At present, most of the blasting equipment used in the production of open pit mines are detonating cords and ordinary detonating tube millisecond detonators. During the use process, the blasting vibration and air shock wave caused by the detonation index explosion mode are large, and the surface after blasting is large in size, and the root bottom is easy to occur, the overall effect is relatively poor, and the cost of the blasting equipment is high. The common detonating millisecond detonator is used as the detonating means. Because the interval between the detonator sections of the domestic detonating tube is long and the detonation accuracy is poor, the parameters of the blasting hole network are greatly limited, and the blasting effect is difficult to control, which is difficult to achieve. Millior blasting between holes in the hole [1] . Therefore, while optimizing the parameters of the blasting hole network, it is necessary to select a millisecond delay detonator with high delay time and reliable detonation, and use the combination of surface delay and intra-hole delay to realize the differential detonation between the holes in the hole.

First, high-precision detonator

(1) Detonator performance

At present, the high-precision detonators produced in China are mainly Exel surface detonators and intra-bore detonators produced by Orica.

1. Exel surface deferred detonator. The Exel surface deferred detonator consists of a 4 # weak detonator, a plastic connecting block and a J-hook. The detonator has an extended delay time and the network connection is very simple and reliable. The Exel surface detonator has an outer diameter of 3 mm and a tensile strength of 45 kg. Exel surface deferred standard deferred time and error are shown in Table 1.

Table 1 High-precision surface deferred detonator standard extension time

2. Delay the detonator in the hole. The inner diameter of the detonator tube is 3mm, the tensile strength is 45kg, and the standard length is 3,5,6,9,12,15,18,24m8, all of which are 8# reinforced detonators, which can detonate the emulsion explosive reliably. Explosives with detonator sensitivity, such as rock explosives and water-gel explosives. See Table 2 for the millisecond delay time and error of the high-precision hole detonator.

Table 2 High-precision hole detonator millisecond delay time

(2) Comparison of delay time and error

1. Delay time. The average millisecond delay detonator detonator used in a mine has an average error of about 29.5%. In this way, the sequence of the bursting holes in the explosion zone is likely to have a jump blast, which will have a great impact on the quality of the blasting. The blasting theory shows that the inter-hole delay and the inter-row detonation time of the surface detonator design are selected according to the hole spacing, row spacing of 3~8ms/m and 8~15ms/m [2] . The maximum error of the upper and lower limits of the surface detonator is 4ms. The maximum delay error of the upper and lower limits of the detonating detonator in the 15th and 16th sections of the hole is 10ms. The total delay time of the surface and the hole is only 14ms, and the shortest delay time between the holes is also It can guarantee 17ms, so the high-precision detonator can completely avoid the phenomenon of hopping.

2. Detonation reliability. If all of the inter-bore millisecond blasting detonator ordinary milliseconds, the metal must be primary explosive detonator bore surface delayed detonation, explosive blast hole such networks after the first explosion or blast hole Zhaduan unraveling prone detonating Tube, poor reliability, insufficient delay accuracy, and blasting construction is more complicated.

The high-precision surface deferred detonator has a special connecting block, which can directly embed the detonating tube to be blasted on the connecting block without the need to wrap it with black rubber. The detonating tube of the detonator has high strength and can withstand a pulling force of 45kg without Deformation.

It can be seen that the high-precision detonator has the advantages of high delay time precision and reliable detonation. For this reason, the high-precision detonator is used to realize the millisecond blasting between the holes in the hole.

Second, the blasting test

2003 May 21, 2004 - November 26, LANJIAN iron ore were used in 261 high-precision detonators to blast blasting area, the main initiation methods are Deep - hole Millisecond, split-level differential bore hole Millior blasting between inner holes, involving all types of blasting in the range of blasting, such as clearing, extrusion, trenching, silting and pre-cracking [3 ~ 5] .

(1) Selection of detonators

1. Selection of delayed detonators for surface blasting between holes. According to the previous comparison and the surface detonation of the detonator, the suitable interval between the holes in the Lanjian iron mine is: the drilling and blasting area of ​​the downhole hole (Φ200mm aperture) is 17~25ms, and the high precision detonator can be selected for 17ms and 25ms; The drilling and blasting area (Φ250mm aperture) is 25~42ms, and the high precision detonator can be selected for 25ms and 42ms. Delay between rows: 65ms for the Drilling and Drilling Zone, 100ms for the Drilling and Explosion Zone. The design uses Orica high-precision detonator: 2 holes in the hole are detonated and the detonator is delayed.

2. Selection of the detonating detonator in the hole. According to the current blasting scale and the number of holes in the Lanjian Iron Mine, the 15 sections (375ms) or 16 sections (400ms) of the high-precision detonator can ensure the safe explosion of the blasting network.

3. Blasting network connection. The high-precision detonator network connection is simple, and in the case of designing the surface extension time unchanged, there are a variety of connection methods to achieve balanced inventory of various segments. The same explosion zone surface connection is not the same, and the actual delay of each blasthole detonation time is exactly the same as shown in Figure 1.

Figure 1 High-precision detonator hole-by-hole detonation network

(2) Blasting vibration

Lanjian Iron Mine has promoted the application of high-precision detonators for production blasting. In areas where key earthquakes are required, micro-difference blasting between holes, micro-difference blasting between holes, differential blasting between holes, and fineness between holes have been carried out. Production test of pre-cracking blasting.

In order to quantitatively understand the blasting vibration of the high-precision detonator detonation blasting area, from April 14, 2004, several TOPBOX blasting vibration testers developed by Chengdu Tuopu Electronics Research Institute were used in the Lanshan and Yingpanshan mining sites. The blasting vibration of the explosion area, and then input the test data into the computer for processing analysis. In the area where the earthquake is very demanding near the Lan 4 # , Lan 5 # waste stone chute and the tail shovel, the blasting between the holes in the hole, the differential blasting between the holes, and the deep hole blasting between the holes The vibration reduction rate of the differential blasting between the holes in the hole is shown in Table 3.

Table 3 Comparison of vibrations of different millisecond blastings under the same blasting distance

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