Industrial Silica Sand FAQs
The information provided on this webpage is current as of October 31, 2012. A fact sheet of this information is available for download here.
What is industrial silica sand (Frac Sand)? Answer
Where is industrial silica sand found? Answer
What is the current status of industrial silica sand mining in Minnesota? Answer
How is it mined? Answer
What types of industries use silica sand? Answer
What is "fracking"? Answer
Is fracking for oil and gas occurring in Minnesota? Answer
Why here? What makes our sand so unique? Answer
Who regulates industrial silica sand mining? Answer
Who are the other regulating authorities? Answer
Industrial silica sand refers to sand having the composition and grain-size distribution required for industrial applications. Specifically, industrial silica sand consists of well-rounded, sand composed of almost pure quartz grains. Quartz, or silicon dioxide (SiO2) is the common mineral found on the Earth’s surface and is found in rocks like granite, gneiss, and sandstone. The value of industrial silica sand is significantly higher than sand and gravel used in the construction industry.
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Industrial silica sand is mined from sandstones occurring in portions of Minnesota, Wisconsin, Iowa, and Illinois. In Minnesota, glacial drift and other bedrock layers commonly exist on top of the sandstone. Three sandstone formations in Minnesota have potential for producing high quality industrial silica sand. The Jordan and Wonewoc sandstones are the most sought after sources followed by the St. Peter sandstone. Natural aggregates mined from sand and gravel deposits do not meet the specification for frac sand.*
*Dustman, J.E., Gulbranson, B., Bell, P., Gregg, W., 2011: Characteristics of high quality frac sand, and where to find it in the upper Midwest., Geological Society of America Abstracts with Programs, Vol. 43, No 5.
Industrial silica sand is found in the southeastern portion of the state. Eight mines are currently known to extract industrial silica sand. Mines may or may not process the sand on-site. Off-site processing plants that receive silica sand from various mining operations in Minnesota and Wisconsin are also found in Minnesota. To date, four counties, Goodhue, Wabasha, Houston, and Fillmore, have moratoria on new permits for industrial silica sand mining.
In Minnesota, all industrial silica sand mines operate as surface quarries. However, both surface quarries and underground mines exist in other states.
Industrial silica sand has been mined in the Upper Midwest for over a century. Uses for this resource include a variety of products and applications like glass-making, abrasives, golf course sand traps, and frac sand. Over the past decade, a sharp increase in demand for industrial silica sand corresponded with a rapid expansion of shale oil and gas development. An extraction method called hydraulic fracturing is used to produce oil and gas from oil/gas producing bedrock which can require approximately 10,000 tons of industrial silica sand per well. Due to increased demand, there is interest to develop new industrial silica sand mines and expand existing operations in certain counties in southeastern Minnesota.
“Fracking” is slang for hydraulic fracturing. Developed in 1947, hydraulic fracturing is a method used to increase the production of a well. The hydraulic fracturing process for oil and gas takes a mixture of proppant (usually frac sand), water, and chemicals and injects this mixture into a well under very high pressures. Small cracks form in the bedrock, frac sand “props” open the fissures, and conduits form that increase the flow of fluids and gas within a well. The average depth of an hydraulically fractured oil/gas well is between 6000-9000 feet below the surface.
No. Sand used for hydraulic fracturing is mined and/or processed in Minnesota. The sand is then transported out of the state by rail or barge to oil and natural gas producing regions (e.g. Western North Dakota, Pennsylvania, and Texas). However, a method of hydraulic fracturing is used in Minnesota to increase production of water wells screened in certain types of bedrock.
Even though sand is found all over the world, the sandstones of the Upper Midwest have several unique physical properties (listed below). It is one of a few known places on Earth where this resource occurs, making it a globally desired commodity.
- Composition: Sand usually contains many different rock types; however, silica sand consists of nearly 95% quartz.
- Strength: Quartz is a very hard mineral and able to withstand high pressures produced during the hydraulic fracturing process without breaking.
- Shape: The sand grains are shaped like little ball bearings allowing for oil and gas to flow between individual grains without clogging the fractured rock. It is very important that the round, unbroken grain shape is preserved throughout mining, processing, and transporting the sand to the market.
- Size: The sand grains are fairly uniform in size. When washed and screened, the sands meet a precise grain-size distribution required for frac sand (specified by the American Petroleum Institute, Recommended Practice 56):
Table: American Petroleum Institute, Recommended Practice 56
|Range of Grain Size Diameters||2.38 to 1.68 millimeter||2.00 to 0.84 millimeter||0.84 to 0.42 millimeter||210 to 105 microns|
|Aggregate Name||Fine Gravel to Coarse Sand||Very Coarse Sand to Coarse Sand||Coarse Sand to Medium Sand||Fine Sand to Very Fine Sand|
Note: Ninety percent (by weight) of the total product must fall within the specified range of grain sizes. Washing significantly reduces silt and clay sized particles (less than 62.5 microns in diameter) so to not exceed a turbidity threshold of 250 FTU (Formazin Turbidity Units).
Counties, townships, or municipalities are the responsible governmental unit (RGU) for administering permits to mine for industrial silica sand. Conditional land use permits, sometimes called special use permits, may be required from local planning and zoning offices.
Depending on size and scope, the proposed mining operation may be subject to the following state and federal permits and regulations:
- Department of Natural Resources (DNR): Water Appropriation Permit; Public Waters Work Permit; Burning Permit; and Endangered or Threatened Species Taking Permit.
- US Army Corps of Engineers: Section 404 Permit (discharge of dredged or fill material or excavation within waters and wetlands may require approval of the US Army Corps of Engineers).
- Environmental Quality Board (EQB): Requires environmental reviews in the form of an Environmental Assessment Worksheet (EAW) for operations excavating 40 or more acres of land at a mean depth of 10 feet and Environmental Impact Statement (EIS) for operations exceeding 160 acres.
- Board of Water and Soil Resources (BWSR): Wetland Conservation Act.
- Pollution Control Agency (MPCA): Section 401 Certification; Water Quality, and Air Quality Regulations.
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