1 Overview
Beneficiation plant drainage components and composition of ore ore grade and sorting methods related. 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.
The general principle of wastewater treatment in the concentrator is:
(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.
2. Treatment of suspended solid waste water
1) Natural precipitation
The effluent containing suspended solids has tailings, wet dust collection and flushing of surface water. The tailings water is generally precipitated by a tailings pond, and the wet dust is collected and rinsed with a sedimentation tank or a concentration tank. When the supernatant after solid-liquid separation is used for production or when the water quality meets the discharge standard, it is directly discharged.
2) Adding drug precipitation
Some ore dressing mills have fine grain size or some ore dressing agents, so that the fine tailings are suspended in the tailings water. They cannot be clarified for a long time, and chemical treatment is required. The chemical agent is mostly made of flocculant or lime.
Example: The tailings water of Taolin Concentrator contains water glass and oleic acid. The fine tailings are suspended in water and cannot be clarified for a long time. After adding lime, a better clarifying effect is obtained. The amount of lime added is about 0.3 to 0.5% of the amount of slurry.
3. Cyanide-containing wastewater treatment
Gold, tungsten, molybdenum, lead, zinc and other concentrating plants have cyanide-containing wastewater discharge. The cyanide-containing wastewater in the gold plant is mainly cyanide-depleted liquid, and the cyanide content is high, generally above 200 mg/l, up to 2000 mg/l. The cyanide-containing wastewater of tungsten, molybdenum, lead and zinc is mainly concentrated and dehydrated drainage of concentrate, and the fluorine content is generally low, ranging from 30 to 100 mg/l. The tailings water contains less cyanide, generally less than 20 mg/l. It is recovered and treated according to the amount of cyanide in the wastewater.
1) Recycling method
Generally used for wastewater containing high cyanide content.
Sulfuric acid is added to the cyanide-containing waste water to generate hydrogen cyanide gas in the generating tower, and then the hydrogen cyanide gas is sent to the absorption tower, and is contacted with the sodium hydroxide solution to form a sodium cyanide solution. Used back to production. Generally about 90%, still 10% of the cyanide waste water discharged with the column occur, adding milk of lime required to adjust the pH to 9 to 10, the precipitate was thickener underflow hydrogen-containing oxide, copper chloride recovery occurs by column After the filter press is dehydrated by pressure filtration, copper and other metals are recovered, and the supernatant is further added with bleaching powder to remove cyanide. When the ratio of drug to CN:Cl=1:9～13, the amount of cyanide can reach the national “three wastes†emission standard.
Example: a gold mine cyanide solution in Shandong, pH=12, cyanide containing 1200-2000 mg/l, copper 300-500 mg/l, zinc 230 mg/l, thiocyanide 800 mg/l, recovered by recycling Sodium cyanide is used in production. The system processing capacity is 50 mg / liter, and its main technical and economic indicators are as follows:
Sulfuric acid dosage: 6 kg / m 3 wastewater.
Sodium hydroxide dosage: NaOH: CN = 1:1.
Bleaching powder dosage: 1.7 ~ 3.2 kg / m 3 wastewater.
Daily recovery of sodium cyanide: 50 to 90 kg.
Daily copper recovery: 13 to 21 kg.
Treatment of sodium cyanide value per cubic meter of lean liquid: 9 yuan
Processing the cost per cubic meter of lean liquid: 6 yuan
Dealing with the profit per cubic meter of lean liquid: 3 yuan
The treated drainage index is in line with the national industrial “three wastes†emission standards.
2) Processing
Generally used for wastewater with low cyanide content. Many treatment methods, methods with a basic chloride, ferrous sulfate a lime method, stripping method, adsorption method, an electrolytic method or the like. Among them, the ferrous sulfate-lime method and the stripping method have low treatment efficiency, and the treated effluent does not reach the national industrial “three wastes†discharge standard, and is easy to cause secondary pollution. The treatment of the electrolysis method and the adsorption method is expensive, and the alkaline chlorination method is a commonly used treatment method. In addition, natural purification has a certain effect on the treatment of cyanide-containing wastewater.
A alkaline chlorination
Add lime milk to the cyanide-containing wastewater to maintain the pH between 8.5 and 11 l, add bleaching powder or liquid chlorine, and oxidize cyanide to carbon dioxide and nitrogen.
The drug consumption is generally CN:Cl:CaO=l:6.83:4.31
Example: The discharge of cyanide lean liquid from a gold ore plant is 35 m 3 / day, and its composition is listed in Table 31.4.2. Treated by alkaline chlorination, the chlorine consumption per metre of exhaust gas is 6.5 kg, and the lime consumption is 22 kg. The amount of cyanide in the water after treatment was 0.34 mg/liter, and the pH was 8. Meet the national industrial "three wastes" emission standards.
B natural purification
The effect of natural purification is related to factors such as ambient temperature, duration and air contact conditions.
4. Organic mineral processing pharmacy wastewater treatment
The nature of organic mineral processing wastewater is related to the type of pesticide contained in the water. When the water contains a small amount of xanthate, black medicine (such as: xanthate content 0.05 mg / liter), pine root oil, can make people smell bad smell, can produce a disgusting foam on the water surface.
1) Natural purification
The treatment effect of natural purification is related to factors such as time and temperature. The natural purification effect of organic ore dressing agent for tailings water in Daye Concentrator is listed in Table 31.4.4 and Table 31.4.5.
2) Chemical method
Adding chemicals such as lime milk and bleaching powder, the effects are listed in Table 31.4.6.
3) Adsorption method
Adsorption with lead-zinc ore or activated carbon:
A lead-zinc ore adsorption
Lead-zinc ore has a good purifying effect on xanthate and pine root oil, but the treatment effect on black medicine is poor. The black drug removal rate is about 80%.
The ore powder that has been crushed to 0.10 to 0.15 mm, mixed with waste water, and treated, is returned to the ball mill . 200 mg of lead-zinc ore powder is required for each 1 mg of organic agent.
B activated carbon adsorption
The use of activated carbon to adsorb xanthate and pine root oil is better.
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