as shown in table 1 note the significantly higher percentage amounts of longer fiber pulp that remains on the coarse screens e g gt 14 and 14 30 screens for pulp produced with the proppant grit pulpstone relative to that made by the conventional stone note that test results represented in fig3 and 4 reflect results from a lab grinder while test results represented in table 1 reflect an actual mill trial on a full size grinder the foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description it is not intended to be exhaustive or to limit the invention to the precise form disclosed many modifications and variations are possible in light of this disclosure for example pores can be induced without the use pore inducing materials by using agglomerates of vitrified or organic bond that include proppant grits and optional abrasive grits a secondary bond material is then used to bond the agglomerates together in an open porous structure additional details of example agglomerates and porous structures are provided in u s pat no 6 679 758 which is herein incorporated by reference in its entirety in one such embodiment proppant grits could be used in place of 10.