Quartz pickling waste liquid treatment Raiders

Pickling is the use of acid-insoluble silica, the acid can dissolve mineral impurities other characteristics, to achieve purification of the mineral quartz, high purity quartz is one of the important step of purification, the actual production process more general use.

Acids commonly used for pickling include sulfuric acid, hydrochloric acid and hydrofluoric acid. A large amount of H+ and F-plasma remain in the pickling waste liquid. If it is directly discharged without treatment, it is likely to cause fluorine pollution, underground pipeline corrosion and groundwater pollution. And other serious consequences.

Recently, environmental storms have continued throughout the country, and there are also many companies that have been shut down, detained or sentenced for privately-discharged quartz pickling waste. How do quartz companies in the existing pickling process deal with pickling waste liquid? The following small series introduces three common quartz pickling waste liquid treatment processes for reference exchange.

1. Neutralization + precipitation process

(1) Pickling waste liquid treatment process

The quartz pickling waste liquid enters the regulating tank through the drainage pipe, and fully adjusts the water quality and water volume of the pickling waste liquid;

The adjusted wastewater is lifted to the acid-base reaction tank by a water pump, and a basic substance (caustic soda, sodium hydrogencarbonate, lime, etc.) is added to the neutralization reaction with the pickling waste liquid, and stirred while being added;

After the acid and alkali are neutralized for a period of time, the upper layer of the reaction tank is free to flow into the sedimentation tank at night, and the water quality is detected after precipitation, and is discharged or recycled after reaching the standard.

(2) Civil construction facilities and related equipment

Comprehensive adjustment pool

1 underground adjustment tank, brick-concrete structure (with epoxy resin anti-corrosion), the pool volume is determined according to the actual situation;

2 sets of sewage lifting pump (1 for 1), made of plastic / 304 stainless steel.

Acid-base reaction tank

1 acid-base reaction tank, brick-concrete structure;

2 sets of dosing pump (adding alkaline liquid neutralizer), made of plastic / 304 stainless steel;

2 sets of matching medicine tanks (adding alkaline solid neutralizing agent), the material is plastic;

2 pH meters, real-time monitoring of pH value;

1 computer, connected to the pH meter monitoring data;

2 sets of mixing motor, supporting related mixing equipment.

Other devices: electronic control box, anti-corrosion pipes, cables, five gold.

Table 1 List of major equipment

2. Neutralization + precipitation + flocculation + pressure filtration dehydration process

(1) Pickling waste liquid treatment process

The pickling wastewater is discharged directly into the regulating tank, and a perforated aeration tube is arranged in the regulating tank to homogenize and mix the wastewater.

The wastewater is lifted from the conditioning tank by the lift pump to the batch tank for a first-stage neutralization reaction to remove most of the pollutants in the wastewater.

The wastewater sludge subjected to the neutralization reaction is settled in the batch treatment tank, and the settled sludge is dehydrated by a plate and frame filter press to remove the solid suspended matter generated by the neutralization reaction.

The wastewater continues to carry out secondary coagulation reaction in the batch tank, completely removing pollutants from the wastewater and ensuring compliance with the discharge.

After the wastewater is subjected to the coagulation reaction, the soluble pollutants are completely removed, and the wastewater is intercepted by the suspended matter in the sand filtration process.

(2) Civil construction facilities and related equipment

The residence time of the pickling wastewater in the adjustment tank should be 2-3 days, and the epoxy resin on the inner wall is preserved. Two sets of self-priming anti-corrosion lifting pumps for regulating tank equipment, one for one, for regulating the improvement of pool wastewater.

Table 2 List of major equipment

3, neutralization + filter press dehydration + multi-stage filtration + reverse osmosis process

(1) Pickling waste liquid treatment process

The quartz pickling wastewater first enters the adjustment sedimentation tank, adding lime water, and adjusting the pH to 8.5~9.5. After a period of reaction, the flocculant is added to coagulate the impurities and sludge in the water to achieve better solid-liquid separation; the separated sludge enters the sludge pool and is dehydrated and transported by a plate and frame filter press.

The supernatant of the sedimentation tank is adjusted by the original water pump to be filtered by the bag filter, and then passed through a quartz sand filter, an activated carbon filter, and then into a security filter, which is pressurized by a high pressure pump and then enters the reverse osmosis membrane group to produce concentrated water. Return to the adjustment sedimentation tank, the product water enters the reuse pool, reuse or discharge.

(2) Civil construction measures and related equipment

Table 3 List of major equipment

4, sewage discharge standards

After treatment, the quartz sand pickling waste liquid needs to reach the "GB8978-1996 Integrated Wastewater Discharge Standard" before it can be discharged.

Table 4 Maximum allowable emission concentration of the first type of pollutants

Unit: mg/L

Table 5 Maximum allowable emission concentration of the second type of pollutants

Unit: mg/L

Table 6 Maximum allowable drainage quota for some industries

5. Outlook

With the continuous improvement of mineral processing technology and equipment, some photoelectric selection (color sorting machine) equipment, superconducting high gradient magnetic separator and new flotation technology are continuously applied to the beneficiation and purification of quartz sand, and enterprises can introduce new ore dressing. Technology and process to replace quartz sand pickling, completely avoid pickling waste liquid from the source. Non-acid washing process for quartz sand is an inevitable way for comprehensive utilization of quartz sand resources.

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