Suitability of Pinehurst Formation as a glass sand, Richmond County, North Carolina

SUITABILITY OF PINEHURST FORMATION AS A GLASS SAND, RICHMOND COUNTY, NORTH CAROLINA Robert Mensah-Biney, North Carolina State University Minerals Research Laboratory Leigh Ann Carpenter, J. William Miller, and Benjamin J. Allen, Department of Environmental Studies, University of North Carolina at Asheville; and Jeffrey C. Reid, North Carolina Geological Survey ABSTRACT Split-spoon samples of six drill cores 0 to 60 feet deep within 2,800 acres from the Pinehurst Formation, Richmond County, North Carolina, were evaluated for glass sand raw material potential. The Pinehurst Formation, as mapped on the 1985 Geologic Map of North Carolina, covers approximately 120,660 acres in Richmond, Scotland, Moore and Hoke counties. Commercial glass sand has been produced from a nearby site from the Pinehurst Formation. Minerals were identified with a binocular microscope and by powder x-ray diffraction. Trace amounts of heavy minerals found in the raw material included schorl (a member of the tourmaline group), rutile, and zircon. Less abundant trace minerals were goethite, hematite, muscovite, kaolinite, and chromite. The major mineral present in these samples was quartz, averaging 60-73% of each sample. Several physical separation processes were necessary to make a product suitable for glass application. These included attrition scrubbing, sizing, flotation, heavy liquid separation, and magnetic separation to remove impurities such as iron and titanium minerals, mica, organic matter, feldspar, trace elements, and other impurities. The glass sand product after attrition scrubbing, sizing, and magnetic separation contained 0.13-0.16 % AI203, 0.02 - 0.04% Fe203, < 0.01 - 0.02% Ti02 and traces of other minor elements. Further reduction of impurities will be obtained from separation processes that include flotation. This product is well within the specifications for typical glass sand and is suitable for many glass sand applications. A glass plant is located only a few miles away. Subsequent ongoing collaborative work by the NC Geological Survey and the NCSU Mineral Resources Laboratory are investigating the suitability of the Pinehurst Formation as a frac sand - a higher value product. The proximity of a nearby railroad and the Port of Wilmington, NC provide worldwide market access. Site location map - (above) - Black dot shows site in Richmond County, North Carolina Primary roads Study area w County boundaries Municipal boundaries s Site location map detail - (above) - Map shows primary roads, and municipal and county boundaries. A main line railroad passes adjacent to the study area and goes directly to the Port of Wilmington, North Carolina. I. \ < MOUNT MOUNT GILEAD GILEAD WEST EAST^ ANSONVII Pinehurst Formation Glass sand (frac sand) - (below) -The Pinehurst Formation (yellow) has extensive drill indicated reserves of glass sand that may also prove to be a frac sand. Glass sand (frac sand) - (below) - Detail of figure above showing location of cross sections with sampled drill holes. Refer to image above for isopach color explanation. Yellow lines show cross sections with drill holes used in this study. "AreaOjvFigure 5 3>ectl<5n R83-R35 SJS74 ч . \ LRSir VR35 m q Section- R1-R 1.8 tv ** Г Ф miles -f ■ у j JT"4 — - ' *» » r* . -д-гач*. inn 3 ^^ВзТ4 Гг Y к J < 13 Isopach (feet) of , Pinehurst Formation — ,n50 feet and above у 40 to 50 feet transition I 30 to 40 feet transition ; — 20 to 30 feet transition ‘-it 1 0 to 20 feet transition > Transifiissionlfnes Pipeline^ •- NC381 Site tpandaryvA» YY R1 R40 R49 R50 RSI R41 ♦ R9 R45 ♦ E R18 EL (FT) 1-390 -380 -370 -360 -350 -340 ■330 -320 310 EROSION SURFACE AT OR NEAR TOP OF MIDDENDORF LOOSE SAND (MOSTLY PINEHURST) 1-300 Glass sand (frac sand) - (left) - Generalized cross section - R1 — R18. A black diamond symbol designates drill holes used in this study. This cross section trends ENE across the inset photo with drill holes above left. о L 500 HORIZONTAL SCALE 1000 FT _ I Site location map detail - (above) - Generalized geologic setting showing the site (outlined in blue) superimposed on the 1985 Geologic Map of North Carolina. The primary units in the immediate area of the site are the Pinehurst Formation (Tp) [shown in yellow], and the Middendorf Formation (Km) shown in pale green. County lines are brown. Red-patterned area is some of the reported range of the red cockaded woodpecker. As a protected species available Pinehurst exposure is reduced. Study are is outside the bird’s reported range. Glass sand (frac sand) - (left) - Work is currently underway to evaluate the Pinehurst as a frac sand - a higher value product. The proximity of a nearby railroad and the Port of Wilmington, NC provide worldwide market access. Scale bar in lower left of image. RESULTS Results of the attrition scrubbing tests for samples from individual drill holes are summarized in Table 2. Table 3 lists the results of the flotation tests, and Table 4 shows the summary of the attrition scrubbing tests for the composite samples. The results of the heavy liquid separation tests are tabulated in Table 5. Table numbers correspond to IC33 - see citation below. Table 2. Attrition scrubbing tests* - Samples from individual drill holes. Test Number 6719-1 6719-2 6719-3 6719-4 6719-5 6719-6 6719-7 Sample ID R83 R83 R41 R18 R63 R9 R42 Scrubbed Product Cumulative % Retained US 40 mesh 28.0 26.5 41.0 33.6 37.2 45.3 52.9 US 60 mesh 58.1 56.9 69.2 62.9 57.2 73.9 75.2 US 100 mesh 84.8 84.7 91.0 88.7 76.3 92.6 91.4 US 140 mesh 91.4 91.4 95.7 94.4 81.1 96.2 95.7 Scrub Yield, Wt. %(Note 1) 80.1 80.3 73.8 77.3 62.4 71.9 63.0 Final Non-magnetic Yield, 72.7 70.1 70.2 69.5 59.3 66.9 59.8 Wt. % (Note 2) Final Product Chemical Analysis % Fe203 0.02 0.02 0.01 0.02 0.04 0.02 ai2o3 0.15 0.13 0.14 0.13 0.34 0.16 MnO 0.01 0.01 0.01 0.01 0.01 0.01 C\J о i- 0.01 0.01 0.01 0.01 0.02 0.01 K20 0.01 0.01 0.01 0.01 0.01 0.01 Na20 0.05 0.05 0.05 0.05 0.05 0.05 MgO 0.05 0.05 0.05 0.05 0.05 0.05 CaO 0.01 0.01 0.01 0.01 0.01 0.01 p2o5 0.05 0.05 0.05 0.05 0.05 0.05 Si02 99.6 99.8 98.7 99.1 97.2 98.8 LOI 0.01 0.1 0.07 0.09 0.1 0.1 * Attrition scrubbed at 70 % solids with H2S04 Note 1 - The yield of sand after scrubbing and slime removal. Note 2 - The yield after magnetic separation of the sized product. Table 3. Flotation Test Results - Samples from individual drill holes. Test Number 6719-8 6719-9 6719-10 6719-11 6719-12 Sample ID R83 R18 R18 R41 R18 Depth (meters) 0.00-5.94 5.33-10.36 0.0-10.36 0.00-5.94 0.0 -5.33 Feldspar Tailings Cum. % Retained US 40 mesh 30.7 28.1 33.2 39.4 37.8 US 60 mesh 60.7 57.3 62.1 68.1 66.2 US 100 mesh 86.4 85.5 88.2 91.0 90.9 US 140 mesh 93.3 93.5 94.6 96.3 96.3 Float Yield, Wt.% (Note 1) 80.1 81.0 78.0 74.9 75.5 Final Non-magnetic Yield, Wt. % /fc 1 — Д- — _ 78.3 78.9 76.7 73.8 74.1 (Note Note 1 - The yield of sand after removal of mica, iron minerals and feldspar. Note 2 - The yield after magnetic separation of the sized feldspar tailings. Table 4. Attrition Scrubbing Tests - Composite Sample from all drill holes. Test Number 6719-13 6719-14 6719-15 6719-16 6719-17 6719-18 Scrub % Solids 70 70 65 65 70 70 Scrub Reagent NaOH H.SO. H.SO. NaOH None H,S04 Scrub Time (min.) 5.0 5.0 5.0 5.0 5.0 3.0 Scrubbed Product- Cumulative % Retained US 40 mesh 28.5 33.2 33.0 34.2 31.0 31.3 US 60 mesh 56.7 62.4 62.1 62.8 61.1 60.4 US 100 mesh 84.4 87.8 87.7 87.7 87.2 86.7 US 140 mesh 92.0 94.2 94.1 93.8 94.1 93.4 Scrub Yield, Wt. % (Note 79.1 78.5 78.3 76.9 80.9 78.6 final Non-magnetic Yield, 75.2 76.9 76.5 74.6 78.8 76.5 Wt. % (Note 2) Final Product Chemical Analvsis. % Fe203 0.02 0.03 0.03 0.02 0.04 0.03 A\00^ 0.16 0.22 0.23 0.14 0.22 0.21 ШО 0.01 0.01 0.01 0.01 0.01 0.01 Ti02 0.02 0.03 0.02 0.02 0.02 0.02 K20 0.01 0.01 0.01 0.01 0.01 0.01 Na20 0.05 0.05 0.05 0.05 0.05 0.05 MgO 0.05 0.05 0.05 0.05 0.05 0.05 CaO 0.01 0.01 0.01 0.01 0.01 0.01 P205 0.05 0.05 0.05 0.05 0.05 0.05 Si02 98.0 96.5 97.0 97.2 98.4 98.2 Lof 0.08 0.07 0.09 0.1 0.08 0.1 Note 1 - The yield of sand after scrubbing and slime removal. Note 2 - The yield after magnetic separation of the sized product. Table 5. Heavy liquid separation test results - Raw samples from individual drill holes. Float Product Sink Product Total Drill Hole Wt- grams Wt. % Wt- grams Wt. % Wt- grams Wt. % R18 158.6 99.5 0.8 0.5 159.4 100.0 R42 152.7 99.5 0.8 0.5 153.5 100.0 R9 152.0 99.5 0.7 0.5 152.7 100.0 R63 162.2 99.8 0.4 0.2 162.6 100.0 R83 153.8 99.6 0.5 0.4 154.3 100.0 R41 148.8 99.4 0.9 0.6 149.7 100.0 Reference cited - Further processing information and additional information see: Robert Mensah-Biney, Leigh Ann Carpenter, J. William Miller, Jr., and Jeffrey C. Reid, 2005, Suitability of Pinehurst Formation as a Glass Sand, Richmond County, North Carolina, North Carolina Geological Survey, Information Circular 33, 29 p. Note: Table numbers correspond to those in IC33. For additional information: Jeffrey C. Reid, North Carolina Geological Survey 1612 Mail Service Center Raleigh, North Carolina 27699-1612 919.733.2423 - http://www.geology.enr.state.nc.us Email: jeff.reid@ncmail.net .dgSIOs 'X >7 ivc -;v'i &У <Jj