## 3 Suichang Gold Mine Shrinkage Method to Filling Method Case
### Comparison of the Effectiveness of Mining Methods  
A comparison of mining technical and economic indicators between the Suichang Gold Mine shrinkage method and the mechanized horizontal layered filling method is shown in Figure 9.  
At the same time, summarizing and analyzing the on-site construction practice and applicability of the two mining methods in the test section, we can conclude that the upward horizontal layered filling method has the following advantages:  
1. High productivity  
In the implementation of the Suichang Gold Mine, the upward horizontal layered filling method was used to drill horizontal blast holes with a drill jumbo. The spacing between the contour hole and the mining contour line is set at 0.3 m, the hole spacing is 1.1 m, and the row spacing is also 1.1 m. Each hole has a diameter of 45 mm and a depth of 3.5 m. The explosives for blasting are emulsified explosives, which are detonated by detonating cords and digital electronic detonators, and the method of differential blasting is used between the blast holes of each row. The mined ore is transported by LHD to the ore chute. In order to ensure that the mechanized equipment can operate effectively on the backfill, the backfill must have the necessary strength. However, an increase in strength is usually accompanied by an increase in the amount of cement used, which leads to an increase in costs. Therefore, in the actual filling operation, the following strategy is adopted for the 3.3 m of filling layer: the bottom 3 m adopts the non-cemented filling method, using tailings to fill, without adding cement, and in the top 0.3 m of layering, the cemented filling technology with a lime-to-sand ratio of 1:10 is adopted to ensure that the strength of the backfill body reaches at least 1 Mpa within 7 days, which meets the use standard of mechanized equipment. Figure 9: Comparison of techno-economic indicators. Compared with the shrinkage method, which adopts pneumatic rock drills to drill rock and an electric rake to get out the ore, the mechanized upward horizontal layered filling mining method adopts a drill jumbo and an LHD (see Figure 10), and the mining process mechanization degree is high. Therefore, the labor intensity of workers is low and the productivity of the mining field is high (see Figure 9). 2. Low loss dilution rate  
As shown in Figure 11, due to the discontinuity of the ore body and the existence of small ore body branches, the shrinkage method will lead to ore dilution and loss. The upward horizontal layered filling method can solve the problem of loss and dilution by separating the ore chute and waste rock chute and mining the ore and not mining the waste rock when it is encountered. As shown in Figure 12, because the electric rake can only linearly rake the ore, it is very easy to lead to the mining area being prone to secondary losses. And the use of an LHD out of the way leads to high efficiency and a good effect, which greatly reduces the loss of high-grade ore in the mining area. Figure 11: Schematic diagram of loss dilution in the case of interrupted or branching ore bodies. Figure 10: Rock drilling process with rock drilling cart and ore discharge process with LHD. High operational safety  
The stability of the ore rock in the test section is extremely poor, and the shrinkage method is very prone to produce the disaster of falling and unstable collapse, which jeopardizes the safety of the operators. The upward horizontal layered filling method adopts the technology of horizontal drilling with a drill jumbo and downward ore-dropping (as shown in Figure 13), and the mechanized supporting equipment of an LHD, which has a higher mining efficiency, a very short exposure time of the mining area, and makes it easy to deal with the upper loose rock, and the maximum height of the empty roof is small, which makes the safety of the mining operation greatly improved.