A Review of Current Blast Practices in Minnesota Iron Mines

Mesabi Range blasting has evolved in over a century of mining. The obstacles including: hard and heavily jointed rock, bitter winters and frequent wet holes; combine to create a unique challenge for blasters. This paper documents current pattern designs, powder selection and loading practices for these seven mines that consumes as much as 130 million lbs of explosives each year. Blasting is characterized by wide burdens and spacings, large diameter holes (up to 16-inch) and bulk loading of augered and pumped emulsion/prill products.