Shibao iron mine located in the northern grasslands of Inner Mongolia DAMAOQI, part of Baotou Iron Shibao Group Co., Ltd., founded in 1988, mainly to the mining industry, Inner Mongolia Autonomous Region is the largest local manufacturers of iron powder. After years of development, it has formed a production scale of 4 million tons of annual mining and 1.3 million tons of iron fine powder.
As of the beginning of 2014, a total of two independent open pits were formed, namely the Western Stope and the Middle East Stope. The minimum mining elevation of the West Stope is 1572m, the highest mining elevation is 1690m, and there are 5 working platforms in the lower part. The production stripping ratio is 1.5t/t, compared with the design of 1620m in 2004. The lowest mining elevation in the Middle East is 1560m, the highest mining elevation is 1710m, and there are 5 operating platforms in the lower part. The production stripping ratio is 0.86t/t. Compared with the design of 1608m in 2004, it has all been helped.
The mine design has an open bottom elevation of 1500m, and there are 5 to 6 steps (step height 12m) from the closed pit. The mine has entered the late stage of mining.
The deep geological exploration of the mine shows that the ore body has a deep extension below 1500m, and the deep resources can also extend the service life of the mine by 7a, making the mine stable production of 10a. The stope continues to extend downwards, and the open-field boundary of the original stope needs to be modified. The recommended production stripping ratio is increased from 1.5t/t to 3.5t/t before the transformation, and the amount of stripping is greatly increased. Great changes, the number of equipment in the stope, equipment efficiency, production organization need to be re-approved, especially the impact on the economic benefits of the mine, the stripping ratio should be optimized.
1 Determine a reasonable production stripping ratio
(1) According to the 2014 China Metallurgical Jingcheng (Qinhuangdao) Engineering Technology Co., Ltd., the technical renovation project of the mining site of Shibao Iron Mine is expanded. The boundary is in the south of the west mining field. The maximum expansion width is 254m, and the open bottom extends downward. 72m, of which the west stope extends 84m downwards, and the middle and east stopes extend down 36m. After the expansion of the stope, the newly added ore is 21,351,200 tons, the new rock is 92,889,800 tons, the incremental stripping ratio is 4.35 t/t, and the average stripping ratio of the whole mine is 2.43 t/t. The upper expansion section is steeply mined and the lower mining section is operated as normal. The production stripping ratio is 4.0t/t, and the pv map equalization method is adopted. The initial production rate is 4a at 4.0t/t stripping ratio, the second equilibrium period is 6a, and the production stripping ratio is 2.125t/t. 3a) The production stripping ratio is less than 1.17t/t. Through comprehensive design, it is initially determined that the production stripping ratio is 3.5t/t at the beginning and the production period is 5a.
(2) In view of the market situation of iron ore in 2015, the mines have a higher pressure on the operation cost of 3.5t/t. Therefore, it is recommended to further reduce the production stripping ratio under the premise of ensuring that the production in the later stage of the mine will not cause the loss of mining and stripping. According to the analysis of reducing the stripping ratio of pre-production, the production is 1~2a according to the lower production stripping ratio, and then the production is stripped and produced according to the re-equalization. The production in the later stage of the mine is required to be stable and reliable.
(3) According to the cost and pressure zone of the mine, the initial stripping ratio of the mine is 2.0~3.0t/t. It is set to produce 2a according to the production stripping ratio of 2.0, 2.3, 2.5, 2.8 and 3.0t/t, and then re-equalize the production stripping ratio according to the space of the stope. The equilibrium method adopts the pv curve diagram method to select a more reasonable scheme, and then further verify the spatial relationship of the stope by formulating the stripping schedule to determine a better scheme implementation.
2 Typical production stripping ratio equalization scheme analysis
2.1 Scheme 1
After the mine produced 2a at 2.0t/t stripping ratio, the ore balance of the mine was 35.375 million tons and the rock was 85.4443 million tons.
According to the data of each layered ore, the pB map method was used to balance the production stripping ratio of the scheme, as shown in Figure 1.

The equilibrium period is divided into three stages, the first period is 3a, the production stripping ratio is 4.5t/t; the second period is 3a, the production stripping ratio is 3.5t/t; the third period is 2a, production stripping The ratio is 1.0 t/t; it is reduced to below 0.5. Due to the low stripping and production of the first 2a, the stripping amount of the stripping is more. When the balance is equal, the production stripping ratio of the first 3a will reach 4.5t/t, and the production stripping ratio of the second equilibrium period is also high. 3.5t/t. Although the initial cost pressure can be alleviated, the mine production organization is more complicated.
2.2 Scheme 2
After the production of stripping ratio of 2.5t/t for 1a, the amount of ore in the mine balance is 38,857,100 tons, and the rock is 94,944,300 tons. According to the above-mentioned stratified ore volume data, the scheme is implemented by using the pv map method.
The production stripping ratio is balanced, as shown in Figure 2.

The equilibrium period is divided into three stages, the first period is 5a, the production stripping ratio is 3.8t/t; the second period is 3a, the production stripping ratio is 2.8t/t; the third period is 2a, the production stripping ratio is It is 0.8t/t; it will fall below 0.5. The first equilibrium period of the program is 5a, and the production organization and personnel are more reasonable. The stripping ratio is 3.8t/t, slightly higher than 3.5t/t. Closer to the design.
2.3 Scheme 3
After producing 2b of stripping ratio at 2.5t/t, the amount of ore in the mine balance is 35.375 million tons, and the rock is 85.434 million tons. According to the above-mentioned stratified ore volume data, the scheme is implemented by the pv map method.
The production stripping ratio is balanced, as shown in Figure 3.

The equilibrium period is divided into three stages, the first period is 3a, the production stripping ratio is 4.5t/t; the second period is 3a, the production stripping ratio is 3.3t/t; the third period is 3a, the production stripping ratio is It is 1.0t/t; it will fall below 0.5. The equilibrium period result of this scheme is similar to that of scheme 1.
2.4 Stripping ratio selection
The above analysis shows that if the Shibao iron ore mine is produced according to the lower production stripping ratio in the early stage, it will have a greater impact on the next expansion plan of the mine. The production stripping ratio will rise sharply, reaching a maximum of 4.5t/t. The sharp increase will bring inconvenience to the mine equipment investment, technical staffing and production organization management. It can be seen from the pv curve that the production stripping ratio is higher in the first equilibrium period, and the equilibrium time is shorter (about 3a), which has an impact on mine management. The characteristics of the above several schemes are that as the production stripping ratio increases, the time of the first equilibrium period of the mine gradually increases, and the production stripping ratio is gradually decreasing. The mine expansion operation is carried out under the conditions of small space and high mining intensity. Reducing the mining strength of the expansion operation is the key to ensuring the completion of the technical transformation work. Accordingly, it is recommended to use the 2.5t/t production stripping ratio to produce 1a and then re-equilibrate. The equilibrium period of the program is divided into three stages, the first period is 5a, the production stripping ratio is 3.8t/t; the second period is 3a, the production stripping ratio is 2.8t/t; the third period is 2a, production stripping The ratio is 0.8t/t; it will drop below 0.5.
Simulation of spatial relationship in production period of 3 stope
In order to verify the rationality of the equilibrium results, a stripping schedule was prepared for the recommended operating conditions, and the spatial relationship of the production period (10a) of the stope was simulated. The stripping schedule is as follows: the ore volume is unchanged according to the design, 3.2 million t / a, mainly to adjust the amount of rock.

In 2015, the total stripping ratio of the three stopes was 2.5t/t, and the total stripping capacity was 11.2 million t/a. The ore in the Middle East is 2.2 million tons, the rock is 4.4 million tons, the stripping ratio is 2.0t/t; the west mining field is 1 million tons, the rock is 3.6 million tons, and the stripping ratio is 3.6t/t. Due to the small amount of rock fragmentation, the west mining field expansion level is 1680~1640m. The Middle East stope plan is mainly on the northern gang expansion and fixed roads. The expansion level is 1690~1572m, which runs through the ore transportation road and the southern gang expands the level. 1670 ~ 1620m.
3.1 Phase 1 5a (2016-2020)
In the first phase, the total amount of stripping in the three stopes was 15.36 million t/a, which was scheduled at 3.8 t/t. The situation is as follows.
In 2016, the ore in the Middle East was 1.9 million tons, the rock was 3.8 million tons, the east stope was opened at a new level of 1560-1548m; the west mining site was 1.3 million tons of ore, the rock was 8.36 million tons, and the new level of 1560-1548m was opened. 1650m level.

In 2017, the ore in the Middle East was 1.8 million tons, the rock was 3.6 million tons, and the middle stop was opened to a new level of 1548 to 1536m. The west mining site was 1.4 million tons of ore, 8.56 million tons of rock, and the east side expanded to 1608m level. The connection between the field and the Middle East stop.

In 2018, the ore in the Middle East was 1.5 million tons, and the rock was 3 million tons; the west mining site was 1.7 million tons of ore, and the rock was 9.16 million tons, opening up a new level of 1548 to 1536 meters.
In 2019, the ore in the Middle East was 1.5 million tons, the rock was 3 million tons, the middle stop was opened to a new level of 1536 to 1524 m, the east stop was opened to a new level of 1548 to 1536 m, the west stope was 1.7 million tons, and the rock was 9.16 million tons. ~1524m new level.
In 2020, the ore in the Middle East will be 1.5 million tons, and the rock will be 3 million tons. The west mining site will have 1.7 million tons of ore and 1.86 million tons of rock, opening up a new level of 1524 to 1512 m.
3.2 Phase 2 3a (2021-2023)
In the second phase, the total amount of stripping in the three stopes was 12.16 million t/a, and the results of the scheduling were as follows.
In 2021, the ore in the Middle East will be 1.5 million tons, the rock will be 3 million tons, the middle stop will be opened to the new level of 1524~1512m, the east stope will open up to the new level of 1536~1524m; the west stope will be 1.7 million tons, the rock will be 5.96 million tons, and the development will be 1512. ~ 1500m new level.
In 2022, the mining in the Middle East was not discharged due to the sharp drop in rock volume; the west mining site had 1.4 million tons of ore and 5.36 million tons of rock, opening up a new level of 1500 to 1488 m.
In 2023, the west mining site ore was 1.7 million tons, and the rock was 5.96 million tons, opening up a new level of 1488 to 1476m.
From the perspective of production scheduling: the first phase 5a (2017-2019) stripping ratio is 3.8t/t, the simulated production space of the stope is relatively compact, and the production organization management requirements are high; the second phase of the Middle East stope, simulation production The space is more relaxed, and the stripping ratio has a larger room for adjustment.
4 Conclusion
Through simulation production verification, the selected program results are feasible, but in actual production, due to many uncertain factors, there will be discrepancies with the simulated production. It should be adjusted according to the actual production situation. The final plan should be based on the annual plan. Organize management for guidance. In 2015, the mine formulated the production plan according to the research plan. After the production implementation of 1a, the mine expansion and reconstruction work has been fully carried out, and the new transportation channel outside the stopway has been basically completed. The planned production stripping ratio in 2016 is 3.0t/t. After the iron ore concentrate price stabilizes and rebounds, the production stripping ratio will be raised to the predetermined number in time to ensure the stable development of mine production.