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Recovery scheme of iron ore in mixed ore waste rock in Shantoushan iron ore mine
Benxi iron ore Waitoushan belong Presinian metamorphosed sedimentary beds Anshan magnetite ore types are mainly actinolite natural quartzite, followed by rock from the sun as the magnet, the magnet quartz rock, dolomite magnet, magnet actinolite rock. The surrounding rocks are mainly slanted amphibolites , erect quartzites, and erectite schists. The ore body is produced in three layers and is roughly north-south. Due to the influence of the structure, the geological conditions of the mining area are complex, the veins are severely interspersed and cut, and the ore body shape changes greatly. The ore bodies in individual parts are quite scattered, and the ore and rock mixing is very serious.
At present, the mine has been converted to deep open pit mining stage, using large-area medium-deep hole differential blasting mode, the mining equipment is 4m 3 electric shovel, and the transportation adopts the combined operation mode of electric motor car and automobile. The ore loss is large during the production process, resulting in the loss and waste of ore resources. The recovery test using bulk dry magnetic iron Waitoushan from row to dump waste rock mixed in iron ore, ore grade can reach more than 28%, in line with grade ore beneficiation plant selected, can be achieved The dual purpose of improving the utilization rate of iron ore resources and reducing the cost of mineral processing.
   First, the cause of mixed ore waste rock
There are two main stopes in the Shantoushan Iron Mine, namely the main stope and the Malingling stop. The main stope is divided into three mining areas according to the direction of the vein, namely the upper mining area, the lower mining area and the bottom mining area. The upper mining area of ​​the main stope is a pure rock part, and no mixed ore waste rock is generated. The Maerling stope and the main mining area ditch mining area adopt the automobile-flip-motor vehicle transportation mode, and the mineral rock packing in the production process. Distributing is easier to achieve, and the amount of mixed ore waste is small. There are two kinds of rocks in the mining area of ​​the main stope: one is pure rock part, this part does not produce mixed ore waste rock; the other is mixed rock part, the mixed ore rate is 8%~10%, as The ore is selected, which will seriously affect the cost of ore dressing and iron ore concentrate production. Therefore, it can only be used as waste rock waste. The amount of mixed ore waste in this part is as high as 2 million tons. If it is recovered from large dry magnetic separator Ore has great value.
   2. Dry magnetic separation test of mixed ore waste rock
The test equipment adopts two kinds of large-scale dry magnetic separators, the cylinder diameter × cylinder length is about 630mm × 850mm, the width of the conveyor belt is 650mm, the speed of the conveyor belt is 2.0m / s, and the magnetic induction intensity of the barrel in the sorting area is 240mT and 180mT.
The mixed ore waste rock is taken 50t in the mining and mining part of the main stope, crushed to -60mm with a jaw crusher , sieved with a vibrating bar sieve with a sieve hole of 30mm, and the product under -30mm sieve is used as test sample A. The 30-60mm sieved product was used as test sample B, and they were subjected to dry magnetic separation test by a bulk magnetic separator. The test procedure is shown in Figure 1, and the test results are shown in Table 1.
Figure 1 -60mm mixed ore waste rock dry magnetic separation test process
Table 1 - Dry magnetic separation test results of -60mm mixed ore waste rock
Sample
Particle size / mm
Yield/%
Magnetic induction intensity / mT
Ore grade /%
Ore work yield /%
A
-30
61.47
200
280
29.13
25.32
9.23
7.87
B
30~60
35.53
200
280
20.52
22.43
7.84
6.21
It can be seen from Table 1 that for the test sample A with a particle size of -30 mm, a large dry magnetic separator with a magnetic induction strength of 200 mT is used to recover the ore, and the ore grade can reach 29.13%, which is in accordance with the ore grade requirement of the ore dressing, and the ore operation yield. The yield of 9.23% and the -60mm mixed ore waste rock was 5.67%. For the test sample A, the large dry magnetic separator with magnetic induction intensity of 280mT was used to recover the ore. The ore grade was only 25.32%, which did not reach the concentrator. The grade requirements for the ore are selected. For the test sample B with a particle size of 30-60 mm, respectively, the test sample B with magnetic induction intensity of 30-60 mm was used to recover ore with a large dry magnetic separator with magnetic induction of 200 mT and 280 mT, and the ore grades were only 20.52% and 22.43 respectively. %, did not meet the requirements of the ore selection of ore grades, and further treatment is needed.
The recovered ore with a grade of 30 to 60 mm of 20.52% was further crushed to a size of 30 mm or less as a test sample C by a jaw crusher , and dry magnetic separation was performed using a bulk dry magnetic separator having a magnetic induction of 200 mT. The test procedure is shown in Figure 2, and the test results are shown in Table 2.
Figure 2 Test sample C dry magnetic separation test flow
Table 2 Test sample C test results
Magnetic induction intensity / mT
Ore grade /%
Ore work yield /%
200
28.42
81.09
It can be seen from Table 2 that the recovered ore with a grade of 30-60mm of 20.52% is crushed and then re-selected with a large dry magnetic separator with a magnetic induction of 200mT, which can further discard some of the waste rock and increase the ore grade to 28.42%. , to meet the grade requirements of the ore selected for ore.
Based on the above test results, it can be known that the mixed ore waste rock is divided into two grades of -30mm and 30-60mm, and the -30mm grade is selected by a large dry magnetic separator with a magnetic induction strength of 200mT, and the grade is 29.13%. The qualified ore for the mixed ore waste rock yield of 5.67%; the large dry magnetic separator with the magnetic induction strength of 280mT at the level of 30-60mm discards most of the waste rock, and is broken to -30mm with a magnetic induction of 200mT. The bulk dry magnetic separator is re-selected once, and the qualified ore with a grade of 28.42% and a yield of 2.45% for mixed ore waste can be obtained. The two-part qualified ore has a comprehensive grade of 28.92% and a total yield of 8.12%.
   3. Industrial recycling scheme for iron ore in mixed ore waste rock
According to the test results, it is possible to construct a production line for recovering iron ore from mixed ore waste rock in the lower dumping site of Shantoushan Iron Mine, and also to produce ore products for paving and construction at the same time. The process plan is shown in Figure 3. Show.
Figure 3 Process plan for recycling iron ore in mixed ore waste rock
   Fourth, the conclusion
The annual discharge of mixed ore waste rock in the lower mining area of ​​Shantoushan Iron Mine is about 2 million tons. A production line for recovering iron ore from a large dry magnetic separator is used to reclaim the magnetite ore with an annual grade of about 29%. About 160,000 tons, and annual output of gravel for paving and construction is about 700,000 m 3 , and its annual economic benefit is nearly 25 million yuan.