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By K. C. Corin, Z. G. Song, J. Y. Liu, M. W. Zhang, State Key Laboratory of Mineral Processing-BGRIMM, J. G. Wiese

"In the present study effect of grinding media on flotation of two mineral systems have been investigated, viz. sulphide minerals (including a pure chalcopyrite and pyrite mineral, and two different base metal sulphide ores), and oxide minerals (quartz, hematite and cassiterite). It was shown that mild steel media milling produced lower recoveries in the case of chalcopyrite and pyrite, as compared to the case of milling using ceramic media. For oxide minerals, the effects of using mild steel media as opposed to ceramic media were not as significant as was for the sulphides, although, after mild steel milling, at acidic pHs their recoveries were significantly reduced. For two base metal sulphide ores, viz. Nkomati and Dexing ores, the differences resulting from different milling media , although marginal, were opposite for each of these ores.For oxide minerals XPS showed that oxides and hydroxides of iron (e.g. FeOOH) adsorbed on the surfaces of the minerals. In the case of the Nkomati ore, adding Fe2+ or F3+ ions after milling with chrome steel media resulted in reduced talc (gangue) recovery, but increased water recovery and reduced concentrate grades. Further investigations are currently in progress to examine the Fe ions effect on the talc surfaces and froth properties.INTRODUCTIONGrinding of ores is necessary to liberate the valuable minerals from its gangues to allow for their selective recovery during mineral processing such as flotation. The grinding process inevitably involves contact of the ores with the surface of the grinding device and the grinding media. Accompanied by grinding, several phenomena can occur including the grinding medium wear, formation of precipitated species on the ore surfaces, chemical reaction, galvanic effects, changes in the Eh of solution, etc. There is a considerable body of literature on the differences observed in the flotation of various ores after milling using various grinding media. Laboratory studies have used balls or rods made from mild steel, ceramic, stainless steel or chrome steel to investigate the effects of different grinding media on mineral flotation. It is found that the interactions between the ore and the grinding environment can affect flotation separation of sulphide (Wei and Sandenbergh, 2007; Bruckard, 2011), oxide (He et al., 2014) and carbonate minerals (Song, 2009 and 2010). For example, mild steel milling produces relatively high concentrations of Fe ions in the pulp, affecting the recoveries of minerals compared to the case of ceramic media. On the other hand, the stainless steel media or chrome media are reported to be beneficial to the recovery of sulphides, when compared to the cases of using mild or carbon steel media (Rey and Formanek, 1960; Peng et al., 2003a,b; Huang and Grano, 2006; Bruckard, 2011). It is not clear, however, whether these Fe ions may affect the surface properties of the minerals involved or the general pulp/froth behaviour and hence their floatability. In addition, in the study of an low-S PGE ore carried out by Miettunen et al. (2012), forged media grinding in the CO2 atmosphere led to the highest Pt and Pd grades and recoveries, but the high chrome grinding media gave lower flotation recoveries than those using the forged media."

Jan 1, 2016

By D. Neely

As Saskatchewan potash mines grow in age and size, mining reaches greater depths.  The stress-relief design principals which were empirically derived at shallower depths are beginning to show fault.  Nutrien Vanscoy Potash has began to encounter new ground support and panel design challenges which were previously had negligible effect.  While the initial reaction was to reduce extraction and implement distance buffers between operating machines, it eventually became clear that these would only provide short term relief and that in order to continue safely and efficiently mining broad areas, a fundamental change in the mine design would provide the long-term protection required.  Presented is a case study with an overview of the challenges encountered at Vanscoy Potash in areas of greater depth along with an account of the design changes considered, implemented and recommended for future success. 

May 4, 2025

By K. G. Markkola

The Minera Candelaria concentrator was commissioned in August 1994, and in October 1997 it doubled its grinding capacity. The concentrator was designed to treat 56,000 metric tonnes of copper ore with a primary crusher, two grinding circuits, pebble crushing, and flotation. The grinding circuit includes two 11.2 m (36 ft) diameter by 4.6 m (15 ft) long semi-autogenous (SAG) mills, each fitted with a 12 MW motor. Throughout the history of Candelaria, different strategies have been developed to maximize the plant's operational time, strategies that include increasing the life of the SAG mill liners and reducing the time involved in changing these elements. This work describes the improvements made in the design of the liners, the change planning, and a new strategy to change the liners with the purpose of increasing their use and throughput.

Jan 1, 2007

By L. Jiang

The evolution of twinning in an AM30 Mg alloy was examined by uniaxial tension and compression testing at temperatures from ambient to 250°C and a strain rate of 0.1/s. The samples were cut along the extrusion direction from extruded AM30 Mg alloy tubes. Specimens deformed to various strain levels were examined by optical microscopy and electron backscattered diffraction (EBSD) techniques. The results indicate that the initial extrusion texture plays an important role in the formation of different types of twins and that the twinning behavior also depends on the strain path. Contraction and double twinning are the dominant twinning mechanisms in uniaxial tension, while extension twinning prevails in uniaxial compression. The different twinning behaviors are shown to be responsible for the sharply contrasting strain hardening characteristics of the experimental flow curves.

Jan 1, 2006

By Nur Hossain

Analysis of Linear Elastic Fracture Mechanics (LEFM) parameters via the Virtual Crack Closure Technique (VCCT) has been obtained for SENT specimens of AM6OB magnesium alloy. It is found that the ratio of initial crack length to initial monotonic plastic zone size is one of the critical factors in establishing the limit of using LEFM concepts. If this ratio is below a certain limit (i.e. when crack lengths are small in comparison to the plastic zone size), loss of similitude stress intensity factor range would occur. This ratio, therefore describes the limit below which the use of LEFM would no longer be admissible. In this study, the above limit was established for AM6OB magnesium alloy. In addition, fatigue crack propagation tests were conducted to ascertain the fatigue response of the alloy and determination of the coefficients of Paris model.

Jan 1, 2010

By W. I. van Drunick

The Anglogold Ashanti (AGA) Navachab single stage SAG mill has provided an excellent setting for incremental optimization. Over the past decades, several interventions have resulted in marked improvements in specific performance; including steel ball scat removal, re-design of the mill lifters, replacement the pebble crusher and cyclone cluster, as well as the use of a vibrating screen in place of a discharge trommel. Recent initiatives now include an operating fine DMS circuit, studies on pre-crushing of the ROM feed and also fine-screening as an alternative to hydrocyclone classification. The current optimized state of the Navachab mill allows it to operate at approximately 20% higher efficiency when compared to mills of similar shell dimensions in gold mining, treating similar ore. This paper describes the systematic improvement of the SAG circuit to its current state.

Jan 1, 2012

By H. M. A. Rice

"The Ainsworth mining camp is on the west side of Kootenay lake; British Columbia; 14 miles south of the town of Kaslo. It is in one of the oldest mining districts in central British Columbia; for mining started there in 1888. Its principal production was between 1905 and 1920. Activity since then has been sporadic. According to available records; some 222; 000 tons of ore had been produced from the camp up to 1942.GENERAL GEOLOGY Bedrock in the district consists of a succession of quartzite, quartz-mica schist, hornblende schist, and limestone of Late Precambrian, Carboniferous, and Triassic age. Most of the hornblende schists are of volcanic origin but some formed from related intrusions. The Nelson granodiorite batholith of Jurassic age borders the camp on the west. There is also a series of basic dykes of much later age."

Jan 1, 1954

By S. Kawai

Natural convective flow of the electrolyte solution plays an important role in several electrochemical systems. Copper refining electrolysis is the most important industrial process to produce high purity copper on large scale. Turbulent natural convection develops along vertical plane copper electrodes installed in an unstirred electrolyte accompanying with the electrochemical deposition and dissolution of copper during the electrolysis. It introduces the electrolyte stratification phenomenon. Thus, the electrolyte is circulated in a special way depending on each electrorefining tankhouse. The theoretical discussion is indispensable to understand the coupling phenomenon between the ionic mass transfer rate and the morphological variations of electrodeposited copper. In present study, the mass transfer rate of both Cu2+ and H+ ions as well as the momentum transfer rate is numerically analyzed accompanying with the turbulent natural convection along 1 m high Cu metal electrode surface.

Jan 1, 2007

The copper electrodeposition from sulphuric acid electrolytes in the presence of Thiourea and Gelatin as additives was investigated by electrochemical noise and cyclic voltammetry in conjunction with the scanning electron microscopy technique. This study was oriented to examine the utility of using electrochemical noise "EN" technique to characterize the electrowinning process and the deposit structure morphology as compared to cyclic cyclovoltammetry "CV", an electrochemical method generally used industrially. Both EN and CV techniques were successful to reveal the effect of different concentrations of Thiourea and Gelatin on copper electrodeposition process. In this study, CV has detected an excess of Thiourea leading to porous deposit. While, the electrochemical noise analysis in the time domain (skewness and kurtosis parameters) as detected the presence of nodules and has given useful information concerning the morphology of the deposit closely related to the macroscopic and microscopic studies.

Jan 1, 2007

By V. C. Pandolfelli, P. Bonadia, F. A. O. Valenzuela, L. R. Bittencourt

Refractories for aluminum cells, if not properly selected, can lead to increased energy consumption and even shorten the pot life. Based on recent advances in understanding the deterioration mechanism of cathode materials, several commercial bricks in the SiO2-Al2O3 system were compared to the one used by an Alcoa smelter. Both physical and chemical properties were considered in the selection of the refractories. A more reliable method of permeability measurement, which takes into account inertial and viscous effects during the fluid flow, was applied. Additionally, the traditional cup test and other characterization techniques, such as thermal conductivity, X-ray diffraction, and mercury porosimetry, indicated that a brick with a relatively low alumina/silica ratio, presenting low open porosity and low permeability, far exceeded the performance of the brick currently in use.

Jan 1, 2004

By Pierre Labrecque

Dispatch systems have been used for open pit mining since the early 1980?s but similar systems do not widely exist for underground mining. There is a need for developing dispatch systems for underground mines, particularly highly automated operations such as block caving. An innovative method, Agent Based Modeling (ABM) for a dispatch system for a block caving operation, is proposed in this paper. The model is based on a particular behaviour observed in social insects. The focus of the ABM dispatch system is adaptability with respect to changing operational conditions and effective integration of maintenance modules with the operation. The paper will show the advantages of this innovative method compared to existing similar systems. Furthermore, the preliminary approaches for developing an agent based modeling system for block caving operations are highlighted and discussed in this paper. 1. Introduction In social

May 1, 2008

By H. Wilhelm, W. I. van Drunick

The Anglogold Ashanti (AGA) Navachab single stage SAG mill has provided an excellent setting for incremental optimization. Over the past decades, several interventions have resulted in marked improvements in specific performance; including steel ball scat removal, re-design of the mill lifters, replacement the pebble crusher and cyclone cluster, as well as the use of a vibrating screen in place of a discharge trommel. Recent initiatives now include an operating fine DMS circuit, studies on pre-crushing of the ROM feed and also fine-screening as an alternative to hydrocyclone classification. The current optimized state of the Navachab mill allows it to operate at approximately 20% higher efficiency when compared to mills of similar shell dimensions in gold mining, treating similar ore. This paper describes the systematic improvement of the SAG circuit to its current state.

Jan 1, 2012

By Robert B. Parsons

"The Province of Manitoba tabled a Budget on March 11, 1992, which contains some important new initiatives designed to improve the fiscal environment for mining in the province. In addition, the Minister of Energy and Mines has released details of the Mineral Exploration Incentive Program which was originally announced in the 1991 Budget.Introduction""We recognize the important contribution o f mining to the economic activity of our province, including direct and service jobs and export earnings. We are determined to secure its future."" - The Honourable Clayton Manness, Minister of Finance, Province of Manitoba, March 11, 1992.With these words of introduction, Manitoba Finance Minister Clayton Manness announced a number of significant measures aimed at improving the fiscal regime for exploration and mining in Manitoba. At the same time, details of the Manitoba Mineral Exploration Incentive Program (MEIP) were released."

Jan 1, 1992

By N. Aydogan, H. Dundar, Å. Partapuoli, A. Fredriksson, P. Wikström, K. Tano, G. Adolfsson

The Autogenous milling of ores holds an increasing attraction as the focus moves towards reducing energy usage, both direct and embodied in grinding media. However, most of the early AG mills were converted to SAG for improved stability and increased throughput. This imposes a huge penalty in steel grinding media consumption. The LKAB iron ore operations in Sweden process highgrade magnetite through fully-autogenous milling lines to a final product P80 of about 45µm. The outcomes of P9O AMIRA research surveys, covering a wide range of mill fillings and throughputs and with different feed blends, are presented. Insights are provided on operational strategies, opportunities, the influence of feed size control and balancing the blend of competent gangue and softer magnetite. Areas of importance in the successful operation and control of energy-efficient autogenous circuits are highlighted.

Jan 1, 2012

By S. M. Grillo, Fiori. M., R. Bornioli, C. Marini, S. Fadda

Abstract - The Na-feldspar orebodies in Sardinia occur along structures belonging to a regional ENE-WSW system that developed during the late stages of the Hercynian orogeny, and that was reactived during the Alpine orogeny. The main petrographic facies include granitoids, albitized granitoids, albitites (more or less rich in quartz), and albitites containing Mg minerals. Field observations and petrological and geochemical data point toward a metasomatic origin for the albitite orebodies. Albitization involved depletion of K from K-feldspar and biotite, dissolution of free quartz, and a lowering of Sr/Na2O and CaO/Na2O ratios in the protolith, under conditions of a positive thermal gradient. The absence of later K-metasomatism implies that, during a subsequent decline in temper- ature, the composition of the albitizing fluids was modified by an influx of meteoric or other waters.

Jan 1, 1996

By C. Díaz, A. D. Dalvi, C. E. O'Neill

Roast-reduction smelting (RRS) of nickel concentrate, combined with flash smelting of copper concentrate, was one of the process options that Inco considered as a means of meeting its 1994 sulphur dioxide abatement target at its Copper Cliff operations. RRS involves deep roasting the nickel concentrate in fluid bed roasters. The roaster off-gas is treated in a sulphuric acid plant, and the low sulphur calcine is reduction smelted with coke in an electric furnace to yield a sulphur- deficient matte. The latter material is converted to Bessemer matte in Peirce-Smith converters, with minimal evolution of sulphur dioxide, and the converter slag is reverted to the electric furnace. Excellent nickel and cobalt recoveries (Ire obtained. This paper discusses the development of RRS, including extensive commercial scale testing at Inco's Thompson Smelter, and its key operating parameters.

Jan 1, 1994

By Ö Yilmaz

In this study, the behaviour of rock mass subjected to blasting load is investigated using three dimensional finite difference numerical modelling. In the analyses, Mohr-Coulomb failure criterion has been used for the characterisation of the rock mass strength. Stresses acting on the borehole boundary have been simulated by an exponential function which reaches its maximum within a short time and then falls to zero value in a considerable time period. The strain rate effect on the mechanical properties of rock material has also been taken into account in the analyses. Four different explosive-rock mass combinations have been studied to investigate blast induced damage zone. It has been observed that proposed equation for the dynamic compressive strength of rock material fits very well to general suggestions. Results have shown that blast damage analysis model recommended with this study is successful.

Aug 1, 2013

By Y. Lizotte

"This paper examines the application of blasthole sloping to narrow vein mining in Canada, for ore deposits where widths are less than two metres. While the technique has now been utilized for more than ten years, it remains in the experimental stage and on-site testing is necessary for its adoption at new mining operations or in differ¬ent geological settings. It is intrinsically a safer method than other narrow vein methods in current use.The investigation describes the main operating parameters for mines recently surveyed. The criteria for method applicability are defined and the problems encountered are studied. It is concluded that blasthole sloping for narrow vein mining is a viable modern method which promises to gain popularity and that emerging fragmentation technology and blasting research can be used to further increase applicability of the stoping method."

Jan 1, 1991

By W. Melnyk, L Pokhilenko, J. A. McDonald, A. Hall

The Camsell Lake property comprises 270 000 acres located about 240 kilometres northeast of Yellowknife in the Northwest Territories. Kimberlite has been located in two areas of the property:

Jan 1, 2001

By W. C. Zhu, C. H. Wei, L. L. Niu

With an increase of mining depth, a series of mining-induced hazards such as rockburst, coal and gas outburst, roof collapse, and water burst are getting more serious and more frequent. The intrinsic mechanism responsible for the occurrence of mining-induced hazards is the damage and unstable failure of rockmass or coal seam. The most distinct difference between deep and shallow levels is the so-called three ‘high’ (H3) conditions, i.e. high geo-stress, high fluid pressure and high geo-temperature. Therefore, the response of rock or coal to the deep mining operation is a phenomenon involving thermal (T), hydraulic (H), and mechanical (M) processes. Most importantly, mining excavation may vary the rock stress condition greatly, which may be a key factor to trigger the mining-induced hazards such as rockburst. In this regard, it is of great significance to clarify the damage and failure mechanism of rock and coal under coupled THM conditions, in order to clarify the rock failure mechanism responsible for the occurrence of mining-induced hazards. Thereafter, the mining-induced hazards cannot be predicted with confidence by considering each process independently. Of course, the requirement to include coupling of these processes depends on the specifics of the mining-induced hazards under consideration. For example, the water inrush is considered as a coupled hydro-mechanical (HM) process, in which the unstable failure of rockmass occurs under the combined contribution of geo-stress and water pressure. As for the coal mining at depth, in addition to high geo-stress and gas pressure in coal seam, the high geo-thermal condition that may greatly change the adsorption / desorption of gas and gas flow should be taken into account. Firstly, a general-purpose mathematical model for rock damage and failure process under coupled THM conditions is formulated based on damage mechanics principle, and it is solved by finite element method (FEM). In this model, the deformation and damage of rock, fluid flow and thermal transfer in rock would interact with each other, one process affects and initiation and progress of another. Then, the model is used to predict the mining-induced water outburst, where it is simulated as coupled hydro-mechanical (HM) problems. Based on the numerical simulation, the dimension of water-proof pillar is designed. Finally, the gas drainage from deep coal seam is numerically evaluated, where the coupled coal-gas interaction considering the effect of gas adsorption/desorption, gas flow in coal seam and geo-stress and geotemperature, is comprehensively taken into account. The proposed model could be used for clarifying the mechanism of mining-induced hazards in deep-level mining.

Jan 1, 2015