Overview of Sulphuric Acid Plants in India
Sulphuric acid (H2SO4)is an important industrial chemical used to manufacture many intermediate and end products that are used in a wide range of applications. Sulphuric acid is rightly referred to as a universal chemical/ king of chemicals due to its applications as a raw material or processing agent. H2SO4 is categorised as hazardous and toxic under the Manufacture, Storage and Import of Hazardous Chemical Rules, 1989. A sulphuric acid plant, therefore, must abide by the occupier's responsibilities as mentioned in the rules. Although modern acid manufacturing plants are designed with the state of the art facilities in the country where many companies are providing the complete installation of the facility, the occupier of the facility must also ensure proper hazardous waste management in the facility. The occupier also has to obtain specific licences and hazardous waste management authorisation to be able to run the plant in the country legally. Though the production of H2SO4is automated and the production unit requires substantial capital investment, the returns provided by the sulphuric acid plant due to the huge demand for this chemical will soon make the facility churn out a huge profit in a short time.H2SO4is the most produced chemical in the world and is used in almost all major industries like
- Fertilizer Industry
- Pharmaceutical Industry
- Automobile batteries (Lead Acid Batteries)
- Paper bleaching
- Sugar bleaching
- Water treatment
- Sulfonation agents
- Cellulose fibres
- Steel Manufacturing
- Colouring agents
- Amino acid intermediates
- Regeneration of ion exchange resins
Uses of Sulphuric Acid
The largest single sulphuric acid consumer by far is the fertiliser industry. Some of the significant uses of H2SO4 have been given below.
- The industry in which sulphuric acid is incorporated into the final product is the organic sulphonation process, particularly in the manufacturing of detergents. Many pharmaceuticals are also made by the sulphonation process.
- Sulphuric acid is used with phosphate rock in the manufacture of phosphate fertilisers.
- Smaller amounts are used in the production of ammonium and potassium sulphate.
- Sulphuric acid is used in the pulp and paper industry for chlorine dioxide generation, pH adjustments and tail-oil splitting.
- A substantial quantity of H2SO4 is used as an acidic dehydrating agent in organic chemical and petrochemical processes and oil refining.
- In the metal processing industry, H2SO4 is used for pickling and descaling steel, extraction of copper, uranium and vanadium from ores and in non-ferrous metal purification and plating.
- In the inorganic chemical industry, H2SO4 is used to produce titanium dioxide.
- Wood pulping processes also require sulphuric acid. Some textile and fibre like rayon or cellulose manufacturing and leather tanning uses sulphuric acid.
- End uses for H2SO4include water/ effluent treatment, dyestuffs, explosives, plasticisers, silicate for toothpaste, rubbers, edible oils, adhesives, lubricants and making food acids such as lactic acid and citric acid.
The manufacturing process and waste generation in Sulphuric Acid Plant
Liquid sulphur is a product of the desulphurisation of crude oil and natural gas. The starting material for sulphuric acid production is clean and dry SO2. The process starts with gas cleaning and removing H2O (water vapour) by condensation, followed by gas dehydration with sulphuric acid desiccant. The next step is the oxidation of the produced SO2 into SO3. This SO3 is used to make sulphuric acid in the plant.
Hazardous Waste generated by Sulphuric Acid Plant
SO2 and SO3 are the major air emissions in sulphuric acid production. SO2 emissions are emitted because of an incomplete reaction of SO2 into SO3 on the catalyst.
- Sulphur Sludge: Depending upon the purity of sulphur, sulphur sludge is generated in the range of 2 to 5 kg per metric tonne of sulphur used.
- Catalytic Waste: Used catalyst from sulphur plants contains vanadium pentaoxide. Catalytic Waste generated from Sulphuric Acid Plants varies from 0.01 kg/metric tonne to 0.20 kg per metric tonne of sulphuric acid produced.
In Sulphuric Acid Plants, wastewater is produced from high TDS and highly acidic water coming out through spillage or acid leakages. As the plant involves an exothermic reaction, a large amount of heat energy is also generated. Also, the water used in the scrubbing system, used repeatedly after pH correction by using lime or caustic soda, still contains dissolved solids that need to be precipitated.
Noise Pollution: Air blowers, steam turbines and pumps are the major noise pollution-causing factors that must be managed as per the regulations provided by the CPCB
Essential Factors to consider while setting up a sulphuric Acid Plant
CPCB provides the emission levels and the standard operating procedures to be followed by a sulphuric acid plant. The concerned Pollution Control Board (i.e. SPCB/ PCC)can prescribe more stringent standards if conditions demand.
- Acid plants must be constructed and operated in such a way that liquid H2SO4 is not produced in unexpected locations/ equipment etc.
- Appropriate scrubbing technology must be implemented, and scrubbers must be replaced periodically. Also, Scrubbers must have online pH meters with a recording facility.
- For plants having more than one stream or unit at the same location, the combined capacity from all streams/units will apply to all the streams or units for compliance with the norms specified by CPCB.
- The Stack Height of the Sulphuric Acid Plant must be 30 meters or as per the formula:
- H = 14 (Q) 0.3 (here H is the height of the stack, and Q is the quantity of SO2 expected to be released through the stack at 110% of the capacity as per the norms of gaseous emission)
- For H2SO4 Plants having more than one stream or unit at a particular location, the combined capacity of all streams/units must be considered for determining the height of the stack.
- In Sulphuric Acid Plants, where there is a separate stack for the emission of toxic gases from the Scrubbing Unit, the height of this stack must also conform to the norm for the main plant.
Emission Levels: The emission levels of So2 and acid mist set by the CPCB are as follows
Plant Capacity (MTPD)
Acid Mist & SO3 (mg/Nm3)
Load (Kg/MT of 100% concentrated acid production)
Concentration (mg/Nm3 )
Up to 300
Licences and Authorisations required by the Sulphuric Acid Manufacturing Plant
Consent Certificate: Consent NOC is required by the sulphuric acid manufacturing unit before it can start the operation. The application for this licence has to be made to the concerned Pollution Control board that will issue Consent to establish (CTE) and later Consent to Operate (CTO) under the Air Act and the Water Act. The documents required for this NOC are
- Online Application
- Layout Plan
- Schematic diagram of the plant operation
- Water consumption, groundwater level and wastewater details
- land ownership document
- Project Report from certified CA
- Proof of payment of Consent fee
- Environmental Clearance
- List of plant & machinery installed by the unit.
- Monitoring reports for emission or trade effluents from SPCB recognised Laboratories.
- Copy of Clearance from NBWL (if applicable)
- Proof of CTO compliance report in case of renewal
Under the Factories Act 1948, a sulphuric acid manufacturing plant must obtain a licence from its state department. The licence ensures proper and safe working conditions for the workers in the plant. The documents required for a Factory Licence include
- Application form with stipulated fees.
- ID proof of Occupier and Manager.
- NOC /Board Resolution by partners/ directors for the nomination of the occupier.
- Latest electricity (proof of a load of electricity)
- Proof of ownership (rent agreement/ conveyance deed).
- Flow chart of the manufacturing process.
- List of raw materials used.
- List of machinery on the premises.
- Copy of Project Report
Additional licence required to set up Sulphuric Acid Plant
- Hazardous Waste Authorisation/ Tie-up with a TSDF operator
- Environment Clearance
- BIS Certificate
- Fire NOC
- CGWA NOC (for groundwater use)
Market overview and Scope of the Sulphuric Acid Industry
The demand for sulphuric acid was by 2030 due to the increasing consumption of phosphate fertilisers across the country. There is a booming market of this chemical as its demand is projected to reach 24.40 MT by FY2030 at a CAGR of 6.24% until FY2030. Moreover, the growing use of H2SO4 across various industries like the fertiliser industry (i.e. in phosphoric acid production to be used in DAP/ NP/NP manufacturing), Single Super Phosphate, Dye Intermediates and Ammonium Sulfate, Linear Alkyl Benzene Sulfonate etc. is expected to drive the sulphuric acid market during the forecast period. These trends reflect a positive growth pattern in demand for sulphuric acid and, therefore, the need for facilities that produce in an eco-friendly manner.
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