Search Documents

By Rodolfo V. de la Cruz

This paper describes the development of a modified Goodman Jack method for determining the mechanical properties of rock masses in situ. The modified method consists of the basic borehole loading device and a friction-strain-gauge measuring module. The friction gauges, located in the central portion of the jack, are impressed on opposite quadrants of the borehole walls and the remaining quadrants are loaded by the borehole jack with a uniaxial self-equilibrating pair of forces. The tangential strains generated at the borehole walls are thus measured concurrently with the loading. For ideal elastic materials, the tangential stresses at any point on the borehole walls due to jack loading can be obtained from closed-form analytical solutions utilizing the complex variable method. Complete stress-strain curves for the rock material can then be directly obtained from the tangential strain measurements and the calculated tangential stresses at those points. The continuous data are considerably more significant and reliable than averaged or point data obtainable by other current in situ measuring techniques. Moreover, the advantages inherent to the original Goodman Jack method are also obtainable in the modified method. The suitability of the new method was demonstrated by carrying out a number of laboratory measurements in large specimens of reinforced concrete, aluminum and granite blocks. The results of actual field measurements carried out in sandstone and granite quarries were found comparable with those obtained in the laboratory.

Jan 1, 1976

By William R. Henkle

High-calcium limestone has been intermittently produced from the Monarch quarry since the late 1800s. Initial production was used in sugar processing and for a smelter located near Salida, Colorado. During the 1920s, Colorado Fuel and Iron Company (CF&I) began to exploit the deposit as a source of flux stone for its blast furnace steel operations at Pueblo. The deposit was operated for many years as a captive quarry by CF&I. In 1984, CF&I closed the quarrying operations at Monarch; flux stone was no longer required since the blast furnaces were taken off line in 198 1. In 1994, Colorado Lime Company, a subsidiary of United States Lime and Minerals, Inc. acquired the property. Limestone was mined from the Castle Butte Member of the Leadville Limestone (Lower Missippian). Some high- magnesium dolomite was also mined during WWII from the Redcliff Dolomite Member which directly underlies the Castle Butte. Past production was from both an upper and lower quarry at elevations ranging from 10,000 to 11,000 feet (3,048 m-3,353 m) mean sea level (m.s.1.). The reserves at Monarch quarry are in a dip slope deposit, occupying the northwest slope of Monarch Hill. The structural geology of the deposit is complex on both a region- al and mine scale. The reserves are located on the eastern limb of the Syncline Hill syncline. The beds on this limb of the structure strike to the northeast and dip to the northwest from 30 to 45 degrees. A major reverse fault separates the reserves into an upper and lower deposit. Numerous smaller normal and reverse faults cut the deposit, requiring a flexible mine plan. At the Monarch quarry, the Castle Butte Member con- sists of two stratigraphic units. The Upper unit (Mlu) is a thick-bedded, fine-grained crystalline dolomitic limestone from 0 to 300 feet (0-90 m) thick. The unit generally has an Si02 content of less than 4 percent. A bedded chert horizon and a karst horizon at the base of the unit locally raise the Si02 content as high as 20 percent. The underlying Quarry Stone unit (Mlq) is a light-gray, massive, bedded, calcilutite/micrite limestone from 90 to 130 feet (27-40 m) thick. The Quarry Stone unit is remarkably uniform chemically throughout it's entire thickness. Average analysis is CaC03 - 95 percent, MgC03 - 3.5 percent, and Si02 - 0.5 percent. The Footwall dolomite unit (Mld) of the Redcliff Member of the Leadville Limestone is a dark gray to black, blocky, medium-to-thick-bedded, calcilutite/micrite dolomite from 150 to 180 feet thick (46-55 m). The upper 100 feet (30 m) of the unit is a low-silica facies with an average Si02 content of less than 0.5 percent. MgC03 content is con- sistent at 39.8 percent throughout the upper 50 feet (15 m) of the unit but varies from 15 percent to 39.8 percent in the lower portion (50 to 100 feet [15-30 m]) of the low-silica facies. The lowest portion of the unit, 100 feet (30 m) to base of unit is high in silica and is not considered chemical grade. Current in-place, surface-minable reserves at the quarry are estimated to be 14 million short tons (st) (13 million metric tons [mt]) of limestone and 50 million st (45 million mt) of dolomite. A 1.4 million st (1.3 million mt) stockpile of finely crushed limestone is also present on the property. Colorado Lime is presently processing approximately 2,000 st (1,800 mt) per month from the crushed limestone stockpile. This material is pulverized and sold to underground coal mines for use as rock dust, some of this product is also used for environmental purposes. Limestone mining is scheduled to resume in spring of 2000.

Jan 1, 2001

By Donald M. Hausen

Microscopic evaluation of trace quantities of metalliferous phases in flotation products requires counting large numbers of particles. Particle counts of many thousands may be required for precision, but not obtained practically by conventional microscopic techniques. A less tedious microscopic method for evaluating trace sulfides in mill tailings was developed for the O'okiep Mining Company in South Africa. Hundreds of thousands of particles were evaluated by this method called "gross-counting." Gross-counting consists of counting microscopic fields rather than point-counting individual particles. Total counts are calculated by multiplying the average number of particles per field by the total number of fields examined over the entire mount. Total gross-counts range from about 20,000 particles for +200 to 100,000 or more for -400 mesh size material in lucite mounts. Sulfides and metallic particles in each field are identified and tallied along with field counts. Totals for each type of metallic particle are divided by the total gross-count to give volume percent which is corrected to weight percent by specific gravity factors.

Jan 1, 1969

By J. R. Kadambi, C. Shingote, J. Furlan, R. Ke

"Hydrocyclone separators are widely used in various industrial applications in the oil and mining industries to sort, classify and separate solid particles or liquid droplets within liquid suspensions, which are considered to be multi-phase systems. Numerous valuable studies have been conducted in recent years to investigate the flow fields inside hydrocyclones. However, much of the information regarding the performance of cyclones in the literature has limitations, based in some part on the respective current-available theoretical models, and much of it cannot be considered as completely applicable to most real-world applications; many of the studies investigated the flow fields within extremely simplified hydraulic designs that are not representative of the complex geometries or large sizes which are typical in industry. Therefore, in this study, the two phase flow system inside the actual hydraulic geometry of a milling circuit hydrocyclone was explored with the aid of both computational and experimental techniques (Particle Image Velocimetry). In this study, the flow field with an air core has been investigated; in essence, the research was a two-phase problem, which caused some challenges on both the computational and experimental sides. Two turbulence models were used in the numerical calculations: the Reynolds Stress Model and Large Eddy Simulation. The computational studies are mainly focused on the prediction of the dimensions and shape of the air core. Different section planes of the hydrocyclone were selected as planes of interest and then were divided into several fields of view (FOV) for PIV measurements. Two dimensional experimental velocity vector maps were obtained in each of the fields of view. The computational results were validated globally using pressure and flow rate readings at the boundaries and locally by comparison to the PIV velocity vector maps and profiles. Keywords: Computational fluid dynamics (CFD); Hydrocyclone; Particle image velocimetry (PIV); Reynolds Stress Model (RSM); Large Eddy Simulation (LES). INTRODUCTION A hydrocyclone is a device used to separate a solid-liquid, liquid-liquid, solid-gas, or liquid-gas suspensions into at least two separate density or particle size components. Hence, the flow field of the hydrocyclone is generally considered a multi-phases flow system. Application of hydrocyclones have been used in numerous industries including oil, drilling, metal working, and mineral processing since 1891, when E. Bretney obtained the first patent for the predecessor design of all contemporary hydrocyclones. A modern hydrocyclone typically consists a cylindrical section at the top where the liquid is being fed tangentially, and a conical chamber attached to the bottom of the cylindrical section, as shown in Figure 1. The characteristics of the feed stream that is injected into the cylindrical chamber play a significant role in hydrocyclone operation. The inlet is tangential relative to the cylindrical chamber and hence causes a centripetal force in the flow field which is considered as the primary separation mechanism."

Jan 1, 2017

By Thomas V. Falkie

The title of this talk has brought some interesting responses - even before it was written - from different parts of the country. A geologist from the Western U. S, was deeply concerned with recent layoffs in his profession and the employment situation in general and wondered why "the AIME wasn't doing anything for the benefit of its members." A petroleum engineer in Texas said that a group in his field were studying "professionalism" and their professional status and wondered if there were any words of wisdom for him. A mining engineering professor from the East pointed out that the National Science Foundation did not include mining engineering as one of its recognized fields in one of its equipment funding programs. These are just a few examples of reactions received to date, but they serve to illustrate the broad image that the title has meant to various people. Actually the term profession is defined by Webster as "a calling requiring specialized knowledge and often long and intensive academic preparation." The word encroach means "to enter by gradual steps or by stealth into the possessions or rights of another", or "to advance beyond desirable or normal limits." The intention of this paper, as originally conceived and requested by the program chairman, was to combine those two words literally and talk about how the professional standing of mineral engineers is being eroded from people outside the profession. But the amazing preliminary response suggests that it may be timely to broaden the discussion by including some comments about professionalism in general. In the paper the terms "mineral engineer" or "mining engineering" are used frequently, but it should be clearly understood that much of what is said is valid and is intended for all fields covered by SME and perhaps for AIME in general.

Jan 1, 1972

By Cristian Saavedra, Patricio Zarate

Flotation collectors play a crucial role in mineral flotation by selectively adhering to mineral surfaces and aiding in their separation from gangue material. They are heteropolar molecules, as defined by Sutherland and Wark (1955), featuring non-polar hydrocarbon chains and polar groups interacting with mineral surfaces to induce hydrophobicity selectively. The importance of collectors in mineral processing, as underscored by Lotter and Bradshaw (2010), lies in their ability to enhance recovery rates and improve selectivity, thereby optimizing the extraction of valuable minerals from complex ores. Collectors are classified based on their mechanism of action, as proposed by Laskowski (2010). This classification categorizes collectors into three groups: water-soluble compounds, water-insoluble “oily” collectors, and water-insoluble amphipathic compounds forming molecular films at the water/gas interface. This complements the chemical structure-based classification by Sutherland and Wark (1955) and Suoninen and Laajalehto (1993), offering a comprehensive understanding of collector diversity in flotation systems. Collector selection is an iterative process crucial for optimizing mineral processing efficiency, as emphasized by Lotter and Bradshaw (2010). Understanding the significance of collector mixing or synergy outcomes is paramount for enhancing mineral flotation efficiency and sustainability. Taguta, O’Connor, and McFadzean (2018) demonstrate that mixed collector systems enhance interaction enthalpies and microflotation recoveries, indicating improved performance. McFadzean, Castelyn, and O’Connor (2012), along with Critchley and Riaz (1991), delve into investigating synergistic interactions between collectors, offering insights for strategic selection. Observations from the study of collector synergy, as noted by Wakamatsu et al. (1980), reveal nuanced relationships surpassing individual collector behaviors. The methodology outlined in this paper provides valuable guidance for classifying and selecting collectors based on specific application needs, while also suggesting the potential for synergistically improving recovery across fine, intermediate, and coarse particles.

Feb 1, 2025

By E Marambio, R Brändle, G Fischer, G von Rickenbach, M Fuentealba, L Burgos, R Luis Fonseca

In underground excavations, under high stress conditions, ground support systems must provide safe and effective response to dynamic events. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the back analysis through numerical methods (central difference and Newmark’s method) of a ground support system tested with a double dynamic impact in 2019 is presented.

Apr 26, 2022

By A. Martikainen, S. GYAMFI

Luossavaara-Kiirunavaara Aktiebolag’s (LKAB) Konsuln iron ore mine, located just south of the famous Kiruna iron ore mine in Malmfälten in northern Sweden inside the Arctic Circle, was developed as a test mine between 2018 and 2020 for the Sustainable Underground Mining (SUM) project [1]. Besides functioning as a test mine, Konsuln also contributes to ore production. The existing mine ventilation system was designed for the current production rate of 0.8 Mtpa using conventional diesel machines. The design was created by Kiruna mine ventilation team, Stina Klemo and Joakim Jonasson, in cooperation with a consultant, Tomas Bolsöy from EOL Vent Mining AB. There is a plan to increase this rate to between 1.8 and 3 Mtpa in the future, and this requires the primary fans to be upgraded. Therefore, a study was carried out to determine whether using ventilation on demand (VOD) could avoid this fan upgrade and reduce Konsuln’s ventilation and heating power costs in the future. The study also investigated whether using battery electric vehicles (BEVs) along with VOD or as a standalone strategy could further reduce these power costs. In addition, the study analyzed the suitability of heating power reduction strategies presently or previously used in Nordic countries and Canada to investigate potential additional strategies to reduce heating power cost, the largest portion of Konsuln’s ventilation and heating power costs.

By Arthur R. MacPherson

Primary autogenous grinding has been in general use for somewhat over 20 years. During this period there have been many highly successful plants built on this principle, while some others have had problems such as: 1. Not performing as predicted from test work. 2. Highly fluctuating tonnage rates. 3. Mechanical problems. 4. High liner wear. Many of the problems with commercial autogenous mills have resulted from improper sampling and testing of the ore during the development period. It is recognized that the fully autogenous mill is very sensitive to any changes in grindability which may occur in the feed to such a mill. The semi-autogenous mill is somewhat less sensitive, but large swings in grindability of the feed require adjustment of ball charge and this cannot be easily accomplished in a short period of time.

Jan 1, 1976

By James P. Connell

The Montana Operations of the Anaconda Company constitute an integrated, though geographically separated, non-ferrous metal production complex. The mines are located at Butte and consist of one large open-pit mine, two small underground mines, a precipitation plant for both underground and pit-dump leach water, and the Weed Copper Concentrator. The smelter, located at Anaconda, Montana 25 miles to the west, processes all Butte copper shipments as well as copper materials from both Anaconda and private mines. Copper and zinc are refined at Great Falls, Montana, 165 miles to the north. Other facilities developed over the years include the Anaconda Forest Products Division, the Butte, Anaconda, and Little. Chicago Water Companies, and the Montana Hardware Company. Data processing for these operations has been performed on an IBM 360 Series, Model 30 computer, utilizing a Disc Operating System. This was replaced in September 1970 with a 360 Series, Model 40 128K unit. In addition, some data processing is also done for Anaconda Company operations located at Britannia Beach, British Columbia; Columbia Falls, Montana; Yerington, Nevada; and Twin Buttes and Tuscon, Arizona. The material under discussion in this paper will be concerned primarily with the mining operations at Butte.

Jan 1, 1970

By S. V. Krishnan

Stability of fine quartz suspensions in process water is of concern in several mineral processing applications. In alkaline solutions, the presence of magnesium ions, arising from such sources as water hardness and magnesium-bearing minerals, leads to the precipitation of Mg(OH)2 which coats the surfaces of quartz. The conditions under which heterocoagulation or surface precipitation of Mg(OH)2 on quartz occur and the manner in which they influence the settling behavior of ground quartz was studied by means of settling tests, coating density determinations, zeta potential measurements and electron microscope observations. Coating density was greater when Mg(OH)2 nucleated on the surface of quartz than when the precipitates heterocoagulated on the quartz surface. The settling curves of quartz suspensions in the presence of different concentrations of MgCl2 exhibited a maximum of maxima which occurred at 10-3M MgC12 and pH 11. Interactions between quartz and Mg(OH)2, and flocculation-dispersion characteristics of quartz suspensions in this system are discussed.

Jan 1, 1983

By D. Belin

Treatment of dilute acid mine drainage and similarly polluted water is becoming increasingly complicated. The pressure of economics is now exacerbated by legislation which classifies as hazardous waste the precipitates from conventional lime treatment plants. Since acid mine drainage invariably contains sulfate ions, one solution is to use anaerobic Desulfovibrio type bacteria to reduce the sulfate into sulphide ions which could then be used to precipitate out the heavy metals. Results are presented for both batch flask cultures and continuous column tests. Compost was used as the bacterial substrate in the column test which simulated heaps. Conditions changed from aerobic to the required anaerobic deep in the columns. Polluted feeds (up to 700 mg/l zinc) gave effluent containing well below I mg/l zinc over extended periods. Direct transfer of sulphide ions through a stream from an isolated container of bacteria is a good alternative.

Jan 1, 1991

By Ian Mitchell, Peter Faganl, Paul Haddad, Rob Dunne

During the gold cyanidation process, cyanide can be lost from the leachate by various chemical routes. The products of these cyanide losses include base metal cyanide complexes, thio­cyanate and cyanate. These losses are particularly important when treating pyritic or cupriferous ores since the two most sig­nificant cyanic ides, in order of importance, are sulfides and cop­per bearing minerals (I). Cyanidation of pyritic minerals results in the formation of thiocyanate. The problems caused by cyanide soluble copper minerals are well known to the gold processing industry and have been reviewed by several authors (e.g. 2, 3). An important consider­ation, especially with a number of more recent leaching tech­nologies, is the effect of the CN :Cu mole ratio, R, on the gold leaching kinetics. In order to efficiently leach cupriferous ores, it is important that R is maintained at a level that allows suffi­ciently rapid leaching without excessive use of cyanide. The optimum value for R in a fixed leaching system would appear to lie between 3 and 4. This is based on the early observations that the leaching rate is very slow when R is below 3, with a rapid increase in the leaching rate above 3 (2, 3,4). The leaching rate increases gradually when R is greater than 4 (4). The major Cu(I)-cyanide complex in this range of R values is the [Cu(CN)J]2· species. It has been postulated that leaching occurs due to either uncomplexed cyanide or the fourth ligand in [Cu(CN)4]3·, since the stepwise formation constant for this complex is very small (2, 3). An additional consideration when leaching cupriferous ores is the oxidation of cyanide by Cu(II) minerals, resulting in the formation of cyanate. It has also been reported that both sulfide minerals (5) and activated carbon (6, 7) catalyse the oxidation of cyanide to cyanate. From the above discussion, it is important for the leaching con­ditions to be carefully controlled when treating pyritic and cuprifer­ous ores in order to achieve efficient and economically viable leach­ing. For example, large concentrations of thiocyanate in the leachate would reveal large cyanide losses and thus indicate the need for a pretreatment step to oxidize the sulfides. Alternatively, a low R value would indicate slow leaching kinetics and consequent low gold recoveries, indicating the need for increased cyanide dosage.

Jan 1, 1996

By J. Sohn

The most promising near-term alternative to fuel cell driven vehicles is probably Hybrid Electric Vehicle (HEV or EV) technology. HEV technology combines the best characteristics of fuel-driven engines, electric motor drives, and energy storage components. It is designed with a combustion engine that functions as the primary power source, and an electric power storage system that functions as the secondary power source. The presence of the secondary power source allows designers to size the combustion engine for cruising power requirements. A new energy source for HEV or EV market will become lithium ion batteries (LIBs) in the near future. LIBs for HEV or EV has large scale about more 10,000 times than small size one for IT devices in order to achieve high electric density/capacity and high efficiency, etc. In those reasons, physical treatment of the batteries is more difficult for stable dismantling in comparison with the smaller one. Hybrid vehicle sales will grow by nearly 400 percent during the next seven years, according to a new report from analyst firm ABI Research. By 2013 hybrids will make up 6 percent of annual U.S. auto sales. The traction battery pack will become air-cooled LIBs which consists of several modules of Li ion battery and connected in series/parallel configuration to provide about >450 VDC, >150 kW peak power, and >80 Ah capacity. As the use of these batteries tends to increase significantly for the next years, it is relevant issues that development of new recycling methods as well as optimization of existing processes to treat spent LIBs for HEV have being addressed in order to obtain sustainability. In this study, physical treatment containing stable electrical discharge of spent LIBs for HEV was carried out for recovery of valuable metals from the batteries. Also In order to increase the yield of valuable metals through physical treatments such as electric discharge of spent batteries, crushing, and classification, we also focused on the recovery of cobalt from +8 mesh fraction due to its large portion in crushed intermediates.

Jan 1, 2010

By Jim Gebhardt

Douglas W. Fuerstenau (DWF) grew up on a farm and in several small communities in rural South Dakota during the depression years, where he learned the value of hard work. Working hard can produce results but being clever and hardworking will give you a bright future. In his later school years, Fuerstenau’s family moved to Rapid City where his intellectual curiosity and capacity helped him graduate with a B.S. in Metallurgical Engineering from the South Dakota School of Mines and Technology in 1949. His technical interests led to graduate studies and completion of a master’s degree from the Montana School of Mines in 1950 and Sc.D. degree from the Massachusetts Institute of Technology (MIT) in 1953.

By Víctor Vázquez, Guillermo Tiburcio, Martin Encinas, Jesús L. Valenzuela, Erick Montaño, Alejandro Valenzuela, José Parga

Merrill-Crowe is the primary process used for the concentration and purification of silver in a cyanide solution. The Langmuir Adsorption model for silver recovery in a cyanide solution was used for the study. The maximum adsorption capacity was 6.19 mmol/g for silver. This model properly adjusts the experimental results of the adsorption equilibrium with high correlation coefficients, which also favors the formation of a single layer of molecules adsorbed for the silver in the electrocoagulation- generated species. The thermodynamic parameters ΔG, ΔH, and ΔS were estimated, and it was found that the adsorption process is exothermic and spontaneous. For the kinetic study, the Lagergren second-order equation was used to study the adsorption speed. To characterize the solids coming from the electrocoagulation, X-ray diffraction (XRD), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) were used; the results of this study suggest that silver is present in aluminite, hydroniumjarosite, and alunogen.

Oct 30, 2021

By Joseph M. Morrison

This paper offers a comprehensive solution to the problem of dust emissions at belt conveyor transfer points. It discusses details of enclosure design and presents a straightforward procedure for calculating required dust control exhaust volumes. Many design variables are taken into account which heretofore have been commonly ignored or inadequately considered. These include belt widths, belt speeds, enclosure openings, material flow rates, material bulk densities, material lump sizes, height of material fall, material temperature, and ambient air temperature. All of these quantities are handled by means of a "fill-in-the-blanks" type of calculation form which permits quick, reliable solutions by relative "non- experts".

Jan 1, 1970

By Ronald O. Harma

Iron ore pellets made from concentrates produced from low grade iron ores are the primary iron bearing feedstock for iron making in North American blast furnaces. Steelmakers are demanding increasingly higher quality to provide for improved blast furnace productivity, efficiency, product quality and environmental compliance. Unfortunately, this higher quality iron ore product must be produced from the vast deposits of low grade iron ores that are becoming increasingly poorer in quality with regard to mineral liberation and ease of concentration. Since some of these low grade iron ores require grinding to as fine as 90% -500 mesh (25 microns) for liberation and since more of the silicious gangue and other minor undesirable constituents must be removed to provide the higher quality, we have come to depend on flotation to do the added work. Flotation technology and other preflotation unit operations must improve to meet these increasing demands. In many cases, flotation equipment, reagents and circuit operating performance have improved little during the last two to three decades. Mechanical flotation cells have grown from 14 cubic meters (500 cubic feet) to over 84 cubic meters (3000 cubic feet) to help reduce capital and operating costs; however, flotation metallurgical performance has not improved, Column flotation has only recently shown promise in improving metallurgical performance for iron ore rougher flotation. Previous column flotation success was mainly in scavenger and cleaner flotation steps for treating minerals other than iron ore. Although some new flotation chemicals have been developed for removal of silica and other minor constituents under widely varying mineralogical scenarios, recovery of iron mineral has not improved. The operation and control of flotation circuits have become more challenging because of the increasing workload on flotation. Better sensing, process control and operation of flotation circuits are essential as we go forward. Iron ore upgrading by flotation can be classified into either anionic or cationic methods. Anionic flotation of either iron oxide or silicious gangue is accomplished by collector type, pH control and selective chemical activation . Similarly, cationic flotation of silica or iron oxides is accomplished by collector type, activation and/or pH control. Removal of other minor constituents is achieved by using specialty chemicals under controlled conditions for preflotation, co-flotation or post flotation steps. Generally, anionic flotation is used for floating cleanly liberating crystalline oxidized iron ores such as hematite, specularite and martite. Earthy and hydrated oxides such as hematite and geothite can be upgraded with either anionic or cationic collectors after controlled dispersion of slimes or prior removal of slimes. Anionic flotation of silicious waste can be achieved by calcium activation of silica. For magnetic iron ores small amounts of locked silica particles (middlings) can be removed by cationic silica flotation, which is the only method in commercial use in North America today. Historically the efficiency of these iron ore flotation processes has been restricted by the loss of fine iron particles (minus 500 mesh) to the tailings product. New technology is required to overcome this loss and improve overall flotation performance. Development of technology for more selective separation of silica and other minor undesirable constituents from iron ore will provide both quality and cost benefits to the iron and steel producers. Development of future iron ore production in North America will face stiffer technical challenges. These new and undeveloped iron ore deposits are largely oxidized (non-magnetic) and by nature contain more slimes and other undesirable constituents. Unless other new technology evolves, flotation will be the major treatment process required to upgrade these difficult low grade iron ores.

Jan 1, 1993

By W. E. Benton

The name Perlite applies to both a hydrated volcanic glass containing from 2% to 5% combined water and to the lightweight material that is produced from expanding the sized volcanic glass. Upon heating, Perlite expands to about twenty times its original volume which results in a material of low density, low thermal conductivity, and high sound absorpt'ion. Perlite ore is mined by open pit methods and is crushed and sized to provide specific gradations for expanding into products used in acoustical tile, built- up roofing, filtration, lightweight concrete and horticultural applications, among others. In 1983, the U.S. production of crude Perlite came from 12 mines and 6 western states, with apparent consumption and production estimated to be about 6% lower than 1982. The average price per ton was slightly higher than in 1982.

Jan 1, 1984

By Ning Wang, Tengfei Guo, Wanyan Li, Hanjie Wen, Hannian Gu, Zehai Li

Red mud has been reported as a potential resource for lithium. To investigate the leaching behavior of lithium, a lithium-rich red mud was neutralized with hydrochloric or oxalic acid and then leached with acetic acid. When red mud was neutralized using dilute hydrochloric acid, about 58 to 60 percent of lithium was leached with 25 percent acetic acid at 95 °C for 60 min, while more than 95 percent of sodium and 85 percent of calcium were dissolved in the leachate solution. When oxalic acid was used to neutralize red mud prior to acetic acid leaching, lower lithium leaching efficiencies of about 42 to 47 percent were observed. Nevertheless, these leaching efficiencies of lithium were close to that of calcium and much higher than those of sodium under the same conditions. In this study, 25 percent (v/v) of acetic acid at 85 °C for 60 min was demonstrated to be the optimum conditions for lithium extraction from oxalic acid-neutralized red mud using acetic acid. The results are useful and of interest for lithium recovery and purification from red mud.