Beneficiation of Hydrofracturing Sand from the Minnesota Fracsand Company

Abstract

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.