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By R. I. Kraydenko, A. N. Dyachenko

"The possibility of SiO2 5N production by staged purification of ammonium hexafluosilicate (NH4)2SiF6 is discussed. High-purity silicon dioxide can be obtained with fluoridation of quartz concentrate by solid NH4F at 100 °C, with further sublimation of the product at 320 °C, its dissolution, ammonia hydrolysis, filtration and drying of SiO2•nH2O. This is accompanied by regeneration of the processing reagent - NH4F.INTRODUCTIONProduction of high-purity silica-5N (SiO2 content over 99.999%) is an important and urgent task of the modern chemical industry. This material is used in the manufacture of optical glass, optical fibers for internet cables, silicon for solar power and electronics.Quartz concentrate is raw material for the production of silicon dioxide. The existing technologies of synthetic silicon dioxide were introduced in the mid-twentieth century. These methods are energy-consuming, multi-step and do not meet stringent environmental requirements. In fact, as some conventional technologies became obsolete; it became necessary to develop new methods for the production of synthetic silica. We believe that the fluoride technology of processing of quartz materials by ammonium fluoride is the most promising direction.In industry, silicon dioxide marked ""Silica White"" is obtained by liquid-phase method. The method consists of the precipitation of amorphous silica from sodium silicate solutions with acids. The resulting product is filtered, washed and dried. Depending on the deposition conditions and nature of the coagulant the ""Silica White"" is acidic, neutral or alkaline. The dry product is subjected to grinding. The degree of dispersion and porosity of the particles of Silica White depends on the nature of decomposition agent (a substance that decomposes the silicate) and coagulant, conditions of sedimentation, filtration and drying. During the drying process the silica particles are sintered into aggregates of a few millimeters."

Jan 1, 2012

By C. M. Acuna, M. Sherrington

In high temperature processes thermodynamic equilibrium is assumed and therefore chemical potential of elements, among the condensed phases, have to be the same. In such situation impurities distribute accordingly and their fractional distributions are affected by the masses of the coexisting phases. It has been claimed Teniente Converters perform quite well for smelting high impurity concentrates, especially in respect to volatilization and/or slagging. Production of high matte grade near white metal composition, requiring moderate oxygen enrichment in the process air, results in a huge mass of gas and therefore a high fraction of impurities report to it. Similarly, by recycling different sources of slag, flue dust or other materials, the mass of the final slag is increased and so do the masses of impurities reporting to the slag. Nevertheless, above a certain level the recycling of smelter byproducts is no longer feasible and the cycle has to be halted, unless higher impurity mattes are accepted. Although the process might be continued during converting and refining, lengthy and expensive measures have to be taken if suitable anode copper for electrolytic refining is to be achieved. In the present study samples of high arsenic matte grade and slag were obtained on a pilot scale. The matte samples, on the order 75%Cu, were equilibrated with slag at varying ratios in magnesia crucibles under CO/C02 atmospheres at 1523 K. After 24 hours equilibrium matte and slag were rapidly solidified and analyzed by copper, sulfur, iron and arsenic. Furthermore, industrial samples of matte and slag, in the order 75%Cu at 1523 K, were obtained via a special quenching sampling device to determine the association of copper and suspension of matte and copper in slag. Based on the results, the distribution coefficient of arsenic between slag and matte was evaluated along with copper species in slag and the fractional distribution of arsenic, in the coexisting phases, was determined as a function of the ratio mass of slag to mass of matte.

Jan 1, 2007

By R. P. Kofluk

The nickel-cobalt sulphides produced from limonitic laterite ores by Moa Nickel S.A. in Cuba are refined at the Corefco nickel-cobalt refinery in Canada. Significant economic implications are associated with the refining of precipitated sulphides containing elevated iron contents. The Moa Nickel S.A. operations encompass laterite mining, high pressure acid leaching (H PAL), and ultimately, precipitation of a mixed sulphide product. These processes are reviewed as they pertain to the control of iron and the formation of a mixed sulphide containing nominally 55% Ni, 5% Co and 1% Fe. The contributors to the iron content of the mixed sulphide product are reviewed; the major contributors are the HPAL operation and sulphide precipitation. The precipitation of iron during sulphide precipitation is influenced by the solution acidity, the iron and copper concentrations in the feed solution, and the presence of laterite leach solids. The significance of the copper concentration of the sulphide precipitation solutions is manifested by both physical and chemical modifications of the sulphide precipitates, presumably through the formation of fine copper sulfide seed particles.

Jan 1, 2006

By C. Allen

In 2004, Boliden Odda underwent an extensive modernisation project targeting mainly the leaching section of the plant. Direct leach technology was introduced as part of this project. The Direct Leach process, developed by Outokumpu, is an atmospheric oxidative leach of zinc sulphide concentrate. The effects of this new processing operation on behaviour of iron in the plant are discussed. As well, the filterability of the new residue on belt filters prior to its deposition in mountain caverns is also discussed. The solids from the direct leach process have been analysed by scanning electron microscopy, and the results of these analyses are presented.

Jan 1, 2006

By José J. Suárez

Abstract: Globally, the mining industry is expected to face the following challenges through 2020: 1. Sustaining growth amidst fierce competition 2. Containing cost increases and managing through the cycle 3. Attracting and retaining talent 4. Managing environmental concerns and improving sustainability 5. Managing volatility risks in commodity markets Our experience and research reveals that the higher performing global miners are adopting many of the following strategies: (1) Adopt a Global, Agile Operating Model (2) Be the Developer of Choice (3) Drive Capital Efficiency (4) Be the Employer of Choice (5) Integrate the End-to-End Business Model (6) Move to the Virtual Mining Value Chain This paper/presentation will provide data obtained through research on five (5) challenges facing the mining industry, and on the six (6) strategies that high performing global miners are adopting.

May 1, 2013

By L. Zeng, Q. Feng, Z. Qiu, L. Ou, Central South University

It is well-known that the use of nanobubbles can significantly improve the flotation efficiency of ultra-fine particles. However, this is mainly focused on coal and phosphate rock flotation. In the field of nonferrous metal processing, the related research is few. In this paper, a small laboratory mechanical cell associated with a specially-designed nanobubbles generator was used to investigate the effects of nanobubbles on enhancing ultra-fine scheelite flotation. Nanobubbles were created and based on the hydrodynamic cavitation principle through Venturi tubes. Comparative flotation tests were performed using different tubes to evaluate the nanobubbles impact on the ultra-fine scheelite particle flotation recovery. In order to better understand the nanobubbles enhanced ultra-fine scheelite flotation, nanobubbles potential and size distribution were measured. The effect of nanobubbles on the particle aggregation and scheelite particles potential were also studied through the turbidity tests, microscope tests and zeta potential measurements. According to the results, the mean size of nanobubbles was about several hundred nanometers, and the surface of nanobubbles was of highly negative charge in alkaline conditions. The flotation recovery of ultra-fine scheelite particles was increased in the presence of nanobubbles. The zeta potential measurements indicated that the repulsive forces between scheelite particles decreased when nanobubbles existed. Through the turbidity tests and microscope tests, the promotion effect of nanobubbles on particle coagulation could be verified more directly. The existence of nanobubbles in flotation system promotes the particle aggregation, thus increasing particles apparent size and particles capture by bubbles, which may be the fundamental reason why nanobubbles enhance ultra-fine scheelite flotation.

Jan 1, 2016

By Qing-hua Tian, Xue-yi Guo, Fei Li

A novel process for the preparation of a-Al2O3 from secondary aluminum dross was studied. Factors including alkali dross ratio, salt dross ratio, smelting temperature, smelting time, leaching temperature, leaching time, and the solid-liquid ratio, which possibly influence the transfer of Al into water were studied, and the feasibility of using seed precipitation as a treatment technology of the leachate was discussed. The optimum condition of the process was determined as: alkali dross ratio 1.3, salt dross ratio 0.7, smelting temperature 500°C, smelting time 60min, leaching temperature 60°C, leaching time 30min, solid-liquid ratio 1:4. The results show that using the seed precipitation method, the leaching of aluminum reaches 92.71%, demonstrating the technique as a feasible and effective treatment technology of the leachate.

Jan 1, 2011

By P. A. Distin, Jr. da Silva

The history of commercial processes for zirconium/hafnium production and separation is reviewed. A new technology is then proposed as a potential alternative for zirconium/ hafnium separation in a simpler, cleaner way than achieved with current processes. Primary sources of zirconium always contain small amounts of hafnium that must be removed during production of zirconium metal for nuclear applications. This separation is usually carried out by a solvent extraction process, developed in the 1950s, that selectively extracts hafnium, as a thiocyanate complex, using methyl isobutyl ketone (MIBK). Environmental problems inherent to this process are the high aqueous solubility and low flash point of MIBK, and possible gaseous contaminants formation generated by the decomposition of the thiocyanic complexes in hydrochloric acid medium (H2S, HCN, mercaptan’s formation). The present work shows how these problems could be avoided by using organophosphorous extractants that were unavailable when the MIBK process was developed.

Jan 1, 1998

By L. P. Srivastava

Rock bolts have been used since long to enhance the shear strength response of jointed rocks in civil and mining engineering structures. However, the assessment of strength response of a rock mass reinforced with rock bolts remains an unresolved problem till date. In the present article, an attempt has been made to study, through physical model tests, the shear strength enhancement of a blocky mass due to provision of passive rock bolts. Direct shear tests were conducted on large specimens of size 750 mm x 750 mm x 900 mm of rock mass under a normal stress varying from 0 to 2.0 MPa. Concrete was used as a model material to simulate intact rock and, elemental blocks of size 150 mm x 150 mm x 150 mm were used to form the mass specimens. Steel bolts of 6 mm diameter with 2 mm thick grout were used to reinforce the mass. Three different configurations of bolts were adopted. Observations were made on shear stress, horizontal shear displacement, and dilation during the tests. Effect of normal stress and reinforcement on peak shear stress and shear stiffness was studied. It is observed that the rock bolts enhance the shear strength of the mass by preventing sliding along the shearing plane, and by inducing additional normal stress due to tension mobilized in the bolts. The rock mass, therefore, becomes stronger due to the high degree of interlocking produced by the bolts. Shear strength of the mass increases with increasing numbers of bolts. In the case of reinforced mass, the enhancement in shear strength due to provision of bolts decreases with an increase in normal stress. The provision of bolts improves the cohesion of joints substantially. The effect on friction angle is low. The shear strength enhancement depends on the area of the bolts, spacing of the joints, spacing between the bolts and the cohesion of the intact material. A correlation has been established using which the enhancement in shear strength due to the provision of bolts can be assessed.

Jan 1, 2015

By O. D. Maurice

"This paper will essentially update the information that is already known and published on the limestones of the Province of Quebec. The excellent report by M. F. Goudge (1935)m is difficult to improve upon and the areas of limestone quarrying are generally the same as they were at the time of Goudge's report. Our knowledge of the limestones of Quebec has been improved considerably in recent years by the publications of T. H. Clark, 2 who, since 1938, has been mapping and reporting on these lime-stones and has discussed their stratigraphy, their structural features, their history and their economic value. One economic aspect is the presence of natural gas in these formations and the possible occurrence of oil. A total of 150 test holes had been drilled to a depth of more than 500 feet by the end of 1967 and, in addition, at least 256 more shallow holes had been put down in the St. Lawrence Lowlands. The information from these test holes has greatly improved our knowledge of the thickness and extent. of the various formations of Paleozoic limestone and shale in Quebec.This paper will then review briefly the limestone occurrences in Quebec, using the old as well as the more recent reports as principal references"

Jan 1, 1970

Abstract - A method to extract certain types of error variance information from paired data is presented, which constitutes an important tool for the calibration of Gy’s formula for variance predictions in the sampling of broken ores. The research summarized here complements publications by others on geochemical precision. The model and method proposed for treating duplicate data provide a practical means of deriving separate estimates of the purely analytical and aliquot sampling variances, from a unique set of duplicate assays, and, hence, proposes a new avenue for estimating effective mineral grain size.

Jan 1, 1998

By Werner W. Scholz

A corrosion-resistant lining is, quite often, selected on the merits of its corrosion resistance only. This paper demonstrates the effects of temperature, pressure, weather, design aspects and variances of physical properties within the scope of the generic designation of a corrosion-resistant material or materials. The base for the study is a rubber- and brick-lined steel vessel, with unchanged chemical conditions. Graphs and sketches illustrate the various effects of physical influences on the selected lining specifications.

Jan 1, 1979

By A. J. Pearce

MOST mines have a model of some kind to illustrate either geological structure, mining operation, or some special condition or feature of the property. The type used depends on the particular feature or use for which it is intended. At Dome Mines we have developed an interesting and practical application of the horizontal-type model. This model shows the workings of each level horizon plotted on glass. These glass panes are set in frames which, in turn, rest on drawers equipped with rollers which can be pulled out as desired into a light chamber. The features of this model are its rigid steel construction and that any desired number of level plans can be pulled out, eliminating any other interference from other levels. Figures 1 and 2 are photographs of the model cabinet and show its construction and general features. The cabinet is of steel construction with the following overall dimensions: width, 6 ft. 5 in.; depth, 6 ft. 7 in.; height, 5 ft. 2 in. When not in use it can be completely closed-in, making the cabinet practically dustproof. There are 30 drawers, one for each of the 29 levels and one for the surface. The glass in each drawer is divided into two panes, 36 in. by 36 in., of flatdrawn double-diamond 'lustraglass' with about l/32 in. between adjacent edges. The panes are held rigidly in the frames, which are lined with felt strips, and may be adjusted by set screws, four of which on each drawer are shown in Figures 1 and 2. The level workings, on a scale of 1 inch equals 100 feet, are traced in ivory black Windsor & Newtons artist oil paint. Co-ordinate lines are shown in crimson lake, and main geological contacts are shown in their respective colours. Figure 3 is a photograph looking down on one of the levels. The lighting consists of 14 30-watt fluorescent bulbs, with reflectors, under frosted glass. These lamps are much more satisfactory when operated by 60-cycle rather than 25-cycle and, as we had available nearby a source of direct current, this was used. The electrical unit consists of a rotary converter from d.c. to 60-cycle. This arrangement gives perfect lighting, allowing most colours to be easily distinguished. Figure 1 was photographed using this source of light, Figure 2 using an outside floodlight.

Jan 1, 1945

By S. Parkash, A. J. Szladow

Vigorous agitation of suspensions of coking coals in water (or light mineral oils) will often result in catast rophic loss of caking properties. It is shown that this deterioration is not a consequence of oxidation of the coals (by dissolved oxygen), but that it can be qualitatively connected with internal "solid-state" reactions which appear to derive their activation energies from cavitation of the liquid.

Jan 1, 1971

By O. Hyvärinen

Outokumpu has developed a new chloride leaching process called HydroCopper®. In this process copper sulfide concentrates are leached at atmospheric pressure in concentrated sodium chloride solution using cupric ions as the oxidant. Copper is recovered from the purified leach solution by precipitating cuprous oxide, which is then reduced to pure copper and further melted and cast directly into copper products. The key reactants: sodium hydroxide, hydrogen and chlorine are generated from the spent sodium chloride using chlor-alkali technology. An important feature in the HydroCopperTM process is that the gold contained in copper concentrates is leached as chloride complexes and recovered from solution by activated carbon. Conditions for the leaching of gold-bearing pyrite can also be achieved in the chloride system by optimizing the redox conditions. This paper deals with the basic factors affecting gold leaching from copper sulfide concentrates. Opportunities for the recovery of refractory gold associated with arsenopyrite and pyrite will also be discussed.

Jan 1, 2005

By A. C. Ter-Oganesyants, N. N. Anisimova, G. P. Kotukhova, G. N. Dylko

The process utilized at Norilsk Nickel Polar Circle Division for treating slimes from the electrorefining of copper and nickel was developed in the late nineteen fifties and has survived without any fundamental changes. This technology is a combination of pyro and hydrometallurgical operations to produce PGM concentrates that are sent away for refining. The characteristic feature of the current technology is multiple-stage, extended cycle treatment with significant incomplete production, low labour and automation efficiency and poor hygiene and sanitary conditions. To eliminate all negative aspects mentioned above, specialists of Norilsk Nickel Polar Circle Division have developed a new hydrometallurgical process for treating electrolytic slimes. The main steps of the flow sheet developed are autoclave leaching of the slimes and electrochemical opening-up of a cake from autoclave leaching. The implementation of the new process will allow Norilsk Nickel Polar Circle Division to shorten the process cycle 4-5-fold thus reducing the volume of incomplete production, considerably increase labour efficiency, simultaneously improving working conditions, upgrade the final concentrate, reducing costs and increasing PGM recovery during refining and, ensure higher security of precious metals by employing automated processes and vacuum sealed units.

Jan 1, 2004

By M. Reda

Because of the adverse environmental effect of Chromate, Molybdate ions had been investigated as replacement for Chromate and the results had shown not to be encouraging. Film deposited from peroxopolymolybdate (from reaction of Molybdenum meta, with excess Hydrogen Peroxide), are more robust than that deposited from molybdate solutions. This was shown to be due to higher fraction of Mo (IV) and Mo (V) that form from Mo (VI) in the peroxopolymolybdate deposited film than the film deposited from Molybdate solutions. The peroxopolymolybdate film contains 40% un-hydrated molybdic acid, tetraperoxodimolybdate and tetra peroxo tetra molybdate. The protective properties of peroxopolymolybdate were shown to be due to the effectiveness of the un-hydrated molybdic acid.

Jan 1, 2010

By Jie Deng, Wenliang Xiong, Binyan Chen

"With falling rare earth metal prices, low cost beneficiation of rare earth minerals is essential. The “Flotation-Agglomeration-Magnetic” (FAM) separation process is a newly developed technology by IMUMR to economically recover rare earth elements from different types of deposits. The theory of FAM process is to selectively agglomerate rare earth particles and separate from gangue minerals by bubble flotation process. The flotation product is further upgraded by magnetic separation. The FAM process has been successfully applied in industrial production on the Dalucao rare earth ore, Sichuan, China. The average REO grade of rare earth concentrate is 65% in the latest 12 month production run, with an average recovery of 55%.INTRODUCTIONRare earth elements (REEs) include fifteen lanthanide elements coupled with two chemically similar elements (yttrium and scandium). These elements are split into two sub-groups, La to Sm are classified as light rare earth elements (LREEs) and the remaining elements including yttrium are heavy rare earth elements (HREEs) (Kumari & Panda, 2015). The demand of rare earth elements surged in recent years due to their increasing usage in diverse industrial aspects including high strength magnets, phosphors, clean energy, polishing compounds and catalysts (Goley &Scott, 2014).More than 250 REE-bearing minerals have been discovered, but many minerals are with very low concentrations of REEs, varying from 10-300 ppm (Adam &Ping, 2013). The most common rare earth minerals mined are bastnaesite, monazite, xenotime and ion-adoption REE (Chelgani & Rudolph, 2015; Kanazawa & Kamitani, 2006). Before the 1960s, most rare earth resources were extracted from monazite in the beach placer, with the exploiting of Mountain Pass in the United States and Bayan Obo mine in China, bastnaesite became the chief mineral source of rare earth resources (Klinger, 2015). These minerals are commonly separated with gangue minerals by froth flotation, gravity concentration, magnetic separation, or any combination thereof based on their specific physical characteristics (Zhou & Wang, 2014; Adam & Richard, 2014; Yang & Satur, 2015; Xia & Brian, 2015a,b)."

Jan 1, 2016

By M. Grenon

"The presence, size, orientation, nature, and persistence of geological discontinuities dictate the behaviour of a rock mass. Block size, which is defined by discontinuity spacing, by the number of joint sets, and by the persistence of the discontinuities delineating potential blocks is an important indicator of the degree of fracturing of a rock mass. Consequently, block size is represented either explicitly or implicitly in all rock mass classification systems employed for analysis and design of surface and underground mining structures. Insitu block size distributions may provide a better means to describe the structural complexity of a rock mass. These are the distributions that would be derived if the in-situ rock mass was separated into its constitutive blocks, delineated by existing discontinuities, and each block measured. This paper presents the results of a field campaign at Louvicourt Mine aiming to characterize the rock mass using different methods for determining block size and block size distributions. IntroductionGeological structural data are used to provide input data for analysis and design methods for surface and underground structures. As the collection of structural data involves considerable investment of time and effort, it is sometimes overlooked, thus denying an important source of information for mine design. What is somewhat surprising, however, is that when structural data are available, they are not used to their full potential. Recent work has shown that data on block size have potential applications in different areas of rock engineering:• Blasting — Hudson (1993) has described the excavation process as the change of a preexisting natural block size distribution to the debris fragment size distribution (Fig. 1). Lizotte and Scoble (1994) have reviewed previous efforts on integrating site specific geological conditions into blast design. Grenon et al. (1997) provide a case study where in-situ block size distributions are compared to photogrammetric studies of blasted rock.• Rock mass classifications — Block size is used in the majority of rock mass classification systems either explicitly, as in the RMi classification system Palmstrøm (1995), or implicitly, such as in the NGI system, Barton et al. (1974)."

Jan 1, 1998

By Carlos Antônio de Morais, Renata Dias Abreu

The present work describes a study of the separation of terbium and dysprosium from heavy RE concentrate through a solvent extraction circuit in a counter-current system. As the efficiency of the REE extraction by acid extractants rises with the increase of the atomic number of the element, the aim of this work is to extract the elements with higher atomic number maintaining Tb and Dy in the aqueous phase. Thus, terbium was separated first with subsequent separation of dysprosium. The experiments were carried out by using IONQUEST®801 as the extractant and a REE-hydrochloric liquor as feed solution. The optimum operational circuit in terbium separation was comprised of 37 stages: extraction, scrubbing, stripping, and solvent washing. For the dysprosium separation 39 stages were required. Terbium separation over 92% with over 95% purity and a Dy separation over 97% with over 95% purity were obtained.

Jan 1, 2014