| 摘要 |
FIELD: mining industry; openpit mining of ferruginous quartzites. ^ SUBSTANCE: method is proposed in two versions. According to first version, method includes drilling at bench parallel rows of vertical boreholes at angle beta relative to strike line of layers determined by the following relationship: beta=arc cos (cos 45°-singamma.cosalpha)/(sinalpha.cosgamma), where alpha is angle of dip; gamma is angle between plane of blast wave front and vertical. Then, boreholes are charged with explosive followed by tamping at simultaneous blasting in each row for forming inclined compression blast wave. According to second version, proposed method includes drilling parallel rows of vertical boreholes at angle beta relative to strike line determined by the following relationship: beta= arc cos (cos 45°-singamma.cosalpha/(sinalpha.cosgamma)±psi, where alpha is angle of dip; gamma is angle between plane of compression blast wave front and vertical; psi is angle of turn of compression blast wave front around vertical axis relative to strike line which is determined as follows: psi=arc sin(upsilonel.t/L) where upsilonel is velocity of propagation of elastic wave in mass; t is interval of time between blasts of charges in first and last boreholes of row; L is length of this row of boreholes; sign of angle psi is selected that angle between line of each row of boreholes and line of crest of bench of shoulder is close to or is equal to 90°, after which boreholes are charged with explosive followed by tamping and successive blasting in each row forming inclined compression blast wave. ^ EFFECT: enhanced efficiency of softening the ore. ^ 3 cl, 6 dwg, 3 ex |
