Open-pit mining of Yanjin Mine--Application of combined step steep mining

Heilongjiang Provincial Bureau of solidarity wulaga gold mine gold deposit is a large gold deposit, which applies a combination of stairs and steep slope mining technology, the expansion of mining in 1988 after the comprehensive production capacity of 1200t / d.

First, mining technical conditions

The No. I ore body in the Tuanjiegou Gold Mine has the largest scale, accounting for more than 96% of the industrial reserves. The strike length is 1550m, the elevation is 250-122m, the slope is 450m, and the maximum thickness of the ore body is 130m, with an average of 46m and an inclination of 20 ° ~ 30 °. The ore body is divided into two sections, east and west, with the 115-111 exploration line as the boundary.

The eastern ore body is especially developed between 107 and 112 lines, forming a thick ore body and exposing the surface. The elevation is 206 to 30 m, which is like a funnel, and the ore body is 200 m deep. The western ore body expands and develops between 115 and 131 lines. The ore body has an elevation of 160 to 50 m, which is a concealed ore body. The ore body has a funnel shape with a depth of 210 m and an average thickness of 50 to 70 m. The average thickness of the ore body is 46m, the length is 250m, the inclination angle is 20°~26°, and the average grade of ore is 3.55g/t. The surrounding rock of the ore body is relatively stable and the groundwater is rich.

Second, mining methods and mining technology

According to the conditions of the ore body and the expansion requirements, through technical and economic analysis and comparison (see Table 1), the shallow parts of the eastern and western mining areas are all open-pit mining, and the mining order is the Houxi District of Xiandong District.

Table 1 Comparison of mining schemes

Open-pit mining boundary parameters are listed in Table 2.

Table 2 Open-pit mining boundary and working parameters

Different mining and stripping processes have different effects on infrastructure and infrastructure cycles, and are compared by technology and economy (see Table 3).

Table 3 Infrastructure Construction Scale

It can be seen from the calculation that the amount of infrastructure construction of the four steps combined with the stripping process is 1.33 million m ³ less than that of the two steps, which is 1.45 million m ³ less than the single step stripping process.

The four steps are combined into one combined step, and there are two groups. The stripping operation uses a combination of steps along the strike strip. Two excavators are used for trailing work in each combination step. The minimum working distance of the excavator is 200m, and the operation sequence is from top to bottom. The blasting operation was carried out on a wide platform (35 to 45 m) of each group, and the blasting pile was scattered on the first narrow platform (15 m) adjacent to it, and the first excavator was formed after shovel loading on a narrow platform. The wide platform provides a blasting site for the second step, and the second shovel is shoveled on a wide platform formed by the second step. After the first excavator completes the first step, it is transferred to the third step. Correspondingly, the second excavator is dug to the fourth step and then transferred to the fourth step. The second set of combined step operations is identical to the first set of combined step operations. The steps that do not work in the first set of steps serve both as a security function and as a transport road. At this point, each group of combined steps form an independent system of wear, installation, transportation and security. Each advancement width is 20~30m on average, until the final slope, forming a working angle of 23°~25.2°.

Due to the thick cover of the open pit in the west, the amount of stripping is large. In order to reduce the amount of infrastructure construction and maintain the balance of production and stripping, in the fourth year after the production of the open pit in the east, the west open pit stripping work began. When the stope is in the 15th year, the west open pit will continue to be produced.

The perforation operation adopts KQX-150 type DTH drilling rig , medium-deep hole blasting, efficiency 25m/table, perforation 21,000m/set a, total 5 sets, including 1 mining and 4 stripping. Emulsified oil, floating plastic explosive, plastic non-electrical detonation series. Controlled blasting was adopted near the slope, and the perforating equipment was changed from a YQ-150 type down- drilling rig to an 80-100m down-the-hole drilling rig.

The annual mining volume is 360,000 t ³ , and the WK-2 electric excavator is used. The bucket capacity is 2m ³ and the station efficiency is 141,700 m ³ /a. The mining sequence is advanced along the upper disc of the ore body. When the ore body is in the triangle belt, the ore is divided into mining and mining, and the T-140 bulldozer is used with the ZL-50 front-end loading and unloading operation.

Mines peeling rock 1,800,000 m ^3, using WK-4A electric excavator bucket capacity 4m ^3, 473,400 units efficiency m ³ / a, and with a working ZL-50 type front loader.

The main parameters of the mining and stripping face are as follows:

Third, the combination of steep step mining technology evaluation

The combination of stepped and steep mining is used to effectively reduce the amount of expansion and balance the production stripping ratio. But at the same time, it also brings the following problems: (1) The main mining and stripping equipment should be adjusted up and down once a year, and the efficiency of the excavator will be reduced by 6% to 10%; (2) After the completion of a stripping strip, the original temporary road disappears. It is necessary to form a new mobile pit line, increase the amount of temporary road construction, reduce the speed of production of automobiles and increase the transportation cost of automobiles; (3) Coordination between the upper and lower working steps in the production process, Strict schedule requirements, complex production management, strict organization of production, and enhanced production and equipment management.