Toward Pillar Design to Prevent Collapse of Roomand ...
TOWARD PILLAR DESIGN TO PREVENT COLLAPSE OF ROOMANDPILLAR MINES R. Karl Zipf, Jr. ... longterm performance of roomandpillar mines are described. INTRODUCTION Roomandpillar mining accounts for a significant portion of the total mineral production in the United States As shown in table 1, well in excess of 6 billion worth of ...