How to effectively treat the sewage from the concentrator?

The ore dressing wastewater includes the beneficiation process drainage, the tailings pond overflow water and the mine drainage. The ore dressing process drainage is generally transported to the tailings pond together with the tailings slurry, collectively referred to as tailings water; therefore, the ore dressing wastewater treatment is also referred to as tailings water treatment.

The composition of the drainage produced by the ore dressing is related to the composition, grade and selection method of the ore ore. Drainage may exceed national industrial production "waste" emission standards project follows: pH, suspension, cyanides, fluorides, sulfides, chemical oxygen demand and heavy metal ions.

According to the pollutants contained in the wastewater of the concentrator, it can be roughly divided into three types: wastewater containing suspended solids, wastewater containing cyanide and wastewater containing organic ore dressing. However, for the concentrator, no matter the heavy, magnetic or flotation wastewater, the wastewater contains a large amount of suspended solids, and other pollutants are related to the selection method and the ore variety. For example, the flotation plant drainage contains organic ore dressing chemicals, lead and zinc. , tungsten, molybdenum , gold selection plant contains cyanide and other substances.

First, the characteristics and harm of mineral processing wastewater

Dressing wastewater mainly heavy metal ions hazardous substances, various organic and inorganic flotation agent when used in ore flotation, including highly toxic cyanide, cyanide compounds like chromium. The wastewater also contains various insoluble coarse particles and fine particles dispersed impurities. The ore dressing wastewater often contains sulfates, chlorides or hydroxides such as sodium, magnesium and calcium. The acid in the ore dressing wastewater is mainly formed by the mixing of sulfur-containing minerals with water and water.

The pollutants in the ore dressing wastewater mainly include suspended solids, acid and alkali, heavy metals and arsenic , fluorine, mineral processing chemicals, chemical oxygen-consuming substances and other pollutants such as oils, phenols, ammonium, phosphines and the like. The hazards of heavy metals such as copper , lead, zinc, chromium, mercury and arsenic ions and their compounds are well known. The main hazards of other pollutants are as follows:

(1) Suspended matter: Suspended matter in water can occur, such as blocking fish gills, affecting the photosynthesis of algae to interfere with the living conditions of aquatic organisms. If the concentration of suspended solids is too high, it can also cause river siltation, which can cause soil compaction. . If used as domestic water, suspended matter is a substance that makes people feel uncomfortable, and it is a carrier of bacteria and viruses, which is potentially harmful to the human body. Even when heavy metal compounds are present in the suspension, they are released into the water under certain conditions (pH drop of the water body, ionic strength, change in concentration of the organic chelating agent, etc.).

(2) Xanthate: that is, xanthate, which is a pale yellow powder, has a pungent odor and is easily decomposed, and the odor smell valve is 0.005 mg/L. Fish and shrimp in water bodies contaminated with xanthine have an unpleasant smell of yellow medicinal herbs. Xanthate is easily soluble in water, unstable in water, especially under acidic conditions, and its decomposition product CS can be sulfur pollutant. Therefore, the maximum allowable concentration of butylxanthate in ground water in China is 0.005 mg/L, while the concentration of sodium butylxanthate in the former Soviet Union water is 0.001 mg/L.

(3) of black powder: disulfide dihydroxy phosphate as a main component, impurities contained include formic acid, phosphoric acid, cresol sulfur and hydrogen sulfide. It has a dark brown oily liquid, slightly soluble in water, and has a smell of hydrogen sulfide. It is also a source of pollution such as phenol and phosphorus in mineral processing wastewater.

(4) Pine oil: it is 2# flotation oil, the main component is terpene alcohol. Yellow-brown oily transparent liquid, insoluble in water, is a non-toxic dressing agent, but has a loose fragrance, so it can cause changes in the sensory performance of water. Since pine oil is a foaming agent, it is easy to cause unpleasant foam on the water surface.

(5) Cyanide: a highly toxic substance, which enters the human body and is hydrolyzed into hydrocyanic acid by the action of gastric acid and absorbed by the stomach and then enters the blood. Hydrocyanic acid in the blood can bind to the iron ions of cytochrome oxidase to form oxidized high-iron cytochrome acidase, thereby losing the ability to transmit oxygen, causing tissue hypoxia to cause poisoning. However, cyanide can be removed by self-purification in the water body. Therefore, if this property is used to extend the residence time of the ore dressing wastewater in the tailings pond, it can be brought to the discharge standard.

(6) Sulfide: Under normal circumstances, S and HS will affect the hygienic condition of water in water, and generate hydrogen sulfide under acidic conditions. When the content of hydrogen sulfide in water exceeds 0.5mg/L, it is toxic to fish and can detect the odor emitted by it; the hydrogen olfactory valve in the atmosphere is l0mg/m. In addition, low concentrations of CS, which are volatile in water, enter the body through breathing and skin, and long-term exposure can cause poisoning, leading to the neurological disease Charcote carbon disulfide.

Second, the general principles of wastewater treatment in the concentrator:

(1) The tailings pond should be fully utilized for clarification and natural purification.

(2) If the natural precipitation does not meet the discharge requirements, it should be treated with flocculant, chemical or other methods.

(3) If chemical treatment is required, it is advisable to use one medicine as much as possible. If you can't bear, you can use several kinds of medicines according to the pollution situation, but the type of medicine should not be too much.

(4) The chemicals used should be non-toxic, low-toxic, highly efficient or less polluting, inexpensive and readily available. The most commonly used agent for wastewater treatment in a concentrator is lime.

(5) The composition of wastewater should be analyzed and analyzed, and its different properties should be used to ensure waste treatment and comprehensive treatment.

Third, the treatment method of mineral processing wastewater pollutants

(1) Treatment of ore dressing wastewater by coagulation inclined tube sedimentation

The wastewater from the workshop is firstly separated into solid and liquid by a grit chamber, and the grit of the grit chamber is discharged into the tailings field through the unloading gate. The supernatant liquid overflowing from the grit chamber is mixed and then enters the reactor to fully coagulate the reaction, and then flows into the inclined tube precipitator to further remove fine particles and harmful substances, and the sludge of the inclined tube precipitator passes through the valve. Arranged to the tailings sand field. After passing this process, the wastewater reaches the national allowable discharge standard. According to the requirements of environmental protection, the water from the inclined pipe settler enters the clear water tank, and is returned to the workshop with a clean water pump to save water, and the wastewater is closed in a closed circuit to achieve zero discharge.

(2) Coagulation and sedimentation-activated carbon adsorption-reuse process

This method is currently used in the domestic selection of more ore processing wastewater reuse method. Through the research on the ore dressing wastewater of different mines, it is found that different amounts of different agents or the same agent are applied to the same ore dressing wastewater, and the results are different. But their common points are as follows:

1 Condenser effect comparison test: Polyferric sulfate (PFS), mixed aluminum chloride (PAC) and alum were used as coagulation precipitants respectively. The results showed that the use of alum as a coagulant is economical and reasonable, and the optimum dosage is generally Controlled at around 30mg/L.

2 Effect of polyacrylamide PAM on coagulation effect: The addition of PAM further improves the coagulation treatment effect of wastewater, but because it is an organic polymer, the COD value in water rises. In practice, the effect of coagulation treatment is Considering the combination of changes and COD values, the input amount of PAM is generally 0.2 mg/L.

3 The effect of sedimentation time on wastewater: The standing time after coagulation was established to be 30 min.

4 adsorption test: the amount of powdered activated carbon is less than the amount of granular activated carbon, basically in the case of half of it, the same effect can be achieved. At the same time, since the powdered activated carbon easily enters the concentrate and does not accumulate in the water cycle, it is selected as the adsorbent. The optimum amount is generally 50 to 100 mg/L.

5 Flotation test: After the wastewater is coagulated and precipitated, and activated carbon is adsorbed, it can be reused, and has no effect on the beneficiation index. After alum (30mg / L), PAM (0.2mg / L)} Kunming sedimentation, and then purified by powder activated carbon (50 ~ 100rag / L) process, the effluent water quality not only meets the national mine wastewater discharge standards, but also shows that the reuse results show The wastewater treated by the process can not only be reused, but also does not affect the beneficiation index. In the process of beneficiation, the amount of flotation reagent is also reduced, which brings considerable economic benefits to the enterprise. At the same time, due to the reuse of wastewater, the daily consumption of fresh water is reduced. This is more of a social significance for reducing pollution and purifying the environment for water shortage in China. The method has simple process, good effect and broad industrial application prospects.

(III) Comprehensive method for resource utilization of mineral processing wastewater

After a large number of water treatment tests and mineral processing comparison experiments, the professionals have summarized a better solution to solve the ore dressing wastewater. Taking lead-zinc ore as an example, the process flow is shown in Figure 2.

Due to the different water quality of various wastewaters, the regulating tank plays a role in regulating water quality and water volume during the recycling process. The coagulation sedimentation tank enhances the mixing of the coagulant and the waste water, so that the fine particles grow and become a suspended matter which can be removed by precipitation. The reaction tank is used for further deepening of the wastewater, and the defoaming agent is used to react the excess foaming agent in the wastewater to weaken the influence on the flotation index.

Fourth, the tailings pond water treatment technology introduction

The tailings pond is a large-volume sedimentation-storage pond that can be built on a dam, using slopes on slopes, slopes, rivers or flats. A drainage well and a drain pipe are arranged in the pool, or a drainage ditch is opened along the edge, and the tailings water is clarified and purified in the pool and discharged. The suspended solids in the tailings water are stored at the bottom of the tank. The wastewater stays in the pool for at least one night. This method can effectively remove suspended solids in wastewater, and the content of heavy metals and flotation reagents is also reduced. The longer the residence time, the better the treatment.

The overflow water in the tailings pond can be recycled. Re-election, magnetic separation and simple flotation of a single metal ore have low water quality requirements, water recycling rate of up to 80%, or no drainage at all. When the tailings particles are extremely fine and partially colloidal, a coagulant can be added to the tailings water to accelerate the clarification process and improve the treatment effect. If lime is added to the tailings water, 60-70% of the xanthate and black medicine can be removed.

If the supernatant of the tailings pond does not meet the discharge standards, it should be further processed. Commonly used treatment methods are:

1 Removal of heavy metals can be carried out by lime neutralization and calcination dolomite adsorption. To remove 1 mg of copper, 0.81 mg of lime is needed, 1 mg of nickel requires 0.88 mg of lime, and the pH requirement is controlled to be 8.5 or more. Copper and lead ions can be removed by adsorption of calcined dolomite having a particle size of less than 0.1 mm. Removal of 1 mg of copper requires 25 mg of dolomite, and 1 mg of lead requires dolomite 2.5 mg.

2 Removal of flotation agent by ore adsorption method, using lead-zinc ore to adsorb organic flotation agent, removing 1 mg of organic flotation agent requires lead-zinc ore 200 mg. Treatment with activated carbon adsorption is more effective, but expensive.

3 Cyanide-containing wastewater mainly uses chemical oxidation method, such as bleaching powder oxidation method; it can also remove cyanide by ferrous sulfate lime method and lead-zinc ore method, adding 200 grams of ore per gram of cyanide, which can remove simple cyanide by about 90%, or compound cyanide The compound is about 70%. High concentration of cyanide-containing wastewater can recover sodium cyanide. The process of purifying the overflow water of the tailings pond by lead-zinc ore and lime method is shown in the figure.

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