In addition to the above plants that are currently operational, the Haldia complex has had manufacturing experience of speciality chemicals such as fluid-cracking catalyst, abrasive silica, cryolite and detergent zeolite.

Sodium tri-poly phosphate plant
The plant was commissioned in 1979, with an installed capacity of 30,000 TPA. It was revamped in 1996 to upgrade its capacity to 50,000 TPA. The plant has also been suitably modified to be able to handle phosphoric acid from rocks of different origin, without any loss of capacity.

Sulphuric acid plant
This was set up as a 200-TPD plant. It was revamped in 1983 by changing over to DCDA technology, increasing its capacity to 330 TPD. Subsequently, it was further upgraded to increase the capacity to 450 TPD. The sulphuric acid produced here is utilised in the manufacture of phosphoric acid, SSP and DAP/NPK complex. The surplus acid is sold in the merchant market.

Phosphoric acid plant
This plant was commissioned in 1979 with a capacity of 85 TPD. In 1986 it was revamped to 120 TPD by providing balancing facilities. The unique feature of this plant is the total recycling of all liquid effluents through a gypsum pond (with zero discharge of liquid effluents). The plant is now capable of handling a variety of rock phosphates. Phosphoric acid at a concentration of 27per cent P₂O₅ is primarily used for manufacture of STPP. The by-product, gypsum, is sold to be utilised in the manufacture of cement.

Diversification
The DAP plant at Haldia was commissioned in 1986 for the manufacture of 1,53,450 TPA and it was based on the Norsk Hydro Fertilizer (NHF) pressure-neutralisation process. To improve productivity and meet growing market demand, the plant embarked on a continuous improvement journey. This led to an increased production of 2,93,000 in 2002.

Expansion
A substantial expansion of Haldia phosphatic complex was undertaken in 1998-99, which added a DAP/NPK plant, a SSP plant and a sulphuric acid plant to its facilities.

Single super-phosphate plant
A 1,20,000 TPA single super-phosphate plant was set up in Haldia in 1999. Since then the plant's capacity has been upgraded by carrying out process changes.

DAP/NPK complex plant
A new standalone DAP/NPK complex unit of 4,00,000 TPA, with a built-in flexibility to produce NPK grade fertiliser of different grades has been set up based on the INCRO Pipe Reactor technology. The plant was commissioned in 1999 and has been stabilised at its rated capacity.

300-TPD sulphuric acid plant
A new sulphuric acid plant with 300-TPD capacity was commissioned in 1999 to cater to the requirements of the SSP and DAP/NPK plants. The plant is based on the Monsanto DCDA process.