Browsing by Subject "Iron ore"

Now showing 1 - 20 of 25
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    Bentonite Survey
    (University of Minnesota Duluth, 1999-10) Bleifuss, Rodney L
    The objective of this study was to examine the mineralogical characteristics of the various bentonites in greater detail to determine if subtle differences in the mineralogy could be related to the chemical analyzes and physical test data and perhaps explain the anomalous plant performances reported. The study was based on field samples collected from four of the bentonite companies operating in Wyoming and on representative bentonite samples provided by the taconite plants operating in Minnesota. Chemical and physical tests were run on all of the samples. X-ray diffi-action .patterns obtained from the bentonite samples under different conditions: "as received", minus 2 micron-air dried, minus 2 micron-w/glycol, and minus 2 micron after heat treatment at 250°C.
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    Chemistry, Mineralogy & Liberation Characteristics of Samples of EVTAC Concentrator Unit Operations
    (University of Minnesota Duluth, 2005) Niles, Harlan B
    Minnesota taconite operations frequently encounter quality problems due to chemical-mineralogical variations in crude ore blends. Mine personnel have expressed interest in determining ore blend behaviors in unit operations of concentrators. This knowledge could assist in providing ore blends that produce more uniform and desirable final concentrates. The behavior of ores in intermediate concentrator stages may also help concentrator operators to adjust units to produce optimum results. A project proposal submitted to the Permanent University Trust Fund (PUTF) to determine chemistry, mineralogy, and indicated magnetite liberation for samples of unit operations of two EVTAC ore blends was approved. Feed, concentrate, and tailing samples from concentrator unit operations that represented two crude ore blends were received by the Coleraine Minerals Research Laboratory (CMRL) in 2001 and 2002. They were designated Set 1 and Set 2, respectively. The samples were dried, mixed, and split into portions for "As Is" Davis tube magnetic separations and other splits to be pulverized for chemical analyses and for x-ray diffraction. Chemistry was run at the CMRL and x-ray diffraction patterns were run at the University of Minnesota Shepherd Laboratory in Minneapolis. Mineral percentages in each sample were calculated from the chemical analyses on a spreadsheet in a "Quattro Pro for Windows" computer program after examining x-ray patterns to determine the minerals that were present. The spreadsheet was adjusted to comprehend minerals present and their chemical compositions, and so that the sum of mineral percentages in a sample was within 0.50 percent of the chemistry total oxides (near 100 percent). The results of “As Is" Davis tube separations are given in Table I. It shows magnetic weight recoveries and concentrate iron and silica percentages and provides an indication of the progressively improved magnetite liberation through the concentrator operations. It also shows that liberation in sample Set 2 was somewhat better than in Set 1, and, when compared to the sample chemical analyses in Table 2, separation efficiencies in concentrator units are demonstrated. Calculated mineral percentages in cobber feed samples showed that total silicates were nearly equal in Sets 1 and 2, that the hematite percentage was considerably higher in Set 1, and that total carbonate was higher in Set 2. In the final concentrates, most hematite and silicates had been rejected from both sets, but the total carbonate from Set 2 was 3.6 percent, about double that for Set 1. A set of bar graphs was made for each unit operation, which shows percentages of each mineral in the feed, concentrate and tailing. They illustrate the recovery and rejection of each mineral in each concentrator operation. Company personnel may therefore distinguish the effectiveness of each unit in recovering and rejecting particular gangue minerals.
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    Correlation of Metallurgical Testing of Mine Samples to Plant Feed and Concentrate
    (University of Minnesota Duluth, 2007) Benner, Blair R
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    Cost Comparison of Underground and Surface Mining Options for Potential Western Mesabi Range Iron Ore Resources
    (University of Minnesota Duluth, 2011-05) Zanko, Lawrence M
    This summary report compares capital and operating costs associated with hypothetical underground and surface mining operations located on Minnesota’s Western Mesabi Iron Range. Spreadsheet cost models developed by the author are used for generating the comparative cost data.* The models are based in part on underground and surface mine cost information provided in InfoMine USA, Inc. Mining Cost Service. Model output is intended to provide only an approximation of capital and operating costs associated with both underground and surface mining, and should be viewed accordingly. “Ore” is considered to be restricted to sub-members Lower Cherty 4 and Lower Cherty 3 (LC-4 and LC-3). Note that the stripping ratio increases from about 4:1 to 6:1 approximately one mile to the south of the Biwabik Iron Formation’s southern subcrop extent. Currently, the stripping ratio at active Minnesota iron ore (taconite) surface mining operations is at about 1:1. Based on the Biwabik Iron Formation’s overall dip of 5-10° to the south in the area of interest, for every mile that mining progresses down-dip, the depth to ore increases by about 700 feet. Therefore, the ore zone (LC-4 and LC-3) of any mine developed more than one mile to the south of historic iron ore mining activity will be more than 1,000 feet below ground surface.
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    Development of a Bed Permeability Test for Iron Ore Sintering
    (University of Minnesota Duluth, 2012) Englund, David J
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    Evaluation of Indian Iron Ore for Direct-Reduction Pellets
    (University of Minnesota Duluth, 1991) Goetzman, Harold E
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    Final Report: Shallow vs. Deep Bed Sintering
    (University of Minnesota Duluth, 2010) Englund, David J
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    Investigation into Production of Iron Ore Concentrates with less than 3 percent Silica from Minnesota Taconites Report Two · Erie Concentrate
    (University of Minnesota Duluth, 1991-06) Benner, Blair R; Bleifuss, Rodney L
    The pellets produced by Minnesota taconite companies generally contain between 4.0 and 7.0 percent silica. These silica levels were established initially by the concentratability of the ore, that is, its response to closed circuit ball mill grinding and magnetic concentration. Those operations that had taconite that was easy to concentrate generally produced lower silica pellets. As processing technology improved and it became possible to achieve lower silica levels constraints imposed by the blast-furnace operation became limiting. These constraints related primarily to sulphur and alkali levels in the furnace which control both the volume and chemistry of the furnace slag. Because the trend in blast-furnace practice has been to move toward lower slag volumes, pellets with lower silica levels have become more desirable. Recent extensive installation of external hot metal desulphurization facilities at many steel works allows even lower slag volumes. The basic driving force to go to lower slag volumes is the cost and availability of high quality metallurgical grade coke and related environmental problems. The recent move to produce fluxed pellets has made lower pellet silica levels more attractive because of the lower palletizing costs related to both the lower flux addition and higher production rates with a lower silica content. A common target silica level in fluxed pellets is now about 4.0 percent. A 4.0 percent silica pellet requires a concentrate containing between 3.7 and 3.9 percent silica depending upon bentonite addition levels. This lower silica level has been accomplished in some plants by the use of fine screens, while other plants require the use of silica flotation. The lower silica level has been accomplished at a relatively small incremental cost, generally less than $0.50 per ton. With increasing pressure from the blast furnaces for lower-silica pellets to reduce coke consumption, concentrate silica levels on the order of 3.0 percent may be common in the future. In addition to the need to produce a lower silica blast-furnace feed, there is a potential need to produce even lower silica concentrates, below 3.0 percent, as feed stock for direct steelmaking. Worldwide the current research emphasis is on the development of a coal-based direct-steelmaking process to replace the conventional two step, blast furnace-basic oxygen furnace, process. Most of the current prototype direct steel making processes would benefit from a lower silica feed. These low silica levels will require increasingly complex and expensive secondary treatment of normal magnetic concentrates which exceed the capability of current taconite processing flowsheets. The purpose of this test program is to establish the lower silica limits that can be achieved by current technology for various Minnesota taconites and gain a preliminary indication of the cost.Because the magnetite concentrates produced by different taconite plants range significantly in terms of their size-silica relationships the program included three different concentrate sources for evaluation. Major differences will exist between concentrates produced in a fully autogenous grinding system and those produced in a conventional rod mill-ball mill circuit in which the ball mills are closed with hydrocyclones and/or a combination of hydrocyclones and fine screens. There are also differences in the nature of the siliceous gangue minerals in the various operations. The concentrates from the western Mesabi range contain quartz and low- grade metamorphic iron silicates such as minnesotaite, stilpnomelane, and talc and iron carbonates. The concentrates from the east Mesabi metamorphosed iron formation contain high grade metamorphic iron silicates such as cummingtonite, grunerite, and fayalite as well as quartz. The type of gangue mineral greatly affects the ability to upgrade the concentrates by silica flotation. The purpose of this test program is to determine the lowest silica content that it is technically possible to produce from three different concentrate sources representing the east Mesabi metamorphosed iron formation (Erie), the unmetamorphosed central range produced in a rod mill and ball mill circuit (Minntac), and the unmetamorphosed western Mesabi produced in an autogenous milling circuit (Hibtac). Sufficient data were collected to allow preliminary cost estimates to be made at several silica levels. The cost estimates will be based on reagent consumption, regrind power and metal requirements, and iron recovery. This report contains all of the information obtained on the Erie samples. This includes the results of the initial characterization studies, basic bench scale beneficiation test results, pilot plant flotation data, and the results of the secondary and tertiary treatment of bulk flotation froth to improve overall iron recovery.
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    Iron Ore Green Ball Porosity Measurements
    (University of Minnesota Duluth, 2005-09-13) Kiesel, Richard F
    The objective of this research project is to investigate the potential for mercury porosimetry to measure and characterize pore characteristics for iron ore green balls and fired pellets. Pellet porosity is significant to the diffusion of oxygen during the oxidation and reducing gases through fired pellets and therefore critical to both physical and metallurgical quality.
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    Iron Ore Processing Improvements through Process Modeling and Computer Simulation - 2003
    (University of Minnesota Duluth, 2003-09-05) Ersayin, Salih
    When the Concentrator Modeling Center was established in 1998, its first task was to define the prevailing conditions in terms of taconite plant simulation. Capabilities of existing software and unit operations needing improved models were defined. Preliminary simulations were carried out to determine how accurately the existing models could simulate taconite plant operations. Plant data was analyzed to determine how taconite plant operation could be simulated and to define the common problems and bottlenecks. It also provided some insight in terms of model development. This work indicated that there was a need for improved model development for the unit operations commonly used in taconite processing. Therefore, the Center's task was defined as "to develop advanced models, while providing simulation based assistance to the taconite plant operators using available simulation capabilities. n On the model development side, the specific objective was to develop improved models for magnetic separators, hydroseparators, fine screens and mineral liberation. Despite unsuccessful attempts to obtain federal funding for this type of work due to unwillingness of federal sources to fund projects that would benefit only a smaller section of the mining industry, the Center managed to improve the very simple models available for these unit operations using its plant database and limited funding for specific projects, Now it has the capability of simulating taconite processing more realistically. This was achieved . by analyzing available plant data and developing theoretical understanding of how these unit operations function, and along with pilot scale testing in the case of fine screen modeling. The Center's task was not only to develop these models, but also to incorporate them into the existing software, Usim Pac. Models for magnetic separators and hydroseparators were converted to the programming language of the software. The liberation model is expected to be incorporated soon. The Center's simulation efforts were concentrated on case studies involving the Evtac and lspat Inland plants. While replacing hydrocyclones in a ball mill grinding circuit with fine screens was the focus of study in the former plant, improving overall plant performance was the aim in the latter, which is still an on-going project funded by the DOE. Another simulation study was carried out to determine benefits of ore segregation in one of the taconite plants.
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    Liberation Characteristics of Taconite Plant Feeds
    (University of Minnesota Duluth, 2007) Ersayin, Salih
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    Next Generation Metallic Iron Nodule Technology in Electric Arc Steelmaking – Phase II
    (University of Minnesota Duluth, 2010) Fosnacht, Donald R; Iwasaki, Iwao; Kiesel, Richard F; Englund, David J; Hendrickson, David W; Bleifuss, Rodney L
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    On-Line Measurement of Moisture Content of Iron Ore Slurries
    (2014) Gao, Feng; Davis, Richard A
    This report presents a method of measuring moisture content in iron ore slurries using the application of microwave. The composition of iron ore slurries consists of magnetite, hematite, calcium carbonate, magnesium carbonate, siderite, alumina, silica, and water. When being placed in an electromagnetic field, interactions will happen between the slurry components and the field. Permittivity ϵ^* is the main parameter to describe these interactions. Since water has the largest dielectric constant compared with other materials, the water content of the material can be estimated from measured permittivity values. For each species, attenuation and microwave phase shift are two intermediate functions related to permittivity, temperature and bed depth when a microwave is passing through particles on conveyor belt. According to theory, a linear model is expected between the materials’ moisture content and the ratio of attenuation and phase shift.
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    Pot Grate Induration Simulator
    (University of Minnesota Duluth, 2007) Englund, David J; Davis, Richard A
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    Production of Low-Silica Concentrates from Mesabi Taconite
    (University of Minnesota Duluth, 1993) Benner, Blair R