Jamshedpur, Sept 12: Tata Steel strongly believes in the utilisation of solid waste in its production of crude steel.

Over the years, the steel major has made ample use of various waste in its business opportunities and steps have been taken to recycle and reuse the waste.

In 2004-05, Tata Steel generated 700 kg of various waste products (excluding fly ash) for the production of one tonne of crude steel.

Officials said 83.16 per cent of the waste is utilised, either through recycling and reused in own processes, or sold as raw materials to other industries, while the remaining wastes are sent for safe sand filing.

The total production of crude steel in 2004-05 was 4,103,715 tonnes, while 2,887,363 tonnes of waste was produced during the same period. The waste includes blast furnace and linge-donamar (LD), slag and sludge, mill sludge and scale, flue dust, lime fines, dolo dust, undersize limestone, refactory waste, coal tar sludge and biological oxygen demand (BOD) sludge.

About 92.48 per cent of the blast furnace slag generated was used, primarily for cement making.

The facility enhancement of the D and F furnaces resulted into over a 10 per cent increase in slag granulation.

There has been a rise in the sales of air-cooled colloidal slag for road making and other construction job.

There was an over 10 per cent rise in slag granulation in the central slag granulation plant, due to better co-ordination with the blast furnaces and also an over 98 percent consistency level of cast house slag granulation.

As far as the usage of LD slag is concerned, 74.32 per cent was used in 2004-05. These were primarily used as flux material at Tata Metallics Limited, used in sinter production and in mini cement plants.

On the other hand, all the dust and sludge, which originate from various points in the processing of iron and steel was used.

These contain iron, lime and carbon, which enables a large quantity of these wastes to be recycled within the steel works.

Experts in the steel industry pointed out that recycled waste such as mill sludge from rolling processes contains a very high level of oil and is a major source of HC emission from Sinter Plants.

Officials said in Tata Steel, sludge is now mixed with lime and metal to reduce oil quantity in the sludge below seven per cent.

Tata Steel in 2004-05 has also devised various ways and means to dispose of hazardous and bio-medical wastes.

While hazardous wastes like tar sludge and BOD sludge have been entirely utlised in the coke making process, used oil has been used as a direct injection reducing agent in the blast furnaces since it cannot be recycled or reprocessed.