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By Donald S. Bubar

The Separation Rapids property, located approximately 60 km (37 miles) north of Kenora, Ontario, Canada, is host to one of the largest rare metal pegmatite deposits in the world. This pegmatite was named the Big Whopper by its discoverer, Dr. Fred Breaks of the Ontario Geological Survey, because of the exceptional length and width of the surface exposure. The property is readily accessible from a main, all-weather road via a network of secondary logging roads. The main line of the Canadian National Railway passes through the village of Redditt, just 40 km (24 miles) south of the property. The Big Whopper is one of the complex-type (petalite sub-type) class of rare metal pegmatites that are geochemically the most highly evolved in the spectrum of granitic pegmatites. Such deposits are economically important as resources for the rare metals lithium, tantalum, cesium, and rubidium. While complex-type pegmatites are found in many areas of the world, most are too small to be profitably mined, however, with an inferred resource in excess of 15 million metric tons (mt) (17 million short tons [st]), the Big Whopper is only the fourth deposit of its type in the world with the size required to be of major economic importance. The other three deposits, which are currently in production, are the Tanco mine in Manitoba, the Bikita mine in Zimbabwe, and the Greenbushes mine in Western Australia. The Big Whopper is situated in the eastern continuation of the Archean Bird River greenstone belt which also hosts the Tanco pegmatite, approximately 60 km (37 miles) to the west. The principal commodities identified in the portions of the Big Whopper pegmatite explored to date are petalite (LiAlSi4010) and rubidium-rich K-feldspar. These are industrial minerals with important applications in the glass and ceramics industries. The Big Whopper also contains substantial quantities of lepidolite, a lithium, rubidium-mica which is the principal ore mineral for rubidium metal. Tantalum and cesium occur in anomalous levels with the petalite mineralization, and the possibility of finding zones of high enrichment in these valuable high-tech metals elsewhere in the deposit is excellent. Such enriched zones are typical of pegmatites as highly evolved as the Big Whopper. To date, the geological mapping and diamond drilling work completed by Avalon have delineated the Big Whopper pegmatite system over a strike length exceeding 1.5 km (0.9 miles), over widths ranging from 10 m to 80 m (30 feet to 260 feet) in thickness, and to a vertical depth of close to 300 m (1,000 feet), where it remains open. The pegmatite system consists of a vertically oriented massive petalite pegmatite dyke striking 280 degrees that is flanked by amphibolites containing a swarm of narrower albite and petalite dykes which have all undergone intense deformation in a high strain zone resulting in folding and intense shearing. The Big Whopper exhibits a mineralogical zonation pattern which is complicated by the superimposed deformation that has both folded and stretched the deposit. Drilling has defined a dilute geological resource totaling 7.1 million mt (7.8 million st) grading 1.283 percent Li20, 0.346 percent Rb20, and .007 percent Ta205 over a strike length of 600 m (2,000 feet), and to a vertical depth of 250 m (820 feet), where it remains open. The petalite and rubidium-rich-K-feldspars contained in the Big Whopper all appear to be of superior quality. The grades are consistent with a petalite content averaging 25-30 percent and a rubidium-rich-K feldspar content averaging 15-20 percent. The remainder of the rock consists mainly of albite, several types of mica, and quartz. Accessory minerals include columbitetantalite, cassiterite, apatite, garnet, and gahnite. Market studies show that the deposit is located close enough to existing transportation infrastructure to access rapidly growing, major markets in the glass and ceramics industries, both in the northeastern U.S. and Europe. There are only three competing lithium minerals producers in the world with the Bikita mine in Zimbabwe being the only major producer of petalite. The other lithium deposits produce spodumene, a less desirable lithium mineral. Lakefield Research Limited has successfully designed a process to produce an ultra-pure petalite concentrate containing up to 4.65 percent lithium oxide, and as little as 0.014 percent iron oxide, low levels of soda and potash, and negligible amounts of other trace elements. With these specifications, Avalon will have an excellent quality product for glass-ceramics applications such as Corningware®, CERAN® stove tops, and other thermal shock-resistant products. Lakefield is presently designing the balance of the flowsheet to produce separate concentrates of rubidium-rich K-feldspar, albite, mica, tantalum, tin, and high-purity quartz. Initial test work indicates that the feldspar products will be of exceptional quality. The K-feldspar concentrates contain 11-12 percent K20 and 1 percent Rb20, while the sodaspar contains over 10 percent Na20, and both have very low iron (0.01 percent Fe203). A preliminary economic model shows that with an initial production rate of 90,000 mt (100,000 st) per year, expanding to 170,000 mt (190,000 st) per year over 5 years, the project is capable of generating over CDN $10 million per year in pre-tax cash flow by year 5 on a capital cost of approximately CDN $30 million.

Jan 1, 2001

By James H. Dye, N. E. Norman

There will be about 300 raise boring machines used worldwide by late 1981, attesting to the acceptance of this drilling system by the mining and construction industries. Over the past few years, many articles have cited the advantages of raise boring: •improved safety; •faster completion of the raise; •elimination of sublevels; •cost reductions; •better structural characteristics of the opening; •labor reduction; and •noise abatement. The relative importance of each advantage varies from mine to mine. When analyzing the total economics of raising, each advantage must be considered. The factors having the most effect on economics are fixed costs, direct costs, and comparative savings versus conventional methods.

Jan 3, 1981

By Staff

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several stages—basic (mining), intermediate processing, manufacturing of finished goods and construction. The estimated growth rate for the real GDP of the United States for 2006 was 3.2 percent. The nominal GDP was about $13.2 trillion. The value of minerals mined in the United States in 2006 rose significantly because of increased unit price for some metals—particularly copper, zinc and other base metals. There was also a significant reduction in metals stocks. Infrastructure expansion and manufacturing in China and India have been absorbing a significant portion of world output. Domestic production increased for some industrial mineral materials, mainly cement and construction sand and gravel. Production of crushed stone declined less than 1 percent in 2006 compared

Jan 1, 2007

Liebherr Mining Equipment Co., of Newport News, VA and Baxter Springs, KS, introduced the T282, a new two-axle, diesel-electric, AC drive haul truck with a payload capacity of 327-t (360-st). The T282 was unveiled at a press briefing in October 1998 at the company's Baxter Springs research and development1 manufacturing facility. In addition to an increase in pay- load capacity, the truck's AC drive system has been de- signed to allow for easy configuration to a trolley-assist system with minimal additional equipment. The T282 provides fuel savings, reduced maintenance requirements, and reduced downtime and maintenance costs, providing the mine operator with increases in productivity. Basic dimensions and weight of the T282 are: ? Overall length, 14.5 m (47.5 ft). ? Overall width, 8.7 m (28.7 ft). ? Loading height, 6.5 m (21.2 ft). ? Height - body up, 13.9 m (45.9 ft). ? Empty vehicle weight, 201 t (221 st). ? Operating weight - loaded, 528.6 t (582.6 st). ?Engine, Detroit Diesel 16V4000 at 2 MW (2,750 hp). ?Electric drive system, Siemens/Liebherr.

Jan 1, 1999

By Jameel Menashi

Aqueous solutions of Na2Cr04 can be reduced with CO to produce hydrous Cr203 and NaHCO3/Na2CO3. CH3OH, HCOO and HCHO in the presence of CO2 also reduce Cr 6+ and yield similar products. It is shown that the rate of Cr6+ reduction can be represented by the expression -d[Cr6+]/dt=k[Cr6+)1/2[R] where [R] is the aqueous phase concentration of CH3OH, HCOO- or CO. With these three reductants, the activation energies for the reduction processes are comparable and are of the order of 100 kJ/mole. Rapid reduction rates are attained at temperatures in excess of 220°C and, with these three reductants, a green acid-insoluble readily filterable hydrous Cr203 is formed. With HCHO significant reduction of Cr6+ occurs at about 80-100°C and an acid-soluble violet modification of hydrous Cr2O3 is formed. The reduction process is reasonably selective: solutions of Na2CrO4 contaminated with Mo6+ and W6+ can be reduced to yield a Cr2O3 product with significantly reduced contaminant levels. These findings are utilized as a basis for a process for recovering chromium from secondary source materials.

Jan 1, 1984

By Mohammad R. Jafari

The Camp Dresser & McKee (CDM)/Hatch Mott MacDonald (HMM) joint venture has been engaged by the New York City Economic Development Corporation (NYCEDC) to provide engineering ser-vices in connection with the replacement of two existing siphons which cross New York Harbor between Staten Island and Brooklyn. The project involves the construction of a 72-inch diameter pipeline within a 12-foot diameter tunnel beneath the New York Harbor. The tunnel will be constructed using either slurry or an earth pressure balanced (EPB) tunnel boring machine (TBM). This paper presents the results of an extensive geotechnical field and laboratory testing program including advanced frozen soil tests (uniaxial compressive strength tests, triaxial tests, and uniaxial creep tests), in-situ vane shear and pressure meter testing, and a marine geophysical survey (seismic reflection technique) to ascertain the complex subsurface conditions along the tunnel alignment and shaft locations. The paper will also discuss the design and construction aspects and the challenges associated with each component of this project.

Jan 1, 2008

By Günter Huber, Bruno Mattle, Helmut Westermayr, Daniel Spöndlin, Max John, Nejad Ayaydin

PROJECT DESCRIPTION Alignment The Strenger Tunnel forms part of the S16 four-lane expressway between Landeckand Bludenz. The construction of this important East-West connection started in 1973with the Arlberg Road Tunnel as its key constituent. Beginning in 1992, solutions for the section between Pians and Flirsch were investigated. Efforts to conserve nature and to avoid potential avalanche and landslide areas led to a solution detouring the villages in the Stanz valley. The starting points were predetermind by the intersections at Pians in the East and at Flirsch in the West. As a result of the expected traffic load and the comparatively high gradient of 2.9%, both one-way, two-lane tubes were constructed at once. The north tube is 5.851 m long, the south tube 5.775 m, see Figure 1. Layout of Tunnel Cross-Section The tunnel cross-section was determined by 2 × 3.75 m wide, 4.70 m high roadways, two sidewalks and sufficient space for two fans above the clearance

Jan 1, 2005

By Judy B. Jones, Bradley A. Crenshaw, Theodore DePooter

This paper reviews groundwater issues leading to a secondary grouting program at the Chattahoochee Tunnel that was implemented subsequent to the contact grouting program. The secondary grouting program was developed based on infiltration data, geology, and testing programs. This paper includes a brief description of the geological features encountered, as well as describing the grouting program. The success of this grouting operation has been quantified by several methods, and is presented to help others project the costs and benefits of this type of program. Review of initial results and refinements of techniques are also discussed.

Jan 1, 2005

By M. H. Basiri

The application of aluminum matrix composites, due to their unique properties, is significantly growing in the variety of industries such as aerospace and automobile. In comparison to other light metals, such as magnesium and titanium, aluminum is lower in price. These are the advantages that this metal dominates the others. In this research, first by applying the lost foam casting method, the SiCp/A356 composite was cast in the bottom and side gate conditions with 690°C and volume fraction of 10%. Furthermore, the effects of reinforcement particles (60 µm, 75 µm) were examined. The results present the particles distribution in the side gate methods is more homogeneous than the bottom gate casting method. Also, by increasing the particles sizes, the fading rate in the side gate are reduced from 22% to 19%, as well as from 26.4% to 25.4% in the bottom gate. Key words: Carbide-Silicone Particle, Gating System, Composite Micro-Structure, Foam Casting

Feb 27, 2013

By Brian Khalighi, Massimo Franceschi, Giovanni Giacomin, Gianni Porta

Headrace Tunnels and parts of the Access Adit Tunnels of Kárahnjúkar Hydropower project, KAR-14, in Iceland will be excavated using three full-face Robbins Tunnel Boring Machines (TBM). TBM sizes range from 7.23 to 7.63 meters in diameter and the total headrace tunnel length is approximately 40 km. The crushed rock is transported on conveyor belts to disposal areas near each Adit. The estimated average excavation rate is approximately 25 meters per day per machine. Electricity will begin to flow in April 2007, and the project is scheduled for completion in 2009. This paper is divided into four sections. In the PROJECT OVERVIEW section, a short overview of the scope of the project is presented. In the GEOLOGY section, the geological condition along the tunnel drives is briefly introduced. The TBM DESIGN section discusses the various design criteria and the resulting machine specifications. The paper concludes in the TBM OPERATION section with a case history describing the tunneling operation from start-up to the time of the writing of this paper.

Jan 1, 2005

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By Qinghua Tian, Zhipeng Xu, Dong Li, Xueyi Guo, Liu Zhu

A possible process for extracting tellurium and antimony from a residue generated in alkaline sulfide leaching of telluriumbearing alkaline skimming slag was proposed. The central composite design was employed to define the optimal leaching conditions for tellurium and antimony extractions from the residue sample. Using a 23 factorial matrix, the best performance for tellurium and antimony extractions (96.36% and 99.64%) were obtained at 175 g L−1 Na2S concentration for 80 °C during 60 min. The notable degree for influencing tellurium and antimony extractions was leaching temperature, Na2S concentration, and leaching time. The analysis of variance results indicated that the regression model was significant and suitable to be used for the optimization of independent variables within the range. The model was validated under optimal operating conditions based on the experimental design results. Antimony and tellurium in the leach liquor were separated and recovered by H2O2 oxidation followed by Na2S-Na2SO3 reduction. 98.93% of antimony was precipitated selectively during H2O2 oxidation, while 95.06% of tellurium was precipitated during Na2S-Na2SO3 reduction. NaSb(OH)6 and elemental tellurium was obtained as the product.

By M. Moagabo

CO2 emissions from carbonate laden reclaimed mine spoil has been shown to pose a hazard to residents in homes built on or adjacent to such land. The objective of this project was to develop a soil CO2 flux survey protocol for assessing reclaimed mine land. The research involved CO2 chamber accumulation flux surveys; stable carbon isotope ratio analysis; statistical hypothesis testing to examine correlation between CO2 flux and soil temperature and moisture as well as spatial dependence; and geostatistics to map CO2 and delineate high flux zones. Soil temperature was observed to have a positive correlation with fluxes while soil moisture was observed to be negatively correlated. Spatial dependence of CO2 fluxes on reclaimed mine land was observed on one of the two study sites. The research suggests that macro-porosity and gas permeability may be important factors that explain CO2 migration in mine spoil. A flux survey protocol has been developed, based on these results, for reclaimed mine lands. The work demonstrates the capability of geostatistical methods to delineate high flux fields. Further research will be required to determine suitable thresholds for such analysis.

Jan 1, 2012

By Steve Kral

Despite low commodity prices and mining industry cutbacks throughout the world, Peru remains one of the industry’s bright spots. The country’s remarkable economic turnaround during the 1990s remains a model for other developing nations to follow. And the Peruvian government has not forgotten the industry that was instrumental in that turnaround. True, the country has not been spared the effects of the mining industry’s retrenchment that has occurred in other parts of the world. However, foreign mining companies remain committed to doing business in Peru. And the government remains committed to attracting foreign investment and maintaining a strong mining industry. This commitment was evident in September 1999during the 24th Convention of the Institutos de Ingenieros de Minas del Peru in Arequipa, Peru. More than 3,000 mining industry professionals from around the world attended the convention. And Extemin, the accompanying exhibit, featured more than 450 companies, many from the United States, Canada, Australia, South Africa and other countries.

Jan 1, 2000

By A. K. Majumder

The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. However, the published literature does not demonstrate its use in the separation of coal fines. Therefore, an attempt was made to study the effects of different process variables on the performance of an MGS for the beneficiation of coal fines. The results obtained from this study revealed that among the parameters studied, drum rotation and feed solids concentration play dominating roles in controlling the yield and ash content of the clean coal. Mathematical modeling equations that correlate the variables studied and the yield and ash contents of the clean coal were developed to predict the performance of an MGS under different operating and design conditions. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 14.67% and a yield of 71.23% from a feed coal having an ash content of 24.61%.

Jan 1, 2007

By W. C. Goldberg, E. M. Frizzell

Monitoring slope displacement in open-pit mines can help predict collapses and prevent serious damage, injuries, and fatalities. Early detection of movement may indicate the need to modify slope geometry, initiate dewatering if the slope is wet, or consider artificial support measures such as cable bolting. Slope monitoring at the Berkeley pit was carried out with varying degrees of intensity and continuity for about 15 years. Some of the old mine records are still intact and accessible. Slope monitoring data can therefore be collected and published for the benefit of other mine operators. Because prediction of slope failures is empirical in nature, publication of several well documented case studies will be a valuable contribution to the industry. Background - Berkeley pit Open-pit mining of copper from the Berkeley pit, located on the east side of Butte, MT, began in 1955 and ceased in 1982. During that time, about 1 Gt (1.2 billion st) of material were removed to form a pit about 1.8 km wide by 2.1 km long (6000 ft by 7000 ft) at the rim, and 550 m (1800 ft) deep as measured from the high hill on the northwest side. From the south side, the pit only measures 365 m (1200 ft) deep. The Berkeley pit was first owned and operated by Anaconda Minerals Co., and subsequently by Arco. Following its closure in April 1982, the mine began to fill with water. Washington Construction purchased the property in 1986, and Montana Resources Inc. began mining to the east of the Berkeley pit in July 1986. Numerous instances of slope failure were recorded during the course of mining and several intensive geotechnical investigations were conducted in an effort to optimize the mine design. One of the last and most comprehensive studies was initiated in 1977. For purposes of geotechnical analysis, the mine was divided into nine design sectors on the basis of geologic conditions, geographic orientation, and economic importance (Fig. 1). Only two of these sectors - the concentrator and the southeast corner - are considered here. Material properties were obtained from several studies of samples collected from the mine and adjacent areas. The slope was monitored using standard surveying techniques to record the amount of movement in an area. The

Jan 1, 1989

By John J. Stetler

Introduction Samarco Mineracao S.A. is a Brazilian corporation jointly owned by S.A. Mineracao da Trindade (SAMITRI) and Utah International Inc., with 51% and 49% interests respectively. Headquartered in Belo Horizonte in the state of Minas Gerais, Samarco owns and operates an open-pit mine capable of producing 10 Mt/a (11 million stpy) of iron ore; a concentrator rated at 7 Mt (7.7 million st); a 12-Mt (13.2-million st) capacity pipeline transportation system; a 7 Mt (7.7 million st) filtering and pelletizing plant; and a harbor facility. The mine, concentrator, and initial pipeline pump station are located at Germano, near the town of Mariana, about 300 km (186 mi) north of Rio de Janeiro by air. The pipeline terminal, pellet plant, and harbor are at Point Ubu, 70 km (43 mi) south of Vitória the capital city of Espirito Santo State, and about 300 km (186 mi) by air east of the mine. The 396-km (246-mi) pipeline uses 508-mm (20-in.) pipe except for a 53-km (33-mi) section where 457-mm (18-in.) pipe is used to absorb and control slack flow through increased velocity in one of the areas along the route. Iron Ore Slurry The hematite iron ore concentrate produced at the Germano plant is processed by grinding the average 53% run-of-mine itabirite iron ore to -150 µm (100 mesh) for gangue liberation. It is treated further by cyclones to remove the 10 µm (1250 mesh) slimes to prepare the ore for flotation. During the multistage cationic flotation operation, the silica is reduced to make low silica (-0.9%) concentrate for the direct reduction (DR) iron-making process or to make normal silica (-3.5% +2.5%) concentrate for the blast furnace (BF) iron-making process. The concentrate then is reground further to meet the particle size requirements for pelletizing. The reground hematite concentrate is screened in closed circuit with the regrind mills for close control of the maximum particle size, not to exceed 3.5% +75 µm (200 mesh) for pipeline wear protection. Thickened concentrates at 70% solids are pumped to four 5-kt (5,510-st)(dry) agitated slurry storage tanks that hold the feed before it goes to the first pipeline system pumping station. Pipeline Capacity The pipeline system was designed to transport 12 Mt/a (13.2 million stpy) at 65% solids with an average minimum safe operating velocity of 1.5 m/s (5 fps). The pipeline will transport 5 Mt (5.5 million st) in 1982. The system, therefore, is moving the slurry in 13-kt (14,330-st) batches, dispatched at intervals to move 20 kt/d (22,050 stpd). In operation, the pipeline has exceeded its 93% availability design factor. Pipeline Facilities Pump station No. 1 is located at the Germano minesite 1 km (3,330 ft) above sea level. It has the following principal equipment: • four 5 kt (5,510-st) (dry) agitate slurry storage tanks; • two centrifugal charge pumps (one stand-by); • a 217-m (712-ft) safety loop; • seven mainline positive displacement triplex plunger pumps (189 m3/h, or 832 gpm, at 14.9 MPa, or 2,162 psi, maximum output pressure); • four corrosion-erosion spools; • a control and command center. Operation The output at pump station No. 1, with 66% solids, is pumped 151

Jan 10, 1982

Instabilities occurred as a result of climate changes caused to investigate the rock behavior dependency to temperature changes, in this paper. In the natural earth condition, the phase transition of pore water has known to be the most effective factor causing different rocks mechanical properties due to temperature changes. So, the temperature range of [-30, 30]°C is selected in laboratory tests of this study. P-wave velocity, unconfined compressive strength (UCS) and elasticity modulus of rocks at different temperatures are studied by developing a temperature adjusting apparatus. The tests were performed on three rock types. The results show that firstly, the temperature reduction and pore fluid freezing improves these rock?s mechanical properties. Secondly, the dependency of rock properties to climate changes depends on the type and shape of its porosity as well as porosity percent. The improvement of rock mechanical properties in jointed rocks exceeds rocks with spherical pores. Finally, maximum changes in rock?s properties occur at [-10, 0]°C, which includes the phase transition of pore fluid. Keywords: Temperature; Rock Mechanical Properties; Pore Fluid; Porosity.

Feb 27, 2013

By J. K. Lemley

The human element in large measure dictates success in contracting relationships. Because of our professional backgrounds, we view contracts primarily as either engineers, contractors or owners. A beneficial contractual environment--one in which decisions, risks and benefits are shared--demands equal consideration of all three points of view. Most of the older cities in the United States, for example, suffer from bad contracts--generalized, patched-together documents that represent an accumulation of modifications originally written to compensate for specific situations that have occurred over the years. Because such documents lack coherence, they often present conflicting instructions which lead to defensive, ultimately destructive attitudes among the parties involved in the day-to-day administration of the project. Good contract development begins with a strong central philosophy to which the details of the contract can be related. First, the owner should establish a comprehensive philosophy in which risks between the parties are identified. Following this, a specific contract document can be written to satisfy this established philosophy. The contrast between two opposed contractual situations, NYC Water Tunnel Number Three and the Seabrook Nuclear Power Plant Cooling Water Tunnels, illustrates how comprehensive, well-written contracts--contracts which share both risks and benefits--provide the basis for achieving quality construction that will reward engineer, contractor and owner.

Jan 1, 1983

By N. A. Abdel-Khalek

The amenability of carbonate separation from a sedimentary phosphate ore using a bioflotation process was studied. Two types of bacteria were chosen for this study. The experiments were performed using oleic acid as collector. The flotation experiments were carried out using statistical designs for optimizing the main operating parameters. A concentrate containing 0.78% MgO and 30.15% P2O5 with a recovery of 92.31% was obtained from a feed containing about 2.45% MgO and 27% P2O5. These specifications could not be obtained using conventional flotation experiments under similar conditions in the absence of bacteria. Measurements of zeta potential, adsorption of bacteria and collector, as well as froth power, were performed to explain the role of microorganisms in the surface modification of both dolomite and phosphate and in their interaction with the collector.

Jan 1, 2009