Overview of Nitric Acid Plants in India

Nitric acid (HNO₃) is the most widely used inorganic chemical in the world today. Nitric acid is of great commercial importance as it is needed in large amounts to manufacture explosives, fertilizers, dyes, drugs etc. It is an essential chemical for pharmaceutical and chemical industries like polymers & plastics items, explosives, dyestuff, fertilizers and other critical organic nitro compounds. There are three major forms of nitric acid, i.e. dilute nitric acid (DNA), which is around 60 %w/w strong nitric acid (SNA) with 64%, 68%, and 72%. These are used in multiple industries as per the strength of the acid. The most considerable amount of acid being manufactured is concentrated nitric acid (CNA), a high-strength acid that is 98-99% w/w.Concentrated nitric acid is required to produce chemicals like isocyanates and nitrobenzene, commonly used as the initial materials in various chemicals. HNO3 for industrial application is obtained as a weak acid solution at a concentration of about 65% -67% w/w. The plant design is also, therefore, based on the strength of the acid that is being manufactured. The process used in nitric Acid plant manufacturing are

• Mono Medium Pressure Process
• Mono high-Pressure Process
• Dual Pressure Process

New-age Production facilities in Nitric Acid Manufacturing

Nitric acid plants have two significant concerns, reducing energy consumption and reducing emissions. New-age technology has made the manufacturing process more efficient by dealing with these two issues. While new plants are adopting these energy-efficient methods, existing plants are upgrading their infrastructure and environmental controls more effectively. However, both these actions require environmental clearance and permission from the respective state government. An energy-efficient nitric acid plant is based on the magnesium nitrate route and existing plants can also be upgraded to include this efficient process. These plants have advantages like lower maintenance/ repair costs and are a significant step towards sustainability. Newly developed techniques are designed to eliminate the hazardous chemicals generation, storage and handling (due to the elimination of weak sulphuric acid). The process of production of nitric acid (Ostwald process) has been described below.

Step 1:Ammonia combustion: Ammonia is sent for combustion in the presence of hot air, and a platinum/rhodium catalyst creates nitric oxide (NO).

Step 2: Oxidation of the NO to create nitrogen dioxide (NO2). The NO from the above stage is cooled and compressed as it travels into the absorption tower. The cooling process produces nitrogen dioxide and releases heat, which is usually recycled in other plant operations.

Step 3: Absorption of the NO2 in water to form nitric acid: This dilute solution is dissolved in water, and nitric acid is obtained. The further reaction forms small quantities of NO that combine with ambient oxygen to create NO2 again, and the reaction continues.

Waste Management in Nitric Acid Plants

When starting any chemical manufacturing plant, it is crucial to research the process and technologies popularly used and choose the one with the most negligible environmental impact. This is why proper waste management in a nitric acid plant is required, as the acid manufacturing unit generates hazardous industrial waste and other waste. Like any other acid manufacturing plant, a nitric acid manufacturing plant releases solid waste, waste water and toxic gaseous fumes that must be treated with a series of pollution control mechanisms per the guidelines of the environmental laws and applicable rules to them. This can be a tedious and time-consuming step and usually requires assistance from experts in the industry that can streamline and manage legal formalities.

Solid Waste

• Spent Catalyst after the scrubbing air emission must be recycled only through recycling by an authorised recycler.
• The municipal solid waste generation at the plant area and township is being segregated into biodegradable waste and recyclable waste.
• Recyclable waste must be sold off to authorized vendors, while other cleaning materials must be collected, stored and transported to an incinerator for disposal.
• Other discarded waste (containers, drums etc.) should be discarded through a TSDF.

Wastewater

Chemical sludge from wastewater treatment from ETP in a Nitric Acid Plant

must be removed and disposed of through TSDF or co-processing in cement plants.

Air Emission

The manufacturing of nitric acid leads to the formation of nitric oxide, nitrous oxide and nitrogen dioxide. Some of these agreement house gases that must be trapped through air scrubbers to avoid the emission of such gases that causes global warming.

Noise Pollution

Noise management in the nitric acid plant is also required due to the operation of machines like blowers, EDG sets, vacuum pumps, dryers, process pumps, compressors, etc., which generate noise. These machines usually have inbuilt noise control measures or are provided with an acoustic enclosure to reduce the noise.

Legalities in setting up a Nitric Acid Plant

Modern CNA, DNA or SNA plants are designed to carry out the three stages in several ways, considering the initial investment costs, feedstock costs, space constraints, and other factors. Besides the technical know-how, skilled workforce and huge capital investment for setting up a nitric Acid Industry, the project proponent will need a series of licences and waste management authorisation such as

Consent Certificate

A Consent to Establish certificate(CTE) is the first stage of the Consent granted by the concerned State Pollution Control Board or the Pollution Control Committee, followed by Consent to operate (CTO) to a Nitric Acid Plant that is categorised as a highly polluting industry. This Pollution NOC, therefore, requires the submission of the following documents.

• GST certificate

• Proof of ownership like a Rent agreement, lease documents etc.
• Certificate of incorporation in the case of company or LLP
• Layout Plan
• Aadhar Card copy and PAN card copy of the applicant
• Electricity bill
• Proof of Pollution Control equipment
• Details of water balance in the area, the requirement of water
• Detailed Project Report,
• Details of raw material, final product and process flow chart
• List of machinery, installed capacity
• Consent Fee
• Environmental Clearance
• Any permission/document required by the Board

Environmental Clearance

Projects are categorised into two broad categories per the EIA notification, based on their production or area as Category A and category B (B1 and B2). Documents required for the purpose are

• Detailed Project Description (like project name, the proposed breakup of area, location, water requirement and waste generation.)
• Site/ Layout plan
• Proof of installed machinery
• Proof of Land Ownership
• ID proof of Signatory
• Quality test Report (wherever applicable)
• Proof of mitigation options adopted

• Proof of Electricity and water connection

Factory’s licence

To establish their manufacturing units, owners must register their businesses under Factories Act. Under this, they are mandated to get a Factory license, which the Chief Inspector of the Labour Commissioner Organisation approves after examining the operation site. For the Factory license, the documents that are required are: -

• Form 1
• Layout plan/site plan
• Aadhaar card
• Name and address of directors
• MOA
• AOA
• Partnership deed
• Account details
• Commencement date
• Payment receipt
• Land deed
• Consent form from SPCB/PCC
• Details of Hazardous and Non-Hazardous waste

Additional Licences required for setting up a Nitric Acid Plant

• Fire NOC
• CGWA NOC
• Explosive licence (if ammonium nitrate is being manufactured)

Market Overview and Scope of Nitric Acid Plants in India

India produces around 2044 KTPA of nitric acid. As nitric acid is a widely used chemical, its demand and consumption is concentrated nitric acid in different grades is used in nitroaromatics, pharmaceuticals, dyes, steel rolling industry, defence and explosive industries. Nitric acid is used in the production of raw materials in some of the vital industries in the country. For instance, it produces ammonium nitrate for fertilizers, making plastics and dyes. It is also used for manufacturing explosives such as nitroglycerin and TNT. CNA is processed into essential intermediate products that produce fibres, lacquers, polyurethane and other base and speciality chemicals.

Manufacturing of Ammonium Nitrate

After obtaining requisite licences, some nitric acid plants can also manufacture ammonium nitrate, a major ingredient for manufacturing explosives. It has been declared as explosive as it has the potential to form explosive mixtures with the addition of fuel. To regulate the use of Ammonium Nitrate, the Ammonium Nitrate Rules, 2012, were framed. Manufacture, conversion, stevedoring and bagging, import-export, possession or transport for sale or use of this chemical is covered under the Rules. For the manufacture of the chemical, an Industrial licence is also required under the IDR Act of 1951. A permit under the Ammonium Nitrate Rules, 2012, is also required. The licensing authority grants a licence under the Ammonium Nitrate Rules, 2012, for five financial years from the date of issuance of the licence.

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