Browsing by Subject "Hibbing Taconite"

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    Screen Performance Optimization: Part 2a: Smart Screen Systems
    (University of Minnesota Duluth, 2003-09-03) Larson, Thomas R
    A Smart Screen Systems screening device was installed in the pilot plant at the Coleraine Mineral Research Laboratory. As installed, the machine holds one pre-tensioned panel at 25-degrees from horizontal. Currently, single or two panel machines are available, and can be manufactured at the deck angle required for optimum performance. The effective screen cloth surface area on the pre-tensioned panels was 43" wide by 34" long, and the feed stream was distributed evenly along the 43" wide surface. The panel installation system was very simple, consisting of six cams used to hold an edge bracket onto the panel. A single individual can change a panel in just a few minutes. The scope of work for this project follows the pattern set in Part 1, in which five tests were completed on each of two feed samples, one from Hibbing Taconite, and one from Northshore Mining. The scope of work for Part 2 also includes silica and magnetic iron assays on head samples as well as on each size fraction. Otherwise, the test plan was identical to the previous part. For each material, initial tests were completed to achieve the established separation criteria as in Part 1. These criteria were to achieve a split at near 100 microns for the Hibbing Taconite material, and to achieve an undersize grade close to 90% -325 mesh for the Northshore Mining material. Once the panel was selected and other operating issues were resolved, a formal test sequence was conducted using two values for feed rate and two values of feed solids that were just higher and just lower than in the initial tests. The idea was to bracket the optimum separation and measure the variation in screen performance as these two parameters varied. As seen in Table 1, the four tests were completed in a 2x2 pattern, and a fifth test was a repetition of one of the first four in order to measure experimental error.
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    Weakending of Taconite in Small Scale Explosive Tests
    (University of Minnesota Duluth, 2000-11-01) Niles, Harlan B; Bacca, D. A
    The primary objectives in blasting taconite are to produce broken rock that permits optimum digging and shovel loading rates with minimum secondary breakage and eliminates primary crusher delays. Since at least 1990, much of the blasting research by explosives companies, academics, and mining companies has been directed toward determining the downstream benefits of increased blast energy, particularly on crushing and coarse grinding. Several papers have been published that attempt to quantify the cost benefits. However, so many variables are involved that most benefits are only indicated or estimated. A report entitled "Effects of Blasting on Milling," by C. M. Lownds and D. A. Bocca of Viking Explosives & Supply, Inc., and K. Nielsen, Professor, Department of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology, was presented at the 1997 Duluth, Minnesota, SME Annual Meeting. It describes a rather simple method of explosively loading taconite samples and of evaluating the explosive effects on grindability.1 " The small-scale explosive tests were conducted on taconite rock pieces collected from the back of a muckpile instead of on diamond drill core or sawed and drilled cubes, as described in previous work.2 · 3 The testwork described in the following report was proposed as a continuation of the tests on rock fragments to examine more extensively the effects of small-scale explosive tests on rock weakening.