.54 g/t in the gravity feed to an average of 2 600 g/t in the concentrator feed to the inline reactor. The recovery of gold in the inline reactor is in excess of 98.5 per cent. This paper discusses the background to the project, the laboratory test work prior to the equipment selection, the operational results of the system, as well as the benefi ts of the future application of high mass yield centrifugal concentrators in base metals, sulfides and industrial minerals. Bench scale, pilot scale and plant practice examples are also presented.

Aug 1, 2010

By Rodolfo V. de la Cruz

The stresses in the materials surrounding an underground opening are dependent upon the virgin stress field, the geometry of the opening and changes in boundary conditions as mining progresses. For most underground openings especially in coal mines, roof bolts are installed to help stabilize the opening. While most parameters in roof bolt design and installation have been thoroughly investigated, the effects of the initial stress field on the effectiveness of roof bolts have not been recognized. This paper summarizes the results of investigation of the effect of the initial stress field on the performance of mine roof bolts. Roof bolt installations are duplicated in the laboratory utilizing conventional roof bolt frame, commercial roof bolts and shells, mine torque wrench and encapsulated rock specimens for anchorage. A special and primary feature of the laboratory set-up is the addition of a loading system for generating stresses at the anchorage specimens. For this preliminary study, different levels of hydrostatic stress fields were induced at the anchorage specimen, instrumented roof bolts were installed in the usual manner, and the bolt load loss-with-time observed. Statistical analysis of data showed that the stress field at the anchorage horizon has a considerable influence on the performance of mine roof bolts, i.e. the higher the stress field, the higher the anchorage efficiency. From this observation, methods of improving the performance of mine roof bolts utilizing new shell designs and methods of installing them are suggested.

Jan 1, 1978

By A. H. Kaksonen

Numerous reactor designs for biological sulfate reduction have been reported. Fluidized-bed bioreactors (FBR) can efficiently retain biomass and allow high mass transfer and reaction rates. This work reviews the development of various sulfate-reducing FBR processes for treating acidic metal- and sulfate-containing waters and recovering metals from bioleaching liquors. The FBR process performance was evaluated with continuous flow experiments under various operational conditions: fluidization rates, influent pH values, metal, sulfate and salt concentrations, hydraulic retention times, electron and carbon sources, and temperatures. Substrate utilization and sulfide inhibition kinetics were determined with batch FBR-kinetic experiments. An artificial neural network (ANN) model was used to predict the performance of the FBR. Sulfate-reducing bacteria (SRB) were characterized in FBRs with molecular and culture-based approaches with the aim to gain a better understating of the bioprocesses. Based on the studies, FBRs are well suited for the combined removal of metals, acidity and sulfate from water.

Jan 1, 2010

By R. F. Yap

Although laboratory studies of tin flotation have been reported as far back as the 1920`s(1), the commercial application has only been realized within the past few years(2,3). The principal technical difficulty in the application of the process to tin ores has not been in the flotation of cassiterite itself, this mineral being readily recoverable with the common collectors, including xanthates with heavy metal ion activation(2). The difficulty has been with the depression of the gangue minerals commonly associated with tin ores, and to a lesser extent with the problems of collector consuming semi-colloidal minerals which are in some cases present. The application of sulfosuccinamate collectors to flotation of cassiterite from the Catavi, Bolivia, slime tailings has recently been described(3). The investigation which led to this successful process development included studies of other samples of gravity plant tailings as well as of lode tin ores. A common flowsheet with few significant variations was applied to most of these ore samples with acceptable results. In the following the process is described and the results of its application to samples from Bolivia and elsewhere given. Among the factors considered are: gangue depression, particle size and slime effects, and reagent and pulp density levels.

Jan 1, 1971

By Thomas T., Read

IN this survey of the progressive development (of education for the mineral industries throughout the United States, the review of .the history of each school has usually been completed wherever it is first mentioned, but the history of the schools in the cities of the eastern seaboard was not carried beyond 1870. It is necessary now to cover what happened during the period of approximately the last quarter of the nineteenth century in several of the schools in the east. Philadelphia Of Philadelphia, it has been related in chapter 4 that the Polytechnic College of Pennsylvania began offering a curriculum leading to the B.S. in mining in 1853; that the school did not prosper, and finally closed about 1890. The establishment of a Department of Mining, Arts, and Manufactures at the University of Pennsylvania in 1855-56 was also mentioned, but its history was not carried beyond 1860. In 1859 J. Peter Lesley was appointed professor of mining in the University of Pennsylvania. The son of a cabinetmaker, born in Philadelphia Sept. 17, 1819, he had taken his A.B. degree at the University of Pennsylvania in 1838 and then secured a position on the Geological Survey of Pennsylvania under H. D. Rogers. When the Survey was discontinued, in 1841, he went to Princeton to study theology, was ordained a Presbyterian minister and followed that career until 1852, when the Pennsylvania, Geological Survey was again started and he rejoined its staff. He published "A Manual of Coal and its Topography" in 1856, and studied at the École des Mines, Paris, in 1856-57. He published an 800-page "Iron Manufactures Guide" the year that he was appointed to the staff at the University of Pennsylvania. In 1863-64 a College of Agriculture, Mines, Arts and the Mechanic Arts was established, but it was not a separate school

Jan 1, 1941

By R. F. Hammen

Heavy metal contamination of water is a problem of immense national and international proportions. However, effective cleanup is complicated both by the toxicity and the low concentrations of metals in wastewater streams. Using high performance chelation chromatography, the solid phase extraction and purification of extremely dilute metals from water was highly effective. The process is based on selective displacement of metals from a chromatographic column containing a chelating resin. The resin is characterized by extremely efficient adsorption kinetics which allow rapid and complete removal of the metals.

Jan 1, 1993

By Kai Koosmen, Mehdi Serati, Tengzhou Wang

Spalling and rockburst are unwanted brittle failures at the boundaries of underground excavations that are commonly observed in hard rock and high-stress environments at significant depths, although, spalling has also been observed in comparatively shallow soft rocks. The crack initiation (CI) stress threshold (representing the stress level at which new micro cracks begin to form in an intact rock) is widely used to establish the in-situ spalling strength, and is generally regarded as the lower limit of the long-term rock strength. This study analyses the evolution of CI and other mechanical properties for a high-porosity sandstone with an average UCS of 38 MPa under unconfined cyclic compressive loading. The results indicate that rock properties are variably affected by cyclic loading with; no significant effect on Youngs Modulus; a moderate increase in Poisson’s ratio and fracture angle; a moderate decrease in UCS; and a major reduction in the CI stress threshold. All of these changes were generally amplified by cyclic loading at higher stresses. From the results, it is concluded that rockburst and spalling limit in underground structures may reduce over time if the rock is subject to repetitive cyclic loading, and that the reductions will be greater for higher cyclic stresses. This may be a significant factor in the design and operation of some deep underground structures.

Apr 26, 2022