Browsing by Author "Bleifuss, Rodney L"
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Item Bentonite Survey(University of Minnesota Duluth, 1999-10) Bleifuss, Rodney LThe 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.Item Cleanup of Lead Contaminated Soil from Battery Reprocessing Sites(University of Minnesota Duluth, 1990-04) Benner, Blair R; Bleifuss, Rodney LThe hazards of lead in the environment have been a matter of increasing concern over the past several years. The most common sources of lead contaminated soils are those related to abandoned lead battery reclamation sites. There are over 200 such sites in the United States and several real and potential sites in Minnesota. Under present regulations such contaminated soil must be removed and placed in an approved and licensed landfill. The purpose of this study was to demonstrate that by applying conventional mineral dressing techniques it is possible to detoxify a significant percentage of the soil and thereby reduce the cost of landfill disposition. Prior test work at the Natural Resources Research lnstitute's Coleraine Minerals Research Laboratory (CRL) on a sample from a battery reprocessing site in Wisconsin demonstrated that partial detoxification of the soil was practical. The object of this study was to apply similar techniques to material from a Minnesota site. The Shafer Metal site on north Plymouth avenue in Minneapolis was selected for this study after consultation with personnel from the Minnesota Pollution Control Agency and the Minnesota Department of Transportation who own the property. The lead contamination at the Shafer Metal battery reprocessing site occurs in three principal modes: lead metal fragments, surficial coatings of precipitated lead sulphate and lead dioxide, and lead incorporated into fused plastic material. The lead metal consists primarily of fragments of battery plates and connectors. The precipitated lead compounds occur as coatings on the rock and sand particles in the soil. The fused plastic material could have resulted from melting and casting of the lead, or operation of an incinerator. After preliminary sampling to confirm the distribution of lead contaminated soil at the site, three bulk samples of about 800 pounds each were collected for testing. These three samples were subjected to a series conventional mineral processing techniques involving attrition scrubbing, screening, and gravity separation. The tests demonstrated that over 60% of the material can be separated as a clean rock and sand product that can be disposed of on site. About 5% to 10% of the material can be recovered as a lead-rich product that would be acceptable feedstock to a lead smelter. About 25% of the weight would contain so much lead that it would have to be treated as hazardous material. Some 5% to 10% of the material would be rejected as a coarse trash product eligible for disposal in conventional landfills. The EPA Synthetic Precipitation Leach Test for Soils (Method 1312) was run on the rock and clean sand portion which represents over 60% of the material. The tests demonstrated that this material had been effectively detoxified and could be disposed of on site. Based on these test data a treatment flow sheet to detoxify the material represented by the bulk samples taken at the Shafer Metal site was developed. The flow sheet includes the following process steps: I) Coarse screening to remove tramp trash; 2) attrition scrubbing to remove the lead compounds from the coarser rock and sand particles; and 3) gravity concentration to separate a high lead product, a clean rock and sand reject, and a lead-bearing fused plastic product. A minus 165 mesh fines fraction is also produced containing the natural fines from the soil and the lead released by the attrition scrubbing. The recommended treatment flow sheet is based on using conventional mineral processing equipment. The equipment could be sized small enough to be truck mounted, or set up as semi-portable units for on-site treatment. Engineering such a portable treatment plant was included in the extended project, but is beyond the scope of this abbreviated study. Whether treatment of the Shafer Metal site is practical depends upon the cost of building and operating such a treatment plant on site as opposed to direct disposal. It is recommended that this study be extended to include the design and engineering of a portable or semi-mobile treatment plant and that further continuous pilot plant operations be supported to confirm some of the coarse gravity separation steps. There are other similar sites in Minnesota that are contaminated by lead that would be amenable to similar treatment. Costing out the plant required and demonstration of the viability of the treatment flow sheet would make it possible to offer alternatives to the expensive disposal of such hazardous material in a licensed disposal site.Item Investigation in Production of Iron Ore Concentrates with Less Than 3 Percent Silica from Minnesota Taconites – Report One – Minntac Concentrate: A Final Report(University of Minnesota Duluth, 1991) Benner, Blair R; Bleifuss, Rodney LItem Investigation in Production of Iron Ore Concentrates with Less Than 3 Percent Silica from Minnesota Taconites – Report Three – Hibtac Concentrate: A Final Report(University of Minnesota Duluth, 1991) Benner, Blair R; Bleifuss, Rodney LItem 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 LThe 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.Item 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 LItem Round Robin Analyses: (1) EP Toxicity Test: (2) ASTM Water Leach Test(University of Minnesota Duluth, 1988-01-15) Bleifuss, Rodney L; Niles, Harlan B; Engesser, JohnThe Natural Resources Research Institute supervised and evaluated a round robin analyses for the EP Toxicity and ASTM Water Leach tests on samples of incinerator fly ash. Samples were distributed to 14 laboratories for analyses. The leachates were analyzed for Pb, Cd, Hg, As and Se. Statistical analyses of the Pb and Cd data from the EP Toxicity tests give unreliable results for Pb with somewhat better reproducibility for the Cd. The Pb variability within, and between laboratories was very high and a single data point or single test result would be statistically meaningless. The corresponding analyses for Cd are somewhat better. The results for Hg, As and Se are too low for proper evaluation. The results from the ASTM Water Leach test were inconclusive because much of the data reported was below the limits of detection. We assume that the wide variations among the values reported for Pb are in large part related to the extraction step; i.e., the Cd data are better and the Cd compounds are more readily soluble. The data do not permit differentiation between errors related to extraction and those related to the analytical step. It appears logical that the control parameters applied to the extraction procedure are not sufficiently precise.Item Second Quicklime Test 03-4 Balling Circuit November 1994(University of Minnesota Duluth, 1995-01-16) Goetzman, Harold E; Bleifuss, Rodney LThere were two main goals to the second test; to determine the long tenn operability of balling circuits using quicklime and to produce green balls equal in quality to those produced using bentonite without allowing the mixed material to sit before balling. Modifications were made to the 03-4 circuit after the May test in order to achieve both of the above and this test was run from November 8 through November 12, 1994. A summary of the results is given below: The test was a success for two reasons. The 03-4 circuit ran smoothly for 4 days using quicklime instead ofbentonite. -.And, because the circuit ran smoothly, a lot of useful and meaningful data was collected and evaluated. The test was completed safely. There were no incidents or accidents reported during the preparation for or during the test. Levels of ammonia and fugitive dust were monitored during the test and found to be lower than during the May test. The levels detected in both tests were well below MSHA requirements. The green ball quality achieved during this test was higher than that achieved during the May test but below desired levels. However, this test, the May test and pilot plant tests all indicate that acceptable quality green balls can be produced using quicklime under the right conditions. Good quality green balls were produced during the May test when the mixed materials were allowed to sit after being mixed, during pilot plant tests when the materials were mixed for 1 minute and during this test when the mixing time exceeded 110 seconds. There were no unloading or handling problems during the test despite the fact that the pulverized quicklime was contaminated with pebble sized chunks. The supplier, Marblehead Lime Company, indicated that the chunks represented contamination from loading bins at their plant. The fired pellet quality on the entire line dropped during both tests despite the fact that quicklime was being used on only one of the four circuits on the line. This appears to be indirectly related to the use of quicklime. It appeared that, during the tests, quicklime reacted with the water in the bentonite and negatively affected the water absorbing properties of the bentonite. The circuits using the contaminated bentonite then produced poorer quality green balls than the circuit using quicklime. The slightly lower quality green balls produced using quicklime combined with the significantly lower quality green balls made with contaminated bentonite and resulted in lower quality fired pellets. This was suspected in the May test and verified during this test.