95% of China's energy and 85% of raw materials come from mineral resources. With rapid population expansion and economic development, the demand for mineral resources is growing. At the same time, along with the exploitation and development of the mine, a large amount of tailing water will be produced. Tailings water is the main component in the tailings slurry after solid ore dressing . When the tailings slurry is transported to the tailings pond, it is self-gravity sorted and precipitates the tailings water. Our tailings discharge water in an amount of about 3.6 billion t, most of them without any treatment, direct deposit germanium in the tailings dam.
A copper- molybdenum plant adopts a grinding-mixing flotation-separation separation process. After one rough selection, one sweep and three times, a copper-molybdenum mixed concentrate is obtained, and finally copper-molybdenum separation is performed. The mine is located in arid and rain-free areas, and water resources have always been a bottleneck restricting the development of enterprises. A large amount of tailings water is accumulated in the tailings dam, which makes the water resources more difficult. At the same time, it also occupies a large amount of land, causing serious pollution to the surrounding environment and posing a major threat to people's life and health. Therefore, the study of tailings water treatment and the use of tailings backwater has become a major problem that the concentrator needs to solve urgently.
Tailings water purification refers to the physical and chemical treatment of harmful substances in the ore water, so that the content is reduced to meet the requirements for reuse or discharge. The purification method of tailings water depends on the composition and quantity of harmful substances, the type of drainage system and the requirements for the quality of the return water. The common methods are: 1 natural precipitation. The tailings granules in the tailings slurry are removed using a tailings pond or other sedimentation tank. 2 physical chemical purification. Some harmful substances are removed by using an adsorbent material. 3 chemical purification. Add appropriate amounts of chemicals to promote the conversion of harmful substances into harmless substances.
After the tailings water is purified and returned to the water, it can not only alleviate the contradiction of water shortage in the plant, but also solve the problems of environmental protection and safety. The recycling of tailings water is the focus of wastewater treatment technology at home and abroad. Common methods are: 1 returning water from the concentration pool. In order to save new water consumption, tailwater dewatering facilities such as tailings concentration tanks or inclined plate concentration tanks are often built in or near the plant for tailings dewatering. The tailings sand sinks to the bottom of the concentration tank, and the clarified water overflows from the pool. Return to the factory for reuse. The return water rate of the concentration tank can generally reach 40% to 70%. 2 tail mines back to the water. After the tailings are discharged into the tailings pond, part of the water content in the tailings slurry remains in the voids of the sedimentary tailings. Some of them are naturally clarified in the tailings pond, degrading toxic and harmful substances, and the other part is evaporated in the reservoir. The backwater from the tailings pond is to recover the remaining part of the clarified water for use in the selection plant.
First, the experimental method
The test results of the final tailings water quality of the copper-molybdenum concentrator are shown in Table 1. The tailings water is dark gray with a turbidity of 49.4 and a pH of 13.
Table 1 Water quality component of tailings water / (mg·L -1 )
Cu | Mo | S | Fe | As |
0.0411 | 2.4761 | 538.43 | 0.0364 | <0.01 |
In this paper, the new ore, untreated tailings backwater, treated tailings backwater for ore dressing test, and comparison of ore dressing effect, the ore dressing test process is shown in Figure 1.
Figure 1 Beneficiation test process
Second, the test results
(1) New water test
According to the procedure shown in Figure 1, fresh water was used for the flotation test. The results are shown in Table 2.
Table 2 New water test results
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.28 | 0.54 | 48.32 | 0.25 | 85.52 |
Copper concentrate | 2.03 | 21.75 | 0.08 | 76.35 | 1.01 |
Middle mine 1 | 0.03 | 1.89 | 26.53 | 0.10 | 5.06 |
Middle mine 2 | 0.19 | 13.27 | 4.76 | 4.36 | 5.69 |
Middle mine 3 | 5.25 | 0.347 | 0.011 | 3.15 | 0.38 |
Tailings | 92.22 | 0.099 | 0.0043 | 15.79 | 2.34 |
Raw ore | 100.00 | 0.57 | 0.15 | 100.00 | 100.00 |
(2) Untreated tailings backwater test
Flotation tests were carried out using untreated tailings backwater according to the procedure shown in Figure 1. The results are shown in Table 3.
Table 3 Untreated tailings backwater test results
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.26 | 0.80 | 44.03 | 0.40 | 70.05 |
Copper concentrate | 2.37 | 7.59 | 0.071 | 33.67 | 1.67 |
Middle mine 1 | 0.20 | 8.09 | 4.93 | 3.01 | 6.35 |
Middle mine 2 | 5.20 | 1.06 | 0.24 | 9.86 | 7.15 |
Middle mine 3 | 3.45 | 0.66 | 0.072 | 5.44 | 1.01 |
Tailings | 88.52 | 0.31 | 0.025 | 47.62 | 13.77 |
Raw ore | 100.00 | 0.55 | 0.16 | 100.00 | 100.00 |
As can be seen from Table 3, the untreated tailings backwater slightly reduces the grade and recovery of molybdenum concentrate, and because the untreated tailings backwater contains a large amount of Na 2 S, when the tailings water returns to When used in the process, the copper mineral is inhibited, so qualified copper concentrate cannot be obtained, and the copper concentrate recovery rate is low. This is why the tailings water cannot be returned directly to the process.
(III) Tailrace backwater test after anionic flocculant treatment
The bulk of the anionic flocculant is based on polyacrylamide and the bridging group is an anion. The anionic flocculant was directly added to the tailings water for treatment, and then the treated tailings water was used for the test. The test procedure is shown in Figure 1, and the results are shown in Table 4.
Table 4 Results of tailings backwater test after anionic flocculant treatment
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.31 | 0.72 | 43.14 | 0.36 | 79.05 |
Copper concentrate | 2.14 | 10.09 | 0.061 | 40.01 | 1.28 |
Middle mine 1 | 0.17 | 9.09 | 3.05 | 2.17 | 3.73 |
Middle mine 2 | 4.06 | 1.01 | 0.34 | 7.42 | 7.88 |
Middle mine 3 | 3.58 | 0.36 | 0.041 | 2.01 | 1.02 |
Tailings | 89.74 | 0.31 | 0.015 | 48.03 | 7.04 |
Raw ore | 100.00 | 0.55 | 0.16 | 100.00 | 100.00 |
It can be seen from Table 4 that the grade of molybdenum concentrate decreased after the tailings water treated with anionic flocculant, and the grade and recovery rate of copper concentrate increased slightly. The sorting effect was close to that of untreated tailings. .
(4) Test of tailings backwater after cationic flocculant treatment
The bulk of the cationic flocculant is based on polyacrylamide and the bridging group is a cation. The cationic flocculant was directly added to the tailings water for treatment, and then the treated tailing water was used for the test. The test procedure is shown in Fig. 1, and the results are shown in Table 5.
Table 5 Results of tailings backwater test after cationic flocculant treatment
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.27 | 0.53 | 44.06 | 0.36 | 80.23 |
Copper concentrate | 1.97 | 11.29 | 0.13 | 74.08 | 2.07 |
Middle mine 1 | 0.21 | 9.98 | 3.05 | 3.91 | 10.12 |
Middle mine 2 | 4.37 | 0.97 | 0.044 | 7.18 | 2.81 |
Middle mine 3 | 3.82 | 0.41 | 0.035 | 3.52 | 0.85 |
Tailings | 89.36 | 0.28 | 0.042 | 10.95 | 3.92 |
Raw ore | 100.00 | 0.55 | 0.16 | 100.00 | 100.00 |
It can be seen from Table 5 that the grade and recovery of molybdenum concentrate obtained after the tail water backwater treatment by the most ionic flocculant is not much different from the data obtained from the tailings backwater test after anion treatment. The recovery rate of copper and molybdenum and The grades fluctuated within a small range and the test results were still not satisfactory.
(5) The tailings backwater test after KMG treatment
KMG Kunming Research Institute of Metallurgy of an organic agent, the agent into a polymer main component polysaccharide, non-toxic source of extensive, cheap, and high-molecular flocculant apparently similar, having a bridging effect, the liquid flocculating Suspended matter in. Another important feature of the agent is its ability to adsorb certain substances in the slurry. The direct addition of KMG to the tailings water reduces the pH of the tailings water and eliminates residual sodium sulfide and suspended solids in the liquid. The water quality test results of tailings water treated with KMG are shown in Table 6. The color is light gray, the turbidity is 20, and the pH is 7-8. According to the flow shown in Figure 1, the tailings backwater by KMG treatment was used for flotation test. The results are shown in Table 7.
Table 6 Tailings water composition after KMG treatment / (mg · L -1 )
Cu | Mo | S | Fe | As |
0.0411 | 2.461 | 205.36 | 0.0265 | <0.01 |
Table 7 Results of tailings backwater test after KMG treatment
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.29 | 0.69 | 45.36 | 0.36 | 80.23 |
Copper concentrate | 1.80 | 22.24 | 0.19 | 74.08 | 2.07 |
Middle mine 1 | 0.20 | 10.72 | 8.30 | 3.91 | 10.12 |
Middle mine 2 | 3.10 | 1.27 | 0.15 | 7.18 | 2.81 |
Middle mine 3 | 2.48 | 0.78 | 0.059 | 3.52 | 0.85 |
Tailings | 92.23 | 0.07 | 0.007 | 10.95 | 3.92 |
Raw ore | 100.00 | 0.55 | 0.16 | 100.00 | 100.00 |
The results in Table 7 show that the tailings backwater treated with the water treatment agent KMG is tested, and the obtained molybdenum concentrate and copper concentrate index are better than the tailings return water index treated with anionic or cationic flocculant. The indicators for new water beneficiation are similar. Therefore, KMG can be used to treat tailings water and return to the process.
(6) Closed circuit experiment
The closed-circuit experiment was carried out on the basis of open circuit and closed circuit using KMG-treated tailings backwater. The closed-circuit process is shown in Figure 2, and the results are shown in Table 8.
Figure 2 closed circuit test process
Table 8 Closed circuit test results
product name | Yield/% | grade/% | Recovery rate/% | ||
Cu | Mo | Cu | Mo | ||
Molybdenum concentrate | 0.29 | 48.53 | 0.50 | 90.96 | 0.26 |
Copper concentrate | 2.52 | 0.19 | 19.23 | 0.03 | 88.50 |
Tailings | 97.19 | 0.99 | 0.06 | 9.01 | 11.24 |
Raw ore | 100.00 | 0.15 | 0.54 | 100.00 | 100.00 |
It can be seen from Table 8 that the KMG-treated tailings water is used for closed-circuit test, and the molybdenum concentrate grade is 48.53%, the recovery rate is 90.96%, the copper content is 0.50%, the copper concentrate grade is 19.23%, and the recovery rate is 88.50%. The concentrate contains a satisfactory index of 0.19% molybdenum, which further proves that the tailings water treated by KMG is suitable for returning to the plant for use in research purposes.
Third, the conclusion
(1) A copper-molybdenum plant adopts a grinding-mixing flotation-separation process to obtain a copper-molybdenum mixed concentrate through a coarse-sweeping and three-preparation, and finally a copper-molybdenum separation. The tailings of the plant have high alkalinity and high content of sodium sulfide. If directly returned to use, it will have a certain inhibitory effect on copper minerals. The tailings backwater test showed that the untreated tailings backwater and the tailings backwater test treated with anionic flocculant or cationic flocculant failed to obtain the ideal test results. The KMG-treated tailings backwater test can obtain a good index of molybdenum concentrate grade 45.36%, recovery rate 80.23%, copper content 0.69%, copper concentrate grade 22.24%, recovery rate 74.08%, and molybdenum 0.19%.
(2) The treatment and reuse of tailings wastewater can achieve comprehensive utilization of backwater under lower cost conditions, with high economic and social benefits.
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