Sodium Metabisulfite Na2S2O5

Short Description:

Sodium Metabisulfite is white or yellow crystalline powder or small crystal, with strong odor of SO2, specific gravity of 1.4, soluble in water, the aqueous solution is acidic, contact with strong acid will release SO2 and generate corresponding salts, long time in the air, it will be oxidized to na2s2o6, so the product can not survive for a long time. When the temperature is higher than 150 ℃, SO2 will be decomposed.Sodium Metabisulfite is turned into a powder and is then used in a wide variety of uses from preservatives to water treatment. Wit-stone carries all forms and grades of Sodium Metabisulfite.

Product Detail

Product Tags

Product Description

Sodium Metabisulfite is white or yellow crystalline powder or small crystal, with strong odor of SO2, specific gravity of 1.4, soluble in water, the aqueous solution is acidic, contact with strong acid will release SO2 and generate corresponding salts, long time in the air, it will be oxidized to na2s2o6, so the product can not survive for a long time. When the temperature is higher than 150 ℃, SO2 will be decomposed.Sodium Metabisulfite is turned into a powder and is then used in a wide variety of uses from preservatives to water treatment. Wit-stone carries all forms and grades of Sodium Metabisulfite.


Chinese standard

Company standard

Main content(Na2S2O5)



Fe(As content Fe)




Pass test


Heavy metal content (Pb)



Arsenic content (As)



Molecular Formula :Na2S2O5
Molecular Weight: 190.10
Appearance:  white crystal powder
Packing: plastic bag
Net weight: 25, 50, 1000 kilograms per bag or according to demands from customers



Used in the treatment of wastewater .Eliminate excess oxygen in wastewaterand pipelines; Clean water pipes indesalination plants because it is anantimicrobial agent.


Used in the printing and dyeing industrybleachingagent in theasmanufacture of pulp, cotton and wool,etc.


Used in the pharmaceutical industry asan antioxidant additive in injectableagent indrugs and as a reducingmedicine


Leather industry: It can make leather soft, well-developed, tough water proof, wear-ability Chemical. 


Used as an ore-dressing agent for mines.Industry Used for manufacturing hydrochloride hydroxylamine and etc.


Food industry: used as preservative, antioxidant, flour improver

Competitive Edge

At present, our company has successfully achieved a stable whiteness value of 85 and above through technical transformation of the sodium metabisulfite production line, while some enterprises have also adopted similar sodium metabisulfite production process, but the whiteness value of their products cannot exceed 80. Based on the analysis of the production process, combined with the characteristics of sodium pyrosulfite production process, the focus of technical transformation is to control the amount of iron in the feed gas, that is, take reasonable measures to remove iron in the feed gas purification stage. The expert group proposed the following technical improvement measures to improve the whiteness of the product:

1. Adjust the process parameters of washing water

The cold water tower and the packed tower are combined in series. Before the technical transformation, the washing water system of the cold water tower and the washing condensate system of the packed tower are in parallel, which weakens the concentration gradient advantage of the washing water. After the technical transformation, the water system of the washing water of the cooling tower and the washing condensate of the packing tower is designed as a cascade mode, which increases the comprehensive mass transfer gradient and strengthens the mass transfer efficiency.

2. Change the liquid discharge mode of packed tower

Change the excess washing liquid in the packed tower from continuous discharge to intermittent discharge. Before the technical transformation, the condensed water separated from the feed gas will be concentrated in the packed tower. With the continuous replenishment of fresh water to the packed tower, the washing liquid in the packed tower will continue to increase. Therefore, the measure of continuously discharging excess washing liquid is taken to maintain the dynamic balance of the liquid level in the tower. After the technical transformation, the packing tower adopts intermittent drainage, which can effectively reduce the weighted salt content of the scrubbing liquid in the tower and improve the comprehensive absorption rate of the feed gas. The specific implementation method is as follows: after each discharge of liquid from the packing tower, the PLC control will automatically open the fresh water make-up valve of the packing tower to quickly make up water for the packing tower, and stop the fresh water replenishment after reaching the set level. Its effect is to effectively dilute the salt concentration of the washing liquid in the packed tower. With the continuous enrichment of the condensate in the feed gas in the packed tower, the liquid level of the packed tower will continue to rise. When the liquid level reaches the liquid discharge level, the PLC will control the repeated liquid discharge and the repeated fresh water replenishment.

3 Dismantled foam scrubber

Before the technical transformation, the resistance of the foam scrubber was too high, resulting in an increase in the air leakage rate of the system, which significantly reduced the SO concentration in the feed gas. In addition, when the feed gas came out of the foam scrubber, the entrainment of liquid foam was large, and the impurity content in the liquid foam was high, which reduced the purification efficiency of the subsequent purification system, and the comprehensive impurity removal capacity was weak. From the perspective of comprehensive benefits, the foam scrubber was removed during the technical transformation, and the water circulation path of the chiller scrubber was changed to improve the impurity removal capacity of the purification system.

4.Implementation effect

After the technical transformation of the whole line: the clarity of the packing tower washing water and its subsequent washing solution has been significantly improved, from black to light yellow-green, the product( sodium metabisulfite ) whiteness has increased from 73 to 79 to more than 82, and the proportion of the finished product whiteness above 83 has increased from 0 to more than 20%, and its iron content has decreased by nearly 40%, which initially meets the end customer's requirements for the whiteness quality of sodium metabisulfite.

Related Reading

1.Two production processes of sodium pyrosulfite: dry process and wet process:

1. Dry process :  stir the soda ash and water evenly according to a certain molar ratio, and put them into the reactor when the Na2CO3. nH2O generated is in the form of blocks, keep a certain gap between the blocks, and then add SO2 until the reaction is finished, take out the blocks, and crush them to get the finished product.

2. Wet process :  add a certain amount of soda ash into the sodium bisulfite solution to make it form a suspension of sodium bisulfite, and then add SO2 to form sodium pyrosulfite crystals, which are centrifuged and dried to obtain the finished product.


2.Traditional wet process of sodium pyrosulfite with sulfur as raw material

First, crush the sulfur into powder, and send compressed air into the combustion furnace at 600~800 ℃ for combustion. The amount of air added is about twice the theoretical amount, and the concentration of SO2 in the gas is 10~13. After cooling, dust removal and filtration, sublimated sulfur and other impurities are removed, and the gas temperature is reduced to 0 ℃, left to right, and then sent to the series reactor

Slowly add mother liquor and soda ash solution to the third reactor for neutralization reaction. The reaction formula is as follows:

2NaHSO4+ Na2CO3→ 2 Na2SO4+ CO2+ H2O

The generated sodium sulfite suspension is passed through the second and first stage reactors in turn, and then absorbed and reacted with SO2 to generate sodium pyrosulfite crystal

3.Introduction to Sodium Metabisulfite in application of metal mineral processing

Sodium Metabisulfite is widely used for mining industry. Methods of mineral processing are as follows:

Gravity | Magnetic separation | Electric selection |  Flotation | chemical selction |  Photoelectric election |  Friction selection  | Hand picking

Flotation: Flotation is the technique of separating useful minerals from the ore, based on the physical and chemical properties of mineral particles. Almost all of the ore can be used in flotation separation.

Flotation reagents commonly used in flotation: collector, foaming agent, modifier. Among them, the modifier also includes the inhibitor, activator, pH adjusting agent, dispersing agent, flocculant, etc..

Catching agent: Catching agent is flotation reagents that changes hydrophobicity of mineral surface, makes planktonic mineral particle adhere to bubble. Xanthate, black powder is anionic collector.

Flotation of lead and zinc ores

Galena (i.e. PBS) is a relatively common mineral, it is a kind of sulfide. Xanthate and black powder are commonly used as catching agent (potassium dichromate is an effective inhibitor).

Sphalerite (ZnS)   chemical composition is sulfide minerals such as ZnS, Crystals. 

The catching capacity of short chain alkyl xanthate on sphalerite is weak or not available. ZnS or Marmatite without activation can be selected only by long chain type xanthate.

In the next period of time, the applications of xanthate catching agents will continue to occupy the dominant position. In order to adapt to the demand of increasingly complex Sphalerite flotation, the combination of pharmacy is imperative, it is also an effective way to fully tap the potential of traditional medicine.

 The main flotation inhibitor are as follows:

1.  Lime (CaO) has strong water absorption, acted with water to produce hydrated lime Ca(OH)2. Lime is used to improve pH of the pulp, inhibit of iron sulfide minerals. In the sulfide copper, lead, zinc ore, often associated with sulfided iron ore.  

2. Cyanide (KCN, NaCN) is an effective inhibitor for the separation of lead and zinc. In alkaline pulp, CN concentration increases, which is in favor of inhibition. 

3. The sterling of Zinc Sulfate is white crystal, soluble in water, is the inhibitor of sphalerite, usually in the alkaline pulp it has effect of inhibition.

4. The key that plays inhibition roles in sulfite, sulfite, SO2 is mainly HSO3-.  Sulfur dioxide and sub sulfuric acid (salt) are mainly used in inhibition of Pyrite and sphalerite. Weak acid mine pulp made of lime from Sulfur dioxide (pH=5~7), or use Sulfur dioxide, zinc sulfate, ferrous sulfate and ferric sulfate together as inhibitor. Thus galena, pyrite, sphalerite are inhibited. The inhibited sphalerite can be activated by small amount of copper sulfate. Also can use Sodium thiosulfate, sodium metabisulfite to replace sulfite, to inhibit sphalerite and iron pyrites (commonly known as FeS2). 


Buyer's Guide


It should be stored in a cool and dry warehouse. The package shall be sealed to prevent air oxidation. Pay attention to moisture. It shall be protected from rain and sunlight during transportation. It is strictly prohibited to store and transport together with acids, oxidants and harmful and toxic substances. This product should not be stored for a long time. Handle with care during loading and unloading to prevent package breakage. In case of fire, water and various fire extinguishers can be used to put out the fire.


Packed in plastic woven bags lined with polyethylene plastic bags, each bag has a net weight of 25kg or 50kg. 1. Sodium metabisulfite is packed in plastic woven bags or barrels, lined with plastic bags, with a net weight of 25 or 50kg; 1100 kg net heavy packing bag.

2. The product shall be protected from damage, moisture and heat deterioration during transportation and storage. It is forbidden to coexist with oxidant and acid;

3. The storage period of this product ( Sodium metabisulfite ) is 6 months from the date of production.


Support various modes of transportation, welcome to contact us for consultation.


Any port in China.


Q:What's your delivery time?

A: Usually we will arrange the shipment in 7 -15 days.

Q:How about the packing?

A: Usually we provide the packing as 50 kg / bag or1000kg/bags Of course, if you have special requirements on them, we will according to you.

Q:How do you confirm the product quality?

A:First, we have clean and sanitary production workshop and analysis room.

Second, our workers change into dust-free clothes at work, which are sterilized every day.

Third, Our production workshop provides complete equipment to ensure the hygiene of the production process.

You can contact us to learn more about our factory.

Q:How to confirm the product quality before placing orders?

A: You can get free samples from us or take our SGS report as reference or arrange SGS before loading.

Q:What is loading port?

A: At any port in China.

Buyer's Feedback

Buyers’ feedback1

I’m glad to meet WIT-STONE, who is really an excellent chemical supplier. Cooperation needs to continue, and trust is built little by little. They have a strict quality control system, which I highly appreciate

After selecting Sodium Metabisulfite suppliers for many times, we resolutely chose WIT-STONE. Integrity, enthusiasm and professionalism have captured our trust again and again

Buyers’ feedback2
Buyers’ feedback

I am a factory from the United States. I will order a lot of Sodium Metabisulfite as an ore-dressing agent for mines .WIT-STONE's service is warm, the quality is consistent, and it is the best choice.

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