Drilling of open-pit deep-hole blasting.
1. Construction of drilling rig platform.
Whether it is a one-time blast or a stepped blast, a drilling platform should be built for the drilling rig. The width of the platform shall not be less than 6 8m, and it is guaranteed that there are no less than 2 rows of holes at a time. The platform should be flat to facilitate the drilling rig's walking and operation. During construction, shallow hole blasting and bulldozer leveling methods can be adopted. When some rocks are not particularly hard, they can also be excavated and leveled with an excavator. For the layered stepped blasting platform should be according to the design of the blasting step, from top to bottom layer by layer construction, after the upper layer blasting for the construction of the lower platform to create conditions, the lower platform of the upper layer is the upper platform of the next layer. Although the blasting technology also needs to be improved, the platform must have an appropriate width to meet the needs of blasting and shovel shipment.
2. Drilling method.
2.1 Drilling Essentials.
The drilling driver should master the operation essentials of the drilling rig, be familiar with and understand the performance, construction principle and precautions of the equipment, be proficient in operation technology, and master the drilling and drilling rules of rocks with different properties. The basic essentials of drilling: "soft rock is slow, hard rock is fast;The small wind pressure is hit, and the hard rock is not pressurized;Watch, listen, and check". These basic essentials are a summary of the experience of the older generation of rig drivers, simple and concise.
2.2 Basic methods of drilling.
1) Opening. For the complete rock face, the scum should be blown clean first, the small wind should not be pressurized, the rock face should be slowly impacted, and after the hole was punched, the hole should be drilled under the rotating drilling tool. When the drill bit enters the hole, gradually increase the air volume to the state of rapid rock drilling with full wind and full pressure. For the weathered gravel layer on the surface or the cracks on the surface of the lower layer increase or even loosen due to the blasting of the upper layer, if the opening is improper, a bell mouth will be formed, and the gravel may fall into the hole at any time, resulting in jamming or plugging the hole. Therefore, there should be a certain amount of technique when opening. First of all, the drill bit should be off the ground to the high wind and high pressure, blow off the scum, according to the "small wind pressure to hit, no hard rock without pressure" of the essentials of opening, the opening is not good, will bring some inconvenience to the borehole;Secondly, in order to prevent the collapse of the orifice, mud wall protection technology should be adopted, that is, the yellow mud is injected into the hole, the rotary drilling tool is drilled, the yellow mud is squeezed into the stone crack by the method of one pressure and one rotation, and then the drill pipe is lifted up and down, so that the yellow mud is firm and the orifice is round, and the upper part of the orifice can be artificially protected by the yellow mud to protect the wall, so that the loose gravel is firm and will not be affected by vibration and fall into the hole. This kind of operation has not been seen in many years, and even if the rock is relatively broken, it is rarely done by operators nowadays.
2) Drilling techniques. After the orifice is opened, certain skills should also be mastered when entering normal drilling. For hard rock, a high-quality and high-hardness drill bit should be selected, and the full air should be sent to the full pressure, but the speed should not be too high to prevent damage to the drill bitFor soft rock, the whole wind should be sent to add half pressure, slow drilling, and slag discharge, 1. per footage0~1.5m lift the drill and blow the hole once to prevent the hole from being stuck due to excessive slag at the bottom of the holeFor the weathered fracture layer, the air volume should be small, the pressure should be light, and the air should be blown and the hole should be guarded frequently. In order to prevent the phenomenon of hole collapse, the hole is protected with yellow mud once every 1m or so. The blasting is a little more common to think that the old driver of the drilling rig must know these operation essentials, but some new drilling rig operators may not be able to understand this drilling rig skills. Often deviate from the hole, stuck drilling, and the mud at the bottom of the hole can not be lifted, resulting in unsatisfactory drilling quality.
3. Mud hole protection method.
For the unstable section of rock crushing at the orifice, mud should be used to protect the wall during the drilling process, one is to avoid the formation of a horn shape at the orifice, which is easy to affect the drilling cuttings to rush out;The second is to prevent the orifice from breaking the rock and falling into the hole during the drilling and charging process, resulting in hole blockage.
The operating procedure of the mud wall protection is: 2 3m of blast hole drilling;A certain amount of water-containing sticky yellow mud is stacked at the orifice;Use the drill pipe to move up and down to bring the yellow mud into the hole and invade the fractured rock;Check whether the wall protection meets the requirements, move the drill pipe up and down before the final hole, and try to blow the rock powder out of the hole to ensure the drilling depth and improve the utilization rate of the hole. This requires skill and not every rig operator can do it completely.
4. Acceptance and protection of blast holes.
The main contents of the blast hole acceptance are:
1) Check the hole depth and mesh parameters
2) Review the line of resistance of each gun hole in the front row;
3) Check the water content in the hole.
The inspection of the depth of the blast hole is to use a soft ruler (or measuring rope) to tie a hammer (ball) to measure the depth of the blast hole, and make a record when measuring. To prevent hole blockage, it should be done:
1) Immediately after each blast hole is drilled, the orifice is plugged with a wooden or plastic plug to prevent rainwater or other debris from entering the blast hole;
2) Clean the orifice rock to prevent it from falling into the hole;
3) Blasting is carried out as soon as possible after the completion of a blast zone drilling.
In the process of hole acceptance, it is found that the hole is plugged and the depth is not enough, and the drilling should be carried out in time. In the process of filling holes, attention should be paid to the safety of the surrounding blast holes to ensure that all the blast holes meet the design requirements before charging. [Blasting one-point processing finishing].