Buffer properties of caved ore

Conclusions

Laboratory research and field observation of the buffer properties of caved rock made it possible to effect the following.

• 1. Obtain a qualitative relationship between the thickness of the buffer layer of ore and its degree of compaction for ore in the 0–2.5, 2.5–5.0, and 5.0–7.0 mm size ranges for parallel and fan hole arrangements.

• 2. Establish that compaction increases with the thickness of the buffer layer, regardless of the hole arrangement or the coarseness of the material.

• 3. Establish that in the case of the 0–2.5 mm fraction martite and hydrohematite-martite ores, the effect of the blast in parallel holes extends (for the investigated charge values at any rate) to a depth of 27 cm, while in the case of the 2.5–5.0 and 5.0–7.0 mm fractions, these values are 25 and 23 cm, respectively.

• 4. Where the holes are in a fan array in the center of the panel (block) the blasting effect extends to depths of 33.30 and 25.5 cm, respectively, for the 0–2.5, 2.5–5.0, and 5.0–7.0 mm fractions.

• 5. The qualitative laws thus obtained were confirmed in field observations carried out at the Gigant-Glubokaya mine. These laws have been recommended for determining the volume of compensation space available and the thickness of the buffer layer when working deposits in single-stage systems.