At present, black metal mining waste water treatment processing plant to use more common thickener for natural sedimentation, water purification poor results. For example, a mine will pump 485m 3 /h of wastewater into a natural concentrator with a diameter of 18m for natural precipitation. When the effluent is 425m 3 /h, the overflow concentration is as high as 9996mg/L, which does not meet the requirements of national industrial wastewater discharge standards. . For this reason, some of the common beneficiation plant concentrator fitted with the swash plate, the swash plate converted into a precipitation tank. Although the effect of the sedimentation tank is better, the transformation cost is high, the service life is short, the utility is easy to block, and the maintenance workload is large.

In order to make full use of the original processing equipment of the concentrator, we proposed to change the concentrator with a diameter of 18m into a cyclone flocculation sedimentation tank. After a small test, if the concentration of effluent is controlled below 300mg/L, the treatment load is only 0.3m 3 /m 2 •h, but after adding anionic polyacrylamide in the modified cyclone flocculation sedimentation tank, The treatment load can reach 2m 3 /m 2 •h, that is, the treatment efficiency of the cyclone flocculation sedimentation tank is 7 times that of the ordinary concentrator.

First, the reform of the thickener

The 18m diameter ordinary concentrator was changed into a cyclone flocculation sedimentation tank. It is carried out on the basis of the original ordinary concentrator structure, that is, a cyclone reactor is installed between the center pillar and the truss, and its shape is a truncated cone shape, and a multi-layer swirling guide plate is installed inside (see the figure). 1).

The modified cyclone flocculation sedimentation tank has the following characteristics:

(1) It does not destroy the structure of the original ordinary concentrator, and not only utilizes the original enrichment facility, but also significantly improves the purification efficiency of the wastewater;

(2) adding an anionic polyacrylamide near the inlet of the cyclone flocculation reactor, which can fully utilize the hydrocyclone to carry out the reaction without adding a mechanical agitator;

(3) The swirling flocculation sedimentation tank adopts deep influent water, which greatly shortens the sedimentation distance of the solid particles, so that the medium and coarse particles quickly sink into the compression layer, relatively reducing the concentration of the middle and upper water bodies of the pool body, and forcing fine particles. Enter the upper part of the compression zone with a higher concentration. Due to the collision of dense particles, their energy is greatly reduced, so that a considerable amount of fine particles can not float up, and the underflow concentration is correspondingly increased.

(4) The upper part of the cyclone flocculation reactor has a small diameter, a large diameter at the lower part, and the water flow is continuously variable, which meets the requirements of rapid mixing of the coagulation reaction and slow flocculation. After the water leaves the reactor, there is still a swirling process, which gradually spreads. The “flocs” continue to grow, and the effluent and influent flows in opposite directions. After passing through the concentrated layer, they enter the clear water area and then overflow to the periphery, which is radiated from the upper part of the ordinary thickener. The flow is much better.

Second, flocculant equipment

(1) Static test

The concentration of 300-mg/L of ore dressing wastewater was used as the test solution (pH=8.12), and the poly- iron , poly- aluminum , polyacrylamide, etc. were screened in a 100 mL measuring cylinder and a 40 mm diameter and 2 m high precipitation tube at room temperature. The order of promoting sedimentation effect between various flocculants was evaluated from the sedimentation speed of floc and the turbidity of supernatant. It was confirmed that the anionic polyacrylamide had the best sedimentation effect on the treatment of the beneficiation wastewater. The test curve is shown in Figure 2.

(2) Industrial test

The process flow is shown in Figure 3.

The selected anionic polyacrylamide has a molecular weight of 7 to 8,000,000, a concentration of 0.1%, and an amount of 2.3 g/m 3 . In the actual operation, when the original influent concentration is 21540mg/L, pH=8.05, and the temperature is 6 degrees, after the anionic polyacrylamide is added, the effluent concentration is 33 mg/L, and the removal rate can reach 99.85%.

(3) Dosing equipment

1. Mixing drum: a mixing drum with a diameter of 1.7 m and a volume of 3 m 3 . Consider 4h mixing cycle, one work, one standby.

2. Dosing pump: In order to facilitate the automatic control of the dosage, the XF-101 metering pump was selected. One job, one spare.

3. Storage tank: According to the working condition of the anionic polyacrylamide concentration of 0.1%, the mixing drum can work continuously and can be discharged one by one, the designed volume is 7m 3 .

Third, the treatment effect of the benefits analysis

The operation and monitoring data of this modified equipment for more than 2 years show that the discharge rate of the external drainage after treatment is 100%, the treatment rate is 100%, the purification efficiency is 99.85%, and other water quality indicators are lower than the national water discharge standard; The discharge of tail slurry is controlled from l80m 3 /h to ≤ll5m 3 /h, which increases the bottom discharge rate of the thickener from 15% to 31.89%, and realizes the delivery of all tailings with a YJB～120/25 Mars pump. The control target of the slurry. According to estimates, after the new wastewater treatment system is put into operation, it will be exempted from the excessive sewage discharge fee of about 1.49 million yuan per year, and the exemption from raising the standard collection fee will be about 220,000 yuan. After deducting the operating expenses, the direct economic benefit of the project is about 1,314,400 yuan / year.

Fourth, the conclusion

The use of two-stage ore wastewater is the first in China. The use of this new type of high-efficiency beneficiation wastewater treatment equipment has made China's ferrous metal ore beneficiation wastewater treatment technology reach the domestic advanced level in the 1990s. It has found a technologically advanced, economical and practical technology for many ferrous metal ore dressing plants in China. Efficient wastewater treatment methods.

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