The purification and treatment process of scheelite beneficiation wastewater

Scheelite beneficiation mainly adopts the flotation process that consumes a lot of water. The wastewater contains a large amount of water glass, beneficiation agents and fine-grained ore. The resulting stable colloidal dispersion system is difficult to clarify and reuse. It is a huge waste, pollutes the environment, and also seriously restricts the sustainable development of my country’s scheelite processing enterprises.

A scheelite mine has a daily ore processing capacity of 2,000t, and produces about 8,000m of wastewater every day, and the beneficiation wastewater needs to be reused. The untreated wastewater is directly reused for scheelite beneficiation production. The first-stage roughing recovery rate is 81.6%, and the total scheelite concentrate recovery rate is 70.8%. The production indicators are poor.The scheelite beneficiation process is as follows: crushing, ball milling, sulfide ore flotation, scheelite flotation at room temperature, scheelite heating selection, and tailings re-election. The beneficiation wastewater treated by acid-base combined treatment is reused for gravity separation, and the scheelite beneficiation wastewater treated by acid-base combined with a pressurized dissolved air flotation is reused for grinding and sulfide ore flotation, compared with when tap water is used , the beneficiation index has no effect. However, the amount of water used in grinding, sulfide ore flotation and re-use only accounts for 60% to 70% of the wastewater produced in scheelite beneficiation. The recycling rate of wastewater is relatively low, and the degree of resource utilization is not high.

According to the current situation of purification and resource utilization of mineral processing wastewater at home and abroad, it is extremely difficult and costly to treat mineral processing wastewater to discharge standards. If the use of wastewater is classified according to the water quality grade of the beneficiation wastewater, especially if the beneficiation wastewater is treated and then recycled into the beneficiation section, the wastewater treatment fee can be reduced, water and reagents can be saved, and environmental pollution can also be reduced.

In view of the above problems, this experimental study determines the use of wastewater according to the water quality and beneficiation process characteristics of scheelite beneficiation wastewater, maximizes the reduction of wastewater treatment costs, and saves the consumption of new water and chemicals, so as to achieve technical feasibility, economical and reasonable health, safety and environmental protection. Reasonable unity of reliability.

Materials and methods

1.1 Test equipment

VIS-723 visible spectrophotometer, heated magnetic stirrer, photoelectric analytical balance, QF-O.5 type combined air flotation machine.

1.2 Test material

Lime: chemically pure; tungsten flotation reagent GYW, sulfide ore collector MB, foaming agent DY-1, sodium carbonate and water glass are all provided by the concentrator. The test water sample is the total wastewater sample of the concentrator, and the water quality indicators are shown in Table 1. The ore is primary scheelite, and the properties of the ore are shown in Table 2.

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  1.3 试验方法

The test process is as follows: the untreated mineral processing wastewater is directly applied to the tungsten room temperature flotation section for mineral sorting, and compared with the clear water beneficiation index; the acid-base combined with a pressurized dissolved air flotation treated water is directly reused for grinding And the sulfur separation process, the untreated tailings water is reused in the tungsten normal temperature flotation process to obtain tungsten rough concentrate, and the tungsten rough concentrate is obtained by using tap water to heat the tungsten flotation process. The beneficiation index of tungsten concentrate obtained by clear water is compared; Untreated tailings water, acid-base combined clarified water and clarified water further processed by pressurized dissolved air flotation and tap water are respectively used for tungsten room temperature flotation process, tailings re-election process, grinding process according to the characteristics of beneficiation process. The ore and sulfur beneficiation process and the tungsten heating flotation process form a complete set of scheelite beneficiation wastewater recycling process.

The grade of WO3 adopts potassium thiocyanate differential spectrophotometry.

Test results and discussion

2.1 Influence of untreated tailings water on tungsten room temperature flotation

The untreated tailings water also contains foaming agent DY-1, sulfide ore collector MB and tungsten flotation agent GYW. The scheelite beneficiation process is to first carry out the flotation of sulfide ore, and then carry out the flotation of scheelite. The remaining foaming agent DY-1 and sulfide ore collector MB in the wastewater have no effect on the subsequent tungsten selection, while GYW is the flotation agent for tungsten selection. Therefore, the untreated tailings water can be directly recycled for use in Tungsten in the normal temperature flotation process. Adjust the chemical system and directly recycle the tailings water for tungsten room temperature flotation. The test indicators are shown in Table 3.

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It can be seen from Table 3 that the untreated wastewater and tap water are used for beneficiation respectively, and the WO3 grade of the tailings is the same, both of which are 0.05%. , the tailings water is directly reused in the beneficiation test, which has little effect on the beneficiation index. In addition, the tailings water is directly recycled for tungsten flotation at room temperature, and the tungsten agent is only 400g/t, which is two-thirds of the 600g/t tungsten agent in clean water.

The untreated ore dressing wastewater can be directly reused for tungsten room temperature flotation, which not only reduces the amount of wastewater treatment, reduces the cost of wastewater treatment, but also reduces the use of chemicals.

2.2 Influence of the use of backwater on the selection of tungsten heating

The acid-base combined use ~ pressurized dissolved air flotation treatment water is directly reused in the grinding and sulfur separation process, the untreated tailings water is reused in the tungsten room temperature flotation process, and the heating flotation tungsten process uses tap water . The tungsten is flotated with all tap water, the WO3 grade is 66.09%, and the total recovery rate of WO3 is 76.47%; the backwater is used in the stages of grinding, sulfur separation and tungsten room temperature flotation, and the tungsten heating flotation uses tap water, and the WO3 grade is 65.25% , the total recovery rate of WO3 was 75.56%. It can be seen that in grinding, its beneficiation index is not much different from the beneficiation index of full tap water: the WO3 concentrate grade can also reach about 66%, and the WO3 recovery rate is less than 1% lower than that of tap water beneficiation, which has little impact.

2.3 Process flow of recycling wastewater from scheelite beneficiation

The untreated tailings water, acid-base combined clarified water and clarified water further processed by pressurized dissolved air flotation can be reused in the tungsten room temperature flotation process and the heated tailings re-election process respectively according to the characteristics of the beneficiation process. , grinding and sulfur beneficiation process, tungsten heating flotation process and drug dissolving process using clean water, the specific scheme is shown in Figure 1.

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  3、社会与经济效益分析

Using the scheelite processing wastewater treatment process shown in Figure 1, the return water rate is over 90%, and zero discharge of wastewater is realized. Compared with the use of untreated wastewater, the recovery rate of the first stage of roughing has increased from 81.6% to more than 90%, the total scheelite concentrate recovery rate has increased from 70.8% to about 76%, and the recovery rate has increased by about 5%. The production of WO3 (65%) concentrate is about 140t, calculated at 80,000 yuan per ton of concentrate, and the annual output value is increased by nearly 11.2 million yuan.

Due to the large amount of flotation reagents remaining in the beneficiation wastewater, after the beneficiation plant uses the return water for production, the consumption of the reagents is significantly reduced, as shown in Table 4. According to the treatment volume of 2000t/d and the annual production of 300d, the annual cost of reagents can be saved. 2.388 million yuan.

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4 Conclusion

According to the characteristics of beneficiation process, combined with the water quality of beneficiation wastewater, this study reuses water of different quality in the beneficiation process. Through chemical adjustment, the beneficiation index is not affected, and the complete recycling of wastewater is realized.

Using this process can not only save a lot of valuable water resources, save chemicals and reduce costs, but also achieve zero discharge of sewage from scheelite processing enterprises, with significant economic and social benefits.

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