Browsing by Author "Niles, Harlan B"

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Beneficiation of Hydrofracturing Sand from the Minnesota Fracsand Company
(University of Minnesota Duluth, 1986) Niles, Harlan B
The Minnesota Fracsand Company (MFC), a division of J. L. Shiely Company, requested the assistance of the Coleraine Laboratory of the NRRI in determining a method of beneficiating one of the products of the quarry at Jordan, Minnesota. MFC wishes to sell the product, called "plus 18", as a hydrofracturing sand for use in oil and gas wells. Most of the "plus 18" consists of well rounded quartz grains that are suitable for this application. However, about 20 percent of the product consists of agglomerate particles of small quartz grains cemented by iron oxide. These particles, called clusters, fail under pressure so that unacceptably large volume losses of more than 18.5 percent occur during the compression test for hydrofracturing sand. The maximum loss for this size sand is 16 percent so the cluster content must be reduced to a level that will produce acceptable crush resistance test results. A small sample of "plus 18" was submitted by MFC for preliminary work to determine potential beneficiation methods. Examination using a low magnification microscope indicated that dry high-intensity magnetic separation (HIMS) could be an appropriate method of removing the clusters. Subsequently a concentrate produced on a laboratory model HIMS machine at Coleraine and tested by MFC met the volume loss requirement.
Characterization of Residue from the Pressure Oxidation Leaching of Bulk Copper-Nickel Sulfides from the Duluth Gabbro
(University of Minnesota Duluth, 1999) Benner, Blair R; Niles, Harlan B
The copper-nickel bearing material in the Duluth Gabbro represent a potentially significant reserve of copper and nickel with lesser amounts of cobalt and platinum group elements (PGEs). To help promote the development of this resource, the Coleraine Minerals Research Laboratory (CMRL) has conducted a series of investigations into methods of processing the material. A bulk sulfide flotation process followed by oxidation pressure leaching resulted in high extractions (>98 %) of the copper and nickel in the flotation concentrate. During the leaching, the iron in the flotation concentrate leaches and precipitates as either hematite (crystalline or amorphous) or as a basic iron sulfate (jarosite). The leaching should also leave the PGEs in the residue. If the hematite was present as a crystalline material, then if may be possible to recover a high grade iron product from the residue. If any PGE minerals could be found, then it may be possible to develop a method to recover and concentrate the PGEs. The Minnesota DNA through the Minerals Coordinating Committee funded the current study. The purpose of the research was to characterize the leach residue as to the iron bearing material and to determine if any PGE minerals could be found either by X-ray diffraction (XRD) or by electron microprobe analysis.
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.
Duluth Complex Mineral Separations
(University of Minnesota Duluth, 2001) Niles, Harlan B
The Minerals Division of the Minnesota Department of Natural Resources (DNR) is examining leaching characteristics of minerals that would likely be present in tailing produced by mining and concentrating copper- and nickel sulfide-bearing ores from the Duluth Complex. The Coleraine Minerals Research Laboratory (CMRL) of the Natural Resources Research Institute submitted a project proposal to provide concentrates of silicate minerals for DNR leaching studies. The DNR accepted the proposal and funded the project for $14,210.
Evaluation of the Carbonate Resources of Southern Minnesota
(University of Minnesota Duluth, 1990-04) Niles, Harlan B; Mossler, John H
The Paleozoic carbonate deposits in southeastern Minnesota, consisting of several formations ranging from limestone to dolomite, constitute an important mineral resource of the state. They are quarried quite extensively for aggregate, aglime, and dimension stone, but new uses being developed for carbonate rocks often require greater adherence to specifications for chemical composition than is now required. Because no comprehensive study of chemical compositions of the several formations was available and because this information must be provided to potential producers and consumers for expansion of the industry, this evaluation by the Natural Resources Research Institute (NRRI) was approved for funding by the Minerals Coordinating Committee (MCC) through the Department of Natural Resources (DNR). The duration of the project was from October 1, 1987, to June 30, 1989, and the amount of funding was $168,300. Because no sample materials from previous studies were available for additional chemical analyses, most samples for this evaluation were taken by channel sampling, diamond drilling, or sampling split core from two drill holes that are stored by the DNR. The Minnesota Geological Survey (MGS) provided county maps with possible sampling sites keyed to references and provided consultation and background information on the various carbonate formations and their general characteristics. Channel sampling sites were selected to provide reasonable geographic distributions of the formations and maximum stratigraphic sections of fresh rock. Sample sites were briefly described and continuous samples taken with hammer and chisel over the sections. Channel samples were taken at 45 locations over 1423 vertical feet to provide 196 assay intervals. Diamond drill core sampling was undertaken to provide samples of formations at locations not well exposed for channel sampling and where high vertical faces were not otherwise accessible. The 17 holes at 15 locations totaled 1724 vertical feet and provided 300 assay sample intervals. The MGS supervised drilling, collected and logged core, and provided detailed stratigraphic descriptions. The core was split and one half is stored by the DNR in Hibbing. All samples were crushed, pulverized, and analyzed at the Coleraine Research Laboratory (CRL). Chemical analyses were run on 615 samples representing 3774 feet, and differential thermal analyses (OTA) were run on 307 samples representing 2236 vertical feet. Most samples assayed for this evaluation are classed as dolomites with an encouraging number containing more than 90.0% CaC03 + MgC03 over intervals of more than 20 feet. Most of these locations would require selective mining practices and/or beneficiation to produce moderate or high purity carbonates. Formations of the Devonian System were sampled only in Mower County where both the Cedar Valley and the Spillville Formations trended to higher purity from west to east. A high purity unit of the Stewartville Formation, approximately 50 feet thick, is present in Olmsted and Fillmore Counties. Many Prosser Formation sections are impure dolomites to dolomitic limestones, although several 15- to 45-foot thick moderately pure units do occur. The only true limestones (less than 10% of the carbonates as dolomite) noted in the Prosser Formation were sampled in Fillmore County. Most Platteville sections sampled are classed as impure dolomites· to dolomitic limestones often with relatively high sulfur contents. Only in Fillmore County was the entire Platteville section classed as limestone, and it was also impure. Most Shakopee Formation samples were impure dolomites, but one 30-foot section in northwestern Scott County was exceptionally pure with 95.4% CaC03 + MgC03• The Oneota Dolomite is one of the most prominent and extensively quarried formations in the project area. In the West from Mankato northward, it is classed as impure dolomite with very few thin units that are not impure. However, in the eastern counties, the Oneota includes many 20- to 80-foot sections that are moderately and even highly pure. Additional evaluations of Minnesota carbonate rocks should include benefication testing to develop methods of producing carbonates to meet consumer specifications for new applications. Selective mining, Munsell color determinations, and relationships between calcining characteristics and differential thermal analyses should be further investigated.
Metallurgical Testing of Copper-Nickel Bearing Material from the Duluth Gabbro
(University of Minnesota Duluth, 1998-12) Benner, Blair R; Engesser, John; Niles, Harlan B
Photomicrographs of the Minerals of the Central and Western Mesabi Range
(University of Minnesota Duluth, 2009-09) Niles, Harlan B
The paper consist of photomicrographs that show colors, forms, occurences, and associations of minerals of the central and western Mesabi Range. These minerals are minnesotaite, talc, stilpnomelane, greenalite, chlorites, quartz, carbonates (mostly siderite and ankerite), magnetite, hematite, and goethite.
Physical and Image Analysis Sizing of Mine Run Taconite Ore
(University of Minnesota Duluth, 1993-10) Niles, Harlan B
The United States Bureau of Mines (USBM) has developed an image analysis system to determine the size distribution of mine-run taconite ore. The results can be used to evaluate fragmentation so that blasts can be designed for better productivity. ~he Coleraine Minerals Research Laboratory (CMRL) has been testing the system at Minntac with apparent success, but there was no method available for testing the accuracy of size distributions determined by image analysis. The Iron Ore Cooperative Research Committee approved and funded a project to screen mine-run ore and compare the results to sizing by image analysis. Three samples, about 2500 tons each, were sized on 6 and 12 inches in a contractor's vibrating grizzly plant at Minntac. Size analyses were extended to 65 mesh by sizing samples of minus-6 inch at the Coleraine laboratory. Between 30 and 60 plus- 12 inch pieces from each bulk sample were measured to provide thickness-width-length aspect ratios and to indicate large-fragment dimensions and weights that are encountered in mine-run ore. The average ratio of thickness to width to length was 1.00:2.20:3.21. Fragment volumes ranged from 4 to 80 cubic feet. Weights of these would be approximately 800 pounds and 16,000 pounds. After the size fractions had been weighed, they were recombined, each sample was loaded into rail cars, and they were dumped at number one primary crusher. The USBM and CMRL video-taped the ore as it was dumped and processed the tapes through a computer to produce an image analysis size distribution for each of the three samples. Because of a large discrepancy between the contractor's and the track scale weights, the size analysis of sample number one was not acceptable. The physical size analyses of samples two and three and their corresponding image analysis size distributions were nearly identical for fragment widths of at least 12 inches. Size. distributions of mine-run ore by the image analysis system have been proven reliable for evaluating the effective fragmentation of individual blasts for sizes down to 12 inches in width.
Potential Value Added Products from the Minnesota Ilmenite Deposits
(University of Minnesota Duluth, 2002-10) Benner, Blair R; Niles, Harlan B
As part of the University of Minnesota’s ongoing support for the development of ilmenite deposits located within the Duluth complex, the University’s Permanent Trust Fund sponsored a project by the Coleraine Minerals Research Laboratory to determine if valued added products could be produced from the ilmenite deposits and to determine if ilmenite recovery could be increased. A previous study sponsored by the Minerals Coordinating Committee indicated that using high pressure rolls in place of a rod mill to grind the ilmenite increases TiO2 recovery by about 10 percent. The major loss of TiO2 (about 25 %) was associated with the removal of magnetite by magnetic separation after spiral concentration. The objective of this program was to determine if the magnetic portion of the spiral concentrate could be upgraded to make a concentrate suitable for either blast furnace pellet feed or DRI feed. During upgrading of the magnetic portion, non-magnetic materials should contain the bulk of the ilmenite, and they would also be upgraded to determine the potential for additional ilmenite recovery. Initial liberation grinds and Davis tube tests on the spiral magnetic concentrate indicated that grinding and magnetic separation alone could not upgrade the material sufficiently. Standard silica flotation on the ground and magnetically separated material did not provide significant upgrading. The best concentrate produced contained 58.84 percent iron, 6.66 percent TiO2, and 5.74 percent silica. Perhaps this material could be used in the iron nugget process. Amine flotation, fatty acid flotation and WHIMS were used to recover TiO2 from the non-magnetic portion of the reground spiral magnetic concentrate. Only fatty acid flotation of the ilmenite showed any potential for recovering additional ilmenite at grade. Additional test work on the use of silicate depressants is needed. Elutriation tests on size fractions indicated that grinding to finer than 200 mesh is needed for liberation of the ilmenite from the silicate gangue. While the previous test work showed increased TiO2 recovery in the spiral nonmagnetic fraction, no work was conducted on upgrading that material to determine if the increased recovery could be carried through to a final concentrate. Therefore, bench scale electrostatic separator tests were run on the spiral non-magnetic fraction produced in the previous project. The electrostatic tests indicated that both grade and recovery could be obtained.
Properties and Aggregate Potential of Coarse Taconite Tailings from Five Minnesota Taconite Operations
(2003-12-01) Zanko, Lawrence M; Oreskovich, Julie A; Niles, Harlan B
The goal of Zanko's study is to evaluate the technical and economic viability of using coarse taconite tailings for aggregate purposes in road construction. Making use of this mining byproduct makes environmental sense because it maximizes the use of a resource that has already been mined and crushed. The report presents well-documented, technical data from five sites relating geological, mineralogical, and chemical properties to performance when used in road construction. A series of aggregate tests demonstrated the suitability and durability of coarse tailings as a component of bituminous asphalt. In addition, state-of-the-art testing methods showed that none of the samples contained asbestos. In terms of the marketing potential, low-cost rail transportation and a workable distribution plan would be key for expanding the use of coarse taconite tailings as aggregate in markets beyond Northeastern Minnesota.
Properties and Aggregate Potential of Coarse Taconite Tailings from Five Minnesota Taconite Operations
(University of Minnesota Duluth, 2003-12) Zanko, Lawrence M; Niles, Harlan B; Oreskovich, Julie A
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, John
The 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.
Size Distributions of Taconite Ore by Image Analysis of Video Tapes of Muckpiles
(University of Minnesota Duluth, 1994-02) Niles, Harlan B
A computer-based digital imaging system has been developed by the United States Bureau of Mines (USBM), with the assistance of NORAMCO Engineering Corporation of Hibbing and the Coleraine Minerals Research Laboratory (CMRL), to determine size distributions of mine-run taconite ore. One such system, operating at a primary crusher at United States Steel's Minntac mine, produces size distributions of mine-run ore that are accurate for fragment widths of 12 inches and more. The CMRL proposed a project to develop a method of sizing mine-run ore in muckpiles by image analysis. These size analyses could provide rapid evaluations of blast fragmentation so that later blasts could be designed for more effective breakage. It was assumed that video tapes of muckpiles processed through an I.A. computer program could provide these rapid analyses. The Iron Ore Cooperative Research Committee approved and funded this project. After the CMRL camcorder was calibrated so that I.A. size distribution computer output could be converted from pixels to inches, several muckpiles at Minntac and at Eveleth Taconite were video taped at lens-to-subject distances of 24 to 116 feet. Video tape size distributions from one Minntac muckpile were compared to the size distributions established for that blast at the primary crusher. The size distributions from the muckpile were much coarser than those from the crusher which indicated that fragment resolution at the long distances was too insensitive to provide accurate sizing. The same Minntac blast was then video-taped by the CMRL by walking over the muckpile so that the lens-to-subject distance was 7.5 feet. Size distributions from this video tape were quite close to the average size distribution established by 120 trains at the primary crusher. This indicated that video tapes could be representative of muckpile surfaces and that the I.A. resolution is adequate at the shorter distance. Additional experimental blast areas will be video-taped by the CMRL by walking over muckpiles to generate size analyses to compare to sizing of the same blasts at the primary crusher. If these sets of size analyses are very similar and both muckpile and crusher data show the same size variations between experimental areas, the sizing method could be recommended for use at all Minnesota taconite mining operations.
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.

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