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By Ernst Langer

INTRODUCTION Morro do Niquel is located near the small town of Pratdáolis in the southwest part of the State of Minas Gerais, Brazil, about 300 km in a straight line north of São Paulo and 300 krn west of Belo Horizonte. The deposit is known since 1935. Systematic exploration started, however, only in 1957 and production with one furnace in 1962. Since 1969, after the installation of a second furnace, the mine produces about 2 500 tons of nickel, contained in ferronickel, per year. This production is now consumed totally by the Brazilian steel industry. The "Morro do Niquel" is a serpentinite stock of 900 by 400 m which rises 200 m high above the surrounding metamorphic rocks of Algokian age (see Figure 1). On top of the hill there is a leached barren zone of about 200 by 400 m, generally 20-30 m deep, which consists practically only of a boxwork of quartz colored brown by limonite. Surrounding this zone on the sides of the hill is weathered, decomposed serpentinite which contains about 213 of the economic nickel mineralization. Roughly 113 of the ore reserves lie below the leached overburden representing ore of a different type. The geological map and cross-section, Figure 2, give a clear picture of the occurrence.

Jan 1, 1979

By Kadri Dagdelen, Thys B. Johnson, Salih Ramazan

Long-term production scheduling design is a very important part of mining because it determines the economic outcome of a project There have been many attempts to solve the optimum pit scheduling problem, but there has been no success in developing a scheduling method to give optimum results in maximizing net present value of a mining project. Open pit production scheduling problem can be formulated as a mathematical programming problem and solved using Mixed Integer Programming technique. However, it is not possible to solve the formulation within a reasonable time since the number of integer variables required for the mathematical model is too great to do that by today's available computer technology. There- fore, a methodology is required to combine, or aggregate, the mining blocks and to decrease the number of integer variables in scheduling without losing the optimality. Therefore, the fundamental tree concept was developed in this paper to combine the blocks. A fundamental tree is defined as any combination of blocks such that: 1. the blocks can be profitably mined, 2. the blocks obey the slope constraints and, 3. there is no subset of the chosen blocks that meets 1 and 2. A Linear Programming (LP) formulation is developed as a mathematical model to find a set of fundamental trees that exist for a deposit. Since the blocks are combined to form the fundamental trees, the number of variables required for the scheduling model is decreased significantly. This decrease in the number of variables makes it possible to mathematically formulate the multi-time period scheduling problem as a Mixed Integer Programming (MIP) model. A case study is performed on a multi-mineral copper deposit in Peru, South America. NPVs of annual after-tax cash flows generated based on the schedule provided by the "Fundamental Tree Algorithm" is compared with NPVs resulted from the schedules coming from three of the computer packages presently available to the mining industry. These are Mintec's M821V, Earth- work's NPV Scheduler, and Whittle's Milava open pit mine schedulers.

Jan 1, 2002

By Roger S. Dewey

1.1. INTRODUCTION Despite indications of a general economic recovery in the U.S. during the mid-19801s, mine operators have not generally shared in the benefits of these reported better times. Budgets have not rebounded, borrowing is tougher, parent companies' pockets are not as deep as in previous years, and margins are not any better -- if there is any left over at all. Managing capital equipment budgets is always a challenge, and the last five years of stretched equipment lives make these decisions more tenuous. Delays and avoidance of replacements due to tough times inevitably makes those decisions increasingly difficult and usually more expensive The purposes of this paper are to present. a brief refresher outline of the fundamentals of equipment replacement analysis, to suggest a number of papers where analysis methods are explained in greater detail. and to recommend the use of a widespread microcomputer software capability (1-2-3) as the easiest path to a much-needed solution for a very difficult, and usually under-supported management decision problem 2. REPLACEMENT DECISION POLICY Investments in equipment replacements must compete for capital with all other investment alternatives. Capital for replacements of ten represents a greater commitment than do the new projects which a company might handle in a given year. But. sadly, formal policies for standardized analysis of replacements rarely exist, even in major companies. Yet this policy can be very significant in determining the competitiveness of a firm. Whereas many replacement decisions are based on cost minimization, economists and financial analysts agree that wealth maximization or return on investment is the superior criterion. Though the difference may seem slight, agreement on a firm's financial objective is vital. Replacement policy should be straight- forward. have a logical basis, and a proper level of sophistication. There are several reasons to develop a policy for replacement decision-making: [I] 1 - equipment's optimal economic life is nearly always shorter than its physical life; 2 - mine life often exceeds equipment life, so management must face these decisions routinly 3 - replacement capital costs, on an undiscounted basis, can run 25 to 75% of original capital 4 - technological changes may result in a newer machine or system which can operate more efficiently, more safely. or less expensively 5 - estimates should be made consistently in the fundamental areas of life expectancy, availability, utilization. price escalation, taxes 6 - long-term and short-term budgeting without decent data and analytical capability is nearly impossible, or at least ineffective Policy development assumptions which must be considered include: the planning horizon, cost patterns, interest rates, availability of capital, replacement vs. expansion, technology advances.

Jan 1, 1987

By Song Jiang, Xianzhi Tan, Minjie Lian

"The ground water heat pump system lades underground hot water which can be heated or cooled by heat exchanger in water source heat pump air conditioner. This system replaces the model of heating of air-conditioning by refrigerator and boiler. In this paper, the formation conditions of hot water energy in Shan Dong are analyzed in order to achieve the purpose of energy conservation and emissions reduction by taking full advantage of water resources such as water pouring and return water of beatification during the productive process of underground metal mine. In order to analyze the issue better, the paper points out some ways and methods for geothermal water often used in underground metal mine. This paper also presents the advantages of the technology of water source heat pump that is applied into underground metal mine. Here is a case study of comprehensive utilization of water source in a certain underground metal mine in Ji Ning. This mine, according to its own actual situation, designs heat pump heat exchange system which is used for indoor heating of buildings and bath for staff. It turns out that the system can save 23% water per year, cut down 3.303 million KW electric energy, and reduce 4160t emission of carbon dioxide. It is concluded that the technology of water source heat pump has broad application prospects in underground metal mine. Therefore, the results show that it is an ideal way to change the present structure of cooling and heating source in metal mine.Introduction In recent years, overuse of fossil fuels has posed a grave threat onto the environment, which makes renewable energy a more important status in energy structure. Development and utilization of renewable energy has become an important direction. Water source heat pump technology is to use solar energy stored in water as cold/heat source to convert energy. Currently, this technology has been widely used in some advanced countries. However, due to facers of implementation technology and component costs, there is still a gap in water source heat pump technology between China and these advanced countries. According to (Blum et al 2011) that after in-depth study, water source heat pump technology has developed rapidly in China recently, and the gap is gradually reduced. Groundwater source heat pump system as a kind of high efficiency, energy-saving and environmentally friendly technology in recent years, more and more get the people's attention. At the same time, its practical application has also been rapid development. Based on (Ni et al 2015) that According to the relevant departments of the prediction, the technology will become the 21st century the most efficient heating and cooling technology."

Jan 1, 2017

By H. L. Ehrlich

Marine manganese nodules harbor a mixed population of manganese-oxidizing and -reducing bacteria, as well as bacteria that do not act on manganese. They also host phagotrophic protozoa. Out of several laboratory studies, one line of investigation indicates that some kinds of bacteria found on nodules can catalyze the oxidation of Mn2+ bound to Mn(IV) oxide at the surface of nodules at in situ temperature and pressure. In the absence of appropriate bacteria, the rate of oxidation of the surface-bound Mn2+ is significantly slower. How Fe(III) is incorporated is still unclear. Base metals such as Cu, Ni and Co, which are usually found in marine nodules in various quantities, may be incorporated through scavenging by Mn(IV) oxide. Laboratory evidence shows that some other bacteria on nodules can reduce the Mn(IV) oxide to Mn2+ in the presence of an appropriate source of reducing power in the form of organic carbon. The reduction of Mn(IV) oxide mobilizes manganese and trace metals such as Cu, Ni, and Co in the nodules. These bacteria reduce Mn(IV) whether oxygen is present or not. They could be harnessed in the bioleaching of nodules. The manganese(IV)-reducing bacteria and the bacteria that neither oxidize nor reduce manganese are thought to keep the organic matter in the nodule environment sufficiently low to favor bacterial manganese-oxidation, which in laboratory tests is inhibited by excess organic carbon. The preying by the protozoa on the different kinds of bacteria is thought to control the bacterial population on nodules and ensure continued growth of the manganese-oxidizing bacteria and the nodules. To eliminate interference from seawater salts in the bioleaching of Mn, Cu, Ni and Co, it may be more advantageous to use terrestrial Mn(IV)-reducing bacteria than the Mn(IV)-reducing bacteria resident on nodules. The terrestrial bacteria would allow bioleaching in fresh water. Unlike the marine bacteria, most terrestrial bacteria studied to date reduce Mn(IV) oxide only anaerobically. A general outline for an anaerobic bioleach process of marine nodules with freshwater bacteria is discussed.

Jan 1, 2000

By J. C. Hower

The Hardgrove grindability index (HGI) is a widely used coal-quality parameter with applications in coal mining, beneficiation, and utilization. An understanding of the petrology of the coal is fundamental to understanding the validity of the HGI in the given application. The HGI varies with coal rank, increasing (greater ease of grinding) with increasing rank through the high-volatile bituminous rank range; and the HGI varies with changes in the maceral and microlithotype composition, decreasing with an increase in liptinite and liptinite-rich microlithotypes. In this review, the .fundamental relationship between HGI and coal petrology, and consequently its relationship to coal utilization, is examined.

Jan 1, 1999

By Nai-piu Tong, Huaren Dou, Sui-shun Poon, Leslie H. Swann

This paper mainly presents geotechnical aspects of a vehicular underpass that was built across under one of the busiest highway in Hong Kong. The underpass, in a section comprising an upper arch and invert slab, is approximately 6.2 m high at crown and 15 m wide at the base level with 40 m in length. The construction inevitably requires the underpass to be built using tunneling techniques to keep the overheadroad traffic uninterrupted. The paper will describe the design of temporary support for the tunnel excavation that was provided by an arch formed with horizontal pipes, which were installed using the pipe ramming method. The pipes arch was then supported by steel ribs founded on rock or mass concrete. Permanent lining design consideration was also discussed. Results of numerical modeling of the soil-structure interaction using the 2-D computer code FLAC will be presented. The predictions have been compared to the monitored results during construction, which indicates the prediction is in reasonable agreement with the measurement in the light of ground movement. The construction challenges will also be discussed in the paper.

Jan 1, 2003

By A. M. Marabini, G. Belardi, V. Alesse, M. Acosta

Sotiel mine is situated in the Iberian Pyrite Belt in southern Spain, some 40 km north of the port of Huelva. Although mining operations at the site date back to Roman times, the present mine came into production in 1983 and 5.6 million tonnes of ore had been extracted by 1993. The orebody is volcano-sedimentary and consists of fine grained copper, lead and zinc minerals in massive pyrite surrounded by slates and volcanics. Prior laboratory research had resulted in the synthesis of a new collector, belonging to the MercaptoBenzoOxazole (MBO) class that acts selectively towards Cu and Zn minerals after activation with CuS04. The MethylMercaptoBenzoOxazole (MMBO) version of this collector had been used for the laboratory flotation of Cu minerals and sphalerite activated by CuS04. This resulted in identification of the optimal physicochemical conditions for laboratory-cell flotation of the two minerals from samples of complex sulphide ores, and subsequently the reagent has been tested in the Sotiel plant (Spain). The plant has three flotation sections. With conventional re-agents, the first section yields a Cu concentrate grading 21% with a total recovery of 29%, and the second one yields a 40% Pb concentrate with total recovery of 34% and a 47% Zn concentrate with total recovery of 78%. Application of the new synthetic reagent in the copper and zinc circuits produces a more selective process with a decrease in re- agent concentration grade and recovery are increased by 2 and 9 points respectively in the case of Cu and by 1 and 3 points where Zn is concerned. Moreover, the penalty elements in the Cu concentrate are halved.

Jan 1, 1995

By Lawrence A. Taylor

The rocks and minerals of the moon will be included among the raw materials used to construct a lunar base. The lunar regolith, the fragmental material present on the surface of the Moon, is composed mostly of disaggregated rocks and minerals, but also includes glassy fragments fused together by meteorite impacts. The finer fraction (i.e., < lcm) of the regolith, the soil, is probably the most important portion of the regolith for use at a lunar base. For example, soil can be used in bulk as insulation against cosmic rays, for lunar ceramic and abodes, or for growing plants. However, beneficiation of the soil can provide other feedstocks. For example, the soil contains abundant solar-wind implanted elements, as we1 1 as various minerals, particularly oxide phases, which are of potential economic importance. These components of the soil are sources of oxygen and hydrogen for water and rocket fuel, helium for nuclear energy, and metals such as Fe, Ni, Al, Si, and Ti. The uses of the lunar materials only await a fertile imagination.

Jan 1, 1990

By C. P. Shen, H. C. Tsai, Bennie Chu, Y. S. Hsieh

The Pinglin tunnels are situated within the fold-and-thrust belt structural region in Taiwan, due to continent-arc collision and plate tectonic setting. The pilot tunnel TBM (§=4.8m) became stuck ten times with the standstills to date. The westbound main tunnel TBM (§=11.74m) was buried in a collapsing calamity. The main tunnel TBM shall identify and overcome the adverse geology with high volume of ground water ingress itself. This paper presents our experience and methodology through the adverse geology with Pinglin large TBM.

Jan 1, 1999

By M. Kung, D. Schwegler-Berry, V. Castranova, D. Lewis, H. Abrons

Pulmonary responses to coal mine dust exposure were investigated by analysis of bronchoalveolar lavage specimens from non-smoking coal miners (n-12, mean age-43 ± 2 years, mean underground exposure-17 ± 2 years) and from non-smoking normal volunteers (n-18, mean age-43 ± 2 years). Spirometric and diffusion capacity indices were monitored as part of a physical exam. Lavage was performed in a subsegment of the right middle lobe by instillation of 200 ml of warmed saline solution in 50 ml aliquots and recovery by gentle suction. Specimens were centrifuged at 500g for 5 minutes at 2°C. Total and differential cell counts were recorded. Secretion of oxidants measured by chemiluminescence, surface morphology (spreading and ruffling), and lymphocyte parameters were determined. Lavage fluid was analyzed for the presence and quantity of acute phase reactants and immunoglobulins. Pulmonary function measurements as well as recovered lavage volume, total lavagable cells, and differential cell counts were similar in both miners and controls. Both resting and phorbol myristate acetate-stimulated chemiluminescence were also similar in miners and controls. In contrast, particle-stimulated chemiluminescence was significantly decreased in the alveolar macrophages from the miners (48% of control values). Morphometric analysis of scanning electron micrographs indicate that phagocyte surface spreading was similar in miners and controls. However, surface ruffling was 127% greater in the miners compared to controls. Lymphocyte subpopulations were similar in miners and controls. Protein analysis of the lavage fluid revealed lower total protein content in the lavage fluid of miners. However, the concentration of albumin, IgG, and IgA were similar in miners and controls. We conclude that most indices were normal in underground miners working under the current dust standard of 2 mg/m3. The decrease in particlestimulated chemiluminescence and the increase in surface ruffling in miners may suggest the beginnings of particle overload and activation of the macrophages. In addition, a decrease in total protein was noted in lavage fluid from miners.

Jan 1, 1991

By Henry N. McCarl

In the period 1982-1992, world trade has increased in real terms about 65% (Anon., 1992b). The nominal value of this trade in the early 1990s is approximately $5 trillion. In 1970, mineral commodities constituted approximately 20% of the value of world trade. By 1980, despite rising petroleum prices, mineral commodities made up about 18% of the total value of world trade, with crude oil amounting to 16% and other minerals the remaining 2%. By 1987, the major worldwide economic slowdown and falling oil prices meant that minerals constituted only about 10% of the total value of world trade, or about $500 billion in 1987 (Kimbell and Zajac, 1988). The importance of minerals in world trade since 1987 has remained at about these levels. Approximately 40% of world mineral commodity production is traded internationally. Some economists predict that minerals and other commodities are likely to continue to decline in relative importance in terms of the value of world economic output, as well as world trade, into the foreseeable future (Thurow, 1992). This projected decline in commodity demand may also be related to much slower global economic growth over the next decade (Alperovitz, 1992). Industrial minerals and rocks constituted roughly 2.5% of total mineral commodity exports in the late 1980s, but their relative importance as a portion of mineral commodity exports nearly doubled in the decade 1977-1987 (Kimbell and Zajac, 1988). Industrial minerals constitute the most rapidly growing share of total mineral commodity exports. In addition, price declines among industrial minerals were uncommon in the decade 1977-1987 (Kimbell and Zajac, 1988). While prices of sulfur and most of the fertilizer minerals have seen some erosion and slow growth in markets in the period 1987-1992, other industrial minerals have increased in both value and share of the export market (USBM, 1992). The place of industrial minerals in world trade becomes even more significant when one looks at shipments of chemical fertilizers and basic chemicals that are counted as manufactured products rather than industrial mineral commodities. The United States is the major world producer of industrial mineral commodities and products made from these nonmetallic minerals and rocks. The former Soviet Union, now The Commonwealth of Independent States (CIS), and China have very significant deposits of industrial minerals. Japan exports significant quantities of cement. The US, CIS, and Morocco export large amounts of phosphate rock. Canada and Germany export substantial amounts of potash. Sulfur from Poland, industrial diamonds from South Africa, Zaire, and Brazil, and fluorspar from Mexico are all important exports.

Jan 1, 1994

By R. B. Krog

Airflow patterns in longwall bleeder systems are affected by gob permeability and porosity and the condition of the gateroad entries after mining. As longwall panels are mined, areas of the caved zone and portions of the remaining gateroad entries become inaccessible, making direct ventilation measurement impossible. Mine operators are left to estimate direction and amount of airflow in the gob and the surrounding gateroads. The most readily available locations are where air enters the worked-out area, approved measurement point locations (MPLs) and/or evaluation points such as bleeder evaluation points, intake evaluation points, and the outer bleeder entry. Ventilation models (network or Computational Fluid Dynamics, CFD) can model the gob and the surrounding bleeder system but calibrating these models is difficult without field data. NIOSH installed a tube sampling system ahead of a longwall face and, as the face retreated, released a slug of tracer gas (SF6) to determine transportation times and flow rates in the inaccessible gateroads. The data was used to calibrate both network and CFD ventilation models for a longwall panel. Both model types were used to predict the airflow patterns in the gob and to determine the airflow rate from the longwall tailgate corner back to the bleeders.

Jan 1, 2011

By Cheryl L. Mardock, Michael D. Strickler

The Bureau of Mines is examining mineral deposits bearing strategic elements such as cobalt, for which the United States heavily relies on imports. The Turner-Albright volcanogenic sulfide deposit in southwestern Oregon is marginally economic based on its gold content and associated silver, copper, zinc, and cobalt values. Bureau research on the Turner-Albright deposit was performed (1) to evaluate domestic cobalt recovery as a byproduct of gold production from massive sulfide ores; (2) to develop an analogue of modern sea-floor polymetallic deposits to determine the economic potential of the deep-sea resources; and (3) to compile information on the geochemistry and genesis of the deposit that can aid in future onshore exploration. Cold was introduced as near micrometer-sized disseminations by exhalative hydrothermal fluids near sea-floor vent sites and by late influxes of mineralizing fluids into lower zones of brecciated sulfides and basaltic fragments. Cobalt is a substitutional element in pyrite that occurs in outlying halos around original vent sites. Mineralogic studies conducted with a scanning-electron microscope and an electron microprobe determined that none of the ore minerals are amenable to traditional beneficiation methods such as gravity and flotation. An experimental oxygen pressure-leaching procedure developed by the Bureau has proven successful in treating such complex ores.

Jan 1, 1990

By J. W. Jang, I. Iwasaki

Introduction Grinding ball wear in wet grinding is due to a complex combination of abrasion, corrosion, impact and their interactions. The ball charge is continually falling from a height greater than half of the ball mill&apos;s diameter, and contact is made with ore particles or other balls. Abrasive wear occurs through penetration and plowing of media materials from the ball surface by hard ore particles (Gangopadhyay and Moore, 1985). Electrochemical interactions between the abraded and unabraded areas of the ball surfaces, as well as between the grinding media and the minerals, occur in grinding mill pulps (Adam et al., 1986). The wear depends on the media composition, the hardness and the corrosive/abrasive characteristics of the slurry. The marked-ball-wear test method was used to evaluate the performance of grinding media under nitrogen and oxygen atmospheres. Also, the wear mode was studied by observing the grinding media surface under a scanning electron microscope. In general, grinding media of high hardness and high chromium contents were found to have better corrosive wear resistance than those of low hardness and low chromium contents (Jang, Iwasaki and Moore, 1988). The purpose of this investigation was to determine the size distribution and the shape of wear debris in a study of the wear rates and wear behaviors of grinding balls. Experimental Materials The grinding ball alloys used in this investigation were: •martensitic stainless steel (MSS; 0.96% C and 16.2% Cr), •high-carbon, low-alloy steel (HCLA; 0.89% C and 0.53% Cr), and •mild steel (MS; 0.22% C and 0.09% Cr). The mineral used in this study was synthetic corundum, because it was on hand and contained no magnetic impurities. Debris A 203- mm (8-in.) diam porcelain mill was used for grinding the corundum. The mill charge consisted of: •1200 g of 12-grit synthetic corundum, •770 mL of 0.05 mole/L Na2SO4 (61% solids), and •125 steel balls of nominally 25-mm (1-in.) diam. To minimize the debris corrosion, nitrogen was introduced into the mill. Grinding with MSS, HCLA-steel or MS balls was conducted for 2 hr at 51 rpm. The grinding time using the MS ball was varied from 0.5 hr to 2 hr in an attempt to study the debris amount and shape as a function of time. The debris was collected with a hand magnet from the ground slurry and separated from the corundum particles using a Davis magnetic tube. After the separation, the debris particles were immediately washed with acetone and then filtered and dried. Debris size analysis Buckbee-Mears 3-in.-diam, micro-mesh sieves and an electromagnetic shaker were used for determining the debris size distribution. In sieving, isopropyl alcohol was used. The debris fraction collected from each sieve was washed with acetone, dried and then weighed on an analytical balance. [ ]

Jan 1, 1993

By R. C. Fox

The geophysical aspect of reconnaissance marks the beginning of extensive computer applications supporting development of a mine. Although there are some storage and retrieval applications in geology, and some statistical analysis in geochemistry, large-scale compilation, reduction, and interpretation of mineral resource data are initiated in reconnaissance geophysics. The reasons for this fact are quite simple. Geophysics is oriented toward quantitative evaluation of areas of interest, and methods of data collection are automated to the extent that large amounts of analog and digital information are recorded. The large volume of data must be interpreted in a reasonable time. Furthermore, some modeling problems involving complex numerical solutions could not be attempted without the computer. Therefore, the computer is essential to the success of an exploration project using geophysics. For example, aeromagnetics is a common technique for reconnaissance examination of areas associated with sulfide systems and porphyry deposits. An area covering 161 X 161 km (100 X 100 miles) may be flown with a 1.6-km (1-mile) line spacing yielding 10,000 line miles (16,093 km) of data. If only 10 measurements are recorded per mile, 100,000 data points, including location and magnetic field intensity, must be reduced and stored for quantitative interpretation. Computer applications often represent a significant investment in manpower and hardware. It is desirable, therefore, to initiate an engineering approach to the application of computers to geophysics. By this it is meant that computer programs and systems should be formulated, developed, and implemented in a disciplined manner such that their usage is dependent only on the application and not on the individual doing the programming. In other words, computer application, development, and usage should evolve beyond the personal gadget phase to an important applied technology. Geophysics has evolved over the past two decades in a course parallel to computer hardware development. During the sixties, the computer became large enough and fast enough that complex models required by geophysics could be solved. Automation also relieved the geophysicist from routine manual calculations. During the seventies, computing power in¬creased and applications expanded from two-dimensional problems to three-dimensional modeling. Moving into the eighties, as computer hardware costs will significantly decrease, the major expense of computing will be the manpower required to develop, implement, and use an application; therefore, improved programming techniques and applications software engineering methods will be used to optimize and preserve this investment. This chapter presents a general overview of computer methods in geophysical reconnaissance; it is divided into two parts: geophysical methodology and software engineering.

Jan 1, 1979

By Eduardo Poltronieri Trés, Anderson Denadai Thomazini, Rodrigo Boyer Fernandes, Francisco de Assis Dutra Macedo, Gilvandro Bueno, Maycon Athayde, Rossano Augusto Pilon Nunes

The earliest industrial application of high pressure grinding rolls (HPGR) at comminution was in 1984 in the cement industry. Since then, the equipment has been widely applied in mining activities. Despite the rapid spread across the industry, several challenges are still present in the equipment’s application, especially considering the complex ore breakage behaviour reported for this process. The pellet feed’s HPGR comminution was recognized as fundamental to efficiently increase the particle surface area (e.g., blaine specific area, BSA) at a lower energy and water consumption level (Chapman et al. in J Southern Afr Instit Mining Metall 113:407–413, 2013). The present study considers a novel milling process applying only HPGR as a re-regrind stage after concentration. The amount of successive ground product recirculation into the machine to achieve the required particle size for the pelletizing process was investigated. The study compared the ball wet milling process with the innovative processing technology for hematite–goethite ores. Green pellet balling and induration processes were simulated in bench and pilot scale. The milling results showed a considerably steep increase in BSA after each recirculation step into the HPGR, although compared with the ball-milled product the size fraction <45 μm% increased a modest five percentage points after three recirculation cycles, remaining steady until the last recirculation step. As a result, the green pellet generated presented higher concentration of pellets between 10 and 16 mm (%10-16 mm), with a higher drop number than typically observed when produced with ball-milled feedstock. Consequently, on the induration process, a higher pellet deformation was observed during the pot grate loading. Despite that, the fired pellets still presented an outstanding performance in cold crush strength (CSS) considered suitable to an industrial application.

By K. Saberyan

A technique is described for the solvent extraction of zirconium. In this method, zirconium has been extracted quantitatively from 0.005 M sodium salicylate solution at pH 2.5 - 3 using 0.01 M triphenylphosphine oxide dissolved in toluene as an extractant. Zirconium has also been recovered quantitatively from 0.2 M potassium thiocyanate solution, but extractions in nitric and hydrochloric acids (as media) were negligible. The resulting extracted metal ion has been stripped with sulfuric acid (0.5 M) and determined with inductively coupled plasma atomic emission spectrometry. This method has been applied successfully to achieve 95% recovery of zirconium from zircon concentrate.

Jan 1, 2010

By Judson H. Whitman

To evaluate intelligently and to market a source of rare earth raw material, it is necessary that the producer understand the requirements of the processor and the manner in which these requirements effect the value and salability of his product. This paper will be an attempt to aid in such an understanding. The majority of rare earth processors are primarily chemical companies, not mining or metallurgical companies, as the complexities of the processing procedures are&apos; much more chemical in nature than metallurgical. The rare earths and the rare earth industry are normally divided into two groups - the ?light? or cerium group and the ?heavy? or yttrium group. They are so named because cerium and yttrium are the most common elements in &apos;heir respective groups and are so divided on the basis of mineralogical and chemical characteristics. The dividing line of the two groups is not rigidly fixed but usually is considered as being between samarium (atomic number 62) and europium (atomic number 63). Although the two groups are quite similar, processing procedures differ significantly, hence most processors tend to specialize in one group or the other. There is, however, a growing tendency toward participation in both groups.

Jan 1, 1960

Power plants that utilize conventional wet flue-gas desulfurization methods produce enormous amounts of flue-gas scrubber sludge. A typical 400 MW power station that burns a high sulfur coal produces 170,000 tons of wet flue-gas scrubber sludge per year. This scrubber sludge is currently landfilled at an enormous cost to utility companies. This material could be used as a raw material for industries that use gypsum, such as the wallboard and plaster industries. However, before it can be used as feedstock for these industries, some of the impurities such as unreacted limestone and silicates must be removed from the scrubber sludge. Froth flotation has tremendous potential for separating these impurities from scrubber sludge. In order to select an optimum flotation process, it is necessary to characterize the surface properties of the major components in the scrubber sludge, which consist of calcium sulfite, calcium sulfate, calcium carbonate (limestone), and silica. In this study zeta potential measurements were used to determine the surface charge of the components in scrubber sludge, with the goal of optimizing a froth flotation process to produce a marketable gypsum product for the wallboard and plaster industries.

Jan 1, 1996