Guide of Filling Mining Method

Filling mining method refers to the mining method in which the goaf is filled with filler material while ore drawing, transporting and other operations. Because the filling mining method can maximize the recovery of mineral resources and protect the underground and surface environment, it has been widely used in non-ferrous metal mines and precious metal mines.

This article will introduce the filling mining method from the following six aspects.

• Filling mining method purpose

•  Filling material source

• Filling mining method classification

• Filling mining method applicable conditions

• Filling mining method features

• Safety management measures

Let’s drive in now!

(1) Ground Pressure Management

Filling mining method uses the formed filling material for ground pressure management to prevent wall rock collapse and ground subsidence.

And it also create convenient and safe conditions for the mining face, protects the surface buildings, and restore safe production.

(2) Prevent Spontaneous Fire

Some mines use this method to prevent spontaneous combustion of deposits (internal fires or other disasters)

(3) Created Conditions for Pillar Robbing

Whether the goaf can be filled in time after the mining is completed will directly lead to whether the pillar can be mined, also directly affect the balanced production of three grades of reserves. Backfill mining method provides favorable conditions for pillar stoping.

(4) Create Conditions for Deep and Underwater Mining

Filling mining can be used for deep mining, underwater mining and the prevention of impact ground pressure.

The main sources of filling materials are:

 ①   Waste rocks piled up on the ground

 ②   The waste rock at the edge of the excavation pit

 ③   Tailings of the mineral processing plant

 ④   Slag from the smelting plant

 ⑤   Gobi aggregate

 ⑥   Stones mining from the surface

According to the different filling material and transportation methods, as well as the ore body mining direction and filling method, the filling mining method can be divided into the upward layered (or approach) filling method, the downward layered (or approach) filling method and the Backfill mining method.

(1) Upward Layered Filling Method

The upward horizontal layered filling method is one of the most widely used filling mining methods in the world. Its characteristics are that the ore block can be divided into ore room and pillar, mining room first, then mining pillar. The ore house is stratified from bottom to top (horizontally or diagonally) for mining. After each stoping of one or more layers, fill in time to maintain the surrounding rock of the upper and lower walls and

create operating conditions for continuous upward mining. Pillars shall be mined by filling method or other suitable methods in a reasonable order of stoping.

(2) Downward Layered Filling Method

For metal deposits with extremely high ore value but not stable, when the upward horizontal layered filling method cannot guarantee the safety of the mining operation, the downward approach filling method can be considered. Its main feature is that in the stage, the layered approach (roadway) stoping and approach filling are carried out in sequence from top to bottom under the protection of the layered artificial roof. Due to the many production links, the artificial top requires high strength and good integrity, so the production cost is relatively high.

(3) Backfill Mining Method

Layered filling mining method has outstanding advantages such as high recovery rate and low dilution rate. However, due to its many times of filling and complex processes, it takes a certain amount of curing time after each filling to enter the next stoping operation cycle, which increases costs and affects production capacity. Under the condition of good rock stability, the backfilling method can be used. Its main characteristic is that in the stage, the ore body is divided into ore room and pillar alternately. First stoping the ore pillar using the open-stope method. After the stoping of the whole ore block is completed, the primary cementing pack is carried out to form an artificial ore pillar. After the cement has reached the curing time, under the protection of the artificial pillar, use the same method to mine room. After the stopping of ore house is completed, primary non-cementing pack shall be carried out. Since the filling work is completed at one time in the entire stage of the ore block, this method is also called the stage filling method.

(1) The mining of high grade rich ore, and requires high recovery rate and low dilution rate. Or the mining of rare and precious metals.

(2) The mining of deposits with more complicated preservative conditions and technical conditions. Such us: 

①   The hydrogeological conditions of the deposit and the shape of the ore body are more complicated.

②   The ore body is buried deep and has high ground pressure

③   Ore or surrounding rock has the risk of spontaneous combustion

④   The surface or surrounding rocks do not permit large subsidence or violent movement and require special protection

⑤   Open-pit and underground mining is carried out simultaneously

(3) The mining of deposits with stable ore and unstable surrounding rock

If a special support method or downward layered filling method can be used, it can also be used to mine unstable ore bodies.

(4) The mining of steeply inclined ore body

Because the steeply inclined ore body is convenient for conveying filling materials to stope, and can reduce the space that cannot be filled and the area where the filling material is connected to the top. However, if it can be filled by hydraulic or wind power, it can also be used in the mining of gently inclined thin veins.

(1) Merit

①   Small quantity of mining and cutting works and great flexibility.

②   Less ore loss and low dilution rate

③   It can effectively maintain the surrounding rock, reduce the movement of surrounding rock and prevent a lot of caving

④   For thin veins or multiple types of ores, sorting stoping can be carried out

⑤   It can prevent the spontaneous fire of deposit

(2) Demerit

 ①  Complex stoping process and filling process

 ②   Filling and mining are mutually affecting. If the mechanization of backstoping operation cannot be properly solved, the production efficiency and production capacity will be relatively low

 ③   The mining, processing, transportation and other consumption of filling material increase the cost of ore. The cost of mining, transportation and accumulation of filling materials accounts for 40-50% of mining costs.

 ④   High labor intensity

①  The stope must have two exits and be equipped with lighting equipment. Pedestrian shafts, ore chute, drainage well (for water sand filling) and ventilation shafts should be kept unblocked.

②   The maximum particle size of the water sand filling material is not more than 1/4 of the pipe diameter, and the maximum particle size of the cemented filler is not greater than 1/5 of the pipe diameter.

③   In the upward layered filling stope, the filling shaft and its connecting channel must be constructed first, and then the bottom structure and the stope drift must be constructed to form good ventilation conditions as soon as possible. When arranging the ore chute and by-pass footpath in veins, it is strictly forbidden to blast the whole layer at one time.

④   When drilling rock in the stope, the placement of the porthole should be even, forming an arch along the roof. The amount of gunpowder should be appropriate to control the ore fragment

⑤   Filling should be timely after each layer stoping to ensure the filling quality. The roof should be tightly connected after the last layer stoping.

⑥   People are prohibited from staying and passing under the filling shaft. When filling, there should be communication between each process.

⑦   Pedestrian shafts and ore chute should have reliable backing materials to prevent leakage of filling materials to prevent blockages and form a dangling. The filling material accumulated in the lower roadway and ditch of the stope should be cleaned up in time.

⑧   In the stope with downward cementation filling, the ore at the bottom corners of the two banks should be cleaned up.

⑨   When using the artificial up-pillar up-layer filling method for mining, the adjacent stopes should keep a certain distance

⑩   When combined steel cylinders are used as square-set raise (pass, water filtration, ore drawing), safety nets should be hung at the wellhead before the steel cylinders are assembled.

⑪   The stope must be equipped with grid screens to prevent people from falling and blocking. Pedestrian wells, ore chute, drainage well, and filling shaft should be staggered.

⑫   When dry filling, every operation point should have good ventilation and dust removal measures, and strengthen personal protection.

⑬   It is forbidden to drill and process pumice at the same time in the stope.

The above have learned about the filling mining method from six aspects: the purpose of the filling mining method, the source of the filling material, the classification of the filling mining method, the applicable conditions, the characteristics and the safety management measures. It is suggested that all mining owners make mining engineering planning in advance, which can not only maximize the completion of mining, but also reasonably protect the environment and maximize the benefits.

If you have different ideas, questions or want to purchase mining equipment, please submit a message or consult our online customer service, we will contact you as soon as possible.