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By Wei Sun, Xiangsong Meng, Xiaodong Li, Weisheng Huang, Yuehua Hu, Chonggao Cao, Haisheng Han, Wensheng Chen, Runqing Liu, Central South University

"The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work revealed the effect of water glass on the flotation of scheelite by FTIR and the wettability change of the usual cleavage plane, and proved that water glass inevitably influenced the flotation of tungsten minerals to a large extend in traditional fatty acid flotation process. A new collector, benzohydroxamic acid complexes, was found to be selective for the separation of scheelite and calcium minerals with little water glass. Hence a novel flotation process was developed for the recovery of tungsten minerals in shizhuyuan mine in China. Normal temperature flotation of tungsten minerals was developed to instead of the classical “Petrov's process” for scheelite-calcite-fluorite type ores. Compared with the traditional process, the recovery was improved by 10% and the grade of scheelite concentrate was above 55%. The disappearance or decreasing of water glass contributed to improving the recovery of tungsten and fluorite and the circulation of water and reagents.INTRODUCTIONChina is rich in tungsten resources and the proved reserves accounted for 60% of the world's reserves (Cai Gaipin et al., 2009). However the wolframite has been dried up and the scheelite resource has become the main resource of the tungsten metal. Scheelite deposits were classified to scheelite-silicate type and scheelite-calcite-fluorite type based on the associated gangue minerals. Scheelite was easy to separate from the silicate minerals. Flotation separation of scheelite from calcium minerals creates difficulties because of the existence of the same cation in the minerals and similar physicochemical characteristics such as solubility, hardness, specific gravity, PZC (point of zero charge) etc.(Arnold & Warren, 1974; Yongxin & Changgen, 1983; Ozcan & Bulutcu, 1993a; Deng et al., 2015, 2016;). The conventional collectors used in the flotation of scheelite ores are generally fatty acids or fatty acid derivatives ( Yongxin & Changgen, 1983; Oliveira & Sampaio, 1988; Sivamohan, 1988; Shi et al., 2014; Bo et al., 2015). It is difficult to separate scheelite especially from calcite with these reagents because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface (Atademir et al., 1979; Changgen and Yongxin, 1983; Hiçyìlmaz et al., 1993; Hu et al., 2011). Therefore, it is almost impossible to separate them by fatty acid flotation without using any selective depressant. Although oleoyl sarcosine was used as a selective collector in the flotation of fluorite and siliceous scheelite ores (Ozcan & Bulutcu, 1993b; Ozcan et al., 1994), this selectivity is not adequate for a low-grade calcitic scheelite ore. Unfortunately, the reagents such as organic colloids (dextrine, starch), quebracho, sodium phosphates, sodium silicate solutions containing polyvalent cations (hydrosols), etc. (Yongxin and Changgen, 1983; Schubert et al., 1990; Shi et al., 2014; Bo et al., 2015) used for calcite depression also depress scheelite to a large extent."

Jan 1, 2016

By N. Samman, S. N. Lau

"A series of new, grease-based, solvent free open gear lubricants were developed to meet the demanding service requirements of mining equipment. The use of these products has resulted in better performance under conditions of temperature extremes and in terms of longer component lives. They have gained widespread acceptance within the mining communities for such applications as the lubrication of mining shovels, draglines and ball mills.These products are WHMIS non-controlled and are environmentally acceptable. The benefits and advantages of using this type of product to lubricate mining equipment as well as the field evaluation and experience will be discussed."

Jan 1, 2002

By Jiuhua Xu, Yuling Xie, Fenglei Bie, Neng Jiang

"Abstract - The Xiaoqingling Mt. area is one of the most productive gold districts in China. The gold-bearing quartz veins are controlled by a series of east-west shear zones within the Archean Taihua Group, and related to the late Yanshanian (Cretaceous) granite. The major metallic minerals are native gold, electrum, pyrite, galena, chalcopyrite and sphalerite, with gangue minerals dominated by quartz, sericite, ankerite, and calcite. The host rocks are mainly amphibolite, plagioclase gneiss, and migmatites. Principal alteration is sericitization, silicification, pyritization, and carbonization.There are four generations of hydrothermal quartz in altered rocks of gold deposits. The earliest generation of quartz, (Q1), occurs in altered amphibolite gneiss and migmatite, and typically contains fluid inclusions with halite crystals (type A) and two phases, (L+V), of fluid inclusions (type B). The salinities of type A inclusions are 32 wt% to 52 wt%, with dissolution temperatures of halite crystals being from 155°C to 465°C. The second generation of quartz, (Q2), occurs as a fine-grained aggregate associated with sericite, and has small (less than 3 µm) type B inclusions. The third generation of quartz, (Q3), occurs in mylonitic, intensively altered rocks and specially beresite (a type of rock composed of quartz, sericite, and pyrite) near the veins, and contains large amounts of CO2-rich fluid inclusions (type C-fluid inclusions with liquid CO2 and type D-fluid inclusion with high density CO2). The CO2 contents of type C range from 72.6 to 87.4 mol% in gas phases, and 35.7 to 68.3 mol% in liquid phases, based on Laser Raman analysis. The homogenization temperatures of fluid inclusion type A and C are from 215°C to 380°C, and from 210°C to 325°C, respectively. The minimum trapping pressure of fluid inclusions is estimated as 80 MPa to 170 MPa for type A, and from 57 MPa to 190 MPa for type C, which approximate to those of fluid inclusions in vein quartz.The ?18O of quartz are from 10.4‰ to 11.0‰ for Q3 of altered rocks, and from 10.7‰ to 12.8‰ for stage I quartz. The calculated ?18O of fluid inclusions varies from -1.3‰ to 6.0‰. The ?D of fluid inclusions ranges from -67‰ to -59‰ and from -81‰ to -48 ‰, respectively. It is concluded that the water in the hydrothermal fluids both reacting with wallrocks and precipitating orebodies could have been mainly of magmatic and/or metamorphic nature. However, local meteoric water might have been important in late mineralization, because of a distinct oxygen-shift toward the meteoric water. The ?34S values for pyrite of the ores range from -7.1‰ to +7.1‰, with an average of +2.9‰. Those of other sulfides (chalcopyrite, galena, and sphalerite, range from -12.5‰ to 8.3‰. The ratios of lead isotopes for galena of the ores are: 17.06 to 17.31 (206Pb/204Pb), 15.43 to 15.74 (207Pb/204Pb) and 37.58 to 38.45 (208Pb/204Pb). In summary, ore-forming fluids in the Wenyu-Dongchuang gold deposits may have originated from a mantle and/or lower crust source, and ore materials were derived from the Precambrian basement, the Taihua Group."

Jan 1, 1998

By Rong. G., T. Q. Lin, W. Du

Based on analysis of the evolutionary history of the valley in Baihetan, the mechanism of asymmetrical evolution, gradual migration-incision evolved from left bank to the right, is revealed in Baihetan river valleys. The process of in-situ stress evolution is carried out by using the Universal Distinct Element Code (UDEC). Consequently, the numerical results which indicate the main regulations of that stress field are as follow: (1) The phenomenon termed "high in-situ stress fold" appears in the bottom of the valley. With the maximum principal stress being 28-34 MPa, the stress increases significantly at a vertical depth of approximately 130 m. (2) The in-situ stress presents zonal distribution along the bank slope. It is apparent that the in-situ stress field consists of stress relaxation zone (SRZ), stress concentration zone (SCZ) and original stress zone (OSZ). The horizontal depth of stress relaxation zone varies from the left bank (roughly 200 m) to the right (about 120 m). Furthermore, the stress evolution of the left bank slope is studied. As a result, it is found that asymmetrical erosion contributes to the difference of the in-situ stress distribution as a critical factor, between the left bank and the right. And for an asymmetrical valley, the evolutionary process of in-situ stress field is a circular procedure, which includes the incision of valley, the accumulation of landslides and the migration of valley.

Jan 1, 2015

By H. Wotruba, L. von Ketelhodt, M. Kowalzcyk, M. Robben

ABSTRACT Decreasing reserves, water shortages, increasing energy costs, and environmental and social constraints are challenges to the gold mining industry that must be met with innovative machines and methods. This paper introduces the principles of sensor-based sorting and installations that demonstrate the technical and financial viability of the method. The scenarios discussed highlight the potential and advantages of this dry processing technology that requires little infrastructure. Case studies are presented for different ore types using optical- and X-ray transmission–based sorting. Current research is discussed in terms of the potential of near-infrared spectroscopy and X-ray fluorescence sorting for gold applications.

Jan 1, 2013

By T. Hidayat, D. Shishin, V. Prostakova, M. Shevchenko

The chemical compositions of copper feed streams are becoming increasingly complex following the growing demand for metals and corresponding shortages of primary sources. The optimisation of process conditions requires an accurate description of phase equilibria and thermodynamics. Integrated experimental and thermodynamic modelling research program on the characterisation of the complex, multi-component, multi-phase gas-slag-matte-speiss-metal-solids Cu2O-PbO-ZnO-Al2O3- CaO-MgO-FeO-Fe2O3-SiO2-S-(As-Bi-Ni-Sb-Sn-Ag-Au) system is being carried out to support companies undertaking the pyrometallurgical primary production and recycling of copper. The experiments involve high temperature equilibration in controlled gas atmospheres, rapid quenching and direct measurement of equilibrium phase compositions with quantitative microanalytical techniques, including electron probe X- ray microanalysis and Laser Ablation ICP-MS. The thermodynamic modelling is undertaken using FactSage computer package with advanced thermodynamic solution models. The continuing development of research methodologies has resulted in significant advances in research outcomes. Implementation of the results of these fundamental studies involves an ongoing collaboration of researchers and industry technologists. An overview of recent progress in research, implementation and applications in industrial practice are given in the paper. INTRODUCTION Rapidly developing technologies increase the demand for various metals in number and volumes. Modern technological devices such as mobile phones, computers, other electronic devices, have dozens of metals—all those metals have to be a) produced and b) recycled. The fast transition in mobility from fossil energy delivered through combustion to renewable energy first stored in bakeries and delivered through electric engines introduce a significant change in the metal demand in terms of both type and volume of metals. Pyrometallurgy is playing a key role in supporting these changes in our industrialised society.

Jan 1, 2019

By K. R. Brown, P. L. Krawchuk

In-situ recovery (ISR) is under increased investigation as a viable methodology for the extraction of minerals in ore bodies that may be uneconomic to mine by traditional methods or for resources situated in locations where underground and surface mining operations are not feasible. Although the concept of ISR is relatively new with respect to hard rock applications, it is not a new technology; it has been used successfully in potash and uranium mining and also in heavy oil extraction for years where it has been proven to be both technically and commercially viable. ISR allows for the extraction of metals and minerals without the need to mine large amounts of ore that need to be processed at surface. The ore stays in-situ and only the valuable metals and minerals are produced to surface in a process that produces very little to no waste rock or tailings. This paper aims to discuss the geological conditions that make ISR amenable to an ore body as well as the application of maturing technologies such as advanced directional drilling and the creation of artificial permeability that will help to access deep ore bodies and enhance or create favorable recovery conditions for ISR in the ore body. INTRODUCTION In-situ recovery (ISR), also referred to as in-situ leaching, is a potentially disruptive technology for the mining industry. ISR is under increased investigation as a viable methodology for the extraction of valuable minerals that may be uneconomic to mine by traditional methods or for deposits situated in locations where underground and surface mining operations are not feasible. Although the concept of ISR is relatively new with respect to hard rock applications, it is not a new technology; it has been used successfully in potash mining, uranium mining and also in heavy oil extraction for years where it has been proven to be both technically and commercially viable. Recently there has been increased interest in deploying ISR in hard rock applications due to a number of factors: the drive for environmental stewardship is stronger than ever, technological advances in drilling, blasting, and leaching are strengthening ISR economics, and a large inventory of ore bodies exists that are not feasible to mine or extract using conventional open pit or underground mining techniques. ISR allows for the extraction of valuable metals and minerals without the need to mine large amounts of ore that need to be processed at surface. The ore stays in-situ and only the valuable metals and minerals are produced to surface in solution via a recovery process that produces very little to no waste rock or tailings. Where the right conditions exist, the ISR process has a much smaller environmental footprint (Hiam-Galvez, 2018) and potentially much lower capital and operating costs than using conventional mining techniques.

Jan 1, 2019

By R. S. Douglas

Introduction During the past few years, a number of changes in the mine operations at Copper Mountain have taken place. The modernization and mechanization were necessitated and given impetus by wartime and other conditions, which were: (1) The urgent need for copper for wartime purposes. (2) The scarcity of skilled labour for underground work. (3) The increase in labour and supplies cost. (4) The necessity of finding ways and means of increasing the output per man-shift, because of the scarcity of skilled labour and the rising cost of labour. (5) The desire to increase safety measures, reduce the silicosis hazard, and aid mine ventilation. (6) The desire to improve the general working conditions in the mine for all workmen. (7) The desire to reduce the amount of dilution in the ore stream by a more selective yet highly productive method of mining. To this end, mining with diamond drills, and transferring broken ore with slusher hoists, appeared to be the answer to the problem. After considerable discussion and estimation of costs for comparison with those of the operation as carried on at that time, the proposed methods were tried out and, in practice, gave very gratifying results. Reference at this point is made to the paper written by C. H. Brehaut, W. N. Taylor, H. A. Shannon, and R. S. Douglas, which was published in the September, 1945, issue of Mining Technology, by the American Institute of Mining and Metallurgical Engineers, Inc., and subsequently in commercial mining journals. Since that time some improvements have been made in undercutting an orebody - the first through experiment and practice, the second through making use of the earth's barodynamic or gravitational forces. It is the purpose of this paper to describe and discuss these later developments.

Jan 1, 1947

By Dao Dac Tao

The Vietnam coal industry in recent years has achieved the rapid growth. However, in the process of industrialization and modernization of the country, the demand for coal for energy is constantly increasing. This paper presents the Vietnam coal industry in the last stage: the opportunities and challenges facing the coal industry as it strives to become modern, highly effective and capable of meeting the demands of national energy security, all in harmony with socio-economic and environmental needs.

Aug 1, 2013

By S. Shairp

"After cooling and thickening, slurry from the second stage of the Hudbay zinc pressure leach circuit is filtered and washed on a belt filter prior to disposal. At times, the belt filter can be a bottleneck to the process. Preliminary studies show that filterability of the second-stage (HAL) autoclave leach residue can be indicated by particle size distribution of the filter feed and filtered residue cake. In particular, the Volume Weighted Mean Diameter, D[4,3], generated by a laser diffraction particle size analyzer from samples of HAL Filter feed, shows residues that filter more poorly have a lower Volume Weighted Mean Diameter than those that filter better. INTRODUCTIONHudbay produces cast zinc metal from blends of zinc concentrates at its metallurgical complex in Flin Flon, Manitoba, Canada, using Sherritt’s two-stage pressure leach process (Collins et al., 1994; Collins et al., 1995; Barth et al., 1998; Shairp et al., 2006). Pressure leaching replaced the original roastleach- electrowinning process in 1993.Filtration for the second-stage (HAL) leach residue originally consisted of two stages of vacuum drum filtration with intermediate cake repulping stirred tanks. As part of Hudbay’s 777 Project, with a designed increase in cast zinc production, a pre-feasibility study by SNC-Lavalin Inc. showed that losses of soluble zinc in the zinc pressure leach residue could be reduced by installing more efficient filtering and washing equipment. Based on laboratory performance, capital cost, installation ability, and potential operating cost savings, a 70 m2 Filtres Phillipe belt filter was chosen for the HAL residue, and commissioned in 2000/2001.When the HAL belt filter is performing well, there is no pooling of water on the surface, moisture content is relatively low, and subsequent analysis shows that water soluble zinc content is relatively low. There have been occasions where the filter has performed poorly with respect to the aforementioned parameters. Aside from the filter experiencing mechanical difficulties, there are several variables affecting leach residue filtration:"

Jan 1, 2012

By J. P. Mogan, E. D. Dainty, K. Katsuyama

"The Volvo BM 861 U articulated truck is one of the few underground diesel units manufactured by an organization which shares the same corporate roof as the engine manufacturer. As a consequence, the unit has provided an opportunity for the characteristics of the entire system- turbocharged aftercooled engine, transmission and exhaust scrubber- to interact to minimize emission levels. The performance of the components of the system, as evaluated by full-scale dynamometer testing, is summarized. The over-all effect of the various innovations was a 38% reduction in the recommended ventilation level over that of the bare engine.IntroductionThe Mining Research Laboratories of Energy, Mines and Resources Canada is required, as part o f the certification service of the Canadian Explosive Atmosphere s Laboratory, to test the exhaust emissions of diesel engines, and to recommend appropriate amounts of fresh ventilating air to minimize the risks to health of underground personnel working with, or in the vicinity of, such diesel engines. Volvo BM AB of Sweden made application for the certification of the BM 861 U truck during a period in which EMR personnel were engaged in a number of research projects concerned with improving the environment in dieselized mines. One such avenue of research was the venturi or high-energy scrubber; as the BM 861 U was equipped with this type of scrubber , EMR and Volvo BM agreed to cooperate in a considerably more extensive investigation than would be normal for a certification application. The outcome of some of this research is summarized in this paper."

Jan 1, 1981

By R. J. Mitchell

"A lest apparatus has been developed for obtaining the relations among confining stress, porosity and percolation rate for hydraulic sand backfills. The apparatus can also be used to evaluate internal drainage characteristics and the effects of partial saturation on percolation rates. The test apparatus, test procedures and typical test data are presented in this paper.IntroductionAlthough the standard percolation test has become an accepted method of evaluating the drainage characteristics of hydraulically placed tailings backfill, it is recognized that the test results require considerable interpretation due to the following factors: (I) The results can be markedly influenced by varying sample preparation procedures, which vary the amount of material segregation in the sample . In particular, a thin layer of slimes on the top of a sample can control the flow of water into the sample. Wall edge effects can also affect the test results. (2) The in-place porosity of the backfill is not duplicated in the test sample and empirical formulae must be used to estimate the variation of percolation rate with porosity. (3) Internal drainage characteristics and the percolation rate of partly saturated fill cannot be evaluated in the standard percolation test.In addition to eliminating these problems, the compression percolation test apparatus also provides additional data on the mechanical properties of the backfill. Compressibility (or bulk modulus) is measured at different stress levels during the course of a test and this information can be used in evaluating the usefulness of the fill in providing ground control and in limiting ground subsidence. The engineering design of mine backfill is becoming an important part of the over all design of underground mine operations. The design problems are sufficently different from conventional civil engineering soil mechanics problems that new test methods and design procedures are required."

Jan 1, 1981

By Jie Li, Xinyu Liu, Yan Chen, Linjian Ma, Yasong Wang

Nonlinear time-dependent response analysis of salt cavern under extreme loads in disaster mode is of great importance to the safety and disaster prevention of gas storage group. Uncontrolled blowout is one of the extreme conditions for compressed-air cavern operation. Based on the geological structure of Jintan salt deposit, China, the numerical model of the complete process of water solution, cyclic operation, and internal pressure runaway was developed. The effects of rapid unloading on the stress filed, the progressive failure of surrounding rock, the volume convergence of storage cavern, and the ground subsidence were simulated employing an elasto-viscoplastic damage constitutive equation for rock salt. The results indicate that the damage and failure zones propagate much larger in the mudstone interlayer than in the host salt. The volume of damage and failure zones surrounding salt cavern induced by unloading process is 5~6 times that of cyclic injection and withdrawal process. The average volume convergence rate of salt cavern reaches 0.012%/d~0.013%/d, which is 6~6.5 times that induced by cyclic operation. The ground subsidence exhibits a typical funnel curve. The affected region of ground subsidence due to rapid unloading in the blowout period is about two times the maximum cavern diameters. Furthermore, double cavern analysis reveals that the interaction between adjacent caverns may be ignored so long as the pillar width is larger than two times the maximum cavern diameters.

Jan 1, 2015

By Kenneth L. Norris

Stonegate Agricom Ltd. is currently conducting exploration and development drilling of the Paris Hills Phosphate Project (Paris Hills Project) located in Bear Lake County, southeastern Idaho, 3.2 km west of the towns of Paris and Bloomington, Idaho. The project is located adjacent to a highway and 19 km by paved highway to Montpelier, Idaho where the Union Pacific Railroad system is located. Power and water are available locally. The nearest metropolitan centre is Salt Lake City, Utah approximately 225 km by road to the south-west of the property. The Paris Hills Project encompasses an area of approximately 856 hectares. Property holdings consist of three (3) patented lode mining claims and 16 contiguous fee parcels (some with federal phosphate leases). Active open pit phosphate mining operations are located in surrounding counties in south-east Idaho and are owned and operated by Agrium Inc., Monsanto Company and J.R. Simplot Company. The Paris Hills Project is located near the centre of the Western Phosphate Field which constitutes the most extensive phosphorite beds in the United States. Phosphate beds of the Western Phosphate Field occur within the Phosphoria Formation of Permian age and extend over an area of more than 350,000 km2 including extensive areas of Idaho, Utah, Wyoming and Montana. At Paris Hills the phosphate mineralized beds occur in the overturned limb and the horizontal limb of the Paris Syncline. Grades and thicknesses in both the western overturned limb and the eastern horizontal limb of the anticline are similar. The vast majority of potential mineralization occurs in the horizontal limb which underlies most of the property holdings. Mineralization in the overturned limb has a strike length of over three (3) kilometres and extends from the surface to a depth exceeding 300 m depending on location along the north-trending strike of outcrops. Depths of the horizontal limb range from surface along the north side of Bloomington Canyon to estimated depths of 915 to 1,035 m at Paris Canyon. The property contains an Inferred resource of 109.6 million tonnes at 23.6% P2O5 over two mineralized horizons. The phosphate zones have a strike length of over 3 km and extend from surface to a depth of at least 900 m. Drilling commenced late in the 3rd quarter of 2010 and is planned to continue through 2011. The drilling was planned to target an area of potentially higher grade phosphate mineralization and better define and upgrade the current resources.

May 1, 2011

By M. Cossette, P. C. A?tcin

At present there is considerable confusion in the asbestos industry with regard to density and porosity measurements of asbestos. In order to clarify the situation, various notions of porosity and density are defined by means of simple schemes and clear symbols are proposed to denote them. An experimental procedure is then preposed and outlined, which is based upon Archimedes' principle. Experimental conditions at each stage of the method are explained clearly in order to minimize the opportunity for errors. Finally, the results of a study on the porosity and density of asbestos minerals having various characteristics are presented.

Jan 1, 1972

By S. Nikolic

"Calcium ferrite slags are currently used in a number of copper-converting processes. Despite the industrial importance of this system the phase equilibria have not been fully investigated. Characterization of this slag system is necessary to improve the control of process parameters, including fluxing and operating temperatures. Recently, a modified experimental method has been developed; this involves rapid quenching of slag samples equilibrated at high temperatures with the resulting phase assemblages analysed using electron probe microanalysis (EPMA). In the present study, experiments were completed under controlled temperatures and oxygen partial pressures using CO/C02 or H2/C02 gas mixtures. The investigated slags were supported during equilibration by a substrate of the primary phase. This technique removes the limitations arising from the use of crucibles and facilitates rapid quenching of the melt. Experiments were carried out at 1200°C and 1250°C (1473 Kand 1523 K) and in the composition range 0-40 wt.% Cu20, 0-25 wt. % CaO and 45-80 wt. % Fe203. Liquidus and solidus data are reported for the primary phase field of spinel between the oxygen partial pressures of 10-4.5 to 1 o- 6-5 atm. The analyzed compositions of liquids and solids are used to construct the phase diagram of ""Cu20"" -CaO-""F ez03"" system in equilibrium with metallic copper at fixed oxygen partial pressures."

Jan 1, 2007

By F. McCarthy, R. McDonald, G. Woodbridge, G. Brock, D. Robinson

"The Direct Nickel process is a hydrometallurgical technology being developed to treat nickel laterite ores by leaching at atmospheric pressure. The leaching process uses nitric acid in a relatively large excess, is thus non-selective, and much of the soluble iron goes into solution. The first stage of solution purification is iron hydrolysis and the Direct Nickel process utilises the colligative properties of the pregnant leach solution (PLS) to enable the removal nitric acid of varying concentrations via distillation. Once sufficient acid has been removed, the boiling point of the solution is increased allowing high temperatures (up to ~170°C) to be achieved under atmospheric pressure. The higher temperatures initiate the precipitation of the iron primarily as hematite and allow the removal of the acid generated by the hydrolysis reaction. The rejection of the iron is near complete with solution tenors typically falling from 65 g/L Fe, or more, to less than 50 mg/L Fe. The separation of clean nitric acid from the PLS at this stage allows for relatively simple acid recycling. A hematite product with iron content above 60% could also provide an extra revenue stream.INTRODUCTION The Direct Nickel (DNi) Process is a novel hydrometallurgical processing route designed to treat all types of nickel laterite ores in a single flow sheet using nitric acid under atmospheric conditions. A simplified flow sheet is shown in Figure 1.Between 2007 and 2012 the process was developed and refined at Direct Nickel’s laboratory within the CSIRO Minerals’ facilities in Perth, Australia, and in 2013 a series of pilot plant trials were run under continuous operating conditions. The process is designed to treat both limonite and saprolite in the same flow sheet, and after comminution, the blended ore is mixed with nitric acid and leached just below boiling point in agitated atmospheric leach tanks. The acid is added in excess, so typically for a blend of limonite and saprolite the acid addition can be in the order of 1.8-2.0 t acid/t dry ore. After a residence time of between 4-6 hours the majority of the soluble metals have leached into solution and the insoluble leach residue is separated from the pregnant leach solution (PLS) via counter-current decantation."

Jan 1, 2016

By G. Lucas

"Material substitution occurs continuously in response to competitive and economic pressures. Technical development can accelerate or slow substitution by improving the performance of the invading or defending material. The choices are seldom simple and have to be made in the context of continuous commercial change.The development and commercialization of a new aluminum material is examined. The material has been introduced into· several different markets, so it is possible to compare and contrast the degree of success obtained in each.IntroductionAluminum-based materials have been in use for over one hundred years and , therefore, the development of a new family of alloys is rare. In the early 1970s, Dr. L.R. Morris and his coworkers at Alcan' s Kingston Research Centre started work on what was, at the time, something of a scientific curiosity-a family of alloys strengthened by an unusual mechanism.This paper deals with the development and commercialization of what became known as the Alcan 255 alloys"". These alloys have found uses in several markets, usually as improved substitutes for existing materials. Forecasting the usefulness of a substitute material in an existing marketplace is difficult, in part, because even material users are seldom able to specify precisely their requirements. This uncertainty can cause the failure of some substitutions but can also lead to opportunities which were not initially obvious.Technical BackgroundPure aluminum is a soft, weak material. It can be strengthened by the addition of various alloying elements and by work hardening. Alloying elements usually act by forming solid solutions which are stronger than the pure metal or by precipitating during heat treating or aging and so preventing the easy movement of dislocations during deformation. Elements which can perform either role had been investigated for decades and were thought to offer little chance of technical breakthrough in 1970. An outgrowth of the then new and exciting research on directional solidification seemed, however, to offer such promise.Some aluminum-iran-manganese alloys will solidify under certain conditions as 'coupled growth' eutectics (Figs. I and 2). The microstructure shows one phase growing as long rods through the other. This is an uncommon structure and it was investigated to see if it had equally unusual properties. On deformation by rolling the rods were broken up into small equiaxed , evenly-spaced particles (Fig. 3). Materials with this structure were found to be stronger than other alloys with similar amounts of alloying addition, and to resist thermal softening remarkably well. This combination of properties was thought initially to be due directly to the particles by a dispersion strengthening mechanism, but later this was found not to be strictly true."

Jan 1, 1987

By H. Qi, J. L. Feng, D. J. Li

"In the present paper, the characteristics of the granite burst under loading/unloading conditions was studied by means of both laboratory experiment and finite-discrete element method (FDEM). After gaining the mechanical properties of the granite samples under uniaxial compression conditions, the parameters taken as input arguments in the FDEM modelling were then carefully calibrated so as to provide some basic data including Young’s modulus, Poisson’s ratio, uniaxial strength, Lame constants, cohesive strength, and frictional angle for further being used in simulating granite bursts. All the simulating results by the FDEM were basically in agreement with that obtained from the uniaxial compression test and triaxial granite bursts in laboratory, respectively. This study shows that that such computational mechanics of discontinua can be employed to gain powerful insight into the failure mechanism of granite burst, which could also be a useful tool to clarify the collapse mechanism of rock structures in rock engineering design and rock test scheme optimisation. INTRODUCTIONBased on discontinuum state a priori, discontinuous modeling techniques that are commonly referred to as discrete element methods (DEM) treat the material directly as an assembly of separate blocks or particles, which was originally proposed by Cundall (1971) and Cundall and Strack (1979) from the viewpoint of analogous molecular dynamics simulation to better account for and understand the interaction between the blocks. The distinct feature of these formulations is that a constantly changing problem of geometry and contact conditions can be addressed by solving the equations of motion using an explicit time marching scheme (most often in a ‘leap-frog’ format), while updating contact force histories as a consequence of contacts between different discrete elements and/or resulting from contacts with model boundaries (Bicanic 1998). The most notable implementations of DEMs are arguably represented by the universal distinct element code (UDEC) (Itasca Consulting Group Inc., 2013) and the particle flow code (PFC) (Itasca Consulting Group Inc., 2012). Another formulation is the discrete crack framework that is based upon some criteria for an advancement of crack front, which is coupled with extensive local and global re-meshing while simulating by numerical methods such as finite element technique, commonly using fracture theories. Certainly, it is relatively easy to trace the propagation of single crack front governed by some principles of energy release rates (Ingraffea 1997) but tracing of multiple cracks leads to topological and algorithmic complexities. Otherwise, there is no consideration of interacting cracks in these formulations of finite element or enhanced finite element techniques (e.g., in XFEM and ABAQUS)."

Jan 1, 2015

By M. S. Badollet

"IntroductionASBESTOS FLOATS may be defined briefly as blends of air-borne particles of fibrous asbestos and dusts produced during the milling stages and collected by Cottrell precipitators, dust sheds, or bag-houses.The various grades of asbestos floats on the market contain fibrous asbestos particles ranging in length from microscopic to approximately 1/4-inch. The fines or dusts present in the floats are from 40 microns to 2 microns or less in cross-section.Airborne asbestos particles are of diverse length because they are collected at numerous places in the mill. There are: (1) dusts removed from dry rock storage bins, (2) dusts removed from rock and fiber screens, (3) particles from the tops of collectors, and (4) fines removed by suction from the processing equipment. Sometimes the airborne particles are kept segregated, so that there is a partial separation by gravity. This is accomplished by a series of dust chambers enclosed in a long, rectangular building. The longest and heaviest particles fall nearest to the air flow entrance, the smallest at a point farthest away and nearest the exit. Sometimes the air from the dust chamber building is passed through a series of bag-houses or electric :precipitators ,to collect the extremely fine particles which normally escape to the atmosphere."

Jan 1, 1952